Streptosporangium oxazolinicum sp. nov., a novel endophytic actinomycete producing new antitrypanosomal antibiotics, spoxazomicins

An actinomycete strain K07-0460(T) producing new antitrypanosomal antibiotics, spoxazomicins, was isolated from the roots of a variety of orchid collected in the subtropical Okinawa prefecture. The 16S ribosomal RNA gene sequence analysis indicated that the strain belonged to the genus Streptosporangium and showed high similarities with S. amethystogenes subsp. amethystogenes DSM 43179(T) (99.4%), S. amethystogenes subsp. fukuiense IFO 15365(T) (99.2%) and S. longisporum DSM 43180(T) (98.7%). The DNA-DNA hybridization relatedness values between strain K07-0460(T) and the three strains were below 70%. On the basis of phylogenetic analysis, DNA-DNA hybridization relatedness and physiological characteristics, the strain should be classified as a new species Streptosporangium oxazolinicum sp. nov. in the genus Streptosporangium. The type strain of S. oxazolinicum is K07-0460(T) (=JCM 17388(T)).     

Actinomycetospora iriomotensis sp. nov., a novel actinomycete isolated from a lichen sample

An actinomycete strain, IR73-Li102(T), was isolated from a lichen sample obtained from Iriomote Island, Japan, and subsequently characterized using a polyphasic approach. Comparative 16S rRNA gene sequence analysis revealed that strain IR73-Li102(T) had the highest sequence similarities with Actinomycetospora chiangmaiensis YIM 0006(T) (98.3%), A. corticola 014-5(T) (98.1%) and A. rishiriensis RI109-Li102(T) (98.0%). However, DNA-DNA hybridization assays, as well as physiological and biochemical analyzes, showed that strain IR73-Li102(T) could be clearly differentiated from its closest phylogenetic relatives. The strain contained meso-diaminopimelic acid, and arabinose and galactose were present in whole-cell hydrolysates. The predominant menaquinone was MK-8(H(4)), and the diagnostic phospholipids were phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol and diphosphatidylglycerol. The major cellular fatty acid was iso-C(16:0) (58%). The chemotaxonomic properties of strain IR73-Li102(T) were consistent with those shared by members of the genus Actinomycetospora. On the basis of the phenotypic features and DNA-DNA hybridization data, strain IR73-Li102(T) (= NBRC 106365(T) = KCTC 19783(T)) represents a novel species of the genus Actinomycetospora, for which the name Actinomycetospora iriomotensis sp. nov. is proposed.     

Actinoplanes rishiriensis sp. nov., a novel motile actinomycete isolated by rehydration and centrifugation method

The motile actinomycete strain RI50-RCA114(T) was isolated using rehydration and centrifugation method from a soil sample obtained from Rishiri Island in Japan. The taxonomic status of this organism was established using a polyphasic approach. Cells of strain RI50-RCA114(T) were Gram positive, aerobic, motile and formed irregular sporangia. The strain grew in the presence of 0-2% (w/v) NaCl, between pH 5 and 8, and over a temperature range of 20-37°C, with optimal growth at 30°C. Whole-cell hydrolysates of the strain contained meso-diaminopimelic acid, galactose, glucose and mannose, in addition to one unidentified O-methyl-hexose. The predominant menaquinone was MK-9(H(4)), and the major polar lipids comprised phosphatidylethanolamine, diphosphatidylglycerol and phosphatidyl-N-methylethylethanolamine. The major cellular fatty acids were iso-C(16:0), iso-C(15:0) and anteiso-C(17:0). Comparative 16S ribosomal RNA gene sequence analysis revealed that strain RI50-RCA114(T) had the closest sequence similarity with Actinoplanes globisporus JCM 3186(T) (97.6%). However, DNA-DNA hybridization assays as well as physiological and biochemical analyses differentiated strain RI50-RCA114(T) from its closest phylogenetic relative. On the basis of these data, we propose that strain RI50-RCA114(T) (=NBRC 108556(T)=BCC 49184(T)) be classified as the type strain of a novel Actinoplanes species and named Actinoplanes rishiriensis sp. nov.     

Sphaerisporangium siamense sp. nov., an actinomycete isolated from rubber-tree rhizospheric soil

A Gram-positive aerobic actinomycete, designated SR14.14(T), isolated from the rhizospheric soil of rubber tree was determined taxonomically using a polyphasic approach. The organism contained meso-diaminopimelic acid and the N-acetyl type of peptidoglycan. The predominant menaquinones were MK-9, MK-9(H?) and MK-9(H?). Madurose was detected in the whole-cell hydrolysates. Mycolic acids were not presented. Major phospholipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol mannoside. Major cellular fatty acid was iso-C(??:?) and the G+C content was 71.9?mol %. Phylogenetic analysis based on 16S rRNA gene sequence suggested that the isolate belongs to the genus Sphaerisporangium. The sequence similarity value between the strain SR14.14(T) and its closely related species, Sphaerisporangium album, was 97.8%. DNA-DNA hybridization values between them were well below 70%. Based on genotypic and phenotypic data, strain SR14.14(T) represents a novel species in the genus Sphaerisporangium, for which the name Sphaerisporangium siamense sp. nov. is proposed. The type strain is SR14.14(T) (=BCC 41491(T)=NRRL B-24805(T)=NBRC 107570(T)).     

Luteimicrobium album sp. nov., a novel actinobacterium isolated from a lichen collected in Japan, and emended description of the genus Luteimicrobium

A novel Gram-stain-positive actinobacterium, designated RI148-Li105(T), was isolated from a lichen sample from Rishiri Island, Japan, and its taxonomic position was investigated by a polyphasic approach. 16S rRNA gene sequencing study indicated that strain RI148-Li105(T) was related to the type strain of Luteimicrobium subarcticum, with a similarity of 97.8%. Cells of strain RI148-Li105(T) exhibited a rod-coccus cycle. The diagnostic cell-wall diamino acid of this organism was lysine and the peptidoglycan type was found to be A4α. The predominant menaquinones were MK-8(H(2)) and MK-9(H(2)), and the major fatty acids were iso-C(16:0), C(17:1) ω9c and C(17:0). The DNA G+C content was 73.6 mol%. The major phenotypic characteristics of strain RI148-Li105(T) basically corresponded to those of the genus Luteimicrobium excluding the fatty acid composition. These results suggest that strain RI148-Li105(T) should be affiliated with the genus Luteimicrobium. Meanwhile, DNA-DNA hybridization and some phenotypic characteristics revealed that the strain differs from L. subarcticum. Therefore, strain RI148-Li105(T) represents a novel species of the genus Luteimicrobium, for which the name Luteimicrobium album sp. nov. is proposed. The type strain of Luteimicrobium album is RI148-Li105(T) (=NBRC 106348(T)=DSM 24866(T)).     

Flexivirga alba gen. nov., sp. nov., an actinobacterial taxon in the family Dermacoccaceae

A novel actinobacterial strain ST13(T) isolated from soil near wastewater treatment facilities of an electroplating plant was subjected to a polyphasic taxonomic study. Cells of this organism were non-sporulating, and were irregular coccoid to comma shaped. The peptidoglycan of strain ST13(T) contained glutamic acid, serine, alanine, glycine and lysine, and represented the peptidoglycan type A4α. The whole-cell sugars contained ribose, glucose, galactose, rhamnose and mannose. The predominant menaquinone was MK-8(H(4)). The major fatty acid was iso-C(16:0). The polar lipid contained phosphatidylglycerol. The DNA G+C content was 67.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain ST13(T) fell within the radius of the family Dermacoccaceae, and its closest neighbor was Luteipulveratus mongoliensis MN07-A0370(T) (95.1%). However, strain ST13(T) did not make a coherent clade with members of the recognized organisms. On the basis of the phylogenetic and phenotypic characteristics of this actinobacterium, a novel genus and species, Flexivirga alba gen. nov., sp. nov., is proposed. The type strain of F. alba is ST13(T) (= NBRC 107580(T) = DSM 24460(T)).     

广西沿海红树林土壤放线菌多样性、新颖性及抗菌活性研究

摘要：目的 研究广西3个主要红树林生态区土壤放线菌资源的多样性和新颖性,为研发微生物药物提供菌种资源储备。 方法 从广西茅尾海、北仑河口、山口红树林自然保护区采集27份土壤样品;采用稀释涂布法和8种分离培养基进行放线菌的 分离纯化;菌株纯化后,采用Chelex-100法提取基因组DNA;通过PCR扩增和测序,获得菌株16S rRNA基因序列,并提交到 EzBioCloud数据库中进行相似性搜索比对;构建基于16S rRNA基因序列的系统进化树,进行多样性和新颖性分析;潜在放线 菌新种经发酵离心后,上清液用乙酸乙酯萃取、浓缩,采用纸片扩散法进行抗菌活性检测。结果 分离出菌株246株,其中放 线菌181株,分布于6个目12个科19个属,菌株M2SK6-2、M2SK3-10、M5SK3-12和M1QZ16-11分别与最近有效种Streptomyces avicenniae DSM 41943T、Rhodococcus olei JCM 32205T、Agromyces kandeliae Q22T和Humibacillus xanthopallidus KV-663T的16S rRNA基因序列相似性最高,相似率分别为97.4%、97.7%、98.4%和98.4%,为潜在新种;4株潜在放线菌新种中,菌株M2SK6-2 对多种革兰阳性菌具有较强的抗菌活性。结论 广西沿海红树林放线菌资源丰富多样,新颖性高,具有从中发现放线菌新物种 和新次级代谢产物的潜力,值得深入研究。     

Vibrio inhibens sp. nov., a novel bacterium with inhibitory activity against Vibrio species

Strain BFLP-10(T), isolated from faeces of wild long-snouted seahorses (Hippocampus guttulatus), is a Gram-negative, motile and facultatively anaerobic rod. This bacterium produces inhibitory activity against Vibrio species. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain BFLP-10(T) was a member of the genus Vibrio and was most closely related to Vibrio owensii (99%), Vibrio communis (98.9%), Vibrio sagamiensis (98.9%) and Vibrio rotiferianus (98.4%). However, multilocus sequence analysis using gyrB, pyrH, recA and topA genes revealed low levels of sequence similarity (<91.2%) with these closely related species. In addition, strain BFLP-10(T) could be readily differentiated from other closely related species by several phenotypic properties and fatty acid profiles. The G+C content of the DNA was 45.6?mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain BFLP-10(T) represents a novel species within the genus Vibrio, for which the name Vibrio inhibens sp. nov. is proposed. The type strain is BFLP-10(T) (=CECT 7692(T)=DSM 23440(T)).     

一株红树林链霉菌所产抑菌活性化合物的分离及其生物合成基因簇的研究

摘要：目的 分离鉴定一株红树林来源具有拮抗真菌活性的链霉菌MCCG 2008,分析其对植物病原真菌香蕉尖孢镰刀 菌热带4号小种(Fusarium oxysporum f.sp. cubense tropical race 4)、苹果链格孢菌(Alternaria alstroemeriae)、珍珠李葡萄座腔菌 (Botryosphaeria dothidea)和芒果炭疽菌(Colletotrichum fructicola)的抑制作用,对其所产的抑菌活性化合物进行了分离纯化,并 通过基因扩增测序分析与活性化合物生产相关的生物合成基因簇,为进一步调控活性化合物的生产以及结构优化提供依据。方 法 通过形态观察、生理生化特性和16S rRNA基因序列分析对MCCG 2008进行初步鉴定;通过发酵液原液、发酵液乙酸乙酯粗 提取物和菌丝体丙酮浸提物针对不同植物病原真菌进行了活性测试与效用组成分析;采用液液萃取和柱色谱分离该菌株所产生 的具有抑菌活性的次级代谢产物,通过高效液相色谱质谱联用仪和核磁共振仪对活性化合物结构进行解析;设计引物使用PCR 扩增该菌中与活性化合物生物合成相关的基因。结果 菌株MCCG 2008可形成茂盛的气生菌丝,并产生黄色的可扩散色素, 16S rRNA基因序列系统发育分析显示菌株MCCG 2008与微小链霉菌Streptomyces parvulus NBRC 13193T的相似度为100%;在拮 抗活性试验中,菌株MCCG 2008对珍珠李葡萄座腔菌的抑制活性最强,抑制率为48.0%,其发酵液乙酸乙酯粗提物和菌丝体丙 酮浸提物仅对香蕉尖孢镰刀菌热带4号小种有抑制活性;质谱(MS)和核磁(1H NMR)数据分析表明从菌株MCCG 2008的发酵液中 分离得到的活性化合物为放线菌素D;以放线菌素D生产菌为参照,通过序列比对发现MCCG 2008中的同源序列,并通过PCR 扩增获得菌株MCCG 2008基因组中与放线菌素D生物合成相关的基因。结论 分离自广西红树林根际土壤的链霉菌MCCG 2008 初步鉴定为微小链霉菌,其具有拮抗植物病原真菌的生防潜力,所产的活性化合物为放线菌素D。     

Mitochondrial benzodiazepine receptors regulate oxygen homeostasis in the early mouse embryo

The peripheral benzodiazepine receptor (Bzrp) has been implicated in the control of several processes, including mitochondrial biogenesis and embryo development. The present study examined the impact that specific Bzrp ligands have on oxygen homeostasis in the early mouse embryo. Day 9 embryos at the 16-18 somite pair stage were exposed to standard (21% oxygen) and suboptimal (5% oxygen) oxygen tensions in whole embryo culture. Analysis of gene expression used relative PCR to monitor changes in nuclear respiratory factor-1 (Nrf1), mitochondrial 16S ribosomal RNA (16S rRNA), and genes for several glycolytic enzymes. Ocular development was highly sensitive to periods of hypoxia through a mechanism blocked with the potent Bzrp ligand PK11195. Hypoxia led to a decline of Nrf1 and 16S rRNA levels also through a mechanism blocked with PK11195. Similar activity was observed for FGIN-1-27 whereas Ro5-4864 had contradictory effects. Morpholino-based gene knockdown of Nrf1 (anti-NRF1) produced a sequence-specific decrease in 16S rRNA insensitive to PK11195. These functional relationships suggest that Bzrp-dependent signals regulate the Nrf1 --> Tfam1 --> mtDNA --> 16S rRNA pathway in response to oxygen levels. The activity of PK11195 most likely has a pharmacodynamic basis with regards to specific embryonic precursor target cell populations, transducing a mitochondrial signal to an Nrf1 response analogous to retrograde regulation in yeast for mitochondria-to-nucleus signaling.     

Optimization of antifungal production from a novel strain Streptomyces sp. TKJ2 using response surface methodology

A newly filamentous bacteria was recovered from Tikjda forest soil (Algeria) for its high antifungal activity against various pathogenic and phytopathogenic fungi. The nucleotide sequence of the 16S rRNA gene (1454 pb) of Streptomyces sp. TKJ2 exhibited close similarity (99 %) with other Streptomyces 16S rRNA genes. Response surface methodology (RSM) was employed for optimizing this production. Three nutritional variables namely concentration of carbon source (starch), nitrogen source (casein), and NaCl were selected for the production of antifungal in submerged fermentation. Starch, casein, and NaCl were found to influence antifungal production significantly. These variables were selected for further optimization studies using a Box–Behnken design at three levels in 15 experiments using full factorial design. The statistical optimization by RSM to enhance the yield of antifungal production by Streptomyces sp. TKJ2 resulted that starch and NaCl increase, respectively, 13.05 g/l instead of 10 g/l and 2.54 g/l instead of 2 g/l. While casein decrease 0.2 g/l instead of 0.3 g/l. The present study has proved that RSM could be used as a valuable and dependable tool for the optimization of antifungal production from actinomycetes.     

Prevalence of β-lactamases and 16S rRNA methylase genes amongst clinical Klebsiella pneumoniae isolates carrying plasmid-mediated quinolone resistance determinants

To characterise the prevalence of β-lactamases and 16S rRNA methylase genes amongst clinical Klebsiella pneumoniae isolates carrying plasmid-mediated quinolone resistance (PMQR) determinants in China, 59 non-duplicate K. pneumoniae isolates harbouring at least one PMQR gene were screened for common β-lactamases and 16S rRNA methylases genes. The genetic relatedness of the isolates was analysed by pulsed-field gel electrophoresis (PFGE). Most of PMQR gene-positive isolates carried no substitutions within the quinolone resistance-determining regions (QRDRs) or single point mutation in GyrA or ParC. Over one-half (52.5%) of the isolates exhibited decreased susceptibility to ciprofloxacin [minimum inhibitory concentration (MIC)=0.5-2 μg/mL] or low-level resistance to ciprofloxacin (MIC=4-8 μg/mL). qnr, aac(6')-Ib-cr and qepA were positive in 52 (88.1%), 16 (27.1%) and 3 (5.1%) isolates, respectively. The identified genes for β-lactamases were distributed as follows: bla(TEM), 50.8%; bla(SHV), 91.5%; bla(CTX-M), 55.9%; bla(DHA), 59.3%; and bla(OXA-1), 22.1%. armA and rmtB were detected in 16.9% and 3.4% of isolates, respectively. All qnrB were detected in DHA-producing K. pneumoniae. Approximately 81.3%, 68.8% and 43.8% of aac(6')-Ib-cr carrying isolates produced OXA-1, DHA and ArmA, respectively. In conclusion, owing to few QRDR substitutions, most of the PMQR gene-carrying K. pneumoniae isolates exhibited low-level resistance to fluoroquinolones. qnr appears to be the predominant PMQR gene and it presented a significant correlation with bla(SHV), bla(CTX-M) and bla(DHA), whereas aac(6')-Ib-cr exhibited a close relationship with bla(OXA-1), bla(DHA) and armA. qepA was rarely detected in this study.     

Isolation and characterization of a human intestinal bacterium, Eubacterium sp. ARC-2, capable of demethylating arctigenin, in the essential metabolic process to enterolactone

Plant lignans, such as pinoresinol diglucoside, secoisolariciresinol diglucoside and arctiin, are metabolized to mammalian lignans, enterolactone or enterodiol, by human intestinal bacteria. Their metabolic processes include deglucosylation, ring cleavage, demethylation, dehydroxylation and oxidation. Here we isolated an intestinal bacterium capable of demethylating arctigenin, an aglycone of arctiin, to 2,3-bis(3,4-dihydroxybenzyl)butyrolactone (1) from human feces, and identified as an Eubacterium species (E. sp. ARC-2), which is similar to Eubacterium limosum on the basis of morphological and biochemical properties and 16S rRNA gene sequencing. By incubating with E. sp. ARC-2, arctigenin was converted to 1 through stepwise demethylation. Demethylation of arctigenin by E. sp. ARC-2 was tetrahydrofolate- and ATP-dependent, indicating that the reaction was catalyzed by methyltransferase. Moreover, E. sp. ARC-2 transformed secoisolariciresinol to 2,3-bis(3,4-dihydroxybenzyl)-1,4-butanediol by demethylation.     

New aromatic nitro compounds from Salegentibacter sp. T436, an Arctic Sea ice bacterium: taxonomy, fermentation, isolation and biological activities

Nineteen aromatic nitro compounds were isolated from the culture broth of an Arctic sea ice bacterium. Four of these compounds are new and six compounds are reported from a natural source for the first time. The new natural products showed weak antimicrobial and cytotoxic activities. 2-nitro-4-(2'-nitroethenyl)-phenol was the most potent antimicrobial and cytotoxic substance. Some of the compounds exhibit plant growth modulating activities. Based on its biochemical properties and the 16S rRNA gene sequence, the producing strain can be described as a distinct species within the genus Salegentibacter.     

Clinical characteristics of bacteraemia caused by Burkholderia cepacia complex species and antimicrobial susceptibility of the isolates in a medical centre in Taiwan

This study investigated the clinical characteristics and outcomes of bacteraemia due to Burkholderia cepacia complex (BCC) species among 54 patients without cystic fibrosis from January 2013 to February 2015. BCC isolates were identified to the species level by the Bruker Biotyper MALDI-TOF MS system and by sequencing analysis of the 16S rRNA and recA genes. Antimicrobial susceptibilities of the isolates were determined by the agar dilution method. Sequencing of the recA gene in the 54 blood isolates revealed 37 (68.5%) isolates of B. cenocepacia, 9 (16.7%) of B. cepacia, 4 (7.4%) of B. multivorans and one isolate each of B. arboris, B. pseudomultivorans, B. seminalis, and B. vietnamiensis. The overall performance of the Bruker Biotyper MALDI-TOF MS system for correctly identifying the 54 BCC isolates to the species level was 79.6%, which was better than that (16.7%) by 16S RNA sequencing analysis. Bacteraemic pneumonia (n?=?23, 42.6%) and catheter-related bacteraemia (n?=?21, 38.9%) were the most common types of infection. Higher rates of ceftazidime and meropenem resistance were found in B. cepacia isolates (33.3% and 22.2%, respectively) than in isolates of B. cenocepacia (21.6% and 10.8%, respectively) and other species (12.5% and 12.5%, respectively). Overall, the 30-day mortality rate was 38.9% (21/54). Bacteraemia caused by BCC species other than B. cenocepacia and B. cepacia (adjusted odds ratio [aOR] 20.005, P?=?0.024) and high SOFA score (aOR 1.412, P?=?0.003) were predictive of higher 30–day mortality. Different BCC species are associated with different outcomes of bacteraemia and exhibit different susceptibility patterns.     

宁夏枸杞根际土壤链霉菌V-1-3次级代谢产物分析

摘要：目的 获得链霉菌V-1-3的基因组序列信息,分析其次级代谢产物生物合成基因簇并预测其代谢产物,为发现潜在新抗生素奠定基础。方法 基于16S rRNA基因序列进行菌株属水平鉴定,利用Illumina HiSeq+PacBio测序技术对菌株V-1-3进行基因组测序,采用antiSMASH(v6.0.1)在线工具分析次级代谢产物生物合成基因簇,液-质联用技术检测产生的次级代谢产物。结果 链霉菌V-1-3基因组序列全长8 243 417 bp,平均(G+C)含量为72.14 %,共编码7578个基因,预测到33个生物合成基因簇,利用液-质联用检测到4个代谢物：oxalomycin B、geosmin、coelichelin和ishigamide。结论 来自盐碱地的链霉菌V-1-3具有丰富的次级代谢产物生物合成基因簇,能产生多种次级代谢产物,具有进一步发掘新抗生素的价值。     

Tityus perijanensis González-Sponga (Scorpiones, Buthidae): molecular assessment of its geographical distribution and venom lethality of Venezuelan populations.

An extensive field survey allowed us to expand the geographical distribution of the scorpion Tityus perijanensis in the Perijá range, western Zulia State, Venezuela, including areas where adult cases of severe scorpionism have been reported. 16S ribosomal RNA (rRNA) gene sequencing, DL(50) determination, and native PAGE suggest low genetic and venom proteomic divergence across the distribution range. The results also indicate phylogenetic divergence between T. perijanensis and T. discrepans, the species prevalent in northcentral Venezuela. T. perijanensis venom lethality (0.91-0.94 mg/kg) is comparable to that of the Brazilian T. serrulatus and ranks highest among toxic Venezuelan Tityus studied so far. The data indicate that the Perijá range should be included amongst the endemic areas of scorpionism of Venezuela and Colombia.     

Enhanced vasoconstriction to endothelin-1, angiotensin II and noradrenaline in carriers of the GNB3 825T allele in the skin microcirculation

Hypertension is associated with enhanced peripheral vascular resistance, which may be mediated by enhanced vasoconstriction. The impact of the recently detected G-protein beta3-subunit gene C825T polymorphism on the response to the major pressor mediators has been studied in vivo in the human microcirculation. We assessed the effects of endothelin-1 (ET-1), angiotensin II (AT), endothelin-antagonists (BQ-123 and BQ-788) and noradrenaline (NA, each 10-16-10-8 mol) on vasoconstriction in the human skin microcirculation in vivo in 25 healthy male volunteers (13 with CC genotype, 12 TC/TT genotype) using laser Doppler flowmetry. The effects of endothelium-derived vasodilation on NA-induced effects were studied using the NO-synthase inhibitor l-nitro-monomethyl-arginine (L-NMMA) and the alpha2-adrenoceptor-antagonist yohimbine (YO). ET-1, AT and NA caused a dose-dependent vasoconstriction (P < 0.001). In carriers of the 825T allele the response to ET-1, AT and NA was significantly enhanced leading to a shift to the left of the dose-response curve of up to two log units (ET-1: P < 0.001 vs. CC; AT: P < 0.01 vs. CC; NA: P < 0.05 vs. CC). After pretreatment with L-NMMA or YO, NA induced vasoconstriction was no longer different between subjects with the CC- and CT/TT genotypes. However, following combined pretreatment with both L-NMMA and YO, vasoconstriction to NA was significantly potentiated in carriers of the T-allele. Vasodilatation to an ETA-antagonist (BQ-123) was more pronounced in the CT/TT genotype, while ETB-antagonism (BQ-788) led to a more pronounced vasoconstriction in the CT/TT genotype (not significant vs. CC). Healthy, normotensive carriers of the 825T-allele have enhanced vasoconstriction to ET-1, AT and NA in the skin microcirculation. This enhanced vasoconstriction appears to be partially antagonized by an enhanced release of endothelium derived vasodilators mediated by the stimulation of endothelial alpha2-adrenoceptors. The GNB3 C825T polymorphism is potentially an attractive pharmacogenetic marker to predict hormone-mediated responses in humans.     

Frequency of the C1236T, G2677T/A and C3435T MDR1 gene polymorphisms in the Serbian population

The multi-drug resistance 1 (MDR1) gene encodes for a P-glycoprotein (PGP), which acts as a gate-keeper against various kinds of xenobiotics. Several single nucleotide polymorphisms (SNPs) in the MDR1 gene that may influence PGP level and function have been identified. The aim of this study was to simultaneously analyze the three most important MDR1 SNPs, C3435T, G2677T/A and C1236T, in the Serbian population and to compare the results with those published for other ethnic groups. A group of 158 unrelated, healthy subjects was included in the present study. For determination of MDR1 SNPs, a multiplexed mutagenically separated PCR was performed. The genotype frequency of the analyzed MDR1 SNPs was as follows: 3435 nt - 0.19 (CC), 0.54 (CT) and 0.27 (TT); 2677 nt - 0.26 (GG), 0.52 (GT), 0.15 (TT), 0.03 (GA) and 0.064 (TA), and 1236 nt - 0.23 (CC), 0.61 (CT) and 0.16 (TT). Our results for the Serbian population could be relevant for further investigation of drugs that are substrates of PGPand for studies of interethnic diversity in MDR1 polymorphism frequency.