Cold-seep mollusks are older than the general marine mollusk fauna

The origin and possible antiquity of faunas at deep-sea hydrothermal vents and seeps have been debated since their discovery. We used the fossil record of seep mollusks to show that the living seep genera have significantly longer geologic ranges than the marine mollusks in general, but have ranges similar to those of deep-sea taxa, suggesting that seep faunas may be shaped by the factors that drive the evolution of life in the deep sea in general. Our data indicate that deep-sea anoxic/dysoxic events did not affect seep faunas, casting doubt on the suggested anoxic nature and/or global extent of these events.     

Hirschsprung disease is linked to defects in neural crest stem cell function

Genes associated with Hirschsprung disease, a failure to form enteric ganglia in the hindgut, were highly up-regulated in gut neural crest stem cells relative to whole-fetus RNA. One of these genes, the glial cell line-derived neurotrophic factor (GDNF) receptor Ret, was necessary for neural crest stem cell migration in the gut. GDNF promoted the migration of neural crest stem cells in culture but did not affect their survival or proliferation. Gene expression profiling, combined with reverse genetics and analyses of stem cell function, suggests that Hirschsprung disease is caused by defects in neural crest stem cell function.     

Zur Habitatbindung der Kriebelmücken (Simuliidae, Diptera) im pr?imaginalen Stadium

In dieser Arbeit werden insbesondere die für die Habitatselektion bzw. Habitatbindung präimaginaler Simuliidae wesentlichen Prozesse der Drift und Substratbesiedlung analysiert. Unter Berücksichtigung eigener Ergebnisse und des Schrifttums werden die Verhaltensweisen der Larven in den verschiedenen Phasen (Zudrift, Landung, Migration, Nahrungsaufnahme, Häutung, Kokonbau) dargestellt und die sie beeinflussenden Faktoren genannt. Hervorgehobene Widersprüche und Probleme sollen auf mögliche Neuansätze und Wege der weiterführenden Analyse hinweisen. Erkenntnisse für die Praxis, wie z. B. die Notwendigkeit der Trennung von primärer und sekundärer Dispersion, die bei der Erfassung von Dispersionen und Präferenzen zu berücksichtigen ist, werden erörtert. Mögliche Störgrößen, wie z.B. Migration, Sekretalterung oder Interferenz, werden als Abdrift auslösender Larven bzw. Adhäsion und andere Substrateigenschaften werden auf ihre Funktion als driftbeendende Faktoren überprüft.In this paper, we focus on habitat selection and preferences in simuliid larvae and stress their drift and substrate colonization as most important processes. Referring to our own results and to other studies we review information on larval behavior and factors influencing their activities, i.e. drift and locomotory behaviour or filterfeeding, molting and cocon-building. Some problems and inconsistent statements in literature are featured in order to point to further directions of investigation. Also, some of our results appearing important for applied limnology are mentioned. There is a need, for example, to distinguish between primary and secondary dispersion, especially when analyzing dispersion patterns or preferences. We discuss migration, silk-decay, interference etc. being factors likely to disturb the settling of larvae, thus causing them to drift off. Besides, it is argued whether special movements of drifting larvae as well as adhesion or other substrate features may help larvae to terminate drift.

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Frau Prof. Dr.H. Francke-Grosmann, Reinbek, zum Gedenken.     

SNARE proteins: one to fuse and three to keep the nascent fusion pore open

Neurotransmitters are released through nascent fusion pores, which ordinarily dilate after bilayer fusion, preventing consistent biochemical studies. We used lipid bilayer nanodiscs as fusion partners; their rigid protein framework prevents dilation and reveals properties of the fusion pore induced by SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor). We found that although only one SNARE per nanodisc is required for maximum rates of bilayer fusion, efficient release of content on the physiologically relevant time scale of synaptic transmission apparently requires three or more SNARE complexes (SNAREpins) and the native transmembrane domain of vesicle-associated membrane protein 2 (VAMP2). We suggest that several SNAREpins simultaneously zippering their SNARE transmembrane helices within the freshly fused bilayers provide a radial force that prevents the nascent pore from resealing during synchronous neurotransmitter release.     

Zur Habitatbindung der Kriebelmücken (Simuliidae,Diptera) im präimaginalen Stadium

Zusammenfassung In dieser Arbeit werden insbesondere die für die Habitatselektion bzw. Habitatbindung präimaginaler Simuliidae wesentlichen Prozesse der Drift und Substratbesiedlung analysiert. Unter Berücksichtigung eigener Ergebnisse und des Schrifttums werden die Verhaltensweisen der Larven in den verschiedenen Phasen (Zudrift, Landung, Migration, Nahrungsaufnahme, Häutung, Kokonbau) dargestellt und die sie beeinflussenden Faktoren genannt. Hervorgehobene Widersprüche und Probleme sollen auf mögliche Neuansätze und Wege der weiterführenden Analyse hinweisen. Erkenntnisse für die Praxis, wie z. B. die Notwendigkeit der Trennung von primärer und sekundärer Dispersion, die bei der Erfassung von Dispersionen und Präferenzen zu berücksichtigen ist, werden erörtert. Mögliche Störgrößen, wie z.B. Migration, Sekretalterung oder Interferenz, werden als Abdrift auslösender Larven bzw. Adhäsion und andere Substrateigenschaften werden auf ihre Funktion als driftbeendende Faktoren überprüft.

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On the habitat selection ofSimuliidae larvae

In this paper, we focus on habitat selection and preferences in simuliid larvae and stress their drift and substrate colonization as most important processes. Referring to our own results and to other studies we review information on larval behavior and factors influencing their activities, i.e. drift and locomotory behaviour or filterfeeding, molting and cocon-building. Some problems and inconsistent statements in literature are featured in order to point to further directions of investigation. Also, some of our results appearing important for applied limnology are mentioned. There is a need, for example, to distinguish between primary and secondary dispersion, especially when analyzing dispersion patterns or preferences. We discuss migration, silk-decay, interference etc. being factors likely to disturb the settling of larvae, thus causing them to drift off. Besides, it is argued whether special movements of drifting larvae as well as adhesion or other substrate features may help larvae to terminate drift.

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Frau Prof. Dr.H. Francke-Grosmann, Reinbek, zum Gedenken.     

Physiologic aging of mature porcine erythrocytes: effects of various metabolites, antimetabolites, and physical stressors

Red blood cells were collected from Landrace X Duroc pigs in pooled and single batches. The RBC were stored for 24 hours to 20 days and exposed to 1 or more chemical and physical stressors. The chemicals were pyruvate, lactate, inosine, concanavalin A-luminol-bovine serum albumin conjugate, hydrogen peroxide, L-mimosine, and 3-amino-L-tyrosine. Physical stressors included thermogenic microwave radiation (2,450 MHz, mean specific absorption rate of 91 W/kg) and conventional heating with hot air or hot-water bath. Heating erythrocytes to 43 C for 10 minutes with microwaves or hot air did not significantly (P greater than 0.05) increase hemolysis, compared with hemolysis of RBC at 4 C (controls). Pyruvate or lactate did not affect the RBC under these conditions. Hemolysis of cells coated with concanavalin A-luminol-bovine serum albumin and heated to 43 C for 10 minutes by use of microwaves or hot air was significantly (P less than 0.05 by Student's t test) greater (48%) than that of RBC at 4 C (controls). The method of heating or the presence of pyruvate, lactate, or inosine did not have a significant (P greater than 0.05) effect on hemolysis. Lysis of RBC (14 days after collection) coated with concanavalin A-luminol-bovine serum albumin and stored at 4 C was not significantly different (P greater than 0.05) than that of noncoated cells (6 days after collection) stored at 4 C (control). When RBC were heated 20 days after collection to 48 C for 30 minutes, using a hot water bath, hemolysis was 60.6% greater than that of control cells (4 C).(ABSTRACT TRUNCATED AT 250 WORDS)