Kurze Mitteilungen

Zusammenfassung Ein Paar Türkentauben brütete vom 29. 1. bis 15. 2. 1966 auf einem Straßenbaum in Berlin-Tempelhof. Es wurde nur ein Ei gelegt. Nach 17 Tagen schlüpfte das gelbbedaunte Junge. Es ist dann kurz danach, wahrscheinlich beim Umherkriechen auf dem Nestrand, erfroren. Die Umstände, unter denen die Brut erfolgte, waren äußerst ungünstig. Die Temperatur lag seit dem 7. 2. 1966 dauernd unter Null (–9 und –13 Grad). Die brütende Taube hatte von Anfang an auf dem Nestrand brüten müssen, da die Mulde schon vor der Eiablage völlig mit Schnee bedeckt war. Der brütende Vogel war mehrere Tage und Nächte von einem hohen Schneewall umgeben, der sich auf dem Nest gebildet hatte. Dieses Nest wurde von Mai 1964 an viermal von einem Türkentaubenpaar zum Brüten benutzt. Es wird vermutet, daß zum mindesten der eine Partner, der Tauber, während der ganzen Zeit derselbe geblieben ist.     

The lepidopteran mitochondrial control region: structure and evolution

For several species of lepidoptera, most of the approximately 350-bp mitochondrial control-region sequences were determined. Six of these species are in one genus, Jalmenus; are closely related; and are believed to have undergone recent rapid speciation. Recent speciation was supported by the observation of low interspecific sequence divergence. Thus, no useful phylogeny could be constructed for the genus. Despite a surprising conservation of control-region length, there was little conservation of primary sequences either among the three lepidopteran genera or between lepidoptera and Drosophila. Analysis of secondary structure indicated only one possible feature in common--inferred stem loops with higher-than-random folding energies-- although the positions of the structures in different species were unrelated to regions of primary sequence similarity. We suggest that the conserved, short length of control regions is related to the observed lack of heteroplasmy in lepidopteran mitochondrial genomes. In addition, determination of flanking sequences for one Jalmenus species indicated (i) only weak support for the available model of insect 12S rRNA structure and (ii) that tRNA translocation is a frequent event in the evolution of insect mitochondrial genomes.      

Einiges vom Verhalten der Nebelkr?he(Corvus corone cornix)

Zusammenfassung Ein Strandwald bei Danzig diente im Winter Zehntausenden von Nebelkrähen als Schlafplatz. Jeden Morgen flogen die Krähen nach allen Richtungen zu ihren Nahrungsplätzen, die zum Teil 50 und mehr Kilometer entfernt waren. Es wird ein Fall geschildert, aus dem hervorgeht, wodurch die Entdeckung einer besonders ergiebigen Nahrungsquelle den Artgenossen in weitem Umkreis bekannt wird.Das Raubvogel-Schema der Krähen ist sehr weit und schließt nur den Seeadler aus, der (wenigstens im Winter) von ihnen nicht angegriffen, sondern als Nahrungsspender betrachtet wird. Besonders heftig reagieren sie auf den Habicht. 150–200 Nebelkrähen belagerten einen Habicht, der vor ihnen in ein Kiefernstangenholz geflüchtet war. Der Baummarder löst bei Nebelkrähen dieselbe starke Reaktion aus wie der Habicht. Kolkraben scheinen im Winter von Krähen nicht angegriffen zu werden.     

Glutamine repeats and inherited neurodegenerative diseases: molecular aspects

Several dominantly inherited, late onset, neurodegenerative diseases are due to expansion of CAG repeats, leading to expansion of glutamine repeats in the affected proteins. These proteins are of very different sizes and, with one exception, show no sequence homology to known proteins or to each other; their functions are unknown. In some, the glutamine repeat starts near the N-terminus, in another near the middle and in another near the C-terminus, but regardless of these differences, no disease has been observed in individuals with fewer than 37 repeats, and absence of disease has never been found in those with more than 41 repeats. Protein constructs with more than 41 repeats are toxic to E. coli and to CHO cells in culture, and they elicit ataxia in transgenic mice. These observations argue in favour of a distinct change of structure associated with elongation beyond 37–41 glutamine repeats. The review describes experiments designed to find out what these structures might be and how they could influence the properties of the proteins of which they form part. Poly- -glutamines form pleated sheets of β-strands held together by hydrogen bonds between their amides. Incorporation of glutamine repeats into a small protein of known structure made it associate irreversibly into oligomers. That association took place during the folding of the protein molecules and led to their becoming firmly interlocked by either strand- or domain-swapping. Thermodynamic considerations suggest that elongation of glutamine repeats beyond a certain length may lead to a phase change from random coils to hydrogen-bonded hairpins. Possible mechanisms of expansion of CAG repeats are discussed in the light of looped DNA model structures.     

The mating-type locus B alpha 1 of Schizophyllum commune contains a pheromone receptor gene and putative pheromone genes.

Analysis of the multispecific B alpha mating-type locus of Schizophyllum commune provided evidence that pheromones and pheromone receptors govern recognition of self versus non-self and sexual development in this homobasidiomycetous fungus. Four subclones of an 8.2 kb genomic fragment carrying B alpha 1 specificity induced B-regulated sexual morphogenesis when introduced into a strain with one of the eight compatible B alpha specificities that are known to exist in nature. One of these clones, which activated all other B alpha specificities, contains a gene termed bar1. The predicted protein product of bar1, as well as that of bar2, a homologous gene isolated from a B alpha 2 strain, has significant homology to known fungal pheromone receptor proteins in the rhodopsin-like superfamily of G protein-linked receptors. The other three active B alpha 1 clones were subcloned further to identify the minimal active element in each clone. Every active subclone contains a putative pheromone gene ending in a signal for possible isoprenylation. A message of approximately 600 bp was observed for one of these genes, bap1(1). This paper presents the first evidence for a system of multiple pheromones and pheromone receptors as a basis for multispecific mating types in a fungus.     

Differential expression of the p65 gene family

The genome of the marine ray Discopyge ommata contains at least three p65-related genes. o-p65-A is 84% identical, o-p65-B is 78% identical, and o-p65-C is only 41% identical to a previously characterized rat p65. The cytoplasmic domain, particularly the two regions that are similar to the regulatory domain of protein kinase C, are most highly conserved. The three genes are expressed in different but overlapping patterns in the central nervous system. o-p65-A immunoreactivity is found predominantly in forebrain, cerebellum, and neuroendocrine cells, while o-p65-B immunoreactivity is predominantly localized to the spinal cord, brainstem, and midbrain. Many synaptic vesicle proteins are members of small gene families that are differentially expressed, resulting in several unique combinations of these molecules in specific brain regions.     

Development of cell surface saccharides on embryonic pancreatic cells

Using a battery of seven lectin-ferritin conjugates as probes for cell surface glycoconjugates, we have studied the pattern of plasmalemmal differentiation of cells in the embryonic rat pancreas from day 15 in utero to the early postpartum stage. Our results indicate that differentiation of plasmalemmal glycoconjugates on acinar, endocrine, and centroacinar cells is temporally correlated with development and is unique for each cell type, as indicated by lectin-ferritin binding. Specifically, (a) expression of adult cell surface saccharide phenotype can be detected on presumptive acinar cells as early as 15 d in utero, as indicated by soybean agglutinin binding, and precedes development of intracellular organelles characteristic of mature acinar cells; (b) maturation of the plasmalemma of acinar cells is reached after intracellular cytodifferentiation is completed, as indicated by appearance of Con A and fucoselectin binding sites only at day 19 of development; conversely, maturation of the endocrine cell plasmalemma is accompanied by "loss" (masking) of ricinus communis II agglutinin receptors; and (c) binding sites for fucose lectins and for soybean agglutinin are absent on endocrine and centroacinar cells at all stages examined. We conclude that acinar, centroacinar, and endocrine cells develop from a common progenitor cell(s) whose plasmalemmal carbohydrate composition resembles most closely that of the adult centroacinar cell. Finally, appearance of acinar lumina beginning at approximately 17 d in utero is accompanied by differenetiation of apical and basolateral plasmalemmal domains of epithelial cells, as indicated by enhanced binding of several lectin-ferritin conjugates to the apical plasmalemmal, a pattern that persists from this stage through adult life.     

EH proteins

Endocytosis is a protein and lipid-trafficking pathway that occurs in all eukaryotic cells. It involves the internalization of plasma membrane proteins and lipids into the cell and the subsequent degradation of proteins in the lysosome or the recycling of proteins and lipids back to the plasma membrane. Over the past decade, studies in yeast and mammalian cells have revealed endocytosis to be a very complex molecular process that depends on regulated interactions between a variety of proteins and lipids. The Eps15 homology (EH) domain is a conserved, modular protein-interaction domain found in several endocytosis proteins. EH proteins can function as key regulators of endocytosis through their ability to interact with many of the other proteins involved in this process.