Isolation and characterization of human immunodeficiency virus type 1 variants infectious to brain-derived cells: detection of common point mutations in the V3 region of the env gene of the variants.

T-cell-line-tropic human immunodeficiency virus type 1 cannot infect CD4-positive, brain-derived cells. We isolated several new variants that readily infected brain-derived cells. Mutation of proline to serine, to alanine, or to threonine in the well-conserved GPGR sequence in the V3 region of the envelope glycoprotein was found in all these variants. This indicates the importance of amino acid sequences at the tip of the V3 region for brain cell tropism of human immunodeficiency virus type 1.     

Effect of pH on sulfite oxidation by Thiobacillus thiooxidans cells with sulfurous acid or sulfur dioxide as a possible substrate.

The oxidation of sulfite by Thiobacillus thiooxidans was studied at various pH values with changing concentrations of potassium sulfite. The optimal pH for sulfite oxidation by cells was a function of sulfite concentrations, rising with increasing substrate concentrations, while that by the cell extracts was unaffected. The sulfite oxidation by cells was inhibited at high sulfite concentrations, particularly at low pH values. The results from kinetic studies show that the fully protonated form of sulfite, sulfurous acid or sulfur dioxide, is the form which penetrates the cells for the oxidation.     

Influence of Fusarium wilt toxin(s) on carnation cells

The influence of culture filtrates of Fusarium oxysporum f.sp. dianthi which causes Fusarium wilt was investigated on growth and viability of carnation tissue cultures and leaf segments. Culture filtrates of avirulent race 1 of this fungus did not affect calli and leaf segments of cultivars both susceptible and resistant to Fusarium wilt. However, culture filtrates of virulent race 2 decreased viability and suppressed growth of callus of the susceptible cultivar. In contrast, callus of the resistant cultivar showed resistance to the culture filtrates. The results of these experiments may provide information on methods of selection of new wilt resistant carnation varieties.Abbreviations A270 absorbance at 270 nm - 2,4-d 2,4-dichlorophenoxyacetic acid - CF-MCD culture filtrate of 16064 grown in MCD medium - MCD medium modified Czapeck-Dox medium - MS medium basal medium of Murashige and Skoog - MW molecular weight - PD medium potato dextrose medium - TTC 2,3,5-triphenyl tetrazolium chloride     

Effects of exercise on rats subjected to tail suspension

Deterioration of vital functions is observed in living organisms in microgravity. However, this deterioration can be arrested by adequate exercises. In this study, utilizing tail suspension in rats to simulate microgravity, we examined the influence of running exercise every other day on blood constituents, visceral parameters, and muscles.     

Age distribution,sex ratio and mortality of the red foxVulpes vulpes in Tochigi,central Japan: an estimation using a museum collection

One hundred and thirty carcasses of the red fox were collected in Tochigi Prefecture, by the Tochigi Prefectural Museum, from 1981 to 1991. The young/adult ratio of the sample was 1.60, which suggests that the hunting pressure has been relatively low in this area. Six percent of the animals were 5 years or older which compares to those taken in Hokkaido, but is higher than those in Europe and North America. The sex ratio for all specimens had a tendency towards male bias (0.587), but this bias was higher for the adult (0.605) than for the young (0.576). Among young (0 year-old) foxes, more individuals were killed on roads than by trapping or shooting (P<0.02, chisquare test). This mortality pattern was caused by high mortality of young males (P<0.02). The proportions of adults killed by the three mortality factors were similar, though only one of the 14 foxes older than 4 years old was shot, probably due to age-linked activity patterns. Most road-kills of young foxes occurred in May when juveniles began exploiting and in November when sub-adults began dispersal. The ratios of road-kills for the whole sample and for adults alone were 42% and 34%, respectively. These high rates of road-kills suggest that the mortality pattern in Tochigi has been affected by factors characteristic of urban environments.     

Reclassification of “Flavobacterium arborescens” (Frankland and Frankland) Bergey et al. in the genusMicrobacterium (Orla-Jensen) Collins et al., asMicrobacterium arborescens comb. nov., nom. rev.

Flavobacterium arborescens (Frankland and Frankland) Bergey et al. IFO 3750 (ATCC 4358) is a Gram-positive, coryneform bacterium and the only available reference strain of the species. The cell wall peptidoglycan of the organism possesses alanine, glycine, lysine, glutamic acid plus 3-hydroxyglutamic acid, and homoserine at a ratio of 1:3:1:1:1, and a possible peptidoglycan structure is the B1 type described by Schleifer and Kandler. Cell wall sugars are galactose, mannose, and 6-deoxy-l-talose, but not rhamnose. Major menaquinones are unsaturated MK-11 and MK-12. These findings and other taxonomic properties suggest that F. arborescens should be reclassified in the genusMicrobacterium (Orla-Jensen) Collins et al., asMicrobacterium arborescens comb. nov., nom. rev.     

Halophilic Nuclease of a Moderately Halophilic Bacillus sp.: Production, Purification, and Characterization

A moderately halophilic bacterium, Bacillus sp., isolated from rotting wood on the seashore in Nauru, produced an extracellular nuclease when cultivated aerobically in media containing 1 to 2 M NaCl. The enzyme was purified from the culture filtrate to an electrophoretically homogeneous state by ethanol precipitation, DEAE-Sephadex A-50 column chromatography, and Sephadex G-200 gel filtration. The enzyme consisted of two charge isomers and showed both RNase and DNase activities. Molecular weight was estimated to be 138,000 by Sephadex G-200 gel filtration. The enzyme had marked halophilic properties, showing maximal activities in the presence of 1.4 to 3.2 M NaCl or 2.3 to 3.2 M KCl. The enzyme hydrolyzed thymidine-5′-monophosphate-p-nitrophenyl ester at a rate that increased with NaCl concentration up to 4.8 M. In the presence of both Mg²⁺ and Ca²⁺, activity was greatly enhanced. The activity was lost by dialysis against water and low-salt buffer, but it was protected when 10 mM Ca²⁺ was added to the dialysis buffer. When the inactivated enzyme was dialyzed against 3.5 M NaCl buffer as much as 68% of the initial activity could be restored. The enzyme exhibited maximal activity at pH 8.5 and at 50°C on DNA and at 60°C on RNA and attacked RNA and DNA exonucleolytically and successively, producing 5′-mononucleotides.     

The preventive influence of cysteamine on the teratogenic action of 5-azacytidine.

The radioprotective agent cysteamine can prevent the teratogenic action of 5-azacytidine in rat fetuses. The preventive influence of cysteamine was observed when applied to the mother not only 3 hours and 30 minutes before the 5-azacytidine administration, but also 30 minutes after it. However, the application of cysteamine 3 hours after the administration of 5-azacytidine showed no preventive influence.