IntroductionIn clinical settings, dairy cows are often attacked by pathogenic bacteria after delivery, especially Staphylococcus aureus (S. aureus). Neutrophils have long been regarded as essential for host defense against S. aureus. Prostaglandin E2 (PGE2) can additionally be used as an inflammatory mediator in pathological conditions to promote the repair of inflammatory injuries. However, whether S. aureus can promote the accumulation of PGE2 after the infection of neutrophils in cows and its mechanism remain unclear. Lipoprotein is an important immune bioactive ingredient of S. aureus.MethodsIn this study, the changes in neutrophils were monitored in dairy cows infected with wild-type S. aureus (SA113) and an S. aureus lipoprotein-deficient strain (Δlgt); meanwhile, we established whether pattern recognition receptors mediate this process and whether S. aureus lipoproteins are necessary for causing the release of PGE2 from cow neutrophils.ResultsThe results showed that Δlgt was less effective than SA113 in inducing the production of IL-1β, IL-6, IL-8, IL-10, and PGE2 within neutrophils; furthermore, TLR2, TLR4, and NLRP3 receptors were found to mediate the inducible effect of lipoprotein on the above inflammation mediators and cytokines, which depended on MAPK and Caspase-1 signaling pathways. In addition, TLR2, TLR4, and NLRP3 inhibitors significantly inhibited PGE2 and cytokine secretion, and PGE2 was involved in the interaction of S. aureus and neutrophils in dairy cows, which could be regulated by TLR2, TLR4, and NLRP3 receptors. We also found that S. aureus was more likely to be killed by neutrophils when it lacked lipoprotein and TLR2, TLR4, and NLRP3 were involved, but PGE2 seemed to have no effect.DiscussionTaken together, these results suggest that lipoprotein is a crucial component of S. aureus in inducing cytokine secretion by neutrophils as well as killing within neutrophils, which could be accomplished by the accumulation of PGE2 by activating MAPK and the Caspase-1 signaling pathways through TLR2, TLR4, and NLRP3 receptors. These results will contribute to a better understanding of the interaction between S. aureus and host immune cells in dairy cows.
Spermatogenesis is a highly organized process by which undifferentiated spermatogonia self‐renew and differentiate into spermatocytes and spermatids. The entire developmental process from spermatogonia to sperm occurs within the seminiferous tubules. Spermatogenesis is supported by the close interaction of germ cells with Sertoli cells. In this study, testicular tissues were collected from Hu sheep at 8 timepoints after birth: 0, 30, 90, 180, 270, 360, 540, and 720 days. Immunofluorescence staining and histological analysis were used to explore the development of male germ cells and Sertoli cells in the Hu sheep testes at these timepoints. The changes in seminiferous tubule diameter and male germ cells in the Hu sheep testes at these different developmental stages were analyzed. Then, specific molecular markers were used to study the proliferation and differentiation of spermatogonia, the timepoint of spermatocyte appearance, and the maturation and proliferation of Sertoli cells in the seminiferous tubules. Finally, the formation of the blood–testes barrier was studied using antibodies against the main components of the blood–testes barrier, β‐catenin, and ZO‐1. These findings not only increased the understanding of the development of the Hu sheep testes, but also laid a solid theoretical foundation for Hu sheep breeding.
Objective:The objective of this study was to analyse the differentially abundant proteins caused by freeze-thawing of ram sperm and explore candidate proteins of interest for their ability to improve ram sperm cryopreservation outcomes in vitro .Methods: Sperm were from three mature Dorper. Fresh and frozen sperm proteins were extracted, and the differentially abundant proteins were analysed by mass spectrometry (MS).Among these proteins, lactoferrin(LTF) was selected to be added before cryopreservation.Next, sperm samples were diluted in Tris extender, with the addition of 0μg/ml,10 μg/ml, 100 μg/ml, 500 μg/ml, 1000 μg/ml of LTF. After thawing, sperm quality evaluated by motility, plasma membrane integrity, mitochondrial activity and reactive oxygen species (ROS).Results: Cryopreservation significantly altered the abundance of 40 proteins; the abundance of 16 proteins was increased, while that of 24 proteins was decreased. Next, LTF was added to Tris extender applied to ram sperm. The results showed that sperm motility and plasma membrane integrity were significantly improved (p<0.05) by supplementation with 10 μg/ml LTF compared to those in the control group. There was no significant difference in mitochondrial activity between the 0μg/ml group and other groups (p>0.05). Supplementation of the cryoprotective extender with 10 μg/ml LTF led to decreased reactive oxygen species (ROS) levels compared with those in the control and other groups (p<0.05). Conclusion:LTF is an important protein during cryopreservation, and the addition of 10 μg/ml LTF to a cryoprotective extender can significantly improve the function of frozen ram
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