QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online November 1, 2006
Journal of Experimental Biology 209, 4436-4443 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02527

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wilkie, I. C. Articles by Carnevali, M. D. C. Search for Related Content PubMed PubMed Citation Articles by Wilkie, I. C. Articles by Carnevali, M. D. C.

Mechanical adaptability of a sponge extracellular matrix: evidence for cellular control of mesohyl stiffness in Chondrosia reniformis Nardo

I. C. Wilkie^1,*, L. Parma², F. Bonasoro², G. Bavestrello³, C. Cerrano⁴ and M. D. Candia Carnevali²

¹ Department of Biological and Biomedical Sciences, Glasgow Caledonian University, 70 Cowcaddens Road, Glasgow G4 0BA, Scotland, UK
² Dipartimento di Biologia `Luigi Gorini', Università degli Studi di Milano, 20133 Milano, Italy
³ Dipartimento di Scienze del Mare, Università Politecnica delle Marche, 60131 Ancona, Italy
⁴ Dipartimento per lo studio del Territorio e delle sue Risorse, Università di Genova, 16132 Genova, Italy

View larger version (79K): [in a new window]   Fig. 1. Samples and experimental setup. (A) Diagrammatic vertical section through a whole specimen of C. reniformis, showing location and orientation of choanosome (CHO) and ectosome (ECT) samples. ex, exopinacoderm; s, substrate. (B,C) Drawings of vertical sections through the ectosome and choanosome. ch, choanocyte chamber; ec, exhalant canal; ic, inhalant canal; m, collagenous mesohyl. (D) Drawing showing a sample attached to a glass coverslip (cs) with cyanoacrylate cement (cy). (E) Diagrammatic lateral view of experimental set-up in which the coverslip is held horizontally in a clamp (cl) and the deflection (d) of the sample under gravity is measured after a predetermined time period (45 s unless stated otherwise). [B and C are from Grassé (Grassé, 1973)].

View larger version (9K): [in a new window]   Fig. 2. Effect of temperature on mesohyl destiffening. In this and all subsequent figures ectosome (ECT) results are coloured blue and choanosome (CHO) red, vertical bars represent standard deviations and asterisks indicate statistically significant differences between means: *P<0.05, **P<0.01, ***P<0.001. Although all deflections were measured at 0, 1, 3, 5, 7 and 9 h, in this figure the means for the different groups have been staggered to avoid overlap.

View larger version (31K): [in a new window]   Fig. 3. (A-D) Effect of cell membrane disrupters on maximally stiffened samples (i.e. protocol 1). (A) Effect of immersion for 2.5-3 h in ASW (control; CON), 1% Triton X-100 (TRI), 0.1% Quillaja saponin (SAP), deionised water (DW) and freezing at -24°C for 3 days followed by thawing (FRO). In all cases where statistics could be applied (i.e. where the standard deviation was not zero), P<0.01. (B) Reversibility of effects of membrane disrupters. After treatment and testing, all samples used for the experiments in A were left in ASW for 3.5 h then retested. In all cases where statistics could be applied, P<0.01. (C) Effect of immersion for 2 h in 0.05% nystatin (NYS). (D) Reversibility of effect of nystatin. After treatment and testing, the samples used in the experiments in C were left in ASW for 2 h then retested. (E) Effect of membrane disrupters on partially destiffened samples (i.e. protocol 2). After excision, samples were left for 5-6 h in ASW then tested (solid bars). They were then left for 2 h in the stated media (CON=ASW) and retested (cross-hatched bars). In A-D, statistical comparison is between mean deflections of ASW control and treated samples; in E, statistical comparison is between mean deflections of each group of samples before (solid bars) and after (cross-hatched bars) treatment. Vertical bars represent standard deviations and asterisks indicate statistically significant differences between means: *P<0.05, **P<0.01, ***P<0.001.

View larger version (69K): [in a new window]   Fig. 4. Effect of ion manipulation. (A) Elevated [Ca2+]. Deflection of maximally stiffened samples immersed for 2 h in normal ASW (CON), ASW containing 100 mmol l-1 Ca2+ or 0.38 mol l-1 CaCl2 (solid bars), and of the same samples after a subsequent wash for 2 h in ASW (cross-hatched bars). (B) Effect of the same agents on partially destiffened samples. After excision, samples were left for 3-4 h in ASW then tested (solid bars). They were then left for 2 h in the stated media and retested (cross-hatched bars). (C) Ca2+ depletion. Deflection of maximally stiffened samples (solid bars) immersed for 2 h in normal ASW, calcium-free ASW alone (CaFASW) or CaFASW containing 5 mmol l-1 EGTA, and of the same samples after a further wash for 4 h in ASW (cross-hatched bars). (D) Effect on maximally stiffened samples of 2 h exposure to low concentrations of EGTA (dissolved in CaFASW). (E) Effect on maximally stiffened samples of 2 h exposure to EGTA-AM (dissolved in CaFASW containing 1% DMSO). (F) Effect of EGTA on partially destiffened samples. After excision, samples were left for 3.5 h in CaFASW then tested (solid bars). They were then left for 2 h in CaFASW containing 1, 2 or 4 mmol l-1 EGTA and retested (cross-hatched bars). (G) Inorganic Ca2+-channel blockers. Deflection of maximally stiffened samples (solid bars) immersed for 1-2 h in normal ASW (CON), ASW containing 20 mmol l-1 Co2+ or ASW containing 20 mmol l-1 Mn2+, and of the same samples after a further wash for 2 h in ASW (cross-hatched bars). (H) Effect of inorganic Ca2+-channel blockers on partially destiffened samples. After excision, samples were left for 3-4 h in ASW then tested (solid bars). They were then left for 2 h in the stated media and retested (cross-hatched bars). (I) Effect of verapamil (VER; 100 µmol l-1) and nimodipine (NIM; 100 µmol l-1) on partially destiffened samples. Control: 1% methanol in ASW. In D-F and I deflections were measure after 35 s. In A,C-F,I statistical comparison is between mean deflections of ASW control and treated samples; in B,G, statistical comparison is between mean deflections of each group of samples before (solid bars) and after (cross-hatched bars) treatment. Vertical bars represent standard deviations and asterisks indicate statistically significant differences between means: *P<0.05, **P<0.01, ***P<0.001.

View larger version (16K): [in a new window]   Fig. 5. Effect on maximally stiffened samples of treatment for 1, 2 and 3 h with an extract of frozen minced tissue (EX1), unfrozen minced tissue (EX2) and the frozen residue from EX2 (EX3). Control: ASW. Deflections were measured after 35 s.