Does sand content in spawning substrate result in early larval emergence? Evidence from a lithophilic cyprinid fish

The spawning success of lithophilic salmonids is strongly influenced by the fine sediment content (“fines”) of spawning substrates, yet knowledge on the impacts of fines on the spawning of non‐salmonid lithophiles remains limited, despite their ecological and socio‐economic importance in European rivers. Consequently, the aim here was to use an ex‐situ experiment to investigate the impact of sand content on egg survival and timing of larval emergence of the surface‐spawning cyprinid European barbel Barbus barbus. Thirty incubator boxes within a recirculating system were filled with one of five experimental sediment mixtures (0%–40% sand by mass) that each contained 300 fertilised eggs at a depth of 50 mm. Emerged, free‐swimming larvae were captured and counted daily to assess grain‐size effects on larval survival and emergence. Specifically, total proportion of emerged larvae, cumulative daily proportion of emerged larvae and time required to reach 50% emergence were measured during the study. Whilst the proportion of sand in the sediments did not have a significant impact on egg‐to‐emergence survival (mean survival per treatment 75%–79%), it significantly affected the timing of larval emergence to the water column; early emergence was detected in treatments with elevated sand content (on average, 50% emergence after 12–13 days versus 19 days in the control). Similar to findings from salmonid studies, these results suggest high sand content in spawning gravels can influence timing of larval emergence and potentially cyprinid lithophilic fish survival.     

Reduction in cadmium accumulation in japonica rice grains by CRISPR/Cas9-mediated editing of OsNRAMP5

Cadmium (Cd) intake is harmful to human health and Cd contamination in rice grains represents a severe threat to those consuming rice as a staple food. Knockout of Cd transporters is a promising strategy to reduce Cd accumulation in rice grains. OsNRAMP5 is the major transporter for Cd and manganese (Mn) uptake in rice. Nevertheless, it is uncertain whether knockout of OsNRAMP5 is applicable to produce low Cd rice without affecting plant growth and grain yield. In this study, we adopted CRISPR/Cas9-based gene editing technology to knock out OsNRAMP5 in two japonica varieties. We generated three independent transgene-free osnramp5 mutants and investigated the effect of osnramp5 mutations on Cd accumulation and plant growth. Hydroponic experiments showed that plant growth and chlorophyll content were significantly reduced in osnramp5 mutants at low Mn conditions, and this defective growth in the mutants could be fully rescued by supply of high levels of Mn. Cd and Mn accumulation in both roots and shoots was markedly reduced in the mutants compared to that in wild-type plants. In paddy field experiments, although Cd in flag leaves and grains was greatly reduced in osnramp5 mutants, some agronomic traits including plant height, seed setting rate, and grain number per panicle were affected in the mutants, which ultimately caused a mild reduction in grain yield. The reduced plant growth in the mutants can be attributed to a marked decrease in Mn accumulation. Our results reveal that the manipulation of OsNRAMP5 should be treated with caution: When assessing the applicability of osnramp5 mutants, soil pH and soil water content in paddy fields need to be taken into consideration, since they might affect the levels of available Mn in the soil and consequently determine the effect of the mutation on grain yield.     

微波辐射法竹浆纤维素的中性TEMPO氧化及表征

采用微波辐射法和中性2,2,6,6-四甲基哌啶-1-氧化物(TEMPO)自由基氧化工艺来预处理竹浆纤维素,之后用超声波机械处理制备微纤化纤维素。实验结果表明,在60℃下,TEMPO用量为0.15 mmol/g(以绝干浆计,下同),Na Cl O2用量为10 mmol/g,Na Cl O用量为1 mmol/g,微波氧化2 h,其羧基含量最高到达0.729 mmol/g,氧化效果最佳,超声波处理后微纤化纤维素得率高达85.7%。FT-IR分析表明纤维素氧化后引入羧基官能团;XRD结果揭示纤维素氧化反应只发生在纤维素的无定型区或结晶区表面;纤维素氧化前后的聚合度(Dp)结果表明相对于碱性氧化,微波辐射和中性TEMPO氧化对纤维的降解程度低,从而有效地保持了纤维素原本的长度。     

云南传统水稻品种W axy基因多样性形成和维持机制初探

本研究针对W axy基因第四外显子和第五外显子的3个功能位点开发了新的AS-PCR标记，完善了W axy基因的分子标记体系，为更精确的鉴定和筛选目标W axy等位基因提供了工具。直链淀粉含量测定和AS-PCR分析结果显示，云南传统水稻品种具有极为丰富的W axy基因多样性和直链淀粉含量变异，308个传统品种中共检测到65种不同的W axy单倍型，直链淀粉含量变幅为0~48%。In1、E6、E10和E4op/hp这4个位点的碱基频率在四大稻区间存在显著差异，E2位点和In1位点的碱基频率在不同民族间存在显著差异，表明不同稻作区、不同民族对水稻直链淀粉含量和W axy基因有着多样化的选择。同时民族混居地区E2和In1位点的碱基频率不同于其相应的民族独居地区，说明不同民族混居也会产生对W axy基因不同的选择并增加W axy基因的多样性。多样化的选择和民族混居是云南传统水稻品种W axy基因多样性形成和维持的重要机制。在云南四大稻作区中，南部边缘水陆稻区的W axy单倍型最为丰富，共检测到50种单倍型，占总数的77%，这一区域应被设为云南传统稻种资源的保护优先区和核心区。     

Physicochemical characterization and in-vitro digestibility of extruded rice noodles with different amylose contents based on rheological approaches

The physicochemical properties and in-vitro digestibility of extruded rice noodles with different amylose contents were characterized from a rheological point of view. Thermo-mechanical measurements showed that the rice flour with higher amylose contents exhibited greater stability to dual-mixing and higher degrees of starch gelatinization and retrogradation. In addition, greater elastic properties were clearly observed in the high amylose rice samples. The use of high amylose rice flour produced noodles with a harder texture, consequently contributing to reduced cooking loss. Furthermore, the rheological changes of extruded rice noodles were monitored in real time during the in-vitro starch digestion. The rice noodle digesta with higher amylose contents exhibited greater viscosities throughout the simulated oral-gastric-intestinal digestion steps. The flow behaviors of the rice noodle digesta consisted of the Power-law region and infinite shear plateau that were satisfactorily characterized by the Sisko model (R² > 0.99).     

密集烤房不同循环风机烘烤烟叶的色素降解及感官质量

采用三速和单速循环风机,研究密集烤房不同循环风机对烤烟色素及感官质量的影响.结果表明:采用三速循环风机烤后烟叶的叶绿素a、叶绿素b含量分别为5.10、167.74 μg/g,分别为单速循环风机的72.11％和93.30％;叶黄素、β-胡萝卜素、类胡萝卜素含量分别为0.84、155.56、156.40 μg/g,分别为单...     

Effects of cerium on the antioxidant defence system in the petals and the contents of pigments in the calyces of Rosa chinensis Jacq. cut flower

To study the role of cerium (Ce) in regulating the vase life of Rosa chinensis Jacq. cut flowers, the effects of cerium nitrate (Ce(NO₃)₃) on the activities of antioxidant enzymes, the contents of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in the petals, and the contents of chlorophyll a, chlorophyll b and carotenoids in the calyces were investigated. The results showed that Ce(NO₃)₃ evidently enhanced the activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione S-transferase (GST) and glutathione peroxidase (GPX), and evidently decreased the contents of MDA and H₂O₂ in the petals, compared with the control. Moreover, Ce(NO₃)₃ evidently increased the contents of chlorophyll a, chlorophyll b and carotenoids in the calyces. The results also showed that Ce(NO₃)₃ evidently increased the numbers of open flowers and decreased the numbers of wilted flowers. Our results suggest that Ce(NO₃)₃ extended the vase life of R. chinensis Jacq. cut flower by improving the antioxidant defence system in the petals and the contents of pigments in the calyces.     

积雪特性参数分析及雪深模型建立

通过2015~2016年冬季积雪观测试验,测量自然条件下雪深、雪层温度、雪层密度、雪层液态含水率等积雪特性参数,分析积雪特性参数影响因子和发育变化规律,构建径向基神经网络雪深模型。结果表明,空气、地表温度及水汽压是影响雪参数发育三大主要气象因子。在时长为124 d覆雪期中,雪深最大平均融雪速率达3.20 mm·d-1,出现在融雪后期。雪层密度随雪深增加波浪式上升,其中稳定期全层密度0.1~0.4 g·cm-3;雪层液态含水率0.5%~3.5%,分层液态含水率中层较大,积雪表层和底部波动较小;全层积雪孔隙率平均值为72.3%,积底层孔隙率廓线下降最快,极差最大。经两次优化后,雪深模型最大绝对误差为0.614 1 cm,最大相对误差为5.85%,模拟精度控制在6 mm以内。     

桃PpSnRK1α在番茄中过表达对营养胁迫下植株生长的影响

以番茄(Solanum lycopericum)超表达桃SnRK1(蔗糖非发酵蛋白激酶–1)基因PpSnRK1α的株系及野生型为试材,研究在养分供应不足时SnRK1对植株生长的影响。结果表明,低营养条件下,转基因番茄叶片和根系中的Sn RK1酶活性比野生型高41.55%和39.46%;功能叶片的净光合速率平均比野生型高18.98%;低营养胁迫12 d的叶片SOD、POD、CAT活性比野生型高35.56%、28.85%和14.90%;根系活力比野生型高26.39%;茎和叶中氮磷含量显著高于野生型,钾含量两者差别不大,在根系中氮磷含量差别不大,而钾含量显著高于野生型,且氮素向地上部茎和叶中的分配比率增加。上述结果说明,在营养缺乏条件下,超表达PpSnRK1α可以提高番茄功能叶净光合速率,促进植株对氮素的吸收利用,从而延缓叶片衰老。     

农业技术经济学实验教学探索

研究了开展农业技术经济学实验教学的必要性,根据课程内容,确定了动态经济效果评价等实验项目,选择Excel、SPSS、Eviews、LINDO、DEAP软件作为实验教学软件,并分析了实验实施的各个环节。