MIAH: automatic alignment of eukaryotic SSU rRNAs.

SUMMARY: MIAH is a WWW server for the automatic alignment of new eukaryotic SSU rRNA sequences to an existing alignment of 1500 sequences. AVAILABILITY: http://chah.ucc.ie/MIAH Contact :     

Development of an acute and chronic ecotoxicity assay using lux-marked Rhizobium leguminosarum biovar trifolii

A soil isolate of Rhizobium leguminosarum bv. trifolii was marked with a lux CDABE gene cassette to enable the expression of bioluminescence. The suitability of the bacterium as a soil pollution biosensor was assessed using acute and chronic assays. Bacterial bioluminescence responded sensitively to the metals studied. The order of sensitivity was found to be Cd > Ni = Zn > Cu for the acute test and Cd > Ni = Zn = Cu for the chronic test. The sensitive response of the biosensor highlighted its potential for use as an indicator of soil pollution.     

Purification and partial characterization of a bovine epidermal growth factor-like polypeptide

A heterologous radioreceptor assay was developed to follow the purification of an EGF-like polypeptide from bovine kidney. Purification of the growth factor was facilitated by the use of a novel affinity column using fixed A431 cells attached to sephadex beads. The mol. wt. of the purified EGF-LP was estimated to be 5480 from the amino acid composition. The purified EGF-like polypeptide stimulated the proliferation of bovine mammary epithelial cells and appeared to be equipotent to mouse EGF. Available evidence suggests that the purified molecule is distinct from bovine TGF-alpha.     

Adriamycin resistance in HL60 cells in the absence of detectable P-glycoprotein

Previous studies have shown that the development of multi-drug resistance in cell lines treated with chemotherapeutic agents is closely associated with the overexpression of a 170-180 kilodalton surface membrane glycoprotein (P-glycoprotein). In the present study a monoclonal antibody against the P-glycoprotein was used to determine if this protein is overexpressed in multi-drug resistant HL60 cells. Using either indirect immunofluorescent staining or immunoblot analysis P-glycoprotein could not be detected in HL60 cells isolated for resistance to adriamycin. In contrast HL60 cells isolated for resistance to vincristine contain the P-glycoprotein and the amount of this material increases with increasing levels of resistance. These studies thus demonstrate adriamycin resistance in P-glycoprotein negative HL60 cells. Furthermore adriamycin and vincristine are found to have distinct effects in inducing overexpression of P-glycoprotein in the HL60 cell line. This information could be useful in the development of therapeutic strategies for the treatment of certain forms of cancer.     

Alpha-chloralose as a capture and restraint agent of birds: therapeutic index determination in the chicken

The median effective dose for capture (ED50) and the median lethal dose (LD50) of alpha-chloralose given orally to domestic chickens (Gallus domesticus) were determined by probit analysis to be 45 mg/kg and 300 mg/kg, respectively. The therapeutic index (TI = LD50/ED50) was 6.7. This indicates that alpha-chloralose is only a marginally safe capture agent in domestic species and particularly in field applications involving other wild avian species in which the amount of the drug ingested by an individual bird is not controlled.     

Inhibition of the oxygen-induced contraction of the isolated human umbilical artery by indomethacin, flurbiprofen, aspirin and drugs modifying Ca2+ disposition

In this study we have quantified the potency of three cyclo-oxygenase inhibitors, indomethacin, flurbiprofen and aspirin to reduce the vasoconstriction of isolated strips of human umbilical artery (HUA) to changing the oxygen-tension (PO2) of the bathing medium. The inhibitory potencies (IC50) of indomethacin and flurbiprofen were similar (IC50 = 2.1 x 10(-9) M and 7.6 x 10(-9) M respectively) while aspirin (IC50 = 2.5 x 10(-5) M) was approximately 12,000 fold less potent than indomethacin. At the physiological PO2 of 15 mmHg the isolated HUA was found to have an inherent cyclo-oxygenase induced tone since either reducing the PO2 from 15 to OmmHg or adding cyclo-oxygenase inhibitors caused vasorelaxation. O2-induced contractions were partly dependent on extracellular Ca2+: nifedipine and Bay K 8644 inhibited and enhanced oxygen-induced contractions, respectively, but did not have a significant effect on calcium-dependent 5-hydroxy-tryptamine-induced (5-HT) contractions. Therefore cyclo-oxygenase products and 5-hydroxytryptamine-induced contractions of the HUA may both utilise extracellular calcium but through different processes.     

Alterations in alpha 1-adrenoceptor stimulation of isolated atria from experimental diabetic rats

This purpose of this investigation was to determine the influence of experimental diabetes (3 months) on the responsiveness of rat isolated atria to alpha 1-adrenoceptor stimulation by phenylephrine. Diabetes was chemically induced with streptozotocin (65 mg/kg i.v.) in 42- to 43-day-old, nonfasted male Sprague-Dawley derived rats. Chronotropic (right atria) and inotropic (left atria) indices were recorded in response to alpha 1-adrenoceptor stimulation by phenylephrine. These experiments were performed in the presence of beta-adrenoceptor antagonism (timolol). Isolated right atria from diabetic rats demonstrated a greater increase in heart rate in response to phenylephrine than did corresponding control atria. Left atria were supersensitive (decrease in EC50 values) and hyperresponsive to alpha 1-adrenoceptor stimulation by phenylephrine when compared with stimulation of control left atria. Diabetic left atria in response to phenylephrine were observed to exchange more radioactive calcium (45Ca2+) than control left atria, whereas both diabetic and control left atria exchanged the same amount of 45Ca2+ during basal contractile conditions. Phenylephrine had no effect on 45Ca2+ efflux from either diabetic or control atria. These results indicate that 3 months of uncontrolled experimental diabetes in the rat produces an enhancement of alpha 1-adrenoceptor activation of isolated atria, and that there is an alteration in Ca2+ mobilization which may contribute to the enhanced receptor activation.     

Expression of normal and activated human Ha-ras cDNAs in Saccharomyces cerevisiae.

We expressed normal and activated human cellular Ha-ras cDNAs which encode 21,000-dalton polypeptides (p21s) in Saccharomyces cerevisiae by their insertion into a 2 micron-based replicating plasmid vector under 3-phosphoglycerate kinase promoter control. We found that newly synthesized p21 in S. cerevisiae was produced as a soluble precursor (pro-p21) which matured into a form electrophoretically indistinguishable from the processed form (p21) observed in mammalian cells. Coincident with the processing event was translocation to a membrane component, suggesting a coupling of the two events. Using vectors that direct the synthesis of p21 variants possessing the ability to autophosphorylate in vitro, we found that processing of p21 did not significantly affect this autophosphorylation reaction. In contrast to Escherichia coli, marked phenotypic changes were observed in S. cerevisiae as a consequence of the synthesis of p21, including reduction in growth rate and induction of flocculation. Accompanying these phenotypic alterations was a significant elevation of adenylate cyclase activity.