Comparative studies on myosin ATPase of a flying and nonflying bird.

Myosin was purified from the flight muscles of a flying (pigeon) and a nonflying (fowl) bird. Ki (ADP) of myosin ATPase of pigeon is higher, but the Km (ATP) is lower than that of fowl. The specific activity (mumole of Pi liberated/min/mg protein) is higher for the fowl. A0.5 (CaCl2) of myosin of both pigeon and fowl is similar. However, the two proteins differ in their interactions with ADP, ATP and p-chloromercuribenzoate. The two proteins have the same tyrosine, tryptophan and sulfhydryl contents. The electrophoretic patterns of the two myosins on SDS-polyacrylamide gels are different. These studies show significant molecular differences in the myosin derived from the flight muscles of a flying (pigeon) and a nonflying (fowl) bird.     

Effect of Ceramide on Nonraft Proteins

The currently accepted model of biological membranes involves a heterogeneous, highly dynamic organization, where certain lipids and proteins associate to form cooperative platforms (“rafts”) for cellular signaling or transport processes. Ceramides, a lipid species occurring under conditions of cellular stress and apoptosis, are considered to stabilize these platforms, thus modulating cellular function. The present study focuses on a previously unrecognized effect of ceramide generation. In agreement with previous studies, we find that ceramide leads to a depletion of sphingomyelin from mixtures with palmitoyl oleoyl phosphatidylcholine bilayers, forming a ceramide–sphingomyelin-rich gel phase that coexists with a fluid phase rich in palmitoyl oleoyl phosphatidylcholine. Interestingly, however, this latter phase has an almost fourfold smaller bending rigidity compared to a sphingomyelin–palmitoyl oleoyl phosphatidylcholine mixture lacking ceramide. The significant change of membrane bulk properties can have severe consequences for conformational equilibria of membrane proteins. We discuss these effects in terms of the lateral pressure profile concept for a simple geometric model of an ion channel and find a significant inhibition of its activity.     

A genome-wide Drosophila screen for heat nociception identifies α2δ3 as an evolutionarily conserved pain gene

Worldwide, acute, and chronic pain affects 20% of the adult population and represents an enormous financial and emotional burden. Using genome-wide neuronal-specific RNAi knockdown in Drosophila, we report a global screen for an innate behavior and identify hundreds of genes implicated in heat nociception, including the α2δ family calcium channel subunit straightjacket (stj). Mice mutant for the stj ortholog CACNA2D3 (α2δ3) also exhibit impaired behavioral heat pain sensitivity. In addition, in humans, α2δ3 SNP variants associate with reduced sensitivity to acute noxious heat and chronic back pain. Functional imaging in α2δ3 mutant mice revealed impaired transmission of thermal pain-evoked signals from the thalamus to higher-order pain centers. Intriguingly, in α2δ3 mutant mice, thermal pain and tactile stimulation triggered strong cross-activation, or synesthesia, of brain regions involved in vision, olfaction, and hearing.     

Survey of keratinophilic fungi inhabiting Passer domesticus in two districts of Orissa,India

The distribution patterns of keratinophilic fungi isolated from Passer domesticus of a coastal (Puri) and an intercoastal (Dhenkanal) district were compared with respect to three parameters, season, age and sex. Irrespective of the parameters, Chrysosporium tropicum and Rollandina hyalinospora showed the highest frequency of occurrence. Their occurrence in the birds was not determined by any ecological or environmental condition in nature. Thus these fungi exhibited their ecological maturity or firm establishment in nature. The maximum fungal distribution occurred during the monsoon season and was minimal in the summer. Juvenile birds were active carriers of the fungi and the male birds harboured the maximum number of fungi. Thus male juvenile birds carried the maximum number of keratinophilic fungi during the monsoon season. The free-living P. domesticus enhances the degree of dispersal of keratinophilic fungi, it being in frequent contact with human artifacts, breeding in settlements and town gardens Eusynanthropic habit. The fungi so dispersed are called mesoornithochorus as their occurrence in birds is determined to a certain degree by avian habits.     

Identification of members of the P-glycoprotein multigene family.

Overproduction of P-glycoprotein is intimately associated with multidrug resistance. This protein appears to be encoded by a multigene family. Thus, differential expression of different members of this family may contribute to the complexity of the multidrug resistance phenotype. Three lambda genomic clones isolated from a hamster genomic library represent different members of the hamster P-glycoprotein gene family. Using a highly conserved exon probe, we found that the hamster P-glycoprotein gene family consists of three genes. We also found that the P-glycoprotein gene family consists of three genes in mice but has only two genes in humans and rhesus monkeys. The hamster P-glycoprotein genes have similar exon-intron organizations within the 3' region encoding the cytoplasmic domains. We propose that the hamster P-glycoprotein gene family arose from gene duplication. The hamster pgp1 and pgp2 genes appear to be more closely related to each other than either gene is to the pgp3 gene. We speculate that the hamster pgp1 and pgp2 genes arose from a recent gene duplication event and that primates did not undergo this duplication and therefore contain only two P-glycoprotein genes.     

When identical functional groups are not identical: A DFT study of the effects of molecular environment on sulfur K-edge X-ray absorption spectra

Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations have been used to elucidate differences in the sulfur K-edge spectra of three pairs of related compounds: methionine and , cystine and (±)6-thioctic amide, and (Me)₂SO₃ and (CH₂)₂SO₃. TD-DFT is shown to accurately reproduce all the experimental XAS spectra. The 2 eV energy difference in the sulfur K-edge rising edge position between methionine and trimethylsulfonium is shown to derive from changes in bonding rather than the increase in effective nuclear charge. A similar insensitivity to effective nuclear charge is found in the XAS spectra of cystine and (±)6-thioctic amide. These surprising results are traced back to the fact that XAS spectra reflect orbital energy differences, rather than a measure of the atomic potential. The change in atomic potential following oxidation or reduction affects the core and valence orbitals almost equally. In all cases DFT calculations showed that the dramatic differences in sulfur K-edge spectra found between functional groups in alternative molecular environments derive from the variations in orbital mixing and energies following from bonding. However, XAS rising-edge energy positions have a near linear correlation with oxidation state. This is attributed to the fact that bond strength typically increases with oxidation state. Therefore, although XAS rising-edge energies are an approximate measure of the oxidation state of the absorbing atom, it is important to recognize that the correlation of XAS edge energy with effective nuclear charge is not direct. This result is finally applied to the question of quantitative sulfur speciation in complex materials of chemical, biological, or geological origin.     

IL-10 and natural regulatory T cells: two independent anti-inflammatory mechanisms in herpes simplex virus-induced ocular immunopathology

Two prominent anti-inflammatory mechanisms involved in controlling HSV-1-induced corneal immunopathology (stromal keratitis or SK) are the production of the cytokine IL-10 and the activity of natural regulatory T cells (nTregs). It is not known whether, under in vivo conditions, IL-10 and nTregs influence the corneal pathology independently or in concert. In the current study using wild-type and IL-10(-/-) animals, we have assessed the activity of nTregs in the absence of IL-10 both under in vitro and in vivo conditions. The IL-10(-/-) animals depleted of nTregs before ocular infection showed more severe SK lesions as compared with the undepleted IL-10(-/-) animals. In addition, nTregs purified from naive WT and IL-10(-/-) animals were equally able to suppress the proliferation and the cytokine production from anti-CD3-stimulated CD4(+)CD25(-) T cells in vitro. Furthermore, intracellular cytokine staining results indicated that nonregulatory cells expressing B220 and CD25 markers were the major IL-10-producing cell types in the lymphoid tissues of HSV-infected mice. In contrast, in the infected corneas, cells with the CD11b(+)Gr1(+) phenotype along with a minor population of Foxp3(-)CD4(+) and a few F4/80(+) cells produced IL-10. Our current investigations indicate that at least two independent anti-inflammatory mechanisms are involved in limiting the corneal lesions in SK, both of which may need to be modulated to control SK therapeutically.