Seasonally Changing Cryptochrome 1b Expression in the Retinal Ganglion Cells of a Migrating Passerine Bird

Cryptochromes, blue-light absorbing proteins involved in the circadian clock, have been proposed to be the receptor molecules of the avian magnetic compass. In birds, several cryptochromes occur: Cryptochrome 2, Cryptochrome 4 and two splice products of Cryptochrome 1, Cry1a and Cry1b. With an antibody not distinguishing between the two splice products, Cryptochrome 1 had been detected in the retinal ganglion cells of garden warblers during migration. A recent study located Cry1a in the outer segments of UV/V-cones in the retina of domestic chickens and European robins, another migratory species. Here we report the presence of cryptochrome 1b (eCry1b) in retinal ganglion cells and displaced ganglion cells of European Robins, Erithacus rubecula. Immuno-histochemistry at the light microscopic and electron microscopic level showed eCry1b in the cell plasma, free in the cytosol as well as bound to membranes. This is supported by immuno-blotting. However, this applies only to robins in the migratory state. After the end of the migratory phase, the amount of eCry1b was markedly reduced and hardly detectable. In robins, the amount of eCry1b in the retinal ganglion cells varies with season: it appears to be strongly expressed only during the migratory period when the birds show nocturnal migratory restlessness. Since the avian magnetic compass does not seem to be restricted to the migratory phase, this seasonal variation makes a role of eCry1b in magnetoreception rather unlikely. Rather, it could be involved in physiological processes controlling migratory restlessness and thus enabling birds to perform their nocturnal flights.     

Replacement of nucleosomal histones by histone H1-like proteins during spermiogenesis in Cnidaria: Evolutionary implications

We have analyzed the chromosomal protein composition of the sperm from several species belonging to three different classes (Hydrozoa, Scyphozoa, Anthozoa) of the phylum Cnidaria. In every instance, the sperm nuclear basic proteins (SNBPs) were found to consist of one to two major protein fractions that belong to the histone H1 family, as can be deduced from their amino acid composition and solubility in dilute perchloric acid, and the presence of a trypsin-resistant core. In those species where mature spawned sperm could be obtained, we were able to show that these proteins completely replace the somatic histones from the stem cells that are present at the onset of spermatogenesis. The presence of a highly specialized histone H1 molecule in the sperm of this phylum provides support for the idea that the protamine-like proteins (PL) from higher groups in the phylogenetic tree (and possibly protamines as well) may all have evolved from a primitive histone H1 ancestor.     

X-linked dominant inherited diseases with lethality in hemizygous males

Summary X-linked dominant inheritance with lethality in hemizygous males is a rare mode of inheritance. The three best-known disorders which seem to be inherited in this way, are incontinentia pigmenti (IP) Bloch-Sulzberger, oral-facial-digital I (OFD I) syndrome, and focal dermal hypoplasia (FDH syndrome, Goltz syndrome). It is the purpose of this article to give a review of the clinical and genetic aspects of the abovementioned diseases and to add those disorders in which this mode of inheritance is discussed. These disorders are: X-linked chondrodysplasia punctata (CP), cervico-oculo-acusticus syndrome (Wildervanck syndrome, COA), congenital cataract with microcornea or slight microphthalmia, muscular dystrophy-hemizygous lethal, partial lipodystrophy with lipatrophic diabetes and hyperlipidemia, Aicardi syndrome, coxo-auricular syndrome, and Johanson-Blizzard syndrome. OTC defiency is included in the study, although there is no lethality in utero, only in the neonatal period.A critical evaluation of the current literature is carried out.     

Nocturnal activity and orientation behavior during spring migration and early summer in the indigo bunting,Passerina cyanea

Summary Indigo Buntings (Passerina cyanea) that had been trapped in August were kept during the following months under photoperiodic conditions simulating the ones they would normally experience at that time of the year. From April 24 to June 16, their nocturnal activity and their directional tendencies were recorded. It was found that the activity, although it varied greatly from night to night, continued to be high until the termination of the registration period in mid June, whereas the orientation deteriorated at the end of May, i.e., after the end of the normal spring migration (Fig. 1, Table 1). Thus directed spring migratory restlessness and undirected summer restlessness seem to represent two separate phenomena. A possible adaptive significance of summer restlessness is discussed.This work was supported by National Science Foundation grant BMS-72-02198-AO2 to S.T. Emlen and by a Deutsche Forschungsgemeinschaft grant to W. Wiltschko. The Hochschulrechenzentrum of the Universität Frankfurt a.M. provided computer time. We thank S. Bergman for his valuable help in conducting the experiments and quantifying the footprint records of the funnel cages, and R.J. Young and the Department of Poultry Science, Cornell University, for the use of the brooder houses as experimental rooms.     

Volatile metabolites in sera of normal and diabetic patients

The profiles of volatile metabolites in serum samples from normal individuals and from individuals with diabetes mellitus with varying degrees of polyneuropathy have been studied. The transevaporator procedure was used to obtain sample extracts which were chromatographed on a highly efficient glass column coated with Silar 10C (106 m × 0.25 mm I.D.). Differences in profiles between normal subjects and diabetic subjects on no drug therapy were noticed. However, correlations between the severity of the neuropathy and the concentrations of certain ketones could not be established. Compounds present both in diabetic and normal sera have been identified by mass spectrometry.     

Die Orientierung von Zugv?geln: Magnetfeld und Himmelsfaktoren wirken zusammen

Ohne Zusammenfassung

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Migratory orientation: magnetic and celestial factors work together

     

Evaluation of ancestral inbreeding coefficients: Ballou’s formula versus gene dropping

Estimation of the purging of detrimental effects through inbreeding and selection is an important issue in conservation genetics opening new perspectives for the management of small populations. In 1997 Ballou proposed the ancestral inbreeding coefficient, which is calculated recursively via pedigree inbreeding coefficients, as a tool for evaluating the purging of deleterious alleles in zoo populations. The formula of Ballou assumes independence of inbreeding and ancestral inbreeding coefficients at any stage of the recursion. This study investigates the consequences of this inaccuracy on the estimation of true ancestral inbreeding, i.e. the proportion of alleles within a genome that has undergone inbreeding in the past. As an alternative we propose the estimation of ancestral inbreeding by the method of gene dropping. The methods are compared by stochastic simulation for various models with respect to mode of inheritance (neutral, detrimental and lethal alleles) and different settings for population size and initial allele frequencies. In all scenarios the proportion of alleles within a genome that has undergone inbreeding in the past was overestimated by Ballou’s formula. The overestimation was more pronounced in smaller populations but was not affected by genetic model or initial allele frequency. In contrast, the ancestral inbreeding coefficient calculated by gene dropping provided a robust estimate of ancestral inbreeding in most models and settings. A marginal overestimation was observed only in models with lethal alleles. Therefore, we recommend applying the gene dropping approach to estimate ancestral inbreeding coefficients.