Strain identification inRhizobium meliloti using the antibiotic disk susceptibility test

Summary The antibiotic disk susceptibility test was used to measure the variation in the intrinsic resistance of 49 strains ofRhizobium meliloti to 9 antibiotics. Several strains had unique patterns of resistance. However, during cluster analysis, when a minimum Euclidean distance equal to 4 was used as a discriminating tool, the strains were grouped in 12 groups. The largest group contained 74% of the strains but 9 strains (2 very effective, 4 effective and 3 ineffective) showed very unique patterns of resistance and formed 9 distinct groups.R. meliloti strains in general showed high intrinsic resistance to the 9 antibiotics tested.Contribution no. 189 Station de Recherches, Agriculture Canada.     

Cytoplasmic proteome reference map for a glutamic acid-producing Corynebacterium glutamicum ATCC 14067

We constructed a cytoplasmic proteome reference map for a glutamic acid producing Corynebacterium glutamicum ATCC 14067 by 2-DE and protein identification by MALDI-TOF-MS and PMF using genome database of the type strain ATCC 13032. The map allowed us to identify 166 protein spots representing 139 different proteins. A considerable strain difference was observed in the proteomic images between strains ATCC 14067 and ATCC 13032 grown under the glutamic acid production conditions, suggesting the importance of strain-specific reference map for proteomic analysis.     

Gymnodinium catenatum Graham isolated from the Portuguese coast: Toxin content and genetic characterization

The bloom forming marine dinoflagellate Gymnodinium catenatum Graham has been linked to paralytic shellfish poisoning (PSP) outbreaks in humans. Along the Portuguese coast (NE Atlantic), G. catenatum shows a complex bloom pattern, raising questions about the origin and affinities of each bloom population. In this work, the variability within six cultured strains of G. catenatum isolated from Portuguese coastal waters (S coast, W coast and NW coast), between 1999 and 2011, was investigated. The strains were analyzed for toxin profiling and intra-specific genetic diversity. Regarding the toxin profile, differences recorded between strains could not be assigned to the time of isolation or geographical origin. The parameter that most influenced the toxin profile was the life-cycle stage that originated the culture: vegetative cell versus hypnozygote (resting cyst). At the genetic level, all strains showed similar sequences for the D1–D2 region of the large subunit (LSU) of the nuclear ribosomal DNA (rDNA) and shared complete identity with strains from Spain, Algeria, China and Australia. Conversely, we did not find a total identity match for the ITS-5.8S nuclear rDNA fragment. After sequence analysis, two guanine/adenine (R) single nucleotide polymorphisms (SNP 1 and 2) were detected for all strains, in the ITS1 region. This species has been reported to present very conservative LSU and ITS-5.8S rDNA regions, though with few SNP, including SNP1 of this study, already attributed to strains from certain locations. The SNP here described characterize G. catenatum populations from Portuguese waters and may represent valuable genetic markers for studies on the phylogeography of this species.     

鸡产蛋下降综合征病毒NE4毒株对KM小鼠感染特性观察

目的初步探究鸡产蛋下降综合征病毒NE4（EDSV NE4）毒株对昆明小鼠的感染特性。方法用106TCID50攻毒量的EDSV NE4株对4～6周龄的KM小鼠进行攻毒试验,同时以正常尿囊液接种作为阴性对照。用荧光定量PCR对小鼠组织及粪便中的EDSV进行检测,同时用HE染色及免疫组化法对小鼠组织切片进行病理组织学观察和抗原定位。结果 EDSV攻毒对小鼠的采食情况产生一定影响,但并未引起明显的临床症状;攻毒组小鼠可产生针对EDSV特异性的抗体,HI抗体滴度可高达212,阴性对照组小鼠体内抗体检测为阴性;攻毒后小鼠大部分组织器官如肝脏、子宫、肾脏、肺脏等与攻毒7 d后粪便中均可检测到EDSV,阴性对照小鼠所有受检组织中均未检测到病毒;EDSV攻毒未能引起小鼠组织的病理学变化,攻毒后不同时间内,可在子宫、肺脏、肝脏、肾脏中可检测到阳性信号,最为典型的定殖位置是子宫腺体上皮细胞及肌层细胞的胞质中。结论 EDSV NE4株可以感染KM小鼠。     

产乙醇工程菌研究进展

伴随着21世纪的到来,低油价的时代也悄然落幕。简要概述了燃料乙醇产生菌代谢工程的研究进展,包括了利用淀粉、戊糖及纤维素的工程酵母构建,运动发酵单胞菌利用戊糖工程菌的构建,引入外源乙醇合成途径的大肠埃希氏菌和产酸克雷伯氏菌等。对燃料乙醇的重视将促进开发能利用廉价原料和要求粗放的工程菌株用于高产乙醇的生产过程,以降低成本和能耗,其中能利用生淀粉的工程酵母及利用木质纤维素水解物的运动发酵单胞菌工程菌有较大的工业化潜力。     

Body rate decoupling using haltere mid-stroke measurements for inertial flight stabilization in Diptera

Halteres, the modified rear wings of Diptera, have long been recognized as sensory organs necessary for basic flight stability. These organs, which act as vibrating structure gyroscopes, are known to sense strains proportional to Coriolis accelerations. While compensatory responses have been demonstrated that indicate the ability of insects to distinguish all components of the body rate vector, the specific mechanism by which the halteres are able to decouple the body rates has not been clearly understood. The research documented in this report describes a potential mechanism, using averaged strain and strain rate at the center of the haltere stroke, to decouple the inertial rate components. Through dynamic simulation of a nonlinear model of the haltere 3-dimensional trajectory, this straightforward method was demonstrated to provide an accurate means of generating signals that are proportional to three orthogonal body rate components. Errors associated with residual nonlinearity and rate-coupling were quantified for a bilaterally reconstructed body rate vector over a full range of pitch and yaw rates and two roll rate conditions. Models that are compatible with insect physiology are proposed for performing necessary signal averaging and bilateral processing.

近交系剑尾鱼的STR遗传检测技术

目的建立近交系实验用鱼DNA检测方法,用于遗传质量控制。方法以RR-B、RW-H、BY-F三个近交系剑尾鱼的基因组DNA为主要研究对象,并以非选育剑尾鱼作对照,采用STR（short tandem repeat）引物扩增方法检测不同品系在DNA上的异同。设计10对STR引物,优化PCR电泳条件,使用相同的实验条件进行重复,以得到可靠的扩增条带,筛选出特异性引物。结果有4对引物可扩增出稳定条带,1对引物（AY204223）的PCR扩增条带在非选育群中表现多态性,在RR-B与BY-F系表型一致,与RW-H表型不同。这些STR位点能够区分剑尾鱼三个近交系品系。结论STR检测技术可望用于近交系剑尾鱼的遗传质量监测。     

Theoretical study of the geometrical and electronic structures and thermochemistry of spherophanes

A set of supramolecular cage-structures—spherophanes—was studied at the density functional B3LYP level. Full geometrical structure optimisations were made with 6–31G and 6–31G(d) basis sets followed by frequency calculations, and electronic energies were evaluated at B3LYP/6–31++G(d,p). Three different symmetries were considered: C1, Ci, and Oh. It was found that the bonds between the benzene rings are very long to allow π-electron delocalisation between them. These spherophanes show portal openings of 2.596 Å in Spher1, 4.000 Å in Meth2, 3.659 Å in Oxa3, and 4.412 Å in Thia4. From the point of view of potential host–guest interaction studies, it should also be noted that the atoms nearest to the centre of the cavities are carbons bonded to X groups. These supramolecules seem to exhibit relatively large gap HOMO?LUMO: 2.89 eV(Spher1), 5.26 eV(Meth2), 5.73 eV(Oxa3), and 4.82 eV(Thia4). The calculated ΔH°_f (298.15 K) values at B3LYP/6–31G(d) are (in kcal mol^?1) 750.98, 229.78, ?10.97, and 482.49 for Spher1, Meth2, Oxa3, and Thia4, respectively. Using homodesmotic reactions, relative to Spher1, the spherophanes Meth2, Oxa3, and Thia4 are less strained by ?399.13 kcal mol^?1, ?390.40 kcal mol^?1, and ?411.38 kcal mol^?1, respectively. Their infrared and ¹³C NMR calculated spectra are reported.     

遗传改良"新吉富" (NEW GIFT)尼罗罗非鱼RAPD-SCAR标记开发及其在品系鉴别中的应用

“新吉富”(NEW GIFT)尼罗罗非鱼是以1994年引进的 “吉富”(GIFT)品系尼罗罗非鱼为基础群体,经过14年9代系统选育后获得的新品种,该品种已被国家审定为良种,已在全国推广,迫切需要有效的分子遗传标记来鉴别该新品种并实施科学管理。该研究对良种群体开展了RAPD分析,并进一步将特异性的RAPD标记转化成了稳定的SCAR标记。 通过对“新吉富”群体的RAPD分析,找到了两个品种特异性的RAPD条带（S₃₀₄^{624 bp}和S₃₆^{568 bp}）。对品种特异性的RAPD条带进行了胶回收、克隆和序列测定。根据测序结果设计了两对位点特异性引物来扩增这两个品种特异性条带（简称SCAR标记Ⅰ和Ⅱ）,检测这两个SCAR标记在“新吉富”、“吉富”以及国内外7个养殖品系中的出现频率。SCAR标记Ⅰ（553 bp）在“新吉富”群体中的出现频率为85.7%,而在其基础群体（“吉富”）中的出现频率仅为16.7%;SCAR标记Ⅱ（558 bp）在“新吉富”群体中的出现频率达到91.4%,但在其它7个养殖品系中的出现频率仅在0%～70%之间。为验证这两个标记的可靠性,检测了这两个标记在一个埃及罗非鱼野生群体中的出现频率,发现SCAR标记Ⅰ和SCAR标记Ⅱ的出现频率分别为10%和70%,远低于在“新吉富”群体中的出现频率。这两个SCAR标记在“新吉富”良种群体中的高出现频率,预示它们可能与生长性能相关QTL位点间存在连锁关系,显示SCAR标记技术对选育世代间的纵向追溯、以及选育良种群体与其它养殖品系间的横向鉴别有较好应用前景。