Light and electron microscopic studies on Kudoa pagrusi sp. n. (Myxosporea: Multivalvulida) infecting the heart of sea bream Pagrus pagrus (L.) from the Red Sea.

Abstract

A new multivalvulid species, Kudoa pagrusi sp. n., was described from the sea bream Pagrus pagrus. The cysts were oval to ellipsoidal and restricted to the cardiac muscles. The mean spore measurements were 7.0 microm in length and 6.4 microm in width as well as in thickness, while the mean polar capsule measurements were 3.7 microm in length and 1.5 microm in width. The ultrastructural features of the present species proved that the spore have four polar capsules with four shell valves that are the main criteria for genus Kudoa.

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ORIGINAL PAPER
Light and electron microscopic studies on Kudoa pagrusi
sp. n. (Myxosporea: Multivalvulida) infecting the heart of sea
bream Pagrus pagrus (L.) from the Red Sea
S. Al Quraishy & E. Koura & A. S. Abdel-Baki &
A.-R. Bashtar & N. El Deed & K. Al Rasheid &
F. Abdel Ghaffar
Received: 15 August 2007 /Accepted: 28 August 2007 / Published online: 13 November 2007
# Springer-Verlag 2007
Abstract A new multivalvulid species, Kudoa pagrusi sp.
n., was described from the sea bream Pagrus pagrus. The
cysts were oval to ellipsoidal and restricted to the cardiac
muscles. The mean spore measurements were 7.0 μm in
length and 6.4 μm in width as well as in thickness, while the
mean polar capsule measurements were 3.7 μm in length and
1.5 μm in width. The ultrastructural features of the present
species proved that the spore have four polar capsules with
four shell valves that are the main criteria for genus Kudoa.
Introduction
Myxozoans are economically important fish parasites with
over 2,180 described species (Lom and Dykova 2006). Genus
Kudoa is a myxosporean parasite of marine fishes. It has
worldwide distribution and infects wide range of host species.
This parasite is responsible for causing economic losses to the
fisheries sector by causing postmortem “myoliquefaction,”
softening of the flesh to such an extent that the fish becomes
unmarketable (Moran et al. 1999; Whipps et al. 2003).
Regarding the type of fish infected, muscle-infecting
species is predominant. Other parasite species have been
found in extramuscular localizations as brain, kidney, gills,
gallbladder, and ovaries (Swearer and Robertson 1999;
Dykova et al. 2002).
During a recent survey on the myxosporean parasites from
selected Red Sea fish, Kudoa pagrusi sp. n. is described as
new species from the heart muscle of the common sea bream
Pagrus pagrus (L.).
Materials and methods
Fresh caught fishes were purchased from fishermen at Gulf of
Suez during visits between March 2006 and March 2007. A
totalof100P. pagrus fish were examined. Gross examination
of all organs and body fluids was carried out for myxospor-
ean infection. The highly infected heart muscles were fixed in
10% neutral buffered formalin for histological preparations.
For the electron microscopy, small parts of the highly
infected heart muscles were isolated and fixed in 3%
glutaraldehyde in 0.1 M sodium cacodylate buffer (pH 7.4),
washed in the same buffer and post-fixed with 2% OsO4in
the same buffer. The tissue pieces were dehydrated in graded
ethanol and embedded in araldite. Ultrasections were stained
with uranyl acetate and lead citrate and examined with
Philips (208) electron microscope at 80–100 kV. Fresh spores
were measured and photographed using Zeiss Axiovert 100
microscope with C80 Camera. Descriptions and measure-
ments of spores followed the guidelines of Lom and Arthur
(1989). Measurements were based on 30 fresh spores, and
data were presented as mean±SD (range). Drawings were
made with the aid of a camera lucida. For permanent
preparations, air-dried smears were stained with Giemsa after
fixation in acetone-free absolute methanol.
Parasitol Res (2008) 102:205–209
DOI 10.1007/s00436-007-0748-8
S. Al Quraishy:K. Al Rasheid
Zoology Department, College of Science, King Saud University,
Riyadh, Saudi Arabia
E. Koura:N. El Deed
Zoology Department, Girls College, Ain Shams University,
Cairo, Egypt
A. S. Abdel-Baki
Zoology Department, Faculty of Science, Beni-Suef University,
Beni Suef, Egypt
A.-R. Bashtar:F. Abdel Ghaffar (*)
Zoology Department, Faculty of Science, Cairo University,
Cairo, Egypt
e-mail: fathyghaffar@yahoo.com

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Results
Light microscopy
Vegetative stage
The plasmodia of the present parasite species were detected in
the heart muscles. Up to 12 cysts were counted per infected
fish. Cysts were whitish in color, elliptical to oval in shape,
and measured 1.64±0.4 (1.27–2.2) mm in length and 0.75±
0.6 (0.70–0.86) mm in width (Figs. 1 and 2a,b).
Fig. 1 Photograph of heavily
infected hearts of sea bream
Pagrus pagrus with Kudoa
pagrusi sp. n. cysts (arrow),
(square=1 mm)
Fig. 2 a, b Photomicrographs
of Kudoa pagrusi sp. n. cysts in
the heart of sea bream Pagrus
pagrus (arrow; scale
bar=1 mm)
Fig. 3 Photomicrograph of the
semithin section of Kudoa
pagrusi sp. n. cyst surrounded
with connective tissue (arrow)
and stained with toluidine blue
(scale bar=0.2 mm)
Fig. 4 Photomicrograph of
fresh spores of Kudoa pagrusi
sp. n. (arrow; scale bar=5 μm)
Fig. 5 a, b Giemsa-stained
spores with polar capsules
(arrow) of Kudoa pagrusi sp. n.
(scale bar=5 μm)
Fig. 6 a, b Photomicrographs
of histological section through
infected heart with cysts of
Kudoa pagrusi sp. n (arrow).
The cysts were surrounded with
connective tissue (scale bar=
0.1 mm, 0.5 mm, respectively)
Fig. 7 Photomicrographs of the semithin section through the cyst of
Kudoa pagrusi sp. n. surrounded with cyst wall (CW) and containing
spores (Sp) and stained with toluidine blue (scale bar=5 μm)
Fig. 8 Electron micrograph of Kudoa pagrusi immature spore with
distinct sutures at the periphery (arrow; scale bar=0.5 μm)
206Parasitol Res (2008) 102:205–209

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Spores
Spores were typically of genus Kudoa. Mature spores were
quadrate in the apical view with nearly rounded edges.
Spore membrane was delicate, while the suture was distinct
(Figs. 4, 5a,b, and 9). The spore length was 7.0±0.8 (6.5–
8.6) μm in the lateral view, while the width and thickness
were6.4±0.4(5.8–7.2)μm.Fourpolarcapsuleswerepyrifom
inshape and were equal insize. Theymeasured 3.7±0.3 (2.6–
4.2) μm in length and 1.5±0.2 (1.0–1.8) μm in width. Polar
filament turns were not clearly seen, but when straight
released, they reached to 10–12 μm long nearly four times
longer than the polar capsule length.
Histology
The infection site of the present species was the heart muscles,
where fully developed plasmodia were detected containing
only mature spores (Figs. 3, 4, 5a,b, and 6a,b). No inflam-
matory reactions were observed. The only host reaction was
manifested by the encapsulation of the plasmodia with a thick
layer of connective tissue (Figs. 6a,b and 7).
Electron microscopy
Plasmodiaofthepresentspeciesweresurroundedwithasingle
unit membrane with few and small pinocytotic channels. Late
Fig. 9 Line diagram of Kudoa pagrusi spores infecting the heart of
Pagrus pagrus
Table 1 Comparative descriptive measurements (μm) of Kudoa pagrusi sp. n. with morphologically similar species
SpeciesSporePolar capsule SiteLocalityReferences
LengthWidthLength Width
Kudoa thyrsitis12.7 (10.0–14.0)7.1 (6.0–8.0)5.5 (4.5–6.2)
–
MuscleCanadaKabata and Whitaker
1981
Meglitsch 1948 Kudoa
clupeidae
K. branchiate
Kudoa
cerebralis
Kudoa kabatai
Kudoa
amamiensis
Kudoa
paniformis
Kudoa lunatas
Kudoa
cynoglossi
Kudoa
miniauriculata
Kudoa cascasi
6.4 (6.3–7.5)5.1(4.0–5.3)(1.5–2.6)
–
MuscleAtlantic
4.7 (4.4–4.9)
6.2 (5.6–7.0)
4.2 (3.9–4.9)
5.2 (4.5–6.5)
1.5
3.4 (2.7–4.8)
–
–
Gills
Nervous
system
Muscle
Muscle
Texas
Virginia
Joy 1972
Paperna and Zwerner
1974
Kovaleva et al. 1979
Egusa and Nakajima
1980
Kabata and Whitaker
1981
Lom et al. 1983
Obiekezie and Lick
1994
Whitaker et al. 1996
(5.0–7.7)
(5.0–6.0)
(4.0–5.0)
(4.5–5.0)
(1.5–2.0)
(1.5–2.0)
–
–
North sea
Japan
5.9 (5.0–6.5)5.3 (4.5–6.0)2.6 (1.9–3.3)
–
MuscleCanada
10.0 (9.0–11.4)
14.1 (13.8–14.4)
5.3 (4.5–6.2)
6.2 (5.8–6.5)
2.5 (2.0–3.0)
(2.9–3.2)
–
–
Muscle
Muscle
Czechoslovakia
West Africa
7.9 (7.0–8.5)5.4 (4.9–5.9)2.2 (1.8–2.3)
–
MuscleCalifornia
8.0 (6.6–8.2) 6.6 (5.8–6.9) 3.1 (2.4–3.4)
–
IntestineIndiaSarker and
Chaudhury 1996
Hallett et al. 1997
Koura 2000
Dykova et al. 2002
Kudoa ciliatae
Kudoa aegyptia
Kudoa dianae.
6.4 (6.3–7.3)
10.1 (9.1–11.4)
5.0 (4.5–5.5)
5.7 (4.5–5.9)
8.1 (7.1–8.5)
6.0 (5.5–6.5)
3.1 (2.4–3.4)
4.3 (3.2–5.9)
2.0
–
–
1.5
Intestine
Heart
Esophagus,
Mesenteries
Australia
Egypt
Czech
Kudoa
monodactyli
Kudoa pagrusi
sp. n.
8.0 (7.3–9.2)8.5 (7.7–9.1) 3.8 (3.2–4.6) 2.4 (1.9–2.7) MuscleAustraliaGunter et al. 2006
7.0 (6.5–8.6)6.4 (5.8–7.2)3.7 (2.6–4.2)1.5 (1.0–1.8) HeartEgyptPresent study
Parasitol Res (2008) 102:205–209207

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