Evidence for a plasmid conferring salt-tolerance in the plant-root associated,diazotrophKlebsiella sp. NIAB-I

Summary Using analytical and preparative methods, we demonstrated the presence of an indigenous plasmid (pNIAB-I) in a diazotroph,Klebsiella sp. NIAB-I isolated, from the roots of Kallar grass, growing on saline lands in Pakistan. The plasmid is approximately 50 kilobase (kb) in size. Transformation experiments indicated that non-halophilic bacteria such asE. coli K12 strain (MV10) andK. pneumoniae M5AI on acquiring this plasmid become tolerant to high salt (NaCl) and alkaline pH.     

Discovery of isolated patches ofIcerya purchasi byRodolia cardinalis: A field study

The discovery of isolated patches of prey by the natural enemies of the cottony-cushion scaleIcerya purchasi Maskell was tested in the field on potted plants ofAcacia baileyana and citrus between November and February in South Australia. The survival of scales to adults in patches in the 4 fortnightly releases (cohort sets) was not significantly different between location-1 (under anAcacia tree harbouring scales and its natural enemies) and location-2 (about 500 m away from the nearest host plant of the scale). The temporal distribution of mortality in the scale cohorts was described by the Weibull model. The proportion of scales surviving at the 2 locations (on the 3^rd & 6^th fornight) was not significantly different suggesting that the total effect of all the mortality factors on the scales at the 2 locations was the same. The trends in prey patches destroyed in time could be explained from the period of activity of the natural enemies in the field.Rodolia cardinalis (Mulsant) had discovered the prey patches within a fortnight of the release of scale crawlers. The results substantiate earlier reports thatRodolia can find and destroy isolated scale colonies.      

Evaluation of hydroxyl radical-scavenging property of garlic

While antibiotics are broadly used in dental and medical therapy, little attention has been directed towards the potential toxic side effects of antibiotics on tissue regeneration. Here we examined the effect of a quinolone antibiotic, pefloxacin (Rhone Poulenc) on rat parotid gland responses to chronic isoproterenol treatment. Groups of rats received injections of isoproterenol to induce glandular growth, saline (controls), pefloxacin, or isoproterenol and pefloxacin in combination. Parotid gland weight decreased significantly after pefloxacin treatment for 7 days as well as inhibiting glandular enlargement provoked by isoproterenol. The same trend was observed for the rates of DNA synthesis, with the incorporation of [³H]-thymidine in isoproterenol/pefloxacin-treated rats reduced to 49% of isoproterenol treatment alone levels. Saline-treated animals were 42% of the rate of [³H]-thymidine incorporation into DNA observed in isoproterenol treated rats. While isoproterenol treatment increased steady-state mRNA levels for fos, jun, myc, src, c-erbB-2, ras and topo II, inclusion of pefloxacin with the isoproterenol regimen blocked these increases. Pefloxacin treatment by itself did not alter proto-oncogene mRNA levels in the parotid gland. Glandular amylase activity was decreased in the pefloxacin treated group, while the combination of isoproterenol with pefloxacin did not decrease glandular amylase levels to the extent of that observed with -agonist treatment alone. In acute experiments, pefloxacin significantly decreased the volume of saliva secreted by the parotid gland. These results suggest that quinolone-based antibiotics disturb the secretory function of the parotid gland and can inhibit cell proliferation and regeneration. (Mol Cell Biochem 165: 55–63, 1996)     

Refinement of the Van der Woude Gene Location and Construction of a 3.5-Mb YAC Contig and STS Map Spanning the Critical Region in 1q32–q41

Van der Woude syndrome (VWS) is the most frequent form of syndromic clefting. Linkage analysis has localized the gene between D1S245 and D1S414, an interval of 4.1 cM with the following order of loci: centromere–D1S245/D1S471–D1S491–D1S205–D1S414–telomere. A microdeletion around D1S205 aided in narrowing the critical region to D1S491–D1S414 by heterozygosity testing. In this study, the location was refined by detection of a recombinant with D1S205 in a new family, indicating that VWS lies between D1S491 and D1S205, a 1.6-cM interval. A roughly 3.5-Mb YAC contig was built from D1S245 through D1S414, encompassing the interval D1S491–D1S205 in level 1 or level 2 paths. Clones were assembled by sequence tagged site (STS) content using the five polymorphic markers from above, four novel STSs identified from YAC ends, and a new STS derived from probe CRI-L461 (D1S70). D1S70 was assigned to the critical region. One single YAC, yCEPH785B2, contains both flanking STSs (D1S491, D1S205). STS content mapping suggests neither chimerism nor deletion of yCEPH785B2 but does suggest that the maximum size of the critical region is approximately 850 kb. All STSs were tested for their presence on a somatic cell hybrid containing the microdeleted chromosome 1 as the sole human chromosome 1 component. Both the proximal and distal ends of the microdeletion mapped to the 850-kb YAC, yCEPH785B2. Therefore, the microdeletion overlapped the critical region, confirming the genetic recombinant data.     

Protective effects of lazaroids against oxygen-free radicals induced lysosomal damage

Lipid peroxidation of membranes by oxygen free radicals has been implicated in various disease states. Different antioxidants and iron chelators have been used to reduce lipid peroxidation. Lazaroids have been used for the acute treatment of central nervous system disorders such as trauma and ischemia wherein lipid peroxidative processes take place.In this study we evaluated the effect of lazaroids (U-785 18F and U-74389F) on the release of acid phosphatase activity and formation of malondialdehyde (MDA) in rat liver lyosomes subjected to exogenously generated oxygen free radicals. There was a significant increase in the acid phosphatase release and MDA formation in the presence of oxygen free radicals. This was prevented by both the lazaroids. In a separate study the effect of lazaroid U-74389F was seen on the zymosan-stimulated polymorphonuclear (PMN) leukocyte-derived chemiluminescence. The PMN leukocyte chemiluminescent activity was attenuated by the lazaroid in a dose-dependent manner. These studies suggest that lazaroids may inhibit lipid peroxidation and stabilize the membrane.     

Bloom Syndrome and Maternal Uniparental Disomy for Chromosome 15

Bloom syndrome (BS) is an autosomal recessive disorder characterized by increases in the frequency of sister-chromatid exchange and in the incidence of malignancy. Chromosome-transfer studies have shown the BS locus to map to chromosome 15q. This report describes a subject with features of both BS and Prader-Willi syndrome (PWS). Molecular analysis showed maternal uniparental disomy for chromosome 15. Meiotic recombination between the two disomic chromosomes 15 has resulted in heterodisomy for proximal 15q and isodisomy for distal 15q. In this individual BS is probably due to homozygosity for a gene that is telomeric to D15S95 (15q25), rather than to genetic imprinting, the mechanism responsible for the development of PWS. This report represents the first application of disomy analysis to the regional localization of a disease gene. This strategy promises to be useful in the genetic mapping of other uncommon autosomal recessive conditions.     

Termination of endothelin signaling: Role of nitric oxide

Cellular mechanisms responsible for the termination of ET-1 signal are poorly understood. In order to examine the hypothesis that nitric oxide serves as a physiological brake of ET- 1 signaling, Chinese hamster ovary (CHO) cells stably transfected with the ET_A receptor cDNA (CHO-ET) were studied. CHO-ET responded to ET-1 with robust [Ca²⁺], transients and developed a long-lasting homologous desensitization. Donors of nitric oxide (NO), 3-morpholino-sydnonimine HCl(SIN-1), or sodium nitroprusside (SNP) reduced the amplitude of these responses, accelerated the rate of [Ca²⁺], recovery, and counteracted the development of homologous desensitization by a cyclic GMP-independent mechanism, suggesting an alternative mode for NO modulation of ET-1 responses. Stimulation of CHO-ET cells with mastoparan, a wasp venom acting directly on G proteins (bypassing receptor activation), was inhibited by NO, revealing a postreceptoral target for NO-induced modulation of [Ca²⁺] mobilization. Using a lys⁹-biotinylated ET-1 (ET-1 [BtK⁹]), binding sites were “mapped” in CHO-ET cells. Receptor-ligand complexes did not exhibit spontaneous dissociation during 60min observations. Quantitative fluorescence microscopy revealed that SNP or SIN-1 caused a rapid, concentration-dependent, and reversible dissociation of biotinylated ET- 1 from ET_A receptor (EC₅₀ = 75 μM and 6 μM, respectively), an effect that was not mimicked by 8-bromo-cyclic GMP. “Sandwich” co-culture of endothelial cells with CHO-ET showed that activation of NO production by endothelial cells similarly resulted in dissociation of ET-1 [BtK⁹] from ET_A receptors. We hypothesize that NO plays a role in physiological termination of ET-1 signalling by dual mechanisms: (1) displacement of bound ET-1 from its receptor, thus preventing homologous desensitization, and (2) interference with the postreceptoral pathway for [Ca²⁺] mobilization, hence inhibiting end-responses to ET-1. © 1994 Wiley-Liss, Inc.     

Enhanced Phosphodiestric Breakdown of Phosphatidylinositol Bisphosphate After Experimental Brain Injury

Abstract: Regional levels of lactate and inositol 1,4,5-trisphosphate (IP₃), a cellular second messenger of the excitatory neurotransmitter system, were measured after lateral fluid percussion (FP) brain injury in rats. At 5 min postinjury, tissue lactate concentrations were significantly elevated in the cortices and hippocampi of both the ipsilateral and contralateral hemispheres. By 20 min postinjury, lactate concentrations were elevated only in the cortices and hippocampus of the ipsilateral hemisphere. Whereas the IP₃ concentrations were elevated in the hippocampi of the ipsilateral and contralateral hemisphere and in the cortex of ipsilateral hemisphere at 5 min postinjury, no elevation in these sites was found at 20 min postinjury. Histologic analysis revealed neuronal damage in the cortex and CA3 regions of hippocampus ipsilateral to the injury at 24 h postinjury. The present results suggest activation of the phosphoinositide signal transduction pathway at the onset of injury and of a possible requirement of early persistent metabolic dysfunction (>20 min) such as the lactate accumulation in the delayed neuronal damage.