scholarly journals Sea Urchin Covering Behavior: A Comparative Review

2017 ◽  
Author(s):  
Morgan A. Ziegenhorn
Keyword(s):  
Sea Urchin ◽  
Comparative Review

Immunogold and immunoblot studies on a cell surface protein found in primary mesenchyme cells and in the cortical secretory vesicles of the sea urchin egg

1987 ◽  
Vol 45 ◽  
pp. 832-833
Author(s):  
G.L. Decker ◽  
M.C. Valdizan
Keyword(s):  
Cell Surface ◽  
Sea Urchin ◽  
Surface Protein ◽  
Egg Cell ◽  
Secretory Vesicles ◽  
Cell Surface Protein ◽  
Surface Complexes ◽  
Mesenchyme Cells ◽  
Lowicryl K4m ◽  
Primary Mesenchyme Cells

A monoclonal antibody designated MAb 1223 has been used to show that primary mesenchyme cells of the sea urchin embryo express a 130-kDa cell surface protein that may be directly involved in Ca2+ uptake required for growth of skeletal spicules. Other studies from this laboratory have shown that the 1223 antigen, although in relatively low abundance, is also expressed on the cell surfaces of unfertilized eggs and on the majority of blastomeres formed prior to differentiation of the primary mesenchyme cells.We have studied the distribution of 1223 antigen in S. purpuratus eggs and embryos and in isolated egg cell surface complexes that contain the cortical secretory vesicles. Specimens were fixed in 1.0% paraformaldehyde and 1.0% glutaraldehyde and embedded in Lowicryl K4M as previously reported. Colloidal gold (8nm diameter) was prepared by the method of Mulpfordt.

The extracellular matrix of echinoderm and amphibian eggs: Visualization in quick-frozen, deep-etched, and rotary-shadowed specimens

1990 ◽  
Vol 48 (3) ◽  
pp. 60-61
Author(s):  
Barry Bonnell ◽  
Carolyn Larabell ◽  
Douglas Chandler
Keyword(s):  
Extracellular Matrix ◽  
Plasma Membrane ◽  
Sea Urchin ◽  
Crystalline Structure ◽  
Cortical Granule ◽  
Two Dimensional ◽  
Small Peptides ◽  
Deep Etching ◽  
Quick Freezing ◽  
Acrosomal Reaction

Eggs of many species including those of echinoderms, amphibians and mammals exhibit an extensive extracellular matrix (ECM) that is important both in the reception of sperm and in providing a block to polyspermy after fertilization.In sea urchin eggs there are two distinctive coats, the vitelline layer which contains glycoprotein sperm receptors and the jelly layer that contains fucose sulfate glycoconjugates which trigger the acrosomal reaction and small peptides which act as chemoattractants for sperm. The vitelline layer (VL), as visualized by quick-freezing, deep-etching, and rotary-shadowing (QFDE-RS), is a fishnet-like structure, anchored to the plasma membrane by short posts. Orbiting above the VL are horizontal filaments which are thought to anchor the thicker jelly layer to the egg. Upon fertilization, the VL elevates and is transformed by cortical granule secretions into the fertilization envelope (FE). The rounded casts of microvilli in the VL are transformed into angular peaks and the envelope becomes coated inside and out with sheets of paracrystalline protein having a quasi-two dimensional crystalline structure.

Introductory Remarks

1980 ◽  
Vol 38 ◽  
pp. 598-599
Author(s):  
H. Mohri
Keyword(s):  
Muscle Contraction ◽  
Experimental Evidence ◽  
Sea Urchin ◽  
Constant Length ◽  
Thin Filaments ◽  
Bridge Formation ◽  
Thick Filaments ◽  
Sliding Mechanism ◽  
Radial Spokes ◽  
Cilia And Flagella

In 1959, Afzelius observed the presence of two rows of arms projecting from each outer doublet microtubule of the so-called 9 + 2 pattern of cilia and flagella, and suggested a possibility that the outer doublet microtubules slide with respect to each other with the aid of these arms during ciliary and flagellar movement. The identification of the arms as an ATPase, dynein, by Gibbons (1963)strengthened this hypothesis, since the ATPase-bearing heads of myosin molecules projecting from the thick filaments pull the thin filaments by cross-bridge formation during muscle contraction. The first experimental evidence for the sliding mechanism in cilia and flagella was obtained by examining the tip patterns of molluscan gill cilia by Satir (1965) who observed constant length of the microtubules during ciliary bending. Further evidence for the sliding-tubule mechanism was given by Summers and Gibbons (1971), using trypsin-treated axonemal fragments of sea urchin spermatozoa. Upon the addition of ATP, the outer doublets telescoped out from these fragments and the total length reached up to seven or more times that of the original fragment. Thus, the arms on a certain doublet microtubule can walk along the adjacent doublet when the doublet microtubules are disconnected by digestion of the interdoublet links which connect them with each other, or the radial spokes which connect them with the central pair-central sheath complex as illustrated in Fig. 1. On the basis of these pioneer works, the sliding-tubule mechanism has been established as one of the basic mechanisms for ciliary and flagellar movement.

The Organization of Actin Filaments in the Stereocilia of the Bird Cochlea

1980 ◽  
Vol 38 ◽  
pp. 554-555
Author(s):  
E.J. Battles ◽  
D. DeRosier ◽  
J.C. Saunders ◽  
L.G. Tilney
Keyword(s):  
Hair Cell ◽  
Diffraction Pattern ◽  
Sea Urchin ◽  
Actin Filaments ◽  
Optical Diffraction ◽  
Dense Material ◽  
Apical Surface ◽  
Structural Rigidity ◽  
High Degree ◽  
Degree Of Order

Extending from the apical surface of each hair cell of the chick cochlea are from 75 to 200 microvilli or stereocllia and one true cllium, the kinocilium. The stereocllia are arranged in rows of progressively increasing length (Fig. 1). Within each tapering sterocilium is a bundle of actin filaments with over 900 filaments near the tip yet only approximately 25 at the base where filaments are enmeshed in a dense material (Fig. 1); from here some of the filaments enter the apical surface of the cell (cuticular plate) as a rootlet. Examination of longitudinal sections of the stereocilia (Fig. 2) show that the filaments are aligned parallel to each other and show considerable order. Examination of an optical diffraction pattern of this bundle (Fig. 4) reveal that the actin filaments are packed such that the crossover points of adjacent actin filaments are inregister. A prominent reflection at 125Å−1 demonstrates that the filaments are cjossbridged by a macromolecular bridge situated at an average of 125Å−1 intervals (Fig. 4) in transverse sections the filaments appear hexagonally packed although there are regions where the filaments are less ordered (Fig. 3). In images processed in the computer to remove, noise and enhance detail periodic nature of the bridge can be clearly seen (see arrows Fig. 5). This image resembles that of an actin paracrystal formed from sea urchin extract composed of bundles of actin filaments crossbridged by a second protein. Thus the actin filaments in the bird stereocilia by being cross-bridged and packed with a high degree of order and produces a structure with considerable structural rigidity. Embryos were studied at various stages in development in an attempt to determine how the stereocilia form and how does the actin packing develops. These stages will be discussed.

A Comparative Review of Three Introductory Texts

1989 ◽  
Vol 34 (9) ◽  
pp. 836-838
Author(s):  
Virginia Greendlinger
Keyword(s):  
Comparative Review

Cystic Bone Lesions in Horses and Humans: A Comparative Review

1998 ◽  
Vol 11 (01) ◽  
pp. 08-18 ◽  
Author(s):  
C. W. McIlwraith ◽  
J. A. Auer ◽  
Brigitte von Rechenberg
Keyword(s):  
Recurrence Rate ◽  
Subchondral Bone ◽  
Fibrous Tissue ◽  
Clinical Signs ◽  
Bone Lesions ◽  
Anatomical Location ◽  
Cystic Lesions ◽  
Bone Cysts ◽  
Biological Behaviour ◽  
Comparative Review

SummaryCases of cystic bone lesions in horses and humans were reviewed in the literature. These lesions are radiolucent areas of bone, recognized as subchondral cystic lesions in the horse (SCL), intra-osseous ganglia (IOG), subchondral bone cysts secondary to osteoarthrosis (OAC), and unicameral bone cysts (UCB) in humans. Their morphology is quite similar, consisting of lesions with a distinct cyst wall, and a cavity filled with fibrous tissue and yellowish mucoid fluid. The lesions are surrounded by sclerotic bone and can be easily diagnosed radiographically. SCL, IOG and OAC occur in the subchondral bone close to the adjacent joint, whereas UCB occur in the metaphysis of long bones. Their aetiology and pathogenesis is still unknown, although primary damage to the subchondral bone, cartilage or local blood supply and growth disturbances are discussed. In this review 703 lesions of SCL in horses, 289 lesions of IOG and 1460 lesions of UCB in humans were compared in their anatomical location and clinical signs. SCL and OAC resembled each other with respect to anatomical location. A correlation of affected bones could not be found for all four groups. Clinical presentation concerning age was most similar for SCL and UCB with both lesions mainly occurring in young individuals. Gender predominance of males was present in SCL, IOG and UCB. Clinical diagnosis was either incidental, or connected with intermittent pain in all lesions except for OAC. Additionally, the lesions were also found in conjunction with degenerative joint disease (SCL, OAC) or pathological fractures (UCB). Cystic bone lesions were either treated conservatively, surgically with curettage alone, curettage in combination with grafting procedures, or intra-lesional application of corticosteroids. SCL and UCB were similar in their biological behaviour concerning their slow response to the therapy and relatively high recurrence rate. None of the cystic bone lesions were comparable, and a common aetiology and pathogenesis could not be found.In a literature review cases of cystic bone lesions in horses and humans were compared with the goal to find a common aetiology and pathogenesis. Cystic bone lesions occur in horses as subchondral cystic lesions (SCL), and in humans as either intra-osseous ganglia (IOG), subchondral cystic lesions secondary to osteoarthrosis (OAC) or unicameral bone cysts (UCB). IOG and OAC compare with SCL mainly in the anatomical location. IOG and SCL resemble each other in size, clinical signs and histology, whereas UCB and SCL show a similar biological behaviour regarding their therapeutic response and recurrence rate. None of the cystic bone lesions in humans were comparable to the SCL in horses in all aspects. A common aetiology and pathogenesis could not be established.

Canopy structure at the edge of seagrass affects sea urchin distribution

2013 ◽  
Vol 485 ◽  
pp. 47-55 ◽  
Author(s):  
S Pinna ◽  
N Sechi ◽  
G Ceccherelli
Keyword(s):  
Sea Urchin ◽  
Canopy Structure
Sign in / Sign up

Export Citation Format

Share Document