The aim of the present study was to evaluate the effects of synchronization method, season, parity, corpus luteum (CL) size, and progesterone (P4) levels on the pregnancy rate after bovine embryo transfer (ET). Among 165 recipient candidates who received 1 of 2s estrus synchronization treatments, 96 heifers and 43 cows were selected through rectal examination and used as recipients. The day before ET, the CL size and plasma P4 concentration were evaluated. The CL sizes and plasma P4 levels were not different between the selected and unselected candidates, and the pregnancy rates with the two synchronization methods were not different. However, the pregnancy rates were higher in heifers than in lactating cows, and also higher after ET performed from September to February than from March to August (p < 0.05). The recipients with a CL larger than 1.5 cm showed statistically higher pregnancy rates, and although there was no statistical significance, the pregnancy rate was higher when the plasma P4 levels were between 2.0 and 4.0 ng/mL. Exposure to a stressful environment and repeated manipulations can reduce the success rate of ET, and recipient selection with an optimal CL size and P4 level can increase the success rate of ET.

Staphylococcus aureus can cause local or systemic infections as an opportunistic pathogen and induce the activation of inflammasomes, leading to the secretion of interleukin (IL)-1β. Since S. aureus is part of the normal flora, it is essential to control it using safe, non-antibiotic substances like Korean Red Ginseng Extract (RGE). This study investigated the effects of maltol, a non-saponin compound found in RGE, on S. aureus-mediated inflammasome signaling. Human keratinocytes (HaCaT) and macrophages were infected with S. aureus and treated with RGE and maltol. The secretion of IL-1β, an indicator of inflammasome activation, was analyzed. For the mechanistic studies, the HaCaT cells were infected with S. aureus in the presence of maltol or inflammasome inhibitors, and the generation of mitochondrial reactive oxygen species (mitROS) and IL-1β production were measured. The effect of maltol was also evaluated in S. aureus-injected mice. RGE and maltol inhibited S. aureus-mediated IL-1β secretion in HaCaT, but not in macrophages. In the mechanistic studies, maltol suppressed the production of mitROS and the priming step of inflammasome signaling resulting in attenuated S. aureus-mediated inflammasome activation in HaCaT. In mice, maltol inhibited the production of peritoneal IL-1β and IL-6 in response to the S. aureus injection. Maltol selectively regulated skin inflammasome activation by inhibiting mitROS generation and the inflammasome priming step.

Hwang H, et al. J Vet Sci. 2022 Aug;23(5):e75. https://doi.org/10.4142/jvs.22045

Chimeric lysins composed of various combinations of cell wall-lysing (enzymatic) and cell-wall-binding (CWB) domains of endolysins, autolysins, and bacteriocins have been developed as alternatives to or adjuvants of conventional antibiotics. The screening of multiple chimeric lysin candidates for activity via E. coli expression is not cost effective, and we previously reported on a simple cell-free expression system as an alternative. In this study, we sufficiently improved upon this cell-free expression system for use in screening activity via a turbidity reduction test, which is more appropriate than a colony reduction test when applied in multiple screening. Using the improved protocol, we screened and compared the antibacterial activity of chimeric lysin candidates and verified the relatively strong activity associated with the CHAP (cysteine, histidine-dependent amidohydrolase/peptidase) domain of secretory antigen SsaA-like protein (ALS2). ALS2 expressed in E. coli showed two major bands, and the smaller one (subprotein) was shown to be expressed by an innate downstream promoter and start codon (ATG). The introduction of synonymous mutations in the promoter resulted in clearly reduced expression of the subprotein, whereas missense mutations in the start codon abolished antibacterial activity as well as subprotein production. Interestingly, most of the S. aureus strains responsible for bovine mastitis were susceptible to ALS2, but those from human and chicken were less susceptible. Thus, the simple and rapid screening method can be applied to select functional chimeric lysins and define mutations affecting antibacterial activity, and ALS2 may be useful in itself and as a lead molecule to control bovine mastitis.

Ro Y, et al. J Vet Sci. 2022 Jul;23:e60. https://doi.org/10.4142/jvs.22050

Gyuho Jeong, Younghye Ro, Kyunghyun Min, Woojae Choi, Ilsu Yoon, Hyoeun Noh, Danil Kim. J Vet Clin 2023;40:215-20. https://doi.org/10.17555/jvc.2023.40.3.215