The immunological response to handling stress of four tilapia species is evaluated.Polymorphism is examined in genes known to influence immune response in fish

Cnaani, A.

Hulata, G.

Ron, M.

Seroussi, E.

English

Aquatic Commons

Naga, The ICLARM Quarterly (Vol. 25, No. 2) April-June 200240
INGA NEWS
Genetic Analysis of
Immunological Traits in Tilapia
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The immunological response to handling stress of four tilapia species is evaluated. Polymorphism is
examined in genes known to influence immune response in fish.
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A comparative evaluation of a
series of biochemical blood
parameters and of immunological
indicators in response to handling
stress was conducted in four species
of tilapia (Oreochromis aureus, O.
mossambicus, O. niloticus and red
O. niloticus).  Significant
differences were observed among
the four tilapia species in the
following biochemical blood
parameters: total protein, albumin,
globulin, cholesterol, triglicerides,
bilirubin, b-hydroxybutiric acid,
calcium, magnesium and phosphorus,
and the following immunological
indicators in response to stress:
hematocrit, glucose and lysozyme
activity.  O. aureus differed from
the other three species in all variables
mentioned above, with largest
differences occurring between O.
aureus and O. mossambicus (Palti
et al. 1999).  None of these
parameters differed significantly
between males and females, nor
was a correlation with fish size
observed.
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A breeding family, consisting of
O. mossambicus females and O.
aureus males, which participated in
the above-mentioned experiment,
was established to produce F1
hybrids.  F
1
 hybrid progeny were
obtained and reared to sexual
maturity.  Three breeding families,
each consisting of a single F
1
 male
and 4-6 F1 females were established
and four F2 progenies, each
consisting of 200 or more individuals
were obtained.  These batches were
9 months old at the time of reporting
(October 2001) and ready for blood
sampling and testing immunological
response to handling stress.
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A few F
1
 fish, and their
respective O. aureus and O.
mossambicus parents were
screened using 65 microsatellite
markers.  Thirty-five of those were
found to be informative (i.e.,
heterozygous in the F
1
 generation).
These markers will be used to scan
the genome of the F
2
 generation in
search for QTLs (Quantitative Trait
Loci) for immune response and
disease resistance.
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Polymorphism was examined in
several genes, known to play a role
in the immune system.  Different
genotypes of these genes are known
to influence immune response in fish
and avian species.
The MHC genes: The major
histocompatibility complex (MHC)
genes are attractive candidates for
this approach.  Primers for various
loci of the O. niloticus MHC system
(Mallaga-Trillo et al. 1998; Sato et
al. 2000) were used for PCR
(Polymerase Chain Reaction).
Products were cloned into plasmids
and sequenced.  Two loci of MHC
class II were identified, using primers
flanking intron-1 and exon-3, and one
of MHC class I, using primers
flanking intron-3.  Using
polymorphism found in the MHC
class I locus, a segregating family
was genotyped.  This locus was
found to be located on linkage group
#15 of the tilapia linkage map.  Single
nucleotide polymorphism (SNP) sites
were found in a coding region (exon)
of one loci of MHC class II for the
two parental species, O. aureus and
O. mossambicus.
Genes of the non-specific
immune system: The gene
sequences coding for enzymes of the
innate immune system are not known
in species of the Cichlidae family or
in any fish from the order
Perciformes.  A search in the
GeneBank database for known
Naga, The ICLARM Quarterly (Vol. 25, No. 2) April-June 2002 41
sequences in fish species belonging
to three different orders (flounder,
salmon, trout, medaka and zebrafish)
revealed conserved regions in
several such genes.  Heterologous
primers were designed at the
conserved regions for detection of
three genes: transferrin, lysozyme
and ceruloplasmin.  So far, only the
primers for transferrin resulted in
good PCR amplification; the product
obtained was cloned into a plasmid
and sequenced.  Comparison with
known sequences in the databases
confirmed that this is indeed a
section of the gene for transferrin,
which consists of four exons and
three introns.  Length polymorphism
was found in one of these introns
and specific primers were designed
to trace the segregation of these
alleles.  A mapping family, consisting
of 129 individuals, was genotyped for
the transferrin site.  The gene for
transferrin was located on linkage
group #18 along with nine
microsatellite markers (Cnaani et al.
2002).
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Cnaani, A., M. Ron, B.-Y. Lee, G. Hulata,
T.D. Kocher and E. Seroussi. 2002.
Mapping the transferrin gene in tilapia.
Anim. Genet. 33: 78-80.
Málaga-Trillo, E., Z. Zaleska-Rutczynska,
B. McAndrew, V. Vincek, F. Figueroa,
H, Sültmann. and J. Klein. 1998. Linkage
relationships and haplotype
polymorphism among cichlid Mhc class
II loci. Genetics 149: 1527-1537.
Palti, Y., S. Tinman, A. Cnaani,Y. Avidar, M.
Ron and G. Hulata. 1999. Comparative
study of biochemical and non-specific
immunological parameters in two tilapia
species (Oreochromis aureus and O.
mossambicus). Israeli J.  Aquacult.-
Bamidgeh 51: 148-156.
Sato, A., F. Figueroa, B.W. Murray, E.
Málaga-Trillo, Z. Zaleska-Rutczynska,
H. Sültmann, S. Toyosawa, C.
Wedekind,N. Steck and J. Klein. 2000.
Nonlinkage of major histocompatibility
complex class I and class II loci in bony
fishes. Immunogenetics 51: 108-116.
A. Cnaani is a postgraduate student,
M. Ron and E. Seroussi are research
scientists, and G. Hulata is a research
scientist at the Department of Aquaculture,
Institute of Animal Science, Agricultural
Research Organization, Bet Dagan, Israel.
Progress on Genetic Improvement of Rohu in India
The Indo-Norwegian project on
“Genetic improvement of Rohu,
Labeo rohita for growth through
selective breeding” initiated at the
Central Institute of Freshwater
Aquaculture (CIFA) in collaboration
with the Institute of Aquaculture
Research (AKVAFORSK), Norway in
1992 is now in its second phase.
The project started with the
collection of base population from 5
rivers (Ganga, the Yamuna, Gomati,
Brahmaputra and the Sutlej) along
with the CIFA farm stock. Growth
and survival were considered as traits
for selection. Combined selection
method was adopted for breeding
value estimation. During the execution
of the project many methods and
protocols for selective breeding were
standardized (i.e. production of full-
sib groups, rearing of full-sib groups
in nursery as well as in laboratory,
tagging with PIT tag, rearing of
fingerlings in the communal ponds
and data analysis using SAS package
for breeding value estimation and other
analysis). The major findings of the
project are: (i) large differences in
growth observed between fullsib
families within stocks both in mono-
and polyculture systems; (ii)
substantial additive genetic variation
for growth performance; (iii) highly
consistent ranking of stocks and full-
sib groups for growth in mono and
polyculture system indicating that
genotype by environmental interaction
is low for growth trait in present
production systems.; (iv) diallel cross
of five stocks indicated negative
heterosis effect; hence pure breeding
may be suitable method of selection;
(v) average 34.5% realized selection
response at its second generation of
selection.
Multilocational field-testing of
improved strain (3rd generation) is in-
progress at three sites (Jallandhar,
Punjab; Vijayawada, Andra Pradesh;
and Rahara, West Bengal).
Survey of carp hatcheries in
Orissa State undertaken by CIFA to
determine the rate of inbreeding
revealed high rate of inbreeding (i.e.
1.67-12.16%) for different carp
species in these hatcheries. The rate
of inbreeding was observed to be
higher in the case of exotic carps than
in indigenous carps. Guidelines were
prepared for the hatcheries to improve
the genetic status of carp stocks.
For further information, contact:
Director, Central Institute of
Freshwater Aquaculture, P.O.
Kausalyaganga, Bhubaneswar – 751
002, Orissa, India; Tel: 91-674-
465421; 465446; 465430; Fax: 91-
674-465407; E-mail: cifa@ori.nic.in;
cifa@hub1.nic.in
n
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Naga, The ICLARM Quarterly (Vol. 25, No. 2) April-June 200242
Publication of Interest (in Chinese)
Book on biodiversity and
conservation of major fishes in
Yangtze River, China
The Yangtze River is the major
habitat of important fish resources and
cradle of freshwater aquaculture in
China. The river basin has produced
60% of freshwater fish production (by
weight) in the country. However, the
stress on biodiversity especially on
aquatic animals is high in this river.
The book entitled A Study on
Biodiversity and Conservation of
Major Fishes in the Yangtze River (in
Chinese) by Li Sifa describes the
author’s extensive work on genetic
resources and sustainable development
of fisheries in the Yangtze River. The
170-page book focuses on fish
biodiversity, particularly on genetic
diversity of important and/or
endangered economic fish species.
For more information, contact: Dr.
Li Sifa, Director, Aquatic Genetic
Resources Laboratory, Shanghai
Fisheries University, 334 Jun Gong
Road, Shanghai 200090 China; Tel:
(86-21) 6571 0333; Fax: (86-21)
65684153; E-mail: lisifak@online.
sh.cn
Improved Strain of Freshwater Prawn
A private company in Thailand,
Charoen Pokhphand Foods, has
developed a new breed of giant
freshwater prawn (Macrobrachium
rosenbergii), which has higher meat
yield and size uniformity than the
traditionally farmed strain. The
improved strain has a meat content
of as high as 60%, twice of the
undeveloped strain and is harvestable
after four months. A hatchery, with
an initial capacity of 50 million post-
larvae a month, is being built in
Ayuthaya. In view of this positive
development, the new breed is seen
as a potential substitute for the black
tiger shrimp (Penaeus monodon),
after a ban was imposed on the
farming of this species in inland areas
of Thailand following complaints that
it was causing salinization of paddy
fields and fruit orchards.
Source: INFOFISH International
6/2001 (November/December).
Patented Genetically Modified Salmon
The European Patent Office has
approved the first patent for a
genetically modified Atlantic salmon.
The modified fish which is owned by
a Canadian company, Genesis Group
Inc and Massachussetts-based Aqua
Bounty Farms carries an additional
gene for faster growth. The fish has
been reported to grow eight times
bigger than usual. Strong concerns
have been expressed however by
some groups calling for a ban to
release the genetically modified fish
in the commercial market.
Source: INFOFISH International
6/2001 (November/December).
New Development in Tilapia Research
The Freshwater Fisheries
Research Center (FFRC) of the
Chinese Academy of Fisheries
Sciences has succeeded in
hybridization of Tilapia sp (Family
Cichlidae) with Siniperca chuatsi
(Family Serranidae).
FFRC has optimized the best
conditions for hybridization and the
treatment of fertilized eggs.
According to FFRC, the success
would provide data on mechanisms
of hybridization on the one hand and
could breed a new fish species better
than their parents on the other. As is
well known, tilapia grows fast with
omnivorous feeding habit and strong
resistance to diseases but they cannot
endure low temperature. S. chuatsi
has quality meat and is cold resistant
with great economic value but they
subsist on live feeds throughout their
life cycle. The new hybrid is expected
to have desirable traits of parents.
For further information, contact
Xia Dequan, Freshwater Fisheries
Research Center, Qitang, Wuxi,
Jiangsu, China; Tel: (86) (510)
5801424; Fax: (86) (510) 5803304


Genetic analysis of immunological traits in tilapia

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Genetic analysis of immunological traits in tilapia

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