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UVic BIOL 309 - Spring 2019 > Fly Development > Flashcards

Fly Development Flashcards

1
Q

What differentiates gastrulation in protostomes from gastrulation in deuterostomes?

A

Protostomes: gastrulation begins at mouth
Deuterostomes: gastrulation begins at anus

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2
Q

Which has a notochord, protostomes or deuterostomes?

A

Only deuterostomes, and only those that are chordates.

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3
Q

Describe ametabolous development.

A

No metamorphosis. Immature stages similar to adults, just smaller and lacking genitalia.

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4
Q

Describe hemimetabolous development.

A

Incomplete metamorphosis involving nymph stage + molting before mature adult.

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5
Q

Describe Holometabolous development. What is an example of an insect which does this?

A

dissimilar larval and adult stages. Requires complete metamorphosis + molting (ex: drosophila melanogaster).

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6
Q

How long does fruit fly development take, from egg to mature adult?

A

~10 days.

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7
Q

Outline the 8 stages of fruit fly development.

A
  1. Egg
  2. Cellular blastoderm
  3. Embryo
  4. 1st Instar
  5. 2nd Instar
  6. 3rd Instar
  7. Pupa
  8. Adult
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8
Q

At what 3 stages during fruit fly development is axis formation and patterning being established?

A
  1. Egg
  2. Cellular blastoderm
  3. Embryo
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9
Q

What is an “imaginal disc”?

A

Parts of a fruit fly larva/pupa that develop into the mature body parts.

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10
Q

How did Wigglesworth determine what triggered metamorphosis? What were his findings?

A

By transplanting the head of a nearly mature stinkbug onto the body of a juvenile. Observed that the head had some factor which caused maturation

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11
Q

What hormone did Wigglesworth identify in the kissing-bug head that was required for maturation? What did this produce?

A

Prothoracicotropic hormone which produced 20-hydroxyecdysone.

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12
Q

How can Wigglesworth’s experiments with kissing-bugs be applied to other research?

A

Can use insect-specific promoter to control the timing of gene expression in mouse brain (inducible expression system).

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13
Q

Why could Drosophila melanogaster be a good model organism?

A

Small, easy to breed/store/maintain. Short generation time. Simple, well-studied genome. High conservation between fly and human molecular pathways.

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14
Q

Why might Drosophila melanogaster not be a good model organism?

A

Tiny, so tissue manipulation is hard. Not transparent. Body plan less relevant to humans.

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15
Q

What is a “syncytial blastoderm”? What common lab organism demonstrates this?

A

During development, all nuclei are contained within a single large cytoplasm. Seen in drosophila.

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16
Q

Following the nuclear division stage of drosophila development, how do the nuclei get arranged (stage 9/10)?

A

They all move to the periphery of the embryo.

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17
Q

What characterizes the “cellular blastoderm” stage of drosophila development (stage 13)?

A

A large inner yolk surrounded by a single-cell layer.

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18
Q

During drosophila development, at what stage does asynchronous division begin to occur?

A

Stage 14 (immediately after the cellular blastoderm forms).

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19
Q

Where on the early drosophila embryo does gastrulation begin? What are these cells destined to become?

A

On the ventral side in the “ventral furrow”. These ~1000 cells will become mesoderm.

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20
Q

After the ventral furrow forms in the drosophila embryo, the pole cells invaginate at the anterior and posterior. What will these invaginations form?

A

The gut.

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21
Q

What do cytoplasm removal and replacement experiments in drosophila embryos suggest?

A

That AP axis asymmetry already exists in the fertilized egg.

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22
Q

In drosophila development, when are the AP and DV axes specified? By what genes?

A

Prior to fertilization by maternal effect genes.

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23
Q

Does the egg transcribe maternal effect genes? Where?

A

No, they are actually transcribed in the supporting nurse cells.

24
Q

Which are the 3 “tethered” maternal effect genes? Which is the “free” maternal effect gene?

A 
Tethered:
1. Bicoid
2. Oskar
3. Gurken
Free:
1. Nanos
25
Q

How is RNA moved into the drosophila oocyte from the nurse cells?

A

Along microtubules, carried by dynein.

26
Q

Where is bicoid mRNA localized in the drosophila germarium? What about nanos mRNA?

A

Bicoid mRNA is in the middle, while nanos mRNA is at the posterior end.

27
Q

In drosophila, what 2 things establish the AP axis?

A
  1. Bicoid (anterior)

2. Nanos (posterior)

28
Q

In drosophila, what causes the DV axis to be established?

A

The nucleus is dorsally localized. Maternal effect gene gurken also stabilizes a dorsal fate.

29
Q

In drosophila, what causes the deadenylation of nanos? What prevents this? How?

A

Smaug and CCR4-NOT deadenylate. Oskar prevents this by stabilizing the 3’ UTR (+ poly A tail).

30
Q

How can you characterize the function of bicoid and nanos in drosophila, using one word?

A

Morphogen.

31
Q

Describe the general pathway of gurken signalling in drosophila.

A

Gurken(only dorsal) –> Torpedo –| Pipe synthesis(in ventral) –> cascade of proteolytic cleavages.

32
Q

How does dorsal protein act to help induce the DV axis?

A

Acts as a morphogen. Induces ventral cell fate when translocated to nucleus.

33
Q

How does a fushi tarazu drosophila mutant differ from the wild-type?

A

It has half the number of segments (7).

34
Q

What are 3 classes of zygotic mutations that affect drosophila segmentation (in development order)?

A
  1. GAP genes
  2. Pair rule genes
  3. Segment polarity genes
35
Q

What kinds of mutant drosophila morphologies arise from GAP gene mutations?

A

Organisms which lack large regions of the body.

36
Q

What are some examples of drosophila GAP genes?

A

Any of:

  • Kruppel
  • Knirps
  • Hunchback
  • Giant
  • Tailless
  • Huckebein
  • Buttonhead
  • Empty spiracles
  • Orthodenticle
37
Q

What are 5 examples of ways in which the transcriptional activity of a single TF can be regulated?

A
  1. Post-transcriptional modification
  2. Post-translational modification
  3. Interaction with other proteins
  4. Epigenetic modification of target site
  5. Strength of binding site
38
Q

Why, among the other drosophila GAP genes, is hunchback so important?

A

Initiates expression of the other GAP genes.

39
Q

In drosophila, how does the hunchback mRNA interact with nanos?

A

Nanos inhibits hunchback protein production, ensuring that hunchback is only expressed in the anterior of the oocyte.

40
Q

What is the general mechanism which establishes the TF morphogen gradient for GAP genes in drosophila oocytes?

A

Differential binding site affinity.

41
Q

In addition to its role as a TF, what other function does drosophila bicoid protein have?

A

Also acts as an RNA binding protein.

42
Q

In drosophila, how does hunchback interact with knirps? What about giant and kruppel? What does this cause?

A

Hunchback and knirps mutually repress each other, same as giant and kruppel. This begins establishing TF boundaries leading to segmentation.

43
Q

In drosophila, how is expression of the primary pair rule genes dictated? How many bands will this create?

A

By the overlapping expression of the GAP genes. Gives 7 bands.

44
Q

In drosophila, what do secondary pair-rule genes do in general? What is an example of this kind of gene?

A

They increase the number of distinct morphogen bands in the oocyte from 7 to 14. (ex: fushi tarazu)

45
Q

Do the drosophila pair-rule gene band patterns overlap?

A

No, they express non-overlapping bands.

46
Q

What is an example of a segment polarity gene in drosophila? What do these genes do in general?

A

Engrailed is a segment polarity gene. They form a gradient to determine which side of a segment is anterior and which is posterior.

47
Q

What is an example of a primary pair-rule gene in drosophila?

A

Even-skipped.

48
Q

Outline the 4 steps of the hedgehog signalling pathway.

A
  1. Hedgehog binds/inhibits patched protein
  2. Patched inhibits smoothened
  3. Smoothened stimulates Ci protein
  4. Ci protein either stimulates or represses transcription
49
Q

In the hedgehog signalling pathway, how does cubitus interuptus (Ci) function if it is cleaved? What if it is not cleaved?

A

Cleaved: represses hedgehog-responsive genes
Whole: activates hedgehog-responsive genes

50
Q

In drosophila, how is segment polarity defined specifically?

A

By genes involved in wingless and hedgehog signalling. Hedgehog stimulates wingless and vise-versa.

51
Q

What transcription factor is expressed on the anterior side of a drosophila segment? What about the posterior side? How are these expressed?

A

Anterior: hedgehog
Posterior: wingless
Both are establish morphogen gradients.

52
Q

In drosophila, what determines the positional identity of body segments? What are the 2 major examples of this?

A

Homeotic selector gene complexes:

  1. Antennapedia complex
  2. Bithorax complex
53
Q

How does the chromosomal order of homeotic selector genes affect drosophila segment identity?

A

They influence segment development in the order that they are arranged on the chromosomes. They also repress adjacent gene expression.

54
Q

What do all the drosophila homeotic selector genes share? How is specificity achieved?

A

A ~60 AA domain which binds to DNA. Specificity comes from the identity of the 9th AA of α-helix #3.

55
Q

Describe, in general, drosophila leg growth?

A

Begin with the imaginal disc, and then picture a cinnamon bun being popped out from the middle.

UVic BIOL 309 - Spring 2019 (9 decks)

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