Recent studies in model organisms have shown that compositional variation in the microbiome can affect a variety of host phenotypes including those related to digestion, development, immunity, and ...behavior. Natural variation in the microbiome within and between natural populations and species may also affect host phenotypes and thus fitness in the wild. Here, I review recent evidence that compositional variation in the microbiome may affect host phenotypes and fitness in wild mammals. Studies over the last decade indicate that natural variation in the mammalian microbiome may be important in the assistance of energy uptake from different diet types, detoxification of plant secondary compounds, protection from pathogens, chemical communication, and behavior. I discuss the importance of combining both field observations and manipulative experiments in a single system to fully characterize the functions and fitness effects of the microbiome. Finally, I discuss the evolutionary consequences of mammal–microbiome associations by proposing a framework to test how natural selection on hosts is mediated by the microbiome.
The palladium-catalyzed cross-coupling reaction between organoboranes and organic electrophiles in the presence of base was first developed 30 years ago. It offers a powerful and general methodology ...for forming carbon-carbon bonds. The scope of the reaction has continued to evolve and broaden to meet modern synthetic requirements.
The role of the microbiota in human genetic adaptation Suzuki, Taichi A; Ley, Ruth E
Science (American Association for the Advancement of Science),
2020-Dec-04, 2020-12-04, 20201204, Letnik:
370, Številka:
6521
Journal Article
Recenzirano
As human populations spread across the world, they adapted genetically to local conditions. So too did the resident microorganism communities that everyone carries with them. However, the collective ...influence of the diverse and dynamic community of resident microbes on host evolution is poorly understood. The taxonomic composition of the microbiota varies among individuals and displays a range of sometimes redundant functions that modify the physicochemical environment of the host and may alter selection pressures. Here we review known human traits and genes for which the microbiota may have contributed or responded to changes in host diet, climate, or pathogen exposure. Integrating host-microbiota interactions in human adaptation could offer new approaches to improve our understanding of human health and evolution.
There is a growing appreciation of the role of gut microbial communities in host biology. However, the nature of variation in microbial communities among different segments of the gastrointestinal ...(GI) tract is not well understood. Here, we describe microbial communities from ten different segments of the GI tract (mouth, esophagus, stomach, duodenum, ileum, proximal cecum, distal cecum, colon, rectum, and feces) in wild house mice using 16S rRNA gene amplicon sequencing. We also measured carbon and nitrogen stable isotopic ratios from hair samples of individual mice as a proxy for diet. We identified factors that may explain differences in microbial composition among gut segments, and we tested for differences among individual mice in the composition of the microbiota. Consistent with previous studies, the lower GI tract was characterized by a greater relative abundance of anaerobic bacteria and greater microbial diversity relative to the upper GI tract. The upper and lower GI tracts also differed in the relative abundances of predicted microbial gene functions, including those involved in metabolic pathways. However, when the upper and lower GI tracts were considered separately, gut microbial composition was associated with individual mice. Finally, microbial communities derived from fecal samples were similar to those derived from the lower GI tract of their respective hosts, supporting the utility of fecal sampling for studying the gut microbiota of mice. These results show that while there is substantial heterogeneity among segments of the GI tract, individual hosts play a significant role in structuring microbial communities within particular segments of the GI tract.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Mammals house a diversity of bacteria that affect health in various ways, but the routes by which bacterial lineages are transmitted between hosts remain poorly understood. We experimentally ...determined microbiota transmission modes by deriving 17 inbred mouse lines from two wild populations and monitoring their gut microbiotas for up to 11 host generations. Individual- and population-level microbiota compositions were maintained within mouse lines throughout the experiment, indicating predominantly vertical inheritance of the microbiota. However, certain bacterial taxa tended to be exchanged horizontally between mouse lines. Consistent with evolutionary theory, the degree of horizontal transmission predicted bacterial genera with pathogenic representatives responsible for human infections and hospitalizations.
The perirhinal cortex Suzuki, Wendy A; Naya, Yuji
Annual review of neuroscience,
01/2014, Letnik:
37
Journal Article
Recenzirano
Odprti dostop
Anatomically, the perirhinal cortex sits at the boundary between the medial temporal lobe and the ventral visual pathway. It has prominent interconnections not only with both these systems, but also ...with a wide range of unimodal and polymodal association areas. Consistent with these diverse projections, neurophysiological studies reveal a multidimensional set of mnemonic signals that include stimulus familiarity, within- and between-domain associations, associative recall, and delay-based persistence. This wide range of perirhinal memory signals not only includes signals that are largely unique to the perirhinal cortex (i.e., object familiarity), consistent with dual-process theories, but also includes a range of signals (i.e., associative flexibility and recall) that are strongly associated with the hippocampus, consistent with single-process theories. These neurophysiological findings have important implications for bridging the gap between single-process and dual-process models of medial temporal lobe function.
The maintenance of oxygen homeostasis in the gut is critical for the maintenance of a healthy gut microbiota. However, few studies have explored how the concentration of atmospheric oxygen affects ...the gut microbiota in natural populations. High‐altitude environments provide an opportunity to study the potential effects of atmospheric oxygen on the composition and function of the gut microbiota. Here, we characterized the caecal microbial communities of wild house mice (Mus musculus domesticus) in two independent altitudinal transects, one in Ecuador and one in Bolivia, from sea level to nearly 4,000 m. First, we found that differences in altitude were associated with differences in the gut microbial community after controlling for the effects of body mass, diet, reproductive status and population of origin. Second, obligate anaerobes tended to show a positive correlation with altitude, while all other microbes tended to show a negative correlation with altitude. These patterns were seen independently in both transects, consistent with the expected effects of atmospheric oxygen on gut microbes. Prevotella was the most‐enriched genus at high elevations in both transects, consistent with observations in high‐altitude populations of pikas, ruminants and humans, and also consistent with observations of laboratory mice exposed to hypoxic conditions. Lastly, the renin–angiotensin system, a recently proposed microbiota‐mediated pathway of blood pressure regulation, was the top predicted metagenomic pathway enriched in high altitudes in both transects. These results suggest that high‐altitude environments affect the composition and function of the gut microbiota in wild mammals.
To provide a better understanding of rheological properties of mantle rocks under lithospheric conditions, we carried out a series of experiments on the creep behavior of polycrystalline olivine at ...high pressures (∼4–9 GPa), relatively low temperatures (673 ≤ T ≤ 1273 K), and anhydrous conditions, using a deformation‐DIA. Differential stress and sample displacement were monitored in situ using synchrotron X‐ray diffraction and radiography, respectively. Experimental results were fit to the low‐temperature plasticity flow law, . On the basis of this analysis, the low‐temperature plasticity of olivine deformed under anhydrous conditions is well constrained by our data with a Peierls stress of σP = 5.9 ± 0.2 GPa, a zero‐stress activation energy of Ek(0) = 320 ± 50 kJ mol−1, and AP = 1.4 × 10−7 s−1 MPa−2. Compared with published results for high‐temperature creep of olivine, a transition from low‐temperature plasticity to high‐temperature creep occurs at ∼1300 K for a strain rate of ∼10−5 s−1. For a geological strain rate of 10−14 s−1, extrapolation of our low‐temperature flow law to 873 K, the cutoff temperature for earthquakes in the mantle, yields a strength of ∼600 MPa. The low‐temperature, high‐stress flow law for olivine in this study provides a solid basis for modeling tectonic processes occurring within Earth's lithosphere.
A dominant view in the learning and memory literature states that a subset of anatomically related structures within the medial temporal lobe (MTL), including the hippocampus, entorhinal, perirhinal, ...and parahippocampal cortices, forms a functionally related system specialized for declarative memory but not for perception. However, recent reports challenge this view, suggesting instead that the medial temporal lobe is not only important for memory, but also critical for certain forms of perception. In this review, I argue that little or no conclusive evidence currently exists to support the latter view. Experimental studies that have examined the perceptual functions of the MTL in monkeys are inconclusive because they fail to isolate perceptual from mnemonic task demands. Evaluation of conflicting results from studies in human amnesic patients suggests that extraneous damage to extra-MTL areas may underlie the reported perceptual deficits in the group of amnesic patients at the heart of this debate. See the related Review from Baxter, “Involvement of Medial Temporal Lobe Structures in Memory and Perception,” in this issue of Neuron.
PDF
