Pathology of skin diseases in crocodiles

Objective To establish which skin diseases occur in crocodiles, particularly those on farms, to indicate the relative frequency of each particular disease and to provide information on pathogenesis, especially in regard to lesions with two or more pathogens present.
Design A gross and microscopic retrospective (period of 1989 to 1995) and current (1996 to 1997) examination of skin lesions in crocodiles in Queensland and the Northern Territory.
Result Skin lesions were obtained from crocodiles on nine farms, from a group of experimental animals and from one adult found dead in the wild. A total of 203 lesions from 180, mostly young, crocodiles was examined; 119 lesions were from retrospectively examined cases and 84 were recent. The relative frequencies of four presumed primary pathogens in lesions were Dermatophilus s p 28.1 %, fungi 14.8%, poxvirus 3.4% and probable Mycobacterium s p 2.5%. In addition, other bacteria of unknown significance were present in many lesions, and there was one case of presumed Paratrichosoma crocodilus infection. In 32.5% of lesions, multiple pathogens were identified.
Conclusion Dermatophilosis is the most common and probably the most important skin disease of crocodiles in Australia, but it is frequently complicated by concurrent infection with fungi or other microorganisms.     

Dose-response effects of inactivated Newcastle disease vaccines: influence of serologic assay, time after vaccination, and type of chickens

Knowledge of the dose-response relation of inactivated vaccines and of the factors that influence this relation is essential for the evaluation of existing vaccine potency assays and the development of new potency assays that are based on the antigen content of the inactivated vaccines. We quantified the relation between vaccine dose, serologic response, and clinical protection after vaccination for three different inactivated Newcastle disease (ND) vaccines. Qualitatively, similar dose-response curves were obtained for the three vaccines when either the serologic response or the clinical protection of specific-pathogen-free (SPF) chickens was plotted against the different vaccine doses applied. However, the vaccines differed quantitatively: doses of vaccines that induced similar antibody titers or clinical protection differed 2-8-fold. In contrast with the narrow range of antibody titers induced by a full vaccine dose, a very broad range of titers was obtained after dilution of the vaccines. At least 95% of the SPF chickens with detectable antibody in the serum were protected against a challenge with virulent Herts ND virus. The relation between the dosage of two different ND vaccines and the serum antibody titers remained markedly constant between 3 and 18 wk after vaccination. Vaccination of broilers instead of layers with a dilution series of inactivated ND vaccine resulted in significantly lower antibody levels and less clinical protection against virulent challenge. In conclusion, despite quantitative differences, we found comparable dose-response relations for the three inactivated ND vaccines studied.     

Management of the yellow beet cyst nematode with crop rotation,soil fumigation and granular nematicides

A trail field was managed for six years to test effects of short crop rotations, soil fumigation and granular nematicides on the population dynamics of the yellow beet cyst nematode (Heterodera trifolii f. sp.beta) and sugar-beet yields.In the two-year rotation, the cyst nematode population before planting varied from about the tolerance level (5 eggs per millilitre of soil) to 25 eggs per millitlitre of soil, leading to losses of sugar yield. Soil fumigation with metam-sodium effectively reduced the nematode density before planting, resulting in a 15 and 25% increase in sugar yield in the first two crops, respectively, but was insufficient to protect the third sugar-beet crop from yield-reducing nematode attack. This was attributed to the wet soil at the time of application and accelerated disappearence of the chemical in the soil through biological adaptation to repeated fumigation. Oxamyl or aldicarb granular nematicides applied as a side-dressing to the rows had insufficient effect to protect the sugar-beet from yield-reducing nematode attack. An overall treatment with aldicarb rotavated into the soil, alone and in addition to soil fumigation, increased sugar yield significantly. However in the two-year rotation, yield of the third sugar-beet crop treated with soil fumigation and granular nematicide was still lower than that of the untreated second crop in the three-year rotation.In the three-year rotation, thecyst nematode population before sugar-beet varied from hardly detectable to about the tolerance level. Here sugar-beet could be protected from yield-reducing nematode attack by soil fumigation or an overall treatment with granular nematicide. In the threeyear rotation with soil fumigation an increase ofRhizoctonia crown rot was observed in the second sugar-beet crop.Samenvatting Om de effecten na te gaan van korte rotaties, grondontsmetting en nematicide granulaten op het populatieverloop van de gele bietcystenematode (Heterodera trifolii f.sp.beta) en de opbrengsten van suikerbieten werd gedurende zes jaren een proef uitgevoerd op een natuurlijk besmet perceel van de proefboerderij Vredepeel.In de tweejarige rotatie variëerde de cystenematodepopulatie vóór het bietegewas boven de schadedrempel, wat resulteerde in verlaging van de suikeropbrengst. Grondontsmetting met metam-natrium veroorzaakte een effective vermindering van de dichtheid van de nematoden vóór de bieten en een verhoging van de suikeropbrengst van respectievelijk 15 en 25% bij de eerste twee gewassen, maar was onvoldeende om het derde bietegewas te beschermen tegen een opbrengst verminderende aantasting door nematoden. Dit was een gevolg van natte bodemomstandigheden bij het injecteren en het versneld verdwijenen van het middel door biologische adaptatie van de grond na herhaalde ontsmetting. Nematicide granulaten (oxamyl of aldicarb) naast de rij toegepast hadden onvoldoende effect om de bieten te beschermen tegen een opbrengstverminderende aantasting door nematoden. Een volvelds toepassing van in de grond gefreesde aldicarb alleen en toegevoegd na grondontsmetting verhoodge de suikeropbrengst beduidend. De opbrengst van het derde suikerbietegewas in de tweejarige rotatie was echter na toepassing van grondontsmetting en nematicide granulaten nog beduidend lager dan die van het onbehandelde tweede suikerbietegewas in de driejarige rotatie.In de driejarige rotatie variëerde de cystenematodepopulatie vóór het bietegewas van nauwelijks aantoonbaar tot nabij de tolerantiegrens. Hier kon het suikerbietegewas worden beschermd tegen een eventueel opbrengst verminderende nematodenaantasting door grondontsmetting of volveldstoepassing van nematicide granulaten.     

Root lesion nematode,Pratylenchus penetrans,in ‘Fire King’ lilies: attack and control with aldicarb

In field trials on fumigated sandy soil planted with stock of Fire King lilies lightly infested withPratylenchus penetrans, nematode control with aldicarb did not influence growth and yield of the lilies in the first growing season, perhaps because of the low initial number of nematodes. In the second season, however, a clear relation appeared between yield and nematode control by aldicarb.In such a biennial crop, yields after aldicarb treatment at planting were almost as good as after treatment in both years, 3 kg aldicarb a.i./ha (1.6 mmol.m^–2) being optimum.Samenvatting Bij de bestrijding van wortellesieaaltjes moet niet alleen rekening worden gehouden met de in de grond aanwezige aaltjes maar ook met die in de wortels van het plantgoed. Aan de wortels van het plantgoed is de aanwezigheid van deze aaltjes niet altijd duidelijk te zien. In als goed gekwalificeerd plantmateriaal van de leliecultivar Fire King werden gemiddeld 15Pratylenchus penetrans per bol gevonden en in slecht plantgoed 9.De aaltjes in de grond kunnen effectief worden bestreden door toepassing van grondontsmetting met een aaltjesdodend middel. In een tweejarige teelt van licht besmet plantmateriaal is dit echter onvoldoende om schade te voorkomen. Dit bleek uit een proef met Fire King in vooraf ontsmette zandgrond op de proeftuin Ens. In het tweede jaar was de groei van de lelies na toepassing van aldicarb ongeveer drie maal beter dan zonder dit middel. In de wortels van de onbehandelde lelies werden ongeveer twintig keer zoveel wortellesieaaltjes gevonden als in die van de behandelde planten.Om dit tweedejaarseffect nader te analyseren en de toepassing van aldicarb beter te preciseren werd het onderzoek op de proeftuin in 1975 en 1976 voortgezet, waarbij vooral aandacht werd besteed aan de dosering en de toedieningswijze van aldicarb in de vorm van Temik 10 G.Uit het pouplatieverloop van de wortellesieaaltjes gedurende de tweejarige teelt (Fig. 3) kan worden afgeleid dat pas merkbare schade optreedt bij meer dan 300P. penetrans per 10 g wortels en meer dan 20P. penetrans per 100 ml grond in mei, wanneer de ontwikkeling van de stengelwortels plaats vindt. De gevonden besmettingen blijven in het eerste jaar in alle objekten beneden deze schadegrens en komen in het tweede jaar daarboven in de objekten waar minder dan 3 kg aldicarb a.i./ha (1,6 mmol.m^–2) is toegediend in het eerste jaar. Dit is in overeenstemming met de opbrengstresultaten (Tabel 2).Uit het verband tussen de toegediende hoeveelheid aldicarb en de relatieve opbrengst blijkt eveneens dat een hogere dosering dan 1,6 mmol.m^–2 nog slechts weinig effectiever is en mogelijk zelfs groeiremmend kan werken. Het maakt daarbij weinig verschil of de toediening plaats vindt bij het planten in de vore of kort voor de opkomst van de lelies in de rug (Tabel 1). Uit praktische overwegingen moet de voorkeur worden gegeven aan de toediening in de plantvoor.De toediening van aldicarb in beide jaren had slechts een geringe produktieverhogend effect boven toediening uitsluitend in het eerste jaar (Tabel 2). Blijkbaar is de effectiviteit van dit nematicide veel groter tegen de lichte aanvangsbesmetting met aaltjes in de wortels van het plantgoed dan wanneer het in de rug wordt toegediend aan de veel hogere, verspreide besmetting aan het begin van het tweede jaar.Wat betreft de bewortelingskwaliteit van de bollen valt het op (Tabel 3) dat ook hogere doseringen dan 1,6 mmol.m^–2 nog verbetering geven en dat toediening in beide jaren een betere bewortelingskwaliteit geeft dan wanneer alleen in het eerste jaar aldicarb wordt toegediend. Het nematicide aldicarb heeft slechts een werkingsduur van 1 à 2 maanden, zodat de aaltjes zich later in het seizoen weer sterk kunnen vermeerderen waardoor de kwaliteit van de wortels snel kan teruglopen. Om een betere bewortelingskwaliteit te bereiken wordt dan ook een veel effectievere bestrijding van de wortellesieaaltjes gevraagd dan voor het veiligstellen van de groei en de opbrengst van lelies.Aangezien de bolwortels van ondergeschikte betekenis zijn voor de groei en de opbrengst van deze lelies lijkt het niet verantwoord hogere doseringen dan 1,6 mmol.m^–2 toe te passen.     

Discovery and characterization of a molecular marker for <Emphasis Type="Italic">Sclerotinia minor</Emphasis> (Jagger) resistance in peanut

The production of cultivated peanut, an important agronomic crop throughout the United States and the world, is consistently threatened by various diseases and pests. Sclerotinia minor Jagger (S. minor), the causal agent of Sclerotinia blight, is a major threat to peanut production in the Southwestern US, Virginia and North Carolina. Although information on the variability of morphological traits associated with Sclerotinia blight resistance is plentiful, no molecular markers associated with resistance have been reported. The identification of markers would greatly assist peanut geneticists in selecting genotypes to be used in breeding programs. The main objective of this work was to use simple sequence repeat (SSR) primers previously reported for peanut to identify a molecular marker associated with resistance to S. minor. Out of 16 primer pairs used to examine peanut genomic DNA from 39 different genotypes, one pair produced bands at approximately 145 and 100 bp, consistent with either S. minor resistance or susceptibility, respectively. Cloning and sequencing of these bands revealed the region is well conserved among all genotypes tested with the exception of the length of the SSR region, which varies with disease resistance levels. This is the first report of a molecular marker associated with resistance to Sclerotinia blight in peanut. The identification of this marker and development of a PCR-based screening method will prove to be extremely useful to peanut breeders in screening germplasm collections and segregating populations as well as in pyramiding S. minor resistance with other desirable traits into superior peanut lines.     

Observations of fibropapillomatosis in green turtles (Chelonia mydas) in Indonesia

Objective To determine the prevalence and manifestations of fibropapillomatosis in green turtles in Indonesia, to identify any relationship between fibropapillomatosis and concurrent parasitic infection, to ascertain the effect of fibropapil-lomatosis on health, and to examine whether environment might have an effect on the prevalence of fibropapillomatosis.
Procedure 4407 green turtles ( Chelonia mydas ) and 401 hawksbill turtles ( Eretmochelys imbricata ) were examined. The occurrence of fibropapillomatosis was correlated with sex, maturity, curved carapace length, body weight/curved carapace length ratio, the number and distribution of tumours on the skin, parasite burdens, some haematological variables and the region of capture.
Results Fibropapillomatosis was seen only in green turtles, and the overall prevalence in these was 21.5%. This prevalence increased with the curved carapace length up to 85 cm. The average number of tumours per affected turtle was 5 SD 4.1 (range, 1 to 29), and was negatively correlated with the body weight/curved carapace length ratio (rs = -0.8; P = 0.001). The red blood cell count in turtles with fibropapilloma was lower than in non-fibropapilloma turtles captured and examined at the same time (P = 0.001). The prevalence of fibropapilloma in turtles captured near densely populated, industrial regions (26.3%) was greater than in turtles from sparsely populated areas (17.7%).
Conclusion Fibropapillomatosis in green sea turtles in Indonesia is of moderate occurrence; young mature turtles (curved carapace length = 85 cm) are most frequently affected. Fibropapilloma adversely affects health of turtles. Fluke infestation seems not to be a causal factor, but viral infection, perhaps with concurrent stress of environmental origin, seems likely.     

Een geval van noodrijpheid bij blauwmaanzaad

Summary Premature dying of seed poppies, of unknown cause, was observed in The Netherlands, in 1959, at the end of the vegetative growth period.In a spraying experiment with systox the untreated plants died prematurely and showed a 50% decrease in yield based mainly on the weight of harvested seed. This disorder may be due to sugar beet yellows virus or to aphid damage alone. One spray before flowering reduced the disease and increased the yield.The fungusPyrenophora calvescens (Fr.) Sacc., which also is supposed to cause a premature ripeness of seed poppies, was present to the same degree in both the untreated and the sprayed plots.     

Bovine anaplasmosis: susceptibility of seronegative cows from an infected herd to experimental infection with Anaplasma marginale

Adult cows from an Anaplasma marginale-infected herd that were negative to the A marginale rapid card agglutination (RCA) and complement fixation (CF) tests for 1 to 4 years developed acute anaplasmosis after inoculation with 0.5 ml of blood from an A marginale carrier cow. The test cattle were as susceptible as the control cattle of similar ages. Also, 2 cows that had seroconverted from RCA/CF-positive to RCA/CF-negative status naturally were fully susceptible to anaplasmosis when they were experimentally infected. Results of the study indicated that indigenous seronegative cattle in anaplasmosis-enzootic regions probably do not have acquired or natural immunity to A marginale infection.     

Inhibition of aflatoxin M1 production by bovine hepatocytes after intervention with oltipraz

It is well known that cattle ingesting aflatoxin B1 contaminated feed commodities excrete aflatoxin M1 into their milk. As aflatoxin M1 originates from hepatic metabolism, measures to prevent aflatoxin M1 formation need to be directed to either the immobilization of aflatoxin B1 in the gastrointestinal tract or the modification of hepatic metabolism of aflatoxin B1. Here we studied the influence of oltipraz and a second dithiolthione, (1,2) dithiolo (4,3-c)-1,2-dithiole-3,6 dithione (DDD) on bovine hepatic aflatoxin B1 biotransformation. Oltipraz inhibited aflatoxin B1 metabolism as no aflatoxin M1 and no aflatoxin B1-dihydrodiol, the second metabolite found in bovine hepatocytes, was formed. DDD did not significantly inhibit aflatoxin B1 metabolism. It could be demonstrated that the inhibition of aflatoxin B1 metabolism was due to the inhibition of several cytochrome P450 enzyme activities by oltipraz. In contrast, DDD inhibited only ethoxyresorufin O-deethylation activity. These findings suggest a high efficacy of oltipraz in inhibiting aflatoxin M1 contamination of milk from dairy cows exposed to aflatoxin B1 contaminated feeds.