Heterotrophic microorganisms are important for the flow of carbon and nutrients in the sea. Bacteria, nanoflagellates and ciliates are relevant components of the pelagic food web. In order to be able to predict the outcome of e.g. eutrophication or climate change we need to know how the different components of the pelagic food web are regulated. With the focus on the northern Baltic Sea food web, this thesis deals with limitation and control of heterotrophic protists, the effect of resource heterogeneity on food web efficiency and diversity of nanoflagellates. In-situ microcosm experiments showed that the net growth of heterotrophic flagellates were resource limited throughout the year. Field data confirmed that the abundance of flagellates was bottom-up controlled. Furthermore, field data also showed that the annual average biomass of protists, flagellates and ciliates increased with primary productivity. On a smaller seasonal scale temperature and bacterial biomass were able to explain most of the variation in flagellate biovolume. The temporal variation in ciliate biovolume could not be explained by any bottom-up factors like bacterial biomass, flagellate biomass or chlorophyll a. This and an in-situ microcosm experiment implied that the seasonal dynamics of ciliates were more regulated by predators like mesozooplankton. The food web efficiency i.e. how much of production at the resource level is converted to production at the top trophic level, may be affected by specific size or type of resource. Indoor mesocosms revealed that the food web efficiency was 11 times lower when heterotrophic bacteria dominated basal production instead of nano- and micro-sized phytoplankton. This was due to a lengthening of the food web when pico-sized bacteria constituted the main resource. The PCR-DGGE molecular biological method was used to study the diversity of heterotrophic or mixotrophic chrysomonads. The focus was set on chrysomonads due to their relatively large contribution to the nanoflagellate community. Group-specific PCR primers were optimized for the target group. A field survey in the northern Baltic Sea showed that a handful of chrysomonad sequences were present throughout the year. Significantly more chrysomonads were recorded in the basin with higher primary productive and salinity. In total 15-16 different chrysomonad sequences were recorded. Most of them matched uncultured chrysomonad clones.

Green algae are quite important primary producers in fresh waters. The genus Chlorella represents one of algae most frequently utilized in algal biotechnologies to produce biomass, using either autotrophic or heterotrophic cultivation systems. It is than exploited as a food supplement for humans or animals. However, particular species within the genus are morphologically indistinguishable and molecular markers should be used to characterize production strains. This work is aimed to molecularly characterize three production strains of Chlorella for patent protection purposes and to specify their phylogenetic and taxonomic position.

O presente trabalho teve por objetivo identificar fragmentos homólogos a genes de resistência em Brassica oleracea e Zea mays, por meio da amplificação por PCR, utilizando oligonucleotídeos homólogos a regiões conservadas de genes de resistência de plantas. Em B. oleracea, os oligonucleotídeos foram desenhados com base na seqüência de um gene homólogo ao RPS2 de Arabidopsis thaliana descrito em B. oleracea. Um fragmento de 2,5 Kb foi amplificado em duas linhagens. Os fragmentos amplificados apresentaram polimorfismo de comprimento entre as linhagens, gerando um marcador molecular. Este marcador foi utilizado em uma população F2 segregante para resistência a Xanthomonas campestris pv. campestris oriunda do cruzamento entre as linhagens BI-16 e Lc201. O marcador, no entanto, não apresentou-se ligado a nenhum gene de resistência a este patógeno. Análise da expressão por meio de RT-PCR detectou a expressão do fragmento homólogo nas linhagens resistente e suscetível de B. oleracea com e sem inoculação, indicando que o gene é expresso constitutivamente. Em Z. mays, oligonucleotídeos sintetizados com base em seqüências de milho homólogas a genes de resistência, denominadas Pics, e a ESTs de milho, também homólogos a genes de resistência, foram utilizados para amplificação em linhagens resistente e suscetível a Exserohilum turcicum, Colletotrichum graminicola e Phaeosphaeria maydis. Um par de oligonucleotídeos amplificou um fragmento polimórfico entre as linhagens resistente e suscetível a E. turcicum. Este foi utilizado em uma população segregante, mas também não observou-se ligação com o gene Ht de resistência a E. turcicum. Nas demais linhagens, os fragmentos foram monomórficos. Os oligonucleotídeos baseados em ESTs amplificaram fragmentos em todas as linhagens parentais. Esses fragmentos foram digeridos com enzimas de restrição, mas não apresentaram polimorfismo entre nenhuma das linhagens. Os resultados indicaram que a estratégia de utilização de seqüências conservadas é eficiente para amplificação de genes homólogos. O polimorfismo entre estes homólogos pode ser usado como marcador molecular para detecção de genes de interesse. Todavia, nem sempre estes marcadores estão ligados a esses genes. / The aim of this work was to identify homologs of resistance genes in Brassica oleracea and Zea mays by PCR amplification using primers based on conserved domains of plant resistance genes. In B. oleracea, the primers were based on the sequence of a homolog of the Arabidopsis thaliana RPS2 gene previously described in B. oleracea. A 2.5 Kb fragment was amplified on two lines. These fragments showed length polymorphisms between lines, based on which a molecular marker was developed. This marker was used in a F2 population, derived from the crossing between the inbred lines BI-16 and Lc201, and which segregates to resistance to Xanthomonas campestris pv. campestris. The marker, however, was not linked to any Xcc resistance gene. Expression analyses by RT-PCR detected the expression of these homologs on both resistant and susceptible lines with and without inoculation, indicating that the gene is constitutively expressed. In Z. mays, primers based on resistance gene homologs sequences, named Pics, and on maize ESTs homologous to disease resistance genes, were used to amplify genomic fragments on resistant and susceptible lines to Exserohilum turcicum, Colletotrichum graminicola and Phaeosphaeria maydis. A set of primers amplified a polymorphic fragment between lines resistant and susceptible to E. turcicum. This fragment was used in a segregating population, but no linkage was detected between this marker and the E. turcicum resistance gene Ht. Among the other lines, the fragments were not polymorphic. The primers based on ESTs amplified fragments on all parental lines. These fragments were digested with restriction enzymes but did not reveal any polymorphism between lines. The results indicated that the strategy of using conserved sequences is efficient to amplify disease resistance gene homologs. The polymorphism among these homologs may be used as a molecular marker, but these markers are not always linked to disease resistance genes.

Background: Critically ill patients are at particular risk of developing bloodstream infection. Such infections are associated with the development of sepsis, leading to a marked increase in mortality rate. Early detection of the causative organism and appropriate antibiotic treatment are therefore critical for optimum outcome of patients with nosocomial infection. Current infection diagnosis is based on standard blood culture techniques. However, microbiological culture has a number of limitations, not least that it takes several days to confirm infection and is therefore not useful in directing the early treatment with antibiotics. New techniques based on the detection of pathogen DNA using real-time polymerase chain reaction (PCR) technology have the potential to address these limitations but their clinical utility is still to be proved. Objectives: Develop and evaluate novel PCR-based approaches to bloodstream infection diagnosis in critical illness based on detection and identification of bacterial and fungal DNA in blood. Methods: A range of commercial and 'in-house' PCR-based assays for detection of bacterial and fungal DNA were developed and/or optimised for use in clinical blood samples. These included LightCycler SeptiFast, a CE-marked multi-pathogen assay for common bloodstream pathogens, BactScreen and GramScreen, broad spectrum bacterial assays based on 16S rRNA gene and real-time PCR assays developed to detect a range of clinically important fungal pathogens. Novel approaches to speciation of pathogen DNA using melting temperature (Tm) profiling and high resolution melting analysis (HRMA) were developed. Clinical evaluation of assays was either on blinded clinical isolates or blood samples from critically ill patients with clinical suspicion of bloodstream infection against conventional microbiological culture. Several techniques aimed at improving extraction of pathogen DNA from blood were also investigated. Results: The CE-marked commercial assay SeptiFast showed analytical sensitivity and specificity of 79% and 83% respectively. Concordance with positive culture results was good but high levels of 'false positives' were detected possibly attributed to detection of free pathogen DNA not associated with viable pathogens. The predictive value of a negative SeptiFast test was 98% suggesting that absence of pathogen DNA is a strong indicator of absence of infection. Further studies were aimed at detailed optimisation and validation of 16S rRNA gene real-time PCR assays for bacterial DNA. BactScreen and GramScreen were able to detect a broad range of clinically important bacteria down to <50 CFU/ml blood. A preliminary comparative evaluation against SeptiFast showed BactScreen gave excellent concordance with blood culture results with minimal false positive results compared to SeptiFast. Efficient extraction of pathogen DNA was shown to be a key factor in determining analytical sensitivity and several protocols were evaluated. Low cost approaches to speciation of bacterial DNA were developed by combining broad range real-time PCR with HRMA. A novel HRMA method based on Tm profiling was shown to identify 89% and 96% of blinded clinical isolates at species or genus level respectively. Real-time PCR/HRMA approaches were also successfully developed for detection and identification of fungal pathogens including a range of Candida and Aspergillus species associated with bloodstream fungal infection. Conclusions: These studies have highlighted some of the key factors that need to be considered when developing and validating PCR based assays for pathogen DNA detection in blood. A set of novel tools have been developed for rapid detection and identification of bacterial and fungal pathogens that could address the challenges of infection diagnosis based on pathogen DNA detection. Further work is required, not least in development of more efficient pathogen DNA extraction and detailed clinical validation but the tools described here have the potential to provide cost effective solutions to aid infection diagnosis that would be complementary to current culture-based methods. The provision of time critical information could have a positive impact on clinical decision-making leading to more effective management and treatment of patients with suspected bloodstream infection.

Polymerase chain reaction (PCR) is a method used in many research protocols to amplify a small amount of a short segment of DNA to millions of copies. PCR is used for many taxonomic studies, as well as for some medical diagnostic procedures. Through PCR, short DNA primers bind to the template DNA to allow the thermostable DNA polymerase to copy the DNA. Often, researchers create universal primers to target a conserved region of DNA in multiple species, for example, the 16S rRNA gene in bacteria. The problem with these universal primers is that they do not always perfectly match the target DNA. The mismatch primers can still bind to the template, but could affect the efficiency of the PCR amplification. The effect of mismatch primers on the efficiency of the amplification in PCR is the focus of this thesis. Four forward primers with various mismatch overhangs were generated and incorporated into a DNA template through an initial PCR. These primers contained the binding region complementary to the V3/V4 region of the 16S rRNA bacterial gene. Further quantitative PCR (qPCR) reactions were run on these newly-made templates using two sets of primers complementary to the 16S rRNA gene region – one with ambiguous base pairs, one with unambiguous base pairs. The qPCR amplification curves, the Cq values, and the initial concentrations of DNA products (seed values) were analyzed and compared. The results showed differences in the Cq values and seed values between the reactions containing mismatches and those not containing mismatches. Other variables including annealing temperature, addition of Illumina sequencing tails to the primers, and initial primer concentration were also tested to determine if these variables had an effect on the amplification. The results from these reactions using different variables were inconclusive.

No description available.

No description available.

Genotypic differences in growth and yield of two common bean (Phaseolus vulgaris L) cultivars to Rhizobium inoculation and management were investigated. In 2003-04, the two bean cultivars (Scylla and T-49) were combined with three inoculant treatments (strains CC 511 and RCR 3644, and a control of no inoculation), two fertiliser levels (0 and 150 kg N ha⁻¹) and two irrigation treatments (irrigated and rainfed). There was no nodulation on either cultivar. To further investigate the symbiotic relationship, 16 rhizobial isolates, including the two used in the first field experiment, were combined with the cultivar Scylla and evaluated in a greenhouse. Subsequently, five Rhizobium isolates were chosen for further field evaluation, based on signs of early nodulation in the greenhouse trial. The second field experiment in 2004-05 combined the five inoculant strains (RCR 3644, UK 2, H 20, PRF 81, PhP 17 and a control) with two bean cultivars (Scylla and T-49). In the greenhouse, nodule number varied from 7 (UK 2) to 347 (H 441) nodules plant⁻¹ at 51 DAS and from 13 (UK 1) to 335 (CIAT 899) nodules plant⁻¹ at 85 DAS. In 2004-05, in the field, nodulation was also variable, ranging between 1 and approximately 70 nodules plant⁻¹, with higher nodules numbers plant⁻¹ being found on cultivar T-49. Of the isolates used in the field, strains H 20, PRF 81 and PhP 17 produced 70, 25 and 12 nodules plant⁻¹ at 70, 40 and 54 DAS respectively. Nodules formed were of various sizes and more than 80 % were pink to dark red in colour denoting the presence of leghaemoglobin and active N fixation. The remaining nodules were either green or white. The importance of selecting an appropriate cultivar for the growing conditions was highlighted in these experiments. Leaf area index, leaf area duration intercepted radiation and final utilisation efficiency were significantly affected by cultivar. In both seasons cv. T-49 reached maturity (dry seed) before Scylla, while unirrigated plants reached green pod maturity seven days before irrigated plants. Plants of cv. Scylla gave a final TDM of 730 g m⁻²; compared to the 530 g m⁻² produced by T-49. The average growth rate was 7.0 and 5.2 g m⁻² day⁻¹ for Scylla and T-49 respectively (2003-04). Plants receiving 150 kg N ha⁻¹ produced 665 g m⁻² TDM which was 12 % more than was produced by unfertilised plants. The application of 150 kg N ha⁻¹ gave an average growth rate of 6.4 g m⁻² day⁻¹ compared to 5.7 g m⁻² day⁻¹ from plants with no N. Inoculation in the field had no significant effect on TDM in both seasons. Temperature affected growth and DM accumulation. Accumulated DM was highly dependent on cumulative intercepted PAR. Air temperatures below the base temperature (10 °C) affected growth in 2004-05, resulting in plants accumulating just 0.24 g DM MJ⁻¹ PAR during early growth. This increased to 2.26 g DM MJ⁻¹ PAR when the temperature was increased above the base temperature. There was a strong relationship between LAI and intercepted PAR. A LAI of 4.0-4.5 was required to intercept 90-95 % of incident solar radiation. Cultivar significantly (p < 0.001) affected radiation use efficiency (RUE). Scylla had a RUE of 1.02 g DM MJ⁻¹ PAR compared to T-49 at 1.18 g DM MJ⁻¹ PAR. Seed yield was significantly (p < 0.001) affected by cultivar and fertiliser application. Cultivar Scylla produced 467 g m⁻² which was 76 % more than T-49, while a 12 % increase in seed yield was observed in N fertilised plants over unfertilised plants. Only cultivar significantly affected HI, while the yield components that had the greatest effect on seed yield were hundred seed weight and pods plant⁻¹. Inoculation significantly (p< 0.05) affected 100 seed weight (2004-05). Plants inoculated with strain H 20 had the highest 100 seed weight at 25.2 g with cv. Scylla producing larger seeds than T-49. The belief that local environmental conditions play a major role on field survival of bacteria, led to the use of PCR methods to identify field nodulating organisms. Amplification of genomic DNA from parent isolates using primers fC and rD generated a single band for each isolate. Isolates were identified to the species level as either Rhizobium or Agrobacterium, using the highly conserved internally transcribed spacer (ITS) region and are known to nodulate common bean. The DNA extracted from the isolates recovered from nodules of field grown beans gave multiple bands with primers fC and rD. Five distinct banding patterns were observed. All of these were different from those of parent isolates. Sequencing of the 16S rRNA demonstrated that nodules of field grown beans in Canterbury were inhabited by Pseudomonads either alone or in association with other root nodulating organisms. The inability to identify the inoculant strains in nodules of field grown beans does not rule out their infection and nodulating function in the cultivars used. The results suggest the possibility of both Rhizobium and Pseudomonads cohabiting in the nodules of field grown beans. The aggressive nature of Pseudomonads on artificial media, possibly out competing the inoculant rhizobia is proposed, leading to the inability to identify the inoculant strain from the nodules of the field grown beans by PCR methods. The need to identify the nodule forming or nodule inhabiting bacteria in the nodules is necessary to classify the importance of these organisms and their economic benefit to agricultural production. This study also underlines the importance of using PCR methods to gain valuable insights into the ecological behaviour of Rhizobium inoculants and nodule inhabiting organisms.

Agricultural management is essential for achieving optimum crop production and maintaining soil quality. Soil microorganisms are responsible for nutrient cycling and are an important consideration for effective soil management. The overall goal of the present research was to better understand microbial communities in agricultural soils as they relate to soil management practices. For this, we evaluated the differential impact of two contrasting drainage practices on microbial community composition and characterized active denitrifiers from selected agricultural sites. Field drainage is important for crop growth in arable soils. Controlled and uncontrolled tile drainage practices maintain water in the field or fully drain it, respectively. Because soil water content influences nutrient concentration, moisture, and oxygen availability, the effects of these two disparate practices on microbial community composition was compared in paired fields that had diverse land management histories. Libraries of the 16S rRNA gene were generated from DNA from 168 soil samples collected from eight fields during the 2012 growing season. Paired-end sequencing using next-generation sequencing was followed by read assembly and multivariate statistical analyses. Results showed that drainage practice exerted no measureable effect on the bacterial communities. However, bacterial communities were impacted by plant cultivar and applied fertilizer, in addition to sampled soil depth. Indicator species were only recovered for depth; plant cultivar or applied fertilizer type had no strong and specific indicator species. Among indicator species for soil depth (30-90 cm) were Chloroflexi (Anaerolineae), Betaproteobacteria (Janthinobacterium, Herminiimonas, Rhodoferax, Polaromonas), Deltaproteobacteria (Anaeromyxobacter, Geobacter), Alphaproteobacteria (Novosphingobium, Rhodobacter), and Actinobacteria (Promicromonospora). Denitrification in agricultural fields transforms nitrogen applied as fertilizer, reduces crop production, and emits N2O, which is a potent greenhouse gas. Agriculture is the highest anthropogenic source of N2O, which underlines the importance of understanding the microbiology of denitrification for reducing greenhouse gas emissions by altered management practices. Existing denitrifier probes and primers are biased due to their development based mostly on sequence information from cultured denitrifiers. To circumvent this limitation, this study investigated active and uncultivated denitrifiers from two agricultural sites in Ottawa, Ontario. Using DNA stable-isotope probing, we enriched nucleic acids from active soil denitrifiers by exposing intact replicate soil cores to NO3- and 13C6-glucose under anoxic conditions using flow-through reactors, with parallel native substrate controls. Spectrophotometric chemistry assays and gas chromatography confirmed active NO3- depletion and N2O production, respectively. Duplicate flow-through reactors were sacrificed after one and four week incubation periods to assess temporal changes due to food web dynamics. Soil DNA was extracted and processed by density gradient ultracentrifugation, followed by fractionation to separate DNA contributed by active denitrifiers (i.e., “heavy” DNA) from that of the background community (i.e., “light” DNA). Light and heavy DNA samples were analyzed by paired-end sequencing of 16S rRNA genes using next-generation sequencing. Multivariate statistics of assembled 16S rRNA genes confirmed unique taxonomic representation in heavy fractions from flow-through reactors fed 13C6-glucose, which exceeded any site-specific or temporal shifts in putative denitrifiers. Based on high relative abundance in heavy DNA, labelled taxa affiliated with the Betaproteobacteria (71%; Janthinobacterium, Acidovorax, Azoarcus, Dechloromonas), Alphaproteobacteria (8%; Rhizobium), Gammaproteobacteria (4%; Pseudomonas), and Actinobacteria (4%; Streptomycetaceae). Metagenomic DNA from the original soil and recovered heavy fractions were subjected to next-generation sequencing and the results demonstrated enrichment of denitrification genes with taxonomic affiliations to Brucella, Ralstonia, and Chromobacterium in heavy fractions of flow-through reactors fed 13C6-glucose. The vast majority of heavy-DNA-associated nitrite-reductase reads annotated to the copper-containing form (nirK), rather than the heme-containing enzyme (nirS). Analysis of recovered nirK genes demonstrated low sequence identity across common primer-binding sites used for the detection and quantification of soil denitrifiers, indicating that these active denitrifiers would not have been detected in molecular surveys of these same soils.

FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / A tese à composta por dois capÃtulos. O primeiro capÃtulo inclui o trabalho cujo objetivo foi investigar o potencial uso de pares de transcritos correlativos baseados em microarranjos como marcadores de fertilidade masculina usando a displasia da bainha fibrosa (DFS) como modelo afetado. Atualmente à bastante reconhecido que a tecnologia de microarranjos pode ser limitada pelos custos e que a qualidade dos transcritos permanece relativamente desconhecida. Para responder essas questÃes, nÃs analizamos pares de transcritos estÃveis por qPCR com um processo sistemÃtico de desenho de primers sistemÃtico. Nesse estudo experimental, nÃs utilizamos amostras de homens com fertilidade comprovada e de homens com diagnÃtico de DFS. Nossa abordagem foi baseada nas sequÃncias de primers dos seis genes de interesse, os quais foram desenhados utilizando os programas Oligo7 e Primer3Plus. A especificidade do primer foi inicialmente analisada in silico atravÃs de pesquisas nos bancos de dados ENSEMBL, University of California Santa Cruz (UCSC), e National Center for Biotechnology Information (NCBI) para uso de sequÃncias especÃficas aos genes alvos. A habilidade dos pares de transcritos em classificar as amostras de homens de fertilidade comprovada das amostras de DFS foi avaliada. Nossos resultados mostraram que em conjunÃÃo com a identificaÃÃo de quatro novos pares estÃveis, a comparaÃÃo dos coeficientes de correlaÃÃo dos valores de C(t) dos DSF revelou a interrupÃÃo de quatro pares estÃveis identificados nas amostras de homens normais. Esta seleÃÃo de pares estÃveis resolve a questÃo sobre a DSF. Em conclusÃo, os resultados mostram efetivamente que o desenho de primers e qPCR podem fornecer um ensaio molecular de baixo custo para avaliar a fertilidade masculina. O segundo capÃtulo divide-se em dois estudos e avalia em carneiros os efeitos de uma dieta suplementada com farelo de castanha de caju. No estudo 1, nosso objetivo foi detectar a presenÃa de transcritos para Heat Shock Protein (HSP70), clusterina (CLU), proteÃna semelhante à subunidade alfa do complexo T (TCP1) e proteÃna do complexo T subunidade 8 (CCT8) no espermatozÃide de ovinos, seguindo a mesma metodologia para qPCR utilizada no capitulo 1. As sequÃncias de primers foram desenhadas utilizando os programas Primer3Plus e Oligo Analyzer. Gene para protamina 2 (PRM2) foi usado como controle interno de reaÃÃo. O sÃmen foi coletado de machos pÃberes Morada Nova utlizando eletroejaculador. As amostras selecionadas para extraÃÃo de RNA espermÃtico seguiram as recomendaÃÃes do ColÃgio Brasileiro de ReproduÃÃo Animal quanto aos parÃmetros de motilidade, vigor e concentraÃÃo. Nossos resultados mostraram a presenÃa de mRNA para a HSP70 nos espermatozÃides de ovinos. Maiores estudos sÃo necessÃrios a fim de confirmar ou refutar a presenÃa das chaperonas TCP1 e CCT8 no espermatozÃide ovino. A presenÃa do transcrito da HSP70 no espermatozÃide de ovinos abre perspectivas para estudos futuros sobre os efeitos do mRNA HSP70 no desenvolvimento embrionÃrio, de modo a avaliar se essa expressÃo ocorre de modo espontÃneo, programado e seqÃencial, e se esses mecanismos se refletem na fertilidade e no desenvolvimento embrionÃrio. O segundo estudo tem como principal objetivo avaliar os efeitos de uma dieta contendo farelo de castanha de caju (FCC) na expressÃo de genes relacionados ao metabolismo dos lipÃdios no mÃsculo Longissimus dorsi de carneiros Morada Nova. Vinte carneiros maduros sexualmente foram divididos em dois grupos baseando-se no peso vivo. Os animais foram mantidos em baias individuais. Durante trÃs meses, o grupo castanha (GCA) foi alimentado com raÃÃo contendo FCC, enquanto o grupo controle (GCO) recebeu raÃÃo à base de milho e soja. As duas dietas eram isocalÃricas e isoprotÃicas, adicionadas de suplemento mineral. Os carneiros tambÃm receberam feno de Tifton e Ãgua à vontade. A quantidade de alimento ofertado (raÃÃo e feno) foi ajustada diariamente para sobra de 10%. Sete genes codificantes de proteÃnas envolvidas direta ou indiretamente foram selecionados como alvos, incluindo: GH, ACACA, CAST, CAPN3, LPL, SCD e FASN. Para normalizaÃÃo, foram selecionados cinco genes candidatos: ACTB, GAPDH, RPL4, RPS18 e TBP. Dentre os sete genes alvos selecionados anteriormente, os alvos GH, ACACA e CAST foram removidos. Os dois primeiros foram removidos devido amplificaÃÃo de alinhamento mÃltiplo (baixa especificidade do primers), enquanto CAST apresentou baixa eficiÃncia de amplificaÃÃo. Da lista de gene alvo final, a expressÃo de somente dois genes foi afetada pela dieta, SCD (p<0.01) e FASN (p<0.05), enquanto LPL (p=0,1022) e CAPN3 (p=0,0939) nÃo apresentaram diferenÃa significativa (p<0.05). Os genes SCD e FASN foram reprimidos no GCA comparada ao GCO. Este à o primeiro relato de que uma raÃÃo contendo FCC afetou a expressÃo gÃnica de proteÃnas envolvidas na deposiÃÃo de lipÃdios no mÃsculo em ovinos. Considerando que uma dieta contendo FCC altera a expressÃo de genes lipogÃnicos sem afetar o ganho de peso nem a eficiÃncia reprodutiva de ovinos, faz da castanha de caju uma importante alternativa para o sistema de produÃÃo de ovinos criados em regiÃes tropicais. / This thesis presents two chapters. In the first chapter, its objective was to investigate the potential use of correlative microarray-based transcript pairs as candidate markers for male fertility using dysplasia of the fibrous sheath (DFS) as an affected model. It is widely recognized that microarray technology may be limited by cost and that the quality of the transcript remains relatively unknown. To address these issues, we analyzed the stable transcript pairs by qPCR with a systematic primer design process. On this experimental study, we used men with proven fertility and men with a diagnosis of DFS. Our approach was based on primer sequences for six genes of interest were designed using Oligo7 and Primer3Plus. Primer specificity was initially assessed in silico by searching the ENSEMBL, University of California Santa Cruz, and National Center for Biotechnology Information databases for nontarget complementary sequences throughout the genome. The ability of transcript pairs to classify samples from males of proven fertility away from DFS was assessed. Our results showed that in conjunction with identifying four new stable transcript pairs, comparison of the DFS qPCR C(t) correlation coefficients revealed the disruption of four stable fertile sample transcript pairs. This suite of transcript pairs resolves DFS. In conclusion, the results show that with effectively designed primers, qPCR may provide an affordable molecular assay to assess male fertility status. Second chapter includes two studies regarding evaluations of ram feeded with supplemented diet with cashew nut. On the frist study, our goal was detect transcripts for Heat Shock Protein (HSP70), Clusterin (CLU), Ovis aries T-complex protein 1 alfa subunit-like protein (TCP1) e Ovis aries chaperonin containing TCP1, subunit 8 (theta) (CCT8) on ram sperm by. For primer designing we used published ESTs from NCBI and manually annotated by us using Primer3Plus and OligoAnalizer. PRM2 was used as internal qPCR control. Semen samples from mature Morada Nova ram were collected by eletroejaculator, washed in PBS and prepared for further RNA extraction. Selected samples followed quality recommendatios from ColÃgio Brasileiro de ReproduÃÃo Animal regarding motility, vigor and concentration. Our results showed presence of mRNA HSP70 on ram sperm and they can possible be envolved in early embryo development, oocyte activation and post fertilization events. Further analyses will be necessary to confirm presence of TCP1 and CCT8 on ram sperm. Our findings indicate new perpectives about the effects of these chaperones during embryo development mesuring if its expression reflects male fertility on the early embryo development. On the second study the the main goal is to evaluate the effects of a lipid-enriched diet containing cashew nut brain on the expression of genes related to lipid metabolism in the longissimus dorsi muscle of Morada Nova rams. Twenty sexually mature and reproductively sound rams were divided in two groups based on ram live weight, and each ram was kept on individual pens. During three months, group 1 (G1) rams were fed with a lipid-rich diet, containing cashew nut bran (CNB), while group 2 (G2) was fed with a meal based on corn and soy. Both diets were isocaloric and isoproteic, and had a mineral mix added-in. The rams also were offered Tifton grass hay and had free access to water. The amount of diet offered (ration plus hay) was adjusted everyday to a maximum waste of 10%. Seven genes coding for proteins directly or indirectly involved in lipid metabolism were initially selected as targets, incluiding GH, ACACA, CAST, CAPN3, LPL, SCD, and FASN. Also, five genes were selected as reference genes, ACTB, GAPDH, RPL4, RPS18 and TBP. From the seven genes originally selected as targets, GH, ACACA and CAST were removed, leaving the final list with four targets. The first two genes were removed due to alternative pairing of the primers (low specificity), while CAST showed low amplification efficiency during PCR reaction. From the final target list, the expression of only two genes was affected by diet, SCD (p<0.01) and FASN (p<0.05), while LPL (p=0,1022) and CAPN3 (p=0,0939) were not different at the p<0.05 level. Both SCD and FASN genes were down-regulated in G1 (lipid-rich diet containing CNB) compared to G2. These genes are involved in lipogenic pathways, related to tissue lipid deposition; therefore, these results were expected. This is the first time that a fat-rich diet based on CNB was shown to affect gene expression of proteins involved in fat deposition in carcass muscles of rams. Longissimus dorsi is one of the finest meat cuts. Considering that human diets rich in poli-unsaturated fatty acids (PUFA) can decrease the risk of heart and other chronic diseases, a change in the fatty acid profile of this muscle could contribute to a healthier diet, aggregating value to the end-product of the lamb meat market. The effects of CNB-based diet on the gene expression of SCD and FASN support the notion that such diet, as previously shown for other sources of lipid in ruminants, can potentially change the fatty acid composition of L. dorsi, but this hypothesis needs to be experimentally verified by profiling fatty acids in animals fed CNB versus carbohydrate-based diets. CNB use as an ingredient in animal feeding is environmentally-friendly, since it contributes to by-product recycling from the agroindustrial plants in Northeast Brazil. Also, considering that CNB-based diet changes lipogenic gene expression without affecting weight gain or reproductive status of the rams, as shown in another work from our team, makes CNB a very important alternative food in ram production systems in tropical regions.