共查询到20条相似文献，搜索用时 937 毫秒
1.
Histochemical studies on the cysticercus and surrounding tissue reaction were performed at various intervals after experimental infection. It was found that acid mucosubstances and proteins with SH- and SS-groups appeared first in the granulation tissue around the cysticercus (on about day 14 p.i.) and only later (on day 28 p.i.) in the tegument of the cysticercus where they were localized in the rim of microtriches. This envelope consisting of mucosubstances and proteins seems to be identical with the electron-dense substance found on the surface of developing cysticercus during electron-microscopical studies. It is considered to be a mimicry enabling the cysticerci to survive even in an immunologically unfavourable environment. Phospholipids were found in activated fibroblasts and in some cells of macrophage type on days 21 and 30 p.i. and in a large number in subtegumental cells of cysticercus on days 28-34 p.i. This phenomenon seems to be correlated with the increased activity of subtegumental cells of the larva in this period. In morphologically fully differentiated cysticerci, the reaction for phospholipids in subtegumental cells and distal cytoplasm was only feebly positive. Phospholipids were not detected in the rim of microtriches at any time after infection. 相似文献
2.
Nie X 《Phytopathology》2006,96(3):255-263
ABSTRACT The effects of salicylic acid (SA) and 1-aminocyclopropane-1-carboxylic acid (ACC) on the systemic development of symptoms induced by a severe isolate of Potato virus Y group N:O (PVY(N:O)) in tobacco were investigated. Upon inoculation, the systemic development of symptoms in tobacco plants could be divided into three stages: virus incubation stage, rapid symptom-progress stage, and partial recovery and symptom-shifting stage. Treatment of seedlings with SA delayed the virus-induced necrosis in stems by 1 to 2 days. SA, not ACC, also significantly suppressed the symptom severity in stems. However, neither SA nor ACC treatment affected the partial recovery phenotype exhibited in the latterly emerged upper parts of the plants. Further analysis indicated that the accumulation of PVY was retarded by SA at the early stage of infection, and the effects were more profound in stems than leaves. Peroxidase (POX) activity and pathogenesis-related (PR) genes PR-1a and PR-1b were enhanced by PVY infection. SA not only increased POX activity in stems and PR genes in stems and leaves of mock-inoculated plants, but also elevated the activity of POX in both leaves and stems and the expression of PR-1a in leaves of PVY-infected plants. Together, the results suggest that systemic acquired resistance plays a key role in suppressing PVY(N:O)-induced symptom development through SA-mediated and ethylene-independent pathways. The symptom suppression was correlated with reduced replication/ accumulation of virus at the early stage of infection. The results also suggest that neither SA nor ethylene plays a role in the recovery phenotype. 相似文献
3.
An experimental infection with the microsporidian Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923 was studied using a model of immunocompetent BALB/c mice and immunodeficient SCID mice. The course of infection after intraperitoneal inoculation of E. cuniculi spores was evaluated using the presence of spores in peritoneal macrophages as a criterion. First significant decrease in the proportion of infected cells was recorded on day 9 post infection (p.i.) in BALB/c mice. From day 14 p.i. no spores were observed in macrophages from BALB/c mice, while the number of infected macrophages from SCID mice increased until the death of the mice. The natural killer (NK) cell activity of mouse splenocytes was compared with the production of interferon gamma (IFN-gamma) by these cells. While in BALB/c mice NK activity peaked on days 9 and 14 p.i., in SCID mice the marked increase of NK activity was recorded close before death of mice, on day 21 p.i. in correlation with the production of IFN-gamma. Production of specific antibodies was demonstrated from day 9 p.i. in sera from BALB/c mice. It is concluded that intraperitoneal infection of SCID mice with spores of E. cuniculi results in the marked increase in the number of peritoneal exudate cells and in the percentage of infected cells close before death of mice. Neither high activity of NK cells nor increased production of IFN-gamma are sufficient for the recovery of SCID mice from an E. cuniculi infection. 相似文献
4.
The development of the nematode Procamallanus saccobranchi Karve, 1952, a parasite in the stomach of the fish Heteropneustes fossilis (Bloch), was studied in Mesocyclops crassus (Fischer) and Mesocyclops leuckarti (Claus). After being ingested by the copepods the nematode first-stage larvae penetrated into the haemocoel of the intermediate host; there they moulted twice (on days 3 and 5 p.i. at 28-30 degrees C) attaining the third, infective stage. The definitive host H. fossilis acquired infection by feeding on copepods harbouring infective-stage larvae; in the stomach of this definitive host, the larvae were observed to undergo two more moults. The third moult occurred on day 13 p.i. and the fourth moult on day 38 p.i. and day 66 p.i. in "male" and "female" larvae, respectively. The larval stages, including the moulting forms are described and illustrated. 相似文献
5.
The terminal phase of the migration of Trichobilharzia regenti Horák, Kolárová et Dvorák, 1998 in the definitive host (Anas platyrhynchos f. domestica) was studied 12-27 days post infection (p.i.). Brain meninges were the last part of the nervous system where the worms were detected before their occurrence in the nasal cavity. In meninges, the parasites started to feed on red blood cells. Then the worms occurred in the nasal mucosa 14-25 days p.i. and the first immature eggs appeared 15 days p.i. The fully developed miracidia were recorded in the eggs from 17 days p.i. and freely in the nasal mucosa 19 days p.i. Infiltrates of lymphocytes, later also eosinophils and heterophils around the eggs and free miracidia, were observed from 15 and 19 days p.i., respectively. The haemorrhages occurring from 17 days p.i., and the granulomas with lymphocytes, eosinophils and heterophils forming around the eggs from 22 days p.i. were the most apparent pathological changes of nasal tissue. 相似文献
6.
S Lukes 《Folia parasitologica》1984,31(4):339-343
Immune response of rabbits experimentally infected with Ascaris suum was studied by indirect haemagglutination method. The animals were infected with the doses of 5,000, 10,000 and 20,000 infective eggs per animal. Positive reactions were observed from days 5-11 p.i., maximum reactions on days 11-19 p.i. A reinfection with the same doses (1x or 2x after 35 and 65 days) increased the antibody titre. The strongest individual reaction was recorded on day 19 p.i. in the group infected with the highest dose (titre 1 : 4096). The increased antibody titres persisted til the end of the experiment (82th day p.i.) in all groups. 相似文献
7.
V Skárková 《Folia parasitologica》1986,33(2):115-122
The asexual reproduction of Sarcocystis dispersa was studied in the liver of the house mouse. Histopathological examinations revealed infection of parenchymal cells with the parasite and diffuse cellular infiltrations with the presence of polymorphonuclear cells, monocytes and eosinophilic leukocytes. The volume and number of cellular infiltrates increased gradually from day 3 till day 10 p.i. Then appeared necrotic foci and both phenomena reached the maximum on days 10-12 p.i. On days 21-34 p.i., no changes occurred in the tissue and the liver healed without scars. The infection of common vole with Sarcocystis cernae sporocysts caused cellular infiltrations in the liver around the portobiliary veins. The parasite was present from day 3 till day 7 p.i. The histopathological picture of liver changes was similar to that in the house mouse. 相似文献
8.
大豆花叶病种子带毒及介体传播在流行中的作用 总被引：3，自引：0，他引：3
大豆植株的生育时期,对大豆花叶病的发展程度和危害性,有明显的影响。单叶期最感病,抗性随着生育年龄的增长而提高,单叶期潜育期最短、发病率最高,危害性最大。开花、结荚期后感病,对植株生长影响不大,黑龙江省大豆田出现的蚜虫中,大豆蚜、桃蚜、玉米蚜、棉蚜均能传播SMV,蚜虫最早出现于6月上中旬,高蜂为7月中下旬,大豆花叶病田间传播主要发生在7月中旬以后,8月为传播盛期,观察圃病害传播初期,病株有明显的梯降分布。与对照区呈鲜明对比,说明除早期形成的病苗外,没有其他的自源侵染,病害传播距离不远,多数在5-15米内,少有超过25米的,垅间和逆风向传播距离更短,种子带毒形成的病苗,在流行中起主导作用。蚜虫传播发生晚,主要引起种子斑驳。 相似文献
9.
小麦与禾谷镰刀菌相互作用下病穗过氧化物酶和酯酶的变化 总被引：4，自引：0，他引：4
研究了苏麦3号(抗病)和凡6(感病)穗部受禾谷镰刀菌侵染后,过氧化物酶和酯酶的变化.在侵染的早期(症状显现前),苏麦3号接种穗的过氧化物酶活性增加较凡6接种穗的酶活增加快和稍高,且症状显现稍迟.在侵染的中后期,症状显现后,感病凡6较抗病苏麦3号的过氧化物酶活性增加快且高得多.2品种病穗中的酶活均是随着症状的发展和病情加重而迅速上升.无新的过氧化物酶同工酶出现在2品种病穗,但第2、3酶带活性随病情发展逐渐增强,5、6酶带活性逐渐减弱,凡6的变化较苏麦3号强烈.2品种病穗中均新出现2条相同的酯酶同工酶带.因此可以初步认为,在相互作用的早期,过氧化物酶活性的增加与苏麦3号对赤霉菌的抗性有一定联系,但在相互作用的中后期,二种组合酶活的大幅度提高是与症状的发展和感病反应相联系.2种同工酶难于作为鉴定小麦抗赤霉菌的生化指标. 相似文献
10.
《Pesticide biochemistry and physiology》1987,29(1):77-86
Glutathione S-transferase in the Australian sheep blowfly, Lucilia cuprina, was studied using 3,4-dichloronitrobenzene (DCNB) and 1-chloro-2,4-dinitrobenzene (CDNB) as substrates. The optimum pHs for enzyme activity were 7.5–8.0 and 6.7–7.4 for DCNB and CDNB conjugations, respectively. Inclusion of glutathione and bovine serum albumin in the homogenizing buffer protected the glutathione S-transferase from inhibition by endogenous compounds present in extracts of final instar larvae and of adults less than 7–8 days old. Conjugation activities for DCNB and CDNB increased throughout larval development to reach a peak early in the pupal stage. Activity then decreased through the remainder of the pupal stage and for the first 6–7 days after emergence of the adult. Almost all of the decrease in activity during the first 6 days of the adult occurred in the abdomen, which accounted for 85% of total activity in the adult female at emergence but only 47% at 6 days. Larval DCNB conjugation activity was localized almost entirely in the fat body (94%), whereas only 50% of the CDNB conjugation activity was in the fat body with the remainder in the cuticle (25%), gut (15%), and blood (10%). Adult and larval enzyme was induced ca. three- to four-fold by sodium phenobarbital. The induction was associated with changes in apparent Vmax rather than apparent Km, suggesting that phenobarbital caused increased production of forms of enzymes already present rather than inducing synthesis of altered or new forms. 相似文献
11.
T Scholz 《Folia parasitologica》1991,38(1):39-55
A part of the life cycle of Proteocephalus neglectus La Rue, 1911, a parasite of trout, starting from release of eggs from mature parasites into water, to the early phase of development in the definitive host, was studied under experimental conditions. Special regard has been paid to development in the intermediate host, copepod Cyclops strenuus. Some oncospheres in eggs kept in water at 5 and 10 degrees C remained infective for 20-25 days. The percentage of infected copepods depended on the length of their contact with parasite eggs. Cestode larvae (cercoscoleces) were formed in the intermediate host on days 8-10 p.i. at the temperatures of 21-22 degrees C, on days 18-21 at 15 degrees C, on days 24-28 at 10 degrees C, and on days 59-65 at 6 degrees C. Most larvae, including infective cercoscoleces, were localized in the cephalothorax of the intermediate host, particularly in its first segment. This localization did not change during their development. The infectivity of cercoscoleces was verified by experimental infection of Salmo gairdneri fry. The development of the cestode in this definitive host was observed for 17 days after infection at 10 degrees C. The finding of P. neglectus cereoscoleces in fish of the families Cottidae and Cyprinidae on day 2 after experimental infection indicates that these larvae can survive for a short time in atypical fish hosts. 相似文献
12.
绿僵菌侵染对黏虫免疫反应的影响 总被引：1，自引：0，他引：1
为揭示黏虫被病原菌侵染后的免疫应答机制,本试验分析比较了黏虫幼虫被金龟子绿僵菌Metarhizium anisopliae侵染后不同时间其血淋巴蛋白含量、免疫关键酶系(酚氧化酶PO,溶菌酶)活性、抗菌活力以及血细胞数量等免疫相关指标的变化。结果表明:受绿僵菌侵染后,黏虫6龄幼虫血淋巴蛋白含量在侵染初期(6 h和24 h)显著高于对照,侵染48、72和96 h后幼虫血淋巴蛋白质含量显著低于对照。且侵染后幼虫血淋巴PO活性也呈现先升高后降低的趋势,侵染初期(6 h和24 h)显著高于对照,侵染后期除72 h外与对照组无显著差异。侵染初期(24 h)溶菌酶活性也显著升高,随后出现下降,并于48 h显著低于对照,但在化蛹时(96 h)再次上升。绿僵菌侵染后期,黏虫的抗菌活性下降,于侵染后72 h抗菌活性显著低于对照,而侵染初期抗菌活性与对照无显著差异。另外,绿僵菌侵染对幼虫血细胞数量以及浆血胞比率也有显著的影响,表现为:侵染后6 h和24 h血细胞总数、浆血胞比率均显著高于对照,随后与对照并无显著差异。综上,绿僵菌侵染黏虫幼虫初期会显著诱导其免疫反应的启动,体现在主要免疫指标升高,而后随着免疫系统的破坏与能量的消耗,其免疫反应能力降低,生理活动受到干扰。 相似文献
13.
Khamrunissa BegumP.S. Rajini 《Pesticide biochemistry and physiology》2011,99(1):33-38
The present study was undertaken to investigate the potential of monocrotophos (MCP), a widely used organophosphorus insecticide, to induce hyperglycemia and its interactive ability to accentuate the early diabetic outcomes and associated complications in experimentally rendered diabetic rats. Rats were rendered diabetic with an acute dose (60 mg/kg b.w, i.p) of streptozotocin. MCP was orally administered at a sublethal dose (1/20 LD50, 0.9 mg /kg b.w./d, 5 days) to both normal and diabetic rats. While MCP per se moderately increased (by 25%) the blood glucose levels in normal rats, it significantly aggravated the hyperglycemic outcome in diabetic rats (56% above diabetic rats). Further, experimentally-induced diabetes was associated with only a marginal increase in total and HDL-cholesterol levels, while serum triglyceride levels were significantly enhanced. Although MCP per se did not affect these parameters, it caused a marked increase in triglyceride levels in serum of diabetic rats (54% above diabetic control). Furthermore, MCP-induced higher activity levels of serum transaminases viz., ALT and AST (51% and 71% higher as compared to diabetic control) suggestive of enhanced hepatic damage. Collectively, our findings provide evidence that MCP on repeated exposure has the propensity to augment the secondary complications associated with diabetes in a rat model. 相似文献
14.
The development of the nematode Spinitectus inermis (Zeder, 1800), a parasite of the stomach of eels, Anguilla anguilla (L.) in Europe, was experimentally studied. Mayfly nymphs Caenis macrura, Ecdyonurus dispar, Heptagenia sulphurea, Potamanthus luteus and Seratella ignita from Portugal and the Czech Republic were found to serve as experimental intermediate hosts. After ingestion of the nematode eggs by the mayfly nymphs, the toothed first-stage larvae were released and penetrated into the body cavity of the intermediate host. There they moulted twice (on day 4 and 6 post infection [p.i.] at water temperatures of 20-25 degrees C), attaining the third infective stage. The definitive host, A. anguilla, undoubtedly acquires infection by feeding on mayfly nymphs harbouring infective-stage larvae. In an experimentally infected eel, the fourth-stage larva undergoing the third moult was observed 28 days p.i. at water temperature of 20 degrees C. The larval stages, including moulting forms, are described and illustrated. The prepatent period of S. inermis is estimated to be about two months. 相似文献
15.
Physiological parameters were measured after experimental infection of roach (Rutilus rutilus L.) with Rhipidocotyle fennica Gibson, Valtonen et Taskinen, 1992 (Digenea) cercariae. The fish were caught from two lakes: a eutrophic bleached kraft mill effluent (BKME)-contaminated lake and an oligotrophic unpolluted lake. The intensity of infection was followed up to 10 days post infection (p.i.) and physiological parameters indicating non-specific stress responses and the condition of fish were examined simultaneously. The mean abundance, the number of parasites per fish, of R. fennica was significantly higher in the fish from the contaminated water during the first two days p.i., probably reflecting the decreased resistance of these fish to infection. The decrease of leukocrit, as well as the increase of the activity of transaminases (GOT and GPT) in infected fish of both groups are suggestive of pathological processes caused by cercariae penetrating the fish. A significantly lower leukocrit value, as well as higher alkaline phosphatase activity and plasma chloride levels were noted in fish originating from the contaminated lake compared to those from the unpolluted lake. No significant differences were noted in haematocrit, plasma protein and calcium values between the fish from the uncontaminated and contaminated lakes, or between the infected and uninfected control fish. 相似文献
16.
黄瓜黑星病菌致病机理的研究Ⅱ细胞壁降解酶及其在致病中的作用 总被引：15，自引：2，他引：13
本文通过活体内外黄瓜黑星病菌(Cladosporium cucumerinum)产生的细胞壁降解酶活性分析,初步明确了Cx-酶(羧甲基纤维素酶)、β-葡萄糖苷酶和PMG(聚甲基半乳糖醛酸酶)、PMTE(果胶甲基反式消除酶)在该菌侵染黄瓜中的作用。瓜条感病的各部位,以病健交界处细胞壁降解酶活性最高;在检测的各类酶中,活性最高的为PMG、PMTE,Cx-酶、β-葡萄糖苷酶和FPA(滤纸酶)活性较低。抗感病黄瓜品种染病后,细胞壁降解酶活性均迅速增强。感病品种染病后,果胶酶(PMG、PMTE)活性远远高于抗病品种,其高峰值是抗病品种的2.72~7.52倍。感病品种接种后纤维素酶(Cx-酶、β-葡萄糖苷酶)活性一直增强;抗病品种接种后β-葡萄糖苷酶随着接种天数的增加酶活性一直增强,Cx-酶在染病后初期活性迅速增强,增至高峰后逐渐降低。 相似文献
17.
河南省主推小麦品种白粉病发生程度及流行动态研究 总被引：1，自引：0，他引：1
经１９９５～１９９７年的试验表明,河南省近几年推广的小麦品种６７％以上为感白粉病品种。极感品种（豫麦１３号）白粉病发生早,发病全盛期长,约３０ｄ,表观侵染速率（ｒ）达０.１１～０.１６,最终病指和病指曲线下面积（ＡＵＤＰＣ）都最高;高感品种豫麦２５等的最终病指及ＡＵＤＰＣ值分别比极感品种低１９％～６６％、４０％～７３％,发病早,发病全盛期２５～３０ｄ,ｒ值０.１～０.１５;中抗品种豫麦２１号、２４号、中育４号占３３％,没有免疫品种。中抗品种的最终病指及ＡＵＤＰＣ值比极感品种分别低８３％～９１％、８９％～９４％,且发病较晚,发病全盛期只有１０ｄ,ｒ值０.０６～０.１１。 相似文献
18.
黄瓜黑星病菌致病机理的研究Ⅱ细胞壁降解酶及其在致病中的作用 总被引：3，自引：0，他引：3
本文通过活体内外黄瓜黑星病菌(Cladosporium cucumerinum)产生的细胞壁降解酶活性分析,初步明确了Cx-酶(羧甲基纤维素酶)、β-葡萄糖苷酶和PMG(聚甲基半乳糖醛酸酶)、PMTE(果胶甲基反式消除酶)在该菌侵染黄瓜中的作用。瓜条感病的各部位,以病健交界处细胞壁降解酶活性最高;在检测的各类酶中,活性最高的为PMG、PMTE,Cx-酶、β-葡萄糖苷酶和FPA(滤纸酶)活性较低。抗感病黄瓜品种染病后,细胞壁降解酶活性均迅速增强。感病品种染病后,果胶酶(PMG、PMTE)活性远远高于抗病品种,其高峰值是抗病品种的2.72~7.52倍。感病品种接种后纤维素酶(Cx-酶、β-葡萄糖苷酶)活性一直增强;抗病品种接种后β-葡萄糖苷酶随着接种天数的增加酶活性一直增强,Cx-酶在染病后初期活性迅速增强,增至高峰后逐渐降低。 相似文献
19.
《Physiological and Molecular Plant Pathology》2002,60(4):169-183
The growth of a coffee orange rust fungus (Hemileia vastatrix Berk and Br.) isolate (race II) and the sequence of responses it induced in leaves of resistant Coffea arabica L. and C. congensis Froehner as well as on a susceptible C. arabica were investigated cytologically and biochemically. The percentages of germinated urediospores and of appressoria formed over stomata as well as the fungal growth inside leaf tissues were similar in resistant and susceptible leaves until the 3rd day after the inoculation. In the susceptible leaves, at the majority of the infection sites (70%) the fungus pursued its growth without apparent inhibition while in the resistant leaves the fungus ceased its growth with higher frequency (34% in C. arabica and 54% in C. congensis) after the formation of at least one haustorium. The first signs of incompatibility, detected 2 days after the inoculation, were cytologically expressed by hypersensitive host cell death (HR), host cell wall autofluorescence and haustoria encasement with callose and β-1,4-glucans. Biochemically, two peaks of phenylalanine ammonia-lyase (PAL) activity were detected by 2 and 5 days after the inoculation. The 1st peak coincided with the early accumulation of phenolic compounds and with the beginning of cell death. The 2nd peak could be related to later accumulation of phenols and the lignification of the host cell walls. About 5–7 days after the inoculation, ultrastructural observations revealed the accumulation of a material partially crystallized in the intercellular spaces around the senescent hyphae, next to dead host cells and in close association with the middle lamella that initially labelled for pectins. It also contained polysaccharides and phenolic-like compounds. Cellulose, hemicellulose, extensins, hydroxyproline-rich glycoproteins and proteins were not detected. The hypertrophy of the host cells in the infection area were also observed around 12 days after the inoculation corresponding macroscopically to the reaction flt.In susceptible plants, cell death was also observed 3 days after the inoculation but only in a reduced percentage of infection sites in which the fungus aborted at an early stage. A late haustorium encasement and stimulation of PAL activity were also observed but these delayed host responses did not prevent fungal growth and sporulation.The intercellular material, only observed in the resistant plants, is here reported for the first time and although its role is unknown it might be the result of plant cell death. 相似文献
20.
T Scholz 《Folia parasitologica》1991,38(3):225-234
The development of the tapeworm Khawia sinensis has been observed up to the stage of sexually mature parasites releasing eggs in an experimentally infected definitive host (Cyprinus carpio) at 15-16 degrees C. Juvenile, maturing, adult and gravid tapeworms were found 2-12, 19-24, 36-62, and 78-91 days post infection, respectively. No apparent size difference between tapeworms from carp kept at 20-22 degrees C, examined 1-16 days post infection, and those from 15-16 degrees C was observed. In naturally infected and fed carp, kept at 21-22 degrees C, some tapeworms survived till the end of experiment (44 days) while in unfed fish they survived only 15 days from the beginning of experiment. 相似文献