Biosurfactant production and use in oil tank clean-up

A proprietary bacterial strain (Pet 1006) produced biosurfactants when grown on both glucose and an immiscible hydrocarbon as carbon sources. Pilot-plant-scale (1500 I) production gave, on repeated batch runs, 2 tonnes of culture broth containing active biosurfactant. The product was used as a substitute for chemical surfactants in a clean-up demonstration test carried out by Cargo Fleet Chemical Company Ltd. (UK) on an oil storage tank belonging to Kuwait Oil Company, Kuwait. The clean-up was successful in removing the sludge from the tank bottom, and it also allowed the recovery of more than 90% of the hydrocarbon trapped in the sludge. The recovered hydrocarbon had excellent properties and could be sold after being blended with fresh crude.I.M. Banat is at 5, Upper Galliagh Road, Londonderry, Northern Ireland BT48 8LW, UK but was at the Kuwait Institute for Scientific Research at the time this paper was written. The remaining authors are with the Kuwait Institute for Scientific Research, Biotechnology Department, P.O. Box 24885, 13109, Safat, Kuwait. I.M. Banat is the corresponding author.In view of the annexation of Kuwait by Iraq in August 1990, this paper has been accepted without return to the author for attention to minor details and for approval of certain editorial changes that have been made. The Editor-in-Chief therefore assumes full responsibility for any errors or omissions.     

Hydralazine differentially increases mRNAs for the alpha and beta subunits of prolyl 4-hydroxylase whereas it decreases pro alpha 1(I) collagen mRNAs in human skin fibroblasts.

We have used specific oligonucleotide probes to measure the effect of hydralazine on mRNA levels of the alpha and beta subunits of prolyl 4-hydroxylase (PH), a key post-translational modifying enzyme in collagen biosynthesis. Hydralazine exerts a paradoxical effect on collagen biosynthesis in cultured fibroblasts. Cells exposed to hydralazine synthesize substantially reduced amounts of collagen, which is severely deficient in hydroxyproline. Surprisingly, however, the level of prolyl hydroxylase activity assayed in extracts of treated cells is markedly increased, suggesting overproduction of the enzyme. Hybridization analysis indicated that in untreated cells the concentration of the alpha PH subunit mRNA was about 20-25% of the beta PH subunit mRNA concentration. Hydralazine treatment increased the mRNAs for both alpha and beta subunits of PH by three- to fourfold. A differential induction of these mRNAs was observed, however. The alpha subunit mRNA was maximally increased within 24 h, whereas the beta subunit mRNA was increased more slowly, reaching a maximum at 72 h. In contrast, the 5.8 and 4.8-kb mRNAs for pro alpha 1(I) collagen were virtually eliminated by 72 h. This study demonstrates that the increased prolyl hydroxylase activity is a direct result of hydralazine-mediated increases in steady state mRNA content for the alpha and beta subunits of this enzyme. Moreover, the earlier induction of alpha PH mRNA may provide the first evidence at the mRNA level that regulation of PH activity occurs mainly through regulation of the alpha subunit of PH. In addition, the decrease in collagen synthesis by hydralazine appears to result directly from suppression of both species of mRNA for pro alpha 1(I) collagen.     

Rickettsia influences thermotolerance in the whitefly Bemisia tabaci B biotype

Abstract The whitefly Bemisia tabaci harbors Portiera aleyrodidarum, an obligatory symbiotic bacterium, as well as several secondary symbionts, including Rickettsia, Hamiltonella, Wolbachia, Arsenophonus, Cardinium and Fritschea, the function of which is unknown. In Israel, Rickettsia is found in both the B and Q of B. tabaci biotypes, and while all other secondary symbionts are located in the bacteriomes, Rickettsia can occupy most of the body cavity of the insect. We tested whether Rickettsia influences the biology of B. tabaci and found that exposing a Rickettsia‐containing population to increasing temperatures significantly increases its tolerance to heat shock that reached 40°C, compared to a Rickettsia‐free population. This increase in tolerance to heat shock was not associated with specific induction of heat‐shock protein gene expression; however, it was associated with reduction in Rickettsia numbers as was assessed by quantitative real‐time polymerase chain reaction and fluorescence in situ hybridization analyses. To assess the causes for thermotolerance when Rickettsia is reduced, we tested whether its presence is associated with the induction of genes required for thermotolerance. We found that under normal 25°C rearing temperature, genes associated with response to stress such as cytoskeleton genes are induced in the Rickettsia‐containing population. Thus, the presence of Rickettsia in B. tabaci under normal conditions induces the expression of genes required for thermotolerance that under high temperatures indirectly lead to this tolerance.     

Silencing of ZFP36L2 increases sensitivity to temozolomide through G2/M cell cycle arrest and BAX mediated apoptosis in GBM cells

Molecular Biology Reports - Despite the advancements in primary brain tumour diagnoses and treatments, the mortality rate remains high, particularly in glioblastoma (GBM). Chemoresistance,...     

Expression and characterization of <Emphasis Type="Italic">Trichoderma virens</Emphasis> UKM-1 endochitinase in <Emphasis Type="Italic">Escherichia</Emphasis> <Emphasis Type="Italic">coli</Emphasis>

A gene encoding endochitinase from Trichoderma virens UKM-1 was cloned and expressed in E. coli BL21 (DE3). Both the endochitinase gene and its cDNA sequences were obtained. The endochitinase gene encodes 430 amino acids from an open reading frame comprising of 1,690 bp nucleotide sequence with three introns. The endochitinase was expressed as soluble and active enzyme at 20°C when induced with 1 mM IPTG. Maximum activity was observed at 4 h of post-induction time. SDS-PAGE showed that the purified endochitinase exhibited a single band with molecular weight of 42 kDa. Biochemical characterization of the enzyme displayed a near neutral pH characteristic with an optimum pH at 6.0 and optimum temperature at 50°C. The enzyme is stable between pH 3.0–7.0 and is able to retain its activity from 30 to 60°C. The presence of Mg²⁺ and Ca²⁺ ions increased the enzyme activity up to 20%. The purified enzyme has a strong affinity towards colloidal chitin and low effect on ethyl cellulose and D-cellubiose which are non-chitin related substrates. HPLC analysis from the chitin hydrolysis showed the release of (GlcNAc)₃, (GlcNAc)₂ and GlcNAc, in which (GlcNAc)₂ was the main product.     

Identification and Localization of a Rickettsia sp. in Bemisia tabaci (Homoptera: Aleyrodidae)

Whiteflies (Homoptera: Aleyrodidae) are sap-sucking insects that harbor “Candidatus Portiera aleyrodidarum,” an obligatory symbiotic bacterium which is housed in a special organ called the bacteriome. These insects are also home for a diverse facultative microbial community which may include Hamiltonella, Arsenophonus, Fritchea, Wolbachia, and Cardinium spp. In this study, the bacteria associated with a B biotype of the sweet potato whitefly Bemisia tabaci were characterized using molecular fingerprinting techniques, and a Rickettsia sp. was detected for the first time in this insect family. Rickettsia sp. distribution, transmission and localization were studied using PCR and fluorescence in situ hybridizations (FISH). Rickettsia was found in all 20 Israeli B. tabaci populations screened but not in all individuals within each population. A FISH analysis of B. tabaci eggs, nymphs, and adults revealed a unique concentration of Rickettsia around the gut and follicle cells, as well as a random distribution in the hemolymph. We postulate that the Rickettsia enters the oocyte together with the bacteriocytes, leaves these symbiont-housing cells when the egg is laid, multiplies and spreads throughout the egg during embryogenesis and, subsequently, disperses throughout the body of the hatching nymph, excluding the bacteriomes. Although the role Rickettsia plays in the biology of the whitefly is currently unknown, the vertical transmission on the one hand and the partial within-population infection on the other suggest a phenotype that is advantageous under certain conditions but may be deleterious enough to prevent fixation under others.     

Oral Ingestion of Transgenic RIDL Ae. aegypti Larvae Has No Negative Effect on Two Predator Toxorhynchites Species

Dengue is the most important mosquito-borne viral disease. No specific treatment or vaccine is currently available; traditional vector control methods can rarely achieve adequate control. Recently, the RIDL (Release of Insect carrying Dominant Lethality) approach has been developed, based on the sterile insect technique, in which genetically engineered ‘sterile’ homozygous RIDL male insects are released to mate wild females; the offspring inherit a copy of the RIDL construct and die. A RIDL strain of the dengue mosquito, Aedes aegypti, OX513A, expresses a fluorescent marker gene for identification (DsRed2) and a protein (tTAV) that causes the offspring to die. We examined whether these proteins could adversely affect predators that may feed on the insect. Aedes aegypti is a peri-domestic mosquito that typically breeds in small, rain-water-filled containers and has no specific predators. Toxorhynchites larvae feed on small aquatic organisms and are easily reared in the laboratory where they can be fed exclusively on mosquito larvae. To evaluate the effect of a predator feeding on a diet of RIDL insects, OX513A Ae. aegypti larvae were fed to two different species of Toxorhynchites (Tx. splendens and Tx. amboinensis) and effects on life table parameters of all life stages were compared to being fed on wild type larvae. No significant negative effect was observed on any life table parameter studied; this outcome and the benign nature of the expressed proteins (tTAV and DsRed2) indicate that Ae. aegypti OX513A RIDL strain is unlikely to have any adverse effects on predators in the environment.