Pool sizes of metabolic intermediates and their relation to glucose repression of β-galactosidase synthesis in Escherichia coli

1. The intermediary metabolism of two strains of Escherichia coli has been examined. One strain (Q22) exhibits acute transient repression of β-galactosidase synthesis when glucose is supplied to cells growing on glycerol; the other strain (W3110) does not. The two strains do not differ genetically in their lac operons. 2. Strain Q22 uses about twice as much glucose as strain W3110 per unit of cell mass produced. 3. Pentose phosphate-cycle activity in the presence of glucose is much stronger in strain Q22 than in strain W3110. 4. In strain Q22 the pool sizes of glucose 6-phosphate, 6-phosphogluconate, fructose 1,6-diphosphate and NADPH increase when glucose is added to cells growing on glycerol, and β-galactosidase synthesis is severely inhibited. After about 1hr. the synthesis of β-galactosidase is partly resumed, and the pool sizes of the four compounds fall. ATP, NADH and several other phosphorylated compounds show no concentration changes. 5. These concentration changes do not occur in strain W3110, in which β-galactosidase synthesis is only rather weakly repressed by glucose. 6. It is suggested that repression of enzyme synthesis by glucose requires the rapid operation of the pentose phosphate cycle, and is mediated by one of the four substances whose concentration rises and later falls in strain Q22. A definite choice of effector from among these four possibilities cannot at present be made.     

Action of phyenethyl alcohol on the synthesis of macromolecules in Escherichia coli

Prevost, C. (University of California, Berkeley), and V. Moses. Action of phenethyl alcohol on the synthesis of macromolecules in Escherichia coli. J. Bacteriol. 91:1446-1452. 1966.-A kinetic study of the effects of various concentrations of phenethyl alcohol on the synthesis of ribonucleic acid (RNA), deoxyribonucleic acid (DNA), protein, and beta-galactosidase in Escherichia coli has confirmed that RNA synthesis, rather than DNA synthesis, is first and most affected by phenethyl alcohol. The presence of inducer did not protect beta-galactosidase synthesis from inhibition by phenethyl alcohol. Little preferential inhibition of beta-galactosidase synthesis was observed; this is in contrast to the severe catabolite repression which results from partial inhibition of total protein synthesis caused by chloramphenicol or starvation for a required amino acid. We found no evidence that messenger RNA synthesis was inhibited to a greater extent than total RNA synthesis.     

Screening of staphylococci for the toxic shock syndrome toxin-1 (TSST-1) gene

Dot blot hybridization was used to screen 820 staphylococci for the presence of the gene coding for TSST-1. The DNA of 33 strains among 70 Staph. aureus strains isolated from suspected toxic shock syndrome (TSS) cases hybridized with the probe. These results agreed perfectly with those obtained with a phenotypic method (immunodiffusion). Among 608 Staph. aureus strains isolated over a period of one month from hospitalized patients, 66 (11%) hybridized with the probe; of these strains, 64 (97%) were found to produce TSST-1 in vitro. None of 145 coagulase-negative staphylococcal strains harboured DNA hybridizing with the probe. The data indicate that this genotypic assay is suitable for epidemiological studies.     

Morphology ofEntomophthora muscae protoplasts grownin vitro

Summary Entomophthora muscae (C.) Fres. can be grownin vitro as protoplasts. Light and electron microscopical studies of thein vitro developed protoplasts have demonstrated the absence of an organized wall over the protoplasmic Con A-positive membrane at all stages of growth. The cytological organization is typical of the Entomophthorales with condensed chromatin in the interphase nuclei and small eccentric metaphase spindles. Long strands of endoplasmic reticulum, microubules and vesicles surrounding the plasmalemma may be involved in maintaining the precise shape ofE. muscae protoplast. Starvation of the fungus induces the formation of hyphal bodies after deposition of Con A- and WGA-positive wall material at the plasmalemma surface.Abbreviations Con A concanavalin A - DH Drosophila cell culture medium - FITC fluorescein isothiocyanate - GLEN glucose-lactal-bumin-yeast extract-NaCl culture medium for protoplasts - HBL hyphal body-like protoplasts - MM Mitsuhashi and Maramorosch' insect cell culture medium - PATAg periodic acid-thiocarbohydrazide-silver proteinate technique - PBN phosphate buffer with NaCl - S spherical protoplasts - WGA wheat germ agglutinin     

Heritable differences in the response of the braconid waspMicroplitis croceipes to volatile allelochemicals

The heritable nature of differential responses by Microplitis croceipes(Cresson) (Hymenoptera: Braconidae) to airborne allelochemicals was investigated. Four isofemale lines were tested for three generations in a flight tunnel. Flight response was found to be strongly dependent on the familial origin, with two highly responsive lines being clearly differentiated from two less responsive ones. Each isofemale line could also be recognized by typical behaviors that suggested that M. croceipesfemales may inherit independent characters of sensory acuity to plant and to host chemicals and of learning ability.     

Strain identification inRhizobium meliloti using the antibiotic disk susceptibility test

Summary The antibiotic disk susceptibility test was used to measure the variation in the intrinsic resistance of 49 strains ofRhizobium meliloti to 9 antibiotics. Several strains had unique patterns of resistance. However, during cluster analysis, when a minimum Euclidean distance equal to 4 was used as a discriminating tool, the strains were grouped in 12 groups. The largest group contained 74% of the strains but 9 strains (2 very effective, 4 effective and 3 ineffective) showed very unique patterns of resistance and formed 9 distinct groups.R. meliloti strains in general showed high intrinsic resistance to the 9 antibiotics tested.Contribution no. 189 Station de Recherches, Agriculture Canada.     

Raising the level: orangutans use water as a tool

We investigated the use of water as a tool by presenting five orangutans (Pongo abelii) with an out-of-reach peanut floating inside a vertical transparent tube. All orangutans collected water from a drinker and spat it inside the tube to get access to the peanut. Subjects required an average of three mouthfuls of water to get the peanut. This solution occurred in the first trial and all subjects continued using this successful strategy in subsequent trials. The latency to retrieve the reward drastically decreased after the first trial. Moreover, the latency between mouthfuls also decreased dramatically from the first mouthful in the first trial to any subsequent ones in the same trial or subsequent trials. Additional control conditions suggested that this response was not due to the mere presence of the tube, to the existence of water inside, or frustration at not getting the reward. The sudden acquisition of the behaviour, the timing of the actions and the differences with the control conditions make this behaviour a likely candidate for insightful problem solving.     

Tracing geographical patterns of population differentiation in a widespread mangrove gastropod: genetic and geometric morphometrics surveys along the eastern African coast

In the present study, we assessed the inter‐ and intrapopulation genetic and morphological variation of Cerithidea decollata along the eastern coast of Africa. The population structure of C. decollata along the latitudinal gradient was examined by sequencing 420 bp of the mitochondrial cytochrome c oxidase I (COI) gene in 172 snails from 29 sites, in a combined analysis with geometric morphometrics in 1799 snails from 32 sites. Analysis of molecular variance and spatial analysis of molecular variance showed a moderate spatial population differentiation from Kenya to the Republic of South Africa, suggesting genetic divergence between the northern, central, and southern regions. This structure appears to be the result of life‐history traits combined with oceanographic features. Haplotype network and mismatch analysis suggest a recent population expansion during the Holsteinian interglacial period in the northern region and several colonization events in the central and southern regions. The morphometric approach suggests that morphological variation in shell shape is somewhat independent of the genetic divergence, revealing an overlap of shape across the latitudinal gradient but significant differences among‐population at a local level. This may indicate that similar ecological pressures are acting along the coast, leading to the occurrence of similar morphological characters. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 107 , 647–663.