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This study aimed to investigate the effects of physical mutagenesis on the development and adaptive traits of early-stage shrimp larvae and to explore the feasibility of increasing genetic diversity and utilizing genetic variation in breeding populations through mutation technology. Atmospheric and room-temperature plasma (ARTP) mutagenesis technology was used to perform batch mutagenesis on fertilized eggs (gastrula stage) of four different families (A, B, C, and D) of Penaeus vannamei at the same power (360 W) and different times (2, 4, 8, and 12 min). Hatching rates, limb bud stage hatching deformity rates, survival rates, metamorphosis rates, and indicators of juvenile shrimp hypoxia tolerance and ammonia nitrogen stress were analyzed.The experimental results showed that all groups except for the 2 min mutation group showed hatching deformity rates significantly higher than those of the control group for the A and D families (P < 0.05). The deformity rate of each treatment group showed no significant differences from that of the control group in Family B. The malformation rate for Family C in the 8 min mutation treatment group was significantly higher than that in the control group. However, there was no significant difference between the 2 and 4 min treatment groups. In all four families, the hatching rate of fertilized eggs decreased with an increase in mutation time, and when the mutation time was greater than or equal to 4 min, the hatching rates of all four families were less than 15%. Compared with that of the control group, all treatment groups of the families except for the 2 min mutation group from Family A showed a significant decrease in hatching rate (P < 0.05). The hatching rate of the 2 min group for families A, B, C, and D was significantly higher than that of the 4, 8, and 12 min mutation groups, and the hatching rate of the 4 min mutation group from Family B was significantly higher than that of the 8 min mutation group (P < 0.05). The hatching and limb bud stage hatching deformity rates were moderately and highly correlated with mutagenic time, respectively.Compared with the control group, the survival rates of families A, B, C, and D in the same treatment group at the same stage showed no significant differences. The survival rate of the 8 min mutation group from Family A was significantly reduced (P < 0.05), that of the 4 and 8 min mutation groups from Family C was significantly increased, and that of the 2 and 4 min mutation groups from Family D was significantly reduced relative to the control value, whereas that of the 8 min group from Family D was significantly increased. Considering Family A as an example, metamorphosis rates in each stage were analyzed. The metamorphosis rates of the control group and the 2 min mutation group showed a significant decreasing trend during the three stages of larval development (P < 0.05); however, the metamorphosis rate in the M–P stage was significantly lower than that in the N–Z and Z–M stages. The metamorphosis rate in the Z–M stage of the 4 min and 12 min groups was significantly lower than that during the N–Z and M–P stages, whereas the metamorphosis rate during the N–Z stage of the 8 min group was significantly lower than that of the Z–M stage. After low-dose (0 and 2 min) mutagenesis of fertilized eggs of P. vannamei, the peak period of death mainly occurred in the late stage of larval development. The peak period of larval death after relatively high doses of mutagenesis (4, 8, and 12 min) mainly occurred in the middle or early stages of larval development. The peak period of death varied among different treatment groups. The results caused by radiation treatment showed directionality, and this trend of peak mortality was similar between all families.Hypoxia tolerance and ammonia-nitrogen stress testing in Family A of juvenile shrimp revealed that almost all shrimp in the 4, 8, and 12 min groups died after 5.5 h of hypoxia stress. In contrast, the control group died after 9 h of stress, and the 2 min group died after 10 h of stress. The results indicate that low doses of radiation (2 min) may improve hypoxia tolerance to some extent. The survival rates of the 2 min and 8 min groups were highest on the fourth and seventh days of the ammonia nitrogen stress experiment, respectively. Mutation had a certain impact on the ability of larvae in Family A to resist ammonia-nitrogen stress.The experimental results suggest that ARTP induced the mutation of fertilized P. vannamei eggs with non-directional changes in adaptive traits. These findings suggest the feasibility of novel methods for creating new germplasms and preparing functional research materials for P. vannamei and provide basic data and a scientific basis for the mutagenic breeding of P. vannamei.

The Pacific white shrimp or white leg shrimp, Penaeus vannamei, is native to the tropical coastal regions of Central and South America. It is one of the three major shrimp species with high production worldwide. It was brought from Hawaii, USA, in 1988 and introduced into China. It has been widely promoted and cultivated due to its adaptability to the environment, fast growth rate, and suitability for high-density industrial farming. As of 2022, China's total production of P. vannamei reached 2.09 million tons, accounting for > 90% of the country's total shrimp farming production. It has become one of the pillar industries in China's aquaculture sector.With the continuous expansion of aquaculture, diseases are becoming increasingly severe. Among them, acute hepatopancreatic necrosis disease (AHPND) hinders the development of the global shrimp farming industry and causes catastrophic economic losses. After infection, most shrimp show hepatopancreatic enlargement, which appears pale white or light yellow. In the later stages of infection, some diseased shrimp may exhibit atrophy of the hepatopancreas, appearing reddish-brown and blackened, with a hardened texture. Within 20–30 d after infection, death can occur, with a mortality rate of up to 90%. As of 2021, the economic losses caused by this disease to the major P. vannamei farming areas (China, Malaysia, Thailand, Vietnam, and Mexico) have exceeded 43 billion US dollars. Cultivating novel P. vannamei germplasm with AHPND resistance is an effective way to solve AHPND.Recently, domestic researchers have established independent shrimp breeding systems and cultivated 12 novel P. vannamei strains, such as "Hai Xing Nong No.2", "Ren Hai No.1", and "Zheng Jin Yang No.1". These varieties mainly target traits such as growth, resistance to white spot syndrome virus, farming survival rate, and temperature, salinity, and ammonia nitrogen tolerance. However, no reports of novel varieties specifically targeting AHPND resistance are available. Growth traits are essential economic traits in the genetic breeding of aquatic animals. Among the 12 novel P. vannamei varieties in China, 11 have excellent traits related to growth. Evaluating the genetic relationship between growth and AHPND resistance in the core breeding population of P. vannamei is important for fully utilizing existing high-quality germplasm and breeding novel varieties with composite traits and AHPND resistance.Genetic parameters reflect the genetic variation of target traits in a breeding population and are important references for breeding decisions. Due to the complex genetic background of existing P. vannamei germplasm resources in China, genetic parameters are influenced considerably by the tested population, infection methods, and other factors. Before breeding, stable infection tests must be conducted on the base population and obtain accurate parameters.This study used two independently bred P. vannamei strains as research objects to test their growth and AHPND resistance. Among them, 40 families were selected for high resistance (20 individuals per family, total 800 experimental individuals), and 30 families were selected for fast growth (32 individuals per family, total 960 experimental individuals). The test was conducted at P70–P90 by feeding with VpAHPND quantitative oral infection. Feeding with toxic bait was stopped after 50% of the experimental individuals died. The genetic heritability and correlation of the weight, individual survival time after VpAHPND infection, and half-lethal survival rate of the two strains were evaluated using individual animal and male and female threshold models. The results showed that the weight heritability estimate of the highly resistant strain was 0.599±0.120, indicating a high level of genetic heritability. The heritability estimates of survival time and half-lethal survival rate were 0.240±0.072 and 0.173±0.051, respectively, indicating a moderate to low level of genetic heritability, and all significantly different from 0 (P < 0.01). The weight heritability estimate of the fast-growth strain was 0.266±0.082, indicating a low level of genetic heritability. The heritability estimates of survival time and half-lethal survival rate were 0.374± 0.096 and 0.257±0.048, respectively, indicating a moderate level of genetic heritability, and all significantly different from 0 (P < 0.01). The genetic correlation between weight and AHPND resistance traits (survival time and half-lethal survival rate) in both strains showed a low positive correlation (0.061–0.235), and no significant difference was observed from 0 (P > 0.05). The genetic correlation between survival time and half-lethal survival rate in both strains was highly positively correlated, with estimates of 0.997±0.129 and 0.967±0.044, respectively. The results indicate that growth and AHPND resistance can be included as selection indicators in the comprehensive selection index for breeding and seed production in the actual breeding process. Under limited conditions, the infection program can be simplified, and the half-lethal survival rate can be used as the AHPND resistance indicator for the breeding population. This study provides a primary reference for utilizing existing germplasm resources to develop high-quality P. vannamei strains for growth and AHPND resistance breeding.

In a preliminary study conducted in our laboratory, the parkin co-regulated gene (PACRG) was identified as a candidate for white spot syndrome virus (WSSV) resistance using a genome-wide association approach. PACRG is genetically closely linked to the Parkinson´s disease-associated gene parkin, both of which are regulated by a bidirectional promoter. The PACRG and parkin genes have been found to interact with each other, associate with autophagy, and participate in cellular protection. Therefore, the functions of PACRG and parkin in WSSV resistance in Penaeus vannamei were investigated. The mRNA and amino acid sequences were analyzed, and the expression levels in shrimp infected with WSSV at different times and tissues were detected by real-time PCR. Spatial localization was performed using fluorescence in situ hybridization. PCR and Sanger sequencing were employed to obtain single nucleotide polymorphisms (SNPs) and conduct an association analysis of these SNPs with resistance to WSSV. Our findings illustrated that the complete open reading frame (ORF) sequence of PACRG was 600 bp, encoded 199 amino acids, and was predicted to contain the ParcG structural domain. The complete sequence of parkin mRNA was 2, 329 bp, comprising a 1, 653 bp ORF, 100 bp 5′-untranslated region (UTR), and a 576 bp 3′-UTR, encoding 550 amino acids. Parkin is predicted to contain UBQ and IBR structural domains and a signal peptide structure. Amino acid sequence alignment and phylogenetic tree analysis showed that the homology of PACRG between P. vannamei and Penaeus japonicus was the highest at 89.70% similarity. The phylogenetic relationship of P. vannamei was the closest to Penaeus chinensis and P. japonicus. Thus, PACRG may exhibit high evolutionary conservation. The parkin homology between P. vannamei and P. chinensis was the highest, with a similarity of 93.45%. It has been speculated that the parkin protein exhibits a high degree of evolutionary conservation. Herein, real-time PCR results suggested that PACRG and parkin were expressed in the hepatopancreas, gill, muscle, and eyestalk of healthy P. vannamei, with no significant difference. Following the challenge with WSSV, the PACRG and parkin expression levels in the hepatopancreas, gill, muscle, and eyestalk of P. vannamei were significantly altered. Post-WSSV infection for 48, 96, 192, and 228 h, the PACRG and parkin expression levels in the hepatopancreas of P. vannamei were significantly downregulated. At 48, 72, 96, 144, 192, and 228 h post-WSSV infection, PACRG expression in the gill of P. vannamei were significantly downregulated. However, at 48, 96, and 228 h post-WSSV infection, the parkin expression levels in the gill of P. vannamei were significantly upregulated. Post-WSSV infection at 96, 192, and 228 h, the PACRG and parkin expression levels in P. vannamei muscle were significantly upregulated. Post-WSSV infection, PACRG and parkin exhibited similar expression patterns in the eyestalk. The location of PACRG mRNAs mostly overlapped with the WSSV replication site in the shrimp muscle, suggesting that PACRG plays a functional role in the interaction between P. vannamei and WSSV. Two SNPs were identified within the ORF of the PACRG, One SNP was identified within the ORF of parkin, and one SNP was identified in the UTR of parkin. After conducting association analyses of these SNPs with WSSV resistance, SNPs located in the UTR of parkin-specific SNP3, SNP4, SNP5, SNP7, and SNP9 were significantly associated with resistance to WSSV. This study provides a theoretical reference for future research on the molecular mechanisms underlying P. vannamei's resistance to WSSV.

Penaeus vannamei, also known as white foot shrimp, is globally one of the three high-yield shrimp farming varieties. The wild species is found along the Pacific coast of South America. Since 1988, China has introduced P. vannamei. Due to its strong environmental adaptability, high feed conversion rate, fast growth rate, and high tolerance to ammonia nitrogen and nitrite, it has been widely promoted in aquaculture. By 2021, the aquaculture output of P. vannamei in China reached 1.977 million tons, accounting for approximately 37% of the world's total production, and has extremely high economic value.Growth traits are among the most important economic factors in the production of P. vannamei. With the intensive development of shrimp farming and degradation of germplasm, the white spot syndrome virus (WSSV) is a serious disease faced by the global shrimp industry. The infection can cause symptoms such as reduced food intake, enlarged liver and pancreas, pale red body color, and white spots on the head and chest armor in shrimp, resulting in widespread death.At present, China has cultivated 12 new varieties of P. vannamei, which to some extent alleviates its dependence on imports for high-quality P. vannamei. However, the excellent traits of domestic shrimp species are singular, and cultivating new varieties of P. vannamei with fast growth and strong disease resistance is an urgent demand in the market. Genetic parameter evaluation is the fundamental work of selection breeding. Heritability reflects the genetic variation in traits in the breeding population, which is of great significance in the development of a selection index, prediction of selection response, comparison of selection methods, selection breeding planning, and other breeding processes. There are different degrees of genetic correlation among various quantitative traits of shrimp, and genetic correlation coefficients are important for selecting target traits. The estimation of genetic correlation can be used to develop a comprehensive selection index and breeding program of multiple traits, which can improve the selection efficiency and breed better varieties with multiple traits. The higher the genetic correlation between traits, the better the effect of indirect selection. The estimation of genetic parameters is greatly affected by the test population, breeding management, analysis methods, and other factors. To ensure the accuracy of multi-trait composite breeding for growth and WSSV resistance, accurate evaluation of growth and WSSV resistance needs to be carried out for specific breeding populations. There are two commonly used target traits for measuring WSSV resistance in P. vannamei: individual survival time after infection and half-lethal survival rate (SS50) of families. In practice, measuring the half-lethal survival rate of families is more convenient. However, the correlation between these two traits has not yet been reported.To promote the growth and WSSV resistance of P. vannamei, 59 families (1, 770 individuals) were tested for WSSV infection. We recorded the survival time and individual body length of shrimp after infection and analyzed the mean, standard deviation, maximum and minimum values, and coefficient of variation of half-lethal survival rate and test traits for each line. The heritability and genetic correlation coefficients of growth, survival time, and half-lethal survival rate were calculated. Variance components and genetic parameters for growth and survival traits were estimated using a two-trait animal model and a sire-dam threshold model. The genetic parameters of body length were corrected by including age as a covariate. The genetic parameters of WSSV survival time were corrected by including body length as a covariate. The estimated heritability of body length was medium (0.17±0.05), and the estimated heritabilities of survival time and half-lethal survival rate were medium (0.18±0.05 and 0.14±0.05). Further, the estimated heritabilities of the three traits were significantly different from zero (P < 0.01). The genetic correlation between body length and survival time and that of body length and half-lethal survival rate were low (0.15±0.20 and 0.25±0.22). There were no significant differences between the genetic correlations and zero (P > 0.05). The genetic correlation between survival time and half-lethal survival rate was high (0.96±0.03). There was no significant difference between the genetic correlation and one (P > 0.05). The results showed that a comprehensive selection index of growth and WSSV resistance of P. vannamei can be established to carry out multi-trait composite breeding. In this breeding population, the growth and WSSV resistance of P. vannamei can be combined with multiple traits according to the breeding requirements, and the comprehensive selection index can be formulated by assigning values. In addition, to optimize the breeding of each generation, the half-lethal survival rate of WSSV can be used as an indicator of WSSV resistance. This study provides basic data and theoretical support for breeding varieties of P. vannamei with excellent growth and WSSV resistance.

The research on the mining stability and deformation mechanism of the overlying accumulation layer on the gently inclined bedding slope, especially from the perspective of coordinating the exploitation of underground resources and the safety protection of ancient buildings on the ground is in the exploratory stage. Taking the accumulation layer of Baoyingsi slope in Shanxi Province as the research object, based on the analysis of surface dynamic monitoring and geological process mechanism, combined with numerical simulation, the stability of accumulation layer and the formation mechanism of surface cracks were studied, and the mining method was discussed and optimized. The research shows that: ① Long-wall underground mining is the cause of the deformation of the accumulation layer, and the weak characteristics of the accumulation layer and the soft and hard interbedded structure of the slope are the internal causes of its deformation. The deformation mode of the bedrock under the accumulation layer is vertical extrusion and horizontal tension, which has an amplification effect on the deformation of the accumulation layer and affects the generation of ground cracks. The deformation and failure mechanism of the accumulation layer is as follows: mining under the slope-bending of overburden rock-toppling deformation of side rock-stress concentration of underlying rock-pulling and cracking; ② The cracks in the accumulation layer are distributed near the end of the working face of the goaf in the uphill direction, and are approximately parallel on the plane, showing a zigzagging motion or serrated shape. The number of ground fissures is more than that of surface fissures, but the scale is smaller. The temple buildings are affected by the hidden tensile ground fissures, which cause the deformation of the foundation and cause the cracking of the above-ground structure. During the monitoring period after stopping mining, the deformation rate of the accumulation body tends to converge, the residual deformation is reduced, and the deformation movement is basically stable. ③ After complete mining, the accumulation layer shows tensile deformation dominated by the following dislocations, and shear strain appears. The deformation degree of the accumulation layer will be aggravated under continuous mining conditions. The maximum principal stress increment of the underlying bedrock is 1080.75 %, and the tensile stress is concentrated. ④ Short-wall room mining leaving section coal pillar is beneficial to reduce the deformation of accumulation layer.The research conclusions provide a reference for understanding the deformation and failure of the overlying accumulation layer on the slope disturbed by underground resource mining and seeking solutions for the protection of cultural relics in coal mining under ancient buildings.

In recent years, the slope of the bottom plate of the underground reservoir in the loose porous medium constructed in the middle and upper reaches of the river is relatively large, which makes the underground water surface incline to a certain slope as a whole, near-horizontal section will appear in front of the underground dam during continuous recharge. Given this situation, the definition and calculation of the characteristic index of the underground reservoir in line with the actual changes are carried out. The characteristic water level of the underground reservoir is defined based on the groundwater surface with a certain slope at the inclined level in the case of the lower dam (single dam) impoundment. The characteristic capacity is calculated through the water level at the typical section defined by the inclined surface. A new set of definition and calculation method based on the characteristic index of the underground reservoir with a dam on the inclined bottom plates is proposed and applied to the Rushan River underground reservoir, which more accurately reflects the water level change and the corresponding actual reservoir capacity during the operation of the underground reservoir. HIGHLIGHTS ·The research results can be applied to determine groundwater reservoirs’ characteristic water surface, characteristic reservoir capacity.; The research results put forward a concept of water surface–reservoir capacity relationship with inclined bottom plates.; The research results provide a set of improved storage capacity calculation methods for underground reservoirs.;

Penaeid shrimp, with its genomes enriched in short tandem repeats (STRs), presents an ideal model for studying the distribution and biological functions of STRs. In this study, we systematically identified and compared STRs across multiple species, confirming a significantly higher prevalence of STRs (26–32%) in penaeid shrimp, which is markedly higher than that observed in other species, such as mammals (1.3–2.1%) and plants (0.21–0.73%). Further analysis utilizing a cohort of 326 Pacific white shrimp revealed a total of 672,507 high-quality STRs evenly distributed across the genome, with a notably lower frequency of SNPs within these STR regions. Focusing on growth traits as a case study, we conducted a genome-wide association study (GWAS) and correlation analyses to identify the regulatory relationship of STRs on complex traits. We discovered 84 STRs that showed a significant association with body weight. Interestingly, eleven of these STRs, with 81% being composed of an A/T base, showed a significant linear correlation with body weight, revealing the key role of A/T-related STRs in shrimp weight regulation. For instance, a significant association and a negative correlation were found between the copy number of the STR [(A)n] at NW_020872788.1:580574 and body weight. The cytokinesis protein 7-like (LOC113800912) gene, which contains this STR in its splice region, exhibits differential expression associated with body weight variation. These findings introduce a model for STR copy number regulation in non-human species, illuminating the influence of STRs on growth traits. It offers a valuable framework for investigating complex traits and the biological functions of STRs in agricultural animals.

C-type lectins are known for agglutination activity and play crucial roles in regulating the prophenoloxidase (proPO) activation system, enhancing phagocytosis and encapsulation, synthesizing antimicrobial peptides, and mediating antiviral immune responses. This work cloned a C-type lectin, ladderlectin (LvLL), from Litopenaeus vannamei. LvLL comprised a 531 bp open reading frame (ORF) that encoded 176 amino acids. The predicted LvLL protein included a signal peptide and a CLECT domain. LvLL was predicted to feature a transmembrane region, suggesting it may be a transmembrane protein. LvLL was predominantly expressed in the shrimp’s hepatopancreas. After WSSV infection, LvLL expression in the hepatopancreas increased significantly by 11.35-fold after 228 h, indicating a general upregulation. Knockdown of LvLL resulted in a significant decrease in WSSV viral load and a notable increase in shrimp survival rates. Additionally, knockdown of LvLL led to a significant downregulation of apoptosis-related genes Bcl-2 and caspase 8 and a significant upregulation of p53 and proPO in WSSV-infected shrimp. This study showed that LvLL played a vital role in the interaction between L. vannamei and WSSV.

This study investigates the thermal–hydraulic behavior and deposition characteristics of a shell and tube exhaust heat exchanger using a CFD-based predictive model of soot deposition. Firstly, considering the influences of thermophoretic, wall shear stress, and other deposition and removal mechanisms, a predictive model is developed for long-term performance of heat exchangers under soot deposition. Then, the variations in exhaust heat exchanger performance during a 4 h deposition period are simulated based on the model. Subsequently, the variation of deposition distribution and different deposition velocities are also evaluated. Finally, an analysis of the long-term performance of the exhaust heat exchanger under varying gas velocities and temperature gradients is conducted, revealing the performance variations under all engine-operating conditions. Results show that the deterioration in normalized relative j/f1/2 varies from 5.26% to 24.91% under different work conditions, and the exhaust heat exchanger with high gas velocity and low temperature gradient exhibits optimal long-term performance.

Aberrant expression of the heat shock proteins and factors was revealed to be closely associated with male reproduction. Heat shock factor 2 (HSF2) is a transcription factor that is involved in the regulation of diverse developmental pathways. However, the role and the corresponding molecular mechanism of HSF2 in male cattle-yak sterility are still poorly understood. Therefore, the aim of this study was to obtain the sequence and the biological information of the cattle-yak HSF2 gene and to investigate the spatiotemporal expression profiles of the locus during the development of cattle-yak testes. Additionally, the differential expression was analyzed between the cattle-yak and the yak, and the methylation of corresponding promoter regions was compared. Our results showed an additional 54 bp fragment and a missense mutation (lysine to glutamic acid) were presented in the cattle-yak HSF2 gene, which correlated with enriched expression in testicular tissue. In addition, the expression of the HSF2 gene showed dynamic changes during the growth of the testes, reaching a peak in adulthood. The IHC indicated that HSF2 protein was primarily located in spermatocytes (PS), spermatogonia (SP), and Sertoli cells (SC) in cattle-yak testes, compared with the corresponding cells of cattle and the yak. Furthermore, bisulfite-sequencing PCR (BSP) revealed that the methylated CpG sites in the promoter region of the cattle-yak HSF2 were more numerous than in the yak counterpart, which suggests hypermethylation of this region in the cattle-yak. Taken together, the low expression abundance and hypermethylation of HSF2 may underpin the obstruction of spermatogenesis, which leads to male cattle-yak infertility. Our study provided a basic guideline for the HSF2 gene in male reproduction and a new insight into the mechanisms of male cattle-yak sterility.

Temperature is an important environmental factor that affects the growth, development, and metabolism of shrimp. High temperatures tend to cause a decrease in the immunity and production performance of shrimp, resulting in a significant increase in shrimp disease and mortality. Based on transcriptome sequencing data, we screened for the involvement of DNA damage-inducible transcript 4 like (ddit4l) in the temperature stress process of Litopenaeus vannamei. Ddit4l (also known as Redd2 and Rtp801L) is involved in regulating cell survival, proliferation, and apoptosis by affecting DNA damage repair factors, hypoxia-inducible factors, and other signaling pathways when stimulated by DNA damage, hypoxia, ischemia, and oxidative stress, among others. Ddit4l may be an important transducer of pathological stress in autophagy through mammalian target of rapamycin (mTOR) signaling. Autophagy is a process in which cells use lysosomes to degrade their own damaged organelles and macromolecules, and the process plays an important role in maintaining the balance of protein metabolism and the stability of the intracellular environment, promoting cell growth and development. An important regulator of autophagy is the mTOR, which responds to various stimuli, such as growth factors, cellular energy status, oxygen concentrations, and stress, to regulate cell metabolism and growth. Ddit4l and its homolog ddit4 are upstream mTOR inhibitors in several tissues and cell models. We set up sudden temperature change and gradual temperature change experiments to induce a stress response in L. vannamei. In the gradual change experiment, the water temperature was increased from 26℃ to 38℃ at a rate of 4℃ per day, and cooled back to 26℃ at the same rate. Two individuals were randomly selected from each of the three parallel experiments in the experimental group at each time point. The eyestalk, gill, hepatopancreas, nerve, and muscle were used for subsequent RNA extraction and gene expression quantification. RNA quality and concentration were also examined. The partial ddit4l cDNA (complete ORF and partial UTR) of L. vannamei was obtained directly by PCR amplification to evaluate the structure and function of the Lv-ddit4l gene. The Lv-ddit4l sequence contained a 495 bp open reading frame, encoding 164 amino acids, with a molecular weight of 18.51 kDa, and an isoelectric point of 5.35. The instability index was 65.83, which classifies the protein as unstable. Lv-ddit4l contains a highly conserved RTP801-C domain. BLAST alignment and phylogenetic tree analysis showed that the Lv-ddit4l gene had 59.76% similarity with the Chionoecetes opilio ddit4l gene, and first clustered with C. opilio. A real-time RT-PCR confirmatory experiment considered three parallel groups for each sample with 18S rRNA as the reference gene. Relative gene expression was analyzed using the 2–ΔΔCt method. Quantitative analysis of gene expression levels showed that Lv-ddit4l was widely expressed in all of the examined tissues, with similar expression levels at 26℃. When the temperature was increased gradually from 26℃ to 32℃, the Lv-ddit4l gene in the eyestalk was significantly increased (P < 0.05), and was 10.37 times higher than that in the control (A-26℃). Therefore, this gene is hypothesized to respond to temperature changes in the eyestalk of L. vannamei. The expression of Lv-ddit4l in the eyestalk, gills, hepatopancreas, nerves, and muscles did not change significantly when the water temperature was gradually increased to the highest temperature of 38℃; it is speculated that this gene may play a role in pre-heat stress. When the temperature was gradually cooled from 38℃ to 32℃, the expression of Lv-ddit4l increased significantly in the gill and hepatopancreas (P < 0.05), which were respectively 3.37 and 2.03 times higher than that of the control group (A-26℃). There was no significant difference in gene expression under different levels of gradual changes in temperature stress in the nerve and muscle. The expression in the gill, hepatopancreas, and nerve was significantly up-regulated (P < 0.05) at a sudden change in water temperature to 36℃ for 10 min, and the change in expression in the hepatopancreas was 24.06 times higher than that in the control group (A-26℃). Gene expression in the gills and nerves was 1.22-fold and 3.67-fold higher than that in the control (A-26℃), respectively. When the water temperature was increased to 36℃ suddenly for 24 h, Lv-ddit4l gene expression increased significantly in the muscle (P < 0.05). Lv-ddit4l showed significant up-regulation of expression in the gill, hepatopancreas, nerve, and muscle with sudden changes in temperature, suggesting that this gene may play a role in the stress induced by sudden increases in temperature. When the temperature was restored from 38℃ and 36℃ to 26℃, the expression of the Lv-ddit4l gene was downregulated in L. vannamei. The above results indicate that Lv-ddit4l is associated with the response to high-temperature stress.

White spot disease (WSD) outbreaks pose a significant threat to the Pacific white shrimp (Litopenaeus vannamei) farming industry. The causative agent is the white spot syndrome virus (WSSV). There are no effective treatments for WSD so far. Therefore, understanding the resistance mechanisms of L. vannamei against the WSSV is crucial. C-type lectins (CTLs) are important pattern recognition receptors (PRRs) that promote agglutination, phagocytosis, encapsulation, bacteriostasis, and antiviral infections. This study cloned the C-type lectin domain family 4 member F (LvCLEC4F) from L. vannamei. LvCLEC4F contains a 492 bp open reading frame (ORF) encoding a protein of 163 amino acids, including a carbohydrate recognition domain (CRD). Following a challenge with the WSSV, the expression profile of LvCLEC4F was significantly altered. Using RNA interference (RNAi) technology, it was found that LvCLEC4F promotes WSSV replication and affects the expression levels of genes related to the regulation of apoptosis, signaling and cellular stress response, and immune defense. Meanwhile, the hemolymph agglutination phenomenon in vivo was weakened when LvCLEC4F was knocked down. These results indicated that LvCLEC4F may play an important role in the interaction between L. vannamei and WSSV.

To explore the performance differences among offspring obtained by the intra- and inter-strain crosses, strain A with outstanding WSSV resistance and strain B with outstanding growth of Litopenaeus vannamei were used to construct four experimental groups in a complete diallel cross. 27 growth-related phenotypic traits and WSSV resistance represented by the surviving hours post-infection were obtained via the growth and the virus challenge test. Mixed linear model along with physical pedigree were utilized to calculate the least squares means, correlations, heritability and heterosis. The results showed that crossbreeding can realize character complementation of advantage strain. The performance of WSSV resistance was ranked AA> BA> AB> BB, and the reciprocal crosses performed significantly better than intra-strain group BB. Most growth-related traits in two reciprocal cross groups were also significantly better than those in AA group. Comparisons between the two reciprocal crosses showed that BA cross was better than AB in terms of WSSV resistance and growth. Heterosis of WSSV resistance in BA cross was 5.74∼10.18% greater than that in AB, meanwhile the absolute weight gain rate of BA cross was 4.83% higher than that of AB. The heritability estimates of body length and body weight were 0.0278 and 0.339, both of which reached medium level. The genetic and phenotypic correlations among growth-related traits were from 0.36 to 0.99 and 0.32 to 0.99, respectively. In term of WSSV resistance, the heritability estimate was 0.135 ± 0.082. The genetic and phenotypic correlations between WSSV resistance and growth-related traits were from − 0.034 to − 0.573 and − 0.001 to − 0.202, respectively. The results showed that hybrid offspring obtained by crossing female parents with outstanding WSSV resistance and male parents with outstanding growth culminated in a superior heterosis in both traits. This study provides basic reference data for L. vannamei breeding of new strains that are disease resistant and fast-growing.

The relationship between inbreeding and traits of disease resistance in shrimp has not been studied comprehensively. To explore the effect of inbreeding on white spot syndrome virus (WSSV) resistance in Fenneropenaeus chinensis, we established F. chinensis “Huanghai No. 5” populations with different inbreeding coefficients. We infected F. chinensis individuals with WSSV to compare WSSV-resistance between five inbred groups and a control group. Survival time, survival rate, distribution of deaths, and cumulative mortality rate were analyzed. A mixed linear model was established based on the acquired data. The viral load in muscle tissue of F. chinensis of 12 families from the five inbred groups and the control group was determined at different time points via real-time PCR. The average survival and longest survival time of the inbred groups were lower than those of the control group, and the coefficient of variation was universally greater than that of the control group. The least squares means of survival time of the five inbred groups (F0.1325, F0.25, F0.3125, F0.375, F0.5) were 118.96 115.14, 124.58, 123.97, and 101.34 h, respectively, which were 10.28%, 13.16%, 6.04%, 6.5%, and 23.57% lower than that of the control group. Further, when the inbreeding coefficient increased by 10%, WSSV infection survival time was changed by − 7.76%, − 5.26%, − 1.93%, − 1.73%, and − 4.71% for the five inbred groups, respectively. Thus, the results indicated that inbreeding enhanced the susceptibility of F. chinensis to WSSV infection, and the resistance of F. chinensis to WSSV declined as the inbreeding coefficient values increased, consequently, resulting in greater population dispersion, intensified differentiation, and instability of resistant phenotypes. In conclusion, we elucidated the effect of inbreeding on F. chinensis resistance to WSSV infection and established a theoretical basis to conduct further research in the future.

The combined effect of ε-polylysine (PL) and modified atmosphere packaging (MAP; 60% CO2/40% N2) on the bacterial community of greater amberjack filets and their physicochemical properties was evaluated at 4°C. The total viable counts (TVC), psychrotrophic bacterial count, sensory index, texture analysis, and total volatile basic nitrogen (TVB-N) revealed that PL, MAP, and MAP + PL treatment delayed the deterioration of greater amberjack filets. These treatment groups also showed decreased accumulation of biogenic amines. High-throughput 16S rRNA gene sequencing results indicated that these treatments suppressed the growth of Pseudomonas in greater amberjack filets. Furthermore, the MAP + PL treatment group was observed to be more effective than the PL and MAP groups, extending the shelf life of greater amberjack filets by 6 days. This investigation showed that the combination of PL and MAP has the potential to retain the quality and extend the shelf life of greater amberjack.

Long-chain fatty acyl-CoA synthase 1 (ACSL1) plays a vital role in the synthesis and metabolism of fatty acids. The proportion of highly unsaturated fatty acids in beef not only affects the flavor and improves the meat’s nutritional value. In this study, si-ACSL1 and NC-ACSL1 were transfected in bovine preadipocytes, respectively, collected cells were isolated on the fourth day of induction, and then RNA-Seq technology was used to screen miRNAs related to unsaturated fatty acid synthesis. A total of 1,075 miRNAs were characterized as differentially expressed miRNAs (DE-miRNAs), of which the expressions of 16 miRNAs were upregulated, and that of 12 were downregulated. Gene ontology analysis indicated that the target genes of DE-miRNAs were mainly involved in biological regulation and metabolic processes. Additionally, KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis identified that the target genes of DE-miRNAs were mainly enriched in metabolic pathways, fatty acid metabolism, PI3K-Akt signaling pathway, glycerophospholipid metabolism, fatty acid elongation, and glucagon signaling pathway. Combined with the previous mRNA sequencing results, several key miRNA-mRNA targeting relationship pairs, i.e., novel-m0035-5p—ACSL1, novel-m0035-5p—ELOVL4, miR-9-X—ACSL1, bta-miR-677—ACSL1, miR-129-X—ELOVL4, and bta-miR-485—FADS2 were screened via the miRNA-mRNA interaction network. Thus, the results of this study provide a theoretical basis for further research on miRNA regulation of unsaturated fatty acid synthesis in bovine adipocytes.

Viral covert mortality disease (VCMD), also known as running mortality syndrome (RMS), is caused by covert mortality nodavirus (CMNV) and has impacted the shrimp farming industry in Asia and Latin America in recent years. The pathogenic mechanism of CMNV infecting Penaeus vannamei was investigated in this study. In the naturally infected shrimp, histopathological and in situ hybridization (ISH) analysis verified that CMNV infection and severe cellar structural damage occurred in almost all cells of the ommatidium. Under transmission electron microscopic (TEM), vacuolation and necrosis, together with numerous CMNV-like particles, could be observed in the cytoplasm of most cell types of the ommatidium. The challenge test showed that a low CMNV infectious dose caused cumulative mortality of 66.7 ± 6.7% and 33.3 ± 3.6% of shrimp in the 31-day outdoor and indoor farming trials, respectively. The shrimp in the infection group grew slower than those in the control group; the percentage of soft-shell individuals in the infection group (42.9%) was much higher than that of the control group (17.1%). The histopathological and ISH examinations of individuals artificially infected with CMNV revealed that severe cellar damage, including vacuolation, karyopyknosis, and structural failure, occurred not only in the cells of the refraction part of the ommatidium, but also in the cells of the nerve enrichment and hormone secretion zones. And the pathological damages were severe in the nerve cells of both the ventral nerve cord and segmental nerve of the pleopods. TEM examination revealed the ultrastructural pathological changes and vast amounts of CMNV-like particles in the above-mentioned tissues. The differential transcriptome analysis showed that the CMNV infection resulted in the significant down-regulated expression of genes of photo-transduction, digestion, absorption, and growth hormones, which might be the reason for the slow growth of shrimp infected by CMNV. This study uncovered unique characteristics of neurotropism of CMNV for the first time and explored the pathogenesis of slow growth and shell softening of P. vannamei caused by CMNV infection.

Abstract Segregation distortion is a common phenomenon found in most genetic mapping studies and is an important resource to dissect the mechanism of action in gene loci that cause deviation. Marine animals possess high genetic diversity and genomic heterozygosity, they therefore are ideal model organisms to study segregation distortion induced by selection. In the present study, we constructed a full-sib family of Fenneropenaeus chinensis and exerted high-intensity selection on 10,000 incipient progenies. 2b-RAD method was employed in remaining 273 individuals to develop genome-wide SNPs for segregating analysis and 41,612 SNPs were developed. 50.77% of 32,229 high-quality representative markers deviated from the expected Mendelian ratio. Results showed that most of these distorted markers (91.57%) were influenced at zygotic level. Heterozygote excess (53.07%) and homozygous deletions (41.96%) may both play an important role, sum of which explained 95.03% of distortion after fertilization. However, further results identified highly probable linkage among deleterious alleles, which may account for a considerable portion of heterozygote excess rather than single locus with heterozygote advantage. Results of this study support a major role of deleterious alleles in genetic load, thus in favor of partial dominance hypothesis. It would also offer necessary recommendations for the formulation of breeding strategy in shrimps.

White spot syndrome virus (WSSV) is one of the most lethal viruses in shrimp aquaculture. Compared with other shrimp species, the Chinese shrimp (Fenneropenaeus chinensis) is more susceptible to WSSV. The mortality of WSSV-infected F. chinensis can reach 100% within a week. No effective solution currently exists to solve the WSSV problem in F. chinensis aquaculture. After years of research, we found that individual F. chinensis from the same family can carry different viral load at the same time post-WSSV infection. To better understand the anti-WSSV mechanism of F. chinensis, we analysed the transcriptomic data from F. chinensis with high and low WSSV load at the same time post-WSSV infection and from healthy F. chinensis, in a WSSV-resistant group and a WSSV-susceptible group, respectively. We identified more differentially expressed genes in F. chinensis with high WSSV load than in those with low WSSV load at the same time post-WSSV infection. Many differentially expressed genes were enriched in Gene Ontology terms related to binding function and the extracellular matrix-receptor interaction pathway, which might play important roles in the anti-WSSV processes among F. chinensis.

The time maintenance accuracy of the navigation constellation determines the user positioning and timing performance. Especially in autonomous operation scenarios, the performance of navigation constellation maintenance time directly affects the duration of constellation autonomous navigation. Among them, the frequency stability of the atomic clock onboard the navigation satellite is a key factor. In order to further improve the stability of the navigation constellation time-frequency system, combined with the development of high-precision inter-satellite link measurement technology, the idea of constructing constellation-level synthetic atomic time has gradually become the development trend of major GNSS systems. This paper gives a navigation constellation time scale generation framework, and designs an improved Kalman plus weights (KPW) time scale algorithm and time-frequency steer algorithm that integrates genetic algorithms. Finally, a 30-day autonomous timekeeping simulation was carried out using the GPS precision clock data provided by CODE, when the sampling interval is 300 s, the Allan deviation of the output time scale is 5.73 × 10−14, a 71% improvement compared with the traditional KPW time scale algorithm; when the sampling interval is 1 day, the Allan deviation is 9.17 × 10−15; when the sampling interval is 1 × 106 s, the Allan deviation is 8.87 × 10−16, a 94% improvement compared with the traditional KPW time scale algorithm. The constellation-level high-precision time scale generation technology proposed in this paper can significantly improve the stability performance of navigation constellation autonomous timekeeping.

The enzyme long-chain acyl-CoA synthetase 1 (ACSL1) is essential for lipid metabolism. The ACSL1 gene controls unsaturated fatty acid (UFA) synthesis as well as the formation of lipid droplets in bovine adipocytes. Here, we used RNA-Seq to determine lncRNA and mRNA that regulate UFA synthesis in bovine adipocytes using RNA interference and non-interference with ACSL1. The corresponding target genes of differentially expressed (DE) lncRNAs and the DE mRNAs were found to be enriched in lipid and FA metabolism-related pathways, according to GO and KEGG analyses. The differentially expressed lncRNA- differentially expressed mRNA (DEL-DEM) interaction network indicated that some DELs, such as TCONS_00069661, TCONS_00040771, TCONS_ 00035606, TCONS_00048301, TCONS_001309018, and TCONS_00122946, were critical for UFA synthesis. These findings assist our understanding of the regulation of UFA synthesis by lncRNAs and mRNAs in bovine adipocytes.

In order to screen the candidate genes of Fenneropenaeus chinensis related to low-temperature tolerance, this research takes juvenile prawns of F. chinensis (P40) in low temperature stress group (4°C) and normal temperature group (18°C) as experimental materials. The results showed that a total of 127,939 Unigenes with average length of 1,190 bp were obtained by assembly, of which 46% were annotated in the Nr database. A total of 1,698 differentially expressed genes were screened by differential gene expression analysis, of which 920 genes showed up-regulated expression and 778 genes showed down-regulated expression. Both GO and KEGG enrichment analysis revealed that differentially expressed genes were enriched in spliceosomes, ribosomes, bile secretion, ABC transport pathways, and cellular nitrogen compound synthesis. A further in-depth analysis obtained 8 genes that may be associated with low-temperature traits of F. chinensis. Five of them displayed up-regulated expression, including ATP-binding cassette protein C, acid ceramidase, glutathione transferase, C-type lectin and heat shock protein HSP70. The remaining three genes, γ-butyl betaine hydroxylase, β-hexosaminidase A and long chain fatty acid-CoA ligase displayed down-regulated expression. Eight differentially expressed genes were randomly selected and the real time RT-PCR verification showed that their expression levels were consistent with the sequencing results, demonstrating the accuracy of the sequencing results. The results of this study provide basic data for revealing the molecular mechanisms of F. chinensis in response to low temperature stress and the molecular assisted breeding of F. chinensis in low temperature.

This paper presents a passive buffer system of connection mechanism for space-assembled segmented mirrors. The purpose of assembling telescope in space is to overcome the limits of launch volume and mass to support ever increasing aperture sizes. Using this buffer system, the docking impact between two mirror segments can be alleviated effectively. In this paper, first, a design methodology called “double-elastic contact model” is developed. Then, the design details and operation principle of the connection mechanism, are presented to validate the passive buffer system. Finally, by comparing the traditional docking system, the simulated results of dynamic performance show that the proposed buffer system can absorb the impact energy effectively and is considerably suitable for assembling the space optical system.

For a large-aperture space telescope, one of the key techniques is the method for designing the lightweight primary mirror assembly (PMA). In order to minimize the mirror surface error under axial gravity, lateral gravity, and polishing pressure at the same time, a method for topology optimization with multi-objective function combined with parametric optimization is introduced in this paper. The weighted compliance minimum is selected as the objective function to maximum the mirror structural stiffness. Then sensitivity analysis method and size optimization are used to determine the mirror structure parameters. Compared with two types of commonly used lightweight configurations, the new configuration design shows obvious superiority. In addition, the surface figure root mean square (RMS) of the mirror mounted by given bipod flexure (BF) under 1 g lateral gravity is minimized only with a value of 3.58 nm, which proves the effectiveness of the design method proposed in this paper.

The recovery of coseismic 3-dimensional (3D) surface deformation field plays a crucial role in studying seismic source characteristics and earthquake hazards. As of now, there are two main types of methods for recovering coseismic 3D surface deformations: the first type is to solve the problem directly by using the least squares method based on observations from three or more viewpoints, and the second type solves the problem by combining ascending and descending InSAR line-of-sight (LOS) observations with constraint models. The former type is mainly applicable to surface rupture earthquakes, because when an earthquake ruptures to the surface, we can usually obtain surface deformation observations from three or more views. The latter type applies to earthquakes that do not cause surface ruptures and have extensive blind faults. Currently, most research focuses on improving the above types of methods. However, some key factors in the coseismic 3D surface deformation inversion are rarely mentioned, such as the influence of window size on the inversion results in the strain model and variance component estimation method (SM-VCE), and whether the outliers in the observational data are considered. So, we developed a new chain of integrating InSAR observation and SM-VCE model to systematically assess the impacts of window size and outliers on coseismic 3D surface deformation inversions. Through simulation experiments, we observed that the selection of window size significantly impacts the accuracy of the results. Specifically, larger window sizes lead to wider residuals ranges in the fault region, resulting in the loss of extreme solution values when using a window of 15 × 15 pixels (i.e., 7.5 km × 7.5 km). Hence, we recommend utilizing windows with 7 × 7 pixels or 9 × 9 pixels for optimal accuracy, as larger window sizes diminish the significance of the outcomes. The elimination of points displaying different deformation directions helps reduce residuals and preserves near-field deformation results. Furthermore, the residuals along the 3D direction can be reduced by 10%–30% when a small set of points is selected using a method based on Euclidean distances. However, when 441 points were selected, the vertical residuals increased by 22% compared to 81 points. Integration of the SM-VCE algorithm with robust estimation techniques effectively minimizes far-field deformation errors in data, thereby marginally enhancing the near-field deformation solution.