三疣梭子蟹14-3-3基因的克隆及其在低盐和病原胁迫后的表达分析

本研究利用cDNA末端快速扩增技术(RACE)克隆了三疣梭子蟹(Portunus trituberculatus)14-3-3基因(Pt14-3-3)。Pt14-3-3基因cDNA序列全长为2510 bp,包含开放阅读框741 bp,编码由247个氨基酸组成的蛋白,分子量为27.98 kDa。序列比对结果显示,Pt14-3-3基因与中华绒螯蟹14-3-3基因同源性最高(100%)。系统进化树分析表明,Pt14-3-3氨基酸序列与中华绒螯蟹(Eriocheir sinensis)紧密聚为一支。组织表达分析显示,Pt14-3-3基因在肝胰腺、肌肉、鳃、心脏、眼柄、血淋巴中均有表达,其中,在肝胰腺中的表达量最高。低盐胁迫后,Pt14-3-3基因在鳃和肝胰腺中的表达量分别于48 h和12 h显著上调并达到最大值,分别为对照组的1.34倍(P<0.05)和7.54倍(P<0.05)。人工感染副溶血弧菌(Vibrio parahaemolyticus)和白斑综合征病毒(WSSV)后,Pt14-3-3基因在肝胰腺和血细胞中整体均呈显著上调表达,最高上调17.52倍(P<0.05)。本研究结果表明,Pt14-3-3基因可能在三疣梭子蟹低盐适应和免疫反应中发挥重要作用。     

蛋鸭坦布苏病毒与金黄色葡萄球菌混合感染的诊治

山东省某养鸭场蛋鸭发病,通过临床诊断及实验室检测最终确诊为坦布苏病毒与金黄色葡萄球菌混合感染。通过对感染鸭群进行对症治疗和抗生素治疗,控制住了病情,减少了经济损失。     

不同土地利用类型氨挥发氮同位素自然丰度特征

为了探讨不同土地利用类型下氨（NH3）挥发氮同位素自然丰度特征,采集3种土地利用类型（果园、菜地和林地）土壤,在可控条件下采用海绵吸收法开展了为期15d的室内培养试验,测定了不同土地利用类型下土壤NH3挥发全过程δ15N值及其变化规律。培养期间,3种土地利用类型下的土壤NH+4-N浓度均呈现先上升后下降的趋势;果园和菜...     

Shape transition of germanium nanocrystals on a silicon (001) surface from pyramids to domes

Chemical vapor deposition of germanium onto the silicon (001) surface at atmospheric pressure and 600 degrees Celsius has previously been shown to produce distinct families of smaller (up to 6 nanometers high) and larger (all approximately 15 nanometers high) nanocrystals. Under ultrahigh-vacuum conditions, physical vapor deposition at approximately the same substrate temperature and growth rate produced a similar bimodal size distribution. In situ scanning tunneling microscopy revealed that the smaller square-based pyramids transform abruptly during growth to significantly larger multifaceted domes, and that few structures with intermediate size and shape remain. Both nanocrystal shapes have size-dependent energy minima that result from the interplay between strain relaxation at the facets and stress concentration at the edges. A thermodynamic model similar to a phase transition accounts for this abrupt morphology change.     

抗H5亚型禽流感病毒血凝素蛋白特异性单克隆抗体的研制及鉴定

以抗H5亚型禽流感病毒（AIV）JSD株鸡胚尿囊液免疫8周龄BALB/c小鼠,第4次免疫后取其脾淋巴细胞与SP2/0-Ag-14骨髓瘤细胞融合,用血凝抑制试验（HI）对杂交瘤进行筛选,经3次亚克隆后,共获得4株针对血凝素（HA）蛋白的特异性单克隆抗体,分别命名为：2D2、2C8、3D3和3D11。该4株单抗的小鼠腹水的HI效价在2^13～2^15,ELISA效价为1.2×10^5～5.1×10^5。亚类鉴定结果表明,2D2和3D11属于IgG1,2C8属于IgG3,3D3属于IgG2a亚类;特异性试验结果表明,上述4株单抗仅与H5 AIV毒株发生特异性反应,而不与其他亚型AIV以及NDV、IBV和EDSV-76等病毒反应;鸡胚中和试验结果显示,4株单抗均具有较好的中和活性。本研究成功获得4株针对H5 AIVHA蛋白的特异性单抗,为临床H5 AIV的血清学监测及鉴定提供了必需的试剂。     

几种不同类型土壤有机碳库容大小及周转研究

通过土壤样品的室内培养,运用三库一级动力学理论,分析了沼泽土、草甸土、普通黄棕壤和棕色石灰土4种土壤有机碳库容大小、各碳库平均周转时间及分解动态。结果表明,4种土壤剖面表层和中层有机碳含量分别为8.48~24.53 g/kg,4.02~16.77 g/kg;活性碳占总有机碳含量的0.99%~5.01%,1.31%~1.91%,平均周转时间分别为8.8~14.3 d,10.4~16.5 d;缓效性碳占总有机碳含量的15.88%~59.04%,20.43%~48.36%,平均周转时间分别为1.3~29.1 a,3.6~21.3 a;惰性碳占总有机碳含量的39.97%~79.11%,50.31%~77.66%。不同类型土壤三库有机碳含量均是上层明显大于中层,培养3个月,表层和中层土壤有机碳累计分解量分别达到了165.99~2 429.57 mg/kg,108.04~743.02 mg/kg,4种土壤有机碳分解速率大小顺序:沼泽土>草甸土>棕色石灰土>普通黄棕壤,与活性碳的百分比含量成正相关关系。对培养期间土壤有机碳累计释放量进行拟合,发现三次方程(Y=b0 b1x b2x2 b3x3)能很好地描述其变化趋势,相关性均达到极显著水平(P<0.01)。     

Denitrification characteristics of pond sediments in a Chinese agricultural watershed

Ponds are widely distributed in rice-based agricultural watersheds, particularly in southern China, and may play an important role in nitrate (     ) removal. However, the denitrification rate of pond sediment, measured using the acetylene (C₂H₂) inhibition technique, indicated that the amount of nitrogen removed by denitrification accounted for <1% of the total nitrogen applied. The present study was undertaken to determine the effects of sediment depth and temperature on denitrification of pond sediment using the C₂H₂ inhibition technique. The highest denitrification potential was found in the upper 5 cm of sediment, but this only accounted for approximately 34% of the total denitrification of the upper 0–30 cm of sediment, suggesting that sediment denitrification potential would be underestimated if only the upper 5 cm of sediment was measured. The denitrification potential was low and showed a weak response over a temperature range of 6–18°C, whereas denitrification increased significantly from 18 to 30°C, indicating that denitrification may play an important role in the removal of     in warm seasons. A comparison of the     disappearance and C₂H₂ inhibition methods showed that they were significantly ( P  < 0.01) and positively correlated. However, the C₂H₂ inhibition method gave only approximately 25% of the values determined by the     disappearance method.     

白马鸡人工驯养初步研究

通过人工饲养的方式探索出白马鸡驯养的经验,即:在野生白马鸡适宜生境下建立饲养场,从育雏阶段开始进行人工投食饲养和本地土鸡带领相结合的驯养方式。目前已经完成从子一代到子二代的完整驯养、饲养流程,取得了云南省林业厅的驯养繁殖许可证。对育雏、亚成体、成体阶段的喂食量、存活情况等作了分析,认为接近原始生境的环境及本地带雏母鸡是成功的重要条件。     

中国和日本农业活动对流域氮素收支的影响

To analyze the effect of agricultural activity on nitrogen(N) budget at the watershed scale,a comparative study was conducted at two Japanese watersheds,the Shibetsu River watershed(SRW) and Upper-Naka River watershed(UNRW),and one Chinese watershed,the Jurong Reservoir watershed(JRW).The total area and the proportion of agricultural area(in parentheses) of the watersheds were 685(51%),1 299(21%),and 46 km 2(55%) for SRW,UNRW,and JRW,respectively.The main agricultural land use in SRW was forage grassland,while paddy fields occupied the highest proportion of cropland in UNRW(11% of total area) and JRW(31% of total area).The farmland surplus N was 61,48,and 205 kg N ha 1 year 1 for SRW,UNRW,and JRW,respectively.The total input and output for the whole watershed were 89 and 76,83 and 61,and 353 and 176 kg N ha 1 year 1 for SRW,UNRW,and JRW,respectively.The proportion of discharged N to net anthropogenic N input was 31%,37%,and 1.7% for SRW,UNRW,and JRW,respectively.The two watersheds in Japan showed similar proportions of discharged N to those of previous reports,while the watershed in China(JRW) showed a totally different characteristic compared to previous studies.The high N input in JRW did not increase the amount of discharged N at the outlet of the watershed due to high proportions of paddy fields and water bodies,which was an underestimated N sink at the landscape scale.     

中国粮食生产的温室气体减排策略以及碳中和实现路径

作为世界上最大的农业生产国和温室气体排放国,我国承诺力争到2030年前实现碳达峰,2060年前实现碳中和。国家“双碳”目标给农业生产带来很大的减排挑战,因为农业源温室气体排放约占我国碳排放总量的14%。粮食生产是农业源非CO₂温室气体的主要排放源,归因于过量灌溉和施肥引起的稻田甲烷(CH₄)和土壤氧化亚氮(N₂O)排放。在碳达峰后,粮食生产温室气体的排放占比和减排重要性将越来越大。我国粮食生产究竟能否实现碳中和,以及如何实现碳中和仍不明确。本文综述了我国粮食生产碳排放的源汇效应和时空特征,总结了稻田CH₄和土壤N₂O减排以及农田土壤固碳的有效措施,解析了固碳减排之间的“此消彼长”效应和应对策略,明确了粮食生产实现碳中和的潜在路径,并对未来固碳减排的研究方向进行了展望。