Key terms and concepts developmental biology
Lecture 1: Introduction
Basic concept of development: key terms and concepts
Drosophila development
Syncytium, blastoderm, imaginal disc
Role of RNA transport, regulation of translation and protein diffusion
Maternal, gap, pair-rule, segmentation and selector genes
Forward genetics
Drosophila versus vertebrate life cycle
Blastula, gastrula, neurula
Patterning, body axes (A-P, D-V)
Germ layers (endoderm, mesoderm, ectoderm)
Fate, induction, determination, mosaic, regulative
Practice questions
1) What is syncytium and how does it influence the early development of drosophila?
nuclei without cell membranes, allowing for diffusion of proteins to pattern the embryo
2) What is the essence of forward genetics screens?
Introduction of random mutations, followed by screening of phenotypes
3) How do you know you have reached saturation (al genes identified) in a forwards genetics
screen?
most genes that you do find, you find more that once
4) Most of the variation in embryonic cell division time between species may be best
explained by:
External (can be related to egg size) vs. intra-uterine development
5) Order the following embryonic stages according to their number of cells, from the lowest
to the highest
Blastula, Gastrula, Neurula
Lecture 2: origin and specification of the germ layers in vertebrates 1
Practice questions
1) What are the hallmarks of the maternal to zygotic transition?
new transcription followed by degradation of maternal mRNAs
2) Which axes are maternally determined in Xenopus (in the oocyte), and which are specified
in the embryo?
Animal-vegetal is maternally determined, dorsal-ventral and anterior-posterior specified in
the embryo. (dorsal-ventral events are before the maternal to zygotic transition)
3) If xenopus embryos are bisected in ventral and dorsal halves at the four cell stage, what
will happen?
The ventral half will not develop axial structures or a head
4 cell stage: relocation of dorsal half, in the dorsal half you have Wnt-signaling which leads to
B-catenin nuclear accumulation. The ventral half is missing out on that so you won’t get axial
structures or a head.
1
, How will the dorsal side look: it will be a smaller embryo, relatively large head but small
belly. It will be dorsalized (strong influence of dorsal signal) very dominant dorsal features
and abdominal ventral features.
Lecture 3: origin and specification of the germ layers in vertebrates 2
Overview first part of this lecture: Understand what all these components in the picture below mean
(patterning of the mesoderm) and you understand the concept of mesoderm patterning.
Summary vertebrate axis determination
Origins dorso-ventral and anterior-posterior axis
ICM = inner cell mass > embryonic vs abembryonic axis.
Key terms and concepts
Origin and specification of the germ layers in vertebrates
Germ layers and germ layer derivatives
Regulative versus mosaic development
Maternal to zygotic transition, zygotic genome activation
Animal-vegetal polarity (Xenopus, Zebrafish)
Role of maternal RNA localization
Dorsal-ventral (D-V) axis determination Xenopus, Zebrafish
- Dorsal determinants, cortical rotation
2
Lecture 1: Introduction
Basic concept of development: key terms and concepts
Drosophila development
Syncytium, blastoderm, imaginal disc
Role of RNA transport, regulation of translation and protein diffusion
Maternal, gap, pair-rule, segmentation and selector genes
Forward genetics
Drosophila versus vertebrate life cycle
Blastula, gastrula, neurula
Patterning, body axes (A-P, D-V)
Germ layers (endoderm, mesoderm, ectoderm)
Fate, induction, determination, mosaic, regulative
Practice questions
1) What is syncytium and how does it influence the early development of drosophila?
nuclei without cell membranes, allowing for diffusion of proteins to pattern the embryo
2) What is the essence of forward genetics screens?
Introduction of random mutations, followed by screening of phenotypes
3) How do you know you have reached saturation (al genes identified) in a forwards genetics
screen?
most genes that you do find, you find more that once
4) Most of the variation in embryonic cell division time between species may be best
explained by:
External (can be related to egg size) vs. intra-uterine development
5) Order the following embryonic stages according to their number of cells, from the lowest
to the highest
Blastula, Gastrula, Neurula
Lecture 2: origin and specification of the germ layers in vertebrates 1
Practice questions
1) What are the hallmarks of the maternal to zygotic transition?
new transcription followed by degradation of maternal mRNAs
2) Which axes are maternally determined in Xenopus (in the oocyte), and which are specified
in the embryo?
Animal-vegetal is maternally determined, dorsal-ventral and anterior-posterior specified in
the embryo. (dorsal-ventral events are before the maternal to zygotic transition)
3) If xenopus embryos are bisected in ventral and dorsal halves at the four cell stage, what
will happen?
The ventral half will not develop axial structures or a head
4 cell stage: relocation of dorsal half, in the dorsal half you have Wnt-signaling which leads to
B-catenin nuclear accumulation. The ventral half is missing out on that so you won’t get axial
structures or a head.
1
, How will the dorsal side look: it will be a smaller embryo, relatively large head but small
belly. It will be dorsalized (strong influence of dorsal signal) very dominant dorsal features
and abdominal ventral features.
Lecture 3: origin and specification of the germ layers in vertebrates 2
Overview first part of this lecture: Understand what all these components in the picture below mean
(patterning of the mesoderm) and you understand the concept of mesoderm patterning.
Summary vertebrate axis determination
Origins dorso-ventral and anterior-posterior axis
ICM = inner cell mass > embryonic vs abembryonic axis.
Key terms and concepts
Origin and specification of the germ layers in vertebrates
Germ layers and germ layer derivatives
Regulative versus mosaic development
Maternal to zygotic transition, zygotic genome activation
Animal-vegetal polarity (Xenopus, Zebrafish)
Role of maternal RNA localization
Dorsal-ventral (D-V) axis determination Xenopus, Zebrafish
- Dorsal determinants, cortical rotation
2
