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C C Reddy

Publications and source records attributed to C C Reddy.

95 records · Page 6Linked to original sources
PubMedDate not supplied

Open-air-nesting honey bees Apis dorsata and Apis laboriosa differ from the cavity-nesting Apis mellifera and Apis cerana in brood hygiene behaviour.

The cavity-nesting Apis mellifera and Apis cerana bees detect, uncap, and remove diseased brood. The hygiene behaviour of open-air-nesting bees Apis dorsata and Apis laboriosa was investigated in India and Nepal. Sealed A. dorsata pupae were pin-killed or deep-frozen. The workers removed 73 or 37% of damaged pin-killed pupae depending on the diameter of the pins, and only 7% of the frozen undamaged pupae. Migrating A. dorsata and A. laboriosa left unopened the sealed brood in deserted combs. Thus, A. dorsata and A. laboriosa do not open undamaged cells with dead brood. This behaviour is a more efficient mechanism in preventing the spread of diseases and parasitic mites than uncapping and removing dead pupae by A. mellifera and A. cerana. It may be beneficial for migrating A. dorsata and A. laboriosa to temporarily disuse part of the comb cells in exchange for arresting the mites there and thus reducing the increase of their population.

Animals↗
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Biochemistry of selenium: a brief overview.

The chemistry of Se suggests that, in biological systems, it is most likely present as the selenol (selenomercaptan)R-SeH, or, as the Se ether analogous to sulfur in the amino acid methionine. Selenols are stronger acids than mercaptans and, at physiological pH, exist mainly in anionic form (R-Se-) whereas the sulfhydryl group exists mainly in the protonated form. The anionic form of the selenohydryl group is a good nucleophile as well as a good leaving group. Also, it binds metals strongly, which is the principle behind the use of Se compounds for heavy metal detoxification. Conversely, metal ions can strip Se from organoselenium compounds and Hg, Cd, Pb, and Cu are highly effective in this capacity. In vivo, Se compounds tend to undergo reduction in contrast to sulfur compounds which are acquired in reduced form and generally undergo oxidation. Biosynthesis of methylated Se compounds, yielding dimethyl selenide, dimethyl diselenide, or trimethyl selenonium ion, appears to be the major pathway of Se metabolism/detoxification in animals. The highest activity of the pathway has been found in liver and kidney followed by lung, skeletal muscle, spleen, and heart. Selenium (Se) appears to be incorporated into proteins via post transcriptional modification of polypeptides. Six proteins that incorporate/require Se have been isolated: Se-dependent glutathione peroxidase (GSH-Px), the selenoprotein of muscle, selenoflagellin, Se-transport protein, and the bacterial enzymes formate dehydrogenase and glycin reductase. There is evidence also that Se is an essential component of nicotinic acid hydroxylase, xanthine dehydrogenase, and a bacterial thiolase.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗
PubMedDate not supplied

Proliferative response of fibroblasts expressing internalization-deficient epidermal growth factor (EGF) receptors is altered via differential EGF depletion effect.

We describe experiments comparing the proliferation responses to epidermal growth factor (EGF) by NR6 fibroblasts expressing genetically engineered epidermal growth factor receptors (EGFRs). These cells present either wild-type (WT) EGFR or a cytoplasmic domain-truncated (c'973) EGFR that exhibits a decreased ligand-induced internalization rate constant. In two distinct in vitro proliferation assays, with or without medium replenishment, we measured the specific cell proliferation rate constants and EGF depletion kinetics for both WT and c'973 cells. When EGF depletion is minimized by replenishment, the EGF concentration dependencies of the two cell types are similar, whereas when EGF depletion is not prevented, maximal proliferation of WT cells requires an initial EGF concentration that is approximately 10x that required by c'973 cells. However, when EGF depletion is accounted for, the dependencies of growth rate for the two cell types on the current EGF concentration in both assays are essentially identical. Our results demonstrate that diminished depletion of EGF from the extracellular medium is a major reason for increased mitogenic sensitivity to EGF by cells possessing internalization-deficient receptors.

3T3 Cells↗