Fasciola hepatica: Histology of the testis in egg-producing adults of several laboratory-maintained isolates of flukes grown to maturity in cattle and sheep and in flukes from naturally infected hosts

A total of 8 calves approximately 6 months old and 22 lambs of similar age were infected with metacercariae of Fasciola hepatica of various laboratory-maintained isolates including: Cullompton (sensitive to triclabendazole) and Sligo, Oberon and Leon (reported as resistant to triclabendazole). Ten to 16 weeks after infection, flukes were harvested from these experimental animals and the histology of the testis tissue was examined in a representative sample of flukes from each population. Adult wild-type flukes were also collected from 5 chronically infected cattle and 7 chronically infected sheep identified at post-mortem inspection. The testis tissue of these flukes was compared with that of the various laboratory-maintained isolates. Whilst the testes of the wild-type, Oberon and Leon flukes displayed all the usual cell types associated with spermatogenesis in Fasciola hepatica (spermatogonia, spermatocytes, spermatids and mature sperm), the Cullompton flukes from both cattle and sheep showed arrested spermatogenesis, with no stages later than primary spermatocytes represented in the testis profiles. The presence of numerous eosinophilic apoptotic bodies and nuclear fragments suggested that meiotic division was anomalous and incomplete. In contrast to the wild-type flukes, no mature spermatozoa were present in the testes or amongst the shelled eggs in the uterus. A high proportion of the eggs collected from these flukes hatched to release normal-appearing miracidia after an appropriate incubation period, as indeed was the case with all isolates examined and the wild-type flukes. It is concluded that the eggs of Cullompton flukes are capable of development without fertilization, i.e. are parthenogenetic. The implications of this for rapid evolution of resistant clones following an anthelmintic selection event are discussed. Amongst the Sligo flukes examined, two subtypes were recognised, namely, those flukes with all stages of spermatogenesis and mature spermatozoa present in the testes (type 1), and those flukes with all stages of spermatogenesis up to spermatids present, but no maturing spermatozoa in the testes (type 2). Each sheep infected with the Sligo isolate had both type 1 (approximately 60%) and type 2 (approximately 40%) flukes present in the population. Spermatozoa were found amongst the eggs in the uterus in 64% of flukes and this did not necessarily reflect the occurrence of spermatozoa in the testis profiles of particular flukes, suggesting that cross-fertilization had occurred. The apparent disruption of meiosis in the spermatocytes of the Cullompton flukes is consistent with reports that Cullompton flukes are triploid (3n=30), whereas the Sligo and wild-type flukes are diploid (2n=20). In the Sligo flukes the populations are apparently genetically heterogenous, with a proportion of the flukes unable to produce fully formed spermatozoa perhaps because of a failure in spermiogenesis involving elongation of the nucleus during morphogenesis.     

Monoclonal antibodies reacting specifically with Francisella sp

Twenty two hybridoma strains producing monoclonal antibodies against Francisella tularensis ATCC 6223, var. tularensis, were characterized. In an enzyme-linked-immunosorbent-assay (ELISA) using formaldehyde fixed bacteria as antigens, neither cross-reactions with six different Brucella spp., with Yersinia enterocolitica 0:9 nor with two biotypes of Yersinia pseudotuberculosis could be detected. The antibodies gave comparable titres with the three strains of F.tularensis tested. ELISA binding studies indicated that fifteen of the antibodies bound with high affinities to their epitopes of the three Francisella strains, while the others each seemed to bind with low affinity to at least one of the antigens. Immunoblot analysis showed that six of the antibodies were directed to epitopes on the core moiety of the lipopolysaccharide molecule, while the other 16 antibodies bound to O side chain components.     

Development of a Simple Enzyme Immunoassay for the Determination of Ovine Luteinizing Hormone

The present study describes the development and validation of a simple sensitive and specific sandwich enzyme immunoassay (EIA) for the quantification of ovine luteinizing hormone (LH) in plasma. Microtitre plates were coated with the capture antibody 518b7 anti-bovine LH. A second peroxidase-labelled anti-ovine LH antibody was used as tracer. A simple 3-step procedure was used for the sample analysis; (1) incubation of standards and samples with the pre-coated antibody plates for 2 h at 37^°C; (2) incubation with the peroxidase-labelled antibody for 1 h at room temperature; and (3) colour development with TMB substrate. A linear dose–response curve was obtained in the range 0–10 ng/ml (r ² > 0.99). The detection limit was 0.05 ng/ml, and the intra-assay and inter-assay coefficients of variation were 7% and 11.7%, respectively. The theoretical stability of microplates and reagents was calculated, this being greater than one year. Low or undetectable cross-reactivities were recorded for follicle-stimulating hormone, bovine thyroid-stimulating hormone, equine chorionic gonadotrophin and a gonadotrophin-releasing hormone (GnRH) analogue. The EIA was biologically validated by the determination of plasma LH concentrations of nine Rasa Aragonesa ovariectomized and estradiol-implanted ewes after a double GnRH challenge. In conclusion, this enzyme immunoassay provides an efficient, simple and sensitive method for the routine analysis of ovine LH.     

Neoplastic angioendotheliomatosis in a dog: an angiotropic lymphoma

Neoplastic angioendotheliomatosis was diagnosed in a nine-year-old, intact male German Shorthaired Pointer exhibiting progressive neurological signs over a six-month period. At necropsy, there was multifocal asymmetric, hemorrhagic necrosis within the cerebral hemispheres, centrum semiovale, caudate nucleus, and internal capsule. Histologically, there was extensive intravascular proliferation of pleomorphic mononuclear cells within the brain and multiple parenchymatous organs. Transmission electron microscopy demonstrated the absence of intercellular junctions between neoplastic cells. These cells were not attached to the vascular lining endothelium; Weibel-Palade bodies and a basement membrane were lacking. By indirect immunofluorescence, positive cytoplasmic staining of intravascular neoplastic cells for IgG was demonstrated. Peroxidase-antiperoxidase technique for Factor VIII related antigen was negative. As in man, this rare neoplastic disorder appears to be a lymphoma, apparently of the B cell line.     

Structure and stability of soil aggregates

The formation and disintegration of macroaggregates into water-stable particles in a wide range of soil water contents—from the hygroscopic moisture to the capillary saturation moisture—were analyzed. It was found that the disintegration of macroaggregates into water-stable particles follows an exponential law. As the system becomes a three-phase system, neighboring particles in the macroaggregate are pressed together due to capillary pressure, and strong molecular bonds are formed. The disintegration curve of macroaggregates is an integral informative characteristic, which reflects the dynamics of changes in the strength properties of the macroaggregates.     

Haematological evaluation of ethanolic extract of Allium ascalonicum in male albino rats

The haematological effect of ethanolic extract of Allium ascalonicum was evaluated in male albino rats during a 21 day administration at the doses of 50, 100 and 200 mg/kg b.w, orally. Parameters evaluated include the serum lipids, red and white cell indices. The results showed that the extract administered decreased most of the parameters relating to red cell and increased most of those parameters relating to white cells. It also decreased the total cholesterol (TCH), high density lipoprotein cholesterol (HDL) and low density lipoprotein cholesterol (LDL) with no significant effect on the triglyceride levels.     

The effect of monthly anthelmintic treatment on the growth of young sheep rotationally grazed on hill pastures

Extract

Regular anthelmintic treatment is often recommended as a routine procedure in the management of lambs and hoggets over the summer, autumn, and winter months. There is, however, little published information available on the effect of such a procedure on the health and productivity of sheep. It is clear that the effect will vary widely under different conditions of climate, management, plane of nutrition, and level of parasitic infestation.     

Clinical and pathological studies on intoxication in horses from freshly cut Jimson weed (Datura stramonium)-contaminated maize intended for ensiling

Spontaneous intoxication in 34 horses after ingesting freshly harvested maize that was to be used for ensiling and heavily contaminated with young Datura stramonium plants, is described. The clinical status of all horses was monitored for 7 days, and included body (rectal) temperature, respiratory and heart rates, colour and moistness of visible mucosae, changes in pupil size, appetite, thirst, general behaviour, locomotion, sensory perceptions, urination and defaecation. The intoxication was accompanied by altered clinical status, namely mild hyperthermia, tachycardia, polypnoea, dyspnoea and shallow breathing, mydriasis, dry oral, rectal, vaginal and nasal mucosae, acute gastric dilatation and severe intestinal gas accumulation, anorexia to complete refusal of feed, decreased or absent thirst, absence of defaecation and urination. As a result of the treatment, the clinical parameters normalised between days 2 and 5. Necropsies and pathological studies were performed on two horses that died, revealing toxic liver dystrophy, cardiac lesions and substantial dystrophic and necrotic processes in the kidneys. The observed clinical signs, the pathomorphological changes and the applied therapy could be used in the diagnosis, differential diagnosis, prognosis and treatment of Jimson weed intoxication.     

Endolithic pedogenesis and rock varnish on massive crystalline rocks in East Antarctica

Desert varnish and endolithic organisms are two widespread phenomena that have been studied in detail separately; their interaction and their genetic relationships have virtually escaped the attention of researchers. Both phenomena are of indubitable interest for pedology: endolithic organisms as an agent of soil formation and rock varnish as a probable product of pedogenesis. It is argued that the system of endolithic organisms, their functioning products, and the rock has all the features inherent to soils: the rock layer subjected to the influence of external abiogenic factors and living organisms dwelling in the rock and synthesizing and decomposing organic substances. The action of biogenic and abiogenic agents leads to the in situ transformation of the rock with the accumulation and removal of the products of this transformation and with the development of vertical heterogeneity in the form of microhorizons composing the soil microprofile. Instrumental measurements indicate that the carbon content in the endolithic horizons developed by biota in granitoid rocks of the Larsemann Hills oasis varies from 0.2 to 3.3%, the nitrogen content in these horizons varies from 0.02 to 0.47%, and the radiocarbon age of their organic matter reaches 480 ± 25 yrs. The products of the pedogenesis are represented by fine earth materials and by abundant and often multilayered films and coatings on the rock surface and on the lower sides of the desquamation (spalling) plates. Scanning electron microscopy with X-ray microprobe analysis indicates that the major elements composing these films are O, C, Si, Al, Fe, Ca, Mg, and S. It is shown that the films of the rock varnish and the organomineral films in the fissured zone of the rock under the plate with endolithic communities have certain similarity in their morphology and composition: the films of the rock varnish also contain biota (dead cells or cells in the dormant state), and their botryoidal structure is similar to the structure of the biofilms inside the endolithic system. In both types of films, amorphous aluminum and silicon compounds are present, and the accumulation of Fe, Ca, Mg, S, Cl, and some other elements takes place. It is argued that some varieties of rock varnish are the products of endolithic pedogenesis; in essence, they represent the horizons of micropaleosols exposed to the surface in the course of spalling and then transformed by the external environmental agents.