Characterization of fluoroquinolone resistance in Escherichia coli strains from ruminants.

Thirty-seven fluoroquinolone-resistant Escherichia coli strains from ruminants (according to Clinical and Laboratory Standards Institute guidelines) were screened by molecular methods for mutations in the quinolone resistance-determining region (QRDR) of the gyrA and parC genes and for the presence of the qnrA gene. One of the strains studied was an enterohemorrhagic E. coli (EHEC) strain potentially pathogenic for humans. Three E. coli strains resistant to enrofloxacin (minimal inhibitory concentration [MIC] = 2 microg/ml) but not to ciprofloxacin (MIC = 1 microg/ml) presented single mutations in the gyrA and parC genes, while 34 strains resistant to both fluoroquinolones presented double and single mutations in gyrA and parC, respectively (31 strains), or double mutations in gyrA and parC (3 strains). The EHEC strain presented a double amino acid substitution in the GyrA protein (Ser-83-->Leu and Asp-87-->Gly) and a double amino acid substitution in the ParC protein (Gly-78-->Cys and Ser-80-->Arg), one of which has not been previously described. The present study shows that most of the mutations in the QRDR of the gyrA and parC genes of fluoroquinolone-resistant E. coli strains from ruminants are the same as those seen in E. coli strains from other animal species and humans and that there are no differences in mutation patterns in the QRDR of E. coli strains from healthy ruminants and those with diarrhea. No strains carried qnrA, which indicates that this gene does not play an important role in the selection of fluoroquinolone-resistant E. coli strains from ruminants.     

Cataracts: when to refer

Unique stages of cataract development have been characterized in both human and animal lenses. These lens opacities impair visual acuity and are associated with inflammation. Total lens removal is typically followed by implantation of an artificial intraocular lens to restore vision. The success of this procedure is mainly dependent on the developmental stage of the cataract to be removed. This article reviews cataract development and provides the clinician with cataract referral criteria.     

Toxoplasma gondii infections in sheep in Sicily, southern Italy

The aim of the study was to determine the burden of Toxoplasma gondii-infections in sheep in Sicily, southern Italy and the risk factors for infection. Sera from 1961 sheep were collected just before slaughtering from 62 farms located in 8 out of 9 Sicilian administrative districts. The sera were analysed for Toxoplasma-specific IgG antibodies using commercially available enzyme-linked immunosorbent assay. Sheep less than 4 weeks old were further analysed by ELISA for Toxoplasma-specific IgM-antibodies. Data on farm size and location were obtained from slaughterhouse sanitary reports and through structured telephone interviews of the veterinary officers from public health districts. The overall seroprevalence of Toxoplasma-specific IgG-antibodies were 49.9% (937/1876) by ELISA. Eighty-seven (54/62) percent of the farms had at least one Toxoplasma-positive animal. All the farms fed the animals outdoor on pasture and only one was claiming organic farming. Having cats on the farm, age of the animals, farm size and the use of surface water sources for drinking were all significantly associated with T. gondii-infected animals on the farm. T. gondii infection in mutton used for human consumption is very prevalent, and eating unprocessed sheep and lamb meat has a high risk of transmitting infections to humans. The presence of cats on the farm, farm size and using surface water as drinking water for the animals were risk factors for infection in sheep, with age as a significant confounder.     

Disposition of plasma creatinine in non-azotaemic and moderately azotaemic cats

The objectives of this study were to compare assay methods for plasma creatinine (Pl-creat) in cats and to describe the disposition of creatinine and iohexol in 12 healthy and moderately azotaemic cats. Exogenous creatinine and iohexol were injected simultaneously by intravenous bolus, and repeated blood samples were taken to determine the pharmacokinetic parameters of each marker. Pl-creat was assayed by high-performance liquid chromatography (HPLC), Jaffé and enzymatic methods. The enzymatic method was shown to be more reliable than the Jaffé method. Two stereoisomers, exo- and endo-iohexol were identified. The plasma clearance of creatinine (2.3+/-0.66 ml/min/kg) was significantly higher (P<0.001) than that of exo-iohexol (1.7+/-0.40 ml/min/kg). The volume of distribution (447+/-97 ml/kg) and elimination half-life (181+/-77 min) of creatinine were also higher (P<0.001) than those of exo- and endo-iohexol. The estimated daily endogenous production of creatinine was 65+/-23 mg/kg. None of the pharmacokinetic parameters was changed by the azotaemic status of the animals.     

香草兰营养特性的研究

对海南不同生产水平的香草兰种植园植株的养分调查分析,及Ｎ,Ｐ,Ｋ,Ｃａ,Ｍｇ肥料的盆栽试验,研究香草兰的营养特性。结果表明,香草兰植株养分的吸收量以Ｋ〉Ｃａ〉Ｎ〉Ｍｇ〉Ｐ,叶片以Ｃａ〉Ｋ〉Ｎ〉Ｍｇ〉Ｐ;结果植株养分吸收量Ｎ：Ｐ：Ｋ：Ｃａ：Ｍｇ＝１．００：０．２４,１．３９：１．１８：０．４８,盆栽幼苗Ｎ：Ｐ：Ｋ：Ｃａ：Ｍｇ＝１．００：０．１０：１．３８：１．２３：０．３３;高产园植株Ｃａ,Ｐ含量极     

Effects of no‐take area size and age of marine protected areas on fisheries yields: a meta‐analytical approach

Marine protected areas (MPAs) are often promoted as tools for biodiversity conservation as well as for fisheries management. Despite increasing evidence of their usefulness, questions remain regarding the optimal design of MPAs, in particular concerning their function as fisheries management tools, for which empirical studies are still lacking. Using 28 data sets from seven MPAs in Southern Europe, we developed a meta‐analytical approach to investigate the effects of protection on adjacent fisheries and asking how these effects are influenced by MPA size and age. Southern European MPAs showed clear effects on the surrounding fisheries, on the ‘catch per unit effort’ (CPUE) of target species, but especially on the CPUE of the marketable catch. These effects depended on the time of protection and on the size of the no‐take area. CPUE of both target species and the marketable catch increased gradually by 2–4% per year over a long time period (at least 30 years). The influence of the size of the no‐take area appeared to be more complex. The catch rates of the entire fishery in and around the MPA were higher when the no‐take areas were smaller. Conversely, catch rates of selected fisheries that were expected to benefit most from protection increased when the no‐take area was larger. Our results emphasize the importance of MPA size on its export functions and suggest that an adequate, often extended, time frame be used for the management and the evaluation of effectiveness of MPAs.     

Optimal egg viability storage conditions in two commercial fairy shrimps (Crustacea: Branchiopoda: Anostraca) from Thailand

Optimal egg viability storage conditions for two commercial fairy shrimps, Branchinella thailandensis and Streptocephalus sirindhornae, were investigated. Eggs for each treatment were kept under eight different conditions at four different temperatures for 24 months. Every 2 months, representative eggs were hatched to evaluate hatching percentages. Low temperature and oxygen, darkness and dry conditions significantly influenced egg hatchability of both species. Undehydrated eggs hatchability in all conditions ranged from 0 to 10% in S. sirindhornae and 0 to 20% in B. thailandensis. Hatching percentages of B. thailandensis were higher than those of S. sirindhornae. Hatchability under all experimental regimes continuously decreased over time, except for dry eggs stored at ?18°C in dark‐anoxic conditions. Hatchability was markedly delayed in both species over time. We demonstrate that both species’ eggs can be stored at ?18°C at least for 24 months with high hatchability in B. thailandensis (80%) and S. sirindhornae (60%) under dry, dark, anoxic conditions.     

弯扭耦合柔性构件系统的变结构控制研究

对由柔性杆和柔性梁组成的两连杆柔性构件系统的弯扭耦合振动进行了研究,建立了此柔性系统的动力学方程。在柔性杆根部粘贴一只压电扭转致动器抑制柔性杆的扭转振动,在柔性梁根部粘贴一只压电弯曲致动器抑制柔性梁的弯曲振动。采用一种带有饱和环节及滤波器的滑模变结构控制策略,进行了实验研究。结果表明：施控后的系统是稳定的,弯扭的各阶模态均能得到有效抑制,柔性梁末端的振动位移能得到显著衰减。     

黄芪多糖对仿刺参非特异性免疫功能的影响

向刺参体腔中注射相同体积(500 μl)的无菌黄芪多糖溶液后第1、3、6 d,测定体腔液中溶菌酶、超氧化物歧化酶、碱性磷酸酶活性及补体C3的含量,研究黄芪多糖对刺参免疫系统的影响.每头刺参多糖含量分别达0.2、0.4、0.6 mg,溶菌酶、超氧化物歧化酶、碱性磷酸酶活性及补体C3含量均在注射后第3 d达到最高,且前3种指标以0.6 mg/头剂量组最高,分别达到232.25 U/ml,45.1 U/ml,966.5 nkat/L;C3含量则以0.4 mg/头剂量效果最好,达到0.09 g/L.经SPSS软件分析,均与对照组差异显著(P<0.05),表明黄芪多糖具有增强刺参免疫功能的作用.     

Early life history connectivity of Antarctic silverfish (Pleuragramma antarctica) in the Ross Sea

A recent population hypothesis for Antarctic silverfish (Pleuragramma antarctica), a critical forage species, argued that interactions between life history and circulation associated with glacial trough systems drive circumpolar distributions over the continental shelf. In the Ross Sea, aggregations of eggs and larvae occur under fast ice in Terra Nova Bay, and the hypothesis predicted that dispersing larvae encounter outflow along the western side of Drygalski Trough. The outflow advects larvae towards the shelf‐break, and mixing with trough inflow facilitates return toward the inner shelf. To examine the hypothesis, we compared samples of P. antarctica collected near Coulman Island in the outflow, along Crary Bank in the inflow, and a third set taken over the rest of the Ross Sea. We ruled out misidentification using an innovative genetic validation. Silverfish larvae comprised 99.5% of the catch, and the highest population densities were found in Drygalski Trough. The results provided no evidence to reject the population hypothesis. Abundance indices, back‐calculated hatching dates, length distributions and growth were congruent with a unified early life history in the western Ross Sea, constrained by cryopelagic early stages in Terra Nova Bay. By contrast, a sample in the Bay of Whales revealed much smaller larvae, suggesting either a geographically separate population in the eastern Ross Sea, or westward connectivity with larvae spawned nearby by fish sourced from troughs upstream in the Amundsen Sea. These results illustrate how hypotheses that integrate population structure with life history can provide precise spatial predictions for subsequent testing.