The opsin repertoire of the Antarctic krill Euphausia superba

Biscontin, Alberto; Frigato, Elena; Sales, Gabriele; Mazzotta, Gabriella; Teschke, Mathias; Pittà, Cristiano De; Jarman, Simon; Meyer, Bettina; Costa, Rodolfo; Bertolucci, Cristiano

doi:10.1016/j.margen.2016.04.010

Cited by 30 publications

(30 citation statements)

References 42 publications

(57 reference statements)

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“…The phylogenetic relationships among opsin families in tarantulas is shown in Figure S4. It is largely consistent with results from other invertebrate studies 12 , but differs in that peropsins (RRH) emerge as the most derived in our case, where they emerge as the most basal in Biscontin, et al . 12 .…”

Section: Resultssupporting

confidence: 93%

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The Evolution Of Colouration And Opsins In Tarantulas

Foley

Saranathan

Piel

2020

Preprint

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14Tarantulas paradoxically exhibit a diverse palette of vivid colouration despite their crepuscular 15 to nocturnal habits. The evolutionary origin and maintenance of these colours remains a 16 mystery. In this study, we reconstructed the ancestral states of both blue and green colouration 17 in tarantula setae, and tested how these colours correlate with the presence of stridulation, 18 urtication, and arboreality. Green colouration has likely evolved at least eight times, and blue 19 colouration is likely an ancestral condition that appears to be lost more frequently than gained. 20 While our results indicate that neither colour correlates with the presence of stridulation or 21 urtication, the evolution of green colouration appears to depend upon the presence of 22 arboreality, suggesting that it likely originated for, and functions in, crypsis through substrate 23 matching among leaves. We also constructed a network of opsin homologs across tarantula 24 transcriptomes. Despite their crepuscular tendencies, tarantulas express a full suite of opsin 25 genesa finding that contradicts current consensus that tarantulas have poor colour vision on 26 the basis of low opsin diversity. Overall, our results support the intriguing hypotheses that blue 27 colouration may have ultimately evolved via sexual selection and perhaps proximately be used 28 in mate choice or predation avoidance due to possible sex differences in mate-searching. 29 30 52for each genus in this study, and conducted a series of correlative tests to determine whether 53 any of these traits might inform the function of blue or green colouration in tarantulas. We 54 hypothesize that blue colour should be associated with stridulating / urticating setae, or both, 55 if it either originally evolved or has been exapted (sensu 8 ) for an aposematic function. 56However, we posit that green colouration could aid in crypsis and should show an association 57 with arboreality. 58It is generally thought that tarantulas possess little or no colour vision, with only a weak 59 colour spectrum discrimination 2,9 , with Hsiung, et al. 2 noting that sexual selection as a driving 60 force behind the evolution of tarantula colouration is unlikely. Morehouse et al. 10 argue that 61 tarantulas are colour-blind on the basis of finding a low opsin diversity in Aphonopelma 10 . We 62 investigate whether this claim holds true for other tarantulas by scoring the presence and 63 relative expression of opsins from transcriptomic data in 25 tarantula genera. Opsins are 64 specialized, transmembrane proteins belonging to the superfamily of G-protein coupled 65 receptors that convert light photons to electrochemical signals through a signalling cascade 11 . 66 While the expression of multiple opsin species does not necessarily imply greater colour 67 discrimination, the absence of opsin orthologs could provide support to the hypothesis that 68 tarantulas, broadly speaking, cannot perceive colours. 69 70 RESULTS 71 72 Phylogenetic Signal of Colour Traits 73Our phylogeny con...

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Section: Resultssupporting

confidence: 93%

“…It is largely consistent with results from other invertebrate studies 12 , but differs in that peropsins (RRH) emerge as the most derived in our case, where they emerge as the most basal in Biscontin, et al . 12 . Full sequence alignments (MSA) of tarantula opsins are available in Figure S5.…”

Section: Resultssupporting

confidence: 93%

The Evolution Of Colouration And Opsins In Tarantulas

Foley

Saranathan

Piel

2020

Preprint

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“…Aquatic animals usually display higher variability than terrestrial animals in their opsin gene repertoire (Biscontin et al, 2016;Liegertova et al, 2015;Ramirez et al, 2016) and amphioxus is no exception to this rule. Approximately twenty functional opsin genes have been identified in each of the amphioxus genomes completed so far: 21 opsin genes in B. floridae, 21 opsin genes plus one opsin pseudogene in B. lanceolatum and 20 opsin genes in B. belcheri Pantzartzi et al, 2017).…”

Section: Opsins As Key Molecular Determinants Of Light Detection In Amentioning

confidence: 99%

Amphioxus photoreceptors - insights into the evolution of vertebrate opsins, vision and circadian rhythmicity

Pergner

Kozmík²

2017

Int. J. Dev. Biol.

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Studies on amphioxus, representing the most basal group of chordates, can give insights into the evolution of vertebrate traits. The present review of amphioxus research is focused on the physiology of light-guided behavior as well as on the fine structure, molecular biology, and electrophysiology of the nervous system, with special attention being given to the photoreceptive organs. The amphioxus visual system is especially interesting because four types of receptors are involved in light detection -dorsal ocelli and Joseph cells (both rhabdomeric photoreceptors) and the frontal eye and lamellar body (both ciliary photoreceptors). Here, we consider how the available information on photoreceptive organs and light-guided behavior in amphioxus helps generate hypotheses about the history of these features during chordate and subsequently vertebrate evolution.

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“…Primer pairs for eight reference gene candidates were kindly provided by Alberto Biscontin and Cristiano de Pittà from the University of Padova (Biscontin et al 2016). The Fig.…”

Section: Nucleic Acid Extraction and Qpcr Setupmentioning

confidence: 99%

Sex identification from distinctive gene expression patterns in Antarctic krill (Euphausia superba)

et al. 2019

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Antarctic krill (Euphausia superba) is a highly abundant keystone species of the Southern Ocean ecosystem, directly connecting primary producers to high-trophic level predators. Sex ratios of krill vary remarkably between swarms and this phenomenon is poorly understood, as identification of krill sex relies on external morphological differences that appear late during development. Sex determination mechanisms in krill are unknown, but could include genetic, environmental or parasitic mechanisms. Similarly, virtually nothing is known about molecular sex differentiation. The krill genome has to date not been sequenced, and due to its enormous size and large amount of repetitive elements, it is currently not feasible to develop sex-specific DNA markers. To produce a reliable molecular marker for sex in krill and to investigate molecular sex differentiation we therefore focused on identifying sex-specific transcriptomic differences. Through transcriptomic analysis, we found large gene expression differences between testes and ovaries and identified three genes exclusively expressed in female whole krill from early juvenile stages onwards. The sex-specific expression of these three genes persisted through sexual regression, although our regressed samples originated from a krill aquarium and may differ from wild-regressed krill. Two slightly male-biased genes did not display sufficient expression differences to clearly differentiate sexes. Based on the expression of the three female-specific genes we developed a molecular test that for the first time allows the unambiguous sex determination of krill samples lacking external sex-specific features from juvenile stages onwards, including the sexually regressed krill we examined.

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The opsin repertoire of the Antarctic krill Euphausia superba

Cited by 30 publications

References 42 publications

The Evolution Of Colouration And Opsins In Tarantulas

The Evolution Of Colouration And Opsins In Tarantulas

Amphioxus photoreceptors - insights into the evolution of vertebrate opsins, vision and circadian rhythmicity

Sex identification from distinctive gene expression patterns in Antarctic krill (Euphausia superba)

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