Bayesian Insight into a Robust Test for Linear Contrast Based on Asymmetric Censored Samples

A robust test for linear contrast using modified maximum likelihood estimators based on symmetrically censored samples proposed by Tiku (1973, 1982a) is studied in this paper from the Bayesian point of view. The effects of asymmetric censoring on this testing procedure is investigated and a good approximation to its posterior distribution in this case is worked out. We also present an example which illustrates the method of obtaining the highest posterior density interval for the linear combination of the unknown location parameters.     

Chick embryonic cells as a source for generating in vitro model of muscle cell dystrophy

Chick embryonic cells can be used to develop an easy and economical in vitro model for conducting studies on the disease muscle dystrophy (MD). For this, the limb myoblasts from 11th day chick embryo were isolated and cultured. To this muscle cell culture, anti-dystroglycan antibody (IIH6) was added so as to target the α-dystroglycan and disrupt the connection between the cytoskeletal proteins and the extracellular matrix (which is a characteristic feature of MD). Cells were allowed to differentiate further and the morphometrics and mRNA expression were studied. The IIH6-treated muscle cells displayed changes in morphometry, contractibility, and also atrophy was observed when compared to the control cultures. Concomitant gene expression studies showed an upregulation in TGF-β expression, while the muscle sculpture genes MYOD1, MYF5, LAMA2 and MYOG were downregulated resembling the MD in vivo. This simple and cost-effective method can be useful in studies to further understand the disease mechanism and also in conducting initial studies on effect of novel pharmacological agents.     

Population ecology of the giant forest hog,Hylochoerus meinertzhageni in Chebera Churchura National Park,Ethiopia

Population, feeding habit, distribution and activity patterns of the giant forest hog (Hylochoerus meinertzhageni) were studied in Chebera Churchura National Park (CCNP), Ethiopia, using line transect sample counts. Population estimate of the hogs was 845 individuals. Among the counted individuals, 42.4% were males and 57.6% were females. Among them, 32.8% were adults, 26.9% were subadults, and 40.3% were piglets. Large sounders of up to 20 individuals were seen during the wet season. They were seen in all habitat types in CCNP with higher abundance in the riverine vegetation. Availability of food, green vegetation cover and water were factors governing distribution of forest hogs in the study area. Grass was the major food item of the hogs (90%), mainly of Panicum sp., Acalypha psilostachya, Cissapelos rigidifolia, Psilotrichum gnaphalobryum and Abutilon ceclii. Feeding was the major activity for which 49.7% of the active daytime was used. Resting (lying down, standing and wallowing) was the next major activity, for which they spent 38.8% of the daytime, followed by other activities (11.5%). Morning and late afternoon activity peaks were more intensive during the dry season. This female‐biased giant forest hog population is expected to sustain in CCNP.     

One-step purification of glucoamylase by affinity precipitation with alginate.

It was found that alginate binds to glucoamylase, presumably through the recognition of starch binding domain of the latter. The present work exploits this for purification of glucoamylases from commercial preparation of Aspergillus niger and crude culture filtrate of Bacillus amyloliquefaciens by affinity precipitation technique in a single-step protocol. Glucoamylase is selectively precipitated using alginate as macroaffinity ligand and later eluted with 1.0 M maltose. In the case of A. niger, 81% activity is recovered with 28-fold purification. The purified glucoamylase gave a single band on SDS-PAGE corresponding to 78 kDa molecular weight. The developed affinity precipitation process also works efficiently for purification of Bacillus amyloliquefaciens glucoamylase from its crude culture filtrate, giving 78% recovery with 38-fold purification. The purified preparation showed a major band corresponding to 62 kDa and a faint band about 50 kDa on SDS-PAGE. The latter corresponds to the molecular weight for alpha-amylase of Bacillus amyloliquefaciens.     

Seed Dispersal by the Sloth Bear (Melursus ursinus) in South India1

Previous studies have shown that sloth bears are mainly myrmecophagous, but in this study, 39 and 83 percent (wet and dry season, respectively) of scats surveyed in South India contained fruits. Seeds from three of six plant species collected from scats germinated faster than seeds not passing through bears; germination percentage was not higher in any of the six species. These results suggest that the sloth bear may play an important role in the population dynamics of fleshy‐fruited species of the region.     

Transfer and Expression of a Multiple Antibiotic Resistance Plasmid in Marine Bacteria

Conjugal transfer of a multiresistance plasmid from Pseudomonas fluorescens to halophilic and halotolerant bacteria was studied under in vitro and in situ conditions. Mating conducted in broth as well as on plates yielded a plasmid transfer frequency of as high as 10⁻³. Among these two, plate mating facilitated conjugal transfer of plasmid, because the cell-to-cell contact is more in plate mating. When P. fluorescens was incubated in seawater, the organism progressively lost its colony forming activity within 15 days. Microscopic examination revealed the presence of very short rods, indicating that the cells have become viable but nonculturable (VNC). Mating conducted in natural seawater without any added nutrients revealed that the conjugal transfer is influenced by the physical state of the donor and the recipients as well as the availability of nutrients. But a plasmid transfer frequency of 10⁻⁷ was obtained even after the donor cells have become VNC suggesting that the nonculturable state and nutrient deprived condition may not limit plasmid transfer. The results suggest that the terrestrial bacteria entering into the seawaters with antibiotic resistance plasmids may be responsible for the prevalence of resistance genes in the marine environment. Received: 4 May 1998 / Accepted: 18 June 1998