Download MUSCLE GROWTH OF NILE TILAPIA Oreochromis niloticus GIFT

MUSCLE GROWTH OF NILE TILAPIA
Oreochromis niloticus GIFT STRAIN
Vander Bruno dos Santos¹*, Edson Assunção Mareco², Rondinelle Artur S. Salomão² Robson
Maciel da Silva³, Maeli Dal Pai Silva4
POLO REGIONAL ALTA SOROCABANA
Aquaculture América
1 Researcher from Polo Regional Alta Sorocabana / Agência Paulista de Tecnologia dos Agronegócios - APTA, SP, BRAZIL; 2 Posgraduating from UNESP, SP, Brasil; 3 APTA; 4 Researcher from UNESP. *Corresponding author: [email protected]
1. INTRODUCTION
The swimming muscle constitutes the edible part of teleost fish
and it is divided into several parts containing different muscle fiber
types. Phenotypic variation in morphological characteristics of muscle
tissue, as the fiber number and size, is due to genetic and
environmental factors. Muscle growth in fish occurs by both
hypertrophy and hyperplasia from undifferentiated myogenic progenitor
cells or myoblasts (Johnston, 2006). The objective of this study was to
evaluate the muscle growth of Nile tilapia, GIFT strain (Genetically
Improved Farmed Tilapia).
2. MATERIALS AND METHODS
A
One hundred and twenty fish weighing 1.4 g were cultivated in
tanks of 0.5 m³, in indoor recirculation systems at 28 ºC. It was
evaluated the fish weight, standard length, diameter and density of
white muscle fibers and the MyoD and myogenin gene expression at 7,
30 and 60 days of cultivation. Diameter and density of fibers were
evaluated in slides of muscle tissue in microscope coupled to a system
of image analysis. MyoD and myogenin gene expression levels were
detected by reverse transcription quantitative real-time polymerase
Chain Reaction (RT-qPCR).
3. RESULTS AND DISCUSSION
B
After 30 days of cultivation, tilapias achieved 12.9 g and 6.7 cm,
and after 60 days 50.5 g and 10.6 cm. It can be observed that diameter
and density of white fibers and MyoD and myogenin gene expression
did not present difference at 7 or 30 days of cultivation. However, at 60
days tilapias presented increase in diameter and decreasing in density
of muscle fibers diameters, indicating the hypertrophy process. Skeletal
muscle growth in fish is dependent on the proliferation and
differentiation of myogenic progenitor or satellite cells that express
several transcriptional activators; these control the expression of
muscle-specific gens and contribute to hyperplasia and hypertrophy.
Myogenic precursor cell activity is regulated by differential expression
of myogenic regulatory factors (MyoD family) (Watabe 1999).
MyoD presented higher gene expression than myogenin
and it was constant, but myogenin increased at 60
days of cultivation, showing its relation with
differentiation and fusion for muscle
fibers hypertrophy, contributing
for the fish growth.
Fig 1. (A) Diameter (µm) and density (fibers/mm²) of white muscle fibers. (B) Myod and miogenin gene
expression.
4. CONCLUSION
Tilapia GIFT strain present fiber muscle hypertrophy at 60 days
of cultivation with higher myogenin gene expression during the growth.
5. ACKNOWLEDGEMENTS
Financial support was given by Fapesp, SP, Brazil and CNPq.
6. REFERENCES
JOHNSTON I.A (2006) Environment and plasticity of myogenesis in
teleost fish. The Journal of Experimental Biology 209, 2249-2264.
WATABE S. (1999) Myogenic regulatory factors and muscle
differentiation during ontogeny in fish. Journal of Fish Biology 55, 1-18.