用分子遗传学及免疫学方法控制鱼类寄生性甲藻

寄生性甲藻,例如Amyloodiniumocellatum,给鱼类养殖带来严重的危害。虽然,近年来针对Amyloodinium的药物治疗有一些新的进展,如使用氯喹、过氧化氢和3,N泛影葡胺拉沙洛西等,然而,含铜类药物仍然是最有效的。近年来分子遗传学和免疫学的进展,使得我们能够更好地了解寄生性甲藻的流行病学及其防治方法。分子系统学研究认为某些寄生性甲藻,如Amyloodiniumocellatum,可以聚类为高度同源性的一支;而其它的如Piscinoodiniumpillulare,则可以认为不止一种或更高的分类阶元。这些分子分析也发展出一些高灵敏的检测技术,可以检测出环境中极少量的寄生性甲藻。通过对Amyloodinium的免疫学研究表明,鱼类能对寄生物的感染产生强烈的高度特异的保护性免疫应答,其中主要是抗体介导的免疫应答。鱼体皮肤和鳃也能表达内源非特异性多肽抗生素(类组蛋白),它们能对Amyloodinium造成致命的破坏。利用这些特异或非特异的免疫防御,将更有助于我们控制这些具有严重危害性的寄生性甲藻     

Changes in Photosynthetic Electron Transport in Potato Cultivars with Different Field Resistance after Infection with Phytophthora infestans

The estimation of field resistance of potato cultivars to Phytophthora infestans are usually carried out in expensive and time consuming field experiments over several years. Therefore, a procedure is required for the fast and objective determination of qualitative and quantitative field resistance of new cultivars. This study correlated level of field resistance to P. infestans in leaf discs or leaflets of various potato cultivars to characteristic changes of Chlorophyll-a fluorescence (CF) parameters F _m (maximal fluorescence) and F _v (maximal variable fluorescence). Two different inocula, both containing virulence genes 1-11 were tested. The results were achieved when leaf discs from greenhouse or field plants were each inoculated with a P. infestans spore suspension and incubated for 24 h. In field measurements, comparable results were obtained 48 h after inoculation. The estimation of field resistance by measuring specific CF parameters could be an economical and rapid procedure to reduce or substitute visual lesion assessment for determining cultivar field resistance.     

Marine pollution and coral reefs

Coral reefs are exposed to many anthropogenic stresses increasing in impact and range, both on local and regional scales. The main ones discussed here are nutrient enrichment, sewage disposal, sedimentation, oil-related pollution, metals and thermal pollution. The stress comprising the main topic of this article, eutrophication, is examined from the point of view of its physiological and ecological mechanisms of action, on a number of levels. Nutrient enrichment can introduce an imbalance in the exchange of nutrients between the zooxanthellae and the host coral, it reduces light penetration to the reef due to nutrient- stimulated phytoplankton growth, and, most harmful of all, may bring about proliferation of seaweeds. The latter rapidly outgrow, smother and eventually replace, the slow-growing coral reef, adapted to cope with the low nutrient concentrations typical in tropical seas.
Eutrophication seldom takes place by itself. Sewage disposal invariably results in nutrient enrichment, but it also enriches the water with organic matter which stimulates proliferation of oxygen-consuming microbes. These may kill corals and other reef organisms, either directly by anoxia, or by related hydrogen sulfide production. Increased sediment deposition is in many cases associated with other human activities leading to eutrophication, such as deforestation and topsoil erosion.
Realistically achievable goals to ensure conservation, and in some instances, rehabilitation of coral reefs are listed.