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The study reveals that raising mice at 22 °C boosts gut transit speed by two times compared to 30 °C, primarily due to stress signals from the hypothalamic–pituitary–adrenal axis and an increase of corticotropin-releasing hormone.
Researchers have developed a cost-effective, noninvasive method for determining torpor-bout duration in heterothermic mammals. They used the paper towel shredding behavior of ground squirrels to detect 59 arousals with 100% accuracy over 52 days. This method avoids the drawbacks of other cheap monitoring systems such as the sawdust technique.
The authors defined rat microbial biogeography by re-analyzing publicly available RNA sequencing data from 11 organs of juvenile, adolescent, adult and aged Fisher 344 rats.
The study introduces an open-source, customizable 3D printable design for rodent conditioning for magnetic resonance imaging and other imaging modalities. The design is easy to use and can be applied to both anesthetized and awake mice, and anesthetized rats.
Poor replicability in animal research can be a result of low external validity driven by rigorous standardization of study populations. This study investigates how heterogenization of study populations by using mice from different breeding sites might affect the replicability of animal studies conducted in a single facility. The findings suggest that heterogenization by breeding site has limited capacity to improve replicability in animal research.
Environmental enrichment is a home-based intervention that mimics natural habitats for laboratory-housed animals. This systematic review of 27 environmental enrichment protocols finds consistent benefits for zebrafish welfare while raising the importance of a standardizing protocol to improve reproducibility of results.
The authors used a gene-editing approach to generate a C57BL/6J mouse model expressing the CD45.1 epitope. The model, which overcomes some of the issues reported with the congenic mouse B6.SJL, could be useful for adoptive cell transfer experiments.
The authors present a simultaneous PET/MR dataset of 20 Macaca fascicularis images structured according to the Brain Imaging Data Structure standards. The PREMISE database is stored and available through the PRIME-DE consortium repository.
The authors show that VAR2CSA-based placental malaria vaccine candidates induce similar responses in Aotus nancymaae monkeys as those reported in humans; these findings suggest that the Aotus model is suitable for preclinical downselection of placental malaria vaccine candidates.
The authors used liquid chromatography–mass spectrometry to compare the metabolic profile of non-fasted and fasted plasma samples in the Nile rat model of type 2 diabetes. Metabolite measurements in non-fasted samples were more reproducible than in fasted samples, supporting the use of non-fasted plasma metabolomics to study glucose tolerance in Nile rats during diabetes progression.
Unpredictable chronic stress (UCS) increases anxiety/fear-related behavior and cortisol levels while decreasing locomotor performance, according to a systematic analysis of 38 studies on UCS in zebrafish. To further assess the effects of UCS on zebrafish behavior, future well-designed trials are required.
Two Cre-dependent reporter mice, oFluc and Akaluc, were created and tested for bioluminescence in neural tissues and organs. Both strains were brighter than the classical luciferase Luc2, potentially facilitating in vivo bioluminescence imaging of various tissues.
The authors developed an R package that enables the estimation of group size required for mouse breeding, taking into account Mendelian genetics, fertility and litter size.
This protocol describes a humanized mouse model created using neonatal thymus and umbilical cord blood hematopoietic stem cells as nonfetal human tissue sources.
The authors investigated the influence of housing density and bedding volume on ammonia build-up in two individually ventilated mouse cages models. While the amount of bedding had no influence on ammonia levels, smaller Type II individually ventilated cages accumulated higher ammonia levels than larger Type III individually ventilated cages, even at similar housing densities.
A mouse model to study norovirus pathogenesis is described. The murine norovirus strain WU23, originally isolated from an intestinal site, induces severe but self-resolving diarrhea in neonates, reflecting the pathology observed during human norovirus infection.
Tomsits and colleagues investigated the effects of medetomidine/midazolam/fentanyl and isoflurane/fentanyl narcosis on murine cardiac autonomic nervous activity and electrophysiology. The results show that, compared with medetomidine/midazolam/fentanyl narcosis, isoflurane/fentanyl narcosis seems to have no effect on cardiac autonomic nervous function and less influence on cardiac electrophysiology.
A large number of refinements have been studied with the aim to improve rat welfare, but more evidence is needed to fully understand their impact. This mapping review draws on the findings of 1,017 studies to show that different refinements impact different rats in different ways, and that a ‘one-size-fits-all’ approach to refinements might not be appropriate.
Using behavioral assays, transcriptome analysis and viral approaches to manipulate gene expression in the mPFC, Zhang et al. identified an important role for early growth response 2 (Egr2/Krox-20) in the development of social and cooperative behaviors in mice.
A clinically relevant murine model of septic arthritis via direct inoculation of methicillin-resistant Staphylococcus aureus into the knee joint is described. This protocol details methods for serum, synovial fluid and knee joint tissue analysis that more closely mimic the workup of septic arthritis in human patients.