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981.
Nguyen Huy Thuan Ramesh Prasad Pandey Jae Kyung Sohng 《Applied microbiology and biotechnology》2014,98(18):7747-7759
Avermectins (AVMs), produced by Streptomyces avermitilis MA-4680 (or ATCC 31267, NRRL 8165, NCBIM 12804), are 16-member macrocylic lactones that play very important functions as bactericidal and antiparasitic agents against nematodes and anthropods, as well as Mycobacterium tuberculosis H37Rv. Since its discovery in 1975, use of AVM has been widely spreading around the globe. To date, the whole genome sequence of S. avermitilis K139 has been acquired, in which the AVM biosynthetic gene cluster was the most highly investigated to mine the genes responsible for functional as well as regulatory roles. Therefore, significant progress has been achieved for understanding and manipulating the biosynthesis, improved production, regulation mechanism, side effects, as well as the resistance of AVMs and their derivatives. These findings will facilitate further strain improvement and biosynthesis of novel derivatives bearing stable and improved biological activities, as well as overcoming the resistance mechanism to open up a bright period for these compounds. In this review, we have summarized and analyzed the update in advanced progress in biochemistry and biotechnological approaches used for the production of AVMs and their derivatives. 相似文献
982.
Guruprasad R. Ramesh Krishnan S. B. Dandin V. Girish Naik 《Trees - Structure and Function》2014,28(3):723-731
Key message
A strategy for effective utilization of RAPD marker data for sampling diverse entries was suggested and utilized for the development of mulberry core collection.Abstract
Mulberry (Morus spp.) is a perennial tree cultivated mainly for its foliage in sericulture industry and also known for its edible fruits, fodder, and valued timber. In recent years, mulberry cultivation is confronted with several abiotic and biotic stresses due to inimical climatic factors and this has necessitated the genetic improvement of the crop. Core collection is an efficient way of harnessing the trait variation and novel genes available in a natural gene pool for the development of improved elite lines. In this study, we analyzed 850 mulberry accessions assembled from 23 countries with separate sets of polymorphic RAPD markers along with a limited number of ISSR, SSR, and phenotypic markers. A total of 75 accessions were duplicated in 20 clusters among five natural groups. The limitations of the RAPD marker system like problem in cross gel comparison were tackled by adopting a novel “Groupwise sampling” approach. A mulberry core collection with 100 diverse entries was selected using maximization method implemented in MSTRAT software. The mean Dice dissimilarity coefficient computed from marker data was 0.308 among core entries. Indigenous and exotic entries were not discriminated in cluster and principal component analysis supporting the spread of mulberry far from the place of origin. Accessions belonging to two wild mulberry species from Andaman Islands and Himalayan region formed separate clusters indicating the geographical, reproductive, and taxonomic distinction. The identified core collection will be available for researchers for intensive mining of desirable alleles in mulberry improvement as well as in genome resequencing program. 相似文献983.
Amino acids, especially glutamine (GLN) have been known for many years to stimulate the growth of small intestinal mucosa. Polyamines are also required for optimal mucosal growth, and the inhibition of ornithine decarboxylase (ODC), the first rate-limiting enzyme in polyamine synthesis, blocks growth. Certain amino acids, primarily asparagine (ASN) and GLN stimulate ODC activity in a solution of physiological salts. More importantly, their presence is also required before growth factors and hormones such as epidermal growth factor and insulin are able to increase ODC activity. ODC activity is inhibited by antizyme-1 (AZ) whose synthesis is stimulated by polyamines, thus, providing a negative feedback regulation of the enzyme. In the absence of amino acids mammalian target of rapamycin complex 1 (mTORC1) is inhibited, whereas, mTORC2 is stimulated leading to the inhibition of global protein synthesis but increasing the synthesis of AZ via a cap-independent mechanism. These data, therefore, explain why ASN or GLN is essential for the activation of ODC. Interestingly, in a number of papers, AZ has been shown to inhibit cell proliferation, stimulate apoptosis, or increase autophagy. Each of these activities results in decreased cellular growth. AZ binds to and accelerates the degradation of ODC and other proteins shown to regulate proliferation and cell death, such as Aurora-A, Cyclin D1, and Smad1. The correlation between the stimulation of ODC activity and the absence of AZ as influenced by amino acids is high. Not only do amino acids such as ASN and GLN stimulate ODC while inhibiting AZ synthesis, but also amino acids such as lysine, valine, and ornithine, which inhibit ODC activity, increase the synthesis of AZ. The question remaining to be answered is whether AZ inhibits growth directly or whether it acts by decreasing the availability of polyamines to the dividing cells. In either case, evidence strongly suggests that the regulation of AZ synthesis is the mechanism through which amino acids influence the growth of intestinal mucosa. This brief article reviews the experiments leading to the information presented above. We also present evidence from the literature that AZ acts directly to inhibit cell proliferation and increase the rate of apoptosis. Finally, we discuss future experiments that will determine the role of AZ in the regulation of intestinal mucosal growth by amino acids. 相似文献
984.
Prakash Parajuli Ramesh Prasad Pandey Anaya Raj Pokhrel Gopal Prasad Ghimire Jae Kyung Sohng 《Glycoconjugate journal》2014,31(8):563-572
Mupirocin is a commercially available antibiotic that acts on bacterial isoleucyl-tRNA synthetase, thereby inhibiting protein synthesis and preventing bacterial infection. An in vitro glycosylation approach was applied to synthesize glycoside derivatives of mupirocin using different NDP-sugars and glycosyltransferase from Bacillus licheniformis. Ultra pressure liquid chromatography-photo diode array analyses of the reaction mixtures revealed the generation of product peak(s). The results were further supported by high-resolution quadruple time of flight electrospray ionization mass spectrometry analyses. The product purified from the reaction mixture with UDP-D-glucose was subjected to NMR analysis, and the structure was determined to be mupirocin 6-O-β-D-glucoside. Other glycoside analogs of mupirocin were determined based on high-resolution mass analyses. Antibacterial activity assays against Staphylococcus aureus demonstrated complete loss of antibacterial activity after glucosylation of mupirocin at the 6-hydroxyl position. 相似文献
985.
Oxidative stress is an important factor in causing aging and age-related diseases. It is caused by an imbalance between oxidants such as reactive oxygen species (ROS) and antioxidants. Protein oxidation elicited by free radicals may cause protein function disruptions. Protein carbonylation, an irreversible process resulting in loss of function of the modified proteins, is a widely used marker for oxidative stress. In the present study, we have evaluated the levels of protein carbonyls, ROS, and catalase in the cerebral hemispheres of young and aged mice. When aged mice were subjected to a dietary restriction (DR) regimen (alternate days feeding) of 3 months, a significant reduction in the endogenous levels of protein carbonylation as well as ROS and elevation of catalase was observed in their cerebral hemispheres. The present study, thus, demonstrated the antioxidative effects of late-onset DR regimen in the cerebral hemispheres of aged mice which may act as a powerful modulator of age-related neurodegenerative diseases. 相似文献
986.
Spencer C. H. Barrett Ramesh Arunkumar Stephen I. Wright 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2014,369(1648)
The evolution of self-fertilization from outcrossing has occurred on numerous occasions in flowering plants. This shift in mating system profoundly influences the morphology, ecology, genetics and evolution of selfing lineages. As a result, there has been sustained interest in understanding the mechanisms driving the evolution of selfing and its environmental context. Recently, patterns of molecular variation have been used to make inferences about the selective mechanisms associated with mating system transitions. However, these inferences can be complicated by the action of linked selection following the transition. Here, using multilocus simulations and comparative molecular data from related selfers and outcrossers, we demonstrate that there is little evidence for strong bottlenecks associated with initial transitions to selfing, and our simulation results cast doubt on whether it is possible to infer the role of bottlenecks associated with reproductive assurance in the evolution of selfing. They indicate that the effects of background selection on the loss of diversity and efficacy of selection occur rapidly following the shift to high selfing. Future comparative studies that integrate explicit ecological and genomic details are necessary for quantifying the independent and joint effects of selection and demography on transitions to selfing and the loss of genetic diversity. 相似文献
987.
Ramesh Prasad Pandey Prakash Parajuli Niranjan Koirala Joo Ho Lee Yong Il Park Jae Kyung Sohng 《Molecules and cells》2014,37(2):172-177
A glycosyltransferase, YjiC, from Bacillus licheniformis has been used for the modification of the commercially available isoflavonoids genistein, daidzein, biochanin A and formononetin. The in vitro glycosylation reaction, using UDP-α-D-glucose as a donor for the glucose moiety and aforementioned four acceptor molecules, showed the prominent glycosylation at 4′ and 7 hydroxyl groups, but not at the 5th hydroxyl group of the A-ring, resulting in the production of genistein 4′-O-β-D-glucoside, genistein 7-O-β-D-glucoside (genistin), genistein 4′,7-O-β-D-diglucoside, biochanin A-7-O-β-D-glucoside (sissotrin), daidzein 4′-O-β-D-glucoside, daidzein 7-O-β-D-glucoside (daidzin), daidzein 4′, 7-O-β-D-diglucoside, and formononetin 7-O-β-D-glucoside (ononin). The structures of all the products were elucidated using high performance liquid chromatography-photo diode array and high resolution quadrupole time-of-flight electrospray ionization mass spectrometry (HR QTOFESI/MS) analysis, and were compared with commercially available standard compounds. Significantly higher bioconversion rates of all four isoflavonoids was observed in both in vitro as well as in vivo bioconversion reactions. The in vivo fermentation of the isoflavonoids by applying engineered E. coli BL21(DE3)/ΔpgiΔzwfΔushA overexpressing phosphoglucomutase (pgm) and glucose 1-phosphate uridyltransferase (galU), along with YjiC, found more than 60% average conversion of 200 μM of supplemented isoflavonoids, without any additional UDP-α-D-glucose added in fermentation medium, which could be very beneficial to large scale industrial production of isoflavonoid glucosides. 相似文献
988.
Inhibition of constitutive nitric oxide (cNO) production inhibits SGLT1 activity by a reduction in the affinity for glucose without a change in Vmax in intestinal epithelial cells (IEC-18). Thus, we studied the intracellular pathway responsible for the posttranslational modification/s of SGLT1. NO is known to mediate its effects via cGMP which is diminished tenfold in L-NAME treated cells. Inhibition of cGMP production at the level of guanylyl cyclase or inhibition of protein kinase G also showed reduced SGLT1 activity demonstrating the involvement of PKG pathway in the regulation of SGLT1 activity. Metabolic labeling and immunoprecipitation with anti-SGLT1 specific antibodies did not show any significant changes in phosphorylation of SGLT1 protein. Tunicamycin to inhibit glycosylation reduced SGLT1 activity comparable to that seen with L-NAME treatment. The mechanism of inhibition was secondary to decreased affinity without a change in Vmax. Immunoblots of luminal membranes from tunicamycin treated or L-NAME treated IEC-18 cells showed a decrease in the apparent molecular size of SGLT1 protein to 62 and 67 kD, respectively suggesting an alteration in protein glycosylation. The deglycosylation assay with PNGase-F treatment reduced the apparent molecular size of the specific immunoreactive band of SGLT1 from control and L-NAME treated IEC-18 cells to approximately 62 kD from their original molecular size of 75 kD and 67 kD, respectively. Thus, the posttranslational mechanism responsible for the altered affinity of SGLT1 when cNO is diminished is secondary to altered glycosylation of SGLT1 protein. The intracellular pathway responsible for this alteration is cGMP and its dependent kinase. 相似文献
989.
990.
Lavanya Balakrishnan Raja Sekhar Nirujogi Sartaj Ahmad Mitali Bhattacharjee Srikanth S Manda Santosh Renuse Dhanashree S Kelkar Yashwanth Subbannayya Rajesh Raju Renu Goel Joji Kurian Thomas Navjyot Kaur Mukesh Dhillon Shantal Gupta Tankala Ramesh Jois Vivek Vasdev YL Ramachandra Nandini A Sahasrabuddhe TS Keshava Prasad Sujatha Mohan Harsha Gowda Subramanian Shankar Akhilesh Pandey 《Clinical proteomics》2014,11(1):6