Replication of live-attenuated vaccine strains of bluetongue virus in orally infected South African Culicoides species

Field-collected South African Culicoides (Diptera, Ceratopogonidae) were fed on sheep blood containing 16 live-attenuated vaccine strains of bluetongue virus (BTV) comprising serotypes -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -16 and -19. After 10 days extrinsic incubation at 23.5 degrees C, 11 and seven of the 16 BTV serotypes used were recovered from Culicoides (Avaritia) imicola Kieffer and Culicoides (A.) bolitinos Meiswinkel, respectively. One serotype was also recovered from Culicoides (Remmia) enderleini Cornet & Brunhes. Bluetongue virus recovery rates and the mean titres for most serotypes were significantly higher in C. bolitinos than in C. imicola. Significant differences were found in virus recovery rates from Culicoides species fed on blood containing similar or identical virus titres of different BTV serotypes. In addition, we demonstrated that a single passage of live-attenuated BTV-1, -2, -4, -9 and -16 through the insect vector, followed by passaging in insect cells, did not alter its infectivity for C. imicola and that the oral susceptibility of C. imicola to the attenuated vaccine strains of BTV-1, -4, -9 and -16 remained similar for at least three consecutive seasons.     

Oxidative metabolic profiles of Brucella strains isolated from marine mammals: contribution to their species classification

Since the 1990s, Brucella strains not matching the characteristics of any of the six conventional species have been isolated worldwide from marine mammals. In this study, 31 Brucella strains isolated from various marine mammals were examined for their oxidative metabolic pattern on 12 amino-acid and carbohydrate substrates. Three main oxidative profiles different from those of the Brucella terrestrial mammal strains were identified for the marine mammal strains: one gathering strains isolated from pinnipeds and two gathering strains from cetaceans. Thus, both oxidative metabolism results and previous molecular studies are in agreement with the proposal of two new Brucella species, Brucella pinnipediae and Brucella cetaceae, to classify the Brucella strains isolated from marine mammals, and are also in accordance with a classification of species of the Brucella genus based on host preference.     

木质纤维素预处理抑制物产生及脱除方法的研究进展

利用纤维素酶将木质纤维素降解成可发酵性糖,然后发酵生产氢气、乙醇、丁醇等生物燃料及高附加值产品,是当今全球研究的热点。预处理是生物质转化过程中至关重要的步骤,而预处理过程中产生的抑制物对木质纤维素后续的酶解和发酵微生物有负面影响。因此了解预处理方法及其过程中产生的抑制物及脱除方法是能否高效转化生物质的基础。文中首先介绍了木质纤维素常用的两类预处理方法即化学法和物理化学法。随后阐述了不同抑制物的产生及其抑制机制,并重点介绍了多种脱毒方法。最后展望了脱除木质纤维素预处理抑制物的研究趋势:应用交联聚乙烯亚胺和金属有机骨架化合物等新型材料脱除抑制物或通过基因工程、代谢工程技术等构建抑制物耐受性菌株等。     

Photosynthetic characteristics of two Cylindrospermopsis raciborskii strains differing in their toxicity

We studied the growth and photosynthetic characteristics of a toxic (CS506) and a nontoxic strain (CS509) of the bloom‐forming cyanobacterium Cylindrospermopsis raciborskii grown under identical experimental conditions. When exposed to light‐saturating growth conditions (100 μmol photons · m^?2 · s^?1), values for maximal photosynthetic capacity (P_max) and maximum quantum yield (F_v/F_m) indicated that both strains had an equal ability to process captured photons and deliver them to PSII reaction centers. However, CS506 grew faster than CS509. This was consistent with its higher light requirement for saturation of photosynthesis (I_k). Greater shade tolerance of CS509 was indicated by its higher ability to harvest light (α), lower photosynthetic light compensation point (I_c), and higher chlorophyll a to biovolume ratio. Strain‐specific differences were found in relation to non‐photochemical quenching, effective absorption cross‐sectional area of PSIIα‐centers (σPSIIα), and the antenna connectivity parameter of PSIIα (J_conPSIIα). These findings highlighted differences in the transfer of excitation from phycobilisome/PSII to PSI, on the dependence on different pigments for light harvesting and on the functioning of the PSII reaction centers between the two strains. The results of this study showed that both performance and composition of the photosynthetic apparatus are different between these strains, though with only two strains examined we cannot attribute the performance of strain 506 to its ability to produce cylindrospermopsins. The emphasis on a strain‐specific light adaptation/acclimation is crucial to our understanding of how different light conditions (both quantity and quality) can trigger the occurrence of different C. raciborskii strains and control their competition and/or dominance in natural ecosystems.     

Hairy root induction and plant regeneration of medicinal plant Dracocephalum kotschyi

An efficient hairy root induction system for an important endangered medicinal plant, Dracocephalum kotschyi, was developed through Agrobacterium rhizogenes-mediated transformation by modifying the co-cultivation medium using five bacterial strains, A4, ATCC15834, LBA9402, MSU440, and A13 (MAFF-02-10266). A drastic increase in transformation frequency was observed when a Murashige and Skoog medium lacking NH₄NO₃ KH₂PO_4, KNO₃ and CaCl₂ was used, resulting in hairy root induction frequencies of 52.3 %, 69.6 %, 48.6 %, 89.0 %, and 80.0 % by A4, A13, LBA9402, MSU440, and ATCC15834 strains, respectively. For shoot induction, hairy roots and unorganized tumors induced by strain ATCC15834 were placed on an MS media supplemented with 0.1, 0.25, 0.5, and 1 mg/l BA plus 0.1 mg/l NAA. The high frequency of shoot regeneration and number of shoot were obtained in the medium containing 0.25 mg/l BA and 0.1 mg/l NAA. Root induction occurred from the base of regenerated shoots on the MS medium supplemented with 0.5 mg/l IBA after 10 days.     

番茄青枯雷尔氏菌强致病力菌株变异的研究

为研究番茄青枯雷尔氏菌强致病力菌株的变异,探索了继代培养、在NB培养基上不同时间培养、不同pH处理7d和15d、不同温度处理1h后对强致病力菌株变异的影响。结果表明:随着继代培养的培养代数增加,平均弱化指数成增大趋势,在第10代出现了无致病力菌株;在NB培养基上培养15d时,强致病力菌株已完全转化为不确定菌株和无致病力菌株,在培养30d时,强致病力菌株几乎完全转化为无致病菌株;pH7.0时,处理7d和15d后,强致病力菌株比例均为最大,分别为93.33%和92.22%,pH5.8时,强致病力菌株比例最低,分别为46.67%和31.11%;用不同温度处理强致病力菌株发现,温度50℃时,菌株死亡,温度40℃时,活菌数显著低于其他(4~30℃)处理,强致病力菌株比例为4~40℃所有处理中最低。     

不同发酵方式和保存方法对3种生防菌活菌量的影响

为明确3株优良生防菌SC11、153、FO47在不同发酵方法和保存条件下活菌量变化规律,采用活菌平板计数法,测定3种生防菌12个月内活菌量变化及3种生防菌粉剂发酵初期和12月保存期后对茄子黄萎病的温室盆栽防效。结果表明,SC11、 153和FO47菌粉于4 ℃密封保存12个月后活菌量与其初始活菌量差异不显著（P<0.05）;FO47菌粉在4 ℃保存12个月后活菌量高于初始活菌量（P<0.05）;3种生防菌发酵液初始活菌量较菌粉低1～2个数量级,在保存期60 d内活菌量急剧下降,第6个月时接近于0。3种生防菌粉存放12个月后对茄子黄萎病仍保持较高的抑菌活性。说明,固体发酵菌粉可以得到较高数量级的初始活菌量,3种生防菌菌粉4 ℃密封保存12个月后活菌量及抑菌活性不变,且FO47菌粉活菌量略有上升;发酵液不利于生防菌的长期保存。     

The Genome Sequence of the Highly Acetic Acid-Tolerant Zygosaccharomyces bailii-Derived Interspecies Hybrid Strain ISA1307, Isolated From a Sparkling Wine Plant

In this work, it is described the sequencing and annotation of the genome of the yeast strain ISA1307, isolated from a sparkling wine continuous production plant. This strain, formerly considered of the Zygosaccharomyces bailii species, has been used to study Z. bailii physiology, in particular, its extreme tolerance to acetic acid stress at low pH. The analysis of the genome sequence described in this work indicates that strain ISA1307 is an interspecies hybrid between Z. bailii and a closely related species. The genome sequence of ISA1307 is distributed through 154 scaffolds and has a size of around 21.2 Mb, corresponding to 96% of the genome size estimated by flow cytometry. Annotation of ISA1307 genome includes 4385 duplicated genes (∼90% of the total number of predicted genes) and 1155 predicted single-copy genes. The functional categories including a higher number of genes are ‘Metabolism and generation of energy’, ‘Protein folding, modification and targeting’ and ‘Biogenesis of cellular components’. The knowledge of the genome sequence of the ISA1307 strain is expected to contribute to accelerate systems-level understanding of stress resistance mechanisms in Z. bailii and to inspire and guide novel biotechnological applications of this yeast species/strain in fermentation processes, given its high resilience to acidic stress. The availability of the ISA1307 genome sequence also paves the way to a better understanding of the genetic mechanisms underlying the generation and selection of more robust hybrid yeast strains in the stressful environment of wine fermentations.     

297例浅部真菌病临床及病原菌菌种分析

目的 探讨皮肤浅部真菌病致病真菌菌种的构成.方法 对297例真菌涂片阳性和培养阳性的浅部真菌病患者,取标本进行分离培养及菌种鉴定,培养阳性标本在形态学上不能准确鉴定的,进行梅里埃API 20C AUX酵母菌鉴定试剂盒或核糖体DNA （rDNA） ITS区序列测定,确切鉴定菌种.使用SPSS 17.0统计软件对于结果进行统计分析.结果 共分离培养出致病菌13种,其中红色毛癣菌86株（29.0％）,须癣毛癣菌68株（22.9％）,念珠菌属59株（19.9％）,暗色真菌属13株（4.4％）,曲霉菌属13株（4.4％）,红酵母菌12株（4.0％）,青霉菌属9株（3.0％）,毛霉菌9株（3.0％）,犬小孢子菌5株（1.7％）,浅白隐球菌3株（1.0％）,毛孢子菌属2株（0.7％）,絮状表皮癣菌1株（0.3％）,混合感染17株（5.7％）.结论 本地区浅部真菌病以甲癣为主,主要致病真菌是红色毛癣菌,但其他种类真菌感染尤其是念珠菌属有明显上升趋势.     

Direct noninvasive measurement and numerical modeling of depth-dependent strains in layered agarose constructs

Biomechanical factors play an important role in the growth, regulation, and maintenance of engineered biomaterials and tissues. While physical factors (e.g. applied mechanical strain) can accelerate regeneration, and knowledge of tissue properties often guide the design of custom materials with tailored functionality, the distribution of mechanical quantities (e.g. strain) throughout native and repair tissues is largely unknown. Here, we directly quantify distributions of strain using noninvasive magnetic resonance imaging (MRI) throughout layered agarose constructs, a model system for articular cartilage regeneration. Bulk mechanical testing, giving both instantaneous and equilibrium moduli, was incapable of differentiating between the layered constructs with defined amounts of 2% and 4% agarose. In contrast, MRI revealed complex distributions of strain, with strain transfer to softer (2%) agarose regions, resulting in amplified magnitudes. Comparative studies using finite element simulations and mixture (biphasic) theory confirmed strain distributions in the layered agarose. The results indicate that strain transfer to soft regions is possible in vivo as the biomaterial and tissue changes during regeneration and maturity. It is also possible to modulate locally the strain field that is applied to construct-embedded cells (e.g. chondrocytes) using stratified agarose constructs.