DASAR-DASAR MORFOGENESIS

Morfogenesis Proses biologis yang menyebabkan organisme berkembang bentuknya Aspek dasar dari bioper: morfogenesis, tumbuh dan diferensiasi Proses pengaturan tersebut terjadi selama perkembangan embrio menjadi organisme dewasa

Pola perkembangan stadium I Pola perkembangan stadium II Pengaturan waktu Intensitas masa

PERKEMBANGAN Perkembangan sebelum lahir/menetas Urutan peristiwa morfogenetik awal Mekanisme pengaturan → organisasi dari kompleks sampai tingkat molekular

Sel → Jaringan → Organ Organisme Sistem organ : Pencernaan makanan Saraf Pernafasan Reproduksi Transportasi, dll

TERDIRI DARI 2 PERIODE : PERTUMBUHAN ANTARA PERTUMBUHAN AKHIR 1. PERIODE PERTUMBUHAN ANTARA TERJADI TRANSFORMASI DAN DIFERENSIASI BAGIAN-BAGIAN TUBUH EMBRIO DARI BENTUK PRIMITIF, SEHINGGA BENTUK YANG DEFINITIF SUATU SPESIES (BENTUK KATAK, AYAM ATAU SAPI, TINGKAT BERUDU / LARVA)

2. PERIODE PERTUMBUHAN AKHIR PENYELESAIAN BENTUK DEFINITIF MENJADI BENTUK INDIVIDU (PERTUMBUHAN JENIS KELAMIN, WAJAH INDIVIDU YANG KHAS) PADA AVES, REPTIL DAN MAMALIA : BATAS ANTARA KEDUA PERIODE TERSEBUT TIDAK JELAS

Morfogenesis diinduksi oleh: hormon Kimia lingkungan (toxic chemicals) dari polutan Induksi stres mekanik Morfogenesis terjadi di: Embrio Organisme dewasa Kultur sel Sel tumor

Dasar-dasar Molekular Molekul yang penting selama morfogenesis: Molekul morfogen, ciri: Morfogen → bentuk cair, dapat difusi dan pembawa sinyal untuk pengaturan diferensiasi sel, dapat mengikat reseptor protein spesifik, protein faktor transkipsi untuk mendeterminasi sel melalui interaksi dengan DNA, merupakan molekul yang mengatur perlekatan sel, misal: selama gastrulasi, kelompok stem sel, migrasi, dan pembentukan jaringan – organ baru

Dasar selular Sel hidup (merah) banyak mengandung E-cadherin (molekul perlekatan sel (cell adhesion molecules, CAMs), sel hidup (hijau) sedikit Live cells were stained with either Dil (red) or DiO (green). The red cells were genetically altered and express higher levels of E- cadherin (). than the green cells. After labeling, the two populations of cells were mixed and cultured together allowing the cells to form large multi-cellular mixed aggregates. Individual cells are less than 10 m in diameter

Morphogenesis arises because of changes in the cellular structure or how cells interact in tissues The ability of cells to do this comes from differential cell adhesion. Two well-studied types of cells that sort out are epithelial cells and mesenchyme cells During embryonic development cellular differentiation (mesenchymal cells become epithelial cells) Following epithelial-mesenchymal transition, cells can migrate away from an epithelium and then associate with other similar cells in a new location.

Adhesion During embryonic development → cells sort out in different layers due to differential adhesion The same cell-to-cell adhesion molecules separate from cells that have different adhesion molecules. Cells sort → differences in adhesion between the cells, so two populations of cells → different levels

In culture cells →the strongest adhesion move to the center of a mixed aggregates of cells The molecules responsible for adhesion are are cadherins There are dozens of different cadherins that are expressed on different cell types. Cadherins bind to other cadherins in a like-to- like manner: E-cadherin (found on many epithelial cells) binds to other E-cadherin molecules. Mesenchymal cells usually express other cadherin types such as N-cadherin.

Extracellular matrix The extracellular matrix (ECM) → separating tissues, providing structural support or providing a structure for cells to migrate on ECM molecules: collagen, laminin, and fibronectin are secreted and assembled into sheets, fibers, and gels. Multisubunit transmembrane receptors called integrins are used to bind to the ECM.

Integrins bind: extracellularly to fibronectin, laminin, or other ECM components intracellularly to microfilament-binding proteins - actinin and talin to link the cytoskeleton with the outside. Integrins also serve as receptors to trigger signal transduction cascades when binding to the ECM

MORPHOGENESIS

TERIMA KASIH ATAS PERHATIANNYA alfiahayati@unair.ac.id