Testing changes in gene expression profiles in Octopus vulgaris (Mollusca Cephalopoda)

Zarrella, Ilaria (2012). Testing changes in gene expression profiles in Octopus vulgaris (Mollusca Cephalopoda). PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000eea3


The aim of this thesis is to contribute to the understanding of the molecular machinery involved in learning and memory processes in Octopus vulgaris. Fear is the leitmotif. A fear conditioning training protocol was developed to evaluate behavioural responses in animals negatively conditioned to an artificial stimulus. To test whether interaction with con specifics in a solitary animal induces a form of innate fear, experiments were carried out to test the influence of 'social' interaction on predatory performances.

Genomic information available for O.vulgaris is limited, from these data I found a-tubulin, octopressin, cephalotocin, stathmin. I also identified the partial cDNA sequences for TH, uch and dat. Creb and ubi were also considered herein.

I studied the pattern of distribution of these genes by in situ hybridization, the analysis of the co-localization of Ov-dat and Ov-THtranscripts allowed to draw a possible distribution of dopaminergic and noradrenergic neurons in the octopus CNS.

I analysed the pattern of expression of these genes in response to fear. I showed that CREB phosphorylation levels significantly increased during memory retrieval suggesting that a phenomenon analogue to reconsolidation may occur in octopus.

Experiments of qRT-PCR revealed the increased expression of Ov-uch and Ov-stm in the lobes known as centers for learning and memory confirming the involvement of these genes in the processes of synaptic plasticity, learning and LTM.

The increased expression of Ov-dat and Ov-TH in response to learned fear suggests that the consolidation of a task with aversive reinforcers is mediated by a dopaminergic pathway. On the contrary, in response to social interaction these genes are down-regulated suggesting that this process is mediated by other neurotransmitters.

Finally, this study will provide the basic tools for future experiments where the analysis of the molecular machinery may be correlated with different forms of learning and synaptic plasticity.

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