Food Biochemistry and Food Processing (2 edition)

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414 Part 3: Meat, Poultry and Seafoods

Table 22.1.(Continued)

Protein

Sequences

Nucleotide

Sequences

Protein

Sequences

Nucleotide

Sequences

Orange roughy (Hoplostethus

atlanticus)

11 40 Astacidea(lobsters and crayfishes) 1,742 4,466

Pleuronectiformes(flatfishes) 4,109 11,851 American lobster (Homerus

americanus)

195 173

Atlantic halibut (Hippoglossus

hippoglossus)

218 2,958 European crayfish (Astacus

astacus)

28 39

Witch (Glyptocephalus cynoglossus) 22 54 Langoustine (Nephrops

norvegicus)

19 35

Plaice (Pleuronectes platessa) 88 285 Brachyura (short-tailed crabs) 5,143 8,238

Winter flounder

(Pseudopleuronectes americanus)

139 196 Edible crab (Cancer pagurus)3738

Turbot (Scophthalmus maximus) 385 1,014 Blue crab (Callinectes sapidus) 123 133

Source:(a)http://www.ncbi.nlm.nih.gov/Taxonomy/taxonomyhome.html/.

The developmental changes in the composition of muscle pro-

tein isoforms have been tracked by proteome analysis in African

catfish (Heterobranchus longifilis) (Focant et al. 1999), com-

mon sole (Solea solea) (Focant et al. 2003), and dorada (Brycon

moorei) (Huriaux et al. 2003). These studies demonstrated that

the muscle shows the usual sequential synthesis of protein iso-

forms in the course of development. For example, in the common

sole, 2DE revealed two isoforms (larval and adult) of myosin

light chain 2, and likewise in dorada larval and adult isoforms

of troponin I were sequentially expressed during development.

Proteomic techniques have, thus, been shown to be applicable

for investigating cellular and molecular mechanisms involved in

the morphological and physiological changes that occur during

fish development.

The major obstacle on the use of proteomics in embryonic fish

has been the high proportion of yolk proteins. These interfere

with any proteomic application that intends to target the cells

of the embryo proper. In a recent study on the proteome of

embryonic zebrafish, the embryos were deyolked to enrich the

pool of embryonic proteins and to minimize ions and lipids

found in the yolk prior to two-dimensional gel analysis (Tay

et al. 2006). Despite this undertaking, a large number of yolk

proteins remained prominently present in the embryonic protein

profiles. Link et al. (2006) published a method to efficiently

remove the yolk from large batches of embryos without losing

cellular proteins. The success in the removal of yolk proteins

by Link et al. (2006) is probably due to dechorionation prior to

the deyolking of the embryos. By dechorionation, the embryos

fall out of their chorions facilitating the removal of the yolk

(Huriaux et al. 1996, Westerfield 2000).

Changes in the Proteome of Early Cod Larvae

in Response to Environmental Factors

The production of good quality larvae is still a challenge in ma-

rine fish hatcheries. Several environmental factors can interfere

with the protein expression of larvae affecting larval quality like

growth and survival rate. Proteome analysis allows us to exam-

ine the effects of environmental factors on larval global protein

expression, posttranslational modifications, and redistribution of

specific proteins within cells (Tyers and Mann 2003), all impor-

tant information for controlling factors influencing the aptitude

to continue a normal development until adult stages.

A variety of environmental factors have shown to improve

the health and survival of fish larvae, including probiotic bac-

teria (Tinh et al. 2008) and protein hydrolysates (Cahu et al.

1999). However, the beneficial effects of these treatments on

fish larvae are poorly understood at the molecular level. Only

a few proteome analysis studies on fish larvae have been pub-

lished (Focant et al. 2003, Tay et al. 2006, Guðmundsdottir ́

and Sveinsdottir 2006, Sveinsd ́ ́ottir et al. 2008, Sveinsdottir ́

and Guðmundsdottir 2008, Sveinsd ́ ottir et al. 2009), of which ́

two have focused on the changes in the whole larval pro-

teome after treatment with probiotic bacteria (Sveinsd ́ottir et al.

2009) and protein hydrolysate (Sveinsd ́ottir and Gudmundsdottir ́

2008). These studies provide protocols for the production of

high-resolution two-dimensional gels of whole larval proteome,

where peptide mass mapping (MALDI-TOF MS) and peptide

fragment mapping (LC-MS/MS) allowed identification of ca.

85% of the of the selected cod protein spots (Guðmundsdottir ́

and Sveinsdottir 2006, Sveinsd ́ ottir and Gudmundsd ́ ottir 2008, ́

Sveinsdottir et al. 2008, Sveinsd ́ ottir et al. 2009). ́

The advantages of working with whole larvae versus distinct

tissues is the ease of keeping the sample handling to a minimum

in order to avoid loss or modification of the proteins. Neverthe-

less, there are several drawbacks when working with the whole

larval proteome, like the overwhelming presence of muscle and

skin proteins. These proteins may mask subtle changes in pro-

teins expressed in other tissues or systems, such as the gastroin-

testinal tract or the central nervous system caused by various

environmental factors. The axial musculature is the largest tis-

sue in larval fishes as it constitutes approximately 40% of their

body mass (Osse and van den Boogaart 1995). This is reflected

in our studies on whole cod larval proteome, where the majority