Body Color Variation Research Articles

Global patterns of genomic and phenotypic variation in the invasive harlequin ladybird

BackgroundThe harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae), native to Asia, has been introduced to other major continents where it has caused serious negative impacts on local biodiversity. Though notable advances to understand its invasion success have been made during the past decade, especially with then newer molecular tools, the conclusions reached remain to be confirmed with more advanced genomic analyses and especially using more samples from larger geographical regions across the native range. Furthermore, although H. axyridis is one of the best studied invasive insect species with respect to life history traits (often comparing invasive and native populations), the traits responsible for its colonization success in non-native areas warrant more research.ResultsOur analyses of genome-wide nuclear population structure indicated that an eastern Chinese population could be the source of all non-native populations and revealed several putatively adaptive candidate genomic loci involved in body color variation, visual perception, and hemolymph synthesis. Our estimates of evolutionary history indicate (1) asymmetric migration with varying population sizes across its native and non-native range, (2) a recent admixture between eastern Chinese and American populations in Europe, (3) signatures of a large progressive, historical bottleneck in the common ancestors of both populations and smaller effective sizes of the non-native population, and (4) the southwest origin and subsequent dispersal routes within its native range in China. In addition, we found that while two mitochondrial haplotypes-Hap1 and Hap2 were dominant in the native range, Hap1 was the only dominant haplotype in the non-native range. Our laboratory observations in both China and USA found statistical yet slight differences between Hap1 and Hap2 in some of life history traits.ConclusionsOur study on H. axyridis provides new insights into its invasion processes into other major continents from its native Asian range, reconstructs a geographic range evolution across its native region China, and tentatively suggests that its invasiveness may differ between mitochondrial haplotypes.

Combinatorial expression of ebony and tan generates body color variation from nymph through adult stages in the cricket, Gryllus bimaculatus.

Insect body colors and patterns change markedly during development in some species as they adapt to their surroundings. The contribution of melanin and sclerotin pigments, both of which are synthesized from dopamine, to cuticle tanning has been well studied. Nevertheless, little is known about how insects alter their body color patterns. To investigate this mechanism, the cricket Gryllus bimaculatus, whose body color patterns change during postembryonic development, was used as a model in this study. We focused on the ebony and tan genes, which encode enzymes that catalyze the synthesis and degradation, respectively, of the precursor of yellow sclerotin N-β-alanyl dopamine (NBAD). Expression of the G. bimaculatus (Gb) ebony and tan transcripts tended to be elevated just after hatching and the molting period. We found that dynamic alterations in the combined expression levels of Gb'ebony and Gb'tan correlated with the body color transition from the nymphal stages to the adult. The body color of Gb'ebony knockout mutants generated by CRISPR/Cas9 systemically darkened. Meanwhile, Gb'tan knockout mutants displayed a yellow color in certain areas and stages. The phenotypes of the Gb'ebony and Gb'tan mutants probably result from an over-production of melanin and yellow sclerotin NBAD, respectively. Overall, stage-specific body color patterns in the postembryonic stages of the cricket are governed by the combinatorial expression of Gb'ebony and Gb'tan. Our findings provide insights into the mechanism by which insects evolve adaptive body coloration at each developmental stage.

Male Guppies Recognize Familiar Conspecific Males by Their Face

Individual recognition is a necessary cognitive ability for the maintenance of stable social relationships. Recent studies have shown that like primates, some fish species can distinguish familiar fish from unfamiliar strangers via face-recognition. However, the taxa of the studied fish species are restricted (within Perciformes) and the visual signal used for the recognition of fish remains unclear. Here, we investigated the visual signal for individual-recognition in males of a sexually dichromatic guppy (Poecilia reticulata, Cyprinodontiformes). Using guppy males, we examined the hypothesis that fish distinguish between familiar individuals and unknown strangers by their faces rather than by body coloration. We randomly presented focal fish with four types of composite photo-models: familiar (familiar-face and familiar-body = F/F), stranger (stranger-face and stranger-body = S/S), familiar face combined with stranger body (F/S) and stranger face combined with familiar body (S/F). Focal males infrequently attacked familiar-face models but frequently attacked stranger-face models, regardless of body types. These behavioral reactions indicate that guppy males discriminate between familiar and stranger males by their face, not body coloration with wide variation. Importantly, male faces contain clear individual-variation in white/metallic colored patches on the operculum visible for humans. Considering the photo-model, our results suggest that these patches might be an important visual stimulus for face-recognition in guppy males, like some cichlids. Comparative examination among males of different guppy variants, including wild type phenotype, suggests that the face color-patch is stable regardless of variation in body color, with a different genetic mechanism potentially underlying face and body colors.

The “True Colours” of Golden Loaches (Teleostei: Cobitidae)

Loaches of the genus Sabanejewia are model organisms for many ichthyologic studies focusing on morphological and colour variation. The bright lateral spots—a part of the mimicry of this fish—cause a taxonomic puzzle. Common practice is that morphometric and molecular studies lack habitat assessments of species originating from different environments. In this study, we analysed body shape and colour variation within two species of Sabanejewia in order to reveal whether they are more affected by phylogeny or environmental conditions. The environmental parameters were obtained using satellite mapping tools, body shape using geometric morphometry, and the molecular identification of specimens using an analysis of mitochondrial DNA (sequence of the cytochrome b gene). Generalized linear mixed models were used for the analysis of lateral spot numbers, and principal components analysis to describe the changes in landmark position defined by the permutation tests. Results show a significant impact of the locality elevation and specimen’s sex on the change of the body shape. We identified significant differences in the number of lateral spots, which are considered mimicry variation across an elevation gradient. Morphological differences of Sabanejewia spp. vary with ecological factors along the river continuum.

Body colour adjustment of the freshwater shrimp Macrobrachium jelskii (Miers 1877) in different background colours

The body colour variation in response to different background colours is associated with camouflage, increasing efficiency against predation. In our study, we investigated the body colour variation of the freshwater shrimp Macrobrachium jelskii in response to different background colours. For this, we collected specimens of M. jelskii in the Thomás Osterne Reservoir, Municipality of Crato, State of Ceará, Brazil. For the experiment, we used six aquariums divided into three treatment groups: white background; black background; red background; with two replicates for each group. Before the experiment, we photographed 30 specimens of M. jelskii in dorsal view. Then, we distributed five shrimps in each aquarium, totalling 10 shrimps per treatment. After 30 days, we obtained new images of the shrimps, under the same settings used before the experiment. We used ImageJ software to obtain the RGB values (Red, Green, Blue) of the dorsal region of the first abdominal somite of the shrimps. Before the experiment, the body pigmentation of M. jelskii was homogeneous, with overlap between the groups. After the experiment, the RGB of M. jelskii varied according to each background colour, differing between the white and black, between the white and red, and not differing between the black and red. Our results show that M. jelskii adjusted its pigmentation to different background colours, evidencing a mechanism that may favour the camouflage of the species in different habitats and provide more chances of survival against visual predators.

Evolutionary history and diversity in the ball roller beetle Canthon cyanellus

To understand the evolutionary history of species, it is necessary to know the mechanisms for reproductive isolation, divergence-time between populations, and the relative action of the evolutionary forces (e.g., mutation, genetic drift, gene flow) within and between populations of the same, or closely related species. Although Canthon is one of the more diverse genera of neotropical beetles, insufficient research has been done to comprehend the divergent patterns that explain its speciation process. The absence of diagnostic morphological characters and the wide geographic variation of qualitative traits in Scarabaeinae obscures species delimitation, genealogical limits between populations, and its taxonomy. Canthon cyanellus is one of the best-known species in ecological and evolutionary aspects. It is a widely distributed species in the tropical forests of America. Also, the current deforestation has facilitated its incursion into open areas. Individuals from different populations have similar morphological characters but show wide variation in body color throughout their distribution, which makes it difficult to delimit the subspecies that comprise it. Recently, studies have been carried out to elucidate the pre-and postzygotic isolation mechanisms between populations and the historical biogeographical processes favoring cladogenesis events during the Pleistocene. Morphological variation of the male genitalia does not correspond to the phylogeographic structure. However, the morphological differences in one of the pieces of the endophallic sclerites have allowed a preliminary delimitation of some genetically differentiated clades. Finally, we consider that the joint analysis of traditional morphological taxonomy and phylogeography is important to understand the speciation process in the C. cyanellus complex.

Evidence of Seasonal Variation in Body Color in Adults of the Parasitoid Cirrospilus pictus (Hymenoptera: Eulophidae) in Sicily, Italy.

As part of the studies on the morphological color variation of insects, a case study on the seasonal body color variation of Cirrospilus pictus (Nees) (Hymenoptera: Eulophidae: Eulophinae) parasitoid of leafminers is reported. Observations were made from January 2000 to December 2003 in north-western Sicily (Italy), in relation to sex, body regions of adults and seasonal periods. Wasps parasitizing Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) were collected from organic citrus orchards (Citrus limon L., var. "Femminello zagara bianca" and "Femminello comune"). Adults were grouped in classes: yellow males, black males, yellow females, yellow-black females and black females. The results highlighted a phenotypic pigmentation variation in the head, thorax, gaster and legs of individuals influenced by the season of sampling. Adults were yellow-green in summer months, whereas individuals with dark pigmentation were found in autumn and winter months. A correlation between color patterns and seasonal temperatures was found for both females and males. This work provides a contribution to the description of the intraspecific variability of this species, improving its identification.

Differential regulation of the Tor gene homolog drives the red/green pigmentation phenotype in the aphid Myzuspersicae

In some aphid species, intraspecific variation in body colour is caused by differential carotenoid content: whilst green aphids contain only yellow carotenoids (β-, γ-, and β,γ-carotenes), red aphids additionally possess red carotenoids (torulene and 3,4-didehydrolycopene). Unusually, within animals who typically obtain carotenoids from their diet, ancestral horizontal gene transfer of carotenoid biosynthetic genes from fungi (followed by gene duplication), have imbued aphids with the intrinsic gene repertoire necessary to biosynthesise carotenoids. In the pea aphid, Acyrthosiphon pisum a lycopene (phytoene) desaturase gene (Tor) underpins the red/green phenotype, with this locus present in heterozygous form in red individuals but absent in green aphids, resulting in them being unable to convert lycopene into the red compounds 3,4-didehydrolycopene and torulene. The green peach aphid, Myzus persicae, separated from the pea aphid for ≈45MY also exists as distinct colour variable morphs, with both red and green individuals present. Here, we examined genomic data for both red and green morphs of M. persicae and identified an enlarged (compared to A. pisum) repertoire of 16 carotenoid biosynthetic genes (11 carotenoid desaturases and five carotenoid cyclase/synthase genes). From these, we identify the homolog of A. pisum Tor (here called carotene desaturase 2 or CDE-2) and show through 3D modelling that this homolog can accommodate the torulene precursor lycopene and, through RNA knockdown feeding experiments, demonstrate that disabling CDE-2 expression in red M. persicae clones results in green-coloured offspring. Unlike in A. pisum, we show that functional CDE-2 is present in the genomes of both red and green aphids. However, expression differences between the two colour morphs (350–700 fold CDE-2 overexpression in red clones), potentially driven by variants identified in upstream putative regulatory elements, underpin this phenotype. Thus, whilst aphids have a common origin of their carotenoid biosynthetic pathway, two aphid species separated for over 40MY have evolved very different drivers of intraspecific colour variation.

Genetic architecture of wintering black spot trait in red tilapia as revealed by a genome-wide association study

Black spots could be induced in red tilapia at wintering stage. This body color variation causes significant economic loss to the aquaculture industry of red tilapia. Understanding the genetic architecture of wintering black spot variation is of great significance for the selection of pure red tilapia lines. In this study, 37 SNPs and five QTLs controlling for the wintering black spot trait at genome-wide significance were successfully identified on Chr2:4.6–4.9 Mb, Chr2:20.0 Mb, Chr3:30.1–34.0 Mb, Chr8:4.0–6.1 Mb, Chr12:5.9–7.5 Mb in red tilapia (N = 287) by using a genome-wide association study. These QTLs were further verified by genotyping four novel microsatellite markers in the mapping population. Three candidate genes (sema-4c, uvssa and htr2cl1) in these QTL regions showed significantly differentiated expression in response to low temperature (LT) or UVB or UVB + LT challenges in brain or skin tissues of red tilapia as revealed by qRT-PCR analysis. Interestingly, the expression levels of the three candidate genes were more significantly changed under the UVB+ LT stressors than the LT or UVB stress solely. These suggested that the wintering black spots in red tilapia may be regulated by comprehensive environmental factors.

Observation of body colour formation and pigment cells in grey‐black and golden Paramisgumus dabryanus

In nature, most Paramisgurnus dabryanus are grey-black (grey-black loach), although there is a mutant (albino) in the breeding population with a ‘golden colour’ (golden loach). There are no reports of early body colour formation in albino fishes. In this study, the differences in body colour characteristics between normal body colour P. dabryanus and albino P. dabryanus were compared by comparing body colour formation, skin and fin pigment cells of two body colours of P. dabryanus. It was found that the order of appearance of pigment cells in grey-black loach and golden loach was melanophores, xanthophores, erythrophores, and finally, iridophores; the composition of the pigment cells in the fins and the skin tissue were essentially the same. However, there were no melanophores in the skin of the golden loach. The melanophores of grey-black loach skin were distributed with a large number of melanosomes of high electron density; the xanthophore and erythrophores were spherical and contained pteridine vesicles. Melanophores and xanthophores are distributed in both the epidermis and dermis of the grey-black loach, and the xanthophores of the golden loach are distributed between the scales and the epidermis, and between the dermis and the muscle layer. In this study, we elucidated the body colour composition and pigment cell characteristics of the two body colours of P. dabryanus. Our study provided a scientific basis for the research for fish body colour variation.

Pleistocene paleodrainages explain the phylogeographic structure of Malaysian populations of Asian arowana better than their chromatic variation

Little is known about the genetic structure and phylogeography of Asian arowana (Scleropages spp.). Natural variation in body color has led to the informal distinction of chromatic varieties, but previous studies that attempted to genetically characterize these varieties did not comprehensively cover their geographical distribution. In Malaysia, about 10 drainage-restricted populations of Asian arowana are known that are currently classified into 2 species and 3 color varieties. In this study, we used 3 molecular markers to test 2 hypotheses explaining the relationships among 9 of these populations. The first hypothesis postulates that each color variety forms a monophyletic group, whereas the second hypothesis assumes that Pleistocene paleodrainages shaped the distribution of these populations. We found that the overall genetic variability is low within Asian arowana and that the green variety is non-monophyletic, with other varieties nested within. Instead, the populations of Malaysia belong to 3 genetic lineages that are allopatrically distributed. The ages and distribution of 2 of these lineages are consistent with past connections through paleodrainages, whereas the last lineage is restricted to Central Sarawak. Overall, our results reject the first hypothesis, demonstrating that the geographic origin of specimens is a better phylogenetic indicator than their body color. This study highlights the importance of Malaysia in the conservation of Asian arowana, because it is the only country in which populations of all 3 main genetic lineages occur.

Relationship between body colour and microhabitat breadth in an orb-web spider

Abstract Habitat use often differs among intraspecific individuals, and the degree to which individual animals use specific habitats, i.e. microhabitat breadth, can also vary. Variation in body colour sometimes emerges as dark vs. bright coloration, which can be related to habitat selectivity. The aim of this study was to examine whether darker animals prefer shady sites to avoid overheating from direct sunlight exposure, whereas brighter animals would use both shady and open sites. Orb-web spiders, Cyclosa argenteoalba, have a silver dorsal abdomen with black markings; the proportion of these black markings varies between 20 and 100% among individuals. In summer, there was less variation in the duration of direct sunlight hitting the webs of darker spiders compared with that of brighter spiders. This indicated a narrower microhabitat range for darker spiders, which preferred shady sites. This pattern was not observed in spring and autumn, when thermal conditions were less severe. These results are consistent with the hypothesis that when the temperature is high, darker animals are microhabitat specialists, whereas brighter animals are generalists. A previous study found that darker spiders capture more prey than brighter spiders, and the amount of black markings is considered to be a trade-off between foraging success and microhabitat availability.

Cloning, sequence analysis, and expression of tyrp1a and tyrp2 genes related to body colour in different developmental stages and tissues of rainbow trout Oncorhynchus mykiss

Tyrosinase-related protein 1 (tyrp1) and tyrosinase-related protein 2 (tyrp2) genes are important downstream regulatory factors for body colour formation in animals. The present study aimed to explore the relationship between tyrp1a and tyrp2 expression and body colour variation between wild-type (WT) and yellow mutant (YM) rainbow trout. The full-length cDNA sequences of trout tyrp1a and tyrp2 were obtained using rapid amplification of cDNA ends, and the bioinformatic analysis was performed. Quantitative real-time PCR (qRT-PCR) was used to investigate the different expression levels of tyrp1a and tyrp2 in different developmental stages and tissues. The full-length cDNAs of tyrp1a and tyrp2 were 2409 bp and 2219 bp encoding predicted proteins of 522 and 529 amino acid residues, respectively. Both proteins possess six conserved domains, including a signal peptide, an EGF-motif, a Pfam tyrosinase motif, a transmembrane structure, and two copper binding sites (CuA and CuB). Amino acid sequence comparisons showed higher conservation of Tyrp1a and Tyrp2 proteins amongst fishes than amongst other vertebrates, which was further confirmed by phylogenetic analysis. qRT-PCR analysis revealed that tyrp1a and tyrp2 expression levels in WT rainbow trout, and tyrpla in YM rainbow trout, were detected from the fertilised stage to 12 months post hatching (12 M), while tyrp1a did not expressed until the blastula in YM rainbow trout. In addition, the expression levels of both of the genes post hatching were significantly higher than those in the embryonic stages, which showed extremely low expression levels. Additionally, there were extremely significant differences (P < 0.01) in expression at the same stages between WT and YM rainbow trout, e.g., at the blastula, gastrula, 7 days post hatching (7 dph), 10 dph, 2 M, 3 M, 6 M, and 12 M stages for tyrp1a; and at the 4-cell, 16-cell, multicell, blastula, somites, heartbeating, 1 dph, 5 dph, 7 dph, 3 M, 6 M, and 12 M stages for tyrp2. Besides, variable expression levels of tyrp1a and tyrp2 were detected in all tissues; significantly high expression was detected in the dorsal skin and eye compared with that in the other tissues in WT and YM rainbow trout (P < 0.05). These results suggested that the expression level changes of tyrp1a and tyrp2 might be closely related to the variation of rainbow trout body colour, which will enrich our knowledge of the molecular mechanism of skin colour variation in rainbow trout and provide data for research into fish skin colour inheritance and improvement.

De novo transcriptome assembly for two color types of the marine sponge Mycale (Carmia) cecilia.

Despite the ecological importance and the potential pharmacological application of the sponge Mycale (Carmia) cecilia, it is uncertain whether the body-color variation, even in individuals coexisting in the same area, is due to intraspecific phenotypic plasticity or corresponds to taxonomic divergence. This uncertainty is relatively common in several Porifera groups, which lack the resolution of morphological diagnostic characters and slow-evolving mitochondrial genomes as occurs in early splitting lineages. We sequenced the RNA of six individuals with two different body-color (green-morphotype and red-morphotype) collected at the same time side by side. High-throughput sequencing of cDNA libraries produced ~ 129 million reads with a length of 150bp. Each morphotype was assembled separately owing to the low overlapping in the global assembly. Metatranscriptome de novo assembly of the trimmed and normalized reads produced 461 thousand transcripts for the green-morphotype and 342 thousand for the red-morphotype (respectively). Over 30% of the transcripts contained Open Reading Frames (ORFs) with functional significance. BUSCO analysis of the ORFs of putative poriferan origin (31.3% green or 30.4% red) indicated that our assemblies are 60% complete. This is the first attempt to evaluate the morphological diversity in the species M. (C.) cecilia and the phylum Porifera at the transcriptomic level. Due to the minimum overlap of the assembly and that, the red-morphotype diverged significantly from the green-morphotype (original color of M. (C.) cecilia). Therefore, we suggest that the red-morphotype should undergo a complete taxonomic investigation and its taxonomic status be reviewed. We expect that the transcriptome assembly metrics can be useful for comparing other transcriptome assemblies of non-model organisms.

Expression and function analysis of crustacyanin gene family involved in resistance to heavy metal stress and body color formation in Exopalaemon carinicauda.

Crustacyanin has the function of binding astaxanthin which is the best antioxidant, and plays an important role in the body color variation of crustaceans. To investigate the causes of body color variation of the ridgetail white prawn, Exopalaemon carinicauda, the present study obtained four subtypes of crustacyanin gene: C1, C2, A1, and A2. Based on fluorescence quantitative polymerase chain reaction, lipocalin-C1 is mainly expressed in the eyestalk, lipocalin-C2 is in the ventral nerve cord, and lipocalin-A1 and lipocalin-A2 are in subcutaneous adipose tissues. Under the inhibiting effect of Cd2+ stress, the expression of four subtypes first increases and then decreases within 24 h, and reaches the maximum at 6 or 12 h. RNA interference experiments showed a decrease in the expression of lipocalin genes in subcutaneous adipose tissue for each subtype, with the body color changing from transparent to red, and the dark red spots on the epidermis changing to bright red. Moreover, the blue protein in the subcutaneous adipose tissue largely disappeared, based on the light micrographs. In view of these findings, the crustacyanin gene appears to fulfill some function in the resistance to heavy metal stress and body color formation of E. carinicauda.

Widening the host range of the ectosymbiotic scale-worm &lt;i&gt;Asterophilia culcitae&lt;/i&gt; (Annelida: Polynoidae) to three echinoderm classes, with data on its body color variation

Widening the host range of the ectosymbiotic scale-worm &lt;i&gt;Asterophilia culcitae&lt;/i&gt; (Annelida: Polynoidae) to three echinoderm classes, with data on its body color variation

Body-color plasticity of the English grain aphid in response to light in both laboratory and field conditions

The occurrence of different color patterns in a population of a species can depend on genetic variations or plasticity to environmental conditions. Body color variation is under selection because it is involved in several ecological processes such as camouflage for prey-predator interactions or resistance to environmental variations. Among insects, aphids are known to produce different body-color morphs depending on their biotic and abiotic environments and their bacterial endosymbionts. The English-grain aphid (EGA) Sitobion avenae produces both red and green morphs in cereal fields. Using both field studies on the Canadian prairies (Saskatchewan) and laboratory experiments, we aimed to study the mechanisms that trigger plasticity in body coloration to better understand the ecological role of body coloration and color-change evolved by animals, including aphids. We first analyzed green and red morph EGA distribution on wheat ears in different fields and showed that red aphids were mostly located at the top of the ear and green aphids at the bottom. Then, using DNA sequencing, we showed that red and green morphs did not strongly differ in their bacterial endosymbiont composition and abundances. Finally, using a climate-chamber setup in the laboratory, we highlighted that EGA body-coloration is under light-intensity control and that it is possible to turn aphids from red back to green within a few days, and from green back to red within a couple of weeks (low-to-high and high-to-low light intensities, respectively). Light-intensity-controlled color-change likely results in adaptive plasticity in response to shifts in environmental conditions that can occur over the lifespan of an aphid, and is fully reversible, even at the adult stage.

Lessons from Timor: Shells are poor taxonomic indicators in Asperitas land snails (Stylommatophora, Dyakiidae)

AbstractThe limacoid land snail Asperitas Gude, 1911 encompasses several vividly coloured, yet poorly known species that are distributed throughout the Lesser Sunda Islands, Sulawesi, and the Moluccas. We examined the variation in shell morphology, including the use of geometric morphometrics, and reproductive anatomy of snails from Timor and several adjacent islands. These studies revealed that none of the taxa described from Timor and considered to be endemic to this island could be reliably distinguished from any of the others. In addition to the systematic ambiguity of morphological characteristics, we uncovered rather low amounts of genetic differentiation in the mitochondrial marker cytochrome c oxidase subunit I that was not consistent with the current taxonomy. Based on these observations, we conclude that there is just a single Asperitas species on Timor that exhibits notable variability in shell characters and body colour. This variability is ascribed to the combined effects of polymorphic colour patterns with locally varying selection in different habitats and along altitudinal gradients. Individuals from the adjacent islands of Flores, Sumbawa, Solor and Romang, which are deemed to represent distinct species‐level taxa, exhibit similar amounts of variation in shell and body colour. They exhibit a consistent reproductive anatomy and overall negligible amounts of mitochondrial differentiation from the populations on Timor. Patterns in shell variation do not lend support to previously held ideas that different Sunda Islands harbour distinct radiations of polytypic Asperitas species. By contrast, we suggest that the taxonomic diversity of Asperitas has been overestimated for the over‐reliance on shell features and that many presently accepted taxa are likely mere synonyms of fewer and more widespread species.

The plasticity of vision and body development of turbotScophthalmus maximuslarvae Under different light spectra

This study was aimed to find out the effect of five light spectra (white, LDW; blue, LDB; green, LDG; red, LDR and yellow, LDY) on the visual development and growth performance of turbot (Scophthalmus maximus) larvae. The number (per 100 μm) of cone cells, outer nuclear cells, ganglion cells, the ratio of outer nuclear to cone and ganglion cells, lens diameter and the minimum separable angle were determined. Variations in growth performance in total length, body mass and body colour were also examined. The results showed that the LDB group underwent metamorphosis faster than did the other groups and attained the greatest total length, body mass and light sensitivity. The LDB group also completed the body colour variation prior to the other groups. The LDG group exhibited a high mortality rate since 25 dph (days post-hatching). We arrived at the conclusions that the spectra could affect the vision and body development of turbot larvae specifically and the blue light had the enhancing efficiency during this process, followed by the white and yellow light. The red light imposed an inhibiting effect on these variations. Our study highlighted the significance of light condition and provided the reference for the farming.

The complete mitochondrial genome of Liparis tessellatus and its phylogenetic analysis

Liparis tessellatus is a cubed snailfish that inhabits the northwestern region of the Pacific Ocean. The family Liparidae is difficult to distinguish morphologically due to the typical body color and shape variation, which are used interchangeably due to the differences in local dialects. Therefore, we determined the complete mitochondrial genome sequence of L. tesellatus. The mitochondrial genome length of L. tesellatus was determined as 17,221 bp, which consisted of 22 tRNA genes, two rRNA genes, 13 protein-coding genes (PCGs), and a control region (D-loop). The base composition was as follows: 28.6% of A, 29.5% of T, 26.5% of C, and 15.4% of G. The phylogenetic analysis revealed that L. tesellatus clustered together with different species of the genus Liparis. Thus, the complete mitochondrial genome sequence provided herein would further help in understanding the evolution of Liparis species.