BIOS 484 - Exam 4

Retinoic acid

Inductive signal during early brain development, derived from vitamin A

Fibroblast growth factor

Peptide growth factor that acts as an inducer during early brain development

MAP kinase activation

Leads to the altered expression of target genes and plays a key role in cell signaling pathways

Bone morphogenetic proteins

Peptide hormones that regulate neural induction and differentiation

BMPs in mesodermal cells

Involved in bone growth

BMPs in ectodermal cells

Involved in skin growth and neural development

Noggin and Chordin

Endogenous antagonists that prevent BMPs from binding to receptor proteins, interacts from the roofplate and released from the notochord

Neuroectoderm and BMP interaction

The “default” state of neuroectoderm is to become epidermis with the help of BMP binding. Noggin and Chordin prevent BMP binding, leaving the neuroectoderm to continue to develop into neural tissue instead of skin

Sonic hedgehog

Inductive signaling hormone responsible for closing the neural tube, differentiation of neurons in the spinal cord, and axon growth and synapse formation, interacts from the floorplate

Transcriptional code

Combination of transcription factors necessary to establish the identity of a specific neuron class

Neuroblasts

Immature nerve cells that differentiate into neurons

Radial glial cells

Glial cells that connect the luminal and pial surfaces of the neural tube to create a pathway for neuronal migration

Asymmetrical neural stem cell division

One daughter cell becomes a postmitotic neuroblast while the other remains a progenitor cell

Delta-Notch signaling

Delta ligands bind to Notch cell surface receptors, involved in neuronal differentiation of neural stem cells

Neurons and cortical layers

Neurons are generated first on lower cortical levels and later generations migrate to upper layers

Epithelial-to-mesenchymal transition

Initiates cell motility within multiple tissues

EphR/Ephrin signaling function

Repels growth cones

Protocadherin function

Gives rise to thousands of isoforms through differential splicing, plays a role in synapse identity

Growth cone motility

Guides axons in developing nervous system, driven by ATP-dependent modifications of the growth cone cytoskeleton and regulated by actin polymerization

Microtubules

Responsible for axon elongation and transporting new receptors, channels, signaling molecules, and vesicles

ECMs

Secreted cell adhesion molecules that bind to integrins and influence peripheral neuron guidance along the basal lamina

Calcium dependent cadherins

Form homophilic interactions that bundle axons and play a role in synaptogenesis

Chemorepellents

Causes turning away from a signal

Semaphorins

Attractants for outgrowing dendrites and a repellant for axons

Netrin

Attracts axons that express DCC receptors to form a commissure across the midline, localized to the floorplate

Sli/Robo function

Silences netrin attraction after the commissural neurons cross the midline

Ventricular zone

Contains neural stem cells, beginning of neurogenesis

Intermediate zone

Located outside of the ventricular zone, where post-mitotic neurons migrate to and form CNS grey matter

Marginal zone

Located outside of the intermediate zone, contains axonal region and CNS white matter

Reelin function

Responsible for neuron detachment from radial glia

Delta-Notch mechanism

Lateral inhibition: cells with high Delta levels inhibit neighboring cells through higher Notch signaling. This inhibits the neighboring cells’ differentiation and allows the Delta-expressing cell to become a neuron

Cranial nerves

12 pairs, carries information in and out of the brain

Spinal nerves

31 pairs, carries sensory information into the spinal cord and motor commands out of the spinal cord

Autonomic nervous system components

Sympathetic (fight/flight), parasympathetic (rest/digest), enteric (gastrointensinal)

Chordate features

Gill (pharyngeal) slits, a notochord, a hollow dorsal nerve cord, and a post-anal tail

Notochord

Stiffening rod, gives rise to the vertebral column

Blastulation

Formation of the blastocyst

Gastrulation

Formation of germ layers: ectoderm, mesoderm, and endoderm

Notochord formation

The migrating epiblast turns inwards at Hensen’s node and forms the notochord, elongates to form the primitive streak

Notochord germ layer

Mesoderm

Neurulation germ layer

Ectoderm

Neurula

Embryonic stage where neural tube is formed

Neurulation formation direction

Rostral to caudal (head to tail)

Somites

Precursors of musculature, skeleton, and vertebral column/spine

Neural crest cells

Specifies the peripheral nervous system, emerges from the roofplate

Organizer region

Important for induction of the nervous system from an undifferentiated blastulae region, experiments where the organizer region of a donor embryo was implanted in a host embryo resulted in 2 nervous system formations

Transforming growth factors

Family of peptide hormones that regulate growth, cell proliferation, and differentiation

SMADs

Phosphorylated from BMPs, names for producing small bodies in C. elegans

BMP pathway

BMP activates BMP receptor serine kinases —> phosphorylation of SMADs —> SMADs translocate to the nucleus and affect BMP response elements —> BMPRes regulate gene expression

FGF function

Generates MAP kinase, which regulates SMAD phosphorylation

Neural crest cell mitation

Epithelial to mesenchymal transition from the roofplate

Dermatome

Area of skin in which sensory nerves derive from a single spinal nerve root

AMPA receptor

Receptors open instantly when glutamate binds, allows sodium ions into the cell, short term response

NMDA receptor

Receptor binds when glutamate binds AND when magnesium blocks the channel, releases calcium ions, long term response

LTP

Strengthening connections between neurons and uses both NMDA and AMPA receptors due to increased calcium, implicated in learning

LTD

Occurs when connections between neurons are weakened, low-frequency stimulation results in small calcium signaling and removal of AMPA

Ischemic stroke causes

Occurs when blood is blocked from part of the brain and brain cells are starved of oxygen and glucose

Ischemic stroke effects

Loss of motor skills and language

Herpes Zoster

Reawakening of chickenpox virus in the dorsal root ganglia

Filopodia

Extensions of growing neurons that sense the environment to follow signals

Lamellipodium

Sheet-like extensions of growing neurons, important for directional migration

Concentrations of morphogens

Roofplate: high BMP, creates sensory neurons

Somite: mixed BMP and Shh, creates muscles and bones

Floorplate: high Shh, creates motor neurons

Agenesis

Improper development due to genetic mutations or environmental factors

Vertebral columns

Sclerotome (forms bones for the spine and ribs), dermatome (forms skin), and myotome (forms muscle)

Dorsal root ganglion

Cluster of nerve cell bodies located outside the spinal cord, important for relay of sensory information to the spinal cord

Neurexin function

Presynaptic builder for synaptogenesis

Neuroligin function

Postsynaptic organizer in synaptogenesis

Rubinstein-Taybi syndrome

Caused by a mutation in the CBP and EP300 genes, affects gene regulation