Life cycle of Calyptospora funduli (Apicomplexa: Calyptosporidae)

The taxonomic status of the extraintestinal piscine coccidium Calyptospora funduli is based in part on its requirement of an intermediate host (the daggerblade grass shrimp Palaemonetes pugio). In the present study, grass shrimp fed livers of Gulf killifish (Fundulus grandis) infected with sporulated oocysts of C. funduli exhibited numerous sporozoites suspended in the intestinal contents when fresh squash preparations were examined by light microscopy. Using this method, sporozoites were not seen in intestinal epithelial cells of the grass shrimp or in any other cell types. Ultrastructural examination, however, revealed sporozoites in the cytoplasm of the gut basal cells. Cross-sections of 1-13 sporozoites were seen within a single cell, and those sporozoites each appeared to be situated in individual membrane-bound vesicles, rather than in a single parasitophorous vacuole. These ultrastructural observations indicate that in the grass shrimp intermediate host, sporozoites that develop into an infective stage probably undergo that development in gut mucosal basal cells. Prior studies revealed that these sporozoites modified their structure over 4-5 days and that before that time, they were not infective to the fish host. Following ingestion of an infected shrimp by a killifish, the infective sporozoites apparently reach the liver of their killifish definitive hosts through the bloodstream. Sporozoites were seen in blood smears from the longnose killifish, Fundulus similis, 4 hr after fish were fed experimentally infected grass shrimp. Additionally, coccidian trophozoites and early meronts were seen in hepatocytes from several longnose killifish at 48, 72, and 96 hr postinfection. This study, in conjunction with previous findings, clearly confirms that a true intermediate host is required in the life cycle of C. funduli, that a developmental period of about 5 days in grass shrimp is necessary for sporozoites to become infective to killifishes, and that sporozoites do occur intracellularly in gut basal cells of the grass shrimp.     

Intermediate host of Mediorhynchus orientalis (Acanthocephala: Gigantorhynchidae)

During an acanthocephalan epizootic at the Pittsburgh aviary, an intermediate host for Mediorhynchus orientalis was found for the first time and 2 new potential intermediate hosts for the genus Mediorhynchus were noted. The cockroaches Pycnoscelis surinamensis and Periplaneta americana were found infected with acanthellae and appear to be suitable intermediate hosts.     

Taxonomic status of Choanoscolex lamothei García-Prieto, 1990 (Cestoda: Proteocephalidea) using morphological and molecular evidence

The taxonomic status of Choanoscolex lamothei, a proteocephalidean tapeworm described from the catfish Ictalurus meridionalis (= I. furcatus) from Oaxaca, Mexico, was evaluated on the basis of morphological examination of types and freshly collected specimens from the type host and partial sequences of the large subunit (28S) ribosomal DNA. This study revealed that C. lamothei is a species of Megathylacoides (Proteocephalidae: Corallobothriinae) because of the medullary position of the genitalia (entirely cortical in Choanoscolex), the presence of semispherical sphincters on the suckers, a follicular ovary, and the alternating position of the vagina. Megathylacoides lamothei n. comb. differs from congeneric species in lacking an apical organ and in the number (130-208) of testes. Molecular data confirm the position of M. lamothei within Megathylacoides, which contains species parasitizing ictalurid fishes in North America.     

Phylogenetic analysis on genera of Corallobothriinae (Cestoda: Proteocephalidea) from North American ictalurid fishes, using partial sequences of the 28s ribosomal gene

Partial sequences of the 28S rDNA (ribosomal gene) were obtained from a total of 11 populations of 5 species (in 3 genera) of North American corallobothriine proteocephalideans. These included Corallobothrium fimbriatum (3 populations), Corallobothrium parafimbriatum (1 population), Corallotaenia minutia (1 population), Megathylacoides giganteum (2 populations), and Megathylacoides lamothei (4 populations). These sequences were used in a phylogenetic analysis to test the monophyly of Corallobothriinae and to investigate the interrelationships of the North American species. The results indicate that Corallobothriinae, as conventionally understood, is not monophyletic and that only the North American corallobothriines, parasites of ictalurid catfishes, form a monophyletic group. Corallobothrium parafimbriatum is sister taxon to a clade that includes Corallotaenia intermedia and C. minutia and not to its congener C. fimbriatum. Also, M. giganteum from Mexico appears to be more closely related to M. lamothei than to its conspecific in Canada. This and the amount of sequence divergence indicate possible cryptic speciation in its endemic host, the Lerma catfish, Ictalurus dugesi.     

Effects of Microphallus turgidus (Trematoda: Microphallidae) on the predation, behavior, and swimming stamina of the grass shrimp Palaemonetes pugio

The effect of the trematode Microphallus turgidus on its second intermediate host, the grass shrimp, Palaemonetes pugio, was tested. To do so, we measured the susceptibility of infected and uninfected shrimp to predation by the mummichog, Fundulus heteroclitus. Shrimp behavior was compared in the presence and absence of a fish predator, and the swimming stamina and backthrust escape responses of infected and uninfected shrimp were measured. Infected shrimp were more likely to be eaten by a predator than uninfected shrimp, had lower swimming stamina, and spent more time swimming and less time motionless in the presence of a predator. There was no difference between backthrust distances traveled in response to a stimulus by either infected or uninfected shrimp. Thus, M. turgidus may increase the predation of P. pugio in the wild, possibly by affecting the swimming stamina and predator avoidance responses of the shrimp.     

A new species ofMicrodajus (Crustacea: Tantulocarida) parasitic on a tanaid in the northeastern Atlantic,with observations onM. langi Greve

The tantulus larva ofMicrodajus langi is redescribed using Scanning Electron Microscopy. Thoracopods 2–5 have poorly developed but fully armed endites. Thoracopods 1–5 are biramous, with each ramus represented by a minute segment. A new species,M. pectinatus, is described from a tanaid host collected in the Rockall Trough, off the west coast of Scotland. A system of homologies for the portopodal segments of the thoracopods of the tantulus larva is proposed. Some aspects of the musculature of the adult male are described for the first time.     

Prevalence,geographic distribution,and fitness effects of Microphallus turgidus (trematoda: Microphallidae) in grass shrimp (Palaemonetes spp.) from coastal Georgia

Grass shrimp, Palaemonetes pugio Holthuis and P. vilgaris (Say), were collected at 11 localities along the coast of Georgia and surveyed for digenetic trematode metacercariae. The effect of trematode infection on grass shrimp fitness was also examined. Microphallus turgidas (Leigh) was the only trematode observed. The prevalence of metacercarial cysts of this parasite in P. pugio (75%) was higher than in P. vulgaris (24%), as were the mean intensity, abundance, and population density (no. cysts/cm host body length) of the parasite. Infected shrimp were found at every collection locality and parasite prevalence and density were greatest in P. pugio from higher salinity localities (> or = 20 parts per thousand [ppt]). There was no relation between host body size and parasite density in P. vulgaris, and parasite density increased with host body size in P. pugio, suggesting that the parasite does not affect host survival. There was no relation between parasite density and shrimp egg mass, but nonovigerous female P. pugio were more heavily infected than ovigerous ones. In addition, 1 metacercaria of M. turgidus in each of 2 specimens of P. vulgaris was parasitized by the haplosporidian Urosporidium crescens De Turk. This represents a new shrimp host record for this hyperparasite.     

Two new species of Gyrodactylus von Nordmann, 1832 (Monogenea: Gyrodactylidae) parasitizing Girardinichthys multiradiatus (Cyprinodontiformes: Goodeidae), an endemic freshwater fish from central Mexico

Gyrodactylus mexicanus n. sp. and Gyrodactylus lamothei n. sp. are described from the fins and skin of Girardinichthys multiradiatus, an endemic freshwater fish from central Mexico. Gyrodactylus mexicanus is compared to other Gyrodactylus species that parasitize Fundulus spp., the phylogenetically closest group to the Goodeidae from North America. Gyrodactylus mexicanus is distinguished by having large anchors with well-developed superficial roots, enlarged hooks with a proximally disrupted shank (ligament), and a ventral bar with 2 poorly developed anterolateral projections and a small medial process. Gyrodactylus lamothei is distinguished from G. mexicanus and from other species of Gyrodactylus on the North American continent by having anchors with a sclerite on the superficial root and robust hooks with a straight shaft and a recurved point.     

The life cycle of Euclinostomum heterostomum (Rudolphi, 1809) (Trematoda: Clinostomatidae)

In small forest streams of West Nigeria the snail species Bulinus globosus was found to be the first intermediate host of a clinostomatid species which proved in successful infection experiments with the cichlid fish Tilapia zillii as second intermediate host to be Euclinostomum heterostomum (Rudolphi, 1809). Final hosts are herons. The morphology of the redia and the morphology and behaviour of the cercaria are described for the first time. The metacercaria which settles dorsal to the swim-bladder or in the kidney of the host fish requires more than two months (at tropical temperatures) for full development. Histological sections of the metacercaria revealed that its pharynx is provided with only few muscle fibres but surrounded by many myoblast-like cells, and the fact that the interior surface of this organ has a dense brush-like lining consisting of long microtriches. The pathology of infected fish is briefly described, and remarks about the geographical distribution of the parasite are given.     

Effects of the trematode Microphallus turgidus on locomotion and prey capture in the grass shrimp Palaemonetes pugio

The grass shrimp, Palaemonetes pugio, is common in estuaries and marshes along the east coast of the USA and is frequently infected with metacercariae of the trematode, Microphallus turgidus. To test whether or not M. turgidus has an effect on intermediate host behaviour, the length of time spent swimming and walking over 1 min and 3 min intervals and prey (Artemia) capture rates of uninfected grass shrimp and those infected with 1-10, 11-20 or 21-30 metacercarial cysts were compared. Uninfected shrimps spent significantly more time swimming than infected shrimps during the first minute of observation. There were no differences between the control and infected groups in terms of swimming at 3 min, walking at 1 and 3 min, or in numbers of prey captured. These results indicate that M. turgidus may induce little or no change in grass shrimp locomotion nor in prey capture behaviour. This is in contrast to other parasites that modify intermediate host behaviour to enhance their transmission to definitive hosts. Furthermore, these data support earlier studies indicating that M. turgidus does not affect the growth and survival of P. pugio.     

Identification of genes involved in the response of haemocytes of Penaeus japonicus by suppression subtractive hybridization (SSH) following microbial challenge

Penaeus japonicus were injected with a heat-killed microorganism suspension and 291 randomly selected cDNA fragments generated by suppression subtractive hybridization (SSH) were sequenced. A total of 71 cDNA clones corresponding to 25 genes were found to have enhanced expression, of which eight are found for the first time in shrimp. The most abundant gene in the subtractive library was Kunitz-type protease inhibitor, clearly indicating this protease inhibitor in the response. A number of genes encoding signaling molecules, such as Ras-related nuclear protein (Ran), growth factor receptor bound protein (Grb), TGF-beta receptor interacting protein, integrin binding protein and interferon receptor bound protein were found for the first time in the shrimp, and they may be involved in the regulation of the host defense against the injected microbes. Furthermore, cDNAs of chaperonin, proteasome, antioxidant as well as genes associated with actin reorganization, which may be necessary for phagocytosis and encapsulation, were also expressed at a higher level after the challenge. These results may facilitate the understanding of shrimp immune responses.     

The incidence of Anisakis sp. larvae (Nematoda: Ascaridata) in the commercially exploited stocks of herring (Clupea harengus L., 1758,) (Pisces: Clupeidae) in British and adjacent waters.

10 000 herrings from the commercial fisheries around the coasts of Great Britain and Ireland were examined for the nematode larva Anisakis sp. between October 1968 and October 1970. Heavy infestations were found in the North Sea stocks, moderate infestations west of Scotland and minimal infestations elsewhere; but nowhere was the parasite completely absent. Younger fish were often found to be more heavily infested than older fish and it is therefore suggested that the accumulation of larvae in the body cavity may be affected by annual fluctuations either in the population of an infested first intermediate host or in the extent to which the herrings are feeding on this host. A small but constant proportion of the parasites penetrate the musculature of the herring regardless of other factors such as the age or length of the host, or the number of other larvae present.     

Effects of the parasite Probopyrus ringueleti (Isopoda) on glucose, glycogen and lipid concentration in starved Palaemonetes argentinus (Decapoda)

Effects of the branchial ectoparasite isopod Probopyrus ringueleti on the utilization of glucose, glycogen and total lipids on starved shrimp Palaemonetes argentinus were evaluated, as well as the isopod responses to host starvation. Shrimp were maintained for 12 d under laboratory conditions. Parasitized and unparasitized shrimp were starved for 15 d, and glucose, glycogen and total lipid concentrations were determined at 0, 24, 72, 168 and 360 h of starvation. During starvation, control animals (unparasitized) preferentially metabolized lipids and preserved their carbohydrate reserves. Parasitized shrimp had lower lipid concentrations than unparasitized shrimp, and preferentially metabolized carbohydrates. Bopyrids displayed a similar response, with glycogen depleted at the beginning of the starvation period followed by subsequent reestablishment. Our results demonstrated that bopyrids affect host energy allocation. The lower initial lipid concentration of parasitized shrimp suggested that the host is disadvantaged from both food deprivation and isopod nutritional demands. A possible dependency of P. ringueleti on the mechanisms that control host metabolic processes was also suggested.     

Microdajus tchesunovi sp. n. (Tantulocarida, Microdajidae) - A new crustacean parasite of from the White Sea

A new species of Tantulocarida, Microdajus tchesunovi sp. n., was found on tanaid host, Typhlotanais sp. of the family Nototanaidae, collected from silty sediment in the Kandalaksha Bay in the White Sea. Several tantulus larvae, developing males at different stages of metamorphosis, and early stages of parthenogenetic females were found attached to different sites of their hosts. Ultrastructure of the new species was studied with SEM. Microdajus tchesunovi sp. n. can be easily distinguished from other species of the genus Microdajus Greve by the presence of a pair of longitudinal dorsal lamellae at the anterior end of the cephalon. It is also characterized by the presence of an endopod seta on the sixth thoracopod and the absence of thoracopodal endites. A morphological comparison of species of the family Microdajidae is presented in tabular form.     

Reproductive strategies in a partially protandrous shrimp,Athanas kominatoensis (decapoda: alpheidae): Sex change as the best of a bad situation for subordinates

An alpheid shrimp,Athanas kominatoensis, inhabiting a Japanese purple sea urchin was shown to be a partially protandrous hermaphrodite. They settled mainly in summer and spent the first reproductive season as males. Smaller males changed into females the following spring, but larger ones remained males throughout their lives. Sex change was socially controlled, as has been known in some fishes. In contrast to the fishes, however, subordinates changed their sex as the best of a bad situation in this shrimp. Most larger individuals lived singly or in sexual pairs, not tolerating others of the same sex on a host. The larger a male was, the more likely he was to be found with a female. On the contrary, males smaller than 3 mm were tolerated by larger males to some extent and had chances to cohabit and copulate with larger females. This made it advantageous to be functional as a male at first. Though the secondary sex change from female to male is theoretically expected, it is hardly realized because of the short life span. Hermaphroditism in this shrimp can be explained by the size-advantage model as a special case.     

Recombinant shrimp (Litopenaeus vannamei) trypsinogen production in Pichia pastoris

Shrimp (Litopenaeus vannamei) trypsinogen has never been isolated from its natural source. To assess the production of L. vannamei trypsinogen, we engineered Pichia pastoris strains and evaluated two culture approaches with three induction culture media, to produce recombinant shrimp trypsinogen for the first time. The trypsinogen II cDNA was fused to the signal sequence of the Saccharomyces cerevisiae alpha mating factor, placed under the control of the P. pastoris AOX1 promoter, and integrated into the genome of P. pastoris host strain GS115. Using standard culture conditions for heterologous gene induction of a GS115 strain in shake flasks, recombinant shrimp trypsinogen was not detected by SDS‐PAGE and Western blot analysis. Growth kinetics revealed a toxicity of recombinant shrimp trypsinogen or its activated form over the cell host. Thus, a different culture approach was tested for the induction step, involving the use of high cell density cultures, a higher frequency of methanol feeding (every 12 h), and a buffered minimal methanol medium supplemented with sorbitol or alanine; alanine supplemented medium was found to be more efficient. After 96 h of induction with alanine supplemented medium, a 29‐kDa band from the cell‐free culture medium was clearly observed by SDS‐PAGE, and confirmed by Western blot to be shrimp trypsinogen, at a concentration of 14 μg/mL. Our results demonstrate that high density cell cultures with alanine in the induction medium allow the production of recombinant shrimp trypsinogen using the P. pastoris expression system, because of improved cell viability and greater stability of the recombinant trypsinogen. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

New Deep-sea Leptognathiid Tanaids (Crustacea, Tanaidacea) from the North-east Atlantic

Three new genera ( Araphura, Leptognathioides and Stenotanais ) and six new species of tanaid crustaceans from below 1000 m depth in the north-east Atlantic are described. Two of the new species belong to the genus Leptognathiella Hansen, 1913, which is redescribed and removed from synonymy with Leptognathia Sars, 1882 ( sensu Lang 1968). These species are relatively common in the tanaid material examined and have a widespread distribution in the area under study, i.e. the Rockall Trough, Porcupine Seabight and Bay of Biscay. All six species are found at depths between 2070 and 2892 m. A further nine species previously belonging to the genus Leptognathia are removed to the new genera or to Leptognathiella. New records of Leptognathioides polita (Hansen, 1913) comb.n. and Leptognathiella abyssi (Hansen, 1913) have been obtained.     

Responses of the infaunal peracarid Monokalliapseudes schubarti (Tanaidacea: Kalliapseudidae) to a bottom trawling disturbance and seasonality in an estuary of southern Brazil

The tanaid Monokalliapseudes schubarti is one of the dominant macrobenthic species in the shallow mudflats of southern Brazil. This species plays an important role in local trophic webs as a primary consumer and as a prey. This work investigated (1) the temporal variations in the population densities and structure of M. schubarti in the Patos Lagoon Estuary and (2) the potential impacts of shrimp trawling on the population densities, population structure and vertical stratification of the species in shallow areas of the estuary. The species exhibited significant temporal variability in its total densities and population structure, with a reproductive period observed during late summer and autumn, following an increase in salinity within the estuary. There were significant differences in M. schubarti densities, which appeared to be associated with variations in sediment texture and salinity. No well-defined pattern of trawling impact was identified; however, after high-impact trawling, decreases in the abundance of males and juveniles in the sediment superficial layer were recorded, and ovigerous females disappeared from the sampled area with relatively higher percentages of medium sand. Changes in the densities of different morphological categories observed after trawling were likely due to mortality, resuspension or rapid movement deeper into their tubes.