Parasitoids of the corn borerOstrinia furnacalis [Lep.: Pyralidae] in the Mariana Islands

A survey of the parasitoids of the Asian corn borer,Ostrinia furnacalis (Guenee), in the Mariana Islands showed that few of the borers were parasitized. Parasitoids were reared from only 30 pupae out of more than 4 500 sampled. Three species of pupal parasitoids were found:Xanthopimpla punctata (F.),Brachymeria albotibialis (Ashmead) andTetrastichus? inferens Yoshimoto. No parasitoids were reared from mature larvae. The only egg parasitoid observed wasTrichogramma chilonis Ishii. During the month prior to the sweet corn harvest, which was the peak period of moth oviposition, about 40% of the egg masses had at least one egg parasitized. An average of about 35% of the eggs within a mass were parasitized.     

Ultrastructure and potential significance of cerebral light-refracting bodies of Stenostomum virginianum (Turbellaria,Catenulida)

Summary Light-refracting bodies, possibly photoreceptors, occurring in the posterior lobes of the brain are considered characteristic for most species of catenulid turbellarians of the freshwater genus Stenostomum. In S. virginianum, each of two light-refracting bodies consists of a single cup-shaped granule (3–4 m) situated in the perikaryon of a single nerve cell (the clear vesicle of earlier papers). TEM reveals each granule as an enlarged and folded mitochondrion with a dense matrix inclusion of undetermined composition. Cristae are well-developed and there is a dense granular extramito-chondrial layer of uniform thickness (100 nm) along the posteromedial surface of the mitochondrion. The perikaryon is packed with ribosomes, -glycogen granules and 60–100 nm dense-cored vesicles. A neurite extends from the perikaryon into the neuropile of the brain. Experimental data indicate an absence of phototaxis and photokinesis and an absence of ultrastructural modifications with light- and dark-adaptation. An ultrastructural comparison is made of the light-refracting bodies of S. virginianum with those of a second species. Hypotheses regarding the role of light-refracting bodies as photoperiodic receptors and/or specialized neurosecretory cells are advanced.This study was supported in part by a National Science Foundation grant DEB-7823395 and a Clemson University Faculty Research Grant to E. Ruppert     

Buchbesprechungen

Ohne Zusammenfassung     

Mathematical approaches to decompression

A flexible mathematical treatment of diver decompression has been developed by modifying the classical Haldanian model of inert gas transport. It is based on the assumption that inert gases will remain in solution in the tissues of a diver as long as a particular metastable limit is not exceeded,and that this limit varies with depth, nature of the inert gas,and the specific time constant of its transport in the body. Proposed metastable limits (M-values)of dissolved helium partial pressure have been developed empirically by the Experimental Diving Unit of the United States Navy. These limits permit the design by digital computer of decompression procedures expected to be safer than contemporary decompression tables for extended deep dives.

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Zusammenfassung Ein flexibles mathematisches Verfahren zur Überwachung der Dekompression bei Tauchern wurde entwickelt, durch Modifikation des klassischen Modells von Haldane für den Transport träger Gase.Es beruht auf der Annahme,dass träge Gase so lange in den Geweben eines Tauchers in Lösung bleiben, als eine bestimmte metastabile Grenze nicht überschritten wird. Diese Grenze ändert sich mit der Tiefe,der Natur des trägen Gases und der spezifischen Zeitkonstante seines Transports im Körper. Die vorgeschlagenen metastabilen Grenzen (M-Werte) des Partialdruckes von gelöstem Helium wurden empirisch entwickelt in der Experimental Diving Unit der Marine der Vereinigten Staaten.Diese Grenzen erlauben die Erfassung der Dekompressionsvorgänge durch Digital Computer und es wird angenommen, dass sie sicherer sind als die gebräuchlichen Dekompressions-Tabellen für langes Tieftauchen.

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Resume On a établi un procédé mathématique fléxible pour suivre les phénomènes de décompression chez les plongeurs.Pour ce faire, on a modifié le modèle classique de Haldane concernant le transport d'un gaz inerte. Comme base, on admet que les gaz inertes resteront en solution dans les tissues des plongeurs aussi longtemps qu'une limite métastatique n'est pas franchie.Cette limite varie avec la profondeur,la nature du gaz inerte et la constante de temps spécifique de son transport dans le corps. Les limites métastatiques proposées (valeurs-M)de la pression partielle de l'hélium dissous ont été déterminées empiriquement à l' "Expérimental Diving Unit"de la marine des Etats-Unis. Ces limites permettent de calculer les processus de décompression au moyen d'ordinateurs.On admet en outre que ce procédé est plus sûr que les tables de décompression usuelles, surtout dans le cas de plongées profondes et de longue durée.

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Based on a paper presented at the Forth International Biometeorological Congress, New Brunswick, N.J., 26 August – 2 September 1966.     

RepSeq – A database of amino acid repeats present in lower eukaryotic pathogens

Background  

Amino acid repeat-containing proteins have a broad range of functions and their identification is of relevance to many experimental biologists. In human-infective protozoan parasites (such as the Kinetoplastid and Plasmodium species), they are implicated in immune evasion and have been shown to influence virulence and pathogenicity. RepSeq is a new database of amino acid repeat-containing proteins found in lower eukaryotic pathogens. The RepSeq database is accessed via a web-based application which also provides links to related online tools and databases for further analyses.     

Molecular heterogeneity in the choroid plexus epithelium: the 22-member γ-protocadherin family is differentially expressed, apically localized, and implicated in CSF regulation

The choroid plexus (CP) epithelium develops from the ependyma that lines the ventricular system, and plays a critical role in the development and function of the brain. In addition to being the primary site of CSF production, the CP maintains the blood-CSF barrier via apical tight junctions between epithelial cells. Here we show that the 22-member γ-protocadherin (γ-Pcdh) family of cell adhesion molecules, which we have implicated previously in synaptogenesis and neuronal survival, is highly expressed by both CP epithelial and ependymal cells, in which γ-Pcdh protein localization is, surprisingly, tightly restricted to the apical membrane. Multi-label immunostaining demonstrates that γ-Pcdhs are excluded from tight junctions, basolateral adherens junctions, and apical cilia tufts. RT-PCR analysis indicates that, as a whole, the CP expresses most members of the Pcdh-γ gene family. Immunostaining using novel monoclonal antibodies specific for single γ-Pcdh proteins shows that individual epithelial cells differ in their apically localized γ-Pcdh repertoire. Restricted mutation of the Pcdh-γ locus in the choroid plexus and ependyma leads to significant reductions in ventricular volume, without obvious disruptions of epithelial apical-basal polarity. Together, these results suggest an unsuspected role for the γ-Pcdhs in CSF production and demonstrate a surprising molecular heterogeneity in the CP epithelium.     

Uric Acid Induces Hepatic Steatosis by Generation of Mitochondrial Oxidative Stress: POTENTIAL ROLE IN FRUCTOSE-DEPENDENT AND -INDEPENDENT FATTY LIVER*

Metabolic syndrome represents a collection of abnormalities that includes fatty liver, and it currently affects one-third of the United States population and has become a major health concern worldwide. Fructose intake, primarily from added sugars in soft drinks, can induce fatty liver in animals and is epidemiologically associated with nonalcoholic fatty liver disease in humans. Fructose is considered lipogenic due to its ability to generate triglycerides as a direct consequence of the metabolism of the fructose molecule. Here, we show that fructose also stimulates triglyceride synthesis via a purine-degrading pathway that is triggered from the rapid phosphorylation of fructose by fructokinase. Generated AMP enters into the purine degradation pathway through the activation of AMP deaminase resulting in uric acid production and the generation of mitochondrial oxidants. Mitochondrial oxidative stress results in the inhibition of aconitase in the Krebs cycle, resulting in the accumulation of citrate and the stimulation of ATP citrate lyase and fatty-acid synthase leading to de novo lipogeneis. These studies provide new insights into the pathogenesis of hepatic fat accumulation under normal and diseased states.     

Cross-relaxation bottleneck in water-lysozyme proton magnetization exchange

The proton spin-lattice relaxation parameters in natural and deuterated lysozyme solutions have been measured as a function of temperature (0-50 degrees C). The variation of the apparent magnitudes of the water proton magnetizations in the solutions with temperature indicates that magnetic coupling mixes protein and water proton magnetizations. The results are consistent with an exchange cross-relaxation model (Hills, B. P., Mol Phys 1992, 76, 489-508) in which the cross-relaxation acts between the labile and nonlabile protons, rather than between water and protein protons. Although this cross-relaxation pathway clearly affects the observed magnetization fractions in this protein solution, its influence on the relaxation rates is less apparent.