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991.
Morphological and molecular characterization of free-floating and attached green macroalgae Ulva spp. in the Yellow Sea of China 总被引:5,自引:0,他引:5
Weijun Duan Lixin Guo Dong Sun Shuifang Zhu Xianfeng Chen Wenrong Zhu Tao Xu Changfa Chen 《Journal of applied phycology》2012,24(1):97-108
During the summer of 2008 and 2009, massive algal blooms repeatedly broke out in the Yellow Sea of China. These were undoubtedly
caused by the accumulations of one or more species in the macroalgal genus Ulva. In previous reports, morphological observation indicated that the species involved in this phenomenon is Ulva prolifera but molecular analyses indicated that the species belongs to an Ulva linza–procera–prolifera (LPP) clade. Correct identification of the bloom species is required to understand and manage the blooms, but the taxonomic
status of the bloom species remains unclear. In the current study, the taxonomic status of 22 selected specimens from the
Yellow Sea was assessed by using both morphological and molecular (ITS and rbcL sequences) data. In addition, 5S rDNA analyses
were performed for those samples clustering in the LPP clade, and phylogenetic tree and ribotype analyses were constructed
for determining the possible origin of the bloom. Three free-floating and two attached Ulva species were distinguished and described: Ulva compressa Linnaeus and Ulva pertusa Kjellman were found in free-floating samples; U. linza Linnaeus was found on rocks; and U. prolifera O.F. Müller was found in both habitats. Diversity in free-floating Ulva of the Yellow Sea appears to be greater than previously thought. The dominant free-floating Ulva species, U. prolifera, was not closely related to local populations attached to rocks but was closely related to populations from Japan. 相似文献
992.
The after-harvesting sun-dried processing of Fritillariae thunbergii bulbus (Zhebeimu) was the traditional treatment for commodity. Over recent decades the natural drying process for bulbus of Fritillariae has been replaced by sulfur-fumigation for reducing the drying duration and pest control. We used ultra-performance liquid chromatography coupled with evaporative light scattering detection (UPLC-ELSD) fingerprinting analysis and major alkaloids determination to investigate the potential damaging effect of the sulfur-fumigating process. The experimental conditions were as follows: Chromatography was proceeded on Waters Acquity UPLC BEH C(18) column; the linear gradient elution was conducted with mobile phase prepared from acetonitrile-0.02% triethylamine; the drift tube temperature was set at 40°C with a nitrogen flow-rate of 30psi, and the spray parameter was set 40%. All calibration curves showed good linear regression (R>0.9991) within the tested range. The method was validated for precision, accuracy, limit of detection and quantification. The study also has shown that sulfur-fumigated samples had significant loss of the main active compounds and a more destructive fingerprint profile when compared to the sun-dried samples. 相似文献
993.
Huiling Wu Xiaoli Wu Zhaohu Li Liusheng Duan Mingcai Zhang 《Journal of Plant Growth Regulation》2012,31(1):113-123
Coronatine (COR) is a chlorosis-inducing phytotoxin that mimics some biological activities of methyl jasmonate (MeJA). Although
MeJA has been reported to alleviate drought stress, it is unclear if COR has the same ability. Our objective was to determine
the influence of exogenously applied MeJA and COR on the growth and metabolism of cauliflower seedlings under drought stress
and recovery. Both MeJA and COR enhanced the growth and accumulation of dry matter in cauliflower seedlings during drought-stressed
and rewatering conditions. Treatment with MeJA or COR enhanced tolerance of drought stress through increased accumulation
of chlorophyll and net photosynthetic rate. Enzymatic (superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, and
glutathione reductase) and nonenzymatic antioxidant (proline and soluble sugar) systems were activated, and lipid peroxidant
(malondialdehyde and hydrogen peroxide) was suppressed by MeJA and COR under drought stress. MeJA and COR also increased leaf
relative water content and endogenous abscisic acid level under drought-stressed conditions. After rewatering, the contents
of leaf water, chlorophyll, abscisic acid, and photosynthetic characteristics as well as enzymatic and nonenzymatic antioxidant
systems showed nearly complete recovery. Both MeJA and COR can alleviate the adverse effects of drought stress and enhance
the ability for water stress resistance through promotion of defense-related metabolism in cauliflower seedlings. 相似文献
994.
Kar3 kinesins are microtubule (MT) minus‐end‐directed motors with pleiotropic functions in mitotic spindle formation and nuclear movement in budding and fission yeasts. A Kar3‐like kinesin is also expressed by the filamentous fungus Ashbya gossypi, which exhibits different nuclear movement challenges from its yeast relatives. Presented here is a 2.35 Å crystal structure and enzymatic analysis of the AgKar3 motor domain (AgKar3MD). Compared to the previously published Saccharomyces cerevisiae Kar3MD structure (ScKar3MD), AgKar3MD displays differences in the conformation of some of its nucleotide‐binding motifs and peripheral elements. Unlike ScKar3MD, the salt bridge between Switch I and Switch II in AgKar3MD is broken. Most of the Switch I, and the adjoining region of helix α3, are also disordered instead of bending into the active site cleft as is observed in ScKar3MD. These aspects of AgKar3MD are highly reminiscent of the ScKar3 R598A mutant that disrupts the Switch I–Switch II salt bridge and impairs MT‐stimulated ATPase activity of the motor. Subtle differences in the disposition of secondary structure elements in the small lobe (β1a, β1b, and β1c) at the edge of the MD are also apparent even though it contains approximately the same number of residues as ScKar3. These differences may reflect the unique enzymatic properties we measured for this motor, which include a lower MT‐stimulated ATPase rate relative to ScKar3, or they could relate to its interactions with different regulatory companion proteins than its budding yeast counterpart. Proteins 2011;. © 2011 Wiley Periodicals, Inc. 相似文献
995.
Quick M Yano H Goldberg NR Duan L Beuming T Shi L Weinstein H Javitch JA 《The Journal of biological chemistry》2006,281(36):26444-26454
The gene of a novel prokaryotic member (Tyt1) of the neurotransmitter:sodium symporter (NSS) family has been cloned from Fusobacterium nucleatum. In contrast to eukaryotic and some prokaryotic NSSs, which contain 12 transmembrane domains (TMs), Tyt1 contains only 11 TMs, a characteristic shared by approximately 70% of prokaryotic NSS homologues. Nonetheless upon heterologous expression in an engineered Escherichia coli host, Tyt1 catalyzes robust Na+-dependent, highly selective l-tyrosine transport. Genetic engineering of Tyt1 variants devoid of cysteines or with individually retained endogenous cysteines at positions 18 or 238, at the cytoplasmic ends of TM1 and TM6, respectively, preserved normal transport activity. Whereas cysteine-less Tyt1 was resistant to the inhibitory effect of sulfhydryl-alkylating reagents, N-ethylmaleimide inhibited transport by Tyt1 variants containing either one or both of the endogenous cysteines, and this inhibition was altered by the substrates sodium and tyrosine, consistent with substrate-induced dynamics in the transport pathway. Our findings support a binding model of Tyt1 function in which an ordered sequence of substrate-induced structural changes reflects distinct conformational states of the transporter. This work identifies Tyt1 as the first functional bacterial NSS member putatively consisting of only 11 TMs and shows that Tyt1 is a suitable model for the study of NSS dynamics with relevance to structure/function relationships of human NSSs, including the dopamine, norepinephrine, serotonin, and gamma-aminobutyric acid transporters. 相似文献
996.
Dendritic cells (DC) are highly specialized antigen presenting cells that play critical roles as instigators and regulators of immune responses including B cell function, antibody synthesis and isotype switch. In this study, we compared immunotherapeutic effect of IL-10-treated DC (IL-10-DC) via both intraperitoneal (i.p.) and subcutaneous (s.c.) delivery in rats with incipient experimental autoimmune myasthenia gravis (EAMG). Spleen DC were isolated from onset of EAMG on day 39 post-immunization, exposed in vitro to IL-10, and then injected into incipient EAMG at dose of 1 x 10(6) cells/rat on day 5 after immunization. Intraperitoneal administration of IL-10-DC suppressed clinical scores, anti-acetylcholine receptors (AChR) antibody secreting cells, antigen-specific IL-10/IFN-gamma production and T cell proliferation compared to control EAMG rats. Importantly, IL-10-DC, if given by s.c. route, failed to ameliorate clinical sign of EAMG. Simultaneously, T cell proliferation, anti-AChR antibody secreting cells and IL-10/IFN-gamma production had no alteration, as compared to control EAMG rats. Both in vitro and in vivo experiments showed that treatment of IL-10 inhibited the migration of DC toward MIP-3beta and lymph node, indicating that in vitro manipulation of DC with IL-10 alters the migration of DC that influences the therapeutic effect in the treatment of autoimmune diseases. In MG patients, neither the improvement of clinical symptom nor the alteration of immunological parameter was observed through s.c. delivery of IL-10-DC, suggesting the limitation of IL-10-DC in the treatment of MG patients. 相似文献
997.
998.
Structure and function of glucose-6-phosphate dehydrogenase-deficient variants in Chinese population 总被引:9,自引:0,他引:9
Jiang W Yu G Liu P Geng Q Chen L Lin Q Ren X Ye W He Y Guo Y Duan S Wen J Li H Qi Y Jiang C Zheng Y Liu C Si E Zhang Q Tian Q Du C 《Human genetics》2006,119(5):463-478
A systematic study on the structure and function of Glucose-6-phosphate dehydrogenase (G6PD) variations was carried out in China. A total of 155,879 participants were screened for G6PD deficiency by the G6PD/6PGD ratio method and 6,683 cases have been found. The prevalence of G6PD deficiency ranged from 0 to 17.4%. With informed consent, 1,004 cases from 11 ethnic-based groups were subjected to molecular analysis. Our results showed the followings: (1) The G6PD variants are consistent across traditional ethnic boundaries, but vary in frequencies across ethnic-based groups in Chinese population, (2) The G6PD variants in Chinese population are different from those in African, European, and Indian populations, (3) A novel G6PD-deficiency mutation, 274C→T, has been found, and (4) Denaturing high performance liquid chromatography is of great advantage to detecting G6PD-deficient mutations for diagnosis and genetic counseling. Moreover, functional analysis of the human G6PD variants showed the following: (1) The charge property, polarity, pK-radical and side-chain radical of the substituting amino acid have an effect on G6PD activity, (2) The G6PDArg459 and Arg463 play important roles in anchoring NADP+ to the catalytic domain to maintain the enzymatic activity, and (3) The sequence from codon 459 to the carboxyl terminal is essential for the enzymatic function. 相似文献
999.
A method to deduce RNA secondary structure on the basis of data from microarrays of 2'-O-methyl RNA 9-mers immobilized in agarose film on glass slides is tested with a 249 nucleotide RNA from the 3' end of the R2 retrotransposon from Bombyx mori. Various algorithms incorporating binding data and free-energy minimization calculations were compared for interpreting the data to provide possible secondary structures. Two different methods give structures with 100 and 87% of the base pairs determined by sequence comparison. In contrast, structures predicted by free-energy minimization alone by Mfold and RNAstructure contain 52 and 72% of the known base pairs, respectively. This combination of high throughput microarray techniques with algorithms using free-energy calculations has potential to allow for fast determination of RNA secondary structure. It should also facilitate the design of antisense and siRNA oligonucleotides. 相似文献
1000.
Duan RD 《Biochimica et biophysica acta》2006,1761(3):281-291
Alkaline sphingomyelinase (alk-SMase) is present in the intestinal tract and additionally human bile. It hydrolyses sphingomyelin in both intestinal lumen and the mucosal membrane in a specific bile salt dependent manner. The enzyme was discovered 36 years ago but got real attention only in the last decade, when sphingomyelin metabolism was realized to be a source of multiple lipid messengers, and when dietary sphingomyelin was found to inhibit colonic tumorigenesis in animals. The enzyme shares no structural similarity with other SMases and belongs to the nucleotide pyrophosphatase/phosphodiesterase family. The enzyme is of specific properties, such as bile salt dependency, trypsin resistance, high stability, and tissue specific expression. In the colon, the enzyme may play antiproliferative and antiinflammatory roles through generating ceramide, reducing the formation of lysophosphatidic acid, and inactivating platelet-activating factor. The enzyme is down regulated in human long-standing ulcerative colitis and colonic adenocarcinoma, and mutation of the enzyme has been found in colon cancer cells. In the small intestine, alk-SMase is the key enzyme for sphingomyelin digestion. The hydrolysis of sphingomyelin may affect the cholesterol uptake and have impact on sphingomyelin levels in plasma lipoproteins. The review summarizes the new information of alk-SMase from biochemical, cell and molecular biological studies in the last decade and evaluates its potential implications in development of colon cancer, inflammatory bowel diseases, and atherosclerosis. 相似文献