Metamorphosis and Puberty

Question 1

Direct Development

Answer 1

Body plan is a small form of the adult

Question 2

Indirect development

Answer 2

Body plan at the end of embryogenesis is different from the adult

Question 3

Larva

Answer 3

A larva is the juvenile form that hatches from the egg in insects that undergo metamorphosis

Question 4

Instar

Answer 4

The stages between larval molts

Question 5

Pupa

Answer 5

The larva hatches from the egg and progresses through a series of molts, growing larger with each molt, culminating in the transformation of the larva into a pupa.

Question 6

How juvenile hormone and 20E collaborate to guide postembryonic developmental transitions

Answer 6

Neuroendocrine homes that regulate metamorphosis
- High JH + High 20E = induce molts to form the next larval instar
- Low JH + High 20E = formation of pupa
- Imaginal disks differentiate

Question 7

20E

Answer 7

Produced anterior to the ligature site
1st pulse at late larval stage - initiates pupal dev, stops disk cell division
2nd pulse - instructs prepupa-> pupa

Question 8

Prothoracic gland and PTTH

Answer 8

Prothoracic is an endocrine organ that produces ecdysone critical for molting
PTTH is a peptide hormone that acts on the glad to stimulate the production of ecdysone
LOF mutation for PTTH results in delayed pupation

Question 9

Imaginal Disc

Answer 9

Set of undifferentiated cells that are set aside during embryonic development
- highly active in metamorphosis, giving rise to most adult structures

Question 10

What early larva and pupal extract injections reveal about developmental transition signals

Answer 10

Injecting pupal extract into early fifth instar larvae induces precocious pupation
Early larval extract results in an extra molt to a sixth instar

Question 11

Critical weight checkpoint

Answer 11

At 0.9 mg the larva have enough nutrient stores to support metamorphosis

Question 12

Imaginal disc checkpoint

Answer 12

The imaginal disks must be correct size and healthy
- damage disk causes delayed pupation until disk is healed
- damaged disks produce stop signal, healthy disks produce go signal

Question 13

Puberty

Answer 13

Puberty is a complex developmental transition characterized by several key features.

Question 14

Nutritional and environmental influences on puberty

Answer 14

Nutritional -
obesity is correlated with early puberty
Starvation is correlated with delayed pubery

Environmental -
BPA causes early puberty

Question 15

Hypothalamus-Pituitary-Gonad (HPG) axis and associated hormones

Answer 15

HPG is a neuroendocrine circuit that regulates the development and function of the reproductive system in mammals.
Secretes GnRH
GnRH stimulates the pituitary gland
Promotes the production of sex steroids

Question 16

Kallman’s Syndrome

Answer 16

Delays/ Blocks puberty onset
- Mutation in Anosomin1 gene
- Neural dev in olfactory bulb
- GnRH neurons born in olfactory bulb –> hypothalamus

Question 17

GnRH neurons

Answer 17

Born in olfactory bulb –> hypothalamus