The metabolism of starch, glucose, amino acids, purines, pyrimidines and bacteria by the rumen ciliate Polyplastron multivesiculatum.

The large rumen ciliate protozoon Polyplastron multivesiculatum grown in vitro engulfed a wide range of bacteria (from a population density of 10(9) bacteria ml(-1)) at a rate of 1500 to 137000 bacteria h(-1) protozoon(-1). No evidence was found for the preferential engulfment of bacteria of rumen origin. Except for Proteus mirabilis none of the bacteria were digested with the liberation of soluble materials into the medium. Glucose and amino acids were taken up rapidly by P. multivesiculatum compared with the rate of uptake by Entodinium caudatam. Glucose was incorporated into protozoal polysaccharide and into bacteria associated with the protozoa and was used for the synthesis of a wide range of amino acids. Evidence showed that bacteria and free amino acids at the concentrations found in the rumen could supply the protein requirements of the protozoa for division at least once each day.     

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.     

Scaling of limb joint surface areas in anthropoid primates and other mammals

Recently it was reported that limb joint surface areas scale positively allometrically with body weight in anthropoid primates. This was attributed to the biomechanics of weight bearing: larger animals must require relatively larger joint surfaces to withstand relatively greater weight-related stresses on the joints. Our data on humeral and femoral geometry and joint surface areas in 73 species belonging to six mammalian orders (including primates) demonstrate that positive allometry of joint surface areas is not a general phenomenon for mammals and cannot have its basis among Anthropoidea in the biomechanics of weight bearing. We argue that, to the extent that positive allometric scaling of joint surface areas occurs in anthropoid primates, it is an artifact of differences in positional behaviour among distinct taxonomic groups that also happen to differ widely in body weight. Furthermore, we argue that, among mammals ranging in body size from sportive lemurs to giant pandas, functionally similar groups tend to exhibit: (1) linear dimensions (especially diameters and shaft circumferences) that scale in direct proportion to each other; and (2) joint surface areas that scale in direct proportion to the squares of linear dimensions and to the 2/3 power of body mass. In other words, limb bones of functionally similar animals fit the theoretical model of geometric similarity (or skeletal isometry). Differences in relative sizes of joint surface areas are related to differences in force transmission and movement potential among functionally distinct groups of animals.     

Calcium activated proteolysis of fibrous proteins in central nervous system

A Ca²⁺ activated protease(s) capable of hydrolyzing several polypeptides at neutral pH including cytoskeletal proteins, actin, myosin, tubulin and neurofilament triplet was identified in calf brain cortex. The enzyme activity precipitates at 75 mM KCl, pH 6.5 – 7.0 and is inhibited by the sulfhydryl inhibitors, N-ethylmaleimide and para-chloromercuribenzoate and the protease inhibitors, antipain, pepstatin and leupeptin, leupeptin being the most effective.     

Site-specific integration of an F'' lac pro factor in the region of the replication origin (oriC) of E. coli

Summary An episome, F 128, which carries approximately 8x10⁴ base pairs of chromosomal DNA homologous to the lac pro region of the E. coli chromosome, has been found to integrate into the oriC region of the chromosome in a site specific reaction. While the event appears to be recA-dependent, no homology between the episome and this region of the chromosome was detected. The Hfr strains formed result from the integration of intact F 128 molecules. The structure of the Hfr strains generated has been determined and their transfer properties analyzed.     

Formation of supernumerary structures by the embryonic chick wing depends on the position and orientation of a graft in a host limb bud

The relationship between the position transplanted in a host limb bud, the orientation of a graft in a host limb bud, and the extra limb structures formed was studied by juxtaposing normally nonadjacent embryonic chick wing bud tissue. In one series of transplantation operations, two different wedges (ectoderm and mesoderm) of stage 21 right donor posterior wing bud tissue were transplanted to the middle of a host stage 20 to 22 right wing bud such that the dorsal-ventral polarity of the graft and host were the same or reversed. The results of these transplantation operations show that the formation of supernumerary limb structures depends on the position of origin of the donor tissue, the anterior-posterior position transplanted in a host limb bud, and the orientation of the graft in the host limb bud. In a second series of transplantation operations, the relationship between the proximodistal position where posterior donor tissue is transplanted in an anterior host site and the extra structures formed was studied. A wedge of posterior stage 21 right wing bud tissue was transplanted to an anterior proximal or anterior distal site of a stage 22 to 24 host right wing bud. The results of these transplantation operations show that when the donor tissue is transplanted to an anterior proximal position in a host wing bud, then limbs with only a duplicated humerus result, whereas, when transplanted to an anterior distal position, then limbs with a duplicated forearm element and extra digits result.     

An Examination of Morphometric Variations in a Neotropical Toad Population (Proceratophrys cristiceps,Amphibia, Anura,Cycloramphidae)

The species Proceratophrys cristiceps belongs to the genus Proceratophrys within the family Cycloramphidae. These amphibians are found exclusively in South America in the morphoclimatic domain of the semi-arid depression zones in northeastern Brazil known as the Caatinga. We examined intrapopulational variation using univariate and multivariate statistics with traditional and geometric morphometrics, which supported the existence of two morphotypes of this species. Our results indicated significant degrees of variation in skeletal characteristics between some natural populations of this species. Careful analyses of variability levels are fundamental to avoid taxonomic errors, principally in populations that demonstrate characteristics intimately associated with their area of occurrence, as is the case of Proceratophrys cristiceps.