Macroparasites of five species of ray (genus Raja) on the northwest coast of Spain.

A parasitological study of rays captured on the Atlantic continental shelf off the estuary Muros-Noia in NW Spain (42 degrees 35' to 42 degrees 41' N, 9 degrees 2' to 9 degrees 10' W; mean capture depth 11.6 +/- 4.1 m) was performed. A total of 128 rays were examined: 52 specimens of Raja microocellata, 60 of R. brachyura, 6 of R. montagui, 3 of R. undulata and 7 of an unidentified Raja species, known locally as 'fancheca'. A total of 23 macroparasite species were detected: 5 monogeneans (Acanthocotyle sp., Calicotyle kroyeri, Empruthotrema raiae, Merizocotyle undulata, Rajonchocotyle emarginata), 11 cestodes (Acanthobothrium sp., Crossobothrium sp., Echeneibothrium sp., Echinobothrium brachysoma, Grillotia erinaceus, Grillotia sp., Lecanicephalum sp., Nybelinia lingualis, Onchobothrium uncinatum, Phyllobothrium lactuca, Tritaphros retzii), 6 nematodes (Anisakis simplex, Hysterothylacium sp., Histodytes microocellatus, Piscicapillaria freemani, Proleptus sp., Pseudanisakis baylisi) and a copepod (Holobomolochus sp.). All parasite species were present in several ray species, except for Acanthocotyle sp. and G. erinaceus (detected only in R. brachyura), H. microocellatus (detected only in R. microocellata) and T. retzii (detected only in R. montagui). Three species (C. kroyeri, M. undulata, E. brachysoma) have not been reported previously from Spain. The host with the highest parasite species richness was R. brachyura (18 species), followed by R. microocellata (17) and the unidentified Raja species (14). The parasite with the highest prevalence in R. microocellata was M. undulata, followed by R. emarginata, Acanthobothrium sp. and Echeneibothrium sp. The species with the highest prevalence in R. brachyura was R. emarginata, followed by C. kroyeri and P. baylisi. Some differences in parasite prevalence were detected between sexes and among size classes in both R. brachyura and R. microocellata.

Blood protozoans in elasmobranchs of the family Rajidae from Galicia (NW Spain).

Blood smears from 132 skates Raja spp. captured on the continental shelf off Galicia (NW Spain) were examined for blood parasites. The skate species were Raja brachyura (n=60), R. microocellata (n=52) and a total of 20 specimens belonging to R. undulata, R. montagui and another 2 unidentified Raja species, all captured between March 1999 and March 2000. Two blood parasite species were found, Trypanosoma giganteum and Haemogregarina delagei. Of the 132 skates, 16% were infected only by T. giganteum, 17% only by H. delagei, and 5% by both T. giganteum and H. delagei. Both parasites showed highest prevalence in R. brachyura (22% T. giganteum only, 38% H. delagei only, 12% T. giganteum and H. delagei). Mean leucocyte percentages (n=132 fish) were lymphocytes (43%), eosinophils (35%), neutrophils (20%) and monocytes (2%); basophils were not found. As far as we are aware, this eosinophil percentage is the highest reported to date for elasmobranchs. We did not detect any statistically significant differences in leucocyte percentages between infected and uninfected fish, between male and female fish, among species or among weight groups.

Histodytes microocellatus gen. et sp. nov. (Dracunculoidea: Guyanemidae), a parasite of Raja microocellata on the European Atlantic coast (north-western Spain).

We describe a new genus, Histodytes, within the family Guyanemidae (Nematoda: Spirurida: Camallanina: Dracunculoidea). The type species, Histodytes microocellatus n. sp., is found in the gill, heart, kidney, spleen and gonad tissues of Raja microocellata from the continental shelf off the estuary of Muros y Noia (north-western Iberian Peninsula). Histodytes differs morphologically from the three other genera described to date in this family ( Guyanema, Travassosnema, Pseudodelphys) because the vulva is situated a long way back from the oesophageal-intestinal union, and the anterior uterine branch almost reaches to the level of this union. In addition, it can be distinguished from Guyanema and Travassosnema by the absence of caudal alae in the male, and from Travassosnema by the much greater length of the glandular oesophagus and the lack of an oesophageal appendix. Histodytes is the only guyanemid genus described to date from an elasmobranch and the first one to be found on the European Atlantic coast.

PCR detection of Tetramicra brevifilum (Microspora) infection in turbot (Scophthalmus maximus L.) musculature.

This study investigated the spatial distribution of Tetramicra brevifilum spores in the musculature of infected turbot Scophthalmus maximus, with the aim of identifying the most appropriate body locations for diagnostic assays. A PCR protocol optimized for the detection of T. brevifilum spores in turbot muscle is also described. In fish showing low- and moderate-intensity infection, the spatial distribution of spores was best fitted by a negative binomial distribution, indicating a clumped spatial pattern; the negative binomial coefficient k was lower for fish with low-intensity infection, indicating a more markedly clumped pattern in these fish. In fish with high-intensity infection, the spatial distribution of spores was best fitted by the Poisson distribution, indicating a random pattern. In both low- and moderate-intensity infection, spores were present at highest density in the musculature adjoining the dorsal fins. Samples for PCR were therefore obtained from this location. PCR amplification was of the small subunit ribosomal DNA (SSUrDNA), using a pair of species-specific primers that amplify the 1250 bp product. The PCR protocol developed showed better sensitivity than microscopical techniques (detection rate by microscopy 25%, versus 42% by PCR), suggesting that it may be useful for routine screening for Tetramicra brevifilum infection in cultured turbot.

Amino acids and memory consolidation in the cricket. II: Effect of injected amino acids and opioids on memory.

The effect of injections of selected amino acids on memory, given before a maze-learning, was investigated. Thirsty crickets (Pteronemobius sp.) were trained to turn only to one side of a symmetrical Y-shaped maze using reinforcements with water. The insects retained the learned task 24 hr later. N2 anoxia applied immediately after training produced retrograde amnesia. Injections of Ala, Arg, Gln or morphine prior to training blocked the amnesic action of anoxia, whereas those of Cys, Met, Pro, Orn, octopamine or naloxone did not. Naloxone blocked long-term memory formation, but not learning, whereas Pro and Orn blocked both. The antiamnesic effect of morphine and Arg, but not that of Ala, was blocked by naloxone. A hypothesis assigning a neuromodulatory role to some amino acids is put forward.