Description de Falklandia gen.n. de I'Ocean Austral et définition des Lysianassoidea uristidiens (Crustacea, Amphipoda)

The revision of the antarctic–subantarctic species Orchomenopsis reducta Schellenberg, 1931, has led to its attribution to a new, highly apomorphic genus: Falklandia gen.n. A new definition of the uristid group is given and Falklandia with 36 other lysianassoid genera are attributed to this supposedly monophyletic group.     

Cyanide-Resistant Root Respiration and Tap Root Formation in Two Subspecies of Hypochaeris radicata

Root respiration of the tap root forming species Hypochaeris radicata L. was measured during tap root formation. A comparison was made of two subspecies: H. radicata L. ssp. radicata L., a subspecies from relatively rich soils, and H. radicata L. ssp. ericetorum Van Soest, a subspecies from poor acidic soils. Root respiration was high and to a large extent inhibited by hydroxamic acid (SHAM) before the start of the tap root formation, indicating a high activity of an alternative non-phosphorylative electron transport chain. The rate of root respiration was much lower and less sensitive to SHAM when a considerable tap root was present. However, root respiration was also cyanide-resistant when a tap root was present, indicating that the alternative pathway was still present. A decreased rate of root respiration coincided with an increase of the content of storage carbohydrates, mainly in the tap root. The level of reducing sugars was constant throughout the experimental period, and it was concluded that the activity of the alternative oxidative pathway was significant in oxidation of sugars that could not be utilized for purposes like energy production, the formation of intermediates for growth or for storage. Root respiration decreased after the formation of a tap root. This decrease could neither be attributed to a gradual disappearance of the alternative chain, nor to a decreased level of reducing sugars. No differences in respiratory metabolism between the two subspecies have been observed, suggesting that a high activity of the alternative oxidative pathway is not significant in adaptation of the present two subspecies to relatively nutrient-rich or poor soils.     

Role of pituitary hormones in regulating renal vitamin D metabolism in man.

Studies in animals and tissue culture have shown the importance of prolactin and growth hormone in regulating renal 1 alpha-hydroxylase activity and plasma concentrations of 1,25-dihydroxycholecalciferol (1,25(OH)2D3). Evidence for a similar role for these hormones in man was sought by using a radioreceptor assay to measure plasma 1,25(OH)2D3 concentrations in 20 normal subjects, 12 patients receiving dialysis, 11 patients with primary hyperparathyroidism, 10 pregnant women, seven women with prolactinoma, and 14 patients with acromegaly. Circulating 1,25(OH)2D3 concentrations were appreciably raised in the patients with primary hyperparathyroidism and the pregnant women (P less than 0.001), slightly but significantly increased in the patients with prolactinoma (P less than 0.05), and greatly raised in those with acromegaly (P less than 0.001). These results suggest that prolactin and growth hormone are important regulators of renal vitamin D metabolism in the physiological conditions of pregnancy, lactation, and growth in man.     

ATP(GTP)-dependent conversion of MVM parvovirus single-stranded DNA to its replicative form by a purified 10 S species of mouse DNA polymerase alpha

A species of DNA polymerase alpha that is active in the ATP(GTP)-dependent conversion of MVM parvovirus single-stranded linear DNA to the duplex replicative form has been purified 4300-fold from Ehrlich ascites mouse tumour cells. The single-stranded----replicative form activity is maintained throughout ammonium sulfate precipitation, DEAE-cellulose, phosphocellulose and hydroxyapatite column chromatography and glycerol gradient sedimentation. Polypeptides with Mr = 230 000, 220 000, 183 000, 157 000, 125 000, 70 000, 65 000, 62 000, 57 000, 53 000 and 48 000 copurify with the single-stranded----replicative form activity, which sediments at approx. 10 S. The Mr = 183 000, 157 000 and 125 000 polypeptides exhibit catalytic activity when assayed in situ following SDS-polyacrylamide gel electrophoresis. The 10 S form of DNA polymerase alpha is functionally distinguishable from an 8.4 S form of the enzyme obtained from the same cells on the basis of single-stranded----replicative form activity. The single-stranded----replicative form activity of the 10 S enzyme is stable at 22 degrees C for up to 3 h, but exhibits a half life of only 5 min at 45 degrees C.