Genetics of resistance to transgenic Bacillus thuringiensis poplars in the poplar leaf beetle, Chrysomela tremulae F. (Coleoptera: Chrysomelidae)

International audienceThe area under genetically engineered plants producing Bacillus thuringiensis (Bt) toxins is steadily increasing. This increase has magnified the risk of alleles conferring resistance to these toxins being selected in natural populations of target insect pests. The speed at which this selection is likely to occur depends on the genetic characteristics of Bt resistance. We selected a strain of the beetle Chrysomela tremulae Fabricius on a transgenic Bt poplar clone Populus tremula L. x Populus tremuloides Michx producing high levels of B.thuringiensis Cry3Aa toxin. This strain was derived from an isofemale line that generated some F-2 offspring that actively fed on this Bt poplar clone. The resistance ratio of the strain was >6,400. Susceptibility had decreased to such an extent that the mortality of beetles of the strain fed Bt poplar leaves was similar to that of beetles fed nontransgenic poplar leaves. Genetic crosses between susceptible, resistant, and F1 hybrids showed that resistance to the Cry3Aa toxin was almost completely recessive (D-LC = 0.07) and conferred by a single autosomal gene. The concentration of Cry3Aa produced in the transgenic Bt poplar used in this study was 6.34 times higher than the LC99 of the F1 hybrids, accounting for the complete recessivity (D-ML = 0) of survival on Bt poplar leaves. Overall, the genetic characteristics of the resistance of C. tremulae to the Cry3Aa toxin are consistent with the assumptions underlying the high-dose refuge strategy, which aims to decrease the selection of Bt resistance alleles in natural target pest populations

Incidence and risk factors for thromboembolic events in pediatric-onset inflammatory bowel disease: A French population-based study

International audienceIntroduction: Patients with inflammatory bowel disease (IBD) are at higher risk of thromboembolic events (TE). In pediatric-onset IBD, more data on incidence and risk factors of venous (VTE) and arterial events (ATE) at the population level are needed to guide thromboprophylaxis.Methods: All patients aged ≤ 16 years diagnosed with Crohn's disease (CD) or ulcerative colitis (UC) between 1988 and 2011 in the prospective EPIMAD population-based registry were followed until 2013. Every TE occurring during the follow-up period was included.Results: A total of 1,344 patients were included: 1,007 with CD and 337 with UC, and a median diagnosis age of 14.3 years. After a median follow-up of 8.3 years, 2 (0.15 %) ATE and 15 (1.1 %) VTE occurred at median age of 20.4 years. The global incidence rate of thromboembolic events was 1.32 per 1000 person-years. Periods of active disease (HR=8.4, p = 0.0002), the 3-month-period following surgery (HR=16.4, p = 0.0002) and hospitalization (HR=21.7, p < 0.0001) were found to be associated with an increased risk of VTE. A lower rate of VTE was found in patients treated with 5-aminosalicylates (HR=0.1, p = 0.002).Conclusion: The risk of TE was low in this population. VTE were strongly associated with active disease, surgery and hospitalization

Incidence, prevalence and clinical presentation of inflammatory bowel diseases in Northern France: a 30-year population-based studyResearch in context

Summary: Background: In industrialized countries, the incidence of inflammatory bowel disease (IBD) appears stabilized. This study examined the incidence and phenotype of IBD in Northern France over a 30-year period. Methods: Including all IBD patients recorded in the EPIMAD population-based registry from 1988 to 2017 in Northern France, we described the incidence and clinical presentation of IBD according to age, sex and time. Findings: A total of 22,879 incident IBD cases were documented (59% (n = 13,445) of Crohn’s disease (CD), 38% (n = 8803) of ulcerative colitis (UC), 3% (n = 631) of IBD unclassified (IBDU)). Over the study period, incidence of IBD, CD and UC was 12.7, 7.2 and 5.1 per 105 person-years, respectively. The incidence of CD increased from 5.1/105 in 1988–1990 to 7.9/105 in 2015–2017 (annual percent change (APC): +1.9%, p < 0.0001). The incidence of UC increased from 4.5/105 to 6.1/105 (APC: +1.3%, p < 0.0001). The largest increase was observed in children (+4.3% in CD, p < 0.0001; +5.4% in UC, p < 0.0001) followed by young adults aged 17–39 years (+1.9% in CD, p < 0.0001; +1.5% in UC, p < 0.0001). The increase in UC incidence was significantly higher in women than in men (+1.9% in women, +0.8% in men; p = 0.006). We estimated that in our area, by 2030, nearly 0.6% of the population will have IBD. Interpretation: The persistent increase of IBD incidence among children and young adults but also in women with UC in Northern France, suggests the persistence of substantial predisposing environmental factors. Funding: Santé Publique France; INSERM; Amiens, Lille and Rouen University Hospitals