Analysis of AVR4 promoter by sequential response-element deletion

Several reports have associated the variability in physico-chemical properties of avidin protein to dynamism inherent in the consensus regulatory networks within the promoter region of avidin genes. An Avr4 promoter region ligated to chloramphenicol acetyltransferase plasmid vector (pBLCAT2) to produce recombinant plasmid Avr4pBLCAT2 was sequentially deleted to produce five distinct mutants: Avr4pBLCAT2907-176, Avr4pBLCAT2809-176, Avr4pBLCAT2789-176, Avr4pBLCAT2429-176 and Avr4pBLCAT2 302-176. The transformants elicited different chloramphenicol acetyl transferase (CAT) activities. (African Journal of Biotechnology: 2003 2(7): 185-188

Swarming modulatory effects of some amino acids on Proteus strains from Lagos, Nigeria

Swarming motility, a multicellular behaviour characterized by periodic concentric growth on solid media has severally been reported as a constraint in the clinical investigation of mixed-culture infections involving Proteus and as a requirement for virulence. While media are being formulated to restrain swarming in this organism, the roles played by amino acids in the biogenesis of swarming have not been fully clarified. The effects of 20 amino acids on swarming, extracellular protease activity, cellular RNA level and total protein concentration in 20 clinical Proteus strains from Lagos, Nigeria were investigated. At 0.5mM concentration, glutamine, serine, and methionine were the only amino acids found to enhance swarming motility on M9 minimal medium (7.1—11.3 mm), cause significant increases in protease activity (33.7—48.3 units/ml), total protein concentration (22.5—28.6 mg/ml) and cellular RNA concentration (192.8—264.7 mg/ml) when compared to values obtained for other 17 amino acids (P < 0.05). Furthermore, the amino acid induced swarming in these strains was found to vary directly and significantly (P < 0.05) with protease activity and cellular RNA concentration. The exclusion of methionine, serine and glutamine when supplementing antiswarming media for clinical investigation of Proteus - associated polymicrobial infections in Nigeria is suggested. (African Journal of Biotechnology: 2002 1(1): 10-16

Comparative phytochemical evaluation, antimicrobial and antioxidant properties of Pleurotus ostreatus

This study scientifically examined the phytochemistry, antioxidant and antimicrobial potencies of two organic extracts of Pleurotus ostreatus. Generally, both extracts were effective against 89.8% of theisolates tested with Bacillus subtilis (7.6 – 7.8 mm), Escherichia coli (7.6 – 8.2 mm) and Saccharomycee cerevisae (10.5 – 10.8 mm) exhibiting highest gram ±ve, gram –ve and fungal susceptibilities by agar well diffusion method, respectively. However, petroleum ether extract (PE) exhibited greater anti-gram negative bacterial activity than the acetone extract (AE) and further produced growth inhibition of theseisolates in broth. Compared to PE, the acetone extract elicited higher total phenolic content and in vitro antioxidant capacity. Phytochemical analyses of the extracts revealed low to moderate levels of terpenoids, tannins, steroidal glycosides and carbohydrates, while flavonoids, alkaloids and cynogenic glycosides were not detected. The results indicate that P. ostreatus possesses antimicrobial and antioxidant potentials

Bacteriocinogenicity and production of pyocins from Pseudomonas species isolated in Lagos, Nigeria

A total of 52 strains of Pseudomonas identified as P. aeruginosa (27), P. putida (9), P. fluorescens (13) and P. stutzeri (3) were isolated from Nigerian patients with burns, wound and skin infections, UTI,diarrhoea and eye infections. 81.5, 55.6, 76.9 and 33.3% of these species produced pyocins at a range of 410 – 670 g/ml. High yields of pyocins at 35 – 37oC, which declined sharply at temperatures above37oC were obtained from all the producing strains. The strains also displayed significant pyocin expression (P 3 mm. These pyocins also displayed growth inhibitory activity against some Nigerian isolates of Gram-positive and Gram-negative bacteria when undiluted and at 1:2 - 1:16 dilutions. The susceptible organisms include Bacillus cereus, Listeria monocytogenes, Klebsiella spp., Staphylococcus aureus, S. epidermidis,Proteus spp. and Vibrio parahaemolyticus. The results of this study have provided evidence for broadspectrum antibacterial activity of pyocins elicited by Pseudomonas species from Nigeri

Genetic diversity of ochratoxigenic Aspergillus section Nigri, using RAPD and VCG techniques

This study evaluates the genetic diversity of ochratoxigenic Aspergillus section Nigri using RAPD and VCG techniques. Results obtained revealed OPX 07 as the most informative of the tested RAPD markers generating 12 polymorphic bands while the least bands were generated by OPR 19. Of the 40 Aspergillus section Nigri (20 each of Aspergillus niger and Aspergillus carbonarius), 22 VCGs and 27 RAPD haplotypes were delineated. The two techniques demonstrated similar resolution except in few cases where the RAPD technique further sub divided some VCGs into simpler haplotypes. The average percentage of variable VCG and RAPD reactions were 25 and 50% in that order of sequence while 75 and 50% of the isolates were resolved as same isolates by these techniques respectively. It was also found that the Simpson index of genetic diversity approached one for the isolates from the four geopolitical zones of Ogun State, Nigeria with the mean genetic diversity within isolates (GL) contributing significantly approximately 89% of the total diversity observed within the isolates (F=22.23, p&lt;0.05). The remaining 11% of variation could only be allotted to diversity among isolates (GS). On the whole, the total genetic diversity (HT) was found to be approximately 48%. In conclusion, RAPD markers provided better resolution than the classical VCG typing technique.Keywords; Genetic Diversity, Ochratoxigenic Aspergillus, RAPD and VC

Transcriptional factor influence on OTA production and the quelling attribute of Sirna on the OTA producing strains of Aspergillus section Nigri

This study determined the influence of some transcriptional factors on ochratoxin A production as well as investigates the quelling attributes of some designed siRNA on the OTA producing Aspergillus section Nigri using standard recommended techniques. Results obtained following comparison of the pks gene promoter sequences from 15 isolates depicts differences in length and homology with the pks gene ranging from 218bp in a strain of the Aspergillus niger to 700bp in Aspergillus carbonarius. The alignment of the pks gene promoter region revealed that six and two of the aligned genes have Aba A binding site corresponding to CATTCT and CATTCC respectively while Brl A binding site was absent in all the isolates. Pac C binding site corresponding to CCTGGC and GCCAAG was also found in two and three of the pks gene promoter region respectively. The three designed siRNA shows significant impact on OTA inhibitions with no significant statistical differences (80.9, 74.4 and 75.3% for pks_Ia, pks_Ib and pks_Ic respectively) (F= 3.830, p&gt;0.05). It can be concluded that Are A and Aba A are potential enhancers for ochratoxin A biosynthesis and none of the investigated transcriptional factors is enough for the activation of ochratoxin A production. However, pks gene was seen as a good target gene for inactivation in order to develop efficient means for ochratoxin A control using RNA silencing technology.Key words: Transcriptional factors, Ochratoxin A, siRNA, Quelling , Aspergillus section Nigr

Comparative biochemical and molecular evaluation of swarming of Proteus and effects of anti-swarm agents

In addition to inadequate understanding of swarming motility and virulence of Proteus, there is paucity of information on the relative effectiveness of the various anti-swarm agents. The anti-swarming effects of urea, sodium dodecylsulphate (SDS) and trihydroxymethylglycine (Tris) on 40 clinical isolates of Proteus Spp. were comparatively investigated and plasmids associated with swarming were characterized. The three substances elicited a comparable concentration-dependent anti-swarming property at 0.25 – 1.25% on nutrient agar. Anti-swarm agents displayed heterogeneity in their ability to cause significant decreases in the expression of virulence factors. Swarm motility was further found to be strongly associated with the expression of virulence factors in these strains. Of the Proteus strains tested, 32 were found to harbour 1 – 4 plasmids of size ranging from 6.0 – 33.5 kb. Plasmid curing resulted in loss of swarming in 65.6% of these strains. In order to reduce the risk of infection with virulent Proteus strains, the laboratory use of urea and SDS is suggested. Key Words: Proteus, swarming, urea, SDS, Tris. African Journal of Biotechnology Vol.3(1) 2004: 99-10

Evaluation of the Possible Mechanisms of Antihypertensive Activity of Loranthus micranthus: An African Mistletoe

Loranthus micranthus (LM), also called African mistletoe is a major Nigerian Loranthaceae plant used traditionally to treat hypertension. The methanolic leaf extract of the plant (LMME) has been shown to elicit anti-hypertensive activity in rats but mechanism remains unclear. This study was undertaken to study the effect of LM on pressor-induced contraction of rat aorta smooth muscles and serum lipid profiles in mice. The LMME was partitioned to produce n-butanol (NBF-LMME), chloroform (CF-LMME), ethyl acetate (EAF-LMME) and water (WF-LMME) fractions. The median effective concentrations and maximum relaxation of the fractions were determined against epinephrine and KCl pre-contracted rat aorta ring model. Serum lipid profiles and nitric oxide (NO) were determined spectrophotometrically in mice administered per orally 250 mg/kg b.w. of each fraction for 21 days. Data were analyzed statistically. NBF-LMME elicited the highest dose-dependent inhibitory effect on rat aorta pre-contracted with norepinephrine and KCl, followed in decreasing order by WF-LMME > CF-LMME > EAF-LMME. Similar order of activity was observed in the ability of these fractions to inhibit elevation in artherogenic lipids, raise serum nitric oxide and reduce cardiac arginase in mice. We conclude the anti-hypertensive activity of L. micranthus involve anti-artherogenic events, vasorelaxation, cardiac arginase reduction and NO elevation

Fertility knowledge, care seeking behavioral pattern and attitudes of infertile men in Lagos, Nigeria

Background: The objective was to study the extent of infertility knowledge, attitude and care seeking behavioral pattern of infertile men in Lagos.Methods: A cross sectional study was carried out using questionnaire between 2009 and 2014. Adult males who were clinically infertile, visiting the clinics for the first time and consented were studied. Descriptive statistics were used for the analysis.Results: Only 226 men, mean age 38±5.8 years participated. Up to 20.8% had sired a child for between >1 but 3 times (mean coitus 2.3±0.9 times) weekly. Only 11.1% knew about male-female factor infertility. Up to 42.9% knew about fertility and the sign of female ovulation and 38.1% correctly defined clinical infertility. Up to 40.3% switched treatment for competency of the new places and exorbitant price by 22.1%. Sixty-six (29.2%) made the first visit to a proper care place within a period >1 but 3 years. Majority (50 %) sought to know the causes of infertility, 14.6% how to improve fertility and 6.6% the reality of male infertility.Conclusions: Majority of the participants sought inappropriate help and delayed in seeking appropriate care. Poor collaboration and referral system observed. There is need for edification of both care providers and seekers to be ethical in their actions. Infertility care cost intervention is needed

Effects of experimental Neisseria meningitis W135 infection on serotoninergic parameters in mice

This study investigated the effects of Neisseria menigitidis W135 infection via intraperitoneal route on plasma free tryptophan concentration, brain serotonin and 5-hydroxyindole acetic acid (5-HIAA) levels in albino mice fed normal and tryptophan-enriched diets. The kinetics of appearance of viable bacteria in the blood, brain and liver following infection were also investigated. The serotoninergic parameters were determined by colorimetric and HPLC methods while colony counts were measured by plate count technique. Compared to normal diet, the tryptophan-enriched diet resulted in significantly (