A note on the performance of Rappaport's medium, compared with Rappaport-Vassiliadis broth, in the isolation of salmonellas from meat products, after pre-enrichment

Salmonellas were isolated from meat products using a slightly modified Rappaport's enrichment medium (R25), Rappaport-Vassiliadis procedure (Rappaport's broth containing 10 ml instead of 30 ml of Malachite Green solution and incubated at 43^oC instead of 37^oC), and Muller-Kauffmann's tetrathionate broth. From 255 samples, 89 were found positive with the Rappaport-Vassiliadis procedure, 83 with the R25 broth, whereas only 43 were positive with Muller-Kauffmann broth. It is concluded that the R25 medium may be used as an alternative to the more effective Rappaport-Vassiliadis broth when the only available incubation temperature is 37^oC.     

A comparison of energy budgets and growth effeciency for Aphis fabae Scop. Reared on synthetic diets with aphids reared on broad beans

An energy budget was constructed for A. fabae reared on synthetic diets and compared with that published for aphids living on broad bean. Larval aphids living on broad bean utilized 54% of their energy intake for growth, 4% was lost during respiration and 42% was excreted as honeydew. Aphids living on a synthetic diet utilized 26% of their energy intake for growth and 4% was lost during excretion. 76% was excreted as honeydew. The growth efficiency on a synthetic diet was 20% compared with a value of 50% on plants. The value of synthetic diet experiments in furthering our understanding of aphid nutrition is discussed in the light of these results.

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Résumé Les budgets énergétiques d'Aphis fabae élevé sur des aliments artificiels ont été établis. Du ¹⁴C radioactif a été ajouté aux aliments pour faciliter l'évaluation de la quantité ingérée. Au cours des quatre premiers jours de la vie larvaire le puceron utilise pour sa croissance 0.82 Joules de l'énergie absorbée; les exuvies représentent 0.26 Joules, la respiration 0.16 Joules et l'équivalent de 2.97 Joules sont excrétés sous forme de miellat. Le rendement de croissance est de 20% et la croissance larvaire est de 0,037 mg en poids sec/jour. Ces données sont comparées avec celles obtenous pour des aphides vivant sur fève.Ces pucerons élevés sur fève ont un rendement de croissance de 50% et la croissance larvaire est de 0,056 mg en poids sec/jour. Les pucerons élevés sur milieux artificiels montrent donc une diminution appréciable de leur rendement de croissance et de leur vitesse de croissance, ce qui conduit à discuter les implications de ces observations pour les études nutritionnelles des aphides.

     

人肾上腺内肽能神经的超微结构

应用抗生蛋白链菌素一生物素一过氧化物酶复合物的免疫电镜技术,在相邻切片中,分别观察人肾上腺内ＮＰＹ、ＶＩＰ、ＳＰ和ＣＧＲＰ免疫反应神经纤维的超微结构和免疫反应物的定位。ＮＰＹ和ＶＩＰ免疫反应物位于小颗粒羹泡和线粒体外膜,部分嗜铬细胞呈ＮＰＹ免疫反应阳性。ＳＰ和ＣＧＲＰ免疫反应物主要定位于大颗粒囊泡内。ＳＰ和ＣＧＲＰ免疫反应轴突与嗜铬细胞形成对称性或非对称性的轴体突轴。测量了这４种肽能神经末梢的直径,从而推测其来源,并讨论了该４种神经肽对人肾上腺的作用。     

Restriction-map variation at the zeste-tko region in natural populations of Drosophila melanogaster

Restriction-map variation in 64 X chromosome lines extracted from three different natural populations of Drosophila melanogaster was investigated with seven six-nucleotide-recognizing enzymes for a 20-kb region including the zeste and tko genes. Ten restriction-site and four length polymorphisms (two insertions and two deletions) were detected. Contrary to the predicted lower level of variation for genes on the X chromosome, the level of variation attributable to nucleotide substitution (estimated heterozygosity/nucleotide = 0.004) was similar to that previously reported for autosomal loci. The amount of insertion/deletion variation in the studied region was within the range observed in autosomal regions and thus not explainable by a simple selection model against the effects of insertional mutations. A general lack of linkage disequilibrium between polymorphic sites was observed.      

Evidence of multiple paternity in Morelet's Crocodile (Crocodylus moreletii) in Belize, CA, inferred from microsatellite markers

Microsatellite data were generated from hatchlings collected from ten nests of Morelet's Crocodile (Crocodylus moreletii) from New River Lagoon and Gold Button Lagoon in Belize to test for evidence of multiple paternity. Nine microsatellite loci were genotyped for 188 individuals from the 10 nests, alongside 42 nonhatchlings from Gold Button Lagoon. Then mitochondrial control region sequences were generated for the nonhatchlings and for one individual from each nest to test for presence of C. acutus-like haplotypes. Analyses of five of the nine microsatellite loci revealed evidence that progeny from five of the ten nests were sired by at least two males. These data suggest the presence of multiple paternity as a mating strategy in the true crocodiles. This information may be useful in the application of conservation and management techniques to the 12 species in this genus, most of which are threatened or endangered.     

Nucleocapsid promotes localization of HIV-1 gag to uropods that participate in virological synapses between T cells

T cells adopt a polarized morphology in lymphoid organs, where cell-to-cell transmission of HIV-1 is likely frequent. However, despite the importance of understanding virus spread in vivo, little is known about the HIV-1 life cycle, particularly its late phase, in polarized T cells. Polarized T cells form two ends, the leading edge at the front and a protrusion called a uropod at the rear. Using multiple uropod markers, we observed that HIV-1 Gag localizes to the uropod in polarized T cells. Infected T cells formed contacts with uninfected target T cells preferentially via HIV-1 Gag-containing uropods compared to leading edges that lack plasma-membrane-associated Gag. Cell contacts enriched in Gag and CD4, which define the virological synapse (VS), are also enriched in uropod markers. These results indicate that Gag-laden uropods participate in the formation and/or structure of the VS, which likely plays a key role in cell-to-cell transmission of HIV-1. Consistent with this notion, a myosin light chain kinase inhibitor, which disrupts uropods, reduced virus particle transfer from infected T cells to target T cells. Mechanistically, we observed that Gag copatches with antibody-crosslinked uropod markers even in non-polarized cells, suggesting an association of Gag with uropod-specific microdomains that carry Gag to uropods. Finally, we determined that localization of Gag to the uropod depends on higher-order clustering driven by its NC domain. Taken together, these results support a model in which NC-dependent Gag accumulation to uropods establishes a preformed platform that later constitutes T-cell-T-cell contacts at which HIV-1 virus transfer occurs.     

Genetic barcoding of marine leeches (Ozobranchus spp.) from Florida sea turtles and their divergence in host specificity

Ozobranchus margoi and Ozobranchus branchiatus are the only two species of marine turtle leeches (Ozobranchus spp.) known to inhabit the Atlantic coast of the United States and the Gulf of Mexico. In early reports of fibropapillomatosis (FP) in green turtles (Chelonia mydas), O. branchiatus was implicated as a vector in the transmission of Fibropapilloma‐associated turtle herpesvirus (FPTHV). It is imperative that the leech species be identified to elucidate the role Ozobranchus spp. may play in disease transmission. In this study, Ozobranchus branchiatus has been identified for the first time on a loggerhead (Caretta caretta) turtle, and the molecular data for this species is now available for the first time in GenBank. Both species of leeches were also found infecting a single C. mydas. Using morphological taxonomy combined with distance‐ and character‐based genetic sequence analyses, this study has established a DNA barcode for both species of Ozobranchus spp. leech and has shown it can be applied successfully to the identification of leeches at earlier stages of development when morphological taxonomy cannot be employed. The results suggest a different haplotype may exist for O. branchiatus leeches found on C. caretta versus C. mydas. Leech cocoon residue collected from a C. mydas was identified using the new method.