Distribution of vasoactive intestinal peptide-like immunoreactivity in the taste organs of teleost fish and frog

Summary Using immunohistochemistry, vasoactive intestinal peptide (VIP) was visualized in taste bud cells of the carp, Cyprinus carpio, and the European catfish, Silurus glanis, by means of light and electron microscopy. Intracellular membrane systems, presumably smooth endoplasmic reticulum, of light (sensory) cells, but not of dark (supporting) cells and basal cells, were densely labelled with antibody. In the frog (four species: Rana temporaria, R. ridibunda, R. arvalis, R. pipiens), taste bud cells did not label. However, the dense basal nerve fibre plexus, some subepithelial ganglionic cells, but no ascending intragemmal fibres, were immunoreactive. In fish, the results support evidence that VIP is involved in the modulation of taste transduction at the level of receptor cells. In the frog, an indirect, possibly vasodilatatory effect on taste perception may be considered.     

Capillary recruitment and transit time in the rat lung

Presson, Robert G., Jr., Thomas M. Todoran, Bracken J. DeWitt, Ivan F. McMurtry, and Wiltz W. Wagner, Jr.Capillary recruitment and transit time in the rat lung.J. Appl. Physiol. 83(2): 543-549, 1997.Increasing pulmonary blood flow and the associated rise incapillary perfusion pressure cause capillary recruitment. The resultingincrease in capillary volume limits the decrease in capillary transittime. We hypothesize that small species with relatively high restingmetabolic rates are more likely to utilize a larger fraction ofgas-exchange reserve at rest. Without reserve, we anticipate thatcapillary transit time will decrease rapidly as pulmonary blood flowrises. To test this hypothesis, we measured capillary recruitment andtransit time in isolated rat lungs. As flow increased, transit timedecreased, and capillaries were recruited. The decrease in transit timewas limited by an increase in the homogeneity of the transit time distribution and an increased capillary volume due, in part, to recruitment. The recruitable capillaries, however, were nearly completely perfused at flow rates and pressures that were less thanbasal for the intact animal. This suggests that a limited reserve ofrecruitable capillaries in the lungs of species with high restingmetabolic rates may contribute to their inability to raiseO₂ consumption manyfold abovebasal values.

     

Reduction kinetics of the photo-oxidized chlorophyll a+II in the nanosecond range: Measurements of the absorption changes at 688 nm under repetitive flash excitation

The 688 nm absorption changes (ΔA₆₈₈), indicating the photochemical turnover of chlorophyll a_II (Chl a_II) have been investigated under repetitive laser flash excitation conditions in spinach chlorplasts. It was found that under steady state conditions about 50–60% of the photo-oxidized primary donor of Photosystem II (PS II), Chl a⁺_II, becomes re-reduced with a biphasic kinetics in the nanosecond time scale with half-life times of about 50 ns and 400 ns. The remaining Chl a⁺_II becomes re-reduced in the microsecond range.     

Amino terminus of the interleukin-8 receptor is a major determinant of receptor subtype specificity.

Interleukin-8 (IL-8) is a key mediator in the migration of neutrophils from the circulation to the site of inflammation in the tissue. IL-8 is secreted by many cell types in response to proinflammatory stimuli such as interleukin 1, tumor necrosis factor, and lipopolysaccharide and is a potent chemoattractant and activator of neutrophils. Neutrophil activating peptide-2 (NAP-2) and melanoma growth-stimulatory activity (MGSA/GRO) are structurally and functionally related to IL-8 and, like IL-8, bind to specific G protein-coupled receptors on neutrophils. In the present study two closely related cloned IL-8 receptor subtypes are characterized by expression of the cDNA clones in monkey kidney cells (COS-7) or chinese hamster ovary cells and analysis of their ligand binding profiles. Both receptor subtypes bind 125I-labeled IL-8 with similar high affinity, however, the F3R receptor binds IL-8 exclusively, while the 4Ab receptor binds both IL-8 and MGSA/GRO with high affinity and NAP-2 with lesser affinity. Furthermore, we demonstrate with the use of intersubtype chimeric receptors that the specificity of ligand binding to both IL-8 receptor subtypes is dictated by the heterogeneous NH2-terminal domain. The F3R receptor is representative of a restricted IL-8 receptor subtype, and 4Ab represents a nonrestricted receptor subtype. It is proposed that these subtypes be named IL-8 receptors alpha and beta, respectively.     

Designation of Streptomycete 16S and 23S rRNA-based target regions for oligonucleotide probes.

The 16S and 23S rRNA of various Streptomyces species were partially sequenced and screened for the presence of stretches that could define all members of the genus, groups of species, or individual species. Nucleotide 929 (Streptomyces ambofaciens nomenclature [J.L. Pernodet, M.T. Alegre, F. Boccard, and M. Guerineau, Gene 79:33-46, 1989]) is a nucleotide highly unique to Streptomyces species which, in combination with flanking regions, allowed the designation of a genus-specific probe. Regions 158 through 203 of the 16S rRNA and 1518 through 1645 of the 23S rRNA (helix 54 [Pernodet et al., Gene 79:33-46, 1989]) have a high potential to define species, whereas the degree of variation in regions 982 through 998 and 1102 through 1122 of the 16S rRNA is less pronounced but characteristic for at least certain species. Alone or in combination with each other, these regions may serve as target sites for synthetic oligonucleotide probes and primers to be used in the determination of pure cultures and in the characterization of community structures. The specificity of several probes is demonstrated by dot blot hybridization.     

Primary structure of yeast proteinase B inhibitor 2.

The complete amino acid sequence of yeast proteinase B inhibitor 2 (IB2) was determined to be H3N+-Thr-Lys-Asn-Phe-Ile-Val-Thr-Leu-Lys-Lys-Asn-Thr-Pro-Asp-Val-Glu-Ala-Lys-Lys-Phe-Leu-Asp-Ser-Val-His-His-Ala-Gly-Gly-Ser-Ile-Leu-His-Glu-Phe-Asp-Ile-Ile-Lys-Gly-Tyr-Thr-Ile-Lys-Val-Pro-Asp-Val-Leu-His-Leu-Asn-Lys-Leu-Lys-Glu-Lys-His-Asn-Asp-Val-Ile-Glu-Asn-Val-Glu-Asp-Lys-Glu-Val-His-Thr-Asn-COO-. Elucidation of the primary structure was enabled by automated Edman degradation and COOH-terminal hydrolysis with carboxypeptidases A (bovine pancreas and Y (yeast). IB2 is the first proteinase inhibitor to be sequenced that possesses a structure devoid of disulfide bridges.     

Aspects of the cross transmission to Galleria mellonella of a Baculovirus from the alfalfa looper, Autographa californica

The nuclear polyhedrosis virus originally isolated from the alfalfa looper, Autographa californica, was successfully transmitted to the greater wax moth, Galleria mellonella. Both the many polyhedra per nucleus (MP) and the few polyhedra per nucleus (FP) plaque variants of this virus were found to be infective when injected intracoelomically. When polyhedra of each plaque variant were fed to G. mellonella larvae, a difference in response was observed; the MP plaque variant was estimated to be 30 times more infective than the FP variant.