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991.
NAADP as a second messenger: neither CD38 nor base-exchange reaction are necessary for in vivo generation of NAADP in myometrial cells 总被引:1,自引:0,他引:1
Soares S Thompson M White T Isbell A Yamasaki M Prakash Y Lund FE Galione A Chini EN 《American journal of physiology. Cell physiology》2007,292(1):C227-C239
Nicotinic acid adenine dinucleotide phosphate (NAADP) has recently been shown to act as a second messenger controlling intracellular Ca2+ responses in mammalian cells. Many questions remain regarding this signaling pathway, including the role of the ryanodine receptor (RyR) in NAADP-induced Ca2+ transients. Furthermore, the exact metabolic pathway responsible for the synthesis of NAADP in vivo has not been determined. Here, we demonstrate that the NAADP mediated Ca2+ release system is present in human myometrial cells. We also demonstrate that human myometrial cells use the NAADP second messenger system to generate intracellular Ca2+ transients in response to histamine. It has been proposed in the past that the NAADP system in mammalian cells is dependent on the presence of functional RyRs. Here, we observed that the histamine-induced Ca2+ transients are dependent on both the NAADP and inositol 1,4,5-trisphosphate signaling pathways but are independent of RyRs. The enzyme CD38 has been shown to catalyze the synthesis of NAADP in vitro by the base-exchange reaction. Furthermore, it has been proposed that this enzyme is responsible for the intracellular generation of NAADP in vivo. Using CD38 knockout mice, we observed that both the basal and histamine stimulated levels of NAADP are independent of CD38 and the base-exchange reaction. Our group is the first to demonstrate that NAADP is a second messenger for histamine-elicited Ca2+ transients in human myometrial cells. Furthermore, the NAADP mediated mechanism in mammalian cells can be independent of RyRs and CD38. Our data provides novel insights into the understanding of the mechanism of action and metabolism of this new second messenger system. cADP ribose; inositol 1,4,5-trisphosphate; endoplasmic reticulum; ryanodine channel; nicotinic acid adenine dinucleotide phosphate; CD38; base-exchange reaction 相似文献
992.
Molecular genetic improvement of cereals: transgenic wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) 总被引:4,自引:0,他引:4
Vasil IK 《Plant cell reports》2007,26(8):1133-1154
Only modest progress has been made in the molecular genetic improvement of wheat following the production of the first transgenic
plants in 1992, made possible by the development of efficient, long-term regenerable embryogenic cultures derived from immature
embryos and use of the biolistics method for the direct delivery of DNA into regenerable cells. Transgenic lines expressing
genes that confer resistance to environmentally friendly non-selective herbicides, and pests and pathogens have been produced,
in addition to lines with improved bread-making and nutritional qualities; some of these are ready for commercial production.
Reduction of losses caused by weeds, pests and pathogens in such plants not only indirectly increases available arable land
and fresh water supplies, but also conserves energy and natural resources. Nevertheless, the work carried out thus far can
be considered only the beginning, as many difficult tasks lie ahead and much remains to be done. The challenge now is to produce
higher-yielding varieties that are more nutritious, and are resistant or tolerant to a wide variety of biotic as well as abiotic
stresses (especially drought, salinity, heavy metal toxicity) that currently cause substantial losses in productivity. How
well we will meet this challenge for wheat, and indeed for other cereal and non-cereal crops, will depend largely on establishing
collaborative partnerships between breeders, molecular biologists, biotechnologists and industry, and on how effectively they
make use of the knowledge and insights gained from basic studies in plant biology and genetics, the sequencing of plant/cereal
genomes, the discovery of synteny in cereals, and the availability of DNA-based markers and increasingly detailed chromosomal
maps. 相似文献
993.
Behzadnia N Golas MM Hartmuth K Sander B Kastner B Deckert J Dube P Will CL Urlaub H Stark H Lührmann R 《The EMBO journal》2007,26(6):1737-1748
Little is known about the higher-order structure of prespliceosomal A complexes, in which pairing of the pre-mRNA's splice sites occurs. Here, human A complexes were isolated under physiological conditions by double-affinity selection. Purified complexes contained stoichiometric amounts of U1, U2 and pre-mRNA, and crosslinking studies indicated that these form concomitant base pairing interactions with one another. A complexes contained nearly all U1 and U2 proteins plus approximately 50 non-snRNP proteins. Unexpectedly, proteins of the hPrp19/CDC5 complex were also detected, even when A complexes were formed in the absence of U4/U6 snRNPs, demonstrating that they associate independent of the tri-snRNP. Double-affinity purification yielded structurally homogeneous A complexes as evidenced by electron microscopy, and allowed for the first time the generation of a three-dimensional structure. A complexes possess an asymmetric shape (approximately 260 x 200 x 195 angstroms) and contain a main body with various protruding elements, including a head-like domain and foot-like protrusions. Complexes isolated here are well suited for in vitro assembly studies to determine factor requirements for the A to B complex transition. 相似文献
994.
Santa Maria SR Gangavarapu V Johnson RE Prakash L Prakash S 《Molecular and cellular biology》2007,27(23):8409-8418
In Saccharomyces cerevisiae, postreplication repair (PRR) of UV-damaged DNA occurs by a Rad6-Rad18- and an Mms2-Ubc13-Rad5-dependent pathway or by a Rad52-dependent pathway. The Rad5 DNA helicase activity is specialized for promoting replication fork regression and template switching; previously, we suggested a role for the Rad5-dependent PRR pathway when the lesion is located on the leading strand and a role for the Rad52 pathway when the lesion is located on the lagging strand. In this study, we present evidence for the requirement of Nse1, a subunit of the Smc5-Smc6 complex, in Rad52-dependent PRR, and our genetic analyses suggest a role for the Nse1 and Mms21 E3 ligase activities associated with this complex in this repair mode. We discuss the possible ways by which the Smc5-Smc6 complex, including its associated ubiquitin ligase and SUMO ligase activities, might contribute to the Rad52-dependent nonrecombinational and recombinational modes of PRR. 相似文献
995.
Shreenath Prasad Anurag Misra Ved Prakash Jangir Abhishek Awasthi Jog Raj Tek Chand Bhalla 《World journal of microbiology & biotechnology》2007,23(3):345-353
Rhodococcus sp. NDB 1165, a nitrile-transforming organism was isolated from temperate forest soil of Himalayas. The nitrilase (EC 3.5.5.2)
activity of this organism had higher substrate specificity toward aromatic nitriles (benzonitrile, 3-cyanopyridine and 4-cyanopyridine)
and unsaturated aliphatic nitrile (acrylonitrile) in comparison to saturated aliphatic nitriles (acetonitrile, propionitrile,
butyronitrile and isobutyronitrile) nitrile and arylacetonitrile (phenylacetonitrile and indole-3-acetonitrile). The nitrilase
of Rhodococcus sp. NDB 1165 was inducible in nature and propionitrile proved to be an efficient inducer. However, the salts of ferrous and
cobalt ions had an inhibitory effect. Under optimized reaction conditions (pH 8.0 and temperature 45°C) the nitrilase activity
of this organism was 2.39 ± 0.07 U/mg dry cell mass (dcm). The half-life of this enzyme was 150 min and 40 min at 45°C and
50°C respectively. However, it was quite stable at 40°C and around 58 % activity was retained even after 6 h at this temperature.
The V
max and K
m value of this nitrilase were 1.67 μmol/ml min and 0.1 M respectively using 3-cyanopyridine as substrate. However, the decrease
in V
max and K
m values (0.56 μmol/ml min and 0.02 M, respectively) were ␣observed at >0.05 M 3-cyanopyridine which revealed that this enzyme
experienced uncompetitive inhibition at higher substrate concentrations. Under optimized reaction conditions, 1.6 M 3-cyanopyridine
was successfully converted in to nicotinic acid using 2.0 mg resting cells (dcm)/ml reaction mixture in 11 h. This is the
highest production of nicotinic acid i.e. 8.95 mg/mg resting cells (dcm)/h as compared to nitrilase systems reported hitherto. 相似文献
996.
Sodhi M Mukesh M Prakash B Mishra BP Sobti RC Singh KP Singh S Ahlawat SP 《Biochemical genetics》2007,45(1-2):145-153
The MspI allelic variation in intron III of the bovine growth hormone (bGH) gene was explored using PCR-RFLP in 750 animals
belonging to 17 well-recognized breeds of Indian zebu cattle (Bos indicus) reared in different geographic locations of the
country. Restriction digestion analysis of a 329-bp PCR fragment of the bGH intron III region with MspI restriction enzyme
revealed two alleles (MspI− and MspI+) and two genotypes (−/− and +/−) across the 17 cattle breeds studied. The allelic frequency
varied from 0.67 to 0.94 for MspI (−) and from 0.06 to 0.33 for MspI (+) across the 17 breeds, with a combined average frequency
of 0.87 and 0.13, respectively. No animal with +/+ genotype was detected across the samples analyzed. The chi-square test
showed that the difference in MspI allelic frequency was not significant (p > 0.05), regardless of the geographic origin,
coat color, or utility of the cattle breed. The high MspI (−) allele frequencies obtained for Indian zebu cattle in this study
are in sharp contrast to those reported for taurine breeds from northern Europe, Mediterranean countries, and America. Findings
of this study further substantiate the hypothesis that the MspI (−) allele has an Indian origin. 相似文献
997.
IRS-1 overexpression has been associated with breast cancer development, hormone independence and antiestrogen resistance. IRS-1 is a major downstream signaling protein for insulin and IGF1 receptors, conveying signals to PI-3K/Akt and ERK1/2 pathways. In estrogen-sensitive breast cancer cell lines, the widely used antiestrogen tamoxifen treatment reduces IRS-1 expression and function, thereby inhibiting IRS-1/PI-3K signaling. IRS-1 may serve as an alternative target to overexpressed IGF1R in breast cancer. While siRNA technology has become commonplace in many laboratories for in vitro gene knockdown studies, and in vivo stability issues are largely solved, its use in vivo is limited by an inability to efficiently and specifically deliver it to the intended site of action. We previously reported reduced survival of human MCF7 estrogen receptor positive breast cancer cells treated with a normal IRS1 siRNA delivered by a cationic lipid, plus an additive effect in combination with tamoxifen. We now report enhanced cellular uptake, relative to the unconjugated serum-stabilized IRS1 siRNA, of a serum-stabilized IRS1 siRNA conjugated with our previously characterized peptide mimetic of IGF1, D-(Cys-Ser-Lys-Cys), without the use of cationic lipids or electroporation, in MCF7 cells that overexpress IGF1R. Excess native IGF1 blocked uptake. An IRS1 siRNA cholesterol conjugate, targeted universally to cell membranes, was taken up by MCF7 cells as much as the peptide mimetic conjugate. IRS1 mRNA knockdown and IRS-1 protein knockdown were comparable for the IGF1 peptide and cholesterol conjugates. The unconjugated serum-stabilized IRS1 siRNA control showed negligible effects. Viability assays showed additive effects of siRNA treatment in combination with tamoxifen. In summary, we have taken the first step in converting an siRNA into a pharmacologically active agent for breast cancer. 相似文献
998.
999.
Ujjwal Layek Mrinmoy Midday Sourabh Bisui Arijit Kundu Prakash Karmakar 《Plant Species Biology》2022,37(4):278-293
Besides its importance as an ornamental plant, Justicia betonica L. is also used as a medicinal plant for the treatment of several human disorders. However, the population size and abundance of the plant species are very low in Indian states, including West Bengal. The breeding system and pollination ecology of J. betonica are still unclear. Therefore, some reproductive aspects were investigated in order to provide important information for the sustainability of the species. The flowering duration spanned from December to May, with its peak in February–March. Flower opening time was much earlier (5.00–8.00 a.m.) on a hot day (in April–May) than on a cold day (10.00 a.m.–12.00 p.m. in December–January). The time of anther dehiscence coincided with the flower opening time; however, the stigma became receptive later. The plant species is self-compatible but dependent on pollinators for fruit and seed sets. Members of different insect groups like ants, bees, butterflies, flies, moths and wasps visit the flowers. Among them, Allorhynchium metallicum and Halictus acrocephalus are the primary pollinators (based on the “relative pollinator service”). The plant species showed a significant pollination deficit (coefficient of pollination deficit [D] = 0.32) in the open condition. Larvae of the florivorous moth Gatesclarkeana erotias significantly reduced reproductive success by eating their floral parts, ovules and immature seeds. In conclusion, combining the pollination deficit and the feeding activity of phytophagous insects (moth larvae) may reduce the reproductive fitness of J. betonica in the study regions. 相似文献
1000.
Singh Neha Dev Indra Pal Saurabh Yadav Sanjeev Kumar Idris Mohammed M. Ansari Kausar Mahmood 《Molecular and cellular biochemistry》2022,477(5):1405-1416
Molecular and Cellular Biochemistry - Patulin (PAT) is a natural contaminant of fruits (primarily apples) and their products. Significantly, high levels of contamination have been found in fruit... 相似文献