In vitro studies of haemolysis by Leptospira interrogans serovars pomona and ballum

Washed and unwashed red blood cells (RBC) from young calves, adult cattle, hamsters and humans were incubated with Leptospira interrogans serovars pomona and ballum. Washed cells suspended in saline were always haemolysed while unwashed cells and those which were washed and resuspended in plasma were never haemolysed, despite the presence of large numbers of organisms within the culture supernatant. Pomona produced greater haemolysis of cattle and human RBC than did ballum, but with hamster RBC ballum produced greater haemolysis than did pomona. A group of 6- to 9-month-old cattle infected with pomona showed no signs of clinical disease and RBC taken from them before infection and during the development of antibodies to pomona were haemolysed by pomona only after the cells were washed. Plasma therefore appears to have a protective function. This in vitro protective function of plasma even extended to plasma from young seronegative calves.     

Zur Taxonomie einiger wirtschaftlich wichtiger Drahtwürmer

Ohne Zusammenfassung Mit 7 Abbildungen     

韩国人口政策及对中国农村人口政策的启示

人口政策是一个国家或地区用采影响和干预人口运动过程以及人口因素发展变化的法规、条例和措施的总和.韩国的人口政策经历了由控制人口增长的计划生育政策到鼓励人口增长的新人口政策的转变,该政策成功控制了人口的快速增长,缓解了人口与经济、社会资源、环境之间的矛盾,但也引起了人口老龄化、出生婴儿性别比失调等一系列社会问题.这些问题也正在中国农村上演,如能借鉴立法先行、大力发展社会福利事业、善于运用经济杠杆等经验,对维持中国农村人口的低出生率,控制人口老龄化等具有积极的意义.     

Sectioned pelvic fin ray ageing of muskellunge Esox masquinongy from a Virginia river: comparisons among readers, with cleithrum estimates, and with tag–recapture growth data

Abstract  The potential utility of pelvic fin rays as ageing structures was evaluated for southern US muskellunge Esox masquinongy Mitchill populations by comparing age estimates among three readers and against cleithrum estimates, and by comparing observed length changes of tagged fish with changes predicted from growth equations based on pelvic fin ray age estimates. Mean coefficient of variation in age estimates among all readers and between the two readers with prior ageing experience was 17.8% and 5.6%, respectively. Exact and within 1-year agreement rates between pelvic fin rays and cleithra were 76% and 100%, respectively. Mean (± 2 SE) estimated absolute error between observed and predicted length changes for 13 tagged muskellunge was 30 ± 14 mm. This evaluation indicated that pelvic fin rays may prove to be a useful, non-lethal method for ageing muskellunge in southern US waters. Validation studies are still needed to ensure that growth rings form consistently throughout fish's life span.