Identification of a new RTX-like gene cluster in Vibrio cholerae

A gene cluster containing two genes in tandem has been identified in Vibrio cholerae ElTor N16961. Each has more than one cadherin domain and is homologous to the RTX toxin family and was common in various V. cholerae strains. Insertional mutagenesis demonstrated that each gene has a role in Hep-2 cell rounding, hemolytic activity towards human and sheep RBCs and biofilm formation. The mutants showed reduced adherence to intestinal epithelial cells as well as reduction of in vivo colonization in suckling mice. These two genes thus code for RTX-like toxins in V. cholerae and are associated with the pathogenecity of this organism.     

Production of glucoamylase by 2-deoxy-D-glucose resistant mutant ofAspergillus terreus 4

Summary A catabolite derepressed mutant of a glucoamylolytic strain ofAspergillus terreus 4 produced 1.8 times more glucoamylase than its parent; the crude enzyme preparation appreciably degraded raw starchy materials like wheat, rice, potato and barley.     

Atmospheric pollen and fungal spores in Hamilton in 1972 estimated by the Hirst automatic volumetric spore trap

A knowledge of the atmospheric pollen and fungal spores is necessary for the diagnosis and management of extrinsic rhinitis and asthma. The Hirst automatic volumetric spore trap has been used for the first time in Canada to identify the quantitative and seasonal incidence of these particles. The trap is easy to operate and has several advantages over the previously used gravity samplers. Tree, grass and ragweed pollens occurred in short, well-defined seasons. Fungal spores greatly outnumbered pollen by 120 to one, and occurred in long, ill-defined seasons. They included large numbers of small basidiospores and ascospores which have previously not been detected in Canada. The latter have not been considered as potential allergens; their clinical importance requires investigation.     

Glycosphingolipids: The putative receptor for staphylococcus aureus enterotoxin-B in human kidney proximal tubular cells

We have investigated the binding of ¹²⁵I-staphylococcal enterotoxin-B (SEB) in cultured human proximal tubular cells. We found that the binding of ¹²⁵I-SEB to PT cells was time and concentration dependent and competitively inhibited by antibody against SEB. Preincubation of cells with trypsin and neuraminidase or with fetuin did not significantly impair the binding of ¹²⁵I-SEB to such cells. In contrast, treatment with endoglycoceramidase completely inhibited the binding of ¹²⁵I-SEB to cells. Neutral glycosphingolipids exerted a concentration-dependent inhibition of ¹²⁵I-SEB binding to such cells, maximum inhibition (96% compared to control) occurred upon incubation of PT cells with neutral glycosphingolipids. Taken together, our studies indicate that SEB specifically binds to a neutral glycosphingolipid in PT cells. In contrast, staphylococcal enterotoxin-A and toxic shock toxin (TST-1) are bound to a protein in such cells.Abbreviations SEB Staphylococcal Enterotoxin-B - SEA Staphylococcal Enterotoxin-A - TST-1 Toxic Shock syndrome Toxin - GSL Glycosphingolipid - PT Proximal Tubular - LPDS Lipoprotein Deficient Serum - PBS Phosphate Buffered Saline     

Effect of vibrating steering on grip strength in heavy vehicle drivers.

The grip strength in both hands of thirty-two heavy vehicle drivers and twenty-two nondrivers ranging from 30 to 60 years of age was investigated. Blood pressure, heart rate and other physical parameters were also investigated. The subjects were drawn at random from the employees of the North Bengal State Transport Corporation and Civil Aviation. Heavy vehicle drivers perform their duties 8 hr per day with an average speed of 60-70 km hour for 4-5 hr of continuous driving at a time. The only significant difference in the physical characteristics of heavy vehicle drivers and nondrivers was their body weight (p less than 0.05). The right and left wrist power of heavy vehicle drivers was respectively 6% and 3% higher than that of nondrivers. The mean blood pressure, heart rate and wrist width were found to be almost same in heavy vehicle drivers and nondrivers. From our studies we concluded that vibrating steering probably has no influence on the grip strength and that performing 8 hr of driving daily does not affect the blood pressure and heart rate in heavy vehicle drivers. However, further studies are needed to determine the influence of vibrating steering on grip strength.     

Symmetrical and asymmetrical sexual isolation among laboratory strains of Drosophila ananassae

Male-choice experiments using five isofemale lines of Drosophila ananassae originating from different localities were performed to study sexual isolation within the species. In most of the crosses homogamic matings outnumber heterogamic ones, and deviation from randomness is statistically significant in 11 of 20 crosses. This provides evidence for positive assortative mating within D. ananassae. Isolation indices range from -0.057 to 0.555. Eleven positive isolation indices are significantly greater than zero. Both types of sexual isolation, symmetrical and asymmetrical, have been observed among different strains. Thus the present results clearly indicate that the laboratory strains of D. ananassae have developed behavioural reproductive isolation as a result of genetic divergence.     

Confirmation of the structure of calliterpenone,a diterpene from Callicarpa macrophylla

The structure and absolute configuration of calliterpenone has been established as 3-oxo-13β-kaurane-16α,17-diol. This conclusion confirms that proposed by Ahmad and Zaman, and the formula suggested previously by Chatterjee et al. is revised.     

Characterization of glucoannylaserom Asperigillus terreus 4

A strain of Aspergillus terreus 4 was found to show extracellular amylolytic activity and the amylase was identified as glucoamylase enzyme. The optimum temperature for the enzyme activity was 60% and it was stable at this temperature for 1 h. The enzyme was optimally active at pH 5.0 and stable between pH 3.0-8.0. Km values of glucoamylase for soluble starch, amylose and amylopectin were 5.9 mg/ml, 4.8 mg/ml and 2.6 mg/ml respectively.