Molecular Identification of Aeromonas and Coliform Bacteria Isolated on m Endo Media from Lake Erie Waters

Summary Bacteria from recreational waters collected from two Lake Erie beaches in Dunkirk, New York were plated onto m Endo LES media. The 16S rRNA gene was then amplified from coliform and non-coliform bacteria using the polymerase chain reaction. The PCR products were characterized by restriction fragment length polymorphism (RFLP) analysis. A total of 8 RFLP groups were identified from the analysis of 920 samples and selected PCR products from each group were sequenced. The DNA sequence analysis indicated that more than half of the bacteria identified as coliforms on the m Endo plates belonged to the genus Aeromonas from the family Aeromonadaceae. Most of the remaining coliforms were from the Enterobacteriaceae. The data indicate that m Endo agar plates allow the growth of non-coliform bacteria, especially Aeromonas species.     

A predominant idiotype on rabbit anti-VH a1 allotype antibodies: sharing by both major and minor VH subgroups

In every rabbit examined, greater than or equal to 80% of antibodies directed against the VH allotypic marker, a1, bears a predominant idiotype (IdX-a1). The IdX-a1 marker is site-associated and expressed on H chains, but not L chains, of anti-a1 antibody. Experiments using rabbits suppressed for the VH a subgroup demonstrated that IdX-a1 can be associated with both major (a+) and minor (a-) VH subgroup gene products and that a1 rabbits contain IdX-a1 within their genetic repertoire. The genetic and regulatory implications of our results are discussed.     

Antigenic structure and variation in an influenza virus N9 neuraminidase.

We previously determined, by X-ray crystallography, the three-dimensional structure of a complex between influenza virus N9 neuraminidase (NA) and the Fab fragments of monoclonal antibody NC-41 [P. M. Colman, W. G. Laver, J. N. Varghese, A. T. Baker, P. A. Tulloch, G. M. Air, and R. G. Webster, Nature (London) 326:358-363, 1987]. This antibody binds to an epitope on the upper surface of the NA which is made up of four polypeptide loops over an area of approximately 600 A2 (60 nm2). We now describe properties of NC-41 and other monoclonal antibodies to N9 NA and the properties of variants selected with these antibodies (escape mutants). All except one of the escape mutants had single amino acid sequence changes which affected the binding of NC-41 and which therefore are located within the NC-41 epitope. The other one had a change outside the epitope which did not affect the binding of any of the other antibodies. All the antibodies which selected variants inhibited enzyme activity with fetuin (molecular weight, 50,000) as the substrate, but only five, including NC-41, also inhibited enzyme activity with the small substrate N-acetylneuramin-lactose (molecular weight, 600). These five probably inhibited enzyme activity by distorting the catalytic site of the NA. Isolated, intact N9 NA molecules form rosettes in the absence of detergent, and these possess high levels of hemagglutinin activity (W.G. Laver, P.M. Colman, R.G. Webster, V.S. Hinshaw, and G.M. Air, Virology 137:314-323, 1984). The enzyme activity of N9 NA was inhibited efficiently by 2-deoxy-2,3-dehydro-N-acetylneuraminic acid, whereas hemagglutinin activity was unaffected. The NAs of several variants with sequence changes in the NC-41 epitope lost hemagglutinin activity without any loss of enzyme activity, suggesting that the two activities are associated with separate sites on the N9 NA head.     

Circumferential analysis of digitalized gamma angiocardiography by assessment of regional left ventricular contraction

After acquisition of a digital equilibrium gamma-angiocardiographie, circumferential analysis of end-diastolic and end-systolic frames gives 120 points diastolic and systolic curves. Their difference represents systolic volume and leads to regional left ventricular ejection fraction assessment at the considered radius level. The circumferential analysis evolute gives the regional left ventricular ejection fraction representative curves which allows especially differential diagnosis between left ventricular akinesia and dyskinesia.     

The cloned human oestrogen receptor contains a mutation which alters its hormone binding properties.

We demonstrate here that the human oestrogen receptor (hER) cDNA clone pOR8 obtained from MCF-7 cells contains an artefactual point mutation which results in the substitution of a valine for a glycine at amino acid position 400 (Gly-400----Val-400). This mutation in the hormone binding domain of the cloned hER destabilizes its structure and decreases its apparent affinity for oestradiol at 25 degrees C, but not at 4 degrees C, when compared with the wild-type hER with a Gly-400.     

Recombination and Replication of Plasmid-like Derivatives of a Short Section of the Mitochondrial Chromosome of Neurospora Crassa

The 21-kbp mitochondrial chromosome of the stp-ruv strain of Neurospora crassa undergoes regional amplification yielding plasmid-like supercoiled circles varying in size from subunit length to very high multimers. A comparison of the base sequence of the five plasmids studied, with the region of the chromosome from which they were derived, indicated that the amplified chromosomal segments were determined by a recombination-excision process near or within two structurally distinctive regions. One of these, consisting of nearly uninterrupted strings of Cs and Gs straddling tandem PstI site direct repeats, could form an extended hairpin loop with only a few mismatches. It was found at or near the 5' exchange point of all of the plasmids. An extended 35-bp sequence containing 17-bp direct repeats was the primary 3' site of exchange. Base sequence changes were found in the vicinity of exchange points. Most notable of these was a G insertion and T to C transition within a section of the 5' region likely to form a hairpin loop, suggesting the involvement of a mismatch repair-like mechanism in the recombination process. The sequence, TATATAGACATATA, was identified as a likely candidate for the site of replication initiation. A nearly identical sequence was found common to all of the corresponding plasmids of Podospora anserina and was reported near the presumed replication origin of the Drosophila yakuba mitochondrial chromosome. A search of GenBank revealed a remarkable association of the consensus sequence, TATATAGAXATATA, with the plus strand of organelle DNA.     

Deletion mapping of the medulloblastoma locus on chromosome 17p

Isochromosome 17q has previously been observed consistently in cytogenetic studies of medulloblastoma, the most common posterior fossa neoplasm in children. We performed a restriction fragment length polymorphism (RFLP) investigation of medulloblastoma which showed a loss of chromosome 17p sequences in 45% of these tumors. This finding was predictive of a poor clinical response to treatment. A contiguous panel of markers permitted mapping of the deletion to 17p12-p13.1, the same chromosomal region for which loss of alleles has been shown in tumor specimens from patients with colon cancer, and the same region to which the p53 gene has been mapped. This suggests that medulloblastoma is associated with a recessive oncogene on chromosome 17p that may be involved in the genesis of several embryologically unrelated neoplasms and that the absence of this gene in tumor tissue has prognostic significance.     

Some characteristics of TRH-induced grooming behavior in rats

Intracerebroventricular administration of TRH induces excessive grooming behavior that is characterized by an important contribution of the elements scratching and paw licking. As compared with other grooming inducing peptides, the pattern of TRH-induced grooming resembles that induced by beta-endorphin rather than those elicited by ACTH or bombesin. TRH-induced excessive grooming is suppressed by pretreatment with haloperidol, naloxone or neurotensin. Haloperidol suppresses TRH-induced grooming in a general way, whereas the suppressive effect of the other drugs is mainly due to a selective reduction of TRH-induced excessive scratching. Combined treatments of rats with TRH and a submaximal dose of ACTH, bombesin or beta-endorphin do not result in higher grooming scores than with single peptide treatment. Excessive grooming elicited by water immersion is not affected by TRH. It is concluded that TRH is undoubtedly an excessive grooming inducing peptide. In situations where excessive grooming is elicited by other peptides or by water immersion, TRH does not further activate the operating systems involved in the existing excessive grooming.     

Determination of the Cellular Mechanisms Regulating Thermo-Induced Stem Growth in Thlaspi arvense L

Field pennycress (Thlaspi arvense L.) is a species with a cold requirement for the initiation of reproductive development (thermoinduction). Work in this laboratory has been focused on elucidating the biochemical and molecular mechanisms underlying the bolting or rapid stem elongation response that is an intricate part of reproductive development in this species. In the present paper the cellular basis for thermo-induced stem growth was determined. Evidence is presented indicating that bolting results from the production of new cells that elongate to their original length before thermoinduction. This increase in cell division occurs in the pith and cortex approximately 0.5 to 5.0 millimeters below the stem apex. For at least the early stages of thermo-induced stem growth, enhanced cell elongation does not appear to be a factor because average lengths of pith cells from stems of thermo-induced plants were similar or less than noninduced controls. In addition, both the amount of increase in the production of new pith cells and stem growth were positively correlated with the length of the cold treatment. Two other lines of evidence are presented corroborating previous assertions (JD Metzger [1985] Plant Physiol 78: 8-13) that gibberellins mediate thermo-induced stem growth in field pennycress. First, treatment of noninduced plants with gibberellin A₃ completely mimicked the effects of a 4-week cold treatment on mitotic activity in the pith and cortex. Second, very little increase in the production of new cells was observed in the pith and cortex of thermo-induced plants of a gibberellin-deficient dwarf mutant of field pennycress. It is also shown that the influence of photoperiod on stem growth is mediated by an effect on the final length that cells ultimately attain.