Limits...
AIR-2: An Aurora/Ipl1-related protein kinase associated with chromosomes and midbody microtubules is required for polar body extrusion and cytokinesis in Caenorhabditis elegans embryos.

Schumacher JM, Golden A, Donovan PJ - J. Cell Biol. (1998)

Bottom Line: Unlike other Aurora/Ipl1-related kinases, the Caenorhabditis elegans orthologue, AIR-2, is associated with meiotic and mitotic chromosomes.AIR-2 also remains associated with both extruded polar bodies.In the embryo, AIR-2 is found on metaphase chromosomes, moves to midbody microtubules at anaphase, and then persists at the cytokinesis remnant.

View Article: PubMed Central - PubMed

Affiliation: Cell Biology of Development and Differentiation Group, ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, Frederick, Maryland 21702, USA.

ABSTRACT
An emerging family of kinases related to the Drosophila Aurora and budding yeast Ipl1 proteins has been implicated in chromosome segregation and mitotic spindle formation in a number of organisms. Unlike other Aurora/Ipl1-related kinases, the Caenorhabditis elegans orthologue, AIR-2, is associated with meiotic and mitotic chromosomes. AIR-2 is initially localized to the chromosomes of the most mature prophase I-arrested oocyte residing next to the spermatheca. This localization is dependent on the presence of sperm in the spermatheca. After fertilization, AIR-2 remains associated with chromosomes during each meiotic division. However, during both meiotic anaphases, AIR-2 is present between the separating chromosomes. AIR-2 also remains associated with both extruded polar bodies. In the embryo, AIR-2 is found on metaphase chromosomes, moves to midbody microtubules at anaphase, and then persists at the cytokinesis remnant. Disruption of AIR-2 expression by RNA- mediated interference produces entire broods of one-cell embryos that have executed multiple cell cycles in the complete absence of cytokinesis. The embryos accumulate large amounts of DNA and microtubule asters. Polar bodies are not extruded, but remain in the embryo where they continue to replicate. The cytokinesis defect appears to be late in the cell cycle because transient cleavage furrows initiate at the proper location, but regress before the division is complete. Additionally, staining with a marker of midbody microtubules revealed that at least some of the components of the midbody are not well localized in the absence of AIR-2 activity. Our results suggest that during each meiotic and mitotic division, AIR-2 may coordinate the congression of metaphase chromosomes with the subsequent events of polar body extrusion and cytokinesis.

Show MeSH

Related in: MedlinePlus

The localization of AIR-2 to meiotic chromosomes requires the presence of sperm in the spermatheca. (A and B) Gonads dissected from virgin tra-2(gf) females were fixed and  stained with DAPI (A) and AIR-2–specific antisera (B). AIR-2  staining is diffuse throughout the cellularized oocytes and does  not localize to chromosomes in the proximal oocyte (arrowheads). (C and D) Gonads dissected from mated tra-2(gf) females  were fixed and stained with DAPI (C) and AIR-2–specific antisera (D). AIR-2 strongly stains the chromosomes of the proximal  oocyte (arrowheads) and fainter staining of chromosomes is also  seen in a neighboring oocyte (arrow). Bars, 20 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2132979&req=5

Figure 4: The localization of AIR-2 to meiotic chromosomes requires the presence of sperm in the spermatheca. (A and B) Gonads dissected from virgin tra-2(gf) females were fixed and stained with DAPI (A) and AIR-2–specific antisera (B). AIR-2 staining is diffuse throughout the cellularized oocytes and does not localize to chromosomes in the proximal oocyte (arrowheads). (C and D) Gonads dissected from mated tra-2(gf) females were fixed and stained with DAPI (C) and AIR-2–specific antisera (D). AIR-2 strongly stains the chromosomes of the proximal oocyte (arrowheads) and fainter staining of chromosomes is also seen in a neighboring oocyte (arrow). Bars, 20 μm.

Mentions: Given the striking localization of AIR-2 to chromosomes in the most mature oocyte residing next to the spermatheca, we determined whether this localization was dependent on the presence of sperm in the spermatheca. Gain-of-function (gf) mutations in tra-2 [tra-2(gf)] result in feminization of the hermaphrodite gonad (Doniach, 1986; Schedl and Kimble, 1988). tra-2(gf) females do not produce sperm, but their oocytes can still be fertilized with sperm introduced upon mating with males. In the absence of sperm, these oocytes will remain in diakinesis and are rarely ovulated. Dissected gonads from virgin and mated tra-2(gf) females were fixed and stained with the AIR-2 antibody. Although diffuse AIR-2 staining was seen in the prophase I–arrested oocytes of virgin tra-2(gf) females, no chromosomal staining was found in any of the oocytes, including the oocyte proximal to the empty spermatheca (>20 gonads were examined) (Fig. 4, A and B). We also noted a few tra-2(gf) oocytes that had been ovulated in the absence of sperm. AIR-2 was not present on the chromosomes of these ovulated oocytes (data not shown). In mated tra-2(gf) females, chromosomal staining of the proximal oocyte was indistinguishable from wild-type staining patterns (Fig. 4, C and D). AIR-2 staining in fertilized oocytes and embryos produced from these matings was also indistinguishable from wild-type controls (see below). Thus, like nuclear envelope breakdown and other hallmarks of oocyte maturation (McCarter et al., 1998), the localization of AIR-2 to meiotic chromosomes is dependent on the presence of sperm in the spermatheca.


AIR-2: An Aurora/Ipl1-related protein kinase associated with chromosomes and midbody microtubules is required for polar body extrusion and cytokinesis in Caenorhabditis elegans embryos.

Schumacher JM, Golden A, Donovan PJ - J. Cell Biol. (1998)

The localization of AIR-2 to meiotic chromosomes requires the presence of sperm in the spermatheca. (A and B) Gonads dissected from virgin tra-2(gf) females were fixed and  stained with DAPI (A) and AIR-2–specific antisera (B). AIR-2  staining is diffuse throughout the cellularized oocytes and does  not localize to chromosomes in the proximal oocyte (arrowheads). (C and D) Gonads dissected from mated tra-2(gf) females  were fixed and stained with DAPI (C) and AIR-2–specific antisera (D). AIR-2 strongly stains the chromosomes of the proximal  oocyte (arrowheads) and fainter staining of chromosomes is also  seen in a neighboring oocyte (arrow). Bars, 20 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2132979&req=5

Figure 4: The localization of AIR-2 to meiotic chromosomes requires the presence of sperm in the spermatheca. (A and B) Gonads dissected from virgin tra-2(gf) females were fixed and stained with DAPI (A) and AIR-2–specific antisera (B). AIR-2 staining is diffuse throughout the cellularized oocytes and does not localize to chromosomes in the proximal oocyte (arrowheads). (C and D) Gonads dissected from mated tra-2(gf) females were fixed and stained with DAPI (C) and AIR-2–specific antisera (D). AIR-2 strongly stains the chromosomes of the proximal oocyte (arrowheads) and fainter staining of chromosomes is also seen in a neighboring oocyte (arrow). Bars, 20 μm.
Mentions: Given the striking localization of AIR-2 to chromosomes in the most mature oocyte residing next to the spermatheca, we determined whether this localization was dependent on the presence of sperm in the spermatheca. Gain-of-function (gf) mutations in tra-2 [tra-2(gf)] result in feminization of the hermaphrodite gonad (Doniach, 1986; Schedl and Kimble, 1988). tra-2(gf) females do not produce sperm, but their oocytes can still be fertilized with sperm introduced upon mating with males. In the absence of sperm, these oocytes will remain in diakinesis and are rarely ovulated. Dissected gonads from virgin and mated tra-2(gf) females were fixed and stained with the AIR-2 antibody. Although diffuse AIR-2 staining was seen in the prophase I–arrested oocytes of virgin tra-2(gf) females, no chromosomal staining was found in any of the oocytes, including the oocyte proximal to the empty spermatheca (>20 gonads were examined) (Fig. 4, A and B). We also noted a few tra-2(gf) oocytes that had been ovulated in the absence of sperm. AIR-2 was not present on the chromosomes of these ovulated oocytes (data not shown). In mated tra-2(gf) females, chromosomal staining of the proximal oocyte was indistinguishable from wild-type staining patterns (Fig. 4, C and D). AIR-2 staining in fertilized oocytes and embryos produced from these matings was also indistinguishable from wild-type controls (see below). Thus, like nuclear envelope breakdown and other hallmarks of oocyte maturation (McCarter et al., 1998), the localization of AIR-2 to meiotic chromosomes is dependent on the presence of sperm in the spermatheca.

Bottom Line: Unlike other Aurora/Ipl1-related kinases, the Caenorhabditis elegans orthologue, AIR-2, is associated with meiotic and mitotic chromosomes.AIR-2 also remains associated with both extruded polar bodies.In the embryo, AIR-2 is found on metaphase chromosomes, moves to midbody microtubules at anaphase, and then persists at the cytokinesis remnant.

View Article: PubMed Central - PubMed

Affiliation: Cell Biology of Development and Differentiation Group, ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, Frederick, Maryland 21702, USA.

ABSTRACT
An emerging family of kinases related to the Drosophila Aurora and budding yeast Ipl1 proteins has been implicated in chromosome segregation and mitotic spindle formation in a number of organisms. Unlike other Aurora/Ipl1-related kinases, the Caenorhabditis elegans orthologue, AIR-2, is associated with meiotic and mitotic chromosomes. AIR-2 is initially localized to the chromosomes of the most mature prophase I-arrested oocyte residing next to the spermatheca. This localization is dependent on the presence of sperm in the spermatheca. After fertilization, AIR-2 remains associated with chromosomes during each meiotic division. However, during both meiotic anaphases, AIR-2 is present between the separating chromosomes. AIR-2 also remains associated with both extruded polar bodies. In the embryo, AIR-2 is found on metaphase chromosomes, moves to midbody microtubules at anaphase, and then persists at the cytokinesis remnant. Disruption of AIR-2 expression by RNA- mediated interference produces entire broods of one-cell embryos that have executed multiple cell cycles in the complete absence of cytokinesis. The embryos accumulate large amounts of DNA and microtubule asters. Polar bodies are not extruded, but remain in the embryo where they continue to replicate. The cytokinesis defect appears to be late in the cell cycle because transient cleavage furrows initiate at the proper location, but regress before the division is complete. Additionally, staining with a marker of midbody microtubules revealed that at least some of the components of the midbody are not well localized in the absence of AIR-2 activity. Our results suggest that during each meiotic and mitotic division, AIR-2 may coordinate the congression of metaphase chromosomes with the subsequent events of polar body extrusion and cytokinesis.

Show MeSH
Related in: MedlinePlus