Response to drought among farmers and herders in southern Kajiado District,Kenya

From 1972 to 1976 rainfall in Kajiado District of Kenya was below normal. The capacity of the farming and herding systems to cope with the consequent reduction in production is discussed within a context of changing land-use patterns and altered resource availability. It is concluded that land-use planning to allocate the available land and water resources and to promote off-farm employment is required to reduce the vulnerability of the population to future drought conditions.     

Cyclic GMP-dependent and cyclic AMP-dependent protein kinases,protein kinase modulators and phosphodieterases in arteries and veins of dogs Distribution and effects of arteriovenous fistula and arterial occlusion

Possible involvement of cyclic GMP-dependent and cyclic AMP-dependent protein kinases, protein kinase modulators and cyclic nucleotide phosphodiesterases in functions of vascular tissues were investigated in the dog. All of the above activities, localized in the smooth muscle-rich inner layer of the blood vessels, were found to be higher in the arteries than in the veins. The peripheral arteries were disproportionately richer in cyclic GMP-dependent protein kinase (as indicated by high ratios of cyclic GMP-dependent to cyclic AMP-dependent protein kinase) than were the veins, with the exception of the pulmonary artery, an atypical arterial tissue exposed to low blood pressure. Interestingly, the protein kinase ratio for the aorta, an artery with no significant role in blood pressure regulation, was not higher than that for the vena cava. Creation of femoral arteriovenous fistulae in the dogs led to preferential reductions in the cyclic GMP-dependent enzyme activity both in the proximal and distal arteries, whereas it was elevated in the stressed vein distal to the anastomotic site. The cyclic GMP-dependent enzyme was preferentially reduced in the saphenous artery distal to occlusion. Changes in the cyclic GMP-dependent enzyme activity appeared to precede gross atrophy or hypertrophy of the vessels. It is suggested that the vascular cyclic GMP-dependent protein kinase may be closely related to peripheral resistance and its regulation.     

Intraperitoneal injection of chloral hydrate causes intra-abdominal adhesions and unilateral testicular atrophy in golden Syrian hamsters.

We investigated the reason for the high mortality we had observed in hypophysectomized-orchidectomized Golden Syrian hamsters that were anesthetized with intraperitoneal (i.p.) injections of chloral hydrate (CH). Intact male Golden Syrian hamsters were injected intraperitoneally with 0.1cc/100g BW of a 35% solution of CH, a 35% solution of sodium chloride, or double-distilled water. Equal numbers of hamsters in each group were injected on the right or left side of the abdomen. Within 10 days, 35% of the CH-injected hamsters were dead or had to be euthanized. Autopsy revealed severe peritonitis and adynamic ileus. CH-injected hamsters that survived gained weight at a rate similar to that of the controls. All surviving hamsters were killed 18 days after the injections. Among the surviving CH-injected hamsters, 84.6% had intra-abdominal adhesions, 61.5% had unilateral testicular atrophy, and 53.8% had a yellowish necrotic mass in the epididymal fat pad (EFP). All the lesions occurred on the side that was injected. The atrophied testes had been rendered cryptorchid due to involvement with intra-abdominal adhesions. In the water-treated controls, there were no abnormalities; whereas, in the saline controls, 75% had a mass in the EFP. Histology of the EFP mass was similar in hamsters injected with CH or hypertonic saline and suggested a diagnosis of fat necrosis. The results suggest that the mortality, the intra-abdominal adhesions, and the unilateral cryptorchidism were caused by a single i.p. injection of CH, but the fat necrosis in the EFP was probably caused by high concentrations of salt. The results further suggest that high concentrations of CH should not be injected intraperitoneally for anesthesia in chronic studies, particularly of the male reproductive system.     

Effects of insulin,pertussis toxin and cholera toxin on protein synthesis and diacylglycerol production in 3T3 fibroblasts: Evidence for a G-protein mediated activation of phospholipase C in the insulin signal mechanism

The rapid increase in protein synthesis that occurs on addition of insulin (1 mU/ml) to stepped-down 3T3 cells was blocked by pre-incubation of the cells with pertussis toxin. Cholera toxin on the other hand stimulated protein synthesis and this effect was insensitive to actinomycin D and inhibited by pro-treatment of the cells with phorbol dibutyrate to deplete cell protein kinase C. Insulin was found to cause a rapid and transient increase in diacylglycerol (DAG) synthesis. The insulin-induced increase in diacylglycerol was blocked by pertussis toxin. Exogenous DAG (10 M) stimulated protein synthesis within 1 hour. The results suggest that insuIin stimulates ribosomal activity through a signal mechanism that involves a G-protein mediated activation of phospholipase C to increase DAG levels.     

Characterization of phycoerythrin-containing Synechococcus spp. populations by immunofluorescence

Using an immunofluorescence assay developed to identify serogroups(i.e. clusters of strains labelled by one antiserum), the compositionof natural populations of phycoerythrin-containing Synechococcusspp. was examined. The 7803 (open ocean clone)-serogroup wasfound in most oceanic regions, but was most prevalent (up to85%) in tropical and subtropical waters during spring and summer.At coastal Long Island stations it was most abundant (up to65%) when water temperatures were >22°C. The seasonaland geographic distribution of the 7803-serogroup appeared tobe limited by water temperature. No consistent pattern was observedin the per cent composition with depth in the Sargasso Sea orat coastal to offshore stations in the North-west Atlantic Oceanor eastern tropical North Pacific Ocean. The 8016 (coastal clone)-serogroupwas abundant at coastal and estuarine stations off Long Island(up to 95 %) and its appearance was also correlated with warmwater temperature (> 15°C). However, this serogroup remaineda constant proportion of the population at the Long Island Soundstation during early winter months (through January) when abundanceof the 7803-serogroup was negligible. Owing to limited data,the oceanic distribution of the 8016-serogroup is not yet discernible.Lastly, antisera to the phycocyanin-dominant Synechococcus spp.clones failed to label any cells in samples collected from severaloceanic stations. Thus, these strains appear to be limited tocoastal and estuarine regions, which is consistent with predictionsfrom experiments comparing the photosynthetic performance ofthe phycoerythrin-dominant and phycocyanin-dominant clones. ¹Present address: Department of Oceanography, University ofHawaii, Honolulu, HI 96822, USA     

The geometries of interacting arginine-carboxyls in proteins

The geometries are reported for interacting arginine-carboxyl pairs obtained from 37 high resolution protein structures solved to a resolution of 2.0 A or better. The closest interatomic distance between the guanidinium and carboxyl is less than 4.2 A for 74 arginine and carboxyl groups, with the majority of these lying within hydrogen-bonding distance (2.6-3.0 A). Interacting pairs have been transformed into a common orientation, and arginine-carboxyl, and carboxyl-arginine geometries have been calculated. This has been defined in terms of the spherical polar angles T theta, T phi, and the angle P, between the guanidinium and carboxyl planes. Results show a clear preference for the guanidinium and carboxyl groups to be approximately coplanar, and for the carboxyl oxygens to hydrogen bond with the guanidinium nitrogens. Single nitrogen-single oxygen is the most common type of interaction, however twin nitrogen-twin oxygen interactions also occur frequently. The majority of these occur between the carboxyl oxygens and the NH1 and NE atoms of the arginine, and are only rarely observed for NH1 and NH2. The information presented may be of use in the modelling of arginine-carboxyl interactions within proteins.     

Glutamine synthetase isozymes in elasmobranch brain and liver tissues

Glutamine synthetase is present as isozymic forms in the elasmobranchs Squalus acanthias (dogfish shark) and Dasyatis sabina (stingray). Subcellular fractionation of elasmobranch brain and liver tissue shows the enzyme to be predominantly cytosolic in the former tissue and mitochondrial in the latter. For the cytosolic brain enzyme, the subunit Mr equals 42,000 in the stingray and 45,000 in the shark, as determined by sodium dodecyl sulfate-gel electrophoresis/Western blotting. The subunit Mr = 45,000 and 47,000, respectively, for stingray and dogfish mitochondrial liver enzymes. Translation of total brain RNA from both species gives immunoprecipitable nascent peptides of the same size as their respective mature enzymes. However, in liver tissue, translation of glutamine synthetase mRNA yields peptides of higher Mr than that of the mature enzymes. In dogfish liver, Mr = 50,000 for the translation product and, in stingray liver, Mr = 48,000. This suggests that the translocation of the enzyme into liver mitochondria may be via a signal or leader sequence mechanism. The larger liver isozyme of elasmobranch glutamine synthetase is found in kidney where it is also known to be mitochondrial. The smaller cytosolic isozyme occurs in retina, heart, gill, and rectal gland tissue as well as in brain.