ABSTRACT
Genetic studies have shown that the MAP kinase MGV1 and the transcriptional regulator TRI6 regulate many of the same biosynthetic gene clusters (BGCs) in Fusarium graminearum. This study sought to investigate the relationship between MGV1 and TRI6 in the regulatory hierarchy. Transgenic F. graminearum strains constitutively expressing MGV1 and TRI6 were generated to address both independent and epistatic regulation of BGCs by MGV1 and TRI6. We performed a comparative transcriptome analysis between axenic cultures grown in nutrient-rich and secondary metabolite-inducing conditions. The results indicated that BGCs regulated independently by Mgv1 included genes of BGC52, whereas genes uniquely regulated by TRI6 included the gene cluster (BGC49) that produces gramillin. To understand the epistatic relationship between MGV1 and TRI6, CRISPR/Cas9 was used to insert a constitutive promoter to drive TRI6 expression in the Δmgv1 strain. The results indicate that BGCs that produce deoxynivalenol and fusaoctaxin are co-regulated, with TRI6 being partially regulated by MGV1. Overall, the findings from this study indicate that MGV1 provides an articulation point to differentially regulate various BGCs. Moreover, TRI6, embedded in one of the BGCs provides specificity to regulate the expression of the genes in the BGC.
ABSTRACT
Colic is a common and potentially life-threatening condition of horses. Multiple risk factors have been previously identified and it is known that a careful management routine can help reduce colic rates. The British military working horse population represents a unique cohort of horses that are intensively managed with a strict regimen. This retrospective study examined the incidence and mortality rate of colic within this population, as well as the signalment of affected horses, and compared these with the general population. Data for 717 horses over a five-year period (2008-2012) were analysed. Of these, 163 horses (22.7 per cent) experienced 267 colic episodes and 13 horses (1.8 per cent) died because of colic. Recurrent colic was experienced by 35 per cent (57/163) of horses. The incidence of colic was 11.1 episodes per 100 horse-years and of colic-related death was 0.5 deaths per 100 horse-years. Horses purchased from mainland Europe were more likely to suffer from colic (OR 4.6; P<0.001) and from recurrent colic (OR 6.0; P=0.005) than horses purchased from Ireland. Only 3 per cent (8/267) of colic episodes were treated surgically. It was concluded that the incidences of colic and colic-related deaths within the British military working horse population are similar to those of the general horse population.
