Nucleotide sequence of the Streptococcus faecalis plasmid gene encoding the 3'5"-aminoglycoside phosphotransferase type III

We have cloned in Escherichia coli and sequenced a 1489-bp DNA fragment conferring resistance to kanamycin and originating from the streptococcal plasmid pJH1. The resistance gene was located by analysis of the initiation and termination codons in an open reading frame (ORF) of 792 bp. The deduced gene product, a 3'5'-aminoglycoside phosphotransferase of type III, has an Mr of 29,200. Comparison of its amino acid sequence with those of type I (Oka et al., 1981) and type II (Beck et al., 1982) 3' phosphotransferase, from transposable elements Tn903 and Tn5, respectively, indicated a statistically significant structural relationship between these enzymes from phylogenetically remote bacterial genera. The degree of homology observed indicate that phosphotransferase type III and type I genes have diverged from a common ancestor and that the phosphotransferase type II gene has emerged more recently from the type I evolutionary pathway.     

Gene fusion vectors based on the gene for staphylococcal protein A

Two plasmid vectors, containing the gene coding for staphylococcal protein A and adapted for gene fusion, have been constructed. These vectors will allow fusion of any gene to the protein A gene, thus giving hybrid proteins which can be purified, in a one-step procedure, by IgG affinity chromatography. As an example of the practical use of such vectors, the protein A gene has been fused to the lacZ gene of Escherichia coli. E. coli strains containing such plasmids produce hybrid proteins with both IgG binding and β-galactosidase activities. The hybrid protein(s) can be immobilized on IgG-Sepharose by its protein A moiety with high efficiency without losing its enzymatic activity and they can be eluted from the column by competitive elution with pure protein A. The fused protein(s) also binds to IgG-coated microtiter wells which means that the in vivo product can be used as an enzyme conjugate in ELISA tests.     

Chemical interactions with herpes simplex type 2 virus: Enhancement of transformation by hydrazine and 1,2-dimethylhydrazine

Quantitative assays for the morphological transformation of 3T3 Swiss mouse cells by herpes simplex type 2 virus (HSV-2) were employed to examine the effect on cell transformation of chemical carcinogens and suspected carcinogens. Exposure of the cells to the chemical compound, followed by virus infection, resulted in enhancement of transformation when compared to that observed with chemical or virus alone. Enhancement occurred in tests utilizing either UV light-inactivated HSV-2 (strain 333) or a temperature-sensitive (ts) mutant of HSV-2 [A₈(293)]. A series of seven ts-mutants were tested and exhibited varying degrees of transformation. Enhancement of transformation occurred in cells treated with hydrazine (HZ) and 1,2-dimethylhydrazine (SDMH). No enhancement occurred when cells were treated with monomethylhydrazine, 1,1-dimethylhydrazine and the jet fuels JP-5, JP-10, RJ-4 and RJ-5. A strong time dependence after treatment was demonstrated with some enhancement seen at 6 h after chemical treatment but the greatest enhancement appeared when virus infection began after 24 h of chemical exposure.     

组织型纤溶酶原激活剂的发光分析法及其应用

 本文建立了组织型纤溶酶原激活剂(t-PA)活力的发光固相测定方法。用氨基乙基丁基异鲁米诺(ABEI)标记纤维蛋白原(Fg),在一定条件下,t-PA作用于固相(包被ABEI-Fg),产生纤维蛋白的降解产物。测定可溶性降解产物的发光强度,即能计算t-PA活性。该方法的标准曲线范围对t-PA为0.156IU/mL～40IU/mL。灵敏度可达0.156IU/mL。回收率为98.6％(n=27)。批内批间变异系数分别为6.6％及10.3％。该方法曾用于检测细胞培养液中提取t-PA样品及t-PA基因表达时培养液中t-PA的活性。也曾用于检测从组织中纯化t-PA样品及血浆中t-PA活性的测定。文中讨论了该方法与其它方法优缺点的比较。     

Life Cycle of Paramecium bursaria Syngen 1 in Nature

ABSTRACT. Studies were completed on the natural population density of Paramecium bursaria syngen 1 and on the life cycle stages to which the individuals belonged. Green paramecia were collected from two streams once every 20 days for over one year: 413 individuals on 26 collection dates in Mikumarikyo stream and 83 individuals on 23 collection dates in Momijidani-gawa stream. Individuals in nature did not maintain at a steady density but fluctuated greatly depending on the month. It seems that conjugation occurred from April to June in the Mikumarikyo stream and from May to June in the Momijidani-gawa stream. The appearance of individuals with mating ability might be related closely to increasing population so that sexual reproduction probably occurred near the peak of the population density. The 413 individuals from Mikumarikyo stream were examined to determine their position within the life cycle; 309 (74%) were immature, 55 (13%) were adolescent, and 49 (12%) were mature. No senile individuals were observed. The fraction of individuals with mating ability was generally less than 30% at any collection. Four mating types were observed occurring with about equal frequencies in mature individuals. The results show the frequencies of the recessive genes for mating types (a and b) are higher than for dominant genes (A and B). Of 83 individuals from Momijidani-gawa stream, 44 (52%) were immature, 21 (25%) were adolescent, and 18 (21%) were mature. Again, no senile individuals were observed. Because only two mating types were found, II and III (genotypes aaB- and aabb), it seems possible that the dominant gene A was rare or absent in the Momijidani-gawa population.     

Classification and ecological characterization of coniferous forest phytogeocoenoses of Hokkaido,Japan

Coniferous forest phytogeocoenoses of Hokkaido Island, Japan, were studied to classify them based on vegetation characteristics, to analyse their soils, to correlate the vegetation and soil characteristics, and to provide some ecological interpretation for the phytogeocoenosis differentiation and establishment. Five forest types were distinguished based on the vegetation structure, each of which was comparable to plant association of Krajina (1960); 1. the moss type, 2. the Sasa kurilensis type, 3. the Sasa senanensis type, 4. the Carex sachalinensis type, and 5. the Dryopteris crassirhizoma type. Soil base status indicated by pH, electric conductivity, amount of calcium and magnesium, and base saturation showed a fair correlation with the forest types. The forest types were, therefore, arranged along a soil nutritional gradient. The moss type developed in the least fertile habitats whereas the Dryopteris crassirhizoma type in the most fertile habitats, and others were in between the two. It was suggested that in the island, where climate was humid with excess of soil water throughout a year, soil nutritional regime, more specifically availability of bivalent cations which tended to be removed by the excessive soil water, seemed to be a critical factor to differentiate and establish the forest types.This study was financially supported by the Science Research Grant of the (Monbusho) Japanese Goverment (Grant No. 60540422).     

Increased Neopterin Levels in Brains of Patients with Human Immunodeficiency Virus Type 1 Infection

Postmortem levels of native neopterin (D-erythro-neopterin) were measured in cerebral cortical samples from 44 human immunodeficiency virus type 1-infected and eight uninfected, nonneurological control patients. Cerebral cortical gray and white matter neopterin levels for the controls ranged from 0.5 to 7.2 pmol/mg of protein in contrast to neopterin levels in brains of the virus-infected patients, which frequently were more than threefold and occasionally more than 30-fold higher than mean control levels. Cortical neopterin levels did not correlate with severity of the acquired immunodeficiency syndrome dementia complex, but subcortical levels correlated with the presence of active human immunodeficiency virus type 1 infection, as reflected by pathological evidence of multinucleated giant cell encephalitis. Evidence of opportunistic cytomegalovirus infections in approximately 25% of the human immunodeficiency virus type 1-infected patients was associated with enhanced levels of neopterin in frontal cortex.     

Thecab-m7 gene: a light-inducible,mesophyll-specific gene of maize

Southern blot analysis has revealed the existence in maize of perhaps 12 members of the nuclearcab multigene family encoding the chlorophylla- andb-binding proteins of the photosystem II light-harvesting complex. Hybridization with 3 probes derived from unsequenced cDNA clones showed that six members of this family differ from one another with respect to expression in mesophyll and/or bundle sheath cells and regulation by light. An additional member of this family, designatedcab-m7, that encodes a 28 kDa primary translation product has now been identified. It has been cloned from a maize genomic library and sequenced to begin to define the bases for differences in the expression of these genes. Thiscab gene is shown to be strongly preferentially expressed in the mesophyll (vs. bundle sheath) cells of maize. Furthermore, the gene is photo-responsive; although small amounts ofcab-m7 mRNA are present in etiolated leaves, the mRNA pool is 8-fold larger after six hours of illumination. DNA sequences upstream of thecab-m7 gene resemble those found in the 5-flanking regions of some other plant genes.     

Enxymological characterization of a putative canine analogue of primary hyperoxaluria type 1

This paper concerns an enzymological investigation into a putative canine canalogue of the human autosomal recesive disease primary hyperoxaluria type 1 (alanine:glyoxylate / serine:pyruvate aminotransferase deficiency). The liver and kidney activities of alanine:glyoxylate aminotransferase and seribe:pyruvate aminotransferase in two Tibetan Spaniel pups with familial oxalate nephripathy were markedly reduced when compared with a variety of controls. There were no obvious deficiencies in a number of other enzymes including d-glycerate dehydrogenese / glyoxylate reductase which have been shown previously to be deficient in primary hyperoxaluria type 2. Immunoblotting of liver and kidney homogenates from oxalotic dogs also demonstrated a severe deficiency of immunoreactive alanine:glyoxylate aminotransferase. The developmental expression of alanine:glyoxylate / serine:pyruvate aminotransferase was studied in the livers and kidneys of control dogs. In the liver, enzyme activity and immunoreactive protein were virtually undetectable at 1 day old, but then increased to reach a plateau between 4 and 12 weeks. During this period the activity was similar to that found in normal humanb liver. The enzyme activities and the levels of immunoreactive protein in the kidneys were more erratic, but they appeared to increase up to 8 weeks and then decrease, so that by 36 weeks the levels were similar to those found at 1 day. The data presented in this paper suggest that these oxalotic dogs have a genetic condition that is anlogous, at least enzymologically, to the human disease primary hyperoxaluria type 1.     

Predicting the distribution of plant communities using annual rainfall and elevation: an example from southern Africa

Abstract. Using the results of a total floristic survey of two veld types (Arid Sweet Bushveld and Mixed Bushveld) in the northeastern Transvaal, South Africa, we linked median annual rainfall from a surface response model to each of 139 samples. The samples had been classified floristically into 15 plant communities. These communities represent two broad divisions, corresponding with the concepts embodied in the two veld types. Using contingency tables, we defined the conditions of median annual rainfall and elevation for each of the veld types. Using a geographic analysis system we predicted the distribution of the veld types in an area of 120 000 km² outside the study area. The predicted distribution was validated by comparison with a digitized version of the Acocks map. We conclude that the defined conditions of median annual rainfall and elevation provide confident criteria for the definition of these veld types.