Alien genome mobilization and fixation utilizing an apomixis mediated genome addition (AMGA) strategy in Pennisetum to improve domestication traits of P. squamulatum.

KEY MESSAGE: An approach to release 'frozen' variability in apomictic species using sexuality of another species, eventually its utilization in crop improvement and de-novo domestication of crop wild relatives is presented. Pennisetum squamulatum, a secondary gene pool species of pearl millet (P. glaucum), harbours many desirable traits. However, it was neither utilized to improve pearl millet fodder traits nor improvement of its own domestication traits was attempted, due to the complexities of genomes and apomictic reproduction. To overcome this, we followed an Apomixis Mediated Genome Addition (AMGA) strategy and utilized the contrasting reproductive capacities (sexuality and apomixis) of both the species to access the otherwise un-available variability embedded in P. squamulatum. Segregating population of interspecific hybrids exhibited significant variability and heterosis for desired morphological, agronomical, and nutritional traits. Elite apomictic and perennial hybrids were evaluated in breeding trials, and eventually a novel grass cultivar was released for commercial cultivation in India. The performance of newly developed cultivar was superior to other adapted perennial grasses of arid and semi-arid rangelands. Through AMGA, the sexuality of one species was successfully utilized to 'release' the 'frozen' variability embedded in another species. Subsequently, the hybrids representing desirable trait combinations were again 'fixed' utilizing the apomixis alleles from the male parent in a back-and-forth apomixis-sexual-apomixis selection cycle. This study also demonstrated the potential of AMGA to improve crop relatives through genomes introgression as well as de novo domestication of new crops from wild species.

Gut mucosal lymphocyte subpopulations in the host-defence of Shigella infected guinea-pigs.

Lymphocyte subpopulations from the gut mucosa were studied in Shigella-susceptible guinea-pigs to evaluate their role in mucosal immune responses to such organisms. Four weeks after infection, isolated lymphocytes were characterised by an immunofluorescent technique. The increase in the T cell intra-epithelial population was less (48%) in comparison to that in normal uninfected animals (74%). On the other hand, Ig bearing B cells in the lamina propria showed an increased incidence and more than 15% of the total mucosal lymphocytes lacked any surface marker, which indicated that they were non-T and non-B cells. A significant rise in the intraepithelial T cell population (P less than 0.01) was observed 6 weeks after infection in comparison to that observed after 4 weeks.

Super ORS.

PIP: Oral rehydration therapy (ORT) prevents severe morbidity and death from mild to moderate dehydration from acute diarrhea for all ages and all etiologies. WHO advises ORT fluid to contain 3.5 g sodium chloride, 3.5 g potassium chloride, 2.5 g sodium bicarbonate or 2.9 g trisodium citrate dihydrate, and 20 g glucose all dissolved in 1 1 of water. This fluid does not reduce stool volume or frequency and does not curtail duration thus it is not always acceptable. Improved ORT is needed, however. The glucose concentration cannot be increased above the present 2% since an increased concentration would intensify diarrhea and dehydration. Researchers are working on an improved solution (Super ORS) which would rehydrate the body and actively bring on reabsorption of endogenous secretions in the intestine. Thus this improved ORS would reduce stool volume, shorten duration of diarrhea, and allow early introduction of feeding. Even though some studies demonstrate that fortified ORS with the amino acid glycine decreases stool volume by 49-70% and duration of diarrhea 28-30%, other studies indicate that it induces excess sodium concentrations in the blood. 1 study demonstrates that in comparison with the standard ORS, ORS fortified with the amino acid L-alanine reduced the severity of symptoms and the need for fluid in patients afflicted with cholera and enterotoxigenic Escherichia coli. Further studies reveal that rice powder based ORS (50-80 g/l) reduces stool volume 24-49% and duration of duration 30%. The advantage of using rice is that when it hydrolyzes glucose, amino acids, and oligopeptides emerge. Each 1 of these chemicals facilitate sodium absorption through separate pathways. Disadvantages include the fuel must be used to cook the rice, rice based ORS ferments within 8-24 hours making it useless, and the rice or pop rice needs to be ground.^ieng

Tryptophanase activity in different toxigenic and nontoxigenic strains of Vibrio cholerae: effect of glucose.

Tryptophanase activity was measured in eight different toxigenic and nontoxigenic strains of Vibrio cholerae (V. cholerae) in presence and absence of inducer tryptophan (2 mM). Stimulation of enzyme activity was observed in both toxigenic and nontoxigenic strains of V. cholerae in presence of inducer. Tryptophanase activity remained much higher in toxigenic strains than that in nontoxigenic strains. Low levels of enzyme activity in nontoxigenic strains could be increased by the addition of exogenous cyclic AMP. A lower concentration of glucose (0.25 gm%) in culture medium produced no inhibitory effect on enzyme activity. But a higher concentration of glucose (3 gm%) repressed the tryptophanase activity. The repressive effect of glucose could be reversed by the addition of exogenous cyclic AMP.