Somatic Embryogenesis and Plant Regeneration from Leaf Callus of Hordeum vulgare

Explants obtained from the basal portion of leaves of Hordeumvulgare (cv. Karan 92) gave rise to callus when cultured onMurashige and Skoog (MS) basal medium supplemented with 2, 4-dichlorophenoxyaceticacid (2, 4-D). Initially, the callus was friable, shiny-whiteand watery but subsequently some compact, nodular callus appeared.The latter were cultured on MS medium containing 0.05 mg l^–12, 4-D and 0.1 mg l^–1 N6-furfurylaminopurine (kinetin),when plantlets were generated. Histological studies showed thatplantlet regeneration occurred by the formation of somatic embryos.The regenerated plants had the normal diploid chromosome number(2n = 14). Hordeum vulgare, barley, somatic embryogenesis, tissue culture, plant regeneration     

Seasonal distribution, parity, resting, host-seeking behavior and association of malarial parasites of Anopheles stephensi Liston in Kolkata, West Bengal

Indoor resting and human-landing mosquito collections were conducted at selected localities in Kolkata, India to determine resting and host-seeking behavior, night biting activity, seasonal distributions and malaria infection rates. During a two-year study (2006–2007), 5123 and 1716 female mosquitoes were captured in indoor-resting and human-landing collections, respectively, from two types of residences (brick built rooms, temporary huts). Regression analysis demonstrated that the abundance of indoor resting An. stephensi was positively correlated with ambient temperature and relative humidity. The average duration of the gonotrophic cycle for laboratory-reared An. stephensi was about 4 days. Average proportion of parous An. stephensi , daily survival and daily mortality rates were 46%, 82% and 18%, respectively. Plasmodium vivax sporozoite infections were detected in the salivary glands of two wild-caught An. stephensi (sporozoite rate 2.2%) and one An. annularis (sporozoite rate 1.5%). No P. falciparum infections were detected. Oocyst infections were observed in one An. annularis mosquito (oocyst rate 1.5%).     

Somatic Embryogenesis and Plant Regeneration from Cultured Leaf Explants of Zea mays

Young leaf segments of Zea mays L. seedlings were cultured onMurashige and Skoog's basal nutrient medium supplemented with2 mg l^–1 2, 4-D and sub-cultured on medium containing8 mg l^–1 2,4-D. Two types of callus tissues appeared—embryogenicand non-embryogenic. The embryogenic callus tissue producednumerous somatic embryos which on transfer to media containinglow amounts of 2,4-D or ABA produced plantlets. Callus tissuesexhibited embryogenic potential for more than 1 year. Zea mays L. cv. Ageti-76, Zea mays L. cv. N-L-D-Comp., maize, leaf, callus, somatic embryogenesis, regeneration     

IN VITRO EFFECT OF SUCROSE FEEDING IN THE DIFFERENTIATION OF WOOD ELEMENTS OF PLUMERIA

Wood with cambium of Plumeria rubra Linn. was cultured in modified Schenk and Hildebrandt medium for 75 days. Change in dimension and frequency of cells was compared with that grown in situ for 75 days. Feeding of 41% sucrose in vitro brought about the same type of differentiation as occurred in situ , where non-reducing sugar percentage increased (from 0.0004 before culture to 0.0032 after 75 days' growth in situ ). Sucrose favoured enlargement of axial elements and numerical increase of all lignified elements.     

INTERCELLULAR COMMUNICATION IN RAPIDLY PROLIFERATING AND DIFFERENTIATED C6 GLIOMA CELLS IN CULTURE

Glial cells in the brain are known to provide structural and functional supports to neurons. To sustain such a supportive role, they have developed cell-to-cell communicating gap junctional channels. The authors studied the effect of dbcAMP on gap junctional channels mediated communication in C6 cells, a rat glioma cell line. Quantitative assessment of coupled cells under microscope after microinjection of a fluorescent dye was taken as a measure of junctional permeability. An enhanced coupling between cells was observed following dbcAMP treatment and this elevated coupling was found to be dependent on the duration of exposure of cells to dbcAMP. The studies have focused on a subtle shift in the spatial organization of the functional channels to the processes of dbcAMP induced differentiated cells from the cell cytoplasms and membranes of dbcAMP untreated cells. Immunofluorescence study with affinity purified antibody against gap junction further confirmed the spatial distribution of gap junctional protein(s) in the processes and also showed an increase in the density of the protein at the intercellular spaces in dbcAMP induced differentiated C6 glioma cells.     

Experimental Infection of Nosema sp. Ghose in an Unnatural Host Lesioderma sericorne

ABSTRACT. Various doses of a microsporan parasite, Nosema sp., were fed to third and fourth instar larvae of Lesioderma sericorne that infested different types of stored grains. A spore dose of 3 × 10³ spores/individual resulted in a 39% infection rate, reduction in larval and adult weights, and mean spore concentrations of 1.28 ± 0.2 × 10⁸ spores/larva and 1.1 ± 0.2 × 10⁸ spores/adult. At the above dose, mortality was not well marked (about 35% in larvae and 25% in adults). At 3 × 10⁴ spores/individual, the rate of mortality increases to 80% in larvae and 60% in adults. However, more of the pest population (88% of larvae and 73% of adults) died at a dose of 3 × 10⁵ spores/individual. This dose produced mean spore concentrations of 3.91 ± 0.2 × 10⁸ spores/larva and 2.89 ± 0.2 × 10⁸ spores/adult. Insect death was caused by heavy damage to gut epithelia and fat bodies.