Light-induced shifts in opsin gene expression in the four-eyed fish

The development of the vertebrate eye is a complex process orchestrated by several conserved transcriptional and signaling regulators. Aside from partial or complete loss, examples of exceptional modifications to this intricate organ are scarce. The unique eye of the four-eyed fish is composed of duplicated corneas and pupils, as well as specialized retina regions associated with simultaneous aerial and aquatic vision. In a previous transcriptomic study of the developing eye we identified expression of twenty non-visual and eleven visual opsin genes. Here, we surveyed the expression territories of three non-visual melanopsins genes (××), one teleost multiple tissue opsin () and two visual opsins () in dorsal and ventral retinas. Our data showed that asymmetry of non-visual opsin expression is only established after birth. During embryonic development, while inside pregnant females, the expression of ××, and spans the whole retina. In juvenile fish (post birth), the expression of ××, and genes becomes restricted to the ventral retina, which receives aerial light. Raising juvenile fish in clear water instead of the murky waters found in its natural habitat is sufficient to change gene expression territories of ××, , and , demonstrating that different lighting conditions can shift opsin expression and potentially contribute to changes in spectral sensitivity in the four eyed fish

Tetrapod limb and sarcopterygian fin regeneration share a core genetic programme.

Salamanders are the only living tetrapods capable of fully regenerating limbs. The discovery of salamander lineage-specific genes (LSGs) expressed during limb regeneration suggests that this capacity is a salamander novelty. Conversely, recent paleontological evidence supports a deeper evolutionary origin, before the occurrence of salamanders in the fossil record. Here we show that lungfishes, the sister group of tetrapods, regenerate their fins through morphological steps equivalent to those seen in salamanders. Lungfish de novo transcriptome assembly and differential gene expression analysis reveal notable parallels between lungfish and salamander appendage regeneration, including strong downregulation of muscle proteins and upregulation of oncogenes, developmental genes and lungfish LSGs. MARCKS-like protein (MLP), recently discovered as a regeneration-initiating molecule in salamander, is likewise upregulated during early stages of lungfish fin regeneration. Taken together, our results lend strong support for the hypothesis that tetrapods inherited a bona fide limb regeneration programme concomitant with the fin-to-limb transition

Video_2_Light-induced shifts in opsin gene expression in the four-eyed fish Anableps anableps.MOV

The development of the vertebrate eye is a complex process orchestrated by several conserved transcriptional and signaling regulators. Aside from partial or complete loss, examples of exceptional modifications to this intricate organ are scarce. The unique eye of the four-eyed fish Anableps anableps is composed of duplicated corneas and pupils, as well as specialized retina regions associated with simultaneous aerial and aquatic vision. In a previous transcriptomic study of the A. anableps developing eye we identified expression of twenty non-visual and eleven visual opsin genes. Here, we surveyed the expression territories of three non-visual melanopsins genes (opn4×1, opn4×2, opn4m3), one teleost multiple tissue opsin (tmt1b) and two visual opsins (lws and rh2-1) in dorsal and ventral retinas. Our data showed that asymmetry of non-visual opsin expression is only established after birth. During embryonic development, while inside pregnant females, the expression of opn4×1, opn4×2, and tmt1b spans the whole retina. In juvenile fish (post birth), the expression of opn4×1, opn4×2, opn4m3, and tmt1b genes becomes restricted to the ventral retina, which receives aerial light. Raising juvenile fish in clear water instead of the murky waters found in its natural habitat is sufficient to change gene expression territories of opn4×1, opn4×2, opn4m3, tmt1b, and rh2-1, demonstrating that different lighting conditions can shift opsin expression and potentially contribute to changes in spectral sensitivity in the four eyed fish.</p

Image_2_Light-induced shifts in opsin gene expression in the four-eyed fish Anableps anableps.TIF

The development of the vertebrate eye is a complex process orchestrated by several conserved transcriptional and signaling regulators. Aside from partial or complete loss, examples of exceptional modifications to this intricate organ are scarce. The unique eye of the four-eyed fish Anableps anableps is composed of duplicated corneas and pupils, as well as specialized retina regions associated with simultaneous aerial and aquatic vision. In a previous transcriptomic study of the A. anableps developing eye we identified expression of twenty non-visual and eleven visual opsin genes. Here, we surveyed the expression territories of three non-visual melanopsins genes (opn4×1, opn4×2, opn4m3), one teleost multiple tissue opsin (tmt1b) and two visual opsins (lws and rh2-1) in dorsal and ventral retinas. Our data showed that asymmetry of non-visual opsin expression is only established after birth. During embryonic development, while inside pregnant females, the expression of opn4×1, opn4×2, and tmt1b spans the whole retina. In juvenile fish (post birth), the expression of opn4×1, opn4×2, opn4m3, and tmt1b genes becomes restricted to the ventral retina, which receives aerial light. Raising juvenile fish in clear water instead of the murky waters found in its natural habitat is sufficient to change gene expression territories of opn4×1, opn4×2, opn4m3, tmt1b, and rh2-1, demonstrating that different lighting conditions can shift opsin expression and potentially contribute to changes in spectral sensitivity in the four eyed fish.</p

Image_1_Light-induced shifts in opsin gene expression in the four-eyed fish Anableps anableps.TIF

The development of the vertebrate eye is a complex process orchestrated by several conserved transcriptional and signaling regulators. Aside from partial or complete loss, examples of exceptional modifications to this intricate organ are scarce. The unique eye of the four-eyed fish Anableps anableps is composed of duplicated corneas and pupils, as well as specialized retina regions associated with simultaneous aerial and aquatic vision. In a previous transcriptomic study of the A. anableps developing eye we identified expression of twenty non-visual and eleven visual opsin genes. Here, we surveyed the expression territories of three non-visual melanopsins genes (opn4×1, opn4×2, opn4m3), one teleost multiple tissue opsin (tmt1b) and two visual opsins (lws and rh2-1) in dorsal and ventral retinas. Our data showed that asymmetry of non-visual opsin expression is only established after birth. During embryonic development, while inside pregnant females, the expression of opn4×1, opn4×2, and tmt1b spans the whole retina. In juvenile fish (post birth), the expression of opn4×1, opn4×2, opn4m3, and tmt1b genes becomes restricted to the ventral retina, which receives aerial light. Raising juvenile fish in clear water instead of the murky waters found in its natural habitat is sufficient to change gene expression territories of opn4×1, opn4×2, opn4m3, tmt1b, and rh2-1, demonstrating that different lighting conditions can shift opsin expression and potentially contribute to changes in spectral sensitivity in the four eyed fish.</p

Video_1_Light-induced shifts in opsin gene expression in the four-eyed fish Anableps anableps.MOV

The development of the vertebrate eye is a complex process orchestrated by several conserved transcriptional and signaling regulators. Aside from partial or complete loss, examples of exceptional modifications to this intricate organ are scarce. The unique eye of the four-eyed fish Anableps anableps is composed of duplicated corneas and pupils, as well as specialized retina regions associated with simultaneous aerial and aquatic vision. In a previous transcriptomic study of the A. anableps developing eye we identified expression of twenty non-visual and eleven visual opsin genes. Here, we surveyed the expression territories of three non-visual melanopsins genes (opn4×1, opn4×2, opn4m3), one teleost multiple tissue opsin (tmt1b) and two visual opsins (lws and rh2-1) in dorsal and ventral retinas. Our data showed that asymmetry of non-visual opsin expression is only established after birth. During embryonic development, while inside pregnant females, the expression of opn4×1, opn4×2, and tmt1b spans the whole retina. In juvenile fish (post birth), the expression of opn4×1, opn4×2, opn4m3, and tmt1b genes becomes restricted to the ventral retina, which receives aerial light. Raising juvenile fish in clear water instead of the murky waters found in its natural habitat is sufficient to change gene expression territories of opn4×1, opn4×2, opn4m3, tmt1b, and rh2-1, demonstrating that different lighting conditions can shift opsin expression and potentially contribute to changes in spectral sensitivity in the four eyed fish.</p

A putative RA-like region in the brain of the scale-backed antbird, Willisornis poecilinotus (Furnariides, Suboscines, Passeriformes, Thamnophilidae)

The memorization and production of song in songbirds share important parallels with the process of speech acquisition in humans. In songbirds, these processes are dependent on a group of specialized telencephalic nuclei known as the song system: HVC (used as a proper name), RA (robust nucleus of arcopallium), LMAN (lateral magnocellular nucleus of the nidopallium) and striatal Area X. A recent study suggested that the arcopallium of the Sayornis phoebe, a non vocal learner suboscine species, contains a nucleus with some properties similar to those of songbird RA, suggesting that the song system may have been present in the last common ancestor of these groups. Here we report morphological and gene expression evidence that a region with some properties similar to RA is present in another suboscine, the Amazonian endemic Willisornis poecilinotus. Specifically, a discrete domain with a distinct Nissl staining pattern and that expresses the RA marker RGS4 was found in the arcopallium where the oscine RA is localized. Our findings, combined with the previous report on the S. phoebe, suggest that an arcopallial region with some RA-like properties was present in the ancestor of both Suboscines infraorders Tyranni and Furnarii, and is possibly an ancestral feature of Passeriformes

Figure S1. Expression pattern of Phospho anti-Histone H3 in the larval retina; Figure S2. Expression pattern of sense-control probes in the larval retina. from Eye development in the four-eyed fish <i>Anableps anableps</i>: cranial and retinal adaptations to simultaneous aerial and aquatic vision

A. anableps eye at Stage 3 (a,b), Stage 4 (c,d) and Stage 5 (e,f). Hematoxylin and eosin stained cryosections (a,c,e). Phospho anti-Histone H3 (S10) (green) and DAPI (blue) immunofluorescence staining (b,d,f) Panels on third column are high magnification images of the ventral and dorsal ciliary marginal zone (CMZ) of the retina. DR, dorsal retina; VR, ventral retina; L, lens; Ir, iris; DC, dorsal cornea; VC, ventral cornea; Do, dorsal; Ve, ventral; Di, distal; Pr, proximal. Cryosections 20 µm, scale bars 500 µm.; In situ hybridizations using sense probes of visual opsins in eye sections of larvae of A. anableps: rh1 (a,b), rh2-1 (c,d), rh2-2 (e,f), sws2b (g,h), and lws (i,j). Scale bars are 50 µm

Unraveling the plant diversity of the Amazonian canga through DNA barcoding.

Abstract The canga of the Serra dos Carajás, in Eastern Amazon, is home to a unique open plant community, harboring several endemic and rare species. Although a complete flora survey has been recently published, scarce to no genetic information is available for most plant species of the ironstone outcrops of the Serra dos Carajás. In this scenario, DNA barcoding appears as a fast and effective approach to assess the genetic diversity of the Serra dos Carajás flora, considering the growing need for robust biodiversity conservation planning in such an area with industrial mining activities. Thus, after testing eight different DNA barcode markers (matK, rbcL, rpoB, rpoC1, atpF‐atpH, psbK‐psbI, trnH‐psbA, and ITS2), we chose rbcL and ITS2 as the most suitable markers for a broad application in the regional flora. Here we describe DNA barcodes for 1,130 specimens of 538 species, 323 genera, and 115 families of vascular plants from a highly diverse flora in the Amazon basin, with a total of 344 species being barcoded for the first time. In addition, we assessed the potential of using DNA metabarcoding of bulk samples for surveying plant diversity in the canga. Upon achieving the first comprehensive DNA barcoding effort directed to a complete flora in the Brazilian Amazon, we discuss the relevance of our results to guide future conservation measures in the Serra dos Carajás