DNA methylation extends lifespan in the bumblebee Bombus terrestris.

Epigenetic alterations are a primary hallmark of ageing. In mammals, age-related epigenetic changes alter gene expression profiles, disrupt cellular homeostasis and physiological functions and, therefore, promote ageing. It remains unclear whether ageing is also driven by epigenetic mechanisms in invertebrates. Here, we used a pharmacological hypomethylating agent (RG108) to evaluate the effects of DNA methylation (DNAme) on lifespan in an insect-the bumblebee Bombus terrestris. RG108 extended mean lifespan by 43% and induced the differential methylation of genes involved in hallmarks of ageing, including DNA damage repair and chromatin organization. Furthermore, the longevity gene sirt1 was overexpressed following the treatment. Functional experiments demonstrated that SIRT1 protein activity was positively associated with lifespan. Overall, our study indicates that epigenetic mechanisms are conserved regulators of lifespan in both vertebrates and invertebrates and provides new insights into how DNAme is involved in the ageing process in insects.

DNA methylation and expression of the egfr gene are associated with worker size in monomorphic ants.

The reproductive division of labour is a hallmark of eusocial Hymenoptera. Females are either reproductive queens or non-reproductive workers. In ants, workers often display further task specialisation that is associated with variation in size and/or morphology. Because female polyphenism is typically under environmental control, it is thought epigenetic mechanisms (such as DNA methylation) play a central role since they mediate gene-by-environment interactions. Methylation of the growth-promoting gene epidermal growth factor receptor (egfr) was indeed shown to control worker size in a highly polymorphic ant. However, it remains unknown if egfr methylation could also regulate worker size in monomorphic species. By combining experimental pharmacology and molecular biology, we show that worker size is associated with egfr methylation in two monomorphic ants. Furthermore, we functionally demonstrate that EGFR signalling affects worker size. These results indicate that worker size regulation by egfr methylation has been mechanistically conserved in ants but remains unexploited in monomorphic species.

Cytomegalovirus encephalitis: Undescribed diffusion-weighted imaging characteristics. Original aspects of cases extracted from a retrospective study, and from literature review.

INTRODUCTION: There is paucity of studies analyzing DWI in MRI sequences when imaging cytomegalovirus (CMV) meningoencephalitis. The main objective of this study is to demonstrate that DWI sequence is mandatory when imaging immunocompromised patients presenting with encephalitic symptoms, as this sequence can reveal very peculiar lesions in the setting of CMV encephalitis. PATIENTS AND METHOD: Three CSF PCR CMV positive cases were identified in a 13-year retrospective study with MRI scans including T1, FLAIR, DWI with automated ADC calculation, and T1 with contrast injection, and were reviewed by a senior neuroradiologist. RESULTS: Our three cases presented multiple high-signal intensity punctiform lesions in DWI, which uniformly were in restricted diffusion. Each patient had multiple lesions (mean 19.3, range 12-30): 96.5% were supratentorial and 3.5% were infratentorial. Among supratentorial lesions, 62.5% were subependymal, 28.6% were periventricular and 8.9% were subcortical. Some lesions remained in a long lasting restricted diffusion state. All cases had FLAIR curvilinear periventricular high signal intensities. No contrast uptake was found. DISCUSSION: Punctiform DWI lesions had a clear ventricle wall tropism, consistent with classical autopsy findings. The classical histological knowledge-compatible explanation for long lasting diffusion restriction is non-lethal cytotoxic edema owing to CMV inclusions. CONCLUSION: Subependymal and periventricular punctiform restricted diffusion lesions in the setting of meningoencephalitis in immunocompromised patients seem highly evocative of CMV encephalitis. The diffusion sequence probably reveals focal lesions constitutive of cellular viral inclusions.