Shell Color Research Articles

Molecular signature of phylogenetic relationships and demographic history of Tunisian Mactra stultorum: Evidence from mitochondrial and nuclear DNA data

The genetic structure of Mactra stultorum is inferred from partial sequence of a mitochondrial cox1gene and of the internal transcribed spacer region ITS1. The samples with two colors of shell (white and brown) were collected from three sites belonging to the Tunisian coasts: Kalaât El Andalous (KA) and Soliman (SM) and Gabes (GM)). The phylogenetic trees obtained from the 2 markers are similar and subdivided samples into 3 distinct clades; clade (1) regrouped GM, clade (2) regrouped KS (KS contains samples from SM and KAa) and clade (3) is formed by KAb. Using the external sequences from genbank, it can be suggested that M. stultorum from the three clades KS, GM and KAb are three subspecies. The two sympatric M. stultorum from KA (KAa and KAb) appear to be genetically isolated showing a high genetic distance and no common haplotypes where the shell color serves for segregating marker. A total of 29 and 18 haplotypes were detected in the examined cox1 and ITS1 regions, respectively. Our study revealed higher levels of genetic diversity for ITS1 compared to cox1. For both markers, significant clinal changes in haplotypes frequencies between the north and the south populations supported by the absence of common haplotypes were observed. The demographic history of M. stultorum populations has been assessed using neutral tests and mismatch distribution for cox1 marker. A unimodal curve of the Mismatch’s distribution and negative significant neutral tests suggested a recent sudden demographic expansion for GM.

Egg quality and fatty acid profile of yolk in eggs from Athulya, native and IWN x native crossbred layers under backyard system

Backyard poultry production forms the basis for transforming the rural poultry sector from subsistence to a more economically productive base. The current study was conducted to evaluate the egg quality of eggs produced by Athulya, native and IWN x Native crossbred layers under backyard system. At 36 weeks of age, one egg from each group of birds was collected for fatty acid estimation of egg yolk and 20 eggs from each group was collected at 40 weeks of age for assessing the haugh unit score, yolk colour, shell thickness and shell colour. The beneficial polyunsaturated fatty acid content was higher in native bird eggs. The eggs from Athulya and native chicken had better internal quality in terms of haugh unit and yolk colour score. The shell thickness of eggs was similar among three groups. The egg shell colour was white in Athulya, tinted to brown in native and tinted in IWN x Native crossbreds and the shell colour in native and crossbreds exhibits more consumer preference.

Cornu aspersum (Gastropoda: Helicidae) in Western Ukraine with an overview of introduced species of land molluscs from this area

The first findings of Cornu aspersum in the Lviv region are described, including the shell size and shell colouration variability. A review of the known records of C. aspersum in different regions of Ukraine, from the second half of the 19th century to the present day, is also presented. The most probable ways of penetration and the possibility of further acclimatization of this species in Western Ukraine are discussed. The chronology of the records of introduced species of land molluscs in Western Ukraine is described in tabular form, which, to a large extent, should reflect the chronology of their penetration into this area. It is noted that the majority of alien species began to be found in Western Ukraine only at the end of the 20th or the beginning of the 21st century. Simultaneously several species appeared here, previously known only for the south of the country.

Genetic diversity in a genetically improved line of the Pacific oyster Crassostrea gigas with orange shell based on microsatellites and mtDNA data

The shell color is of interest to the shellfish industry and has been regarded as a target trait for a better commercial value. Based on an inbred variant line of the Pacific oyster Crassostrea gigas with orange shell obtained previously, a genetically improved orange-shell line was formed through hybridization and subsequent mass selection. In the present study, the genetic diversity among the base population (G0) and two successive mass-selected generations of the improved orange-shell line of C. gigas (G1 and G2) were assessed by both 15 microsatellites and mitochondrial cytochrome oxidase I sequences (mtCOI) compared to four outbred populations and three progenitor selected strains. The microsatellite results showed that the genetic variation over two generations of mass selection were maintained since no significant reduction in average number of alleles (Nα: 4.87–5.40), expected heterozygosity (He: 0.59–0.61) and expected heterozygosity (Ho: 0.48–0.54) compared with those of G0. The number of different alleles in the generations of improved orange-shell line ranged from 73 to 81 alleles, which was approximate 55–64% less than the 176–204 alleles found in the oysters from wild populations. The Nα in G0-G2 were obviously higher than that of the inbred orange-shell line without improvement. The differences in alleles in the improved orange-shell line compared to four wild populations is likely due to small broodstock size resulting in genetic drift over successive generations. Effective population size of G1 and G2 calculated by linkage disequilibrium methods was 63.2 and 89.8, respectively. On a population level, pairwise FST value (FST: 0.14–0.21) along with AMOVA analysis indicated medium to high genetic differentiation between the improved orange-shell line and outbred populations and progenitor selected strains. Overall, the results of microsatellite suggested that the genetic diversity of the improved orange shell line was not affected greatly by mass selection during the process of improvement. This study provides insight into utilization of shell color variants and future genetic improvement through selective breeding in aquaculture.

Application of Dipping on CaCl2 as a Postharvest Treatment to Maintain the Quality of Pineapple during Storage

Pineapple is a perishable agricultural products, therefore it needs an appropriate treatments at the postharvest stage. An appropriate treatment will contribute on maintaining the quality and prolong shelf life of the products. Recently, several efforts have been conducted to achieve the purposes. Moreover, appropriate treatments are still required for alternatives solution of pineapples producers. This study aims to determine the effect of the dipping on CaCl2 solution at various concentration on physical (mold incidence and mold severity), chemical (pH value) and sensory properties (color, texture, aroma, taste, and overall acceptance) of pineapple during storage. The dipping of the fruits were conducted at hot condition (50℃). The samples were MD-2 pineapple with two different classification of shell color (shell color 0 and shell color 2). The results showed that there was no significant effect of CaCl2 application treatment by dipping in hot water (50℃) on the parameters of pH value. The incidence and severity of mold were detected after 16th of storage on treated samples and the control. After storage for 40th days, the treated sample had better sensory properties, particularly on texture, color, and overall acceptance.

Cloning and characterization of microphthalmia‐associated transcription factor‐like gene provide insights into Cyclina sinensis clam shell melanin deposition

The reversible black shell colour change in the clam Cyclina sinensis functions as an adaptation to different environmental conditions (within or outside of muddy sediment) due to changes in the melanin redox state in the shell. The microphthalmia-associated transcription factor (MITF) is a melanocyte-specific transcription factor that is involved in the differentiation, proliferation and survival of melanocytes. In this study, the full-length cDNA sequence of the mitf-like gene was obtained from C. sinensis using RACE PCR. The mitf-like cDNA is 1725 bp in length, containing a 47 bp 5′ untranslated region (UTR), a 1398 bp open reading frame and a 280 bp 5′ untranslated region. The mitf-like gene contains seven exons separated by six introns, and it encodes a putative protein of 465 amino acids with a highly conserved domain of MITF containing a basic helix-loop-helix leucine zipper (bHLH-LZ). The phylogenetic analysis of amino acid sequences using neighbour-joining and maximum likelihood methods revealed that C. sinensis is closely related to Meretrix petechialis. Additionally, the mRNA expression of mitf-like and melanin was high in the outer margin of the mantle, suggesting that the mitf-like might play an important role in melanin synthesis in the mantle by regulating the cell cycle and survival of melanocytes; however, its role in C. sinensis shell melanin deposition requires further investigation.

MiRNA-mRNA Integration Analysis Reveals the Regulatory Roles of MiRNAs in Shell Pigmentation of the Manila clam (Ruditapes philippinarum).

The shell color of the Manila clam (Ruditapes philippinarum) is an economically important trait. We used high-throughput sequencing and transcriptome analysis to study the molecular mechanisms that underlie shell color formation and regulation in this species. We constructed small RNA libraries from mantle tissues from four shell color strains of Manila clam, subjected them to high-throughput sequencing. Notably, the results suggested that a number of pigment-associated genes including Mitf, HERC2, were negatively regulated by nvi-miR-2a, tgu-miR-133-3p, respectively. They might be involved in melanin formation via the activation of the melanogenesis pathway. And aae-miR-71-5p and dme-miR-7-5p linked to shell formation-related genes such as Calmodulin and IMSP3 were considered to participate in the calcium signaling pathway. We then used quantitative PCR to verify the candidate miRNAs and target genes in different shell color groups. Our results indicated that miR-7, miR-71, and miR-133 may regulate target mRNAs to participate in shell color pigmentation. These results provide the foundation to further characterize miRNA effects on the regulation of shell color and have significant implications for the breeding of new varieties of clams.

In the Asia-Pacific region, the COI DNA test revealed the divergence of the bivalve mollusc Mactra chinensis into three species; can these species be distinguished using shell coloration and sperm structure?

According to COI DNA barcoding testing, the marine bivalve mollusc Mactra chinensis, which is native to the Asia-Pacific region, diverged into three species. These species were preliminary characterized as M. chinensis COI clade I, M. chinensis COI clade II and M. chinensis COI clade III. To find out whether it is possible to morphologically distinguish samples representing genetic clades, we examined the color of the shells and the structure of the spermatozoa. It was found that the number of detected coloration types exceeds the number of detected species. In addition, it was shown that individuals belonging to the same genetic clade can have shells of different colors. Consequently, it is impossible to choose one type of shell coloration as a species-specific trait. For sperm, the sperm morphological patterns found in each of the three species are consistent with the M. chinensis sperm model described in previous reports. However, the single sperm variant is also not applicable to discriminate between species derived from M. chinensis, since heterogeneous variants of spermatozoa differing in the length of the acrosomal rod were found. We hypothesized that genetic divergence of species could cause a shift towards predominance of one of the sperm variants, and that species-specific sperm morphs could be quantitatively dominant in molluscs belonging to different clades. However, the dominant sperm morphs were the same in COI clade I and COI clade III. Thus, dominant sperm morphs are useless as species-specific traits. However, shell color and sperm parameters are specific to different geographic regions, and it seems that unique environmental factors can determine shell color and sperm morphology. As a result, both shells and spermatozoa can be used to distinguish the geographical forms of M. chinensis, regardless of the belonging of the forms to a particular genetic clade. Here we propose the introduction of geographic identifiers, in which the shell color and parameters of sperm sets are used as morphological criteria to determine the geographical origin of mollusc specimens belonging to the M. chinensis species complex.

Shell colour diversification induced by ecological release: A shift in natural selection after a migration event.

Ecological release is often attributed to the rapid adaptive diversification of phenotypic traits. However, it is not well understood how natural selection changes its strength and direction through the process of ecological release. Herein, we demonstrated how shell colour of the Japanese land snail Euhadra peliomphala simodae has diversified via a shift in natural selection due to ecological release after migration from the mainland to an island. This snail's shell colour diversified on the island due to disruptive selection after migration from the mainland. We used trail camera traps to identify the cause of natural selection on both the mainland and the island. We then conducted a mark–recapture experiment while collecting microhabitat use data. In total, we captured and marked around 1,700 snails on the mainland, some of which were preyed upon by an unknown predator. The trail camera traps showed that the predator is the large Japanese field mouse Apodemus speciosus, and the predatory frequency was higher on the mainland than on the island. However, this predation did not correlate with shell colour. Microhabitat use on the island was more extensive than on the mainland, with snails on the island using both ground and arboreal microhabitats. A Bayesian estimation showed that the stabilizing selection on shell colour came from factors other than predation. Our results suggest that the course of natural selection was modified due to ecological release after migration from the mainland, explaining one cause of the phenotypic diversification.

Genome-wide DNA methylation profile changes associated with shell colouration in the Yesso scallop (Patinopecten yessoensis) as measured by whole-genome bisulfite sequencing

BackgroundMollusca, a phylum of highly rich species, possess vivid shell colours, but the underlying molecular mechanism remains to be elucidated. DNA methylation, one of the most common epigenetic modifications in eukaryotes, is believed to play a vital role in various biological processes. However, analysis of the effects of DNA methylation on shell colouration has rarely been performed in molluscs, limiting the current knowledge of the molecular mechanism of shell colour formation.ResultsIn the present study, to reveal the role of epigenetic regulation in shell colouration, WGBS, the “gold standard” of DNA methylation analysis, was first performed on the mantle tissues of Yesso scallops (Patinopecten yessoensis) with different shell colours (brown and white), and DNA methylomes at single-base resolution were generated. About 3% of cytosines were methylated in the genome of the Yesso scallop. A slight increase in mCG percentage and methylation level was found in brown scallops. Sequence preference of nearby methylated cytosines differed between high and low methylation level sites and between the brown- and white-shelled scallops. DNA methylation levels varied among the different genomic regions; all the detected regions in the brown group exhibited higher methylation levels than the white group. A total of 41,175 DMRs (differentially methylated regions) were detected between brown and white scallops. GO functions and pathways associated with the biosynthesis of melanin and porphyrins were significantly enriched for DMRs, among which several key shell colour-related genes were identified. Further, different correlations between mRNA expression levels and DNA methylation status were found in these genes, suggesting that DNA methylation regulates shell colouration in the Yesso scallop.ConclusionsThis study provides genome-wide DNA methylation landscapes of Yesso scallops with different shell colours, offering new insights into the epigenetic regulatory mechanism underlying shell colour.

PSIV-B-26 Effect of different intakes of sulfur amino acids on the productive response and egg quality of commercial laying hens

Abstract Modern laying hens have improved their productive response and persistence of egg production. However, in terms of productivity, egg quality and profitability, there are still several issues that need to be reevaluated and improved, among them the level and consumption of digestible sulfur amino acids (AASD). The objective is to determine the effect of different AASD consumptions on the productive response and egg quality of commercial laying hens. METHODS: 160 laying hens of the LOHMANN Brown genetic line, 90 weeks old, of uniform weight and size, were used. The laying hens were distributed in the study area, following the protocol of a Random Block Design (DBA). 4 AASD intakes (g / hen / day) were established as treatments: T-1 (730.11 mg), T-2 (677.20 mg), T-3 (607.09 mg) and T-4 (676.88 mg). Each of the treatments had 5 repetitions, giving a total of 20 experimental units. The variables of egg production, egg weight and mass, feed consumption, feed conversion index, energy efficiency, Haugh unit of the egg, shell color and percentage, egg yolk color and index, margin and economic reward were evaluated. RESULTS: The results showed that the different AASD consumptions did not significantly affect (P > 0.05) the productive response and egg quality of the hens and affected the margin and economic retribution. AASD intakes in the range of 607 to 730 mg / hen / day did not affect the productive response and egg quality. The metabolizable energy level of the diet influences the economic response to different intakes of digestible sulfur amino acids. The consumption of 676.88 mg / hen / day of AASD with a level of 2725 Kcal of metabolizable energy / Kg of feed achieved the highest gross margin and best economic return in 90-week-old LOHMANN Brown laying hens.

Effects of air exposure at different temperatures in selected breeding lines of Pinctada fucata with different shell color

In this study, effects of different temperatures (20 ℃, 25 ℃, and 30 ℃) air exposure (12 h) on the survival rate and biochemical indexes of four shell color stains of Pinctada fucata were studied. The survival rates of P. fucata after 72 h′ re-watering period, and the activities of 11 biochemical indexes of P. fucata were measured. 11 biochemical indexes included as follows: digestive enzymes (lipase (LPS), amylase (AMS) and cellulase (CL)), antioxidant related indicators (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), anti-superoxide anion free radical (ASAFR), peroxidase (POD), total antioxidant capacity (T-AOC)) and hydrolytic enzymes (acid phosphatase (ACP) and Alkaline phosphatase (ALP)). The results showed that 12 h′ air exposure at 30 ℃ significantly reduced the survival rate of P. fucata (P < 0.05), and the black shell color breeding line had the highest survival rate (80%), while the golden shell color breeding line had the lowest survival rate (44%) in the 30 ℃ group. Shell colors and air exposure temperatures would lead to significant differences in digestive enzymes (LPS, AMS, CL), hydrolytic enzymes (ACP, ALP), and antioxidant related indicators (T-AOC, POD, SOD, CAT, GSH-Px, ASAFR) of P. fucata (P < 0.05), and there existed significant interactions (P < 0.05). The air exposure tolerance of four shell color strains of P. fucata was different with each other, and the black shell color strains of P. fucata may have the strongest tolerance. In addition, GSH-Px and CAT could be used as a test indicator of the ability of P. fucata to resist the stress of air exposure. In order to reduce the damage to the body caused by air exposure, P. fucata may take the lipid and cellulose as main energy sources during the air exposure stress, and combine the action of the antioxidant system with the hydrolytic enzymes to remove excessive reactive oxygen species (ROS) and then carry out the related immune responses.

Introduced land snail Cepaea nemoralis (Gastropoda: Helicidae) in Eastern Europe: spreading history and the shell colouration variability

The available data on the present distribution of Cepaea nemoralis in Ukraine, Belarus and the European part of Russia, the history and possible ways of penetration of this species into various parts of Eastern Europe, as well as the colour and banding polymorphism of its shells are analyzed. It has been suggested that the process of rapid spreading of C. nemoralis in the three compared Eastern European countries began at approximately the same time (late 20th – early 21st centuries) and that it may be caused by active and practically uncontrolled importation of seedlings from other European countries, as well as by global climate change, which can contribute to better survival of snails outside their natural range. Despite the possible initial limitation of the phenotypic and genetic diversity associated with the accidental transfer of a limited number of individuals, in the Eastern European colonies, in general, a fairly large variety of the inherited traits of the shell colouration remains. This concerns, first of all, the polymorphism in the shell ground colour (yellow, pink, less often brown) and the main variants of the shell banding (unbanded, mid-banded, five-banded, less often three-banded).

Crab diversity as support for ecotourism activities in Pejarakan Mangrove Forest, Buleleng, Bali, Indonesia

Abstract. Ginantra IK, Muksin IK, Joni M. 2021. Crab diversity as support for ecotourism activities in Pejarakan Mangrove Forest, Buleleng, Bali, Indonesia. Biodiversitas 22: 4139-4145. This research aims to determine the diversity of crabs to support ecotourism activities in the coastal mangrove forest of Pejarakan Buleleng. Sampling of crabs was carried out using the square method, as many as 23 squares were spread over three mangrove zones, namely the front zone, the middle zone, and the rear zone. The number of individual crustacean species in each square plot was counted. Crab identification is based on morphological characters (shell color, claw shape, body-color, body size). Habitat use activities are observed directly. The diversity of crabs was calculated using the Shannon-Wiener diversity index. The results showed that in the coastal mangrove area of Pejarakan Buleleng, there were 11 species of crabs (9 species of crabs and 2 species of hermit crabs). Species diversity is in the medium category (index 2.25) and evenness index is high (E = 0.93, mangrove conditions are stable). The seaward mangrove zone shows a higher diversity of crab species than the middle zone and the rear zone. The species of crabs that are quite abundant in the three zonings are Uca vocans, Chiromanthes sp., and Coenobita sp. Characteristics of crabs, activities, habitat use in mangrove zoning are attractions for ecotourism activities.

Negative assortative mating and maintenance of shell colour polymorphism in Littorina (Neritrema) species

Colour polymorphism is a widespread phenomenon in natural populations of several species. In particular, it is especially common on marine gastropod species from the genus Littorina. Recently, it has been argued that intrapopulation shell colour polymorphism in Littorina fabalis could be caused by negative frequency-dependent sexual selection via a mechanism of mate choice (indirectly estimated through negative assortative mating). Here we try to determine the existence of negative assortative mating in three species of the subgenus Neritrema (L. fabalis, L. obtusata, L. saxatilis) that share a similar shell colour polymorphism, to ascertain if this mechanism could represent an ancestral character in this subgenus that could be contributing to the maintenance of the colour polymorphism observed in each species. We collected or reanalysed from previous studies a sample of mating pairs of these three species from seven locations from NW Spain and NE Russia and estimated assortative mating using the IPSI index. Our results suggest that all species and populations show a systematic tendency towards negative assortative mating when shell colour is grouped in the broad categories ‘light’ and ‘dark’. Moreover, a more detailed analysis of each colour separately suggests that shell colour may not be the main target of assortative mating, but perhaps a physically-linked trait to the real target of selection. This hypothesis opens interesting new lines of research in Littorina snails.

Specification of polymorphism and classification of shell coloration in gastropods by the example of Littorina obtusata (Gastropoda: Littorinidae)

Understanding the patterns of microevolutionary processes involves a wide range of population genetic studies on different species. However, the number of genetically studied species is limited due to significant methodological difficulties in testing the genetic conditionality of various traits. Developing population phenetics may become an alternative, which allows considering a large number of new species subject to development of morphologically and genetically-based system to describe the variability and classification of phenotypic traits. Gastropods are a classic object for carrying out population genetic studies based on the analysis of polymorphism of shell coloration. The parametric classification system proposed by S. Sergievsky et al. (1995) for periwinkles of the genus Littorina may serve as a basis for the developing of a universal system for classifying color traits for that taxonomic group. Since a large amount of new data has been published in recent years, this system requires correction and revision. The study aims to revise the system, taking into account new material on the pigment composition, as well as on the peculiarities of the formation and inheritance of color traits, their joint occurrence, etc. A revised and modified classification system for shell coloration traits is presented by the example of the White Sea gastropods L. obtusata; this system considers the idea of the formation of a phenotype as a combination of several elementary traits. These are traits associated with the formation of: 1) a shell background color (the ability to include different pigments in the ostracum and the hypostracum color); 2) a pattern of spots (the presence of inclusions of white and/or brown pigment); and 3) wide longitudinal bands (brown, white, and orange). Elementary traits are highlighted taking into account the pigments involved, as well as the mechanisms of their formation and inheritance. When describing the shell coloration, elementary traits are first used to describe relatively simple traits (groups of phenes “Shell background color”, “Hypostracum color”, “Pattern of spots”, and “Wide longitudinal bands”), which are subsequently combined to describe the phenotype as a whole. Our study provides an overview of the available data on the qualitative composition of shell pigments in periwinkles and patterns of formation and inheritance of color traits; their possible combinations are described. The phenes isolated by us are described together with their occurrence, color specification in the RGB system, and the peculiarities of the formation, taking into account the distribution of pigments in the shell. Visible traits, that may be used to assess the distribution of pigments in the shell, are indicated. The ontogenetic changes in traits are described. Despite the fact that the proposed classification system is developed by the example of L. obtusata, it can be used for same purposes for other periwinkle species and, with some modifications, for a wide range of gastropod species.

Influence of feed additives for chickens on the quality of eggs laid and related risks

A chicken egg is a valuable animal product that has served people for centuries. Research carried out over the last dozen or so years shows that society's knowledge about them is still relatively small. The research cited in the text shows that only 23% of respondents know that the color of a hen's egg shell depends on the breed of the hen, and not on the way it is fed. As a result, some consumers choose eggs in the store by choosing their color instead of the official markings on each individual egg. Chickens' nutrition has a direct impact on the quality of the eggs they lay. Chickens fed with fodder with antibiotics lay eggs in which we can find the same antibiotics that the animal ate with the food. It has many side effects, however, the greatest of which seems to be bacterial drug resistance, caused by the use of the same strong antibiotics in the nutritional industry and in human hospital medicine. Bacteria have developed various resistance mechanisms. For example, Enterococcus spp. Has developed resistance to vancomycin, Salmonella Typhimurum to tetracyclines, sulfonamides and fluoroquinolones. However, it is possible to use antibiotics in poultry treatment, but it is very important in this case to strictly observe the grace periods necessary to eliminate the antibiotic from the animal's body. Some of the world's governments, aware of the dangers of such a state of affairs, are trying to combat the phenomenon of feeding poultry with antibiotic growth stimulants by introducing new norms, orders and bans in their countries. Antibiotics such as avoparcin, zinc-bacitracin and spiromycin have been discontinued. Chicken egg producers are finding newer and newer ways to circumvent these recipes. Non-antibiotic feed additives such as probiotics, phytobiotics, and specific herbs are used. An effective way to combat this phenomenon may be to educate the public on this topic.

Characterization and Function Analysis of β, β-carotene-9′, 10′-oxygenase 2 (BCDO2) Gene in Carotenoid Metabolism of the Red Shell Hard Clam (Meretrix meretrix)

The relationship between carotenoid and shellfish shell color has gained increasing attention. β, β-carotene-9′,10′-oxygenase 2 (BCDO2) is a key enzyme in animal carotenoid metabolism, and its accumulation affects the change in body color, as demonstrated in mammals, birds, and fish. However, it is unclear whether BCDO2 is involved in the formation of the red shell color of clam. To explore the molecular structure and biological function of BCDO2 gene in the process of carotenoids accumulation, in this study, the BCDO2 from hard clam Meretrix meretrix (designated as Mm-BCDO2) was cloned and characterized, and the single-nucleotide polymorphisms (SNPs) associated with shell color were detected. The results of qRT-PCR indicated that Mm-BCDO2 gene was expressed in all six tested tissues, and the expression of mantle was significantly higher than other tissues (P &amp;lt; 0.05). The association analysis identified 20 SNPs in the exons of Mm-BCDO2, among which three loci (i.e., c.984A &amp;gt; C, c.1148C &amp;gt; T, and c.1187A &amp;gt; T) were remarkably related (P &amp;lt; 0.05) to the shell color of clam. The western blot analysis revealed that the expression level of Mm-BCDO2 in the mantle of red shell clams was stronger than that of white shell clams (P &amp;lt; 0.05). Further, the immunofluorescence analysis indicated that the single-layer columnar cells at the edge of the mantle were the major sites for the Mm-BCDO2 secretion. This study explored the potential impacts of BCDO2 gene on the shell color of M. meretrix, which provided a theoretical basis for a better understanding of the important role of BCDO2 in carotenoid metabolism.

Phenoloxidase is involved in the immune reaction of Helix lucorum to parasitic infestation by dicrocoeliid trematode.

Phenoloxidases are known to play a role in the immune defences of arthropods and molluscs. In the invertebrates, phenoloxidases mediate three major physiologically important processes: sclerotization, wound healing, and defence reactions. Helix lucorum serve as the first intermediate host for the larval stages of dicrocoeliid trematodes which infects animals as well as human beings. The aim of the study is to investigate the effect of larval forms of dicrocoeliid trematodes to phenoloxidase acitivity in H. lucorum, Linneaus, 1758, in Bitlis, Turkey. The effect of the snail's shell colour to phenoloxidase activity was also investigated. Land snails (n=200) were collected by hand from their natural habitats during the period May - June 2019 in Bitlis, Turkey. Evaluation of the process was performed by measuring immune reaction of the snails against larval forms of dicrocoeliid trematodes. Phenoloxidase activity assay was carried out using a spectrophotometer device based on 3,4-Dihydroxy-L-phenylalanine (L-dopa) hydrolysis. The natural infection rate of the land snails with the developmental stages of dicrocoeliid trematodes was 20%. Phenoloxidase activity was found to be significantly higher (*p<0.05) in larval forms of dicrocoeliid trematodes infected snails when compared with non-infected snails. No effect of shell colours to phenoloxidase activity was observed. To the best of the authors' knowledge, this study is the first to report that the phenoloxidase system is involved in the immune reaction of Helix lucorum to parasitic infestation by larval forms of dicrocoeliid trematodes.

Comparison of Growth Performance, Carotenoid Content, and Temperature Tolerance of Two-Colored Strains of the Red Claw Crayfish Cherax quadricarinatus

The color of aquatic animals plays an important role in consumer acceptability and perceived quality. In a previous study, a red claw crayfish Cherax quadricarinatus strain with steady and hereditary shell color of blue was selected. To evaluate the potential value of this strain in crayfish culture, the growth performance, carotenoid content, and temperature tolerance of two crayfish strains (shell color; blue and blue-green) were conducted. After the 56-day rearing period, blue crayfish showed higher feed intake and growth rate, but lower survival than blue-green crayfish. Astaxanthin was the main pigment observed in the carapace of both strains, and the content of astaxanthin in blue crayfish was 18.62 mg/kg of wet weight, which was significantly lower than that of astaxanthin in blue-green crayfish (83.23 mg/kg of wet weight). The 7-day survival of two crayfish strains less than 34°C was 100%, and blue-green crayfish showed stronger tolerance to high water temperature exposure (35°C–38°C) than blue crayfish. Furthermore, after high temperature stress, lower activities of superoxide dismutase and catalase, and higher malondialdehyde in the hepatopancreases of blue crayfish were observed than those in blue-green crayfish. This study provides important information for future breeding programs for the red claw crayfish.