368
Also fi sh cardiac ventricle possesses elastin. For example the heart of icefi sh
that can pump the very large volume of haemoglobin-less blood (Agnisola and
Tota 1994 ).
Notochord Elastin genes were found to be specifi cally expressed in the notochord
that “functions as the midline structural element of all vertebrate embryos, and
allows movement and growth at early developmental stages,” (Sagstad et al. 2011 ).
The cells termed chordoblasts are responsible for elastin gene expression here.
Swimbladder The inner layer of the swimbladder in zebrafi sh wall contains elastin
fi bers. Corresponding confi rmation has been reported by Perrin et al. ( 1999 ) as
follow:
– “Elastase delivery to the swimbladder in vitro resulted in signifi cant fragmentation of elastin in the anterior chamber.
– In situ hybridization of zebrafi sh embryos illustrated that elastin gene expression
is evident in the developing gut tract prior to swimbladder morphogenesis.
– Northern blot analysis demonstrated that the major zebrafi sh elastin mRNA is
2.0 kb, which is signifi cantly smaller than its higher vertebrate counterpart.
– Amino acid analysis of alkali-resistant protein from the anterior chamber of the
adult zebrafi sh swimbladder showed a composition similar to higher vertebrate
elastins, including signifi cant amounts of desmosine crosslinks,” (Perrin et al.
1999 ).
10.3 Cetacean Elastin
The protein elastin, a major component of the large, elastic arteries, provides the
elasticity necessary for cyclic deformation of the arterial wall with minimal energy
loss. Elastin provides elasticity and reversible stretch to accommodate pulsatile
pressure waves from the heart. The arterial pressure pulse magnitude decreases with
distance from the heart, due to the pulse-dampening function of the elastic arteries
(Cheng and Wagenseil 2012 ). The amount of elastin also decreases with distance
from the heart, as less pulse dampening is required in the distal vessels. The amount
of collagen, which provides strength and limits stretch at high pressures, remains
approximately constant with distance from the heart (Dobrin 1997 ). The elastic
modulus of collagen is 100–1,000 times higher than elastin, so the decrease in the
ratio of elastin to collagen provides a gradient of arterial stiffening down the vascular tree (Greenwald 2007 ). The large elastic or conducting arteries are those closest
to the heart, and have relatively high elastin to collagen ratios. The role of elastin as
an arterial pulse dampener, or windkessel (Dobrin 1997 ), is supported by evolutionary evidence.
Elastin is found exclusively in vertebrate animals, and its emergence coincides
with the appearance of a closed circulatory system (Sage and Gray 1979 ). Turnover
of elastin is slow, and assembly of elastic fi bers is negligible in adult animals;
10 Marine Elastin
Also fi sh cardiac ventricle possesses elastin. For example the heart of icefi sh
that can pump the very large volume of haemoglobin-less blood (Agnisola and
Tota 1994 ).
Notochord Elastin genes were found to be specifi cally expressed in the notochord
that “functions as the midline structural element of all vertebrate embryos, and
allows movement and growth at early developmental stages,” (Sagstad et al. 2011 ).
The cells termed chordoblasts are responsible for elastin gene expression here.
Swimbladder The inner layer of the swimbladder in zebrafi sh wall contains elastin
fi bers. Corresponding confi rmation has been reported by Perrin et al. ( 1999 ) as
follow:
– “Elastase delivery to the swimbladder in vitro resulted in signifi cant fragmentation of elastin in the anterior chamber.
– In situ hybridization of zebrafi sh embryos illustrated that elastin gene expression
is evident in the developing gut tract prior to swimbladder morphogenesis.
– Northern blot analysis demonstrated that the major zebrafi sh elastin mRNA is
2.0 kb, which is signifi cantly smaller than its higher vertebrate counterpart.
– Amino acid analysis of alkali-resistant protein from the anterior chamber of the
adult zebrafi sh swimbladder showed a composition similar to higher vertebrate
elastins, including signifi cant amounts of desmosine crosslinks,” (Perrin et al.
1999 ).
10.3 Cetacean Elastin
The protein elastin, a major component of the large, elastic arteries, provides the
elasticity necessary for cyclic deformation of the arterial wall with minimal energy
loss. Elastin provides elasticity and reversible stretch to accommodate pulsatile
pressure waves from the heart. The arterial pressure pulse magnitude decreases with
distance from the heart, due to the pulse-dampening function of the elastic arteries
(Cheng and Wagenseil 2012 ). The amount of elastin also decreases with distance
from the heart, as less pulse dampening is required in the distal vessels. The amount
of collagen, which provides strength and limits stretch at high pressures, remains
approximately constant with distance from the heart (Dobrin 1997 ). The elastic
modulus of collagen is 100–1,000 times higher than elastin, so the decrease in the
ratio of elastin to collagen provides a gradient of arterial stiffening down the vascular tree (Greenwald 2007 ). The large elastic or conducting arteries are those closest
to the heart, and have relatively high elastin to collagen ratios. The role of elastin as
an arterial pulse dampener, or windkessel (Dobrin 1997 ), is supported by evolutionary evidence.
Elastin is found exclusively in vertebrate animals, and its emergence coincides
with the appearance of a closed circulatory system (Sage and Gray 1979 ). Turnover
of elastin is slow, and assembly of elastic fi bers is negligible in adult animals;
10 Marine Elastin