RESUMO
Background: White spot syndrome virus is a pathogen of major economic importance to cultured penaeid shrimp industries globally. White spot disease can cause mortalities reaching 100% within 3-10 days of gross signs appearing. WSSV replicates in tissues from mesoderm and ectoderm embryonic origin and characteristically induces cell nuclei hypertrophy and intra nuclear inclusion bodies. WSSV also has an extremely broad host range including marine and freshwater crabs and crayfishes, copepods and other arthropods in addition to shrimp. Water temperature can affect the progress of WSD in crustaceans but there have been conflicting reports of higher temperatures protecting Litopenaeus vannamei shrimp but lower temperatures protecting Marsupenaeus japonicas. Here we have examined how 2 water temperatures affect the progression of WSD in the freshwater crayfish Astacus leptodactylus. Materials, Methods & Results: Freshwater Astacus leptodactylus crayfi sh (20 ± 0.5 g) were obtained from Aras dam, Iran. Crayfish were acclimated for 10 days in an aerated indoor cement tank with flow-through of dechlorinated freshwater with the flow rate set at 0.5 L/s, water temperature 15 ± 1ºC and dissolved oxygen 5.2 ppm. Two groups of 25 crayfish were allocated to tanks being supplied 15 ± 1C water and 2 groups of 25 crayfish were allocated to tanks being supplied 25 ± 1C water. Each crayfish
Background: White spot syndrome virus is a pathogen of major economic importance to cultured penaeid shrimp industries globally. White spot disease can cause mortalities reaching 100% within 3-10 days of gross signs appearing. WSSV replicates in tissues from mesoderm and ectoderm embryonic origin and characteristically induces cell nuclei hypertrophy and intra nuclear inclusion bodies. WSSV also has an extremely broad host range including marine and freshwater crabs and crayfishes, copepods and other arthropods in addition to shrimp. Water temperature can affect the progress of WSD in crustaceans but there have been conflicting reports of higher temperatures protecting Litopenaeus vannamei shrimp but lower temperatures protecting Marsupenaeus japonicas. Here we have examined how 2 water temperatures affect the progression of WSD in the freshwater crayfish Astacus leptodactylus. Materials, Methods & Results: Freshwater Astacus leptodactylus crayfi sh (20 ± 0.5 g) were obtained from Aras dam, Iran. Crayfish were acclimated for 10 days in an aerated indoor cement tank with flow-through of dechlorinated freshwater with the flow rate set at 0.5 L/s, water temperature 15 ± 1ºC and dissolved oxygen 5.2 ppm. Two groups of 25 crayfish were allocated to tanks being supplied 15 ± 1C water and 2 groups of 25 crayfish were allocated to tanks being supplied 25 ± 1C water. Each crayfish
RESUMO
Background: White spot syndrome virus is a pathogen of major economic importance to cultured penaeid shrimp industries globally. White spot disease can cause mortalities reaching 100% within 3-10 days of gross signs appearing. WSSV replicates in tissues from mesoderm and ectoderm embryonic origin and characteristically induces cell nuclei hypertrophy and intra nuclear inclusion bodies. WSSV also has an extremely broad host range including marine and freshwater crabs and crayfishes, copepods and other arthropods in addition to shrimp. Water temperature can affect the progress of WSD in crustaceans but there have been conflicting reports of higher temperatures protecting Litopenaeus vannamei shrimp but lower temperatures protecting Marsupenaeus japonicas. Here we have examined how 2 water temperatures affect the progression of WSD in the freshwater crayfish Astacus leptodactylus. Materials, Methods & Results: Freshwater Astacus leptodactylus crayfi sh (20 ± 0.5 g) were obtained from Aras dam, Iran. Crayfish were acclimated for 10 days in an aerated indoor cement tank with flow-through of dechlorinated freshwater with the flow rate set at 0.5 L/s, water temperature 15 ± 1ºC and dissolved oxygen 5.2 ppm. Two groups of 25 crayfish were allocated to tanks being supplied 15 ± 1°C water and 2 groups of 25 crayfish were allocated to tanks being supplied 25 ± 1°C water. Each crayfish was injected intramuscularly into soft tissue at the base of swimming legs with either 50 µL inoculum containing 103.2 lethal units/mL. A negative control group of crayfish was injected with PBS. Mortality amongst groups was monitored for 30 days and WSSV DNA present in haemolymph collected on Days 3, 5 and 10 post-injection was detected by nested-PCR. Morbidity and mortalities amongst crayfish held in lower temperature water were delayed and WSSV DNA was detected by nested-PCR at Day 10 pi compared to being clearly detected at Days 3, 5 and 10 pi amongst crayfish held in higher temperature water. Evidence of eosinophilic intranuclear inclusions detected by histology correlated with when WSSV was first detected by nested-PCR. Discussion: The data indicate that low water temperature retards WSSV replication in A. leptodactylus crayfi sh. Similar temperature-related effects on WSD progression have been reported in other freshwater crayfish species. For example, no mortality occurred amongst WSSV-infected Pacifastacus leniusculus held in either 4 ± 2°C or 12 ± 2°C water, but all crayfish died with WSD symptoms after they were transferred to 22 ± 2°C water. In another study, Procambarus clarkia held in 24 ± 1°C water all died by Day 9 post-challenge with WSSV but amongst crayfish held in 18 ± 1°C water, mortality only started on Day 10 post-challenge and in took until Day 22 before all had died, and amongst crayfish held in 10 ± 1°C water, no deaths occurred up to Day 24 post-challenge when the bioassay was terminated. A. leptodactylus injected with WSSV and maintained in 15 ± 1°C water only became moribund and nested-PCR-positive for WSSV by Day 10 pi in contrast to crayfish held in 25 ± 1°C water that started to die and were PCR-positive on Day 3 pi. Unlike WSD in shrimp, no histological evidence of basophilic intra nuclear inclusions was observed in WSSV-infected crayfish tissues even in the late stages of disease. This might be attributed to the over expression of anti-lipopolysaccharide factor in crayfish and/or the low numbers of apoptotic haemocytes that develop in WSSV-infected crayfish compared to the shrimp. Whether the over-expression of anti-lipopolysaccharide factor in combination with lowered WSSV replication induced by lowered water temperature both contributed to slowing the progress of WSD in Astacus leptodactylus warrants further investigation.
Assuntos
Animais , Reação em Cadeia da Polimerase/veterinária , Astacoidea/virologia , Palaemonidae/virologia , Vírus da Síndrome da Mancha Branca 1/patogenicidadeRESUMO
Background: White spot syndrome virus is a pathogen of major economic importance to cultured penaeid shrimp industries globally. White spot disease can cause mortalities reaching 100% within 3-10 days of gross signs appearing. WSSV replicates in tissues from mesoderm and ectoderm embryonic origin and characteristically induces cell nuclei hypertrophy and intra nuclear inclusion bodies. WSSV also has an extremely broad host range including marine and freshwater crabs and crayfishes, copepods and other arthropods in addition to shrimp. Water temperature can affect the progress of WSD in crustaceans but there have been conflicting reports of higher temperatures protecting Litopenaeus vannamei shrimp but lower temperatures protecting Marsupenaeus japonicas. Here we have examined how 2 water temperatures affect the progression of WSD in the freshwater crayfish Astacus leptodactylus. Materials, Methods & Results: Freshwater Astacus leptodactylus crayfi sh (20 ± 0.5 g) were obtained from Aras dam, Iran. Crayfish were acclimated for 10 days in an aerated indoor cement tank with flow-through of dechlorinated freshwater with the flow rate set at 0.5 L/s, water temperature 15 ± 1ºC and dissolved oxygen 5.2 ppm. Two groups of 25 crayfish were allocated to tanks being supplied 15 ± 1C water and 2 groups of 25 crayfish were allocated to tanks being supplied 25 ± 1C water. Each crayfish
Background: White spot syndrome virus is a pathogen of major economic importance to cultured penaeid shrimp industries globally. White spot disease can cause mortalities reaching 100% within 3-10 days of gross signs appearing. WSSV replicates in tissues from mesoderm and ectoderm embryonic origin and characteristically induces cell nuclei hypertrophy and intra nuclear inclusion bodies. WSSV also has an extremely broad host range including marine and freshwater crabs and crayfishes, copepods and other arthropods in addition to shrimp. Water temperature can affect the progress of WSD in crustaceans but there have been conflicting reports of higher temperatures protecting Litopenaeus vannamei shrimp but lower temperatures protecting Marsupenaeus japonicas. Here we have examined how 2 water temperatures affect the progression of WSD in the freshwater crayfish Astacus leptodactylus. Materials, Methods & Results: Freshwater Astacus leptodactylus crayfi sh (20 ± 0.5 g) were obtained from Aras dam, Iran. Crayfish were acclimated for 10 days in an aerated indoor cement tank with flow-through of dechlorinated freshwater with the flow rate set at 0.5 L/s, water temperature 15 ± 1ºC and dissolved oxygen 5.2 ppm. Two groups of 25 crayfish were allocated to tanks being supplied 15 ± 1C water and 2 groups of 25 crayfish were allocated to tanks being supplied 25 ± 1C water. Each crayfish
RESUMO
This study compares the morphology of rostrum, pereipods 1,2,4 and mouthparts of juvenile Astacus leptodactylus with those oí Pacifastacus leniusculus. Differences in morphology were observed, in particular with regard to the mouthparts e.g. including setal armature and number of teeth on the mandible. In general, the shape of the rostra in the two species is similar in that both taper to a point with a pair of sharp spines distally. Laterally the rostrum of A. leptodactylus is bordered by a regular row of setae, which is not so well defined in P leniusculus. The observations also showed that in addition to an increase in size, changes in morphology in the feeding apparatus between the developmental stages of the two species were present. It was concluded that both species have similar rostra, but different setal patterns and there are differences between the two species in the armature of mouthparts as development progresses. Therefore, important differences in the morphology of mouthparts between P. leniusculus and A. leptodactylus and in the different stages of the species might cause a difference in the feeding behavior and food choice of the species.
Este estudio compara la morfología del rostro, pereiópodos 1,2,4 y piezas bucales de los Astacus leptodactylus jóvenes con los de Pacifastacus leniusculus. Se observaron las diferencias en la morfología, en particular, con respecto a las piezas bucales, por ejemplo incluyendo la armadura setal y el número de dientes en la mandíbula. En general, la forma del rostro en las dos especies es similar, tanto cónicas, como en punta, con un par de espinas distalmente. Lateralmente al rostro, A. leptodactylus está bordeada por un fila de setas, que no está tan bien definida en P leniusculus. Las observaciones también muestran que, además de un aumento en el tamaño, estaban presentes cambios en la morfología en el aparato masticatorio, entre las etapas de desarrollo de las dos especies. Se llegó a la conclusión que ambas especies tienen rostros similares, pero diferentes patrones setales y hay diferencias entre las dos especies en la armadura de piezas bucales como evolución del desarrollo. Por lo tanto, importantes diferencias en la morfología de piezas bucales entre P leniusculus y A. leptodactylus y en las distintas etapas de la especie podrían causar una diferencia en la conducta de alimentación y opciones de alimentación de la especie.