Über den Einfluss der Regeneration und Überernährung auf die Siphonenlänge bei Ciona Intestinalis L.

Ohne ZusammenfassungIch muß hier meinen innigsten Dank folgenden Personen aussprechen, die mir bei meiner Arbeit Hilfe geleistet haben: meinem Mitarbeiter G. W.Lopaschov, der einen bedeutenden Teil der Messungen bearbeitet hat; dem Direktor der Murmanschen Biologischen Station Prof. G. A.Klüge, der mir liebenswurdig einen Arbeitsplatz gewährt hat; allen Mitwirkenden der Station für die meiner Arbeit erwiesene Aufmerksamkeit, den Herren Prof.Przibeam, Prof.Fox und ProfPérez für ihre von mir im Text zitierten wertvollen Briefe.     

A Desiccant-Holding Slide Box for Radioautographic Exposure

A double-depth plastic slide box is made by removing the bottoms of two standard 25-slide boxes and cementing the remaining frames together, bottom to bottom. A desiccant is placed in one box cover and fitted to the lower section of the cemented unit. A piece of screening is placed over the desiccant, the upper section filled with slides for radioautogaphy, and the empty cover applied to the top of the assembled box. Thus all slides are kept effectively and uniformly dehydrated during exposure.     

Correction de l'hypertension intracranienne créée par compression mécanique directe du cerveau

An attempt has been made to correct cerebral hypertension induced by direct compression of the brain in a group of six dogs. The animals, which had been previously fitted with an inflatable subdural rubber balloon, were either kept eupneic (isolated mechanical hypertension) or deliberately hypoventilated (mixed mechanical and acidotic hypertension). In the first instance, administration of urea brought the intracranial pressure back to control values while, in the second case, injection of an amine buffer controlled only the acidotic component of intracranial hypertension.     

Comparative Metabolism of Free‐living Bodo saltans and Parasitic Trypanosomatids

Comparison of the genomes of free‐living Bodo saltans and those of parasitic trypanosomatids reveals that the transition from a free‐living to a parasitic life style has resulted in the loss of approximately 50% of protein‐coding genes. Despite this dramatic reduction in genome size, B. saltans and trypanosomatids still share a significant number of common metabolic traits: glycosomes; a unique set of the pyrimidine biosynthetic pathway genes; an ATP‐PFK which is homologous to the bacterial PP_i‐PFKs rather than to the canonical eukaryotic ATP‐PFKs; an alternative oxidase; three phosphoglycerate kinases and two GAPDH isoenzymes; a pyruvate kinase regulated by fructose‐2,6‐bisphosphate; trypanothione as a substitute for glutathione; synthesis of fatty acids via a unique set of elongase enzymes; and a mitochondrial acetate:succinate coenzyme A transferase. B. saltans has lost the capacity to synthesize ubiquinone. Among genes that are present in B. saltans and lost in all trypanosomatids are those involved in the degradation of mureine, tryptophan and lysine. Novel acquisitions of trypanosomatids are components of pentose sugar metabolism, pteridine reductase and bromodomain‐factor proteins. In addition, only the subfamily Leishmaniinae has acquired a gene for catalase and the capacity to convert diaminopimelic acid to lysine.     

The role of loop F residues in determining differential d-tubocurarine potencies in mouse and human 5-hydroxytryptamine 3A receptors

The competitive antagonist d-tubocurarine (curare) has greater potency at mouse than at human 5-hydroxytryptamine 3A (5-HT3A) receptors, despite 84% amino acid sequence identity between the receptors. Within the ligand binding domain of this receptor are six loops (A-F). A previous report demonstrated that loop C of the 5-HT3A receptor contributed to differential potency between the receptors [Hope, A. G. et al. (1999) Mol. Pharmacol. 55, 1037-1043]. The present study tested the hypothesis that loop F plays a significant role in conferring interspecies curare potency differences. Wild-type, chimeric, and point mutant 5-HT3A receptors were expressed in Xenopus oocytes, and two-electrode voltage clamp electrophysiological recordings were performed. Our data suggest that loops C and F contribute to curare potency, given that the curare IC50's (concentration of drug that produces 50% inhibition of the response) for chimeric human receptors with substitutions of mouse residues in loop C (40.07 +/- 2.52 nM) or loop F (131.8 +/- 5.95 nM) were intermediate between those for the mouse (12.99 +/- 0.77 nM) and human (1817 +/- 92.36 nM) wild-type receptors. Two human point mutant receptors containing mouse receptor substitutions in loop F (H-K195E or H-V202I) had significantly lower curare IC50's than that of the human receptor. The human double mutant receptor, H-K195E,V202I, had the same curare IC50 (133.8 +/- 6.38 nM) as that of the human receptor containing all six loop F mouse substitutions. These results demonstrate that two loop F residues make a significant contribution in determining curare potency at the 5-HT3A receptor.