No description available.

Specification of floral organ identity in angiosperm flowers is accomplished by the coordinated activity of A-, B-, C-, and E-class MADS-box genes. In the eudicots, B-class genes specify petal and stamen identity. This eudicot B-class function depends on the simultaneous expression of genes from two paralogous B-class lineages (the DEFICIENS/APETALA3 lineage and the GLOBOSA/PISTILLATA lineage). Proteins produced by genes from these two lineages interact as obligate heterodimers and together regulate the transcription of various downstream targets. These obligate heterodimers also positively regulate the transcription of the B-class genes themselves, thereby mediating a unique B-class autoregulatory feedback loop. There is compelling evidence that B-class function at the phenotypic and molecular level is highly conserved among the eudicots. The degree to which B-class homeotic function, obligate heterodimerization, and autoregulation are conserved in non-eudicot, however, remains a topic of debate. Here we describe loss of function in Sterile tassel silky ear1 (Sts1) a maize ortholog of GLOBOSA/PISTILLATA formerly known as Zmm16. Mutation in Sts1 results in homeotic transformation of lodicules and stamens into bract-like organs in male inflorescences. Female inflorescences are affected in a similar manner. Stamens in these inflorescences are, however, transformed into carpels instead of into bract-like organs. This mutant phenotype suggests that Sts1 has a B-class homeotic function. Using qRT-PCR we also demonstrate that Sts1 participates in positive transcriptional regulation of all of the maize B-class genes. These findings suggest a high degree of B-class functional conservation between the monocots and the eudicots. Analysis of tasselseed1/sts1 and grassy tillers1/sts1 double mutants suggests that maize B-class genes also play a role in the sex determination process.

<p>  </p> <p>Down syndrome (DS) is caused by the partial or complete trisomy of human chromosome 21 (Hsa21) and can result in skeletal deficits, including lower bone mineral density (BMD) and increased risk of fracture and osteoporosis or osteopenia earlier than the general population. Mouse models of DS have been developed to understand the genetic mechanisms resulting in these phenotypes, but models differ due to the complex genetic nature of DS and differing genome structures between humans and mice. Ts65Dn mice have been a popular model of DS as they contain ~50% of Hsa21 orthologous genes on a freely segregating minichromosome, but there is speculation that the phenotypes are exaggerated by non-Hsa21 orthologous trisomic genes also present. To address this issue, the Ts66Yah mouse model was developed to remove the non-Hsa21 orthologous trisomic genes. In this study, male and female Ts66Yah mouse femurs were evaluated during bone accrual and peak bone mass to investigate structural differences using micro-computed tomography. Additionally, the role of trisomic <em>Dyrk1a</em>, a Hsa21 gene previously linked to bone deficits in Ts65Dn mice, was evaluated through genetic and pharmacological means in Ts66Yah femurs at postnatal day 36. Ts66Yah mice were found to have little or no trabecular deficits at any age evaluated, but sex-dependent cortical deficits were present at all ages investigated. Reducing <em>Dyrk1a</em> copy number in Ts66Yah mice significantly improved cortical deficits but did not return cortical bone to euploid levels. Pharmacological treatment with DYRK1A inhibitor L21 was confounded by multiple variables, making it difficult to draw conclusions about DYRK1A inhibition in this manner. Overall, these results indicate trabecular deficits associated with Ts65Dn mice may be due to the non-Hsa21 orthologous trisomic genes, and more Hsa21 orthologous trisomic genes are necessary to produce trabecular deficits in DS model mice. As more mouse models of DS are developed, multiple models need to be assessed to accurately define DS-associated phenotypes and test potential treatments.</p>

No description available.

Die Geschlechtsbestimmung bei Säugetieren erfolgt über gegensätzliche Netzwerke von ovariellen und testikulären Genen, die recht gut charakterisiert sind. Die epigenetischen Mechanismen, insbesondere diejenigen, die die 3D-Chromatinorganisation beeinflussen, sind jedoch größtenteils unbekannt. Ich habe die 3D-Chromatinlandschaft der Geschlechtsbestimmung in vivo untersucht, indem ich FACS-sortierte embryonale Mausgonadenpopulationen vor und nach der Geschlechtsbestimmung in beiden Geschlechtern analysierte. Dabei wurde eine begrenzte Variation in der dreidimensionalen Chromatindynamik beobachtet, insbesondere bei den Topologically Associating Domains (TADs). Konventionelle Hi-C-Analysemethoden sind hauptsächlich auf vordefinierte 3D-Strukturen ausgerichtet und könnten potenziell andere Veränderungen in der Chromatinorganisation übersehen, die für die Genregulation relevant sein könnten. Um diese Einschränkungen zu überwinden, wurde METALoci eingesetzt - ein innovatives Werkzeug, das Hi-C- und ChIP-seq-Daten integriert und räumliche Autokorrelationsanalyse nutzt, um dreidimensionale Enhancer-Hubs im gesamten Genom zu identifizieren. METALoci zeigte eine deutliche Umverdrahtung von Chromatininteraktionen während der Geschlechtsbestimmung, die die regulatorischen Landschaften von Hunderten von Genen beeinflusste. Darüber hinaus führte die Vorhersagekraft von METALoci in Kombination mit funktionalen Validierungen an transgenen Mäusen zur Identifizierung eines neuen Fgf9-regulatorischen Hubs. Die Deletion dieses Hubs führte zu teilweisem Geschlechtsumkehr von männlich zu weiblich, mit einer Hochregulierung ovarieller spezifischer Marker und der Einleitung der Meiose. So erweist sich die räumliche Autokorrelationsanalyse als eine effektive Strategie zur Identifizierung von regulatorischen Netzwerken, die mit biologischen Prozessen verbunden sind, und zur anschließenden Charakterisierung der funktionalen Rolle des dreidimensionalen Genoms. / Mammalian sex is determined by opposing networks of ovarian and testicular genes that are relatively well characterized. Yet, the epigenetic mechanisms governing sex determi- nation, in particular those involving 3D chromatin organization, remain largely unknown. This gap of knowledge constrains our understanding of a fundamental process for species reproduction and perpetuation. Here, I explored the 3D chromatin landscape of sex deter- mination in vivo, by profiling FACS-sorted embryonic mouse gonadal populations, prior and after sex determination, in both sexes. Using conventional Hi-C analysis tools, limited variation in the 3D chromatin dynamics was observed, especially at the level of Topolog- ically Associating Domains (TADs). This contrasts with the broad transcriptional differ- ences occurring during sex determination. Yet, conventional Hi-C analysis methodologies are largely focused on predefined 3D structures, potentially overlooking other types of changes in chromatin organization that might be relevant for gene regulation. To ad- dress these limitations, METALoci was applied- an innovative tool that integrates Hi-C and ChIP-seq data and relies on spatial auto-correlation analysis to identify 3D enhancer hubs distributed throughout the genome. METALoci uncovered a prominent rewiring of chromatin interactions during sex determination, affecting the regulatory landscapes of hundreds of genes. Furthermore, METALoci ’s predictive capacity, in combination with functional validations in transgenic mice led to the identification of a novel Fgf9 regulatory hub, which deletion resulted in partial male-to-female sex reversal with the upregulation of ovarian-specific markers and the initiation of meiosis. Thus, spatial auto-correlation anal- ysis proves to be an effective strategy to identify regulatory networks linked to biological processes and to subsequently characterize the functional role of the 3D genome.

Caligid copepods, also called sea lice, are ectoparasites of marine fish, with Lepeophtheirus salmonis (Krøyer, 1837) emerging as a problem for mariculture of Atlantic salmon (Salmo salar Linnaeus, 1758) in the northern hemisphere. Annual costs of sea lice to global salmon farming was estimated to be in excess of €300 million in 2006, with the majority of this accounted for through expenses accrued from chemical treatments. Only a limited range of anti-sea louse drugs are available and licensed for the treatment of fish, and the continued use of only a few compounds creates a situation potentially favouring the development of drug resistance. Emamectin benzoate (EMB) is currently used as a salmon delousing agent, being employed as a 0.2 % in-feed pre-mix (SLICE®). Atlantic salmon farmers have reported increased incidence of reduced L. salmonis sensitivity to SLICE®, which has highlighted the requirement for further research into the molecular mechanisms controlling salmon louse resistance to EMB. Genomic and transcriptomic research concerning L. salmonis drug resistance mechanisms has not often been reported, with previous transcriptomic studies using candidate gene approaches and genetic studies focussing on population genetics. Drug resistance in ecdysozoan invertebrates is associated with a variety of molecular mechanisms including target site mutations and changes in the expression of components in drug detoxification pathways. The research reported in this thesis was aimed at the exploration of mechanisms employed by L. salmonis to reduce the toxicity of EMB exposure, following a transcriptomic approach that utilised custom oligonucleotide (oligo) microarrays and a genetic approach that utilised Restriction-site associated DNA sequencing (RAD-seq) to identify Single Nucleotide Polymorphism (SNP) markers. An EMB-resistant (PT) and drug-susceptible (S) L. salmonis laboratory-maintained strain were to be used as a model for this research, as these two strains differ in EMB susceptibility (~ 7-fold) and show stable susceptibility profiles through multiple generations, suggesting that this drug resistance phenotype may be a heritable trait. Sequence resources available for salmon lice are limited as an annotated L. salmonis genome is currently under construction. Therefore, a significant amount of this study involved creating new resources to facilitate the analysis of EMB susceptibility. Suppression subtractive hybridisation (SSH) was used to enrich for transcripts that were differentially expressed between strains PT and S, which provided sufficient target sequence for the development of 15K oligo microarrays when combined with sequences assembled from existing L. salmonis ESTs. Additionally, transcripts were generated through sequencing a pooled sample representing key developmental stages of the L. salmonis life cycle, which were later used in the construction of a 44K oligo microarray. The toxicity of EMB and other avermectins (AVMs) against ecdysozoan invertebrates is reported to be based mainly on their interaction with ligand-gated ion channels (LGIC), specifically glutamate-gated chloride channels (GluCl). However, -aminobutyric acid (GABA)-gated chloride channels (GABA-Cls) are also believed to be targeted by AVMs and neuronal acetylcholine receptors (nAChRs) can be allosterically modulated by the AVM compound ivermectin. Transcriptional responses in PT and S salmon lice were investigated using custom 15K L. salmonis oligo microarrays. In the absence of EMB exposure, 359 targets differed in transcript abundance between the two strains. GABA-Cl and nAChR subunits showed significantly lower transcript levels in PT compared to S lice, which was estimated at ~1.4-fold for GABA-Cl and ~2.8-fold for nAChR using RT-qPCR, suggesting their involvement in AVM toxicity in caligids. Although, salmon lice from the PT strain showed few transcriptional responses following acute exposure (1 or 3 h) to 200 µg L-1 of EMB, a drug concentration tolerated by PT lice, but toxic for S lice. RAD-seq analysis of both genders from L. salmonis strains S and PT identified 15 RAD-markers that show complete association with salmon louse strain, although these preliminary results will need further analysis to confirm marker association with reduced EMB susceptibility. Additionally, RAD marker Lsa101901 showed complete association with sex for all individuals analysed, being heterozygous in females and homozygous in males. Using an allele-specific PCR assay, this SNP association pattern was further confirmed for three unrelated salmon louse strains. Marker Lsa101901 was located in the coding region of the prohibitin-2 gene, which showed a sex-dependent differential expression, with mRNA levels determined by RT-qPCR about 1.8-fold higher in adult female than adult male salmon lice. In conclusion, the identification of decreased transcript abundances for LGIC subunits in EMB-resistant salmon lice, and polymorphic SNP markers showing complete association with L. salmonis strains S or PT, provides suitable candidates for further investigation into their association with reduced EMB susceptibility. Further analysis will also be required to confirm whether EMB-induced mechanisms are not associated with reduced EMB susceptibility in L. salmonis. Additionally, the identification of sex-linked SNP Lsa101901 suggests that sex determination in the salmon louse is genetic and follows a female heterozygous system, with marker Lsa101901 providing a tool to determine the genetic sex of salmon lice. Improved knowledge of L. salmonis biology and the mechanisms potentially involved in EMB resistance, obtained during this study, may provide molecular markers that contribute to successful monitoring and management of this commercially important parasite of Atlantic salmon.

De par leur diversité de mécanismes de déterminisme du sexe et de chromosomes sexuels, les poissons téléostéens représentent d’excellents modèles pour mieux comprendre les bases moléculaires et évolutives du contrôle du développement sexuel chez les vertébrés. Grâce à l’analyse de chromosomes artificiels bactériens couvrant les chromosomes sexuels du platy Xiphophorus maculatus, trois copies d’un nouveau gène nommé teximY ont été découvertes dans la région de déterminisme du sexe du chromosome Y mais pas du chromosome X. Un gène texim1 très apparenté à teximY ainsi que trois gènes plus divergents ont été identifiés sur les autosomes. Les gènes teximY sont préférentiellement exprimés dans les testicules, au niveau des cellules germinales lors des étapes tardives de la spermatogénèse, alors que texim1 est également transcrit dans les gonades femelles. Des gènes texim ont été détectés chez d'autres poissons téléostéens mais pas chez le poisson-zèbre, ainsi que chez des céphalocordés, des urocordés et des échinodermes mais pas chez les tétrapodes. Les gènes texim codent pour des estérases putatives à domaine SGNH apparentées à des protéines cellulaires procaryotes et eucaryotes ou codées par des retrotransposons animaux. Les gènes texim sont associés à des transposons Helitron chez les poissons mais pas chez les autres animaux, suggérant capture et mobilisation du gène ancestral texim par un transposon à la base de la radiation des téléostéens. TeximY pourrait jouer un rôle dans la transposition du transposon Helitron dans la lignée germinale mâle, ou correspondre à un gène de spermatogenèse mobilisé par le transposon Helitron sur les nouveaux chromosomes sexuels de poissons. / The molecular and evolutionary basis of sex determination in vertebrates needs to be unveiled via comparison of different systems. Fish exhibit hypervariability of sex determination mechanisms. Thanks to the analysis of the Bacterial Artificial Chromosome (BAC) library covering the sex chromosomes of the platyfish Xiphophorus maculatus (Rio Jamapa population, XX /XY), three copies of a new gene have been identified in the sex-determining region of the Y but not the X chromosome, and named teximY. Four autosomal counterparts of teximY have been also detected in the genome of the platyfish with one of them, texim1 presenting 95% of cDNA sequence identity with the Y-linked copies. RT-qPCR expression analyses have been performed for each copy in male and female tissues. Two Y-linked teximY copies were preferentially expressed in testis, whereas the autosomal copy texim1 showed preferential expression in male and female gonads. In situ hybridizations with a teximY/1 probe revealed expression in late spermatids and spermatozeugmata. Texim sequences were detected in several fish species, but not in zebrafish, as well as in cephalochordates, urochordates and sea echinoderms but not in tetrapods. Predicted Texim proteins are related to proteins from different origins. Interestingly, texim genes are associated with a Helitron transposon in fish but neither in cephalochordates nor in echinoderms, suggesting capture and mobilization of an ancestral texim gene at the base of the bony fish lineage. TeximY proteins may play a role in Helitron transposition in the male germ line in fish, or texim genes are spermatogenesis genes mobilized and spread by transposable elements in fish genomes.

Antropologia Forense é a aplicação da ciência da Antropologia Física e osteologia humana em casos criminais onde os restos da vítima estão em fase avançada de decomposição. Devido ao grande fluxo migratório descrito no histórico do Brasil, a população brasileira possui características físicas muito heterogêneas quando comparadas com a população escocesa, uma vez que a imigração mais significativa foi proveniente de outras regiões do próprio Reino Unido. O presente estudo teve como objetivo comparar as variações craniométricas de duas populações (brasileira e escocesa), e avaliar a confiabilidade do método para determinação do sexo nas duas populações, com finalidade forense. A amostra total foi composta por 200 crânios com mandíbulas, sendo que a amostra brasileira foi constituída por 100 crânios completos e a amostra escocesa por 100 crânios e 36 mandíbulas, ambas amostras documentadas. Foram realizadas 72 mensurações sendo 51 cranianas e 21 mandibulares. Os resultados demonstraram que a amostra escocesa apresentou média maior comparada com a amostra brasileira em 54 variáveis do universo de 72 medidas. Trinta e três mensurações cranianas apresentaram diferença significativa entre as duas amostras e dentre as 21 medidas mandibulares analisadas, 05 apresentaram variação superior a 20%, 09 entre 10% e 20%, 07 inferior a 10%. As medidas que apresentaram maior dimorfismo sexual para as duas amostras foram a largura bizigomática (apresentando 73% de acerto para a amostra brasileira e 77% para a amostra escocesa), largura bigoníaca (79% e 83,30%) comprimento Porion-Mastoidale lado esquerdo (76% e 75%) e a altura do corpo mandibular lado esquerdo (67% e 80,60%). A análise discriminante multivariada demonstrou resultados satisfatórios para amostra brasileira com porcentagem de acerto variando entre 76-90% e na amostra escocesa 81-86,6%. Através da análise da curva ROC foram desenvolvidas 04 tabelas de referência sendo 01 para medidas cranianas brasileiras, 01 medida para mandibulares brasileiras, 01 tabela para medidas cranianas escocesas e 01 para medidas mandibulares escocesas. O presente estudo demonstrou que existem diferenças entre as duas amostras estudadas, porém ainda falta elucidar a causa responsável, já que se trata de uma grandeza multifatorial. A metodologia quantitativa analisada demonstrou-se precisa para analisar dimorfismo sexual nas duas amostras. / Forensic anthropology is the application of the physical anthropology science and human osteology in criminal cases where the victim\'s remains are in an advanced stage of decomposition. Due to migration Brazilian population is very diverse, comprising many races and ethnic groups, therefore it is much more varied than the Scottish population, which tends to be more homogenous once there was significant immigration to Scotland from the rest of the United Kingdom. The present study aimed to compare the craniometric variations of two populations (Brazilian and Scottish), and analyze the reliability of sex determination in the two populations for forensic purpose. The total sample was comprised of 200 skulls and 136 mandibles, the Brazilian sample consisted of 100 complete skulls and the Scottish sample was composed of 100 skulls and 36 mandibles, both of which are documented samples. The measure\'s protocol comprised 72 measurements, being 51 cranial and 21 mandibular. The results showed that the Scottish sample had a larger mean compared to the Brazilian sample in 54 variables of the 72 measures. Among the cranial measurements analyzed, 33 variables showed a significant difference between the two samples and among the 21 mandibular measurements considered, 05 presented a variation greater than 20%, 09 between 10% and 20%, 07 lower than 10%. The most dimorphic measurements for both samples were the bizigomatic width (73% of accuracy for the Brazilian sample and 77% for the Scottish sample), the bigoniac width (79% and 83,30%), the Porion-Mastoidale length (76% and 75%), and the left side mandibular body height (67 and 80,60%). The multivariate discriminant analysis showed satisfactory results for the Brazilian sample with a percentage of accuracy varying between 76-90% and in the Scottish sample 81-86.6%. Through the analysis of the ROC curve, four reference tables were developed: 01 for Brazilian cranial measurements, 01 Brazilian mandibular measurements, 01 Scottish cranial measurements and 01 Scottish mandibular measurements The present study showed a difference between the two samples studied, but it is not possible to define an unique cause responsible for that because this comprise multifactorial aspects. The quantitative methodology analyzed showed sexual dimorphism in both samples.

Captive husbandry programs in zoos have documented nesting behavior and have successfully hatched Manouria emys emys, but data on sex determining mechanisms and sex ratios are absent. A total of 30 M. e. emys eggs were artificially incubated at five different temperatures in constant humidity. Mean incubator temperatures were 24.99°C, 25.06°C, 27.18°C, 28.00°C, and 30.79°C. Incubation duration ranged from 60 days to 92 days, and hatching success was 50%. Sex determined by histology and laparoscopy resulted in male differentiation at low temperatures (24.99°C, 27.18°C) and female differentiation at high temperatures (30.79°C). Pivotal temperature was estimated to be 29.29°C. The following investigation into temperature-dependent sex determination (TSD), including its presence or absence, pattern, and pivotal temperature, has implications for studies of adaptive significance of reproductive behaviors and of chelonian phylogenetic history. Additionally, the proposed study can provide foundations for conservation management decisions, and for captive breeding programs.

Fisher’s adaptive sex ratio theory predicts that organisms should invest equally in sons and daughters and the sex ratio at conception should be 1:1. Hamilton’s theory predicts that organisms should adjust sex ratios based on the relative strength of competition within a mating group. Testing sex ratio and sex allocation theories requires variation in sex ratio. Different sex allocation and sex allocation adjustment mechanisms can produce skewed sex ratios. I used Tigriopus californicus, a harpacticoid copepod with extrabinomial variation in sex ratios, to test sex ratio evolution and socially-mediated sex determination. Using artificially selected sex-biased populations, the trajectory of population sex ratios were as expected under Fisher’s theory and sex ratios approached/reached 0.5 proportion males. Populations with overlapping generations had a slower rate of change towards 0.5 than populations with non-overlapping generations. I show that these data are supported by multiple different models: a mechanistic and simulation model. I tested socially-mediated sex determination using seawater conditioned with different local sex ratios of copepods. There were detectable effects found in both wild populations and isofemale lines. However, these effects may be trivial as differences were small between treatments. Sex determination in T. californicus is a complex mechanism, with multiple genetic and environmental components. The complex nature of sex determination in T. californicus and the dynamic nature of their habitat in highly ephemeral splash pools provide a possible explanation for the non-Fisherian sex ratios we see. / Graduate