No description available.

I conducted an integrative field study on male cottonmouths (Agkistrodon piscivorus), a common pitviper of the southeastern United States, to investigate the evolution of contrasting mating patterns in North American pitvipers (bimodal and unimodal annual patterns) and resolve conflicting information about the pattern exhibited by the cottonmouth. I determined a unimodal late summer peak of testosterone (T) and a muted unimodal seasonal cycle of the sexual segment of the kidney (a secondary sexual characteristic), both of which were correlated with the single peak of spermatogenesis in late summer. I also conducted a study to determine diel and seasonal variation of corticosterone (CORT), the effect of captive handling on CORT, and the relationship between CORT and T after captive handling, and detected a significant elevation of CORT and a significant decrease of T after capture in male cottonmouths, as well as a significant negative correlation between CORT and T.

Made available in DSpace on 2015-03-26T13:47:03Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1384970 bytes, checksum: 7a9f338f36b2878167408065484d1268 (MD5) Previous issue date: 2012-02-09 / O estudo da morfologia testicular e do processo espermatogênico em animais silvestres são fundamentais para o conhecimento dos padrões fisiológicos, auxiliando assim no estabelecimento de protocolos em reprodução assistida. Os objetivos deste estudo foram descrever a duração do ciclo do epitélio seminífero pela identificação das células germinativas mais avançadas marcadas pela 5-bromodeoxiuridina (BrdU); caracterizar os diversos estádios que constituem o ciclo do epitélio seminífero com base na associação das técnicas de morfologia tubular e desenvolvimento do sistema acrossômico; calcular a produção espermática diária por grama de testículo de jaguatirica (Leopardus pardalis). Para isso, foram utilizados cinco animais machos adultos provenientes do Centro de Triagem de Animais Silvestres da Universidade Federal de Viçosa e da Fundação Zoobotânica de Belo Horizonte, ambas em Minas Gerais, Brasil. Os animais foram submetidos a biópsias testiculares a fim de se obter material biológico para avaliação histológica e imunohistoquímica. Foram descritos e determinada a frequência relativa de oito estádios do ciclo do epitélio seminífero em jaguatirica com base no método da morfologia tubular associado ao método do sistema acrossômico. Foi observado um estádio do ciclo por secção transversal de túbulo sendo a fase pré meiótica do processo espermatogênico maior que as outras (56,5%). Através do uso de um marcador de proliferação celular injetado intratesticularmente (BrdU) foi observado após 16 dias de aplicação, células marcadas em transição de paquíteno para diplóteno no início do estádio III. A partir daí, pode-se concluir que um ciclo do epitélio seminífero de jaguatirica dura 11,30 dias, assim o processo espermatogênico da jaguatirica dura no total 50,85 dias. A jaguatirica apresentou diâmetro médio de túbulos seminíferos de 211,37μm e 17,81 metros por grama de testículo em média. No epitélio seminífero, em cada secção transversal do túbulo seminífero no estádio I do ciclo, foi observado em média 1,06 espermatogônias do tipo A; 17,78 espermatócitos primários em pré-leptóteno/leptóteno; 19,22 espermatócitos primários em paquíteno; 59,5 espermátides arredondadas e 6,86 células de Sertoli. O rendimento geral da espermatogênese nesta espécie foi de aproximadamente 57 células, e cada célula de viiiSertoli foi capaz de sustentar e manter 14,38 células da linhagem germinativa das quais, 8,76 espermátides arredondadas. A produção espermática diária encontrada demonstra que a jaguatirica é um animal com alto nível de produção, uma vez que sua produção é cerca de 32 milhões de espermatozóides por grama de testículo. / The study of testicular morphology and spermatogenic process in wild animals are fundamental to the knowledge of physiological patterns, thus assisting in establishing protocols for assisted reproduction. The objectives of this paper were to describe the cycle of the seminiferous epithelium by identifying the most advanced germ cells marked by 5-bromodeoxyuridine (BrdU); to characterize the various stages that constitute the cycle of the seminiferous epithelium based on the combination of the techniques of tubular morphology and development of the acrosomal system, calculate the daily sperm production per gram of testis of ocelot (Leopardus pardalis). For this, we used five adult males from Centro de Triagem de Animais Silvestres at Universidade Federal de Viçosa and from Fundação Zoobotânica de Belo Horizonte, both in Minas Gerais, Brazil. The animals underwent testicular biopsies in order to obtain biological material for histology and immunohistochemistry. We described and determined the relative frequency of eight stages of the seminiferous epithelium cycle on the ocelot based in the tubular morphology method associated with the acrosomal system method. We observed one stage of the cycle by tubule cross-section, being that the pre-meiotic spermatogenic process is longer than the others (56.5%). Through the use of a cell proliferation marker intratesticularly injected (BrdU) we observed after 16 days of application, labeled cells in transition from pachytene to diplotene at the beginning of stage III. From there, we can conclude that a cycle of the seminiferous epithelium of ocelot takes 11.30 days, so the ocelot spermatogenesis process lasts 50.85 days. The ocelot had an average diameter of seminiferous tubules of 211.37 μm and 17.81 meters per gram of testis on average. In the seminiferous epithelium, in each cross-section of seminiferous tubule in stage I of the cycle, we observed on average 1.06 type A spermatogonia, 17.78 primary spermatocytes in pre-leptotene/leptotene, 19.22 primary spermatocytes in pachytene, 59.5 round spermatids and 6.86 Sertoli cells. The overall yield of spermatogenesis in this species was approximately 57 cells, and each Sertoli cell was able to sustain and maintain 14,38 germline cells of which 8.76 were round xspermatids. The daily sperm production found shows that the ocelot is an animal with a high level of production, since production is about than 32 million sperm per gram of testis. / Solicitado sigilo pela orientadora em 30/11/2012

No description available.

Yes / In vivo tests for male reproductive genotoxicity are time consuming, resource-intensive and their use should be minimised according to the principles of the 3Rs. Accordingly, we investigated the effects in vitro, of a variety of known, phase-specific germ cell mutagens, i.e. pre-meiotic, meiotic, and post-meiotic genotoxins, on rat spermatogenic cell types separated using Staput unit-gravity velocity sedimentation, evaluating DNA damage using the Comet assay. N-ethyl-N-nitrosourea (ENU), N-methyl-N-nitrosourea (MNU) (spermatogenic phase), 6-mercaptopurine (6-MP) and 5-bromo-2'-deoxy-uridine (5-BrdU) (meiotic phase), methyl methanesulphonate (MMS) and ethyl methanesulphonate (EMS) (post-meiotic phase) were selected for use as they are potent male rodent, germ cell mutagens in vivo. DNA damage was detected directly using the Comet assay and indirectly using the TUNEL assay. Treatment of the isolated cells with ENU and MNU produced the greatest concentration-related increase in DNA damage in spermatogonia. Spermatocytes were most sensitive to 6-MP and 5-BrdU while spermatids were particularly susceptible to MMS and EMS. Increases were found when measuring both Olive tail moment (OTM) and % tail DNA, but the greatest changes were in OTM. Parallel results were found with the TUNEL assay, which showed highly significant, concentration dependent effects of all these genotoxins on spermatogonia, spermatocytes and spermatids in the same way as for DNA damage. The specific effects of these chemicals on different germ cell types matches those produced in vivo. This approach therefore shows potential for use in the detection of male germ cell genotoxicity and could contribute to the reduction of the use of animals in such toxicity assays.

No / Genotoxic agents can interact with DNA in germ cells possibly resulting in a heritable trait (germline mutation). Thus, in vitro male germ cell tests, which can detect phase specificity of such agents, could be used by regulatory agencies to help evaluate the potential risk of mutation. The male germ cell system now has a well-established model for studying phase specificity using the STA-PUT velocity sedimentation. On treatment with genotoxic agents, differences in chemical structure and metabolic differences in types of male germ cell lead to differing susceptibilities to genotoxicity, so careful investigation is required for phase specificity. This can yield valuable information about the potential mechanisms involved in the genotoxicity responses and thus increase the significance of the findings. This is especially important because mutations induced in the germline could also affect future generations. In this chapter, we briefly review the field of the male germ cell DNA damage response.