Transport,verteilung und Metabolismus von3H-und14C-markiertem DDT in graviden mäusen unter hungerbelastung

Summary After i.p. application of 1, 0,5 and 0,1 mg p,p' DDT, labelled with³H or¹⁴C, to pregnant mice in different stages of pregnancy, the same level of radioactivity was found in the fetal and maternal blood. Starvation for 2 days caused a significant increase of residues, especially in the liver. Residue levels of DDT and its metabolities DDE, DDD, DCB and (DDOH+DDA) are found in fetal and maternal blood, brain liver and fat.     

The coagulation of insect hemolymph

In contrast to both vertebrates and non-insect arthropods, little is known about the coagulation of hemolymph (hemostasis) in insects. We discuss the integration of the hemostatic response with other branches of the insect immune system. We also describe the present stage in the characterization of both soluble and cellular factors that contribute to hemostasis in insects. The factors of the well-characterized clotting cascades of vertebrates, primitive chelicerates and crustaceans are used to assess the implications of sequencing the whole Drosophila genome for searching candidate genes involved in hemostasis. Some striking similarities between blood clotting in vertebrates and the reaction of insect cells involved in hemolymph coagulation have implications for a phylogenetic comparison of hemostasis between divergent animal classes.     

Transmitter-evoked local calcium release stabilizes developing dendrites

In the central nervous system, dendritic arborizations of neurons undergo dynamic structural remodelling during development. Processes are elaborated, maintained or eliminated to attain the adult pattern of synaptic connections. Although neuronal activity influences this remodelling, it is not known how activity exerts its effects. Here we show that neurotransmission-evoked calcium (Ca(2+)) release from intracellular stores stabilizes dendrites during the period of synapse formation. Using a ballistic labelling method to load cells with Ca(2+) indicator dyes, we simultaneously monitored dendritic activity and structure in the intact retina. Two distinct patterns of spontaneous Ca(2+) increases occurred in developing retinal ganglion cells--global increases throughout the arborization, and local 'flashes' of activity restricted to small dendritic segments. Blockade of local, but not global, activity caused rapid retraction of dendrites. This retraction was prevented locally by focal uncaging of caged Ca(2+) that triggered Ca(2+) release from internal stores. Thus, local Ca(2+) release is a mechanism by which afferent activity can selectively and differentially regulate dendritic structure across the developing arborization.     

Insertional mutagenesis in zebrafish rapidly identifies genes essential for early vertebrate development

To rapidly identify genes required for early vertebrate development, we are carrying out a large-scale, insertional mutagenesis screen in zebrafish, using mouse retroviral vectors as the mutagen. We will obtain mutations in 450 to 500 different genes--roughly 20% of the genes that can be mutated to produce a visible embryonic phenotype in this species--and will clone the majority of the mutated alleles. So far, we have isolated more than 500 insertional mutants. Here we describe the first 75 insertional mutants for which the disrupted genes have been identified. In agreement with chemical mutagenesis screens, approximately one-third of the mutants have developmental defects that affect primarily one or a small number of organs, body shape or swimming behavior; the rest of the mutants show more widespread or pleiotropic abnormalities. Many of the genes we identified have not been previously assigned a biological role in vivo. Roughly 20% of the mutants result from lesions in genes for which the biochemical and cellular function of the proteins they encode cannot be deduced with confidence, if at all, from their predicted amino-acid sequences. All of the genes have either orthologs or clearly related genes in human. These results provide an unbiased view of the genetic construction kit for a vertebrate embryo, reveal the diversity of genes required for vertebrate development and suggest that hundreds of genes of unknown biochemical function essential for vertebrate development have yet to be identified.     

Fisheries. Population of origin of Atlantic cod

Most of the world's cod (Gadus morhua) fisheries are now tightly regulated or closed altogether. Being able to link individual fish to their population of origin would assist enormously in policing regulations and in identifying poachers. Here we show that microsatellite genetic markers can be used to assign individual cod from three different populations in the northeastern Atlantic Ocean to their population of origin.