Migraine, comprised of migraine with aura (MA) and migraine without aura (MO), is a painful neurovascular disease, affecting approximately 16% of the general population. It is characterised by a wide variety of symptoms including headache, nausea and vomiting, and photo- and phonophobia. The disorder is complex involving not only multiple genes, but also specific environmental factors, which can induce attacks in genetically predisposed individuals. Hyperhomocysteinaemia is a known risk factor for cerebrovascular, peripheral vascular and coronary heart disease. The Methylenetetrahydrofolate Reductase (MTHFR) enzyme is involved in homocysteine metabolism. Furthermore, it has been reported that a homozygous mutation (677C to T; Ala to Val) in the 5,10-MTHFR gene is associated with an elevation in plasma homocysteine levels (Frosst et al., 1995). This common mutation in the MTHFR gene has recently been associated with migraine with aura in a Japanese cohort (Kowa et al., 2000). The present study was designed to determine the prevalence of the MTHFR C677T mutation in Australian patients with migraine and to determine whether this mutation is associated with the disease in Caucasians. A large case-control study, consisting of 270 patients with migraine (167 with aura and 103 without aura), and 270 normal matched controls was investigated. Genotypic results indicated that the prevalence of the homozygous (T/T) genotype in migraine sufferers (15%) was higher than that of controls (9%) (P = 0.084). Furthermore, the frequency of the mutant (T/T) genotype in individuals with MA (19%) was significantly higher than in controls (9%) (P = 0.006). Interestingly, the risk of MA was ~2.5-fold higher in suffers possessing the homozygous variant (OR = 2.52, CI: 1.42 - 4.47, P = 0.0012). To confirm the MTHFR allelic association with MA, family-based tests were performed in an independent pedigrees group, where only those with MA were considered affected. Results from both the Pedigree Disequilibrium Test (PDT) and Family-Based Association Test (FBAT) analysis revealed slight, although not significant (PDT test, P = 132; and FBAT test, P = 0.390), over-transmission of the mutant allele (T) from parents to affected offspring. However, despite the MTHFR variant having a high heterozygosity (0.48), there were a limited number of informative transmissions for the MTHFR variant in the pedigree group resulting in reduced power for these tests. In conclusion, our results support the trends reported in the Japanese migraine study and suggest that the homozygous 677T gene variant causing mild hyperhomocysteinaemia, is a genetic risk factor for migraine, and indicate that further studies investigating the role of this gene are warranted. Mutations in various ion channel genes are responsible for neurovascular and other neurological disorders. Inherited ion channel mutations or "channelopathies" are increasingly found to be the cause of various neurological disorders in humans. Wittekindt and colleagues (1998) reported that the calcium-activated potassium channel (hKCa3) gene is a good candidate for schizophrenia and bipolar disorder (BD), as well as for other neurological disorders such as migraine. The hKCa3 gene is a neuronal small conductance calcium-activated potassium channel, which contains a polyglutamine tract, encoded by a polymorphic CAG repeat in the gene. The hKCa3 gene encodes a protein of 731 amino acids containing two adjacent polyglutamine sequences in its N-terminal domain separated by 25 amino acids. The C-terminal polyglutamine sequence is highly polymorphic in length (Austin et al., 1999). hKCa3 plays a critical role in determining the firing pattern of neurons via the generation of slow after-polarization pulses and the regulation of intracellular calcium channels (Kohler et al., 1996). Three distinct mutations in the a1 calcium channel gene have been shown to cause SCA-6, episodic ataxia-2 and familial hemiplegic migraine (FHM) (Ophoff et al., 1996). The hKCa3 gene contains a highly polymorphic CAG repeat that was initially mapped (Chandy et al., 1997) to a schizophrenia locus on chromosome 22 (Pulver et al., 1994). Recently Austin et al (1999) re-mapped hKCa3 and found it to reside on chromosome 1q21, a region that has been linked to FHM (Austin et al., 1999), a rare subtype of MA (Ducros et al., 1997; Gardner et al., 1998), and a region recently showing genetic linkage to typical migraine (Lea et al., 2002). The hKCa3 polymorphism results in small variations in polyglutamine number, similar to those that occur in the calcium channel a1a subunit gene (CACNA1A), which is encoded by CAG expansions and thought to cause Spinocerebellar Ataxia Type 6 via loss of channel function (Austin et al., 1999). Given the recent linkage of FHM to the region of chromosome 1q21, to which hKCa3 resides, and also linkage of typical migraine to this region, a large case-control study investigating this hKCa3 CAG marker and consisting of 270 migraine and 270 stringently matched healthy controls was undertaken. Our results indicated that there was no statistically significant difference in allele distributions for this marker between migraine and non-migraine patients (P >0.05). No significant difference in the allelic distribution was observed in the MA or MO groups when compared to controls (P >0.05) and there was no significant difference in CAG repeat length distribution between the migraine group and controls (P = 0.92), or between the MA and MO groups (P = 0.72) collectively. Hence, the CAG repeat in this gene does not show expansion in migraine. Overall, our results provide no genetic evidence to suggest that the hKCa3 CAG repeat polymorphism is involved in migraine aetiology in Australian Caucasians. Thus the involvement of the hKCa3 gene in migraine is not likely, although the hKCa3 gene remains an important candidate for other neurological disorders that may be linked to the 1q21.3 chromosomal region.

published_or_final_version / Pathology / Master / Master of Philosophy

The purpose of this study was to analyze the frequency distributions of alleles at the 3$ sp prime$HVR (hypervariable region) and 5$ sp prime$HVR, two highly polymorphic regions on chromosome 16p. About 300 DNA samples from individuals of East Asian, French Canadian, Greek, Italian, Jewish and Middle Eastern origin were analyzed by hybridization to probes for the 3$ sp prime$HVR and 5$ sp prime$HVR. / The distributions of alleles at both loci are skewed with the long tail towards the larger alleles. The observed heterozygosity at the 3$ sp prime$HVR locus for 281 individuals was 0.91, ranging from 0.85 in the Jewish group to 1.00 among French Canadians and East Asians. Statistical analysis demonstrated significant variation among some of the ethnic groups. / The observed heterozygosity at the 5$ sp prime$HVR locus in 225 individuals was 0.75. Heterozygosity varied from 0.91 in East Asians to 0.61 of Middle Eastern samples studied. 28% of samples also display a RsaI site polymorphism near the 5$ sp prime$HVR locus. / Genetic distance analysis demonstrated that the largest distance at these two loci exists between the Jews and East Asians (D = 0.119). / Both the 3$ sp prime$HVR and the 5$ sp prime$HVR are extremely variable in all the populations studied, and thus will serve as informative markers for chromosome 16p for clinical as well as population studies.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 198-219). / Also available by subscription via World Wide Web / xvii, 219 leaves, bound ill., some col. 29 cm

<p>With easy access to technology to generate expressed sequence tags (ESTs), several groups have sequenced from thousands to several thousands of ESTs. These ESTs benefit from consolidation and organization to deliver significant biological value. A number of EST projects are underway to extract maximum value from fragmented EST resources by constructing gene indices, where all transcripts are partitioned into index classes such that transcripts are put into the same index class if they represent the same gene. Therefore a gene index should ideally represent a non-redundant set of transcripts. Indeed, most gene indices aim to reconstruct the gene complement of a genome and their technological developments are directed at achieving this goal. The South African National Bioinformatics Institute (SANBI), on the other hand, embarked on the development of the sequence alignment and consensus knowledgebase (STACK) database that focused on the detection and visualisation of transcript variation in the context of developmental and pathological states, using all publicly available ESTs. Preliminary work on the STACK project employed an approach of partitioning the EST data into arbitrarily chosen tissue categories as a means of reducing the EST sequences to manageable sizes for subsequent processing. The tissue partitioning provided the template material for developing error-checking tools to analyse the information embedded in the error-laden EST sequences. However, tissue partitioning increases redundancy in the sequence data because one gene can be expressed in multiple tissues, with the result that multiple tissue partitioned transcripts will correspond to the same gene.</p> <p><br /> Therefore, the sequence data represented by each tissue category had to be merged in order to obtain a comprehensive view of expressed transcript variation across all available tissues. The need to consolidate all EST information provided the impetus for developing a STACK human gene index, also referred to as a whole-body index. In this dissertation, I report on the development of a STACK human gene index represented by consensus transcripts where all constituent ESTs sample single or multiple tissues in order to provide the correct development and pathological context for investigating sequence variation. Furthermore, the availability of a human gene index is assessed as a diseasecandidate gene discovery resource. A feasible approach to construction of a whole-body index required the ability to process error-prone EST data in excess of one million sequences (1,198,607 ESTs as of December 1998). In the absence of new clustering algorithms, at that time, we successfully ported D2_CLUSTER, an EST clustering algorithm, to the high performance shared multiprocessor machine, Origin2000. Improvements to the parallelised version of D2_CLUSTER included: (i) ability to cluster sequences on as many as 126 processors. For example, 462000 ESTs were clustered in 31 hours on 126 R10000 MHz processors, Origin2000. (ii) enhanced memory management that allowed for clustering of mRNA sequences as long as 83000 base pairs. (iii) ability to have the input sequence data accessible to all processors, allowing rapid access to the sequences. (iv) a restart module that allowed a job to be restarted if it was interrupted. The successful enhancements to the parallelised version of D2_CLUSTER, as listed above, allowed for the processing of EST datasets in excess of 1 million sequences. An hierarchical approach was adopted where 1,198,607 million ESTs from GenBank release 110 (October 1998) were partitioned into &quot / tissue bins&quot / and each tissue bin was processed through a pipeline that included masking for contaminants, clustering, assembly, assembly analysis and consensus generation. A total of 478,707 consensus transcripts were generated for all the tissue categories and these sequences served as the input data for the generation of the wholebody index sequences. The clustering of all tissue-derived consensus transcripts was followed by the collapse of each consensus sequence to its individual ESTs prior to assembly and whole-body index consensus sequence generation. The hierarchical approach demonstrated a consolidation of the input EST data from 1,198607 ESTs to 69,158 multi-sequence clusters and 162,439 singletons (or individual ESTs). Chromosomal locations were added to 25,793 whole-body index sequences through assignment of genetic markers such as radiation hybrid markers and g&eacute / n&eacute / thon markers. The whole-body index sequences were made available to the research community through a sequence-based search engine (http://ziggy.sanbi.ac.za/~alan/researchINDEX.html).</p>

Orientador: Ricardo Barini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-14T06:51:03Z (GMT). No. of bitstreams: 1 Campanhol_CassiadeLourdes.pdf: 2343395 bytes, checksum: b1e0a2ab84f5be9b1578efc09787fd33 (MD5) Previous issue date: 2009 / Resumo: Introdução: Embora até o momento um efeito fenotípico específico não esteja associado a variantes polimórficas, observa-se uma prevalência mais elevada destas variações entre os indivíduos que apresentam um fenótipo de abortamento recorrente. Por outro lado, pouco se sabe sobre a participação destas variantes entre fetos e neonatos com defeitos congênitos. Materiais e métodos: Foram incluídos neste estudo 2060 resultados de cariótipos, de duas populações de estudo diferentes: 1236 indivíduos provenientes de dois diferentes centros (público e privado) e que haviam sido submetidos ao teste de cariótipo como parte da investigação para a subfertilidade, e 824 fetos e neonatos com defeitos congênitos. Resultados: Para os indivíduos com fenótipo de subfertilidade, nos dois centros, a predominância de variações polimórficas foi de 8,9% e 3,8%. Entre os fetos e neonatos, 37 (4,5%) indivíduos apresentaram variantes polimórficas. Dentre esses pacientes, o achado clínico mais prevalente foi história prévia de perda reprodutiva, apresentada nos progenitores em aproximadamente 54% dos casos. Os defeitos craniofaciais e cardíacos foram descritos em aproximadamente 29% dos casos que apresentaram polimorfismos, seguidos pelos defeitos do sistema nervoso central (21,6%), anomalias ósseas (16,2%), defeitos da parede abdominal (13,5%) e alterações renais (10,8%). Conclusões: Os resultados deste trabalho reforçam a necessidade da adequada divulgação da informação citogenética completa nos resultados de cariótipo, com atenção específica em relação às variantes polimórficas. Assim, prevê-se contribuir para uma melhor compreensão da participação desses polimorfismos em conjuntos de fenótipos específicos. Também reforçam a importância de investigação do cariótipo para uma melhor caracterização do fenótipo de subfertilidade, mesmo na ausência de perda fetal recorrente. / Abstract: Introduction: Although up to now a specific phenotypic effect has not been associated to chromosome polymorphic variants such as inversions and variation in length of heterochromatin segments, it has been widely noticed higher frequencies of these variants among individuals who present a subfertility phenotype. On the other hand little is known about the prevalence of these variants among fetuses and neonates with congenital defects. Materials and methods: A total of 2060 karyotype results were included in this study from 1236 individuals of two different centers who had been submitted to karyotyping as part of the investigation for subfertility and 824 fetuses and neonates with congenital defects. Results: Among individuals with the subfertility phenotype, in the two centers, the prevalence of polymorphic variants was 8.9% and 3.8%. There was no significant difference between the prevalence of polymorphic variants and other abnormalities in individuals with or without previous history of reproductive loss. As for the fetuses and neonates, thirty seven individuals (4.5%) presented polymorphic variants. Among these patients, the most prevalent clinical finding was previous parental history of reproductive loss in around 54% of the cases. Craniofacial and cardiac defects were present in about 29% of them, followed by central nervous system defects (21.6%), bone alterations (16.2%), abdominal wall defects (13.5%) and kidney alterations (10.8%). Conclusions: Our findings reinforce the need to disclose complete information on polymorphic variants in karyotype reports and contribute to a better understanding of the genetic mechanisms that characterize some prevalent congenital defects. Also indicate the usefulness of karyotype results to better characterize the subfertility phenotype even in the absence of recurrent fetal loss. / Universidade Estadual de Campi / Ciencias Biomedicas / Mestre em Tocoginecologia

Philosophiae Doctor - PhD / With easy access to technology to generate expressed sequence tags (ESTs), several groups have sequenced from thousands to several thousands of ESTs. These ESTs benefit from consolidation and organization to deliver significant biological value. A number of EST projects are underway to extract maximum value from fragmented EST resources by constructing gene indices, where all transcripts are partitioned into index classes such that transcripts are put into the same index class if they represent the same gene. Therefore a gene index should ideally represent a non-redundant set of transcripts. Indeed, most gene indices aim to reconstruct the gene complement of a genome and their technological developments are directed at achieving this goal. The South African National Bioinformatics Institute (SANBI), on the other hand, embarked on the development of the sequence alignment and consensus knowledgebase (STACK) database that focused on the detection and visualisation of transcript variation in the context of developmental and pathological states, using all publicly available ESTs. Preliminary work on the STACK project employed an approach of partitioning the EST data into arbitrarily chosen tissue categories as a means of reducing the EST sequences to manageable sizes for subsequent processing. The tissue partitioning provided the template material for developing error-checking tools to analyse the information embedded in the error-laden EST sequences. However, tissue partitioning increases redundancy in the sequence data because one gene can be expressed in multiple tissues, with the result that multiple tissue partitioned transcripts will correspond to the same gene.Therefore, the sequence data represented by each tissue category had to be merged in order to obtain a comprehensive view of expressed transcript variation across all available tissues. The need to consolidate all EST information provided the impetus for developing a STACK human gene index, also referred to as a whole-body index. In this dissertation, I report on the development of a STACK human gene index represented by consensus transcripts where all constituent ESTs sample single or multiple tissues in order to provide the correct development and pathological context for investigating sequence variation. Furthermore, the availability of a human gene index is assessed as a diseasecandidate gene discovery resource. A feasible approach to construction of a whole-body index required the ability to process error-prone EST data in excess of one million sequences (1,198,607 ESTs as of December 1998). In the absence of new clustering algorithms, at that time, we successfully ported D2_CLUSTER, an EST clustering algorithm, to the high performance shared multiprocessor machine, Origin2000. Improvements to the parallelised version of D2_CLUSTER included: (i) ability to cluster sequences on as many as 126 processors. For example, 462000 ESTs were clustered in 31 hours on 126 R10000 MHz processors, Origin2000. (ii) enhanced memory management that allowed for clustering of mRNA sequences as long as 83000 base pairs. (iii) ability to have the input sequence data accessible to all processors, allowing rapid access to the sequences. (iv) a restart module that allowed a job to be restarted if it was interrupted. The successful enhancements to the parallelised version of D2_CLUSTER, as listed above, allowed for the processing of EST datasets in excess of 1 million sequences. An hierarchical approach was adopted where 1,198,607 million ESTs from GenBank release 110 (October 1998) were partitioned into &quot;tissue bins&quot; and each tissue bin was processed through a pipeline that included masking for contaminants, clustering, assembly, assembly analysis and consensus generation. A total of 478,707 consensus transcripts were generated for all the tissue categories and these sequences served as the input data for the generation of the wholebody index sequences. The clustering of all tissue-derived consensus transcripts was followed by the collapse of each consensus sequence to its individual ESTs prior to assembly and whole-body index consensus sequence generation. The hierarchical approach demonstrated a consolidation of the input EST data from 1,198607 ESTs to 69,158 multi-sequence clusters and 162,439 singletons (or individual ESTs). Chromosomal locations were added to 25,793 whole-body index sequences through assignment of genetic markers such as radiation hybrid markers and g&eacute;n&eacute;thon markers. The whole-body index sequences were made available to the research community through a sequence-based search engine (http://ziggy.sanbi.ac.za/~alan/researchINDEX.html). / South Africa

Human response to ionising radiation (IR) shows a wide variation. This is most clearly seen in the radiation-response of cells as measured by frequencies of chromosomal aberrations. Different frequencies of IR-induced aberrations can be conveniently observed in phytohaemagglutin-stimulated peripheral blood T-lymphocytes from both normal individuals and sporadic cancer cases, in either metaphase chromosomes or as micronuclei in the following cell cycle. Metaphase cells show frequent chromatid breaks, defined as chromatid discontinuities or terminal deletions, if irradiated in the G 2 -phase of the cell cycle. It has been shown that the frequency of chromatid breaks in cells from approximately 40% of sporadic breast cancer patients, are significantly higher than in groups of normal individuals. This suggests that elevated radiation-induced chromatid break frequency may be linked with susceptibility to breast cancer. It is known that chromatid breaks are initiated by a double strand break (DSB), but it appears that the two are linked only indirectly as repair kinetics for DSBs and chromatid breaks do not match. Therefore, the underlying causes of the wide variation in frequencies of chromatid breaks in irradiated T-lymphocytes from different normal individuals and from sporadic breast cancer cases are still unclear but it is unlikely to be linked directly to DSB rejoining. My research has focused on the mechanism through which chromatid breaks are formed from initial DSBs. The lack of a direct association suggested that a signalling process might be involved, connecting the initial DSB and resulting chromatid break. The signal model, suggested that the initial DSB is located within a chromatin loop that leads to an intra- or interchromatid rearrangement resulting in incomplete mis-joining of chromatin ends during the decatenation of chromatids during G 2 . It was therefore proposed that topoisomerase II alpha (topo IIα) might be involved, mainly because of its ability to incise DNA and its role in sister chromatid decatenation. During my PhD research I have used a strategy of altering topo II activity or expression and studying whether this alters IR-induced chromatid break frequency. The first approach involved cell lines that varied in topo IIα expression. The frequency of IR-induced chromatid breaks was found to correlate positively with topo IIα expression level, as measured in three different cell lines by immunoblotting, i.e. two cell lines with lower topo IIα expression exhibited lower chromatid break frequency. Topo II activity in these three cell lines was also estimated indirectly by the ability of a topo IIα poison to activate the G 2 /M checkpoint, and this related well with topo IIα expression. A second approach involved ‘knocking down’ topo IIα protein expression by silencing RNA (siRNA). Lowered topo IIα expression was confirmed by immunoblotting and polymerase chain reaction. SiRNA-lowered topo IIα expression correlated with a decreased IR-induced chromatid break frequency. In a third series of experiments cells were treated with ICRF-193, a topo IIα catalytic inhibitor. It was shown that inhibition of topo IIα also significantly reduced IR-induced chromatid breaks. I also showed that lowered chromatid break frequency was not due to cells with high chromatid break frequencies being blocked in G 2 as the mitotic index was not altered significantly in cells with lowered topo IIα expression or activity. These experiments show that topo IIα is involved in IR-induced chromatid break formation. The final experiments reported here attempted to show how topo II might be recruited in the process of forming IR-induced chromatid breaks. Hydrogen peroxide was used as a source of reactive oxygen species (reported to poison topo IIα) and it was shown that topo IIα under these conditions is involved in the entanglement of metaphase chromosomes and formation of chromatin ‘dots’ as well as chromatid breaks. Experiments using atomic force microscopy attempted to confirm these dots as excised chromatin loops. The possible role of topo IIα in both radiation- and hydrogen peroxide-induced primary DNA damage was also tested. It was shown that topo IIα does not affect radiation-induced DSBs, even though it does affect chromatid break frequency. Also, topo IIα does not affect hydrogen peroxide-induced DNA damage at low doses. The results support the idea that topo IIα is involved in the conversion of DSBs to chromatid breaks after both irradiation and treatment with hydrogen peroxide at a low concentrations. I have demonstrated that topo IIα is involved in forming IR-induced chromatid breaks, most likely by converting the initial DSBs into chromosomal aberrations as suggested by the signal model.

Estudamos os cariótipos de espécimes de macacos brasileiros (Platyrrhini, Primates) com técnicas citogenéticas tradicionais e de FISH com as sondas totais dos cromossomos 14, 15 e X humanos e do cromossomo Y de Brachyteles arachnoides obtida por microdissecção cromossômica. Vinte e quatro espécimes de Alouatta guariba clamitans, doze machos e doze fêmeas foram estudados. Para os machos, encontramos um número diplóide de 2n = 49, devido à ausência aparente do cromossomo Y provavelmente decorrente de uma translocação Y-autossomo, e 2n = 46 cromossomos, com variação nas fórmulas cromossômicas com 17, 19, 20, 21 ou 24 cromossomos metacêntricos ou submetacêntricos e 22, 28, 29, 30 ou 32 acrocêntricos. Para as fêmeas, uma variabilidade maior no número diplóide foi observada com 46, 48 e 50 cromossomos e as fórmulas cromossômicas encontradas mostraram 18, 19, 20, 21, 27 ou 28 cromossomos metacêntricos ou submetacêntricos e 18, 19, 27, 30, 31 e 32 acrocêntricos. Os cromossomos X eram submetacêntricos. Pares heteromórficos foram observados. Uma fêmea com 48 cromossomos foi descrita pela primeira vez, este número diplóide só havia sido descrito em um único exemplar macho. A confirmação da subespécie dos indivíduos analisados se deu pela presença do par cromossômico característico de Alouatta guariba clamitans, o par 1, e pela região geográfica de procedência dos exemplares. O sexo dos espécimes também foi confirmado ou mesmo determinado pela análise dos cariótipos. Para Alouatta guariba clamitans, corroboramos a tendência à redução do número diplóide orientada no sentido norte-sul. As grandes diferenças cromossômicas entre as populações do sul e sudeste sugerem que Alouatta guariba clamitans seja representante de duas subespécies ou mesmo de duas espécies separadas, evidenciando a necessidade de uma revisão de sua taxonomia. Analisamos um macho de A. sara em coloração convencional, bandamentos GTG e CGB. O cariótipo era formado por 50 cromossomos, com 16 metacêntricos ou submetacêntricos, 31 acrocêntricos e 3 microcromossomos, dois submetacêntricos e um acrocêntrico. O cromossomo X era submetacêntrico e o cromossomo Y estava aparentemente ausente, provavelmente devido a uma translocação Y-autossomo. Um heteromorfismo foi observado. A heterocromatina estava presente na região pericentromérica dos cromossomos, incluindo os três microcromossomos. Duas fêmeas de Ateles paniscus paniscus foram estudadas em coloração convencional. Os espécimes apresentaram 32 cromossomos, com 30 cromossomos metacêntricos ou submetacêntricos e 2 acrocêntricos. A classificação foi baseada no número diplóide e presença do cromossomo 2 metacêntrico característico desta subespécie. Também analisamos dois machos de Ateles sp. em coloração convencional que apresentaram um número diplóide de 34 cromossomos, agrupados em 32 metacêntricos ou submetacêntricos e 2 acrocêntricos. O cromossomo Y era o menor metacêntrico do complemento. Os cromossomos X dos quatro Ateles analisados eram submetacêntricos. A descrição de pares cromossômicos heteromórficos neste gênero é freqüente. Sugerimos que os indivíduos de Ateles sp. sejam classificados como Ateles paniscus chamek. A diferença no número cromossômico entre os exemplares analisados é devido à presença do par metacêntrico em A. p. paniscus que é resultante da fusão in tandem de dois cromossomos de A. p. chamek. A variabilidade intra e interespecífica observada neste gênero podem ser explicadas por inversões pericêntricas. Estudamos uma fêmea e um macho de Callimico goeldii em coloração convencional. Ambos apresentaram 48 cromossomos agrupados em 28 cromossomos metacêntricos ou submetacêntricos e 18 cromossomos acrocêntricos, além do cromossomo X submetacêntrico e do Y acrocêntrico. Heteromorfismos foram observados. Não encontramos variabilidade no número diplóide e a diferença nas fórmulas cromossômicas é devido à morfologia dos cromossomos sexuais. Três machos e quatro fêmeas de Callithrix sp. foram analisados em coloração convencional e bandamentos GTG e CBG. O número cromossômico encontrado foi de 2n = 46, com 30 autossomos metacêntricos ou submetacêntricos, 14 autossomos acrocêntricos, o cromossomo X submetacêntrico e o cromossomo Y acrocêntrico. Duas fêmea e um macho apresentaram linhagens quiméricas 46,XX/46,XY. Heteromorfismos foram encontrados. A heterocromatina estava presente na região pericentromérica dos cromossomos e em blocos extracentroméricos. Não conseguimos determinar com exatidão a espécie de Callithrix, porém pela fórmula cromossômica e morfologia do cromossomo Y sugerimos que possam ser das espécies C. jacchus, C. penicillata ou C. aurita. O macho de Cebus nigritus estudado em coloração convencional apresentou 54 cromossomos divididos em 20 autossomos metacêntricos ou submetacêntricos e 32 acrocêntricos, além do cromossomo X que é um submetacêntrico e do Y que é um acrocêntrico. Não foram observados heteromorfismos. Levando em consideração as características fenotípicas, semelhanças entre os cromossomos com os cariótipos mostrando a mesma fórmula cromossômica e distribuição geográfica, sugerimos que C. nigritus seja sinônimo de C. vellerosus. Estudamos uma fêmea de Callicebus caligatus em coloração convencional que apresentou 48 cromossomos, com 16 metacêntricos ou submetacêntricos e 32 acrocêntricos. Heteromorfismos foram observados. Também analisamos uma fêmea de Callicebus nigrifrons com a mesma coloração e a classificação foi confirmada pela análise citogenética. Esta fêmea mostrou um número diplóide de 2n = 42, compreendendo 30 autossomos metacêntricos ou submetacêntricos e 12 acrocêntricos. Nenhum heteromorfismo foi observado. Os cromossomos X das duas fêmeas eram submetacêntricos. As duas espécies de Callicebus apresentaram números diplóides e fórmulas cromossômicas diferentes, com um predomínio de cromossomos acrocêntricos em C. caligatus e um predomínio de cromossomos não-acrocêntricos em C. nigrifrons, indicando que a redução do número diplóide foi direcionada por eventos de fusão cromossômica. Estudamos a conservação da associação sintênica HSA 14/15 em praticamente todos os gêneros de macacos do Novo Mundo. O homeólogo ao HSA 14 conservou a sintenia para o cromossomo inteiro enquanto o homeólogo ao HSA 15 está fragmentado. Esta associação favorece a origem monofilética da família Atelidae e da subfamília Callitrichinae. Um padrão 14/15/14 foi observado em Alouatta sara e 15/14/15/14 em Aotus nigriceps, mostrando um alto grau de instabilidade citogenética nesta região em alguns gêneros, estando mais susceptível a quebra e inversão. Relatamos a presença desta associação também em Cacajao melanocephalus, que não havia sido estudado com a técnica de FISH. A presença da associação sintênica HSA 14/15 em todas as espécies e subespécies de macacos do Novo Mundo estudadas indica que esta sintenia é um caractere ancestral, concordando com o provável cariótipo ancestral de Platyrrhini. A pintura com a sonda total do cromossomo X humano em praticamente todos os gêneros de Platyrrhini confirmou a Lei de Ohno, que dita a conservação evolutiva do cromossomo X em mamíferos placentários. A sonda total do cromossomo Y de Brachyteles arachnoides produzida por microdissecção cromossômica mostrou uma homeologia entre o cromossomo Y de todos os gêneros pertencentes à subfamília Atelinae (Ateles belzebuth marginatus, Lagothrix lagothricha e Brachyteles arachnoides). Lagothrix e Brachyteles apresentaram um cromossomo Y acrocêntrico diminuto e Ateles mostrou um cromossomo Y acrocêntrico pequeno, mas não diminuto. Não conseguimos hibridar esta sonda em metáfases de espécimes da subfamília Alouattinae, que junto com a subfamília Atelinae compõem a família Atelidae. O uso de caracteres citogenéticos-moleculares pode proporcionar informações valiosas para a elucidação das relações filogenéticas na subfamília Atelinae. Os nossos dados mostram que o cromossomo Y nesta subfamília compartilha uma história comum, devendo mostrar o mesmo padrão filogenético, corroborando a separação da família Atelidae nas subfamílias Atelinae e Alouattinae. Os diferentes números diplóides e fórmulas cromossômicas observados nesse trabalho indicam a grande variabilidade intra e interespecífica e intrapopulacional existente em Platyrrhini, com uma marcante reorganização no seu genoma, decorrente de processos de inversões pericêntricas, fusões cromossômicas, translocações entre cromossomos e outros rearranjos mais complexos. A análise citogenética em Platyrrhini é importante para a identificação das espécies para uma posterior soltura em região geográfica adequada, para os programas de reprodução em cativeiro aumentando as possibilidades de reprodução ex situ e para a deposição em museus. Também é uma ferramenta importante para a identificação das origens dos espécimes com procedência incerta. Uma maior integração e direcionamento dos dados citogenéticos, morfológicos e moleculares é necessária para o entendimento da variação e definição das taxa de forma mais objetiva. A destruição e fragmentação das florestas, as práticas agrícolas, a caça e a subtração de indivíduos como animais de estimação têm afetado negativamente a sobrevivência dos macacos brasileiros. / We studied the karyotypes of Brazilian monkeys (Platyrrhini, Primates) using both traditional cytogenetic techniques as well as FISH. FISH analysis employed human probes for chromosome 14, 15 and the X chromosome and a probe of the Y chromosome of Brachyteles arachnoides obtained by chromosome microdissection. Twenty-four individuals of Alouatta guariba clamitans were studied, twelve males and twelve females. For males, we found a diploid number of 2n = 49 due to the presumed absence of the Y chromosome probably due to a Y-autosome translocation, and 2n = 46 chromosomes, with 17, 19, 20, 21 or 24 biarmed chromosomes and 22, 28, 29, 30 or 32 acrocentrics. For females, a greater variability in the diploid number was observed with 46, 48 and 50 chromosomes and 18, 19, 20, 21, 27 or 28 biarmed chromosomes and 18, 19, 27, 30, 31 and 32 acrocentrics. The X chromosomes were submetacentric. Heteromorphisms were observed. A female with 48 chromosomes was described for the first time; this diploid number had only been described before for a single male. The subspecies has been confirmed by the presence of a characteristic chromosome pair of Alouatta guariba clamitans, pair 1, and by the geographic origin of the samples. The sex was also confirmed or determined by karyotype analysis. The major chromosomal differences between populations of the south and southeast of Brazil suggest that Alouatta guariba clamitans may be representative of two subspecies or even two separate species, highlighting the need for a taxonomic review. A male of A. sara was studied and we observed a diploid number of 2n = 50 chromosomes, with 16 biarmed, 31 acrocentrics and 3 microchromosomes, two submetacentrics and one acrocentric. The X chromosome was submetacentric and the Y chromosome was presumably missing, probably due to a Y-autosome translocation. A heteromorphism was observed. The heterochromatin was present in the pericentromeric region of chromosomes, including the three microchromosomes. Two females of Ateles paniscus paniscus were studied. The specimens had 32 chromosomes, with 30 biarmed and 2 acrocentrics. A heteromorphism was observed. The classification was based on the diploid number and presence of a metacentric chromosome, pair 2, characteristic of this subspecies. We also analyzed two males of Ateles sp. that showed a diploid number of 34 chromosomes, grouped in 32 biarmed and 2 acrocentrics. The Y chromosome was the smallest metacentric. The X chromosomes were submetacentrics. The description of heteromorphisms in this genus is frequent. We suggest that these two individuals of Ateles sp. are classified as Ateles paniscus chamek. The difference in the diploid number of the specimens is due to the presence of a metacentric in A. p. paniscus that is the result of the in tandem fusion of two chromosomes of A. p. chamek. The variability in this genus can be explained by pericentric inversions. We studied a female and a male of Callimico goeldii. Both had 48 chromosomes grouped in 28 biarmed chromosomes and 18 acrocentrics, plus an X submetacentric chromosome and a Y acrocentric. Heteromorphisms were observed. We observed no variations in the diploid number and all differences are due to the morphology of the sex chromosomes. Three males and four females of Callithrix sp. were studied. The chromosome number was 2n = 46, with 30 biarmed, 14 acrocentrics, a submetacentric X chromosome and an acrocentric Y chromosome. Two females and one male showed 46,XX/46,XY chimerisms. Heteromorphisms were found. The heterochromatin was present in the pericentromeric region and in extracentromeric blocks. We observed no variations in the diploid number and the only differences are due to the morphology of the sex chromosomes. We could not determine the Callithrix species, but the karyotypes suggest C. jacchus, C. penicillata or C. aurita. The Cebus nigritus male studied showed 54 chromosomes grouped in 20 biarmed and 32 acrocentrics, and a submetacentric X chromosome and an acrocentric Y. There were no heteromorphisms. Taking into account the phenotypic characteristics, similarities between chromosomes and geographical distribution, we suggest that C. nigritus is synonymous with C. vellerosus. We studied a female Callicebus caligatus that showed 48 chromosomes, with 16 biarmed and 32 acrocentrics. Heteromorphisms were observed. We also analyzed a female Callicebus nigrifrons, whose taxonomic placement was confirmed by cytogenetic analysis. Its diploid number was 2n = 42, including 30 biarmed and 12 acrocentrics. No heteromorphisms were observed. The X chromosomes were submetacentrics. The two Callicebus species showed different diploid numbers, with a predominance of acrocentric chromosomes in C. caligatus and a predominance of biarmed chromosomes in C. nigrifrons, indicating that the reduction in the diploid number was due to events of chromosomal fusion. We studied the syntenic association HSA 14/15 conservation in almost all genera of Platyrrhini. The HSA 14 homolog retained synteny for the entire chromosome however the HSA 15 homolog was fragmented. The association suggests a monophyletic origin of the Atelidae family and Callitrichinae subfamily. A 14/15/14 pattern was observed in Alouatta sara and a 15/14/15/14 pattern in Aotus nigriceps, showing a high degree of instability in this region in some genera. We report the presence of this association also in Cacajao melanocephalus, who had not been previously studied with FISH technique. The presence of the HSA 14/15 syntenic association in all species and subspecies of Platyrrhini that we studied indicates that this is an ancestral trait, agreeing with Platyrrhini ancestor karyotype. The painting with human X chromosome in almost all genera of Platyrrhini consistent with Ohnos Law, indicating evolutionary conservation of the X chromosome in placental mammals. The signals were found exclusively in the X chromosome homologs. The Y chromosome probe of Brachyteles arachnoides produced by chromosome microdissection showed homology between the Y chromosomes of all genera belonging to the Atelinae subfamily (Ateles belzebuth marginatus, Lagothrix lagothricha and Brachyteles arachnoides). Lagothrix and Brachyteles Y chromosomes are extremely small acrocentrics and the Ateles Y chromosome is small. We could not hybridize this probe in metaphases form Alouatta, which along with the Atelinae genera comprise family Atelidae. The use of molecular-cytogenetic traits can provide valuable information for the elucidation of phylogenetic relationships in tne Atelinae subfamily. Our data show that the Y chromosome in the subfamily Atelinae shares a common history and is consistent with the separation of family Atelidae into the subfamilies Atelinae and Alouattinae. In conclusion our study indicates a great degree of chromosomal varaibility within Platyrrhini and suggests a marked reorganization of the genome within this primate group, due to such processes as pericentric inversions, chromosome fusions, translocations between chromosomes and other complex rearrangements. Cytogenetic analyse in Platyrrhini are important for species identification. Such information can in turn be useful for a variety of conservation and systematic purposes including repatriation of animals in an appropriate geographical region, for captive breeding programs, increasing the chances of ex-situ breeding, and for the deposition of specimens in museums. It is also an important tool for identifying the geographical origins of specimens with uncertain origin. Integration of cytogenetic, morphological and molecular data is necessary for the understanding of variation and definition of the taxa and understanding evolutionary processes at these different levels. Forests destruction and fragmentation, agricultural practices, hunting and subtraction of individuals as pets have negatively affected the survival of Brazilian monkeys.

Estudamos os cariótipos de espécimes de macacos brasileiros (Platyrrhini, Primates) com técnicas citogenéticas tradicionais e de FISH com as sondas totais dos cromossomos 14, 15 e X humanos e do cromossomo Y de Brachyteles arachnoides obtida por microdissecção cromossômica. Vinte e quatro espécimes de Alouatta guariba clamitans, doze machos e doze fêmeas foram estudados. Para os machos, encontramos um número diplóide de 2n = 49, devido à ausência aparente do cromossomo Y provavelmente decorrente de uma translocação Y-autossomo, e 2n = 46 cromossomos, com variação nas fórmulas cromossômicas com 17, 19, 20, 21 ou 24 cromossomos metacêntricos ou submetacêntricos e 22, 28, 29, 30 ou 32 acrocêntricos. Para as fêmeas, uma variabilidade maior no número diplóide foi observada com 46, 48 e 50 cromossomos e as fórmulas cromossômicas encontradas mostraram 18, 19, 20, 21, 27 ou 28 cromossomos metacêntricos ou submetacêntricos e 18, 19, 27, 30, 31 e 32 acrocêntricos. Os cromossomos X eram submetacêntricos. Pares heteromórficos foram observados. Uma fêmea com 48 cromossomos foi descrita pela primeira vez, este número diplóide só havia sido descrito em um único exemplar macho. A confirmação da subespécie dos indivíduos analisados se deu pela presença do par cromossômico característico de Alouatta guariba clamitans, o par 1, e pela região geográfica de procedência dos exemplares. O sexo dos espécimes também foi confirmado ou mesmo determinado pela análise dos cariótipos. Para Alouatta guariba clamitans, corroboramos a tendência à redução do número diplóide orientada no sentido norte-sul. As grandes diferenças cromossômicas entre as populações do sul e sudeste sugerem que Alouatta guariba clamitans seja representante de duas subespécies ou mesmo de duas espécies separadas, evidenciando a necessidade de uma revisão de sua taxonomia. Analisamos um macho de A. sara em coloração convencional, bandamentos GTG e CGB. O cariótipo era formado por 50 cromossomos, com 16 metacêntricos ou submetacêntricos, 31 acrocêntricos e 3 microcromossomos, dois submetacêntricos e um acrocêntrico. O cromossomo X era submetacêntrico e o cromossomo Y estava aparentemente ausente, provavelmente devido a uma translocação Y-autossomo. Um heteromorfismo foi observado. A heterocromatina estava presente na região pericentromérica dos cromossomos, incluindo os três microcromossomos. Duas fêmeas de Ateles paniscus paniscus foram estudadas em coloração convencional. Os espécimes apresentaram 32 cromossomos, com 30 cromossomos metacêntricos ou submetacêntricos e 2 acrocêntricos. A classificação foi baseada no número diplóide e presença do cromossomo 2 metacêntrico característico desta subespécie. Também analisamos dois machos de Ateles sp. em coloração convencional que apresentaram um número diplóide de 34 cromossomos, agrupados em 32 metacêntricos ou submetacêntricos e 2 acrocêntricos. O cromossomo Y era o menor metacêntrico do complemento. Os cromossomos X dos quatro Ateles analisados eram submetacêntricos. A descrição de pares cromossômicos heteromórficos neste gênero é freqüente. Sugerimos que os indivíduos de Ateles sp. sejam classificados como Ateles paniscus chamek. A diferença no número cromossômico entre os exemplares analisados é devido à presença do par metacêntrico em A. p. paniscus que é resultante da fusão in tandem de dois cromossomos de A. p. chamek. A variabilidade intra e interespecífica observada neste gênero podem ser explicadas por inversões pericêntricas. Estudamos uma fêmea e um macho de Callimico goeldii em coloração convencional. Ambos apresentaram 48 cromossomos agrupados em 28 cromossomos metacêntricos ou submetacêntricos e 18 cromossomos acrocêntricos, além do cromossomo X submetacêntrico e do Y acrocêntrico. Heteromorfismos foram observados. Não encontramos variabilidade no número diplóide e a diferença nas fórmulas cromossômicas é devido à morfologia dos cromossomos sexuais. Três machos e quatro fêmeas de Callithrix sp. foram analisados em coloração convencional e bandamentos GTG e CBG. O número cromossômico encontrado foi de 2n = 46, com 30 autossomos metacêntricos ou submetacêntricos, 14 autossomos acrocêntricos, o cromossomo X submetacêntrico e o cromossomo Y acrocêntrico. Duas fêmea e um macho apresentaram linhagens quiméricas 46,XX/46,XY. Heteromorfismos foram encontrados. A heterocromatina estava presente na região pericentromérica dos cromossomos e em blocos extracentroméricos. Não conseguimos determinar com exatidão a espécie de Callithrix, porém pela fórmula cromossômica e morfologia do cromossomo Y sugerimos que possam ser das espécies C. jacchus, C. penicillata ou C. aurita. O macho de Cebus nigritus estudado em coloração convencional apresentou 54 cromossomos divididos em 20 autossomos metacêntricos ou submetacêntricos e 32 acrocêntricos, além do cromossomo X que é um submetacêntrico e do Y que é um acrocêntrico. Não foram observados heteromorfismos. Levando em consideração as características fenotípicas, semelhanças entre os cromossomos com os cariótipos mostrando a mesma fórmula cromossômica e distribuição geográfica, sugerimos que C. nigritus seja sinônimo de C. vellerosus. Estudamos uma fêmea de Callicebus caligatus em coloração convencional que apresentou 48 cromossomos, com 16 metacêntricos ou submetacêntricos e 32 acrocêntricos. Heteromorfismos foram observados. Também analisamos uma fêmea de Callicebus nigrifrons com a mesma coloração e a classificação foi confirmada pela análise citogenética. Esta fêmea mostrou um número diplóide de 2n = 42, compreendendo 30 autossomos metacêntricos ou submetacêntricos e 12 acrocêntricos. Nenhum heteromorfismo foi observado. Os cromossomos X das duas fêmeas eram submetacêntricos. As duas espécies de Callicebus apresentaram números diplóides e fórmulas cromossômicas diferentes, com um predomínio de cromossomos acrocêntricos em C. caligatus e um predomínio de cromossomos não-acrocêntricos em C. nigrifrons, indicando que a redução do número diplóide foi direcionada por eventos de fusão cromossômica. Estudamos a conservação da associação sintênica HSA 14/15 em praticamente todos os gêneros de macacos do Novo Mundo. O homeólogo ao HSA 14 conservou a sintenia para o cromossomo inteiro enquanto o homeólogo ao HSA 15 está fragmentado. Esta associação favorece a origem monofilética da família Atelidae e da subfamília Callitrichinae. Um padrão 14/15/14 foi observado em Alouatta sara e 15/14/15/14 em Aotus nigriceps, mostrando um alto grau de instabilidade citogenética nesta região em alguns gêneros, estando mais susceptível a quebra e inversão. Relatamos a presença desta associação também em Cacajao melanocephalus, que não havia sido estudado com a técnica de FISH. A presença da associação sintênica HSA 14/15 em todas as espécies e subespécies de macacos do Novo Mundo estudadas indica que esta sintenia é um caractere ancestral, concordando com o provável cariótipo ancestral de Platyrrhini. A pintura com a sonda total do cromossomo X humano em praticamente todos os gêneros de Platyrrhini confirmou a Lei de Ohno, que dita a conservação evolutiva do cromossomo X em mamíferos placentários. A sonda total do cromossomo Y de Brachyteles arachnoides produzida por microdissecção cromossômica mostrou uma homeologia entre o cromossomo Y de todos os gêneros pertencentes à subfamília Atelinae (Ateles belzebuth marginatus, Lagothrix lagothricha e Brachyteles arachnoides). Lagothrix e Brachyteles apresentaram um cromossomo Y acrocêntrico diminuto e Ateles mostrou um cromossomo Y acrocêntrico pequeno, mas não diminuto. Não conseguimos hibridar esta sonda em metáfases de espécimes da subfamília Alouattinae, que junto com a subfamília Atelinae compõem a família Atelidae. O uso de caracteres citogenéticos-moleculares pode proporcionar informações valiosas para a elucidação das relações filogenéticas na subfamília Atelinae. Os nossos dados mostram que o cromossomo Y nesta subfamília compartilha uma história comum, devendo mostrar o mesmo padrão filogenético, corroborando a separação da família Atelidae nas subfamílias Atelinae e Alouattinae. Os diferentes números diplóides e fórmulas cromossômicas observados nesse trabalho indicam a grande variabilidade intra e interespecífica e intrapopulacional existente em Platyrrhini, com uma marcante reorganização no seu genoma, decorrente de processos de inversões pericêntricas, fusões cromossômicas, translocações entre cromossomos e outros rearranjos mais complexos. A análise citogenética em Platyrrhini é importante para a identificação das espécies para uma posterior soltura em região geográfica adequada, para os programas de reprodução em cativeiro aumentando as possibilidades de reprodução ex situ e para a deposição em museus. Também é uma ferramenta importante para a identificação das origens dos espécimes com procedência incerta. Uma maior integração e direcionamento dos dados citogenéticos, morfológicos e moleculares é necessária para o entendimento da variação e definição das taxa de forma mais objetiva. A destruição e fragmentação das florestas, as práticas agrícolas, a caça e a subtração de indivíduos como animais de estimação têm afetado negativamente a sobrevivência dos macacos brasileiros. / We studied the karyotypes of Brazilian monkeys (Platyrrhini, Primates) using both traditional cytogenetic techniques as well as FISH. FISH analysis employed human probes for chromosome 14, 15 and the X chromosome and a probe of the Y chromosome of Brachyteles arachnoides obtained by chromosome microdissection. Twenty-four individuals of Alouatta guariba clamitans were studied, twelve males and twelve females. For males, we found a diploid number of 2n = 49 due to the presumed absence of the Y chromosome probably due to a Y-autosome translocation, and 2n = 46 chromosomes, with 17, 19, 20, 21 or 24 biarmed chromosomes and 22, 28, 29, 30 or 32 acrocentrics. For females, a greater variability in the diploid number was observed with 46, 48 and 50 chromosomes and 18, 19, 20, 21, 27 or 28 biarmed chromosomes and 18, 19, 27, 30, 31 and 32 acrocentrics. The X chromosomes were submetacentric. Heteromorphisms were observed. A female with 48 chromosomes was described for the first time; this diploid number had only been described before for a single male. The subspecies has been confirmed by the presence of a characteristic chromosome pair of Alouatta guariba clamitans, pair 1, and by the geographic origin of the samples. The sex was also confirmed or determined by karyotype analysis. The major chromosomal differences between populations of the south and southeast of Brazil suggest that Alouatta guariba clamitans may be representative of two subspecies or even two separate species, highlighting the need for a taxonomic review. A male of A. sara was studied and we observed a diploid number of 2n = 50 chromosomes, with 16 biarmed, 31 acrocentrics and 3 microchromosomes, two submetacentrics and one acrocentric. The X chromosome was submetacentric and the Y chromosome was presumably missing, probably due to a Y-autosome translocation. A heteromorphism was observed. The heterochromatin was present in the pericentromeric region of chromosomes, including the three microchromosomes. Two females of Ateles paniscus paniscus were studied. The specimens had 32 chromosomes, with 30 biarmed and 2 acrocentrics. A heteromorphism was observed. The classification was based on the diploid number and presence of a metacentric chromosome, pair 2, characteristic of this subspecies. We also analyzed two males of Ateles sp. that showed a diploid number of 34 chromosomes, grouped in 32 biarmed and 2 acrocentrics. The Y chromosome was the smallest metacentric. The X chromosomes were submetacentrics. The description of heteromorphisms in this genus is frequent. We suggest that these two individuals of Ateles sp. are classified as Ateles paniscus chamek. The difference in the diploid number of the specimens is due to the presence of a metacentric in A. p. paniscus that is the result of the in tandem fusion of two chromosomes of A. p. chamek. The variability in this genus can be explained by pericentric inversions. We studied a female and a male of Callimico goeldii. Both had 48 chromosomes grouped in 28 biarmed chromosomes and 18 acrocentrics, plus an X submetacentric chromosome and a Y acrocentric. Heteromorphisms were observed. We observed no variations in the diploid number and all differences are due to the morphology of the sex chromosomes. Three males and four females of Callithrix sp. were studied. The chromosome number was 2n = 46, with 30 biarmed, 14 acrocentrics, a submetacentric X chromosome and an acrocentric Y chromosome. Two females and one male showed 46,XX/46,XY chimerisms. Heteromorphisms were found. The heterochromatin was present in the pericentromeric region and in extracentromeric blocks. We observed no variations in the diploid number and the only differences are due to the morphology of the sex chromosomes. We could not determine the Callithrix species, but the karyotypes suggest C. jacchus, C. penicillata or C. aurita. The Cebus nigritus male studied showed 54 chromosomes grouped in 20 biarmed and 32 acrocentrics, and a submetacentric X chromosome and an acrocentric Y. There were no heteromorphisms. Taking into account the phenotypic characteristics, similarities between chromosomes and geographical distribution, we suggest that C. nigritus is synonymous with C. vellerosus. We studied a female Callicebus caligatus that showed 48 chromosomes, with 16 biarmed and 32 acrocentrics. Heteromorphisms were observed. We also analyzed a female Callicebus nigrifrons, whose taxonomic placement was confirmed by cytogenetic analysis. Its diploid number was 2n = 42, including 30 biarmed and 12 acrocentrics. No heteromorphisms were observed. The X chromosomes were submetacentrics. The two Callicebus species showed different diploid numbers, with a predominance of acrocentric chromosomes in C. caligatus and a predominance of biarmed chromosomes in C. nigrifrons, indicating that the reduction in the diploid number was due to events of chromosomal fusion. We studied the syntenic association HSA 14/15 conservation in almost all genera of Platyrrhini. The HSA 14 homolog retained synteny for the entire chromosome however the HSA 15 homolog was fragmented. The association suggests a monophyletic origin of the Atelidae family and Callitrichinae subfamily. A 14/15/14 pattern was observed in Alouatta sara and a 15/14/15/14 pattern in Aotus nigriceps, showing a high degree of instability in this region in some genera. We report the presence of this association also in Cacajao melanocephalus, who had not been previously studied with FISH technique. The presence of the HSA 14/15 syntenic association in all species and subspecies of Platyrrhini that we studied indicates that this is an ancestral trait, agreeing with Platyrrhini ancestor karyotype. The painting with human X chromosome in almost all genera of Platyrrhini consistent with Ohnos Law, indicating evolutionary conservation of the X chromosome in placental mammals. The signals were found exclusively in the X chromosome homologs. The Y chromosome probe of Brachyteles arachnoides produced by chromosome microdissection showed homology between the Y chromosomes of all genera belonging to the Atelinae subfamily (Ateles belzebuth marginatus, Lagothrix lagothricha and Brachyteles arachnoides). Lagothrix and Brachyteles Y chromosomes are extremely small acrocentrics and the Ateles Y chromosome is small. We could not hybridize this probe in metaphases form Alouatta, which along with the Atelinae genera comprise family Atelidae. The use of molecular-cytogenetic traits can provide valuable information for the elucidation of phylogenetic relationships in tne Atelinae subfamily. Our data show that the Y chromosome in the subfamily Atelinae shares a common history and is consistent with the separation of family Atelidae into the subfamilies Atelinae and Alouattinae. In conclusion our study indicates a great degree of chromosomal varaibility within Platyrrhini and suggests a marked reorganization of the genome within this primate group, due to such processes as pericentric inversions, chromosome fusions, translocations between chromosomes and other complex rearrangements. Cytogenetic analyse in Platyrrhini are important for species identification. Such information can in turn be useful for a variety of conservation and systematic purposes including repatriation of animals in an appropriate geographical region, for captive breeding programs, increasing the chances of ex-situ breeding, and for the deposition of specimens in museums. It is also an important tool for identifying the geographical origins of specimens with uncertain origin. Integration of cytogenetic, morphological and molecular data is necessary for the understanding of variation and definition of the taxa and understanding evolutionary processes at these different levels. Forests destruction and fragmentation, agricultural practices, hunting and subtraction of individuals as pets have negatively affected the survival of Brazilian monkeys.