共查询到20条相似文献，搜索用时 46 毫秒
1.
Light and electron microscopic observations of sporogenesis in the myxosporida, Ceratomyxa shasta (Noble, 1950) 总被引：1，自引：0，他引：1
Abstract. The stages of development leading to sporogenesis of Ceratomyxa shasta (Noble) were investigated by light and electron microscopy. Salmonid fishes were infected by exposing them to water containing the infectious stage and intestinal material was fixed at weekly intervals. Signs of intestinal infection were barely detectable by 7 days following exposure where trophozoites and later developmental forms were present, but by 14 days a large number of pansporoblasts could be detected in varying stages of development. By 21 days the majority of caeca were completely occluded and infection had spread throughout the connective tissues attached to the caeca.
The early developing trophozoites contained two or more nucleated cells within a mother cell. There was some evidence of multiplication of nuclei by fission. The sporoblasts usually contained twelve nucleated cells that gave rise to two groups of six cells (sporonts) and resulted in the formation of two spores in each mother cell. Each spore was formed by two sets of bilaterally arranged cells consisting of the main germinative cell or sporoplasm, the anteriorly placed capsule cells and the outer envelope or spore valve cell that surrounded the others and formed the spore covering.
As the spore matured the two germinative cells interacted with each other by pseudopodial extensions and appeared to fuse to form a diploid cell. The position of the cells laterally and slightly posteriorly to the central suture line formed a bilaterally curved spore. Mature spores when examined with the electron microscope were condensed, dark staining and relatively featureless, with a lateral measurement of 15 μm and an anterior-posterior measurement of 7μm. 相似文献
The early developing trophozoites contained two or more nucleated cells within a mother cell. There was some evidence of multiplication of nuclei by fission. The sporoblasts usually contained twelve nucleated cells that gave rise to two groups of six cells (sporonts) and resulted in the formation of two spores in each mother cell. Each spore was formed by two sets of bilaterally arranged cells consisting of the main germinative cell or sporoplasm, the anteriorly placed capsule cells and the outer envelope or spore valve cell that surrounded the others and formed the spore covering.
As the spore matured the two germinative cells interacted with each other by pseudopodial extensions and appeared to fuse to form a diploid cell. The position of the cells laterally and slightly posteriorly to the central suture line formed a bilaterally curved spore. Mature spores when examined with the electron microscope were condensed, dark staining and relatively featureless, with a lateral measurement of 15 μm and an anterior-posterior measurement of 7μm. 相似文献
2.
引起池养异育银鲫高死亡率的粘孢子虫新种咽碘泡虫形态和分子分析 总被引：1，自引：0，他引：1
对近几年发生在江苏省盐城地区引起池养异育银鲫大批死亡的粘孢子虫进行了形态和分子等方面分析研究,发现该粘孢子虫主要特点是:孢子梨形,部分孢子后部外周包围有透明无色的膜状鞘和壳瓣底部内侧呈现1～6个"V"形缺刻,两个极囊大小不等,孢子前端内侧两个极囊间有一个细长的囊间突起,胚质中无嗜碘泡,孢囊大小10～25 mm,孢子长16.82±0.43(16.03～17.69)μm,孢子宽10.26±0.43(9.12～10.88)μm,孢子厚8.09±0.29(7.50～8.75)μm,孢子长宽比1.64±0.09(1.50～1.93);大极囊长8.66±0.25(8.25～9.16)μm、宽3.65±0.25(3.01～4.19)μm,小极囊长8.35±0.28(7.60～8.85)μm、宽3.58±0.23(3.09～4.11)μm,囊间突起长1.80±0.12(1.59～2.00)μm。特异性地寄生在异育银鲫的口咽腔上颚的咽组织内、具有寄主和寄生在咽部的专一性,PCR扩增得到1 576 bp的18S rDNA序列,GenBank登录号为JQ726700。该粘孢子虫与相近的其它粘孢子虫比较,孢子长分别与白鲟碘泡虫(Myxobolus psephurusi)和扭曲碘泡虫(M.twistus)无显著差异(P>0.05),与M.ampullicapsulatus、M.wulii和鳙碘泡虫(M.aristichthydis)分别有显著差异(P<0.05);孢子宽和厚、极囊长和宽分别与M.ampullicapsulatus、M.wulii、白鲟碘孢虫(M.psephurusi)、鳙碘泡虫(M.twistus)和扭曲碘孢虫(M.aristichthydis)有显著差异(P<0.05);分子系统树分析结果显示,与M.ampullicapsulatus在同一个分支中,亲缘关系最近。从孢子形态学、寄主的特异性、寄生部位的专一性以及18SrDNA序列等特点综合比较分析,表明该粘孢子虫为一新种,命名为咽碘泡虫Myxobolus pharynae n.sp.。 相似文献
3.
C. D. MINCHEW 《Journal of fish diseases》1981,4(6):513-518
Abstract. Unicauda magna sp.n. (Protozoa: Myxozoa) was found in hatchery-raised fathead minnows, Pimephales promelas (Cyprinidae) from Pennsylvania. A large number of whitish-coloured cysts were located in the tissues of the pectoral, pelvic and caudal fins of infected fish. Spore dimensions (in μm) based on 30 measurements (10 spores/cyst) included the following: total length, 109.6 (75–170); spore body length, 15.5 (14–17); spore body thickness, 12.1 (10–13); spore body width, 13.2 (12–14.5); tail length, 94.1 (60–154); polar capsule lengths, 8.6 (7.5–9.5); polar capsule width 4.1 (3.0–5.0); sutural ridge width, about 1. The tail and body of the spores differed in colour when stained with each of three dyes. They are, therefore, composed of different material. 相似文献
4.
本研究以海带(Saccharina japonica)杂交品系“玉带1号”为研究对象,根据孢子囊形成过程中的外观形态,将孢子囊形成与发育过程分为5个阶段,系统观察了孢子囊形成过程中的外观形态和组织结构变化,研究了孢子囊发育不同阶段生理生化特征的变化规律。结果显示,在孢子囊发育过程中,孢子体表面依次出现光滑、磨砂、突起、破皮和光滑等表观现象,伴随着表皮细胞的突起、隔丝的伸长、孢子母细胞的分化与发育,以及游孢子的形成和释放等组织变化过程;另外,在孢子囊发育过程中,海带孢子体对氮的积累持续增加,蛋白含量呈先显著增加到释放游孢子阶段又有所降低的趋势;过氧化氢(H2O2)和超氧阴离子含量的变化趋势相似,在孢子囊形成初期,其含量呈先上升到后期又有所下降;不同抗氧化酶在孢子囊形成过程中的活性变化存在差异,其中,超氧化物歧化酶(MDA)活性总体呈下降趋势,而抗坏血酸过氧化物酶(APX)、过氧化物酶(POD)、过氧化氢酶(CAT)活性均呈先上升后下降的趋势,丙二醛(MDA)含量无显著变化;在孢子囊发育过程中,1,5-二磷酸核酮糖羧化酶活性呈先降低后升高的趋势,苹果酸脱氢酶(MDH)活性无显著变化。本研究有助于加深对海带杂交品种孢子囊形成过程及生理生化特征的理解,可为海带杂交品种孢子囊的人工诱导提供理论依据。 相似文献
5.
6.
Pathogenicity of Saprolegnia species associated with outbreaks of salmonid saprolegniosis in Japan 总被引：2，自引：0，他引：2
The present study was conducted to evaluate the pathogenicity and pathology of Saprolegnia salmonis NJM 9851 and Saprolegnia parasitica NJM 9868, isolated from outbreaks of saprolegniosis, against the immature stages of five species of salmonids. The cumulative mortalities of the tested fish groups that were exposed to 2 × 10 5 spore/L concentrations of S. salmonis NJM 9851 were 90% for brown trout, 93.3% for sockeye salmon and 100% for rainbow tout, masu salmon, and Japanese char. In contrast, all salmonid species exposed to 2 × 10 5 spore/L concentrations of S. parasitica NJM 9868 experienced cumulative mortalities of 100%. The histopathological changes of the saprolegniosis lesions found in all sites of infection were loss of the epidermis, edema of the hypodermis and different degrees of degenerative changes in the underlying musculature. It is clear from our results that S. salmonis NJM 9851 and S. parasitica NJM 9868 are highly pathogenic species to five species of salmonid fishes 相似文献
7.
A quantitative survey of Saprolegnia spp. in the water systems of Norwegian salmon hatcheries was performed. Water samples from 14 salmon hatcheries distributed along the Norwegian coastline were collected during final incubation in the hatcheries. Samples of inlet and effluent water were analyzed to estimate Saprolegnia propagule numbers. Saprolegnia spores were found in all samples at variable abundance. Number of spores retrieved varied from 50 to 3200 L?1 in inlet water and from 30 to >5000 L?1 in effluent water. A significant elevation of spore levels in effluent water compared to inlet water was detected. The estimated spore levels were related to recorded managerial and environmental parameters, and the number of spores in inlet water and temperature was the factor having most influence on the spore concentration in the incubation units (effluent water). Further, the relative impact of spore concentration on hatching rates was investigated by correlation analysis. From this was found that even high spore counts did not impact significantly on hatching success. 相似文献
8.
J. W. COPLAND 《Journal of fish diseases》1983,6(5):451-460
Abstract. The histopathology of Myxidium giardi infections in wild and cultured elvers, fingerlings and adult eels is described. The lesions in the target organs of the kidney and gills were minimal. Marked granulomatous changes were evident in the spleen, peritoneal fat and, to a lesser extent, the liver and gas gland. The granulomatous reaction consisted of a mononuclear infiltration into the spore mass and proliferative fibrosis of the surrounding connective tissue, Histological evidence of an immunological response is described. The types of M. giardi cysts are described-a primary interstitial cyst of the kidney and gill, a secondary cyst of the gills and a glomerular spore mass. Primary interstitial cysts in the kidney were observed to rupture and formed spore masses in the interstitial tissue. Evidence of vascular spread and the presence of spore emboli is presented. It is suggested that primary multiplication occurs in the primary interstitial cyst of the kidney and gills, and secondary multiplication in the secondary gill cyst and glomerular spore mass from which mature spores are released to the environment. 相似文献
9.
Abstract. A microsporidium, forming xenoparasitic complexes (xencmas) of the cell-hypertrophy tumour type, was found in the gills of the Atlantic cod Gadus morhua L. and studied with the electron microscope. It seemed to be similar to Nosema branchiate Nemeczek, 1911, in the haddock Melanogrammus aeglefinus (L.) except in size of spore. The xenoma (cyst) was basically like the Glugea cyst and the parasite had some other characters in common with Glugea; it was apansporoblastic, unikaryotic, disporoblastic and underwent partial development in parasitophorous vacuoles. It differed from Glugea in lacking plasmodial stages, producing usually 1 or 2 spores (rather than 16) in a vacuole, showing no distinct tendency for different stages to occur in different zones of the cyst and having tubules in the parasitophorous vacuoles. The name Loma morhua n. g., n. sp. (type) was proposed and the genus assigned to the family Glugeidae Thélohan, 1892. The parasite of haddock gill was transferred to the new genus, becoming L. branchialis (Nemeczek, 1911) n. comb. 相似文献
10.
The development of Myxobolus bramae Reuss 1906, a myxosporean parasite of the gills of common bream Abramis brama L., was studied in experimentally infected oligochaetes. In five experiments, uninfected Tubifex tubifex (Müller) and Limnodrilus hoffmeisteri Claparéde were exposed to mature myxospores of M. bramae . In four experiments triactinomyxon type actinospores developed in Tubifex specimens but no infection was found in Limnodrilus . Actinospores were released from oligochaetes 70–81 days after initial exposure. At that time pansporocysts containing eight actinospores were located in the gut epithelium of experimental oligochaetes, but free actinosporean stages were also found in their gut lumen. Each actinospore had three pyriform polar capsules and a barrel-shaped sporoplasm with 32 secondary cells. The spore body joined the three caudal projections with a stout style. The total length of the actinospore was 139 μm on the average. 相似文献
11.
Two new species of myxozoans from the Japanese anglerfish, Lophius litulon, are described using myxospore morphology and small subunit rDNA sequences. Ceratomyxa anko sp. n. is a parasite of the gall bladder and had a prevalence of 57%. Mature spores of C. anko sp. n. are arcuate to crescent shaped with valves tapering to rounded tips. A prominent sutural line runs centrally between the round adjacent polar capsules containing the polar filament coiled two to three times. Spore measurements: length 10.8 (9.7-11.9) microm, width 41.9 (36.9-47.2) microm, polar capsule diameter 4.6 (4.1-5.3) microm. Ceratomyxa anko sp. n. can be distinguished from other Ceratomyxa spp. due to its spore dimensions and shape. Zschokkella lophii sp. n. is a parasite of the urinary bladder and had a prevalence of 70%. Mature spores are ellipsoidal to semicircular with bluntly pointed ends. The sutural line is curved or sinuous and the valves have no discernable surface ornamentation. Two almost spherical polar capsules are located separately in the ends of the spore, opening in almost opposite directions and contain the polar filament with five coils. Spore measurements: length 20.1 (16.8-24.0) microm, width 14.9 (12.7-16.8) microm, polar capsule diameter 5.1 (3.6-5.8) microm. Zschokkella lophii sp. n. can be distinguished from other Zschokkella spp. due to the terminal opening of the polar capsules within the spores and the site of infection within the host fish. In the phylogenetic analyses, C. anko sp. n. grouped with other members of the same genus forming a monophyly. Zschokkella lophii sp. n. forms a discrete clade with another Zschokkella sp. that infects the urinary bladder of marine fish. This grouping forms a sister clade to one containing members of the genus Parvicapsula, all of which are parasites of the urinary system in marine fish. 相似文献
12.
Abstract. Microgemma hepaticus gen.nov. sp.nov. is described from the liver of juvenile grey mullet, Chelon labrosus (Risso). Development occurs within xenomas (diameter 500μm) which have microvillar surfaces, encircling bands of mitochondria and a reticulate hypertrophic nucleus. Vegetative developmental stages, meronts, are plasmodial and divided by plasmotomy. These stages are enclosed by host membranes. Sporogonic stages are free in the cytoplasm and divide by multiple exogenous budding. Uninucleate spores (2·4μm × 4·2μm) possess 7–9 coils of the polar filament and a lamellar polaroplast. Xenomas are associated with liver connective tissue, and cause necrosis of adjacent liver cells in certain circumstances. Host response to infection involves leucocyte infiltration and granuloma formation, with spores being destroyed by repeated macrophage phagocytosis and necrosis and resulting in gradual resolution of the lesion. Although juveniles apparently tolerate large parasite burdens there is some evidence of a contribution by the parasite to stress-related mortality. The transmission of the disease and its potentially high pathogenicity to larval fishes is discussed. 相似文献
13.
Antifungal Activity of Rhein and Aloe‐Emodin from Rheum palmatum on Fish Pathogenic Saprolegnia sp. 
下载免费PDF全文
下载免费PDF全文 Jia‐Yun Yao Ling‐Yun Lin Xue‐Mei Yuan Wen‐Lin Ying Yang Xu Xiao‐Yi Pan Gui‐Jie Hao Jin‐Yu Shen Jin‐Chun Wu Ting Ye Pei‐Hong Ge 《Journal of the World Aquaculture Society》2017,48(1):137-144
Saprolegnia infections cause severe economic losses among freshwater fish farming. In this study, two known compounds, rhein and aloe‐emodin, were isolated from Rheum palmatum, and the in vitro inhibitory activity of both compounds against mycelial growth and spore germination of Saprolegnia was tested. Both rhein and aloe‐emodin were able to decrease Saprolegnia mycelial growth and spore activity in all tested concentrations after exposure for 48 h. Complete inhibition of mycelial growth was observed at 20 mg/L for rhein and at 50 mg/L for aloe‐emodin, while spore germination was 100% prevented at 16 and 40 mg/L for rhein and aloe‐emodin, respectively. Because rhein showed stronger in vitro anti‐Saprolegnia activity, it was further tested in vivo to measure the prevention and treatment efficacy on Saprolegnia infection of grass carp. Its acute activity to grass carp was also evaluated. The results revealed that exposure to rhein at 20 mg/L for 7 d could prevent 93.3% of infections by Saprolegnia in abraded grass carp, while 67.7% of infected fish could be recovered by treatment with rhein. The 48‐h median lethal concentration (48 h‐LC50) to grass carp was 148.5 mg/L, which is about 7.4 times the effective dose indicating the safety for the use of rhein. This study suggests that rhein has promising anti‐Saprolegnia activity and may be an option in preventing and controlling Saprolegnia infection. 相似文献
14.
采用5种附着基采石花菜孢子,通过车间培育和海上育苗相结合,育出石花菜直立苗1．07 hm~2(16亩),同时探讨了育苗过程中的关键技术及存在的问题。 相似文献
15.
Abstract Snakeheads, Channa striatus (Bloch), were inoculated with a spore suspension of the specific pathogenic Aphanomyces , isolated from fish affected by epizootic ulcerative syndrome (EUS), in South East Asia. Fish were held at three different temperatures: 19, 26 and 31 °C. Histological changes induced by the infection are described. In the early stages of the disease, degenerative changes were observed in all samples, but inflammatory infiltrate was much more marked in fish kept at 26 and 31 °C. By 8 days post-injection, extensive mycotic granulomatosis was observed in the samples kept at 26 and 31 °C. The fish kept at 19 °C developed a severe invasive myonecrosis with limited macrophage response. From 14 to 28 days post-injection, healing became well established at 26 and 31 °C and surviving fish kept at these temperatures recovered completely by 28 days. The lesion was still progressing at 21 days post-injection in fish kept at 19 °C, and all such fish succumbed by this time. Thus, mortalities in the fish kept at 19 °C were considerably higher than in the groups of fish kept at 26 and 31 °C. The findings help to explain why mortalities from EUS occur when water temperatures are low. 相似文献
16.
《Journal Of Aquatic Food Product Technology》2013,22(4):75-93
ABSTRACT Sixteen batches of fish mince prepared using fillets from Pacific hake (Merluccius productus) harvested near Vancouver Island, Canada were studied for possible correlations of Kudoa spore counts with proteolytic activity and cooked texture. The fish were mainly infected by K. paniformis, and Kudoa spores were distributed throughout 7 sampling sites on 13 individual hake fish tested. Proteolytic activity of fish homogenate was optimum within the range of pH 5.25–5.50 and 52–55°C. Significant (p < 0.05) correlations were observed among fish mince K. paniformis spore counts, endogenous proteolytic activity, cooked texture measured as maximum compression force (g), and the change in free amino groups during autolysis. 相似文献
17.
Dawson-Coates JA Chase JC Funk V Booy MH Haines LR Falkenberg CL Whitaker DJ Olafson RW Pearson TW 《Journal of fish diseases》2003,26(8):451-459
Atlantic salmon, Salmo salar L., were exposed to Kudoa thyrsites (Myxozoa, Myxosporea)-containing sea water for 15 months, and then harvested and assessed for parasite burden and fillet quality. At harvest, parasites were enumerated in muscle samples from a variety of somatic and opercular sites, and mean counts were determined for each fish. After 6 days storage at 4 degrees C, fillet quality was determined by visual assessment and by analysis of muscle firmness using a texture analyzer. Fillet quality could best be predicted by determining mean parasite numbers and spore counts in all eight tissue samples (somatic and opercular) or in four fillet samples, as the counts from opercular samples alone showed greater variability and thus decreased reliability. The variability in both plasmodia and spore numbers between tissue samples taken from an individual fish indicated that the parasites were not uniformly distributed in the somatic musculature. Therefore, to best predict the probable level of fillet degradation caused by K. thyrsites infections, multiple samples must be taken from each fish. If this is performed, a mean plasmodia count of 0.3 mm(-2) or a mean spore count of 4.0 x 10(5) g(-1) of tissue are the levels where the probability of severe myoliquefaction becomes a significant risk. 相似文献
18.
Suwen Chen Lixiong Chen Changbo Zhu Yongjian Guo Yihui Guo 《Journal of the World Aquaculture Society》2014,45(4):487-492
Two experiments were conducted to study Gloiopeltis furcata spore culture with different substrates in the nonreproduction season. Using spores discharged by fertile G. furcata frozen for storage, two experiments were conducted during the nonreproduction season. In the first experiment, G. furcata spores were collected and incubated in aquariums using palm line, polythene line, vinylon line, and three types of plastic sheets (white, ripple, and transparent polymethyl methacrylate) as substrates. In the second experiment, G. furcata spores were collected and incubated in a plastic tank using plastic sheets of different materials (PP, PE, and transparent PVC) and plastic even nets of different mesh sizes (3, 2, and 0.5 cm) as substrates. At the end of the experiment (after 60 d), discs with raised thallus were found on different plastic sheets and white plastic even nets, but no discs were visible on any type of line or on the black plastic even net (3‐cm mesh). The white plastic even net was found to be a suitable substrate for G. furcata spore culture in farms and for sporeling culture in sea. Results presented in this study are expected to aid in the progress of the artificial seeding of Gloiopeltis. 相似文献
19.
Abstract. Tetramicra brevifilum gen, n. sp, n. is described from the connective tissues throughout the body musculature of turbot Scophthalmus maximus (L.). Uninucleate spores (4.8·2 μm) are characterized by a large posterior vacuole, electron dense inclusion bodies in cytoplasm and nucleus and short filaments with 3–5 coils (50 μm extruded). Sporogony is apansporoblastic and tetrasporoblastic, within a host vacuole. Features of the xenoma (2 mm diameter) include a microvillous surface layer with microtubules and microfilaments and a reticulate nucleus with numerous nucleoli. Adherence between adjacent xenomas results in composite cysts of various sizes and shapes depending on site, being dendritic in the myomeres, arms extending between the fibres. Effects on the host, other than eventual destruction of the host cell, include displacement of muscle fibres in myomeres with loss of attachment to myocommata. Breakdown of the xenoma with release of spores into the connective tissue matrix was associated with a localized necrosis affecting surrounding muscle fibres, with leucocyte infiltration and collagen deposition. Spores phagocytosed by macrophages were destroyed in vacuoles, some with multi-laminate walls. Experimental infections established by intramuscular injection at marked sites remained localized, which suggested that xenomas afford sufficient scope for spore production without the need of secondary invasion. The swimming efficiency of turbot would be impaired in severe infections leading to lowered growth rates and increased mortality in wild populations due to predation and starvation. Feeding hierarchies exist in turbot and the disease could prove significant in farming conditions. 相似文献
20.
Year-round induction of sporogenesis of Laminaria saccharina was performed by mechanically blocking the transport of the putative sporulation inhibitors produced by the blade meristem and culturing the plants in constant short days. Sporogenesis was successfully induced by removal of the blade meristem, either by cultivating distal blade fragments or by performing a transverse cut in the frond. The earliest sorus formation after artificial induction was 10 days. The age of the sporophytes used for induction was 6–11 months or 2 years in tank-grown or field-collected sporophytes, respectively. Zoospores were successfully released in all cases. Thus, by year-round artificial induction of sporogenesis, (1) sporeling production of L. saccharina and thereafter sporophyte cultivation could be achieved without seasonal limitation, and (2) the life cycle of L. saccharina (from spore to spore) could be completed within 8 months under controlled conditions. 相似文献