Effects of sub-minimal inhibitory concentrations of EDTA on growth of Escherichia coli and the release of lipopolysaccharide

Abstract Release of lipopolysaccharide from E. coli was studied in the presence of sub-minimal inhibitory concentrations of ethylenediaminetetraacetic acid (EDTA). In untreated cells no release was detected with 50 mM Mg²⁺ in the medium, but a steady release of over 50% of the synthesized lipopolysaccharide was observed with 0.1 mM Mg²⁺. EDTA at MIC/8 led to a 2- to 3-fold higher release, presumably by an adjustment of the concentration of unchelated Mg²⁺ to a value still sustaining normal growth but giving rise to a highly unstable outer membrane. No structural difference was observed between cell-bound and released lipopolysaccharide.     

Micropropagation of Cowania subintegra and Cowania stansburiana

Both Cowania subintegra Kearney and C. stansburiana Torr. were successfully propagated in vitro. Shoot proliferation occurred from shoot tips of green-house grown C. subintegra using a modified Murashige and Skoog medium supplemented with 4.4 M 6-benzyladenine and 0.5 M indole butyric acid. Excised microshoots (1.5–3.0 cm long) of both species were rooted using a two-step process in which they were cultured for 3 days in a root initiation medium with 2.7 M naphthaleneacetic acid and then transferred to a low nitrogen root elongation medium without auxin. Plantlets were successfully transferred to soilless potting mix.     

Plasma and liver selenium levels in the rat during supplementation with 0.5, 2, 6, and 15 ppm selenium in drinking water

Plasma and liver selenium of Wistar rats were determined after 1, 3, and 6 mo supplementation with 0.5, 2, 6, or 15 ppm selenium as sodium selenite in drinking water. Plasma selenium was not different from control values at additional intake of 0.5 ppm but increased above usual levels at higher intakes. A highly significant correlation was observed between the total quantity of selenium ingested and plasma selenium after 1 mo treatment (r=0.99,p<0.01), but was less pronounced after 3 and 6 mo (0.94,p<0.05, and 0.78,p<0.05, respectively). The decrease in plasma selenium with time of treatment was more pronounced at higher intakes. There was also a highly significant correlation between total selenium intake and liver selenium concentration (r=0.99,p<0.01) after 1 mo of treatment, but this time liver selenium did not change with time, and the correlation remained highly significant throughout the investigation. Liver selenium therefore appears as a more sensitive and more representative measure of selenium intake than plasma selenium. Most supplements did not affect body weight and survival of animals, except when the diet was supplemented with 15 ppm for 6 mo; however, alterations in biochemical parameters concerning lipid status and hepatic function were observed at levels above 2.0 ppm.     

Rank relations among sisters in semi-free-ranging Barbary macaques (Macaca sylvanus)

Although semi-free-ranging Barbary macaque females are able to outrank older females from lower-ranking matrilines (matrilineal rank acquisition), they do not systematically outrank their older sisters, as is known to be the case for semi-free-ranging rhesus monkeys (Macaca mulatta) and Japanese macaques (Macaca fuscata). We test the hypothesis that differences in the support received by younger sisters against their older sisters and against older lower-ranking females might account for this interspecific difference. Thirty-one sister dyads, members of a group of 109 Barbary macaques living at La Montagne des Singes, France, were observed during 16 months. The results indicate that (1) all females were dominant to their younger sisters, and the latter were never observed to challenge their older sisters; (2) younger sisters received as much kin support against their older sisters as against older lower-ranking females; (3) only very young females received support from their kin against their older sisters; (4) younger sisters received much more support from nonkin females against lower-ranking females than against their older sisters; and (5) Barbary macaque females appear to be supported against their older sisters less frequently than rhesus macaque females are. We conclude that the lack of nonkin support is the main factor accounting for the failure of younger sisters to outrank their older sisters in Barbary macaques. Initially this might result from kin support not being sufficient to induce younger sisters to challenge and to solicit support against their older sisters.     

Development and validation of a high-performance liquid chromatographic method for the determination of methocarbamol in human plasma

An isocratic HPLC method was developed and validated for the quantitation of methocarbamol in human plasma. Methocarbamol and internal standard in 200 μl of human plasma were extracted with ethyl acetate, evaporated to dryness and reconstituted in water. Separation was achieved on a reversed-phase C₁₈ column with a mobile phase of methanol—0.1 M potassium phosphate monobasic—water (35:10:55, v/v/v). The detection was by ultraviolet at 272 nm. Linearity was established at 1–100 μg/ml (r > 0.999). The limit of quantitation was designed as 1 μg/ml to suit pharmacokinetic studies. Inter-day precision and accuracy of the calibration standards were 1.0 to 3.6% coefficients of variance (C.V.) and −2.0 to +1.6% relative error (R.E.). Quality controls of 3, 20 and 70 μg/ml showed inter-day precision and accuracy of 2.5 to 3.6% C.V. and −0.9 to −0.4% R.E. Recovery of methocarbamol was 91.4–100.3% in five different lots of plasma. The method was shown to be applicable on different brands of C₁₈ columns.     

Renal eicosanoids and blood pressure in genetically hypertensive rats of the lyon strain

The present paper reviews the evidence for a possible involvement of renal eicosanoids in the pathophysiology of high blood pressure in genetically hypertensive rats of the Lyon strain. Both in vivo and in vitro experiments suggest that an increased ability to synthesize the vasoconstrictor prostaglandin H₂ and/or thromboxane A₂ in renal vessels (1) acts as an autocrine amplifier of pressor agents and (2) may contribute to resetting the pressure natriuresis curve which is a prerequisite for the development and maintenance of hypertension.     

The Presence of (+)-S-Adenosyl-l-Methionine in the Rat Brain and Its Lack of Effect on Phenylethanolamine N-Methyltransferase Activity

Abstract: (+)-S-Adenosyl- l -methionine [(+)-SAM] was isolated from rat brain and was quantified by HPLC followed by UV spectrophotometric measurements and by ¹H-NMR. Its estimated ratio in brain is 3% of total SAM. Because of its commercial unavailability, (+)-SAM was also prepared from chemically synthesized SAM by separation of the two diastereoisomers on a preparative reverse-phase Nucleosil C8 column. The (+) diastereoisomer thus obtained was then assayed in vitro both as an inhibitor and a substrate of phenylethanolamine N -methyltransferase. Enzymatic activity was measured by HPLC analysis. It was shown that (+)-SAM has no effect on phenylethanolamine N -methyltransferase activity; therefore, it is unlikely that (+)-SAM plays any possible role in regulation of adrenaline synthesis in the brain.     

The IS4 family of insertion sequences: evidence for a conserved transposase motif

The eight IS 231 variants characterized so far (IS 231 A-F, V and W) display similar transposases with an overall 40% identity. Comparison with all the proka-ryotic transposable elements sequenced so far revealed that the IS231 transposases share two conserved regions with those of 35 other insertion sequences of wide origins. These insertion sequences, defining the IS4 family, have a common bipartite organization of their ends and are divided into two similarity groups. Interestingly, the transposase domains conserved within this family display similarities with the well known integrase domain shared by transposases of the IS3 and IS15 families, and integrases of retroelements. This domain is also found in IS30- related elements and Tn7 TnsB protein. Amino acid residues conserved throughout all these prokaryotic and eukaryotic mobile genetic elements define a major transposase/integrase motif, likely to play an important role in the transposition process.     

Phenotypic effects of overexpression of Agrobacterium rhizogenes T-DNA ORF13 in transgenic tobacco plants are mediated by diffusible factor(s)

Nicotiana tabacum cv. Xanthi transgenic plants expressing ORF13 of Agrobacterium rhizogenes 8196 T-DNA under the 35S RNA promoter from the cauliflower mosaic virus displayed developmental abnormalities. They were small, with short and variable internodal lengths, their root systems were poorly developed; leaves were small, asymmetric, rounded, wrinkled and dark green; flowers were short, and irregularly shaped. They exhibited reduced apical dominance and regularly produced offshoots at the base of the plant. This phenotype was also exhibited by offshoots of normal N. tabacum cv. Xanthi stock grafted with a transgenic scion indicating that expression of ORF13 influences plant development via diffusible factor(s).     

Parthenogenesis in an elasmobranch in the presence of conspecific males

Parthenogenesis has been observed in several elasmobranch species, primarily in public aquaria. The majority of cases of parthenogenesis have occurred either when females were held without males or once a male was removed from a female's habitat. Here we report a second instance of parthenogenesis in a zebra shark female that was housed with conspecific mature males. This study calls into question the conditions under which elasmobranch females undergo parthenogenesis.