Tissue invagination drives embryo remodeling and assembly of internal organs during animal development. While the role of actomyosin­mediated apical constriction in initiating inward folding is well established, computational models suggest relaxation of the basal surface as an additional requirement. However, the lack of genetic mutations interfering specifically with basal relaxation has made it difficult to test its requirement during invagination so far. Here we use optogenetics to quantitatively control myosin­II levels at the basal surface of invaginating cells during Drosophila gastrulation. We show that while basal myosin­II is lost progressively during ventral furrow formation, optogenetics allows the maintenance of pre­invagination levels over time. Quantitative imaging demonstrates that optogenetic activation prior to tissue bending slows down cell elongation and blocks invagination. Activation after cell elongation and tissue bending has initiated inhibits cell shortening and folding of the furrow into a tube­like structure. Collectively, these data demonstrate the requirement of myosin­II polarization and basal relaxation throughout the entire invagination process.

제 1편 : 코로나-19의 정의
1. 코로나바이러스감염증-19(COVID-19) 정보 7
2. 코로나바이러스 분류 및 특성 9
3. 코로나 바이러스 전자현미경 형태 11
4. 코로나바이러스 구조 (Covid-19 Organization) 13
5. 코로나19: 환경에 지속적인 영향을 미칠까? 19
6. 치료법(Therapeutical Method) 22
제 2편 : 연구논문
Herd immunity and a vaccination game: An experimental study
Abstract 23
Introduction 23
Methods 24
Procedures 28
Results 30
Supporting information 28
References 36