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排序方式: 共有154条查询结果,搜索用时 9 毫秒
101.
Seasonal changes in the levels of compatible osmolytes in three halophytic species of inland saline vegetation in Hungary 总被引:3,自引:0,他引:3
Seasonal changes in the leaf concentration of compatible osmolytes were investigated in three halophytic species (Lepidium crassifolium, Camphorosma annua and Limonium gmelini subsp. hungaricum) native to a salty-sodic grassland. The investigated species were shown to accumulate both carbohydrate- and amino acid-derived osmolytes. The leaf tissues of C. annua (Chenopodiaceae) preferentially stored glycine betaine and pinitol, while in L. gmelini (Plumbaginaceae) beta-alanine betaine, choline-O-sulphate, and pinitol were accumulated. In the leaves of L. crassifolium (Brassicaceae) a very high amount of proline, associated with a high level of soluble carbohydrates was found. Not only the biochemical nature of the osmolyte, but also the seasonal pattern of osmolyte accumulation showed significant species-specific fluctuations. In addition, the cellular levels of the observed osmolytes changed with the growth period and according to the environmental parameters. The highest concentrations of osmolytes were found in March, when low temperatures, hypoxic conditions and high salt concentrations were the main constraints to plant growth. The high structural diversity of osmolytes combined with their multifunctionality and the seasonal flexibility of the metabolism in plants facing multiple stresses is discussed. 相似文献
102.
In modern taxonomy, Trichophyton rubrum with the ‘raubitschekii’ morphotype differs from the common strains of T. rubrum morphologically, physiologically, and clinically, despite genetic homogeneity. In this paper, we report the first autochthonous
Turkish cases in a 24-year-old woman and her 26-year-old fiancé with tinea cruris and tinea manuum, respectively. The isolates
were proven to be T. rubrum with the ‘raubitschekii’ morphotype by their morphological and physiological characteristics including the following: (1) granular colony surface,
(2) profuse macroconidia and microconidia, (3) strongly positive urease activity after 3 days, (4) non-perforating hair, (5)
restricted growth and producing no alkaline reaction on bromocresol purple-milk solids-glucose agar, and (6) restricted growth
and producing no conidia on 3–9% NaCl-supplemented Sabouraud agar. The internal transcribed spacer (ITS) regions of both isolates
were sequenced, and the assembled DNA sequences were examined using the Basic BLAST (nucleotide–nucleotide) software of the
National Center for Biotechnology Information web database. Actually, the lack of epidemiological data on this variety is
notable, and the actual prevalence is unknown. Otherwise, routine methods misidentified the strains as T. rubrum or unrecognized cases were underreported. 相似文献
103.
Paul Becher Stefanie Schmeiser Tuba Cigdem Oguzoglu Alexander Postel 《Journal of virology》2012,86(20):11412
We report here the complete genome sequence of pestivirus strain Aydin/04-TR, which is the prototype of a group of similar viruses currently present in sheep and goats in Turkey. Sequence data from this virus showed that it clusters separately from the established and previously proposed tentative pestivirus species. 相似文献
104.
Francsics-Czinege E Tuba Z Molnár C Horváth J Csörgei J Visky G Balogh G Mák M Hegedus B Magyari M Horváth J 《Steroids》2003,68(9):739-749
Teutsch G. and Bélanger A. treated 5alpha,10alpha epoxides with Grignard-reagents catalyzed by copper(I) ions. The reaction with steroidal epoxides proceeded with complete regio- and stereospecificity, leading exclusively to the 11beta-substituted compounds. According to our synthetic strategy, the 5,10 epoxide isomers were not separated; instead, the pure 11beta, and in some cases, 11alpha-substituted molecules were isolated after the conjugate addition of the Grignard-reagents, followed by deketalization and dehydration. Surprisingly, appearance of a third compound was generally observed beside the expected deprotected products, and this compound turned out to have a 3-keto-5(10),9(11) structural unit. Starting from pure 3-ethylenedioxy-5alpha,10alpha-epoxy-estr-9(11)-ene-17-one and 3-ethylenedioxy-5beta,10beta-epoxy-estr-9(11)-ene-17-one, four model compounds were synthesized (11alpha- and 11beta-[4-[1,1-(ethylenedioxy)-ethyl]phenyl]-estra-, as well as 11alpha- and 11beta-cyclohexyl-estra-derivatives) to study the process of deprotection and dehydration. 3-keto-5(10),9(11)-derivatives were found to form after deketalization and dehydration only from 11alpha-substituted derivatives, while 11beta-derivatives resulted in only the expected 3-keto-5,9-diene structure. After observing this remarkable difference between the behavior of 11alpha-, 11beta-substituted isomers we decided to take a closer look at the processes of deketalization and dehydration. In order to carry out the hydrolysis under mild conditions, pyridinium paratoluenesulfonate, a weakly acidic salt, was applied. All the intermediate products observed by TLC were isolated. The outcome of the deprotection and elimination reactions can be rationalized by two factors: conjugation of olefins (with the 3-oxo-group or the 11-phenyl group) and orientation of groups to be eliminated. 相似文献
105.
Steroidal dienes were synthesised by Stille-coupling of the corresponding alkenyl iodides with vinyltributyltin under microwave irradiation in a domestic microwave oven in drastically reduced reaction times. Rate acceleration was observed also in the one-pot Stille-coupling-Diels-Alder reaction of 17-iodo-5alpha-androst-16-ene. Stereoselectivity of cycloaddition was slightly improved with diethyl maleate as the dienophile, compared to that achieved with thermal heating. 相似文献
106.
Georgieva K Maslenkova L Peeva V Markovska Y Stefanov D Tuba Z 《Photosynthesis research》2005,85(2):191-203
The functional peculiarities and responses of the photosynthetic system in the flowering homoiochlorophyllous desiccation-tolerant (HDT) Haberlea rhodopensis and the non-desiccation-tolerant spinach were compared during desiccation and rehydration. Increasing rate of water loss clearly modifies the kinetic parameters of fluorescence induction, thermoluminescence emission, far-red induced P700 oxidation and oxygen evolution in the leaves of both species. The values of these parameters returned nearly to the control level after 24 h rehydration only of the leaves of HDT plant. PS II was converted in a non-functional state in desiccated spinach in accordance with the changes in membrane permeability, malondialdehyde, proline and H2O2 contents. Moreover, our data showed a strong reduction of the total number of PS II centers in Haberlea without any changes in the energetics of the charge recombination. We consider this observation, together with the previously reported unusually high temperature of B-band (S2QB-) emission of Haberlea to reflect some specific adaptive characteristics of the photosynthetic system. As far as we know this is the first time when such adaptive characteristics and mechanism of the photosynthetic system of a flowering HDT higher plant is described. These features of Haberlea can explain the fast recovery of its photosynthesis after desiccation, which enable this HDT plant to rapidly take advantage of frequent changes in water availability. 相似文献
107.
J. Balogh Z. Nagy Sz. Fóti K. Pintér Sz. Czóbel E. R. Péli M. Acosta M. V. Marek Zs. Csintalan Z. Tuba 《Photosynthetica》2007,45(2):288-292
Measurements of CO2 and H2O fluxes were carried out using two different techniques—eddy-covariance (EC) and open system gas exchange chamber (OC)—during
two-years’ period (2003–2004) at three different grassland sites. OC measurements were made during fourteen measurement campaigns.
We found good agreement between the OC and EC CO2 flux values (n = 63, r
2 = 0.5323, OC FCO2 = −0.6408+0.9508 EC FCO2). The OC FH2O values were consistently lower than those measured by the EC technique, probably caused by the air stream difference inside
and outside the chamber. Adjusting flow rate within the chamber to the natural conditions would be necessary in future OC
measurements. In comparison with EC, the OC proved to be a good tool for gas exchange measurements in grassland ecosystems. 相似文献
108.
Mustafa Çağatay Tufan Tuba Namdar Hasan Gümüş 《Radiation and environmental biophysics》2013,52(2):245-253
The stopping power in some biological compounds for electrons and positrons was calculated over the energy range from 100 eV to 1 GeV. Total stopping power was obtained by summing the electronic (collisional) and radiative stopping power of the target materials and then employing the continuous slowing down approximation (CSDA) to calculate the path length of incident particles in the target. An effective charge approximation was used for the calculation of collisional stopping power, and an analytical expression for the radiation length was applied to obtain the radiative stopping power. Calculations of stopping power and CSDA range were based mostly on analytical expressions, to allow for an easy calculation of these parameters. The results were tabulated and compared with available data. 相似文献
109.
Erdal Eren Tuba Edgunlu Huseyin Anil Korkmaz Esra Deniz Papatya Cakir Korcan Demir Esin Sakalli Cetin Sevim Karakas Celik 《Gene》2014
Objective
Gynecomastia is a benign breast enlargement in males that affects approximately one-third of adolescents. The exact mechanism is not fully understood; however, it has been proposed that estrogen receptors and aromatase enzyme activity may play important roles in the pathogenesis of gynecomastia. While many studies have reported that aromatase enzyme (CYP19) gene polymorphism is associated with gynecomastia, only one study has shown a relationship between estrogen receptor (ER) alpha and beta gene polymorphism and gynecomastia. Thus, the aim of this study was to evaluate the relationships between CYP19 (rs2414096), ER alpha (rs2234693), ER beta (rs4986938), leptin (rs7799039), and leptin receptor (rs1137101) gene polymorphisms and gynecomastia.Methods
This study included 107 male adolescents with gynecomastia and 97 controls. Total serum testosterone (T) and estradiol (E2) levels were measured, and DNA was extracted from whole blood using the PCR–RFLP technique. The polymorphic distributions of CYP19, ER alpha, ER beta, leptin and leptin receptor genes were compared.Results
The median E2 level was 12.41 (5.00–65.40) pg/ml in the control group and 16.86 (2.58–78.47) pg/ml in the study group (p < 0.001). The median T level was 2.19 (0.04–7.04) ng/ml in the control group and 1.46 (0.13–12.02) ng/ml in the study group (p = 0.714). There was a significant relationship between gynecomastia and leptin receptor rs1137101 (p = 0.002) and ER beta receptor rs4986938 gene polymorphisms (p = 0.002).Conclusions
According to our results, increased E2 level and ER beta gene rs4986938 polymorphism might explain why some adolescents have gynecomastia. Leptin receptor gene rs1137101 polymorphism might affect susceptibility to gynecomastia. 相似文献110.
Selective Laser Melting(SLM),one of the metal additive manufacturing methods in the powder bed,is frequently used in the pro-duction of 316L stainless steel bio... 相似文献