Coordinated expression and regulation of deiodinases and thyroid hormone receptors during metamorphosis in the Japanese flounder (<Emphasis Type="Italic">Paralichthys olivaceus</Emphasis>)

In vertebrates, thyroid hormone receptors (TRs) and deiodinases are essential for developmental events driven by the thyroid hormones (THs). However, the significance of deiodinases during the metamorphosis of the Japanese flounder (Paralichthys olivaceus) remains unclear. Moreover, regulation and response of the TRs and deiodinases to THs in this fish are poorly understood. Therefore, we detected the expression patterns of THs, deiodinases, and TRs in drug-treated larvae and untreated larvae of P. olivaceus by using enzyme-linked immunosorbent assay and quantitative real-time PCR during P. olivaceus metamorphosis. To further understand the roles of these elements, a rescue assay was performed. Our results show the importance of THs, TRs, and deiodinases in flatfish metamorphosis. Our results also confirm that D1 and D2 activate THs and D3 plays the opposite and complementary role. Moreover, we demonstrated that both TRα and TRβ have important but different roles during P. olivaceus metamorphosis.     

河套地区种植方式与密度对'张杂谷19号'产量的影响

为明确河套地区不同栽培模式对'张杂谷19号'产量的影响,以新抗旱谷子杂交种'张杂谷19号'为试验材料,研究3种种植方式（干旱无膜、干旱覆膜及灌溉无膜）和5种密度（4.5万、9万、13.5万、22.5万、45万株/hm²）对'张杂谷19号'稳产和丰产性的影响。结果表明,正常灌溉条件下,'张杂谷9号'的产量随着种植密度的增加而增加。当密度为45万株/hm²时产量最高,达到8724.36 kg/hm²。而干旱条件下,适宜种植密度可以同样获得较高产量,与正常灌溉条件下最高产量差异不显著。当种植密度为9万~ 45万株/hm²时,产量普遍提高到7700 kg/hm²以上,最高可达8654.33 kg/hm²。河套地区'张杂谷19号'播前灌溉1次足水、地膜覆盖及种植密度9万~45万株/hm²,可以实现水分高效利用和产量达到较高水平。     

Dietary taurine impacts the growth,amino acid profile and resistance against heat stress of tiger puffer (Takifugu rubripes)

A 56‐day feeding trail was conducted to evaluate the effects of taurine (Tau) supplementation on growth performance, amino acid profile and heat stress resistance capacity in juvenile Takifugu rubripes (initial body weight: 32.28 ± 0.20 g). Tiger puffer were distributed into five groups and each received one of the following diets: each diet was supplemented with 0 (T1), 5 (T2), 10 (T3), 20 (T4) or 50 (T5) g Tau/kg, respectively. Growth performances were significantly ameliorated with fed diet T3 (p < .05). The Tau content of muscle increased significantly as dietary Tau increased (p < .05). Compared to the control group, fish fed diets T4 and T5 showed significantly higher concentration of triglyceride and urea, respectively (p < .05), while taurine transporter (TauT) gene and IGF‐1 gene expression increased significantly in fish fed diets T3 and T4, respectively (p < .05). After acute heat stress, HSP70 gene expression levels were significantly greater in the livers and spleens of T. rubripes (p < .05) fed diet supplemented with Tau. Levels of complement C4 were highest in fish fed 10 g/kg Tau (p < .05). These data suggested that dietary supplemented with taurine indicated positive effects on growth performances, amino acid profile and resistance against heat stress for T. rubripes.     

Effect of hydroxyproline supplementation on growth performance,body composition,amino acid profiles,blood‐biochemistry and collagen synthesis of juvenile chu's croaker (Nibea coibor)

Hydroxyproline (Hyp) may play an important role in collagen metabolism, as it is almost exclusively found in collagen. To examine this possibility, a 56‐day feeding trial was conducted to evaluate the effect of graded supplementaries of Hyp (0, 2.5, 5, 7.5, 10 and 12.5 g/kg dry diet weight) on growth performance, feed utilization, biochemical composition and collagen synthesis of chu's croaker, Nibea coibor (13.6 ± 0.28 g). The growth performance and feed utilization were improved with increased levels of dietary Hyp, reaching a maximum at 5 g/kg (diet H2) followed by a slight decrease. Polynomial regression analysis showed that the maximum specific growth rate (SGR) was attained at 7.177 g/kg dietary Hyp. Increasing levels of Hyp did not affect body composition of juvenile Nibea coibor. However, dietary Hyp supplementation significantly affected the levels of Leu, Ile, Met, Lys, Ser, Glu and Pro in muscle and the levels of Met, Lys, Glu, Pro and Gly in swim bladder. The serum calcium (SC) level decreased significantly with increasing levels of dietary Hyp. However, the triglycerides (TG) and total cholesterol (T‐CH) levels in serum and liver were relatively stable. Importantly, the acid‐soluble collagen (ASC) and total collagen (TC) levels in swim bladder increased significantly initially and then decreased after reaching a maximum. Polynomial regression analysis revealed that the maximum TC level in swim bladder was attained at 9.736 g/kg of dietary Hyp. Collectively, these results suggest that the appropriate provision of hydroxyproline is essential for maximal collagen synthesis and growth.     

基于线粒体COI基因的马科鱼类DNA条形码研究

为明确中国马鲅科(Polynemidae)鱼类的分类地位,测定了中国7省10个地点马鲅科鱼类3属5种33条COI基因5′端序列,结合GenBank下载的5属16种41条同源序列,共分析了6属20种马鲅科鱼类DNA条形码。结果显示,20种鱼类种间平均遗传距离为19.6%,是种内平均遗传距离0.9%的22倍;其中14种形成了单系分支,支持其物种有效性。四指马鲅(Eleutheronema tetradactylum)和多鳞四指马鲅(E.rhadinum)种间遗传距离(16.0%)是种内平均遗传距离(1.2%)的13倍,支持将二者作为2个独立物种的分类处理。多鳞四指马鲅种内遗传距离(2.3%)大于2%,形成了2个自展数据支持率为99%的分支,分支间遗传距离(4.8%)是分支内平均遗传距离(0.1%)的48倍,表明在中国沿海分布的多鳞四指马鲅有可能存在2个亚种或隐藏种。黑斑多指马鲅(Polydactylus sextarius)与马达加斯加多指马鲅(P.malagasyensis)外部形态极为相似,种间遗传距离仅为1.0%,且在分子系统树上镶嵌混杂为一支,仅根据分子数据结果,推测二者可能为同一物种;但由于没有可检视的标本,也不能排除GenBank序列种名注释中形态鉴定出错的可能。马伦氏多指马鲅(P.mullani)与七丝指马鲅(Filimanus heptadactylus)也混为1支,分支内遗传距离仅为0.1%;如果不是GenBank序列种名注释出错,则二者应为同一物种。GenBank序列中来源于北部湾的六丝多指马鲅(P.sexfilis),则可能是黑斑多指马鲅的错误鉴定。     

杜马斯燃烧法和凯氏定氮法在土壤全氮检测中的比较研究

选用 6组不同全氮含量的土壤样品(梯度为 0%～0.06%、0.06%～0.1%、0.1%～0.2%、0.2%～0.3%、0.3%～ 0.4%和 0.4%～ 0.5%)和 4份土壤有效态成分分析标准物质为试验材料，分别采用杜马斯燃烧法和凯氏定氮法测定其全氮含量，并对两种方法测定结果的精密度、准确度和相关性及检测成本进行了比较分析。对土壤有效态成分分析标准物质全氮含量的检测，两种方法测定结果都接近于真实值，比较两种方法的相对标准偏差(RSD)和相对误差(RE)值，可确定杜马斯燃烧法精密度更高，且准确度更好；对于含氮量范围为 0%～ 0.06%的样品，两种方法的测定值之比(D/K)为 0.692～ 0.965，杜马斯燃烧法测定结果的变异系数为 0.00%～ 9.96%，测定结果不稳定，两种方法的测定值间存在显著的线性相关，但 R2仅为 0.9049；而含氮量大于 0.06%的样品，两种方法的测定值之比(D/K)为 0.940～ 1.104，变异系数均小于 5%，测定结果间存在显著的线性相关(R2=0.9979)。在检测成本方面，完成相同数量样品检测，杜马斯燃烧法所需时间和人力都约是凯氏定氮法的1/2。因而，杜马斯燃烧法是一种环保、高效的土壤全氮检测方法，对于含氮量范围为 0%～ 0.06%的土壤样品，凯氏定氮法的测定结果更接近于真实值，而对于含氮量大于 0.06%的土壤样品，杜马斯燃烧法更加适用。     

新生仔猪的护理——以上海某规模猪场为例

我国养猪业发展迅速，整体水平在不断提高，但是与养殖业较为发达的国家相比仍有一些差距。以每年每头母猪断奶的仔猪数（PSY）为例，目前国外养猪发达国家PSY普遍已超30头，而我国却仍在25头左右，仍有较大的提升空间。仔猪护理工作在生猪生产过程中尤为重要，一旦护理措施不当就会造成仔猪死亡，从而降低PSY，直接影响到养猪企业的经济效益。规模猪场仔猪死亡的主要原因就是由于仔猪护理不当所引起的，仔猪护理问题一直是养猪业的一个难题。文内以2020年4—5月上海某规模猪场某栋产房新生仔猪（共477头，其中压死8头，瘦弱致死12头，腹泻致死亡的32头）为例，介绍规模猪场的仔猪护理及注意事项，以期为仔猪护理工作提供借鉴。     

Soil organic and inorganic carbon sequestration by consecutive biochar application: Results from a decade field experiment

Biochar addition can expand soil organic carbon (SOC) stock and has potential ability in mitigating climate change. Also, some incubation experiments have shown that biochar can increase soil inorganic carbon (SIC) contents. However, there is no direct evidence for this from the field experiment. In order to make up the sparseness of available data resulting from the long‐term effect of biochar amendment on soil carbon fractions, here we detected the contents and stocks of the bulk SIC and SOC fractions based on a 10‐year field experiment of consecutive biochar application in Shandong Province, China. There are three biochar treatments as no‐biochar (control), and biochar application at 4.5 Mg ha^?1 year^?1 (B4.5) and 9.0 Mg ha^?1 year^?1 (B9.0), respectively. The results showed that biochar application significantly enhanced SIC content (3.2%–24.3%), >53 μm particulate organic carbon content (POC, 38.2%–166.2%) and total soil organic carbon content (15.8%–82.2%), compared with the no‐biochar control. However, <53 μm silt–clay‐associated organic carbon (SCOC) content was significantly decreased (14%–27%) under the B9.0 treatment. Our study provides the direct field evidence that SIC contributed to carbon sequestration after the biochar application, and indicates that the applied biochar was allocated mainly in POC fraction. Further, the decreased SCOC and increased microbial biomass carbon contents observed in field suggest that the biochar application might exert a positive priming effect on native soil organic carbon.