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Bumblebees are key pollinators with gut microbiotas that support host health. After bumblebee queens undergo winter diapause, which occurs before spring colony establishment, their gut microbiotas are disturbed, but little is known about community dynamics during diapause itself. Queen gut microbiotas also help seed worker microbiotas, so it is important that they recover post‐diapause to a typical community structure, a process that may be impeded by pesticide exposure. We examined how bumblebee queen gut microbiota community structure and metabolic potential shift during and after winter diapause, and whether post‐diapause recovery is affected by pesticide exposure. To do so, we placed commercial Bombus impatiens queens into diapause, euthanizing them at 0, 2 and 4 months of diapause. Additionally, we allowed some queens to recover from diapause for 1 week before euthanasia, exposing half to the common herbicide glyphosate. Using whole‐community, shotgun metagenomic sequencing, we found that core bee gut phylotypes dominated queen gut microbiotas before, during and after diapause, but that two phylotypes, Schmidhempelia and Snodgrassella, ceased to be detected during late diapause and recovery. Despite fluctuations in taxonomic community structure, metabolic potential remained constant through diapause and recovery. Also, glyphosate exposure did not affect post‐diapause microbiota recovery. However, metagenomic assembly quality and our ability to detect microbial taxa and metabolic pathways declined alongside microbial abundance, which was substantially reduced during diapause. Our study offers new insights into how bumblebee queen gut microbiotas change taxonomically and functionally during a key life stage and provides guidance for future microbiota studies in diapausing bumblebees. [ABSTRACT FROM AUTHOR]

Small mammals use day length to adjust morphology and physiology to anticipate seasonal changes in environmental conditions. The canonical photoperiod-mediated annual adaptation is seasonal breeding. However, increasing evidence suggests that day-length information can induce plasticity in the nervous system, and thus provoke behavioral plasticity that can aid in winter survival. We hypothesized that low temperatures and reduced food availability in the winter would necessitate the evolution of increased pain tolerance mediated by short day lengths. Siberian hamsters (Phodopus sungorus (Pallas, 1773)) housed in short days regressed their reproductive tracts and molted to winter pelage. Short- day hamsters also displayed elevated latencies of nociceptive responses in the hot-plate test, suggesting reduced pain responsivity. Prior to assessing potential neuronal or neuroendocrine mediators of altered pain responses, however, we investigated the possibility that changes in fur characteristics mediated photoperiod differences in pain responsivity. Removal of fur with a depilatory cream eliminated photoperiod differences in pain responsivity. Taken together, these data indicate that day length regulates thermal pain responses via changes in fur properties; also, changes in pelage properties have both thermoregulatory and thermal insulatory properties. Les petits mammiferes utilisent la longueur du jour afin d'ajuster leur morphologie et leur physiologie en anticipation des changements saisonniers des conditions du milieu. L'adaptation saisonniere par excellence controlee par la photoperiode est la reproduction annuelle. Cependant, des indications de plus en plus nombreuses laissent croire que les informations sur la longueur du jour peuvent induire une plasticite du systeme nerveux et provoquer ainsi une plasticite comportementale qui peut favoriser la survie a l'hiver. Nous avancons l'hypothese selon laquelle les basses temperatures et la disponibilite reduite de la nourriture en hiver requierent l'evolution d'une tolerance accrue a la douleur sous l'influence des courtes photoperiodes. Des hamsters nains de Dzoungarie (Phodopus sungorus (Pallas, 1773)) gardes dans des conditions de jours courts subissent une regression de leurs voies reproductrices et acquierent par mue leur pelage d'hiver. Les hamsters gardes en jours courts affichent aussi des latences elevees des reactions nociceptives dans le test de sensibilite a la chaleur, ce qui laisse croire a une reactivite reduite a la douleur. Cependant, avant d'evaluer les mediateurs neuronaux ou endocriniens potentiels de ces reactions modifiees a la douleur, nous avons etudie la possibilite que les changements dans les caracteristiques de la fourrure soient responsables des differences de reactivite a la douleur reliees a la photoperiode. Le retrait de la fourrure avec une creme epilatoire elimine les differences de reactivite a la douleur reliees a la photoperiode. Dans leur ensemble, ces donnees indiquent que la photoperiode controle les reactions a la douleur thermique par le biais de changements dans les proprietes de la fourrure; de plus, les changements dans les caracteristiques du pelage ont des proprietes de thermoregulation et d'isolement thermique. [Traduit par la Redaction], Introduction Most animals living outside of the tropics experience significant yet predictable annual fluctuations in environmental conditions, including ambient temperature, food and water availability, and predation pressures (Bronson 1985, 1989). [...]

Adverse neurodevelopmental consequences remain a primary concern when evaluating the effects of thyroid hormone (TH) disrupting chemicals. Though the developing brain is a known target of TH insufficiency, the relationship between THs in the serum and the central nervous system is not well characterized. To address this issue, dose response experiments were performed in pregnant rats using the goitrogen propylthiouracil (PTU) (dose range 0.1–10 ppm). THs were quantified in the serum and brain of offspring at gestational day 20 (GD20) and postnatal day 14 (PN14), two developmental stages included in OECD and EPA regulatory guideline/guidance studies. From the dose response data, the quantitative relationships between THs in the serum and brain were determined. Next, targeted gene expression analyses were performed in the fetal and neonatal cortex to test the hypothesis that TH action in the developing brain is linked to changes in TH concentrations within the tissue. Results show a significant reduction of T4/T3 in the serum and brain of the GD20 fetus in response to low doses of PTU; interestingly, very few genes were significantly different at any dose tested. In the PN14 pup significant reductions of T4/T3 in the serum and brain were also detected; however, twelve transcriptional targets were identified in the neonatal cortex that correlated well with reduced brain THs. These results show that serum T4 is a good predictor of brain THs, and offer several target genes that could serve as pragmatic readouts of T4/T3 dysfunction within the PN14 cortex. [ABSTRACT FROM AUTHOR]