Cassini encounters Enceladus: background and the discovery of a south polar hot spot

The Cassini spacecraft completed three close flybys of Saturn's enigmatic moon Enceladus between February and July 2005. On the third and closest flyby, on 14 July 2005, multiple Cassini instruments detected evidence for ongoing endogenic activity in a region centered on Enceladus' south pole. The polar region is the source of a plume of gas and dust, which probably emanates from prominent warm troughs seen on the surface. Cassini's Composite Infrared Spectrometer (CIRS) detected 3 to 7 gigawatts of thermal emission from the south polar troughs at temperatures up to 145 kelvin or higher, making Enceladus only the third known solid planetary body-after Earth and Io-that is sufficiently geologically active for its internal heat to be detected by remote sensing. If the plume is generated by the sublimation of water ice and if the sublimation source is visible to CIRS, then sublimation temperatures of at least 180 kelvin are required.     

奥利亚罗非鱼3种C型溶菌酶基因的克隆及其序列分析

本研究结合RT-PCR和RACE法获得了奥利亚罗非鱼(Oreochromis aureus)三种C型溶菌酶基因C-1,-2和C-3的全长cDNA.3个基因的cDNA分别为581 bp、662 bp和695 bp,各编码143、156和143个氨基酸(GenBank accession No:EU913095,EU913094和EU836689),相互间氨基酸序列的同源性在63.9%~67.8%之间.3个基因均具有与其它物种C型溶菌酶相同的8个保守半胱氨酸残基和2个活性位点Glu~(35)和Asp~(52),可认为它们均为C型溶菌酶基因.在系统进化树中这3个基因首先与同属高等真骨鱼类的聚类,最后再与低等真骨鱼类的聚类,系统进化关系与传统鱼类分类地位相吻合,显示真骨鱼类C型溶菌酶的进化速度与物种的进化速度基本一致.蛋白分析软件分析显示这3个基因均具有C型溶菌酶的典型结构、相似的蛋白二、三级结构,推测应具有与C型溶菌酶相似的生理功能.但3个基因氨基酸序列间存在一定差异,其中C-1的等电点较低且碱性氨基酸较少,因此3种溶菌酶可能具有生理功能上的差异与分工.     

Comparison of antimicrobial resistance in generic Escherichia coli and Salmonella spp. cultured from identical fecal samples in finishing swine

The objectives of this study were to investigate the associations between antimicrobial resistance patterns in generic Escherichia coli and Salmonella spp. isolates recovered from identical pen pooled fecal samples, and to evaluate potential clustering of multiple isolates of these organisms within identical fecal samples. Up to 5 generic E. coli (n = 922 isolates) and Salmonella spp. (n = 922 isolates) isolates were obtained from each of 188 pen pooled fecal samples that had been collected from 45 finishing swine farms in Alberta in 2000, and tested for susceptibility to 15 antimicrobials. No isolates of either organism were resistant to 3rd generation cephalosporins or fluoroquinolones, which in Canada are considered antimicrobials of very high importance to human health. Approximately twice as many generic E. coli isolates as Salmonella spp. isolates were resistant to at least 1 antimicrobial. In addition, E. coli isolates showed more multidrug-resistance patterns. No significant association was observed between the resistance phenotypes of Salmonella spp. and E. coli at the fecal sample level. More clustering at the sample level was observed for proportions of antimicrobial resistance (AMR) in Salmonella spp. isolates than E. coli indicating that in future studies it might be sufficient to test fewer than 5 Salmonella spp. isolates per sample.     

温度和体重对双齿围沙蚕呼吸和排泄的影响

研究了不同温度和体重对双齿围沙蚕PerinereisaibuhitensisGrube呼吸和排泄的影响。试验设置7个温度梯度(10、12、16、20、24、27、29℃),沙蚕按体重分成S、M、L3组,平均体重分别为(0 40±0 19)、(1 00±0 22)、(2 00±0 50)g。结果表明:1)在10～27℃下,不同体重的沙蚕耗氧率均随温度的升高而增加,但当温度达到29℃时,各体重组的沙蚕耗氧率均明显下降;耗氧率(R)与体重(W)呈负幂函数关系R=aWb-1,其中a值为0 1182～0 3894,b值为-0 3672～-0 5971;2)体重和温度对耗氧率交互作用的方程式为R=0 01993+0 04323T-0 07663WT(F=5 85,P=0 01);3)方差分析表明,温度对排氨率的影响显著(F=3 651,P<0 05),体重对排氨率的影响未见显著。     

Prevalence of intestinal parasites in dogs in some urban and rural areas of Hungary

A total of 490 canine faecal specimens collected in the eastern and northern regions of Hungary were examined for helminth eggs. From the results it appears that more than 50% of the dogs were infected with at least one parasite species. The prevalence of eggs (%) in the two regions was as follows: Toxocara canis (24.3-30.1); Trichuris vulpis (20.4-23.3); Ancylostomatidae (8.1-13.1); Capillaria spp. (0-7.3); Toxascaris leonina (2.1-0); Taenia-type (2.8-2.4); Dipylidium caninum (0.4-1); coccidia (3.5-3.4). Of the positive dogs, 8.5-18.1% harboured two or more species of parasites. The prevalence of parasitic infection was also evaluated according to the maintenance, feeding, and age of the animals. The significance of zoonotic diseases (echinococcosis, toxocarosis, ancylostomatidosis) caused by intestinal helminths makes it necessary to know the infection status of domestic dogs and to take measures for control.     

Factors associated with Echinococcus multilocularis infection in coyotes in southern Ontario

Echinococcus multilocularis was recently reported in wild canids across southern Ontario, a newly recognized endemic area in Canada. In such areas, a comprehensive understanding of factors associated with infection in definitive hosts (wild canids) is critical for mitigating risk of transmission to humans. However, little is known about the transmission dynamics of the parasite in definitive hosts for this region. A study was therefore carried out to investigate the association of host‐level (sex, body condition), environmental (southern Ontario region, land cover), temporal (season, hunting season, calendar year) and extraneous factors (submitter type) with E. multilocularis infection in coyotes in southern Ontario. Between November 2015 and March 2017, 416 coyotes were collected from across the region as part of a study that investigated the prevalence and distribution of the parasite in wild canids; approximately 24% of coyotes were positive for E. multilocularis. Associations between infection and factors of interest were assessed via a mixed‐effects logistic regression model with a random intercept for submitter to account for clustering. Coyotes with poor body condition were at greater odds of E. multilocularis infection than those in good condition (odds ratio [OR] 2.14; 95% CI: 1.08–4.26; p = .030). A negative association was observed between infection in coyotes and the proportion of natural land in a coyote's estimated home range (OR: 0.67; 95% CI: 0.52–0.85; p = .001). Coyotes from the western region of southern Ontario had lower odds of infection compared to coyotes from the central region (OR: 0.26; 95% CI: 0.12–0.55; p < .001). These results can be used to help guide future public health prevention strategies for human alveolar echinococcosis.     

Infrared observations of the jovian system from voyager 1

The infrared spectroscopy and radiometry investigation has obtained spectra of Jupiter and its satellites between approximately 180 and 2500 cm(-1) with a spectral resolution of 4.3 cm(-1). The Jupiter spectra show clear evidence of H(2), CH(4) C(2)H(2), C(2)H(6), CH(3)D, NH(3), PH(3), H(2)O, and GeH(4). A helium concentration of 0.11 +/- 0.03 by volume is obtained. Meridional temperature cross sections show considerable structure. At high latitudes, the stratosphere is warmer in the north than in the south. The upper troposphere and lower stratosphere are locally cold over the Great Red Spot. Amalthea is warmer than expected. Considerable thermal structure is observed on Io, including a relatively hot region in the vicinity of a volcanic feature.     

Infrared observations of the saturnian system from voyager 2

During the passage of Voyager 2 through the Saturn system, infrared spectral and radiometric data were obtained for Saturn, Titan, Enceladus, Tethys, Iapetus, and the rings. Combined Voyager 1 and Voyager 2 observations of temperatures in the upper troposphere of Saturn indicate a seasonal asymmetry between the northern and southern hemispheres, with superposed small-scale meridional gradients. Comparison of high spatial resolution data from the two hemispheres poleward of 60 degrees latitude suggests an approximate symmetry in the small-scale structure, consistent with the extension of a symmetric system of zonal jets into the polar regions. Longitudinal variations of 1 to 2 K are observed. Disk- averaged infrared spectra of Titan show little change over the 9-month interval between Voyager encounters. By combining Voyager 2 temperature measurements with ground-based geometric albedo determinations, phase integrals of 0.91 +/- 0.13 and 0.89 +/- 0.09 were derived for Tethys and Enceladus, respectively. The subsolar point temperature of dark material on Iapetus must exceed 110 K. Temperatures (and infrared optical depths) for the A and C rings and for the Cassini division are 69 +/- 1 K (0.40 +/- 0.05), 85 +/- 1 K (0.10 +/- 0.03), and 85 +/- 2 K (0.07 +/- 0.04), respectively.