WormMine: RNAi WBRNAi00088415

• WormBase ID: WBRNAi00088415
• Phenotype Remark: Depletion of the gene products resulted in embryonic lethality with complete penetrance. RNAi-affected embryos were all arrested during embryogenesis, and ~30% of them displayed defective mitosis in early cell cycles. In wild-type embryos, condensed chromosomes aligned on the metaphase plate and then they separated at once in anaphase, giving a view of splitting two parallel discs. After cytokinesis, chromosomes were decondensed and nuclear membrane was reassembled around them. In contrast, embryos depleted of either SCC-3, or HIM-1/SMC-1, or SMC-3 behaved differently from the wild-type, with these three kinds of RNAi embryos showing phenotypes indistinguishable from each other. Chromosomes were condensed at prometaphase in these embryos, but the metaphase plate often looked diffuse, or was completely missing in some cases. Then, a mass of chromosomes staying in the middle of the bipolar spindle frequently seemed to be divided by a cleavage furrow. This might mean the lack of anaphase, or alternatively, the progression of aberrant anaphase with extensive chromosome bridging, which were not distinguishable at the current resolution. Chromosomes were decondensed after cytokinesis, as in wild-type embryos, but multiple (mainly two to four) nuclei of variable size were often formed in daughter cells. In the case of wild-type embryos, nuclear membrane has been shown to reassemble around subsets of decondensed chromosomes at telophase, but they fuse until they form a single nucleus that encloses the whole chromosome set. Authors speculate that nuclear membrane could reassemble around each chromosome or a subset of a few chromosomes but failed to fuse to form a single nucleus in cells devoid of either SCC-3, or HIM-1/SMC-1, or SMC-3. This is probably because chromosomes were not separated synchronously in these cells and hence were not close enough to each other to compose a unified nucleus. Subsequent cell cycles were also aberrant similarly in the RNAi animals. Nuclear membrane of the multiple small nuclei generated in the previous cell cycle broke down simultaneously and chromosomes were condensed, but only a loose metaphase plate was formed again, and a mass of chromosomes was divided irregularly by a cleavage furrow. These observations suggest that SCC-3, HIM-1/SMC-1, and SMC-3, are essential for proper chromosome segregation, but unlikely to be involved in other aspects of the cell cycle.
• Remark: paper remark: Exact sequence used for RNAi not stated by authors, spliced coding region sequence of gene used for curation. Authors used yk295d12 (smc-3).

1 Organism

• Name: Caenorhabditis elegans
• Taxon Id: 6239

1 Data Sets

• WormBaseAcedbConverter

1 Inhibits Gene

WormBase Gene ID	Gene Name	Sequence Name	Organism
WBGene00004873	smc-3	Y47D3A.26	Caenorhabditis elegans

2 Inhibits Predicted Gene

WormMine ID	Sequence Name	Length (nt)	Chromosome Location
CDS:Y47D3A.26c	Y47D3A.26c	990	III: 11300791-11301000
CDS:Y47D3A.26a	Y47D3A.26a	3618	III: 11290942-11290956

1 Laboratories

Primary Identifier
YM

2 Phenotype

Identifier	Name	Description
WBPhenotype:0000050	embryonic lethal	Animals die during embryonic development. In C. elegans, often assayed as refractile eggs that fail to hatch; when applied to large-scale RNAi screens in C. elegans, more than 10% of embryos die.
WBPhenotype:0000773	chromosome segregation variant	Any variation in the processes that regulate the apportionment of chromosomes to each of two daughter cells compared to control.

0 Phenotype _ Not _ Observed

1 Reference

First Author	Title	Year	Journal	Volume	Pages	PubMed ID
						WBPaper00005937

1 Strain

WormBase ID
WBStrain00000001