Annual cycle of plasma testosterone and thyroxine in the European badger (Meles meles L.)]

In the male European Badger there are important variations in the plasma testosterone and thyroxine levels during the annual cycle. During the summer, plasma testosterone concentrations are low while plasma thyroxine rises to a very high level. In winter, when the thyroid activity is minimal, testicular activity increases. From February to May, the plasma testosterone remains at a high level, and then, after a sudden fall, a second peak occurs in June at which time the concentration of thyroxine is low.     

Seasonal variations in the nyctohemeral rhythm of plasma testosterone in the European badger Meles meles L

In the badger a seasonal sexual rhythm of the plasma testosterone is observed. There is also a nycthemeral rhythm of the testosterone secretion; during the regressed period of the testis this rhythm is bimodal with testosterone peaks during the light phase of the day; during the active period and "activity rhythm" with many transitorys peaks during the dark phase is added.     

β-glucuronidase activity in the liver of infant mammals

Zusammenfassung Niedrige Leber--Glucuronidase (Phenolphthaleinglucuronid-Substrat) neugeborener Ratten steigt in der dritten Woche auf Erwachsenenwerte. Die Aktivität sinkt bei Meerschweinchen von der Geburt an, steigt bei Kaninchen zwischen Geburt und drittem Lebenstag und zeigt bei Mäusen während der postnatalen Entwicklung geringe Schwankungen.     

Characterization and localization of the rat,mouse and human testicular phosphatidylethanolamine binding protein

A cytosolic 23kDa protein was initially puified from bovine brain and shown to bind phosphatidylethanolamine. Later, it was also characterized in rat and human brain, and it is now known to be widespread, having been found in numerous tisues in several species. Here, we report the high level of mRNA and phosphatidyl ethanolamine binding protein expression in rat testis and to a lesser extent mouse testis. In human testis, although it was not detectable by Northern blot analysis, the mRNA was shown be present when PCR amplificatin was performed. Immunohistochemical experiments revealed that the testicular phosphatidylethanolamine binding protein (tPBP) is principally expressed in the elongated spermatids of both rat and mouse testis. This finding, and the association of tPBP with cellular membranes, suggest its possible implication in membrane remodelling during spermatid maturation.     

Dopamine regulation of testicular activity in intact and hypophysectomized frogs,Rana esculenta

In intact frogs, both GnRHA and L-dopa were able to increase testicular and plasma androgen levels and to induce spermiation. The dopamine antagonist pimozide inhibited both the effects of L-dopa but not those of GnRHa. Hypophysectomy reduced androgen levels, but spermiation was still induced by both GnRHa and L-dopa, suggesting that these agents can directly influence the testis through a route not involving the pars distalis. Again, pimozide antagonised spermiation induced by L-dopa but not that induced by GnRHa.This work was supported (40% and 60%) by the Italian Ministry of Education and the C.N.R. Special Project.     

Effects of N2, O2'-dibutyril cyclic GMP on the nucleoside phosphotransferase activity of the retina of the chick embryos.

In the retina of the chick embryo, 2 different forms of nucleoside phosphotransferase take part in the phosphorylation of thymidine. One is an unstable form with higher molecular weight. The other with lower m. wt is a stable form. This paper shows that N2,O2'-dibutyril cyclic GMP causes a marked decrement of the activity of the unstable nucleoside phosphotransferase.     

Ontogenetic changes in relative levels of cyclic AMP-dependent and cyclic GMP-dependent protein kinases in prostates,epididymides and testes from guinea-pigs

Summary Changes in realtive levels of cyclic AMP-dependent protein kinase (A-PK) and cyclic GMP-dependent protein kinase (G-PK) in prostates, epididymides and testes from guinea-pigs were examined at 3 different ages. During postnatal development, a decrease in the ratio of the 2 classes of protein kinases was seen in prostates, whereas increases of the ratios of the enzymes were found in epididymides and testes.Acknowledgments. This work was supported by grant RR-08199 from the National Institutes of Health, USA. The authors thank Dr J.F. Kuo, in whose laboratory part of this work was performed, for his great advice.Undergraduate trainee of Minority Biomedical Support.     

Ontogenetic changes in relative levels of cyclic AMP-dependent and cyclic GMP-dependent protein kinases in prostates, epididymides and testes from guinea-pigs.

Changes in relative levels of cyclic AMP-dependent protein kinase (A-PK) and cyclic GMP-dependent protein kinase (G-PK) in prostates, epidymides and testes from guinea-pigs were examined at 3 different ages. During postnatal development, a decrease in the ratio of the 2 classes of protein kinases was seen in prostates, whereas increases of the ratios of the enzymes were found in epididymides and testes.     

Influences of light on activity of the small mammals,Peromyscus spp.,Tamias striatus,andMustela rixosa

Zusammenfassung Die Aktivität des Backenhörnchens (Tamias striatus) und des Wiesels (Mustela rixosa) wurde im Laufrad bei künstlicher Dämmerung und abruptem Tag-Nacht-Wechsel untersucht. Sowohl die Geschwindigkeit als auch die gesamte Laufzeit war bei diesen Tieren genau wie bei nachtaktiven Mäusen (GattungPeromyscus) von der Beleuchtungsstärke abhängig. Die Bedeutung dieser Befunde für das zirkadische Gesetz und die Evolution von Tages- und Nachtaktivität wird diskutiert.     

Influence of testicular fluid, spermatozoa and androgens on physiological activity of rat epididymis]

By ligation of the efferent duct and the corpus epididymis, the GPC concentration in this delimited anterior region decreased. However, HCG infection increased the GPC concentration. When spermatozoa are present in the epididymal tubule there is always a decrease in GPC concentration in these experimental conditions. Activity of the epididymis is disturbed by ligation.     

Evidence of protein kinase activity in 2 murine oncornaviruses]

A protein kinase activity has been detected in two strains of murine Oncornaviruses, MSV/MLV and EFV. This activity phosphorylates not only endogenous viral proteins but also exogenous substrates (histones and phosvitin). The stimulation of enzyme activity by detergents along with the increase of specific activity in viruses treated with trypsin during purification suggest that the enzyme is located in the viral particle.