MeDIP coupled with a promoter tiling array as a platform to investigate global DNA methylation patterns in AML cells.

Hypermethylation of CpGs in promoter regions and subsequent changes in gene expression are common features in acute myeloid leukemia (AML). Genome-wide studies of the methylome are not only useful to understand changes in DNA methylation and gene regulation but also to identify potential targets for antileukemic treatment. Here we performed methylated DNA immunoprecipitation (MeDIP) in the AML cell line HL-60 and donor-derived CD34+ cells, followed by hybridization on a human promoter tiling array. The comparative analysis of HL-60 versus CD34+ cells revealed differentially methylated promoter regions including genes that are frequently methylated in AML, such as p15/INK4B, OLIG2, RARß2 and estrogen receptor. Microarray data was validated by quantitative pyrosequencing. We corroborate previous reports that MeDIP, in our study combined with a promoter tiling array (MeDIP-Chip), is a robust method to identify genes that are differentially methylated in AML cells in a genome-wide manner, and is thus useful to identify new epigenetic targets for therapeutic or prognostic research.

Feeding ecology of a large social antelope in the rainforest.

We studied the feeding ecology of the bongo (Tragelaphus eurycerus) in the Dzanga National Park in the rainforest of the Central African Republic to understand better the trade-off between food selectivity, ranging behaviour and social organization of a large, forest-dwelling, social antelope. Food plants and vegetation types were registered along a 311-km route travelled by bongos. Food availability was determined by identifying and counting the plants in 19 randomly chosen forest plots. Bongos showed pronounced selectivity for 26 out of 100 woody forest species. They predominantly consumed younger leaves, which suggests that high protein and low fibre content influence plant choice. In addition to leaves, bongos also ate fruits of two and flowers of one species. Furthermore, the diet was supplemented by grasses and herbs consumed on large natural licks. Such licks were regularly visited by the bongos. According to Jarman's ecological classification of antelopes, selective browsers are relatively small and live alone or in pairs to avoid competition over food. The bongo's large size and gregariousness should not allow it to survive in the rainforest as a pure selective browser. Our data suggest that the bongo relies on the opportunity to graze in bulk which it finds on the natural licks. We hypothesize that such licks either limit the distribution of bongos in other rainforest areas or allow larger group sizes than in areas without licks.