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51.
Genetic engineering of fluorescent pseudomonads for various industrially, agriculturally and environmentally important bioprocesses
often involves the use of suitable plasmids. Plasmid-mediated alterations in host physiology and metabolism are poorly understood
for this group of organisms. Thus, we investigated the metabolic perturbations in Pseudomonas fluorescens 13525 due to the independent and combined presence of broad-host-range plasmids, pBBR1MCS-2 (copy number 30) and pUCPM18
derived pAB4 and pAB8 (copy number 14-16). Presence of pAB4 and pAB8 not only significantly increased the growth rate and
glucose utilization of P. fluorescens 13525, but also increased glucose dehydrogenase activity and gluconic acid production indicating enhanced direct oxidative
pathway for glucose catabolism. Additionally, increased secretion of pyruvic, acetic, and citric acids caused faster media
acidification in presence of pAB4 and pAB8. Simultaneous presence of pAB4/pAB8 in Pf (pAB48) and pAB4/pBBR1MCS-2 in Pf (pAB4BBR1MCS-2) reduced their respective copy numbers to nearly half. Pf (pAB48) demonstrated further increase in direct oxidation pathway without altering growth and glucose depletion rates, as
compared with single transformants. Conversely, pBBR1MCS-2 plasmid did not greatly alter P. fluorescens 13525 metabolism when present independently but masked the effects imposed by pAB4 when present in its combination. In conclusion,
P. fluorescens 13525 redesigns its metabolism in response to the presence of plasmids irrespective of their nature, by enhancing anaplerosis
with a simultaneous reduction in catabolism as indicated by increased pyruvate carboxylase and decreased citrate synthase
activities, respectively. Such information will be helpful for vector designing during genetic engineering of fluorescent
pseudomonads. 相似文献
52.
Archana Aggarwal Man Mohan Misro Ankur Maheshwari Neeta Sehgal Deoki Nandan 《Molecular reproduction and development》2010,77(10):900-909
We have earlier reported that following persistent stimulation with hCG, oxidative stress‐induced apoptosis in rat Leydig cells was mainly achieved through the extrinsic pathway. In the present study, the role of N‐acetylcysteine (NAC) in counteracting the oxidative stress and the mechanisms of inhibition of apoptosis under such conditions were investigated. NAC (1 mM) intervention with repeated hCG stimulation (50 ng/ml, four times, each with 30 min challenge) prevented the decline in Leydig cell viability and the rise in lipid peroxidation and reactive oxygen species. Simultaneously, the activities of the enzymes glutathione‐S‐transferase, catalase, superoxide dismutase and the intracellular glutathione and antioxidant capacity of the treated cells improved significantly. Apoptotic markers Fas, FasL, and caspase‐8, up‐regulated following repeated hCG exposure, were significantly down‐regulated following NAC co‐incubation. While Bcl‐2 expression was fully restored, Bax and caspase‐9 remained unchanged. NAC treatment induced down‐regulation of upstream JNK/pJNK and down‐stream caspase‐3 in the target cells. Taken together, the above findings indicate that NAC counteracted the oxidative stress in Leydig cells induced as a result of repeated hCG stimulation, and inhibited apoptosis by mainly regulating the extrinsic and JNK pathways of metazoan apoptosis. Mol. Reprod. Dev. 77:900–909, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
53.
Archana Mathur Ajay Kumar Mathur Anita Gangwar Sharawan Yadav Priyanka Verma Rajender Singh Sangwan 《In vitro cellular & developmental biology. Plant》2010,46(1):13-21
A root-derived callus line of Panax sikkimensis that stably accumulates anthocyanins was established by small cell aggregate selection method. The selected line showed a
growth index of 221.36 and an anthocyanin content of 2.76 mg/g fw (7.076% dw) in 50–60 d of growth on a modified MS medium
containing 4.5 μM 2,4-dichlorophenoxy acetic acid and 1.2 μM kinetin under 16-h light and 8-h dark photoperiodic conditions.
Incubation under continuous light increased the growth index to 435.57 but led to a marginal dilution of anthocyanin content
to 2.192 mg/g fw (6.928% dw). The purple-red pigment had absorption maximum at 528 nm. The selected callus line has shown
sustained growth and productivity for more than 6 yr now. Interestingly, pigment accumulation in the selected line did not
hinder the ginsenoside production in the callus tissue (0.9–1.2% fw). 相似文献
54.
Soma Roy Kiranmayee Rao Ch. Bhuvaneswari Archana Giri Lakshmi Narasu Mangamoori 《World journal of microbiology & biotechnology》2010,26(1):85-91
The present study describes the phytochemical profile and antimicrobial activity of Andrographis paniculata. For the present investigation, two samples of A. paniculata extracts, obtained by extraction in chloroform and chloroform + HCl, respectively, were compared for their antimicrobial
activity and further subjected to GC-MS analysis to find out the nature of the compounds responsible for the antimicrobial
activity. The antibacterial activities were assessed by measuring the diameter of the inhibition zones, MIC and MBC values.
Compared to the chloroform + HCl extract, the chloroform extract showed better antimicrobial activity against all the nine
pathogenic bacterial strains tested. The chloroform extract was observed to be active against the opportunistic and pathogenic
gram-negative bacteria, indicating its potential application related to noscomial infections. GC-MS results revealed phenols,
aromatic carboxylic acids and esters in the chloroform extract to be the molecules responsible for the antimicrobial activity
of A. paniculata. This is the first report on analysis of antimicrobial components from A. paniculata, and our results confer the utility of this plant extract in developing a novel broad spectrum antimicrobial agent. 相似文献
55.
The “marine world” is endowed with diverse life forms. The life under the oceans is bestowed with a unique gene pool and characteristics
owing to extreme conditions such as high salt concentration and temperature variations. The marine biodiversity is an extremely
rich resource for the development of a wide array of applications in food, pharmaceuticals, cosmetics. Various forms of traditional
knowledge, including traditional medicinal knowledge, have been silently developing over the centuries, with the coastal tribes
in nations across the globe. Unfortunately, marine traditional knowledge has been underestimated both commercially and legally.
It has still not gained its due importance at the international platform for sustainable use and development. An attempt has
been made in the present study to collate information on marine traditional knowledge based medicine. Recent trends of marine
bioprospecting by various nations including India have been discussed, followed by the study of legal provisions dealing with
marine bioprospecting that aim at conservation and sustainable use of marine biodiversity and associated traditional knowledge.
Convention of Biological Diversity, United Nations Convention on the Law of the Seas and World Intellectual Property Organization
are the major international legal instruments that discuss the concepts of Prior Informed Consent, access and benefit sharing
with regard to biopiracy and provide guidelines and limits for conducting marine scientific research. 相似文献
56.
Archana Mathur Anita Gangwar Ajay K. Mathur Priyanka Verma Girish C. Uniyal Raj K. Lal 《Biotechnology letters》2010,32(3):457-461
A thin, profusely branched, fast growing hairy root line of Panax quinquefolium (American ginseng) was established by co-culturing epicotyl explants with a wild type strain of Agrobacterium rhizogenes. The transformed roots grew by over 10-fold from the initial inoculum within 8 weeks. The crude ginsenosides content in the roots was about 0.2 g/g dry wt level up to the 10th week of culture. Ginsenosides Rb2, Rd, Re, Rf and Rg1 constituted 47–49% of the crude saponin fraction between 6 and 8 weeks of growth whereas, Rc ginsenoside was accumulated only after 9th weeks when the biomass started receding. PCR amplification analysis of the hairy roots confirmed their transgenic nature by showing the presence of Ri-TL DNA with rolA, rolB and rolC genes in their genome. 相似文献
57.
Acetylcholine receptor gating at extracellular transmembrane domain interface: the cys-loop and M2-M3 linker
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Acetylcholine receptor channel gating is a propagated conformational cascade that links changes in structure and function at the transmitter binding sites in the extracellular domain (ECD) with those at a "gate" in the transmembrane domain (TMD). We used Phi-value analysis to probe the relative timing of the gating motions of alpha-subunit residues located near the ECD-TMD interface. Mutation of four of the seven amino acids in the M2-M3 linker (which connects the pore-lining M2 helix with the M3 helix), including three of the four residues in the core of the linker, changed the diliganded gating equilibrium constant (K(eq)) by up to 10,000-fold (P272 > I274 > A270 > G275). The average Phi-value for the whole linker was approximately 0.64. One interpretation of this result is that the gating motions of the M2-M3 linker are approximately synchronous with those of much of M2 (approximately 0.64), but occur after those of the transmitter binding site region (approximately 0.93) and loops 2 and 7 (approximately 0.77). We also examined mutants of six cys-loop residues (V132, T133, H134, F135, P136, and F137). Mutation of V132, H134, and F135 changed K(eq) by 2800-, 10-, and 18-fold, respectively, and with an average Phi-value of 0.74, similar to those of other cys-loop residues. Even though V132 and I274 are close, the energetic coupling between I and V mutants of these positions was small (< or =0.51 kcal mol(-1)). The M2-M3 linker appears to be the key moving part that couples gating motions at the base of the ECD with those in TMD. These interactions are distributed along an approximately 16-A border and involve about a dozen residues. 相似文献
58.
Cajanus cajan rhizobial isolates were found to be unable to utilize iron bound to ferrichrome, desferrioxamine B or rhodotorulic acid,
all being hydroxamate type siderophores. A broad host range expression vector containing the Escherichia
coli
fhuA gene, encoding the outer membrane receptor for Fe-ferrichrome, was constructed. The plasmid construct (pGR1), designed to
express fhuA under the lac promoter of E. coli, complemented E. coli MB97 ΔfhuA mutant for ferri-ferrichrome utilization and also allowed Rhizobium spp. ST1 and Rhizobium spp. IC3123 to grow using iron bound to ferrichrome. Sensitivity to the antibiotic albomycin, transported via the FhuA receptor,
was found in case of MB97 as well as rhizobial transformants harboring pGR1. The rhizobial transformants expressing fhuA showed growth stimulation when co-inoculated with Ustilago maydis, a fungal species known to produce ferrichrome under iron starved conditions. Growth stimulation was also observed in the
presence of externally supplied ferrichrome. The significance of these findings in terms of the potential for improving the
survivability of rhizobial bioinoculant strains in natural soils is discussed. 相似文献
59.
Caloric restriction and genomic stability 总被引:1,自引:0,他引:1
Caloric restriction (CR) reduces the incidence and progression of spontaneous and induced tumors in laboratory rodents while increasing mean and maximum life spans. It has been suggested that CR extends longevity and reduces age-related pathologies by reducing the levels of DNA damage and mutations that accumulate with age. This hypothesis is attractive because the integrity of the genome is essential to a cell/organism and because it is supported by observations that both cancer and immunological defects, which increase significantly with age and are delayed by CR, are associated with changes in DNA damage and/or DNA repair. Over the last three decades, numerous laboratories have examined the effects of CR on the integrity of the genome and the ability of cells to repair DNA. The majority of studies performed indicate that the age-related increase in oxidative damage to DNA is significantly reduced by CR. Early studies suggest that CR reduces DNA damage by enhancing DNA repair. With the advent of genomic technology and our increased understanding of specific repair pathways, CR has been shown to have a significant effect on major DNA repair pathways, such as NER, BER and double-strand break repair. 相似文献
60.
A unique and highly efficient non-viral DNA/siRNA delivery system based on PEI-bisepoxide nanoparticles 总被引:2,自引:0,他引:2
Swami A Kurupati RK Pathak A Singh Y Kumar P Gupta KC 《Biochemical and biophysical research communications》2007,362(4):835-841
Delivery of DNA and siRNA into mammalian cells is a powerful technique in treating various diseases caused by single gene defects. Herein, we report a highly efficient delivery system using 1,4-butanediol diglycidyl ether (bisepoxide) crosslinked polyethylenimine (PEI) nanoparticles (PN). The nanoparticle/DNA complexes (nanoplexes) exibited approximately 2.5- to 5.0-fold gene transfer efficacy and decreased cytotoxicity in cultured cell lines, compared to the native PEI (25 kDa) (gold standard) and commercially available transfection agents such as Lipofectamine 2000 and Fugene. The bisepoxide crosslinking results in change in amine ratio in PEI; however, it retains the net charge on PN unaltered. A series of nanoparticles obtained by varying the degree of crosslinking was found to be in the size range of 69-77 nm and the zeta potential varying from +35 to 40 mV. The proposed system was also found to deliver siRNA efficiently into HEK cells, resulting in approximately 70% suppression of the targetted gene (GFP). 相似文献