The assembly of DNA into chromatin in eukaryotic cells affects all DNA-related cellular activities, such as replication, transcription, recombination, and repair. Rearrangement of chromatin structure during nucleotide excision repair (NER) was discovered more than 2 decades ago. However, the molecular basis of chromatin dynamics during NER remains undefined. Pioneering studies in the field of gene transcription have shown that ATP-dependent chromatin-remodeling complexes and histone-modifying enzymes play a critical role in chromatin dynamics during transcription. Similarly, recent studies have demonstrated that the SWI/SNF chromatin-remodeling complex facilitates NER both in vitro and in vivo. Additionally, histone acetylation has also been linked to the NER of ultraviolet light damage. In this article, we will discuss the role of these identified chromatin-modifying activities in NER.
BRG1 is a catalytic subunit of the human SWI/SNF-like BAF chromatin remodeling complexes. Recent findings have shown that inactivation of BRG1 sensitizes mammalian cells to various DNA damaging agents, including ultraviolet (UV) and ionizing radiation. However, it is unclear whether BRG1 facilitates nucleotide excision repair (NER). Here we show that re-expression of BRG1 in cells lacking endogenous BRG1 expression stimulates nucleotide excision repair of UV induced DNA damage. Using a micropore UV radiation technique, we demonstrate that recruitment of the DNA damage recognition protein XPC to sites of UV lesions is significantly disrupted when BRG1 is depleted. Chromatin immunoprecipitation of the endogenous DDB2 protein, which is involved in recruiting XPC to UV-induced CPDs (cyclobutane pyrimidine dimers), shows that elevated levels of BRG1 are associated with DDB2 in chromatin in response to UV radiation. Additionally, we detected slow BRG1 accumulation at sites of UV lesions. Our findings suggest that the chromatin remodeling factor BRG1 is recruited to sites of UV lesions to facilitate NER in human chromatin.
Third-generation cephalosporins, such as ceftiofur, are commonly used to treat metritis in dairy cows. Chitosan microparticles has been shown to have a broad spectrum of activity in vitro and to be effective against uterine pathogens in vivo ; therefore, they have been hailed as a possible alternative to traditional antibiotics. Nonetheless, in the present study, we saw that chitosan microparticle treatment slowed the progression of the uterine microbiome of cows with metritis toward a healthy state, whereas ceftiofur treatment hastened the progression toward a healthy state. Given the lack of an effective alternative to traditional antibiotics and an increased concern about antimicrobial resistance, a greater effort should be devoted to the prevention of metritis in dairy cows.
Monitoring circulating progesterone concentration ([P4]) is an important component of basic and applied reproduction research and clinical settings. IMMULITE® 2000 XPi (Siemens Healthineers, Cary, NC) is a newly upgraded fully automated immunoassay system marketed for human use to measure concentrations of different measurands including P4.Our objective was therefore to characterize the analytical performance of the IMMULITE® 2000 XPi P4 immunoassay (IPI) across the reportable range in serum and plasma of cattle.The IPI validation protocols included characterization of the method linearity, within-run, and between-run precision through calculation of the coefficient of variation (CV). The method accuracy was assessed through the calculation of the spiking-recovery (SR) bias across the reportable range (0.2-40.0 ng/mL). Passing-Bablok regression and Bland-Altman plots were used to determine the interlaboratory bias for two laboratories. Three types of observed total error (TEo) were calculated based on the considered type of bias, TEoSR (spiking-recovery), TEoRB (range-based bias), and TEoAB (average-based bias).The IPI was linearly related to the true value (R2 = 0.997) across the reportable range. The within-run and between-run precision (CV%) of the IPI for both serum and plasma [P4] of clinical relevance (1, 2, 5, and 10 ng/mL) were <5 and <10%, respectively. The TEo reported here for serum and plasma at [P4] of 1 and 5 ng/mL was ~20 and 25%, respectively. Of interest, the three types of TEo were relatively similar regardless of the considered bias.We concluded that the automated IPI provides a precise, accurate, reliable, and safe method for measuring [P4] in both serum and plasma of cattle. Consistent with the manufacturer's recommendations, the serum matrix is more accurate than plasma.
The Florida Native Sheep breed (FNS) is an endangered sheep breed that has been shown to be a survival breed with genetic resistance to gastrointestinal parasitism. However, there is a lack of information regarding the breed's reproductive physiology, which hinders their preservation and improvement. This study aimed to characterize the reproductive features of the FNS breed, specifically age at puberty and seasonality, and establish serum progesterone concentration profiles of cyclicity and pregnancy. The study was conducted between July 2021 and July 2022 in North Central Florida. Serial serum samples from 13 ewe lambs, 24 open ewes, and 6 pregnant ewes were collected to evaluate progesterone concentrations (IMMULITE® 2000 XPi Immunoassay System; Siemens Healthcare, CA, USA). Progesterone values >1.0 ng/mL were indicative of luteal activity and/or placental synthesis in pregnant ewes. The start of the breeding season (> 50% of animals cycling) for multiparous ewes was early July and early August for yearling ewes. Ewe lambs reached puberty at an average age of 8 ± 1.26 (mean ± SD) months of age, with more than 50% of them cycling from early October to late December. During pregnancy, progesterone concentrations remained above 1.0 ng/mL and increased exponentially peaking around day 120 post-ram introduction with an average of 16.59 ± 7.2 ng/mL (mean ± SD) and beginning to decrease before lambing. In conclusion, FNS are influenced by seasonality displaying a breeding and an anestrous season associated with the length of the daylight. This information will contribute to the development of targeted reproductive management strategies to improve the breed's profitability and sustainability.
