Induction of Cellular Deoxyribonuleic Acid Synthesis by Simian Virus 40

The incorporation of (3)H-thymidine ((3)H-dT) into deoxyribonucleic acid (DNA) has been studied in uninfected confluent monolayer cultures of monkey kidney and mouse kidney cells, simian virus 40 (SV40)-infected cells, and in SV40-transformed mouse kidney cells. Radioautographic measurements revealed that during the period from 28 to 51 hr after productive SV40 infection of monkey kidney cultures about 80% of the cells synthesized DNA, compared to about 16% in uninfected cultures. At 28 to 43 hr after abortive SV40 infection of mouse kidney cultures, 24 to 37% of the cells synthesized DNA, compared to about 6 to 8% in uninfected cultures. The infected monkey kidney and mouse kidney cultures, respectively, incorporated about 5 to 10 times and 3 to 5 times as much (3)H-dT into DNA as did uninfected cultures. Moreover, the net DNA synthesized by SV40-infected monkey kidney cultures, estimated by colorimetric methods, substantially exceeded that of uninfected cultures.Nitrocellulose chromatography and band centrifugation experiments were performed to elucidate the kinds of DNA synthesized in the cultures. In uninfected monkey kidney cultures and at 2 to 12 hr after SV40 infection, almost all of the (3)H-dT labeled DNA sedimented more rapidly than SV40 DNA, and the radioactive DNA was denatured by heating for 12 min at 100 C (cellular DNA). Almost all of the labeled DNA obtained from abortively infected mouse kidney cultures and from SV40-transformed cells also had the properties of cellular DNA. However, approximately one-third to one-half of the labeled DNA obtained from monkey kidney cultures 28 to 51 hr after infection sedimented more slowly than cellular DNA and was not denatured by the heating (SV40 DNA). It is concluded that cellular DNA synthesis was induced during either the productive or abortive SV40 infections.     

Ecological aspects of nematode parasites of introduced salmonids from Valdivia river basin, Chile.

Between 1986 and 1987, 666 fishes distributed among the following species introduced in Chile, and from different sectors of the Valdivia river basin (39 degrees 30'-40 degrees 00'S, 73 degrees 30'-71 degrees 45'W), were examined: 348 Salmo trutta, 242 Salmo gairdneri, 24 Cyprinus carpio and 52 Gambusia affinis holbrooki. The presence of Camallanus corderoi and Contracaecum sp. in S. gairdneri and of C. corderoi in S. trutta is recorded in Chile for the first time. Cyprinus carpio and G. a. holbrooki did not present infections by nematodes. The prevalence and mean intensity of the infections by nematodes presented significant differences among some sectors of the Valdivia river basin. In general, the prevalence and intensity of the infections by C. corderoi were greater than those by Contracaecum sp. The infections in S. gairdneri were higher than in S. trutta. The sex of the hosts had no influence on the prevalence and intensity of the infections by both nematodes. The length of the hosts did have an influence, except in the case of the infections by Contracaecum sp. in S. gairdneri. The infrapopulations of both nematode species showed over-dispersion in most cases. The diet of the examined salmonids suggests that they would become infected principally through the consumption of autochthonous fishes.     

Gastrointestinal helminths of fish-eating birds from Chiloe Island, Chile

Of four species of fish-eating birds from Chiloé Island (Chile), three were infected with eight species of helminths. Tetrabothrius sp. was found in Larus scoresbii. Tetrabothrius cylindraceus, Profilicollis antarcticus, Anomotaenia dominicanus, Stephanoprora denticulata, Capillaria sp. and P. antarcticus were found in Larus dominicanus. Contracaecum rudolphii and Corynosoma sp. infected Phalacrocorax olivaceus. With the exception of S. denticulata, C. rudolphii and Capillaria sp., the above helminths are reported for the first time from Chile.     

Ca2+-Independent Release of Glutamate During In Vitro Anoxia in Isolated Nerve Terminals

The effects of in vitro anoxia on the release of glutamate in isolated nerve terminals were studied. The extra-synaptosomal concentration of glutamate ([Glu]ext) under aerobic conditions was 2.3 microM and increased to 4.9 microM after 10 min of anoxia. However, when synaptosomes were incubated in the presence of lactate plus pyruvate instead of glucose, to prevent anaerobic glycolysis, anoxia induced an eightfold increase in the [Glu]ext. The accumulation of glutamate in the external medium during anoxia was Ca2+ independent and insensitive to a significant reduction of the Ca(2+)-dependent release of the amino acid. These results indicate that a Ca(2+)-independent efflux of cytoplasmic glutamate occurs during in vitro anoxia in isolated nerve terminals.     

Photosynthesis of Gelidium sesquipedale: effects of temperature and light on pigment concentration,C/N ratio and cell-wall polysaccharides

Tanymastix stagnalis is known from seven locations in Ireland. These range from small to large temporary water bodies. It was earlier shown that the best hatching and survival of eggs and young stages occurred in the presence of soil and at temperatures between about 10° and 15°. Some eggs hatched after one drying period, others after up to at least 4 drying and wetting periods. It was found from field observations that the habitat appeared after a minimum of 200 mm of rain in a 2-month period. This occurred on average more than once per year, mostly between June and February. A computer model was constructed using field data, and meteorological data (rainfall and temperature) covering 100 years, to decide how secure the organism was in two contrasting habitats. This showed that in both habitats there was little likelihood of extinction from metorological causes. There was, however, the possibility of destruction of the smaller habitats either through drainage or conversion to permanent ponds through compaction of the soil by heavy farm animals. The distribution and the possibility of harvesting the organisms is briefly discussed.     

Regulation of lymphokine (gamma-interferon) production by corticotropin

We have shown that corticotropin (ACTH), alpha-endorphin, and enkephalins can regulate antibody responses, which suggested a role for neuropeptides in a regulatory circuit between the immune and neuroendocrine systems. ACTH and structurally related peptides were examined here for regulation of mitogen induction of the lymphokine gamma-interferon (IFN gamma) in C57BL/6 mouse spleen cell cultures. Synthetic ACTH1-39 and a porcine pituitary extract containing ACTH activity were potent suppressors of the IFN gamma response. Synthetic ACTH1-39 suppressed the response by approximately 62% at 1 to 3 microM, whereas the porcine extract suppressed by greater than 90% at 1 to 3 microM ACTH. The greater potency of the pituitary extract was shown to be due to the presence of an additional peptide of Mr 2100 that was reactive with antibodies to the N-terminal region of ACTH (ACTH1-13), possessed potent anti-cellular activity against L cells and various transformed cells, but lacked ACTH biologic activity. The anti-cellular peptide suppressed the IFN gamma response by greater than 99% at 0.05 microM. The ACTH1-39 cleavage products, alpha-melanocyte stimulating hormone (alpha MSH; acetylated and amidated ACTH1-13), and corticotropin-like intermediate lobe peptide (CLIP; ACTH18-39) had no effect on IFN gamma production. ACTH1-24, like ACTH1-39, has full steroidogenesis activity but also had no effect on IFN gamma production, which suggests a dissociation of the immunoregulatory and steroidogenic properties of ACTH1-39. ACTH1-39, and possibly also the anti-cellular 2100 Mr peptide, is initially synthesized as the precursor polyprotein pro-opiomelanocortin (POMC). Enzymatic processing of POMC, first to the active ACTH1-39 or the anti-cellular peptide and then to the inactive smaller peptides, probably plays an important role in regulation of lymphokine and antibody production by ACTH and ACTH-related neuropeptides. This is consistent with the recent demonstration of the production of ACTH-like peptides by lymphocytes.     

Free Fatty Acids and Energy Metabolites in Ischemic Cerebral Cortex with Noradrenaline Depletion

Abstract: We tested whether cerebral noradrenaline (NA) may play a central role in mediating the increased production of free fatty acids (FFAs) during cerebral ischemia. Levels of FFAs, cyclic AMP, and NA, as well as ATP, ADP, and AMP, were measured in cerebral cortex during decapitation ischemia in rats 2 weeks after unilateral locus ceruleus lesion. Comparisons were made between the results obtained from the contralateral cortex with normal NA content and the NA-depleted ipsilateral cortex. Although NA depletion was associated with a diminished transient rise of cyclic AMP in response to ischemia, it failed to influence the magnitude of FFA increase or the decline of energy state within the 15-min period of ischemia. A more than twofold increase of total FFAs (sum of palmitic, stearic, oleic, arachidonic, and docosahexaenoic acids) was observed in both hemispheres at 1 min after decapitation, when energy failure became manifest. The increased production of FFAs continued throughout the 15 min of ischemia, with a preferential rise in the levels of stearic and arachidonic acids. There was an inverse correlation between FFA levels and total adenylate pool. The results do not support a major role for NA and cyclic AMP in increasing cortical FFAs during complete ischemia. Instead, they are consistent with the view that impaired oxidative phosphorylation activates deacylating enzymes. Disturbance of reacylation due to energy depletion is probably another factor contributing to the continuous increase of FFAs during prolonged ischemia.     

A novel stimulator of protein phosphorylation in Neurospora crassa

Summary An endogenous thermostable activator of Protein kinase III (PKIII) was purified from 100000 × g supernatants of Neurospora crassa mycelial extracts. This 38 000 dalton polypeptide, clearly separable from calmodulin on P-60 gel filtration, specifically stimulated N. crassa PKIII activity on casein or phosvitin in vitro phosphorylation.The factor was only present in the initial growth phase of the fungus. The mechanism of PKIII activation and its possible regulatory role are discussed.Abbreviations PK protein kinase - MES 2-N-Morpholino ethane-sulfonic acid - PMSF phenylmethylsulfonyl fluoride - S₁₀₀ 100000 × g Supernatant