A comparative study of the myxosporeans Myxidium rhodei Léger, 1905 and Myxidium pfeifferi Auerbach, 1908 in roach, Rutilus rutilus L.

Abstract. The morphology and dimensions of Myxidium rhodei and M. pfeifferi were studied in roach originating from two different geographic locations (Greece and UK) using both scanning and light microscopy. The measurements and morphology of both mature spores and immature stages (trophozoites and spores) were studied and compared. No differences were observed in the morphology of mature or immature spores of both species when examined under light and SEM. Furthermore, no differences were found in the dimensions of the mature spores of both species in all fish. However, immature spores of both species were found to be smaller but wider than mature ones in all organs and in both habitats. Size differences between the two species were only seen in immature spores, M. rhodei immature spores being always larger than those of M. pfeifferi. When comparing the dimensions of the spores between the two habitats, these were larger and wider in the Greek fish than those in the British fish. The information in this study suggests that, in roach, M. pfeifferi is undistinguishable from M. rhodei and that similar studies should be carried out on the tench, Tinca tinca L., the type host of M. pfeifferi.     

DESORPTION OF PHOSPHATE FROM SOILS USING ANION EXCHANGE RESINS

After 100h reaction with Cl-resin and 300h reaction with HCO₃-resin (approaching equilibrium), the concentration of anions complementary to phosphate was the critical variable affecting the transfer of P from soil to resin. Solution concentrations of H₃0⁺, Ca²⁺ and phosphate indicated that desorption of P by OH^-, and dissolution of Ca phosphates, controlled P release from soils. P extracted by HCO₃-resin was much greater than by Cl-resin from an acid soil, due to lower total anion and higher desorbing anion concentrations, but there was little difference between the two resins with a calcareous soil. HCO₃-resin extracted a constant proportion of isotopically-exchangeable P from different soils whereas Cl-resin did not. Anion exchange resins provide a convenient means for producing P desorption curves for soils.     

Malassezia dermatitis in the dog: a retrospective histopathological and immunopathological study of 86 cases (1990–95)

A retrospective histopathological and immunopathological study was conducted on 86 dogs with Malassezia dermatitis. West Highland White terriers, English Setters, Shih Tzus, Basset Hounds, American Cocker Spaniels, spayed females, and castrated males were found to be at increased risk. The histopathological reaction pattern of lymphocytic superficial perivascular to interstitial dermatitis with parakeratotic hyperkeratosis, irregular epidermal hyperplasia, diffuse intercellular oedema and lymphocytic exocytosis was found to be consistent with a diagnosis of Malassezia dermatitis whether yeast were histologically visible (73.3% of the cases) or not (26.7%). Immunopathological studies revealed that 60– > 90% of the inflammatory cells within the epidermis, and 25–75% of those within the dermis were CD3+T lymphocytes, and that the only immunoglobulin-positive cells were dermal plasma cells.     

Light and electron microscope observations on extrasporogonic and sporogonic stages of a myxosporean parasite of the genus Sphaerospora Thelohan, 1892 from Atlantic salmon, Salmo solar L., in Scotland

Abstract. Juvenile Atlantic salmon from a number of freshwater hatcheries in Scotland were found to be infected by a myxosporean parasite of the genus Sphaerospora. Fish first became infected in June by extrasporogonic stages which could be found in the blood and kidney interstitium. These consisted of a primary cell containing one to over one hundred secondary cells. Some secondary cells contained one or two tertiary cells. Sporogony was disporous and occurred later in the kidney tubules. The development of both extrasporogonic and sporogonic stages was studied by light and transmission electron microscopy.     

The life history of Haplorchis pumilio (Looss, 1896) from cultured tilapias

Abstract. The metacercaria of Haplorchis pumilio (Looss, 1896) (Digenea: Hetero-phyidae) was found to occur commonly in intensively reared tilapias ( Tilapia, Sarotherodon ) in an East African fish farm. The life cycle on the farm was found to involve the gastropod Melanoides tuberculata (Müller) as the first intermediate host. The infection was experimentally transmitted to fish in fresh water from naturally infected molluscs. The salinity of the water on the farm varied with season from 0 to 3%₀, but cercariae were shown to remain infective up to 10%₀ although longevity was reduced at 7.5%₀. Piscivorous predators, Ardea cinerea L., Phalocrocorax sp. and Varanus sp., which were resident or regular visitors to the farm were heavily infected with the parasite. Mice, hamsters and pigeons were found to be convenient laboratory hosts. H. pumilio shows a lack of specificity at the second intermediate and final host level as well as a wide geographic range and has been reported to infect man. Its potential as a possible cause of zoonoses, and control methods are discussed.     

The process of infection, migration, growth and development of Sanguinicola inermis Plehn, 1905 (Digenea: Sanguinicolidae) in carp, Cyprinus carpio L.

Abstract. Sanguinicoliasis is a serious disease of cultured carp causing high mortality in early fry. Experimental infections were used to study the pattern of penetration, and subsequent behaviour and development of the parasite. Maximum penetration of cercariae was achieved within 30 min, followed by a period of rapid development and growth marked by a doubling in length within the first 12 h. Subsequent growth was slower, during which major organ development took place, with gonadal maturity being completed between 60 and 90 days p.i. Penetration occurred mainly through the fins, particularly the caudal fin, and large numbers of worms remained in the skin where they continued to develop to maturity. A small proportion of the worms were found in the heart and gill vessels soon after infection. However, migration from the skin began at 60 days p.i. and greater numbers (57%) of the worms were found in heart and gill vessels at 90 days, coinciding with onset of egg production. Decline in worm numbers in the gill/heart region began after 120 days. Gill/heart worms differed in a number of features from skin worms, but egg production occurred simultaneously in both sites.     

Current practices in the chemotherapeutic control of sea lice infestations in aquaculture: a review

Abstract. This review surveys the available literature on the efficacy and ecotoxicology of chemotherapeutic agents for the control of sea lice (Copepoda: Caligidae) infestations in marine aquaculture. To date, treatment for the disease has relied almost exclusively on the use of the organophosphorus pesticides, trichlorfon and dichlorvos. While use of dichlorvos and trichlorfon appears to have little, if any, environmental impact, protracted use in some areas has led to reduced efficacy. Compounds proposed for sea lice control currently under field evaluation include azamethiphos (organophosphate), ivermectin (avermectin), pyrethrum (pyrethrin) and hydrogen peroxide. Although all of these compounds are effi cacious, at present published information on marine environmental toxicology is scarce and is limited to in vitro toxicity testing. Other compounds that have been considered for sea lice control include formalin, malathion (organophosphate), carbaryl (carbamate), diflubenzuron (insect growth regulator) and natural remedies (i.e. onions and garlic). In general, formaldehyde (aldehyde), malathion and natural compounds show either poor efficacy or unsuitable therapeutic margins. Although carbaryl and diflubenzuron are both efficacious and exhibit suitable therapeutic margins, available data suggests that the compounds, due to undesirable environmental toxicological characteristics, would be unsuitable for sea lice control.     

An experimental study into the possible protection of fry from Ichthyophthirius multifiliis (Fouquet) infections during mouthbrooding of Oreochromis mossambicus (Peters)

Abstract. The tilapine fish species belonging to the genus Oreochromis brood developing eggs and early fry in their buccal cavities. Though it is obvious that mouth brooding facilitates a physical protection from environmental hazards by keeping fry in this confined environment, it is still not clear whether mouth brooding provides any other type of protection to the early fry against pathogens. Investigations were made to study the possibility of protection of early fry of O. mossambicus against infections of the ciliate parasite Ichthyophthirius multifiliis during mouth brooding. Adult females were effectively immunized against I. multifiliis. Brooding immune females were then challenged with controlled infections of I. multifiliis tomites and the survival of the fry compared to those of challenged non-immune brooding females. The study demonstrated that there was some protection from the infection conferred to fry during mouthbrooding.     

The Impact of Migration on Social Capital: Do Migrants Take Their Bowling Balls with Them?

Questions surrounding the impact of population migration on social capital is the focus of this study. Putnam observed that “for people as for plants, frequent repotting disrupts root systems. It takes time for a mobile individual to put down new roots.” However, because of a trending decrease in mobility over time, Putnam rules out migration as an explanation for the long‐term decline in social capital that was the subject of his widely read 1995 book Bowling Alone: America's Declining Social Capital. This study undertakes an empirical examination of the impact of migration on county‐level social capital, which in tribute to Putnam one might view as an attempt to answer the question—do migrants take their bowling balls with them when they move? The potential for county‐level migration of population to impact social capital levels at particular locations in space arises from the conventional argument that social capital promotes trust and cooperation among agents. This trust increases socially efficient collective action but requires investment in relationships and commitment of scarce resources to build social capital. It seems plausible that migration of population might have a negative impact on the stock of social capital by interfering with trust and cooperation among agents. However, it is also possible that migrants may take their social capital with them to new places of residence. In other words, the propensity to join social and civic organizations might reflect inherent traits of individuals who are willing to make commitments of their resources to building social capital in any community where they reside.     

Effect of Prosthesis Number and Position on Rima Glottidis Area in Equine Laryngeal Specimens

Objective— To assess the effect of 1 or 2 laryngeal prosthetic sutures on rima glottidis areas in equine laryngeal specimens. Study Design— Experimental, randomized design. Animals— Cadaveric equine larynges (n=16). Methods— Larynges were collected from 10 horses; 2 sutures each were preplaced in the right and left sides of each larynx. A dorsal suture (DS) was placed through the caudal rim of the dorsal midline of the cricoid cartilage, under the cricopharyngeus muscle and through the proximal and rostral aspect of the muscular process. A lateral suture (LS) was placed 1.5 cm lateral to the DS and through the muscular process more distal and caudal to the 1st suture. Larynges were positioned in a customized stand and the rima glottidis photographed after each suture (LS or DS) or suture combination (CS) was tied in random sequence. An additional 6 larynxes were used to determine whether the tension applied to the sutures was repeatable. Sutures were preplaced in both the right and left side of each larynx as described above and each suture and CS was tied and released 3 times in each larynx. Photographs were taken of the rima glottidis after each suture or CS was tied generating 3 replicates for each suture configuration on each side of the 6 larynges. Results— Mean rima glottidis area was not different between DS and LS when tied alone (P=.85); however, mean area after CS (DS+LS) was greater than DS (P<.001) and LS (P<.001) alone. The coefficient of variation for the 6 suture patterns were low (1–7%) and the intraclass correlation coefficient estimates were very high (0.997–0.998) demonstrating excellent repeatability between replicates for each of the 3 suture configurations. Conclusion— Our results suggest that laryngoplasty using 2 prostheses; 1 placed dorsally in the cricoid and through the rostral and proximal muscular process and 1 placed 1.5 cm lateral to the 1st and more caudal and distal in the muscular process results in a greater cross sectional area of the rima glottidis than either suture used alone. Clinical Relevance— Seemingly prosthetic sutures contribute independently to each other in determining the contour of the rima glottidis. Use of 2 prosthetic sutures improves crosssectional area of the rima glottidis compared with each suture alone and may improve surgical outcome in laryngoplasty.