Effects of dietary cobalt on testicular structure

Adult male rats were maintained on a diet containing 265 ppm cobalt for up to 98 days. Three rats were sacrificed weekly and assayed for testicular damage by light and electron microscopy. Testicular damage was first apparent after 70 days of treatment, followed by a progressive deterioration of cell architecture and decrease in testicular volume. The degenerative changes were of a very general nature; e.g., thickening of basal lamina and basement membranes, increased packing of red blood cells in veins and arteries, formation of "giant" cells, loss of sperm tail filaments, and degeneration of sperm mitochondria. No cobalt residues could be detected by energy dispersive x-ray microanalysis. These data indicate that testicular degeneration was not a primary response to cobalt and suggest that the testes become hypoxic due both to blockage of veins and arteries by red blood cells and to changes in permeability caused by thickening of basal lamina and basement membranes.     

Characteristics of bacterium GB-2, a presumptiveCytophaga species with novel immunoregulatory properties

A Gram-negative, psychrophilic bacterium, designated GB-2, was isolated from fetal calf serum and analyzed for its morphological, physiological, and biochemical characteristics. Gliding motility, sensitivity to actinomycin D, the presence of the pigment flexirubin and cytochrome c, growth on a variety of carbohydrates, the production of acid fermentation products, and a 34.9 mol% guanine+cytosine (G+C) content of bacterial DNA indicate GB-2 to be a member either of the generaCytophaga orFlexibacter. Growth of GB-2 was optimized in a simple defined medium to facilitate isolation and characterization of bacterial products. Liquid growth of GB-2 resulted in the release of significant quantities of a macromolecule free of both endotoxin and protein into the growth supernatant, which activated the proliferation of murine lymphocytes. The relationship between this bacterium and its end-products to other species of theCytophaga/Flexibacter group is discussed.     

The effects of a settled industrial–domestic sewage works effluent from percolating filters on the survival and growth of various stages of rainbow trout, Salmo gairdneri (Richardson)

Comparisons were made of the mortality, growth and condition factor over a 50-day period of eleutheroembryos, alevins, 2-month fry, 4-month fry and 1 + rainbow trout, Salmo gairdneri , in water of three qualities–Birmingham tap-water, 50% and 100% settled effluent from percolating filters (Minworth Effluent Treatment Works) when dissolved oxygen levels were maintained near 100% ASV.
There was no significant mortality among life stages in control tap-water but the LT50 values of life stages in both 50% effluent and 100% effluent revealed significant differences. Inter-treatment comparisons showed similar mortalities of eleutheroembryos, of 2-month fry and of 1 + fish in the three treatments but LT50 values of 4-month fry showed significant differences. Growth rates of 2-month and 4-month fry were suppressed in both effluents after 7 days and there was a significant deterioration in the K factor of these life stages after 14 days. Predicted toxicities (the sum of the proportions of the 48-h LC50 of the individual poisons to rainbow trout) were compared with the observed toxicity in 50% and 100% effluent. The relevance of in vivo testing in comparison to predictive techniques is compared.     

Hyperbaric hyperoxia reversibly inhibits erythrocyte phospholipid fatty acid turnover

The present study is one component of a comprehensive investigation of oxygen tolerance of tissues and organs in normal human subjects. The focus of this study was the acylation of membrane phospholipid in situ by erythrocytes. Activation of exogenous [9,10-3H]oleic acid to acyl thioester and transesterification of the acyl thioester into phospholipid by intact human erythrocytes incubated in vitro decreased 30% after exposure of 10 human subjects to hyperbaric hyperoxia (100% O2, 3 ATA, 3.5 h). Partial recovery of activity could be detected when additional cells were obtained from these subjects and assayed in vitro 24 h after cessation of exposure. No significant change in membrane phospholipid fatty acid composition was detected under these conditions. The reduced glutathione content of intact erythrocytes increased by 15% after hyperbaric hyperoxia and remained elevated 24 h after exposure. In isolated membranes prepared from the same cells activation of [9,10-3H]oleic acid to acyl thioester and its transesterification into phospholipid did not change after hyperoxia. Since the ability of intact cells to replace oxidized fatty acids in membrane phospholipids via deacylation and reacylation in situ may be necessary for the maintenance of membrane integrity during exposure to oxidative stress, the decrease in [9,10-3H]oleic acid incorporation by human erythrocytes detected in vitro after hyperbaric hyperoxia in vivo may reflect an early event in the pathogenesis of oxygen-induced cellular injury and may be a useful index for assessment of the tolerance of tissues to hyperoxia.     

Construction of fifteen human chromosome-specific DNA libraries from flow-purified chromosomes

We report the construction of 15 human chromosome-specific DNA libraries. Metaphase chromosomes were purified by flow sorting and the DNA was extracted and cleaved with HindIII before cloning into the lambda vector Charon 21A. A sensitive miniblot hybridization method was used to monitor the physical and biochemical steps in the cloning procedure. Using this method, we have developed a highly efficient protocol for producing large numbers of recombinant phage from 0.2-1.0 X 10(6) sorted chromosomes. DNA from the following chromosomes was cloned: #4, 6, 8, 9, 11, 13, 14 + 15, 16, 17, 18, 19, 20, 21, 22 and Y. These libraries are available to the scientific research community and will be valuable in the genetic analysis of the human genome.     

Population Dynamics of Meloidogyne incognita and Rotylenchulus reniformis Alone and in Combination,and Their Effects on Sweet Potato

Meloidogyne incognita (Mi) and Rotylenchulus reniformis (Rr) interactions on sweet potato were studied in naturally and artificially infested field plots for 3 years. In a naturally infested field, early season counts of Mi or Rr were positively correlated with later counts of the same nematode, but negative correlations were found between early Mi and subsequent Rr, and early Rr and subsequent Mi counts. In field plots fumigated with methyl bromide and then infested with low levels of Rr, Mi, and Rr + Mi, final population densities of Mi juveniles were reduced by Rr, but Rr was not affected by Mi. In field plots with a high natural population density of Rr, artificial infestation with high levels of Mi in both fumigated and nonfumigated treatments inhibited Rr, while the final Mi juvenile population density was not affected. Results indicate that a competitive interaction exists with each species capable of inhibiting the other and becoming the dominant population. The nematodes had no apparent effect on yield at the inoculum densities used, either alone or mixed. Both nematodes increased cracking of sweet potatoes, but mixed populations did not differ in incidence of cracking from either Rr or Mi alone.     

“Ischaemic” Colitis in Young Adults

Four cases of transient haemorrhagic colitis seen in young adults resemble 10 others in the literature. The 14 cases are distinguished from the classical transient ischaemic colitis syndrome by their youth, the low incidence of stricture formation, and the prevalence of right-sided lesions.     

Starch Gel Electrophoresis of Catalase and Esterase Isoenzymes from Some Rhizobium and Agrobacterium spp.

S ummary : The esterase and catalase isoenzymes of Agrobacterium tumefaciens and A. radiobacter have been compared to those of the fast growing rhizobia using starch gel electrophoresis. An overall similarity was found for the agrobacteria-rhizobia group although the majority of the agrobacteria possessed only one catalase. Those agro-bacteria with 2 catalases gave patterns similar to Rhizobium meliloti and were 3-ketolactose negative. Agrobacterium pseudotsugi isoenzymes, although fitting the general agrobacteria-rhizobia pattern, were not identical to any specific isogram. The taxonomic value of these findings is discussed.