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  • 1
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The giant freshwater prawn, Macrobrachium rosenbergii, is facing increased threat due to disease as its culture becomes more widespread. A disease characterized by the swelling of the branchiostegal region and deformities of the appendages, named balloon disease by farmers, has caused considerable economic loss in the Nellore region of Andhra Pradesh, India. Clinical signs of diseased animals include a voluminous hypertrophy of some gill filaments and the inner area of the branchiostegite. By histology, hypertrophied areas at the level of the gill filaments or branchiostegite had an identical structure corresponding to a large cyst filled with a fluid containing a few free haemocytes, limited on one side by the cuticle and on the other by the subcuticular epithelial layer. Analysis of the diseased prawns did not reveal any pathogenic agent leading us to conclude that the disease is idiopathic, probably due to suboptimal water quality conditions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of fish diseases 27 (2004), S. 0 
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: A new reovirus was recently isolated from a freshwater crab, the Chinese mitten crab, Eriocheir sinensis, in China. The complete viral particles are 55 nm in diameter, icosahedral, non-enveloped and have a mean buoyant density of 1.39 g cm−3 in CsCl gradient. The viral genome is composed of 12 pieces of dsRNA with an electrophoretic pattern of 3/4/2/3. This virus infects connective tissue of the gills, gut and hepatopancreas. Partial cDNA cloning and sequence analysis showed that the RNA-dependent RNA polymerase is located in the first RNA segment. From its biochemical, ultrastructural and physicochemical properties, this virus is quite different from the genus Aquareovirus (Reoviridae). It may represent a new genus of Reoviridae, different from the other crab reoviruses, P and W2.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The availability of specific and rapid detection methods is essential for monitoring the health status of farmed species, particularly in viral diseases as in this case early diagnosis is a critical factor in containing disease outbreaks. Three complementary genome-based methods were developed for the detection of Macrobrachium rosenbergii nodavirus (MrNV), i.e. dot-blot hybridization, in situ hybridization and reverse transcriptase-polymerase chain reaction (RT-PCR). Detection limits were established for dot-blot hybridization and RT-PCR and are c. 7 fg and 8 pg of viral RNA, respectively. In situ hybridization indicated that infection was confined to the striated muscle tissue. As a result of its sensitivity, RT-PCR can be used for in-depth investigations to examine the extent of the viral infection and establish the onset of infection in hatcheries. The application of RT-PCR on samples collected from prawn farms in China showed the possible use of this method in routine health monitoring.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: White-clawed crayfish, Austropotamobius pallipes, were endemic to the Nant watershed, Ardéche, France, until they were extirpated by epizootic mortality at the beginning of the twentieth century. A. pallipes were successfully reintroduced to the Nant watershed in the middle of the twentieth century. However, epizootic mortality was observed in the Nant watershed in the summer of 2000 during which time A. pallipes was extirpated from downstream regions. Dead and moribund crayfish were again detected in several episodes in summer 2001 and by October the range of A. pallipes was reduced to the headwaters of just one of the three streams in the watershed. Water quality for the watershed in summer 2001 was appropriate for crayfish habitation. Bacteriology and mycology on A. pallipes collected during several of the mortality episodes in 2001 failed to reveal a cause. However, histopathology revealed a high occurrence of intranuclear eosinophilic inclusions in hepatopancreatocytes of A. pallipes. The nuclei were hypertrophic and contained bacilliform virions consisting of a cylindrical nucleocapsid surrounded by a trilaminar envelope. Virions in section were approximately 63 × 258 nm and nucleocapsids were approximately 52 × 225 nm. It is unclear whether the intranuclear bacilliform virus was the cause of the mortality episodes or was a contributor to a disease complex involving one or several other undetected pathogens.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of fish diseases 28 (2005), S. 0 
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of fish diseases 28 (2005), S. 0 
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: White spot syndrome virus (WSSV) is a serious pathogen of aquatic crustaceans. Little is known about its transmission in vivo and the immune reaction of its hosts. In this study, the circulating haemocytes of crayfish, Procambarus clarkii, infected by WSSV, and primary haemocyte cultures inoculated with WSSV, were collected and observed by transmission electron microscopy and light microscopy following in situ hybridization. In ultra-thin sections of infected haemocytes, the enveloped virions were seen to be phagocytosed in the cytoplasm and no viral particles were observed in the nuclei. In situ hybridization with WSSV-specific probes also demonstrated that there were no specific positive signals present in the haemocytes. Conversely, strong specific positive signals showed that WSSV replicated in the nuclei of gill cells. As a control, the lymphoid organ of shrimp, Penaeus monodon, infected by WSSV was examined by in situ hybridization which showed that WSSV did not replicate within the tubules of the lymphoid organ. In contrast to previous studies, it is concluded that neither shrimp nor crayfish haemocytes support WSSV replication.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: White tail disease of the farmed freshwater prawn, Macrobrachium rosenbergii, is the cause of mortalities in the French West Indies, China and India. Two different sized particles, both developing in the cytoplasm of target cells, are found associated with diseased animals. These two viruses were separated, purified and subsequently characterized. The larger one, called MrNV, is icosahedral in shape and 27 nm in diameter. Its genome is composed of two fragments of linear single-stranded RNA (ss-RNA), of 2.9 and 1.3 kb, respectively and its capsids exhibited a single polypeptide of 43 kDa. These characteristics and the partial sequence of a cloned fragment of RNA-1 suggest this agent is a member of the family Nodaviridae, but with differences from both the genera Alphanodavirus and Betanodavirus. The smaller virus, named XSV, is icosahedral in shape, 15 nm in diameter, possesses a linear ss-RNA genome of about 0.9 kb, and its capsid exhibits two polypeptides of 16 and 17 kDa, respectively. The relationships between these two viruses remain unknown.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 10 (1987), S. 0 
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: A disease of Macrobrachium rosenbergii, the giant freshwater prawn, farmed in China was recently recorded in Zhejiang, Jiangsu, Shanghai, Guangxi and Guangdong provinces. The clinical sign of the disease, which develops in post-larvae (PL), is a whitish appearance of the muscles, particularly noticeable in the abdomen. Mortalities may reach 100% in some hatcheries. Investigations by transmission electron microscopy after negative staining of diseased PL homogenates showed the presence of two types of viral particles: one, unenveloped, icosahedral in shape, 26–27 nm in diameter, the second, much smaller, about 14–16 nm in diameter, designated extra small virus particle (XSV). The large virus has a genome with two pieces of ssRNA (RNA-1 and RNA-2), of 3 and 1.2 kb, respectively. Hybridization tests confirmed that this large virus is closely related to M. rosenbergii nodavirus (MrNV) which was isolated from diseased prawns in a hatchery in the French West Indies. Its very small size and hypothesized biochemical and biological characteristics suggest XSV is a new type of crustacean virus. As XSV has always been found associated with the larger virus (nodavirus) and is located in muscle and connective cells of diseased animals, it could be an autonomous virus, a helper-type virus or a satellite-like virus.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of fish diseases 27 (2004), S. 0 
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: White spot syndrome virus (WSSV) isolated from Penaeus monodon was found to be highly infective for the western Mediterranean shrimp, Palaemon sp. Using polymerase chain reaction (PCR), it was demonstrated that such shrimp are not naturally carriers of WSSV. Following challenge with virus, mortality reached 100% 3.5–4 days after injection at 22 °C. Incubation of infected shrimp at 10 °C totally suppressed the mortality which rapidly developed when shrimp were returned to 18 or 22 °C. Preincubation of WSSV with mature synthetic mytilin significantly reduced shrimp mortality with a 50% efficient dose of about 5 μm. Survival of shrimp was not due to the development of an active mechanism of defence as re-injection of WSSV produced the same mortality pattern. Mortality was probably due to WSSV replication as dot blot failed to detect viral DNA in the injection sample but was positive 1 day post-injection. Protection by mytilin was by interaction at the virus level, preventing replication as no WSSV nucleic acid was detected by PCR even after 7 days in shrimp injected with WSSV preincubated with 10 or 50 μm mytilin.
    Materialart: Digitale Medien
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