Mobile Monkeys and Modified Microbes: Medical Experimentation between Metropolitan and Colonial Laboratories, 1880-ca. 1925.

Following the medical breakthroughs of Pasteur and Koch after 1880, the use of simians became pivotal to laboratory research to develop vaccines and cultivate microbes through the technique of serial passage. These innovations fueled research on multiple diseases and unleashed a demand for simians, which died easily in captivity. European and American colonial expansion facilitated a burgeoning market for laboratory animals that intensified hunting for live animals. This demand created novel opportunities for disease transfers and viral recombinations as simians of different species were confined in precarious settings. As laboratories moved into the colonies for research into a variety of diseases, notably syphilis, sleeping sickness, and malaria, the simian market was intensified. While researchers expected that colonial laboratories offered more natural environments than their metropolitan affiliates, amassing apes, people, microbes, and insects at close quarters instead created unnatural conditions that may have facilitated the spread of undetectable diseases.

Microbe transmission from pet shop to lab-reared zebrafish reveals a pathogenic birnavirus.

Zebrafish are popular research organisms selected for laboratory use due in part to widespread availability from the pet trade. Many contemporary colonies of laboratory zebrafish are maintained in aquaculture facilities that monitor and aim to curb infections that can negatively affect colony health and confound experiments. The impact of laboratory control on the microbial constituents associated with zebrafish in research environments compared to the pet trade are unclear. Diseases of unknown causes are common in both environments. We conducted a metatranscriptomic survey to broadly compare the zebrafish-associated microbes in pet trade and laboratory environments. We detected many microbes in animals from the pet trade that were not found in laboratory animals. Cohousing experiments revealed several transmissible microbes including a newly described non-enveloped, double-stranded RNA virus in the Birnaviridae family we name Rocky Mountain birnavirus (RMBV). Infections were detected in asymptomatic animals from the pet trade, but when transmitted to laboratory animals RMBV was associated with pronounced antiviral responses and hemorrhagic disease. These experiments highlight the pet trade as a distinct source of diverse microbes that associate with zebrafish and establish a paradigm for the discovery of newly described pathogenic viruses and other infectious microbes that can be developed for study in the laboratory.

Comparison of the exploratory behaviour of wild and laboratory mouse species.

In this study, we compared the exploratory behaviour of mound-building mice (Mus spicilegus) and house mice (Mus musculus) with domesticated laboratory mouse strains (BALB/c and C57BL/6). The animals spent 15 minutes in the furnished test box before the exit to the outside world became free. During the 5-minute test, it was noted whether the animal left the familiar environment; if it did, it was recorded in how many seconds. Based on our results, the wild mouse species were more likely to leave the familiar mouse box and explore the outside environment earlier than the laboratory mice. We also found a difference within the wild mouse species, the mound-building mouse being the one that explored the external environment to a greater extent and faster. The effect of domestication manifests in the fact that laboratory mouse strains are less likely to leave their familiar environment and are significantly less active than their wild ancestors.

Optimizing environmental enrichment for Sprague Dawley rats: Exemplary insights into the liver proteome.

BACKGROUND: Considering the expected increase in the elderly population and the growing emphasis on aging-related biomedical research, the demand for aged laboratory animals has surged, challenging established husbandry practices. Our objective was to establish a cost-effective method for environmental enrichment, utilizing the liver as a representative organ to assess potential metabolic changes in response to differing enrichment levels. METHODS: We conducted a six-month study involving 24 male Sprague Dawley rats, randomly assigned to four environmental enrichment groups. Two groups were housed in standard cages, while the others were placed in modified rabbit cages. Half of the groups received weekly playtime in an activity focused rat housing unit. We evaluated hormone levels, playtime behavior, and subjective handling experience. Additionally, liver tissue proteomic analysis was performed. RESULTS: Initial corticosterone levels and those after 3 and 6 months showed no significant differences. Yet, testosterone levels were lower in the control group by the end of the study (p = 0.007). We observed 1871 distinct proteins in liver tissue, with 77% being common across groups. In gene ontology analysis, no specific pathways were overexpressed. In semiquantitative analysis, we observed differences in proteins associated in lipid metabolism such as Apolipoprotein A-I and Acyl-CoA 6-desaturase, which were lower in the control group (p = 0.024 and p = 0.009). Rats in the intervention groups with weekly playtime displayed the least amount of reported distress during inspection or upon room entry and were less prone to accepting treats. Removing animals from their enclosure was most effortless for those in the large cage group. Over time, there was a decrease in conflicts among rats that interacted only twice weekly during playpen time. DISCUSSION: In summary, refining husbandry practices for aging rats is both simple and budget-friendly, with no apparent adverse effects on stress levels, animal development, or relevant metabolic changes in the liver.

Quantitative morphological analysis of age structural changes in prostate of experimental animals with ethanol poisoning.

OBJECTIVE: Aim: To find out the age remodeling of the structural components of the prostate gland at alcohol poisoning using quantitative morphological analysis. PATIENTS AND METHODS: Materials and Methods: The structure of the prostate gland of 4 white male rats groups were morphologically investigated. The 1 group included 30 control intact animals aged 8 months, the 2-nd group - 30 rats aged 24 months, the 3-rd group - 30 8-month-old animals with ethanol intoxication, and the 4-th group included 30 24-month-old rats with the specified simulated pathology. Ethanol intoxication was modeled by intragastric administration of 30% ethyl alcohol solution at a dose of 20 ml/kg once daily for 28 days. Rats were euthanized by bloodletting under general thiopental anesthesia 28 days after the beginning of the experiment. The area of glands, the height of glandular epithelial cells, the area of their nuclei and cytoplasm, the nuclear-cytoplasmic ratio in these cells and the stromal-parenchymal ratio in the organ were studied using light microscopy and were determined morphometrically. Morphometric parameters were processed statistically. RESULTS: Results: It was established that with age in the intact prostate of laboratory sexually mature white male rats, the area of glands, the height of glandular epitheliocytes, the area of their nuclei and cytoplasm, with the stability of nuclear-cytoplasmic ratios in the epithelial cells of the glands, significantly decreases, and the stromal-parenchymal ratio in the organ under study increases. Long-term ethanol poisoning leads to pronounced structural changes in the prostate, which is characterized by pronounced atrophy of the glandular epithelium, a decrease in the area of the glands, a decrease in the height of epithelial cells, a violation of nuclear-cytoplasmic relations in them, an increase in stromal-parenchymal ratio, and a prominent growth of the muscle-elastic stroma. The revealed structural changes of the studied components of the prostate dominated in 24-month-old experimental animals. CONCLUSION: Conclusions: Morphological analysis of the prostate gland established that morphometric and morphological changed significantly according to the age and were depend on the ethanol poisoning.

Microstructure of the corneal endothelial transition zone in different laboratory animals.

Purpose: To compare the microstructure of the corneal endothelial transition zone in different laboratory animals. Methods: Flat-mount corneas of rabbits, rats, and mice were stained with Alizarin Red S (ARS) and observed using scanning electron microscopy (SEM). The progenitor cell markers p75 neurotrophin receptor (p75NTR), SRY-box transcription factor 9 (SOX9), leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5), telomerase reverse transcriptase (TERT), and proliferation marker Ki-67 were examined in the flat-mounted corneas of three laboratory animals using immunofluorescence microscopy. Results: On flat mounts, proximity to the trabecular meshwork correlated with weaker ARS staining and greater polymorphism of endothelial cells in the transition zone in all animals. On SEM, distinct and smooth structures of the transition zone were negligibly detected in all animals. The endothelial cells in the transition zone had irregular shapes, with less dense, less wavy intercellular junctions, especially in murine corneas, exhibiting unique intercellular cystic spaces. In the transition zone of the rabbit cornea, progenitor cell markers p75NTR, SOX9, Lgr5, TERT, and proliferation marker Ki-67 were expressed, in contrast to those in other murine corneas. Conclusions: Although the transition zone was not identified clearly, irregular cell morphology and loss of cell-cell contact were observed in all animal corneal endothelial cells. The proliferative capacity and the presence of progenitor cells were confirmed in the transition zone, especially in the rabbit cornea.

Effects of Different Tank Sizes on Laboratory Rare Minnow (Gobiocypris rarus)-Under the Same Density.

Laboratory fish play an important role in many research fields, and they are also raised and bred in many laboratories around the world. While many studies have suggested suitable feeding densities for various laboratory fish, significant variations exist in the sizes of rearing tanks across different laboratories. Moreover, there is limited research on the effects of different rearing tank sizes. In this study, we set up the same rearing density (one liter of water corresponding to two fishes) and four treatments with different tank sizes (5 L, 10 L, 15 L, 20 L). We found that different sizes of rearing tanks had no significant effect on the growth and shoaling of laboratory rare minnow. However, the rare minnow in 10 L tank had lower cortisol levels, while the rare minnow in 20 L tank had higher levels of dopamine (DA), serotonin (5-HT) and their metabolites (DOPAC and 5-HIAA). These results show that even under the same rearing density, different sizes of rearing tanks will still have a physiological effect on the rare minnow, and the tank size suitable for laboratory fish should be considered.

Impact of enriched environment on motor performance and learning in mice.

Neuroscience heavily relies on animal welfare in laboratory rodents as it can significantly affect brain development, cognitive function and memory formation. Unfortunately, laboratory animals are often raised in artificial environments devoid of physical and social stimuli, potentially leading to biased outcomes in behavioural assays. To assess this effect, we examined the impact of social and physical cage enrichment on various forms of motor coordination. Our findings indicate that while enriched-housed animals did not exhibit faster learning in eyeblink conditioning, the peak timing of their conditioned responses was slightly, but significantly, improved. Additionally, enriched-housed animals outperformed animals that were housed in standard conditions in the accelerating rotarod and ErasmusLadder test. In contrast, we found no significant effect of enrichment on the balance beam and grip strength test. Overall, our data suggest that an enriched environment can improve motor performance and motor learning under challenging and/or novel circumstances, possibly reflecting an altered state of anxiety.

Training Laboratory Rabbits to Refine Routine Husbandry Procedures.

Non-aversive handling and training techniques for laboratory animals are required to facilitate experimental and routine husbandry procedures, improving both animal welfare and scientific quality. Clicker training was utilized to develop training protocols for rabbits to refine stressful routine husbandry procedures usually associated with lifting (i.e., being picked up from the floor)/restraining (i.e., being held in the arms of a human) them. Thirteen female New Zealand White rabbits were trained over three weeks. All rabbits learned the predefined goal behaviors: they followed the target stick, jumped onto the weighing scale, entered a transport box, and reared while placing their front paws onto the trainer's hand. In addition, ten animals jumped from the floor onto the sitting trainer's lap and allowed the trainer to lift their paws off the surface while sitting on the trainer's lap. For some individuals, the protocols had to be adapted by additional interim steps. At the end of the training, the rabbits reliably showed the expected goal behaviors, even after short and long training breaks. With few exceptions, a familiar person other than the trainer could elicit the goal behaviors from the rabbits (generalization), though further sessions were required for generalization. In the voluntary approach test, the rabbits preferred interacting with the trainer in the 1st trial but spent as much time with an unfamiliar person as with the trainer in the 2nd trial. The behavioral observations suggested that picking the rabbits up with the transport box, as described in the protocol, instead of restraining them with the scruff of their neck and lifting them on the arm, was less aversive. All in all, the training protocols were feasible and can serve as a refinement strategy in laboratory animal facilities. In the interest of animal welfare, the training protocols should be applied wherever possible.

Recommendations for measuring and standardizing light for laboratory mammals to improve welfare and reproducibility in animal research.

Light enables vision and exerts widespread effects on physiology and behavior, including regulating circadian rhythms, sleep, hormone synthesis, affective state, and cognitive processes. Appropriate lighting in animal facilities may support welfare and ensure that animals enter experiments in an appropriate physiological and behavioral state. Furthermore, proper consideration of light during experimentation is important both when it is explicitly employed as an independent variable and as a general feature of the environment. This Consensus View discusses metrics to use for the quantification of light appropriate for nonhuman mammals and their application to improve animal welfare and the quality of animal research. It provides methods for measuring these metrics, practical guidance for their implementation in husbandry and experimentation, and quantitative guidance on appropriate light exposure for laboratory mammals. The guidance provided has the potential to improve data quality and contribute to reduction and refinement, helping to ensure more ethical animal use.

Making sense of the costs of adversity throughout the lifespan on aging in humans and other animals.

Social adversity, particularly early in life, can cause lifelong damage to health; by now, numerous studies examine this relationship in non-human species, producing some important themes: A) Captive animals readily lack ethological validity, giving a special place to studies of natural populations; one must appreciate though, that animal studies typically benefit humans who themselves lack ecological validity, namely Westernized subjects. B) Animal studies of the links between social adversity and psychiatric maladies potentially produce anthropomorphism; however, long-term study of our closest relatives demonstrates how convincingly another primate can, for example, experience grief, rather than display "grief-like" behavior. C) Are long-term consequences of social adversity best viewed as maladaptive and pathological, or as adaptive preparation for similar adversity later in life?; the growing literature casts light on when adversity's consequences are the purview of medicine or natural history. D) Studies examining sustained adversity and aging can increasingly distinguish between aging versus diseases of aging or cohort effects, and between aging effects arising from direct physiological mechanisms or indirect behavioral ones.

Differential effects of four laboratory animal control diets on gut microbiota in mice.

BACKGROUND: The gut microbiota is intricate and susceptible to multiple factors, with diet being a major contributor. The present study aimed to investigate the impact of four commonly used laboratory animal control diets, namely Keao Xieli's maintenance diet (KX), HFK's 1025 (HF), Research Diets' D12450B (RD), and Lab Diet's 5CC4 (LD), on the gut microbiota of mice. RESULTS: A total of 40 mice were randomly assigned to four groups, and each group was fed one of the four diets for a duration of 8 weeks. The assessment of gut microbiota was conducted using 16S rRNA sequencing both at the beginning of the study (week 0) and the end (week 8), which served as the baseline and endpoint samples, respectively. Following the 8-week feeding period, no significant differences were observed in physiological parameters, including body weight, visceral weight, and blood biochemical indices, across the four groups. Nonetheless, relative to the baseline, discernible alterations in the gut microbiota were observed in all groups, encompassing shifts in beta-diversity, hierarchical clustering, and key genera. Among the four diets, HF diet exhibited a significant influence on alpha-diversity, RD diet brought about notable changes in microbial composition at the phylum level, and LD diet demonstrated an interconnected co-occurrence network. Mantel analysis indicated no significant correlation between physiological parameters and gut microbiota in the four groups. CONCLUSION: Overall, our study demonstrated that the four control diets had a minimal impact on physiological parameters, while exerting a distinct influence on the gut microbiota after 8 weeks. © 2024 Society of Chemical Industry.

Immunoinformatics-guided recombinant polypeptide-based enzyme-linked immunosorbent assay for seromonitoring of laboratory animals for minute virus of mice and Kilham rat virus.

Subclinical infection of laboratory animals with one or more of several pathogens affects the results of experiments on animals. Monitoring the health of laboratory animals encompasses routine surveillance for pathogens, including several viruses. This study aimed to explore the development of an alternative assay to the existing ones for detecting infection of mice and rats with the parvoviruses minute virus of mice (MVM) and Kilham rat virus (KRV), respectively. Full-length VP2 and NS1 proteins of these parvoviruses, besides fragments containing multiple predicted epitopes stitched together, were studied for serological detection. The optimal dilution of full-length proteins and antigenic regions containing predicted epitopes for coating, test sera, and conjugate was determined using a checkerboard titration at each step. The assays were evaluated vis-à-vis commercially available ELISA kits. The results showed that an engineered fusion of fragments containing multiple predicted MVM VP2 and NS1 epitopes was better than either of the full-length proteins for detecting antibodies in 90% of the tested sera samples. For KRV ELISA, full-length VP2 was better compared to other individual recombinant protein fragments or combinations thereof for the detection of antibodies in sera. This report is the first description of an ELISA for KRV and an improved assay for MVM. Importantly, our assays could be exploited with small volumes of sera. The results also demonstrate the utility of immunoinformatics-driven polypeptide engineering in the development of diagnostic assays and the potential to develop better tests for monitoring the health status of laboratory animals.

Evaluation of Vibration as an Extrinsic Variable in In Vivo Research.

Vibration is inherent in research animal facilities due to the mechanical systems and practices required for animal care and use. Ample evidence indicates that vibration can change behavior and physiology in multiple species, potentially altering the results of research studies. Although one cannot eliminate environmental vibration, its control is important in research animal environments to decrease the possibility of introducing a research variable due to vibration effects. To assess the potential for a vibration source to alter experimental results and variability, one must understand the principles of vibration, its likely sources, and control methods. The literature regarding the effects of vibration, as it applies in a practical sense, can be challenging to interpret because the vibration frequencies tested to date have often not been within or near the most sensitive ranges of the species being tested. Some previous studies have used unrealistic vibration magnitudes and provided insufficient detail to duplicate or build upon conclusions. Standardization is essential for research examining the effects of vibration on animals to validate knowledge of this extrinsic variable in animal research and identify ways to mitigate the variable in research facilities.

Light: An Extrinsic Factor Influencing Animal-based Research.

Light is an environmental factor that is extrinsic to animals themselves and that exerts a profound influence on the regulation of circadian, neurohormonal, metabolic, and neurobehavioral systems of all animals, including research animals. These widespread biologic effects of light are mediated by distinct photoreceptors-rods and cones that comprise the conventional visual system and melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) of the nonvisual system that interact with the rods and cones. The rods and cones of the visual system, along with the ipRGCs of the nonvisual system, are species distinct in terms of opsins and opsin concentrations and interact with one another to provide vision and regulate circadian rhythms of neurohormonal and neurobehavioral responses to light. Here, we review a brief history of lighting technologies, the nature of light and circadian rhythms, our present understanding of mammalian photoreception, and current industry practices and standards. We also consider the implications of light for vivarium measurement, production, and technological application and provide simple recommendations on artificial lighting for use by regulatory authorities, lighting manufacturers, designers, engineers, researchers, and research animal care staff that ensure best practices for optimizing animal health and well-being and, ultimately, improving scientific outcomes.