Complete mitochondrial genome of black porgy Acanthopagrus schlegelii (Perciformes, Sparidae)

Black porgy, Acanthopagrus schlegelii, is a marine protandrous hermaphrodite and belongs to one of the most important species commercialized for food in various areas of Asia. In this study, the complete mitochondrial genome of A. schlegelii has been determined. The mitogenome was 16,649 bp in length and contained 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and 2 non-coding regions. It shared 90.2%, 82.3%, and 82.1% mitogenome sequence with Acanthopagrus latus, Parargyrops edita, and Pagrus major, respectively.     

四种鲷科鱼类的精子激活条件与其生态习性的关系

研究了盐度、ｐＨ和温度和对黄鳍鲷Ｓｐａｒｕｓ ｌａｔｕｓ（Ｈｏｕｔｔｕｙｎ）、平鲷Ｒｈａｂｄｏｓａｒｇｕｓ ｓａｒｂａ（Ｆｏｒｄｋａｌ）、黑鲷Ｓｐａｒｕｓ ｍａｃｒｏｃｅｐｈａｌｕｓ（Ｂａｓｉｌｅｗｓｋｙ）和真鲷ｐａｇｒｏｓｏｍｕｓ ｍａｊｏｒ（Ｔｅｍｍｉｎｃｋ ｅｔ Ｓｃｈｌｅｇｅｌ）４种鲷科鱼类精子活力的影响。比较了南海区４种鲷科鱼类精子对盐度、ｐＨ和温度和适应性探讨了４种鲷科鱼类的精子激活条     

The prostaglandin synthesis in marine fish thrombocyte

1. Prostaglandin (PG) syntheses from labelled highly unsaturated fatty acids were investigated in washed thrombocyte suspensions of four species of marine fish, flounder (Paralichthys olivaceus), black seabream (Acanthopagrus schlegeli), black rockfish (Sebastes schlegeli), and red seabream (Pagrus major). 2. Synthesized PGs were analyzed by thin-layer radiochromatogram scanner and high-performance liquid chromatography. 3. When [1-(14)C]arachidonic acid (AA) was incubated with washer thrombocyte suspension, AA was mainly converted to PGF(2alpha), PGE2, and PGD2 in all species. 4. It was suggested that [1-(14)C]eicosapentaenoic acid was mainly converted in PGs only in black rockfish thrombocytes, and the metabolites were mainly PGE3 and PGD3. 5 However, [1-(14)C]docosahexaenoic acid was not cyclized into PGs in all the species.     

Ultrastructure of Pagrus major and Rhabdosargus sarba spermatozoa (Perciformes: Sparidae: Sparinae)

Transmission and scanning electron microscopy were used to investigate the ultrastructure of spermatozoa in two Sparinae species Pagrus major and Rhabdosargus sarba. Ultrastructurally, the spermatozoa of P. major and R. sarba both consist of a spherical, homogeneously electron-dense nucleus with a deep axial nuclear fossa, and an unusual notch, in the nuclear region. The midpiece contains two spherical mitochondria in R. sarba and one in P. major. The comparison of spermatozoal ultrastructure of these two species of Sparidae shows that they closely resemble one another and suggests that they are closely related. Variation in the geometry and dimensions of the mitochondrion and nucleus is substantial in these two Sparidae species. It is concluded that the spermatozoa of both species are of primitive type, and they are distinguished by several unique features which may provide useful systematic characteristics.     

Stable minihairpin structures forming at minisatellite DNA isolated from yellow fin sea bream Acanthopagrus latus

The lengths of simple repeat sequences are generally unstable or polymorphic (highly variable with respect to the numbers of tandem repeats). Previously we have isolated a family of minisatellite DNA (GenBank accession AF422186) that appears specifically and abundantly in the genome of yellow fin sea bream Acanthopagrus latus but not in closely-related red sea bream Pagrus major, and found that the numbers of tandem arrays in the homologous loci are polymorphic. This means that the minisatellite sequence has appeared and propagated in A. latus genome after speciation. In order to understand what makes the minisatellite widespread within the A. latus genome and what causes the polymorphic nature of the number of tandem repeats, the structural features of single-stranded polynucleotides were analyzed by electrophoresis, chemical modification, circular dichroism (CD), differential scanning calorimetry (DSC) and electron microscopy. The results suggest that a portion of the repeat unit forms a stable minihairpin structure, and it can cause polymerase pausing within the minisatellite DNA.     

Escherichia coli-produced fish growth hormone as a feed additive to enhance the growth of juvenile black seabream (Acanthopagrus schlegeli)

Recombinant growth hormone (rGH) of fish was highly efficiently synthesized by Escherichia coli cells harbouring an expression plasmid (pKLYP) containing a 600 base pairs segment of cDNA which encoded the mature region of yellowfin porgy ( Acanthopagrus latus ) pre-growth hormone. After dena-turation and renaturation, rGH purified from inclusion bodies became the refolding form. rGH were then processed into the fishmeal pellet at various concentrations. Juvenile black sea-bream ( Acanthopagrus schlegeli ) fed twice daily with meal containing 0.5% rGH exhibited significant increases (P < 0.01) in percentage weight gain (60%) and feed efficiency (41%) relative to fish in the control group at week 12. Growth enhancement was maintained for at least 4 weeks (at week 16) after the termination of treatment.     

Pathogenesis of Gastroenteritis Caused by Vibrio carchariae in Cultured Marine Fish

Serious mortality among the cultured grouper Epinephelus coioides, characterized by a swollen intestine containing yellow fluid (gastroenteritis), occurred in 1993 in Taiwan. A bacterium isolated from the intestinal fluid and head kidney of moribund groupers was identified as Vibrio carchariae. Since then, the same Vibrio species has also been isolated from moribund black sea bream Acanthopagrus schlegeli, yellowfin sea bream A. latus, Japanese sea bass Lateolabrax japonicus, and red drum Sciaenops ocellatus suffering from the same syndrome. Each isolate was virulent to the respective fish. Recently, a similar syndrome, flounder infectious necrotizing enteritis, also caused by V. carchariae in summer flounder Paralichthys dentatus, was reported in Rhode Island. The extracellular products (ECPs) of V. carchariae strains EmI82KL (from grouper), Rd (from red drum), and SfUSA (from summer flounder, U.S.A.) were virulent to the grouper or red drum. A 33-kDa serine protease partially purified from the ECP of strain EmI82KL was lethal to the fish. All the moribund or killed fish exhibited gastroenteritis except those killed within 12 hours. This report is the first to show that intraperitoneal injection of the ECP or protease in the fish is virulent and can reproduce gastroenteritis. The serine protease was suggested as a major toxin in the grouper or red drum secreted by V. carchariae.     

Some aspects of the reproductive biology of Acanthopagrus spp. (Family: Sparidae)

Changes in the seasonal development of the gonads in Acanthopagrus latus and A. cuvieri over an annual reproductive cycle are described. There is one major spawning period from January to March. Hermaphrodite A. latus and A. cuvieri constituted 5.8% and 5.7% of the total sample respectively. The histological changes in the ovary, testis and ovo-testis in both species are described. Fecundity estimates for A. latus , 27.5–31.8 cm, ranged from 1 362 137 to 2 152 993, and estimates for A. cuvieri , 47.1–63.5 cm, ranged from 308 273 to 1 693 365.     

Monogenea of Chinese marine fishes. XIV. Two new species of Microcotylidae from fishes of the South China Sea

Two new species of microcotylid monogeneans are described. Solostamenides platyorchis n. sp. was obtained from the gills of Mugil cephalus (Mugilidae) and Polylabroides guangdongensis n. sp. from the gills of Sparus macrocephalus, S. berda and Acanthopagrus latus (Sparidae). Solostamenides platyorchis is morphologically similar to S. mugilis (Vogt, 1878) Unnithan, 1971 and S. pseudomugilis (Hargis, 1956) Unnithan, 1971 in the structure of the copulatory organ, but differs from them in the number, arrangement and shape of the testes. Features of P. guangdongensis distinguishing it from other species of the genus include a copulatory organ lacking small spines and an extremely long polar filament on the egg. In view of this species, we suggest omitting the presence of small spines on the copulatory organ as a diagnostic character of the genus Polylabroides Mamaev & Parukhin, 1976.     

Resolution of the Acanthopagrus black seabream complex based on mitochondrial and amplified fragment-length polymorphism analyses

In this study, DNA analyses were employed to verify the identity of six morphologically similar species that occur in the coastal waters of Taiwan: the black seabream complex (Acanthopagrus latus, Acanthopagrus schlegelii, Acanthopagrus sivicolus, Acanthopagrus taiwanensis, Acanthopagrus chinshira and Acanthopagrus pacificus). Amplified fragment-length polymorphism (AFLP) analyses clearly distinguished the same six species that are morphologically diagnosable based on subtle differences in scale counts and anal-fin colouration. In contrast, mitochondrial DNA analyses based on cytochrome b gene sequences did not distinguish individuals of A. schlegelii and A. sivicolus, reflecting either historical introgression or recent speciation and incomplete sorting of their mitochondrial lineages. Phylogenetic relationships among these six north-west Pacific Ocean species of Acanthopagrus analysed using AFLP data were consistent with scale rows above the lateral line (TRac), sperm ultrastructure and geographical distribution. The study provides molecular tools for future research relevant to improved management of these resources, and an increased understanding of the evolutionary history of this radiation.     

Significant population genetic structure of yellowfin seabream Acanthopagrus latus in China

The yellowfin seabream Acanthopagrus latus is widely distributed throughout the Indo‐West Pacific. The genetic analyses of mtDNA control region sequence variation in samples from Chinese waters revealed a pattern of genetic structure between southern and northern samples (P < 0·05) and high levels of genetic diversity in this species. Significant isolation by distance between southern and northern locations (Mantel test r = 0·35, P = 0·04) and among northern populations (r = 0·55, P = 0·01) indicated that ocean straits and other barriers substantially limit gene flow. Phylogeographical analysis also revealed two major divergent mtDNA lineages across Chinese waters. For conservation, A. latus populations in Chinese waters should be divided into at least two management units for protection.     

Retinoid composition and retinal localization in the eggs of teleost fishes

Retinoids in the eggs of four teleosts, chum salmon (Oncorhynchus keta), black porgy (Acanthopagrus schlegeli), marbled flounder (Pleuronectes yokohamae), and stingfish (Inimicus japonicus), were analyzed by high performance liquid chromatography. Retinal (RAL1) or both RAL1 and 3,4-didehydroretinal (RAL2) were major or exclusive retinoids in the eggs of every species examined. In O. keta eggs, both RAL1 and RAL2 were present at the ratio of approximately 3:4, whereas RAL1 was the only retinal in the eggs of the other three marine species. RAL1 was the exclusive retinoid in the eggs of P. yokohamae and I. japonicus, whose eggs lack lipid bodies. In the eggs of O. keta and A. schlegeli, which have lipid bodies, retinylesters were also detected, and retinals composed 69% and 93%, respectively, of total retinoids. In O. keta eggs, retinals were present mostly in the aqueous part and were bound to a protein homologous to lipovitellin 1, an amphibian yolk protein, and retinylesters were located in lipids. These results indicate that retinals are the essential mode of retinoid storage in eggs of teleosts and they are the precursors of functional retinoids, such as retinoic acid and visual pigment chromophores. Retinylesters are additional retinoids that accompany lipid accumulation.     

Chromosome set manipulations and hybridization experiments in gilthead seabream (Sparus aurata). II. Assessment of diploid and triploid hybrids between gilthead seabream and red seabream (Pagrus major)

The experiments were designed to evaluate the suitability for mariculture of the diploid and triploid hybrids of gilthead seabream Sparus aurata and red seabream Pagrus major , both of which are members of the Sparidae family. Performance testing of the hybrids was carried out in comparison with the parental species under the same controlled environment. The reciprocal diploid hybrids as well as the triploid hybrid did not exhibit any significant growth advantage over diploid parental species either before or after sexual maturity. The adults, both reciprocal diploid hybrids and triploid hybrid (female S. aurata × male P. major ), were clearly immature and had only vestigial gonads; neither ovaries nor released milts were observed. Histological examination of the gonads, carried out during associated periods of the first and second maturation cycles of the parental species, showed that all the hybrids were completely sterile. Despite their sterility, the growth of the hybrids did not display any positive effect, and for this reason their commercial culture appears to be questionable. On the other hand, the use of sterilization through hybridization and chromosome set manipulation may be important when there is a need to restrict the ecological impact on a wild population.     

Review of the Acanthopagrus latus complex (Perciformes: Sparidae) with descriptions of three new species from the Indo‐West Pacific Ocean

Acanthopagrus latus, long considered a single valid Indo‐West Pacific Ocean species, characterized by having yellow pelvic, anal and caudal fins, is reviewed and separated into A. latus (east Asian shelf) and Acanthopagrus longispinnis (Bengal Bay), and three new species: Acanthopagrus morrisoni sp. nov. (north‐western Australia), Acanthopagrus arabicus sp. nov. [Middle East (except for the Red Sea) to coasts of Iran and Pakistan, and western Indian coast] and Acanthopagrus sheim sp. nov. (The Gulf). Although A. latus as redefined considerably varies in morphology and colouration, it can be recognized as a discrete east Asian endemic, with the following nominal species being junior synonyms: Chrysophrys auripes, Chrysophrys xanthopoda, Chrysophrys rubroptera and Sparus chrysopterus. Chrysophrys novaecaledoniae, known only from the holotype (type locality: Nouméa, New Caledonia), is a questionable junior synonym of A. latus, the lack of subsequent collections suggesting that the type locality is erroneous. Acanthopagrus longispinnis is differentiated from the other species in the complex by consistently having 12 dorsal‐fin spines and a much larger second anal‐fin spine, 21–26% (mean 23%) of standard length (L_S) (v. 14–24%, mean 18–21% in the other four species). Acanthopagrus morrisoni sp. nov. has the entire caudal fin yellow with a wide black posterior margin (persisting in preserved specimens) and consistently 3 ½ scale rows between the fifth dorsal‐fin spine base and the lateral line. Acanthopagrus sheim sp. nov. has the pelvic, anal and lower caudal fins vivid yellow, with two (rarely three) small black blotches on the lower inter‐radial membranes between the spinous and soft dorsal‐fin rays. Acanthopagrus arabicus sp. nov. consistently has 4 ½ scale rows between the fifth dorsal‐fin spine base and the lateral line, whereas A. latus always has black streaks proximally on the inter‐radial membranes between the yellow anal‐fin rays. A neotype and lectotye, respectively, are designated for A. latus and A. longispinnis. The p‐distance (net nucleotide substitutions per site) of partial mitochondrial 16s ribosomal RNA genes (538 bp) among the above species (except A. longispinnis) and three other congeners (Acanthopagrus berda, Acanthopagrus pacificus and Acanthopagrus bifasciatus) strongly indicates that each is a distinct species. A key is provided for the 20 species of Acanthopagrus currently known from the Indo‐West Pacific Ocean.     

Exposure of eggs to solar UV‐B leads to reduced hatching rates in two sparid fishes,red sea bream Pagrus major and black sea bream Acanthopagrus schlegeli

Hatching success was examined under exposure to solar ultraviolet radiation (UVR) using filters to give three different light conditions [C1: UV‐B, UV‐A and photosynthetically active radiation (PAR), C2: UV‐A and PAR, C3: PAR] in red Pagrus major and black Acanthopagrus schlegeli sea bream. Hatching rate of both species was reduced by an exposure over a 2 day period to UVR and was not significantly different between two species under the three light conditions.     

寄生于南海鱼类中的单殖吸虫一新种和一新纪录(吸虫纲: 单殖目)

报道了寄生于中国南海的芝麻斑鱼Epinephelus rhyncholepis(Bleeker)(Serranidae)上的香港拟大杯虫Megalocotyloides hongkongensis sp.nov.和寄生于黑鲷Acanthopagrus schlegeli(Bloch)(Sparidae)上的鲷裸盘虫Anoplodiscus spari(Yamaguti,1958)。前者为新种,隶属于分室科Capsalidae (Barid,1853)、轮足亚科Trochpodinae、拟大杯足属Megalocotyoides;后者为中国新纪录,隶属于裸盘虫科Anoplodiscidae(Tagliani,1912)、裸盘虫属Anoplodiscus。香港拟大杯虫Megalocotyloides hongkongensis sp.nov.具分室科、Trochopodinae亚科的形态特征。虫体背腹扁平,呈长椭圆形,体表光滑无棘。前端腹面有一对前吸器,成对吸盘状结构,通过一头冠在前背面联系,有头腺。眼点2对,位于咽前。后吸器盘状,无柄,分成5隔和周边5个小隔室,中央小室缺;后吸盘边上有肌肉缘,周围有精致的圆齿状边缘膜,边缘小钩14个;中央大钩3对,有肌肉纤维支持着,第1对钩大,远端尖,近端钝,分叉,有明显的肌腱通过大钩的分叉牵拉,第2对钩细长,远端有刺钩,第3对钩尖细,远端钩尖略弯曲,3对中央大钩成直线纵向排列,有肌腱牵引。口开于咽中央,咽肌肉质,发达,呈5瓣状。食道不明显或缺。两肠支前端达咽的水平处,末端终止于后吸器前,呈树枝状分布,末端不汇合。睾刃个并列,椭圆形,前端略尖,位于体中部。输出管在中部吻合形成输精管,呈盘曲长管状,阴茎囊椭圆形,靠近卵巢的右上角,阴茎细长,卷曲在阴茎囊内。阴茎复合体包含有肌肉质的阴茎、射精管、前列腺球和前列腺储藏囊。阴茎囊远端与子宫远端联合形成生殖腔,其生殖孔开口于体左侧的前吸器旁。卵巢圆球形,位于睾丸前,输卵管自卵巢发出后,向前略大成卵模,周围有发达的梅氏腺,子宫粗短,开口于生殖腔。卵黄腺呈滤泡状,自咽水平处随肠支,略呈对称状分布至后吸器前,贮卵黄囊位于卵巢前。阴道富肌肉质,管状,近端膨大形成受精囊,远端窄,开口于共同生殖腔下方。卵呈多面体形,虫卵的一端有一根卷曲的长极丝。鲷裸盘中Anoplodiscus spari(Yamaguti,1958)具裸盘虫科Anoplodiscidae、裸盘虫属Anoplodiscus的形态特征。虫体背腹扁平,体前端有一对假吸盘,开口于体外,后吸器盘状,无钩,不分室。具2对眼点,咽发达。食道不明显或缺。单支肠支不对称地呈树枝状分布,末端终止于后吸器前。睾丸单个,圆球形,位于体中部。具贮精囊,阴茎囊长,管状,具有几丁质支持器,卵巢卵圆形,位于睾丸前,具受精囊和阴道,卵黄腺发达,呈大滤泡状,自交接器水平处随肠支,略呈对称状分布至后吸器前。     

Consistently outstanding recruitment of five species of fish to a seagrass bed in Botany Bay,NSW

Abstract Variability in abundance of fish associated with beds of the seagrass Zostera capricorni was documented at 16 sites in NSW. Samples were collected from each site by seine net every 3 months for 2.5 years. One site had significantly greater abundances of recruits of five species of economically important fish during all three recruitment seasons. This site was within a small, constructed harbour in Botany Bay. Between June and March of each year abundances of five species (Acanthopagrus australis, Rhabdosargus sarba, Girella tricuspidata, Achoerodus viridis and Meuschenia trachylepis) were up to 73 times greater than abundances at the other 15 sites. However, at other times during the year, there was no significant difference between this site and the 15 others. Understanding the processes that contribute to the success of this modified site as a recruitment sink should aid in increasing the potential of other areas as fish nursery habitat, and contribute to the management and productivity of fish populations.     

Molecular cloning and sequencing of Australian black bream Acanthopagrus butcheri and barramundi Lates calcarifer fish growth hormone cDNA using polymerase chain reaction.

The complementary DNA (cDNA) encoding the preprotein growth hormone (pre-GH) from two Australian marine fish species, namely Acanthopagrus butcheri and Lates calcarifer, have been isolated, cloned and sequenced. The sequences were amplified from reverse transcribed total RNA of whole brains using Polymerase Chain Reaction (PCR) and oligonucleotide primers corresponding to the 5' and 3' regions of Pagrus major. Use of PCR offers a rapid method of isolating fish GH cDNA sequences for commercial and taxonomic applications. Sequence comparison indicates a high degree of conservation for GH cDNAs within the family Sparidae.     

Experimental infection of several fish species with the causative agent of Kuchijirosho (snout ulcer disease) derived from the tiger puffer Takifugu rubripes.

Kuchijirosho (snout ulcer disease) is a fatal epidemic disease which affects the tiger puffer, Takifugu rubripes, a commercial fish species in Japan and Korea. To assess the possibility that non-tiger puffer fish can serve as reservoirs of infection, 5 fish species were challenged by infection with the extracts of Kuchijirosho-affected brains from cultured tiger puffer: grass puffer T. niphobles, fine-patterned puffer T. poecilonotus, panther puffer T. pardalis, red sea bream Pagrus major, and black rockfish Sebastes schlegeli. When slightly irritated, all these species, especially the puffer fish, exhibited typical signs of Kuchijirosho, i.e., erratic swimming, biting together and bellying out (swelling of belly), as generally observed in tiger puffers affected by Kuchijirosho. Although the mortalities of the 2 non-puffer species were lower, injection of the extracts prepared from the brains of both inoculated fish into tiger puffer resulted in death, indicating that the inoculated fish used in this experiment have the potential to be infected with the Kuchijirosho agent. Condensations of nuclei or chromatin in the large nerve cells, which is a major characteristic of Kuchijirosho, were histopathologically observed to some extent in the brains of all kinds of puffer fish species infected. These findings suggest that the virus can spread horizontally among wild and cultured puffers and even among fishes belonging to different orders.     

Pyrrolo- and pyridoazepine alkaloids as chemical markers in Stemona species

Broad-based phytochemical investigations on 31 Stemona species and geographical provenances led to an overview concerning characteristic accumulation trends and the distribution of different Stemona alkaloids. Two major metabolic differences suggested a taxonomic segregation of the complex Stemona tuberosa group from the other species, and was supported by morphological characters. Whereas most of the Stemona species were characterised by protostemonine type alkaloids, the S. tuberosa group clearly deviated by accumulation trends towards tuberostemonine or croomine derived alkaloids belonging to two different skeletal types. Also of chemotaxonomic relevance was the structural divergence of protostemonine type alkaloids into pyrrolo- or pyridoazepine derivatives represented by stemofoline or oxystemokerrine, respectively, as major constituents. Their common occurrence in different provenances of S. curtisii, also deviating from the other species by various chromosome numbers, deserves special taxonomic attention. Species specific chemical markers were given by the unique accumulation of didehydrostemofoline (=asparagamine A) in S. collinsae and stemokerrine in S. kerrii. In contrast to previous reports, no bisdehydro derivatives with an aromatic pyrrole ring were detected supporting the hypothesis that these alkaloids are artifacts. A new stereoisomer of tuberostemonine was isolated and identified by spectroscopic methods.