To show how dramatic global climate change affects marine ecosystem species in different habitats. We used a joint species distribution model (SDM) and an ecological niche model (ENM) to investigate the suitable habitat shifts and ecological niche overlaps of the Tridentiger fishes. In the present study, the SDM results showed that 5 hotspots were identified for T. trigonocephalus and T. barbatus, and 4 hotspots for T. bifasciatus. The study on center-of-mass transfer revealed notable reductions in the habitual range of the three Tridentiger species with future climate change and no significant bipolar shifts in the center of mass. The ENM results indicated that T. trigonocephalus and T. barbatus exhibited the greatest ecological niche overlap with Schoener's D (D) and Hellinger-based I (I) values of 0.4719 and 0.7690, respectively. Both SDM and ENM results have suggested that T. trigonocephalus occupied a wider distribution and greater adaptability to future climate change. This study sought to measure the variations in the effects of global climate change on marine species in different habitats. Our study first found that intertidal species with specific life histories may be more resilient to environmental change.

A local deformation analysis method of buildings based on point cloud surface feature constraints is presented herein. First, the point cloud is pre-processed and segmented to obtain point cloud data of each surface of the building. Second, the surface features of point cloud data are recog-nized and judged. Based on the surface type, the surface fitting calcula-tion is carried out for the point cloud data, and the characteristic parameters of each surface of the building are obtained. Then, the dimen-sional and structural constraints of each building surface are calculated. Finally, according to the feature constraint relationship of building sur-faces, the spatial position relationship between building surfaces is judged, and the local deformation between surfaces is analysed. Experi-ments show that this method can judge the local deformation of different parts of the building, analyse and evaluate the safety of the building from multiple local perspectives, and improve the accuracy and reliability of building deformation analysis.

Acidic digestion is an important digestive process of marine fish. In fish stomach, two enzymes are involved in the secretion of hydrochloric acid (HCl) and proteomic digestion: H + /K + -ATPase and pepsinogen. However, the starting of digestive function in fish is still unclear. To reveal the details of acidic digestion of turbot Scophthalmus maximus in early development, a 40 day of turbot larvae culture was conducted. The H + /K + -ATPase gene from the turbot S. maximus (sm H + /K + -ATPase) was identified and characterized. Based on our previous discription on pepsinogen of turbot S. maximus , we combined pepsinogen and H + /K + -ATPase and analyzed the mechanism of acidic digestion in turbot. Results show that the spatial and temporal expression profiles of H + /K + -ATPase agreed with pepsinogen A and C in turbot, indicating a synergetic action between H + /K + -ATPase and pepsinogen during the acidic digestion process. In addition, the turbot juveniles showed a faster growth after the expressions of H + /K + -ATPase gene and pepsinogen gene, demonstrating that pepsin had a higher digestive efficiency, for which a compound diet should be provided to the fish from Day 22 onward. This study provided a reference for biology research and aquaculture of turbot and other marine fishes.

This study provides a novel record of the reproductive behaviour of the Kong skate (Okamejei kenojei) in captivity. These skates were found to mate and deposit eggs at a temperature of 16.5 +/- 0.5 degrees C. The results showed that 76.13% of the eggs possessed one yolk, 0.77% of the eggs possessed two yolks and 23.11% of the eggs had no yolk (N = 1043). The deposition of non-yolk and double-yolk eggs was random. A total of 100 eggs were collected. After nearly 92 +/- 5 days of incubation, 28 eggs failed to hatch, and 72 skates were successfully hatched with a female-to-male ratio of 1:1 (P > 0.05). The results enrich our knowledge of the reproduction in cartilaginous fishes and can inform management and conservation strategies for this species.

Convolutional neural networks (CNNs) in deep learning enable the extraction of features in image data. Through the multi-layer superposition of a convolutional neural network, we can better capture the essential characteristics of different auroral subclasses and further classify auroral images in detail. Because the auroral morphological features often present abstract characteristics, our study compares different CNN architectures and different layering in order to test the best neural network model for mesoscale aurora classification. Although the classification models and subclasses used by us are both more complex, the highest F1 score of aurora classification of the test set reaches 99.6% (ResNet-50), which performs best comparing with previous works. Our classification models work also quite well when applied to an independent auroral image sequence, declaring our approach can automatically select images of various mesoscale auroral forms using CNNs, and allow the time sequence of auroral evolution to be seen automatically through the mesoscale auroral feature recognitions.

The barred knifejaw, Oplegnathus fasciatus, is characterized by an X1X2Y system with a neo-Y chromosome for males. Here, a chromosome-level genome was assembled to investigate the origin of neo-Y chromosome to the male O. fasciatus. Twenty-three chromosomes corresponding to the male karyotypes were scaffolded to 762-Mb genome with a contig N50 length of 2.18 Mb. A large neo-Y chromosome (Ch9) in the male O. fasciatus genome was also assembled and exhibited high identity to those of the female chromosomes Ch8 and Ch10. Chromosome rearrangements events were detected in the neo-chromosome Ch9. Our results suggested that a centric fusion of acrocentric chromosomes Ch8 and Ch10 should be responsible for the formation of the X1X2Y system. The high-quality genome will not only provide a solid foundation for further sex-determining mechanism research in the X1X2Y system but also facilitate the artificial breeding aiming to improve the yield and disease resistance for Oplegnathus.

为了探明大菱鲆(Scophthalmus maximus)卵子在卵巢腔内老化的原因及特征,采用连续跟踪采卵的方式,通过荧光染色、生理生化指标测定,对不同采卵时间(0,3,6,9,12 h)的卵子活性氧和脂质过氧化情况(氧化产物丙二醛MDA)、抗氧化系统(超氧化物歧化酶SOD,还原型谷胱甘肽GSH)、卵巢液pH值及受精率和孵化率进行对比研究.结果表明,随着卵子在体内老化时间的延长,其活性氧含量及脂质过氧化程度逐渐升高,活性氧含量及过氧化程度与排卵后卵子老化呈正相关;SOD酶活力,GSH酶活力均显著下降,MDA含量显著提高;受精率和孵化率均显著下降.排卵后6 h,孵化率降到2.87％～10.60％,此时的卵质已经极度恶化,不能再继续用于后续的生产中.综上,在卵巢腔中,卵子排放后,随着时间的延长,活性氧含量显著升高,抗氧化能力逐渐下降,受精率和孵化率显著降低,老化逐渐加剧.

The barred knifejaw, Oplegnathus fasciatus (Teleostei: Centrarchiformes Oplegnathidae), is an important species in marine cage culture and fish stocking for marine ranching in East Asia. The males of Oplegnathidae (O. fasciatus and O. punctatus) species are characterized by an X1X2Y system with a neo-Y chromosome based on male karyotype analyses. Release of the chromosome-level reference genome of female O. fasciatus has facilitated insights into the origin of the unique X1X2Y system of male O. fasciatus. In the present study, we applied PacBio long-read sequencing and high-throughput chromosome interaction mapping (Hi-C) to assemble a chromosome-level genome of male O. fasciatus. A highly contiguous genome with a size of 795 Mb, 2,295 contigs, and a contig N50 of 2.13 Mb was obtained. The 1,355 ordered contigs combined with the draft genome were further assembled into 23 chromosomes approximately 762 Mb in length with a contig N50 of 2.18 Mb and a scaffold N50 of 32.43 Mb. A large neo-chromosome (Ch9) of 94.2 Mb was assembled from 444 contigs, and found to be more than three times larger than the rest chromosomes of male O. fasciatus. In addition, 63.4 Mb of the Ch9 sequences of male O. fasciatus had high identity (~99.0%) to the Ch8 (31.4 Mb/37.5 Mb) and Ch10 (32.0 Mb/35.3 Mb) sequences of female O. fasciatus based on a whole-genome synteny analysis, showing that the neo-Y chromosome shared significant homology with Ch8 and Ch10 based on male/female genome comparison. Significant fission tracks at the terminal point of the chromosomes were also identified between Ch9 and Ch8/Ch10 using synteny analyses, which showed chromosome rearrangements events had happened in the neo-chromosome Ch9. Our present results accurately demonstrated that the X1X2Y system of male O. fasciatus originated from the fusions of the non-homologous chromosomes Ch8 and Ch10. According to the synteny analyses and previous karyotypes results, which characterized acrocentric chromosomes, we suggested that a centric fusion of Ch8 and Ch10 was responsible for the formation of the X1X2Y system of male O. fasciatus.

Atlantic salmon reared in recirculating aquaculture system (RAS) may lead to inappropriately high stocking density, because fish live in a limited space. Finding the suitable stocking density of Atlantic salmon reared in RAS is very important for RAS industry. In this paper, the influence of stocking density on growth and some stress related physiological factors were investigated to evaluate the effects of stocking density. The fish were reared for 220 days at five densities (A: 24 kg/m3; B: 21 kg/m3; C: 15 kg/m3; D: 9 kg/ m3 and E: 6 kg/m3 ). The results show that 30 kg/m3 might be the maximum density which RAS can afford in China. The stocking densities under 30 kg/m3 have no effect on mortality of Atlantic salmon reared in RAS. However, the specific growth rate (SGR), final weight and weight gain in the high density group were significantly lower than the lower density groups and middle density groups. Moreover, feed conversion rate (FCR) had a negative correlation with density. Plasma hormone T3 and GH showed significant decrease with the increase of the stocking density of the experiment. Furthermore, thyroid hormone (T3), GH (growth hormone) activities were decreased with stocking density increase. However, plasma cortisol, GOT (glutamic oxalacetic transaminase) and GPT (glutamic pyruvic transaminase) activities were increase with stocking density increase. And the stocking density has no effects on plasma lysozyme of Atlantic salmon reared in RAS. These investigations would also help devise efficient ways to rear adult Atlantic salmon in China and may, in a way, help spread salmon mariculture in China.

Hyporthodus septemfasciatus is a commercially important proliferation fish which is distributed in the coastal waters of Japan, Korea, and China. We used the fluorescent AFLP technique to check the genetic differentiations between broodstock and offspring populations. A total of 422 polymorphic bands (70.10%) were detected from the 602 amplified bands. A total of 308 polymorphic loci were checked for broodstock I (Pbroodstock I = 55.50%) coupled with 356 and 294 for broodstock II (Pbroodstock II = 63.12%) and offspring (Poffspring = 52.88%), respectively. The levels of population genetic diversities for broodstock were higher than those for offspring. Both AMOVA and Fst analyses showed that significant genetic differentiation existed among populations, and limited fishery recruitment to the offspring was detected. STRUCTURE and PCoA analyses indicated that two management units existed and most offspring individuals (95.0%) only originated from 44.0% of the individuals of broodstock I, which may have negative effects on sustainable fry production.

Abstract Background The barred knifejaw (Oplegnathus fasciatus), a member of the Oplegnathidae family of the Centrarchiformes, is a commercially important rocky reef fish native to East Asia. Oplegnathus fasciatus has become an important fishery resource for offshore cage aquaculture and fish stocking of marine ranching in China, Japan, and Korea. Recently, sexual dimorphism in growth with neo-sex chromosome and widespread biotic diseases in O. fasciatus have been increasing concern in the industry. However, adequate genome resources for gaining insight into sex-determining mechanisms and establishing genetically resistant breeding systems for O. fasciatus are lacking. Here, we analyzed the entire genome of a female O. fasciatus fish using long-read sequencing and Hi-C data to generate chromosome-length scaffolds and a highly contiguous genome assembly. Findings We assembled the O. fasciatus genome with a total of 245.0 Gb of raw reads that were generated using both Pacific Bioscience (PacBio) Sequel and Illumina HiSeq 2000 platforms. The final draft genome assembly was approximately 778.7 Mb, which reached a high level of continuity with a contig N50 of 2.1 Mb. The genome size was consistent with the estimated genome size (777.5 Mb) based on k-mer analysis. We combined Hi-C data with a draft genome assembly to generate chromosome-length scaffolds. Twenty-four scaffolds corresponding to the 24 chromosomes were assembled to a final size of 768.8 Mb with a contig N50 of 2.1 Mb and a scaffold N50 of 33.5 Mb using 1,372 contigs. The identified repeat sequences accounted for 33.9% of the entire genome, and 24 003 protein-coding genes with an average of 10.1 exons per gene were annotated using de novo methods, with RNA sequencing data and homologies to other teleosts. According to phylogenetic analysis using protein-coding genes, O. fasciatus is closely related to Larimichthys crocea, with O. fasciatus diverging from their common ancestor approximately 70.5–88.5 million years ago. Conclusions We generated a high-quality draft genome for O. fasciatus using long-read PacBio sequencing technology, which represents the first chromosome-level reference genome for Oplegnathidae species. Assembly of this genome assists research into fish sex-determining mechanisms and can serve as a resource for accelerating genome-assisted improvements in resistant breeding systems.

Germ cells undergo a series of cellular changes including differentiation, mitosis, meiosis and maturation, and eventually develop into a large number of functional gametes. The available data regarding teleost gametogenesis in seasonal batch spawners is limited. In this study, we investigated spermatogenesis with special attention on spermatogonia differentiation using heat-induced masculine juveniles of genetically female Japanese flounder. Meanwhile, the Nanos2 expression had been detected by immunohistochemistry for analysis of spermatogonial stem cells (SSCs) distribution. Spermatogonia began mitosis at 35 dph, and basement membrane firstly appeared and gradually surrounded and separated the spermatogonia (type A) into single and paired status. At this period, the spermatogonia continuously maintained mitotic proliferation. As a result, the number of spermatogonia including isolated and clusters (2-8 spermatogonia) significantly increased in the presumptive testes. From 85 dph to 120 dph, with the mitosis of spermatogonia, germline acinar-clusters formed. In the clusters, type A spermatogonia differentiated into type B, and multi-spermatogonia surrounded by several sertoli cell formed cysts，which represented the formation of lobular precursors. After that, type B spermatogonia began meiosis, which indicated the initiation of spermatogenesis. In adult testes, most type A spermatogonia distributed in the peripheral region and a few clung to a basement membrane in the internal germinal epithelium. Various spermatogenic cysts with germ cells in different developmental stages existed in a testicular lobules, moreover the germ cells in earlier stages resided in the distal termini, and the advanced stages were adjacent to the spermatic duct of testes. Therefore, the testes of Japanese flounder belonged to an intermediated distribution of SSCs, which might contribute greatly to multiple spermiation during breeding season. These findings would improve the understanding the mechanisms of SSCs differentiation and testicular development, and may be of great value in future studies of the spermatogenesis regulation.

We investigate the statistical, dual‐spacecraft correlations of field‐aligned current (FAC) signatures between two Swarm spacecraft. For the first time, we infer the orientations of the current sheets of FACs by directly using the maximum correlations obtained from sliding data segments. The current sheet orientations are shown to broadly follow the mean shape of the auroral boundary for the lower latitudes and that these are most well ordered on the dusk side. Orientations at higher latitudes are less well ordered. In addition, the maximum correlation coefficients are explored as a function of magnetic local time and in terms of either the time shift (δt) or the shift in longitude (δlon) between Swarms A and C for various filtering levels and choice of auroral region. We find that the low‐latitude FACs show the strongest correlations for a broad range of magnetic local time centered on dawn and dusk, with a higher correlation coefficient on the dusk side and lower correlations near noon and midnight. The positions of maximum correlation are sensitive to the level of low‐pass filter applied to the data, implying temporal influence in the data. This study clearly reflects the two different domains of FACs: small‐scale (some tens of kilometers), which are time variable, and large‐scale (>50 km), which are rather stationary. The methodology is deliberately chosen to highlight the locations of small‐scale influences that are generally variable in both time and space. We may fortuitously find a potential new way to recognize bursts of irregular pulsations (Pi1B) using low‐Earth orbit satellites.

Some germ cell marker genes, such as vasa, nanos, and dead end (dnd), have been identified in fish. Recently, lymphocyte antigen 75 (Ly75/CD205) has been identified as a mitotic germ cell-specific cell-surface marker in several fish species. In this study, the Japanese flounder Paralichthys olivaceus ly75 homolog (ly75) was cloned and its expression pattern in gonads was analyzed. The full-length cDNA of ly75 was 7 346 bp, with an open reading frame (ORF) of 5 229 bp. The ORF encoded a protein containing 1 742 amino acids with a predicted molecular mass of 196.89 kDa. In adult tissues, ly75 transcripts were detected in all analyzed tissues but abundantly in the testis. In in-situ hybridization analyses, ly75 mRNA was predominantly localized in oocytes in the ovary and spermatogonia in the testis, but ly75 mRNA was not detected in oogonia, spermatocytes, spermatids, or spermatozoa. These results indicated that ly75 could be a potential germ cell-specific marker in P. olivaceus, as in other fishes.

ABSTRACTIn this study, all genetic female (XX) broods of Japanese flounder were produced artificially by mating the females with sex‐reversed males. The proliferation and migration of primordial germ cells (PGCs), formation of ovary and oogenesis were described in detail. After hatching, around 20 individual PGCs migrated from the lateral to the dorsal of trunk region. At 15 days posthatching (dph), a part of PGCs were covered by a single layer somatic cells and formed the genital ridge. By 22 dph, the elongated gonadal primordia appeared under the ventral kidney, where the PGCs were totally enclosed by somatic cells. During the process of migration, PGCs were presumed to be mitotically inactive. From 63 to 73 dph, somatic cells rearrangement resulted in the formation of a narrow crevice, which became deeper and formed ovarian lumen. However, at 52 dph, dramatic mitotic proliferation of germ cell occurred and germline nest formed before the appearance of ovarian lumen. The onset of intensive germ cell proliferation and appearance of cell nests could be accepted as a criterion of initial ovarian differentiation. Then germ cells and somatic epithelial cells were gradually delimited by basement membrane and formed the germinal epithelium. In this period, results from in situ hybridization revealed that the early forkhead box L2 (pofoxl2) was expressed in somatic cells and oocytes in primary growth, which indicated the prefollicle cells formed. Then oogonia or oocytes, follicle cells, basement membrane, and theca cells composed a follicle complex. Finally, oocytes underwent meiosis and developed into to mature eggs. Anat Rec, 301:727–741, 2018. © 2017 Wiley Periodicals, Inc.

Focused on a variety of JSSP considered flexibility and fuzziness, namely the fuzzy flexibility JSSP (FfJSSP), a novel method based on fuzzy satisfaction rate and differential evolution (DE) algorithm is proposed in this paper. In the method, the fuzzy membership functions' parameters are determined according to normal distribution for maximum satisfaction rate calculation. Then a DE algorithm is proposed by well designing the coding for the problem and extending the related operators on the coding. A local exploring search for operation and machine parts of the coding is also introduced to improve the performance of the method. Experimental results show that our proposed method is effective compared with other five popular existed methods. Comparisons between different mutation and crossover strategies are also performed. Numerical results show that the proposed method could be applied to real FfJSSP problems. (C) 2018 PEI, University of Maribor. All rights reserved.

Ocean warming has multifaceted impacts on marine organisms. This study investigated the different responses of Paralichthys olivaceus and the hybrids (P. olivaceus ♀ × P. dentatus ♂) to chronic and acute heat stress. By comparing their survival, behavioural and histological changes, we found that the hybrids possess a better thermal tolerance with a higher cumulative survival rate (CSR), relatively fewer behavioural changes and less gill damage. Moreover, we analysed the relationship between thermal tolerance and the hsp70 expression pattern and found that thermal tolerant species (the hybrids) exhibited higher threshold induction temperature, shorter durations, stronger magnitudes and a delay in hsp70 expression. We speculated that the expression mode of hsp70, rather than itself, plays a critical role in thermal tolerance. These findings would improve the understanding of hsp70 in future marine climate research and help clarify the profound effects of rising temperature on marine demersal fishes.

Seven-band grouper (Hyporthodus septemfasciatus) is a commercial rocky reef fish in East Asia that has been regarded as a promising species for aquaculture. To investigate the broodstock contributions to offspring for the sustainability of fry production, 62 individuals ofH. septemfasciatusfrom two broodstocks and one offspring population were analysed using fluorescent-AFLP. A total of 602 bands were amplified and 70.10% of them were polymorphic. The numbers of polymorphic loci were 308 (Pbroodstock I= 55.50%) and 356 (Pbroodstock II= 63.12%) in the two broodstocks, and 294 (Poffspring= 52.88%) in the offspring, respectively. The average values of Shannon diversity index (I) and expected heterozygosity (H) were higher in the broodstock (Ibroodstock I= 0.281,Ibroodstock II= 0.244,Hbroodstock I= 0.185,Hbroodstock II= 0.161) than those in the offspring (Ioffspring= 0.243,Hoffspring= 0.161). AMOVA and FSTanalyses showed that significant genetic differentiation between broodstock and offspring populations, and limited effective broodstock population size has contributed to the offspring. Both STRUCTURE and Principal Coordinates Analysis (PCoA) also showed the three populations composed of two stocks and most offspring individuals (95.0%) only originated from 44.0% of the individuals of broodstock I, which may have negative effects on sustainable fry production. Therefore, genetic variation between broodstock and offspring should be monitored, and large effective size of broodstock should be employed to ensure the success of commercial breeding programmes. Our data provide a useful genetic basis for future planning of sustainable culture and management ofH. septemfasciatus.

As a rocky reef species, Oplegnathus fasciatus displays significant geographic differences that may be congruent with patterns of molecular variation. We used 10 polymorphism microsatellite loci to characterize the genetic structure and test the impact of ocean currents and the Yangtze River on the population genetic connectivity of the rock bream, O. fasciatus, sampled from Jiaonan (JN), Zhoushan (ZS) and Taiwan (TW). The average number of alleles was 17.78, with a total of 160 alleles, and the average allele value in the East China Sea (ZS = 13.70) was higher than that in the Yellow Sea (JN = 6.70). The individuals at the ZS location showed the highest expected heterozygosity (He = 0.86), Nei's genetic diversity (H = 0.84) and Shannon genetic diversity (I = 2.21). Genetic bottleneck tests showed that individuals had experienced a recent bottleneck effect in the JN location. AMOVA analysis showed that 12.19% of genetic variation existed among populations, indicating significant population genetic differentiation in the species. The values of the population pairwise differentiation index (F-st and phi(pt)) ranged from 0.01 to 0.29. The UPGMA tree showed two diverged genealogical branches corresponding to sampling localities (Clade A = JN, Clade B = ZS and TW) in the species. The AMOVA and STRUCTURE analyses suggested that O. fasciatus may be composed of two stocks in the examined range, and the freshwater discharge from the Yangtze River might act as a physical barrier to genetic exchange between north and south China stocks of the species.