Mapping of mutations in Pseudomonas aeruginosa defective in pyoverdin production.

Twelve mutants of Pseudomonas aeruginosa PAO defective in pyoverdin production were isolated (after chemical and transposon mutagenesis) that were nonfluorescent and unable to grow on medium containing 400 microM ethylenediaminedi(o-hydroxyphenylacetic acid). Four mutants were unable to produce hydroxamate, six were hydroxamate positive, one was temperature sensitive for pyoverdin production, and another was unable to synthesize pyoverdin on succinate minimal medium but was capable of synthesizing pyoverdin when grown on Casamino Acids medium (Difco Laboratories, Detroit, Mich.). The mutations were mapped on the PAO chromosome. All the mutations affecting pyoverdin production were located at 65 to 70 min, between catA1 and mtu-9002.     

Expression in Escherichia coli and function of Pseudomonas aeruginosa outer membrane porin protein F

The gene encoding porin protein F of Pseudomonas aeruginosa was cloned onto a cosmid vector into Escherichia coli. Protein F was expressed as the predominant outer membrane protein in a porin-deficient E. coli background and was clearly visible on one-dimensional sodium dodecyl sulfate-polyacrylamide gels in a porin-sufficient background. The identity of the protein F from the E. coli clone and native P. aeruginosa protein F was demonstrated by their identical mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoretograms, 2-mercaptoethanol modifiabilities, and reactivities with monoclonal antibodies specific of two separate epitopes of protein F. In the course of gene subcloning, a 2-kilobase DNA fragment was isolated, with an apparent truncation of the part of the gene encoding the carboxy terminus of protein F. This subclone produced a 24,000-molecular-weight, outer membrane-associated, truncated protein F derivative which was not 2-mercaptoethanol modifiable and which reacted with only one of the two classes of protein F-specific monoclonal antibodies. The 2-kilobase fragment was used in Southern blot hybridizations to construct a restriction map of the cloned and subcloned fragments and to demonstrate with restriction digests of whole P. aeruginosa DNA that only one copy of the protein F gene was present in the P. aeruginosa chromosome. The protein F produced by the original cosmid clone in a porin-deficient E. coli background was purified. To demonstrate retention of porin function after cloning, the protein F from the E. coli clone was incorporated into black lipid bilayer membranes. Two major classes of channels were revealed. The predominant class of channels had an average conductance of 0.36 nS in 1 M KCl, whereas larger channels (4 to 7 nS) were seen at a lower frequency. Similar channel sizes were observed for porin protein F purified by the same method from P. aeruginosa outer membranes.     

Immunocytochemical identification of α-endorphin-like material in neurones of the brain and corpus cardiacum of the blowfly,Calliphora vomitoria (Diptera)

Summary A group of the 24–26 paraldehyde fuchsin-positive median neurosecretory cells (MNC) in the pars intercerebralis of the brain of the blowfly, Calliphora vomitoria, has shown immunoreactivity towards three different antibodies to -endorphin, a peptide that corresponds to the amino acid sequence present between residues 61 and 76 of the precursor molecule, -lipotropin (-LPH). The immunoreactive material could be followed in axons within the median bundle, the tract through which neurosecretory material from the MNC is passed down to the corpus cardiacum (CC). The -endorphin-immunoreactive material was observed leaving the CC in the cardiac-recurrent nerve, dorsal to the proventriculus, in the direction of the abdomen. The cells that contain the -endorphin-like material are different from those of the MNC that contain insulin-, pancreatic polypeptide-, and gastrin/CCK-like peptides. This finding demonstrates the considerable complexity and peptidergic nature of the MNC and constitutes further evidence that morphinomimetic-like peptides are present in the nervous system of invertebrates.     

Maternal and paternal origin of extra chromosome in trisomy 21

Summary Fluorescence markers were studied in 40 patients with Down's syndrome and their parents. In 11 cases maternal and in 5 cases paternal non-disjunction could be shown. The disjunctional event occurred in the first meiotic division in 5 maternal and in 2 paternal cases. A second division failure was found in 4 maternal and 2 paternal cases. In 3 cases the failure could either be of first or second meiotic division origin.     

Degradation and induction specificity in actinomycetes that degrade p-nitrophenol.

We have isolated two soil bacteria (identified as Arthrobacter aurescens TW17 and Nocardia sp. strain TW2) capable of degrading p-nitrophenol (PNP) and numerous other phenolic compounds. A. aurescens TW17 contains a large plasmid which correlated with the PNP degradation phenotype. Degradation of PNP by A. aurescens TW17 was induced by preexposure to PNP, 4-nitrocatechol, 3-methyl-4-nitrophenol, or m-nitrophenol, whereas PNP degradation by Nocardia sp. strain TW2 was induced by PNP, 4-nitrocatechol, phenol, p-cresol, or m-nitrophenol. A. aurescens TW17 initially degraded PNP to hydroquinone and nitrite. Nocardia sp. strain TW2 initially converted PNP to hydroquinone or 4-nitrocatechol, depending upon the inducing compound.     

Combined removal of nitrate and carbon in granular sludge: Substrate competition and activities

Granular sludge from an upflow anaerobic sludge blanket reactor treating synthetic waste water containing a mixture of volatile fatty acids and nitrate showed a removal efficiency of nearly 100% for both nitrogen and carbon. This activity was achieved by a combined process of denitrification and methanogenesis under conditions of surplus carbon. Under batch conditions the two processes proceeded clearly separated in time with first denitrification dominating and excluding methanogenesis. However, as soon as nitrate was depleted, methane production was initiated, showing that the inhibition of methanogenesis by nitrate was reversible. Of the volatile fatty acids supplied to the reactor, i.e. acetate, propionate, and butyrate, the denitrifying population clearly preferred butyrate and propionate even though acetate could also be metabolized. Consequently, growth of syntrophic volatile fatty acid degraders was suppressed by the denitrifiers in cases of low C:N ratios in the medium, leaving acetate as the major substrate for methanogenesis.Abbreviations UASB upflow anaerobic sludge blanket - COD chemical oxygen demand - VFA volatile fatty     

Comparisons of genetic diversity in a narrow endemic, Impatiens hypophylla, and in its widespread congener, I. textori (Balsaminaceae)

Genetic diversity in two species of Impatiens in Korea was investigated using starch gel electrophoresis. Impatiens hypophylla is a rare species endemic to southwestern Japan and southeastern Korea, whereas I. rextori is widespread in East Asia. Impatiens textori has considerably higher genetic diversity than I. hypophylla . For example, mean values of genetic diversity within populations (He) of I. textori and I. hypophylla were 0.206 and 0.102, respectively. The high outcrossing rate (mean 1 = 0.89), abundance and widespread distribution, and large population size may be factors responsible for the maintenance of high levels of genetic variation in I. textori . Analyss of fixation indices indicated that considerable population substructuring within populations of I. hypophylla , partly resulting from inbreeding and/or genetic drift in small populations coupled with limited gene flow (mean F_IS= 0.699). However, the degree of population divergence observed in I. hypophylla (mean G_ST= 0.059) was considerably lower than that in other plants with similar life history traits. It is supposed that similar selection at populations of I. hypophylla examined might maintain similar gene frequencies in isolated populations.     

Morphometric and Isozyme Analysis of the Genus Hosta (Liliaceae) in Korea

Abstract The hostas native to Korea have never been carefully reviewed taxonomically and their patterns of variability are not well understood. For morphological and electrophoretic studies, samples of rootstocks were taken from 45 Korean Hosta populations and from two populations of H. tsushimensis N. Fujita on Tsushima Island, Japan. For morphometric analysis, ten plants from each of twenty populations were grown and observed under greenhouse conditions. Fifty-one floral and vegetative characters were examined on each plant and the data were analyzed using principal components and cluster analysis. Six Korean species can be recognized: H. yingeri S. B. Jones (Taehuksan, Sohuksan, and Hong islands); H. capitata (Koidz.) Nakai (southern Korea); H. clausa Nakai (central and northern Korea); H. minor (Baker) Nakai (southeastern Korea including Wan and Kojae islands); H. venusta F. Maekawa (Cheju Island); and H. jonesii M. Chung (southern islands). Morphological features contributing to recognition of the natural groups were: ridges on the scape; the width of inner and outer floral lobes; bracts pappillous at apex; length and color of the bracts; length of inflorescences; the withering condition of the bracts; scabrous nerves on the lower leaf surface; and size of the leaves. Isozyme analyses indicate a recent origin of H. venusta from H. minor. Although hostas are easily hybridized, natural hybridization seems to be rare in Korea. The morphological and isozyme studies identified no hybrids and the species are well characterized by their distribution patterns, phenology, and habitats.     

Neuronal protein gene product 9.5 (IEF SSP 6104) is expressed in cultured human MRC-5 fibroblasts of normal origin and is strongly down-regulated in their SV40 transformed counterparts

Neuronal protein gene product 9.5 (PGP 9.5) most likely identical to ubiquitin carboxyl-terminal hydrolase isozyme LI (UCH-LI) has been reported to be expressed almost exclusively in neuronal and neuroendocrine tissues. By two-dimensional (2D) immunoblotting, comigration and microsequencing of proteins recovered from 2D gels we have identified PGP 9.5/UCH-LI as polypeptide IEF SSP 6104 (M_r = 27000, PL = 5.49) in the comprehensive 2D gel cellular protein database of human embryonal lung MRC-5 fibroblasts [(1989) Electrophoresis 10, 76–115; (1990) Electrophoresis 11, 1072–1113]. This protein is expressed at high levels in quiescent and proliferating cultured normal fibroblasts and is strongly down-regulated (about 10 times) in their transformed counterparts.