医学寄生虫实验教学中标本短缺解决办法的尝试

为改变目前寄生虫学实验教学标本短缺、试验内容及形式不能满足临床医学生未来从医需要的现状,近年来在寄生虫学实验教学中实施了标本、活虫体、寄生虫感染动物模型、现场调查相结合的寄生虫学实验教学新模式.

Effects of Some Management Practices on Electron Transport System (ETS) Activity in Paddy Soil

Electron transport system (ETS ) / dehydrogenase activity in a paddy field soil was measured under a variety of incubation conditions using the reduction of 2- (p-iodophenyl- 3- (p-nitrophenyl ) -5- phellyl tetrazolium chloride (INT) to iodonitrotetrazolium formazan (INTF). The results exhibited a high positive correlation between the ETS activity and the incubation temperature and soil moisture. Dehydrogenase/ETS activity displayed a negative correlation with insecticide concentrations, and the activity affected adversely as the concentration of the insecticide increased. The higher doses, 5 and 10 field rates (1 field rate ~ 1500 mL ha-1), of insecticide significantly inhibited ETS activity, while lower rates failed to produce any significant reducing effect. Inorganic N (as urea) of concentrations from 0 to 100 ug N g-1 soil showed a positive response to ETS activity. However, at concentrations of 200 and 400 ug N g-1, the activity was reduced significantly.

In-vitro and In-vivo Anti-trypanosomal Activity of Terminalia chebula Retz Dried Fruits

African trypanosomosis had caused lots of havocs to both humans and animals over a century with successes and failure in curtailing it. This study was aimed at screening medicinal plant, Terminalia chebula dried fruits against Trypanosoma evansi for trypanocidal activity. Twenty grams of powdered Terminalia chebula dried fruits was cold extracted with methanol. Obtained MPE （methanolic plant extract） was in vitro tested against Trypanosoma brucei （1 × 10^6 trypanosomes/mL of the medium in each ELISA plate wells） at concentrations （250～1,000 μg/mL） on Vero cells grown in DMEM （Debecco＇s Modified Eagle Medium） in appropriate conditions for trypanocidal activity. In-vitro cytotoxicity test of MPE of Terminalia chebula was conducted on Vero cells grown in DMEM. In-vivo assay for trypanocidal activity, each mouse was inoculated with 1 × 10^4/mL of trypanosomes and treated （48 h post inoculation） with MPE of Terminalia chebula at concentrations （12.5, 25, 50, 100 and 200 mg/kg body weight） were administered at dose rate of 100 BL per mouse via intraperitoneal route to different groups of mice, 6 mice per concentration. In-vitro cytotoxicity test was done on Veto cells at concentrations （1.58～100 μg/mL） of MPE of Terminalia chebula. Results of in-vitro trypanocidal activity varied from immobilization, reduction and to the killing of the trypanosomes. At 250 μg/mL ofMPE ofTerminalia chebula dried fruits, there was significant trypanocidal activity at 4 h of incubation and trypanosomes were not detected in corresponding ELISA plate wells at 5 h of incubation, which was statistically equivalent to reference drug, diminazine aceturate （50 μL/mL） at 4 h of incubation. Results of in-vivo trypanocidal activity revealed that at concentrations （l 2.5～25 mg/kg body weight） of MPE of Terrninalia chebula, mice in these groups survived for 6 days. While at 50 and 100 to 200 mg/kg body weight, mice in these groups survived up to 7 and 8 days, respectively. In-vitro cytotoxicity test showed that all concentrations of MPE of Terminalia chenula and diminazine aceturate were cytotoxic to cells except at 1.56 μL/mL and 6.25 μL/mL. In conclusion, MPE of Terminalia chebula dried fruits possessed trypanocidal compounds. Further study （bioassay-guided purification） is required to know the full potential of Terrninalia chebula as future trypanocide candidate.

Optimization for Production of Intracellular Polysaccharide from Cordyceps ophioglossoides L2 in Submerged Culture and Its Antioxidant Activities in vitro

Cordyceps ophioglossoides is a valuable traditional medicinal material.We have found that intracellular polysaccharide(IPS) is the major biologically active ingredient in Cordyceps ophioglossoides.This study is the first time to optimize the yield of IPS from Cordyceps ophioglossoides.The optimal medium for IPS production consists of glucose 54.50 g·L·1,yeast powder 25.50 g·L·1,NaH2PO4 0.4 g·L·1 and K2HPO4 0.4 g·L·1.The suggested culture conditions are 24 ℃,initial pH 4.5 with a rotary speed of 120 r·min·1 for 168 h.The yield of IPS is 737.93 mg·L·1,which is 50% higher than the yield under the conditions prior to optimization.The anti-oxidative activities of IPS in Cordyceps ophioglossoides L2 are also characterized using various in vitro assay.The anti-oxidative activity may explain the reason why IPS from Cordyceps ophioglossoides can be used to fight against neurodegenerative dis-eases and menopausal symptoms.

Expansion of Small Terrestrial Mammals and Their Parasites into the Barun Valley (Makalu Mt. Region, Nepal Himalaya) Linked with Changes in Glaciation and Human Activities

The article is based on collection of small terrestrial mammals(Soriculus nigrescens,Episoriculus caudatus, Neodon sikimensis,Alticola stoliczkanus, Niviventer eha and Ochotona roylei) collected in the Barun Valley, east Nepal in the pre-monsoon period of 1973.Zoogeographic and ecological characteristics and altitudinal stratification of these species are analysed, depending both on abiotic(geomorphological and climatic) and biotic(vegetation, and human presence and activities)factors. All the captured mammals were examined for ecto- and endoparasities. Infestations of Trombiculid mites and Ixodid ticks were tightly linked to the local habitat where these ectoparasites must survive during their nonparasitic phase. Analysis of their occurrence completes the reconstruction of migration routes during the expansion of small mammals into the Barun Valley and the exacerbating influence of human activities(summer pasturing,mountaineering expeditions and trekking parties).An indicator of anthropogenic influence was the occurrence of synantropic flies. The potential medical importance of these findings is discussed.It is assumed a possible occurrence of arboviruses transmitted by ticks and also rickettsioses(transmitted by ticks and chigger mites). As far bacteriological infections, plague cannot be excluded.

Yield trait improvement of bay scallops following complete diallel crosses between different scallop stocks

This study describes the complete diaUel hybridization between newly introduced bay scallop stock （W） from Canada and local commercial stock （D） grown under laboratory conditions, in China. Larval survival and growth during all life stages （larvae, spat, and adult） were compared among hybrid （DW, WD） and purebred （DD, WW） populations. Significant heterosis was detected for survival during the larval stage （〉 1% of the mid-parent values）. The mean heterosis （Hm） varied in growth throughout the life span. More than 50% of the Hm values were positive and negative in the DW and WD groups, respectively. The influence of maternal effects and mating types （intrapopulation vs. interpopulation crosses） on growth for all life stages was not consistent. Larval survival did not differ significantly （P〉0.05） with maternal effect or mating type. In the harvest stage, shell length （SL）, shell height （SH）, shell width （SW）, and total weight （TW） were larger in the hybrid compared with the inbred groups. Positive Hm values were observed in SL （1.5%）, SW （5.8%）, and TW （12.3%）, and were more significant in the DW groups （6.1%, 4.5%, 6.8%, and 27.2%）. These results suggest that hybridization between two geographic populations is a good tool for improving bay scallop growth. However, unstable heterosis between the two populations requires further study.

Purification,Characterization and in vitro Anthelmintic Activity of a Neutral Metalloprotease from Laccocephalum mylittae

A neutral metalloprotease was purified from the cultured mycelia of Laccocephalum mylittae,an effective medicinal fungus widely used in anthelmintic therapy.The protease was purified to homogeneity with 31.85-fold purification and a final yield of 21.76%.The subunit molecular weight of the protease is about 40000 estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE).The optimum reaction pH and temperature are 7.5 and 50oC,respectively.The protease activity is largely enhanced by Ca2 +,but highly inhibited by tetrasodium ethylenediaminetetraacetate(EDTA),a metal-chelator,suggesting that the enzyme is a metalloprotease.The Michaelis-Menten constan Km and Vmax value for casein substrate are 6.09 mg·ml -1and 21.32μg·min -1·ml -1, respectively.In vitro anthelmintic tests of the protease exhibit distinct lethal effects on the third stage larvae(L3)of Ascaris suum.Scanning electron microscopy and SDS-PAGE analysis indicates that the proteolysis of larvae proteins caused by this protease may relate to the anthelmintic activity of L.mylittae.

Mesocosm Hatcheries Using Semi-intensive Methodologies and Species Diversification in Aquaculture

Mesocosm hatcheries using semi-intensive culture methodologies are characterized by large tanks （40 m3） for fish larvae production at low densities （2-8 larvae/L）, with live prey production within the tank supplemented by exogenous sources of feed. Due to the high biological quality of larvae produced and low level of technological input, these methodologies are regarded as an interesting option to meet the increasing fry demand from the aquaculture industry. This study aimed to describe the experience at Centro de Maricultura da Calheta, Madeira Island, Portugal, with the establishment of a mesocosm hatchery for the production of marine fish larvae. Production trials were initiated with gilthead seabream Sparus aurata. This larval species presented faster growth in total body length （TL） per day （TL = 3.7516e~ ~293day, R2 = 0.9404）, higher survival rate （SR = 31.9%） and comparable swimbladder inflation rates （SB = 90%） to those of larvae reared with intensive methodologies. High larval performance was obtained with two candidate species for aquaculture： the red porgy Pagruspagrus （TL = 3.212e~~39day, R2 = 0.995; SR = 15.3%; SB = 95.7%） and the white seabream Diplodus sargus （TL = 3.6355e~~413day, R2= 0.9824; SR = 25%; SB --- 100%）. Testing ofa 110 m3 mesocosm rearing tank with white seabream larvae revealed limitations associated to larger tanks namely, the amount and quality of live feed required daily. First trials with striped jack （Pseudocararoc dentex） larvae resulted in low larval survival （0.04%）, but the use of a white tank avoided culture management constraints related to positive phototropism. The present results suggest that a mesocosm using semi-intensive methodologies may contribute to species diversification and consequently, to the sustainable development of aquaculture.

The off-host survival and viability of a native and non-native fish louse （Argulus, Crustacea： Branchiura）

Fish ectoparasites are introduced to water bodies or aquaculture systems along with their hosts. Argulid fish lice can survive off-host for a given time, and in spite of quarantine measures might also be introduced via the transfer of water. However, they must cope with varying abiotic conditions without access to food. We investigated the effect of temperature （5 to 28℃） on the off-host survival time of Argulus japonicus, an invasive species which is apparently increasing its distribution, and compared this with the European A. foliaceus. A clear effect of temperature on the off-host survival time of all stages of both species was demonstrated. Larval and juvenile A. japonicus survived up to 9 days at 22℃ and in the case of adults up to 13 days at 15℃. By comparison, larval A. foliaceus survived up to 5 days at 15℃, adults up to 14 days at 9℃ and juveniles up to 7 days at 9℃ and 15℃. Thus, A. japonicus is more resistant to starvation at higher temperatures under controlled off-host conditions and A. foli- aceus is more resistant to starvation at lower temperatures. Infectivity of A. japonicus decreased linearly with the time spent off-host after 2 days for larvae and 4 days for adults. Temperature only had a significant effect on the infectivity of both develop- mental stages after 24 hours off-host between 13-23℃ for larvae and 13-18℃ for adults. In conclusion both species can potentially survive off-host pelods in water transports for up to 13-14 days as adults. Their survival is shorter as larvae. This study demonstrates that transportation of water has the potential to introduce Argulus species