Thymol and acibenzolar-s-methyl reduce incidence and severity of bacterial wilt of tomato caused by race I biovar III (R1B3) strain of Ralstonia solanacearum in Nigeria

Abstract

In Nigeria, most strains of Ralstonia solanacearum, the causative agent of tomato bacterial wilt disease; belong to race 1 biovar III (RIB3). Control strategies to assuage its destructive effect are highly necessary. A randomised complete-block design (RCBD) was used for the experiment. Thymol (0.7%) and Acibenzolar-s-methyl (ASM, 30 and 15?µg/ml) were used. Results indicated that the combination of thymol and ASM recorded the highest numbers of days for fruiting in Beske which were 74 and 75 while 59 and 60?days were recorded for UC82-B in both early and late seasons, respectively. When thymol and/or ASM were applied, bacterial wilt disease incidence and disease severity were significantly reduced and this was translated to a significant yield increase when compared with the untreated control plots. The results suggested that the combined application of thymol and ASM could be advantageous to tomato-growing farmers where R. solanacearum is prevalent.     

Effects of double ligation of Stensen's duct on the rabbit parotid gland

Salivary gland duct ligation is an alternative to gland excision for treating sialorrhea or reducing salivary gland size prior to tumor excision. Duct ligation also is used as an approach to study salivary gland aging, regeneration, radiotherapy, sialolithiasis and sialadenitis. Reports conflict about the contribution of each salivary cell population to gland size reduction after ductal ligation. Certain cell populations, especially acini, reportedly undergo atrophy, apoptosis and proliferation during reduction of gland size. Acini also have been reported to de-differentiate into ducts. These contradictory results have been attributed to different animal or salivary gland models, or to methods of ligation. We report here a bilateral double ligature technique for rabbit parotid glands with histologic observations at 1, 7, 14, 30, 60 days after ligation. A large battery of special stains and immunohistochemical procedures was employed to define the cell populations. Four stages with overlapping features were observed that led to progressive shutdown of gland activities: 1) marked atrophy of the acinar cells occurred by 14 days, 2) response to and removal of the secretory material trapped in the acinar and ductal lumens mainly between 30 and 60 days, 3) reduction in the number of parenchymal (mostly acinar) cells by apoptosis that occurred mainly between 14–30 days, and 4) maintenance of steady-state at 60 days with a low rate of fluid, protein, and glycoprotein secretion, which greatly decreased the number of leukocytes engaged in the removal of the luminal contents. The main post- ligation characteristics were dilation of ductal and acinar lumens, massive transient infiltration of mostly heterophils (rabbit polymorphonuclear leukocytes), acinar atrophy, and apoptosis of both acinar and ductal cells. Proliferation was uncommon except in the larger ducts. By 30 days, the distribution of myoepithelial cells had spread from exclusively investing the intercalated ducts pre-ligation to surrounding a majority of the residual duct-like structures, many of which clearly were atrophic acini. Thus, both atrophy and apoptosis made major contributions to the post-ligation reduction in gland size. Structures also occurred with both ductal and acinar markers that suggested acini differentiating into ducts. Overall, the reaction to duct ligation proceeded at a considerably slower pace in the rabbit parotid glands than has been reported for the salivary glands of the rat.     

Comparative action of calpain on erythrocyte Ca2+-pumping ATPase in sickle cell anaemia,essential hypertension and kwashiorkor

Calpain, a calcium-dependent, neutral cysteine-protease was purified from the erythrocyte cytosol of subjects having essential hypertension (HTN), sickle cell anaemia, (SCA), or kwashiorkor (KWA). Identical electrophoretic mobility on SDS-polyacrylamide gradient gel, sensitivity to micromolar amounts of Ca²⁺, absolute requirement for a reducing environment and a high susceptibility to inhibition by leupeptin and thiol-group modifying reagents confirm that calpain preparations from these erythrocytes are equivalent to calpain I. Whereas the extent of calpain activation of erythrocyte membrane Ca²⁺-pumping ATPase of normal subjects was almost equal to that due to calmodulin, calpain activation of the HTN and SCA pump was greater than activation by calmodulin. Like in normal membranes, exogenous calmodulin protected the Ca²⁺-pumping ATPase of these erythrocytes against calpainization; the degree of protection by calmodulin is least in SCA and HTN. Electrophoretic separation of erythrocyte membranes and the purified Ca²⁺-pumping ATPase of HTN, SCA and KWA subjects does not indicate the presence of fragments resulting from the proteolytic action of calpain.Abbreviations PMSF phenylmethylsulfonylfluoride - TLCK N--tosyl-L-lysine chloromethyl ketone - EGTA ethyleneglycol-bis (-aminoethylether) N,N¹-tetraacetic acid - ATP adenosine 5¹-triphosphate - Hepes 4-(2 hydroxyethyl)-1-piperazine ethanesulphonic acid - Tris-HC1 Tris (hydroxymethyl) aminomethane-hydrochloride - SDS sodium dodecyl sulphate     

AN INDIRECT ENZYME-LINKED IMMUNOSORBENT ASSAY FOR THE DETECTION OF LEPTOSPIRA INTERROGANS SEROVAR POMONA ANTIBODIES IN BOVINE SERA

An indirect ELISA was developed and initially evaluated for the detection of bovine antibodies to Leptospira interrogans serovar pomona. The antigen used in this ELISA was extracted from a serovar pomona culture supernatant by a combination of centrifugation, digestion with proteinase K and ultra-centrifugation. The antigen showed little cross-reaction with immune rabbit sera to L. interrogans serovars copenhageni, grippotyphosa, hardjo and sejroe and, Leptospira biflexa serovar patoc. Some cross-reaction was observed with immune rabbit serum to L. interrogans serovar canicola. The relative sensitivity of the ELISA was 94.76% confidence interval =± 3.32%) when estimated with bovine sera (n=172) with serovar pomona microscopic agglutination test (MAT) titers of 100. The relative specificity of the ELISA was 99.28% (95% confidence interval = 1.40%) when estimated with bovine sera (n=139) with MAT titers of <100 to L. interrogans serovars canicola, copenhageni, grippotyphosa, hardjo, pomona and sejroe. Thirty six of 258 field sera (13.95%) with serovar pomona MAT titers of <100, gave positive reactions in the ELISA.     

DEVELOPMENT AND EVALUATION OF A RAPID ENZYME-LINKED IMMUNOFILTRATION ASSAY (ELIFA) AND AN ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA) FOR THE DETECTION OF STAPHYLOCOCCAL ENTEROTOXIN B

An enzyme-linked immunofiltration assay (ELIFA) and a microtitre plate enzyme-linked immunosorbent assay (ELISA) were developed and compared for their ability to detect staphylococcal enterotoxin B (SEB). The double antibody capture format was used for both assays. Factors which improved the sensitivity of the ELIFA system were (1) addition of casein and thimerosal to the antigen dilution buffer; (2) addition of polyethylene glycol (MW 6000) to the detection and conjugate antibody dilution buffers; and (3) washing with diethanolamine buffer prior to addition of the substrate/chromogen. The ELIFA system had a turnaround time of approximately 1 h and a detection limit of 1 ng/mL of purified SEB. The ELISA had a total turnaround time of 21 h, or 3 h using plates pre-coated overnight with the capture antibody. The detection limit of the ELISA for purified SEB was 0.05 ng/mL. The detection limit of SEB in cheese samples spiked with purified enterotoxin and subjected to a simple extraction procedure was 1 ng/mL and 0.1 ng/mL of extract, with the ELIFA and the ELISA, respectively.     

Biting of anthropophilic Culicoides fulvithorax (Diptera: Ceratopogonidae), a vector of Mansonella perstans in Nigeria

Anthropophilic Culicoides were investigated in a rural community endemic for Mansonella perstans in Ijebu North area of western Nigeria between December 2003 and October 2004. Three hundred and fifty-nine adults of Culicoides fulvithorax collected by human bait in the morning were dissected for Mansonella perstans larvae, and 1.95% of infection rate was found. Seasonal abundance of C. fulvithorax was investigated by monthly biting rates, and showed that higher prevalence was observed in rainy season, with peak in September. Culicoides prevalence was positively correlated with rainfall and relative humidity, but not temperature. Human perceptions on the behavior of these biting midges were determined by interviewing 854 self-selected villagers, of which 86.5% of the interviewees confessed having experienced Culicoides bites. Between 76.5 and 99.1% of the various age groups complained body reactions to Culicoides bites. Itching was the most frequent body reaction. No interviewees associated Culicoides with transmission of any parasitic infections. The results showed need to adequately control Culicoides in the community.     

Intestinal helminthiases and schistosomiasis among school children in an urban center and some rural communities in southwest Nigeria

Intestinal helminths and schistosomiasis among school children were investigated in an urban and some rural communities of Ogun State, southwest Nigeria. Fecal samples of 1,059 subjects (524 males, 535 females) aged 3-18 years were examined using direct smear and brine concentration methods between June 2005 and November 2006. The pooled prevalence of infection was 66.2%. Ascaris lumbricoides showed the highest prevalence (53.4%) (P < 0.001) followed by hookworms (17.8%), Trichuris trichiura (10.4%), Taenia sp. (9.6%), Schistosoma mansoni (2.3%), Strongyloides stercoralis (0.7%), Schistosoma haematobium (0.6%), and Enterobius vermicularis (0.3%). The prevalences of A. lumbricoides, hookworms, Taenia sp., S. mansoni, and S. stercoralis in the urban centre were similar (P > 0.05) to those in the rural communities. The fertile and infertile egg ratios of A. lumbricoides in the urban centre and the rural communities were 13: 1 and 3.7: 1, respectively. Each helminth had similar prevalences among both genders (P > 0.05). The prevalence of A. lumbricoides increased significantly with age (P < 0.001). The commonest double infections were Ascaris and hookworms, while the commonest triple infections were Ascaris, hookworms, and Trichuris. The study demonstrates the need for urgent intervention programmes against intestinal helminthiases and schistosomiasis in the study area.     

A microbiological assay for sterigmatocystin,T-2 toxin and zearalenone

A survey was done to find microorganisms useful for assaying sterigmatocystin; T-2 toxin and zearalenone.Staphylococcus aureus was found to be sensitive to T-2 toxin and zearalenone;Bacillus cereus was found to be sensitive to T-2 toxin only; andEscherichia coli was sensitive to sterigmatocystin. The response of the organisms to sterigmatocystin; T-2 toxin and zearalenone was found to be linear between 4 and 100 μg with sterigmatocystin toE. coli; between 2 and 25 μg with T-2 toxin toStaph, aureus andB. cereus; and between 4 and 100 μg with zearalenone toStaph, aureus. The lower limits of sensitivity of the test were 2 μg T-2 toxin and zearalenone, and 4 μg sterigmatocystin. The assay is rapid (15–17 hrs); simple and inexpensive; and can be used to verify the toxicity of samples and to confirm thin layer chromatographic results.     

A full Bayesian hierarchical mixture model for the variance of gene differential expression

Background  

In many laboratory-based high throughput microarray experiments, there are very few replicates of gene expression levels. Thus, estimates of gene variances are inaccurate. Visual inspection of graphical summaries of these data usually reveals that heteroscedasticity is present, and the standard approach to address this is to take a log₂ transformation. In such circumstances, it is then common to assume that gene variability is constant when an analysis of these data is undertaken. However, this is perhaps too stringent an assumption. More careful inspection reveals that the simple log₂ transformation does not remove the problem of heteroscedasticity. An alternative strategy is to assume independent gene-specific variances; although again this is problematic as variance estimates based on few replications are highly unstable. More meaningful and reliable comparisons of gene expression might be achieved, for different conditions or different tissue samples, where the test statistics are based on accurate estimates of gene variability; a crucial step in the identification of differentially expressed genes.