Evidence for an adrenergic mechanism in the control of body asymmetry

The effect of phenylephrine, an alpha-1 adrenergic agonist, on development of body asymmetry was studied using a rat whole embryo culture system. Embryos were explanted at the presomite stage, cultured in 100% rat serum containing various concentrations of phenylephrine, and examined at the 20-25 somite stage for sidedness of asymmetric body structures, namely, bulboventricular loop, allantoic placenta, and tail. Phenylephrine treatment resulted in a dose-dependent increase of situs inversus with a maximum incidence of 52%. Coadministration of prazosin, an alpha-1 adrenergic antagonist, almost completely prevented this effect. Our results suggest that receptor-mediated stimulation of the alpha-1 adrenergic pathway is involved in the control of normal body asymmetry in developing rat embryos.     

韩国华津浦湖的鱼类区系

There are sevenlagoons onthe east coast of Korea,including Kyeongpo Lake,Hyang Lake,Mae Lake,Chung-cho Lake,Yeoungrang Lake,Songji Lake and HwajinpoLake.They are all originally natural and brackish waterlakes.Therefore,these lakes are not only historically veryimportant but also have high values for geological,andecological sciences.Natural lakes like lagoons are different from man-made lakes.That is,water level in natural lakes is almostconstant,cline by waterside is not much,and wet la…     

Role of C-terminal region of HA-33 component of botulinum toxin in hemagglutination.

Using SDS-PAGE, we found that one subcomponent, hemagglutinin (HA-33), from the Clostridium botulinum progenitor toxin of type D strain 1873 and type C strain Yoichi had slightly smaller molecular sizes than those of type C and D reference strains, but other components did not. Based on N- and C-terminal sequence analyses of HA-33, a deletion of 31 amino acid residues from the C-terminus at a specific site was observed in the HA-33 proteins of both strains. The progenitor toxins from both strains showed poor hemagglutination activities, titers of 2(1) or less, which were much lower than titers from the reference strains (2(6)), and did not bind to erythrocytes. These results suggest strongly that the short C-terminal region of the HA-33 plays an essential role in the hemagglutination activity of the botulinum progenitor toxin. Additionally, a sequence motif search predicted that the C-terminal region of HA-33 has a carbohydrate-recognition subdomain.     

Characterization of the rat adrenal medulla cultured in vitro

Summary A wide variety of experimental animal models have been used to investigate the mechanisms of synthesis, storage, and release of catecholamines. Whereas in vivo experimental models are situated at one end of the spectrum, cell culture models are situated at the other end. In the present study, we have characterized various aspects of the rat adrenal medulla cultured in vitro as a whole tissue, aiming to establish a new experimental model in between in vivo animal models and cell culture models. We adapted a bottle rotator system commonly used for culturing rodent whole embryos. Changes in histology, activities and mRNA levels of catecholamine-synthesizing enzymes, and concentrations of catecholamines in the adrenal medulla were studied. In addition, the effects of cholinergic stimulation on catecholamine release from the adrenal medulla were examined. Overall the results indicate that various aspects of the adrenal medulla become stable after 4 d of culture and the adrenal medulla at this stage releases catecholamines in response to cholinergic stimulation. The whole adrenal medulla culture system may be a useful tool for investigating catecholamine-related functions dependent on intercellular reactions or communications.     

The HA proteins of botulinum toxin disrupt intestinal epithelial intercellular junctions to increase toxin absorption

The type B botulinum neurotoxin (BoNT) elicits flaccid paralysis and death in humans by intoxicating peripheral nerves after oral absorption. Here, we examine the function of the haemagglutinin (HA), a non-toxic component of the large 16S BoNT complex. We find that the HA acts in the intestine to disrupt epithelial barrier function by opening intercellular tight and adherens junctions. This allows transport of BoNT and other large solutes into the systemic circulation and explains how the type B BoNT complexes are efficiently absorbed. In vitro , HA appears to act on the epithelial cell via the basolateral membrane only, suggesting the possibility of another step in the absorptive process. These studies show that the 16S BoNT complex is a multifunctional protein assembly equipped with the machinery to efficiently breach the intestinal barrier and act systemically on peripheral nerves.