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Early Gametogenesis of Kumamoto oyster (Crassostrea sikamea)
Gametogénesis temprana en el ostión Kumamoto (Crasssotrea sikamea)
Jorge Cáceres-Martínez,1,2 Rebeca Vásquez-Yeomans2 and Yanet Guerrero-Rentería1
1 Centro de Investigación Científica y de Educación Superior de Ensenada. Departamento de Acuicultura. Carretera
Ensenada-Tijuana No. 3918, Zona Playitas. Ensenada, Baja California, 22860. México
2 Instituto de Sanidad Acuícola, A. C. (ISA). Calle 15 #265, entre Obregón y Moctezuma, Zona Centro. Ensenada, Baja
Cáceres-Martínez J., R. Vásquez-Yeomans and Y. Guerrero-Rentería. 2012. Early Gametogenesis of Kumamoto oyster
crosatellite DNA markers, concordant differences in 16S rDNA
The Kumamoto oyster, Crassostrea sikamea,
and allozymes (Banks et al
., 1993, 1994; Hedgecock et al
esis as young as 71 days old from spawning (35 days from post-
Sekino et al
., 2003; Reece et al.
, 2008; López-Flores et al
settlement) with a mean shell height of 3.0 mm. This information
Additionally, there are phenotypic and physiological differences
constitutes a new record in age-size for gametogenesis in oysters
between C. gigas
and C. sikamea
, the later has slower growth
for commercial importance and adds another biological differ-
rate, smaller size, smaller eggs, a more deeply cup-shaped left
ence comparing this species with the Pacific oyster Crassostrea
valve, and a highly wrinkled or ridged shell (Amemiya, 1928; Nu-
machi, 1978). The age and size for gametogenesis could also be different among genetically related species. The smaller size for
: Crassostrea sikamea
, gametogenesis, gonadal devel-
opment, Kumamoto oyster, sexual differentiation.
gametogenesis in C. gigas
is between 16 to 39 mm of shell height (Buroker, 1983), while for C. virginica
(Gmelin, 1791) it is smaller
than 35 mm of shell height, and as young as 42 days from post-
El ostión Kumamoto, Crassostrea sikamea
, inicia la gametogéne-
settlement (Stafford, 1913; Thompson et al
., 1996). The oyster C.
sis a una edad de 71 días después del desove (35 días después del
(Guilding, 1828) begins gametogenesis at the small-
asentamiento) con un promedio de altura de la concha de 3.0 mm.
est sizes; from 5 to 9 mm of shell height and less than 42 days old
Esta información constituye un nuevo registro en la edad y talla
from post-settlement (Vélez, 1976). Until now, there is no informa-
en la cual se inicia la gametogénesis en ostiones de importan-
tion about the age and size for the beginning of gametogenesis in
cia comercial. Adicionalmente, pone en evidencia otra diferencia
. During a histological survey of Kumamoto oysters of
biológica respecto al ostión Japonés Crassostrea gigas
< 4.5 mm of shell height and 35 days old from post-settlement, sur-prisingly, we observed gametogenesis. Results from this survey
: Crassostrea sikamea
, desarrollo gonadal, dife-
renciación sexual, gametogénesis, ostión Kumamoto.
In August 2007, one sample of 120 Kumamoto oysters from
The Kumamoto oyster, Crassostrea sikamea
Amemiya, 1928, was
a commercial hatchery in Sinaloa, Northwest Mexico, was sent
introduced for commercial culture into bahía de San Quintín, Baja
alive to the Laboratory of the Instituto de Sanidad Acuícola, A.C.
California, Mexico around 1970 from the West coast of the U.S.A.
for histological analysis. The sample was composed by oysters
as a variety of the Pacific oyster Crassostrea gigas
of 71 days old from spawning and 35 days from post-settlement,
1793) (Gobierno del Estado de Baja California Sur, 2010). Nowa-
cultured at 24 oC. A second sample of 80 oysters of similar age and
days, it is known that the Kumamoto oyster is a separate species
cultured at the same temperature was sent a month later to the
from the Pacific oyster based on molecular characterization, mi-
same laboratory. The oysters were cleaned using running water
Figure 1A-F. A. Live juvenile Kumamoto oyster. B. Undifferentiated oyster of 2.5 mm of shell height. There is no follicular develop-
ment in the connective tissue (Ct) surrounding the digestive gland. C. Male oyster of 2.7 mm of shell height with sperm (S) sur-
rounding the digestive gland. D. Female oyster of 3.5 mm of shell height with ovocytes (Ov). E. Hermaphrodite oyster of 3.00 mm
of shell height. F. Detail of hermaphrodite (encircled), showing ovogonies (Og) attached to the germinal wall of the follicle and
spermatids and spermatozoids (Sp) in the central area of the follicle.
to eliminate debris. From each sample, 54 and 58 organisms were
The shell height of the oysters from the first subsample
chosen respectively due to best appearance and entire shells.
ranged from 2 to 4.1 mm, the mean value was 2.99 mm (± 0.51
These organisms were considered as subsamples and were
SD). In Figure 1A is showing a live oyster of about 3 mm of shell
measured using a micrometer placed in a stereo microscope,
height. In 64% of individuals from this subsample, we do not de-
considering the shell height (distance from the umbo to the distal
tect gonad development and this sub-group was considered as
posterior border of the shell; Helm et al
., 2006). The whole oysters
undifferentiated (Fig. 1B); however, 36% of these oysters showed
were fixed by 24 h in Davidson’s fixative solution (Shaw & Battle,
development of reproductive follicles with sperm (Fig. 1C). The
1957) and washed in running water. Later, oysters were decalci-
fied by immersion in a solution of 10% EDTA for approximately 12
shell height of this sub-group varied from 2 to 4 mm with a mean
h (Howard et al
., 2004) and washed in running water to eliminating
value of 2.95 mm (± 0.52 SD). There was no significant difference
excess of EDTA. Thereafter, oysters were placed in histocassetes
between the shell heights of both subgroups (t
> 0.05). The
for histological process according to Shaw and Battle (1957) and
shell height of oysters from the second subsample varied from 2
they were checked for tissue alterations and general condition.
to 4.4 mm, the mean value was 3.19 mm (± 0.58 SD), 62% of the
The size of oysters from different subsamples and reproductive
oysters showed gonad development, from which 80.55% were
conditions was compared for possible significant differences us-
males, 13.89% females (Fig. 1D) and 5.56% hermaphrodites (Figs.
There was no significant difference between the shell height
Buroker, n. e. 1983. Sexuality with respect to shell length and group size
of both subsamples (t
> 0.05); however, there was a trend
Japanese oyster Crassostrea gigas
. Malacologia 23 (2): 271-279.
of larger oysters in the second subsample.
cooper, k. r. & m. Wintermyer. 2009. A critical review: 2,3,7,8 -tetrachloro-
Results indicate that gametogenesis of cultured Kumamoto
dibenzo-p-dioxin (2,3,7,8-tcdd) effects on gonad development in bi-
oyster starts in very young and small size. This finding adds an-
valve mollusks. Journal of Environmental Science and Health - Part
other biological difference between C. gigas
and C. sikamea
C. Environmental Carcinogenesis and Ecotoxicology Reviews
the later starts gamete production at about 3 mm of shell height
versus 16 mm in C. gigas
. It is important to carry out studies on
GoBierno Del estADo De BAJA cAliforniA sur. 2010. Plan Rector: Sistema
natural populations of C. sikamea
for determining if this early de-
velopment of gametes takes place in nature or if it was influenced by the hatchery operation, possible due by use of chemicals dur-
HeDGecock, D., m. A. BAnks & Z. kAin. 1999. Occurrence of the Kumamoto
ing culture (Cooper & Wintermyer, 2009). Presence of gametes in
oyster Crassostrea sikamea
in the Ariake Sea. Japan. Marine Biol-
these oysters do not means that they are physiologically viable.
Moreover, there was not observed empty follicles or the pres-
ence of hemocytes which could indicate spawning or reabsorp-
elm, m. m., n. Bourne & A. lovAtelli (eDs.). 2006. Cultivo de bivalvos en
criadero. Un manual práctico. FAO Documento Técnico de Pesca
tion process. Specific studies are needed for determining if these
small oysters may reproduce successfully and if so, how this early reproduction accounts for oyster population dynamics in nature,
HoWArD, D. W., e. J. leWis, B. J. keller & c. s. smitH. 2004. Histological
and how this information may impact management practices in
techniques for marine bivalve mollusks and crustaceans. NOAA
Technical Memorandum NOS NCCOS
The fact that the percentage of oysters showing gametogen-
lópeZ-flores, i., c. ruiZ-reJón, i. cross, l. reBorDinos, f. roBles & r. nA-
esis was greater in oysters from the second sample could be re-
vAJAs-péreZ. 2010. Molecular characterization and evolution of an
lated to their slightly larger size; in this sense, Quayle (1988) noted
interspersed repetitive DNA family of oysters. Genética
that in C. gigas
sexual maturity appears to be a function of size
rather than age. This information constitutes a new record in the
size of gametogenesis in oysters of aquaculture importance, plac-
ikHAilov, A. t., m. torrADo & J. ménDeZ. 1995. Sexual differentiation of
reproductive tissue in bivalve molluscs: identification of male asso-
ing the Kumamoto oyster (Crassostrea sikamea
) as the most pre-
ciated polypeptide in the mantle of Mytilus galloprovincialis
cocious species among cultivable oysters in the world. Precocity
International Journal of Development Biology
in bivalve mollusks has been documented in Mytilus galloprovin-cialis
Lamarck, 1819 (Mikhailov et al
., 1995; Paz et al
numAcHi, k. 1978. Japanese species, breed, and distribution. In
: Imai, T.
(Ed.), Aquaculture in shallow seas: progress in shallow sea culture,
part II, Chapter 1
, Biologial research on the oyster
. Tokyo: Koseisha Koseikakn Publishers, pp. 123-126.
The authors would like to thank Ing. Daniel Carreño Montreal from Sea Farmers, S. A. de C. V. for providing us with the oysters for the
pAZ, m., A. mikHAilov & m. torrADo. 2001. Sexual differentiation of the
study and allowing us to publish the data obtained.
somatic gonad tissue in marine bivalve mollusks: esterase- and fi-bronectin-like recognition signals. International Journal of Develop-ment Biology
QuAyle, D. B. 1988. Pacific oyster culture in British Columbia. Canadian
AmemiyA, i. 1928. Ecological studies of Japanese oysters, with special
Bulletin of Fisheries and Aquatic Sciences
reference to the salinity of their habitats. Journal of the College of Agriculture
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oyster species. Marine Biology
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) via mitochondrial DNA sequences coding for large subunit rRNA.
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Molecular Biology and Biotechnology
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and C. sikamea. Marine Biology
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: 03 de mayo de 2012.
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