Cellular uptake of cell-penetrating peptides pVEC and transportan in plants.

Internalization of fluorescently labeled CPPs, pVEC, transportan and scrambled pVEC, in a range of plant cells was investigated. Cellular uptake of the peptides was found to be tissue dependent. pVEC and transportan were distinctly internalized in triticale mesophyll protoplasts, onion epidermal cells, leaf bases and root tips of seven-day old triticale seedlings but showed negligible florescence in coleoptile and leaf tips as observed under a fluorescence microscope. Further, pVEC and transportan uptake studies were focused on mesophyll protoplasts as a system of investigation. In fluorimetric studies transportan showed 2.3 times higher cellular internalization than pVEC in protoplasts, whereas scrambled pVEC failed to show any significant fluorescence. Effect of various factors on cellular internalization of pVEC and transportan in protoplasts was also investigated. The cellular uptake of both the peptides was concentration dependent and nonsaturable. The cellular uptake of pVEC and transportan was enhanced at low temperature (4 degrees C). The presence of endocytic/macropinocytosis inhibitors did not reduce the cellular uptake of the peptides, suggesting direct cell penetration, receptor-independent internalization of pVEC and transportan into the plant cells.     

Purification and characterization of a cellulase-free xylanase of a moderate thermophile Bacillus licheniformis A99

Two cellulase-free xylanases were secreted by a thermophile, Bacillus licheniformis A99. Of the two, the predominant one was purified to homogeneity. The enzyme was optimally active at 60 °C, pH 6–7.5, and had a molecular weight of about 45 KDa and isoelectric point of 7.0 ± 0.2. The K _m (for birchwood xylan) and V _max were 3.33 mg/ml and 1.111 mmols mg^–1 protein min^–1 respectively. The half-life of the enzyme was 5 h at 60 °C. All cations except Hg²⁺ and Ag⁺ as well as EDTA were well tolerated and did not adversely affect xylanase activity. However, SDS inhibited the enzyme activity. The release of reducing sugars from unbleached commercial pulp sample on treatment with the enzyme indicated its potential in prebleaching of paper pulp. The enzyme caused saccharification of lignocellulosics such as wheat bran, wheat straw and sawdust. This is the first report on purification and characterization of cellulase-free xylanase from a moderate thermophile Bacillus licheniformis.     

Effect of Vibriocins on Members of the Enterobacteriaceae

Certain vibriocin producers exhibited antibacterial activity throughout the Enterobacteriaceae. To examine this phenomenon, an effective technique for demonstrating vibriocin production was developed.     

Modifying effect of iron on lead-induced clastogenicity in mouse bone marrow cells

Essential trace elements such as iron (Fe) are known to interact with nonessential metals like lead (Pb), influencing its metabolism. Ferric chloride and lead nitrate were administered intraperitoneally to Swiss albino miceMus musculus singly and successively, with or without a time gap of 1 h, to study the degree of protection, if any, afforded by iron against the clastogenic effects induced by Pb in bone marrow cells. A decrease in the frequency of lead-induced chromosomal aberrations was observed when Fe was given together with or prior to Pb administration.     

Regeneration via somatic embryogenesis from leaf basal segments and genetic transformation of bread and emmer wheat by particle bombardment

Direct gene transformation methods such as microprojectile bombardment have been successfully employed for obtaining transgenics in cereals in general and wheat in particular. As success of any transformation strategy depends largely upon the regeneration capability of the target explant, the present investigation employs leaf basal segments to achieve high regeneration response via somatic embryogenesis. Basal segments of 5-day-old seedlings of T. aestivum var. CPAN1676 and T. dicoccum var. DDK1001 were cultured on callusing medium for 3 weeks at 26 ± 1 °C, discontinuous light followed by a culture period of 15 days at 21 ± 1 °C in continuous light. The calli were then transferred to auxin-free medium for regeneration in discontinuous light at 26 ± 1 °C. Regeneration via somatic embryogenesis was observed within 2 weeks in T. aestivum var. CPAN1676 and T. dicoccum var. DDK1001 (68 and 82%, respectively). This embryogenic calli were employed further to obtain hygromycin resistance by particle bombardment in T. aestivum and T. dicoccum. A transformation efficiency of 8.6, 7.5 and 4.9% was obtained in T. aestivum var. CPAN1676, PBW343 and T. dicoccum DDK1001, respectively. Presence of the transgene hptII (hygromycin) in T ₀ plants was confirmed by Southern hybridization.     

Horizontal gene transfer and bacterial diversity

Bacterial genomes are extremely dynamic and mosaic in nature. A substantial amount of genetic information is inserted into or deleted from such genomes through the process of horizontal transfer. Through the introduction of novel physiological traits from distantly related organisms, horizontal gene transfer often causes drastic changes in the ecological and pathogenic character of bacterial species and thereby promotes microbial diversification and speciation. This review discusses how the recent influx of complete chromosomal sequences of various microorganisms has allowed for a quantitative assessment of the scope, rate and impact of horizontally transmitted information on microbial evolution.