Huddling substates in mice facilitate dynamic changes in body temperature and are modulated by Shank3b and Trpm8 mutation.

Social thermoregulation is a means of maintaining homeostatic body temperature. While adult mice are a model organism for studying both social behavior and energy regulation, the relationship between huddling and core body temperature (Tb) is poorly understood. Here, we develop a behavioral paradigm and computational tools to identify active-huddling and quiescent-huddling as distinct thermal substates. We find that huddling is an effective thermoregulatory strategy in female but not male groups. At 23°C (room temperature), but not 30°C (near thermoneutrality), huddling facilitates large reductions in Tb and Tb-variance. Notably, active-huddling is associated with bidirectional changes in Tb, depending on its proximity to bouts of quiescent-huddling. Further, group-housed animals lacking the synaptic scaffolding gene Shank3b have hyperthermic Tb and spend less time huddling. In contrast, individuals lacking the cold-sensing gene Trpm8 have hypothermic Tb - a deficit that is rescued by increased huddling time. These results reveal how huddling behavior facilitates acute adjustments of Tb in a state-dependent manner.

Neural cell-types and circuits linking thermoregulation and social behavior.

Understanding how social and affective behavioral states are controlled by neural circuits is a fundamental challenge in neurobiology. Despite increasing understanding of central circuits governing prosocial and agonistic interactions, how bodily autonomic processes regulate these behaviors is less resolved. Thermoregulation is vital for maintaining homeostasis, but also associated with cognitive, physical, affective, and behavioral states. Here, we posit that adjusting body temperature may be integral to the appropriate expression of social behavior and argue that understanding neural links between behavior and thermoregulation is timely. First, changes in behavioral states-including social interaction-often accompany changes in body temperature. Second, recent work has uncovered neural populations controlling both thermoregulatory and social behavioral pathways. We identify additional neural populations that, in separate studies, control social behavior and thermoregulation, and highlight their relevance to human and animal studies. Third, dysregulation of body temperature is linked to human neuropsychiatric disorders. Although body temperature is a "hidden state" in many neurobiological studies, it likely plays an underappreciated role in regulating social and affective states.

Establishment of a cell culture-qPCR system to quantify early developmental stages of Eimeria zuernii.

Bovine coccidiosis is caused by apicomplexans of the genus Eimeria and results in significant economic losses in the cattle industry worldwide. Numerous anticoccidial drugs are available for the treatment of bovine Eimeria infections. However, many compounds have been on the market for decades, and multidrug resistance is commonly observed in avian Eimeria. Recent reports of anticoccidial resistance in ovine Eimeria indicate the need for a rapid and inexpensive in vitro method to assess drug efficacy against ruminant Eimeria. Currently, no such assay exists for bovine Eimeria. The aim of this study was to develop a Madin-Darby bovine kidney (MDBK) cell culture-qPCR model to support the development of Eimeria (E.) zuernii in laboratory settings. The established in vitro assay was applied on three field strains of E. zuernii from the western United States to identify its general suitability for a variety of field strains. Infected cells were observed microscopically and analyzed by quantitative PCR (qPCR) at 48 and 192 h post infection (hpi). Light microscopy observations demonstrated E. zuernii sporozoite invasion as early as 24 hpi, while confocal laser scanning microscopy revealed early meront formation by 48 hpi. Gene copy numbers displayed variations in parasite copy numbers directly after infection and over the observation period over 192 h. Based on these findings, this assay is suitable for detecting E. zuernii gene copies in MDBK cells over an experimental period of 192 h. Though total gene copy numbers did not increase over time, we conclude that this assay is a suitable for sustaining the growth and development of E. zuernii stages in vitro. This testing system will allow for further investigations of bovine Eimeria while reducing the use of animal experiments.