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The growth environment significantly influences the intestinal microbiota of aquatic organisms. We investigated the composition and functional differences in the intestinal microbiota of red claw crayfish (Cherax quadricarinatus) in rice fields (RB) and ponds (PB) by 16S rDNA high-throughput sequencing technology. The results indicate that the Shannon, Simpson, Sobs, Chao1, and ACE indices of PB are all higher than those of RB, demonstrating greater diversity and richness of intestinal microbiota. The dominant phyla in the intestinal microbiota of the Cherax quadricarinatus were Proteobacteria, Tenericutes, and Firmicutes. Tenericutes and Proteobacteria were significantly more abundant in the RB than in the PB, while Planctomycetes and Firmicutes were significantly more abundant in the PB than in the RB. The results of network correlation analysis indicate that Proteobacteria and Firmicutes exhibit strong connectivity with other microbial groups in the gut microbiota of Cherax quadricarinatus, showing significant centrality. They play an important role in the interactions within the gut microbiota community. The dominant bacterial genera in the Cherax quadricarinatus's gut were Citrobacter, Candidatus_Bacilloplasma, and Clostridium_sensu_stricto_1. The abundance of the genus Clostridium was significantly higher in the PB than in the RB, whereas the abundance of Candidatus_Hepatoplasma and Vibrio was significantly lower in the PB than in the RB. The prediction function of KEGG enrichment showed that the abundance of Amino acid metabolism, Biosynthesis of Other Secondary Metabolites, Transport and Catabolism, Cancers, and Nervous System, Substance Dependence were significantly higher in the PB, while the infectious diseases pathway was enriched in the RB. In summary, our results revealed significant differences in the composition and diversity of intestinal microbiota in the Cherax quadricarinatus between rice paddy and pond farming environments. The intestinal microbiota of the Cherax quadricarinatus grown in pond environments exhibit higher diversity and stability, manifested by an increase in beneficial bacteria abundance and a decrease in opportunistic pathogens. These findings significantly improve understanding of the complex relationship among Cherax quadricarinatus, intestinal microbiota, and the environment. [ABSTRACT FROM AUTHOR]

Understanding the eco‐evolutionary processes which drive phenotypic variability in non‐native species is crucial to predicting impact and informing spatially explicit management models. Invasive redclaw crayfish, Cherax quadricarinatus, are spreading rapidly through the ecologically and economically important Upper and Middle Zambezi system in south‐central Africa.We tested whether there was an invasion front effect in the Barotse floodplain and disentangle whether these effects were related to environmental filtering, spatial sorting, or density‐dependent processes along a nonlinear 200 km invasion gradient over seasonal hydrological periods.Crayfish spread up‐ and down‐stream indicated an expanding population compared to the former invasion front in 2019, facilitated by both sexes. Wet season detection probability and relative abundance were lower than in the dry season. No signals of environmental filtering were detected as a result of high connectivity of habitats in the wet season.The invasion front population was characterised by lower relative abundance, lower body condition, larger overall body and chelae size, and longer front leg length. There was no effect on sex ratio. This indicated that spatial sorting, density‐dependent processes and predation pressure are acting as selective forces on phenotypic variability across the invasion gradient.Better understanding of the effects of flood regime and trophic interactions on phenotypic variability and dispersal is urgently needed. Population suppression to reduce spatial sorting and conspecific competition could be a viable management option at the invasion front. [ABSTRACT FROM AUTHOR]

【Objective】This trial was conducted to investigate the protein nutrient demand of crayfish (Cherax quadricarinatus) in low salinity (1.5‰), which would provide a theoretical basis for the development of artificial compound feed of crayfish in low salinity.【Method】Six kinds of equal energy feeds with different protein levels of 26.83% (D1), 29.71% (D2), 32.59% (D3), 35.42% (D4), 38.37% (D5) and 41.09% (D6) were prepared, and the crayfish larvae with initial weight of (0.41±0.01) g were cultured for 56 d as research objectives. The influence of feed protein level on the growth performance, basic muscle nutrients and amino acid content of young crayfish in low salinity culture environment were analyzed.【Result】The results showed that dietary protein level significantly affected the weight gain rate, specific growth rate, crude protein and crude lipid contents, and amino acid content (P＜0.05, the same below), but did not show any significant influence on survival rate, moisture and ash content of the crayfish (P＞0.05, the same below) . The weight gain rate and specific growth rate of crayfish in each group first increased and then decreased with the increase of protein level in the dietary. The weight gain rate in D3 was the highest, which was significantly higher than that in other groups. There was no significant difference in specific growth ratio among D3-D6 groups, but it was significantly higher than that in D1 and D2 groups. The crude protein content in crayfish muscle was positively correlated with the dietary protein level, and the crude protein content in high protein level group (D5, D6) was significantly higher than that in other groups. On the contrary, the crude lipid content of crayfish muscle was negatively correlated with the dietary protein level, and the crude lipid content of crayfish muscle decreased significantly with the continuous increase of dietary protein level. Seventeen amino acids were detected in muscle, including 7 essential amino acids (EAA), 2 semi-essential amino acids (HEAA) and 8 non-essential amino acids (NEAA) . The total amount of amino acids with protein level of 29.71%-41.09% increased significantly with the increase of dietary protein level.【Conclusion】In the low salinity culture environment, considering specific growth rate, the optimum protein level of crayfish feed was 36.09%. And considering umami amino acid ratio(WDAA/WTAA), the optimum protein level of crayfish feed was 30.96%. [ABSTRACT FROM AUTHOR]

Abstract Background The introduction of non-native species is a primary driver of biodiversity loss in freshwater ecosystems. The redclaw crayfish (Cherax quadricarinatus) is a freshwater species that exhibits tolerance to hypoxic stresses, fluctuating temperatures, high ammonia concentration. These hardy physiological characteristics make C. quadricarinatus a popular aquaculture species and a potential invasive species that can negatively impact tropical and subtropical ecosystems. Investigating the genomic basis of environmental tolerances and immune adaptation in C. quadricarinatus will facilitate the development of management strategies of this potential invasive species. Results We constructed a chromosome-level genome of C. quadricarinatus by integrating Nanopore and PacBio techniques. Comparative genomic analysis suggested that transposable elements and tandem repeats drove genome size evolution in decapod crustaceans. The expansion of nine immune-related gene families contributed to the disease resistance of C. quadricarinatus. Three hypoxia-related genes (KDM3A, KDM5A, HMOX2) were identified as being subjected to positive selection in C. quadricarinatus. Additionally, in vivo analysis revealed that upregulating KDM5A was crucial for hypoxic response in C. quadricarinatus. Knockdown of KDM5A impaired hypoxia tolerance in this species. Conclusions Our results provide the genomic basis for hypoxic tolerance and immune adaptation in C. quadricarinatus, facilitating the management of this potential invasive species. Additionally, in vivo analysis in C. quadricarinatus suggests that the role of KDM5A in the hypoxic response of animals is complex.

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For the first time, the data on the feeding habits of the Australian red claw crayfish Cherax quadricarinatus in water bodies of Russia are presented. The studies were carried out during the cultivation of crayfish in three ponds of the scientific and experimental complex of aquaculture BIOS of the Volga-Caspian branch of the Russian Federal Research Institute of Fisheries and Oceanography (VNIRO) in Astrakhan oblast in 2022. The food spectrum of C. quadricarinatus was dominated by plant remains and detritus (mainly rotting parts of cane), they were noted in all stomachs with food, and their share in the virtual food bolus constituted 82.4% on average. The share of the animal component in the virtual food bolus was 12.8% on average, and it was represented mainly by macrobenthos. Planktonic crustaceans did not make up a significant proportion in the virtual food bolus. In total, 20 taxa of invertebrates were found in stomachs. Among the benthic species, larvae of Odonata, chironomids, and larvae and imagoes of Coleoptera predominated. A preliminary assessment of the possible impact of crayfish Cherax quadricarinatus on ecosystems when it penetrates into natural water bodies of the South of Russia has been carried out. [ABSTRACT FROM AUTHOR]

Fishing is part of human culture since ancient times to catch fish. The use of live bait by anglers is an important factor in the spread of invasive aquatic species. To analyze the habits of Indonesian anglers in using freshwater crayfish as live bait, an anonymous online questionnaire was spread via social media in Indonesia. The questionnaire included a series of closed and open-ended questions that investigated various socio-psychological parameters and types of bait used by Indonesian anglers. Redclaw crayfish Cherax quadricarinatus, which is non-indigenous in most of the Indonesian territory, was found to be used by 13% of anglers for this purpose there. These findings illustrate the need for focused management activities. Any potentially invasive non-native species imported into Indonesia, as well as those that are accidentally or deliberately released into the waters, should be regulated, so as not to cause environmental damage. [ABSTRACT FROM AUTHOR]

Aim. The concentration of total protein in the hemolymph of the Australian red-clawed crayfish Cherax quadricarinatus, Von Martens 1868, contained in artificial conditions in closed water supply installations and an aquarium complex, was studied. Methodology. The object of the study was the Australian red-clawed crayfish, a total of 161 individuals were used in the experiment. Crayfish were kept in closed water supply installations. To study the protein concentration depending on the time of year, samples were taken and analyzed in the period 2021-2023: January – winter; April – spring; August – summer; September, October and November – autumn. To conduct an experiment to study the total protein content of cancer hemolymph, depending on the water temperature, three experimental groups of 15 cancers were formed in each. The experimental groups were seated in three aquariums, with a water temperature of 20, 25, 30 ° C. The duration of the crayfish exposure was 10 days. On the tenth day, hemolymph was collected. The total hemolymph protein was determined by the refractometric method. Results. It was found that the concentration of total protein in the hemolymph can be in the ranges from 10.8 to 108.8 g/l and average 50.5 ± 21.1 g/l. In crustaceans kept in unfavorable conditions, the concentration of total protein was 1.6 times lower. There were no differences in protein concentration at different seasons of the year. After molting, the concentration of total protein in the hemolymph decreases 2.7 times. It was found that short-term exposure of cancer in water with a temperature of 20, 25, 30 ° C does not lead to a change in the total protein content. Conclusion. A wide range of total protein concentrations may indicate a high adaptive potential of this organism. A decrease in the concentration of total protein may be due to the presence of a crustacean in unfavorable conditions and its defeat by a bacterial agent. It is noted that the change in protein concentration at different times of the year in a crustacean under artificial conditions cannot be interpreted as seasonal fluctuations.

The purpose of the experiment was to study the effects of Lactobacillus on the growth performance and intestinal microbial community structure of Cherax quadricarinatus. A total of 600 Cherax quadricarinatus seedlings with initial weight of (0.55±0.05) g were randomly divided into four groups with three replicates in each group and 50 shrimp seedlings in each replicate. CA group, TB group, TC group, and TD group were fed with 0, 1.8x105, 1.8x106, and 1.8x107 CFU/g of Lactobacillus, respectively. The trial period was 45 days. The results showed that compared with CA group, the final weight, weight gain rate, and specific growth rate of Cherax quadricarinatus in TB group and TC group increased significantly (P<0.05), the feed coefficient in TC group decreased significantly (P<0.05), while the growth performance of TD group did not increase further. The addition of Lactobacillus in feed obviously changed the intestinal microflora structure of Cherax quadricarinatus, improved the diversity and abundance of beneficial bacteria in intestinal tract, and inhibited the growth of conditional pathogenic bacteria, especially in the early stage. The results showed that adding 1.8x106 CFU/g Lactobacillus to the feed could obviously improve the growth performance of Cherax quadricarinatus, increase the diversity and abundance of beneficial bacteria in the intestinal tract of Cherax quadricarinatus, inhibit the growth of conditional pathogenic bacteria, and benefit the health of Cherax quadricarinatus. [ABSTRACT FROM AUTHOR]

Freshwater lobsters are one of the crustacean commodities that have started to be developed through cultivation. Besides having high nutritional value, freshwater lobsters have a stable sales value or price throughout the year. Freshwater lobster is a crustacean commodity that is not easily stressed or easily attacked by disease. The availability of calcium is essential for lobster growth, especially the formation of its shell. This research aims to determine the effectiveness of adding calcium carbonate at different time intervals by adding 150 mg/L CaCo3 lime. The study was conducted from June to July 2020 at the Aquaculture Environmental Laboratory, Bogor Agricultural Institute. The research used a Completely Randomized Design (CRD) with five treatments and three replications. The treatment used was K+ and K-, and the time interval for adding CaCo3 was once every five days, once every ten days, and once every 15 days. The aquarium measures 100 x 50 x 51 cm with a water height of 21 cm. The lobster used measures 1.5 cm. The research results after statistical testing showed that aquarium A1 (addition of CaCo3 every five days) experienced an increase in length of 0.67 cm. Weight of 0.67 g, B1 (addition of CaCo3 every ten days) experienced an increase in length of 0.87 cm and weight of 0.78 g, C1 (addition of CaCo3 every 15 days) experienced an increase in length of 0.97 cm and weight of 0.98 g, K+1 experienced an increase in length of 1.05 cm and weight of 1.06 gr, K-1 experienced an increase in length of 0.46 cm and weight of 0.45 g. [ABSTRACT FROM AUTHOR]

The purpose of this experiment is to explore the effect of different additives on the nursing effect of young Cherax quadricarinatus. A total of 10 800 Cherax quadricarinatus. were selected and randomly divided into six groups, with three repetitions in each group and 600 Cherax quadricarinatus. in each repetition. Group 1 (control group) was fed basic feed, Group 2 was fed 70% basic feed + 30% Spirulina powder, Group 3 was fed 80% basic feed + 20% Spirulina powder, Group 4 was fed 80% basic feed + 10% Spirulina powder + 3% astaxanthin +2% linseed oil + 3% Antarctic krill oil + 2% riboflavin, Group 5 was fed 70% basic feed + 10% Spirulina powder + 6% astaxanthin + 4% linseed oil + 6% Antarctic krill oil + 4% riboflavin, and Group 6 was fed 70% basic feed + 20% Spirulina powder + 3% astaxanthin + 2% linseed oil + 3% Antarctic krill oil + 2% riboflavin. The experiment lasted for 10 days. The results showed that the survival rates of juveniles in Group 4 and Group 5 were significantly higher than those in Group 1 and Group 2 (P<0.05), with the survival rates ranking as follows: Group 4 > Group 5 > Group 3 > Group 6 > Group 2 > Group 1. Juveniles in Group 4 exhibited higher weight gain and total length increase rates, with the weight gain rates ranking as follows: Group 4 > Group 3 > Group 5 = Group 6 = Group 2 > Group 1, and the total length increase rates ranking as follows: Group 4 > Group 5 > Group 3 > Group 2 > Group 6 > Group 1. The activity of TPS, SOD, ACP, and AKP in juveniles from Group 4 was significantly higher than those in Group 1 and Group 2 (P<0.05). The results showed that Group 4 had a higher survival rate, growth rate, and immune related enzyme activities, that was, 80% basic feed +10% Spirulina powder + 3% astaxanthin + 2% linseed oil + 3% Antarctic krill oil + 2% riboflavin had better effect. [ABSTRACT FROM AUTHOR]

Crayfish are known to effectively invade freshwater systems worldwide. Whilst no native crayfish species exist in Israel, three exotic species have been documented in recent years, and their introduction details are hereby discussed. Three of these introduction events, one of each species, were previously reported; one was established, one failed to establish, and the third was successfully eradicated. However, more recently, invasive crayfish have been independently detected multiple times, involving a variety of natural and artificial habitats. Altogether, three invasive crayfish species currently inhabit Israeli freshwaters: Cherax quadricarinatus, Procambarus clarkii, and Procambarus virginalis. They were found in fourteen independent cases, and at least five of them represent established populations. Similar to other crayfish invasions around the globe, we speculate that the invasive populations in Israel result from the intentional release of aquarium inhabitants, as well as from aquaculture escapees. The import and trade policy of aquatic organisms in Israel requires thorough revision to prevent future invasions. Thought should also be given to the prevention of the spread of the existing invasive populations as well as to their eradication, if possible. [ABSTRACT FROM AUTHOR]

Cutibacterium acnes is one of the bacteria that cause acne on the face. Freshwater crayfish (Cherax quadricarinatus) shells have been abandoned and are not used by the community; thus, their shells are processed into economically valuable compounds such as chitosan. Chitosan has antibacterial characteristics that can inhibit acne bacterial development. The purpose of this study is to see if chitosan derived from crayfish shells may be stable in the form of an anti-acne gel and has antibacterial action against Cutibacterium acnes. Anti-acne gel was made from crayfish shells at concentrations of 2, 4 and 6 %, then gel formulations were evaluated and antibacterial efficacy against Cutibacterium acnes germs was tested. Chitosan produced by freshwater lobster shells was 68.75 %. The results of the test of freshwater crayfish shells against Cutibacterium acnes revealed that the average diameter of the inhibition was 6.34 mm at a concentration of 2 %, 6.57 mm at a concentration of 4 % and 6.90 mm at a concentration of 6 %; thus, a concentration of 6 % has the best inhibition. According to the organoleptic test, there was no change in shape or color. According to the homogeneity test, there are no lumps or coarse grains. According to the spreadability test, all preparations were within a 56 cm range. The adhesion test shows a satisfactory adhesion time of more than 1 s. The pH test revealed that all preparations were within the normal skin pH range, indicating that the recipe satisfied the specifications. Anti-acne gel prepared from the shell of a freshwater crayfish displays antibacterial action against Cutibacterium acnes as a cause of acne, with an inhibitory diameter of 6.11 mm at 2 % concentration, 6.8 mm at 4 % concentration and 7.11 mm at 6 % concentration. The diameter of the inhibitory zone in the positive control was 11.9 mm. [ABSTRACT FROM AUTHOR]

The growth environment significantly influences the intestinal microbiota of aquatic organisms. We investigated the composition and functional differences in the intestinal microbiota of red claw crayfish (Cherax quadricarinatus) in rice fields (RB) and ponds (PB) by 16S rDNA high-throughput sequencing technology. The results indicate that the Shannon, Simpson, Sobs, Chao1, and ACE indices of PB are all higher than those of RB, demonstrating greater diversity and richness of intestinal microbiota. The dominant phyla in the intestinal microbiota of the Cherax quadricarinatus were Proteobacteria, Tenericutes, and Firmicutes. Tenericutes and Proteobacteria were significantly more abundant in the RB than in the PB, while Planctomycetes and Firmicutes were significantly more abundant in the PB than in the RB. The results of network correlation analysis indicate that Proteobacteria and Firmicutes exhibit strong connectivity with other microbial groups in the gut microbiota of Cherax quadricarinatus, showing significant centrality. They play an important role in the interactions within the gut microbiota community. The dominant bacterial genera in the Cherax quadricarinatus’s gut were Citrobacter, Candidatus_Bacilloplasma, and Clostridium_sensu_stricto_1. The abundance of the genus Clostridium was significantly higher in the PB than in the RB, whereas the abundance of Candidatus_Hepatoplasma and Vibrio was significantly lower in the PB than in the RB. The prediction function of KEGG enrichment showed that the abundance of Amino acid metabolism, Biosynthesis of Other Secondary Metabolites, Transport and Catabolism, Cancers, and Nervous System, Substance Dependence were significantly higher in the PB, while the infectious diseases pathway was enriched in the RB. In summary, our results revealed significant differences in the composition and diversity of intestinal microbiota in the Cherax quadricarinatus between rice paddy and pond farming environments. The intestinal microbiota of the Cherax quadricarinatus grown in pond environments exhibit higher diversity and stability, manifested by an increase in beneficial bacteria abundance and a decrease in opportunistic pathogens. These findings significantly improve understanding of the complex relationship among Cherax quadricarinatus, intestinal microbiota, and the environment.

Nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs), classified as pattern recognition receptors (PRRs), play crucial roles in innate immune responses. However, research on this topic in crustaceans remains limited. In the present study, 27 NLR family members were identified and characterized based on the redclaw crayfish genome. Gene structure, conserved domain, and motif analyses revealed that these NLR genes were classified into four subfamilies with three major domains, and phylogenetic and structural analyses further confirmed their evolutionary conservation. qRT-PCR analysis showed that the relative expression levels of several NLR genes changed significantly under the DIV1 challenge. More importantly, in vivo silencing of NAWD1 gene in Cherax quadricarinatus promoted DIV1 replication . These findings, together with those of previous studies, suggest that NLR genes in crustaceans may play a key role in immune responses to viral infections.

Cherax quadricarinatus, also known as the redclaw crayfish, is native to northern Australia and southern Papua New Guinea and is an important freshwater aquaculture species in many countries. Studying the genetic structure of the current cultured population can improve the breeding plan for redclaw crayfish to better manage the hybridization and germplasm bank and promote their rational utilization; however, microsatellite resources for redclaw crayfish remain insufficient. The purpose of this study was to analyze the genetic diversity of different redclaw crayfish populations in China. After screening 18 pairs of microsatellite markers from redclaw crayfish transcriptome data, 240 samples from seven main breeding areas (Changsha, Guangzhou, Haikou, Huzhou, Jiangmen, Wuxi, and Zhanjiang) were evaluated and detected using these microsatellite markers. In total, 97 alleles were detected, of which the minimum number was two and the maximum number was twelve. The observed heterozygosity ranged from 0.258 to 0.807, with an average of 0.559, and the expected heterozygosity ranged from 0.288 to 0.815, with an average value of 0.558. The polymorphic information content values of seven populations ranged from 0.268 to 0.791, with an average of 0.511. Moreover, pairwise genetic differentiation within the population was between 0.007 and 0.031. The UPGMA clustering results showed that the Zhanjiang population stands alone on a branch, but the genetic variation between branches is very small. Meanwhile, STRUCTURE analysis further revealed that the genetic backgrounds of each population are essentially identical, with no noticeable genetic differentiation arising from geographic differences. These results provide a basic assessment of the genetic diversity of the main cultured populations of redclaw crayfish and a molecular foundation for future genetic monitoring and selective breeding research.

Aquaculture traditionally used antibiotics, leading to environmental contamination, food residue, and antibiotic-resistant superbugs. Probiotics offer a promising antibiotic alternative. In this study, a strain of Bacillus subtilis W2Z was isolated from aquaculture environments and can inhibit pathogens in aquaculture food production through chemical compounds. Eight-weeks C. quadricarinatus cultivation experiments revealed that B. subtilis W2Z, as a probiotic, contributes to increasing the yield of red claw crayfish. The supplementation of strain W2Z in the feed enhanced the crayfish's resistance to Aeromonas hydrophila by increasing immune-related enzyme activity and improving intestinal microbiota. B. subtilis W2Z has significant potential as a bioresource for exploring probiotics in crustacean aquaculture. Adding B. subtilis W2Z to C. quadricarinatus feed at a concentration of 1 × 108 to 1 × 109 colony forming unit (CFU)/g is recommended. • Isolated B. subtilis W2Z has potential as a probiotic. • Dietary supplement of B. subtilis W2Z increased the yield of red claw crayfish. • Dietary supplement of B. subtilis W2Z enhanced the immunity of red claw crayfish. • Dietary supplement of B. subtilis W2Z improved intestinal microbiota structure. [ABSTRACT FROM AUTHOR]

Serine protease inhibitors Kazal type (SPINKs) function in physiological and immunological processes across multicellular organisms. In the present study, we identified a SPINK gene, designated as CqSPINK , in the red claw crayfish Cherax quadricarinatus , which is the ortholog of human SPINK5. The deduced CqSPINK contains two Kazal domains consisting of 45 amino acid residues with a typical signature motif C-X 3 -C-X 5 -PVCG-X 5 -Y-X 3 -C-X 6 -C-X 12-14 -C. Each Kazal domain contains six conserved cysteine residues forming three pairs of disulfide bonds, segmenting the structure into three rings. Phylogenetic analysis revealed CqSPINK as a homolog of human SPINK5. CqSPINK expression was detected exclusively in hepatopancreas and epithelium, with rapid up-regulation in hepatopancreas upon V ibrio parahaemolyticus E1 challenge. Recombinant CqSPINK protein (rCqSPINK) was heterologously expressed in Escherichia coli and purified for further study. Proteinase inhibition assays demonstrated that rCqSPINK could potently inhibit proteinase K and subtilisin A, weakly inhibit α-chymotrypsin and elastase, but extremely weak inhibit trypsin. Furthermore, CqSPINK inhibited bacterial secretory proteinase activity from Bacillus subtilis, E. coli, and Staphylococcus aureus, and inhibited B. subtilis growth. These findings suggest CqSPINK's involvement in antibacterial immunity through direct inhibition of bacterial proteases, contributing to resistance against pathogen invasion. • A serine protease inhibitors Kazal type gene (CqSPINK), the ortholog of human SPINK5, was identified in Cherax quadricarinatus. • CqSPINK was expressed only in hepatopancreas and epithelium. • CqSPINK could directly inhibiting bacterial protease. • CqSPINK play a vital role in the innate immunity of Cherax quadricarinatus. [ABSTRACT FROM AUTHOR]

Background: The introduction of non-native species is a primary driver of biodiversity loss in freshwater ecosystems. The redclaw crayfish (Cherax quadricarinatus) is a freshwater species that exhibits tolerance to hypoxic stresses, fluctuating temperatures, high ammonia concentration. These hardy physiological characteristics make C. quadricarinatus a popular aquaculture species and a potential invasive species that can negatively impact tropical and subtropical ecosystems. Investigating the genomic basis of environmental tolerances and immune adaptation in C. quadricarinatus will facilitate the development of management strategies of this potential invasive species., Results: We constructed a chromosome-level genome of C. quadricarinatus by integrating Nanopore and PacBio techniques. Comparative genomic analysis suggested that transposable elements and tandem repeats drove genome size evolution in decapod crustaceans. The expansion of nine immune-related gene families contributed to the disease resistance of C. quadricarinatus. Three hypoxia-related genes (KDM3A, KDM5A, HMOX2) were identified as being subjected to positive selection in C. quadricarinatus. Additionally, in vivo analysis revealed that upregulating KDM5A was crucial for hypoxic response in C. quadricarinatus. Knockdown of KDM5A impaired hypoxia tolerance in this species., Conclusions: Our results provide the genomic basis for hypoxic tolerance and immune adaptation in C. quadricarinatus, facilitating the management of this potential invasive species. Additionally, in vivo analysis in C. quadricarinatus suggests that the role of KDM5A in the hypoxic response of animals is complex., (© 2024. The Author(s).)

Antimicrobial peptides (AMPs), which are widely present in animals and plants, have a broad distribution, strong broad-spectrum antibacterial activity, low likelihood of developing drug resistance, high thermal stability and antiviral properties. The present study investigated the effects of adding AMPs from Hermetia illucens larvae on the growth performance, muscle composition, antioxidant capacity, immune response, gene expression, antibacterial ability and intestinal microbiota of Cherax quadricarinatus (red claw crayfish). Five experimental diets were prepared by adding 50 (M1), 100 (M2), 150 (M3) and 200 (M4) mg/kg of crude AMP extract from H. illucens larvae to the basal diet feed, which was also used as the control (M0). After an eight-week feeding experiment, it was discovered that the addition of 100–150 mg/kg of H. illucens larvae AMPs to the feed significantly improved the weight gain rate and specific growth rate of C. quadricarinatus. Furthermore, the addition of H. illucens larvae AMPs to the feed had no significant effect on the moisture content, crude protein, crude fat and ash content of the C. quadricarinatus muscle. The addition of 100–150 mg/kg of H. illucens larvae AMPs in the feed also increased the antioxidant capacity, nonspecific immune enzyme activity and related gene expression levels in C. quadricarinatus , thereby enhancing their antioxidant capacity and immune function. The H. illucens larvae AMPs improved the structure and composition of the intestinal microbiota of C. quadricarinatus , increasing the microbial community diversity of the crayfish gut. Finally, the addition of 100–150 mg/kg of H. illucens larvae AMPs in the feed enhanced the resistance of C. quadricarinatus against Aeromonas hydrophila , improving the survival rate of the crayfish. Based on the aforementioned findings, it is recommended that H. illucens larvae AMPs be incorporated into the C. quadricarinatus feed at a concentration of 100–150 mg/kg. • Dietary AMPs improved the growth performance and non-specific immunity of crayfish. • Dietary AMPs effectively reduced the abundance of Proteobacteria in crayfish intestine. • Dietary AMPs enhanced the crayfish's resistance to A. hydrophila infection. [ABSTRACT FROM AUTHOR]

Cherax quadricarinatus exhibit sexual dimorphism, with males outpacing females in size specification and growth rate. However, there is limited understanding of the molecular mechanisms underlying sex determination and sex differentiation in crustaceans. To study the differences between intersex individuals and normal individuals, this study counted the proportion of intersex individuals in the natural population, collected the proportion of 7 different phenotypes in 200 intersex individuals, and observed the differences in tissue sections. RNA-seq was used to study the different changes in the transcriptome of normal and intersex gonads. The results showed that: the percentage of intersex in the natural population was 1.5 %, and the percentage of different types of intersex ranged from 0.5 % to 22.5 %; the sections revealed that the development of normal ovaries was stagnant at the primary oocyte stage when intersex individuals with ovaries were present; We screened for pathways and genes that may be associated with gonadal development and sex, including ovarian steroid synthesis, estrogen signaling pathway, oocyte meiosis, progesterone-mediated oocyte maturation, etc. Relevant genes including tra2a , dmrta2 , ccnb2 , foxl2 , and smad4. This study provides an important molecular basis for sex determination, sex-controlled breeding, and unisex breeding in red crayfish. The Cherax quadricarinatus is one of the world's most valuable freshwater economic shrimps and is sexually dimorphic. In this study, we investigated the percentage of red crayfish intersexed between males and females in natural populations, and screened for genes and pathways that may be associated with sex regulation. These findings complement our understanding of molecular differences in sex determination and gonadal differentiation in intersex individuals of the red crayfish. [Display omitted] • The proportion of intersex individuals in red crayfish is about 1.5 %, with seven different intersex phenotypes. • Ovarian development in intersex individuals with ovaries stalled at the primary oocyte cell stage. • Gonadal transcriptome analyses of red crayfish and intersex individuals screened for sexually differentially expressed genes. • The intersexed individuals functioned more differently from normal females and more closely to normal males. [ABSTRACT FROM AUTHOR]

Dietary cholesterol and lecithin are two essential nutrients for the growth and health of crustaceans. A 56-day feeding trial was carried out to evaluate the effects of dietary cholesterol and lecithin on the growth performance, antioxidant capacity, intestinal digestive enzymes, and gut microbiota of the Redclaw crayfish, Cherax quadricarinatus. The crayfish (initial average weight 11.39 ± 0.28 g) were fed with six experimental diets formulated with different contents of cholesterol (0.5% and 1%) and lecithin (1%, 2%, and 3%). No additional cholesterol (0%) and lecithin (0%) were added to the diet of the control group. Crayfish fed the diet with 0.5% cholesterol and 2% lecithin improved growth performance, antioxidant capacity, and intestinal digestive enzyme activities than crayfish fed with other diets. Survival, condition factor, hepatosomatic index, and whole-body proximate composition of crayfish were not significantly affected by different dietary cholesterol and lecithin levels. The Proteobacteria , Firmicutes , and Actinobacteria dominate the gut microbiota community of C. quadricarinatus. In diets with 0.5% cholesterol and 2% lecithin, there were more positive connections and a more complex network structure, which may reduce the risk of pathogen infection. Overall, the combination of 0.5% cholesterol and 2% lecithin in C. quadricarinatus diets was optimal. • Diets with 0.5% cholesterol and 2% lecithin improved growth performance in crayfish. • Diets with 0.5% cholesterol and 2% lecithin had more positive connections. • Optimal level of cholesterol and lecithin combination for crayfish were 0.5% and 2%. [ABSTRACT FROM AUTHOR]

Snail control in aquaculture and control of snail vectors implicated in animal and human diseases are global challenges. Potential biocontrol agents could be species of crayfish, which are known to be voracious predators of snails. However, at present, the use of crayfish as biocontrol agents is limited due to their invasive nature. A promising candidate biocontrol agent is the Australian redclaw crayfish, Cherax quadricarinatus , a key species in the aquaculture industry. However, the downside of using this species for biocontrol is that C. quadricarinatus aquaculture escapees – being highly robust, fast growing, and ferocious omnivores – have become invasive, establishing feral populations around the world. Here we suggest the production of monosex C. quadricarinatus populations that open two exciting biotechnology applications—as a possible sustainable solution for snail control and as a means to improve yields and management in crayfish aquaculture, without the inherent danger of establishing invasive populations of aquaculture escapees. In the first part of this study, C. quadricarinatus was tested as a snail eradicator. Both males and females were highly efficient in predation experiments, eliminating 89% and 98% of Thiara scabra snails, respectively. The superior efficiency of the females in the predation experiments and the possible advantage for aquaculture of all-female crayfish populations provided the rationale for the second part of the study—the development of an economically feasible and non-labor-intensive biotechnology for the production of all-female C. quadricarinatus populations. To this end, we leveraged the naturally occurring intersexuality in C. quadricarinatus populations to produce female-biased populations. Females bearing only the W sex chromosome isolated from such populations using W and Z -specific genomic markers were found to be reproductive when bred with WZ intersexuals. Resulting progenies from the above crosses were 100% female populations including 50% WW females, thus paving the way to the establishment of an all-female producing brood stock. We present a quantitative scheme that demonstrates how our approach, which does not include any genomic intervention, can be implemented both for sustainable aquaculture and to fight harmful snails damaging aquaculture, agriculture, and human health. • Cherax quadricarinatus genomic sex markers were used for genotyping. • Cherax quadricarinatus were employed as disease-carrying snails eradicators. • For the first time, Non-GMO method to produce all-female C. quadricarinatus is used. • All-female crayfish for aquaculture and biocontrol reduces the risk of invasiveness. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the potential benefits of chitosan oligosaccharide (COS) on red claw crayfish (Cherax quadricarinatus) and explore its underlying mechanisms. The crayfish were randomly divided into six groups, and the diets were supplemented with COS at levels of 0 (C0), 0.2 (C1), 0.4 (C2), 0.6 (C3), 0.8 (C4), and 1 (C5) g kg−1. Treatment with COS significantly improved the growth performance of the crayfish with a higher weight gain rate (WGR) and specific growth rate (SGR) in the C2 group compared to the C0 group. Additionally, the content of crude protein in the crayfish muscles in the C1 group was significantly higher than that of the C0 group. Regarding non-specific immunity, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and alkaline phosphatase (AKP), and the levels of expression of the genes related to immunity (SOD; anti-lipopolysaccharide factor [ALF]; thioredoxin1 [Trx1]; C -type lysozyme, [ C -LZM]; and GSH-Px) in the hepatopancreas and hemolymph increased significantly (P < 0.05) after supplementation with 0.4 g kg−1 of COS, while the content of malondialdehyde (MDA) decreased (P < 0.05). The survival rate of C. quadricarinatus increased (P < 0.05) in the C2, C3, C4, and C5 groups after the challenge with Aeromonas hydrophila. This study found that COS has the potential to modulate the composition of the intestinal microbiota and significantly reduce the abundance of species of the phylum Proteobacteria and the genera Aeromonas and Vibrio in the gut of C. quadricarinatus, while the abundance of bacteria in the phylum Firmicutes and the genus Candidatus _Hepatoplasma improved significantly. This study suggests that the inclusion of COS in the diet of C. quadricarinatus can enhance growth, boost immunity, and increase resistance to infection with A. hydrophila , especially when supplemented at 0.4–0.8 g kg−1. • Dietary COS improved growth performance and immunity of crayfish. • Dietary COS increased crude protein content in muscle. • Dietary COS reduced the abundance of Aeromonas and Vibrio in intestine. • Dietary COS enhanced resistance against A. hydrophila infection. [ABSTRACT FROM AUTHOR]