Cold-inducible RNA-binding protein (Cirp) was the first cold-shock protein identified in mammals. It is structurally quite different from bacterial cold-shock proteins and is induced in response to mild, but not severe, hypothermia. To clarify the physiological function of Cirp in vivo, we produced cirp-knockout mice. They showed neither gross abnormality nor defect in fertility, but the number...

The identity and behavior of mouse spermatogenic stem cells have been a long-standing focus of interest. In the prevailing "As model," stem cell function is restricted to singly isolated (As) spermatogonia. By examining single-cell dynamics of GFRα1+ stem cells in vivo, we evaluate an alternative hypothesis that, through fragmentation, syncytial spermatogonia also contribute to stem cell functi...

Recent studies detailed the spermatogenic cycle of the Western Cottonmouth Snake, Agkistrodon piscivorus and noted that spermatogenesis is bimodal, with active periods during March-June and August-October in southeastern Louisiana. However, only spermatogonia were present in September in the only specimen that was captured and the authors state that the individual "should have a high testis vol...

The effect of endosulfan, an Organochlorine pesticide, on bluegill testes was studied. Endosulfan is aqua-toxic and has an immediate effect on fish and other aquatic life. In this experiment, we exposed the fish for 24-, 48-, 72-, 96-h, and 1- and 2-week periods. A second group of fish without exposure to endosulfan served as the control. The control testis appeared structurally normal. The sem...

Male fertility is declining and an underlying cause may be due to environment-epigenetic interactions in developing sperm, yet nothing is known of how the epigenome controls gene expression in sperm development. Histone methylation and acetylation are dynamically regulated in spermatogenesis and are sensitive to the environment. Our objectives were to determine how histone H3 methylation and ac...

Spermatogonial stem cells (SSCs) maintain spermatogenesis throughout adulthood through balanced self-renewal and differentiation, yet the regulatory logic of these fate decisions is poorly understood. The transcription factors Sal-like 4 (SALL4) and promyelocytic leukemia zinc finger (PLZF; also known as ZBTB16) are known to be required for normal SSC function, but their targets are largely unk...

The effects of genotoxic substances on ecosystems should be assessed using various test systems with multiple genetic end points. The most widely used test system has been the specific-locus test developed by W.L. Russell, using the mouse. We are developing a new, nonmammalian test system using the Japanese medaka, Oryzias latipes. We have examined 625,926 embryos that correspond to 1,586,649 l...

We have identified and purified TH3, a germ cell-specific histone. It has been characterized by amino acid analysis, tryptic peptide mapping, labeling with cystine, and by electrophoretic mobility as a variant of H3. On fully reduced Triton/acid/urea gels its mobility is retarded more than that of the somatic variants H3.2 and H3.3, but less than that of H3.1; it migrates between the H2As and H...

Ultrastructural observations of spermatogenesis and sperm development of Saccocoelioides godoyi, an intestinal parasite of Leporinus friderici (Bloch, 1794) are described. The irregular-shaped spermatogonia form a peripheral layer, and show a prominent nucleus. Spermatocytes are larger than spermatogonia, and in the early stage present synaptonemal complex. Spermatids show nuclei smaller than t...

Effects of adrenalectomy and administration of gonadotropins on cell counts of different cell types of spermatogenesis and morphology of the Leydig cells were studied in 30 day old mice. Adrenalectomy (duration, 12 days; age at autopsy 42 days) caused a significant decrease in the diameters of seminiferous tubules and Leydig cell nucleus and, cell counts of intermediate spermatogonia, round and...