Studies of bovine Mycoplasma mastitis. 2. Testing of various culture media and culture methods for the isolation of Mycoplasma from milk samples]

The recipes Medium-I broth, Medium-B broth, and Weissenseemycoplasma broth as well as Medium-I agar, Medium-B agar, and MRL agar were tested for their applicability to culturing mycoplasma from milk samples, using the direct and indirect techniques. No dependable information on the occurrence of mycoplasma was obtainable from tested material unless several nutritive media and techniques were combined. Medium I, for which almost no imported substances were needed, was in no way inferior to common international nutritive substrates. Its use in conjunction with the indirect culturing technique is recommended for routine diagnosis.     

大棚黄瓜上烟粉虱成虫动态研究

对大棚烟粉虱成虫动态进行了研究.结果表明:烟粉虱成虫的聚集强度随密度的上升而下降;成虫始终处于聚集-扩散-再聚集-再扩散的动态过程之中.烟粉虱成虫在黄瓜植株上部充分展开的幼嫩叶片上数量最大;烟粉虱在大棚黄瓜上呈指数增长,其模型为Nt=2.5642e0.532t,(r=0.9858**).应用最优分割法将烟粉虱成虫动态划分为3个时期,分别为建立期、发展期和暴发期,在种群建立期对烟粉虱实施控制可以获得最佳的效果.     

Inheritance of seedling and adult plant resistance to leaf rust of selected Australian spring and English winter wheat varieties

Genetic studies were conducted to gain an understanding of the inheritance of adult plant resistance (APR) to leaf rust in six common wheat varieties. The Australian varieties ‘Cranbrook’ and ‘Harrier’ each carry two genes for APR to leaf rust. These genes are genetically independent of the seedling resistance genes Lr23 and Lrl7b, carried by the respective varieties. Adult plant resistance in ‘Suneca’ was conferred by at least two genes, in addition to the seedling genes Lr1 and Lrli. It is likely that the APRs in ‘Cranbrook’, ‘Harrier’ and ‘Suneca’ are conferred by uncharacterized gene(s). Tests of allelism confirmed that seedling resistances in the varieties ‘Avocet R’, ‘Hereward’, ‘Moulin’ and ‘Pastiche’ are conferred by Lrli. Adult plant resistance in the variety ‘Hereward’ was inherited monogenically, whereas varieties ‘Moulin’ and ‘Pastiche’ each carried two dominant genes. On the basis of rust specificity and pedigree analysis, it would seem likely that the APR genes in ‘Hereward’, ‘Moulin’ and ‘Pastiche’ are also currently uncharacterized.     

Hypersensitivity skin testing of lambs infested with the biting louse (Bovicola ovis)

Abstract Cockle, a defect of lamb's pelts, has recently been shown to be associated with infestation of lambs with the louse Bovicoh ovis. The mechanisms by which infestation with the louse leads to cockle are not known, but immunological hypersensitivity has been suggested. The objectives of our work are to determine if lambs respond immunologically to lice and, if so, whether hypersensitivity occurs. Preliminary results are presented here.     

Physiological processes associated with salinity tolerance in an alfalfa half‐sib family

We previously reported an alfalfa half‐sib family, HS‐B, with improved salt tolerance, compared to parental plants, P‐B. In this study, we conducted additional experiments to address potential physiological mechanisms that may contribute to salt tolerance in HS‐B. Vegetatively propagated HS‐B and P‐B plants were treated with a nutrient solution (control) or a nutrient solution containing NaCl (EC = 12 dS/m). Shoots and roots were harvested at various time points after treatment for quantification of proline, soluble sugar, and H₂O₂ using spectrophotometers. Subcellular localization and quantification of Na in roots were conducted using a Na⁺‐specific dye under a confocal microscope. HS‐B produced 86 and 89% greater shoot and root dry biomass, respectively, compared to parental plants, P‐B, under salinity in the greenhouse. Under saline conditions the HS‐B shoots accumulated 115% and roots 55% more soluble sugars than P‐B counterparts. The non‐saline HS‐B shoots, however, showed 72% less soluble sugars than the non‐saline P‐B plants. Under saline conditions HS‐B accumulated 39% less proline in shoots, while roots accumulated 56% more proline, compared to their P‐B parents. HS‐B plants also showed a greater reduction of stomatal conductance under mild saline stress. HS‐B shoots and roots contained 3–4 times less reactive oxygen species (H₂O₂) after salt treatment compared to P‐B plants. Sodium localization and distribution analysis using Na⁺‐specific dye revealed HS‐B plants accumulated 88% and 48% less Na⁺ in stele and xylem vessels compared to P‐B. The study provides insights into the potential mechanisms that may contribute to salt tolerance in HS‐B: maintaining RWC by accumulating soluble sugars while reducing transpiration, maintaining healthy status by reducing oxidative stresses, and preventing salt toxicity by reducing accumulation of Na⁺ inside root cells and xylem.     

Transpiration increases during the dry season: patterns of tree water use in eucalypt open-forests of northern Australia

Australian savannas exhibit marked seasonality in precipitation, with more than 90% of the annual total falling between October and May. The dry season is characterized by declining soil water availability and high vapor pressure deficits (up to 2.5 kPa). We used heat pulse technology to measure whole-tree transpiration rates on a daily and seasonal basis for the two dominant eucalypts at a site near Darwin, Australia. Contrary to expectations, transpiration rates were higher during the dry season than during the wet season, largely because of increased evaporative demand and the exploitation of groundwater reserves by the trees. Transpiration rates exhibited a marked hysteresis in relation to vapor pressure deficit, which was more marked in the dry season than in the wet season. This result may be attributable to low soil hydraulic conductivity, or the use of stored stem water, or both. Tree water use was strongly correlated with leaf area and diameter at breast height and there were no differences in transpiration between the species studied. These results are discussed in relation to scaling tree water use to stand water use.     

RGO/Nylon-6 composite mat with unique structural features and electrical properties obtained from electrospinning and hydrothermal process

In this work, the reduced graphene oxide (RGO) sheets were effectively uploaded through nylon-6 fibers using combined process of electrospinning and hydrothermal treatment. Good dispersion of graphene oxide (GO) with nylon-6 solution could allow to upload GO sheets through nylon-6 fibers and facilitate the formation of spider-wave-like nano-nets during electrospinning. GO sheets present on/into nylon-6 spider-wave-like nano-nets were further reduced to RGO using hydrothermal treatment. The impregnated GO sheets into nylon-6 nanofibers and their reduction during hydrothermal treatment were confirmed by FE-SEM, TEM, FT-IR and Raman spectra. The electrical characteristics of pristine nylon-6, GO/nylon-6 and RGO/nylon-6 nanofibers were investigated and it was found that RGO/nylon-6 composite mat had better electrical conductivity than others. The formation of spider-wave-like nano-nets as well as indirect route of incorporation of RGO sheets on electrospun nylon-6 mat may open a new direction for future graphene/polymer electronics.     

In silico prediction of Gallibacterium anatis pan-immunogens

The Gram-negative bacterium Gallibacterium anatis is a major cause of salpingitis and peritonitis in commercial egg-layers, leading to reduced egg production and increased mortality. Unfortunately, widespread multidrug resistance and antigenic diversity makes it difficult to control infections and novel prevention strategies are urgently needed. In this study, a pan-genomic reverse vaccinology (RV) approach was used to identify potential vaccine candidates. Firstly, the genomes of 10 selected Gallibacterium strains were analyzed and proteins selected on the following criteria; predicted surface-exposure or secretion, none or one transmembrane helix (TMH), and presence in six or more of the 10 genomes. In total, 42 proteins were selected. The genes encoding 27 of these proteins were successfully cloned in Escherichia coli and the proteins expressed and purified. To reduce the number of vaccine candidates for in vivo testing, each of the purified recombinant proteins was screened by ELISA for their ability to elicit a significant serological response with serum from chickens that had been infected with G. anatis. Additionally, an in silico prediction of the protective potential was carried out based on a protein property prediction method. Of the 27 proteins, two novel putative immunogens were identified; Gab_1309 and Gab_2312. Moreover, three previously characterized virulence factors; GtxA, FlfA and Gab_2156, were identified. Thus, by combining the pan-genomic RV approach with subsequent in vitro and in silico screening, we have narrowed down the pan-proteome of G. anatis to five vaccine candidates. Importantly, preliminary immunization trials indicated an in vivo protective potential of GtxA-N, FlfA and Gab_1309.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-014-0080-0) contains supplementary material, which is available to authorized users.