各隔离株旋毛虫感染性的研究

以旋毛虫国际标准种 :旋毛形线虫(Trichinella spiralis)和本地毛形线虫(Trichinella nativa )为对照 ,对黑龙江省猪、犬旋毛虫对大、小鼠和猪的感染性进行了比较研究。结果表明 :4个旋毛虫隔离株均对大鼠不易感 ,但相对犬旋毛虫和 T.nativa而言 ,猪旋毛虫和 T.spiralis对大鼠的感染性较高 (P <0 .0 1)。猪旋毛虫、 T.spiralis、犬旋毛虫、T.nativa在大鼠体内的繁殖力指数 (RCI)分别为 (35 .0 2± 8.37)、(32 .10± 7.77)和 (2 .90±1.71)、(2 .6 6± 2 .19)。 4个旋毛虫隔离株对小鼠和猪的感染性存在着明显差异 ,猪旋毛虫和T.spiralis对小鼠和猪的感染性较强 ,其在小鼠体内 RCI分别为 (137.4 1± 7.80 )和 (15 9.86±7.4 7) ,在猪体内的 RCI分别是 (385 .6 8±4 1.5 1)和 (30 0 .5 5± 12 .4 5 ) ;而犬旋毛虫和T.nativa对小鼠和猪的易感性差 ,其在小鼠体内 RCI分别是 (6 4.98± 5 .0 5 )和 (5 8.15±4 .6 9) ,在猪体内的 RCI分别为 (0 .0 6 4± 0 .0 31)和 (0 .0 33± 0 .0 33)。研究结果揭示 ,黑龙江省猪旋毛虫相当于旋毛形线虫 (Trichinellaspiralis) ,犬旋毛虫相当于本地毛形线虫(Trichinella nativa )     

Sporulation of Pyrenopeziza brassicae (light leaf spot) on oilseed rape (Brassica napus) leaves inoculated with ascospores or conidia at different temperatures and wetness durations

In controlled environment experiments, sporulation of Pyrenopeziza brassicae was observed on leaves of oilseed rape inoculated with ascospores or conidia at temperatures from 8 to 20°C at all leaf wetness durations from 6 to 72 h, except after 6 h leaf wetness duration at 8°C. The shortest times from inoculation to first observed sporulation ( l ₀), for both ascospore and conidial inoculum, were 11–12 days at 16°C after 48 h wetness duration. For both ascospore and conidial inoculum (48 h wetness duration), the number of conidia produced per cm² leaf area with sporulation was seven to eight times less at 20°C than at 8, 12 or 16°C. Values of Gompertz parameters c (maximum percentage leaf area with sporulation), r (maximum rate of increase in percentage leaf area with sporulation) and l ₃₇ (days from inoculation to 37% of maximum sporulation), estimated by fitting the equation to the observed data, were linearly related to values predicted by inserting temperature and wetness duration treatment values into existing equations. The observed data were fitted better by logistic equations than by Gompertz equations (which overestimated at low temperatures). For both ascospore and conidial inoculum, the latent period derived from the logistic equation (days from inoculation to 50% of maximum sporulation, l ₅₀) of P. brassicae was generally shortest at 16°C, and increased as temperature increased to 20°C or decreased to 8°C. Minimum numbers of spores needed to produce sporulation on leaves were ≈25 ascospores per leaf and ≈700 conidia per leaf, at 16°C after 48 h leaf wetness duration.     

Postponed germination of Puccinia recondita urediospores deposited on wheat seedlings. II. Infectivity of urediospores after postponed germination

Urediospores ofPuccinia recondita f.sp.tritici were applied to wheat seedlings. Inoculated plants were placed in a growth chamber to expose the spores to dry periods from zero to nine days at near-optimal temperatures (ca 18 °C). The dry period was followed by a wet period varying from 2 to 24 hours for germination of spores and infection of plants. Infection results were subjected to analysis of variance. The main effects dry period, wet period, and temperature were highly significant. The dry period×wet period interaction was significant. The interaction implied that the effects of post-detachment, ripening of germinable spores appeared in their resulting infectivity. There were two forms of post-detachment ripening, a slow ripening during the dry period and a faster ripening during the wet period. The two forms of ripening showed a non-additive compensatory interaction. The effect of post-detachment ripening on infectivity of germinated spores was more pronounced at 15 than, at 18 or 20 °C; the effect was strongest during the first day of the dry period. At dry periods of over 6 days, infectivity of germinated spores decreased, especially at the higher temperatures. Prolonged exposure, of spores to a dry period apparently damages the spores even though they are still able to germinate.Samenvatting Uredosporen van de bruine roest van tarwe (Puccinia recondita f.sp.tritici) werden over het eerste blad van tarwekiemplanten verstoven. De aldus geïnoculeerde planten werden in een klimaatkamer geplaatst bij ca. 18 °C om de sporen bloot te stellen aan droge perioden van 0 tot 9 dagen. De droge perioden werden gevolgd door natte perioden van 2 tot 24 uur om de sporen te laten kiemen en de planten te infecteren. Na de natte periode werden de planten bij verschillende temperature geplaatst om de latente periode en de vorming van sporenhoopjes te bepalen. De hoofdeffecten op de vorming van sporenhoopjes waren zeer significant: duur van de droge periode, duur van de natte periode en temperatuur. Twee vormen van sporenrijping werden gevonden bij rijping vnn sporen, die los op het blad lagen (rijping, buiten de sporenhoopjes), een langzame rijping tijdens de droge periode en een snelle rijping tijdens de natte periode. Deze twee vormen van rijping vertoonden statistische interactie met enige wederzijdse compensatie. Het effect van deze sporenrijping (buiten de sporenhoopjes) op de infectiviteit van gekiemde sporen was bij 15 °C duidelijker dan bij 18 en 20 °C; het effect was het sterkst tijdens de eerste dag van de droge periode. Bij droge periodes langer dan 6 dagen daalde de infectiviteit, vooral bij de hogere temperaturen.     

草坪常用化学药剂对昆虫病原线虫存活和侵染率的影响

测定了草坪上常用的14种化学药剂对蝼蛄斯氏线、长尾斯氏线虫X-7品系和小卷蛾斯氏线虫All品系存活和侵染率的影响。杀虫剂乙酰甲胺磷在高浓度和推荐浓度下对蝼蛄斯氏线虫、长尾斯氏线虫和小卷蛾斯氏线虫的致死率分别为21％和9．5％，13％和5．5％，5．5％和2％；敌百虫在高浓度和推荐浓度下对蝼蛄斯氏线虫的致死率分别高达94．5％和92．5％，在高浓度下对长尾斯氏线虫的致死率为8％，对小卷蛾斯氏线虫没有明显致死作用；克蛾宝对3种线虫的致死作用均比乙酰甲胺磷和敌百虫低。杀菌剂对3种线虫的存活均无影响。除草剂2，4-D丁酯对3种线虫低浓度和高浓度下致死率分别为2％、6％、3．5％和5％、85．5％、6％。经化学药剂处理24h后的线虫侵染黄粉虫9-11龄幼虫，对线虫存活没有影响或者影响较小的化学药剂对线虫的侵染率都没有明显的影响，但剂型为10％可湿性粉剂的吡虫啉对长尾斯氏线虫，以及高浓度的2，4-D丁酯对小卷蛾斯氏线虫的侵染率有明显抑制作用。     

Studies on amoebae and cysts associated with the isolation of Spongospora subterranea f.sp. subterranea in vitro

New evidence is presented to support the contention that the amoeba/cyst colonies isolated from surface-sterilized Spongospora subterranea f.sp. subterranea -infected potato tubers and spore balls have a saprophytic phase but are contaminants and not S. subterranea. Amoebae isolated from infected tissues and spore balls formed colonies associated with bacteria on 1% water agar at 18°C and encysted after 5–7 days. These cysts were morphologically distinct from the resting spores of S. subterranea and were formed singly or in a layer, unlike the spore ball (cystosorus) of S. subterranea . Amoebae, cysts and mixtures of amoebae and cysts in primary, secondary and tertiary subcultures failed to infect tomato roots. PCR amplification of DNA from amoebae, cysts and spore balls using the S. subterranea -specific primer pair SsF/R generated a 434-bp product from S. subterranea spore balls only and not from amoebae or cysts. When an amoeba/cyst-specific primer pair AmF/R was designed and used for PCR amplification, a single 411-bp product was generated from DNA of amoebae and cysts, but not from DNA of S. subterranea spore balls. These results are discussed in relation to earlier reports claiming the successful isolation of S. subterranea and other plasmodiophorids in vitro .     

Molecular and biological characterisation of Cryptosporidium in pigs

OBJECTIVE: Genetic and biological characterisation of 12 isolates of Cryptosporidium from pigs and comparing them with Cryptosporidium isolates from humans and cattle. DESIGN: Cryptosporidium isolates from pigs were compared with those obtained from human and cattle using rDNA sequence analysis. The infectivity of two of the porcine isolates was determined in neonatal mice and the clinical history of the infected pigs recorded. RESULTS: Pig-derived isolates of Cryptosporidium exhibited two distinct genotypes; a porcine genotype and a bovine genotype, which is common to cattle and other livestock. The porcine genotype did not produce any infection in neonatal mice whereas the bovine genotype did. CONCLUSION: Two distinct genetically and biologically differing strains of Cryptosporidium appeared to be associated with acute diarrhoea in pigs. Whether Cryptosporidium was a primary or secondary pathogen is unclear but warrants further investigation. As the bovine genotype is known to infect humans, the results suggest that pigs can act as reservoirs of cryptosporidial infections for humans and other live-stock. The zoonotic potential of the pig-adapted genotype is uncertain and requires further study.     

In vitro and in vivo efficacy of lasalocid for treatment of experimental cryptosporidiosis

In vitro viability of purified Cryptosporidium parvum oocysts, exposed for 30, 60, 90 and 120 min to 0.27 mg/ml lasalocid suspension was evaluated by inclusion or exclusion of two fluorogenic vital dyes and an excystation technique. Continuously, preventive and curative efficacies at different doses (9, 6.75, 5.625 and 4.5 mg/kg body weight) and regimens of lasalocid against cryptosporidial infection were evaluated on an experimental neonatal mice model. In vitro assays demonstrated a decrease in the oocyst viability related to an increase in exposure time for exposure to the lasalocid suspension. The infection was eradicated when the suspension was administered with a dose of ≥6.75 mg/kg body weight. No apparent toxic effects were observed.     

PCV2感染性分子克隆的制备及体内外感染性试验

将猪圆环病毒2型（Type2 porcine circovirus，PCV2）JXL株cDNA插入到载体pMD18-T中，获得的pMDT-PCV转染猪肾细胞PK15细胞系，盲传4代后，利用PCV2阳性猪血清进行间接免疫荧光抗体试验（IFA），能检测到特异性荧光。将pMDT-PCV质粒DNA腹股沟淋巴结注射40日龄仔猪2头，分别接种2、3次，接种剂量500μg／次，首次注射35d心脏放血致死。在体内感染性试验期间，动物未出现明显临床症状。试验结束，病理切片结果显示，不同淋巴组织中分别存在淋巴细胞缺失或增多的现象；肾小球、扁桃体、空肠淋巴结和股前淋巴结等冰冻组织切片中存在大量PCV2病毒抗原；血清中PCV2特异性的ELISA抗体效价迭1：2560，IFA效价为1：1280；通过聚合酶链式反应（PCR）可以分别从体外感染PK15细胞和体内感染动物及同圈饲养的空白对照猪的淋巴组织中扩增到病毒特异性基因片段。本研究证明含有单拷贝PCV2的重组质粒pMDT—PCV在体内、外均具有感染性，能衍生出病毒，并产生符合自然感染PCV2的大体病变和组织病理学变化，并激发较强的体液免癌应答。     

昆虫病原线虫对木麻黄毒蛾侵染能力的初步研究

本文报道应用昆虫病原线虫Steinernema spp.室内对木麻黄毒蛾的侵染能力。通过斯氏属九个线虫品系对木毒蛾的侵染力测定筛选出S.feltiae Agriotos为最佳品系;能寄生低、中、高龄幼虫及蛹;可在3天内把害虫致死。供试的其它八个线虫品系也能不同程度地致死害虫,并在死虫体内繁殖。S.f.Agriotos线虫的剂量对木毒蛾的致死速度及效果有影响,以1000条线虫/害虫侵染期线虫为最适宜剂量,林间对木毒蛾幼虫的致死率平均为89.6%。     

Virion glycosylation governs integrity and infectivity of infectious pancreatic necrosis virus

The possible importance of the O-linked glycosylation in virion stability and infectivity of infectious pancreatic necrosis virus (IPNV) was analysed. Enzymatic treatment with O-glycosidase of radiolabelled virions under different ionic conditions, to allow for possible alternative exposure of glycosidic enzyme cleavage sites, did not alter the specific infectivity of virions re-isolated after rate-zonal centrifugation in glycerol gradients. As an alternative method to assess the significance of carbohydrates in IPNV integrity, periodate oxidation in the presence of an aldehyde quencher was chosen. Following re-isolation of viruses, a 3-5 (10)log-unit reduction in specific infectivity was revealed and, at higher concentrations, a total disruption or virion aggregation was observed. The loss of infectivity of intact virions was not because of a lack of attachment to cells. Additionally, re-evaluation of reading values from UV-spectra of purified IPNV yielded a specific infectivity of 3 × 10(11) TCID(50)-units mg(-1) of protein and a ratio of 40 virions per TCID(50)-unit in the CHSE-214 cell system.