Search Results (37)

The large yellow croaker (Larimichthys crocea) is an economically significant aquaculture species in Asia, with skin coloration being a key quality attribute affecting consumer choice and commercial value. This study integrated morphological, biochemical, and proteomic approaches to investigate chromatophore characteristics, pigment composition, and diurnal body color variation in the large yellow croaker. Colorimetric analysis showed the highest yellowness, redness, and lightness values in ventral skin, followed by caudal skin, with dorsal skin showing the least yellowness. Three major chromatophores were identified: melanophores, xanthophores, and iridophores. Xanthophores were abundant in ventral and caudal skin, showing larger size and deeper pigmentation ventrally, while melanophores dominated dorsally and iridophores were mainly on scales. Skin and fins were key sites for carotenoid deposition, with lutein as the predominant carotenoid. Esters of lutein and zeaxanthin were the main contributors to yellow coloration in fish. A strong positive correlation was found between skin yellowness and total carotenoid content (R = 0.91, p < 0.05). The aggregation and dispersion of xanthosomes within xanthophores appeared to be the key driver behind the light-influenced diurnal body color variation. Proteomic analysis revealed motor proteins (such as KIF21, DYNC1L1, and MYO9) and pathways related to intracellular granule movement were probably related to the pigment transport in chromatophores of large yellow croaker. In addition, tubulin dynamics also appeared to participate in pigment translocation. This study is helpful to understand the pigmentary basis of this important farmed sea fish and provides a foundation for improving the golden color traits and further molecular research on diurnal color changes in large yellow croaker. Full article

To evaluate the aquaculture potential of Amphioctopus kagoshimensis, we investigated the reproductive biology, embryonic development, and early paralarval morphology of Amphioctopus kagoshimensis under controlled laboratory conditions. Each adult specimen collected from the coastal waters of Fujian Province spawned approximately 4000–5000 eggs (mean ± SD: 4375 ± 478 eggs), with an overall hatching rate of 75% ± 10% (n = 2). Embryonic development lasted approximately 30 days at 22.0–24.5 °C and followed a classical 20-stage pattern. Hatchlings measured an average mantle length of 1.4 ± 0.1 mm and exhibited a merobenthic strategy, characterized by planktonic paralarvae with progressive morphological differentiation. The chromatophores appeared progressively on the head, mantle, arms, and funnel, with numbers increasing from 5 to 23 per arm by 30 days post-hatching. Paralarvae demonstrated active swimming, feeding behavior, and arm sucker development during rearing. By day 30, mantle length reached 2.5 mm, with significant growth in arm length and behavioral complexity. Its relatively small adult size (mantle length 8 cm), a moderate egg size (2.6 mm), fecundity and successful artificial incubation and 30-day paralarvae seedling suggested it may be a suitable model species for developmental studies and potential candidate for merobenthic octopod aquaculture in East Asia. Full article

The green octopus, Octopus hubbsorum, is a merobenthic species that inhabits warm-temperate waters in the eastern Pacific. However, its similarity to some morphological characteristics of and its slight genetic divergence from Octopus mimus has led to the proposal that both species are conspecific. The objective of this study was the morphological and molecular identification of eggs and paralarvae of the green octopus, O. hubbsorum, to provide information contributing to clarifying its taxonomy and relationship with O. mimus. The results obtained show that although O. hubbsorum has similarities with O. mimus in terms of egg size, chromatophore pattern, number of suckers, and presence of Kölliker’s organs, the O. hubbsorum paralarvae observed in this study are smaller (1.6 mm) and have a thin layer of loose skin, not described for O. mimus. Likewise, the morphology of the beak, radula, and suckers of O. hubbsorum is described for the first time and there are no studies of these structures for O. mimus. The phylogenetic analysis (mitochondrial cytochrome C oxidase subunit I and III genes) showed that both species form a monophyletic clade but belong to separate subclades. In conclusion, although the slight genetic divergence between these two species suggests conspecificity, their disjoint geographic distribution (O. hubbsorum is found in warm-temperate waters and O. mimus in cold-temperate waters) suggests the hypothesis of being two separate species with a close phylogenetic relationship. However, further research (morphological and population analyses) is required to solve taxonomic uncertainty. Full article

Photosynthetic eukaryotes have shaped the Earth’s biosphere by producing oxygen and organic compounds using light energy in specialized organelles called plastids. Plastids evolved from free-living cyanobacteria ingested by heterotrophic unicellular eukaryotes. Two such independent engulfment processes, called cyanobacterial endosymbioses, have been reported. The first gave rise to primary plastids and three Archaeplastida lineages: glaucophytes, red algae, and green algae with land plants, whereas the second resulted in chromatophores in the rhizarian amoeba Paulinella. Importantly, Archaeplastidans donated their plastids to many protist groups, further spreading photosynthesis across the tree of life. To reveal complex plastid evolution, we performed comprehensive phylogenetic and molecular clock analyses using new fossil calibrations and the largest number yet of plastid-encoded proteins from 108 taxa, representing diverse photosynthetic organisms. Our results indicate that primary plastids evolved prior to 2.1–1.8 Ga, i.e., before glaucophytes diverged from other Archaeplastidans, and Paulinella chromatophores were likely before 292–266 Ma. Red and green algae were engulfed by cryptophyte and chlorarachniophyte ancestors between 1.7–1.4 Ga and 1.1–1.0 Ga, respectively; the former subsequently triggered plastid transfers to other eukaryotes. We also examined the impact of molecular clocks and calibration sets on age estimates, showing that clocks are the main source of variation. Full article

Bioenergetic membranes of mitochondria, thylakoids, and chromatophores are primary sites of ATP production in living cells. These membranes contain an electron transport chain (ETC) in which electrons are shuttled between a series of redox proteins during the generation of ATP via oxidative phosphorylation. The phospholipid composition of these membranes, which often include negative lipids, plays a role in determining the electrostatics of their surface owing to the spatial distribution of their charged head groups. Cardiolipin (CDL) is a phospholipid commonly associated with bioenergetic membranes and is also a significant contributor to the negative surface charge. Interactions between cytochromes and phospholipid head groups in the membrane can in principle affect the rate of its travel between ETC components, hence influencing the rate of ATP turnover. Here, we use molecular dynamic (MD) simulations that feature an accelerated membrane model, termed highly mobile membrane mimetic (HMMM), to study protein–lipid interactions during the diffusion of cytochrome c₂ between redox partners in a bioenergetic membrane. We observe a “skipping” mode of diffusion for cytochromes along with a bias for binding to anionic lipids, particularly with a strong preference for CDL. During diffusion, cytochrome c₂ maintains a relatively fixed tilt with respect to the membrane normal with wider fluctuations in its angle with respect to the plane of the membrane. The obtained results describing the behavior of cytochrome c₂ on a representative bioenergetic membrane have direct ramifications in shuttling motions of other similar electron-carrying elements in other bioenergetic membranes, which are composed of a significant amount of anionic lipids. The mode of surface-restricted diffusion reported here would modulate rapid electron transfer between the ETC complexes anchored in bioenergetic membranes by reducing the search space between them. Full article

Body color is a key economic trait for Neocaridina denticulata sinensis, an important ornamental shrimp. Scarb1 may be an important mediator of astaxanthin uptake, changing the shrimp’s body color. To discover the relationship between scarb1 and the pigmentation of cherry shrimp, the expression profiles, RNAi, and SNP genotyping of scarb1 were studied. There were significant differences in four color populations and five development stages (p < 0.05). The highest expression level of scarb1 appeared in the red population and the pre-nauplius stage. Exposure to scarb1 dsRNA increased the number and development of chromatophores at the metanauplius stage, but almost no phenotypic changes were observed at the pre-zoea stage. There was a synonymous SNP (G1593A) with a significantly different genotype frequency between the red and yellow populations (p < 0.05). The above results suggested that scarb1 is involved in pigmentation by affecting the development of chromatophores. Full article

Cherry shrimp (Neocaridina denticulata sinensis) is one of the main ornamental shrimp because of its bright body color. β, β-carotene 9′,10′-dioxygenase (BCO2) is closely related to the body color produced by carotenoids. In order to study the role of NdBCO-like4 (homologous gene of BCO2) in the pigmentation of cherry shrimp, the expression profiles, RNA interference, and SNP genotyping were applied in this study. The NdBCO-like4 expression varied significantly among four color strains and five development stages (p < 0.05). The results showed that the NdBCO-like4 expression was the highest in the red strain and the lowest in the wild strain. During the embryonic development, the expression in the metanauplius stage was significantly lower than other stages (p < 0.05), and the expression of NdBCO-like4 was the highest in the membrane-zoea stage. In the metanauplius stage, the RNAi knockdown of NdBCO-like4 mediated the red pigment brightness value, and the pigment cell index in the treatment group was significantly lower than the control group (p < 0.05). After the first round of screening, a total of 8424 high-quality SNPs were obtained. There was one candidate SNP located on the NdBCO-like4 target gene, named G.1719G>A. The synonymous SNP exhibited significantly different genotype frequencies between the yellow and wild strains compared to other strains (p < 0.05), suggesting an association with these phenotypes. These results suggest that NdBCO-like4 has a close relation with carotenoid accumulation in cherry shrimp, providing valuable insights into the molecular mechanisms underlying pigmentation in this species. Full article

The largescale blackfish, Girella punctata Gray, 1835, is important in the fishing industry and recreational fishing, and it is also cultured in East Asia. Cymothoidae (Crustacea: Isopoda) is a group of parasites that infest fish in marine, brackish, and freshwater environments. In this study, we report, for the first time, Ceratothoa arimae (Nunomura, 2001) (Cymothoidae) from the buccal cavity of G. punctata in the Seto Inland Sea, Japan. Ceratothoa arimae showed a prevalence of 29.4–66.7% in G. punctata. The morphology of the mancae of this species was also described in comparison with that of the adult female (ovigerous), transitional stage, and adult male. The manca of Ceratothoa arimae has more chromatophores than those of other Ceratothoa species from Japan, and is a candidate for a future taxonomic trait. This species may have a negative impact on cultured G. punctata, which would be important to determine in future studies. Currently, it is difficult to identify cymothoid mancae species based on their morphology, but the information provided in this study could be useful when combined with other methods developed in the future, such as molecular analysis. Full article

The common octopus (Octopus vulgaris), among coleoid cephalopods, has evolved the most complex nervous system and sophisticated behaviors. Historically, O. vulgaris was a key animal model for neurophysiology research, and today, it is studied for its genomic innovations. However, unlike other models, there is no octopus farming for research, so specimens must be collected from the wild. This study assessed the impact of fishing on octopuses used in research, considering those caught using artisanal pots in the ‘Regno di Nettuno’ Marine Protected Area, Ischia (NA). To evaluate fishing stress, we identified morphological stress indicators such as chromatophore pattern and posture, and three potential molecular markers, estrogen receptor (ER), catalase (CAT), and heat shock protein (HSP70). We measured the percentage of stress signals shown by fished specimens and analyzed their differential gene expression. The transcriptional levels of octopuses caught using traps were compared to control specimens acclimated in captivity. Results indicated fluctuations in gene expression due to fishing stress. These findings suggest that an acclimation period after the stress event of fishing is crucial for ensuring the welfare of octopuses used in research, thus enhancing the quality of physiological and ethological studies. Full article

Carotenoids are crucial for photosynthesis, playing key roles in light harvesting and photoprotection. In this study, spheroidene and bacteriochlorophyll a (Bchl a) were reconstituted into the chromatophores of the carotenoidless mutant Rhodobacter sphaeroides R26.1, resulting in the preparation of high-quality LH2 complexes. Global and target analyses of transient absorption data revealed that incorporating B800 Bchl a significantly enhances excitation energy transfer (EET) efficiency from carotenoids to Bchl a. EET predominantly occurs from the carotenoid S₂ state, with additional pathways from the S₁ state observed in native LH2. Unique relaxation dynamics were identified, including the generation of the carotenoid S* state in reconstituted LH2 with both spheroidene and B800 Bchl a and the formation of the carotenoid T₁ state in reconstituted LH2. These findings underscore the critical influence of pigment composition and spatial organization on energy transfer mechanisms. They provide valuable insights into the molecular interplay that governs excitation energy transfer in photosynthetic light-harvesting systems. Full article

Disaccharide trehalose has been proven in many cases to be particularly effective in preserving the functional and structural integrity of biological macromolecules. In this work, we studied its effect on the electron transfer reactions that occur in the chromatophores of the photosynthetic bacterium Cereibacter sphaeroides. In the presence of a high concentration of trehalose, following the activation of the photochemistry by flashes of light, a slowdown of the electrogenic reactions related to the activity of the photosynthetic reaction center and cytochtome (cyt) bc₁ complexes is observable. The kinetics of the third phase of the electrochromic carotenoid shift, due to electrogenic events linked to the reduction in cyt b_H heme via the low-potential branch of the cyt bc₁ complex and its oxidation by quinone molecule on the Q_i site, is about four times slower in the presence of trehalose. In parallel, the reduction in oxidized cyt (c₁ + c₂) and high-potential cyt b_H are strongly slowed down, suggesting that the disaccharide interferes with the electron transfer reactions of the high-potential branch of the bc₁ complex. A slowing effect of trehalose on the kinetics of the electrogenic protonation of the secondary quinone acceptor Q_B in the reaction center complex, measured by direct electrometrical methods, was also found, but was much less pronounced. The direct detection of carbohydrate content indicates that trehalose, at high concentrations, permeates the membrane of chromatophores. The possible mechanisms underlying the observed effect of trehalose on the electron/proton transfer process are discussed in terms of trehalose’s propensity to form strong hydrogen bonds with its surroundings. Full article

Background color matching is essential for camouflage and thermoregulation in ectothermic vertebrates, yet several key cellular-level questions remain unresolved. For instance, it is unclear whether the number of chromatophores or the activity of individual chromatophores plays a more critical role in this process. Using single-cell RNA sequencing (scRNA-seq), we investigated the cellular and molecular mechanisms underlying color change in Rhacophorus dugritei, which adapted to its background by displaying light-green skin on white and black skin on black within two days. We identified two types of chromatophores in their skin, both responsible for the observed color differences. Our findings reveal that morphological color change (MCC) is the dominant process, with the number of chromatophores being more influential in driving color change than the transcriptional activity of melanogenesis in individual cells. Additionally, melanophores from darker individuals exhibited increased activity in energy metabolism pathways, while those from lighter individuals showed stronger immune-related gene expression, suggesting that background adaptation involves more than just morphological changes. Overall, this study successfully applied single-cell sequencing technology to investigate skin pigmentation in a non-model organism. Our results suggest that MCC driven by chromatophore proliferation is a key mechanism of background adaptation, offering new insights into amphibian color adaptation and environmental adaptation in other vertebrates. Full article

Fish exhibit a broad spectrum of colors and patterns facilitated by specialized cells known as chromatophores. The vibrant coloration of fish, controlled by complex genetic and environmental interactions, serves critical roles in ecological functions such as mating, predation, and camouflage. This diversity not only makes fish an invaluable model for exploring the molecular mechanisms of pigmentation but also significantly impacts their economic value within the aquaculture industry, where color traits can drive marketability and breeding choices. This review delves into the sophisticated biological processes governing fish pigmentation and discusses their applications in enhancing aquaculture practices. By exploring the intersection of genetic regulation, environmental influences, and advanced breeding techniques, this review highlights both the scientific understanding and practical applications of fish coloration, providing a bridge between basic biological research and its application in commercial aquaculture. Full article

Argonauts or paper nautiluses are pelagic octopod cephalopods with a cosmopolitan distribution in tropical and subtropical waters around the world. Unlike other species of octopus, these are characterized by the fact that the female has a shell that serves as the breeding chamber for the eggs. Over time, this structure has been used as a taxonomic diagnostic character, causing problems in the systematics of this genus, with around 50 synonymies reported. Only two species, Argonauta argo and A. nouryi, have been reported in the Northern Humboldt Current System; however, there is taxonomic uncertainty regarding these species, which is reflected in the paralarvae (the first stage of life after hatching). In the paralarvae, the chromatophore patterns are considered to be conservative and reliable taxonomic characteristics. The objective of this study is to demonstrate the extensive variability in the chromatophore arrangement of Argonauta paralarvae in the Northern Humboldt Current using DNA barcoding and five species delimitation models. Our results include up to 11 different paralarvae morphotypes according to the pattern of chromatophores (number and arrangement) and 2 shell morphotypes. Species delimitation methods divided the 13 Argonauta morphotypes into two consensus molecular taxonomic units (MOTUs), A. argo and A. nouryi. Additionally, the results revealed an extensive morphological variability in the paralarvae and female shells of A. nouryi, demonstrating the importance of molecular data in studies involving species with different life stages, especially when this extensive morphological variability obscures conventional analyses. Full article

Introduction: Monitoring cerebral perfusion in patients with brain injury is a major clinical challenge. Monitoring cerebral oxygenation (rSO2) via NIRS was introduced in the early 1980s, and many clinicians believed it to be a valuable method for assessing cerebral perfusion and subsequent measures to optimize cerebral flow. The main problem with the use of NIRS is the presence of intermediate structures—the skin, skull, meninges, cerebrospinal fluid—and their influence on the test result. Therefore, it seems that NIRS assessment performed on a patient during brain death can give an idea of the magnitude of the influence of these intermediate structures on the monitoring result. Case presentation: We present a case study of cerebral oxygenation measurements in a patient undergoing a brain death diagnostic procedure. A clinical situation in which cerebral blood flow is stopped can give an idea of the specificity of this method, in particular of the influence of intermediate structures on the monitoring result. In this case, the result obtained using NIRS is increased by the patient’s oxygenation before the apnea test. The influence of chromophores in the tissues surrounding the CNS and reflections and scattering of the light wave spectrum have a very significant effect on the final result of cerebral saturation measurement. Discussion: The majority of observations in existing research describing changes in cerebral perfusion or its optimization may be burdened by the problem described here, i.e., by the significant influence of measured intermediate structure oxygenation. The specificity of NIRS in assessing cerebral perfusion requires careful analysis. The therapeutic implications of monitoring cerebral oxygenation with NIRS are of great importance, and based on the example presented and the literature provided, this method should be used with caution. It has been shown that in a patient with brain death, the result of NIRS oxygenation measurements depends on the structures surrounding the brain. Full article