Light detection in animals is predominantly based on the photopigment composed of a protein moiety, the opsin, and the chromophore retinal. Animal opsins originated very early in metazoan evolution from within the G-Protein Coupled Receptor (GPCR) gene superfamily and diversified into several distinct branches prior to the cnidarian-bilaterian split. The origin of opsin diversity, opsin classification and interfamily relationships have been the matter of long-standing debate. Comparative studies of opsins from various Metazoa provide key insight into the evolutionary history of opsins and the visual perception in animals. Here, we have analyzed the genome assembly of the cephalochordate Branchiostoma lanceolatum, applying BLAST, gene prediction tools and manual curation in order to predict de novo its complete opsin repertoire. We investigated the structure of predicted opsin genes, encoded proteins, their phylogenetic placement, and expression. We identified a total of 22 opsin genes in B. lanceolatum, of which 21 are expressed and the remaining one appears to be a pseudogene. According to our phylogenetic analysis, representatives from the three major opsin groups, namely C-type, the R-type and the Group 4, can be identified in B. lanceolatum. Most of the B. lanceolatum opsins exhibit a stage-specific, but not a tissue-specific, expression pattern. The large number of opsins detected in B. lanceolatum, the observed similarities and differences in terms of sequence characteristics and expression patterns lead us to conclude that there may be a fine tuning in opsin utilization in order to facilitate visually-guided behavior of European amphioxus under various environmental settings.

• MeSH
• fotoreceptory metabolismus   MeSH
• fylogeneze MeSH
• genomika metody   MeSH
• kopinatci genetika   MeSH
• molekulární evoluce MeSH
• multigenová rodina * MeSH
• opsiny klasifikace   genetika   MeSH
• stanovení celkové genové exprese MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Transposable elements (TEs) are able to jump to new locations (transposition) in the genome, usually after replication. They constitute the so-called selfish or junk DNA and take over large proportions of some genomes. Due to their ability to move around they can change the DNA landscape of genomes and are therefore a rich source of innovation in genes and gene regulation. Surge of sequence data in the past years has significantly facilitated large scale comparative studies. Cephalochordates have been regarded as a useful proxy to ancestral chordate condition partially due to the comparatively slow evolutionary rate at morphological and genomic level. In this study, we used opsin gene family from three Branchiostoma species as a window into cephalochordate genome evolution. We compared opsin complements in terms of family size, gene structure and sequence allowing us to identify gene duplication and gene loss events. Furthermore, analysis of the opsin containing genomic loci showed that they are populated by TEs. In summary, we provide evidence of the way transposable elements may have contributed to the evolution of opsin gene family and to the shaping of cephalochordate genomes in general.

• MeSH
• duplikace genu MeSH
• genom MeSH
• kopinatci genetika   MeSH
• molekulární evoluce * MeSH
• opsiny genetika   MeSH
• regulace genové exprese MeSH
• transpozibilní elementy DNA genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Mammals usually possess a majority of medium-wavelength sensitive (M-) and a minority of short-wavelength sensitive (S-) opsins in the retina, enabling dichromatic vision. Unexpectedly, subterranean rodents from the genus Fukomys exhibit an S-opsin majority, which is exceptional among mammals, albeit with no apparent adaptive value. Because thyroid hormones (THs) are pivotal for M-opsin expression and metabolic rate regulation, we have, for the first time, manipulated TH levels in the Ansell's mole-rat (Fukomys anselli) using osmotic pumps. In Ansell's mole-rats, the TH thyroxine (T4) is naturally low, likely as an adaptation to the harsh subterranean ecological conditions by keeping resting metabolic rate (RMR) low. We measured gene expression levels in the eye, RMR, and body mass (BM) in TH-treated animals. T4 treatment increased both, S- and M-opsin expression, albeit M-opsin expression at a higher degree. However, this plasticity was only given in animals up to approximately 2.5 years. Mass-specific RMR was not affected following T4 treatment, although BM decreased. Furthermore, the T4 inactivation rate is naturally higher in F. anselli compared to laboratory rodents. This is the first experimental evidence that the S-opsin majority in Ansell's mole-rats is a side effect of low T4, which is downregulated to keep RMR low.

• MeSH
• bazální metabolismus účinky léků   MeSH
• čípky retiny - opsiny genetika   metabolismus   MeSH
• mikroftalmičtí podzemní hlodavci krev   metabolismus   MeSH
• retina metabolismus   MeSH
• thyroxin krev   nedostatek   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Animals sense light primarily by an opsin-based photopigment present in a photoreceptor cell. Cnidaria are arguably the most basal phylum containing a well-developed visual system. The evolutionary history of opsins in the animal kingdom has not yet been resolved. Here, we study the evolution of animal opsins by genome-wide analysis of the cubozoan jellyfish Tripedalia cystophora, a cnidarian possessing complex lens-containing eyes and minor photoreceptors. A large number of opsin genes with distinct tissue- and stage-specific expression were identified. Our phylogenetic analysis unequivocally classifies cubozoan opsins as a sister group to c-opsins and documents lineage-specific expansion of the opsin gene repertoire in the cubozoan genome. Functional analyses provided evidence for the use of the Gs-cAMP signaling pathway in a small set of cubozoan opsins, indicating the possibility that the majority of other cubozoan opsins signal via distinct pathways. Additionally, these tests uncovered subtle differences among individual opsins, suggesting possible fine-tuning for specific photoreceptor tasks. Based on phylogenetic, expression and biochemical analysis we propose that rapid lineage- and species-specific duplications of the intron-less opsin genes and their subsequent functional diversification promoted evolution of a large repertoire of both visual and extraocular photoreceptors in cubozoans.

• MeSH
• AMP cyklický metabolismus   MeSH
• biologická evoluce * MeSH
• Cubozoa genetika   metabolismus   MeSH
• exprese genu MeSH
• fotoreceptory metabolismus   MeSH
• fylogeneze MeSH
• genom * MeSH
• genomika metody   MeSH
• mapování chromozomů MeSH
• messenger RNA genetika   MeSH
• multigenová rodina MeSH
• opsiny genetika   metabolismus   MeSH
• proteiny vázající GTP metabolismus   MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

In deep-water animals, the visual sensory system is often challenged by the dim-light environment. Here, we focus on the molecular mechanisms involved in rapid deep-water adaptations. We examined visual system evolution in a small-scale yet phenotypically and ecologically diverse adaptive radiation, the species flock of cichlid fishes in deep crater lake Barombi Mbo in Cameroon, West Africa. We show that rapid adaptations of the visual system to the novel deep-water habitat primarily occurred at the level of gene expression changes rather than through nucleotide mutations, which is compatible with the young age of the radiation. Based on retinal bulk RNA sequencing of all eleven species, we found that the opsin gene expression pattern was substantially different for the deep-water species. The nine shallow-water species feature an opsin palette dominated by the red-sensitive (LWS) opsin, whereas the two unrelated deep-water species lack expression of LWS and the violet-sensitive (SWS2B) opsin, thereby shifting the cone sensitivity to the centre of the light spectrum. Deep-water species further predominantly express the green-sensitive RH2Aα over RH2Aβ. We identified one amino acid substitution in the RH2Aα opsin specific to the deep-water species. We finally performed a comparative gene expression analysis in retinal tissue of deep- vs. shallow-water species. We thus identified 46 differentially expressed genes, many of which are associated with functions in vision, hypoxia management or circadian clock regulation, with some of them being associated with human eye diseases.

• MeSH
• cichlidy genetika   fyziologie   MeSH
• čípky retiny - opsiny genetika   MeSH
• druhová specificita MeSH
• ekosystém MeSH
• fylogeneze MeSH
• jezera MeSH
• molekulární evoluce * MeSH
• regulace genové exprese genetika   MeSH
• retina metabolismus   fyziologie   MeSH
• sekvenční analýza RNA MeSH
• světlo MeSH
• zrak genetika   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Kamerun MeSH

Animals often change their habitat throughout ontogeny; yet, the triggers for habitat transitions and how these correlate with developmental changes - e.g. physiological, morphological and behavioural - remain largely unknown. Here, we investigated how ontogenetic changes in body coloration and of the visual system relate to habitat transitions in a coral reef fish. Adult dusky dottybacks, Pseudochromis fuscus, are aggressive mimics that change colour to imitate various fishes in their surroundings; however, little is known about the early life stages of this fish. Using a developmental time series in combination with the examination of wild-caught specimens, we revealed that dottybacks change colour twice during development: (i) nearly translucent cryptic pelagic larvae change to a grey camouflage coloration when settling on coral reefs; and (ii) juveniles change to mimic yellow- or brown-coloured fishes when reaching a size capable of consuming juvenile fish prey. Moreover, microspectrophotometric (MSP) and quantitative real-time PCR (qRT-PCR) experiments show developmental changes of the dottyback visual system, including the use of a novel adult-specific visual gene (RH2 opsin). This gene is likely to be co-expressed with other visual pigments to form broad spectral sensitivities that cover the medium-wavelength part of the visible spectrum. Surprisingly, the visual modifications precede changes in habitat and colour, possibly because dottybacks need to first acquire the appropriate visual performance before transitioning into novel life stages.

• MeSH
• barva MeSH
• biologické modely MeSH
• časové faktory MeSH
• ekosystém * MeSH
• fylogeneze MeSH
• fyziologická adaptace MeSH
• korálové útesy * MeSH
• kůže cytologie   MeSH
• kvantitativní znak dědičný MeSH
• mimikry * MeSH
• opsiny genetika   MeSH
• pigmentace fyziologie   MeSH
• predátorské chování MeSH
• regulace genové exprese MeSH
• ryby růst a vývoj   fyziologie   MeSH
• zrak fyziologie   MeSH
• zrakové dráhy fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Austrálie MeSH

The origin of vertebrate eyes is still enigmatic. The "frontal eye" of amphioxus, our most primitive chordate relative, has long been recognized as a candidate precursor to the vertebrate eyes. However, the amphioxus frontal eye is composed of simple ciliated cells, unlike vertebrate rods and cones, which display more elaborate, surface-extended cilia. So far, the only evidence that the frontal eye indeed might be sensitive to light has been the presence of a ciliated putative sensory cell in the close vicinity of dark pigment cells. We set out to characterize the cell types of the amphioxus frontal eye molecularly, to test their possible relatedness to the cell types of vertebrate eyes. We show that the cells of the frontal eye specifically coexpress a combination of transcription factors and opsins typical of the vertebrate eye photoreceptors and an inhibitory Gi-type alpha subunit of the G protein, indicating an off-responding phototransductory cascade. Furthermore, the pigmented cells match the retinal pigmented epithelium in melanin content and regulatory signature. Finally, we reveal axonal projections of the frontal eye that resemble the basic photosensory-motor circuit of the vertebrate forebrain. These results support homology of the amphioxus frontal eye and the vertebrate eyes and yield insights into their evolutionary origin.

• MeSH
• axony metabolismus   MeSH
• Chordata genetika   fyziologie   MeSH
• cytoplazma metabolismus   MeSH
• fluorescenční mikroskopie metody   MeSH
• fotoreceptory bezobratlých fyziologie   MeSH
• fotoreceptory obratlovců fyziologie   MeSH
• imunohistochemie metody   MeSH
• konfokální mikroskopie metody   MeSH
• melaniny metabolismus   MeSH
• molekulární sekvence - údaje MeSH
• opsiny metabolismus   MeSH
• pigmentace MeSH
• přenos světelných signálů MeSH
• proteiny vázající GTP metabolismus   MeSH
• retina fyziologie   MeSH
• serotonin metabolismus   MeSH
• transkripční faktory metabolismus   MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Cryptochromes are a ubiquitous group of blue-light absorbing flavoproteins that in the mammalian retina have an important role in the circadian clock. In birds, cryptochrome 1a (Cry1a), localized in the UV/violet-sensitive S1 cone photoreceptors, is proposed to be the retinal receptor molecule of the light-dependent magnetic compass. The retinal localization of mammalian Cry1, homologue to avian Cry1a, is unknown, and it is open whether mammalian Cry1 is also involved in magnetic field sensing. To constrain the possible role of retinal Cry1, we immunohistochemically analysed 90 mammalian species across 48 families in 16 orders, using an antiserum against the Cry1 C-terminus that in birds labels only the photo-activated conformation. In the Carnivora families Canidae, Mustelidae and Ursidae, and in some Primates, Cry1 was consistently labeled in the outer segment of the shortwave-sensitive S1 cones. This finding would be compatible with a magnetoreceptive function of Cry1 in these taxa. In all other taxa, Cry1 was not detected by the antiserum that likely also in mammals labels the photo-activated conformation, although Western blots showed Cry1 in mouse retinal cell nuclei. We speculate that in the mouse and the other negative-tested mammals Cry1 is involved in circadian functions as a non-light-responsive protein.

• MeSH
• antisérum chemie   MeSH
• Canidae fyziologie   MeSH
• čípky retiny - opsiny genetika   MeSH
• čípky retiny fyziologie   účinky záření   ultrastruktura   MeSH
• cirkadiánní rytmus fyziologie   účinky záření   MeSH
• exprese genu MeSH
• fylogeneze * MeSH
• Hominidae fyziologie   MeSH
• imunohistochemie MeSH
• konformace proteinů MeSH
• kryptochromy chemie   genetika   MeSH
• magnetické pole MeSH
• medvědovití fyziologie   MeSH
• Mustelidae fyziologie   MeSH
• proteinové domény MeSH
• ptáci fyziologie   MeSH
• savci klasifikace   fyziologie   MeSH
• světlo MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Animal eyes are morphologically diverse. Their assembly, however, always relies on the same basic principle, i.e., photoreceptors located in the vicinity of dark shielding pigment. Cnidaria as the likely sister group to the Bilateria are the earliest branching phylum with a well developed visual system. Here, we show that camera-type eyes of the cubozoan jellyfish, Tripedalia cystophora, use genetic building blocks typical of vertebrate eyes, namely, a ciliary phototransduction cascade and melanogenic pathway. Our findings indicative of parallelism provide an insight into eye evolution. Combined, the available data favor the possibility that vertebrate and cubozoan eyes arose by independent recruitment of orthologous genes during evolution.

• MeSH
• biologické modely MeSH
• Cercopithecus aethiops MeSH
• cilie metabolismus   ultrasonografie   MeSH
• COS buňky MeSH
• Cubozoa růst a vývoj   MeSH
• financování organizované MeSH
• fotoreceptory bezobratlých cytologie   metabolismus   ultrastruktura   MeSH
• krystaliny metabolismus   MeSH
• melaniny metabolismus   MeSH
• messenger RNA MeSH
• molekulární sekvence - údaje MeSH
• obratlovci růst a vývoj   MeSH
• oči cytologie   růst a vývoj   ultrastruktura   MeSH
• oční čočka metabolismus   MeSH
• pigmentace MeSH
• regulace genové exprese genetika   MeSH
• sekvenční homologie nukleových kyselin MeSH
• transkripční faktor spojený s mikroftalmií genetika   metabolismus   MeSH
• tyčinkové opsiny metabolismus   MeSH
• zrak genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH

• Klíčová slova
• oftalmologové - konference/Sendai,1986/ - sborníky prací, degeneratio tapetoretinalis - sborníky prací, sítnice - poruchy degenerativní - sborníky prací,

• Konspekt
• Ortopedie. Chirurgie. Oftalmologie
• NLK Obory
• oftalmologie
• patologie
• embryologie a teratologie
• fyziologie
• genetika, lékařská genetika