Mineral fine structure defends the cuticle of the American lobster (Homarus americanus)

J.G. Kunkel, W. Nagel, M. JercinovicUMass Amherst, MA

An Apatite for Lobster?

Calcite and Amorphous Calcium Carbonate

Calcite vs Apatite: Contrasting functions in lobster cuticle

Bone (Carbonate Apatite) in Canals and Trabeculae

Biomineralization Models

Lobster as a model system in study of composite materials

Properties are computed for a hierarchically averaged material! (Raabe 2010) Dusseldorf (Raabe), Ulm (Ziegler) and Linz (Hild)

Cuticle Heterogeneity: Organules - Bristles and

Dermal Glands1

1

2

2

3

3Three or four stadia of organule development: 10% linear growth requires 21% increase per molt.

Electron Microprobe Images of Lobster Minerals

Flexible Carbonate-Apatite Formula

Ca10-x+u(PO4)6-x(CO3)x(OH)2-x+2u • z H2O

BoneTrabecula:

Canals andTrabeculae

Canal (False Color) Mineral ID

Canal (False Color) Mineral ID

Major Conclusion:

• Lobsters use ‘apatite’ for critical skeletal structures.– Apatite: Ca5(PO4)3 OH Ca:P = 5:3 Ca/P = 1.667– Dermal gland and neurite canals - Ca:P 2:1 - - 7:1– A flexible carbonate apatite formula is followed.

– Ca10-x+u(PO4)6-x(CO3)x(OH)2-x+2u • z H2O

x u z Ca:P Ca/P CO3/Ca1 1 1 2:1 2.0 0.102 1 1 9:4 2.25 0.223 1 1 8:3 2.67 0.3754 1 1 7:2 3.5 0.5715 2 1 7:1 7.0 0.714

Major Conclusion about divalent Cations:• Ca has an even density across the calcite layer.• Mg + other divalent cations decline in density toward surface.• Carbonate dissolution at cuticle surface makes surface alkaline.

Artificial Lesions

d1 ----------------------------- d34 --------------------------------------- d59

d1 ========================== d25 Aug 26 Sept 29 Oct 24

Probing Protocol for Ion and O2 Flux

Artificial Lesion H+ and Ca2+ Flux in pH 8.2 Bkg

Mineral Model of Lobster Cuticle

Acknowledgements• UMass Amherst, Biology

Al Shipley, Mike Zeitchek, Amanda Sceusa, Edwin Han, Sunyoung Yang.

• UMass Amherst, GeosciencesMike Jercinovic Sheila SeamensAnna Keskula

• LM-University, Munich, GermanyWolfram Nagel, Physiology

• Johannes Kepler University, Linz, Austria Sabine Hild, Polymerwissenschaft InstituteKatja Huemer

• URI: Kathy Castro, Barbara Somers, Thomas Angell• Maine DMR: Carl Wilson, Maine Ventless Trap program