Recalcitrant Grain Legume Vigna radiata, Mung Bean, Made to Regenerate on Change of Hormonal and Cultural Conditions

Induction of shoots is possible from cotyledonary node of Vigna radiata seedlings by culturing them on a low concentration of thidiazuron (TDZ 1.0 μM). Interestingly, flooding the seedlings with the same concentration of TDZ considerably enhanced this effect and also led to the induction of shoots from the epicotyl – an unexpected and significant finding. Even plain mineral medium evoked this response on flooding. But seedlings raised on TDZ and flooding with mineral medium was not so effective. Instead seedlings raised on TDZ (1.0 μM) medium as well as flooding with it had synergistic effect. In a comparative study TDZ (1.0 μM) was found to be more effective than BAP (10 μM). Marked repression of root formation and expansion of shoot–apex were noted in seedlings raised on TDZ or BAP, particularly in cultures that were flooded.     

Opercular Activity and Temporal Organization of Surfacing Behaviour in Indian Catfishes,Clarias batrachus and Heteropneustes fossilis

Opercular and surfacing activity were observed in the Indian catfish Clarias batrachus and Heteropneustes fossilis. In the series A experiments, the opercular activity was monitored under two experimental conditions, viz., (1) surfacing allowed and (2) surfacing prevented. A statistically significant elevation of the rate of opercular activity was observed when air breathing was prevented in both species. In addition, a significant prevention effect and a time of day dependence of that were noticed in both species. In the series B experiments, temporal patterns of surfacing and air-gulping activities were examined under an artificial LD 12:12 schedule at 2-h intervals over a period of 48 h. The inter air-gulping interval in minutes between two consecutive bouts was also recorded four times each day in both species. A significant 24-h rhythm was found for the rate of surfacing activity and length of the inter air-gulping interval in both species. However, the overall activity appears to be much higher in Heteropneustes fossilis as compared to Clarias batrachus.     

Significance of the gonoduct in the classification of echiurans (Phylum Echiura)

The gonoducts of 21 species have been studies. The reliability of the gonoduct as a taxonomic tool has been assessed at different levels of the hierarchy, employing the variations in respect of the number of genital pores, and the modifications in the body of the females for lodging the males in the case of sexually dimorphic echiurans. Special reference has been made to sexually dimorphic echiurans and their position in the taxonomy of the phylum.     

Sequence Analysis of a Plastidial Omega-3 Desaturase Gene from Brassica juncea

A genomic clone (λg₂) encoding a plastidial omega-3 desaturase has been isolated from a genomic library of Brassica juncea cv Pusa Bold and sequenced after subcloning. A continuous stretch of 3866 by of the clone sequenced showed homology with omega-3 desaturase from other plant sources but maximum homology was with that of a plastidial omega-3 fad 7 gene. This sequence designated as Bjgfad7 includes 1381 by 5’ untranslated region, 273 by 3’ untranslated region along with an open reading frame of 1290 by interrupted by 7 introns. The 5’ untranslated region contains putative cis elements responsible for seed specificity, light responsive and stress-inducible expression besides minimal promoter elements.