INTRODUCTION TO DEVELOPMENTAL BIOLOGY Flashcards
the study of the process by which organs grow and develop
synonymous with ontogeny
Developmental Biology
CONCERNS OF DEVELOPMENTAL BIOLOGY
- Changes with time on life scale
- Ontogenetic development
- Embryogenesis - Changes in form and function
- “Morphogenesis”
- Biochemistry - Integrative and Eclectic (wide-ranging)
WHY IS DEVELOPMENTAL BIOLOGY IMPORTANT?
- Can help in sustaining food resources (SDG 1 & 2) = improve crop and plant cultivation
- Developmental defects in humans are very abundant (SDG 3) = address major population health challenges.
- Developmental Biology is a generator of new ideas and concepts (by asking fundamental questions)= underpins modern biomed sciences
- Reaches across the different levels of biological complexity and explanation = tracing back to events at the level of genes & cells (Organismal -> Cellular)
- Makes strategic use of suitable animal models
Specific questions scrutinized by developmental biologists
- Differentiation (ex. Pax6 gene - Pancreas, lens and cornea, neural tube, retina)
- Pattern formation (ex. Zebrafish - gradient, induction)
- Morphogenesis (ex. Frog - provide spatial information)
- Growth (Teratogens)
- Reproduction
- Environmental Integration
- Regeneration
- Evolution
- Human Development
The ultimate stem cell
Zygote - a fertilized egg
A historical approach to embryology that uses experimental methods to study the development of embryos
Classical embryology
process by which the presence of one tissue influences the development of others
Induction
How do our cells know when to stop dividing?
when they receive chemical signals from other cells, or when their telomeres shorten to a critical length
How come our arms are are
generally the same size on both
sides of the body?
Hox genes
How is cell division so tightly
regulated?
Cyclins and CDKs
Cell checkpoints
Chemicals that disrupt normal development
Teratogens
Why some organisms can
regenerate every part of their
bodies?
Stem cells
the study of how environmental factors and behaviors can change gene activity without altering DNA sequences
Epigenetics
one of the first to allude to the
concept of preformationism
Hippocrates
a theory that organisms develop from miniature versions of themselves
Embryonic structures are preformed within the gamete
(either egg or sperm)
preformation
Credited with 1st notions on embryology
“On the generation of animals”
Studied embryos of different organisms
Aristotle
embryonic structures arise anew from the interaction of substances within the gametes
Epigenesis
Visualized epigenesis of embryonic germ layers
studied the chick embryo
Christian Pander
father of Modern Embryology
described notochord, discovered mammalian egg, proposed 4 laws of development
Karl Ernst von Baer
________ gene is an important tillering/branching-related transcription factor gene that regulates tillering by integrating environmental and developmental cues
teosinte branched 1 (tb1)/CYC
2 major accomplishments in development
- Differentiation - unicellularity to multicellularity
- Ensuring continuity of life
a birth defect that causes the complete absence of one or more limbs
Amelia
- The more general characters of a large group appear earlier in the embryo than the more special characters.
- From the most general forms, the less general forms are developed, and so on, until finally, the most special forms arise.
- Every embryo of a given animal form, instead of passing through the other forms, rather becomes separated from them.
- Fundamentally, therefore, the embryo of a higher form never resembles any other form, but only its embryo.
Baer’s Laws
Experimental Approaches
Defect experiments
Isolation experiments
Recombination experiments
Transplantation experiments
is a DNA sequence found within genes that regulates developmental processes in animals, fungi, and plants.
Homeobox
are an evolutionary highly conserved gene family. They determine the anterior-posterior body axis in bilateral organisms and influence the developmental fate of cells.
Hox genes
DEVELOPMENTAL OUTCOMES—— THROUGH CELLULAR INTERACTION
Cell signaling
Cell proliferation
Cell Movement
COMMON CONSIDERATIONS IN CHOOSING A GOOD MODEL SYSTEM
- Size
- Generation time
- Embryo accessibility
- Feasibility of genomic interrogation
- Organism type & genetic position
- Ease of experimental manipulation
a chemical signal that controls how tissues develop and which cell types are in what positions
Morphogen
Origins of plant embryos
Egg cell
Microspore
Somatic cell
Callus cell = cells that cover a plant wound
Genetic screens in worms and flies led to discovery of __________________signaling pathways
notch
BMP
hedgehog
Wnt
Basis of Developmental Biology Research
Find it (correlative)
Lose it (loss of function)
Move it (gain of function)
stem of germinating seedling
hypocotyl
seed leaves
cotyledon
In deuterostomes, blastopore becomes the
e. Echinoderms and ancestors of chordates
anus
In protostomes, the first opening is the
mouth
takes into consideration the genetic control of cell growth, differentiation and morphogenesis, which is the process that gives rise to tissues, organs and anatomy, but also regeneration and ageing.
Modern Developmental Biology
the causal analysis of the cellular mechanisms that drive processes of growth, pattern formation, and morphogenesis.
includes new syntheses with evolution, molecular biology, advances in molecular developmental genetics, and signaling pathways.
Developmental Biology
Embryology vs. Developmental Biology
Embryology
- observational biology
- experimental manipulations
- part of Developmental Biology
Developmental Biology
- expands embryological studies using molecular techniques
- used genetic approaches to study model systems
- More encompassing
Life cycle in diploid organism
- Fertilization
- Zygote
- Embryo
- Individual
- Meiosis
- Gametes
- Individual and germ line
Ectoderm forms the …
Outer surface
CNS
Neural Crest
Endoderm forms the…
Digestive tube
Pharynx
Respiratory tube
Mesoderm forms the…
Dorsal
Paraxial
Intermediate
Lateral
Head
Development of an organism is ultimately driven by the regulated expression of its genes, determining which proteins are present in which cells and when
Model Systems for Developmental Biology
Arabidopsis thaliana
Drosophila melanogaster
Hydra vulgaris
Caenorhabditis elegans
Xenopus laevis
Danio rerio
Gallus gallus
Mus musculus
Stem cell blastocyst (Homo sapien)
The circle of life
Gametogenesis
Fertilization
Cleavage
Gastrulation
Organogenesis
Larval stage
Maturity
Cavity in gastrula
Archenteron cavity
How can developmental biology help feed a growing population?
Adoption of semi-dwarfed crop species in agriculture.
ex. Semi-dwarfed rice, wheat & barley (Green Revolution of the 1960s/1970s)
Elucidation of the gibberellin (GA)-dependent control of growth in model species.
Fundamental understanding of developmental processes/traits guides crop improvement.
An estimated 240 000 newborns die worldwide within 28 days of birth every year due to congenital disorders. Congenital disorders cause a further 170 000 deaths of children between the ages of 1 month and 5 years (WHO, 2023).
Top 10 Birth Defects Among Neonates Born at the Philippine General Hospital from January 2011 to December 2014
Give 5
Q90 = Down syndrome
Q37 = Cleft palate with cleft lip
Q03 = Congenital hydrocephalus
Q66 = Congenital deformities of feet
Q91 = Edwards and Patau syndrome
The 3rd and 4th law of Baer contradicts ___________, the repetition of an evolutionary or other process during development or growth
Recapitulation
STEM CELLS AND THEIR AMAZING POTENTIAL
- Modeling diseases
- Neural diseases
- Blood diseases
- Regenerative medicine
- Ethics and policy
- Cloning and reprogramming
Synthetic Developmental Biology
a. Organoids from TDCs
b. Organoids from iPSCs
HOW DEVELOPMENT WORKS?
- Regional specification
- Pattern formation
- Cell Differentiation
- Morphogenesis
- Growth
Embryonic period (weeks 1-8)
Week 1 & 2 = Cleavage and Implantation
Week 3 = Heart, CNS, Embryo attached to placenta
Week 4 & 5 = Eyes, Heart, Limbs
Week 6 = Teeth, Ears
Week 7 = Palate, External genitalia
Week 8 = Brain, Spinal cord
Fetal period (weeks 9-38)
Week 9 - 16 = Continuous growth
Week 27-38 = Third trimester (fetus viable)
Week 38 = Full term
