Factors influencing seasonal and monthly changes in the group size of chital or axis deer in southern India

Chital or axis deer (Axis axis) form fluid groups that change in size temporally and in relation to habitat. Predictions of hypotheses relating animal density, rainfall, habitat structure, and breeding seasonality, to changes in chital group size were assessed simultaneously using multiple regression models of monthly data collected over a 2 yr period in Guindy National Park, in southern India. Over 2,700 detections of chital groups were made during four seasons in three habitats (forest, scrubland and grassland). In scrubland and grassland, chital group size was positively related to animal density, which increased with rainfall. This suggests that in these habitats, chital density increases in relation to food availability, and group sizes increase due to higher encounter rate and fusion of groups. The density of chital in forest was inversely related to rainfall, but positively to the number of fruiting tree species and availability of fallen litter, their forage in this habitat. There was little change in mean group size in the forest, although chital density more than doubled during the dry season and summer. Dispersion of food items or the closed nature of the forest may preclude formation of larger groups. At low densities, group sizes in all three habitats were similar. Group sizes increased with chital density in scrubland and grassland, but more rapidly in the latter—leading to a positive relationship between openness and mean group size at higher densities. It is not clear, however, that this relationship is solely because of the influence of habitat structure. The rutting index (monthly percentage of adult males in hard antler) was positively related to mean group size in forest and scrubland, probably reflecting the increase in group size due to solitary males joining with females during the rut. The fission-fusion system of group formation in chital is thus interactively influenced by several factors. Aspects that need further study, such as interannual variability, are highlighted.     

Wnt Pathway Activation Increases Hypoxia Tolerance during Development

Adaptation to hypoxia, defined as a condition of inadequate oxygen supply, has enabled humans to successfully colonize high altitude regions. The mechanisms attempted by organisms to cope with short-term hypoxia include increased ATP production via anaerobic respiration and stabilization of Hypoxia Inducible Factor 1α (HIF-1α). However, less is known about the means through which populations adapt to chronic hypoxia during the process of development within a life time or over generations. Here we show that signaling via the highly conserved Wnt pathway impacts the ability of Drosophila melanogaster to complete its life cycle under hypoxia. We identify this pathway through analyses of genome sequencing and gene expression of a Drosophila melanogaster population adapted over >180 generations to tolerate a concentration of 3.5–4% O₂ in air. We then show that genetic activation of the Wnt canonical pathway leads to increased rates of adult eclosion in low O₂. Our results indicate that a previously unsuspected major developmental pathway, Wnt, plays a significant role in hypoxia tolerance.     

Immobilization of amyloglucosidase on polystyrene anion exchangeresin II. Kinetics and stabilities

Summary Amyloglucosidase (exo-1, 4- -D-glucosidase, EC 3.2.1.3), was coupled to glutaraldehyde activated Indion 48-R (a cross-linked macroporous anion exchanger) by Schiff base reaction. Immobilization brought about a marginal increase in the apparent K_m. The bound enzyme exhibited increased stability towards urea and metal ions, but was less stable in the presence of guanidine hydrochloride. Immobilized amyloglucosidase could be stored at 4°C (in wet state) for 6–8 months without any apparent loss of activity.     

The fate of the fusarium mycotoxin zearalenone in maize cell suspension cultures

The fusarium mycotoxin zearalenone was transformed in cell suspension cultures of Zea mays giving α- and β-zearalenol and the β-D-glu cos ides of zearalenone and α- and β-zearalenol. The structure of zearalenone-4-β-D-glucopyranoside was determined by liquid — chromatography-mass spectrometry and specific hydrolysis with β-glucosidase. α- and β-zearalenol and their glucosides were identified by co chromatography using tic and HPLC and glucosidase — treatment Up to 50% of the mycotoxin added was bound to a non extractable or “bound” residue fraction. After treating this residue by a sequential cell wall fractionation procedure, zearalenone was found to be bound mainly to starch, hemicellulose, and lignin fractions.     

Extraction of non-timber forest products in the Forests of Biligiri Rangan Hills,India. 3. Productivity,extraction and prospects of sustainable harvest of amla phyllanthus emblica, (Euphorbiaceae)

Sustainable extraction of non-timber forest products (NTFPs) depends upon harvesting a small fraction of the total productivity. Over-exploitation can lead to a loss of biodiversity, but a low level of extraction, without value addition at the point of origin, is usually not economically feasible for extractors. Extraction and productivity levels per unit area for most non-timber forest products are unknown, nor do we have much information about value addition at various points in the marketing channels. Here we determine extraction and productivity levels for Amla trees (Phyllanthus emblica), which yield fruits that are used for a wide variety of purposes in preparation of various foods, beverages and medicines. We also present preliminary data on the price appreciation of the fruit for one of the processed products. We have determined that the current level of extraction, 60-80% of all fruits at the population level, may have a negative effect on new recruitment. We present a model for value addition that has the potential to enhance income and reduce the level of extraction. This model is currently being implemented by the Soliga community with the assistance of a non-governmental organization.     

Mutational analysis of nucleoside diphosphate kinase from Pseudomonas aeruginosa: characterization of critical amino acid residues involved in exopolysaccharide alginate synthesis.

We report the utilization of site-directed and random mutagenesis procedures in the gene encoding nucleoside diphosphate kinase (ndk) from Pseudomonas aeruginosa in order to examine the role of Ndk in the production of alginate by this organism. Cellular levels of the 16-kDa form of the Ndk enzyme are greatly reduced in P. aeruginosa 8830 with a knockout mutation in the algR2 gene (8830R2::Cm); this strain is also defective in the production of the exopolysaccharide alginate. In this study, we isolated four mutations in ndk (Ala-14-->Pro [Ala14Pro], Gly21Val, His117Gln, and Ala125Arg) which resulted in the loss of Ndk biochemical activity; hyperexpression of any of these four mutant genes did not restore alginate production to 8830R2::Cm. We identified six additional amino acid residues (Ser-43, Ala-56, Ser-69, Glu-80, Gly-91, and Asp-135) whose alteration resulted in the inability of Ndk to complement alginate production. After hyperproduction in 8830R2::Cm, it was determined that each of these six mutant Ndks was biochemically active. However, in four cases, the in vivo levels of Ndk were reduced, which consequently affected the growth of 8830R2::Cm in the presence of Tween 20. Two mutant Ndk proteins which could not complement the alginate synthesis defect in 8830R2::Cm were not affected in any characteristic examined in the present study. All of the mutant Ndks characterized which were still biochemically active formed membrane complexes with Pk, resulting in GTP synthesis. Two of the four Ndk activity mutants (His117Gln and Ala125Arg) identified were capable of being truncated to 12 kDa and formed a membrane complex with Pk; however, the complexes formed were inactive for GTP synthesis. The other two Ndk activity mutants could be truncated to 12 kDa but were not detected in membrane fractions. These results further our understanding of the role of Ndk in alginate synthesis and identify amino acid residues in Ndk which have not previously been studied as critical to this process.     

Evaluating second year cropping on jhum fallows in Mizoram,north-eastern India—Phytomass dynamics and primary productivity

Cropping on jhum fallows in north-eartern India is predominantly done for one year in a jhum cycle. If second year cropping is done, expanse of the forest land required for slashing and burning could be reduced significantly. We tested this hypothesis in a young (6 yr) and an old (20 yr) jhum fallow. We also evaluated if the productivity during second year cropping could be alleviated by auxiliary measures such as tilling the soil or application of fertilizers (chemical or farm-yard manure or both in combination). The results demonstrate that the ecosystem productivity (total dry matter production) and economic yield (rice grain production) decline with shortening of jhum cycle. Second year cropping causes a further decline in ecosystem productivity in old jhum field, but not in young jhum field. Economic yield from second year cropping in its traditional form (without any fertilizer treatment) is not much lower than that in the first year, and can be improved further by manuring the soil. Tilling of soil improves neither ecosystem productivity nor economic yield. Different fertilization treatments respond differently; while inorganic manuring enhances ecosystem productivity, a combination of inorganic and organic manuring improves economic yield     

Gene transfer is a major factor in bacterial evolution

Lateral gene transfer in four strains of Salmonella enterica has been assessed using genomic subtraction. Strain LT2 (subspecies I serovar Typhimurium) chromosomal DNA was used as target and subtracted by three subspecies I strains of serovars Typhimurium (S21), Muenchen (S71), Typhi (M229), and a subspecies V strain (M321). Data from probing random cosmids of LT2 DNA with preparations of the residual LT2 DNA after subtraction were used to estimate the amounts of LT2 DNA not able to hybridize to strains S21, S71, M229, and M321 to be in the range of 84-106, 191-355, 305-629, and 778-1,286 kb, respectively. Several lines of evidence indicate that most of this DNA is from genes not present in strain M321 and not from genes that have diverged in sequence. The amounts correlate with the divergence of the four strains as revealed by multilocus enzyme electrophoresis and sequence variation of housekeeping genes. Sequence of 39 of the fragments from the M321 subtracted residual LT2 DNA revealed only six inserts of known gene function with evidence of both gain and loss of genes during the development of S. enterica clones. Sixteen of the 39 segments have 45% or lower G+C content, below the species average, but over half are within the normal range for the species. We conclude that even within a species, clones may differ by up to 20% of chromosomal DNA, indicating a major role for lateral transfer, and that on the basis of G+C content, a significant proportion of the DNA is from distantly related species.