Changes during a three-year period in the sensitivity to ergosterol biosynthesis inhibitors of Sphaerotheca fuliginea in the Netherlands

Isolates ofSphaerotheca fuliginea colleeted in 1981–1984 in cucumber giasshouses in the Netherlands were tested for their sensitivity to the ergosterol biosynthesis inhibitors (EBIs) fenarimol and imazalil.The data collected in the 1981 survey indicated that sensitivity to EBIs was lower than that of reference isolates. In the 1982 and 1983 surveys, sensitivity to EBIs continued to decrease. In 1984, data were collected until July; no significant difference in sensitivity with the 1983 level was apparent.Isolates collected in the district of Limburg, where EBIs were applied less frequently than in the district of Pijnacker, showed a significantly higher sensitivity to EBIs than isolates collected in Pijnacker.Besides differences in sensitivity to EBIs between years, differences within years were noticed. In 1983, the sensitivity to fenarimol and imazalil was significantly higher in the beginning of the growing season, before any fungicides were applied, than later in the growing season.Generally, changes in sensitivity to EBIs did not result in full failure of control. In most cases, a change to shorter spray intervals has been sufficient to compensate for the decrease in sensitivity and to achieve proper control by fenarimol and imazalil. The results once more emphasize the necessity of designing strategies to prevent resistance to EBIs.Samenvatting Uit komkommerkassen in Nederland werden gedurende de periode 1981–1984 isolaten vanSphaerotheca fuliginea verzameld. De gevoeligheid van deze isolaten voor fenarimol en imazalil, twee ergosterolbiosyntheseremmers (EBR's), werd getest. De gegevens verzameld in 1981 wijzen erop dat de gevoeligheid voor EBR's lager was dan die van referentie-isolaten. In 1982 en 1983 daalde de gevoeligheid voor EBR's nog verder. In 1984 werden gegevens verzameld tot en met juli. Er werd geen significant verschil in gevoeligheid waargenomen met het niveau van 1983.Isolaten verzameld in Limburg, waar EBR's minder vaak toegepast worden dan in Pijnacker, hadden een significant hogere gevoeligheid voor EBR's dan isolaten uit Pijnacker.Naast verschillen in gevoeligheid voor EBR's tussen jaren, werden ook verschillen binnen de jaren waargenomen. In het begin van het groeiseizoen in 1983, voordat fungiciden waren gebruikt, was de gevoeligheid voor fenarimol en imazalil hoger dan later in het groeiseizoen. In het algemeen hadden de veranderingen in gevoeligheid voor EBR's geen volledig falen van de bestrijding tot gevolg. In de meeste gevallen was een verkorting van de intervallen tussen de toepassingen van fenarimol en imazalil voldoende om te compenseren voor de verminderde gevoeligheid en om een goede bestrijding te verkrijgen. De resultaten benadrukken nogmaals de noodzaak om strategieën te ontwerpen die resistentie tegen EBR's voorkomen.     

Pregnancy Rates to Fixed Embryo Transfer of Vitrified IVP Bos indicus,Bos taurus or Bos indicus × Bos taurus Embryos

The pregnancy rates obtained after the transfer of cryopreserved in vitro‐produced (IVP) embryos are usually low and/or inconsistent. The objective of this study was to evaluate the pregnancy rates of Holstein, Gyr and Holstein × Gyr cattle after the transfer of vitrified IVP embryos produced with X‐sorted sperm. Seventy‐two Gyr and 703 Holstein females were subjected to ovum pickup (OPU) sessions, followed by in vitro embryo production using semen from sires of the same breeds. Embryos (1636 Holstein, 241 Gyr and 1515 Holstein × Gyr) were exposed to forskolin for 48 h prior to vitrification. The pregnancy rate achieved with Gyr dam and sire was 46.1%, which was similar (p = 0.11) to that of Holstein dam and Gyr sire (40.3%). Crossing Gyr dams with Holstein sires resulted in a pregnancy rate of 38.9% and did not differ (p = 0.58) from the pregnancy rate obtained with the cross between Holstein dams and Gyr sires. The rate obtained with Holstein dam and sire was 32.5%. The average pregnancy rate was 36.6%, and no difference was found in the proportion of female foetuses (88.8%, in average) among breeds (p > 0.05). In conclusion, transfer of cryopreserved X‐sorted embryos represents an interesting choice for dairy cattle. Despite the small differences between pregnancy rates, we highlight the efficiency of this strategy for all of the racial groups studied.     

An in situ single-pass perfusion model for assessing absorption across the intestinal mucosa of the brushtail possum

AIM: To develop an in situ animal model for assessing absorption of molecules across the intestinal mucosa of possums.

METHODS: A surgical preparation was used to perfuse known concentrations of reference compounds (fluorescein and luteinising hormone-releasing hormone; LHRH) through measured sections of selected regions (jejunum, caecum, proximal colon) of the intestinal tract of 19 possums, over a 2-h period. Plasma concentrations of the compounds, which were perfused either with or without co-administration of a permeation enhancer (sodium deoxycholic acid; SDA), were determined in the perfusion effluent, peripheral and in some instances in the pre-hepatic circulation by spectrofluorometry (fluorescein) or radio-immunoassay (LHRH). Pharmacokinetic parameters of both compounds in the possum were determined over a period of up to 4 h in a further 30 animals (fluorescein, n=6; LHRH n=24), from their plasma profiles following intravenous (I/V) administration of a bolus dose.

RESULTS: In animals perfused with 25 mg/ml fluorescein (Perfusion Experiment (PE) 1), the mean plasma concentration was 2.8 (SE 0.12) µg/ml in post-hepatic blood samples. When possums were perfused with 2.5 mg/ml fluorescein and 7 µg/ml LHRH (PE 2), mean plasma concentrations were 0.3 (SE 0.01) and 7.8 (SE 1.64) µg/ml fluorescein and 0.1 (SE 0.02) and 6.3 (SE 0.45) ng/ml LHRH, in the absence and presence of permeation enhancer, respectively. There was a poor correlation between pre-hepatic and post-hepatic concentrations.

CONCLUSIONS: The single-pass in situ perfusion technique provided a useful model for investigating basic information on the absorption of biocontrol agents across the intestinal tract of possums, but had limitations that must be recognised.     

In vitro enzymatic hydrolysis of protein and protein pattern change of soya and faba beans during germination

In addition to technological processes like heat treatment, germination can be an alternative process for the improvement of protein quality of legumes. This was demonstrated by enzymatic protein hydrolysis of flour of germinated faba and soya beans, using a pepsinpancreatin enzyme system. SDS-PAGE was used to study the changes in protein pattern of these legumes during germination. In addition, the effect of germination on the content of condensed tannins in flour from germinated faba beans and trypsin inhibitors in flour from germinated soya beans were studied. Germination for five days resulted in a maximum increase in enzymatic protein hydrolysis by 21.3% in flour from faba beans and by 25.7% in flour from soya beans after 12 hours of germination. Protein patterns, obtained with SDS-PAGE demonstrated a considerable protein breakdown during germination between day 2 and 3 in faba beans and between day 1 and 2 in soya beans. The tannin content in flour from faba beans decreased by 29.7% after seven days of germination, but the tannin content of the hulls of the faba beans did not change during that period of germination. The trypsin inhibitors in flour from soya beans decreased by 25.5% after seven days of germination. We conclude that the increased enzymatic hydrolysis of protein in both legumes cannot be explained by a decrease of tannins or trypsin inhibitors. The possible explanation is that through degradation of proteins during germination of the legumes, the cleaved protein fragments are more susceptable for hydrolysis by pepsin-pancreatin.     

Effect of rain on efficacy of fungicide deposits on potato againstPhytophthora infestans

Summary The influence of the intensity of rain and the interval between application of fungicides and the onset of rain on the efficacy of maneb-fentinacetate and fluazinam againstPhytophthora infestans in potato was evaluated in pot trials and field trials. In the pot trials a clear wash-off of maneb-fentinacetate was observed when simulated rain was applied 4 hours after plants had been sprayed with the fungicide. The retention of fluazinam deposits was higher and in some trials the efficacy in the bioassay was even increased by rain, probably by redistribution from the spray deposits. When 10 mm of simulated rain was applied 4–6 days after application of the fungicides, no decrease in the efficacy was observed with both fungicides. In the field trials fluazinam also showed a better retention of deposits compared with maneb-fentinacetate.