Aminoacylase I from porcine kidney: Identification and characterization of two major protein domains

The domain structure of hog-kidney aminoacylase I was studied by limited proteolytic digestion with trypsin and characterization of the resulting fragments. In the native enzyme, the sequences from residue 6 to 196 and 307 to 406 are resistant to trypsin and remain tightly bound in nondenaturing solvents, while the intervening sequence (197–306) is efficiently degraded by trypsin. We conclude that the N-terminal half of the molecule and its C-terminal fourth form two independently folded domains. Both contain a peculiar PWW(A,L) sequence motif preceded by several strongly polar residues. We propose that these sequences form surface loops that mediate the membrane association of aminoacy clase I. We further show that the three free cysteine residues and the essential Zn²⁺ ion reside in the trypsin-resistant domains, while the intervening sequence contains the only disulfide H bond of the protein.     

Ecological and Behavioral Aspects of Nest Building in Wild Bonobos (Pan paniscus)

Data on nest building behavior were collected from free ranging bonobos (Pan paniscus). Considering the physical features of both nests and trees used for nest construction, bonobos appeared to show various preferences: (1) Trees with small leaves were chosen more frequently than expected; (2) The majority of nests were constructed in trees of the middle forest layer (15 to 30 m) and at a mean height of 16 m; (3) nests built during the day were located higher than night nests and differed in the general mode of construction (number of trees involved). Comparing nests made by mature males and females it became apparent that females (4) built nests higher, (5) constructed day nests more frequently and (6) used them for a longer time than males. Comparison of data collected at different study sites indicates site-specific differences concerning selection of trees and location of nesting sites. Behavioral observations made clear that nests were not only used for rest but also for other activities like feeding, social grooming and play. Moreover, the study provided the first evidence that bonobos build nests also in order to avoid potential or imminent conflicts with other party members. Field observations indicate that these nests symbolize a taboo zone and show another facet of the social abilities of bonobos for the solution of intra group conflicts. It is suggested that this behavior derives from the spatial intolerance shown by females during the process of weaning.     

Chauvinism in science

Is Science chauvinistic? It is not, but scientists often are. How does chauvinism in Science manifest itself? Could it be that we are genetically programmed to reject those we see as “foreign”?     

C4-dicarboxylates and l-aspartate utilization by Escherichia coli K-12 in the mouse intestine: l-aspartate as a major substrate for fumarate respiration and as a nitrogen source

C4-dicarboxylates, such as fumarate, l -malate and l -aspartate represent substrates for anaerobic growth of Escherichia coli by fumarate respiration. Here, we determined whether C4-dicarboxylate metabolism, as well as fumarate respiration, contribute to colonization of the mammalian intestinal tract. Metabolite profiling revealed that the murine small intestine contained high and low levels of l -aspartate and l -malate respectively, whereas fumarate was nearly absent. Under laboratory conditions, addition of C4-dicarboxylate at concentrations corresponding to the levels of the C4-dicarboxylates in the small intestine (2.6 mmol kg⁻¹ dry weight) induced the dcuBp-lacZ reporter gene (67% of maximal) in a DcuS-DcuR-dependent manner. In addition to its role as a precursor for fumarate respiration, l -aspartate was able to supply all the nitrogen required for anaerobically growing E. coli. DcuS-DcuR-dependent genes were transcribed in the murine intestine, and mutants with defective anaerobic C4-dicarboxylate metabolism (dcuSR, frdA, dcuB, dcuA and aspA genes) were impaired for colonizing the murine gut. We conclude that l -aspartate plays an important role in providing fumarate for fumarate respiration and supplying nitrogen for E. coli in the mouse intestine.     

Über den Flavonoidstoffwechsel während der Samenkeimung

Es wurde das Flavonoidmuster ruhender Samen und 8 bis 10 Tage alter Keimlinge von 18 Pflanzenarten unterschiedlicher taxonomischer Einheiten verglichen. Als allgemeines Ergebnis kann festgestellt werden: In den meisten Samen und in allen Keimlingen liegen neben Zimtsäuren (und Derivaten) Flavonoide, hauptsächlich Quercetin- und Kämpferolglykoside, in unterschiedlicher Anzahl und Menge vor. Das “Ruhemuster” unterscheidet sich allgemein von der Pigmentausstattung junger Keimlinge. Drei typische Gruppen von Pflanzen wurden gefunden, deren Pigmentgehalt und -muster während der Samenkeimung charakteristisch verändert wird.     

Pupariation in flies: A tool for monitoring effects of drugs,venoms, and other neurotoxic compounds

A complex Sarcophaga bullata pupariation assay was used to evaluate the neurotropic effects of several drugs, venoms, and insecticides. The assay consists of tests for (1) immediate effects on the intact larva, (2) effects on ligated (ie, isolated from the central nervous system) larval abdomens, (3) morphogenetic effects on the puparium, and (4) effects on stereotyped pupariation behavior. The latter are monitored barographically by recording changes in hemocoelic pressure. Of 62 compounds screened, 18 showed morphogenetic activity at a threshold dose of 5 μg or less, 11 at a dose of 50 μg, four at a dose of 100 μg, and 29 showed no morphogenetic activity. From a comparison of the putative pharmacological actions of the tested compounds with their morphogenetic effects, certain generalizations can be made: Agents that paralyze neuromuscular systems at the peripheral level (eg, tetrodotoxin), or suppress or modify basic motor patterns centrally (eg, veratrine sulphate), cause retention of larval morphological characters in the puparium. Compounds that stimulate convulsive contractions of segmental musculature (mostly cholinergic drugs like eserine sulphate, nicotine, organophosphate insecticides) cause retention of larval segmentation on longitudinally contracted puparia. Five compounds (venom of the scorpion, Leirus quinquestriatus, pyrethrins, protoveratrine A, and kainic and quisqualic acids) stimulate musculature of the denervated abdomen. Barographic monitoring of changes in pupariation behavior appears to be a most sensitive and informative test. It reveals great differences in the ways in which compounds producing seemingly identical morphogenetic effects affect and modify behavior, thus making pharmacological classification more accurate.     

Zur Brutbiologie des Kleinen Sumpfhuhns,Porzana parva

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