Cephalopod DNA/Molecular/Genetic Studies/Health

Metal bioaccumulation and detoxification processes in cephalopods: A review
Virginie Penicaud, Thomas Lacoue-Labarthe, Paco Bustamante 2017 (subscription Science Direct Environmental Research)

Abstract
In recent decades, cephalopods have been shown to have very high capacities to accumulate most trace elements, regardless of whether they are essential (e.g., Cu and Zn) or non-essential (e.g., Ag and Cd). Among the different pathways of exposure to trace elements, the trophic pathway appears to be the major route of assimilation for numerous metals, including Cd, Co, Hg and Zn. Once assimilated, trace elements are distributed in the organism, accumulating in storage organs. The digestive gland is the main organ in which many trace elements accumulate, whichever of the exposure pathway. For example, this organ can present Cd concentrations reaching hundreds to thousands of ppm for some species, even though the digestive gland represents only a small proportion of the total mass of the animal. Such a specific organotropism towards the digestive gland of both essential and non-essential elements, regardless of the exposure pathway, poses the question of the detoxification processes evolved by cephalopods in order to sustain these high concentrations. This paper reviews the current knowledge on the bioaccumulation of trace elements in cephalopods, the differences in pharmaco-dynamics between organs and tissues, and the detoxification processes they use to counteract trace element toxicity. A peculiar focus has been done on the bioaccumulation within the digestive gland by investigating the subcellular locations of trace elements and their protein ligands.
 
Biosynthesis of Polyunsaturated Fatty Acids in Octopus vulgaris: Molecular Cloning and Functional Characterisation of a Stearoyl-CoA Desaturase and an Elongation of Very Long-Chain Fatty Acid 4 Protein
Óscar Monroig, Rosa de Llanos, Inmaculada Varó, Francisco Hontoria, Douglas R. Tocher, Sergi Puig,Juan C. Navarro 2017 (Full study Marine Drugs)

1. Introduction
Cephalopods have been regarded as promising candidates for the diversification of marine aquaculture due to their great commercial interest [1]. Despite significant progress made over the last decade, culture of cephalopod species with pelagic paralarval stages like the common octopus Octopus vulgaris is still challenging due to the massive mortalities occurring upon the settlement phase [2]. The specific factors causing such mortalities of paralarvae remain unclear, although it has become increasingly obvious that nutritional issues associated with inadequate supply of essential nutrients such as lipids are crucial to ensure normal growth and development of O. vulgaris paralarvae and ultimately improve their viability [3].
 
Nerve degeneration and regeneration in the cephalopod mollusc Octopus vulgaris: the case of the pallial nerve
Pamela Imperadore, Sameer B. Shah, Helen P. Makarenkova, Graziano Fiorito 2017 (full article Scientific Reports)
Abstract
Regeneration is a process that restores structure and function of tissues damaged by injury or disease. In mammals complete regeneration is often unsuccessful, while most of the low phyla animals can re-grow many parts of their body after amputation. Cephalopod molluscs, and in particular Octopus vulgaris, are well known for their capacity to regenerate their arms and other body parts, including central and peripheral nervous system. To better understand the mechanism of recovery following nerve injury in this species we investigated the process of axon regrowth and nerve regeneration after complete transection of the Octopus pallial nerves. This injury induces scar formation and activates the proliferation of hemocytes which invade the lesion site. Hemocytes appear involved in debris removal and seem to produce factors that foster axon re-growth. Connective tissue is involved in driving regenerating fibers in a single direction, outlining for them a well-defined pathway. Injured axons are able to quickly re-grow thus to restoring structure and function.
 
Nerve regeneration in the cephalopod mollusc Octopus vulgaris: label-free multiphoton microscopy as a tool for investigation
Pamela Imperadore, Ortrud Uckermann, Roberta Galli, Gerald Steiner, Matthias Kirsch, Graziano Fiorito 2018 (Full paper Journal of the Royal Society Interface)

Abstract
Octopus and cephalopods are able to regenerate injured tissues. Recent advancements in the study of regeneration in cephalopods appear promising encompassing different approaches helping to decipher cellular and molecular machinery involved in the process. However, lack of specific markers to investigate degenerative/regenerative phenomena and inflammatory events occurring after damage is limiting these studies. Label-free multiphoton microscopy is applied for the first time to the transected pallial nerve of Octopus vulgaris. Various optical contrast methods including coherent anti-Stokes Raman scattering (CARS), endogenous two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) have been used. We detected cells and structures often not revealed with classical staining methods. CARS highlighted the involvement of haemocytes in building up scar tissue; CARS and TPEF facilitated the identification of degenerating fibres; SHG allowed visualization of fibrillary collagen, revealing the formation of a connective tissue bridge between the nerve stumps, likely involved in axon guidance. Using label-free multiphoton microscopy, we studied the regenerative events in octopus without using any other labelling techniques. These imaging methods provided extremely helpful morpho-chemical information to describe regeneration events. The techniques applied here are species-specific independent and should facilitate the comparison among various animal species.
 
Octopus vulgaris: An Alternative in Evolution
Anna Di Cosmo,, Valeria Maselli, Gianluca Polese 2018 (Subscription Marine Organisms as Model Systems in Biology and Medicine)

Abstract
Octopus vulgaris underwent a radical modification to cope with the benthic lifestyle. It diverged from other cephalopods in terms of body plan, anatomy, behavior, and intelligence. It independently evolved the largest and most complex nervous system and sophisticated behaviors among invertebrates in a separate evolutionary lineage. It is equipped with unusual traits that confer it an incredible evolutionary success: arms capable of a wide range of movements with no skeletal support; developed eyes with a complex visual behavior; vestibular system; primitive “hearing” system; chemoreceptors located in epidermis, suckers, and mouth; and a discrete olfactory organ. As if these were not enough, the occurrence of recently discovered adult neurogenesis and the high level of RNA editing give it a master key to face environmental challenges. Here we provide an overview of some of the winning evolutionary inventions that octopus puts in place such as the capacity to see color, smell by touch, edit own genes, and rejuvenate own brain.
 
The genome of an elusive giant
January 16, 2020

Today, GigaScience published a report on the genome of a truly unique species: the giant squid Architeuthis dux. The elusive animal is the main character in ancient stories about sea monsters and it is known as “the kraken” in many legends. For a long time its mere existence was questionable, until, in 1857, the Danish naturalist Japetus Steenstrup made the link between those legends and the enormous cephalopod. Now an international team led by researchers at the University of Copenhagen has dragged the mysterious monster into the genomic age.
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