The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Dominique Adriaens - One of the best experts on this subject based on the ideXlab platform.
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Morphological variation in head shape of pipefishes and seahorses in relation to Snout length and developmental growth
Journal of morphology, 2011Co-Authors: Heleen Leysen, Gert Roos, Dominique AdriaensAbstract:The feeding apparatus of Syngnathidae, with its elongate tubular Snout and tiny, toothless jaws, is highly specialized for performing fast and powerful pivot feeding. In addition, the prolonged syngnathid parental care probably enables the juveniles to be provided with a feeding apparatus that resembles the one in adults, both in morphology and function. In this study, a landmark-based geometric morphometric analysis was carried out on the head of syngnathid representatives in order to (1) examine to what degree pipefish shape variation is different from that of seahorses; (2) determine whether the high level of specialization reduces the amount of intraspecific morphological variation found within the family; and (3) elucidate whether or not important shape changes occur in the seahorse head during postrelease ontogeny. We found that (1) there is a significant shape difference between head shape of pipefish and seahorse: the main differences concern Snout length and height, position and orientation of the pectoral fin base, and height of the head and opercular bone. We hypothesize that this might be related to different prey capture kinematics (long Snout with little head rotation versus short Snout with large head rotation) and to different body postures (in line with the head versus vertical with a tilted head) in pipefishes and seahorses; (2) both pipefishes and seahorses showed an inverse relation between relative Snout length and intraspecific variation and although pipefishes show a large diversity in relative Snout elongation, they are more constrained in terms of head shape; and (3) the head of juvenile Hippocampus reidi specimens still undergoes gradual shape changes after being expelled from the brood pouch. Ontogenetic changes include lowering of the Snout and head but also differences in orientation of the preopercular bone and lowering of the Snout tip.
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Musculoskeletal structure of the feeding system and implications of Snout elongation in Hippocampus reidi and Dunckerocampus dactyliophorus
Journal of fish biology, 2011Co-Authors: Heleen Leysen, Joachim Christiaens, B. De Kegel, Matthieu Boone, L. Van Hoorebeke, Dominique AdriaensAbstract:A thorough morphological description of the feeding apparatus in Hippocampus reidi, a long-Snouted seahorse, and Dunckerocampus dactyliophorus, an extremely long-Snouted pipefish, revealed specialized features that might be associated with the fast and powerful suction feeding, like the two ligamentous connections between the lower jaw and the hyoid, the saddle joint of the latter with the suspensorium and the vertebro-pectoral fusion that articulates on three points with the cranium. Despite the conserved morphology of the feeding apparatus, it was found that in H. reidi the orientation of the occipital joint is ventrocaudal, the sternohyoideus and epaxial muscles are more bulky and both have a short tendon. In D. dactyliophorus, on the other hand, the protractor hyoidei muscle is enclosed by the mandibulo-hyoid ligament, the sternohyoideus and epaxial tendons are long and a sesamoid bone is present in the latter. These features were compared to other syngnathid species with different Snout lengths to evaluate the implications of Snout elongation on the musculoskeletal structure of the cranium. The arched path of the adductor mandibulae and the greater rigidity of the lower jaw might be related to elongation of the Snout, as it yields an increased mechanical advantage of the lower jaw system and a reduced torque between the elements of the lower jaw during protractor hyoidei muscle contraction, respectively. Nevertheless, most observed features did not seem to be related to Snout length, but might be associated with different force-generating strategies.
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Effects of Snout dimensions on the hydrodynamics of suction feeding in juvenile and adult seahorses
Journal of Theoretical Biology, 2010Co-Authors: Gert Roos, Sam Van Wassenbergh, Peter Aerts, Anthony Herrel, Dominique AdriaensAbstract:Seahorses give birth to juveniles having a fully functional feeding apparatus, and juvenile feeding behaviour shows striking similarities to that of adults. However, a significant allometric growth of the Snout is observed during which the Snout shape changes from relatively short and broad in juveniles to relatively long and slender in adults. Since the shape of the buccal cavity is a critical determinant of suction performance, this Snout allometry will inevitably affect the suction feeding ability. To test whether the Snout is optimised for suction feeding throughout ontogeny, we simulated the expansion of different Snout shapes varying from extremely long and slender to short and broad for juvenile and adult Snout sizes using computational fluid dynamic models. Our results showed that the Snout diameter at the start of the simulations is involved in a trade-off between the realisable suction volume and expansion time on the one hand (improving with larger initial diameters), and maximal flow velocity on the other hand (improving with smaller initial diameters). Moreover, suction performance (suction volume as well as maximal attainable flow velocity) increased with decreasing Snout length. However, an increase in Snout length decreases the time to reach the prey by cranial rotation, which may explain the prevalence of long Snouts among syngnathid fishes despite the reduced suction performance. Thus the design of the seahorse Snout revolves around a trade-off between the ability to generate high-volume suction versus minimisation of the time needed to reach the prey by cranial rotation.
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Effects of Snout dimensions on the hydrodynamics of suction feeding in juvenile and adult seahorses.
Journal of theoretical biology, 2010Co-Authors: Gert Roos, Sam Van Wassenbergh, Peter Aerts, Anthony Herrel, Dominique AdriaensAbstract:Summary Seahorses give birth to juveniles having a fully functional feeding apparatus, and juvenile feeding behaviour shows striking similarities to that of adults. However, a significant allometric growth of the Snout is observed during which the Snout shape changes from relatively short and broad in juveniles to relatively long and slender in adults. Since the shape of the buccal cavity is a critical determinant of the suction performance, this Snout allometry will inevitably affect the suction feeding ability. To test whether the Snout is optimised for suction feeding throughout an ontogeny, we simulated the expansion of different Snout shapes varying from extremely long and slender to short and broad for juvenile and adult Snout sizes, using computational fluid dynamic models. Our results showed that the Snout diameter at the start of the simulations is involved in a trade-off between the realizable suction volume and expansion time on the one hand (improving with larger initial diameters), and maximal flow velocity on the other hand (improving with smaller initial diameters). Moreover suction performance (suction volume as well as maximal attainable flow velocity) increased with decreasing Snout length. However, an increase in Snout length decreases the time to reach the prey by the cranial rotation, which may explain the prevalence of long Snouts among syngnathid fishes despite the reduced suction performance. Thus, the design of the seahorse Snout revolves around a trade-off between the ability to generate high-volume suction versus minimisation of the time needed to reach the prey by the cranial rotation.
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Snout allometry in seahorses: insights on optimisation of pivot feeding performance during ontogeny
Journal of Experimental Biology, 2010Co-Authors: Gert Roos, Sam Van Wassenbergh, Anthony Herrel, Dominique Adriaens, Peter AertsAbstract:As juvenile life-history stages are subjected to strong selection, these stages often show levels of performance approaching those of adults, or show a disproportionately rapid increase of performance with age. Although testing performance capacity in aquatic suction feeders is often problematic, in pivot feeders such as seahorses models have been proposed to estimate whether Snout length is optimal to minimise the time needed to reach the prey. Here, we investigate whether the same model can also explain the Snout lengths in an ontogenetic series of seahorses, explore how pivot feeding kinematics change during ontogeny, and test whether juveniles show disproportionate levels of performance. Our analysis shows that the dimensions of the Snout change during ontogeny from short and broad to long and narrow. Model calculations show that the Snout lengths of newborn and juvenile seahorses are nearly optimal for minimising prey reach time. However, in juveniles the centre of head rotation in the earth-bound frame of reference is located near the posterior end of the head, whereas in adults it is shifted forward and is located approximately above the eye. Modelling shows that this forward shift in the centre of rotation has the advantage of decreasing the moment of inertia and the torque required to rotate the head, but has the disadvantage of slightly increasing the time needed to reach the prey. Thus, the Snout lengths of juvenile seahorses appear to be close to optimal, suggesting that they reach levels of performance close to adult levels, which illustrates the pervasive nature of selection on performance in juveniles.
Shu-ming Zou - One of the best experts on this subject based on the ideXlab platform.
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Screening of hypoxia-tolerance related SNP in a selectively bred F5 strain of blunt Snout bream (Megalobrama amblycephala)
Aquaculture, 2020Co-Authors: Wang Dongdong, Wu Chengbin, Jie Chen, Shu-ming ZouAbstract:Abstract Blunt Snout bream (Megalobrama amblycephala) is a typical hypoxia-sensitive freshwater fish species. The breeding of new hypoxia-tolerant strains is important for blunt Snout bream aquaculture. Starting in 2007, selective breeding under hypoxic stress has been performed in a wild-caught blunt Snout bream population from Poyang Lake, China. In 2017, the selectively bred F5 population was obtained, which showed markedly improved tolerance toward hypoxic stress. In this study, we identified two completed linked SNP sites at 397 and 715 within exons of the Egln2 gene. We identified these SNP sites after examination of transcriptome data from blunt Snout bream of the hypoxia-tolerant strain, which can be formed using two haplotypes, namely, haplotype 1 (C397G715) and 2 (T397T715). Haplotype 1 occurred mainly in hypoxia sensitive control blunt Snout bream, whereas haplotype 2 was predominantly found in blunt Snout bream of the hypoxia-tolerant strain. The enzyme activities of CAT, SOD, and Na+/K+-ATP related to hypoxia tolerance in blunt Snout bream of diplotype II (T397T397T715T715) were significantly higher than those in blunt Snout bream with other genetic combinations. The homozygous diplotype II blunt Snout bream, in particular, had a significantly (p
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Identification of duplicated suppressor of cytokine signaling 3 (SOCS3) genes in blunt Snout bream (Megalobrama amblycephala).
Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 2019Co-Authors: Shan-shan Zhao, Wu Chengbin, Xin-yu Zhao, Zheng Guodong, Shu-ming ZouAbstract:Abstract The suppressor of cytokine signaling 3 (SOCS3) negatively regulates the responses of various immune cytokines. In this study, we identified socs3s genes of blunt Snout bream. 209- and 216-aa long peptides are encoded by socs3a and socs3b genes, respectively. The socs3s mRNAs are expressed consistently during the entire process of embryonic development. Whole-mount in situ hybridization detected socs3a in the eyes and posterior somites at 12 h post fertilization (hpf), transcribed at the otic vesicle at 24 hpf, and transcribed at the eyes, brain, and otic vesicle at 36 hpf; while the socs3b mRNA was transcribed at the notochord at 12 hpf, expressed in the brain, eyes, and tailbud at 24 hpf, and detected in the brain at 36 hpf. The expression of socs3a is slightly different from that of socs3b in tissues of juvenile and adult blunt Snout bream. After recombinant human growth hormone (hGH) treatment, the transcript levels of socs3s of blunt Snout bream were increased in gills, spleen, kidney, and gonads. After Aerononas hydrophila infection, the mRNA levels of socs3s of blunt Snout bream were significantly increased in the liver, spleen, intestine, and kidney tissues. Blunt Snout bream were susceptible to various pathogenic microorganisms, we intraperitoneally injected blunt Snout bream with A. hydrophila to explore the immune mechanism of socs3s. These results suggested that socs3s of blunt Snout bream plays important roles in the regulation of embryonic development and tissue growth, and that socs3s may also play key roles in regulating the bacterial-induced congenital immune response. Socs3s genes has the potential to be used as targeted genes to improve the immunity against bacteria, which is conducive to the improvement of production and breeding.
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Gill remodeling in response to hypoxia and temperature occurs in the hypoxia sensitive blunt Snout bream (Megalobrama amblycephala)
Aquaculture, 2017Co-Authors: Wu Chengbin, Jie Chen, Zi-yin Liu, Xia-yun Jiang, Shu-ming ZouAbstract:Abstract In this study, we found that blunt Snout bream (Megalobrama amblycephala) had a relatively high critical oxygen tension at which it lost its equilibrium (LOEcrit), confirming that it is a hypoxia sensitive fish. Blunt Snout bream has the ability to remodel its gill structure in response to oxygen levels. When blunt Snout bream were exposed to 4- or 7-days of hypoxia, the average protruding lamella heights and mean lamellar area of gills were significantly (P
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Transgenic overexpression of follistatin 2 in blunt Snout bream results in increased muscle mass caused by hypertrophy
Aquaculture, 2017Co-Authors: Xia-yun Jiang, Chuang-xin Huang, Sha-sha Zhong, Cheng-fei Sun, Shu-ming ZouAbstract:Abstract As a competitive binding protein, follistatin (FST) antagonizes myostatin (MSTN) function and promotes muscle growth. Overexpression of FST in transgenic mice results in dramatically increased muscle mass caused by hyperplasia and/or hypertrophy. Previously, we identified two functional divergent fst genes (gcfst1 and gcfst2) in grass carp (Ctenopharyngodon idella). The objectives of this study were to determine if gcfst genes have similar roles on promoting muscle growth in fish. We generated a heterozygous gcfst1- and gcfst2-transgenic F0 generation in blunt Snout bream (Megalobrama amblycephala). We then produced a homozygous gynogenetic F1 generation, and eventually a homozygous transgenic F2 generation. Driven by the zebrafish skeletal muscle-specific gene Mylz2 promoter, high levels of gcfst1 or gcfst2 mRNAs were expressed in embryonic somites and adult muscles in homozygous gcfst1- or gcfst2-transgenic F2 blunt Snout bream, respectively. In contrast to gcfst1-transgenic fish or wild-type controls, adult gcfst2-transgenic F2 blunt Snout bream exhibited a double-muscling phenotype and marked increases in body height and thickness. Overexpression of gcfst2 caused significant fiber size enlargement in skeletal muscle in gcfst2-transgenic F2 blunt Snout bream. Our findings suggest that enhanced muscle growth induced by gcfst2 overexpression in transgenic blunt Snout bream is caused by hypertrophic muscle growth. This approach may be used to promote directional breeding in important aquaculture species such as blunt Snout bream in the future. Statement of relevance To promote directional breeding in important aquaculture species blunt Snout bream, our research papers presents novel data on fish breeding. Our article complies with the Policy Statement for submission of manuscripts to the Genetics Section.
Gert Roos - One of the best experts on this subject based on the ideXlab platform.
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Morphological variation in head shape of pipefishes and seahorses in relation to Snout length and developmental growth
Journal of morphology, 2011Co-Authors: Heleen Leysen, Gert Roos, Dominique AdriaensAbstract:The feeding apparatus of Syngnathidae, with its elongate tubular Snout and tiny, toothless jaws, is highly specialized for performing fast and powerful pivot feeding. In addition, the prolonged syngnathid parental care probably enables the juveniles to be provided with a feeding apparatus that resembles the one in adults, both in morphology and function. In this study, a landmark-based geometric morphometric analysis was carried out on the head of syngnathid representatives in order to (1) examine to what degree pipefish shape variation is different from that of seahorses; (2) determine whether the high level of specialization reduces the amount of intraspecific morphological variation found within the family; and (3) elucidate whether or not important shape changes occur in the seahorse head during postrelease ontogeny. We found that (1) there is a significant shape difference between head shape of pipefish and seahorse: the main differences concern Snout length and height, position and orientation of the pectoral fin base, and height of the head and opercular bone. We hypothesize that this might be related to different prey capture kinematics (long Snout with little head rotation versus short Snout with large head rotation) and to different body postures (in line with the head versus vertical with a tilted head) in pipefishes and seahorses; (2) both pipefishes and seahorses showed an inverse relation between relative Snout length and intraspecific variation and although pipefishes show a large diversity in relative Snout elongation, they are more constrained in terms of head shape; and (3) the head of juvenile Hippocampus reidi specimens still undergoes gradual shape changes after being expelled from the brood pouch. Ontogenetic changes include lowering of the Snout and head but also differences in orientation of the preopercular bone and lowering of the Snout tip.
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Effects of Snout dimensions on the hydrodynamics of suction feeding in juvenile and adult seahorses
Journal of Theoretical Biology, 2010Co-Authors: Gert Roos, Sam Van Wassenbergh, Peter Aerts, Anthony Herrel, Dominique AdriaensAbstract:Seahorses give birth to juveniles having a fully functional feeding apparatus, and juvenile feeding behaviour shows striking similarities to that of adults. However, a significant allometric growth of the Snout is observed during which the Snout shape changes from relatively short and broad in juveniles to relatively long and slender in adults. Since the shape of the buccal cavity is a critical determinant of suction performance, this Snout allometry will inevitably affect the suction feeding ability. To test whether the Snout is optimised for suction feeding throughout ontogeny, we simulated the expansion of different Snout shapes varying from extremely long and slender to short and broad for juvenile and adult Snout sizes using computational fluid dynamic models. Our results showed that the Snout diameter at the start of the simulations is involved in a trade-off between the realisable suction volume and expansion time on the one hand (improving with larger initial diameters), and maximal flow velocity on the other hand (improving with smaller initial diameters). Moreover, suction performance (suction volume as well as maximal attainable flow velocity) increased with decreasing Snout length. However, an increase in Snout length decreases the time to reach the prey by cranial rotation, which may explain the prevalence of long Snouts among syngnathid fishes despite the reduced suction performance. Thus the design of the seahorse Snout revolves around a trade-off between the ability to generate high-volume suction versus minimisation of the time needed to reach the prey by cranial rotation.
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Effects of Snout dimensions on the hydrodynamics of suction feeding in juvenile and adult seahorses.
Journal of theoretical biology, 2010Co-Authors: Gert Roos, Sam Van Wassenbergh, Peter Aerts, Anthony Herrel, Dominique AdriaensAbstract:Summary Seahorses give birth to juveniles having a fully functional feeding apparatus, and juvenile feeding behaviour shows striking similarities to that of adults. However, a significant allometric growth of the Snout is observed during which the Snout shape changes from relatively short and broad in juveniles to relatively long and slender in adults. Since the shape of the buccal cavity is a critical determinant of the suction performance, this Snout allometry will inevitably affect the suction feeding ability. To test whether the Snout is optimised for suction feeding throughout an ontogeny, we simulated the expansion of different Snout shapes varying from extremely long and slender to short and broad for juvenile and adult Snout sizes, using computational fluid dynamic models. Our results showed that the Snout diameter at the start of the simulations is involved in a trade-off between the realizable suction volume and expansion time on the one hand (improving with larger initial diameters), and maximal flow velocity on the other hand (improving with smaller initial diameters). Moreover suction performance (suction volume as well as maximal attainable flow velocity) increased with decreasing Snout length. However, an increase in Snout length decreases the time to reach the prey by the cranial rotation, which may explain the prevalence of long Snouts among syngnathid fishes despite the reduced suction performance. Thus, the design of the seahorse Snout revolves around a trade-off between the ability to generate high-volume suction versus minimisation of the time needed to reach the prey by the cranial rotation.
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Snout allometry in seahorses: insights on optimisation of pivot feeding performance during ontogeny
Journal of Experimental Biology, 2010Co-Authors: Gert Roos, Sam Van Wassenbergh, Anthony Herrel, Dominique Adriaens, Peter AertsAbstract:As juvenile life-history stages are subjected to strong selection, these stages often show levels of performance approaching those of adults, or show a disproportionately rapid increase of performance with age. Although testing performance capacity in aquatic suction feeders is often problematic, in pivot feeders such as seahorses models have been proposed to estimate whether Snout length is optimal to minimise the time needed to reach the prey. Here, we investigate whether the same model can also explain the Snout lengths in an ontogenetic series of seahorses, explore how pivot feeding kinematics change during ontogeny, and test whether juveniles show disproportionate levels of performance. Our analysis shows that the dimensions of the Snout change during ontogeny from short and broad to long and narrow. Model calculations show that the Snout lengths of newborn and juvenile seahorses are nearly optimal for minimising prey reach time. However, in juveniles the centre of head rotation in the earth-bound frame of reference is located near the posterior end of the head, whereas in adults it is shifted forward and is located approximately above the eye. Modelling shows that this forward shift in the centre of rotation has the advantage of decreasing the moment of inertia and the torque required to rotate the head, but has the disadvantage of slightly increasing the time needed to reach the prey. Thus, the Snout lengths of juvenile seahorses appear to be close to optimal, suggesting that they reach levels of performance close to adult levels, which illustrates the pervasive nature of selection on performance in juveniles.
Weimin Wang - One of the best experts on this subject based on the ideXlab platform.
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ghrelin neuropeptide y npy and cholecystokinin cck in blunt Snout bream megalobrama amblycephala cdna cloning tissue distribution and mrna expression changes responding to fasting and refeeding
General and Comparative Endocrinology, 2015Co-Authors: Haichao Ping, Guirong Zhang, Kaijian Wei, Guiwei Zou, Zechao Shi, Ruibin Yang, Weimin WangAbstract:Blunt Snout bream (Megalobrama amblycephala Yih, 1955) is an endemic freshwater fish in China for which the endocrine mechanism of regulation of feeding has never been examined. Ghrelin, neuropeptide Y (NPY) and cholecystokinin (CCK) play important roles in the regulation of fish feeding. In this study, full-length cDNAs of ghrelin, NPY and CCK were cloned and analyzed from blunt Snout bream. Both the ghrelin and NPY genes of blunt Snout bream had the same amino acid sequences as grass carp, and CCK also shared considerable similarity with that of grass carp. The three genes were expressed in a wide range of adult tissues, with the highest expression levels of ghrelin in the hindgut, NPY in the hypothalamus and CCK in the pituitary, respectively. Starvation challenge experiments showed that the expression levels of ghrelin and NPY mRNA increased in brain and intestine after starvation, and the expression levels of CCK decreased after starvation. Refeeding could bring the expression levels of the three genes back to the control levels. These results indicated that the feeding behavior of blunt Snout bream was regulated by the potential correlative actions of ghrelin, NPY and CCK, which contributed to the defense against starvation. This study will further our understanding of the function of ghrelin, NPY and CCK and the molecular mechanism of feeding regulation in teleosts.
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transcriptome analysis and microsatellite discovery in the blunt Snout bream megalobrama amblycephala after challenge with aeromonas hydrophila
Fish & Shellfish Immunology, 2015Co-Authors: Ngoc Tuan Tran, Zexia Gao, Honghao Zhao, Boxiang Chen, Yuhua Zhao, Li Lin, Xueqin Liu, Weimin WangAbstract:Abstract The blunt Snout bream, Megalobrama amblycephala , is a herbivorous freshwater fish species native to China and a major aquaculture species in Chinese freshwater polyculture systems. In recent years, the bacterium Aeromonas hydrophila has been reported to be its pathogen causing great losses of farmed fish. To understand the immune response of the blunt Snout bream to A. hydrophila infection, we used the Solexa/Illumina technology to analyze the transcriptomic profile after artificial bacterial infection. Two nonnormalized cDNA libraries were synthesized from tissues collected from control blunt Snout bream or those injected with A. hydrophila . After assembly, 155,052 unigenes (average length 692.8 bp) were isolated. All unigenes were annotated using BLASTX relative to several public databases: the National Center for Biotechnology Information nonreduntant (Nr) database, SwissProt, Eukaryotic Orthologous Groups of proteins (KOG), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Ontology (GO). The sequence similarity (86%) of the assembled unigenes was to zebrafish based on the Nr database. A number of unigenes (n = 30,482) were assigned to three GO categories: biological processes (25,242 unigenes), molecular functions (26,096 unigenes), and cellular components (22,778 unigenes). 20,909 unigenes were classified into 25 KOG categories and 28,744 unigenes were assigned into 315 specific signaling pathways. In total, 238 significantly differentially expressed unigenes (mapped to 125 genes) were identified: 101 upregulated genes and 24 downregulated genes. Another 303 unigenes were mapped to unknown or novel genes. Among the known expressed genes identified, 53 were immune-related genes and were distributed in 71 signaling pathways. The expression patterns of selected up- and downregulated genes from the control and injected groups were determined with reverse transcription–quantitative PCR (RT–qPCR). Microsatellites (n = 10,877), including di-to pentanucleotide repeat motifs, were also identified in the blunt Snout bream transcriptome profiles. This study extends our understanding of the immune defense mechanisms of the blunt Snout bream against A. hydrophila and provides useful data for further studies of the immunogenetics of this species.
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genetic diversity of and differentiation among five populations of blunt Snout bream megalobrama amblycephala revealed by srap markers implications for conservation and management
PLOS ONE, 2014Co-Authors: Guirong Zhang, Wei Ran, Jonathan P A Gardner, Kaijian Wei, Weimin Wang, Guiwei ZouAbstract:The blunt Snout bream (Megalobrama amblycephala) is an important freshwater aquaculture fish throughout China. Because of widespread introductions of this species to many regions, the genetic diversity of wild and natural populations is now threatened. In the present study, SRAP (sequence-related amplified polymorphism) markers were used to assess genetic diversity of blunt Snout bream. Three natural populations (Liangzi Lake, Poyang Lake and Yuni Lake, one cultured population (Nanxian) and one genetic strain (‘Pujiang No. 1’) of blunt Snout bream were screened with 88 SRAP primer combinations, of which 13 primer pairs produced stable and reproducible amplification patterns. In total, 172 bands were produced, of which 132 bands were polymorphic. Nei's gene diversity (h) and Shannon's information index (I) values provided evidence of differences in genetic diversity among the five populations (Poyang Lake>Liangzi Lake>Nanxian>‘Pujiang No. 1’>Yuni Lake). Based on cluster analysis conducted on genetic distance values, the five blunt Snout bream populations were divided into three groups, Poyang Lake and Liangzi Lake (natural populations), Nanxian and ‘Pujiang No. 1’ (cultured population and genetically selected strain), and Yuni Lake (natural population). Significant genetic differentiation was found among the five populations using analysis of molecular variance (AMOVA), with more genetic divergence existing among populations (55.49%), than within populations (44.51%). This molecular marker technique is a simple and efficient method to quantify genetic diversity within and among fish populations, and is employed here to help manage and conserve germplasm variability of blunt Snout bream and to support the ongoing selective breeding programme for this fish.
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molecular cloning and expression analysis of liver expressed antimicrobial peptide 1 leap 1 and leap 2 genes in the blunt Snout bream megalobrama amblycephala
Fish & Shellfish Immunology, 2013Co-Authors: Tao Liang, Guirong Zhang, Kaijian Wei, Weimin Wang, Ke Feng, Guiwei ZouAbstract:Liver-expressed antimicrobial peptide 1 (LEAP-1) and LEAP-2 are widespread in fish and extremely important components of the host innate immune system. In this study, full-length cDNAs of LEAP-1 and LEAP-2 were cloned and sequenced from blunt Snout bream, Megalobrama amblycephala. The open reading frames (ORF) of LEAP-1 and LEAP-2 genes encode putative peptides of 94 and 92 amino acids, which possess eight and four conserved cysteine residues, respectively. The homologous identities of deduced amino acid sequences show that the LEAP-1 and LEAP-2 of blunt Snout bream share considerable similarity with those of grass carp. The mRNA expressions of LEAP-1 and LEAP-2 were detectable at different early developmental stages of blunt Snout bream and varied with embryonic and larval growth. LEAP-1 and LEAP-2 were expressed in a wide range of adult tissues, with the highest expression levels in the liver and midgut, respectively. Bacterial challenge experiments showed that the levels of LEAP-1 and LEAP-2 mRNA expression were up-regulated in the liver, spleen, gill and brain of juvenile blunt Snout bream. These results indicate that the LEAP-1 and LEAP-2 may play important roles in early development of embryos and fry, and may contribute to the defense against the pathogenic bacterial invasion. This study will further our understanding of the function of LEAP-1 and LEAP-2 and the molecular mechanism of innate immunity in teleosts.
Peter Aerts - One of the best experts on this subject based on the ideXlab platform.
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Effects of Snout dimensions on the hydrodynamics of suction feeding in juvenile and adult seahorses
Journal of Theoretical Biology, 2010Co-Authors: Gert Roos, Sam Van Wassenbergh, Peter Aerts, Anthony Herrel, Dominique AdriaensAbstract:Seahorses give birth to juveniles having a fully functional feeding apparatus, and juvenile feeding behaviour shows striking similarities to that of adults. However, a significant allometric growth of the Snout is observed during which the Snout shape changes from relatively short and broad in juveniles to relatively long and slender in adults. Since the shape of the buccal cavity is a critical determinant of suction performance, this Snout allometry will inevitably affect the suction feeding ability. To test whether the Snout is optimised for suction feeding throughout ontogeny, we simulated the expansion of different Snout shapes varying from extremely long and slender to short and broad for juvenile and adult Snout sizes using computational fluid dynamic models. Our results showed that the Snout diameter at the start of the simulations is involved in a trade-off between the realisable suction volume and expansion time on the one hand (improving with larger initial diameters), and maximal flow velocity on the other hand (improving with smaller initial diameters). Moreover, suction performance (suction volume as well as maximal attainable flow velocity) increased with decreasing Snout length. However, an increase in Snout length decreases the time to reach the prey by cranial rotation, which may explain the prevalence of long Snouts among syngnathid fishes despite the reduced suction performance. Thus the design of the seahorse Snout revolves around a trade-off between the ability to generate high-volume suction versus minimisation of the time needed to reach the prey by cranial rotation.
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Effects of Snout dimensions on the hydrodynamics of suction feeding in juvenile and adult seahorses.
Journal of theoretical biology, 2010Co-Authors: Gert Roos, Sam Van Wassenbergh, Peter Aerts, Anthony Herrel, Dominique AdriaensAbstract:Summary Seahorses give birth to juveniles having a fully functional feeding apparatus, and juvenile feeding behaviour shows striking similarities to that of adults. However, a significant allometric growth of the Snout is observed during which the Snout shape changes from relatively short and broad in juveniles to relatively long and slender in adults. Since the shape of the buccal cavity is a critical determinant of the suction performance, this Snout allometry will inevitably affect the suction feeding ability. To test whether the Snout is optimised for suction feeding throughout an ontogeny, we simulated the expansion of different Snout shapes varying from extremely long and slender to short and broad for juvenile and adult Snout sizes, using computational fluid dynamic models. Our results showed that the Snout diameter at the start of the simulations is involved in a trade-off between the realizable suction volume and expansion time on the one hand (improving with larger initial diameters), and maximal flow velocity on the other hand (improving with smaller initial diameters). Moreover suction performance (suction volume as well as maximal attainable flow velocity) increased with decreasing Snout length. However, an increase in Snout length decreases the time to reach the prey by the cranial rotation, which may explain the prevalence of long Snouts among syngnathid fishes despite the reduced suction performance. Thus, the design of the seahorse Snout revolves around a trade-off between the ability to generate high-volume suction versus minimisation of the time needed to reach the prey by the cranial rotation.
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Snout allometry in seahorses: insights on optimisation of pivot feeding performance during ontogeny
Journal of Experimental Biology, 2010Co-Authors: Gert Roos, Sam Van Wassenbergh, Anthony Herrel, Dominique Adriaens, Peter AertsAbstract:As juvenile life-history stages are subjected to strong selection, these stages often show levels of performance approaching those of adults, or show a disproportionately rapid increase of performance with age. Although testing performance capacity in aquatic suction feeders is often problematic, in pivot feeders such as seahorses models have been proposed to estimate whether Snout length is optimal to minimise the time needed to reach the prey. Here, we investigate whether the same model can also explain the Snout lengths in an ontogenetic series of seahorses, explore how pivot feeding kinematics change during ontogeny, and test whether juveniles show disproportionate levels of performance. Our analysis shows that the dimensions of the Snout change during ontogeny from short and broad to long and narrow. Model calculations show that the Snout lengths of newborn and juvenile seahorses are nearly optimal for minimising prey reach time. However, in juveniles the centre of head rotation in the earth-bound frame of reference is located near the posterior end of the head, whereas in adults it is shifted forward and is located approximately above the eye. Modelling shows that this forward shift in the centre of rotation has the advantage of decreasing the moment of inertia and the torque required to rotate the head, but has the disadvantage of slightly increasing the time needed to reach the prey. Thus, the Snout lengths of juvenile seahorses appear to be close to optimal, suggesting that they reach levels of performance close to adult levels, which illustrates the pervasive nature of selection on performance in juveniles.
