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The trans-10 shift is a recognized deviation from the normal ruminal biohydrogenation (BH) pathways of the dietary polyunsaturated fatty acids (FA) in the rumen. This phenomenon leads to the formation of the harmful t10-18:1, which is detrimental to the health of the animal, instead of the beneficial t11-18:1, which has positive effects. The phenomenon known as the t10-shift has been observed in animals consuming diets that are high in starch but low in forage. Although consuming such similar diets, there exists a significant variability in t10-shift expression among animals. The reasons be- hind the t10-shift are not well understood. With the aim of finding biomarkers associated with t10-shift, this study utilized multiple levels of information, including lipidomics, metabolomics, and proteomics of ruminal contents. Rumen contents from male lambs (n = 16) distributed by two diets with distinct forage: concentrate ratios (20:80 and 80:20) were collected after 42 d on ad libitum feed. FA from rumen contents were prepared and analyzed by gas chromatography, metaproteomics analyzes were performed from rumen bacterial pellets using LC-MS/MS-based label-free quantification, and metabolomics analyzes were performed from rumen fluid supernatants using IMS-TOF technology. Multivariate analyses and correlations were performed using the Metaboanalyst R package. Several fatty acids, proteins, and metabolites showed a strong correlation with the proportion of t10-18:1 in rumen contents. Among fatty acids, 17:0, 14:0, a-15:0, and t15-18:1 were positively correlated, while t11-18:1, t11,c13-CLA and c9,t11-CLA showed negative correlation. The metabolites, thiamine aldehyde, mevinolinic acid, 2-hydroxy-2H-benzo[h] chromene-2-carboxylate, or biotin were positively correlated with t10-18:1, as well as proteins associated with gluconeogenesis, stress response or amino acid metabolism. This work provides, for the first time, a multi-level integrated view of t10-shift phenomena in sheep. Fundação para a Ciência e a Tecnologia (FCT) provided financial support through the research pro- jects PTDC/CAL-ZOO/29654/2017 (RumOmics), PTDC/CAL-ZOO/4515/2021 (Gene2Rumen), UIDB/00276/2020 (CIISA), UIDB/04129/2020 (LEAF), and LA/P/0059/2020 (AL4Animals) [ABSTRACT FROM AUTHOR]

Ejaculate proteins are key mediators of post-mating sexual selection and sexual conflict, as they can influence both male fertilization success and female reproductive physiology. However, the extent and sources of genetic variation and condition dependence of the ejaculate proteome are largely unknown. Such knowledge could reveal the targets and mechanisms of post-mating selection and inform about the relative costs and allocation of different ejaculate components, each with its own potential fitness consequences. Here, we used liquid chromatography coupled with tandem mass spectrometry to characterize the whole-ejaculate protein composition across 12 isogenic lines of Drosophila melanogaster that were reared on a high- or low-quality diet. We discovered new proteins in the transferred ejaculate and inferred their origin in the male reproductive system. We further found that the ejaculate composition was mainly determined by genotype identity and genotype-specific responses to larval diet, with no clear overall diet effect. Nutrient restriction increased proteolytic protein activity and shifted the balance between reproductive function and RNA metabolism. Our results open new avenues for exploring the intricate role of genotypes and their environment in shaping ejaculate composition, or for studying the functional dynamics and evolutionary potential of the ejaculate in its multivariate complexity.