Neuropeptide VF neurons promote sleep via the serotonergic raphe

Although several sleep-regulating neuronal populations have been identified, little is known about how they interact with each other to control sleep/wake states. We previously identified neuropeptide VF (NPVF) and the hypothalamic neurons that produce it as a sleep-promoting system (Lee et al., 2017). Here we show using zebrafish that npvf-expressing neurons control sleep via the serotonergic raphe nuclei (RN), a hindbrain structure that is critical for sleep in both diurnal zebrafish and nocturnal mice. Using genetic labeling and calcium imaging, we show that npvf-expressing neurons innervate and can activate serotonergic RN neurons. We also demonstrate that chemogenetic or optogenetic stimulation of npvf-expressing neurons induces sleep in a manner that requires NPVF and serotonin in the RN. Finally, we provide genetic evidence that NPVF acts upstream of serotonin in the RN to maintain normal sleep levels. These findings reveal a novel hypothalamic-hindbrain neuronal circuit for sleep/wake control

Neuropeptide VF neurons promote sleep via the serotonergic raphe

Although several sleep-regulating neuronal populations have been identified, little is known about how they interact with each other to control sleep/wake states. We previously identified neuropeptide VF (NPVF) and the hypothalamic neurons that produce it as a sleep-promoting system (Lee et al., 2017). Here we show using zebrafish that npvf-expressing neurons control sleep via the serotonergic raphe nuclei (RN), a hindbrain structure that is critical for sleep in both diurnal zebrafish and nocturnal mice. Using genetic labeling and calcium imaging, we show that npvf-expressing neurons innervate and can activate serotonergic RN neurons. We also demonstrate that chemogenetic or optogenetic stimulation of npvf-expressing neurons induces sleep in a manner that requires NPVF and serotonin in the RN. Finally, we provide genetic evidence that NPVF acts upstream of serotonin in the RN to maintain normal sleep levels. These findings reveal a novel hypothalamic-hindbrain neuronal circuit for sleep/wake control

Comparison of Paleodietary Reconstructions Using Pre- and Post-Glacial Mammut and Mammuthus

Mesowear, microwear and dental calculus analyses are utilized to complete dietary reconstructions on Mammut and Mammuthus, and are compared to modern Loxodonta africana. These analyses demonstrate that left and right, upper and lower, and imperfect molars may be utilized indiscriminately. Loxodonta africana are grazers or mixed-feeders. Mammut were primarily browsers, but may have changed their diets meal-by-meal or seasonally to graze or mixed-feed. Mesowear analysis of Mammuthus indicates a grazing diet, but microwear analysis indicates a mixed-feeding diet. Dental calculus analysis shows all three species were mixed-feeding. Mesowear and microwear show no differences in pre- and post-glacial diet for fossil proboscideans, but dental calculus showed large differences. In pre-glacial dental calculus there was a larger proportion of tiny grass starch granules, whereas post-glacially there is a larger proportion of large grass starch granules with lamellae. This result is consistent with a shift in Mammut and Mammuthus diet during the end-Pleistocene

Diet reconstructions for end-Pleistocene Mammut americanum and Mammuthus based on comparative analysis of mesowear, microwear, and dental calculus in modern Loxodonta africana

We analyse mesowear, microwear, and dental calculus for end-Pleistocene Mammut and Mammuthus from North America, and modern Loxodonta africana to reconstruct diet. These three methods allow both short- and long-term diets to be distinguished. As microwear analysis shows a negative correlation between the numbers of pits and scratches counted, the proportions of pits/(pits + scratches) were used for analyses rather than gross counts. The three types of analyses confirm that modern Loxodonta africana are grazers or mixed-feeders. Microwear analysis demonstrates that end-Pleistocene Mammut were primarily browsers but may have changed their diets opportunistically or seasonally to graze. Mesowear analysis of end-Pleistocene Mammuthus indicates a grazing diet, but microwear analysis indicates a mixed-feeding diet. Dental calculus analysis demonstrates that all three species were mixed-feeding to varying degrees. Results show that extinct proboscidean diet was more complex than previously thought, and may contradict previous work suggesting that Mammut were browsers and Mammuthus were grazers. Using mesowear and microwear, we found no significant differences in pre- and post-glacial diet for fossil proboscideans. However, using dental calculus, we found that for pre-glacial specimens there was a larger proportion of tiny (i.e. less than 8 μm wide) grass starch granules, whereas for post-glacial specimens there is a larger proportion of large (i.e. greater than 20 μm wide) grass starch granules with lamellae, suggesting with a shift in Mammut and Mammuthus diet during the end-Pleistocene. Specimens commonly had different dietary signals depending on the method utilized, suggesting that a multi-faceted approach is required to fully elucidate proboscidean diet.Natural Sciences and Engineering Research Council (NSERC