Project description:Linguistic and cultural evidence suggests that Madagascar was the final point of two major dispersals of Austronesian and Bantu speaking populations. Today, Mikea are described as the last known Malagasy population reported to be still practising a hunter-gatherer life-style. It is unclear, however, whether Mikea descend from a remnant population that existed before the arrival of Austronesian and Bantu agriculturalists or whether it is only their life-style that separates them from the other contemporary populations of South Madagascar. In order to address these questions we have performed a genome wide analysis of >700,000 SNP markers on 21 Mikea, 24 Vezo and 24 Temoro individuals together with 50 individuals from Bajo and Lebbo populations from Indonesia. Our analyses of these data in the context of data available from other Southeast Asian and African populations reveal that all three Malagasy populations are derived from the same admixture event involving Austronesian and Bantu sources. In contrast to the fact that most of the vocabulary of the Malagasy speakers is derived from the Barito group of the Austronesian language family we observe that only one third of their genetic ancestry is related to the populations of Java-Kalimantan-Sulawesi area. Because no additional ancestry components distinctive to for the Mikea were found, it is likely that they have adopted their hunter-gatherer way of life by through cultural reversion.
Project description:Adult female three-spined stickleback fish (Gasterosteus aculeatus) were exposed to 10 individual chemicals, 26 mixtures of these chemicals, or control conditions in a flow-through system for 4 days. Transcriptomics was performed on liver samples by microarray. The main aims were to determine molecular signatures induced by these chemicals in the three-spined stickleback, discover whether these persisted in chemical mixtures and identify non-additive molecular responses in chemical mixtures exposures.
Project description:Linguistic and cultural evidence suggests that Madagascar was the final point of two major dispersals of Austronesian and Bantu speaking populations. Today, Mikea are described as the last known Malagasy population reported to be still practising a hunter-gatherer life-style. It is unclear, however, whether Mikea descend from a remnant population that existed before the arrival of Austronesian and Bantu agriculturalists or whether it is only their life-style that separates them from the other contemporary populations of South Madagascar. In order to address these questions we have performed a genome wide analysis of >700,000 SNP markers on 21 Mikea, 24 Vezo and 24 Temoro individuals together with 50 individuals from Bajo and Lebbo populations from Indonesia. Our analyses of these data in the context of data available from other Southeast Asian and African populations reveal that all three Malagasy populations are derived from the same admixture event involving Austronesian and Bantu sources. In contrast to the fact that most of the vocabulary of the Malagasy speakers is derived from the Barito group of the Austronesian language family we observe that only one third of their genetic ancestry is related to the populations of Java-Kalimantan-Sulawesi area. Because no additional ancestry components distinctive to for the Mikea were found, it is likely that they have adopted their hunter-gatherer way of life by through cultural reversion. 69 samples were analysed with the Illumina platform OmniExpress BeadChips and are described herein.
Project description:Plasticity in the daily timing of activity has been observed in a wide variety of species, yet the underlying mechanisms driving nocturnality and diurnality remain to be discovered. By regulating how much wheel-running activity will be rewarded with a food pellet, we can manipulate energy balance, and switch mice to be nocturnal or diurnal. Here we present the rhythmic transcriptome of 21 tissues, including 17 brain regions (hypothalamic, thalamic, cortical), sampled every 4 hours over a 24-hour period from nocturnal and diurnal male CBA/CaJ mice. Rhythmic gene expression across tissues comprised a different set of genes with minimal overlap between nocturnal and diurnal mice. We show that genes other than clock genes in the suprachiasmatic nucleus (SCN) of nocturnal and diurnal mice change, and the habenula was the most affected tissue. Our results indicate that adaptive flexibility in daily timing of behavior is supported by gene expression dynamics in many tissues and brain regions, especially in the habenula, which suggests a crucial role for the observed nocturnal-diurnal switch.
Project description:Vertebrate ancestors had only cone-like photoreceptors. The duplex retina evolved in jawless vertebrates with the advent of highly photosensitive rod-like photoreceptors. Despite cones being the arbiters of high-resolution color vision, rods emerged as the dominant photoreceptor in mammals during a nocturnal phase early in their evolution. We investigated the evolutionary and developmental origins of rods in two divergent vertebrate retinae. In mice, we discovered genetic and epigenetic vestiges of short wavelength cones in developing rods and cell lineage tracing validated the genesis of rods from S-cones. Curiously, rods did not derive from S-cones in zebrafish. Our study illuminates several questions regarding the evolution of duplex retina and supports the hypothesis that, in mammals, the S-cone lineage was recruited via the Maf-family transcription factor NRL to augment rod photoreceptors. We propose that this developmental mechanism allowed the adaptive exploitation of scotopic niches during the nocturnal bottleneck early in mammalian evolution.
Project description:Most animals restrict their activity to specific part of the day, being either diurnal, nocturnal, or crepuscular. The genetic basis underlying this diurnal preference is largely unknown. Under laboratory conditions, Drosophila melanogaster is crepuscular, showing a bi-modal activity profile. However, recent experiments in our lab indicated that high variability among individuals exist, particularly in strains that derive from different wild populations. By assembling together flies from various geographical strains, we have generated a highly diverse population whose progeny exhibited extreme diurnal preference, including diurnal and nocturnal flies. We have used this population as a starting point for an artificial selection experiment in which we selected males that show the most extreme diurnal preference and mated them to their sisters. The response to selection was strong, and already after 10 selection cycles we obtained highly diurnal (D) and nocturnal (N) strains. Another strain that was not selected and showed intermediate behaviour (crepuscular) served as a control (C). These strains provide us with a unique opportunity to understand the genetics of diurnal preference.
Project description:To clarify the selective advantage of the GPI-AP- cells in paroxysmal nocturnal hemoglobinuria (PNH) patients, RNA-seq was applied to examine functional effects of the PIG-A mutation in human granulocytes.