Objective To explore the effects of microRNA(miRNA)- 30c knockdown on proliferation,diffe-rentiation of P19 cells. Methods miRNA - 30c knockdown plasmid(miRNA - 30c knockdown group)or no - load vector(negative control group)was transfected into P19 cells by lipo2000 and stable cell lines were selected by Blastici-din;Dual luciferase reporter gene system was used to confirm miRNA - 30c knockdown. Cell counting kit - 8(CCK - 8) assay was adopted to detect cell proliferation activity. An inverted microscope was used to observe morphological chan-ges of P19 cell differentiation. Cells were induced to differentiated to myocardiocyte with dimethyl sulfoxide(DMSO). Differentiation marker genes including cTnT,NKX2. 5,GATA4 relative mRNA expression levels were detected with real - time quantitative polymerase chain reaction,respectively. Results Observation of green fluorescent protein ex-pression under a fluorescence microscope indicated similar transfection efficiencies,and miRNA - 30c knockdown re-leased the activity of target gene Gli2. As a result,miRNA - 30c knockdown vector was constructed successfully(P ﹤0. 001). During differentiation of mouse P19 cells into myocardial cells,the beating cell clusters in miRNA - 30c knockdown cells were much lower than those in the control cells,and cTnT,NKX2. 5,GATA4 in miRNA - 30c knock-down cells showed significantly lower expression than those in the control cells( all P ﹤ 0. 05). Conclusions miRNA - 30c inhibits the P19 cell proliferation and differentiation. This study gives us a new insight of heart develop-ment and we need more efforts on exploring the deep function of heart diseases.

The initiation of lactation is the critical initial event contributing to breastfeeding. It is of great significance for maternal lactation and neonatal access to breast milk. However, various factors limit the successful initiation of lactation and increase the risk of poor neonatal prognosis. We provide an overview of the mechanism, significance, method, time, and factors that influence lactation initiation behavior, and summarize related guidelines aiming to gain more insight into the lactation initiation behavior to promote maternal lactation and improve neonatal prognosis.