Surface sterilization method for reducing microbial contamination of field grown strawberry explants intended for in vitro culture

An effective disinfection method for strawberry (Fragaria x ananassa Duch.) cv. Senga Sengana micropropagation using runner tips and nodal segments as explants was developed. The explants were surface sterilized with different sterilants for different durations. The present studies on the effect of different regimes of sterilization revealed that maximum aseptic cultures were obtained from both explants runner tips and nodal segments when treated with 1.5% sodium hypochlorite for 20 min plus ethyl alcohol 70% for 30 s, but the surviving percentage was less because this treatment resulted in necrosis and tissue injury of explants. However, mercuric chloride (0.1%) for 4 min resulted in less percentage of aseptic cultures but gave highest percentage of surviving explants as most of researchers have found that a single sterilant is more effective than the combination. Surface sterilization with mercuric chloride (0.1%) for 4 min was the optimum duration which resulted in highest percentage of explant survival.Keywords: In vitro, senga sengana, strawberry, sterilizationAfrican Journal of Biotechnology Vol. 12(39), pp. 5749-575

A Negative Feedback Loop That Limits the Ectopic Activation of a Cell Type–Specific Sporulation Sigma Factor of Bacillus subtilis

Two highly similar RNA polymerase sigma subunits, σF and σG, govern the early and late phases of forespore-specific gene expression during spore differentiation in Bacillus subtilis. σF drives synthesis of σG but the latter only becomes active once engulfment of the forespore by the mother cell is completed, its levels rising quickly due to a positive feedback loop. The mechanisms that prevent premature or ectopic activation of σG while discriminating between σF and σG in the forespore are not fully comprehended. Here, we report that the substitution of an asparagine by a glutamic acid at position 45 of σG (N45E) strongly reduced binding by a previously characterized anti-sigma factor, CsfB (also known as Gin), in vitro, and increased the activity of σG in vivo. The N45E mutation caused the appearance of a sub-population of pre-divisional cells with strong activity of σG. CsfB is normally produced in the forespore, under σF control, but sigGN45E mutant cells also expressed csfB and did so in a σG-dependent manner, autonomously from σF. Thus, a negative feedback loop involving CsfB counteracts the positive feedback loop resulting from ectopic σG activity. N45 is invariant in the homologous position of σG orthologues, whereas its functional equivalent in σF proteins, E39, is highly conserved. While CsfB does not bind to wild-type σF, a E39N substitution in σF resulted in efficient binding of CsfB to σF. Moreover, under certain conditions, the E39N alteration strongly restrains the activity of σF in vivo, in a csfB-dependent manner, and the efficiency of sporulation. Therefore, a single amino residue, N45/E39, is sufficient for the ability of CsfB to discriminate between the two forespore-specific sigma factors in B. subtilis

Longitudinal Analysis of the Temporal Evolution of Acinetobacter baumannii Strains in Ohio, USA, by Using Rapid Automated Typing Methods

Genotyping methods are essential to understand the transmission dynamics of Acinetobacter baumannii. We examined the representative genotypes of A. baumannii at different time periods in select locations in Ohio, using two rapid automated typing methods: PCR coupled with electrospray ionization mass spectrometry (PCR/ESI-MS), a form of multi-locus sequence typing (MLST), and repetitive-sequence-based-PCR (rep-PCR). Our analysis included 122 isolates from 4 referral hospital systems, in 2 urban areas of Ohio. These isolates were associated with outbreaks at 3 different time periods (1996, 2000 and 2005–2007). Type assignments of PCR/ESI-MS and rep-PCR were compared to each other and to worldwide (WW) clone types. The discriminatory power of each method was determined using the Simpson's index of diversity (DI). We observed that PCR/ESI-MS sequence type (ST) 14, corresponding to WW clone 3, predominated in 1996, whereas ST 12 and 14 co-existed in the intermediate period (2000) and ST 10 and 12, belonging to WW clone 2, predominated more recently in 2007. The shift from WW clone 3 to WW clone 2 was accompanied by an increase in carbapenem resistance. The DI was approximately 0.74 for PCR/ESI-MS, 0.88 for rep-PCR and 0.90 for the combination of both typing methods. We conclude that combining rapid automated typing methods such as PCR/ESI-MS and rep-PCR serves to optimally characterize the regional molecular epidemiology of A. baumannii. Our data also sheds light on the changing sequence types in an 11 year period in Northeast Ohio

Synthesis, characterization, and optoelectronic properties of phenothiazine-based organic co-poly-ynes

202209_bcwwAccepted ManuscriptRGCOthersBritish Petroleum, Oman; Ministry of Higher Education, Research and Innovation (MoHERI), Oman; Deputy for Research & Innovation, Deputy for Research & Innovation, Ministry of Education in Saudi Arabia; Hong Kong Polytechnic University; Research Institute for Smart Energy (RISE), Ms Clarea Au for the Endowed Professorship (847S) and the Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry; Changchun Institute of Applied Chemistry, Chinese Academy of Sciences; UK Research and Innovation Future Leaders Fellowship; Presidential Fellowship from the University of Manchester, UK; Engineering and Physical Sciences Research Council (EPSRC) (UK)Publishe