Soluble microtubule proteins of the sea urchin embryo: Partial characterization of the proteins and behavior of the pool in early development

Raff, Rudolf A.; Kaumeyer, John F.

doi:10.1016/0012-1606(73)90243-1

Cited by 84 publications

(23 citation statements)

References 32 publications

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“…In the above case, taxol would bind to almost all tubulin dimers in the egg cytoplasm because the concentration of tubulin dimers of 5.1 µM reported by Raff and Kaumeyer [1973] is much less than 20 µM. On the other hand, in this study, when 0.1-1 mM of taxol was injected at the smaller doses, resulting in the final concentration of 0.25-2.5 µM of taxol in the cytoplasm, taxol locally affected MT assembly and stability in the mitotic apparatus and modified cleavage furrow formation.…”

Section: Discussion Local Effect Of Taxol On the Mitotic Apparatusmentioning

confidence: 92%

Displacement of cleavage plane in the sea urchin egg by locally applied taxol

Hamaguchi

1998

Cell Motil. Cytoskeleton

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Section: Discussion Local Effect Of Taxol On the Mitotic Apparatusmentioning

confidence: 92%

Displacement of cleavage plane in the sea urchin egg by locally applied taxol

Hamaguchi

1998

Cell Motil. Cytoskeleton

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“…SWANN and MITCHISON, 1958;WOLPERT, 1960;RAPPAPORT, 1971). The abnormality of cleavage in the cells injected with colchicine suggests that the mitotic apparatus acts as a passive guide for the furrow (SWANN and MITCHISON, 1953).…”

Section: Discussionmentioning

confidence: 99%

“…It is reasonable to expect that the spindle and asters can be formed and cleavage take place if 5S% of the total tubulin dimer is present, since the pool of microtubule protein is greater than that actually utilized (INOUE and SATO, 1967;STEPHENS, 1972), whereas the mitotic apparatus will disintegrate and cleavage be suppressed by reducing the free tubulin concentration to 4% of the normal value. It is, however, also possible that a certain amount of insoluble colchicine-binding activity exists in sea urchin eggs (RAFF and KAUMEYER, 1973), and that in consequence the amount of free tubulin dimer required to form a functional mitotic apparatus can not be estimated exactly. On the other hand, TAYLOR (1965) reported that the inhibition of cleavage by colchicine in human cells occurred if about 3 to 5% of the whole colchicine-binding activity in the cell combined with colchicine.…”

Section: Discussionmentioning

confidence: 99%

Microinjection of Colchicine Into Sea Urchin Eggs

Hamaguchi

1975

Dev Growth Differ

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Inhibition of cleavage by colchicine was examined by microinjecting colchicine solution into one of the blastomeres of a sea urchin egg at the two-cell stage. Cleavage was inhibited if the microinjection was made before a critical point prior to the cleavage, whereas cleavage occurred in spite of the destruction of the mitotic apparatus if the microinjection was made after the critical point. The critical point was 10 min before the mid-stage of the cleavage in Clypeaster japonicus and 8 min before the mid-stage in Temnopleurus toreumaticus at 20 + 1"C, corresponding to the beginning of anaphase. The threshold for the cleavage inhibition of colchicine was estimated to be 3 X M to 3 X M in final concentration in the cell.Colchicine is believed to inhibit cell division by preventing the formation of spindle and asters or destroying them after their formation. On the other hand, it has been established that cleavage takes place after destruction of the mitotic apparatus at anaphase or later by mechanical agitation with a microneedle (1 953) observed that cleavage took place in sea urchin eggs even though the mitotic apparatus was destroyed by external application of colchicine during or after anaphase, whereas cleavage was inhibited if colchicine was applied before early anaphase. These facts suggest that the occurrence of cleavage is determined by a stimulus provided by the mitotic apparatus and that cleavage can proceed independent of the presence or absence of the mitotic apparatus after functional differentiation of the cortical cytoplasm is once established by such a stimulus.The author attempted to determine more accurately this critical point for cleavage inhibition by microinjection of colchicine solution at different times and to determine the critical amount of colchicine for cleavage inhibition. MATERIALS AND METHODSEggs of the heart urchin, Clypeaster japonicus, and the regular sea urchin, Temnopfeurus 111

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“…It is not known whether the increase in the steady-state EMAP protein levels reflects an increased synthesis from embryonic or zygotic transcripts or whether there is a decrease in EMAP protein turnover. The accumulation of EMAP mRNA and protein mirrors the accumulation of α and β tubulin heterodimers (Raff 1975;Raff and Kaumeyer 1973) and RNA transcripts (Alexandraki and Ruderman 1985). Thus, the two major components of sea urchin microtubules appear to be expressed in parallel.…”

Section: Emap Is Abundant In Eggs and Embryosmentioning

confidence: 99%

Conservation of the WD-repeat, microtubule-binding protein, EMAP, in sea urchins, humans, and the nematode C. elegans

Suprenant¹,

Tuxhorn²,

Daggett³

et al. 2000

Dev Gene Evol

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The echinoderm microtubule-associated protein (EMAP) is the most abundant microtubule-binding protein in the first cleavage mitotic apparatus in sea urchin embryos. The first goal of this study was to determine whether there is sufficient EMAP in the egg and embryo to modify microtubule dynamics during the early cleavages divisions and whether EMAP functions at a specific time or place in the embryo. To accomplish this goal, we examined the relative abundance, tissue distribution, and temporal pattern of EMAP expression during embryonic development. The second goal of this study was to identify important functional domains within the EMAP coding sequence. A conserved sequence might reveal a potential microtubule-binding domain. We cloned, sequenced and compared overlapping EMAP cDNAs from two different sea urchin species that diverged approximately 80 million years ago, and compared these with cDNA sequences from a vertebrate and nematode species. From quantitative immunoblots, we determined the EMAP concentration in eggs to be 4 microM. The steady-state levels of EMAP mRNA and protein accumulated during development, and all three germ layers expressed EMAP. During the early stages of development, EMAP and tubulin were both abundant in the ectoderm, mesoderm and endoderm. However, during late gastrulation and the formation of the early pluteus larvae, EMAP was enriched in the mesoderm, while tubulin staining was most abundant in the archenteron. These results indicate that EMAP may have tissue-specific functions in the late stage embryo. To identify conserved functional domains, we compared the predicted amino acid sequence encoded by Strongylocentrotus purpuratus and Lytechinus variegatus EMAP cDNAs, and determined that these two sea urchin EMAPs were 95% conserved and shared an identical domain organization. A parsimonious analysis of these sea urchin protein sequences, as well as human and C. elegans EMAP sequences was used to construct a gene tree. Together these results suggest that EMAP is an important microtubule protein required at all developmental stages of sea urchins, and whose cellular function may be conserved amongst metazoans.

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Soluble microtubule proteins of the sea urchin embryo: Partial characterization of the proteins and behavior of the pool in early development

Cited by 84 publications

References 32 publications

Displacement of cleavage plane in the sea urchin egg by locally applied taxol

Displacement of cleavage plane in the sea urchin egg by locally applied taxol

Microinjection of Colchicine Into Sea Urchin Eggs

Conservation of the WD-repeat, microtubule-binding protein, EMAP, in sea urchins, humans, and the nematode C. elegans

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