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81.
Matteo Capone Daniele Narzi Aliya Tychengulova Leonardo Guidoni 《Physiologia plantarum》2019,166(1):33-43
Understanding the structural modification experienced by the Mn4CaO5 oxygen‐evolving complex of photosystem II along the Kok‐Joliot's cycle has been a challenge for both theory and experiments since many decades. In particular, differential infrared spectroscopy was extensively used to probe the surroundings of the reaction center, to catch spectral changes between different S‐states along the catalytic cycle. Because of the complexity of the signals, only a limited quantity of identified peaks have been assigned so far, also because of the difficulty of a direct comparison with theoretical calculations. In the present work, we critically reconsider the comparison between differential vibrational spectroscopy and theoretical calculations performed on the structural models of the photosystem II active site and an inorganic structural mimic. Several factors are currently limiting the reliability of a quantitative comparison, such as intrinsic errors associated to theoretical methods, and most of all, the uncertainty attributed to the lack of knowledge about the localization of the underlying structural changes. Critical points in this comparison are extensively discussed. Comparing several computational data of differential S2/S1 infrared spectroscopy, we have identified weak and strong points in their interpretation when compared with experimental spectra. 相似文献
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83.
为探讨西北干旱区森林土壤螨类群落和环境因子的相互关系,于2014年对新疆天山森林公园七种不同生境进行土壤螨类群落调查与环境因子测定,并采用除趋势对应分析法(DCA)和冗余分析法(RDA)对土壤螨类群落结构和多样性特征及其与环境因子之间的关系进行相关分析。结果表明,共捕获土壤螨类成体标本24399只,隶属4目56科108属(包括9个中国新记录属),其中小甲螨属Oribatella为优势类群。方差分析表明,在7种不同生境之间土壤螨类群落多样性指标均存在显著差异(P<0.05),Shannon-Wiener多样性指数(H)依次为针叶林>苗圃林>阔叶林>灌木林>针阔混交林>草甸草原>林中草地。RDA分析结果表明,第一主轴和第二主轴分别解释了土壤螨类主要群落总变量的34.8%和27.3%,所有环境因子共解释了土壤螨类群落物种组成变异的82.1%。蒙特卡罗置换检验显示,十种环境因子与全部排序轴(F=7.355,P=0.002)均存在极显著的相关性。研究表明,海拔、土壤含水量和有机质含量对螨类群落结构和多样性的影响显著。 相似文献
84.
K. Alpaa V. Gopi S. Aliya B. Sreenivasulu K. Purushotham 《Archives Of Phytopathology And Plant Protection》2013,46(7):624-633
Citrus is an important fruit crop having divergent genetic variation within the species. The germplasm identification and characterisation is an important link between the conservation and utilisation of genetic resources. Conventionally, variety/clone identification has relied on morphological characters such as growth habit, leaf, floral and fruit characters etc. Investigation through RAPD (random amplified polymorphic DNA) markers was carried out for determination of genetic variation among 12 acid lime clones having varied resistance to bacterial canker disease. DNA was extracted from the leaf of 12 acid lime clones and was subjected to PCR using 20 random primers (nine from OPM and 11 from OPA series) which yielded a total of 127 distinct DNA fragments, out of which 103 were polymorphic. Genetic similarity was evaluated based on the presence or absence of bands. The bands obtained were polymorphic, with sizes ranging from 750 bp to 2.5 kb. Cluster analysis using the similarity coefficient showed that the Balaji, RHRL-124 and PKM-1 formed one cluster and the remaining clones formed a second cluster, which in turn were divided into TAL 94-9, TAL 94-10, TAL 94-11 and TAL 94-12 which formed the first subcluster; the Nalgonda selection and local acid lime formed a second subcluster; TAL 94-8, RHRL-49 and RHRL-122 did not resemble any other clones. Among the 12 acid lime clones, Balaji, RHRL-124, RHRL-122 and PKM-1 were found to be moderately resistant to bacterial canker. Correlation of RAPD data with canker disease incidence in the moderately resistant acid lime clones viz., Balaji, RHRL-124 and PKM-1 were formed as one cluster, and all susceptible clones formed as a second cluster viz., except TAL-94-9, RHRL-122, which were found to be moderately resistant and did not form a cluster with any other acid lime clone. 相似文献
85.
T A Lyle R M Freidinger R F Nutt C F Homnick R Saperstein D F Veber 《International journal of peptide and protein research》1987,29(2):244-249
A possible benefit of creating smaller and more rigid active analogs of somatostatin is the discovery of compounds which selectively inhibit the secretion of insulin, glucagon or growth hormone. A series of cyclic tetrapeptide analogs related to somatostatin was synthesized, and one member of this series was found to cause an unexpected stimulation of glucagon secretion while having little if any effect on either insulin or growth hormone secretion. A sustained increase in plasma glucose levels was also observed. Two possible modes of action are proposed. 相似文献
86.
87.
Daniel F. Veber Richard Saperstein Ruth F. Nutt Roger M. Freidinger Stephen F. Brady Paul Curley Debra S. Perlow William J. Paleveda C.Dylion Colton Anthony G. Zacchei Dominick J. Tocco Dale R. Hoff Richard L. Vandlen John E. Gerich Larry Hall Lawrence Mandarino Eugene H. Cordes Paul S. Anderson Ralph Hirschmann 《Life sciences》1984,34(14):1371-1378
The cyclic hexapeptide, cyclo (Pro-Phe-D-Trp-Lys-Thr-Phe), I, has been shown to have the biological properties of somatostatin. We now report structure-activity studies which optimize the potency of this cyclic hexapeptide series with the synthesis of cyclo (N-Me-Ala-Tyr-D-Trp-Lys-Val-Phe), II, which is 50–100 times more potent than somatostatin for the inhibition of insulin, glucagon and growth hormone release. The hydroxyl group of tyrosine is seen to lend a 10-fold enhancement to the potency. Potency also is found to be correlated with hydrophobicity. II is found to improve the control of postprandial hyperglycemia in diabetic animals when given in combination with insulin. The analog is found to be quite stable in the blood and in the gastrointestinal tract, but the bioavailability after oral administration is only 1–3%. The biological properties and long duration of II should allow clinical evaluation of the inhibition of glucagon release as an adjunct to insulin in the treatment of patients with diabetes. 相似文献
88.
Aliya El Nagar Matthew McHugh Toby Rapp David W. Sims Martin J. Genner 《Conservation Genetics》2010,11(3):1203-1206
Simple sequence repeat markers (SSRs, microsatellites) were characterised for skates (Elasmobranchii: Rajidae) from published
expressed sequence tags (ESTs) of Leucoraja erinacea. These were tested in four European species (Raja clavata, Raja montagui, Dipturus batis, and Leucoraja naevus). Thirteen of the fourteen amplified loci were polymorphic in at least one species. Polymorphic loci possessed on average
4.5–5.9 alleles per species, and expected heterozygosity ranged from 0.05 to 0.88. Possible null alleles were detected at
three loci, while one locus showed significant deviation from Hardy–Weinberg Equilibrium proportions. Three locus-pairs exhibited
significant linkage disequilibrium in one or more species. This marker set will be valuable for population genetic analyses
of the focal taxa, and may prove useful for studies of other skate species. 相似文献
89.
Amal K. Halder Emily S. Gurley Aliya Naheed Samir K. Saha W. Abdullah Brooks Shams El Arifeen Hossain M. S. Sazzad Eben Kenah Stephen P. Luby 《PloS one》2009,4(12)
Data on causes of early childhood death from low-income urban areas are limited. The nationally representative Bangladesh Demographic and Health Survey 2007 estimates 65 children died per 1,000 live births. We investigated rates and causes of under-five deaths in an urban community near two large pediatric hospitals in Dhaka, Bangladesh and evaluated the impact of different recall periods. We conducted a survey in 2006 for 6971 households and a follow up survey in 2007 among eligible remaining households or replacement households. The initial survey collected information for all children under five years old who died in the previous year; the follow up survey on child deaths in the preceding five years. We compared mortality rates based on 1-year recall to the 4 years preceding the most recent 1 year. The initial survey identified 58 deaths among children <5 years in the preceding year. The follow up survey identified a mean 53 deaths per year in the preceding five years (SD±7.3). Under-five mortality rate was 34 and neonatal mortality was 15 per thousand live births during 2006–2007. The leading cause of under-five death was respiratory infections (22%). The mortality rates among children under 4 years old for the two time periods (most recent 1-year recall and the 4 years preceding the most recent 1 year) were similar (36 versus 32). The child mortality in urban Dhaka was substantially lower than the national rate. Mortality rates were not affected by recall periods between 1 and 5 years. 相似文献
90.
Aliya Fatehullah Paul L. Appleton Inke S. N?thke 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2013,368(1629)
Cell and tissue polarity are tightly coupled and are vital for normal tissue homeostasis. Changes in cellular and tissue organization are common to even early stages of disease, particularly cancer. The digestive tract is the site of the second most common cause of cancer deaths in the developed world. Tumours in this tissue arise in an epithelium that has a number of axes of cell and tissue polarity. Changes in cell and tissue polarity in response to genetic changes that are known to underpin disease progression provide clues about the link between molecular-, cellular- and tissue-based mechanisms that accompany cancer. Mutations in adenomatous polyposis coli (APC) are common to most colorectal cancers in humans and are sufficient to cause tumours in mouse intestine. Tissue organoids mimic many features of whole tissue and permit identifying changes at different times after inactivation of APC. Using gut organoids, we show that tissue polarity is lost very early during cancer progression, whereas cell polarity, at least apical–basal polarity, is maintained and changes only at later stages. These observations reflect the situation in tumours and validate tissue organoids as a useful system to investigate the relationship between cell polarity and tissue organization. 相似文献