Sheep farmers in the UK rely on strategic anthelmintic use to treat and control gastrointestinal roundworms in their flocks. However, resistance to these drugs is now widespread and threatens the sustainability of sheep production. The mechanisms underlying resistance to the most commonly used class, the macrocyclic lactones, are not known and sensitive diagnostic tools based on molecular markers are not currently available. This prohibits accurate surveillance of resistance or assessment of strategies aimed at controlling its spread. In this study, we examined four UK field populations of Haemonchus contortus, differing in macrocyclic lactone treatment history, for evidence of selection at 'candidate gene' loci identified as determining macrocyclic lactone resistance in previously published research. Individual worms were genotyped at Hc-lgc-37, Hc-glc-5, Hc-avr-14 and Hc-dyf-7, and four microsatellite loci. High levels of polymorphism were identified at the first three candidate gene loci with remarkably little polymorphism at Hc-dyf-7. While some between-population comparisons of individual farms with and without long-term macrocyclic lactone use identified statistically significant differences in allele frequency and/or fixation index at the Hc-lgc-37, Hc-glc-5 or Hc-avr-14 loci, we found no consistent evidence of selection in other equivalent comparisons. While it is possible that different mechanisms are important in different populations or that resistance may be conferred by small changes at multiple loci, our findings suggest that these are unlikely to be major loci conferring macrocyclic lactone resistance on UK farms or suitable for diagnostic marker development. More powerful approaches, using genome-wide or whole genome sequencing, may be required to define macrocyclic lactone resistance loci in such genetically variable populations.
- MeSH
- frekvence genu MeSH
- genetická variace MeSH
- genotypizační techniky MeSH
- Haemonchus účinky léků genetika MeSH
- hemonchóza farmakoterapie parazitologie veterinární MeSH
- laktony farmakologie terapeutické užití MeSH
- léková rezistence genetika MeSH
- makrocyklické laktamy farmakologie terapeutické užití MeSH
- nemoci ovcí farmakoterapie parazitologie MeSH
- ovce MeSH
- polymorfismus délky restrikčních fragmentů MeSH
- vazebná nerovnováha MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Spojené království MeSH
Cryptosporidium parvum contains a unique fusion protein pyruvate:NADP+ oxidoreductase (CpPNO) that is composed of two distinct, conserved domains, an N-terminal pyruvate:ferredoxin oxidoreductase (PFO) and a C-terminal cytochrome P450 reductase (CPR). Unlike a similar fusion protein that localizes to the mitochondrion of the photosynthetic protist Euglena gracilis, CpPNO lacks an N-terminal mitochondrial targeting sequence. Using two distinct polyclonal antibodies raised against CpPFO and one polyclonal antibody against CpCPR, Western blot analysis has shown that sporozoites of C. parvum express the entire CpPNO fusion protein. Furthermore, confocal immunofluorescence and transmission electron microscopy confirm that CpPNO is localized within the cytosol rather than the relict mitochondrion of C. parvum. The distribution of this protein is not, however, strictly confined to the cytosol. CpPNO also appears to localize posteriorly within the crystalloid body.
- MeSH
- Cryptosporidium parvum cytologie enzymologie genetika MeSH
- cytosol enzymologie MeSH
- Euglena gracilis cytologie enzymologie MeSH
- financování organizované MeSH
- fluorescenční mikroskopie MeSH
- ketonoxidoreduktasy analýza genetika imunologie MeSH
- konfokální mikroskopie MeSH
- NADPH-cytochrom c-reduktasa analýza genetika imunologie MeSH
- organely enzymologie MeSH
- protozoální proteiny analýza MeSH
- pyruvátsynthasa analýza genetika imunologie MeSH
- sporozoiti cytologie enzymologie MeSH
- transmisní elektronová mikroskopie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
