82
J. C. Navarro et al.
are generally uncommon in vertebrates but have been found previously in marine
invertebrates, including molluscs, and now also confirmed to be present in specific
tissues of common octopus.
Molecular cloning and functional characterization of a cDNA encoding a putative elongase of very long-chain fatty acids (Elovl), a critical enzyme that catalyzes
the elongation of FA including PUFA, in common octopus, suggests its phylogenetic relation to Elovl5 and Elovl2, two elongases with demonstrated roles in PUFA
biosynthesis in vertebrates (Monroig et al. 2012b). Functional characterization of
the octopus Elovl showed the ability to elongate some C18 and C20 PUFAs, while
C22 PUFA substrates remained unmodified. Interestingly, the octopus Elovl elongates n-6 PUFA substrates more efficiently than their homologous n-3 substrates,
suggesting that n-6 PUFA may have particular biological significance in O� vulgaris, as mentioned above, and stressing again the essentiality of long-chain n-3
PUFA, and in particular DHA. Besides, the elongase also plays a pivotal role in the
biosynthesis of NMID FA.
Similar studies carried out in other cephalopods like S� officinalis show a strict
parallelism in terms of both qualitative FA composition (see Navarro and Villanueva 2000; Almansa et al. 2006) and biosynthetic capacity (Monroig et al., unpublished data). This, along with tissue FA composition (Monroig et al. 2012a),
emphasizes the importance and essentiality of long-chain FA for cephalopods, and
validates the idea of using the information to establish the guidelines of the requirements for coastal cephalopods. The recent manuscript by Valverde et al. (2012) on
lipid classes from marine species and meals intended for cephalopod feeding has
provided additional information on lipids.
5.4 Carotenoids
Carotenoid deposition has been described in cephalopods at the digestive gland
(Fox 1966) and in accessory nidamental glands (Decleir and Richard 1972; Van
den Branden et al. 1978; Van Den Branden et al. 1980) of S� officinalis and proposed to be designated as sepiaxanthine, but there is scarce information about its
physiological role. Carotenoid astaxanthin can also be deposited in the skin of S�
officinalis when fed on grass shrimp ( Palaemonetes varians; Almansa et al. 2006)
and this prey, used for cuttlefish hatchlings rearing, displays up to ten times more
carotenoid content (Domingues et al. 2004). O� vulgaris paralarvae seem to be able
to deposit part of the canthaxanthin present in Artemia spp. and to metabolize this
carotenoid to astaxanthin (Rodríguez et al., Universidad de La Laguna, unpublished
data). Fisher et al. (1956) reported the existence of vitamin A and, in some species, β-carotene in cephalopods. Taking into account the pro-vitamin A and antioxidant activity of carotenoids (Liñán-Cabello et al. 2002), and the importance of this
vitamin in photoreception, growth and development, it would be very interesting
to carry out more studies to determine the role of carotenoids in early stages of
cephalopods as suggested by Villanueva et al. (2009).
J. C. Navarro et al.
are generally uncommon in vertebrates but have been found previously in marine
invertebrates, including molluscs, and now also confirmed to be present in specific
tissues of common octopus.
Molecular cloning and functional characterization of a cDNA encoding a putative elongase of very long-chain fatty acids (Elovl), a critical enzyme that catalyzes
the elongation of FA including PUFA, in common octopus, suggests its phylogenetic relation to Elovl5 and Elovl2, two elongases with demonstrated roles in PUFA
biosynthesis in vertebrates (Monroig et al. 2012b). Functional characterization of
the octopus Elovl showed the ability to elongate some C18 and C20 PUFAs, while
C22 PUFA substrates remained unmodified. Interestingly, the octopus Elovl elongates n-6 PUFA substrates more efficiently than their homologous n-3 substrates,
suggesting that n-6 PUFA may have particular biological significance in O� vulgaris, as mentioned above, and stressing again the essentiality of long-chain n-3
PUFA, and in particular DHA. Besides, the elongase also plays a pivotal role in the
biosynthesis of NMID FA.
Similar studies carried out in other cephalopods like S� officinalis show a strict
parallelism in terms of both qualitative FA composition (see Navarro and Villanueva 2000; Almansa et al. 2006) and biosynthetic capacity (Monroig et al., unpublished data). This, along with tissue FA composition (Monroig et al. 2012a),
emphasizes the importance and essentiality of long-chain FA for cephalopods, and
validates the idea of using the information to establish the guidelines of the requirements for coastal cephalopods. The recent manuscript by Valverde et al. (2012) on
lipid classes from marine species and meals intended for cephalopod feeding has
provided additional information on lipids.
5.4 Carotenoids
Carotenoid deposition has been described in cephalopods at the digestive gland
(Fox 1966) and in accessory nidamental glands (Decleir and Richard 1972; Van
den Branden et al. 1978; Van Den Branden et al. 1980) of S� officinalis and proposed to be designated as sepiaxanthine, but there is scarce information about its
physiological role. Carotenoid astaxanthin can also be deposited in the skin of S�
officinalis when fed on grass shrimp ( Palaemonetes varians; Almansa et al. 2006)
and this prey, used for cuttlefish hatchlings rearing, displays up to ten times more
carotenoid content (Domingues et al. 2004). O� vulgaris paralarvae seem to be able
to deposit part of the canthaxanthin present in Artemia spp. and to metabolize this
carotenoid to astaxanthin (Rodríguez et al., Universidad de La Laguna, unpublished
data). Fisher et al. (1956) reported the existence of vitamin A and, in some species, β-carotene in cephalopods. Taking into account the pro-vitamin A and antioxidant activity of carotenoids (Liñán-Cabello et al. 2002), and the importance of this
vitamin in photoreception, growth and development, it would be very interesting
to carry out more studies to determine the role of carotenoids in early stages of
cephalopods as suggested by Villanueva et al. (2009).