Effect of vitamin A deficiency on rat hepatic and colon epoxide hydrase

Summary Rat liver microsomes and homogenized mucosal linings prepared from vitamin A-supplemented and deficient male rats were used in metabolic studies of 7-³H-styrene oxide. The colon tissue in deficient animals exhibits a significantly higher value of V_max than the same tissue from vitamin-supplemented animals. The implications of this finding in addition to our earlier observation¹⁰ is discussed in relation to colon carcinoma.Acknowledgments. This work was supported by USPHS (NIEHS) Grant RO1 ES 00336 and RO1 CA 00270 and funds from Hoffman-La Roche Foundation Research Corporation.     

Excretion and diuretic action of mercurial diuretics

Résumé Huit diurétiques mercuriels ont été étudiés selon la technique deSperber utilisant la circulation porte rénale de la poule. Six d'entre eux ont montrés clairement leur élimination par secrétion tubulaire. Une diurèse acqueuse peut être obtenue avec tous les diuretiques étudiés, dans la plupart des cas elle est unilatérale du c?té injecté. Une diurèse Na et Cl la suit. On peut supprimer la diurèse unilatérale par la probenécide et le vert de bromocrésol. Les composés étudiés sont éliminés à des vitesses très différentes. Ceux qui présentent l'élimination la plus lente, montrent également l'activité diurétique la plus grande et de plus longue durée.      

Defective membrane repair in dysferlin-deficient muscular dystrophy

Muscular dystrophy includes a diverse group of inherited muscle diseases characterized by wasting and weakness of skeletal muscle. Mutations in dysferlin are linked to two clinically distinct muscle diseases, limb-girdle muscular dystrophy type 2B and Miyoshi myopathy, but the mechanism that leads to muscle degeneration is unknown. Dysferlin is a homologue of the Caenorhabditis elegans fer-1 gene, which mediates vesicle fusion to the plasma membrane in spermatids. Here we show that dysferlin-null mice maintain a functional dystrophin-glycoprotein complex but nevertheless develop a progressive muscular dystrophy. In normal muscle, membrane patches enriched in dysferlin can be detected in response to sarcolemma injuries. In contrast, there are sub-sarcolemmal accumulations of vesicles in dysferlin-null muscle. Membrane repair assays with a two-photon laser-scanning microscope demonstrated that wild-type muscle fibres efficiently reseal their sarcolemma in the presence of Ca2+. Interestingly, dysferlin-deficient muscle fibres are defective in Ca2+-dependent sarcolemma resealing. Membrane repair is therefore an active process in skeletal muscle fibres, and dysferlin has an essential role in this process. Our findings show that disruption of the muscle membrane repair machinery is responsible for dysferlin-deficient muscle degeneration, and highlight the importance of this basic cellular mechanism of membrane resealing in human disease.     

Distalization of the Drosophila leg by graded EGF-receptor activity

Arthropods and higher vertebrates both possess appendages, but these are morphologically distinct and the molecular mechanisms regulating patterning along their proximodistal axis (base to tip) are thought to be quite different. In Drosophila, gene expression along this axis is thought to be controlled primarily by a combination of transforming growth factor-beta (TGF-beta) and Wnt signalling from sources of ligands, Decapentaplegic (Dpp) and Wingless (Wg), in dorsal and ventral stripes, respectively. In vertebrates, however, proximodistal patterning is regulated by receptor tyrosine kinase (RTK) activity from a source of ligands, fibroblast growth factors (FGFs), at the tip of the limb bud. Here I revise our understanding of limb development in flies and show that the distal region is actually patterned by a distal-to-proximal gradient of RTK activity, established by a source of epidermal growth factor (EGF)-related ligands at the presumptive tip. This similarity between proximodistal patterning in vertebrates and flies supports previous suggestions of an evolutionary relationship between appendages/body-wall outgrowths in animals.     

Copepod hatching success in marine ecosystems with high diatom concentrations

Diatoms dominate spring bloom phytoplankton assemblages in temperate waters and coastal upwelling regions of the global ocean. Copepods usually dominate the zooplankton in these regions and are the prey of many larval fish species. Recent laboratory studies suggest that diatoms may have a deleterious effect on the success of copepod egg hatching. These findings challenge the classical view of marine food-web energy flow from diatoms to fish by means of copepods. Egg mortality is an important factor in copepod population dynamics, thus, if diatoms have a deleterious in situ effect, paradoxically, high diatom abundance could limit secondary production. Therefore, the current understanding of energy transfer from primary production to fisheries in some of the most productive and economically important marine ecosystems may be seriously flawed. Here we present in situ estimates of copepod egg hatching success from twelve globally distributed areas, where diatoms dominate the phytoplankton assemblage. We did not observe a negative relationship between copepod egg hatching success and either diatom biomass or dominance in the microplankton in any of these regions. The classical model for diatom-dominated system remains valid.     

Pheromone behavioral responses in unusual male European corn borer hybrid progeny not correlated to electrophysiological phenotypes of their pheromone-specific antennal neurons

In genetic studies on the sex pheromone communication system of two races of European corn borer, which use opposite pheromone blends of the E and Z compounds, it was found that antennal olfactory cell response amplitudes to the two compounds were controlled by an autosomal factor, whereas behavioral responses to the blends were controlled by a sex-linked locus. Because of the difference in genetic controls, it was postulated that some unusual males would be produced in F₂ crosses between these two races. These unusual males would have antennal olfactory cells that respond as the Z-race males, but would respond behaviorally to the E blend. The present studies combined behavioral studies in a flight tunnel and single cell electrophysiological studies to show that these unusual males do indeed exist. These findings show that the spike amplitude of peripheral olfactory cells is not important in regulating species- or race-specific pheromone responses, as compared to some central nervous system factor assesses the spike frequencies from different pheromone-component-specific cells on the antenna. This factor seems to be essential in governing the pheromone-blend specific behavioral responses of male moths.     

The distribution of argentaffin cells in the gastrointestinal tract of the sulfamerazine treated rat

Zusammenfassung Eine direkte Korrelation zwischen Serotoninspiegel und der Zahl der argentaffinen Zellen im gastro-intestinalen Trakt normaler Ratten und solcher, die nach Sulfamerazinbehandlung einen höheren Serotoninspiegel aufweisen, wird festgestellt.

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This research was supported by research grants from the National Science Foundation, (No. GB 6105), and from the American Medical Association Education and Research Foundation awarded toJ. H. Thompson. Dr.M. A. Verity kindly prepared the slides.