Using meta-analysis to understand the impacts of dietary protein and fat content on the composition of fecal microbiota of domestic dogs (Canis lupus familiaris): A pilot study

The interplay between diet and fecal microbiota composition is garnering increased interest across various host species, including domestic dogs. While the influence of dietary macronutrients and their associated microbial communities have been extensively reviewed, these reviews are descriptive and do not account for differences in microbial community analysis, nor do they standardize macronutrient content across studies. To address this, a meta-analysis was performed to assess the impact of dietary crude protein ("protein") and dietary crude fat ("fat") on the fecal microbiota composition in healthy dogs. Sixteen publications met the eligibility criteria for the meta-analysis, yielding a final data set of 314 dogs. Diets were classed as low, moderate, high, or supra in terms of protein or fat content. Sequence data from each publication were retrieved from public databases and reanalyzed using consistent bioinformatic pipelines. Analysis of community diversity indices and unsupervised clustering of the data with principal coordinate analysis revealed a small effect size and complete overlap between protein and fat levels at the overall community level. Supervised clustering through random forest analysis and partial least squares-discriminant analysis indicated alterations in the fecal microbiota composition at a more individual taxonomic level, corresponding to the levels of protein or fat. The Prevotellaceae Ga6A1 group and Enterococcus were associated with increasing levels of protein, while Allobaculum and Clostridium sensu stricto 13 were associated with increasing levels of fat. Interestingly, the random forest analyses revealed that Sharpea, despite its low relative abundance in the dog's fecal microbiome, was primarily responsible for the separation of the microbiome for both protein and fat. Future research should focus on validating and understanding the functional roles of these relatively low-abundant genera.

Cold water immersion in recovery following a single bout resistance exercise suppresses mechanisms of miRNA nuclear export and maturation

Cold water immersion (CWI) following intense exercise is a common athletic recovery practice. However, CWI impacts muscle adaptations to exercise training, with attenuated muscle hypertrophy and increased angiogenesis. Tissue temperature modulates the abundance of specific miRNA species and thus CWI may affect muscle adaptations via modulating miRNA expression following a bout of exercise. The current study focused on the regulatory mechanisms involved in cleavage and nuclear export of mature miRNA, including DROSHA, EXPORTIN-5, and DICER. Muscle biopsies were obtained from the vastus lateralis of young males (n = 9) at rest and at 2, 4, and 48 h of recovery from an acute bout of resistance exercise, followed by either 10 min of active recovery (ACT) at ambient temperature or CWI at 10°C. The abundance of key miRNA species in the regulation of intracellular anabolic signaling (miR-1 and miR-133a) and angiogenesis (miR-15a and miR-126) were measured, along with several gene targets implicated in satellite cell dynamics (NCAM and PAX7) and angiogenesis (VEGF and SPRED-1). When compared to ACT, CWI suppressed mRNA expression of DROSHA (24 h p = 0.025 and 48 h p = 0.017), EXPORTIN-5 (24 h p = 0.008), and DICER (24 h p = 0.0034). Of the analyzed miRNA species, miR-133a (24 h p < 0.001 and 48 h p = 0.007) and miR-126 (24 h p < 0.001 and 48 h p < 0.001) remained elevated at 24 h post-exercise in the CWI trial only. Potential gene targets of these miRNA, however, did not differ between trials. CWI may therefore impact miRNA abundance in skeletal muscle, although the precise physiological relevance needs further investigation.

Epichloë seed transmission efficiency is influenced by plant defense response mechanisms

Asexual Epichloë are endophytic fungi that form mutualistic symbioses with cool-season grasses, conferring to their hosts protection against biotic and abiotic stresses. Symbioses are maintained between grass generations as hyphae are vertically transmitted from parent to progeny plants through seed. However, endophyte transmission to the seed is an imperfect process where not all seeds become infected. The mechanisms underpinning the varying efficiencies of seed transmission are poorly understood. Host gene expression in response to Epichloë sp. LpTG-3 strain AR37 was examined within inflorescence primordia and ovaries of high and low endophyte transmission genotypes within a single population of perennial ryegrass. A genome-wide association study was conducted to identify population-level single nucleotide polymorphisms (SNPs) and associated genes correlated with vertical transmission efficiency. For low transmitters of AR37, upregulation of perennial ryegrass receptor-like kinases and resistance genes, typically associated with phytopathogen detection, comprised the largest group of differentially expressed genes (DEGs) in both inflorescence primordia and ovaries. DEGs involved in signaling and plant defense responses, such as cell wall modification, secondary metabolism, and reactive oxygen activities were also abundant. Transmission-associated SNPs were associated with genes for which gene ontology analysis identified "response to fungus" as the most significantly enriched term. Moreover, endophyte biomass as measured by quantitative PCR of Epichloë non-ribosomal peptide synthetase genes, was significantly lower in reproductive tissues of low-transmission hosts compared to high-transmission hosts. Endophyte seed-transmission efficiency appears to be influenced primarily by plant defense responses which reduce endophyte colonization of host reproductive tissues.

Double cytoplast embryonic cloning improves in vitro but not in vivo development from mitotic pluripotent cells in cattle

Cloning multiple animals from genomically selected donor embryos is inefficient but would accelerate genetic gain in dairy cattle breeding. To improve embryo cloning efficiency, we explored the idea that epigenetic reprogramming improves when donor cells are in mitosis. We derived primary cultures from bovine inner cell mass (ICM) cells of in vitro fertilized (IVF) embryos. Cells were grown feeder-free in a chemically defined medium with increased double kinase inhibition (2i⁺). Adding recombinant bovine interleukin 6 to 2i⁺ medium improved plating efficiency, outgrowth expansion, and expression of pluripotency-associated epiblast marker genes (NANOG, FGF4, SOX2, and DPPA3). For genotype multiplication by embryonic cell transfer (ECT) cloning, primary colonies were treated with nocodazole, and single mitotic donors were harvested by mechanical shake-off. Immunofluorescence against phosphorylated histone 3 (P-H3) showed 37% of nocodazole-treated cells in metaphase compared to 6% in DMSO controls (P < 1 × 10⁻⁵), with an average of 53% of P-H3-positive cells expressing the pluripotency marker SOX2. We optimized several parameters (fusion buffer, pronase treatment, and activation timing) for ECT with mitotic embryonic donors. Sequential double cytoplast ECT, whereby another cytoplast was fused to the first cloned reconstruct, doubled cloned blastocyst development and improved morphological embryo quality. However, in situ karyotyping revealed that over 90% of mitotic ECT-derived blastocysts were tetraploid or aneuploid with extra chromosomes, compared to less than 2% in the original ICM donor cells. Following the transfer of single vs. double cytoplast embryos, there was no difference between the two methods in pregnancy establishment at D35 (1/22 = 5% vs. 4/53 = 8% for single vs. double ECT, respectively). Overall, post-implantation development was drastically reduced from embryonic mitotic clones when compared to somatic interphase clones and IVF controls. We conclude that mitotic donors cause ploidy errors during in vitro development that cannot be rescued by enhanced epigenetic reprogramming through double cytoplast cloning.