Interactions between Zooplankton and Crude Oil: Toxic Effects and Bioaccumulation of Polycyclic Aromatic Hydrocarbons

We conducted ship-, shore- and laboratory-based crude oil exposure experiments to investigate (1) the effects of crude oil (Louisiana light sweet oil) on survival and bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in mesozooplankton communities, (2) the lethal effects of dispersant (Corexit 9500A) and dispersant-treated oil on mesozooplankton, (3) the influence of UVB radiation/sunlight exposure on the toxicity of dispersed crude oil to mesozooplankton, and (4) the role of marine protozoans on the sublethal effects of crude oil and in the bioaccumulation of PAHs in the copepod Acartia tonsa. Mortality of mesozooplankton increased with increasing oil concentration following a sigmoid model with a median lethal concentration of 32.4 µl L⁻¹ in 16 h. At the ratio of dispersant to oil commonly used in the treatment of oil spills (i.e. 1∶20), dispersant (0.25 µl L⁻¹) and dispersant- treated oil were 2.3 and 3.4 times more toxic, respectively, than crude oil alone (5 µl L⁻¹) to mesozooplankton. UVB radiation increased the lethal effects of dispersed crude oil in mesozooplankton communities by 35%. We observed selective bioaccumulation of five PAHs, fluoranthene, phenanthrene, pyrene, chrysene and benzo[b]fluoranthene in both mesozooplankton communities and in the copepod A. tonsa. The presence of the protozoan Oxyrrhis marina reduced sublethal effects of oil on A. tonsa and was related to lower accumulations of PAHs in tissues and fecal pellets, suggesting that protozoa may be important in mitigating the harmful effects of crude oil exposure in copepods and the transfer of PAHs to higher trophic levels. Overall, our results indicate that the negative impact of oil spills on mesozooplankton may be increased by the use of chemical dispersant and UV radiation, but attenuated by crude oil-microbial food webs interactions, and that both mesozooplankton and protozoans may play an important role in fate of PAHs in marine environments.     

Integrating human stem cell expansion and neuronal differentiation in bioreactors

Background  

Human stem cells are cellular resources with outstanding potential for cell therapy. However, for the fulfillment of this application, major challenges remain to be met. Of paramount importance is the development of robust systems for in vitro stem cell expansion and differentiation. In this work, we successfully developed an efficient scalable bioprocess for the fast production of human neurons.     

基于多聚化重组抗原的检测戊型肝炎病毒IgM与IgG抗体的ELISA的建立及初步评估

建立并评估分别检测戊型肝炎（戊肝）病毒IgM与IgG抗体的捕获法及间接法ELISA。以原核表达的多聚化重组HEV蛋白为抗原,建立戊肝捕获法IgM ELISA(E2-IgM)和间接法IgG ELISA(E2-IgG).利用29只实验感染猴系列血清及多份临床急性肝炎血清、正常人血清以及单克隆抗体评估所建立的方法的敏感法与特异性,并与商品化试剂（Genelabs公司抗－HEV IgG和IgM试剂,GL－IgM/GL-IgM)进行比较。29只恒河猴E2－IgM和E2－IgG的阳转率均为100％,其中75％在感染后4周内阳转,均早于ALT异常时间。E2－IgM持续2－14周,平均6周;E2－IgG在70周时仍无一阴转。GL－IgG阳转率为79．3％（23／29）,多数晚于ALT异常时间,平均持续约18周,但最长为1只在感染后70周时仍为阳性。用E2－IgM试剂盒检测928份正常人血清,仅2份OD值略高于0．2。检测510份临床急性肝炎血清,可明显将其区分为2个部分,一个部分OD值小于0．2,其OD值分布与正常人相似;另一个部分OD值大于0．4,共131份,其中109份大于1．0。可能分别对应于急性肝炎中的非戊肝患者和戊肝患者。119份非甲－丙急性肝炎中,E2－IgM阳性57份,GL－IgM阳性29份（E2－IgM均阳性）。5060份普通人群血清的E2－IgG OD值在0．2以下,形成一个近似对数正态峰,均值为0．022,在OD值0．4以上则分布均匀。用E2－IgG试剂检测200份临床急性肝炎血清,结果OD值0．2以下也形成一个与普通人群类似的近似对数正态峰,但OD值在大于1．0－4．0间形成另一个尖峰（峰值在OD2．5处）,其中多数E2－IgM阳性。抗－HEV单抗可明显阻断E2－IgM及E2－IgG,单抗Fab段的阻断效果与完整抗体类似,提示这种阻断是表位特异的。建立的戊肝IgM试剂和IgG试剂具有良好的敏感性与特异性。IgM试剂适用于临床戊肝诊断,IgG试剂适用于既往戊肝感染诊断。     

Four new species of Trembleya (Melastomataceae: Microlicieae) from Serra do Cabral, Minas Gerais, Brazil

Nine species of the Brazilian endemic genus, Trembleya, were collected during a floristic survey of the tribe Microlicieae on Serra do Cabral, an isolated mountain range in north-central Minas Gerais State, Brazil. Four of these are newly described and illustrated here: Trembleya inversa, T. purpurascens, T. rubra, and T. serrulata, represent new taxa for the genus. These new species appear to be endemic to Serra do Cabral where they occur in campo rupestre and cerrado vegetation. Serra do Cabral has the distinction of harboring more species of Trembleya than any other mountain range in Brazil.     

The quantitative role of microzooplankton grazing in dimethylsulfide (DMS) production in the NW Mediterranean

The ubiquitous, biogenic trace gas dimethylsulfide (DMS) represents the largest natural source of atmospheric sulfur. Given DMS involvement in cloud formation and climate, understanding and parameterizing the oceanic DMS source and cycling processes is a necessary challenge. We report DMS cycling rates from microzooplankton dilution grazing experiments conducted monthly during 1 year in coastal northwestern Mediterranean waters. Concentrations of DMS, its algal precursor dimethylsulfoniopropionate (DMSPt) and chlorophyll a (Chla) ranged 0.9–11 nmol L^?1, 10–71 nmol L^?1, and 0.2–1.5 µg L^?1, respectively. By comparing the growth and stock production rates of the DMSP-producing algae to those of total phytoplankton, we estimated that 3?±?4% (range 0.4–12%) of the carbon primary production was invested in DMSP biosynthesis. Microzooplankton grazing rates on DMSP-producing phytoplankton (0.46–1.45 day^?1) were generally higher than those on the bulk assemblage (0.08–0.99 day^?1), except in midsummer months. This could have been due to the smaller size of most DMSP producers. There was no indication of micrograzer selection against DMSP-containing phytoplankton, since they were not grazed at lower rates than the bulk phytoplankton assemblage. A proportion of 6–20% of the grazed DMSP was converted into DMS, and this grazing-derived production accounted for 32–96% of dark gross DMS production by the total community. Bacteria consumed daily?≤?14–100% of the gross DMS production, which resulted in biological DMS turnover times of 1 to?≥?10 days. Throughout the year, grazing-mediated DMS production explained 73% of the variance in the DMS concentration, implying that microzooplankton grazing plays a major role in controlling DMS concentration in surface waters across a broad range of environmental and productivity conditions in the Mediterranean Sea. These findings should help improve the representation of herbivore grazing in prognostic models to predict the distribution and dynamics of the global DMS emission and its feedback response to changing climate.     

Three new Mesoamerican species of Topobea (Melastomataceae)

Three new species ofTopobea are described from species-rich, humid forest environments in Costa Rica and Panama. Discussions, diagnostic illustrations, phenological notes, and a distribution map are provided forTopobea intricata, T. lentii, andT. mephersonii.     

Bioresponsive matrices in drug delivery

For years, the field of drug delivery has focused on (1) controlling the release of a therapeutic and (2) targeting the therapeutic to a specific cell type. These research endeavors have concentrated mainly on the development of new degradable polymers and molecule-labeled drug delivery vehicles. Recent interest in biomaterials that respond to their environment have opened new methods to trigger the release of drugs and localize the therapeutic within a particular site. These novel biomaterials, usually termed "smart" or "intelligent", are able to deliver a therapeutic agent based on either environmental cues or a remote stimulus. Stimuli-responsive materials could potentially elicit a therapeutically effective dose without adverse side effects. Polymers responding to different stimuli, such as pH, light, temperature, ultrasound, magnetism, or biomolecules have been investigated as potential drug delivery vehicles. This review describes the most recent advances in "smart" drug delivery systems that respond to one or multiple stimuli.