Zur Wirkungsweise des white-Allels bei Drosophila melanogaster

Zusammenfassung In den pigmentfreien Augen derwhite-Mutante vonDrosophila melanogaster wurden die gleichen Trägergranula histologisch nachgewiesen, in die die Augenpigmente (Pterine und Ommochrome) bei der Wildform eingelagert sind. In Zusammensetzung (Protein, Ribonucleinsäure, Lipoidphosphat) und biochemischer Funktion (hohe Aktivität der Enzyme der biologischen Oxydation) ähneln sie Mitochondrien. Die Granula der Mutante unterscheiden sich von denen der Wildform darin, daß in ihnen die Succinodehydrase locker, die Protyrosinase dagegen fester gebunden ist, wie Enzymteste in Medien verschiedenen osmotischen Druckes ergaben. diese Unterschiede in den Enzymaktivitäten können eine weitere phänotypische Auswirkung deswhite-Allels sein; auf einen ursächlichen Zusammenhang dieser Ergebnisse mit der fehlenden Fähigkeit, die Endstufen der Augenpigmente zu synthetisieren, wird hingewiesen.

---

---

Mit 5 Textabbildungen     

Effects of Chronic D-Serine Elevation on Animal Models of Depression and Anxiety-Related Behavior

NMDA receptors are activated after binding of the agonist glutamate to the NR2 subunit along with a co-agonist, either L-glycine or D-serine, to the NR1 subunit. There is substantial evidence to suggest that D-serine is the most relevant co-agonist in forebrain regions and that alterations in D-serine levels contribute to psychiatric disorders. D-serine is produced through isomerization of L-serine by serine racemase (Srr), either in neurons or in astrocytes. It is released by astrocytes by an activity-dependent mechanism involving secretory vesicles. In the present study we generated transgenic mice (SrrTg) expressing serine racemase under a human GFAP promoter. These mice were biochemically and behaviorally analyzed using paradigms of anxiety, depression and cognition. Furthermore, we investigated the behavioral effects of long-term administration of D-serine added to the drinking water. Elevated brain D-serine levels in SrrTg mice resulted in specific behavioral phenotypes in the forced swim, novelty suppression of feeding and olfactory bulbectomy paradigms that are indicative of a reduced proneness towards depression-related behavior. Chronic dietary D-serine supplement mimics the depression-related behavioral phenotype observed in SrrTg mice. Our results suggest that D-serine supplementation may improve mood disorders.     

The genomic history of the Aegean palatial civilizations

1. Download : Download high-res image (181KB)
2. Download : Download full-size image

     

Somatic embryogenesis in cell cultures of Thapsia garganica

Cell cultures from different species of the genus Thapsia (Apiaceae) have been investigated. In one 4-yearold line of T. garganica L. spontaneous somatic embryogenesis up to the globular stage occurred in a suspension culture containing 1 mg l^–12,4-dichlorophenoxyacetic acid (2,4-D). Also callus cultures of this line, previously maintained on a medium containing 1 mg l^–1 2,4-D, when transferred to various media deprived of 2,4-D, produced somatic embryos that developed into plantlets. Cell culture, embryos and regenerated organs were analysed for their content of thapsigargins. The undifferentiated cell culture did not synthezise thapsigargins, but was found to produce a yet unidentified compound not present in planta. White embryos in the pre-cotyledonary stage did not synthezise thapsigargins either, but when the embryos developed to the cotyledonary stage and became green, the synthesis started. Regenerated roots and shoots also contained thapsigargins.Abbreviations BAP Benzylaminopurine - 2,4-D 2,4-Dichlorophenoxyacetic acid - EtOAc ethyl acetate - FDA fluorescein diacetate - IAA Indole-3-acetic acid - IBA indole-3-butyric acid - 2-iP 2-isopentenyladenine - NAA 1-Napthaleneacetic acid     

Development of cell surface polarity in the epithelial Madin-Darby canine kidney (MDCK) cell line.

The development of surface polarity has been studied in the epithelial Madin-Darby canine kidney (MDCK) cell line by examining two basolateral markers: a monoclonal antibody against a 58-kd protein and [35S]methionine uptake. The surface distribution of these markers was followed after plating the cells on coverslips or nitrocellulose filters. In subconfluent monolayers the apical surface of many cells was stained with the anti-58-kd antibody. Clearing of the apical surface occurred first after confluency had been reached in cells grown on coverslips. Similarly, in cells grown on filters the basolateral 58-kd protein disappeared from the apical surface concomitantly with the development of a measurable electrical resistance over the cell monolayer. The uptake of [35S]methionine was measured from both sides of filter-grown cells and began to polarize early after seeding, reaching a value of greater than 98% basolateral in the fully polarized monolayer. These results emphasize that the development of surface polarity in MDCK cells is a gradual process, and that extensive cell-cell contacts seem to be required for complete surface polarization.