What is Developmental Biology and How do we Research it? Flashcards
What is developmental biology?
Union of genetics and embryology
Preformation
All structures preformed and just grow in size
Epigenesis
New structures develop progressively during development
William Harvey
1st to use house mouse for study, seminal work in chick refuting spontaneous generation, and ovum is necessary.
Marcello Malpighi
Father of microscopic anatomy, supported preformation
August Weismann
Germ plasm theory: specific cells are different
Nuclear determinant theory: every cell has the same DNA
Ernst Haeckel
Proponent of preformation, proposed the recapitulation theory, and introduced concept of heterochrony (change in rate and timing of development which is an evolutionary shift)
Wilhelm Roux
Pioneer in experimental embryology, proponent of preformation, then mosaic epigenetist, most known for methods, all daughter cells are different and no other cell is exactly the same
Mosaic development:
Differential arrangement of localized nuclear determinants
Hans Driesch
Work in sea urchin helped refute preformation and nuclear determination, showed early blastomeres were capable of forming complete organisms separately, mosaic theory replaced by regulations, unequal distribution in the cytoplasm, and FATHER of totipotency/pluripotency
How did Hans Driesch found totipotency and pluripotency?
Separated cells at the two cell stage. One cell normally died, but the other cell survived and developed into a normal larva. Sometimes both survived and became individuals. This refutes nuclear determination, because it produced whole animals, not half. DNA is the same, but proteins and cytoplasm are different.
Hans Spemann
Proposed concept of induction, experimentally proved the concept in grafting experiments in amphibian embryos, he took small pieces of tissue and moved to other organisms and recorded what happened.
Hilde Mangold worked under Hans.
Gudrun Ruud
Pioneering work in regeneration and grafting, and work in salamander development
Kristine Bonnevie
Pioneer in chromosomal research, heredity, and inheritance.
Studies in polydactylism, dwarfism, and other disorders in isolated populations.
How do traits associate. Did bottleneck experiments on species and looked at what changed.
Karl Ernst von Baer
Prolific in areas of evolution and embryology, discovered blastula stage and notochord, cofounder of germ layer theory, and von Baer Laws.
Heinz Christian Pander
Cofounder of germ layer theory, chick development, and discovered conodonts
Joseph Needham
Chemical embryologist, investigated the concept of induction
Gavin de Beer
An early evo-devo researcher, seminal work in heterochrony (Paedomorphosis) and homology, credited with integrating developmental biology into the modern synthesis
Viktor Hamburger
Synonymous with chick development, “Hamburger-Hamilton Stages”, nerve growth.
J.B.S. Haldane
Coined the term “cloning”, introduced primordial soup, work in genetics and genetic linkage, Haldane’s principle on size
Ernest Everett Just
Pioneering work in invertebrates, fertilization, fast block to polyspermy, and parthenogenesis
Edward B. Lewis
Pioneering work in Drosophila, Hox genes (Bithorax), and complementation test
Rita Levi-Montalcini
Pioneer in chick development, focusing on nerve growth.
Discovered and isolated nerve growth factor
Stanley Cohen
Pioneer in growth factors, isolated nerve growth factor, and discovered epidermal growth factor.
Christiane Nusslein-Volhard
Nobel winner, Groundbreaking work in Drosophila, Chick, Zebrafish.
Hox, Hedgehog, Toll, and more she has had a hand in it.
Haploinsufficiency and Semi-dominance
Often not revealed until stressed during development. Wild type normal, heterozygous mutant deformed, and homozygous mutant lethal.
Recessive mutant
Often fatal. Wild type and heterozygous mutant are normal phenotypes with homozygous mutant leaving vestigial wings or fatal.
3 embryonic germ layers
Ectoderm (outer layer), mesoderm (middle layer), and endoderm (internal layer). Cell movement places layers in correct position within cell. Active cell differentiation rapidly increases.
Zygote to blastula to gastrula to germ layers or germ cells.
Ectoderm
Outer surface, epidermal cells of skin, central nervous system, neuron of brain, neural crest, pigment cell (melanocyte).
Mesoderm
Dorsal, notochord, paraxial, bone tissue, intermediate, tubule cell of the kidney, lateral, red blood cells, head, facial tissue.
Endoderm
Digestive tube, stomach cell, pharynx, thyroid cell, respiratory tube, lung cell.
Germ cell
Male sperm, female egg
How can we be sure what cells contribute to larval, juvenile, and adult structures?
Lineage tracing. Dye staining on embryos and genetically modifying model organisms (transgenic DNA)
In vivo
In a living organism
In vitro
In the lab
In situ
In the original place
What did transplantation experiments allow?
Lineage tracing via chimeras. ex. Chick-Quail
What can you add to sophisticate lineage tracing?
Fluorescent dyes
Which theory and author was von Baer’s laws directly refuting?
Ernst Haeckel Recapitulation Theory (developmental stages recapitulate adult evolutionary stages)
What do transitional forms do, both fossil and living?
Give insight into the changes in developmental processes over time and space.
What do changes in form allow us to make predictions on?
How major phenotypics changes came to be, and test these hypotheses using model species.
Homology
Denotes sameness. Denotes inheritance (structures, organs, genes, etc.) through shared common ancestry. Ex. vertebrate forelimb, which is composed of the same bones in all vertebrates, regardless of function. Structures that are similar due to function (convergent), but not shared inheritance, are analogous (homoplasious)
