Knockdown of GABAA alpha3 subunits on thalamic reticular neurons enhances deep sleep in mice.

Identification of mechanisms which increase deep sleep could lead to novel treatments which promote the restorative effects of sleep. Here, we show that knockdown of the α3 GABAA-receptor subunit from parvalbumin neurons in the thalamic reticular nucleus using CRISPR-Cas9 gene editing increased the thalamocortical delta (1.5-4 Hz) oscillations which are implicated in many health-promoting effects of sleep. Inhibitory synaptic currents in thalamic reticular parvalbumin neurons were strongly reduced in vitro. Further analysis revealed that delta power in long NREM bouts prior to NREM-REM transitions was preferentially affected by deletion of α3 subunits. Our results identify a role for GABAA receptors on thalamic reticular nucleus neurons and suggest antagonism of α3 subunits as a strategy to enhance delta activity during sleep.

Multiple migrations to the Philippines during the last 50,000 years.

Island Southeast Asia has recently produced several surprises regarding human history, but the region's complex demography remains poorly understood. Here, we report ∼2.3 million genotypes from 1,028 individuals representing 115 indigenous Philippine populations and genome-sequence data from two ∼8,000-y-old individuals from Liangdao in the Taiwan Strait. We show that the Philippine islands were populated by at least five waves of human migration: initially by Northern and Southern Negritos (distantly related to Australian and Papuan groups), followed by Manobo, Sama, Papuan, and Cordilleran-related populations. The ancestors of Cordillerans diverged from indigenous peoples of Taiwan at least ∼8,000 y ago, prior to the arrival of paddy field rice agriculture in the Philippines ∼2,500 y ago, where some of their descendants remain to be the least admixed East Asian groups carrying an ancestry shared by all Austronesian-speaking populations. These observations contradict an exclusive "out-of-Taiwan" model of farming-language-people dispersal within the last four millennia for the Philippines and Island Southeast Asia. Sama-related ethnic groups of southwestern Philippines additionally experienced some minimal South Asian gene flow starting ∼1,000 y ago. Lastly, only a few lowlanders, accounting for <1% of all individuals, presented a low level of West Eurasian admixture, indicating a limited genetic legacy of Spanish colonization in the Philippines. Altogether, our findings reveal a multilayered history of the Philippines, which served as a crucial gateway for the movement of people that ultimately changed the genetic landscape of the Asia-Pacific region.

Basal Forebrain Parvalbumin Neurons Mediate Arousals from Sleep Induced by Hypercarbia or Auditory Stimuli.

The ability to rapidly arouse from sleep is important for survival. However, increased arousals in patients with sleep apnea and other disorders prevent restful sleep and contribute to cognitive, metabolic, and physiologic dysfunction [1, 2]. Little is currently known about which neural systems mediate these brief arousals, hindering the development of treatments that restore normal sleep. The basal forebrain (BF) receives inputs from many nuclei of the ascending arousal system, including the brainstem parabrachial neurons, which promote arousal in response to elevated blood carbon dioxide levels, as seen in sleep apnea [3]. Optical inhibition of the terminals of parabrachial neurons in the BF impairs cortical arousals to hypercarbia [4], but which BF cell types mediate cortical arousals in response to hypercarbia or other sensory stimuli is unknown. Here, we tested the role of BF parvalbumin (PV) neurons in arousal using optogenetic techniques in mice. Optical stimulation of BF-PV neurons produced rapid transitions to wakefulness from non-rapid eye movement (NREM) sleep but did not affect REM-wakefulness transitions. Unlike previous studies of BF glutamatergic and cholinergic neurons, arousals induced by stimulation of BF-PV neurons were brief and only slightly increased total wake time, reminiscent of clinical findings in sleep apnea [5, 6]. Bilateral optical inhibition of BF-PV neurons increased the latency to arousal produced by exposure to hypercarbia or auditory stimuli. Thus, BF-PV neurons are an important component of the brain circuitry that generates brief arousals from sleep in response to stimuli, which may indicate physiological dysfunction or danger to the organism.

Optogenetic stimulation of basal forebrain parvalbumin neurons modulates the cortical topography of auditory steady-state responses.

High-density electroencephalographic (hdEEG) recordings are widely used in human studies to determine spatio-temporal patterns of cortical electrical activity. How these patterns of activity are modulated by subcortical arousal systems is poorly understood. Here, we couple selective optogenetic stimulation of a defined subcortical cell-type, basal forebrain (BF) parvalbumin (PV) neurons, with hdEEG recordings in mice (Opto-hdEEG). Stimulation of BF PV projection neurons preferentially generated time-locked gamma oscillations in frontal cortices. BF PV gamma-frequency stimulation potently modulated an auditory sensory paradigm used to probe cortical function in neuropsychiatric disorders, the auditory steady-state response (ASSR). Phase-locked excitation of BF PV neurons in advance of 40 Hz auditory stimuli enhanced the power, precision and reliability of cortical responses, and the relationship between responses in frontal and auditory cortices. Furthermore, synchronization within a frontal hub and long-range cortical interactions were enhanced. Thus, phasic discharge of BF PV neurons changes cortical processing in a manner reminiscent of global workspace models of attention and consciousness.

Pollen flow and paternity in an isolated and non-isolated black walnut (Juglans nigra L.) timber seed orchard.

Artificial pollination of black walnut (Juglans nigra L.) is not practical and timber breeders have historically utilized only open-pollinated half-sib families. An alternate approach called "breeding without breeding," consists of genotyping open-pollinated progeny using DNA markers to identify paternal parents and then constructing full-sib families. In 2014, we used 12 SSR markers to genotype 884 open-pollinated half-sib progeny harvested from two clonal orchards containing 206 trees, comprised of 52 elite timber selections. Seed was harvested in 2011 from each of two ramets of 23 clones, one upwind and one downwind, based on prevailing wind direction from the west-southwest. One orchard was isolated from wild black walnut and composed of forward selections while the other orchard was adjacent to a natural forest containing mature black walnut composed of backward selections. Isolation significantly increased within-orchard pollination (85%) of the progeny from the isolated orchard compared to 42% from the non-isolated orchard. Neither prevailing wind direction nor seed tree position in the orchard affected paternity patterns or wild pollen contamination. Genetic diversity indices revealed that progeny from both orchards were in Hardy-Weinberg equilibrium with very little inbreeding and no selfing. A significant level of inbreeding was present among the forward selected parents, but not the first generation (backward selected) parents. Some orchard clones failed to sire any progeny while other clones pollinated upwards of 20% of progeny.

Prolonging the survival of Tsc2 conditional knockout mice by glutamine supplementation.

The genetic disease tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by loss of function mutations in either TSC1 (hamartin) or TSC2 (tuberin), which serve as negative regulators of mechanistic target of rapamycin complex 1 (mTORC1) activity. TSC patients exhibit developmental brain abnormalities and tuber formations that are associated with neuropsychological and neurocognitive impairments, seizures and premature death. Mechanistically, TSC1 and TSC2 loss of function mutations result in abnormally high mTORC1 activity. Thus, the development of a strategy to inhibit abnormally high mTORC1 activity may have therapeutic value in the treatment of TSC. mTORC1 is a master regulator of growth processes, and its activity can be reduced by withdrawal of growth factors, decreased energy availability, and by the immunosuppressant rapamycin. Recently, glutamine has been shown to alter mTORC1 activity in a TSC1-TSC2 independent manner in cells cultured under amino acid- and serum-deprived conditions. Since starvation culture conditions are not physiologically relevant, we examined if glutamine can regulate mTORC1 in non-deprived cells and in a murine model of TSC. Our results show that glutamine can reduce phosphorylation of S6 and S6 kinase, surrogate indicators of mTORC1 activity, in both deprived and non-deprived cells, although higher concentrations were required for non-deprived cultures. When administered orally to TSC2 knockout mice, glutamine reduced S6 phosphorylation in the brain and significantly prolonged their lifespan. Taken together, these results suggest that glutamine supplementation can be used as a potential treatment for TSC.