Metamorphosis or the larval‐juvenile transition:Steering the future of the foodfish industrySteering the future of the foodfish industry

I f L tImage from Larvanet

Karin PittmanKarin Pittman11, Oystein Sæle, Oystein Sæle1212, Sonnich Meier, Sonnich Meier33, Roland Koedijk, Roland Koedijk11,, Nigel FinnNigel Finn11

1)1) Univ of Bergen Univ of Bergen 2) NIFES2) NIFES 3) Inst of Marine Reseach3) Inst of Marine ReseachBergenBergenNorwayNorway

FOCUS: metamorphosis and development, growth, reproductionFOCUS: metamorphosis and development, growth, reproduction

lili dd i t t tii t t tisampling sampling andand interpretationinterpretation

Stages, metamorphosis, cell plasticityStages, metamorphosis, cell plasticity

Epigenetics, environment and 3R: model vs target fishEpigenetics, environment and 3R: model vs target fish

Multigenerational effects on foodfish productionMultigenerational effects on foodfish productiong pg p

metamorphosis is ”special” crossroad

”roundabout” with extensive cell plasticityp y

Organogenesis:

Metamorphosis or the larval-juvenile transition

brain, eyes, notochord,

gut, endocrine systems,

cranial skeletoncranial skeleton,

gills, blood cells, skin, Cell plasticity

gonads, axial skeleton

(endocrine controlled)(endocrine controlled)

Cell determination

MODEL Hypothalamus-pituitary-thyroid axis directs transformationfrom larva to juvenile

Diet(+iodine?)

pineal

TSH

TRH

T3 T4

Diet(+iodine?)Melatonin

TSHThyroid follicleT3 T4

Diet(+selenium)Thyroid

Tissue

PlasmaT3 Bound T4

T3 T4Deiodination

Photoperiod affectsPhotoperiod affectsMetamorphosisMetamorphosis

Tissue

Up or down regulation DNA

3 4

Receptors

Development Growth Reproduction

Model addresses several levels of organization

POPULATION: developmental differences begin before juvenile is established

Slide courtesy Dr. Joe Brown, Memorial Univ of Newfoundland

GROUP – development and further growth directed by first feed

Same food all groups

Koedijk et al., 2009 submitted

Longterm growth benefit of first feeding on zooplankton (cod, Gadus morhua)

GROUP – growth (and development) directed by early photoperiod

D r y w e ig h ts o f c o d la r v a e su b je c te d to th r e e d i f f e r e n t l ig h t in te n s i ty t r e a tm e n ts

0 . 1 0

ae (g

)

0 . 0 6

0 . 0 8

ht o

f 10

larv

a

0 . 0 4

Wei

gh

0 . 0 0

0 . 0 2

A g e (d a y s)0 1 0 2 0 3 0 4 0 5 0 6 0 7 0

H ig h lig h t in te n s ity th ro u g h o u tL i h t i t it d d t 2 8 d hL ig h t in te n s ity re d u c e d a t 2 8 d p hL ig h t in te n s ity re d u c e d a t 4 0 d p h

Slide courtesy Dr. Joe Brown, MUN, data Monk et al.

Southern flounder larvae, Paralichthys lethostigma

GROUP – development and growth directed by photoperiod

Moustakas et al., 2004

SPECIES + TISSUE – developmental control differentiates (pineal culture)Continuous dark

Solea senegalensisMarine, flatPhotoperiod importantExogenous rhythmExogenous rhythm

Tench (Tinca tinca)FW, round,Photoperiod not so imptEndogenous rhythm

Oliveira et al 2009

METAMORPHOSIS ‐ Sampling by stage gives fundamental steering processes(species, groups, individuals, tissues)

Stage 5

Stage 8

TSH β

Power, Einarsdottir, Pittman, Sweeney, Hildahl, Campinho, Silva, Sæle, GalayPower, Einarsdottir, Pittman, Sweeney, Hildahl, Campinho, Silva, Sæle, Galay--Burgos, Smaradottir & Bjørnsson 2008 Burgos, Smaradottir & Bjørnsson 2008 The molecular and endocrine basis of flatfish metamorphosis. Reviews in Fisheries Science 16:95The molecular and endocrine basis of flatfish metamorphosis. Reviews in Fisheries Science 16:95--111111

TSH β

S rR

NAINDIVIDUAL

development

hhK

er1:

18S

A keratin geneexpressionpatternin halibutin halibut

Thyroid hormonelevels in halibut stageshalibut stages

Campinho et al., 2007

SPECIES AND TISSUE- different tissues produce thyroid, steer development

Mozambique Tilapia – thyroid follicles in subpharyngeal

Common carp – thyroid follicles in kidney (87%), head kidney (3%)subpharyngeal,

Platyfish Xiphophorus maculatusHeterotopic in cardiovascular system

- Thyroid follicle cell populations are not physiologically equal in iodide uptake or hormone synthesis- Multiple isoforms of thyroid hormone receptors exist

Adapted from Geven et al 2007, 2009; Finn unpub data

SPECIES, TISSUE, PROTEIN – different organs express ribosomal proteins

regulation of multiple processes

Fr Matsuoka et al 2008

CLASS ACT - Fish Specific Genome Duplication 350 mya (3R)up to eight copies of the ancestral deuterostome genomeOsteichthyes (ray finned bony fishes)

2R 1R 1

SPECIES - differentiated developmental controlsafter Fish Specific Genome Duplication (FSGD, 3R)

fundamental regulatory mechanisms may be

Common modelsdiverge

mechanisms may be unexpectedly variable

Pigmentation genesPigmentation genes(Braasch et al 2008)

SPECIES, GROUPS – different pathways to reproduction, starting VERY early

zebrafish Sex differentiationFemales and MalesFemales and Males21-42 dpf

medaka

Sex differentiation

Late gastrulation 4 somitescod

Sex differentiationFemale < hatchingMale > 13 dph

5mm cod larva – gonads developing,Primordial Germ Cell migration-Meier (unpub data)

(Kluver 2007; Brion et al., 2004)

EPIGENETICS- changes in phenotype or gene expression

NOT h i DNA ( )NOT changes in DNA sequence (genome)much more than just deformities

especially obvious during cell differentiation-especially obvious during cell differentiation, pluripotent cells become a single cell typeMetamorphosis a series of critical periods?

mechanism: histone modifications and DNA methylation (chemical modification of DNA that can be inherited and subsequently removed without changing the original DNA sequence)

eg nutrition temperature photoperiodeg. nutrition, temperature, photoperiod

Power, Einarsdottir, Pittman, Sweeney, Hildahl, Campinho, Silva, Sæle, GalayPower, Einarsdottir, Pittman, Sweeney, Hildahl, Campinho, Silva, Sæle, Galay--Burgos, Smaradottir & Bjørnsson 2008 Burgos, Smaradottir & Bjørnsson 2008 The molecular and endocrine basis of flatfish metamorphosis. Reviews in Fisheries Science 16:95The molecular and endocrine basis of flatfish metamorphosis. Reviews in Fisheries Science 16:95--111111

EPIGENETICS + GROUP - growth set by photoperiod in early life critical period

Continuous light/Natural light

All groups ambient light and temp

Imsland et al., 2007

TRANSGENERATION – epigenetic inheritance and reprogramming

- diet induced metabolic programming can affect next generation p g g g(Patel & Srinivasan 2002)

- epigenetic inheritance found in all taxa examined (Jablonka & Raz 2009)g ( )-model organisms report most cases of Epigenetic Inheritance

-includes chromatin marks, RNA, self-reconstructing structures (eg. protein folding), and self-sustaining metabolic loops

SPECIES + GROUP – epigenetics and transgenerational effects

Early female 39 mm (44 days)

Estrogen exposure upto day 50 (larvae)

Adult w sperm and egg in one gonad

L l f Bi l i l O i ti

Individual Organ Cell

Level of Biological Organization

Meier et al unpub data

√ ≠ √

METAMORPHOSIS = integration of processes at critical point

3R3R

Fish have most plastic and diverse biology of vertebrate groups (3R)Fish have most plastic and diverse biology of vertebrate groups (3R)t iti i fi h l ti (th id i d d l ti it ?)t iti i fi h l ti (th id i d d l ti it ?)

Conclusions

--transitioning fish more plastic (thyroid induced plasticity?)transitioning fish more plastic (thyroid induced plasticity?)

--long duration of pluripotency in cell groupslong duration of pluripotency in cell groups

--sampling by stage is necessary during larvalsampling by stage is necessary during larval--juvenile transitionjuvenile transitionlarge repertoire of responses (immediate or delayed; some unexpected)large repertoire of responses (immediate or delayed; some unexpected)

Some fundamental steering mechanisms are species specificSome fundamental steering mechanisms are species specificSome fundamental steering mechanisms are species specificSome fundamental steering mechanisms are species specific

”model” fish are not the same as target fish species”model” fish are not the same as target fish species

Level of biological organization analysed is important to level where result is appliedLevel of biological organization analysed is important to level where result is applied

Transgenerational effects Transgenerational effects –– --no single process determines outcome of metamorphosisno single process determines outcome of metamorphosis