Does PBAN play an alternative role of controlling pheromone emission in the cabbage looper moth,Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae)?

There is an active process by which sex pheromone reserves of female cabbage looper moths, Trichoplusia ni, are transported to the gland's surface during the nocturnal period of calling. We hypothesized that this mobilization was controlled by a head factor, possibly related to the pheromone biosynthesis activating neuropeptides (PBAN) that in other species stimulate pheromone synthesis. We evaluated the impact of head extracts of T. ni on pheromone emission and glandular content of pheromone. During the photophase injected head extracts stimulated an increased pheromone emission rate in females, but glandular content of pheromone was not affected. Head extracts of H. virescens, a species with known PBAN activity, and synthetic PBAN stimulated an increased pheromone emission rate in T. ni. There was some specificity of the response of female T. ni to PBAN, in that several other unrelated polypeptides did not stimulate this type of response. Previously it had been determined that brain factors do not play a role in stimulating pheromone biosynthesis in T. ni. Our results indicate that there may be additional avenues by which PBAN or related neuropeptides control pheromone emission, including transport of pheromone reserves to the surface of the sex pheromone gland.     

Cross-protection among lethal H5N2 influenza viruses induced by DNA vaccine to the hemagglutinin.

Inoculation of mice with hemagglutinin (HA)-expressing DNA affords reliable protection against lethal influenza virus infection, while in chickens the same strategy has yielded variable results. Here we show that gene gun delivery of DNA encoding an H5 HA protein confers complete immune protection to chickens challenged with lethal H5 viruses. In tests of the influence of promoter selection on vaccine efficacy, close correlations were obtained between immune responses and the dose of DNA administered, whether a cytomegalovirus (CMV) immediate-early promoter or a chicken beta-actin promoter was used. Perhaps most important, the HA-DNA vaccine conferred 95% cross-protection against challenge with lethal antigenic variants that differed from the primary antigen by 11 to 13% (HA1 amino acid sequence homology). Overall, the high levels of protection seen with gene gun delivery of HA-DNA were as good as, if not better than, those achieved with a conventional whole-virus vaccine, with fewer instances of morbidity and death. The absence of detectable antibody titers after primary immunization, together with the rapid appearance of high titers immediately after challenge, implicates efficient B-cell priming as the principal mechanism of DNA-mediated immune protection. Our results suggest that the efficacy of HA-DNA influenza virus vaccine in mice extends to chickens and probably to other avian species as well. Indeed, the H5 preparation we describe offers an attractive means to protect the domestic poultry industry in the United States from lethal H5N2 viruses, which continue to circulate in Mexico.     

Microsomal and lysosomal enzymes of triacylglycerol metabolism in rat placenta.

The placenta plays a major role in transporting lipid to the developing foetus. Since previous studies have suggested that placental lipid transport involves intermediate esterification steps, we investigated selected microsomal and lysosomal enzymes of triacylglycerol metabolism in rat placenta. Between gestational days 10 and 14, microsomal phosphatidic acid phosphatase specific activity was 6-fold greater than the activity in adult rat liver. Phosphatidic acid phosphatase activity decreased 50% on day 15. Studies employing several different phosphorylated substrates indicated a high degree of substrate specificity. Lysosomal triacylglycerol lipase and cholesterol esterase activities decreased about 50% between days 15 and 18, then rose late in gestation. No changes were observed in the specific activities of fatty acid: CoA ligase, glycerolphosphate acyltransferase, lysophosphatidate acyltransferase, diacylglycerol acyltransferase or diacylglycerol cholinephosphotransferase during the final 12 days of gestation. Kinetic observations (competitive inhibition by alternative substrates, pH-dependence and thermal inactivation) were consistent with the hypothesis that glycerol phosphate and dihydroxyacetone phosphate can be acylated by a single microsomal enzyme in placenta. Except for fatty acid: CoA ligase, the activities of microsomal and lysosomal enzymes of triacylglycerol metabolism were comparable with those in adult rat liver. These observations are consistent with physiological studies suggesting that triacylglycerol synthetic and degradative pathways are very active in rat placenta.     

A common-immunogenic Vibrio outer membrane protein

Abstract The presence of antibodies in rabbit antisera to cell envelope proteins of Vibrio cholerae has been examined using a two-dimensional system, in which the cell envelopes are electrophoresed in sodium dodecyl sulfate (SDS) in polyacrylamide gels in the first dimension, and in agarose containing antibodies in the second. The results show that a 25-kDa protein is markedly immunogenic and appears to be common to Vibrio strains; it is not present in a number of other organisms. This 25-kDa protein is an outer membrane protein as judged by sucrose gradient centrifugation and it is accessible to iodination by lactoperoxidase, suggesting that it is exposed on the cell surface.     

The role of the conjugated carbonyl of cytochalasin A in contractility inhibitions

A study of the mechanism of action of cytochalasin A (CA) in relation to its structural features and to its selective inhibition of certain contractile processes has been initiated. Quantitative structure-function analyses with several CA-related cytochalasins — including synthetic 21, 22-dihydro-CA (DHCA), the 22-β-mercaptoethanol CA-adduct, (CA-2ME), and the 22-dithiothreitol CA-adduct (CA-DTT) — have been carried out in a temperature sensitive gel-sol extract from Ehrlich ascites tumor cells. Each drug congener was purified to homogeneity by HPLC prior to biological testing. The undiminished inhibitory indices of DHCA and CA-2ME $\text{(}\text{ID}{}_{\mathrm{5\; 0}}\text{? 3.7 × 10}{}^{\mathrm{?7}}\text{M}\text{)}$ overrules the prior circumstantial evidence accumulated for the obligatory electrophilic interaction of this drug, at its α-β-unsaturated ketone region, with presumptive receptor nucleophiles.     

Activation of human B lymphocytes. XIV. Characterization of the precursor of the pokeweed mitogen-induced anti-sheep red blood cell plaque-forming cell.

The precursor of the pokeweed mitogen (PWM)-induced anti-sheep red blood cell (SRBC) plaque-forming cell (PFC) in human peripheral blood was characterized. By a variety of purification procedures, it was demonstrated to be a lymphocyte with surface characteristics of a B cell. Furthermore, it was demonstrated to bind to sheep erythrocytes (E) and thus segregated with the E-rosetting T cells when T cell enrichment was performed by differential fractionation of E-rosetting cells. This binding of the PFC precursor to E was blocked by pretreating the lymphocyte with anti-human Ig before E rosetting, indicating that the PFC precursor specifically bound to SRBC by a surface Ig molecule with binding specificity for sheep red blood cell determinants. Hence, the precursor of the PWM-triggered anti-SRBC PFC is a B lymphocyte with surface Ig expressing specificity for SRBC.     

The growth and differentiation of transitional epithelium in vitro

The development of rat transitional epithelial cells grown on conventional non-permeable surfaces was compared with development on permeable collagen supports. On glass or plastic surfaces, cells grew as expanding nomolayer sheets. Once confluent, growth continued with a bilayer being formed in most areas and apical cells being continuously sloughed off. Although most cells were interconnected by desmosomes, and junctional complexes were formed, no other indications of differentiation were observed. After 2-3 wk of growth, division stopped and cel death ensued. In contrast, single-cell suspensions plated on collagen-coated nylon disks reassociated into multicellular islands and commenced growth. Mitoses were confined to the basal cells in contact with the permeable substrate. The islands developed into epithelial trilayers, tapering to monolayers along spreading edges. Once the islands were confluent, stratification was completed and appeared similar to that observed in vivo. Germinal cells formed a basal lamina, and the upper layer was composed of large, flattened cells with an unusually thick asymmetrical plasma membrane on the apical surface. Electron microscopic and radioactive tracers demonstrated "leaky" zonulae occludentes with a restricted permeability to small molecules. The movement of urea was retarded in comparison to water. Unlike the slow turnover of adult epithelium in vivo, maturation and sloughing of apical cells were measurable. Transfer of cells could be effected and growth maintained for up to 4 mo. These results may indicate the necessity of a nutrient-permeable growth surface for the polarized differentiation of adult transitional epithelium.