Evidence for conservation of primordial ~12-hour ultradian gene programs in humans under free-living conditions.

While circadian rhythms are entrained to the once daily light-dark cycle of the sun, many marine organisms exhibit ~12h ultradian rhythms corresponding to the twice daily movement of the tides. Although human ancestors emerged from circatidal environment millions of years ago, direct evidence of ~12h ultradian rhythms in humans is lacking. Here, we performed prospective, temporal transcriptome profiling of peripheral white blood cells and identified robust ~12h transcriptional rhythms from three healthy participants. Pathway analysis implicated ~12h rhythms in RNA and protein metabolism, with strong homology to the circatidal gene programs previously identified in Cnidarian marine species. We further observed ~12h rhythms of intron retention events of genes involved in MHC class I antigen presentation, synchronized to expression of mRNA splicing genes in all three participants. Gene regulatory network inference revealed XBP1, and GABP and KLF transcription factor family members as potential transcriptional regulators of human ~12h rhythms. These results suggest that human ~12h biological rhythms have a primordial evolutionary origin with important implications for human health and disease.

Validation of the C.A.R.E. stimulus set of 640 animal pictures: Name agreement and quality ratings.

Stimulus sets are valuable tools that can facilitate the work of researchers designing experiments. Images of faces, and line drawings of objects have been developed and validated, however, pictures of animals, that do not contain backgrounds, have not been made available. Here we present image agreement and quality ratings for a set of 640 color images of animals on a transparent background, across 60 different basic categories (e.g. cat, dog, frog, bird), some with few, and others with many exemplars. These images were normed on 302 participants. Image agreement was measured both with respect to the proportion of participants that provided the same name as well as the H-statistic for each image. Image quality was measured both overall, and with respect to the accuracy of participants' naming of the basic category. Word frequency of each basic and superordinate category based on the English Lexicon Project (Balota, et al., 2007) and the HAL database (Kucera & Francis, 1976) are provided as are Age of Acquisition (Kuperman, Stadthagen-Gonzalez, & Brysbaert, 2012) data.