EFFECT OF PHOTOPERIOD MANIPULATION ON RAINBOW TROUT EGG QUALITY A GENOMIC STUDY

Transcription

1 EFFECT OF PHOTOPERIOD MANIPULATION ON RAINBOW TROUT EGG QUALITY A GENOMIC STUDY Emilie BONNET, Alexis FOSTIER, Julien BOBE INRA SCRIBE IFR14, Campus de Beaulieu, 3542 Rennes Cedex Emilie.Bonnet@rennes.inra.fr

2 Preamble Fish egg quality can be defined as the egg ability to be fertilized and to subsequently lead to the development of a normal embryo Egg quality is subjected to high variability, in the wild or in hatcheries

3 Context Low egg quality has previously been correlated with oogenesis conditions such as : Embryonic survival (%) 18 C 14 C cortisol days Diet Stress High water temperature Egg postovulatory ageing Izquierdo et al., 21 Schreck et al., 21 Davies and Bromage, 22 Aegerter et al., 23

4 Context Photoperiod is the major factor affecting the timing of ovulation in many species in Sole Solea solea (Devauchelle et al., 1987) Sea Bass Dicentrachus labrax L. (Carrillo et al., 1989) yellow perch Perca flavescens (Ciereszko et al., 1997) rainbow trout Oncorhynchus mykiss (Davies and Bromage, 22)

5 Context In rainbow trout, photoperiod is also known to modulate fecundity and egg size However Little is known about its direct effect on egg quality in terms of survival and embryonic development

6 Context Oogenesis history stress diet photoperiodic manipulations water Temperature synchronisation of ovulation Post-ovulatory ageing etc Egg composition F e r t i l i z a t i o n Early Embryo T r a n s i t i o n time trophic stores Proteins Messenger RNAs etc Stored maternal mrna Zygote mrnas HIGH variability in egg quality

7 Aim of the study 1- Does a long-short photoperiod regime affect egg quality? 2-Does it modulate expression of some maternally inherited mrnas?

8 Work 1. To test photoperiod effects, we use a Long-short photoperiod regime widely used in hatcheries 2. To analyze egg maternal mrna, we used rainbow trout cdna microarrays

9 Methods 3-4 weeks before expected ovulations INRA facilities Photoperiod (PM) group Temperature ( C) Daylength (hours) J F M A M J J A S O N D Temperature ( C) Daylength (hours) Control group J F M A M J J A S O N D water temperature 12 C 8L:16D PM/ natural C Ovulation checked three times a week

10 Methods Eggs stripped 5 days after ovulation Semen pool Egg quality Trial Transcriptome analysis Fertilization (1 C) Unfertilised and frozen -8 C Eyeing (1 C) Survival Yolk-sac resorption (1 C) Malformations and survival QUALITY 2 Survival index Malformation percentage MICROARRAYS nylon membrane 2*9152 trout cdna pool-tissue library 14 PM /4 Control Statistical Differential analysis

11 Quality 1 *** *** Survivals % 6 4 Malformations % 6 4 * 2 2 Eyeing ANF YSR means PM control Only 49% survival in PM group at eying High variability between females Confirmed at YSR Alive Normal Fry less 4% malformations >15 % Photoperiod manipulation induces a decrease of egg quality with high individual variability & increase of malformations

12 Quality Malformation % * Types of malformation were different between two groups No Cyclops type in PM High proportion of DYSR C SCT DYSR P others PM control Egg post-ovulatory ageing more Cyclops (Aegerter,24) C : Cyclops DYSR : Default in yolksac resorption SCT : Spinal cord torsion P : Prognate others Photoperiod manipulation more DYSR Is there a Malformation signature dependent on oogenesis history??

13 Transcriptome GenBank accession # CA BX88617 CA CA BX828 CA38139 Hit description (Species) Amino-acid N- acetyltransferase subunit (Danio rerio) Glucagon II precursor (Rainbow trout) Unnamed protein product (Tetraodon nigroviridis) Tryptophan hydroxylase 1 (Danio rerio) Predicted protein (Danio rerio) Peptide:N-glycanase (Homo sapiens) AA sequence identity % 92% 9% 78% 75% 67% 51% Symbol MAK1 GLP2 UK1 TPH1 UK2 NGLY1 2,5 2 1,5 1, MAK1 UK1 UK2,5,4,3,2,1 2,5 2 1,5 1,5 2,5 2 1,5 1,5 GLP2 TPH1 NGLY1 Hybridizations : 8422 detected clones Differential analysis : 6 maternal mrna significantly less abundant in PM group eggs Photoperiod manipulation is associated with differences in egg mrna levels

14 MAK1 MAK1 is an auxiliary subunit of N-terminal acetyl transferase C ( NAT C), in yeast. In humans, ovarian NAT activity was correlated with the synthesis of melatonin and serotonin (Itoh et al., 1999). In cockroachs (Periplaneta americana), NAT could be a clock-controlled gene in the brain functioning as an output regulator of the circadian clock (Bembenek et al., 25) Photoperiod manipulation could directly affect MAK1 expression in regards to its correlation with melatonin or its clock-controlled role

15 Glucagon II Glucagon/glucagon-like peptides (GLP) are involved in the regulation of hepatic glycogenolysis and gluconeogenesis (reviewed by Plisetskaya and Mommsen, 1996; Moon, 1998). In mammals, glucagon plays an important role in the correction of hypoglycemia. Interestingly, glucose insufficiencies are involved in abnormal embryonic development in mice (Smoak, 22). Glucagon has also been shown to be essential for the paracrine induction of differentiation of other pancreatic components in the early embryonic pancreas in mice (Prasadan et al., 22). These observations are consistent with the decrease of survival observed at YSR in PM group for which glugagon was less abundant.

16 Conclusion A long-short photoperiod regime commonly used to advance spawning date in rainbow trout can induce significant egg quality defects Lower survival at eying and yolk-sac resorption higher malformation percentage higher individual variation between females. In addition, new clues indicate a potential link between specific malformation signatures and oogenesis history Finally, this study suggests that the egg transcriptome before fertilization can be influenced by environmental perturbations

17 Prospects In fish, these conclusions are original and illustrate the importance to Study the relation between quality and mrna in PM group Study effects of other factors on egg quality synchronisation of ovulation To Use rainbow trout cdna microarrays as a powerful tool to characterize fish egg transcriptome Do a functional analysis To detail the 6 maternal mrna identified in this study

18 Emilie BONNET, Alexis FOSTIER, Julien BOBE INRA SCRIBE IFR14, Campus de Beaulieu, 3542 Rennes Cedex phd grant to E. Bonnet from French Government Funding INRA-AGENAE-IFOP-OFIMER-CIPA AGENAE-GADIE core facility for providing trout cdna microarrays