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• W2014656241 abstract "The occurrence of the gregarine Urospora neapolitana in the spatangoid echinoid Echinocardium cordatum was followed monthly over a 1 yr period. Infesting stages (sporozoites) were seen only in the digestive cells of the hosts' gastric caecum while growing stages (trophozoites) only occurred in the hosts' body cavity. Sporozoites showed no variation in abundance over the investigated period. The number of trophozoites, however, clearly varied with a minimum in summer and early autumn. Trophozoite variation appears to be related to the gonadal cycle of the host. Up to 5 species of urospond gregarines may occur concurrently in the spatangoid echinoid Echinocardium cordaturn Pennant, l??? fro111 North Sea coasts (Coulon & Jangoux 1987). E. cordatum becomes infested by swallowing sediment containing ripe gametocysts. Sporozoites released from ripe gametocysts penetrate the digestive cells of the gastric caecum. Depending on the gregarine species, trophozoites reach either the host's hemal lacunae or the host's body cavity where growth, pairing of gamonts and encystment take place. Whether the species is intrahemal or intracoelomic, gametocysts eventually accun~ulate in the echinoid body cavity where they presumably remain until the death of the host (Coulon & Jangoux 1987). Urospora neapolitana Pixell-Goodrich, 1915 is the most abundant of the 5 gregarine species infesting Echinocardium cordatum. It follows a coelomic type of life-cycle with trophozoites and cysts exclusively located in the echinoid body cavity (Coulon & Jangoux 1987). Trophozoites are large worm-like cells from 120 to 320 pm long that swim actively in the coelomic fluid. Some of them are also found dead or necrotic (necrotic trophozoites are motionless rod-shaped cells, covered O Inter-Research/Printed in Germanv by host's coelomocytes; see Coulon & Jangoux 1988). Gametocysts of U. neapolitana lie in the host body cavity, mixed with cysts from other species and embedded in peculiar nodules made of degenerated coelomocytes and peritonea1 cells (the 'brown bodies'; De Ridder & Jangoux 1984). The present note reports results from a 1 yr survey (monthly sampling) of the number of active and necrotic trophozoites of Urospora neapolitana occurring in the body cavity of Echinocardium cordatum. The aim was to determine whether or not there is a seasonal pattern of infestation. Material and methods. From 25 to 30 Echinocardium cordaturn were collected monthly from February 1986 to February 1987 (except in December 1986) on a sandy beach at Wimereux (Pas de Calais, France). Individuals were maintained for a maximum of 6 d in a closed-circuit marine aquarium (13 C, 30 %O salinity) before examination. They were dissected and their coelomic fluid, digestive tube and gonads were collected. Active and necrotic (i.e. coelomocyte-covered) trophozoites of Urospora neapolitana were counted separately in the coelomic fluid using a dissecting microscope. Small pieces of gastric caecum and gonad were fixed in Bouin's fluid and prepared for light microscopy. Sections of caeca were examined to detect intracellular sporozoites. Sections of gonads allowed identification of hosts' sex and determination of whether or not their gonads were active (i.e. in the process of gametogenesis). Results and discussion. The sporozoites observed in the digestive cells of the gastric caecum could not be 72 Dis. aquat. Org. 12: 71-73, 1991 Feb Apr Jun Aug Oct Dec Feb Fig. 1 Mean number of active trophozoites of Urospora neapolitana in the coelorn of Echinocardium cordatum during a 1 yr cycle (February 1986 to February 1987). Vertical bars indicate 95% confidence limits. G-zones: hosts' gonads in the process of gametogenesis; R-zone: hosts' gonads at rest identified to species level. They presumably belonged to the 5 urosporids parasiting Echinocardium cordaturn, including Urospora neapolitana (see Coulon & Jangoux 1987). They were present all year round, with no obvious variation in abundance. This is consistent with the random mode of infestation of E. cordatum which swallows cysts mixed with sediment. Active trophozoites of Urospora neapolitana showed an obvious variation in number with time of year. The lowest values were obtained from June to October (with a minimum of 1.8 trophozoites per host in October) and the highest from November to May (with a maximum of 48.7 in April) (Fig.1). The difference between minimum and maximum values was statistically significant (Student's t-test, p < 0.05). Whatever the collecting period there was no significant difference in infestation level between host sexes. Considering the reproductive cycle of Echinocardiurn cordatum, it appears that high numbers of U. neapoljtana trophozoites" @default.
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• W2014656241 date "1992-01-01" @default.
• W2014656241 modified "2023-09-26" @default.
• W2014656241 title "Cyclic occurrence of gregarine trophozoites (Apicomplexa) in the burrowing echinoid Echinocardium cordatum (Echinodermata, Spatangoidea)" @default.
• W2014656241 doi "https://doi.org/10.3354/dao012071" @default.
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