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Mutations affecting embryonic cell migrations in Caenorhabditis elegans
1Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder.
Abstract:
Four recessive mutations that affect long-range embryonic migration of the two canal-associated neurons (CANs) in C. elegans were isolated and characterized with the goal of identifying genes involved in control of directed cell movement. Mutant animals were identified initially by their "withered" tails, a phenotype associated with abnormal CAN migration; the mutants were then analyzed for abnormal cell migrations by Nomarski microscopy. Based on genetic complementation tests, the mutations were assigned to four different loci, two new (mig-10 III, mig-11 III) and two previously identified (unc-39 V, vab-8 V). Mutations at all four loci affect CAN migration with high to moderate penetrance (the percentage of mutant animals that exhibit the phenotype). In addition, two other bilaterally symmetric pairs of neurons (ALM and HSN), the mesoblast M, and a pair of coelomocyte mother cells are affected by one or more of the mutations, generally with lower penetrance. With the exceptions of HSN and the right coelomocyte mother cell, which occasionally migrate beyond their normal destinations, the cells affected appear to migrate either incompletely or not at all. All the migration phenotypes show incomplete penetrance and variable expressively, although genetic tests suggest that mutations at mig-10 and vab-8 result in complete or nearly complete loss of gene function. The variability in mutant phenotypes allowed tests for interdependence of several of the affected migrations; all those analyzed appeared independent of one another. The possible nature of the mutant defects and possible roles of these four loci in cell migration are discussed.
Insights
Four new mutations affecting embryonic cell migration in C. elegans were identified. These mutations disrupt the directed movement of canal-associated neurons (CANs) and other cells, revealing new genes involved in cell migration control.
Area of Science:
- Developmental Biology
- Cell Biology
- Genetics
Background:
- Embryonic cell migration is crucial for organism development.
- Understanding the genetic control of directed cell movement is essential for developmental biology.
- The nematode C. elegans serves as a powerful model organism for studying conserved cellular processes like migration.
Purpose of the Study:
- To identify and characterize genes involved in the long-range embryonic migration of canal-associated neurons (CANs) in C. elegans.
- To isolate new mutations affecting directed cell movement.
- To understand the genetic basis of neuronal migration defects.
Main Methods:
- Isolation and characterization of recessive mutations affecting CAN migration.
- Genetic complementation tests to assign mutations to loci.
- Nomarski microscopy to analyze cell migration phenotypes.
- Analysis of mutations affecting other cell types, including neurons, mesoblasts, and coelomocyte precursors.
Main Results:
- Four recessive mutations affecting CAN migration were identified and assigned to four loci: mig-10, mig-11, unc-39, and vab-8.
- Mutations at these loci caused abnormal migration of CANs with high to moderate penetrance.
- Other cell types, including ALM and HSN neurons, mesoblast M, and coelomocyte mother cells, were also affected by these mutations, generally with lower penetrance.
- Genetic tests indicated that the affected migrations are largely independent of one another.
Conclusions:
- The identified genes (mig-10, mig-11, unc-39, vab-8) play significant roles in controlling embryonic cell migration in C. elegans.
- These mutations provide tools for further investigation into the molecular mechanisms of directed cell movement.
- The study highlights the complexity of cellular migration pathways and potential genetic redundancies or interdependencies.