A Genome-wide Screen for Neurospora crassa Transcription Factors Regulating Glycogen Metabolism

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Transcription factors play a key role in transcription regulation as they recognize and directly bind to defined sites in promoter regions of target genes, and thus modulate differential expression. The overall process is extremely dynamic, as they have to move through the nucleus and transiently bind to chromatin in order to regulate gene transcription. To identify transcription factors that affect glycogen accumulation in Neurospora crassa, we performed a systematic screen of a deletion strains set generated by the Neurospora Knockout Project and available at the Fungal Genetics Stock Center. In a wild-type strain of N. crassa, glycogen content reaches a maximal level at the end of the exponential growth phase, but upon heat stress the glycogen content rapidly drops. The gene encoding glycogen synthase (gsn) is transcriptionally down-regulated when the mycelium is exposed to the same stress condition. We identified 17 deleted strains having glycogen accumulation profiles different from that of the wild-type strain under both normal growth and heat stress conditions. Most of the transcription factors identified were annotated as hypothetical protein, however some of them, such as the PacC, XlnR, and NIT2 proteins, were biochemically well-characterized either in N. crassa or in other fungi. The identification of some of the transcription factors was coincident with the presence of DNA-binding motifs specific for the transcription factors in the gsn 5'-flanking region, and some of these DNA-binding motifs were demonstrated to be functional by Electrophoretic Mobility Shift Assay (EMSA) experiments. Strains knocked-out in these transcription factors presented impairment in the regulation of gsn expression, suggesting that the transcription factors regulate glycogen accumulation by directly regulating gsn gene expression. Five selected mutant strains showed defects in cell cycle progression, and two transcription factors were light-regulated. The results indicate that there are connections linking different cellular processes, such as metabolism control, biological clock, and cell cycle progression. Molecular & Cellular Proteomics 10: 10.1074/mcp.M111.007963, 1-13, 2011.1011Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Histomorphometric evaluation of the Molossus molossus (Chiroptera, Molossidae) testis: The tubular compartment and indices of sperm production

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Insectivorous bats play a very important role in the regulation of tropical ecosystems, but information about their reproductive cycle is lacking. Thus, male Molossus molossus were captured over the four seasons, and morphometric analyses of their testes were conducted to infer on the gonadal dynamics and the reproductive capacity of the species. Testes were immersed in Karnovsky fixative, and fragments were embedded in methacrylate and paraplast for morphometric and TUNEL assay respectively. The least gonadosomatic index (0.3%), tubulesomatic index (0.2%) and tubular diameter (133.2 mu m) occurred in summer. An adult M. molossus showed a total average of 48.9 m of seminiferous tubules per gram of testis. Primary spermatocytes were observed in the zygotene at Stage I of the seminiferous epithelium cycle. The greatest meiotic index was obtained in winter (3.8 cells), and the general yield of spermatogenesis was higher in winter (64.5 cells) than in summer (19.1 cells). There was no difference in the apoptotic cells count among seasons. The Sertoli cell index was less in summer (5.9) than in fall (11.6), while the number of Sertoli cells per gram of testis did not vary significantly among the seasons (28.0 x 10(7)). The spermatic reserve per gram of testis was greater in the fall (63.9 x 10(7)) and winter (69.8 x 10(7)) than summer (37.1 x 10(7)). We conclude that M. molossus males show a continuous reproductive cycle, featuring greater spermatogenic activity during the fall and winter, a tubular length above the average of other mammals and a less support capacity of the Sertoli cells. (C) 2013 Elsevier B.V. All rights reserved.14041732268278Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Ministry of Education of BrazilFundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP