Quiz
Insect Oogenesis and Development
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1recap of last lecture
- developmental instructions are usually given through [blank_start]chemical[blank_end] gradients
- beta [blank_start]catenin[blank_end] has highest concentration at the bottom of the embryo (the [blank_start]vegetal[blank_end] pole) and causes the formation of the gut and the [blank_start]skeleton[blank_end]
- gradients are important key ways instructions are given
- beta catenin is a [blank_start]transcription[blank_end] factor that binds to regulatory sequences of DNA along with the other transcription factor, [blank_start]Otx[blank_end]
- Achemical
- Bcatenin
- Cvegetal
- Dskeleton
- Etranscription
- FOtx
2Functional properties of Gene [blank_start]regulatory[blank_end] networks (series of on/off switches)
- network circuits consist of regulatory genes (encoding [blank_start]transcription[blank_end] factors)
- [blank_start]Kernels[blank_end] are gene regulatory networks for a given developmental function not used elsewhere in development
- GRNs have '[blank_start]recursive[blank_end] wiring' > products of many genes are required for the kernel to function (recursive [blank_start]wiring[blank_end])
- thus interference with expression of any one kernel gene will destroy the function of the entire kernel and have severe developmental consequences
- as a result, once they have evolved, they tend to be [blank_start]stable[blank_end] during evolution > there is strong [blank_start]selection[blank_end] pressure preventing mutation of these genes
so: [blank_start]kernels[blank_end] are precise sets of interactions between genes that have a developmental function
- if one of these genes becomes inactivated the function of the whole circuit will be affected
[blank_start]Gene[blank_end] regulatory network kernels can be highly conserved during evolution
- the same genes are being transcribed in early gastrulation of sea urchins and starfish
- these organisms diverged at least 500 [blank_start]million[blank_end] years ago
- the developmental kernel has [blank_start]not[blank_end] changed over that time
- there is a local circuit in the early stages of gastrulation that result in the production of the 3 genes: [blank_start]tbr[blank_end], foxa and [blank_start]gatae[blank_end]
- tbr, [blank_start]foxa[blank_end] and gatae are all transcribed in sea urchins and starfish
- Aregulatory
- Btranscription
- CKernels
- Drecursive
- Ewiring
- Fstable
- Gselection
- Hkernels
- IGene
- Jmillion
- Knot
- Ltbr
- Mgatae
- Nfoxa
3Developmental GRNs and evolution of animal body plans
- kernels specify early [blank_start]developmental[blank_end] processes that are most impervious (resistant) to change
the conservation of animal body plans since the pre-[blank_start]Cambrian[blank_end] period may be due to the preservation of kernels
- similar body plan = cephalisation, segments, appendages
- similar body plan likely to be due to these developmental [blank_start]kernels[blank_end] (networks of on/off switches)
these kernels underlie the development of most body parts- Adevelopmental
- BCambrian
- Ckernels
4Oogenesis and Invertebrate Development
- [blank_start]oogenesis[blank_end] = the development of an ovum (egg)
- mother deposits [blank_start]RNA[blank_end] for [blank_start]beta[blank_end] catenin into an ovum
- [blank_start]yolk[blank_end] (dense granules) influences the way the embryo divides in early development
Gametogenesis and the onset of development: the storage of developmental information
- [blank_start]gametogenesis[blank_end] = the process in which cells undergo [blank_start]meiosis[blank_end] to form gametes
sexual reproduction in animals involves the fusion of egg and sperm cells at fertilisation
- could be regarded as the start of development
- but could consider development to start at an earlier stage e.g. [blank_start]gametogenesis[blank_end] (when the gametes are produce, as developmental information from the mother is deposited into the egg)
oogenesis = [blank_start]egg[blank_end] formation [blank_start]spermatogenesis[blank_end] = sperm formation- Aoogenesis
- Bbeta
- CRNA
- Dyolk
- Egametogenesis
- Fmeiosis
- Ggametogenesis
- Hspermatogenesis
- Iegg
5Egg and sperm cells are [blank_start]haploid[blank_end], they are formed during meiosis, also referred to as [blank_start]germ[blank_end] cells
[blank_start]Oogenesis[blank_end] = creating an egg
- the [blank_start]primary[blank_end] oocyte is [blank_start]diploid[blank_end] and through [blank_start]meiosis[blank_end] forms as haploid cells, called the mature [blank_start]ovum[blank_end]
- primary [blank_start]oocyte[blank_end] (diploid) --> meiosis --> [blank_start]mature[blank_end] ovum (haploid)
features of the mature ovum
- storage molecules '[blank_start]yolk[blank_end]' (dense granules) containing the lipoprotein '[blank_start]vitellin[blank_end]'
- [blank_start]membranes[blank_end] and associated structures involved in the fertilisation reaction (results in fertilisation membrane)
- [blank_start]mitochondria[blank_end], ribosomes, stored [blank_start]mRNA[blank_end] (m)
[blank_start]vitellogenesis[blank_end] = also known as yolk deposition, is the process of yolk formation via nutrients being deposited in the oocyte
- may occur through a lengthened [blank_start]prophase[blank_end] of meiosis (may be months-years)
- the oocyte increases massively in size and the reduction division may be delayed until after this growth phase
fact: membrane can be important in fertilisation and the reactions associated, the membrane may [blank_start]swell[blank_end] following fertilisation to prevent more sperm fertilising the egg- Ahaploid
- Bgerm
- COogenesis
- Ddiploid
- Emeiosis
- Fprimary
- Goocyte
- Hmature
- Iovum
- Jyolk
- Kvitellin
- Lmembranes
- Mmitochondria
- NmRNA
- Ovitellogenesis
- Pprophase
- Qswell
6Patterns of oogensis (development of ovum, egg)/how we classify types of egg production/development
oogenesis can be categorised by the relationship of the oocyte to the other cells
- [blank_start]solitary[blank_end] (alone)
- follicular (follicle)
- [blank_start]nutrimentary[blank_end] (nutrients)
OR by the synthetic pathway for the stored yolk in the cytoplasm (the way in which [blank_start]nutrients[blank_end] are deposited into the egg), can be:
1. [blank_start]autosynthetic[blank_end] oogenesis
2. heterosynthetic oogenesis- Asolitary
- Bnutrimentary
- Cautosynthetic
- Dnutrients
7Classify oogenesis based on the oocytes relationship to other cells
1. [blank_start]Solitary[blank_end] oogeneis - there are [blank_start]no[blank_end] follicle cells or nurse cells
> egg cell is floating in the body cavity without being associated with [blank_start]any[blank_end] other cell type
> commonly found in [blank_start]polychaete[blank_end] worms (p)
2. [blank_start]Follicular[blank_end] oogenesis = oocytes are associated with a covering of [blank_start]somatic[blank_end] (body cells), known as [blank_start]follicle[blank_end] cells
> follicular oogenesis is found in the tunicate ([blank_start]sea[blank_end] squirt) Ascidiella aspersa
> locusts and [blank_start]panoistic[blank_end] ovaries, panoistic ovaries have follicle cells and oocytes develop within ovarioles
> the egg cell moves out of the oviduct, then to a structure at the base found in some insects called the [blank_start]ovipositor[blank_end]
> eggs are produced in the ovarioles (hair-like) which are closely associated with follicle cells
3. [blank_start]Nutrimentary[blank_end] oogenesis - oocytes are associated with sister cells called [blank_start]nurse[blank_end] cells
- where we see an even more intimate association of the egg cells (oocyte) with the follicle cells
- specialisation of germ ovum cells into 2 types (2 types of egg cells) = [blank_start]nurse[blank_end]/nutritive cells and eggs from oocytes
- nutrimentary oogenesis occurs in [blank_start]Drosophila[blank_end] (fruit fly), they have [blank_start]polytropic[blank_end] meroistic development
- polytropic [blank_start]meroistic[blank_end] development = when oogonia divide into oocyte and [blank_start]nurse[blank_end] cells- ASolitary
- Bno
- Cany
- Dpolychaete
- EFollicular
- Ffollicle
- Gsomatic
- Hsea
- Ipanoistic
- Jovipositor
- Knurse
- LNutrimentary
- Mnurse
- NDrosophila
- Opolytropic
- Pmeroistic
- Qnurse
8[blank_start]Nutrimentary[blank_end] oogeneis = oocyte is associated with nurse/nutritive cells
- e.g. seen in Drosophila, which have polytropic [blank_start]meroistic[blank_end] development in which oogonia developm into an oocyte and nurse cells
[blank_start]oogonia[blank_end] = an immature female reproductive cell that gives rise to primary oocytes by [blank_start]mitosis[blank_end] (diploid)
Drosophila ovary and oocyte development
- oogonia (immature egg cell) divides by mitosis to form oocyte and nurse cells
- incomplete cell divisions (cytokinesis) leaves [blank_start]cytoplasmic[blank_end] bridges between nurse/nutritive cells and oocyte
Drosophilia have these specialised germ cells called nurse cells, during the first few divisions that would normally form individual eggs, the cells do [blank_start]not[blank_end] disconnect and are joined by cytoplasmic [blank_start]bridges[blank_end], ending with a series of [blank_start]16[blank_end] cells that are closely joined together. These joined cells can pass nutrients and [blank_start]RNA[blank_end] between them but only [blank_start]one[blank_end] of the cells will become the egg, the other 15 are there for support.
The ovarioles have bulges because of these ‘egg [blank_start]chambers[blank_end]’, with oocyte at one end and germ nurse cells at the other surrounded by [blank_start]follicle[blank_end] cells.
[blank_start]Nutrimentary[blank_end] oogenesis = oocyte is associated with sister nurse cells which supply it with nutrients. There is an outer layer of somatic follicles in the egg chamber.
- ANutrimentary
- Bmeroistic
- Coogonia
- Dmitosis
- Ecytoplasmic
- Fnot
- Gbridges
- H16
- IRNA
- Jone
- Kchambers
- Lfollicle
- MNutrimentary
9The other way oogenesis (egg production) can be classified is how [blank_start]nutrients[blank_end] are deposited into the egg "by the synthetic pathway for the stored yolk in the cytoplasm", can be autosynthetic oogenesis or heterosynthetic oogenesis
1. [blank_start]autosynthetic[blank_end] oogenesis
> the synthesis of yolk and other stored materials comes from the [blank_start]oocyte[blank_end] itself
> uptake of low molecular [blank_start]weight[blank_end] precursors of yolk e.g. [blank_start]amino[blank_end] acids and carbohydrates
> can be demonstrated by labelling precursors of yolk e.g. amino acids and carbohydrates with radioactive [blank_start]titanium[blank_end]
> autosynthesis oogenesis is sometimes observed in [blank_start]solitary[blank_end] oogenesis in polychaetes
2. [blank_start]Heterosynthetic[blank_end] oogenesis
> synthesis of yolk proteins by other non-[blank_start]germ[blank_end] (gametes) cells
> characterised by the uptake of yolk-precursor protein [blank_start]vitellogenin[blank_end], later stored as vitellin (vitellogenin)
evidence: from [blank_start]electron[blank_end] microscopy showing characteristic vesicle formation at the cell surface
- electrophoresis showing proteins identical to the yolk protein in body fluid
- immunological demonstration of yolk protein-like proteins in the body fluid- Anutrients
- Bautosynthetic
- Coocyte
- Damino
- Eweight
- Ftitanium
- Gsolitary
- HHeterosynthetic
- Igerm
- Jvitellogenin
- Kelectron
10Uptake and storage of yolk: autosynthetic vs. heterosynthetic
- some solitary oocytes are [blank_start]autosynthetic[blank_end] e.g. seen in polychaete worms
- most follicular and [blank_start]nutrimentary[blank_end] oocytes are heterosynthetic (take in high molecular weight precursors)
- vitellogenin is a high molecular weight protein transported to the oocyte then converted to [blank_start]vitellin[blank_end]- Avitellin
- Bnutrimentary
- Cautosynthetic
11The masked mRNA hypothesis
during oogenesis the oocyte accumulates stored RNA, some of which is ribosomal
- much of the RNA is [blank_start]mRNA[blank_end] which 'stores developmental information'
- the mRNA is '[blank_start]masked[blank_end]' > only available for protein synthesis after fertilisation
storage of mRNA
- pictures show radiographs of RNA synthesis in the [blank_start]nurse[blank_end] cells of Drosophila and the later shift of the RNA to the oocyte
- mature egg chamber (point at which one of the oocytes becomes specialised and will develop into egg at the bottom of the chamber), the sister nurse/nutritive cells are above it
the RNA has been radioactively labelled so it appears as black granules, on the right you can see the black granules (RNA) starting to appear in the cytoplasm of the egg cell/oocyte and even more so on the right
RNA is being transcribed by the [blank_start]nurse[blank_end] cells and transported into the developing egg
- AmRNA
- Bmasked
- Cnurse
- Dnurse
12Development of the body plan in Drosophilia
Whole process from egg to adult takes 9 [blank_start]days[blank_end]
The yolkier the egg, the [blank_start]harder[blank_end] it is for cells to separate in cell division. So much so in Drosophilia the [blank_start]nucleus[blank_end] is the only thing that divides: several nuclei are surrounded by a single membrane = [blank_start]syncytium[blank_end]
- Adays
- Bharder
- Cnucleus
- Dsyncytium
Informationen
- Beschreibung
- Development Quiz am Insect Oogenesis and Development, erstellt von sophie waddington am 07/01/2019.
- Autor
- sophie waddington
- Sprache
- English
- Aufrufe
- 1
- Schlagwörter
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