D.Sc. / A new species of the family Diplozoidae is described from 'the Vaaldam, Transvaal, South Africa. This species Paradiplozoon kimberleyensis n. sp., was initially found on the gills of the large mouth yellow fish Barbus kimberleyensis Gilchrist and Thompson, 1913 and later also on the.gills of the small mouth yellow fish Barbus aeneus (Burchell, 1822). Parasites collected from these fishes were studied with the aid of whole mounts, serial paraffin and methyl acrylate sections and the electron microscope. P. kimberleyensis n. sp. differs from the other African diplozoons with respect to the position of the productive system relative to the region of fusion, the lobular 'structure of the testis and the absence of the egg filament. Reconstructions of the reproductive system and prohaptoral region were used in describing the relevant structures. From these, it was clear that the vas deferens of one individual is fused to the common vitelline duct of the partner in copulation. Furthermore, the relations of the different parts of the reproductive system with respect to each other, could clearly be demonstrated. The physiological reproductive processes (i.e. oogenesis, spermatogenesis and vitellogenesis) of P. kimberleyensis n. sp. follow the basic pattern of other monogenean parasites. The various components of the reproductive system were discussed and compared with those of other diplozoons. Finally, the biological significance of the fusion of two separate individuals into a functional unit and the possible ways in which this phenomenon was accomplished were discussed.

M.Sc. / Two yellowfish species, namely Labeobarbus aeneus and Labeobarbus kimberlyensis were collected in the Vaal Dam and Vaal River Barrage over two years. The macroscopic characteristics, such as dimension and weight were recorded prior to dissecting out the gills. The gills were examined using a stereomicroscope for Paradiplozoon sp., the number of parasites was recorded and they were flat-fixed and stored in 10% Neutral Buffered Formalin. Statistical analysis of host yellowfish dimension and weight, and Paradiplozoon sp. occurrence was performed using Statistical Processing Software Suite v.15.00. The seasonal variation in size and shape of adult life-stage Paradiplozoon sp. attachment clamp sclerites was investigated using the geometric morphometric software Morphologika2 v. 2.5. Water quality variables at the Vaal Dam and Vaal River Barrage were analyzed using RAU Water v.2 software to produce a final Aquatic Toxicity Index Solway aggregate score. Diporpa, juvenile and adult stages of Paradiplozoon sp. were collected from yellowfish in the Vaal Dam, and oncomiracidia were allowed to hatch from eggs that were maintained in vitro. Details of life-stages were examined and measured using light microscopy, epi-fluorescence microscopy, confocal laser scanning microscopy, and scanning electron microscopy. The Solway aggregate score indicated that the water quality score in the Vaal Dam was better than the Vaal River Barrage. The water quality score was the poorest at both sites in the summer and best during the winter. Turbidity was identified to be the poorest water quality variable. No Paradiplozoon specimens were recovered from the gills of fish from 2005 to 2007 in the Vaal River Barrage. The numbers of Paradiplozoon sp. on yellowfish in the Vaal Dam were the greatest in winter at 67% prevalence, when the water quality score was the best during the study. In contrast to the elevated diplozoid numbers in rivers of poorer water quality in Europe, a low number of Paradiplozoon sp. were collected in spring when the water quality was poorer. This may be attributed to the difference in the type of aquatic pollutant in the Vaal River and European rivers. Yellowfish were longest and heaviest during spring, followed by autumn, summer and winter. It was not possible to statistically prove whether the presence of Paradiplozoon sp. negatively influences the size and weight of yellowfish. The increase in weight is suggested to be as a result of increased fat reserves, prior to spawning in spring.

Monogeneans from the family Diplozoidae (subclass Heteronchoinea) are bloodfeeding ectoparasites inhabiting gills of common carp. Digestion of blood in diplozoids is an intracellular process taking place in gut cells within lysosomal cycle in the presence of parasite's peptidases. However, information about the blood digestion comes only from ultrastructural and histochemical analyses. Therefore, I have focused in this work on biochemical and molecular characteristics of bioactive molecules which may participate in blood processing by E. nipponicum adults, especially cysteine peptidases of cathepsin L- and B- types, aspartic peptidases of cathepsin D-type, and Kunitz-type inhibitors of serine peptidases. In homogenates and excretory/secretory (E/S) products of E. nipponicum adults, an activity of cysteine peptidases of cathepsins L-type dominated, followed by an activity of cathepsin D-like aspartic peptidases and a minor cathepsin B-like activity. Inhibitors of the abovementioned peptidase types completely blocked hemoglobinolytic activity in the samples. In the transcriptome of E. nipponicum adults, ten cathepsin L-coding transcripts were found and only one cathepsin B-coding transcript. Primary structures of the encoded enzymes were bioinformatically and phylogenetically compared. Two abundant...

For the successful food intake by organisms that feed on blood is essentials presence of antihaemostatic molecules such as vasodilators, anticoagulant molecules and apyrases., Although members of family Diplozoidae (Heteronchoinea) are blood-feeding parasites on the gills of the fish, these molecules, that could disrupt host hemostasis, have not yet been identified. Thus, the aim of this study was to find molecules with potential anticoagulant activity in homogenates of whole worm bodies and excretory/secretory products of the members of family Diplozoidae. Furthermore perform bioinformatics analysis of sequences obtained from transcriptom project of Eudiplozoon nipponicum (Heteronchoinea: Diplozoidae) and selected proteins (protein domain) then expressed in a recombinant form. We tested inhibitory activity in excretory-secretory products and homogenates of members family Diplozoidae towards coagulation factors IIa and Xa and their specific fluorogenic with 4 negative and 1 positive results. From the results of two transcriptome analysis we discovered three protein families of potential anticoagulants - annexins, serpins and Kunitz-domain proteins. For further analyses we focused on the Kunitz protein family. These proteins contain one or more structurally related active domains which are able to...