NutrigeNomics: the emergiNg face of aquaculture

NutritioN

NutrigeNomics: the emergiNg face of aquaculture

NutritioN

SMIT R. LENDESMIT R. LENDE

Dept. of AquacultureDept. of Aquaculture

Content

•Aquaculture has lagged far behind medical research

in applying genetics improvement technique but this

is rapidly changing field.

•However last 25 year was favorable period for

development aquaculture genomics.

•Nutritional science has long tradition for

recommending specific diets to the farmed fishes for

getting more production.

Introduction Introduction

• Nutrigenomics is the application of high throughput genomics

tools in nutritional research.

• Nutrigenomics is the study of “how foods affect genes and

how individual differences in genetic makeup affect the ways

in which animals respond to nutrients with regard to health”.

• Communication is an essential part of scientific life and many

would regard research that is not passed on to others as being

incomplete.

• Hence the present discussion is the bridge in between genome

based technology and aquaculture nutrition programs.

Brief history of fish nutrition

* Prior to 1950s: -Empirical feed formulation research with a variety of ingredients-Nutritional diseases quite prevalent-Little solid information on nutritional requirements

* 1950s and 60s:

-“Golden age” due to development of semi-purified diet that allowed single nutrients to be deleted and added back (Halver’s PhD work)

-Vitamin and amino acid requirements of salmon and trout were discovered

-Common nutritional diseases eliminated

Cont…*1970s :

-Essential nutrient list expanded to other species

-Refinement of nutrient requirement estimates using new approaches to assess nutritional adequacy

*1980s and 90s: Aquaculture production takes off-Need for economical and efficient grow-out feeds

-New species including those with larval stages

-Low-pollution feeds (low-phosphorus, highly digestible)

*2000 -Main story is alternative protein and lipid sources

-Sub-plot is supplements to enhance disease resistance, provide “semi-essential nutrients” and to produce healthful products (low in POPs, high in omega-3 fatty acids)

Origin of Nutrigenomics

• The concept that diet influences health is an ancient one.

• Nutrigenomics includes known interactions between food

and inherited genes, called inborn errors of metabolism,

that have long been treated by manipulating the diet.

• The Human Genome Project of the 1990s, which

sequenced the entire DNA in the human genome, jump-

started the science of nutrigenomics.

• Nutrigenomics brings along new terminology, novel

experimental techniques and a fundamentally new

approach to nutrition research, such as high-

throughput technologies that enables the global

study of gene expression in a cell or organism.

• Hence to see how molecular approach is useful in

fish nutrition the current discussion is with some

recent studies on nutritional regulation of candidate

gene expression.

Genomics and Aquaculture

• Functional genomics – the combination of genomics, proteomics, transcriptomics, and metabolomics has expanded rapidly over the last decade, but research on important aquaculture species is still relatively uncommon.

• Nutrigenomics uses a number of “omic” disciplines, including 1. Transcriptomics: The complete collection of gene

transcripts in a cell or a tissue at a given time.

2. Proteomics : The study of proteomes (the complete collection of proteins in a cell or tissue at a given

time),which attempts to determine their role inside cells and the

molecules with which they interact.

3. Metabolomics : The study of the metabolome, which is the entire metabolic

content of a cell or organism, at a given time.

4. Epigenomics : Epigenomics is the study of the complete set of epigenetic

modifications on the genetic material of a cell, known as the epigenome.

• The huge data sets generated by this research rely heavily on the field of bioinformatics, which has developed new methods to acquire, store, share, analyze, present, and manage the information.

BIOACTIVE FOOD COMPONENTS CAN MODIFY TRANSCRIPTION, TRANSLATION AND METABOLISM

Candidate Gene Approach in Fish Nutrition

1. Nutritional regulation of digestive physiology at a molecular level

suppression of live diets and replacement by inert-formulated diets in marine fish larvae

*Production of marine fish larvae and juveniles European sea bass, Gilthead seabream, Red sea bream, in commercial hatcheries still depends on the supply of live prey, such as rotifers and Artemia.

• Compound diet substitution for live prey is crucial for lowering production costs and for sustaining production of high and constant quality juveniles.

• A number of studies have attempted to determine the timing of initiation of feeding and/or gastrointestinal functionality in fish larvae.

How molecular techniques may help to answer to this question

How molecular techniques may help to answer to this question

• This adaptation may be due to a molecular regulation of their gene expression.

• Coordinated decrease between specific activity and mRNA levels of amylase enzyme is transcriptionally regulated during larval development.

• As such, amylase mRNA and activity are very high during young larval stages and decrease during the development of larvae.

2. Nutritional regulation of lipid metabolismsuppression of fish oil/fishmeal by vegetable

products without negative consequences on fish product quality

• Increased demand for fish oils in feed industries.

• Only sustainable alternative to fish oils is plant (vegetable) oils.

• Plant oils rich in C18 but devoid of the essential fatty acids such as Eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA),compromising their nutritional value.

• Understanding the molecular basis of fatty acid biosynthesis and its regulation in fish is indeed necessary to enable efficient and effective use of vegetable oils in aquaculture.

Genomics research initiative in farmed fish

• Teleosts are diverse groups of more than 23,000 species.

• Fish undergone whole genome duplication at one or other point of their evolution (Taylor et al., 2003).

• Initially, model fish species for genomics were zebrafish and medaka (Oryzias latipes), two freshwater species – models for developmental and genetic research – and the pufferfish (Fugu rubripes and Tetraodon nigroviridis) (Cossins and Crawford, 2005).

• Over the past 5 years, genomics programmes1 have been initiated for ‘model’ farmed fish species (Thorgaard et al., 2002; Liu, 2003; Rise et al., 2004)

• Carnivorous fish salmonids (rainbow trout and Atlantic salmon) and striped bass Morone saxatilis

• Omnivorous channel catfish Ictalurus punctatus

• Semi-carnivorous tilapia Oreochromis mossambicus

Case study ICase study I

• Methods 1. cDNA microarrays2. Hybridisation: scanning and quantifications of

microarrays3. Microarray data analysis4. Data mining5. Real-time RT-PCR

Duration of experiment: 9.5 weeks

Results Results

Result

Conclusion

• Total removal of ingredients of marine origin is not essential for sustainable aquaculture development, knowledge on potential implications of such extreme diets is useful.

• The use of transcriptomics data obtain from these investigation helpful for the development of novel aquafeeds.

Future DirectionsFuture Directions

• By increasing understanding of dietary manipulation effects on fish production, scientists can develop elite feeds with positive effects on production economics and animal welfare, and develop “designer fish” that target specific market demands.

• One important challenge concerning our future is to establish and maintain sustainable and profitable food production.

THANK YOU FOR ATTENTION