X-ray diffraction analysis of particles ingested by fieter-feeding animals

The size and relative abundance of mineral particles ingested by two filter-feeding aquatic insects, Simulium vittatum Zett. (Diptera: Simuliidae) and Aedes triseriatus (Say) (Diptera: Culicidae) were determined by X-ray diffraction methods. Different minerals representing different particle size categories were supplied larval black flies and mosquitoes. Since minerals possess characteristic diffraction properties, their presence and relative abundance can be determined. Early instars of the black fly ingested and retained particles of three different size ranges; however, more coarse particles relative to fine particles were retained by smaller instars as compared with the larger instars. With mosquito larvae, there was a proportional increase in coarser material ingested with increasing age and size of larvae. Other applications of this method are discussed.

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Résumé La dimension et l'abondance relative des particules minérates, ingerées par deux larves d'insectes aquatiques se nourrissant par filtration, Simulium vittatum (Diptera: Simuliidae) et Aedes triseriatus (Diptera: Culicidae) ont été déterminées par diffraction aux rayons X. Divers minéraux sous forme de particules de différentes dimensions ont été fournis aux larves de Simulies et de moustiques. Puisque les minéraux sont caractérisés par leurs propriétés de diffraction, on peut donc vérifier leur présence et déterminer leur relative abondance. Les larves de Simulies des premiers stades retiennent et ingèrent des particules de trois rangs de taille, cependant les particules plus grossières sont mieux retenues dans l'appareil filtreur des jeunes larves, par comparaison avec les larves plus grandes. Avec les larves de moustiques il y a une augmentation de l'ingestion du matériel le plus grossier proportionnellement à l'accroissement d'âge et de taille des larves. D'autres applications de cette méthode sont discutées.

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This research was partially supported by National Science Foundation Grant DEB76-20122, Black Fly Regional Research Project NE-118, and the Michigan State University Agricultural Experiment Station, Journal Article No. 8318.     

Cytosolic androgen receptor in regenerating rat levator ani muscle.

The development of the cytosolic androgen receptor was studied after degeneration and regeneration of the rat levator ani muscle after a crush lesion. Muscle regeneration appears to recapitulate myogenesis in many respects. It therefore provides a model tissue in sufficiently in large quantity for investigating the ontogenesis of the androgen receptor. The receptor in the cytosol of the normal levator ani muscle has binding characteristics similar to those of the cytosolic receptor in other androgen-sensitive tissues. By day 3 after a crush lesion of the levator ani muscle, androgen binding decreased to 25% of control values. This decrease was followed by a 4-5 fold increase in hormone binding, which attained control values by day 7 after crush. Androgen binding remained stable at the control value up to day 60 after crushing. These results were correlated with the morphological development of the regenerating muscle after crushing. It is concluded that there is little, if any, androgen receptor present in the early myoblastic stages of regeneration; rather, synthesis of the receptor may occur after the fusion of myoblasts and during the differentiation of myotubes into cross-striated muscle fibres.     

A mutation in the RNA polymerase β′ subunit causing depressed ribosomal RNA synthesis in Escherichia coli

Molecular Genetics and Genomics - Macromolecular synthesis in an Escherichia coli mutant with a temperature-sensitive β′ subunit of RNA polymerase was analysed. At the non-permissive...     

Theileria parva: Kinetics of infection in the lymphoid system of cattle

The kinetics of infection with Theileria parva in cattle were studied by examining the total cellularity and numbers of parasites in a range of lymphoid organs from animals killed at intervals during the course of the infection. With the dose of T. parva stabilate used, macroschizonts were initially detected in the drainage lymph node about 7 days after inoculation and death of the host resulted on Day 18–19. Associated with the initial detection of parasites, there was a marked increase in cellularity of the drainage lymph node and a more gradual and less pronounced increase in cellularity of the other lymphoid organs. From about Day 12 onward, there was a gradual decrease in the cellularity in all of the lymphoid organs, so that in animals examined in the terminal stages of the infection there was often cellular depletion. The pattern of these cellular changes was similar in groups of Boran and Friesian cattle, although both the increase in cellularity and the terminal depletion were more marked in the Friesians. Blood leukocyte counts in infected Boran started to drop as early as Day 7 of infection and by Day 14 had reached values less than 25% of normal. Quantitation of parasitic schizonts indicated that the numbers of parasites in the lymphoid organs do not increase in a simple exponential manner. Rather, there appears to be an early rapid increase in parasite numbers followed by a phase of less rapid multiplication. Because of the marked changes which occured in total cellularity of the lymphoid organs during the course of the infection, a significant discrepancy was found between the replication rate of the parasite as calculated using total numbers of parasites and that obtained using schizont index (SI). These results indicated that the use of SI, as described in previous studies, is not a reliable method of determining the replication rate of the parasite.     

A rapid and sensitive determination of bacterial rRNA by means of hybridization-competition

A rapid and sensitive liquid hybridization-competition method for the assay of in vitro synthesized Escherichia coli rRNA was developed. Hybridization with homologous DNA and with heterologous DNA from Proteus vulgaris was compared. Besides unfractionated DNA we used DNA enriched for the sites complementary to ribosomal RNA by chromatography on methylated albumin Kieselguhr. Hybridization with heterologous enriched DNA is the method of choice due to its low background and high hybridization efficiency.     

The chromaffin granule surface Localization of carbohydrate on the cytoplasmic surface of an intracellular organelle

Intact chromaffin granules from bovine adrenal medulla are shown to have complex carbohydrates on their external (cytoplasmic) surface. This is demonstrated by the facts (1) that granules can be agglutinated by wheat germ agglutinin, and (2) that significant amounts of sialic acid can be removed from the granule surface with neuraminidase. Glycoproteins located in the granule membrane, and not glycolipids, are the molecules that mediate wheat germ agglutinin agglutination. The possible involvement of granule surface carbohydrate in the process of exocytosis is discussed.     

Serum lactate dehydrogenase isoenzyme 1 activity in patients with testicular germ cell tumors correlates with the total number of copies of the short arm of chromosome 12 in the tumor

Summary The aim of our study was to assess the relationship between the serum lactate dehydrogenase isoenzyme 1 (S-LDH-1) activity in patients with testicular germ cell tumors and the number of copies of the short arm of chromosome 12 (12p) present in tumor. Twenty-seven adult patients with measurable tumor lesions were studied. Twenty-five had three or more copies of chromosome 12 per cell in the tumors. Nineteen had one or more copies of a specific chromosomal abnormality, an isochromosome of the short arm of chromosome 12, i(12p). Fourteen had increased S-LDH-1 levels. S-LDH-1 activity correlated significantly with the product of total tumor volume and the total number of copies of the short arm of chromosome 12 present per cell (total tumor 12p). We conclude that the total number of copies of the short arm of chromosome 12 in the tumors is most probably a factor contributing to the LDH-1 activity released from the tumors.     

Zur Zuggeschwindigkeit der Flu?seeschwalbeSterna hirundo

Zusammenfassung Die Arbeit stellt einen Versuch dar, die Zuggeschwindigkeit einer Vogelart anhand von Ringfunden zu ermitteln, wobei Beringung und Wiederfund nicht innerhalb einer Zugperiode liegen müssen. Bei der Flußseeschwalbe werden in beiden Zugperioden die gleichen Zuggeschwindigkeiten erreicht. Im Frühjahr werden Europa und Teile der nordwestafrikanischen Küste aber rascher durchwandert als auf dem Wegzug. Die Aufenthaltsdauer im Winterquartier ist sehr kurz, weit mehr Zeit muß für den Zug aufgewendet werden. Daher wird auch die Mauser in der Migrationsphase abgewickelt. Die Bestimmung der absoluten Zuggeschwindigkeit nach der verwendeten Methode ist mit einem relativ großen Fehler behaftet. Unter Berücksichtigung dieser Fehlerquellen läßt sich die mittlere Maximalgeschwindigkeit auf 80–110 km/Tag schätzen.

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The speed of migration of the Common TernSterna hirundo

Summary An attempt is being made to determine the speed of migration of birds by means of recoveries of ringed birds. Ringing and recovery need not to be in one period of migration. The Common Tern reaches the same speed in both migration periods. Europe and parts of the northwest African coast are passed quicker during spring than during fall migration. The Common Tern stays only for a short period in its winter quarters; much more time is spent on migration. Therefore moult takes place during migration. As a result of the method applied the estimation of the absolute speed of migration shows a high rate of error. Hence the figures have to be corrected. This corrected estimation gives 80–110 km/day for the Common Tern as the mean maximum speed.