Effects of domestication on the gut microbiota parallel those of human industrialization.

Domesticated animals experienced profound changes in diet, environment, and social interactions that likely shaped their gut microbiota and were potentially analogous to ecological changes experienced by humans during industrialization. Comparing the gut microbiota of wild and domesticated mammals plus chimpanzees and humans, we found a strong signal of domestication in overall gut microbial community composition and similar changes in composition with domestication and industrialization. Reciprocal diet switches within mouse and canid dyads demonstrated the critical role of diet in shaping the domesticated gut microbiota. Notably, we succeeded in recovering wild-like microbiota in domesticated mice through experimental colonization. Although fundamentally different processes, we conclude that domestication and industrialization have impacted the gut microbiota in related ways, likely through shared ecological change. Our findings highlight the utility, and limitations, of domesticated animal models for human research and the importance of studying wild animals and non-industrialized humans for interrogating signals of host-microbial coevolution.

Living inside our gastrointestinal tracts is a large and diverse community of bacteria called the gut microbiota that plays an active role in basic body processes like metabolism and immunity. Much of our current understanding of the gut microbiota has come from laboratory animals like mice, which have very different gut bacteria to mice living in the wild. However, it was unclear whether this difference in microbes was due to domestication, and if it could also be seen in other domesticated-wild pairs, like pigs and wild boars or dogs and wolves. A few existing studies have compared the gut bacteria of two species in a domesticated-wild pair. But, studies of isolated pairs cannot distinguish which factors are responsible for altering the microbiota of domesticated animals. To overcome this barrier, Reese et al. sequenced microbial DNA taken from fecal samples of 18 species of wild and related domesticated mammals. The results showed that while domesticated animals have different sets of bacteria in their guts, leaving the wild has changed the gut microbiota of these diverse animals in similar ways. To explore what causes these shared patterns, Reese et al. swapped the diets of two domesticated-wild pairs: laboratory and wild mice, and dogs and wolves. They found this change in diet shifted the gut bacteria of the domesticated species to be more similar to that of their wild counterparts, and vice versa. This suggests that altered eating habits helped drive the changes domestication has had on the gut microbiota. To find out whether these differences also occur in humans, Reese et al. compared the gut microbes of chimpanzees with the microbiota of people living in different environments. The gut microbial communities of individuals from industrialized populations had more in common with those of domesticated animals than did the microbes found in chimpanzees or humans from non-industrialized populations. This suggests that industrialization and domestication have had similar effects on the gut microbiota, likely due to similar kinds of environmental change. Domesticated animals are critical for the economy and health, and understanding the central role gut microbes play in their biology could help improve their well-being. Given the parallels between domestication and industrialization, knowledge gained from animal pairs could also shed light on the human gut microbiota. In the future, these insights could help identify new ways to alter the gut microbiota to improve animal or human health.

Bears habituate to the repeated exposure of a novel stimulus, unmanned aircraft systems.

Unmanned aircraft systems (UAS; i.e. 'drones') provide new opportunities for data collection in ecology, wildlife biology and conservation. Yet, several studies have documented behavioral or physiological responses to close-proximity UAS flights. We experimentally tested whether American black bears (Ursus americanus) habituate to repeated UAS exposure and whether tolerance levels persist during an extended period without UAS flights. Using implanted cardiac biologgers, we measured heart rate (HR) of five captive bears before and after the first of five flights each day. Spikes in HR, a measure of stress, diminished across the five flights within each day and over the course of 4 weeks of twice-weekly exposure. We halted flights for 118 days, and when we resumed, HR responses were similar to that at the end of the previous trials. Our findings highlight the capacity of a large mammal to become and remain habituated to a novel anthropogenic stimulus in a relatively short time (3-4 weeks). However, such habituation to mechanical noises may reduce their wariness of other human threats. Also, whereas cardiac effects diminished, frequent UAS disturbances may have other chronic physiological effects that were not measured. We caution that the rate of habituation may differ between wild and captive animals: while the captive bears displayed large initial spikes in HR change (albeit not as large as wild bears), these animals were accustomed to regular exposure to humans and mechanical noises that may have hastened habituation to the UAS.

Experimentally derived δ¹³C and δ¹5N discrimination factors for gray wolves and the impact of prior information in Bayesian mixing models.

Stable isotope analysis of diet has become a common tool in conservation research. However, the multiple sources of uncertainty inherent in this analysis framework involve consequences that have not been thoroughly addressed. Uncertainty arises from the choice of trophic discrimination factors, and for Bayesian stable isotope mixing models (SIMMs), the specification of prior information; the combined effect of these aspects has not been explicitly tested. We used a captive feeding study of gray wolves (Canis lupus) to determine the first experimentally-derived trophic discrimination factors of C and N for this large carnivore of broad conservation interest. Using the estimated diet in our controlled system and data from a published study on wild wolves and their prey in Montana, USA, we then investigated the simultaneous effect of discrimination factors and prior information on diet reconstruction with Bayesian SIMMs. Discrimination factors for gray wolves and their prey were 1.97‰ for δ13C and 3.04‰ for δ15N. Specifying wolf discrimination factors, as opposed to the commonly used red fox (Vulpes vulpes) factors, made little practical difference to estimates of wolf diet, but prior information had a strong effect on bias, precision, and accuracy of posterior estimates. Without specifying prior information in our Bayesian SIMM, it was not possible to produce SIMM posteriors statistically similar to the estimated diet in our controlled study or the diet of wild wolves. Our study demonstrates the critical effect of prior information on estimates of animal diets using Bayesian SIMMs, and suggests species-specific trophic discrimination factors are of secondary importance. When using stable isotope analysis to inform conservation decisions researchers should understand the limits of their data. It may be difficult to obtain useful information from SIMMs if informative priors are omitted and species-specific discrimination factors are unavailable.

High accuracy of narrow band imaging without magnification for the real-time characterization of polyp histology and its comparison with high-definition white light colonoscopy: a prospective study.

OBJECTIVES: Standard white light colonoscopy has limited ability to differentiate between polyp types (adenomatous vs. hyperplastic). Narrow band imaging (NBI) highlights the superficial mucosal/vascular patterns on polyps and may facilitate real-time characterization of polyp histology. The aim of this study was to prospectively evaluate and compare the diagnostic characteristics of high-definition white light colonoscopy (HDWL) and NBI without magnification in the real-time prediction of polyp histology (adenomatous vs. hyperplastic) by evaluating the surface mucosal and vascular patterns. METHODS: We conducted a prospective comparative study in a tertiary referral center. A total of 100 patients referred for screening or surveillance colonoscopy were prospectively enrolled and underwent colonoscopy using a high-definition colonoscope with NBI capability. Every polyp detected was initially evaluated with HDWL followed by NBI for the presence of surface mucosal/vascular patterns. Based on these patterns, polyp histology was predicted by both modalities. The main outcome measurements were: (i) diagnostic characteristics of HDWL and NBI in predicting polyp histology and (ii) impact of polyp size and learning effect (first half of study vs. second half) on the ability of NBI to predict adenomas. RESULTS: A total of 236 polyps were detected in 100 patients-143 adenomas, 77 hyperplastic, and 16 others. Surface patterns (type A: hyperplastic; type B: adenomatous) were recognized in all polyps with NBI (100%) compared to 45% with HDWL. For predicting adenomas, NBI had a significantly higher sensitivity and greater accuracy (96 and 93% respectively) compared with HDWL (38 and 61% respectively) (all P<0.0001). Although the accuracy of NBI for predicting adenomas improved with increasing polyp size (< or =5 mm; 6-9 mm; > or =10 mm) and in the second half compared with the first half of the study, these differences were not statistically significant. CONCLUSIONS: Using a simple surface mucosal/vascular pattern classification, NBI without magnification was highly accurate and significantly superior to HDWL for the real-time prediction of adenomas.

Recognition of surface mucosal and vascular patterns of colon polyps by using narrow-band imaging: interobserver and intraobserver agreement and prediction of polyp histology.

BACKGROUND: The 2 main types of colon polyps are adenomas and hyperplastic. Pit patterns on the surface of polyps have been described by using magnification chromoendoscopy, which can help differentiate between polyp types. Narrow band imaging (NBI) is a novel technology that enhances the visualization of surface mucosal and vascular patterns on the polyp surface. Earlier we described, in a pilot study, patterns seen on the polyp surface with NBI that can help differentiate between adenomas and hyperplastic polyps with a high degree of accuracy. OBJECTIVE: The aim of this study was to evaluate the interobserver and intraobserver agreement (among endoscopists) for the NBI surface mucosal and vascular patterns and prediction of polyp histology and the accuracy of the investigators to predict polyp histology based on these patterns. SETTING: Kansas City Veterans Affairs Medical Center. METHODS: NBI images of the polyp surface mucosal and vascular patterns obtained in our pilot trial were retrieved. A teaching set of 20 images was selected to educate and demonstrate the polyp patterns to 4 endoscopists. Subsequently, the test set of images was evaluated by the 4 endoscopists for quality, polyp pattern, and prediction of polyp type. Interobserver agreement (k value) was calculated among the 4 assessors for the polyp patterns and predicted histology. By using the final histology as the criterion standard, the accuracy of polyp-type prediction was calculated for each assessor. After a period of 2 months, all polyp images were reevaluated by the assessors (as before), and all findings were recorded in a similar fashion. These results were used for calculation of intraobserver agreement (k value) and the accuracy of the assessors in predicting polyp type. RESULTS: Photographs of 65 polyps were included in the test set and were evaluated by the 4 assessors. Thirty-eight polyps were adenomatous, and 27 were hyperplastic. The kappa value for the interobserver agreement for polyp surface pattern was 0.57 (moderate) and for prediction of polyp type was 0.63 (substantial). The kappa value for the intraobserver agreement of the 4 assessors for the surface patterns was 0.70, 0.65, 0.60, and 0.79, and for the prediction of polyp type was 0.87, 0.71, 0.61, 0.81. The accuracy to predict polyp type ranged from 80% to 86% for the 4 assessors in the first reading and from 85% to 91% in the second reading, with every assessor showing an improvement in accuracy in the second reading. LIMITATIONS: A single-center study, with a limited number of polyps. CONCLUSIONS: This initial evaluation showed that the NBI polyp patterns described in our pilot study are reproducible, easy to learn, reasonably accurate, and have the potential for use in daily clinical practice for the real-time differentiation of colon polyps.

Narrow-band imaging colonoscopy--a pilot feasibility study for the detection of polyps and correlation of surface patterns with polyp histologic diagnosis.

BACKGROUND: Colonoscopy is the preferred screening method for colorectal cancer. However, it has a substantial miss rate for colon polyps, and several techniques have been attempted to improve this limitation. Narrow-band imaging (NBI) is a novel technology that enhances the visualization of surface mucosal and vascular patterns. OBJECTIVE: The aim of this study was to determine the detection rate of additional polyps by NBI after removal of polyps visualized by standard white light colonoscopy (WLC) and to correlate the surface mucosal and vascular patterns with polyp histologic diagnosis. DESIGN: This was a prospective pilot feasibility study. SETTING: Kansas City Veterans Affairs Medical Center. PATIENTS: Subjects referred for screening colonoscopy were prospectively enrolled. METHODS: Subjects underwent colonoscopy after enrollment. After intubation of the cecum, colonic segments were sequentially examined, initially with WLC with removal of polyps followed by re-examination of the same segment with NBI. Additional polyps seen with NBI were photographed for their surface patterns and then removed. The total number of polyps visualized by WLC and NBI was calculated and the surface patterns were then correlated with polyp histologic features. RESULTS: Forty patients were enrolled in the study, all men, 32 white. The mean age was 62 years. A total of 72 polyps were detected by WLC (43 tubular adenoma, 28 hyperplastic polyps), whereas NBI detected an additional 51 polyps, of which 29 were tubular adenomas and 22 were hyperplastic. Five different surface/vascular patterns were observed: fine capillary network with absent mucosal pattern, circular pattern with dots, round/oval pattern, tubular pattern, and gyrus pattern. The sensitivity, specificity, and overall accuracy of the first two patterns for hyperplastic polyps were 86%, 96%, and 92%, respectively, and of the latter three patterns for tubular adenomas were 96%, 86%, and 92%, respectively. CONCLUSIONS: This pilot study demonstrates the feasibility of polyp detection and histologic correlation with NBI. These findings need to be confirmed in future randomized controlled trials.

GnRH-agonist induction of fertile estrus with either natural mating or artificial insemination, followed by birth of pups in gray wolves (Canis lupus).

Although captive populations of endangered species such as the Mexican gray wolf (Canis lupus baileyi) can benefit from artificial insemination to accomplish genetic exchange, reliable techniques for timing insemination are lacking. We used the generic gray wolf (C. lupus) to test the efficacy of a short-acting GnRH-agonist implant, deslorelin, for inducing estrus. Of five females receiving implants on 17 or 18 January 2003, two mated naturally 10-17 days later, and the others were artificially inseminated using fresh semen, one on day 7 and all three on day 11. Relaxin tests revealed that one artificially inseminated female and both naturally mated females were pregnant on 1 March, and all three gave birth to healthy puppies on 4-6 April. Of the artificially inseminated females, only the one who subsequently conceived and gave birth was judged to be in cytologic estrus at the time of insemination. Two females were treated again with deslorelin on 12 January 2004, followed by collection of fecal samples for hormone analysis. One female, who was housed with a male, copulated on day 17 but did not conceive; the other was not with an adult male. Fecal progestin and estrogen profiles suggested that estrus, but not ovulation, was induced. These results indicated that deslorelin could induce fertile estrus in the gray wolf, although individual response varied. Further investigation is needed to better define and control the interval between implant insertion and ovulation for optimal timing of insemination.