정태민 교수

Growing pig oocytes (< or = 90 microns in diameter) are unable to resume meiosis in vitro. The objective of our present experiments has been to identify the reasons for meiotic competence in these cells. By comparing histone H1 kinase activity in growing and fully grown oocytes we demonstrate that incompetence is associated with an inability to activate H1 kinase in growing oocytes. Immunoblotting was used to determine whether this kinase inactivity resulted from a lack of either p34cdc2 protein

Cell fusions have been used to determine the biological activity of the MPF complex in murine oocytes during their progression through anaphase and telophase to metaphase II. Oocytes (1) at metaphase I, (2) during the anaphase-telophase transition, or (3) at metaphase II were fused to germinal vesicle-staged (immature) oocytes. The hybrids were cultured for 1 h in the presence of db cAMP before fixation and nuclear evaluation. Metaphase I oocytes invariably induced germinal vesicle breakdown (GV

Bovine oocytes were irradiated at germinal vesicle (GV) or metaphase II (MII) stage, after Hoechst staining, with chromosomally focused UV-C (254 nm) or UV-A ( > 330 nm). UV-C irradiation at GV stage did not inhibit germinal vesicle breakdown (GVBD) or chromosomal condensation; spindle formation was abolished and maturation promoting factor (MPF) levels failed to increase. UV-A irradiation at GV stage caused meiotic arrest at anaphase I; MPF levels were lower than control. UV-C irradiation at MI

The approval of immune checkpoint inhibitors (ICI) that serve to enhance effector T-cell anti-tumor responses has strongly improved success rates in the treatment of metastatic melanoma and other tumor types. The currently approved ICI constitute monoclonal antibodies blocking cytotoxic T-lymphocyte-associated protein (CTLA)-4 and anti-programmed cell death (PD)-1. By this, the T-cell-inhibitory CTLA-4/CD80/86 and PD-1/PD-1L/2L signaling axes are inhibited. This leads to sustained effector T-cel

In vitro maturation of cumulus enclosed and denuded pig oocytes was reversibly inhibited by the protein kinase inhibitor genistein. The half-maximal effect on maturation was observed at 40 micrograms ml-1. Genistein inhibited total protein phosphorylation and synthesis with the same dose-response relationship (ED50: 40 micrograms ml-1). Protein phosphorylation and synthesis patterns were changed by effective concentrations of genistein. Pig oocytes were sensitive to genistein during the first 12

The advent of mitogen-activated protein kinase (MAPK) inhibitors that directly inhibit tumor growth and of immune checkpoint inhibitors (ICI) that boost effector T cell responses have strongly improved the treatment of metastatic melanoma. In about half of all melanoma patients, tumor growth is driven by gain-of-function mutations of BRAF (v-rat fibrosarcoma (Raf) murine sarcoma viral oncogene homolog B), which results in constitutive ERK activation. Patients with a BRAF mutation are regularly t

Maturation promoting factor (MPF) is universally recognized as the biological entity responsible for driving the cell cycle from G2- to M-phase. Histone H1 kinase activity is widely accepted as a biochemical indicator of p34cdc2 protein kinase complex activity and therefore MPF activity. In this paper we present results which indicate that during the G2- to M-phase transition in mouse oocytes the dynamic of p34cdc2 related histone H1 kinase activity differs markedly from the biological activity

Normal oocyte maturation depends on signal transmission between granulosa cells and the oocyte. We have analysed the effects of inhibiting (I) cyclic AMP-dependent protein kinase (protein kinase A, PK-A), (II) Ca2+/phospholipid-dependent protein kinase (protein kinase C, PK-C) and (III) calmodulin (CaM) on pig oocyte maturation in vitro, protein synthesis and phosphorylation. The inhibition of PK-A using a specific inhibitor H8, decreased the maturation rate (rate of germinal vesicle breakdown,

The Benefit Corporation (B-Corp) movement in South Korea aims to integrate social and environmental objectives into corporate missions. However, a significant number of firms fail to renew their certifications. Thus this study explores how the articulated corporate purposes of certified South Korean B-Corps differ from those that have decertified, suggesting that the sustainability of B-Corp status is contingent upon the fit between the B-Corp model's demands and a firm's specific strategic orie

기업의 역량이 개방형 혁신의 과정에서 수행하는 역할에대한 폭넓은 연구가 이루어져 왔으며, 기업가 지향성은 일반적으로 혁신을 촉진하는 긍정적요인으로 간주되어 왔다. 그러나 이러한 관점은 자원조율에 수반되는 잠재적 비용을간과한다는 점에서 한계를 갖는다. 이에 본 연구는 자원조율이론에 기반하여 기업가지향성의 부정적 측면을 조명한다. 특히 기업이 자원을 특정 전략적 지향성에 강하게집중할수록, 해당 전략적 지향성이 특정 외부지식의 원천과 부합하지 않을 경우 ‘조율불일치’를 초래할 수 있음을 제시한다. 본 연구는 이를 위해 외부지식 탐색을 지식의 특성에따라 시장 중심적 탐색과 과학 중심적 탐색으로 구분하고, 기업가 지향성이 이러한 탐색전략과상품혁신 간의 관계를 어떻게 조절하는지 분석하였다. 2020년 한국기업혁신조사에 참여한2,353개의 제조기업을 대상으로 로짓 분석을 수행한 결과, 기업가 지향성은 양면성을 지니는것으로 나타났다. 구체적으로, 기업가 지향성은 시장 중심적 탐색과 급진적 상품혁신