2006年夏季南黄海浮游植物叶绿素a分布特征及其环境调控机制

根据2006年夏季南黄海生态调查资料,分析了浮游植物现存量(叶绿素a)的空间分布特征及其主要环境调控机制.结果表明:南黄海浮游植物叶绿素a浓度范围为0.07～12.17 mg/m3,平均值为1.42 mg/m3;浮游植物叶绿素a平面分布呈近岸混合区高于外海层化区的特征,总体上随水体盐度和营养盐梯度的变化而变化,其中浅海陆架锋区对浮游植物有明显的聚集作用,垂直结构中层化区叶绿素次表层最大值现象明显,且最大值的深度和量值具有明显的区域差异;叶绿素a浓度与主要环境因子的相关性分析表明,在较大空间尺度上营养盐是浮游植物的主要调控因子,温度、光照和浮游动物摄食等也在一定空间和程度上对浮游植物的生长产生影响.     

北部湾北部海域夏季微型浮游动物对浮游植物的摄食压力

2011年8月份于北部湾北部海域5个观测站位获得的分层水样,分析了表层叶绿素a含量和表层微型浮游动物丰度以及类群组成;同时于现场采用稀释培养法研究了该海域浮游植物生长率(μ)和微型浮游动物的摄食率(g)。分析和测定结果表明:调查海区的微型浮游动物丰度400—1167个/L,类群组成以无壳纤毛虫为主;浮游植物的生长率为-1.50—1.13 d-1,微型浮游动物摄食率为0.33—1.08 d-1;推算微型浮游动物对浮游植物现存量以及初级生产力的摄食压力分别为28.1%—66.0%和-7.4%—438.4%。相对于中国其他海区,8月份北部湾北部海域微型浮游动物摄食速率处于中等水平。调查期间,广西沿海高生产力海区,浮游植物生长率大于微型浮游动物动物的摄食率,浮游植物生物量处于积累期;涠洲岛以南海域,浮游植物生产力较低,微型浮游动物摄食作用是控制浮游植物生长的重要因素。     

南海北部浮游植物生长对营养盐的响应

2004年夏季作者在南海北部海域研究了浮游植物生长的营养动力学,结合物理-化学过程对浮游植物生物量分布的影响与机制进行了研究,阐明了水平对流和中尺度涡对营养盐分布的影响及浮游植物生长和现存生物量对其的响应。受西南季风和东向沿岸流作用所形成的Ekman输送的影响,南海北部海岸带表层海水作离岸运动,使深层富含营养盐的冷水爬坡涌升到表层来补充,激发浮游植物生物量迅速增长。海区反气旋涡使海水辐聚下沉,造成水体具高温、低盐、高溶解氧浓度、低营养盐浓度和低浮游植物生物量。同时通过现场营养盐加富试验,发现该海域营养盐是浮游植物生长的主要限制因子,而且是多种营养元素共同限制了浮游植物的生长,添加单一的营养盐并不能促进浮游植物的生长。在生物量出现增长的试验组中,营养盐添加不仅促使浮游植物生物量的增长,而且也改变了浮游植物的粒级结构和群落结构。例如,在站S1008,培养前叶绿素a浓度为0.28 mg.m-3,加富培养60 h后浮游植物生物量在NP和NPSi的试验组中有显著的增加,叶绿素a浓度分别达1.07 mg.m-3和1.19 mg.m-3;培养前粒度分级叶绿素a主要以Pico级份占优势,而加富试验结束后,在NP和NPSi的试验组以Nano级份占优势,其它试验组仍以Pico级份占优势;同时,在培养后生物量出现增长的试验组,浮游植物群落的优势类群从甲藻向硅藻演替。     

中华哲水蚤(Calanus sinicus)对浮游植物和微型浮游动物的摄食速率估算

2005年4月27日至5月30日在东海有害藻华高发区的6个典型站位采样,结合稀释法实验和Frost的直接计量法研究了中型浮游动物对浮游植物和微型浮游动物群落的现场摄食速率,并对中华哲水蚤(Calanus sinicus)的食物组成、中型浮游动物和微型浮游动物对浮游植物群落的摄食压力进行了估算。研究结果表明春季调查区:中华哲水蚤对浮游植物的物种比摄食率介于0.01~8.43d-1,平均值为(2.72±2.14)d-1。中华哲水蚤对浮游植物的物种摄食速率介于0.05~838.23cells ind.-1d-1,平均值为(52.72±154.21)cells ind.-1d-1,对几种有害藻华原因生物的摄食速率较高。中华哲水蚤对浮游植物物种摄食速率具有食物密度依赖性,在低浮游植物丰度下,其摄食速率会随着浮游植物丰度的增加而增加,达到一定阈值后随着浮游植物丰度增加而逐渐降低。中型浮游动物群落对浮游植物群落碳摄食速率介于0.53~4.97ngC L-1d-1,平均值为(2.16±1.63)ngC L-1d-1。微型浮游动物对浮游植物群落物种平均碳摄食速率介于0.04~13.20ngC ind.-1d-1,平均值为(2.91±5.22)ngCind.-1d-1。微型浮游动物群落对浮游植物群落碳摄食速率介于61.07~8632.85ngC L-1d-1,平均值为(2801.01±4198.46)ngC L-1d-1。分析比较中型浮游动物和微型浮游动物对浮游植物现存量摄食压力表明,海区中微型浮游动物的摄食压力要远高于中型浮游动物,介于95.59%~99.98%,平均值为97.88%±2.33%。调查海区中型浮游动物还通过对微型浮游动物的摄食影响浮游植物生长。     

春季东海中华哲水蚤对有害藻华物种的选择性摄食

2005年4月27日—6月5日在东海有害藻华高发区的6个典型站位采样,分析了浮游植物的群落结构,并采用现场实验研究了中华哲水蚤(Calanus sinicus)的选择性摄食.结果表明,中华哲水蚤对浮游植物的选择性摄食具有食物密度依赖性.低浮游植物细胞丰度下中华哲水蚤具有明显的选择性摄食行为,高浮游植物细胞丰度下中华哲水蚤摄食选择性由偏好转变为排斥,浮游植物细胞丰度329 cells·ml^-1是中华哲水蚤由偏好趋于排斥摄食的阈值.中华哲水蚤的选择性摄食还与食物组成有关,对于食物中的微型浮游动物,中华哲水蚤无选择性或排斥摄食.有害藻华发生区中华哲水蚤对具齿原甲藻(Prorocentrum dentatum)的偏好摄食以及对米氏凯伦藻(Karenia mikimotoi)的排斥摄食,促使藻华的物种演替最终向米氏凯伦藻水华方向发展.     

一座南亚热带小型贫营养水库浮游植物群落结构及季节变化

库容大小是影响水体水动力学过程的一个重要变量,它能在很大程度决定生态系统的结构,特别是浮游植物的群落结构.为了解小型贫营养水库浮游植物的群落特点,于2006年4、8、12月对位珠海市的贫营养小型水库-吉大水库的浮游植物群落结构进行采样和计数分析.3次采样共检出浮游植物32种,浮游植物细胞丰度的变化范围在69～342 cells·mL^-1,生物量的变化范围在1.34～3.69 mg·L^-1,夏季浮游植物的丰度和生物量明显高于冬季.甲藻是最主要的优势种类,且相对优势度较为稳定.夏季,隐藻门的隐藻(Cryptomonas sp.)和绿藻门的鼓藻(Cosmarium spp.)大量出现,甲藻的相对优势度有所降低.冬季,隐藻数量急剧下降,但硅藻门的颗粒直链藻(Aulacoseira granulata)大量出现,与甲藻共同成为水体中的优势种.由降雨引起的营养盐浓度增加是浮游植物变化的主要影响因子,而透明度全年维持较高的水平为浮游植物的生长形成了有利条件,此外,较为稳定的水体和甲藻利用营养盐的能力使得甲藻成为浮游植物中的最主要的优势种.     

几株赤潮甲藻的摄食能力

采用荧光标记的方法,在营养盐限制条件下,对6株赤潮甲藻对荧光标记的海洋细菌(FLB)、金藻(FLA)和两种粒径分别为0.5μm和2.0μm的荧光微球(FM0.5和FM2.0)4种摄食对象的摄食进行了比较研究。研究结果表明,除了东海原甲藻对4种摄食对象均没有摄食外,其它5株甲藻,微小亚历山大藻、链状亚历山大藻、塔玛亚历山大藻、海洋原甲藻和微小原甲藻均具有摄食能力,但对摄食对象的选择和摄食率有差异,多数摄食率是在4 h达到最大,白天的摄食能力强于夜间。研究说明了在营养盐限制环境中,有些具有兼性营养能力的甲藻对细菌和/或更小浮游植物的摄食能力可能对维持和促进其生长具有不可忽视的作用。     

春季赤潮频发期东海微型浮游动物摄食研究

2002年4～5月在东海长江口及其邻近水域的8、11、14、23和28号5个典型站位采样。用现场稀释法对春季东海水域浮游植物的生长率和微型浮游动物对浮游植物的摄食压力等方面进行了研究．结果表明,微型浮游动物的摄食行为在东海赤潮过程起到关键作用．各站位微型浮游动物主要以急游虫、红色中缢虫和夜光藻为主,在种类上砂壳纤毛虫是主要的类群．微型浮游动物的摄食速率范围在0．28～1．13d-1,对浮游植物现存量的摄食压力范围在35．14％～811．69％。对浮游植物潜在初级生产力的摄食压力范围在74．04％～203．25％,对浮游植物碳的摄食率范围在9．58～97．91μg·L-1·d-1,靠近岸边的站位,微型浮游动物的摄食速率、对浮游植物现存量的摄食压力和对浮游植物碳的摄食率相对较高。而远离岸边的站位对浮游植物潜在初级生产力的摄食压力却较高．与世界其它海区比较此水域微型浮游动物摄食压力处于较高水平．急游虫是控制东海主要赤潮原因生物具齿原甲藻生长的关键种类．     

瓯江口春季营养盐、浮游植物和浮游动物的分布

研究2007年4月瓯江口海域(27°38′～28°02′N、120°50′～121°14′E)浮游生物空间分布特征,分析这一分布特征与营养盐和其他水文要素之间的联系.结果表明,悬浮物浓度、DIP和DIN分布特征均是近河口最高,由近河口向外数量逐渐减少.在灵昆岛南侧和东南侧近口门水域,是DIP和DIN的高值中心,但该水域高浓度悬沙使水体透光率较低,不利于浮游植物生长.在口门外侧海域,悬沙浓度已经明显降低,因而是浮游植物高密度区域.浮游植物和浮游动物丰度分布趋势基本相同,由内海向外海数量逐渐递减;其中,大型浮游动物丰度和浮游植物丰度,小型浮游动物丰度和浮游植物丰度之间显著地呈线性正相关关系.这一特征的形成,主要由瓯江口营养盐和悬浮物分布特征决定,浮游动物与浮游植物空间分布的一致性,很好地反映出浮游动物对浮游植物有效的下行控制,从而使水域生态系统在此季节保持稳定.     

浮游动物调控对浮游藻类的影响

浮游动物可以通过牧食作用来抑制浮游藻类的增长, 同时浮游动物排泄的营养盐又可以促进浮游藻类的增长,二者的强弱是浮游动物控制浮游藻类的关键。通过人为去除处理组水体中的浮游动物, 研究浮游动物生物量和群落结构的不同对富营养水体中浮游藻类的影响。研究结果显示处理组浮游动物总生物量低于空白组, 且缺乏大型枝角类溞属(Daphnia sp.); 去除浮游动物显著降低了水体中的总氮和总磷浓度以及浮游藻类生物量(叶绿素a), 同时增加了附着藻的生物量; 并且影响了浮游藻类群落结构: 对照组是空星藻(Coelastrum sp.)为优势种而处理组则为湖丝藻(Limnothrix sp.)和四集藻(Palmella sp.)。结果表明浮游动物排泄营养盐产生的上行效应大于牧食作用产生的下行效应。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.