Defect Categories
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Defect names are listed in bold with their corresponding scoring criterion below.
Egg Shape/Size
Small(<2/3 of WT), large (>4/3 of WT), or irregularly shaped eggs
Osmotic Sensitivity
Swelling of the embryo to fill the egg shell and/or irregular granule movements
P0 Cortical Ruffling
Excessive or no early cortical ruffling (WT: wave of membrane ruffling from posterior to anterior resulting in Pseudo Cleavage Furrow)
P0 Cytoplasmic Flows
Lack of granular flows towards the male pronucleus (WT: directional flow of yolk granules towards the male PN
P0 Pseudo-Cleavage Furrow
No or excessive furrowing (WT: Covering 20-30% the width of the embryo)
P0 Pronuclei-Size/Shape
Size >30% smaller or larger than WT (WT: diameter approx. 25% the width of the embryo at onset of PN migration), or irregular shape of pronuclei
P0 Pronuclei-Number
Numbers of pronuclei above or below 2 (WT: one female, one male PN)
P0 Pronuclear Migration (female)
No or little migration of female PN towards the male PN (WT: directional movement of the female towards the male PN)
P0 Pronuclear Migration (male)
No migration of male PN from posterior cortex towards centre of the embryo
P0 Pronuclear Meeting
Position near the cortex or centrally (WT: near the centre of the posterior half of the embryo)
P0 Pronuclear Centration
Position off centre
P0 Pronuclear Rotation
Rotation takes place after PN envelope breakdown (WT: approx. 2-3min before PNEBD)
P0 Pronuclear Envelope Breakdown
Lag time between PN meeting and PN envelope breakdown exeeds 8 min (WT: 4-5 min )
P0 Spindle Assembly-Bipolarity
Lack of 2 visible poles, i.e. two regularly shaped sites of yolk granule exclusion
P0 Spindle Integrity
Irregular length (WT: 25-30% the length of the embryo during metaphase), or Thickness (WT: 20-25% the width of the embryo at metaphase), or lack of Rigidity
P0 Spindle Elongation
Spindle covers less or more than 50-60% of the length of the embryo at telophase
P0 Spindle Rocking
No or excessive spindle rocking
P0 Spindle Positioning-Asymmetry
Spindle positioning at telophase other than along the longitudinal axis with the posterior pole shifted posteriorly approx. 10-15%
P0 Spindle Poles
Irregular shape, in particular lack of flattening of posterior pole in telophase
P0 Cytokinesis-Furrow Specification
Fewer or more than 2 sites of furrowing and/or aberrant positioning (WT: two sites, intersecting the long axis by a ratio of approx. 3:2)
P0 Cytokinesis-Furrow Ingression
Little or no ingression, or uneven ingression from the two sites
P0 Cytokinesis- Completion/Stability
Regression of the furrow
P1/AB Nuclear Separation-Cross-Eyed
Re-forming daughter nuclei stay closely attached to the central cortex
AB Nuclear Migration
Time for centration of AB nucleus exceeds 7-8min., AB nucleus migrates towards the cortex before centration (WT: AB nucleus usually centres directly after cytokinesis)
P1/AB Cortical Activity
Excessive membrane ruffling and blebbing
P1/AB Nuclei-Number
Numbers of nuclei in daughter cells below or above 1
P1/AB Nuclei-Size/Shape
Size >30% smaller or larger than WT (diameter approx. 25% of AB blastomere), or irregular shape of nuclei
P1 Nuclear Migration/Rotation
Lack of migration of P1 nucleus towards posterior cortex, lack of rotation of P1 spindle before nuclear envelope breakdown
P1/AB Spindle Assembly
Aberrant bipolarity or length or thickness
AB Spindle Orientation
Rotation of AB spindle (WT: AB spindle keeps orientation,whereas P1 spindle rotates)
P1/AB Asynchrony of Divisions
Delay between AB and P1 cleavage furrow initiation is either shorter than 2 min or exceeds 5 min (WT: approx. 2-3 min)
P1/AB Cytokinesis
Aberrant furrow initiation or ingression or completion
Four Cell Stage Cross-Eyed
Re-forming daughter nuclei stay closely attached to the central cortex
Four Cell Stage Nuclei-Size/Shape
Irregular size and/or shape of nuclei in daughter cells
Four Cell Stage Configuration
Par-like configurations of blastomeres
Tetrapolar Spindle
4 poles visible by exclusion of yolk granules
Yolk Granules-Density
Reduction >30%
Yolk Granules-Size
Aberrant size of individual or all granules
Areas Devoid of Yolk Granules
Aberrant cytoplasmic structures excluding yolk granules
Polar Bodies
Aberrant number (fewer or more than two) or size (matches or exceeds size of early pronuclei) or internalization of polar bodies
Unclear-Multinucleate
Aberrant numbers of nuclei
Overall Pace of Events
Timing; scored were events where delay between pronuclear meeting and initiation of AB cleavage furrow exceeded 30 min (WT: 18-22min)
Number/Age of Embryos
Absence or reduction of one and two cell stage embryos, suggesting reduced fertility of the parent worm
Meiotic Arrest
No visible pronuclei, little or no cytoplasmic events, embryo often fills egg shell
Other
Any other observation deferring from wildtype events
Inadequate Test
Technical inadequacy, (focussing, coverage of recordings, etc.)