Genome sequences of Tropheus moorii and Petrochromis trewavasae, two eco-morphologically divergent cichlid fishes endemic to Lake Tanganyika.

With more than 1000 species, East African cichlid fishes represent the fastest and most species-rich vertebrate radiation known, providing an ideal model to tackle molecular mechanisms underlying recurrent adaptive diversification. We add high-quality genome reconstructions for two phylogenetic key species of a lineage that diverged about ~ 3-9 million years ago (mya), representing the earliest split of the so-called modern haplochromines that seeded additional radiations such as those in Lake Malawi and Victoria. Along with the annotated genomes we analysed discriminating genomic features of the study species, each representing an extreme trophic morphology, one being an algae browser and the other an algae grazer. The genomes of Tropheus moorii (TM) and Petrochromis trewavasae (PT) comprise 911 and 918 Mbp with 40,300 and 39,600 predicted genes, respectively. Our DNA sequence data are based on 5 and 6 individuals of TM and PT, and the transcriptomic sequences of one individual per species and sex, respectively. Concerning variation, on average we observed 1 variant per 220 bp (interspecific), and 1 variant per 2540 bp (PT vs PT)/1561 bp (TM vs TM) (intraspecific). GO enrichment analysis of gene regions affected by variants revealed several candidates which may influence phenotype modifications related to facial and jaw morphology, such as genes belonging to the Hedgehog pathway (SHH, SMO, WNT9A) and the BMP and GLI families.

Cage bedding modifies metabolic and gut microbiota profiles in mouse studies applying dietary restriction.

Experiments involving food restriction are common practice in metabolic research. Under fasted conditions, mice supplement their diet with cage bedding. We aimed at identifying metabolic and microbiota-related parameters affected by the bedding type. We exposed mice housed with wooden, cellulose, or corncob cage beddings to ad libitum feeding, caloric restriction (CR), or over-night (ON) fasting. Additionally, two subgroups of the ON fast group were kept without any bedding or on a metal grid preventing coprophagy. Mice under CR supplemented their diet substantially with bedding; however, the amount varied depending on the kind of bedding. Bedding-related changes in body weight loss, fat loss, cecum size, stomach weight, fecal output, blood ghrelin levels as well as a response to glucose oral tolerance test were recorded. As fiber is fermented by the gut bacteria, the type of bedding affects gut bacteria and fecal metabolites composition of CR mice. CR wood and cellulose groups showed distinct cecal metabolite and microbiome profiles when compared to the CR corncob group. While all ad libitum fed animal groups share similar profiles. We show that restriction-related additional intake of bedding-derived fiber modulates multiple physiological parameters. Therefore, the previous rodent studies on CR, report the combined effect of CR and increased fiber consumption.