Chemical Detection of Microbial Prey by Bacterial Predators

A motile, predacious bacterium which degraded Pythium debaryanum was strongly attracted to substances released into the medium by the fungus. A nonpredacious bacterium was not attracted to these substances. The predator bacterium was specifically attracted to cellulose and its oligomers which are known to be components of the cell wall of Pythium. Ethanol inhibited chemotaxis of the bacterium without affecting either its motility or its ability to degrade cellulose. A second predacious bacterium was isolated for the alga, Skeletonema costatum. The role of chemoreception in the detection of microbial prey by bacterial predators in natural habitats is discussed.     

Human placental cathepsin B1. Isolation and some physical properties

A reproducible procedure for the isolation, from human placenta, of a cathepsin B1 in a homogeneous state, demonstrated by electrophoretic, ultracentrifugal and enzymic criteria, was carried out. The pH optimum was near pH5.5. The placental enzyme catalysed the release of acid-soluble u.v.-dense products from haemoglobin and myoglobin. It was inhibited by heavy metals and several compounds which react with the thiol groups. The optimum temperature was between 37° and 42°C. The molecular weight of the enzyme was calculated to be 24250.     

Skin Collagen and Thickness in Women with Hirsuties

Total skin collagen is greatly increased in women with hirsuties. This is presumably due to androgen, whether locally produced or circulating.     

Effect of Pregnancy on Sebum Excretion

Sebum excretion rates from forehead skin were measured serially during and after pregnancy in 10 normal women. Only minor fluctuations occurred during the middle and last trimesters of pregnancy, but there was a pronounced decrease in the postpartum period. Probably a powerful sebotrophic factor is present in pregnancy, but its nature is conjectural.     

Chronic Obstructive Pulmonary Emphysema—Is Exercise Beneficial?

Following a six-week program of training in a series of exercises, a significant number of patients with chronic obstructive pulmonary emphysema showed decided improvement in functional activity. Subjective improvement also was noted and kept the patient motivation high.Preliminary observations indicated that the improvement could be maintained long after the end of the training period.     

Mechanism of cadmium uptake by activated sludge

Summary The significance of metabolic activity in cadmium uptake by unacclimated activated sludge was studied. Below 30 mg/l cadmium in solution, biosorption was found to follow the Freundlich isotherm, which is the most common pattern for physico-chemical adsorption. More than 95% of total cadmium uptake was achieved within 5 min metal-sludge contact time. Biosorption increased strongly when the initial cadmium concentration in solution was raised from 10 to 100 mg/l, whereas in the same concentration range the metabolic activity of the sludge, as measured by respiratory activity and extracellular protein production, was very significantly inhibited. The addition of nutrients at low but significant levels failed to increase cadmium uptake in 2 h contact time, while in 24 h the addition of nutrients caused the biosorption to increase by only 5–10% without any significant growth of the biomass. Biosorption was found to increase with temperature between 5° C and 40° C, in correlation with an increase in the metabolic activity of the sludge. Pretreatment of the sludge with metabolic inhibitors (NaN₃ and UV rays) appeared to cause only a very slight decrease (5–10%) of biosorption. These results suggest that metabolic uptake of cadmium was low and that adsorption to the surface of the cells was the major mechanism of uptake.Offprint requests to: S. S. Sofer     

Preservative-mediated changes of the surface properties ofEscherichia coli

The effectiveness of two commonly used preservatives, sodium benzoate and potassium disulfite, was evaluated in terms of their bactericidal activity and capacity to induce changes in the surface properties ofEscherichia coli isolated from commercial food preserves. Preservative treatment over a five-week test period resulted in controlling the multiplication of these organisms and causing a decline in cell-surface hydrophobicity, hemagglutinating ability and adherence capacity to rat intestinal cells ofE. coli isolates. A loss in motility was also exhibited.     

BRCA1 maps proximal to D17S579 on chromosome 17q21 by genetic analysis

Previous studies have demonstrated linkage between early-onset breast cancer and ovarian cancer and genetic markers on chromosome 17q21. These markers define the location of a gene (BRCA1) which appears to be inherited as an autosomal dominant susceptibility allele. We analyzed five families with multiple affected individuals for evidence of linkage to the BRCA1 region. Two of the five families appear to be linked to BRCA1. One apparently linked family contains critical recombinants, suggesting that the gene is proximal to the marker D17S579 (Mfd188). These findings are consistent with the maximum-likelihood position estimated by the Breast Cancer Linkage Consortium and with recombination events detected in other linked families. Linkage analysis was greatly aided by PCR-based analysis of paraffin-embedded normal breast tissue from deceased family members, demonstrating the feasibility and importance of this approach. One of the two families with evidence of linkage between breast cancer and genetic markers flanking BRCA1 represents the first such family of African-American descent to be reported in detail.