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.

Mangifera indica L. extract (Vimang) and mangiferin modulate mouse humoral immune responses.

The present study investigated the effects of orally administered Vimang (an aqueous extract of Mangifera indica) and mangiferin (the major polyphenol present in Vimang) on mouse antibody responses induced by inoculation with spores of microsporidian parasites. Inoculation induced specific antibody production with an exponential timecourse, peaking after about one month. Vimang significantly inhibited this antibody production from about three weeks post-inoculation, and most markedly by four weeks post-inoculation; by contrast, mangiferin had no significant effect. Determination of Ig isotypes showed that the IgM to IgG switch began about four weeks post-inoculation, with IgG2a predominating. Vimang significantly inhibited IgG production, but had no effect on IgM. Mangiferin did no affect either IgM or IgG2a, but significantly enhanced production of IgG1 and IgG2b. Neither Vimang nor mangiferin enhanced specific antibody secretion by splenic plasma cells from mice inoculated with microsporidian spores, whether administered in vivo before serum extraction or in vitro to the culture medium. Inoculation with spores induced splenomegaly, which was significantly reduced by Vimang and significantly enhanced by mangiferin. These results suggest that components of Mangifera indica extracts may be of potential value for modulating the humoral response in different immunopathological disorders.

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.