Browsing by Author "Duncan, Neil J."
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- Linking stress coping styles with brain mRNA abundance of selected transcripts for Senegalese sole (Solea senegalensis) juvenilesPublication . Fatsini, Elvira; Rey, Sonia; Ibarra-Zatarain, Zohar; Boltaña, Sebastián; Mackenzie, Simon; Duncan, Neil J.In fish, proactive and reactive individual stress copying styles (SCS) have been used to resolve variation in molecular expression data. Stress coping styles have been previously described in several stages of Solea senegalensis by validating for the species the use of standard behavioural screening tests. The present study aimed to link behavioural SCS tests with brain transcript abundance in early Senegalese sole juveniles in order to observe the natural variation in a molecular pathway in this species. A total of 50 juveniles were subjected to three individual behavioural (Restraining, New environment and Confinement) and one group (Risk-taking) screening tests. The fish were classified in SCS categories by applying a hierarchical cluster to the variable "Total activity" (the total activity time that the fish was moving in each individual test). Three categories were defined, proactive, intermediate and reactive sole. Six transcripts were chosen and tested, one related to basic metabolism (gapdh-2), three to feeding behaviour (per1, igf-Ia, pparß) and two to the stress response (crh-BP and hsp90aa) in 30 juveniles (10 individuals per SCS category) using rt-qPCR to observe differences in the abundance of those transcripts among SCS. Four transcripts were differentially expressed (DETs) among them. The transcript gapdh-2 showed up-regulation for proactive and intermediate SCS sole while reactive individuals showed down-regulation. Target mRNAs per1, igf-Ia and pparß, showed different levels of up-regulation for proactive and reactive fish while intermediates were highly down-regulated. Surprisingly no differences in stress related transcripts were observed. Correlations were found between variation in coping styles and variation in the abundance of mRNAs involved in important biological functions in Senegalese sole. These results are the first evidence of the relationship between the behavioural individual variation and the fluctuation in brain transcripts abundance in Senegalese sole.
- Olfactory sensitivity of the marine flatfish Solea senegalensis to conspecific body fluidsPublication . Fatsini, Elvira; Carazo, Ignacio; Chauvigne, Francois; Manchado, Manuel; Cerda, Joan; Hubbard, Peter; Duncan, Neil J.Chemical communication is better understood in freshwater fish than marine fish. The Senegalese sole (Solea senegalensis) is a marine flatfish wherein one of the problems in aquaculture is the poor reproductive performance of hatchery-bred males. Is chemical communication involved in the reproduction of this species? Urine, intestinal fluid and mucus samples were taken from adult fish (wild-caught and hatchery-bred) over the spawning season (March-May), and assessed for olfactory potency using the electro-olfactogram (EOG). The effect of stimulation of the olfactory system with adult female urine on circulating luteinizing hormone (LH) levels was also tested in males. Intestinal fluid and urine were potent olfactory stimuli for both juvenile and adult conspecifics, evoking large-amplitude, concentration-dependent EOG responses, with thresholds of detection at approximately 1:10(6). However, the amplitude of the response to urine depended on the sex and state of maturity of both the donor and the receiver. Most olfactory activity could be extracted by C18 solid-phase cartridges. Urine from mature females evoked a slight, but significant, increase in circulating LH levels in mature males 30 min after exposure. Furthermore, the olfactory potency of urine differed between wild-caught and hatchery-bred fish; however, contrary to expectations, urine from wild-caught females was less potent than that from hatchery-bred females. Taken together, these results strongly suggest that faeces-and urine-released odorants are involved in reproduction in the Senegalese sole, and establish a basis for further investigation into pheromonal communication in marine teleosts.
- The presence of wild Senegalese sole breeders improves courtship and reproductive success in cultured conspecificsPublication . Fatsini, Elvira; Gonzalez, Wendy; Ibarra-Zatarain, Zohar; Napuchi, Juvenal; Duncan, Neil J.The life cycle of Senegalese sole (Solea senegalensis) is not closed in captivity due to a reproductive dysfunction related to the lack of participation of cultured male breeders in the courtship. To discern a possible solution to this social reproductive dysfunction, the main objective of this study was to determine the effect of the presence of spawning wild Senegalese sole breeders on the courtship and reproduction of cultured breeders. Three experimental groups were formed: Control group (n = 10) formed with only cultured sole; groups M1 and M2 constituted of mixed-origin sole (10 cultured and 8 or 9 wild breeders). All cultured breeders were from the same stock, which had never successfully reproduced, whilst the wild broodstock had spawned viable eggs in captivity. All groups were held in the same captive conditions and spawning, and behaviour were recorded for each group over four spawning seasons. All spawns were collected, and the parameters registered were floating and non-floating eggs, fertilization and hatching rates. In addition, parental analysis was made of larvae from viable spawns. Behaviour was studied with video recordings to compare locomotor activity and courtship behaviours including the "Follow" behaviours where sole swim after each other in a procession. Fertilized spawns were obtained from the mixed-origin groups (M1 and M2) including spawns involving a cultured male. The cultured males also participated actively in the "Follow" behaviours with the courting wild sole and this participation of cultured males increased significantly over the four years of the experiment. Male percentage participation in the "Follow" behaviours was positively correlated (R = 0.81) to participation in spawning to indicate the importance of increasing cultured male participation in the "Follow" behaviours. A total of seven spawns were obtained from a cultured male that fertilized eggs from one cultured female and two wild females. The same cultured female also spawned with a wild male. No viable spawns were obtained from the Control group and locomotor activity and courtship behaviour counts were significantly lower than in the experimental mixedorigin groups. This is the first report of cultured male breeders participating in reproductive behaviour and spawning, which could be associated with social learning processes, mate selection and dominance where cultured males copied the behaviour and spawning of wild Senegalese sole breeders.