Histological evidence of the lunar reproductive rhythm of Atlantic sea urchin Arbacia punctulata in the Gulf of Mexico

Microtubules with incomplete cylindrical structure are present in isolated mitotic spindles of the sea urchin, Arbacia punctulata. In cross-section they appear C-shaped, and are thus similar to the ‘C-microtubules’ or ‘C-filaments’ observed previously in other systems. The C-microtubules are not uniformly distributed within isolated spindles, but are typically numerous in the interzonal region of anaphase spindles and in the metaphase chromosome ‘plate’. In chromosome-to-pole regions they are seen much less frequently, and microtubules with the usual O-configuration predominate. Counts of C- and O-microtubules in anaphase spindle cross-sections of known location show an inverse relationship between the number of C-microtubules present and the total number of microtubules present. The observations suggest that the C-microtubules are not simple artifacts of fixation or isolation, but rather may represent a stage of microtubule disassembly which occurs in the interzone during isolation or during anaphase in vivo. The alternate possibility of assembly is not excluded, however. The significance of C-microtubules is further discussed with respect to their occurrence in other systems, and to potential differences between mitotic microtubules.

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The role of sea urchin grazing in regulating subtropical seagrass meadows: evidence from field manipulations in the northern Gulf of Mexico

Journal of Experimental Marine Biology and Ecology ◽

10.1016/0022-0981(91)90165-s ◽

1991 ◽

Vol 154 (2) ◽

pp. 215-230 ◽

Cited By ~ 85

Author(s):

John F. Valentine ◽

Kenneth L. Heck

Keyword(s):

Gulf Of Mexico ◽

Sea Urchin ◽

Northern Gulf Of Mexico ◽

Seagrass Meadows ◽

Urchin Grazing

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THE EXTRACELLULAR RELEASE OF ECHINOCHROME

The Journal of General Physiology ◽

10.1085/jgp.29.5.267 ◽

1946 ◽

Vol 29 (5) ◽

pp. 267-275 ◽

Cited By ~ 7

Author(s):

Herbert Shapiro

Keyword(s):

Sea Urchin ◽

Sea Water ◽

Potassium Content ◽

Red Pigment ◽

Anaerobic Conditions ◽

Outward Diffusion ◽

Arbacia Punctulata ◽

Extracellular Release

A study was made of the diffusion of the red pigment echinochrome from the eggs of the sea urchin, Arbacia punctulata, into sea water. Unfertilized eggs retained their pigment, over periods of hours. Outward diffusion of pigment from unfertilized eggs normally is entirely negligible, or does not occur at all. Enchancing the calcium or potassium content of the artificial sea water (while retaining isosmotic conditions) did not induce pigment release. Under anaerobic conditions, unfertilized eggs release pigment in small quantities. Fertilization alone brings about echinochrome release. Fertilized eggs invariably released pigment, whether in normal sea water, or sea water with increased calcium or potassium. This diffusion of the pigment began during the first cleavage, possibly soon after fertilization. The pigment release is not a consequence solely of the cell's permeability to echinochrome (or chromoprotein, or other pigment combination) but is preceded by events leading to a release of echinochrome from the granules in which it is concentrated within the cell. These events may be initiated by activation or by anaerobiosis. The phenomenon was not due to cytolysis.

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Pinocytosis in fertilized sea urchin (Arbacia punctulata) eggs

Journal of Experimental Zoology ◽

10.1002/jez.1402310315 ◽

1984 ◽

Vol 231 (3) ◽

pp. 413-422 ◽

Cited By ~ 16

Author(s):

Christopher P. Carron ◽

Frank J. Longo

Keyword(s):

Sea Urchin ◽

Arbacia Punctulata

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OOCYTE DIFFERENTIATION IN THE SEA URCHIN, ARBACIA PUNCTULATA, WITH PARTICULAR REFERENCE TO THE ORIGIN OF CORTICAL GRANULES AND THEIR PARTICIPATION IN THE CORTICAL REACTION

The Journal of Cell Biology ◽

10.1083/jcb.37.2.514 ◽

1968 ◽

Vol 37 (2) ◽

pp. 514-539 ◽

Cited By ~ 198

Author(s):

Everett Anderson

Keyword(s):

Sea Urchin ◽

Golgi Complex ◽

Morphological Evidence ◽

Cortical Granule ◽

Perivitelline Space ◽

Unit Membrane ◽

Cortical Granules ◽

Arbacia Punctulata ◽

Cortical Reaction ◽

Oocyte Differentiation

This paper presents morphological evidence on the origin of cortical granules in the oocytes of Arbacia punctulata and other echinoderms. During oocyte differentiation, those Golgi complexes associated with the production of cortical granules are composed of numerous saccules with companion vesicles. Each element of the Golgi complex contains a rather dense homogeneous substance. The vesicular component of the Golgi complex is thought to be derived from the saccular member by a pinching-off process. The pinched-off vesicles are viewed as containers of the precursor(s) of the cortical granules. In time, they coalesce and form a mature cortical granule whose content is bounded by a unit membrane. Thus, it is asserted that the Golgi complex is involved in both the synthesis and concentration of precursors utilized in the construction of the cortical granule. Immediately after the egg is activated by the sperm the primary envelope becomes detached from the oolemma, thereby forming what we have called the activation calyx (see Discussion). Subsequent to the elaboration of the activation calyx, the contents of cortical granules are released (cortical reaction) into the perivitelline space. The discharge of the constituents of a cortical granule is accomplished by the union of its encompassing unit membrane, in several places, with the oolemma.

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