Biol. Mar. Mediterr. (2010), 17 (1): 78-79
M. Valente1,2, F. Maltagliati2, R. Cupido1, S. Cocito1,
A. Castelli2, F.G. Pannacciulli1
ENEA – Marine Environment Research Centre, PO Box 224 - 19100 La Spezia, Italia.
[email protected]
2
Dipartimento di Biologia, Università di Pisa, Via Derna, 1 – Pisa, Italia.
1
ABSENCE OF GENETIC STRUCTURE IN THE GORGONIAN
PARAMURICEA CLAVATA (CNIDARIA, OCTOCORALLIA),
FROM THE NW MEDITERRANEAN,
AS INFERRED BY THE COI GENE
ASSENZA DI STRUTTURA GENETICA NELLA GORGONIA
PARAMURICEA CLAVATA (CNIDARIA, OCTOCORALLIA),
DAL MEDITERRANEO NORD OCCIDENTALE,
COME EVIDENZIATO DAL GENE COI
Abstract – Sequences of the subunit I of the mitochondrial cytochrome oxidase c gene (COI) were
gathered from samples of the red gorgonian Paramuricea clavata (Risso, 1826) (Cnidaria, Octocorallia)
from four locations of the NW Mediterranean. All sequences obtained were identical showing absence of
polymorphism at this gene. A slow rate of mutation of the gene or an efficient repairing system of this
species’ mtDNA may account for this result.
Key-words: Paramuricea clavata, genetic structure, COI, NW Mediterranean.
Introduction – Paramuricea clavata (Risso, 1826), a gorgonian endemic of the
Mediterranean Sea (Carpine & Grasshoff, 1975), plays a central role in the structure
and functioning of the coralligenous community, one of the most peculiar and
diverse Mediterranean biogenic reef. Recently, in the NW Mediterranean, P. clavata
was heavily damaged by repeated mortality events that occurred in conjunction with
anomalous seawater warming (Cupido et al., 2008). Since information about gene
flow in Mediterranean gorgonians is scarce, the aim of this study was to assess the
population genetic structure of P. clavata in an area affected by mass mortality as a
consequence of climate changes. Results on species’ genetic structure and population
connectivity may provide a valuable contribution to the development of opportune
conservation plans.
To date, a single study investigated the genetic structure of this species (Calderón
et al., 2006) by employing the mtDNA gene cytochrome c oxidase I (COI). Results
highlighted lack of genetic variability in the sequence of one individual from Marseille
and two from the Medes islands (Fig. 1). Given the limited number of individuals
and the restricted geographical area examined by Calderón et al. (2006), we decided
to extend the analysis to a higher number of specimens and a broader spatial scale.
Materials and methods – Specimens were gathered from three locations in the
Tyrrhenian Sea: Elba Island (42°45’ N, 10°25’ E), Quercianella (43°27’ N, 10°21 E)
and two sites at the Isle of Tinetto (44°02’ N, 9°85’ E), and from one location in the
Catalan Sea, Palamós (41°49’ N, 3°05’ E) (Fig. 1). At least 30 samples were collected
at each location.
Each sample consisted of a 6-8 cm long fragment collected from the tip of a colony
and preserved in 96% ethanol. Sampling was carried out only on those gorgonians
that were at least 50 cm high. DNA was extracted from 20 polyps of each fragment
using a Salting Out protocol modified from Aljanabi & Martinez (1997). The new
protocol employed a highly concentrated lysing solution (EDTA 100 mM; Tris HCl
Absence of genetic structure in the gorgonian P. clavata from the NW Mediterranean
79
10 mM pH 7.5; SDS 0.6%; NaCl 400 mM) in which tissue was incubated overnight.
DNA was PCR-amplified using the COI primers reported in Calderón et al. (2006).
(COI Cni F: 5’-GGYACTYTATATTTACTATTTGG-3’; COI Cni R:
5’-CCSGCAGGATCAAAGAAWGTTG-3’). Amplified products were then purified
and sequenced by a commercial company. Two individuals were sequenced from each
location and the obtained nucleotide sequences aligned using the software BioEdit
vers. 7.0.9.0 (Hall, 1999).
Fig. 1 - Sampling locations of Calderón et al. (2006) (paddle) and of the present work (arrow).
Località di campionamento di Calderón et al. (2006) (pagaia) e del presente lavoro (freccia).
Results – PCR amplifications delivered fragments of 545 bp size. Nucleotide
sequences were inserted in GenBank and they confirmed amplification of the
COI region. All obtained sequences were identical to each other and to the one
of P. clavata deposited in GenBank by Calderón et al. (2006) (GenBank access n°:
AY827539.1).
Conclusions – The genetic homogeneity at the COI locus of P. clavata, in
individuals sampled at locations that were several hundred kilometers distant,
confirms Calderón et al.’s (2006) results even after enlargement of the study area
and use of a higher number of individual colonies. The lack of polymorphism at
the COI region in P. clavata could be attributed to a slow rate of mutation of the
gene or efficient repairing system of this species’ mtDNA. To fully accomplish the
objective of this work the characterization of genetic markers with a sufficient degree
of polymorphism is needed.
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