Strains In Guangzhou Research Articles

Life History Characteristics of Three Strains of Brachionus calyciflorus (Rotifera) at Different Temperatures

ABSTRACT Three strains of Brachionus calyciflorus Pallas (Qingdao, Wuhu, and Guangzhou strains), were cultured at 20°C, 25°C, and 30°C with 3.0x106 cells/ml of Scenedesmus obliquus to investigate their responses in life history characteristics relative to temperature. The population growth rates of both Guangzhou and Wuhu strains increased linearly at similar rates with the rise of temperature, but that of the Qingdao strain was not significantly influenced by temperature. The egg sizes of both Wuhu and Qingdao strains at 20°C and 25°C were similar and were larger than that at 30°C. The egg sizes of Guangzhou strain at 20°C and 25°C were also similar but were smaller than that at 30°C. The durations of juvenile periods of all the three B. calyciflorus strains were significantly reduced at similar rates with the rise of temperature. The responses to temperature in other life history parameters, including body size, durations of reproductive and post-reproductive periods, lifespan, net reproductive rate, and reproductive effort, differed among the three strains.

Study on the genotypes of TEM-like and SHV-like extended-spectrum beta-lactamases in clinical isolates of Gram-negative bacilli in Guangzhou

目的 调查广州地区临床分离的革兰阴性杆菌中TEM和SHV型超广谱β内酰胺酶(ESBLs)的主要基因型别及其流行情况.方法按照美国临床实验室标准化委员会2001年标准筛选广州地区临床分离菌株的ESBLs表型.用聚合酶链反应(PCR)扩增法和DNA测序法进行ESBLs基因序列分析.结果2001年7月-2003年8月本研究小组从广州地区13家大型医院中共获得3500株无重复地连续地革兰阴性杆菌分离菌株,其中ESBLs表型阳性为1084株,占31%.PCR扩增结果显示,blaTEM和blaSHV基因的总阳性率在本地区临床分离的革兰阴性杆菌中分别为24%和10.8%,同时检出TEM和SHV型ESBLs的菌株数为128株,阳性率为3.7%.序列分析进一步证实了TEM型bla均为TEM-1类非ESBLs,包括TEM-1、TEM-1B、TEM-1D和TEM-1F.而本地区的SHV型bla几乎均为SHV类ESBLs(SHV-1型仅占7.2%,获得22株),其中以SHV-12/5a阳性率最高(50%,152/304).各基因型的菌株分布结果显示,TEM型基因主要分布于大肠埃希菌中,占53%(340/641);而SHV型基因则主要分布于肺炎克雷伯菌中,占57.9%(176/304).结论本地区SHV类ESBLs较为常见,其中尤以SHV-12/5a为主,本地区暂无TEM类ESBLs.本地区可能存在SHV-12/5a流行菌株.对于ESBLs的检测,临床常用方法可能存在较高的漏检率和误检率。

Resting Egg Production of Brachionus calyciflorus (Rotifera) at Different Water Temperatures

ABSTRACT Laboratory populations of three strains of Brachionus calyciflorus Pallas (Qingdao, Wuhu, and Guangzhou strains) collected respectively from River Huanghe, River Changjiang and River Zhujiang basins of China were cultured at 20°C 25°C, and 30°C with 3.0x106cells/ml of Scenedesmus obliquus to investigate their resting egg productions. There were significant effects of both temperature and strain, independently and in interaction on resting egg production. The resting egg productions of the rotifers at 20°C and 25°C were not significantly different, but were lower than those at 30°C. Resting egg productions of the Qingdao and Wuhu strains were not significantly different, but were higher than that of the Guangzhou strain. The total production of fertilized mictic females depended on the production of total females and the mixis and fertilization rates. Among all the strain-temperature combinations, the resting egg productions of the Wuhu and Qingdao strains at 30°C were the highest (1202.33±102.50 and 1258.67±403.45 ind./10ml/12d, respectively).

The impact of traveling to endemic areas on the spread of hepatitis E virus infection: epidemiological and molecular analyses.

Traveling to endemic areas carries a risk of hepatitis E virus (HEV) infection, but no molecular analysis to document sources of infection is available. Eighteen (38%) of 47 patients with acute non-A, non-B, non-C hepatitis were positive for antibody to HEV (anti-HEV), and 9 (50%) of these were also positive for serum HEV RNA by polymerase chain reaction following reverse transcription. Only 1 (5%) of the 21 patients with acute hepatitis A was positive for HEV RNA. Travel to endemic areas (mostly to China; odds ratio, 22.2; 95% confidence interval, 4.7-105.8) and deeper jaundice (odds ratio, 5.2; 95% confidence interval, 1.01-27.2) were the only factors associated with HEV infection in multivariate analysis. The two HEV isolates from two patients who had traveled to China and the HEV isolate from a patient whose travel history was obscure formed a monophyletic group with the isolates from Guangzhou. The HEV isolates from our patients show a homology of 72% to 78% in nucleotide sequence with the Burma, Beijing, India, Pakistan, and Xiangjiang strains; a homology of 81% to 91% with the Guangzhou strains; and a homology of 76% with the Mexico strain. The close relationship between the Taiwan isolates and the Guangzhou strains was further supported by the short Kimura's two-parameter distances among them. In summary, HEV infection does occur in this area. Epidemiological and molecular analyses strongly indicate that most cases of HEV infection originated from travel to HEV-endemic areas.