Ultrastructure of neurosecretory granules in the sinus gland of Palaemon serratus Pennant]

Five types secretory granules are distinguished in the sinus gland of Palaemon serratus on the basis of differences in their diameter and their electron density. Variations in the density of the acoplasm and of the granules are observed for three of these granule types.     

In vitro protein synthesis and alpha amylase activity in F cells from hepatopancreas of Palaemon serratus (Crustacea; Decapoda).

In crustaceans, all the steps in the assimilation of food take place in the hepatopancreas. To facilitate the study of this organ, a method for the dissociation of cell types was developed. The hepatopancreas of the prawn Palaemon serratus was mechanically dissociated and the cells separated by Percoll density-gradient centrifugation. The E and R cells had similar densities of around 1.05 g/ml. The F cells were separated into two distinct fractions with densities of 1.075 and 1.082 g/ml. The B cells sedimented at a density of 1.12 g/ml. The ratio between the two populations of F cells was found to vary during the intermolt cycle while B cells disappeared after the molt. When the density gradient fractions were incubated with 3H-leucine, incorporation was highest in the F cell fractions. Measurements of alpha-amylase activity, indicated that the two populations of F cells may be derived from the same cell type.     

Partial characterization of human pancreatic carboxypeptidase A

Zusammenfassung Es sind einige physikochemische Eigenschaften der im menschlichen Pankreas in geringer Menge erhaltenen 2 Carboxypeptidasen A untersucht worden. Gewisse Unterschiede zu den Bovin- und Porcin-Carboxypeptidasen konnten festgestellt werden.     

Inhibitory effects of LHRH on LH receptors in the rat testis]

A single injection of LHRH to the adult male rat, as of its analog [D-Ala6, des-Gly-NH102] LHRH ethylamide, resulted in a marked decrease in LH receptors in the tests. Plasma testosterone level and the weight of the seminal vesicles and prostate were also decreased after treatment. These data demonstrate that LHRH can decrease the sensitivity of LH receptors and testicular function in the rat.     

Partial purification and characterization of acid phosphatase from sporulated oocysts ofEimeria tenella

Summary Acid phosphatase ofEimeria tenella oocysts (Peak II) was purified 77-fold with a recovery of 26% using protamine sulfate precipitation, DEAE-cellulose chromatography and Sephadex G-200 gel filtration. This enzyme occurs in multiple forms as indicated by two peaks which can be separated by DEAE-cellulose chromatography and polyacrylamide gel electrophoresis. The partially purified enzyme has optimal activity at pH 4.5. With p-nitrophenyl phosphate the Km and V_max values for (Peak II) were 25 mM and 1.57 mol/min/mg protein, respectively. The enzyme (Peak II) ist strongly inhibited by Hg⁺⁺, Cu⁺⁺, iodoacetamide, fluoride and molybdate. Tartrate and other divalent metal ions have no effect on enzyme activity. The partially purified Peak II phosphatase is not a glycoprotein as it is not absorbed on concanavalin-A Sepharose and its treatment with bacterial neuraminidase does not alter its elution profile through DEAE cellulose.     

Partial purification and characterization of acid phosphatase from sporulated oocysts of Eimeria tenella

Acid phosphatase of Eimeria tenella oocysts (Peak II) was purified 77-fold with a recovery of 26% using protamine sulfate precipitation, DEAE-cellulose chromatography and Sephadex G-200 gel filtration. This enzyme occurs in multiple forms as indicated by two peaks which can be separated by DEAE-cellulose chromatography and polyacrylamide gel electrophoresis. The partially purified enzyme has optimal activity at pH 4.5. With p-nitrophenyl phosphate the Km and Vmax values for (Peak II) were 25 mM and 1.57 mumol/min/mg protein, respectively. The enzyme (Peak II) is strongly inhibited by Hg++, Cu++, iodoacetamide, fluoride and molybdate. Tartrate and other divalent metal ions have no effect on enzyme activity. The partially purified Peak II phosphatase is not a glycoprotein as it is not absorbed on concanavalin-A Sepharose and its treatment with bacterial neuraminidase does not alter its elution profile through DEAE cellulose.     

Cadmium-induced lipofuscins and effect of zinc on hepatopancreas cells inIdotea baltica

Histological investigation revealed cadmium-induced lipofuscin formation in hepatopancreatic cells of the crustacean isopod,Idotea baltica. A comparison of lipofuscin induction by cadmium and by copper showed that cadmium has a weaker peroxidative action than copper. The effect of cadmium was reduced by the simultaneous presence of zinc, which on its own was ineffective in lipofuscin induction. A tentative explantation of the interactive effects of these materials is suggested.     

The role of histones and their modifications in the informative content of chromatin

It is traditionally accepted that the DNA sequence cannot by itself explain all the mechanisms necessary for the development of living beings, especially in eukaryotes. Indeed part of the information used in these processes is stored in other ways, generally called epigenetic, whose molecular mechanisms are mostly unknown. The ultimate explanation for them might reside in the non-DNA moiety of chromatin which may play an active role in heredity (chromatin information). Histones are the universal structural component of chromatin. However, recent studies strongly suggest that histones, and their modifications — especially the reversible acetylation of lysines — may act as a recognition signal for regulatory proteins and they may participate, for this reason, in gene regulation. This type of information could be maintained through its replication and, ultimately, it could form the molecular basis of certain processes related to the development of the eukaryotic organisms.     

Inhibition of post-hemicastration hypertrophy of the remaining testis by testosterone or aqueous testicular extract treatments in the young rat]

In the 10 day old hemicastrated Rat daily injections of testosterone (total doses of 0.04 to 4 mg/Rat) or of proteinaceous extract of Rat testis (4 mg/Rat) inhibit compensatory hypertrophy of the remaining testis. Both testosterone and testicular proteinaceous extract could be involved in the growing processes of the testis, locally or by means of modification of gonadotropin secretion. Results have been analysed by covariance analysis to eliminate the influence of body weight variations.     

Localization of the exogenous fluorescent histones in Ehrlich Ascites tumour cells

Résumé Les auteurs ont étudié la localisation des histones fluorescents dans des cellules tumereuses d'ascites Ehrlich soumises à l'incubation in vitro avec les dérivés fluorescents de l'histone de thymus bovin ou avec quelques fractions du même histone. Ils ont démontré qu'après une incubation de courte durée les histones ont été adsorbés sur la surface des cellules, tandis que lors d'une incubation de longue durée les histones ont réussi à pénétrer dans les cellules.     

The effect of gonadotropic hormones and the fetal hypophysis on testosterone production by the testis of 18 day mouse fetuses in organ culture]

The production of testosterone (measured by radioimmuno-assay) by the 18-day-old mouse fetal testis may be stimulated specifically by ovine LH (1 ng, p less than 0.005) and HCG in organ culture. A stimulation by FSH is observed only with high doses (10 mug, p less than 0.0005). Prolactin and ACTH have no effect. Age-matched fetal pituitaries increase significantly the testosterone production in the culture medium (p less than 0.0005).     

On the storage and mobilization of organic resources in the hepatopancreas of a crab (Paratelphusa hydrodromus)

Résumé Etude des changements cycliques observés dans les hydrates de carbone et les lipides contenus dans l'hépatopancreas du crabeParatelphusa hydrodromus pendant le cycle de mue.