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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.

In an earlier work (Castillo et al. in J Math Phys 61:103505, 2020), it was established, from a hypergeometric-type difference equation, tractable sufficient conditions for the monotonicity with respect to a real parameter of zeros of classical discrete orthogonal polynomials on linear, quadratic, q-linear, and q-quadratic grids. In this work, we continue with the study of zeros of these polynomials by giving a comparison theorem of Sturm type. As an application, we analyze in a simple way some relations between the zeros of certain classical discrete orthogonal polynomials.

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.

Natural transmission of the mammalian microbiota is poorly understood. Some genera of bacteria are transmitted from mothers to offspring, whereas others are acquired from the wider environment. Moeller et al. derived inbred mouse lines from two wild populations of mice with distinct microbiota and monitored the populations' microbiomes for 3 years while they were kept in the same animal facility. The microbiota of the two mouse lineages remained distinct even after 10 generations. Most microbiota genera transmitted vertically. Those taxa that transmitted horizontally through the shared environment of the animal facility tended to be those that include pathogens. Science , this issue p. 453 The gut bacteria of mice have taxa-specific transmission routes, with implications for virulence evolution. 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.

Background:The Outcome Measures in Rheumatology (OMERACT) developed a scoring system for salivary gland parenchymal inflammation based on power Doppler ultrasound signals (PDs) in Sjogren’s disease (SjD) in 2021. However, limited evaluation has been conducted so far, necessitating further studies for broader use in daily practice.Objectives:We aimed to investigate changes in PDs and greyscale (GS) of parotid (PG) and submandibular glands (SMG) in real-world medical practice and assess the usefulness of PDs in patients with SjD.Methods:Patients diagnosed with SjD by the 2016 ACR/EULAR classification criteria or the revised Japanese Ministry of Health criteria (1999) were included in our hospital study. Data was collected annually for three years following the initial visit. We assessed OMERACT-scored GS and PDs, shear wave elastography (SWE), and shear wave velocity (SWV) in PG and SMG using ultrasound. We also evaluated correlations with the EULAR Sjogren’s Syndrome (SS) disease activity index (ESSDAI), the EULAR Sjogren’s Syndrome Patient Reported Index (ESSPRI), stimulated salivary flow rate (SSFR) by Saxon’s test, Greenspan focus score by labial salivary gland biopsy, anti-SS-A, -SS-B, and -centromere antibodies. Treatments were decided by attending physicians.Results:Data were analyzed for 147, 85, 56, and 31 SjD patients at initiation, one, two, and three years later, respectively. Forty-eight cases were secondary SjD. Ninety patients (61%) received immunosuppressants (including mizoribine [42 patients], glucocorticoids [42 patients], hydroxychloroquine [28 patients], abatacept [14 patients], etc.) for over four months, 33 received Japanese-Kampo medicine, five received saliva secretion stimulants, and 35 received no medication. Initial PG PDs scores correlated with initial ESSDAI, and initial SMG PDs scores correlated with initial SSFR, SWE, and SWV. Over two years, SMG PDs scores decreased (initiation: 1.03, two years later: 0.77, p=0.018), while GS scores increased (PG: initiation: 1.45, one year later: 1.68, p=0.017; SMG: initiation: 2.06, one year later: 2.45, p=0.005, two years later: 2.45, p=0.008). PG PDs correlated with future GS (initial PDs with GS at one and two years later, one-year PDs with GS at two years later). Conversely, initial PG and SMG PDs, and one-year SMG PDs, negatively correlated with ESSPRI two years later. In patients receiving immunosuppressants, PDs significantly improved in PG at one year later and SMG at one and two years later, respectively, similar to ESSDAI and ESSPRI trends. SMG GS deteriorated at one year later but recovered at two years later. Unlike initial GS, PDs had no correlation with Greenspan focus score. Among autoantibodies, anti-SS-B correlated with initial PG PDs.Conclusion:GS scores worsened, but SMG PD scores decreased over time in SjD patients. PDs correlated with ESSDAI, SSFR, SWE, and SWV. PDs presence suggests the possibility of future salivary gland structural changes. Negative correlations between PDs and future ESSPRI suggest treatment efficacy. Future studies are needed to confirm the practical value of PDs.REFERENCES:[1] Hocevar A, Bruyn GA, Terslev L, Agustin JJD, et al. Development of a new ultrasound scoring system to evaluate glandular inflammation in Sjogren’s syndrome: an OMERACT reliability exercise. Rheumatol (Oxford) 2022; 61(8): 3341-3350[2] Lee KA, Lee SH, Kim HR, et al. Ultrasonographic changes of major salivary glands in primary Sjogren’s syndrome. J Clin Med 2020; 9: 803Figure 1.GS: greyscalePDs: power Doppler signalsPG: parotid glandsSMG: submandibular glandsAcknowledgements:NIL.Disclosure of Interests:None declared.

Episodic memory or memory for the detailed events in our lives is critically dependent on structures of the medial temporal lobe (MTL). A fundamental component of episodic memory is memory for the temporal order of items within an episode. To understand the contribution of individual MTL structures to temporal-order memory, we recorded single-unit activity and local field potential from three MTL areas (hippocampus and entorhinal and perirhinal cortex) and visual area TE as monkeys performed a temporal-order memory task. Hippocampus provided incremental timing signals from one item presentation to the next, whereas perirhinal cortex signaled the conjunction of items and their relative temporal order. Thus, perirhinal cortex appeared to integrate timing information from hippocampus with item information from visual sensory area TE.

Fragility fractures are increasingly recognized as a complication of both type 1 and type 2 diabetes, with fracture risk that increases with disease duration and poor glycemic control. Yet the identification and management of fracture risk in these patients remains challenging. This review explores the clinical characteristics of bone fragility in adults with diabetes and highlights recent studies that have evaluated bone mineral density (BMD), bone microstructure and material properties, biochemical markers, and fracture prediction algorithms (i.e., FRAX) in these patients. It further reviews the impact of diabetes drugs on bone as well as the efficacy of osteoporosis treatments in this population. We finally propose an algorithm for the identification and management of diabetic patients at increased fracture risk.

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.