鳊鱼和宽鳍鱲幼鱼流速选择与运动能量代谢特征的关联

为考察喜好激流环境的宽鳍鱲(Zacco platypus)和喜好缓流环境的鳊鱼(Parabramis pekinensis)的最适游泳速度和流速选择的关联以及运动能量代谢特征对流速选择的影响,在(25±0.5)℃条件下将实验鱼(n=13×2)单尾分别置于梯度流速选择仪(设定流速范围为18.6—102.7 cm/s,等距离划分为5个流速区域)中获取视频资料,采用Ethovision XT19软件分析视频资料并计算两种实验鱼在5个流速区域的平均停留时间百分比(P_t)和平均出入频率百分比(Pf);另外,使用游泳代谢仪测定两种实验鱼的临界游泳速度(U_(crit))和不同游泳速度下的运动耗氧率(M_(O2)),并计算出不同速度下单位位移耗能(COT)、最适游泳速度(U_(opt))、静止耗氧率(RMR)和净单位位移耗能(COTnet)。结果显示:鳊鱼的U_(crit)和RMR均显著小于宽鳍鱲(P0.05),但二者的最大耗氧率(MMR)无显著差异;随游泳速度的增加,两种实验鱼的M_(O2)均显著上升,尽管在较低游泳速度下,鳊鱼的M_(O2)和COT均小于宽鳍鱲,但在高游泳速度下则相反;两种实验鱼的U_(opt)分别为(6.20±1.29)体长(BL)/s和(11.56±1.57)BL/s,鳊鱼显著小于宽鳍鱲;两种实验鱼的COTnet随着游泳速度增加差异逐渐增大,鳊鱼显著高于宽鳍鱲(P0.05);两种实验鱼在最低流速区域(18.6—23.8 cm/s)的P_t和Pf显著大于其他速度区域(P0.05),由此可见两种实验鱼的偏好游泳速度(U_(perf))等于或小于(18.6—23.8 cm/s),然而鳊鱼在最低速度区域P_t和Pf均显著大于且在较高速度区域的P_t和Pf则均显著小于宽鳍鱲(P0.05)。结果表明:有别于过往研究的是两种实验鱼的U_(perf)均与U_(opt)偏离;在激流环境中生存的宽鳍鱲更加偏好较高的水流速度,生境水流对实验鱼的水流速度选择特征存在显著影响,这种影响的主要能量学机制与鱼类的运动能量效率有关。     

杉楠混交与人工杉木林自养机制的恢复

自养机制的形成是人工林可持续经营的目标之一。本研究通过混交模拟杉木人工林不同恢复阶段林分,观察比较发现从退化的杉木林阶段到地带性树种比例较低的混交林、地带性树种比例较高的混交林和地带性树种纯林阶段凋落量、Ｎ、Ｐ、Ｋ、Ｃａ和Ｍｇ５种元素的归还量逐渐增加,特别是５种养分元素的循环速率也不断增大,其中Ｎ、Ｍｇ的循环速率由杉木纯林的０．１左右增大到火力楠纯林的０．５以上,与此同时林分土壤有机质含量和养分含     

杉木连栽土壤对其幼树生长的影响

在会同林区采用３种不同连栽杉木次数的土壤,进行杉木幼树盆栽试验．结果表明,杉木连栽不利其幼树生长．连裁使幼树高生长下降３７—４０％,基径下降１９—２８％,冠幅下降２１—２９％,总生物量减少４５—５０％．杉木连栽还造成土壤养分递减,即腐殖质减少７—２８％,速效养分下降２３—２８％,土壤微生物数量和活性也大大降低．因此,杉木纯林连栽经营方式应尽快改变．     

Near Neutral pH Redox Flow Battery with Low Permeability and Long‐Lifetime Phosphonated Viologen Active Species

A highly stable phosphonate‐functionalized viologen is introduced as the redox‐active material in a negative potential electrolyte for aqueous redox flow batteries (ARFBs) operating at nearly neutral pH. The solubility is 1.23 m and the reduction potential is the lowest of any substituted viologen utilized in a flow battery, reaching ?0.462 V versus SHE at pH = 9. The negative charges in both the oxidized and the reduced states of 1,1′‐bis(3‐phosphonopropyl)‐[4,4′‐bipyridine]‐1,1′‐diium dibromide ( BPP?Vi ) effect low permeability in cation exchange membranes and suppress a bimolecular mechanism of viologen decomposition. A flow battery pairing BPP?Vi with a ferrocyanide‐based positive potential electrolyte across an inexpensive, non‐fluorinated cation exchange membrane at pH = 9 exhibits an open‐circuit voltage of 0.9 V and a capacity fade rate of 0.016% per day or 0.00069% per cycle. Overcharging leads to viologen decomposition, causing irreversible capacity fade. This work introduces extremely stable, extremely low‐permeating and low reduction potential redox active materials into near neutral ARFBs.     

Ceramide Production Mediates Aldosterone-Induced Human Umbilical Vein Endothelial Cell (HUVEC) Damages

Here, we studied the underlying mechanism of aldosterone (Aldo)-induced vascular endothelial cell damages by focusing on ceramide. We confirmed that Aldo (at nmol/L) inhibited human umbilical vein endothelial cells (HUVEC) survival, and induced considerable cell apoptosis. We propose that ceramide (mainly C18) production might be responsible for Aldo-mediated damages in HUVECs. Sphingosine-1-phosphate (S1P), an anti-ceramide lipid, attenuated Aldo-induced ceramide production and following HUVEC damages. On the other hand, the glucosylceramide synthase (GCS) inhibitor PDMP or the ceramide (C6) potentiated Aldo-induced HUVEC apoptosis. Eplerenone, a mineralocorticoid receptor (MR) antagonist, almost completely blocked Aldo-induced C18 ceramide production and HUVEC damages. Molecularly, ceramide synthase 1 (CerS-1) is required for C18 ceramide production by Aldo. Knockdown of CerS-1 by targeted-shRNA inhibited Aldo-induced C18 ceramide production, and protected HUVECs from Aldo. Reversely, CerS-1 overexpression facilitated Aldo-induced C18 ceramide production, and potentiated HUVEC damages. Together, these results suggest that C18 ceramide production mediates Aldo-mediated HUVEC damages. MR and CerS-1 could be the two signaling molecule regulating C18 ceramide production by Aldo.     

饥饿对中华倒刺鲃幼鱼代谢、个性和集群的影响

在自然界中,环境变化、季节更替和人为因素造成食物资源时空分布的不均一性,导致鱼类经常面临食物资源短缺的环境胁迫,对其能量代谢和行为造成一定影响。为考察食物资源短缺下暖水性鲤科鱼类能量代谢、个性与集群行为的应对策略及其可能的内在关联,选取中华倒刺鲃(Spinibarbus sinensis)幼鱼为实验对象,分别测定饥饿组(2周)和对照组(维持日粮)在处理前后实验鱼的标准代谢率(Standard metabolic rate,SMR)、个性行为(勇敢性、探索性和活跃性)以及实验处理后的集群行为(凝聚力和协调性)。研究发现:(1)饥饿组和对照组实验过程中实验鱼SMR均显著下降,但仅饥饿组实验鱼SMR具有重复性;(2)饥饿导致中华倒刺鲃幼鱼勇敢性、探索性、活跃性均显著增加;(3)饥饿导致群体成员间距离缩短,游泳速度及其同步性上升。研究表明:饥饿后的中华倒刺鲃不仅适应性降低SMR以减少能量消耗,而且呈现出更高的勇敢性、探索性和活跃性以利于获取食物资源;饥饿迫使中华倒刺鲃群体提高凝聚力和协调性,可能有助于提高群体的生存能力。     

Plant regeneration of Chorispora bungeana via somatic embryogenesis

Summary A method was developed for in vitro regeneration of plants via somatic embryogenesis in Chorispora bungeana, an alpine plant with freeze-tolerance, using cell suspensions initiated from leaf-derived callus. Primary calli were induced from leaves of C. bungeana grown on Murashige and Skoog (MS) media supplemented with 4.0 mg l⁻¹ gibberellic acid (GA₃), 0.2 mgl⁻¹ α-naphthaleneacetic acid (NAA) and 0.2 mgl⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D). Suspension culture was initiated by incubating the callus particulates in liquid MS medium supplemented with 1.0 mgl⁻¹ kinetin (KT) and 0.2 mgl⁻¹ NAA. Individual early cotyledonary-stage somatic embryos isolated from cell suspension developed into whole plants on medium containing high levels of sucrose (60 and 90 gl⁻¹), whereas lower sucrose concentrations (0 and 30 gl⁻¹) were inhibitory to main root development. On the MS medium with 90 gl⁻¹ sucrose, one regenerated plant exhibited hetero-morphologic leaves, while other plants grown on different media showed a transformation from stem to root.     

长江江豚重要栖息地清节洲水域鱼类群落结构

长江清节洲水域是长江江豚的重要栖息地之一,为了解该水域鱼类群落结构特征,于2017年4月、7月、10月和2018年2月对该水域鱼类群落进行了季节性调查。调查共采集鱼类38种,隶属于5目8科29属,其中鲤科鱼类占优势,占总种类数的68.4%。相对重要性指数结果显示鱼类群落优势种为贝氏?（Hemiculter bleekeri）、似鳊（Pseudobrama simony）、银鲴（Xenocypris argentea）和刀鲚（Coilia nasus）。按生活习性划分,定居性鱼类占绝对优势,占总种数的78.9%;在空间上,中上、中下和底层鱼类分布较为均衡,占总种数的比例依次为36.8%,28.9%和34.2%;从食性上划分,杂食性和肉食性鱼类较多,分别占总种数的44.7%和39.5%。Shannon-Weiner指数、Simpson指数、Margalef指数和Pielou均匀度指数依次分别为0.820~1.711,0.601~0.981,1.640~3.423和0.249~0.592。单因素方差分析表明,除春夏季与秋冬季的Margalef指数存在显著性差异（P<0.05）,各指数在时间和空间均无显著性差异（P>0.05）。与历史资料相比,该区域鱼类群落呈现物种多样性降低和群落结构小型化的趋势。因此,建议加强该水域鱼类资源的监测和保护,以维护长江生态系统的稳定与江豚栖息地的适合度。     

不同树种混交林及其纯林对土壤理化性质影响的研究

对针阔混交林土壤理化性质的研究表明,针阔混交林比针叶树纯林对土壤的改良作用要好,它使土壤总孔隙度增加２—１９％,水分含量增加６—３１％,枯枝落叶年凋落量增加２—２００％;土壤养分含量全Ｎ、ＮＨ４－Ｎ、代换性Ｃａ、代换性Ｍｇ和腐殖质含量分别增加４５—７５％、３３—８２％、５５—８５％、４４—８４％和３７—４６％．