The major type-1 protein phosphatase catalytic subunits are the same gene products in rabbit skeletal muscle and rabbit liver

The catalytic subunit of protein phosphatase-1 (PP1) isolated from rabbit liver had the same electrophoretic mobility as, and yielded peptide maps identical to those of the 33 kDa form of rabbit skeletal muscle PP1. The predicted amino-acid sequences of PP1 obtained from three rabbit liver cDNA clones were identical to that of PP1 alpha from rabbit skeletal muscle. These findings suggest that the distinctive substrate specificities and regulatory properties of hepatic and skeletal muscle type-1 protein phosphatases are not conferred by the catalytic subunits themselves, but by regulatory subunits that are complexed to the catalytic subunits in vivo.     

Intrinsic potential for high fetal hemoglobin production in a Druze family with β-thalassemia is due to an unlinked genetic determinant

Summary The mechanism for elevated production of fetal hemoglobin (Hb F) in a Druze patient with °-thalassemia intermedia was investigated. Heterozygous family members exhibited normal Hb F levels, suggesting that the increase in -gene expression in the propositus may be partly due to anemic stress. Erythroid progenitors of these family members cultured in vitro [burst forming units (erythroid); (BFUe)] showed elevated synthesis of Hb F, indicating the existence of a genetically determined intrinsic capacity for high Hb F production in this family. The propositus was found to be homozygous for a IVS2-position 1 mutation, on the background of Mediterranean haplotype I, which is not known to be linked to high Hb F production. Moreover, extensive molecular studies of the -globin gene cluster, including sequence analysis of the promoter regions of the -globin genes, did not reveal any cisacting mechanism that could account for the high Hb F production in the propositus. A young niece of the propositus with °-thalassemia major was recently discovered, who was homozygous for the same -globin allele and haplotype as the propositus. However, unlike her uncle, she does not have a high Hb F level and presents with a severe clinical course. Her inability to produce high Hb F suggests that the genetic determinant for increased -gene expression in the propositus is unlinked to the -globin gene cluster.     

Paracoccidioidomycosis in nude mice: Presence of filamentous forms of the fungus

Congenitally athymic nude mice (nu/nu) and their phenotypically normal littermates (nu/+) were intraperitoneally infected with yeast cells of a strain of Paracoccidioides brasiliensis. The nude mice developed a severe and generalized infection with an intense parasitism of several organs, accompanied by a low-grade of tissue reaction. The lesions were characterized by abundant yeast-like cells of the fungus, and in some animals, numerous hyphal forms could be well visualized. In control animals, infection was moderate, almost exclusively restricted to the area of inoculation, and the lesions presented few parasites surrounded by an inflammatory response. Filamentous forms of the fungus were never encountered in these animals.     

N2-Succinylornithine in ornithine catabolism of Pseudomonas aeruginosa

Most Pseudomonas aeruginosa PAO mutants which were unable to utilize l-arginine as the sole carbon and nitrogen source (aru mutants) under aerobic conditions were also affected in l-ornithine utilization. These aru mutants were impaired in one or several enzymes involved in the conversion of N²-succinylornithine to glutamate and succinate, indicating that the latter steps of the arginine succinyltransferase pathway can be used for ornithine catabolism. Addition of aminooxyacetate, an inhibitor of the N²-succinylornithine 5-aminotransferase, to resting cells of P. aeruginosa in ornithine medium led to the accumulation of N²-succinylornithine. In crude extracts of P. aeruginosa an ornithine succinyltransferase (l-ornithine:succinyl-CoA N²-succinyltransferase) activity could be detected. An aru mutant having reduced arginine succinyltransferase activity also had correspondingly low levels of ornithine succinyltransferase. Thus, in P. aeruginosa, these two activities might be due to the same enzyme, which initiates aerobic arginine and ornithine catabolism.Abbreviations OAT ornithine 5-aminotransferase - SOAT N²-succinylornithine 5-aminotransferase - Oru ornithine utilization - Aru arginine utilization     

Nitrogen mineralization ofSesbania sesban used as green manure for lowland rice in Sri Lanka

Sesbania sesban was evaluated as green manure crop for lowland rice in the Dry Zone of Sri Lanka. The legume was grown during a fallow period before lowland rice (Oryza sativa) and ploughed under just before transplanting. Weight loss and nitrogen content in litterbags containing leaves, stems and roots of the legume were monitored. Comparisons were made between rice yields from 20 m² plots after green manuring in combination with different nitrogen fertilizer levels (0, 2.4, 4.8 and 7.2 gm⁻²) and nitrogen fertilizer (9.6 gm⁻²) alone. Above-ground biomass ofS. sesban was 440 gm⁻² (dry wt) when ploughed under after 84 days growth. N-content in leaves, stems and roots was 3.76%, 0.41% and 0.73%, respectively. This gave a N-input fromS. sesban of 9.2 gm⁻² (8.3 g from above-ground parts and 0.9 g from roots). The corresponding K and P inputs were 7.3 and 0.6 gm⁻² respectively. The nitrogen rich leaves, which contained 88% of the nitrogen in the above-ground parts, decomposed and released its nitrogen much more rapidly than the stems and roots. After only four days the leaves had released 5.3 g Nm⁻² and after 14 days they had released 6.4 g Nm⁻². The highest rice yield (505 gm⁻²) was obtained usingS. sesban and 4.8 gm⁻² of N-fertilizer. The yields with only N-fertilizer or onlyS. sesban were 442 gm⁻² and 396 gm⁻², respectively. Due to the rapid decomposition of the nitrogen rich leaves,S. sesban did not behave as a slow release fertilizer. Thus, it is not necessary to apply nitrogen fertilizers as a basal dose.     

Compensatory payments and vasectomy acceptance in urban Sri Lanka

The effects of different levels of compensatory payment for vasectomy on sterilization acceptance were examined in 496 vasectomized men in urban Sri Lanka. The results indicate that compensatory payments significantly enhanced the participation of economically poor men in vasectomy programs, especially those who had already achieved a large family size. The proportion of poor acceptors (those with a monthly income of Rs 1000 or less) increased with higher levels of payment; the acceptor's level of education was negatively correlated with the compensation amount, and the mean age of the youngest child was higher among those who received higher payments. 60% of vasectomy acceptors reported using contraception immediately before the vasectomy, suggesting a high level of motivation not to have another child. Respondents cited high effectiveness, no extra expense, and no side effects for their wives as the main reasons for selecting vasectomy over other means of contraception, regardless of the amount of payment received. Only 5% said cash payment was an important reason for choosing vasectomy, and this response did not vary significantly by level of payment. There was no influence of payment level on postoperative complications or satisfaction. While compensatory payments significantly enhanced the participation of poor men in vasectomy programs, they were not effective in attracting poorer men with few children or those whose last child was relatively young. Overall, this study's findings suggest that the decision to provide compensatory payments and how much to provide should be based on economic and political factors, not on the grounds that higher compensatory payments have led to the recruitment of ineligible men or that the promotion of vasectomy has been at the expense of a loss in the quality of services provided.     

Label-fracture of cell surfaces by replica staining

We introduce replica-staining label-fracture, a method for the cytochemical mapping of membrane surfaces. This method is a corollary of the rationale of label-fracture (Pinto da Silva and Kan, 1984: J Cell Biol 99:1156). After freeze-fracture the exoplasmic halves of the membrane remain attached to the replica. We show that cytochemical labeling of cell surfaces can be performed by direct post-fracture staining of freeze-fracture replicas. This new variant of label-fracture leads to miniaturization of labeling procedures and allows standardization of labeling conditions and simultaneous processing of different specimens.     

Use of the spin label method for studying the structure of the brain membranes in cats with streptomycin poisoning

The structural changes in cat brain membranes under the injections of intramuscular streptomycin which is ototoxic antibiotic have been studied. The increase of membrane microviscosity in brain areas which are the direct projection of the auditory way has been revealed using fat acidic spin probe on the basis of stearic acid. The changes in membranes of other brain areas have not been found that exhibits a specific streptomycin influence on the auditory analyzer. The EPR spectra of the hydrocarbon spin label C12H25 localizing in near membrane region don't change in brain membranes of experimental animals compared with the normal ones.