Behavioural ecology of the Sloth bear (Melursus ursinus)

The Sloth bear ( Melursus ursinus ), which is endemic to the Indian subcontinent and Sri Lanka, has declined in numbers in many areas in recent years probably as the result of over-killing and habitat alteration. In the 544 km² Royal Chitawan National Park in the Nepal terai, we estimated there were a minimum of 55 bears or a crude density of 0˙1/km². During peak concentrations in the lowlying riverine forest/tall grass habitat in March, the ecological density was 0˙5/km².
Cubs still with their mothers comprised 24 % of the 161 bears classified between December 1972 and November 1975. Females comprised 48% of the adults classified. Average size of 24 litters was 1˙6 (1–2). Seventy-two per cent of the observations were of lone individuals. Three (an adult female with two cubs), was the largest group of bears seen. The only extended social group observed was the female-young unit although newly independent siblings may remain together for a short time. Maternal relations, adult interactions, tree marking, ranging, feeding and anti-predatory behaviour are described.
Examination of 139 droppings showed that these bears fed on at least 17 different fruits (47% occurrence), flowers, grass, honey, and six different insects (52% occurrence). Fruits were an important food from March to June with individual species predominating throughout their fruiting season. Termites, including Odontotermes obesus , were in the diet for most of the year. The Sloth bear was not observed preying on mammals and according to other observers, only rarely feeds on carrion. The ecological basis for selected aspects of Sloth bear biology and behaviour is discussed.     

Hydrocortisone inhibition of the bradykinin activation of human synovial fibroblasts

Human synovial fibroblasts in culture respond to bradykinin with a 20-fold increment in intracellular cyclic AMP concentrations, however bradykinin does not directly activate adenylate cyclase activity in a particulate fraction derived from these cells. Bradykinin evokes a release of labeled arachidonic acid and prostaglandins E and F from synovial fibroblasts pre-labeled with ³H-arachidonic acid. Hydrocortisone inhibits the bradykinin induced increment in cyclic AMP and the release of arachidonic acid and prostaglandins E and F from synovial fibroblasts. Indomethacin, which also inhibits the cyclic AMP response to bradykinin, has no effect on the release of arachidonic acid from synovial fibroblasts. Indomethacin does, however, inhibit the quantity of prostaglandins released into the medium. These studies support the hypothesis that bradykinin does not activate human synovial fibroblast adenylate cyclase, but presumably activates a phospholipase whose products in turn result in the synthesis of prostaglandins. These and other investigations also suggest that a product(s) of the prostaglandin pathway causes the increment in cyclic AMP.     

Plasmids and serotypes of hemolytic fecalEscherichia coli

Twelve of 21 human, hemolytic, fecal isolates ofEscherichia coli produced type 1 hemolysin (HLY1), an extracellular, heat-labile molecule (alpha-hemolysin). Although no common plasmid species was apparent, 11 of 12 HLY1 strains possessed a plasmid60 megadaltons (Mdal); 5 of 9 strains with other hemolysins possessed a plasmid of comparable molecular mass (Fisher's exact probability=0.0805). One derivative of an HLY1+strain, which contained a 125 Mdal plasmid, no longer expressed HLY1 and contained a single 102 Mdal plasmid. The presence of large plasmids of varying size and an apparent deletion mutation in HLY1 strains suggest that HLY1 determinants are located on a small, unstable genetic element. In an initial survey of 224 human fecal isolates ofE. coli, the predominant hemolytic serotype was 06:H-, and conversely most (85%) 06:H-isolates were HLY1+. Serotype appears to play an important role in HLY1 expression.