Immune response to rabbit coccidiosis: a comparison between infections with Eimeria flavescens and E. intestinalis

Seven- to eight-week-old rabbits were infected with Eimeria intestinalis Cheissin, 1948, a highly immunogenic coccidium, or Eimeria flavescens Marotel et Guilhon, 1941, which is weakly immunogenic. Immune response was investigated at 7, 14 and 21 days post inoculation (DPI). The level of serum immunoglobulins, lymphocyte proliferation stimulated by parasite antigens and weight of mesenteric lymph nodes (MLN) showed similar dynamics in rabbits inoculated with both coccidia species. The amount of serum IgG and IgM, but not IgA, was increased from 14 DPI. The lymphocytes from MLN of infected animals significantly reacted to stimulation with parasite antigen 14 and 21 DPI and MLN were enlarged at 14 DPI. Thus, both parasite species elicited immune response characterized by these parameters in a similar manner despite of their different immunogenicity. The only apparent difference in the responses was in the percentage of CD8+ lymphocytes in the specific site of parasite development (the last third of the small intestine in E. intestinalis, caecum in E. flavescens), which increased in rabbits infected with E. intestinalis but not with E. flavescens. This parameter reflects the status of local immunity and hence the results suggest that the local reaction plays an important role in induction of protective immunity to coccidia in rabbits.     

Serum protein profile of mice during infection with single and repeated doses of Hymenolepis nana eggs

Significant alterations in serum protein of mice following Hymenolepis nana infection were observed. These changes were recorded as decrease in albumin, increase in gamma globulin and a temporary rise in alpha-1, alpha-2 and beta globulins. The decrease in albumin and increase in gamma globulin occurred as early as on 1st day after infection. The alpha-1 and alpha-2 globulins did not show definite profile during infection. The beta globulin predominantly increased till the day 20 post infection and thereafter generally decreased. Repeated infection did not enhance any further alterations in serum protein. There was no significant correlation between infection dose levels and serum protein changes.     

A disease and production index (DPI) for selection of cacao (Theobroma cacao) clones highly productive and tolerant to pod rot diseases

Frosty pod rot (FPR) (Moniliophthora roreri), along with black pod rot (Phytophthora species) and witches’ broom disease (Moniliophthora perniciosa) constitute the main phytosanitary problems limiting cacao (Theobroma cacao) production causing severe yield losses. One of the main sought after methods of pod rot management is the selection of tolerant cacao genotypes. Typically, the selection is carried out through the quantification of the percentage of diseased pods (PDP). However, PDP does not consider the relative productivity, or production potential (PT) of the genotype. Production potential can vary among cacao genotypes. Consequently, genotypes with similar PT can have similar or vastly different disease tolerance levels as measured by PDP. The disease and production index (DPI) was developed to integrate a genotype's tolerance to M. roreri and other diseases as measured by PDP, with its PT. Here, we evaluated the number of healthy pods, number of diseased pods, and weight of fresh seed for 29 clones grown in replicated five-tree plots over 4 years. The data obtained was used to calculate PDP and DPI for each clone for three different disease combinations: frosty pod rot alone, pod rots other than frosty pod rot, and the combination of all pod rots. Multivariate analysis verified that DPI discriminated between clones based on productivity and disease tolerance. Surprisingly, there was a close ranking of clones between resistance to FPR and resistance to all other pod rots. The DPI can be used in breeding programmes focused on the selection of high yielding disease-tolerant cacao genotypes.     

Double alteration of the small intestine in conventional and gnotobiotic piglets experimentally infected with the coccidium Isospora suis (Apicomplexa, Eimeriidae)

The pathogenicity of the coccidium Isospora suis was studied in 42 conventional and 26 gnotobiotic piglets at 1-13 days post infection (DPI). The prepatent period of the coccidium I. suis was 4.5-5 days. Only in one experiment in conventional piglets the prepatent period of 3.5 days was recorded. At least 9 days pathogenesis of I. suis was recorded during which double alteration of the small intestine occurred. The first alteration was found at 3-4 DPI. The second phase of alterative changes was observed at 8-9 DPI. In comparison with gnotobiotic piglets in conventional piglets clinical signs and pathological changes used to appear one day sooner but reparation and regeneration of alterative changes was quicker. In the first phase of the infection (3-7 or 8 DPI) the heaviest pathological changes were in the posterior jejunum. In the second phase of the infection (8 or 9-12 DPI) the heaviest changes were in the middle jejunum. In short period repeated lesions of mucosal barrier of the small intestine multiply the pathogenicity of I. suis and rank I. suis in front place among other enteropathogens of nursing piglets.     

The life cycle of Eimeria danailovi from ducks.

The life cycle of Eimeria danailovi Gr?fner, Graubmann et Betke in experimentally infected ducks was studied by optical microscopy. The asexual generation developed in the posterior part of jejunum and in the whole ileum. The sexual stages occurred in jejunum and ileum, and, in addition, in cecum and colon. All endogenous stages were localized in the cytoplasm of epithelial cells in the apical and basal parts of villi. Two generations of meronts were found to develop, differing from one another in the number of merozoites. The meronts of the first generation were observed 2 days post infection (DPI) and contained 10-14 (on the average 11) merozoites. The second generation of meronts, containing 12-22 (on the average 16) merozoites, developed on 3 DPI. The sexual stages were found in histological preparations on 5 and 6 DPI. They appeared in the faces of experimentally infected ducks first on 5 DPI and they were shed for three days. Oocyst sporulation at room temperature lasted 2-3 days.     

The pathogenicity of rabbit coccidium Eimeria coecicola Cheissin, 1947

The pathogenicity of Eimeria coecicola for rabbits has been demonstrated in our experiments. The animals suffered from prolonged affection of appendix lasting at least 20 days. Pathological changes appeared with the development of merogony since day 4 post infection (DPI) and were characterized by an inflammatory infiltration and abundant pyogenic component in lamina propria, swelling and coalescence of upper parts of appendix mucosa above atrophied domes, where spaces filled with stagnating inflammatory exudate, endogenic stages of coccidia, and desquamated epithelia are formed. The alteration of the epithelium and exposure of the appendix lamina propria occur in relation with the gametogony in the period of about 10 DPI. Since 8 DPI, the epithelium of the infected endogenic stages of coccidia becomes hyperplastic, proliferates into lamina propria and is subjected to necrosis. Groups of immature oocysts and their fragments remain in lamina propria and are resorbed, at least for 10 days, by granulomatous inflammatory structures with abundant multinucleate cells of the type of foreign body cells.     

Effect of Host Plant Resistance to Tomato yellow leaf curl virus (TYLCV) on Virus Acquisition and Transmission by Its Whitefly Vector

ABSTRACT The effect that Tomato yellow leaf curl virus (TYLCV)-infected resistant tomato plants may have on virus epidemiology was studied. Four tomato genotypes that exhibit different levels of viral resistance, ranging from fully susceptible to highly resistant, served as TYLCV-infected source plants. Viral acquisition and transmission rates by white-flies following feeding on the different source plants were evaluated. TYLCV transmission rate by whiteflies that had fed on infected source plants 21 days postinoculation (DPI), shortly after the appearance of TYLCV symptoms, was negatively correlated with the level of resistance displayed by the source plant. Therefore, the higher the resistance, the lower the transmission rate. In addition, TYLCV DNA accumulation was shown to be lower in the resistant source plants compared with the susceptible plants. Whitefly survival rate, following feeding on source plants 21 DPI, was similar for all the cultivars tested. Significant differences in whitefly survival were found, however, following feeding on the infected source plants at 35 DPI; here, whitefly survival rate increased with higher levels of resistance displayed by the source plant. At 35 DPI, the susceptible plants had developed severe TYLCV disease symptoms, and transmission rates from these plants were the lowest, presumably due to the poor condition of these plants. Transmission rates from source plants displaying a medium level of resistance level were highest, with rates declining following feeding on source plants displaying higher levels of TYLCV resistance. TYLCV DNA accumulation in whiteflies following feeding on infected source plants at both 21 and 35 DPI was directly correlated with viral DNA accumulation in source plants. Results show that, in essence, the higher the resistance expressed, the less suitable the plant was as a viral source. Consequently, following acquisition from a highly resistant plant, TYLCV transmission by whiteflies will be less efficient.     

Botanical pesticide, azadirachtin attenuates blood electrolytes of a freshwater catfish Heteropneustes fossilis

The present study was aimed to investigate the effects of purified neem extract azadirachtin on the blood electrolytes of Heteropneustes fossilis for short- and long-term. In short-term exposure the fish were subjected to 0.8 (i.e. 80%) of 96 h LC₅₀ value of azadirachtin (41.89 mg L⁻¹) for 96 h. In long-term exposure the experiment was performed for 28 days by using 0.2 (i.e. 20%) of 96 h LC₅₀ value of azadirachtin (10.47 mg L⁻¹). Fish were sacrificed (anaesthesized with MS 222) from control and experimental (azadirachtin) groups after 24, 48, 72, and 96 h in short-term exposure and after 7, 14, 21, and 28 days in long-term experiment. Blood samples were analyzed for calcium and inorganic phosphate levels. Acute exposure of azadirachtin caused a progressive decrease in the serum calcium levels after 48 h in fish H. fossilis which persists till the close of the experiment (96 h). The serum inorganic phosphate levels remained unaffected till 72 h in the azadirachtin exposed fish. After 96 h the levels exhibit a decrease. Chronic azadirachtin treatment caused a decrease in serum calcium levels at day 14. This decrease continued till the end of the experiment. The serum phosphate level of the azadirachtin treated fish decreased on day 14 and 21. However, on day 28 the levels were close to the normal values.     

Pathways of bacterial invasion and watermelon seed infection by Acidovorax citrulli

This study explored the pathways of ingress of Acidovorax citrulli, the causal agent of bacterial fruit blotch of cucurbits, into watermelon seeds. Up until 7 days post‐inoculation (DPI), a significantly higher percentage of watermelon seeds was infected with A. citrulli when the bacteria were applied (c. 1 × 10⁶ colony‐forming units) to stigmas versus ovary pericarps of female flowers. Immunofluorescence microscopy showed that, with stigma inoculation, A. citrulli colonized style and ovary tissues by 1 DPI, and the bacteria co‐localized with pollen germ tubes in these tissues. With ovary pericarp inoculation, A. citrulli cells penetrated the epicarp and mesocarp tissues by 1 DPI but did not reach endocarp until 4 DPI. Finally, manual pollination followed by stigma inoculation led to >53% A. citrulli‐infected seed lots, while A. citrulli was not detected in seeds/ovules generated by stigma inoculation without pollination (chemically induced parthenocarpy). These results show that stigma inoculation results in faster colonization of watermelon ovules by A. citrulli than pericarp inoculation, even though there is no difference in the levels of infection in mature seeds. The data also indicate that pollen germ tubes play an important role in A. citrulli ingress into watermelon seeds via stigmas.     

Signal Mediators for Phytoalexin Production in Defense Response of Oats Elicited by Victorin as a Specific Elicitor

Signals mediating phytoalexin (PA) production were analyzed in primary leaves of oats cv. Iowa X469 treated with an elicitor victorin. Production of the PA avenanthramide A was inhibited by DPI, an inhibitor of NADPH oxidase/nitric oxide synthase (NOS) and the NOS inhibitors l-NMMA and 1,3-PBIT. However, catalase and superoxide dismutase (SOD) hardly suppressed it. From the data, NO functions as a major reactive oxygen species in signal transduction leading to PA production in the defense response of oats. EGTA, verapamil and ruthenium red inhibited PA production, suggesting that Ca²⁺ influx into the cytoplasm and intracellular Ca²⁺ movement are involved in the defense response. Trifluoperazine, a calmodulin function inhibitor, and K-252a, a serine/threonine kinase inhibitor, also suppressed the accumulation, whereas okadaic acid, a serine/threonine phosphatase inhibitor, did not suppress it, suggesting the involvement of calmodulin and protein kinase, but not of phosphatase in PA production. Received 24 December 1999/ Accepted in revised form 4 February 2000     

Effect of <Emphasis Type="Italic">Meloidogyne ethiopica</Emphasis> parasitism on water management and physiological stress in tomato

Root-knot nematodes (RKN) are obligate endoparasites that severely damage the host root system. Nutrient and water uptake are substantially reduced in infested plants, resulting into altered physiological processes and reduced plant growth. The effect of nematode infestation on the morphological changes of roots and subsequent physiological plant responses of infested tomatoes with the RKN Meloidogyne ethiopica was studied in a pot experiment. Plants were infested with two inoculum densities (10 or 50 eggs per cm³ substrate) and its effect was evaluated 74 and 102 days post inoculation (DPI). Morphological changes and root growth was determined by analysing scanned images of the whole root system. Nematode infestation reduced the portion of fine roots and increased that of coarse roots due to gall formation. Fine roots of non-infested control plants represented around 51% of the area of the whole root system at 74 and 102 DPI. In comparison to controls, plants inoculated with low and high nematode density had 2.1 and 3.2-times lower surface area of fine roots at 102 DPI. Root analyses revealed that plants had a very limited ability to mitigate the effects of the root-knot nematodes infestation by altering root growth. Root galls had a major influence on the hydraulic conductivity of the root system, which was significantly reduced. The low leaf water potential of infested plants coincided with decreased stomatal conductivity, transpiration and photosynthesis. The latter two were reduced by 60–70% when compared to non-infested control plants.     

Immunolocalization of <Emphasis Type="Italic">Pepper mild mottle virus</Emphasis> in developing seeds and seedlings of <Emphasis Type="Italic">Capsicum annuum</Emphasis>

The location of Pepper mild mottle virus (PMMoV) within seeds as they developed on inoculated seedlings of pepper (Capsicum annuum) was followed over time by detecting the viral coat protein using immunofluorescence microscopy. Seedlings were inoculated with PMMoV when the flower buds on the first and second branching nodes were in bloom. Fluorescence indicating the presence of PMMoV was first observed around immature seeds and placentas in the ovaries on the fourth branching node at 20 days post-anthesis (20 DPA), which corresponded to 39 days post-inoculation (39 DPI). The area with fluorescence gradually expanded from the placenta into the integument and the parenchyma, and finally reached the tip of the immature seeds by 34 DPA (53 DPI). The embryo or endosperm beyond the endothelium never fluoresced during the experiment [i.e., ending at 81 DPA (102 DPI)]. For visualizing viral routes of invasion from seeds into new seedlings, PMMoV-infected C. annuum seeds that were heterozygous for the L ³ tobamovirus-resistance gene were sown in soil at 30°C. After ~2 weeks, the cotyledon developed virally induced necrosis. These findings shed light on the infection cycle of PMMoV through vertical transmission in C. annuum.     

Effects of sodium fluoride on hepatic toxicity in adult mice and their suckling pups

In this investigation, we have evaluated the effect of sodium fluoride (NaF) on hepatic function in pregnant and lactating mice and their suckling pups. Experiments were carried out on female Wistar mice given 500 ppm sodium fluoride (226 ppm fluoride ion) in their drinking water from the 15th day of pregnancy until day 14 after delivery. All mice were sacrificed on day 14 after parturition. Our results showed a significant decrease in serum levels of total protein and albumin, a marked hypoglycaemia and a significant decline in serum cholesterol and triglyceride levels in fluoride-treated mice and their pups. Whereas globulin and biluribin levels in serum were not significantly changed by NaF treatment. On the other hand, serum transaminase activities (aspartate transaminase; alanine transaminase), which well known as markers of liver function, were elevated indicating hepatic cells’ damage after treatment with fluoride. Lipid peroxidation increased in NaF-treated mice and pups, as revealed by high liver malondialdehyde levels, while serum total antioxidant status showed a significant decline. These biochemical modifications in NaF-treated mice also correspond histologically with extensive ballooning, hepatocellular necrosis and infiltration of mononuclear cells. These effects were not observed in controls.     

Effects of sodium fluoride on hepatic toxicity in adult mice and their suckling pups

In this investigation, we have evaluated the effect of sodium fluoride (NaF) on hepatic function in pregnant and lactating mice and their suckling pups. Experiments were carried out on female Wistar mice given 500 ppm sodium fluoride (226 ppm fluoride ion) in their drinking water from the 15th day of pregnancy until day 14 after delivery. All mice were sacrificed on day 14 after parturition. Our results showed a significant decrease in serum levels of total protein and albumin, a marked hypoglycaemia and a significant decline in serum cholesterol and triglyceride levels in fluoride-treated mice and their pups. Whereas globulin and biluribin levels in serum were not significantly changed by NaF treatment. On the other hand, serum transaminase activities (aspartate transaminase; alanine transaminase), which well known as markers of liver function, were elevated indicating hepatic cells’ damage after treatment with fluoride. Lipid peroxidation increased in NaF-treated mice and pups, as revealed by high liver malondialdehyde levels, while serum total antioxidant status showed a significant decline. These biochemical modifications in NaF-treated mice also correspond histologically with extensive ballooning, hepatocellular necrosis and infiltration of mononuclear cells. These effects were not observed in controls.     

解淀粉芽孢杆菌LJ1对实验鼠的急性毒性研究

解淀粉芽孢杆菌LJ1是从土壤中分离得到的1株对瓜类白粉病具有较好防效的细菌。为了解LJ1菌株对动物及人的安全性,测定了该菌株发酵液对实验鼠的急性毒性,以及处理后小鼠体内谷丙转氨酶(AST)、谷草转氨酶(ALT)和碱性磷酸酶(ALP)的含量及6种血相指标。结果发现:LJ1菌株发酵液对小鼠的急性经口毒性和对大鼠的急性经皮毒性均为"低毒"级(LD50>4 640 mg/kg); 处理3 d后,小鼠血清中AST、ALT和ALP 3种酶的含量及血液中白细胞、红细胞数和血红蛋白的含量均明显升高,与对照相比差异显著(P<0.05),14 d后各项指标基本恢复至正常水平,与对照无显著差异。说明LJ1发酵液灌胃处理初期对小鼠的脏器功能有一定影响,但14 d后其对脏器的影响可逐渐恢复。因此推断LJ1发酵液对动物机体安全,该菌株有进一步研究开发为生防菌的价值。     

Some diagnostic, biologic and morphologic characteristics of Francisella tularensis strains isolated from the ticks Ixodes ricinus (L.) in the Prague agglomeration

Four infectious agents were isolated from the ticks Ixodes ricinus (L.) collected in the recreational area and park-forest of Prague. On the basis of cultivation, staining, biochemical, serologic properties, pathogenicity for animals and histological tests they were identified as Francisella tularensis with the following features: they are short, gram-negative rods of approximate dimensions of 0.3 X 0.8 micron, growing in enriched media after 3-4 day incubation at 37 degrees C. They form small circular, at first transparent, later greyish turbid colonies with regular rims. They are little active biochemically. They are susceptible to streptomycin and some broad spectrum antibiotics. They react positively with tularemic serum, but in lower titres than those in which this serum reacts with standard antigen. The microbes are highly pathogenic for mice, guinea-pigs, young rats, in which a massive bacteriemia occurs before death, but they do not kill rabbits. They multiply well in chick embryo, but do not grow in cell or tissue cultures. The most important histologic changes were observed in liver and spleen of mice. No pathologic changes were found in brain, lungs, heart, kidneys. Necroses were found in liver and in their marginal zones the microbes were present. Conspicuous were changes in numerous hepatocytes which became enlarged due to microbial multiplication and finally transformed into "sacs" packed with microbes. Histological and electronoptical examination showed that these are intracellular parasites fringed with a light lytic zone. Discussed is the problem to what extent the properties of the isolated strains are typical of F. tularensis as well as the importance of their detection from the aspect of epidemiology and differential diagnostics.     

Life cycle and ultrastructure of Eimeria stigmosa, the intranuclear coccidian of the goose (Anser anser domesticus).

The oocyst morphology and endogenous development of Eimeria stigmosa Klimes, 1963 in a domestic goose (Anser anser domesticus L.) was studied using light and electron microscopy. The oocyst wall consisted of two layers. The outer layer formed densely accumulated protrusions, whilst the inner layer was smooth and formed a collar structure around the micropyle. Meronts were observed in the posterior part of the jejunum, along the whole length of the ileum and in Meckel's diverticulum within 1-4 days post infection (DPI). Sexual generation was found in the caecum and colon 4-5 DPI. All endogenous stages were located intranuclearly in enterocytes, predominantly in the apical part of the villi in distinct parasitophorous vacuoles. Numerous different developmental stages were frequently found in one nucleus. Current evidence indicates the existence of only one asexual generation formed by ectomerogony. During the development of asexual stages, invaginations into the body of a meront by the host cell nucleoplasm were observed.     

保护性耕作对旱地麦田土壤酶活性的影响

通过在陇中黄土高原半干旱区设置的田间定位试验,研究了5种保护性耕作措施与传统耕作方式对旱地麦田土壤酶活性的影响.结果表明:不同耕作处理下过氧化氢酶活性均随耕作层的加深而递减;脲酶、碱性磷酸酶、蔗糖酶活性表现为三种翻耕处理(T,TS,TP)随土层的加深呈先增加后降低的趋势,而三种免耕处理(NT,NTS,NTP)随土层的加深而递减;与传统耕作(T)相比,免耕秸秆覆盖处理(NTS)下过氧化氢酶活性升高11.74%,脲酶活性升高17.60%,碱性磷酸酶活性升高43.99%,蔗糖酶活性升高40.22%;另外,就产量表现而言,免耕秸秆覆盖(NTS)是传统耕作(T)的1.68倍,统计分析差异显著(P＜0.05).可见,在黄土高原西部旱农区实施免耕秸秆覆盖的保护性耕作措施,既有利于作物产量的提高,也可以改善耕层土壤酶活性.     

Preliminary observation of the susceptibility of some freshwater snails to the infection with Varestrongylus sagittatus (Nematoda: Protostrongylidae).

Under laboratory conditions, the freshwater snails Galba truncatula Müll.), Radix peregra (Müll.) and Planorbarius corneus (L.) have been successfully infected with the first stage larvae of the protostrongylid nematode Varestrongylus sagittatus (Mueller, 1890) Dougherty, 1945. The net rate of the infection (mean number of larvae per snail examined - l/s) was 6.2 l/s in R. peregra and 3.5 l/s in P. corneus. G. truncatula was susceptible to the infection too (36.3 l/s). However, this result can be considered as pilot only, because of the low number of the specimens of this species examined. At 25 degrees C 50% of V. sagittatus larvae reached the 3-rd stage of development by 12.5 days post infection (DPI) in R. peregra and by 17.8 DPI in P. corneus. It was confirmed that the snail species of the Basommatophora that were studied can act as intermediate hosts of the nematode V. sagittatus under laboratory conditions.     

浙东大棚草莓白粉病菌越夏和初侵染菌源的研究

离体和盆栽试验表明,草莓白粉病菌经38℃高温处理8 h,分生孢子不能萌发;或每天38℃处理8 h,适温下16 h连续培养4 d后病斑不再产生分生孢子。据田间试验和调查,在浙江宁波夏季自然条件下繁育草莓苗,草莓白粉病菌不能存活到秋季,但当草莓生长良好或在有明显遮阳条件下繁育苗,少数病菌可以在草莓上越夏,越夏部位多在病株9月间仍保持绿色或部分绿色的原发病部位的匍匐茎段上。