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An extensive literature shows that astrocytes exhibit metabotropic glutamate receptor 5 (mGluR5)—dependent increases in cytosolic calcium ions (Ca 2+ ) in response to glutamatergic transmission and, in turn, modulate neuronal activity by their Ca 2+ -dependent release of gliotransmitters. These findings, based on studies of young rodents, have led to the concept of the tripartite synapse, in which astrocytes actively participate in neurotransmission. Using genomic analysis, immunoelectron microscopy, and two-photon microscopy of astrocytic Ca 2+ signaling in vivo, we found that astrocytic expression of mGluR5 is developmentally regulated and is undetectable after postnatal week 3. In contrast, mGluR3, whose activation inhibits adenylate cyclase but not calcium signaling, was expressed in astrocytes at all developmental stages. Neuroglial signaling in the adult brain may therefore occur in a manner fundamentally distinct from that exhibited during development.

In fluctuating environments, mothers may enhance the fitness of their offspring by adjusting offspring phenotypes to match the environment they will experience at independence. In free-ranging red squirrels, natural selection on offspring postnatal growth rates varies according to population density, with selection favoring faster-growing offspring under high-density conditions. We show that exposing mothers to high-density cues, accomplished via playbacks of territorial vocalizations, led to increased offspring growth rates in the absence of additional food resources. Experimental elevation of actual and perceived density induced higher maternal glucocorticoid levels, and females with naturally or experimentally increased glucocorticoids produced offspring that grew faster than controls. Therefore, social cues reflecting population density were sufficient to elicit increased offspring growth through an adaptive hormone-mediated maternal effect.

Evaluating methods used to capture and mark neonates is necessary for ensuring research methods are ethical, follow best practices, and do not have long‐term unintended impacts on neonates or populations. We used a quasi‐experimental approach (reference versus treatment) to determine whether visiting wolf dens and marking wolf Canis lupus pups affects important wolf population metrics. Specifically, we examined whether pup recruitment and pack size differed between packs where we visited dens and handled pups (‘disturbed packs' = treatment group) and those where we did not visit dens (‘undisturbed packs' = reference group). During 2019–2023, we studied 43 wolf packs and litters, 19 of which were disturbed packs and 24 of which were undisturbed. We found no difference in recruitment or pack size between disturbed and undisturbed wolf packs. However, we did observe substantial annual variation in recruitment and pack size, which indicated that other ecological factors (e.g. prey abundance) were likely responsible for annual changes in recruitment and pack size. Our findings are consistent with several other studies, and together this research indicates that wolf dens can be visited once and wolf pups handled briefly for research purposes without having a measurable effect on recruitment and pack size.

Background The CRISPR/Cas9 system is increasingly used for gene inactivation in mouse zygotes, but homology-directed mutagenesis and use of inbred embryos are less established. In particular, Rosa26 knock-in alleles for the insertion of transgenes in a genomic ‘safe harbor’ site, have not been produced. Here we applied CRISPR/Cas9 for the knock-in of 8–11 kb inserts into Rosa26 of C57BL/6 zygotes. Results We found that 10–20 % of live pups derived from microinjected zygotes were founder mutants, without apparent off-target effects, and up to 50 % knock-in embryos were recovered upon coinjection of Cas9 mRNA and protein. Using this approach, we established a new mouse line for the Cre/loxP-dependent expression of Cas9. Conclusions Altogether, our protocols and resources support the fast and direct generation of new Rosa26 knock-in alleles and of Cas9-mediated in vivo gene editing in the widely used C57BL/6 inbred strain.

The neuropeptide arginine vasopressin (AVP) is arguably among the most potent regulators of social behaviors in mammals identified to date. However, only the related neuropeptide oxytocin (OXT) has been shown to promote maternal behavior. Here, we assess the role of AVP in maternal care, in particular in arched back nursing, pup retrieval, and pup contact by using complementary pharmacological and genetic approaches. Also, experiments were performed in rat dams with differences in trait anxiety, i.e., rats bred for either high (HAB) or low (LAB) anxiety-related behavior as well as nonselected (NAB) dams. Viral vector-mediated up-regulation of AVP V1a receptors (AVP-Rs) within the medial preoptic area of lactating NAB rats and chronic central AVP treatment of NAB and LAB dams improved, whereas local blockade of AVP-R expression by means of antisense oligodeoxynucleotides or central AVP-R antagonism impaired, maternal care in NAB dams. Also, in HAB rats with a genetically determined elevated brain AVP activity, intrinsically high levels of maternal care were reversed by blockade of AVP-R actions. Treatment-induced impairment of AVP-mediated maternal behavior increased adult emotionality and impaired social interactions in male offspring of NAB dams. These findings provide direct evidence for an essential and highly potent role of brain AVP in promoting maternal behavior, which seems to be independent of the dam's trait anxiety.

Breeding systems in which group members help to raise the offspring of co‐members are associated with arid, unpredictable environments. Cooperative rearing may mitigate the effects of adverse environmental conditions on pup growth and survival. However, few studies have explored the relationship between environmental variation and breeding success, and the role of helpers. Here, we show that reductions in the growth and survival of meerkat (Suricata suricatta) pups have been associated with increases in daily maximum air temperatures (Tmax) in the southern Kalahari over the last 20 years. On days when Tmax was high, meerkat pups gained less body mass than on cooler days. Reductions in the diurnal body mass gain (ΔMb) of pups on hotter days were not a consequence of reductions in the frequency with which pups were fed by adults as feeding rate increased with Tmax, suggesting that the reductions in ΔMb by pups on hot days reflected a decrease in water content of the food items or an increased water and energy cost of thermoregulation. Reductions in pup ΔMb on hot days were smaller in larger groups, in which helper‐to‐pup ratios were relatively high. As increases in air temperature are predicted with climate change, further reductions in meerkat pup growth and survival seem inevitable. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.

This study investigated the effects of a maternal dyslipidaemic (DLP) diet on lipid metabolism, microbial counts in faeces and hepatic and intestinal morphology in rat offspring with respect to sex during different phases of life. Wistar rats (dams) were fed a control (CTL) or DLP during gestation and lactation. After weaning, CTL and DLP offspring were fed a standard diet. The effects of a maternal DLP on body composition, biochemical parameters, faecal microbiota and intestinal and hepatic histomorphometric characteristics in rat offspring were evaluated at 30 and 90 d of age. The DLP diet during gestation and lactation caused lower birth weight and a greater weight gain percentage at the end of the 90-d period in both male and female offspring. Female pups from DLP dams had higher liver fat levels compared with CTL (P≤0·001) at 90 d of age. Males from DLP dams had greater visceral fat weight and lower Lactobacillus spp. faecal counts at 90 d of age (P≤0·001) as well as lower faecal fat excretion (P≤0·05) and Bacteroides spp. faecal counts (P≤0·001) at 30 d of age when compared with pups from CTL dams. However, both dams and DLP pups showed damage to intestinal villi. A maternal DLP alters intestinal function and lipid metabolism in a sex-specific manner and is a potential predisposing factor for health complications in offspring from the juvenile period to the adult period.

Sialic acids (Sia) are postulated to improve cognitive abilities. This study evaluated Sia effects on rat behavior when administered in a free form as N-acetylneuraminic acid (Neu5Ac) or conjugated as 6′-sialyllactose (6′-SL). Rat milk contains Sia, which peaks at Postnatal Day 9 and drops to a minimum by Day 15. To bypass this Sia peak, a cohort of foster mothers was used to raise the experimental pups. A group of pups received a daily oral supplementation of Neu5Ac to mimic the amount naturally present in rat milk, and another group received the same molar amount of Sia as 6′-SL. The control group received water. After weaning, rats were submitted to behavioral evaluation. One year later, behavior was re-evaluated, and in vivo long-term potentiation (LTP) was performed. Brain samples were collected and analyzed at both ages. Adult rats who received Sia performed significantly better in the behavioral assessment and showed an enhanced LTP compared to controls. Within Sia groups, 6′-SL rats showed better scores in some cognitive outcomes compared to Neu5Ac rats. At weaning, an effect on polysialylated-neural cell adhesion molecule (PSA-NCAM) levels in the frontal cortex was only observed in 6′-SL fed rats. Providing Sia during lactation, especially as 6′-SL, improves memory and LTP in adult rats.

1. Climate change imposes an urgent need to recognise and conserve the species likely to be worst affected. However, while ecologists have mostly explored indirect effects of rising ambient temperatures on temperate and polar species, physiologists have predicted direct impacts on tropical species. 2. The African wild dog (Lycaon pictus), a tropical species, exhibits few of the traits typically used to predict climate change vulnerability. Nevertheless, we predicted that wild dog populations might be sensitive to weather conditions, because the species shows strongly seasonal reproduction across most of its geographical range. 3. We explored associations between weather conditions, reproductive costs, and reproductive success, drawing on long-term wild dog monitoring data from sites in Botswana (20°S, 24 years), Kenya (0°N, 12 years), and Zimbabwe (20°S, 6 years). 4. High ambient temperatures were associated with reduced foraging time, especially during the energetically costly pup-rearing period. Across all three sites, packs which reared pups at high ambient temperatures produced fewer recruits than did those rearing pups in cooler weather; at the non-seasonal Kenya site such packs also had longer inter-birth intervals. Over time, rising ambient temperatures at the (longest-monitored) Botswana site coincided with falling wild dog recruitment. 5. Our findings suggest a direct impact of high ambient temperatures on African wild dog demography, indicating that this species, which is already globally endangered, may be highly vulnerable to climate change. This vulnerability would have been missed by simplistic trait-based assessments, highlighting the limitations of such assessments. Seasonal reproduction, which is less common at low latitudes than at higher latitudes, might be a useful indicator of climate change vulnerability among tropical species.