Influence of intercodon and base frequencies on codon usage in filarial parasites.

Base frequency, codon usage, and intercodon identity were analyzed in five filarial parasite species representing five Onchocercidae genera. Wucheria bancrofti, Brugia malayi, Onchocerca volvulus, Acanthocheilonema viteae, and Dirofilaria immitis gene sequences were downloaded from NCBI, and analysis was performed using locally designed computer programs and other freely available applications. A clear sequence bias was observed among the nematode species examined. At the nucleotide level, AT basepairs were present in gene sequences at higher frequencies than GC. In addition, codons ending in A or T were used proportionately more than those with G or C in the third-codon position. In addition, the amino acids used most often corresponded to codons ending in AT basepairs. Intercodon base proportion was biased in that A was found most often at N4, second only to T in certain specific cases. Since all of these sequence biases were observed in a relatively consistent fashion among all of the organisms studied, we conclude that sequence bias is a genetic characteristic, which is associated with multiple filarial genera.

Cyclocoelum microstomum and C. obscurum (Trematoda: Cyclocoelidae) from air sacs of waterfowl in Egypt: early life history, morphological and histological studies of adult.

Two species of genus Cyclocoelum are recorded from air sacs of waterfowls, collected from Egypt. Fully morphological and histological descriptions for the adult stage of C. microstomum from moorhen Gallinula chloropus are presented. Also egg and miracidium stages are described. The second species, C. obscurum collected from coat Fulca sp. also described. Some problematic status of the genus Cyclocoelum are discussed include evaluation of some morphological and histological criteria also the migration and location of worm within the birds.

Effects of lead, mercury and cadmium on the extramolluscan larval stages of Schistosoma mansoni (Sambon).

The effects of the heavy metal pollutants, lead, mercury and cadmium on the survival and behaviour of miracidia and cercariae of Schistosoma mansoni were examined. Concentration ranges of 100-900 microM lead chloride, 0.25-20 microM mercuric chloride and 0.25-9.0 microM cadmium chloride were tested. Inversely proportional relationships between metal concentration and survival were evident with all the metals. The LC50 of miracidia was 600 microM for lead, 1 microM for mercury and 2.5 for cadmium. The LC50 of cercariae was 600 microM for lead, 6 microM for mercury and 2.5 microM for cadmium. Movement and behavior of miracidia and cercariae were severely affected by exposure at the higher end of the concentrations of heavy metals tested. Infectivity of cercariae to mice was reduced by nearly half when cercariae were pre-exposed to lead, mercury or cadmium for five hours at the LC50 concentrations, compared with the infectivity of unexposed cercariae.

The effects of lead, cadmium, and mercury on the mortality and infectivity of Schistosoma mansoni cercariae.

The effects of lead, cadmium, and mercury chloride salts on survival and infectivity of Schistosoma mansoni cercariae were examined. The LC 50 for 5 hr exposure was approximately 500 microM for lead, 2.5 microM for cadmium, and 6 microM for mercury. These toxicity figures are significantly higher than the levels of these heavy metals reported to occur in the natural waters of Egypt where schistosome transmission occurs. Infectivity of cercariae surviving exposure to metals at the LC 50 was reduced to approximately one-half that of control mice infected with unexposed cercariae.

The efficacy of ivermectin in treating rabbits experimentally infected with Eimeria as indicated parasitologically and histologically.

Ivermectin (Ivomec) was used as coccidiocidal drug against Eimeria in experimentally infected rabbits as indicated parasitologically & histologically. Twenty Bosskat rabbits, were divided in to 5 groups, 3 groups were inoculated with 1000 sporulated oocysts and the other 2 groups were kept as negative controls with and without Ivermectin administration. Ivermectin (1:10) was injected subcutaneously in a dose of 0.5 ml in animals of groups 1,2 & 3. The treatment of group (1) was on the 4th day A.I. and on the 4th day and 7th day A.I.in group (2). The treated animals with one or two doses showed mild coccidiosis with very few number of oocysts deposition & rapid intestinal regeneration with degenerated Eimeria developmental stages, especially the asexual ones.

Morphological and anatomical studies on larval trematode of genus Brachylaima (Brachylaimidae) from the land snail, Monacha obstructa.

The metacercariae of genus Brachylaima were collected from the kidney of the land snail Monacha obstructa. About thirteen to fifteen metacercariae were collected from each snail. The metacercariae observed were elongated rather than oval. The gonads were no so developed inspite of the great similarity between this larval stage and the adults. No larval stages rather than the metacercariae were observed. The specimens were examined in fresh status and then stained with carmine and fast green as counter stain. The excretory system was developed to very great extent. This seems to be the first record of this larval stage in Egypt since 1899 when Looss collected the adult of B. aequans from Gerbillus aegyptiacus. The heavy infection of snails reflects the higher incidence of this parasite among land snails as intermediate host. Since, the life cycle of this parasite is not yet confirmed experimentally in Egypt, the species has not been identified.

The histopathological effect of metacercariae of the genus Brachylaima on the land snail, Monacha obstructa.

The histopathological changes in the kidney of the land snail Monacha obstructa and the histochemistry of the body wall of the parasite were studied. The histological pictures of the infected kidney showed extensive degree of degeneration in the renal tissue with multiple necrotic foci. Due to the mechanical and feeding effects of the parasite, the renal lamellae were disintegrated. Also, suckers increased the renal damage. In some levels of the kidney, the renal tissue was completely disappeared except the connective tissue of kidney capsule. Also, it was observed that there was a clear space between the parasites and renal tissue probably as a trial of evasion from the Host's reaction. The histochemical study on the metacercarial body wall revealed that it is consisting of three layers arranged as outer, middle and inner layers. Staining with Periodic Acid Schiff proved that the body wall is rich in mucopolysaccharide content. The idea that this parasite can be used as a biocontrol agent is also discussed.

Scanning electron microscope observations on Parapharyngodon bulbosus (Linstow, 1899) (Nematoda: Pharyngodonidae) from Egyptian Chalcides ocellatus.

The oxyurid nematode Parapharyngodon bulbosus was collected from the lizard Chalcides ocellatus from Egypt. Male and female worms were described by light and scanning electron microscopes. The specific characteristics of the worms were defined, including; mouth opening, cuticular surface of the body, genital cone and genital papillae in the male.

Ultrastructural study of the body surface and the flame cell of Oochoristica sp. (Cestoda: Anoplocephalidae).

Ultrastructural studies on the body surface of the adult tapeworm Oochoristica sp. revealed that all the strobilar surface including the scolex and the adhesive surfaces of the suckers are covered with long filamentous microtriches. Using scanning and transmission electron microscopes, the basic morphology of the microtriches was studied and found to be similar to those described in other cestodes but differs in having a relatively long basal regions. The flame cell was also described.

Studies on larval digenetic trematodes of xiphidiocercariae from some Egyptian fresh water snails.

Six xiphidiocercariae are described from seven Egyptian snails, includes Cleopatra bulimoides, Malanoides tuberculata, Lymnaea cailliaudi, Bulinus truncatus, Biomphlaria alexandrina and Lanistes carinatus collected from Giza (Abou Rawash) and Qualiobyia (Qualiuob). Details are presented on the morphology, behavior of the cercariae, as well as other larval stages within the snails, with discussion and comparison between the previously described cercariae.

Larval occurrence of Hydatigera taeniaeformis Batsch (1786) (Cestoda: Taeniidae) in the liver of wild rodents in Egypt.

Hydatigera taeniaeformis Batsch (1786) was found in the liver of six species of Egyptian wild rodents. Wanas et al., (1990) found the total incidence of this larval stage to be 20.0% among cestode infection. It was found in (40.9%) Rattus norvegicus; (33.3%) Gerbillus gerbillus; (26.8%) Rattus rattus; (25.0%) Mus musculus; (16.6%) Acomys cahirinus; and (7.2%) Arvicanthis niloticus. The cysts of Hydatigera taenioformis was always occupying the marginal surfaces of both right and left lobes and sometimes there was a double cyst contained two strobilae. The rostellar hooks used for identification. The strobilae obtained were in different stages of development. The rostellar hook system was complete and so the suckers but the segment showed no maturation. Morphological characters and role of rodents as intermediate host for such cestode are discussed.

Larval stages of digenetic trematodes of Pirenella conica from Deversoir Ismailia, Egypt.

Two cercariae are described from the prosobranch snail Pirenella conica collected from Deversoir marine-water, Ismailia, Egypt. One of the ercariae is prepleuro-lophoercous group, belonging to genus Stictodora, while the second is a Ephemera monostome cercaria. The latter is a new record for Pirenella conica snail in marine water from Ismailia. Details are present on the morphology and behavior of the cercariae and rediae, as well as of their development within the snail, with discussion and comparison of previously described cercariae. The incidence of single (pure) and simultaneous mixed (double) infection of snail with two larval trematodes were also determined.