Black Porgy Research Articles

A new myxozoan parasite, Myxobolus allami sp. n. (Myxozoa: Myxobolidae) from the intestinal wall of Sparidentex hasta (Valenciennes) in Arabian Gulf.

Myxobolus allami sp. n. is described from the intestinal wall of the silvery black porgy, Sparidentex hasta (Valenciennes), off Saudi Arabian coast of Arabian Gulf. Two of 20 examined fish were found to be infected with irregular-shaped plasmodia 3-8 mm long × 2-3 mm wide. Mature myxospores are subspherical to elliptical in the valvular view and oval in the sutural view, and are 11-13 (12) µm long, 7-8 (7.5) µm wide and 10-12 (10.8) µm thick. Spores have relatively thin valves and mostly (~ 72%) end with short caudal appendages of ~3 µm long. The spores also have two polar capsules, which are oval to elliptical and measure 5-7 (5.7) µm in length and 2-3 (2.7) µm in width. Polar filaments are coiled, with three turns. Transmission electron microscopy revealed that caudal appendages originated from the sutural edge at the posterior pole of the myxospore with density similar to that of its valves. The SSU rRNAgene sequence of the present species does not match any available sequences in GenBank. Phylogenetically, this species is sister to Myxobolus khaliji Zhang, Al-Qurausihy et Abdel-Baki, 2014 within a well-supported clade of Myxobolus-Henneguya with species infecting marine fishes. The combination of molecular data and morphological differences between this and other species of Myxobolus Bütschli, 1882 lead us to propose that the present form be established as a new species, M. allami. The present study also provides more evidence for the idea that caudal appendages cannot be reliably used to distinguish the species of the genera Myxobolus and Henneguya Thélohan, 1892.

The impact of religious release fish on conservation

In Taiwan, many hatchery-reared fish are released into wild waters for various reasons. Among those released individuals, few are documented by government agencies and academics, with almost no documentation by religious groups. Religious release data is scarce and the influence of released fish on the environment is not fully understood by the government, academics or religious groups. This study aimed to (1) investigate public cognition surrounding the relationship between the religious release of fish and conservation via questionnaire, (2) conduct two batches of mark and recapture studies fish used for religious release and (3) assess the impact of religious release fish on conservation based on the natural marks of recaptured specimens. Beginning in 2015, two batches of prayer black porgy (Acanthopagrus schlegelii), which were marked, released and recaptured were surveyed in cooperation with a Buddhist group. The results for overall respondents surveyed by questionnaire, 45% indicated that they were unsure of the impact of religious release fish on conservation. Based on the values of oxygen stable isotope in the core area of the otoliths discrimination, the hatchery-reared stock is thought to contribute to approximately 61% of the total black porgy population in the northern waters of Taiwan. The length distribution between hatchery-reared stocks and wild stocks was similar, suggesting that the two stocks that survive at sea may not interact with each other. The results of this study can be used as evidence for the impact of a religious release fish on environmental conservation.

Limited adaptation to non-natal osmotic environments at high water temperature in euryhaline wanderer fishes

Gradual transfer experiments were conducted to see whether Japanese dace Tribolodon hakonensis (freshwater species) and Japanese black porgy Acanthopagrus schlegelii (marine species) could acclimate to high and low temperatures in natal and non-natal osmotic environments. Two groups of each species, one acclimated to their natal osmotic environment and the other to a non-natal osmotic environment, were exposed to gradual temperature changes. Under high temperature conditions, the plasma osmolality (Posm) of both species approached the osmolality of ambient water, and high mortality was observed in the non-natal osmotic environments but not in the natal osmotic environments. In contrast, there was no clear evidence that the osmoregulatory capacity of either species had declined under low temperature conditions in the natal and non-natal osmotic environments. Limited adaptation of these fishes to non-natal osmotic environments at high temperature suggests that global warming may impair their entry to non-natal habitats.

Molecular cloning and expression pattern of IGFBP-2a in black porgy (Acanthopagrus schlegelii) and evolutionary analysis of IGFBP-2s in the species of Perciformes.

Insulin-like growth factor-binding protein-2 (IGFBP-2) plays a key role in regulating growth and development by its affinity with insulin-like growth factors (IGFs). In this study, we cloned the coding sequence (CDS) of IGFBP-2a from the black porgy (Acanthopagrus schlegelii) muscle and identified that the full-length CDS of IGFBP-2a was 882bp. Real-time quantitative PCR revealed that IGFBP-2a was most abundant in the liver of the black porgy and backcross breed (F1♀×black porgy♂) but remained lower in each tested tissue in self-cross breed (F1♀×F1♂). In addition, the IGFBP-2a expression in the liver of three breeds showed a negative correlation with their growth rates, indicating that the IGFBP-2a played a growth-inhibiting role in the three breeds. We further identified 810bp IGFBP-2b gene from the draft genome of black porgy. Finally, we examined the IGFBP-2a and IGFBP-2b genes by scanning the genomes of the species of Perciformes and found the IGFBP-2 gene duplication took place earlier than the divergence of perciform species. Interestingly, six positively selected sites were detected in both Perciformes IGFBP-2 genes, although both genes were identified to be under purifying selection. Specially, these positively selected sites were located in the functional domains, suggesting these sites played key roles in the growth of Perciformes. Our study partially explains the molecular basis for the prepotency in black porgy hybrids, which will provide guidance for their cultivation in the future.

Activation of the brain-pituitary-gonadotropic axis in the black porgy Acanthopagrus schlegelii during gonadal differentiation and testis development and effect of estradiol treatment

Previous studies revealed an estradiol (E2)-dependent peak in brain activity, including neurosteroidogenesis and neurogenesis in the black porgy during the gonadal differentiation period. The brain-pituitary-gonadotropic axis is a key regulator of reproduction and may also be involved in gonadal differentiation, but its activity and potential role in black porgy during the gonadal differentiation period is still unknown. The present study analyzed the expression of regulatory factors involved in the gonadotropic axis at the time of gonadal differentiation (90, 120, 150 days after hatching [dah]) and subsequent testicular development (180, 210, 300 dah). In agreement with previous studies, expression of brain aromatase cyp19a1b peaked at 120 dah, and this was followed by a gradual increase during testicular development. The expression of gonadotropin subunits increased slightly but not significantly during gonadal differentiation and then increased significantly at 300 dah. In contrast, the expression of brain gnrh1 and pituitary gnrh receptor 1 (gnrhr1) exhibited a pattern with two peaks, the first at 120 dah, during the period of gonadal differentiation, and the second peak during testicular development. Gonad fshr and lhcgr increased during gonadal differentiation period with highest transcript level in prespawning season during testicular development. This suggests that the early activation of brain gnrh1, pituitary gnrhr1 and gths, and gonad gthrs might be involved in the control of gonadal differentiation. E2 treatment increased brain cyp19a1b expression at each sampling time, in agreement with previous studies in black porgy and other teleosts. E2 also significantly stimulated the expression of pituitary gonadotropin subunits at all sampling times, indicating potential E2-mediated steroid feedback. In contrast, no significant effect of E2 was observed on gnrh1. Moreover, treatment of AI or E2 had no statistically significant effect on brain gnrh1 transcription levels during gonadal differentiation. This indicated that the early peak of gnrh1 expression during the gonadal differentiation period is E2-independent and therefore not directly related to the E2-dependent peak in brain neurosteroidogenesis and neurogenesis also occurring during this period in black porgy. Both E2-independent and E2-dependent mechanisms are thus involved in the peak expression of various genes in the brain of black porgy at the time of gonadal differentiation.

The Kiss2/GPR54 system stimulates the reproductive axis in male black porgy, Acanthopagrus schlegelii

Although it is well established that the Kiss1/GPR54 system stimulates the reproductive axis in mammals, its functional roles, especially in male reproduction of non-mammalian species, is less clear. In this study, we have isolated the full-length kiss2 and gpr54 cDNAs from black porgy (Acanthopagrus schlegelii). The Kiss2 precursor expressed from kiss2 comprises 124 amino acids and contains a highly conserved 10-amino acid sequence, Kiss2-10 (FNFNPFGLRF). GPR54 comprises 375 amino acid residues and contains distinct characteristics of G protein-coupled receptors. Real-time PCR analysis indicated that kiss2 and gpr54 were expressed highly in the brain regions. Moreover, intraperitoneal injection of porgy Kiss2-10 could stimulate genes expression of the gpr54, gnrh1, gnrh3, fshβ, lhβ, p450c17, star, and ar, and the serum testerone level in male black porgy. Our findings demonstrate that the Kisspeptin stimulates the male reproductive axis in black porgy.

Discrimination of Wild and Hatchery-Reared Black Porgy <i>Acanthopagrus schlegelii</i> Using Otolith Elements Analysis of Magnesium and Manganese

Due to the decreasing resources of both inshore and offshore fisheries, many organizations have released fry to enhance their stock in recent years. The discrimination between wild and hatchery-reared individuals must be performed to assess the efficiency of the release. Fresh groundwater is generally used by hatchers in southwesternTaiwanto decrease salinity and to promote the growth of larvae prior to feeding; thus, the elemental composition of the otolith may be different in stocks, and this difference may be used for identification. This study used Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) to analyze the trace elements in the nuclei of otoliths from black porgy Acanthopagrus schlegelii, including six hatchery reared specimens from the Tainan County, three recaptured marked and ten captured unmarked specimens from the Miaoli County in Northwestern coast of Taiwan. Among the six hatchery and three recaptured marked specimens, which ranged from 4.9 to23.4 cmin body length, the nucleus zone (relative to within5 cmin size growth) of the otoliths showed higher magnesium concentrations than that observed on both edges. The distribution was similar to an inverse “V” shape. The otoliths also showed lower manganese concentrations near the nucleus and had higher values near the edges, resulting in a distribution similar to a “U” shape. According to the appeared shape of Mg2+/Ca2+ and Mn2+/Ca2+ ratio in the central area of the nucleus zone, this study determined six specimens which were from hatchery reared and three specimens were from wild among ten unmarked specimens captured from the Northwestern coast of Taiwan. Under the conditions used in this study, the absorption of calcium into the otolith was active and required energy in the seawater and freshwater, while the incorporation of magnesium and manganese was passive and was primarily affected by diffusion.

The Effects of Continuous Acoustic Stress on ROS Levels and Antioxidant-related Gene Expression in the Black Porgy (Acanthopagrus schlegelii).

Hao-Yi Chang, Tzu-Hao Lin, Kazuhiko Anraku, and Yi Ta Shao (2018) Short-term exposure to strong underwater noise is known to seriously impact fish. However, the chronic physiological effects of continuous exposure to weak noise, i.e. the operation noise from offshore wind farms (OWF), remain unclear. Since more and more OWF will be built in the near future, their operation noise is an emerging ecological issue. To investigate the long-term physiological effects of such underwater noise on fish, black porgies (Acanthopagrus schlegelii) were exposed to two types of simulated wind farm noise-quiet (QC: 109 dB re 1 μPa / 125.4 Hz; approx. 100 m away from the wind turbine) and noisy (NC: 138 dB re 1 μPa / 125.4 Hz; near the turbine)-for up to 2 weeks. Measurement of auditory-evoked potentials showed that black porgies can hear sound stimuli under both NC and QC scenarios. Although no significant difference was found in plasma cortisol levels, the fish under NC conditions exhibited higher plasma reactive oxygen species (ROS) levels than the control group at week 2. Moreover, alterations were found in mRNA levels of hepatic antioxidant-related genes (sod1, cat and gpx), with cat downregulated and gpx upregulated after one week of QC exposure. Our results suggest that the black porgy may adapt to QC levels of noise by modulating the antioxidant system to keep ROS levels low. However, such antioxidant response was not observed under NC conditions; instead, ROS accumulated to measurably higher levels. This study suggests that continuous OWF operation noise represents a potential stressor to fish. Furthermore, this is the first study to demonstrate that chronic exposure to noise could induce ROS accumulation in fish plasma.

A comparative transcriptomic study on developmental gonads provides novel insights into sex change in the protandrous black porgy (Acanthopagrus schlegelii)

Protandrous black porgy (Acanthopagrus schlegelii) is a popular and valuable commercial marine fish in China and East Asian countries. Controlling and managing its breeding has been an imperative step towards obtaining a sustainable supply of this fish in aquaculture production systems. Therefore, study on the molecular mechanisms of sex change in black porgy has both scientific and commercial importance. Previously, we identified some candidate genes related to sex determination and differentiation from a high-quality genome assembly of the black porgy. In the present study, transcriptome sequencing of developmental gonads (including testis, ovotestis and ovary) of black porgy was performed to further investigate the sex-change mechanisms. Our results showed that the highly expressed male-related genes (dmrt1, piwi1, piwi2, sox9, sox30 and amh) at the male phase were significantly down-regulated to a substantial degree at the intersexual stage, and the female-related genes (jnk1, vasa, wnt4, figla and foxl2) were distinctly up-regulated when the fish grows into a female adult, suggesting the potential roles of these genes in sex change of the black porgy. These data also support a previous hypothesis that the femaleness will be switched on when the testis is entering the degenerated stage through the diminished dmrt1 expression. Our transcriptome data provide a very useful genomic resource for future studies on sex change and practical aquaculture in the black porgy.

감성돔의 음향임피던스 측정

This study was aimed at measuring the acoustic impedance of Japanese black porgy to estimate its sustainable production and resources. The acoustic impedance need to know density contrast and sound speed contrast of target fish. The density contrast is obtained by the Pipette method and sound speed contrast is obtained by the Time-of-flight method. To get basic information on the Japanese black porgy in the experiment, 10 different sizes used. As a result, the body length increases as the weight of the Japanese black porgy was increased. The correlation between the body length and density contrast of the Japanese black porgy was very low. Also, the acoustic speed contrast was shown at very low correlation. However, due to lack of 20~25cm of Japanese black porgy, the standard deviation value is not constant. The impedance results of Japanese black porgy will should be used as basic date of acoustic scattering characteristic and identification of fish.

Draft genome of the protandrous Chinese black porgy, Acanthopagrus schlegelii

BackgroundAs one of the most popular and valuable commercial marine fishes in China and East Asian countries, the Chinese black porgy (Acanthopagrus schlegelii), also known as the blackhead seabream, has some attractive characteristics such as fast growth rate, good meat quality, resistance to diseases, and excellent adaptability to various environments. Furthermore, the black porgy is a good model for investigating sex changes in fish due to its protandrous hermaphroditism. Here, we obtained a high-quality genome assembly of this interesting teleost species and performed a genomic survey on potential genes associated with the sex-change phenomenon.FindingsWe generated 175.4 gigabases (Gb) of clean sequence reads using a whole-genome shotgun sequencing strategy. The final genome assembly is approximately 688.1 megabases (Mb), accounting for 93% of the estimated genome size (739.6 Mb). The achieved scaffold N50 is 7.6 Mb, reaching a relatively high level among sequenced fish species. We identified 19 465 protein-coding genes, which had an average transcript length of 17.3 kb. By performing a comparative genomic analysis, we found 3 types of genes potentially associated with sex change, which are useful for studying the genetic basis of the protandrous hermaphroditism.ConclusionsWe provide a draft genome assembly of the Chinese black porgy and discuss the potential genetic mechanisms of sex change. These data are also an important resource for studying the biology and for facilitating breeding of this economically important fish.

Hematological and histological changes of black porgy Acanthopagrus schlegeli in ozonated recirculating systems

This study evaluated hemato-histological changes of black porgy in recirculating aquaculture systems (RAS) with three different ozone doses (no ozone, 20 g, and 40 g ozone/kg feed day−1). During the 44-day study, black porgy did not show significant behavior changes or mortalities in both the ozonated systems displaying average total residual oxidants concentrations of 0.12 and 0.25 mg/L. There were no differences in growth and blood parameters among the systems. However, histological alterations on gills and livers were observed in both the treatment systems. In the higher ozone dose, signs of cellular damage were more apparent. Although the ozone doses did not manifest a serious adverse effect on growth and hematological observations in this short-term study, an ozone dose should not exceed 20 g ozone/kg feed day−1 for black porgy based on the histological result. In order to use ozone in a seawater RAS, further studies will be needed to evaluate long-term effects of total residual oxidants.

Robust gdf9 and bmp15 expression in the oocytes of ovotestes through the Figla-independent pathway in the hermaphroditic black porgy, Acanthopagrus schlegelii.

More than 1,500 fish species are hermaphroditic, but no hermaphroditic lineage appears to be evolutionarily ancient in fishes. Thus, whether more than one sex at a time was present during the evolutionary shift from gonochorism to hermaphroditism in fishes is an intriguing question. Ectopic oocytes were created in the ovotestes of protandrous black porgy via the withdrawal of estradiol (E2) administration. These ectopic oocytes reprogrammed the surrounding cells, which changed from Sertoli cells to follicle-like cells. We observed that gdf9 and bmp15 expression was localized in the primary oocytes and gradually decreased after oocytes entered a secondary oocyte stage. Robust expression of gdf9 and bmp15 in ectopic oocytes was associated with the surrounding Sertoli cells. However, blocking Cyp19a1a activity and increasing androgen levels did not stimulate the expression of gdf9 and bmp15. Thus, the robust gdf9 and bmp15 expression was not related to the inappropriate male microenvironment. Furthermore, in vitro data demonstrated that gdf9 and bmp15 were not downstream genes of Figla signaling. Therefore, our results suggest that there are two independent mechanisms, a Figla-dependent pathway and a Figla-independent pathway, by which oocyte-surrounding cells are altered from a male somatic fate to a female somatic fate. This functional switch might clarify how oocytes created an appropriate microenvironment during the transition from the ancient gonochorism to the present hermaphroditism.

Molecular cloning, mRNA expression, and characterization of calm×odulin genes in hybrids of Acanthopagrus schlegeli (♀)× Pagrosomus major ( ♂ )

PDF HTML阅读 XML下载 导出引用 引用提醒 黑鲷♀×真鲷♂反交子代与黑鲷的CaM基因克隆与mRNA表达分析 DOI: 作者: 作者单位: 1. 江苏省海洋水产研究所, 江苏省海水鱼类遗传育种重点实验室, 江苏 南通 226007;2. 南京师范大学 生命科学学院 生物多样性与生物技术重点实验室, 江苏 南京 210023 作者简介: 陈淑吟(1966-),女,博士,研究员,研究方向为鱼类种质资源与遗传育种.E-mail:shuyinchen89@163.com;李鹏(1979-),并列第一作者,男,博士,副教授,研究方向为动物比较基因组与分子进化.E-mail:biolipeng@163.com 通讯作者: 中图分类号: Q96 基金项目: 江苏省海洋与渔业局水产三新工程重大项目（D2015-17）；南通市科技局应用基础研究项目（MS12015071，MS12015070）. Molecular cloning, mRNA expression, and characterization of calm×odulin genes in hybrids of Acanthopagrus schlegeli (♀)×Pagrosomus major (♂) Author: Affiliation: 1. Institute of Oceanology & Marine Fisheries, Nantong 226007, China;2. Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为分析黑鲷♀×真鲷）反交子代在生长、发育等经济性状优于黑鲷亲本（PACaM与在仔鱼及2龄成鱼不同组织的表达特征。研究结果表明，基因cDNA全长1241 bp，均具有一个450 bp的开放阅读框，编码149个氨基酸，分子量约16.84 kD，等电点为4.09；序列比对、结构比较等分析表明，在两种鱼的仔鱼及成鱼的脑与性腺中有较高表达；<0.05），在脑、肝及肾中的表达没有明显差异（基因在生长与繁殖中的重要作用。研究结果为鲷科属间杂交获得的子代与亲本性状差异的功能基因表达提供一些基础资料。 Abstract:The hybrid offspring from black porgy () have been successfully farmed in an attempt to develop new marine aquaculture species with optimal target traits. To analyze the molecular mechanism of different growth traits between parent fish (As) and hybrids (PA), the full-length cDNA sequences of ) from each were cloned and identified. The expression profiles of genes in six different tissues of two-year-old and 30 d larvae of F1 generation hybrids and pure individuals were evaluated and compared using real-time quantitative PCR. The gene is 1241 bp, both including an open reading frame (ORF) of 450 bp and encoding a peptide of 149 amino acids with an estimated molecular mass of 16.84 kD and a predicted isoelectric point (pI) of 4.09. Sequence alignment, structure comparison, and bioinformatics analyses showed that family. Functional domain analysis indicated that the protein has four EF-h and calcium-binding domains, with sixteen Ca2+ binding sites. are non-secretory and non-transmembrane proteins, and likely have their functional location in the cytoplasm. Quantification of expressed mRNA showed comparatively high levels in the brain and gonadal tissues of two-year-old fish and in larval fish. in gill, muscle, and gonadal tissue, as well as in larvae, but not significantly different in the brain, liver, or kidney tissues ( transcripts in the hybrid larvae, and the highest enrichment of in growth and development. This study provides a basis for further research into gene function and differing genetic traits between the parent and hybrid offspring of genus crosses of Sparidae. 参考文献 相似文献 引证文献

The Testis Is a Primary Factor That Contributes to Epigenetic Modifications in the Ovaries of the Protandrous Black Porgy, Acanthopagrus schlegelii.

In most hermaphroditic fish, the sexual phase of the gonad responds to external stimuli so that only one sex remains functional while the other sex becomes dormant. However, protandrous black porgy are male during their first two reproductive cycles. Estradiol (E2)-induced female growth results in a transient and immature female, and the sexual phase reverts from female to male after E2 is withdrawn. Conversely, excising the testis results in a precocious female when performed during the second reproductive cycle. We used these characteristics to study epigenetic modifications of cyp19a1a promoter in black porgy. Our results showed that higher levels of gonadotropins receptors were observed in testis than in ovary during the alteration of sexual phase from induced femaleness to maleness, and hCG treatment did not stimulate ovarian gene expression in male (1-yr-old maleness) and female phase (testis excision-induced femaleness) fish. The cyp19a1a promoter exhibited tissue- and lineage-specific methylation patterns. The follicle cells in the ovary had a hypomethylated (0%-20%) cyp19a1a promoter region. In the ovary, the first sign of female phase decision was decreased methylation levels and increased numbers of hypomethylated clones of cyp19a1a promoter during the natural sex change process. Similar methylation patterns were observed in the testis-removed ovary 1 mo after surgery, with no histological difference between the sham and the testis-removed fish. Conversely, there was no increase in methylation levels of cyp19a1a promoter in E2-fed fish. These results suggest that in the digonic gonad of black porgy, the testis is the primary tissue that affects epigenetics of the ovary.

Narrowed temperature adaptability in non-natal osmotic environments of two euryhaline wanderers, dace and black porgy: implications for seasonal habitat changes

Many euryhaline wanderer species exhibit seasonal habitat changes, and temperature is suggested to play a key role in this phenomenon. To examine this possibility, we tested the hypothesis that adaptable temperature ranges of euryhaline wanderers are narrower in a non-natal osmotic environment than in their natal osmotic environment using dace Tribolodon hakonensis, a freshwater born euryhaline fish, and black porgy Acanthopagrus schlegelii, a marine born euryhaline fish. In both species, all individuals survived for 48 h in all the tested temperatures in their natal osmotic environments. In non-natal osmotic environments, however, both low (dace: 6 °C, black porgy: 10 °C) and high temperatures (dace: 30 °C, black porgy: 33 °C) significantly reduced their survival. These results indicate that euryhaline wanderers have a narrowed adaptable temperature range in non-natal osmotic environments. The similar trend observed in these two species of freshwater and marine fishes suggests that this may be a general characteristic in euryhaline wanderers and could be one of the causes of their seasonal movements.

Evaluation of different commercial feeds on grow-out silver black porgy, Sparidentex hasta (Valenciennes), for optimum growth performance, fillet quality, and cost of production.

The objective of the study was to find a cost-effective feed from three commercial feeds, namely, Arasco (Saudi Arabia), Skretting (Turkey), and Biomar (Greece) for commercially producing silver black porgy (sobaity bream), Sparidentex hasta in Kuwait. For confidentiality, these feeds were randomly given code names, diets 1, 2, and 3, which were known only to the investigating staffs. The trash fish (diet 4) was used as the control. The experiment was conducted for 28 wk with grow-out sobaity bream (210.0 ± 0.51 g) using a flow-through system consisting of twelve 1-m3 tanks. There were three replicates for each treatment. Fish were fed two times daily at satiation level. The results showed that fish fed diet 2 resulted in significantly (P > 0.05) better growth performance, feed utilization, and higher fillet eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content compared to other diets. A comparison of fillet quality of cultured and wild sobaity bream showed no significant (P > 0.05) difference between sensory attributes, except that of ‘flavor’ in cooked fillets of wild sobaity bream. A simple economic analysis showed that the cost per kilogram of fish production was significantly (P > 0.05) the lowest in diet 2 (USD4.13), followed by diet 1 (USD5.70), diet 4 (USD6.33), and diet 3 (USD6.92). Thus, based on growth performance, feed utilization, cost of production, and nutritional quality of fillet, it is concluded that diet 2 may be recommended for commercial culture of sobaity bream in Kuwait. However, future research should focus on how to improve fillet quality of the cultured fish at par with wild fish by manipulating the feed formulation.

The complete mitochondrial genome of the hybrid of Pagrus major (♀) × Acanthopagrus schlegelii (♂)

The complete mitochondrial sequence of the hybrid from red bream (Pagrus major ♀) × black porgy (Acanthopagrus schlegelii ♂) was firstly determined by using the PCR-based method. The total length of the mitogenome genes of the hybrid was 17 028 bp in accordance with red bream, and it contained 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and one control regions. Compared with the complete mitochondrial genome of its parents, the results showed that the hybrid of P. major (♀) × A. schlegelii (♂) was consistent with a maternal inheritance. All protein initiation codons are ATG, except for COX1 that begins with GTG. The complete mitogenome of the hybrid of P. major (♀) × A. schlegelii (♂) provides an important data set for the exploration of mitochondrial inheritance mechanism.

Activation of brain steroidogenesis and neurogenesis during the gonadal differentiation in protandrous black porgy, Acanthopagrus schlegelii.

The early brain development, at the time of gonadal differentiation was investigated using a protandrous teleost, black porgy. This natural model of monosex juvenile fish avoids the potential complexity of sexual dimorphism. Brain neurogenesis was evaluated by histological analyses of the diencephalon, at the time of testicular differentiation (in fish between 90 and 150 days after hatching). Increases in the number of both Nissl-stained total brain cells, and Pcna-immunostained proliferative brain cells were observed in specific area of the diencephalon, such as ventromedialis thalami and posterior preoptic area, revealing brain cell proliferation. qPCR analyses showed significantly higher expression of the radial glial cell marker blbp and neuron marker bdnf. Strong immunohistochemical staining of Blbp and extended cellular projections were observed. A peak expression of aromatase (cyp19a1b), as well as an increase in estradiol (E2 ) content were also detected in the early brain. These data demonstrate that during gonadal differentiation, the early brain exhibits increased E2 synthesis, cell proliferation, and neurogenesis. To investigate the role of E2 in early brain, undifferentiated fish were treated with E2 or aromatase inhibitor (AI). E2 treatment upregulated brain cyp19a1b and blbp expression, and enhanced brain cell proliferation. Conversely, AI reduced brain cell proliferation. Castration experiment did not influence the brain gene expression patterns and the brain cell number. Our data clearly support E2 biosynthesis in the early brain, and that brain E2 induces neurogenesis. These peak activity patterns in the early brain occur at the time of gonad differentiation but are independent of the gonads.

Dietary n−3 LC-PUFA requirements in silvery-black porgy juveniles (Sparidentex hasta)

Abstract To determine the effects of n − 3 long chain polyunsaturated fatty acids (n − 3 LC-PUFAs) in juvenile silvery-black porgy ( Sparidentex hasta ), an eight-week feeding trial was conducted using five isonitrogenous and isolipidic semi-purified diets containing graded levels of n − 3 LC-PUFAs (0.1, 0.6, 1.2, 1.9 and 4.2%). Specific growth rate, body weight gain (WG) and feed conversion ratio (FCR) improved by increasing the dietary LC-PUFA content from 0.1% to 1.2%, and remained stable at higher n − 3 LC-PUFA levels. Apparent digestibility of nutrients did not change among different groups; however, fish fed 0.1% n − 3 LC-PUFAs showed the lowest lipid and protein retention values. The whole body and liver fatty acid profiles were correlated with the fatty acid profile of diets, especially for total monounsaturated fatty acids, DHA, EPA, ARA/EPA, DHA/EPA and n − 3/n − 6 ratios. Hemoglobin content and hemolytic and bactericidal activities were highest in fish fed 1.2% n − 3 LC-PUFAs. Fish fed 0.1% n − 3 LC-PUFAs had the highest hepatosomatic index, a change in the liver fatty acid profile, an increase in plasma cholesterol, triglyceride, low density lipoprotein, very low density lipoprotein and alkaline phosphatase concentrations; as well as a decrease in plasma glucose, which indicated signs of n − 3 LC-PUFA deficiency in this group. The broken-line regression method using FCR and WG data allowed us to estimate that the minimum nutritional requirement for n − 3 LC-PUFAs in silvery black porgy juveniles was between 0.6 and 0.8% in diets containing 15% lipids. Statements of relevance Silvery-black porgy ( Sparidentex hasta , Valenciennes 1830) is a commercially valuable carnivorous fish species in Oman Sea and Persian Gulf region for supporting marine aquaculture activities. Thus, the aim of present study was to provide insight into the nutritional requirements of silvery-black porgy, by evaluating the effects of dietary n − 3 LC-PUFA levels on growth performance, feed utilization, body composition and health indices in silvery-black porgy juveniles.