Lecture 1 - Intro + Neural Development

Question 1

How much of the overall bodily energy does the brain use?

Answer 1

20% - a selfish organ
(liver will even break itself down to give the brain energy)

Question 2

Can we tell what exactly every neuron in the nervous system can do?

Answer 2

with the exception of the retina - no we cannot

Question 3

How many total human genes are in the genome? How many are ubiquitous? How many are only in the brain and how many are not expressed in the brain?

Answer 3

Total - 20,000 genes
Brain - 6,000 genes
Ubiquitous - 8,000 genes
Not in brain - 6,000 genes

Question 4

What are the ionic concentration of the sea (high sodium, low potassium and high calcium) similar to?

Answer 4

our blood or ecf

Question 5

Where did calcium come from in our blood?

Answer 5

limestone deposits brought calcium into the sea

Question 6

Why is calcium concentration low in our cells?

Answer 6

-calcium in the cell is cytotoxic because it can form precipitates with phosphates and that is why nature made us have low conc. and exploits this to make calcium a secondary messenger

Question 7

What is the soma of a neuron?

Answer 7

cell body or control center

Question 8

What is the dendrite of a neuron?

Answer 8

signal input

Question 9

What is the axon of a neuron?

Answer 9

specialized for long range electrical trasnfer

Question 10

What is the synapse of a neuron?

Answer 10

output - transfer elec info into chemical and back into elec

Question 11

What are some of the key experimental organisms and techniques used in molecular neuroscience?

Answer 11

model systems - drosophilia, worms, rodents
genetics - drosophilia
-development - frog xenpus oocyte and chick embryo because they are very malleable

Question 12

What are the developmental axes?

Answer 12

the rostral-caudal axis

Question 13

What are the three germ layers and at what stage of development are we at when they are present?

Answer 13

ectoderm, mesoderm, endoderm
-later than a blastocyst 5-10 days after conception

Question 14

What does the ectoderm form?

Answer 14

forms the nervous system, exoskeleton, skin, CNS and PNS

Question 15

What does the mesoderm form?

Answer 15

develops into organs and muscles, connective tissue and vascular system

Question 16

What does the endoderm form?

Answer 16

the inner lining or organs; such as the digestive tract from the mouth to the anus; lung, pancreas, liver

Question 17

What are the three primary model systems in development and why?

Answer 17

-chick embryos - have a three week development cycle so can take the embryo out manipulate it and put in
-xenopus frog oocyte - cheap, translucent and easy to manipulate
-mice (later in genetics)

Question 18

In human development when do you have the nervous system?

Answer 18

-within a month

Question 19

Humans and flies look similar in what stages of development?

Answer 19

in the earlier stages (up to stage 18 or 19) and then they diverge

Question 20

When does nervous system development occur in mice and humans?

Answer 20

mice - the first and second week
humans - first and second month

Question 21

At one month in a human or 2 weeks in a mouse what two flexures are present and what do they become?

Answer 21

-cephalic flexure - forebrain, midbrain, and part of the hindbrain
-cervical flexure - remaining hindbrain and psinal cord

Question 22

If you stain for a ubiquitous nervous system gene where will you see regionalization occur?

Answer 22

in the ectoderm

Question 23

What are the key events that underlie morphogenesis of the nervous system early in development?

Answer 23

-the regionalization of the neural tube

Question 24

What does the ectoderm give rise to and what is it a precursor of?

Answer 24

neural plate - precursor of the CNS and PNS

Question 25

What does the neural plate do to form the neural groove?

Answer 25

invaginate

Question 26

What does the neural plate once it has invaginated to form the neural groove do to form the neural tube?

Answer 26

-buckles at its midline to form the neural tube

Question 27

What folds close to form the neural tube?

Answer 27

the dorsal neural folds

Question 28

What does the neural tube lie over and what does it do?

Answer 28

the notochord - forms the vertebral column or bones of spinal cord -send Shh signals to differentiate dorsal versus ventral neurons

Question 29

What is the neural tube flanked by?

Answer 29

somites - they are mesodermal cells which give ruse to muscle and cartilage - send signals to differentiate anterior and posterior

Question 30

What gives rise to three vesicles in the neural tube and when do you see this in mice?

Answer 30

-differences in the rate of cell proliferation -one week in mice

Question 31

What are the three vesicles the neural tube gives rise to?

Answer 31

-proencephalon - forebrain -mesencephlon - midbrain -rhombencephalon - hindbrain

Question 32

At what stage in mice does the three vesicle neural tube give rise to five vesicles?

Answer 32

2 weeks in mice

Question 33

What does the forebrain become during the five vesicle stage?

Answer 33

diencephalon and telencephalon

Question 34

What does the midbrain become during the five vesicle stage?

Answer 34

remains as the mesencephalon or midbrain

Question 35

What does the hindbrain become during the five vesicle stage?

Answer 35

metencephalon (pons and cerebellum) myelencephalon (medulla)

Question 36

What drives the progressive patterning and subdivision of cells and tissues in the brain?

Answer 36

many secreted molecules; every cell is drive to become something by default - how do you interrupt the default program and cause it to become something else -the default is female but signals secrete to become male

Question 37

What is the yin and yang of life or biology and how do you interrupt it?

Answer 37

all biological processes are programmed by default to do or become something -can inhibit an activator or inhibit and inhibitor

Question 38

What is the organizer region?

Answer 38

-plays an instructive role early in differentiation -dorsal ectoderm; causes nervous system differentiation

Question 39

If you take from a donor embryo of a frog xenopus oocyte and organizer region from the dorsal ectoderm what will happen to the receiving transplanted embryo?

Answer 39

two neural tubes will be developed so the organizer region is important in playing a role of the early nervous system organization

Question 40

What are ectodermal cells supposed to be if there is nothing present?

Answer 40

neural tissue

Question 41

If BMP is secreted from the ventral mesoderm then what to ectodermal cells become?

Answer 41

epidermal cells or skin cells

Question 42

If BMP inhibitors are being secreted from the organizer region or dorsal ectoderm what do the ectodermal cells become even if BMP is being secreted from the ventral mesoderm?

Answer 42

neurons again

Question 43

What are BMPs or bone morphogenetic proteins?

Answer 43

BMPs: group of growth factors and they play key role in morphogenetic signaling -secreted proteins that are secreted out of cells and they signal active properties to other cell -the first cells that were cloned were found to induce bond formation and a mutation that lead to constitutively active BMP lead random cells to be constantly instructed to become bone

Question 44

What is mediated by peptide growth factors (BMPs) and their inhibitors (follistatin, chordin, nogin)?

Answer 44

neurons

Question 45

What is the organizer region generating?

Answer 45

BMP inhibitors

Question 46

What do ventral mesodermal cells and the ectoderm secrete?

Answer 46

BMP

Question 47

What do the cells become in the presence of BMP?

Answer 47

skin cells

Question 48

What do the cells become in the presence of BMP inhibitors or no BMP?

Answer 48

neurons

Question 49

What is the default program of all ectodermal cells?

Answer 49

neurons

Question 50

If BMP is present what do ectodermal cells become?

Answer 50

skin cells

Question 51

If BMP inhibitors are present what do the cells become?

Answer 51

neurons

Question 52

What turns on the secretion of BMPs from part of the ectoderm and ventral mesoderm?

Answer 52

Transcription factors

Question 53

How do BMP inhibitors work and what are some examples of them?

Answer 53

they are secreted from the organizer region of the dorsal ectoderm and bind to BMP and block the ability of ectodermal cells to become skin -chordin, noggin, follistatin

Question 54

What promotes epidermal cell fate?

Answer 54

BMPs

Question 55

If you take the ectoderm that is not the organizing region and leave those cells in a petri dish what do they become?

Answer 55

skin cells

Question 56

If you take the ectoderm that is not the organizing region and leave those cells in a petri dish what do they become then add BMP inhibitors what do they become?

Answer 56

neurons

Question 57

If you dissociate the cells what do they become and why?

Answer 57

neurons because the BMP concentration is not high enough when they are not close together to make them skin cells