Department of Biological Sciences
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Item Current Topics in Biotechnology & Microbiology(LAMBERT Academic Publishing, 2011) Jha, Prabhat N.Welcome to Current Topics in Biotechnology and Microbiology. This book provides the basics as well as new ideas in Biotechnology and Microbiology in a narrative and lucid style. The modern techniques employed in Nano-biotechnology, Genetic Engineering, Biotechnology and Microbiology are discussed in a comprehensive manner which will update the readers of Biotechnology and Microbiology field. This book is aimed to develop scientific and research skill along with the basic knowledge in the undergraduate and postgraduate students.Item Advances in Biotechnology: A Practical Approach (Biotechnology in Agriculture, Industry and Medicine)( Nova Science Publishers, 2013) Jha, Prabhat N.Biotechnology is the use of living organisms to enhance products, our lives and our environment. It is a broad and complex discipline that encompasses many specialised areas. The promise that biotechnology holds for developing countries is well recognised and it is an important tool that can be applied to diverse economic sectors with a focus on the production of food crops, livestock management, human health care, the chemical industry and environmental management. This book covers applications of biotechnology in selected areas such as health care, agriculture, microbial systems, "in silico" analysis for drug designing and drug discovery and the environmentItem RNA Interference: Biology, Mechanism, and Applications(ASM, 2003) Jha, Prabhat N.Double-stranded RNA-mediated interference (RNAi) is a simple and rapid method of silencing gene expression in a range of organisms. The silencing of a gene is a consequence of degradation of RNA into short RNAs that activate ribonucleases to target homologous mRNA. The resulting phenotypes either are identical to those of genetic null mutants or resemble an allelic series of mutants. Specific gene silencing has been shown to be related to two ancient processes, cosuppression in plants and quelling in fungi, and has also been associated with regulatory processes such as transposon silencing, antiviral defense mechanisms, gene regulation, and chromosomal modification. Extensive genetic and biochemical analysis revealed a two-step mechanism of RNAi-induced gene silencing. The first step involves degradation of dsRNA into small interfering RNAs (siRNAs), 21 to 25 nucleotides long, by an RNase III-like activity. In the second step, the siRNAs join an RNase complex, RISC (RNA-induced silencing complex), which acts on the cognate mRNA and degrades it. Several key components such as Dicer, RNA-dependent RNA polymerase, helicases, and dsRNA endonucleases have been identified in different organisms for their roles in RNAi. Some of these components also control the development of many organisms by processing many noncoding RNAs, called micro-RNAs. The biogenesis and function of micro-RNAs resemble RNAi activities to a large extent. Recent studies indicate that in the context of RNAi, the genome also undergoes alterations in the form of DNA methylation, heterochromatin formation, and programmed DNA elimination. As a result of these changes, the silencing effect of gene functions is exercised as tightly as possible. Because of its exquisite specificity and efficiency, RNAi is being considered as an important tool not only for functional genomics, but also for gene-specific therapeutic activities that target the mRNAs of disease-related genes.Item Plant–microbe partnerships for enhanced biodegradation of polychlorinated biphenyls. In Plant Microbe symbiosis- Applied facets(Springer, 2014) Jha, Prabhat N.Item Impact of Plant-Associated Microbial Communities on Host Plants Under Abiotic Stresses(Springer, 2019) Jha, Prabhat N.Item Protective role of certain chemicals against UV-B-induced damage in the nitrogen-fixing cyanobacterium, Nostoc muscorum.(Wiley, 2003) Jha, Prabhat N.Exposure of the N(2)-fixing cyanobacterium Anabaena BT2 to ultraviolet-B radiation (2.5 W m(-2)) for 30 min resulted in complete loss of nitrogenase activity but 100% cell killing occurred only after a 90-min exposure. Inactivation of nitrogenase activity was not specific to Anabaena BT2; other species also showed a similar effect. The time required for 100% killing and inactivation of nitrogenase activity differed in various species, and this difference may be ascribed to the presence of different levels of UV-B protection mechanisms in individual species. Inhibition of nitrogenase activity was immediate, since exposure of cultures to UV-B for as little as 5 min elicited some inhibition of activity. The activity of UV-B-inhibited nitrogenase did not recover upon transfer of exposed cells to fluorescent light, suggesting that the inhibition may be due to specific inactivation of the enzyme. By employment of inhibitors of protein synthesis and PS-II activity, it was demonstrated that restoration of nitrogenase activity in a UV-B-treated culture occurred by fresh synthesis of nitrogenase polypeptide. Our findings suggest that estimation of nitrogenase activity in diazotrophic species may be used as a marker enzyme for assessing the impact of UV-B radiation.Item Inactivation of Cyanobacterial Nitrogenase After Exposure to Ultraviolet-B Radiation(Springer, 2003) Jha, Prabhat N.Exposure of the N2-fixing cyanobacterium Anabaena BT2 to ultraviolet-B radiation (2.5 W m 2) for 30 min resulted in complete loss of nitrogenase activity but 100% cell killing occurred only after a 90-min exposure. Inactivation of nitrogenase activity was not specific to Anabaena BT2; other species also showed a similar effect. The time required for 100% killing and inactivation of nitrogenase activity differed in various species, and this difference may be ascribed to the presence of different levels of UV-B protection mechanisms in individual species. Inhibition of nitrogenase activity was immediate, since exposure of cultures to UV-B for as little as 5 min elicited some inhibition of activity. The activity of UV-B-inhibited nitrogenase did not recover upon transfer of exposed cells to fluorescent light, suggesting that the inhibition may be due to specific inactivation of the enzyme. By employment of inhibitors of protein synthesis and PS-II activity, it was demonstrated that restoration of nitrogenase activity in a UV-B-treated culture occurred by fresh synthesis of nitrogenase polypeptide. Our findings suggest that estimation of nitrogenase activity in diazotrophic species may be used as a marker enzyme for assessing the impact of UV-B radiation.Item Role of white light in reversing UV-B-mediated effects in the N2-fixing cyanobacterium Anabaena BT2(Elsiever, 2003) Jha, Prabhat N.The effects of various irradiances of artificial UV-B (280–315 nm) in the presence or absence of visible light (photosynthetically active radiation) on growth, survival, 14CO2 uptake and ribulose 1,5-bisphosphate carboxylase (RuBISCO) activity were studied in the N2-fixing cyanobacterium Anabaena BT2. We tested the hypothesis whether or not visible radiation offers any protection against UV-B-induced deleterious effects on growth and photosynthesis in Anabaena BT2. Attempts were also made to determine the irradiances of UV-B where inhibitory effects could be mitigated by simultaneous irradiation with visible light. Exposure of cultures to 0.2 W m−2 or higher irradiance of UV-B caused inhibition of growth and survival and growth ceased above 1.0 W m−2. 14CO2 uptake and RuBISCO activity were found to be more sensitive to UV-B and around 60% reduction in 14CO2 uptake and RuBISCO activity occurred after exposure of cultures to 0.4 W m−2 for 1 h. However, growth, 14CO2 uptake and RuBISCO activity were nearly normal when UV-B (0.4 W m−2) and visible light (14.4 W m−2) were given simultaneously. Blue radiation (450 nm) was found to be the most effective in photoreactivation against UV-B, better than UV-A or any other light wavelength band. Our results demonstrate that the studied cyanobacterium possesses active photoreactivation mechanism(s) against UV-B-mediated damage which in turn probably allow survival under natural conditions in spite of being continuously exposed to the UV-B component present in the solar radiation. Continued growth of many algae and cyanobacteria in the presence of intense solar UV-B radiation under natural conditions seems to be due to the active role of photoreactivation.Item Evidences showing ultraviolet-B radiation-induced damage of DNA in cyanobacteria and its detection by PCR assay(Elsiever, 2004) Jha, Prabhat N.Ultraviolet-B (UV-B) radiation is a biologically effective component of solar radiation which because of its absorption by important biomolecules such as nucleic acids, proteins, and lipids causes deleterious effects on biological systems [1], [2]. It has now been well documented that depletion of stratospheric ozone has led to an increase in the level of ultraviolet-B radiation (280–320 nm) reaching the earth’s surface [3], [4] and has caused a risk of exposure of living organisms on the Earth to this harmful radiation [1], [5], [6], [7], [8]. Several studies conducted under laboratory and natural conditions have revealed the harmful effects of UV-B radiation on growth, survival, motility, development, pigmentation, nutrient uptake, and various metabolic processes of cyanobacteria [2], [9]. These effects are in part due to the direct effect on membrane proteins, photosystem II, DNA, enzymes, growth regulators or due to indirect effect through the formation of reactive oxygen species. Amongst several targets of UV-B damage that have been identified, DNA and photosynthesis are recognized as the most predominant action sites [2], [6], [10]. Most of the information pertaining to induction of UV-induced DNA damage, their biological effects, and repair have been obtained by using short wavelength UV-C radiation (254 nm). In general during the course of UV irradiation, photons are absorbed by the DNA causing several types of damage involving single bases or interaction between adjacent bases or between DNA and protein [5], [10], [11], [12], [13]. The main class of UV-induced lesions consists of dimeric pyrimidine photoproducts which distort the DNA helix. These include cyclobutyl pyrimidine dimers arising from the cycloaddition of C5–C6 double bond of two adjacent pyrimidines and the pyrimidine (6-4) pyrimidone adducts which result from the addition of the 5′ end pyrimidine to the C4 carbonyl or imine group of the 3′ end pyrimidine [5], [12]. The latter are produced at a much slower rate but unlike the former cannot be excised and repaired by the usual photoreactivation mechanisms and thus they have the capacity for longer term damage. The dimers block the action of DNA polymerase and thereby prevent genome replication [14], [15], [16]. This may consequently lead to delayed cell division and growth inhibition and ultimately to death.Item Hepatotoxicity of Microcystis aeruginosa Strains Growing as Blooms in Certain Eutrophic Ponds(TUD, 2006) Jha, Prabhat N.; Kumar, AnilCritical assessment of five eutrophicated ponds of Varanasi city (India) revealed the presence of heavy blooms of cyanobacteria consisting mainly of Microcystis aeruginosa. Crude aqueous extracts of blooms as well as laboratory grown M. aeruginosa isolated from three ponds, namely Lakshmikund, Durgakund and Adityanagar showed toxicity in mouse bioassay test. Crude aqueous extracts from these samples caused death of test mice within 1h of administration (i.p.) with a LD50 of 60 mg/kg body weight and the treated animals showed clinical signs of hepatotoxicity. However such an effect was not associated with the blooms from Laatbhairov and Surajkund ponds suggesting that not all strains of M. aeruginosa are toxic. Based on spectral properties (?max 230 nm), and comparison with standard microcystin-LR, the toxin is tentatively identified as microcystin-LR. The purified toxin caused death of test mice within 40 min of its administration with a LD50 of 100 µg/ kg body weight and induced gross morphological and functional changes in liver. A 1.55 fold increase in liver weight accompanied by deep red coloration most probably due to hemorrhage and blood pooling suggested the hepatotoxic properties of the toxin. Hepatotoxicity was also evident from the drastic increase (up to 2.5 fold) in activity of serum enzymes such as glutamate pyruvate transaminase/alanine aminotransferase (GPT/ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (APase) following toxin treatment. ^14C-labelling experiments demonstrated maximum accumulation (~15%) of ^14C- toxin after 20 min. of toxin administration. Appreciable level of toxin was also detected in water of four ponds. In conclusion these results clearly demonstrate that microcystin-producing blooms of M. aeruginosa are common in eutrophicated ponds of Varanasi city but not all ponds harbour toxic blooms.