The brain plays a critical role in controlling reproduction through the hypothalamus-pituitary-gonadal (HPG) axis in vertebrates. Turbot (Scophthalmus maximus) has become an economically important marine fish in Europe and North China. Previous research investigating turbot reproduction has focused on the role of the HPG axis in regulating egg and sperm production. However, the morphology and histology of the organs in the HPG axis have not been studied. In this study, we investigated the morphology and histology of brains in female and male turbot at different stages of gonadal development. The results showed that the brains of both female and male turbot were composed of seven parts that are typical of advanced teleosts: the telencephalon, diencephalon, cerebellum, hypothalamus, pituitary gland, myelencephalon, and olfactory bulbs. The telencephalon was well-developed and contained five distinct lobes, with the contiguous diencephalon at the caudal portion. The torus longitudinales and rostral torus semicircularis of the mesencephalon flattened along the dorsal surface, and the rostral corpus cerebellum was located in the dorsal portion. The actual total brain volume in mature males was significantly greater (p<0.05) than that of females with gonadal development. Notably, the pituitary volume in male turbot significantly increased (p<0.05) from immature to mature stage, but this difference did not occur in females. The data together illustrate a distinct sex difference in the turbot brain during gonadal development, providing insight into their HPG axes.

本研究估计了大菱鲆收获体重性状的遗传参数和选育遗传进展。数据共包括3个世代（G0，G1，G2）的508个全同胞家系10952尾个体。G0，G1，G2的体重估计遗传力分别为0.11±0.08，0.18±0.09，0.17±0.07；世代间估计遗传力为0.19±0.04。每一世代母本和共同环境效应分别为0.10±0.04，0.14±0.04，0.13±0.03；世代间为0.12±0.01。G0和G1世代选择差分别为,18.24g和21.19g。对应的G1和G2世代的遗传进展为22.06g，11.93g；百分比表示分别为6.36%，3.52%。连续两代选择之后总遗传进展为10.10%。以上结果说明针对大菱鲆体重性状的选育项目是成功的。

利用限制性最大似然方法和贝叶斯方法分别估计大菱鲆养殖群体生长性状的遗传参数。利用39尾亲本进行人工授精育成28个后代家系，采集2462尾17月龄后代的收获体重。动物模型包括固定效应、协方差（孵化后110日龄的家系平均体重）、加性效应和残差。对于贝叶斯分析，根据后验条件分布的平均值和众数来估计遗传力和育种值。结果显示，对于加性效应，贝叶斯的后验均值（9320）是最高的，限制性最大似然方法的估计值（8088）次之，后验众数估计值最小（7849）。相应的三种遗传力估计值呈同样趋势。相应的三种育种值两两之间的皮尔逊相关系数均很高，最高的是后验均值和限制性最大似然方法的估计值（0.9969）。研究结果显示贝叶斯方法和限制性最大似然方法在遗传力和育种值估计方面差异小。本研究为大菱鲆的遗传参数估算提供另一种可行方法。

In most fish, reproduction is seasonal or periodic under the suitable conditions. In turbot (Scophthalmus maximus) farms, one of the most economically important marine flatfish species, changes in daylength could cause changes in the spawning time. In this study, to characterize the regulation of reproductive physiology following light signals, three melatonin receptors (Mtnr) investigated in turbot were named smMtnr1, smMtnr2, and smMtnr1c. Distinct expression profiles demonstrated that Mtnr mRNAs were concentrated in the brain (as detected in the hypothalamus (Hy) and mesencephalon (Me)), gonad and eye. The most abundant Mtnr1 and Mtnr2 mRNA expression levels were detected in the central nervous system at the beginning of the breeding season, suggesting that Mtnr1 and Mtnr2 may play vital roles in the regulation of turbot gonadal development. In addition, the melatonin profiles gradually increased and reached to the highest level at the spawning stage, indicating that melatonin is a potent hormone in the regulation of fish oocyte growth and maturation. The results of this study suggested that melatonin is the primary factor that transduces the light signal and regulates the physiological functions of turbot seasonal reproduction. Moreover, the results of this study may establish a foundation for further research seeking to identify fish melatonin receptors involved in the gonadal development and gamete maturation.

The objective of this study was to estimate genetic parameters of body width (BW) to body length (BL) ratio (BW/BL) and of body weight traits (BWT) in turbot, and to elucidate the genetic mechanism of the two traits during ontogeny by dynamic genetic analysis. From 3 to 27 months, BW, BL and BWT of each communally stocked fish were measured every 3 months. The BW/BL ratio was measured at different sampling ages. A two-trait animal model was used for genetic evaluation of traits. The results showed that the heritability values of BW/BL ratio ranged from 0.216 8 to 0.314 8, corresponding to moderate heritability. The BWT heritability values ranged from 0.270 2 to 0.347 9 corresponding to moderate heritability. The heritability of BW/BL ratio was lower than that of BWT, except at 3 months of age. Genetic correlation between BW/BL ratio and BWT decreased throughout the measurement period. Genetic correlations were higher than the phenotypic correlations. The current results for estimating genetic parameters demonstrate that the BW/BL ratio could be used as a phenotypic marker of fast-growing turbot, and the BW/BL ratio and BWT could be improved simultaneously through selective breeding.

遗传参数估计在动物选择育种中占有重要地位。近年来,分子标记被广泛用于遗传评估,提高了评估的准确度。在仅一代系谱信息已知的情况下,为了提高遗传评估的准确度,构建包含39个家系的大菱鲆群体,收集了1890尾100日龄幼鱼的体重数据,借助线性混合模型(Linear Mixed Model),约束极大似然法(REML),分别利用根据亲本12对微卫星标记分型结果推导出的子代加性遗传相关系数(Parental Molecular Relatedness,PMR)和根据三代完整系谱估计的子代加性遗传相关系数(Pedigree Relatedness, PR)估计了子代体重性状的遗传力和育种值,利用交叉验证的方法比较了利用不同加性遗传相关系数预测遗传效应的准确度。结果显示,PMR和PR之间呈高度正相关(0.872),利用PMR和PR估计的遗传力分别为0.52±0.13和0.55±0.22,都属于高等遗传力,并且利用PMR和PR预测遗传效应的能力相同(0.81)。研究结果表明,当仅一代系谱已知时,PMR可以替代PR用于大菱鲆群体遗传参数估计。为了更好的比较PMR与PR,需要扩大微卫星标记数目及家系数目进一步研究。

An introduced turbot population was used to establish families and to estimate genetic parameters of the offspring. However, there is a lack of pedigree information, and common environmental effects can be introduced when each full-sib family is raised in a single tank. Therefore, in the genetic evaluation, SSRs (simple sequence repeats) were used to reconstruct the pedigree and to calculate molecular relatedness between individuals, and the early mixed-family culture model was used to remove the impact of the common environmental effects. After 100 d of early mixed culture, twenty SSRs were used to cluster 20 families and to calculate paired molecular relationships (n=880). Additive genetic matrices were constructed using molecular relatedness (MR) and pedigree reconstruction (PR) and were then applied to the same animal model to estimate genetic parameters. Based on PR, the heritabilities for body weight and body length were 0.214±0.124 and 0.117±0.141, and based on MR they were 0.101±0.031 and 0.102±0.034, respectively. Cross validation showed that the accuracies of the estimated breeding values based on MR (body weight and body length of 0.717±0.045 and 0.629±0.141, respectively) were higher than those of PR (body weight and body length of 0.692±0.052 and 0.615±0.060, respectively). The MR method ensure availability of all genotyped selection candidates, thereby improving the accuracy of the breeding value estimation.

为了开展大菱鲆耐高温选育工作，对其进行耐高温性状及其相关生长性状的遗传评估是非常必要的。以来源于英国、法国、丹麦和挪威4个国家的不同群体构建大菱鲆选育家系，利用F₁的20个和F₂的22个耐高温选育家系进行耐高温实验，统计耐高温评估指标（UTT）和相应的实验鱼体重（每个家系选取40-50尾实验鱼）。基于Gibbs抽样的贝叶斯方法，采用包含母性效应和不包含母性效应的两种动物模型，对大菱鲆耐高温（UTT）和生长性状的遗传力以及这两个性状间的遗传相关和表型相关进行分析。结果表明，基于不包含母性效应的动物模型估计的体重和耐高温性状的遗传力以及这两个性状之间的表型相关和遗传相关分别为0.239±0.141,0.111±0.080,0.075±0.026和-0.019±0.011。基于包含母性效应的动物模型估计的这4个值分别为0.203±0.115,0.055±0.026,0.047±0.034和-0.024±0.028,体重和耐高温性状的母性效应分别为0.050±0.017和0.013±0.004。母性效应对这两个性状的遗传评估有一定的影响。本文的研究结论为制订合理的大菱鲆耐高温育种规划提供了理论依据。

In order to provide pertinent evidence of ion channel with immune response in the fish, whole cell patch-clamp technique was employed for potassium ion channel study in turbot (Scophthalmus maximus). Lymphocytes were isolated by Percoll density gradient centrifugation from peripheral blood samples, and electrophysiological characters of the channel were analyzed. In the recorded cells, activated voltage of the channels was -42.5±3.7 mV and the average peak current was 313.12±28.2 pA. The channel was identified as voltage dependent, the current was outward and it could be inhibited by 10 mmol/dm³ TEA or 5 mmol/dm³ 4-AP, a specific potassium channel inhibitor, identifying the existence of potassium channel in peripheral lymphocytes of the turbot.

蛋白酶体是一个大型的, 负责细胞内蛋白质降解和代谢类的家族. 它与主要组织相容性复合体(MHC)分子结合形成肽聚合物蛋白酶复杂体系从而发挥重要作用. 这份研究报告确定了大菱鲆的蛋白酶体亚基的一个新成员. 该蛋白酶体亚基的全长cdNA序列已经获得, 该cdNA含有一个117 bp的5'非编码区, 825 bp的开放阅读框(ORF)和330 bp的3'非编码区. 3'端非编码区包含在一个典型的多聚腺苷酸化终止密码信号(AATAAA), 之后是一个长24 bp的poly (A)尾巴. 通过密码子分析发现开放阅读框编码274个氨基酸. 序列分析表明, 其主要结构与其他脊椎动物的LMP7序列高度相似. 实验还同时考察了在经受不同病原体感染后, LMP7表达水平和免疫反应之间的关系. 定量RT-PCR表明LMP7在各种组织中的差异表达: 其在脾, 肝, 肌肉和皮肤中, 分别有不同程度的高表达. 在感染牙鲆淋巴囊肿病毒96小时后, LMP7表达在大菱鲆的肝脏、肾脏、脾脏达到最高. 在12 h的鳗弧菌感染过程中, 分别在大菱鲆的肝, 肾, 脾检测到LMP7的高表达. 此外, LMP7的表达在大菱鲆肾细胞(TK)感染鳗弧菌24 h和感染LCdV96h后也明显增加. 这些结果表明, 大菱鲆LMP7蛋白参与大菱鲆的免疫反应, 并可能会起到显着的免疫调节作用.