Early vertebrate development & developmental genetics (lectures 22&23) Flashcards

Question

what are congenital malformations?

Answer 1

those already present at birth usually occur during embryogenesis congenital anomalies result from disruption of normal development can have genetic or environmental causes

Answer 2

first trimester in humans

Answer 3

chromosomal defects syndromes single genes multi-gene interactions

Answer 4

``` maternal diabetes fever prescription drugs recreational drugs pollutants dietary deficiencies/excesses ```

Answer 5

identify cause of malformation predict whether it is likely to happen again understand why specific factors lead to malformations devise strategies for preventing malformations

Answer 6

study of naturally occurring mutations in human and animal models utilised histological techniques to study how the defective structures formed and how they ended up

Answer 7

gross morphology - dissection histology embryos/tissues dehydrated embedded in paraffin wax thin slices cut different tissues/cell types visualised

Answer 8

understanding development tells us about normal development manipulation of developing embryos are used to ask specific questions and test hypotheses

Answer 9

removal of part of the embryo and looking at the consequences replacing one part of an embryo with another using a drug to interfere with a developmental process followed by anatomical analysis

Answer 10

congenital abnormalities are frequently caused by defects in genes have a lot of genetic information from studying families with congenital malformations basic science research has revealed many new genes that act in pathways

Answer 11

visualisation of gene/protein expression measurement of levels of gene/protein expression disruption of gene function • total knockout - in every cell of the embryo • conditional knockout - in cell types of choice ectopic or 'extra' gene expression - knockins and transgenes

Answer 12

powerful tool for showing where genes are active closely linked to anatomical approach gives spacial and temporal information crucial for linking genes to specific cell types mRNA and protein localisation is not always the same

Answer 13

in situ hybridisation - mRNA immunohistochemistry - protein linkage of gene regulatory elements to a reporter gene - transgenesis

Answer 14

creating a mouse with an inactive copy of the gene of interest 1) manipulate the DNA 2) transfer mutated DNA into mouse embryonic stem cells by transgenesis 3) incorporate transgenic ES cells into normal embryo 4) breed mice to obtain 'knockout' offspring

Answer 15

modified ES cell and host embryo have different coat colours 1) clone gene and put in bacteria 2) manipulate gene so its malfunctional 3) transfer into embryonic stem cells 4) transfer into an early embryo to be incorporated into the inner cell mass 5) transfer new embryo into a new mother which has a different coat colour to the original 6) allow offspring to be born 7) select embryos that have mixed coat colour 8) breed until you get offspring that are only the coat colour of the ES cells - these are the knockout mice takes 1-2 years

Answer 16

* uses synthetic RNA to guide enzyme (Cas9) to correct place in the genome * inject RNA and nucleases into fertilised embryos * cuts both DNA strands at the same time * can target multiple sites in the genome can generate transgenic/mutant twice in < 1 month cheap and efficient

Answer 17

can knockout gene of choice see what effects it has on the embryo complemented by anatomical analysis

Answer 18

the process where 3 germ layers are formed occurs in early development key process is formation of the embryo

Answer 19

lp mouse first described in 1948 gross morphology shows us that embryos are short and that neural tube closure is initiated histology revealed a broadened floor plane anatomical approach tells us what the main abnormalities are 1/1000 live births generally

Answer 20

will tying together the neural tube will lead to closure? ties threat around neural tube and Brough neural folds together followed by histological analysis did not result in neural tube closure

Answer 21

shown to be a component of a signalling pathway - Wnt dependent pathway regulates convergence-extension movements at gastrulation in vertebrates

Answer 22

* take place at gastrulation * occur by a process of cell intercalation * result in the narrowing and lengthening of the embryo * disruption leads to short fat embryos * disruption of PCP signalling in mice also causes neural tube defects

Answer 23

1/1000 babies have neural tube defects ``` now have identified mutations in PCP genes in human families with neural tube defects • Vangl1 • Scrib • Celsr1 • Prickle ``` allows genetic counselling

Answer 24

``` folic acid (B vitamin) can prevent some NTD • NTD seen in lp are not prevented by folic acid ``` inositol (another B vitamin) can prevent NTD in mice inositol is now in clinical trial for prevention of NTD in humans