Three wild populations of Clarias gariepinus from Esaodo (River Osun), Owena (River Owena), and Agbabu (River Oluwa), and three farmed populations, viz: Akure, Ilesa and Ado-Ekiti, in Southwest Nigeria, were analysed for their genetic differences using Random amplified polymorphic DNA (RAPD) analysis. Live specimens comprising 40 individuals (680 ± 3.28 g) from each location were collected and kept in six concrete tanks (2x1x1m). Altogether 435 reproducible bands were obtained from six populations for the nine RAPD primers used. The Analysis of Molecular Variance (AMOVA) indicated that the sampled populations are significantly different from each other, and that 99% of the total variation resided within the population. The percentage of genetic identity (GI) of RAPD-PCR profile among six populations ranged from 74.6% to 83.5%, while Genetic distance of the six populations based on RAPD-PCR profile ranged from 0.180 to 0.293. Estimates of genetic variation in wild and cultured populations of C. gariepinus were made, and total and mean number of segregating fragments were 71 (89.9%), 34.5 and 59 (74.7%), 35.4, respectively. Total gene diversity within wild and cultured populations (Ht) was 0.3419 and 0.3010, respectively. The study established that there is genetic variability in both wild and cultured C. gariepinus. RAPD showed that samples within the wild and cultured populations under study were closer to each other than between the two habitats. With reference to total gene diversity values and total number of segregating fragments, the wild population was considerably more diverse than the cultured population.

Morphological aberrations of the pectoral fins in nine mating combinations involving Clarias gariepinus (Burchell, 1822), Heterobranchus longifilis (Valenciennes, 1840) and their hybrids were investigated to determine the level and genetic basis of occurrence. The highest mean percentage survival in a Clarias× Clarias group was 75%, whereas the least mean percentage survival was 2% in the same group. The least mean percentage survival (40.3%) in the remaining three groups occurred in the cross of female hybrid (right pectoral fin absent) × male C. gariepinus (right pectoral fin absent). A maximum of nine types of aberrations was observed in the four mating groups – double dorsal fin, curved posterior dorsal fin, spineless right pectoral fin, right pectoral fin absent, left pectoral fin absent, rudimentary pectoral fin, both pectoral fins absent, double anal fin and curved anterior dorsal fin. These nine aberration types were recorded in the Clarias× Clarias group, with a total frequency ranging from 7.14% to 75.00%. The least number of aberrations was observed in the hybrid ×Clarias group (double dorsal fin and both pectoral fins absent) with a frequency range of 1.47–5.55%. No aberration was observed in two crosses involving female hybrid (right or left pectoral fin absent) × female C. gariepinus (normal). The level of aberrations in some of these crosses indicates the involvement of genotype rather than the influence of environment.

RésuméL'évolution de l'infection provoquée par le Trypanosome congolense chez des rates gravides sem ble très différente de celle constatée dans le cas de rates non-gravides.La moyenne des différences des charges de trypanosome (par millimètre cube de sang en circulation) entre les colonies de para sites présentes chez les rates gravides et non-gravides contaminées est statistiquement élevée.Les variations du nombre de globules blancs et de globules rouges traduisent les augmentations et les diminutions qui se produisent en réaction au besoin physiologique changeant de l'hôte et des cellules de trypanosome elles-m êm es.Il ressort du niveau élevé de Bun obtenu lors des tests biochimiques du sérum des rates gravides parasitées que les para sites sont probablement moins sensibles à l'action uréique.Les rates gravides atteintes du Trypanosome congolense ont montré qu'elles possédaient une quantité réduite de protéine sérique, de sodium et de calcium ainsi qu'une concentration assez normale de potassium.Les tests biochimiques du sérum montrent aussi qu'un état d'hypoglycémie et d'hypercholestérolémie subsiste chez les rates parasitées, gravides et non-gravides.Ces résultats confirment l'existence de troubles physiologiques dans le sang de l'hôte parasite. Ils suggèrent également que la Les changem ents pathologiques observés dans les globules seuls ou accom pagnés de m odifications m étaboliques du sérum détectées chez les hôtes qui ont été exposés au trypanosom e sont concom itants de l'apparition des sym ptôm es cliniques. L es im plications de l'état gravide ou de la régulation horm onale de l'hôte pendant la trypanosom iase sont décrites dans le docum ent. SummaryThe course of Trypanosom a congolense infection in pregnant rats appears to be very different from that of non-pregnant infections.The m ean of the differences in trypanosom e burdens (per cubic m illim eter of circulating blood) betw een the parasite popu lations present in the pregnant and non-pregnant infected rats is statistically signifiant.The changes reported in W B C and R B C counts strongly reflect increases and decreases in response to the changing physio logical requirem ent of the host and the trypanosom e cells them selves.The higher level of Bun obtained from the serum biochem ical tests of pregnant infections indicates that the parasites are probably less susceptible to U rea action.The pregnant rats infected w ith Trypanosom a congolense show ed reduced am ount of total serum protein, sodium , calcium , and a som ew hat norm al potassium concentration.The serum biochem ical tests further indicate that conditions of hypoglycem ia and hypercholesterolem ia persisted only in the pregnant and non-pregnant infected rats.These results confirm the existence of physiological distur bances in the infected host's blood The results also suggest that the slight deviation found in potassium ions and the unbalanced values of sodium and chloride electrolytes are interrelated to the disease virulent m echanism w hich probably involves inhibitions of ac...

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