separation-spermatogenic-cell-types-using-sta-put-velocity

Separation of Spermatogenic Cell Types Using STA-PUT Velocity Sedimentation

Mammalian spermatogenesis is a complex  differentiation process that occurs in several stages in the seminiferous  tubules of the testes. Currently, there ...

University of Pennsylvania

Male rats demonstrate persistent endothelium-dependent attenuation of vasoconstrictor reactivity following chronic hypoxia (CH). Since estrogen may interfere with hypoxia-induced gene expression, we hypothesized that gender differences exist in this response to CH. However, in conscious, instrumented rats, we found that CH resulted in a similar persistent reduction of pressor/total peripheral resistance responses to phenylephrine (PE) in rats of both genders. In contrast, although previous studies show mesenteric vascular responses to PE are reduced in CH males, we found that mesenteric reactivity was maintained in CH females. Since normoxic females demonstrate greater nitric oxide (NO) production, we hypothesized that the failure of CH to further diminish mesenteric reactivity in females was due to the inhibition of NO-dependent vasodilation. To test this hypothesis, constrictor reactivity of mesenteric arteries from male and female rats was examined. NO synthase (NOS) inhibition augmented constrictor responses to PE in arteries from both normoxic and CH males and normoxic females. In contrast, NOS inhibition had no effect in CH female vessels. Endothelial NOS (eNOS) levels were not different in arteries from control and CH females. Endothelial [Ca2+]i was greater in arterioles from CH females. Thus, CH reduces NO-dependent mesenteric dilation in females; this effect is not due to altered eNOS levels or diminished endothelial [Ca2+]i.

Gender differences in mesenteric vasoconstrictor reactivity following chronic hypoxia.

The differentiation of gametes involves dramatic changes to chromatin, affecting transcription, meiosis, and cell morphology. Sporulation in Saccharomyces cerevisiae shares many chromatin features with spermatogenesis, including a 10-fold compaction of the nucleus. To identify new proteins involved in spore nuclear organization, we purified chromatin from mature spores and discovered a significant enrichment of the linker histone (Hho1). The function of Hho1 has proven to be elusive during vegetative growth, but here we demonstrate its requirement for efficient sporulation and full compaction of the spore genome. Hho1 chromatin immunoprecipitation followed by sequencing (ChIP-seq) revealed increased genome-wide binding in mature spores and provides novel in vivo evidence of the linker histone binding to nucleosomal linker DNA. We also link Hho1 function to the transcription factor Ume6, the master repressor of early meiotic genes. Hho1 and Ume6 are depleted during meiosis, and analysis of published ChIP-chip data obtained during vegetative growth reveals a high binding correlation of both proteins at promoters of early meiotic genes. Moreover, Ume6 promotes binding of Hho1 to meiotic gene promoters. Thus, Hho1 may play a dual role during sporulation: Hho1 and Ume6 depletion facilitates the onset of meiosis via activation of Ume6-repressed early meiotic genes, whereas Hho1 enrichment in mature spores contributes to spore genome compaction.

Article	Year
Gender differences in mesenteric vasoconstrictor reactivity following chronic hypoxia. Microcirculation (New York, N.Y. : 1994)\| PubMed ID: 19086257	2008
The linker histone plays a dual role during gametogenesis in Saccharomyces cerevisiae. Molecular and cellular biology\| PubMed ID: 22586276	2012
Low-hanging fruit: targeting Brdt in the testes. The EMBO journal\| PubMed ID: 22960636	2012

Jessica M Bryant

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