Does streptobacillary arthritis reduce house mouse population density,activity and damage to sorghum crops?

An experiment to examine the effect of streptobacillary arthritis on mouse populations was conducted in maturing sorghum crops in mouse-proofed pens. There were three treatment pens and three control pens in which mice with and without clinical signs of streptobacillary arthritis were introduced, respectively. A constant mouse density (533 mice ha⁻¹) was introduced to the pens by releasing 12 mice in each pen. The sex ratio of introduced mice was also constant by releasing in each pen nine males and three females. Mean track index was lower in treatment pens than in control pens, indicating that streptobacillary arthritis reduced the activity of mice. However, this was not translated into a reduction in other population responses. Mean mouse density at harvest, percentage of female pregnant at harvest, yield loss caused by mice and a feeding index (oil card index) did not differ significantly between treatment and control groups. A plausible explanation for these findings was that mice with the clinical signs might be less active but were able to consume as much grains as mice without the clinical signs because food was in abundant supply.     

Morphological changes in carp epithelial cells infected with Aeromonas hydrophila

The in vitro interaction of Aeromonas hydrophila with epithehoma papillosum cells of carp (EPC) was studied. All the virulent and type strains invaded and multiplied inside EPC cells. Morphological changes were induced by the virulent and type strains during the processes of invasion and intracellular replication. Among the virulent group, strain PPD134/91 required the shortest time (30 min post-infection) to induce cytopathic effects in the EPC monolayers. The EPC cells infected with PPD 134/91 became retracted and condensed, lost their attachment abilities, and eventually disintegrated. Confocal microscopy revealed that tubular structures measuring 0.77 ± 0.19 μm appeared to connect the retracted EPC cells. The cytopathic effect was attributed to the growing and metabolically active bacteria. Avirulent strains such as L37 did not multiply nor induce cytopathic effects in the EPC monolayers.     

Applications of systems modeling in aquaculture

This paper deals with the applications of systems modeling in aquaculture. Different types of biological models and techniques of economic analysis such as optimization and simulation are discussed in the context of aquaculture production. Emphasis is on the applicability of such modeling techniques for production system design and operation management. Past modeling efforts for several aquatic species are reviewed and surveyed with a special discussion on an on-going modeling effort of prawn production in Hawaii.     

三黄占2号稻瘟病抗性与稻米直链淀粉含量的关系研究

以高抗稻瘟病、直链淀粉含量（AC）较高的三黄占2号和高感稻瘟病、AC较低的丽江新团黑谷衍生的重组自交系群体为研究材料，从性状的相关性和控制两性状的基因在染色体上的位置关系剖析稻瘟病抗性和稻米AC的内在关系。结果表明，两性状间没有显著的相关性。3个与AC相关的QTL分别被定位在第5、6和7染色体上，其加性效应均来自丽江新团黑谷，起降低AC的作用。比较这些QTL与先前对同一群体鉴定的稻瘟病抗性基因（主效基因和QTL）在染色体上的位置，表明控制这两性状的基因上没有紧密连锁关系, 亦没有显著的基因间互作。据此认为，通过亲本的合理选择和分子标记辅助选择可以把三黄占2号稻瘟病持久抗性与理想AC整合到同一品系中，育成优质、抗病的优良品种。     

Secretion of human interferons by yeast

Plasmids were constructed to direct synthesis of the human interferons IFN-alpha 1, IFN-alpha 2, and IFN-gamma in the yeast Saccharomyces cerevisiae. Expression of IFN genes containing coding sequences for secretion signals resulted in the secretion of IFN activity. A large proportion of the IFN-alpha 1 and IFN-alpha 2 isolated from the yeast cell growth media had the same amino termini as the natural mature interferons, suggesting a removal of the signal sequences identical to that of human cells. These results show that a lower eukaryote, such as yeast, can utilize and process a human signal sequence.