Comparative study of G2 delay and survival after241Americium-α and60Cobalt-γ irradiation

Summary Survival and G2 delay following exposure to either⁶⁰Cobalt--rays or²⁴¹Americium--paticles were studied in eight mammalian cell lines of human and animal origin including human fibroblasts from normal individuals and from patients with Ataxia telangiectasia or Fanconi's anemia.For both endpoints the effectiveness of alpha particles was greater as compared to-rays. RBE values for G2 delay (4.6–9.2) were in general comparable to RBE values derived from initial slopes of survival curves (RBE ) but higher compared to the ratio of mean inactivation doses .Ataxia cells were particularly sensitive to cell killing by-irradiation (D₃₇ = 0.57 Gy), however, showed average sensitivity to-particles of high LET (D₃₇ = 0.30 Gy).With the exception of Ataxia cells, cell killing and G2 delay seem to be related processes if individual cell cycle parameters are taken into account.     

Developmental regulation of NAD+ kinase in Neurospora crassa

The specific activity of NAD⁺ kinase (ATP:NAD⁺ 2-phosphotransferase, EC 2.7.1.23) from Neurospora crassa shows sharp peaks when the organism enters a new developmental stage of the asexual life cycle: the peaks are observed during hydration and germination of conidia, at the transition from exponential to stationary growth and at the photostimulated conidiation. As stimulation of NAD⁺ kinase activity by light in conidiating mycelium is not sensitive to translation inhibitors, the activiation of pre-existing molecules, rather than induction of protein synthesis de novo may be supposed. Enzyme electrophoresis revealed the presence of four forms of NAD⁺ kinase having different apparent molecular weights (I=333,000; II=306,000; III=229,000 and IV=203,000). Manifestation of the activity of individual forms of NAD⁺ kinase is developmentally controlled: form III is most abundant during vegetative growth, forms I and II prevail in conidia. At the conidial germination the increase of NAD⁺ kinase activity is associated with the activation of form III, whereas during photostimulation of conidiation form II is the most activated one. Therefore, certain molecular forms of the enzyme may be regarded as biochemical markers for different developmental stages of N. crassa.     

Occurrence,localization, and possible significance of an ornithine-containing lipid in Paracoccus denitrificans

A ninhydrin-positive, phosphorus-negative lipid from Paracoccus denitrificans ATCC 13543 has been isolated and purified by mild alkaline methanolysis followed by silicic acid column chromatography and preparative thin-layer chromatography. The lipid was identified as an ornithine-containing lipid. The major ester-linked fatty acid was cis vaccenic acid. Major amide-linked fatty acids were 3-OH-20:1 and 3-OH-18:0. Ornithine-containing lipid was a major lipid component of P. denitrificans. Phospholipids made up about 57% and ornithine-containing lipid about 14% of the weight of the total lipid of the organism. The ratios of lipid ornithine: lipid phosphorus were 0.23, 0.65 and 0.58 in cytoplasmic membrane, outer membrane, and an NaCl extract, which is thought to represent chiefly outer membrane, respectively. Thus ornithine-containing lipid appears to be present in larger amounts in outer membrane than cytoplasmic membrane. No substantial variations in lipid ornithine levels were noted in stationary phase versus exposnential phase organisms, organisms grown in complex medium versus organisms grown in minimal medium with and without amino acid supplements, or in organisms grown in low phosphate-containing medium.Non standard abbreviations TLC thin-layer chromatography - Tris-HCl tris(hydroxymethyl)aminomethane hydrochloride - TMS trimethylsilyl - TFA triluoroacetyl - NPPN ninhydrin-positive, phosphorus-negative - ECL equivalent chain length     

Uncommon pneumonia associated with acute poststreptococcal glomerulonephritis

184 cases of acute poststreptococcal glomerulonephritis were investigated and six of these were associated with a peculiar, uncommon pneumonia, and another one had a lethal course. The clinicoradiological and especially pathological data summarized in this study attempt to demonstrate the individuality of this type of pneumonia. Pneumonia associated with acute poststreptococcal glomerulonephritis is similar or identical to rheumatic pneumonia. In both entities, pneumonia and pulmonary edema may and do coexist, and the differentiation of pneumonia from congestive heart failure is difficult and often impossible without pathological evidence. The most attractive pathogenic interpretation is the hypothesis of an immune mechanism in the induction of pneumonia. Authors attributed the lung changes, consecutive to a vascular damage, to a hypersensitivity phenomenon, with accumulation of fibrinogen in alveoli where it is converted to fibrin. Then, the hyaline membrane lining the alveoli, an important feature of pneumonia associated with glomerulonephritis is built up. It is, however, plausible that the effect of the immune reaction is associated with those of hydrosaline retention, arterial hypertension and congestive heart failure. Analogous to rheumatic pneumonia, the "peculiar pneumonia" associated with acute poststreptococcal glomerulonephritis should be named nephritic pneumonia.     

Perennation in woody fruit plants and its relationship to carbohydrate turnover

Carbohydrates constitute the principal reserves in temperate woody fruit plants and are depleted during winter, particularly around the time of bud-break before new growth makes good the losses. Movement of reserves between underground and aerial parts occurs during winter. All perennial parts show alternate depletion and replenishment but root extremities may undergo irreversible depletion and die. Interconversions between soluble carbohydrates and polysaccharides indicate a balance between degradation and synthesis. High growth potential is associated with high starch/starch + sugar ratio.     

Experience with the international standardization of the biological activity of the 3d Standard for streptomycin

The activity of the third International Standard of streptomycin was determined to be equal to 755 IU/mg with the use of accurately weighed amounts of streptomycin and 78037 IU with the use of streptomycin ampoules. The Standardization Center of the WHO decided to use the whole content of the ampoule of the Third International Standard of streptomycin, the activity of which is determined to be equal to 78500 IU per an ampoule.     

A regression analysis of the summer population dynamics of Polyarthra vulgaris in a northern Michigan bog lake

The population dynamics of a planktonic rotifer (Polyarthra vulgaris) were examined in a brown water, acid lake in northern Michigan, U.S.A. Predation by Chaoborus punctipennis and low food (Navicula spp. and Cyclotella spp.) concentrations were the main factors limiting P. vulgaris populations of all factors examined. The data presented here support a hypothesis for zooplankton limitation by an invertebrate predator.     

Seasonal changes in fat and fatty acid composition of Limnothrissa miodon Boulenger (Pisces: Clupeiformes) from Lake Tanganyika,with reference to their nutritive value

The fat content and fatty acid composition of whole sun-dried Limnothrissa miodon Boulenger caught during 1973 have been measured. The fat content seems to increase during the dry seasons. The fatty acids however showed no defined seasonal variations.     

The reproductive biology of some serolid isopods from the Antarctic

Summary Several species of serolid isopod from Signy Island, South Orkney Islands and also from South Georgia were studied, and aspects of their reproductive behaviour and associated morphology are discussed. InSerolis polita Pfeffer egg-laying took place at a mean age of 28 months, and the eggs were then incubated in a ventral marsupium for a period of 20 months before the release of juveniles in the spring. The mean egg dry weight at spawning was 0.68 mg forS. polita and 3.35 mg forSerolis cornuta Studer. The egg weight increased during marsupial development due to the uptake of minerals, but the total calorific content fell. Within each species brood size was linearly related to female size and the mean number of eggs varied from 40 forS. polita to 232 forSerolis pagenstecheri Pfeffer. There was no detectable marsupial mortality.S. polita appeared to breed repeatedly at two-year intervals, butS. cornuta probably only breeds once. The reproductive biology of Antarctic serolids is compared with that of temperate isopods, and it is shown that they produce larger young which is related to their larger adult size. The extremely protracted period of marsupial incubation is associated with the need to synchronize reproduction with the seasonal nature of Antarctic primary production.