青海祁连棱果沙棘自然杂交带三种沙棘 光合特性日变化分析

杂交带是研究物种形成及进化的天然实验室。为探究棱果沙棘自然杂交带三种沙棘的生理生态适应性,该研究在光照充足的7月中旬分别测定了该区域三种沙棘雌、雄株的光合特性及相关环境因子的日变化。结果表明:(1)同种沙棘雌、雄株间光合日变化规律基本一致,不同沙棘光合特性的日变化规律存在较大差异。中国沙棘(Hippophae rhamnoides ssp. sinensis)净光合速率(Pn)日变化呈明显的双峰曲线,峰值出现在光合有效辐射(PAR)和空气温度(Ta)相对较高的10:00和14:00,最高达到(19.53±5.35)μmol·m~(-2)·s~(-1);棱果沙棘(Hippophae goniocarpa)和肋果沙棘(H. neurocarpa ssp. neurocarpa) Pn日变化均呈近双峰曲线,在PAR和Ta相对较低的8:00和16:00有较高的值,最高值分别为(13.43±3.43)和(15.27±2.43)μmol·m~(-2)·s~(-1)。(2)三种沙棘水分利用效率(WUE)与Pn的日变化规律一致,但中国沙棘具有最高的WUE,达到(6.72±0.95)μmol·mmol~(-1),棱果沙棘和肋果沙棘的WUE日变化最高分别为(4.03±1.08)和(4.93±0.86)μmol·mmol~(-1)。(3)三种沙棘蒸腾速率(Tr)、气孔导度(Gs)、胞间二氧化碳浓度(Ci)和气孔限制值(Ls)的日变化规律相似,其中Gs均在10:00后一致下降,在12:00左右均出现不同程度的气孔关闭现象,这是其发生光合午休的主要原因之一。杂交带三种沙棘光合特性日变化差异主要表现在中国沙棘和其他两种沙棘之间,而杂交种棱果沙棘与亲本种肋果沙棘的变化规律基本一致,其Pn与WUE可能受到了Ta、PAR和空气相对湿度(RH)等环境因子的影响。     

A woman with thyrotoxicosis- and hyperemesis gravidarum-associated Wernicke's encephalopathy

Although hyperthyroidism arising from primary thyroid disease is rare in pregnancy, transient gestational hyperthyroidism is not uncommon. This condition can be associated with hyperemesis gravidarum (HG), and Wernicke's encephalopathy. We present the case of a woman with toxic nodular goiter complicating HG-associated Wernicke's encephalopathy. A 38-year-old Caucasian woman, who had received a diagnosis of hyperthyroidism and HG early in her pregnancy, had intrauterine fetal death at Week 16 of gestation. One day after undergoing therapeutic abortion, she was admitted to our clinic with persistent thyrotoxicosis, nausea, and vomiting. A toxic thyroid nodule was detected. She was given antithyroid medication, total parenteral nutrition. On Day 10 of hospitalization, she developed ataxia, aphasia, and somnolence. Cranial magnetic resonance imaging showed increased bilateral thalamic signalization. She was given a diagnosis of Wernicke's metabolic encephalopathy, for which she received thiamine and multivitamin preparations. She responded dramatically on the second day of thiamine therapy. Her consciousness improved rapidly and she began to speak. Her muscle tone was slightly weak and she had paresthesias in both legs. Absorption of thiamine may be particularly impaired in pregnant women with hyperemesis and hyperthyroid disease. Wernicke's encephalopathy should be considered in hyperthyroid women with HG who develop neurological abnormalities.     

Effects of melatonin in reducing the toxic effects of doxorubicin

Anthracycline antibiotics, such as doxorubicin and daunorubicin, constitute a group of wide spectrum therapeutic agents. Application of these drugs in chemotherapy is limited because of their toxic effects. Melatonin, the main secretory product of pineal gland, was recently found as a free radical scavenger and antioxidant.We decided to evaluate the tissue protective effect of melatonin against toxic effects of doxorubicin in six groups of rats. Rats were given doxorubicin (Dx) (45 mg/kg dose), melatonin (MEL) (10 mg/kg), first doxorubicin and then melatonin (DM), first melatonin and then doxorubicin (MD).The degree of kidney, lung, liver and brain cells' alterations were examined biochemically.In doxorubicin-treated group, malondialdehyde (MDA) levels of kidney, lung, liver and brain tissues were significantly increased but glutathione (GSH) levels were decreased compared to control rats. In the group in which first doxorubicin and then melatonin were given, MDA levels were significantly decreased compared to the doxorubicin-treated group.In doxorubicin-treated group, serum levels of creatinine, uric acid, blood urea nitrogen (BUN), Gamma-glutamyl transpeptidase (GGT) and Lactic acid dehydrogenase (LDH) were significantly increased while serum albumin and total protein levels were significantly decreased compared to control rats.Melatonin decreased the intensity of the changes produced by the administration of doxorubicin alone. Melatonin was quite efficient in reducing the formation of lipid peroxidation, restoring the tissue GSH contents and alterations of serum levels.     

New chromosome counts in the genus Centaurea (Asteraceae) from Turkey

Twenty‐two chromosome counts are reported in 16 species, four subspecies and two varieties of the genus Centaurea. These are mostly Turkish local endemics of section Cheirolepis, a complicated group from the Eastern clade of the Jacea group. Twenty‐one reports are new. Prevalence of the basic chromosome number x = 9 among the eastern sections of the Jacea group is confirmed. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 280–286.     

Carbonic anhydrase inhibitors. Inhibition of human erythrocyte isozymes I and II with a series of antioxidant phenols

The inhibition of two human cytosolic carbonic anhydrase (hCA, EC 4.2.1.1) isozymes I and II, with a series of phenol derivatives was investigated by using the esterase assay, with 4-nitrophenyl acetate as substrate. 2,6-Dimethylphenol, 2,6-diisopropylphenol (propofol), 2,6-di-t-butylphenol, butylated hydroxytoluene, butylated hydroxyanisole, vanillin, guaiacol, di(2,6-dimethylphenol), di(2,6-diisopropylphenol), di(2,6-di-t-butylphenol), and acetazolamide showed K_I values in the range of 37.5–274.5 μM for hCA I and of 0.29–113.5 μM against hCA II, respectively. All these phenols were non-competitive inhibitors with 4-nitrophenylacetate as substrate. Some antioxidant phenol derivatives investigated here showed effective hCA II inhibitory effects, in the same range as the clinically used sulfonamide acetazolamide, and might be used as leads for generating enzyme inhibitors possibly targeting other CA isoforms which have not been yet assayed for their interactions with such agents.     

An Enhancing Effect of Exogenous Mannitol on the Antioxidant Enzyme Activities in Roots of Wheat Under Salt Stress

The role of mannitol as an osmoprotectant, a radical scavenger, a stabilizer of protein and membrane structure, and protector of photosynthesis under abiotic stress has already been well described. In this article we show that mannitol applied exogenously to salt-stressed wheat, which normally cannot synthesize mannitol, improved their salt tolerance by enhancing activities of antioxidant enzymes. Wheat seedlings (3 days old) grown in 100 mM mannitol (corresponding to −0.224 MPa) for 24 h were subjected to 100 mM NaCl treatment for 5 days. The effect of exogenously applied mannitol on the salt tolerance of plants in view of growth, lipid peroxidation levels, and activities of antioxidant enzymes in the roots of salt-sensitive wheat (Triticum aestivum L. cv. Kızıltan-91) plants with or without mannitol was studied. Although root growth decreased under salt stress, this effect could be alleviated by mannitol pretreatment. Peroxidase (POX) and ascorbate peroxidase (APX) activities increased, whereas superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR) activities decreased in Kızıltan-91 under salt stress. However, activities of antioxidant enzymes such as SOD, POX, CAT, APX, and GR increased with mannitol pretreatment under salt stress. Although root tissue extracts of salt-stressed wheat plants exhibited only nine different SOD isozyme bands of which two were identified as Cu/Zn-SOD and Mn-SOD, mannitol treatment caused the appearance of 11 different SOD activity bands. On the other hand, five different POX isozyme bands were determined in all treatments. Enhanced peroxidation of lipid membranes under salt stress conditions was reduced by pretreatment with mannitol. We suggest that exogenous application of mannitol could alleviate salt-induced oxidative damage by enhancing antioxidant enzyme activities in the roots of salt-sensitive Kızıltan-91.     

Worldwide Prevalence of Class 2 Integrases outside the Clinical Setting Is Associated with Human Impact

An intI-targeted PCR assay was optimized to evaluate the frequency of partial class 2-like integrases relative to putative, environmental IntI elements in clone libraries generated from 17 samples that included various terrestrial, marine, and deep-sea habitats with different exposures to human influence. We identified 169 unique IntI phylotypes (≤98% amino acid identity) relative to themselves and with respect to those previously described. Among these, six variants showed an undescribed, extended, IntI-specific additional domain. A connection between human influence and the dominance of IntI-2-like variants was also observed. IntI phylotypes 80 to 99% identical to class 2 integrases comprised ∼70 to 100% (n = 65 to 87) of the IntI elements detected in samples with a high input of fecal waste, whereas IntI2-like sequences were undetected in undisturbed settings and poorly represented (1 to 10%; n = 40 to 79) in environments with moderate or no recent fecal or anthropogenic impact. Eleven partial IntI2-like sequences lacking the signature ochre 179 codon were found among samples of biosolids and agricultural soil supplemented with swine manure, indicating a wider distribution of potentially functional IntI2 variants than previously reported. To evaluate IntI2 distribution patterns beyond the usual hosts, namely, the Enterobacteriaceae, we coupled PCR assays targeted at intI and 16S rRNA loci to G+C fractionation of total DNA extracted from manured cropland. IntI2-like sequences and 16S rRNA phylotypes related to Firmicutes (Clostridium and Bacillus) and Bacteroidetes (Chitinophaga and Sphingobacterium) dominated a low-G+C fraction (∼40 to 45%), suggesting that these groups could be important IntI2 hosts in manured soil. Moreover, G+G fractionation uncovered an additional set of 36 novel IntI phylotypes (≤98% amino acid identity) undetected in bulk DNA and revealed the prevalence of potentially functional IntI2 variants in the low-G+C fraction.Integrons are genetic modules described in pathogenic and commensal bacteria that confer the ability to capture and express promoterless DNA units, called gene cassettes, which encode a variety of adaptive functions including antibiotic resistance (9, 42, 64). The acquisition of gene cassettes occurs through a site-specific recombination mechanism catalyzed by an integron-encoded integrase (IntI). The integrative recombination reaction occurs primarily between an integron receptor site (attI) and a cassette-associated sequence known as the attC site or 59-base element (11). However, integron integrases are able to recognize and process nonspecific secondary targets as well as attI and attC sites with a high degree of sequence variation (20, 25). This versatility facilitates the exchange of exogenous genes between different integrons through various recombination reactions (attI × attC, attI × attI, and attC × attC) that propel the adaptability and evolution of bacterial genomes (8, 11, 31, 38, 55, 58). Although integrons can be chromosomally encoded, they also may be horizontally transferred via transduction or by transposons associated with conjugative plasmids (42, 61). Three major groups (classes 1 to 3) are known to be associated with laterally transferred elements and highly prevalent in the clinical scene. In most of the cases, these have also been reported to harbor almost exclusively gene cassettes encoding antibiotic resistance functions (42). All together, these traits have led to their designation as “mobile” (9) or “clinical” (22) integrons. Although integrons have been traditionally classified according to the percent identity of the nucleotide or predicted amino acid sequence of their respective intI genes (9, 43, 71), several structural features and differences in abundance patterns have been identified which distinguish classes 1 to 3 (9, 42).Class 1 integrons are the most widely studied variant and are typically linked to replicative Tn21 transposons, which appears to contribute to their extensive distribution (48). A key feature commonly reported within the class 1 module is the presence of a highly conserved 3′ region comprised of a qacEΔ gene and a sul1 gene, which provide protection against quaternary ammonium compounds and sulfa drugs, respectively. In contrast, class 2 integrons are routinely associated with nonreplicative Tn7 transposons, are less frequently detected and, hence, remain an understudied group relative to their class 1 counterparts (42, 48, 65). Even less is known about the class 3 variants, which so far have been described in only three instances (71).Except for the identical IntI2 elements recently reported in Providencia stuartii and Escherichia coli strains isolated from beef cattle sources and the human urinary tract, respectively, all known integrases encoded by class 2 integrons are considered nonfunctional due to the presence of the ochre 179 codon (6, 40, 42). Nevertheless, it has been argued that integrons with truncated class 2 integrases might be implicated in the transfer and high prevalence of antibiotic resistance genes among clinical isolates, possibly via the in trans activities of other functional integrases or the suppression of the stop codon (27). So far, class 2 integrons have been described in association with isolates affiliated to the gamma, beta, and epsilon subdivisions of the Proteobacteria but have been more frequently reported among members of the Gammaproteobacteria group, particularly the Enterobacteriaceae (1, 14, 19, 56, 57). However, most of these studies have focused on easily culturable, aerobic bacteria or those of clinical importance, leading to the exclusion of unculturable or difficult-to-grow commensals that could be inconspicuous but important reservoirs of class 2 elements in the environment. Although the occurrence and quantification of integrons and integron-associated genes by means of molecular, culture-independent methods are being increasingly documented outside the clinical scene (18, 22, 28, 48, 49, 51, 65, 70), the estimates of the extant diversity of the integron platform in nature are still rudimentary. Likewise, further work is needed for the identification of environmental hosts of integrons commonly found in clinical strains without the bias associated with culture techniques (48).In order to provide a comprehensive view of integron integrase variation and prevalence patterns of IntI2 elements in the environment, we PCR amplified partial intI sequences from metagenomic DNA isolated from various terrestrial, marine, and deep-sea habitats exposed to various degrees of anthropogenic or fecal impact. Amplification conditions were optimized to facilitate the assessment of the frequency of IntI2-like sequences relative to that of environmental integron integrases. Additionally, since the guanine-plus-cytosine content of DNA corresponds to taxonomy (68), we coupled G+C fractionation of total DNA (4, 5, 29, 30) with PCR assays targeted at intI and 16S rRNA genes to identify potential, unconventional hosts of class 2 integrons in soil that had received swine manure.     

Synthesis of stilbene-fused 2′-hydroxychalcones and flavanones

Synthesis of stilbene-fused chalcones and flavanones were successfully completed. Molecules were designed in a way to mimic the structural features of both “stilbene and chalcones” or “stilbene and flavanones” at the same time, and synthesized by three steps. Heck reactions of 3-bromobenzaldehyde with styrene derivatives gave corresponding (E)-stilbenes, which were reacted with acetophenones to furnish stilbene-fused 2′-hydroxychalcones under basic conditions. Finally, intramolecular cyclization reactions were performed to produce stilbene-fused flavanones.     

Analysis of the Wnt/B-catenin/TCF4 pathway using SAGE,genome-wide microarray and promoter analysis: Identification of BRI3 and HSF2 as novel targets

The Wnt signaling pathway is involved in many differentiation events during embryonic development and can lead to tumor formation after aberrant activation of its components. β-catenin, a cytoplasmic component, plays a major role in the transduction of canonical Wnt signaling. The aim of this study was to identify novel genes that are regulated by active β-catenin/TCF signaling in hepatocellular carcinoma-derived Huh7 cells with high (transfected) and low β-catenin/TCF activities. High TCF activity Huh7 cells led to earlier and larger tumor formation when xenografted into nude mice. SAGE (Serial Analysis of Gene Expression), genome-wide microarray and in silico promoter analysis were performed in parallel, to compare gene expression between low and high β-catenin/TCF activity clones, and also those that had been rescued from the xenograft tumors. SAGE and genome-wide microarray data were compared and contrasted. BRI3 and HSF2 were identified as novel targets of Wnt/β-catenin signaling after combined analysis and confirming experiments including qRT-PCR, ChIP, luciferase assay and lithium treatment.     

Drought-induced changes in nutrient concentrations and retention in two shallow Mediterranean lakes subjected to different degrees of management

While extensive knowledge exists on the relationship between nutrient loading and nutrient concentrations in lakes in the cold temperate region, few studies have been conducted in warm lakes, not least in warm arid lakes. This is unfortunate as a larger proportion of the world’s lakes will be situated in arid climates in the future due to climate change and a larger proportion will suffer from a higher frequency of intensive drought. We conducted a comprehensive 11–13 year mass balance study in two interconnected shallow Mediterranean lakes in Turkey, covering a period with substantial changes in climate conditions. The upstream lake was only affected by natural changes in nutrient loading, while the downstream lake was additionally influenced by sewage diversion and restoration by fish removal. Contrasting to experience from north temperate lakes we found an increase in in-lake concentrations of total phosphorus and inorganic nitrogen (ammonia as well as nitrate) in dry years despite lower external nutrient loading, and submerged macrophytes did not increase the nitrogen retention capacity of the lakes. In contrast, fish removal modulated the nitrogen concentration as in north temperate lakes, but the effect was not long-lasting. Our results suggest that climate warming reduces the nutrient retention capacity of shallow lakes in the Mediterranean and exacerbates eutrophication. Lower thresholds of nutrient loading for shifting turbid shallow lakes to a clear water state are therefore to be expected in arid zones in a future warmer climate, with important management implications.