Characteristics of a landscape water with high salinity in a coastal city of China and measures for eutrophication control

Eutrophication of landscape waters is drawing public concerns in China but few studies have been conducted on the problem associated with high water salinity as what happens at Sino-Singapore Tianjin Eco-city in Tianjin, a coastal metropolis of northern China. In order to find ways for eutrophication control, a comparative study was conducted on three landscape water bodies, namely Qingjing Lake, Jiyun River and Jiyun River Oxbow, which are under varied conditions of salinity, organic, and nutrients intrusion. The spatial and temporal variations of water quality were revealed by water sampling and analyses, and correlative relationships were obtained between water salinity and other parameters related to eutrophication. By utilizing a trophic level index (TLI), the eutrophication status of the three landscape water bodies in different seasons could further be evaluated. As a result, water temperature, as expected, showed the strongest effect on eutrophication because higher TLI together with higher Chl-a concentrations tended to occur in later spring and summer seasons, while nutrient concentration, especially TP, was also the determinative factor to the eutrophication status. Of the three water bodies, the Jiyun River Oxbow showed a salinity as high as 20 g/L or more in contrast with the other two water bodies with salinity as 4–5 g/L. Although its TP concentration was usually very low (about 0.1 mg/L), it was under a moderate eutrophication status almost in all seasons, indicating that high salinity tends to induce alga growth. Dilution of saline inflow and nutrients reduction could thus be proposed as the main measures for eutrophication control of landscape waters in the study area.     

New trophic indicators and target values for an ecosystem-based management of fisheries

In the present study, we tested five trophic indicators and we demonstrated their usefulness to assess the environmental status of marine ecosystems and to implement an ecosystem approach to fisheries management (EAFM). The tested indicators include the slope of the biomass spectrum, the mean trophic level (MTL), the marine trophic index (MTI) and two newly developed indicators, the high trophic level indicator (HTI) and the apex predator indicator (API). Indicators are compared between current state and potential reference situations, using as case studies: the Celtic Sea/Bay of Biscay, North Sea and English Channel ecosystems. Trophic spectra are obtained from Ecopath models while reference situations are estimated, simulating with EcoTroph and Ecosim different fishing pressures including three candidate scenarios for an EAFM. Inter-ecosystems assessments are done using Ecopath models, simulations outputs and scientific surveys data to assess the current states of the studied ecosystems, contrast the reference situations and analyze the responses of all indicators. Sensitivity analyses are also conducted on the main simulation parameters to test the robustness of the chosen indicators. Ecosystems specific targets for EAFM are proposed for the five trophic indicators estimated from whole-ecosystem models, while in the Celtic Sea/Bay of Biscay ecosystem targets are proposed for the MTL (=3.85) and HTI (48%) estimated from standard bottom-trawl surveys. The HTI is proposed to be relevant for survey data and the API is recommended using whole-ecosystem models. We conclude that HTI and API show trends in ecosystems health better than MTI.     

Proteomic analysis of Rac1 signaling regulation by guanine nucleotide exchange factors

The small GTPase Rac1 is implicated in various cellular processes that are essential for normal cell function. Deregulation of Rac1 signaling has also been linked to a number of diseases, including cancer. The diversity of Rac1 functioning in cells is mainly attributed to its ability to bind to a multitude of downstream effectors following activation by Guanine nucleotide Exchange Factors (GEFs). Despite the identification of a large number of Rac1 binding partners, factors influencing downstream specificity are poorly defined, thus hindering the detailed understanding of both Rac1's normal and pathological functions. In a recent study, we demonstrated a role for 2 Rac-specific GEFs, Tiam1 and P-Rex1, in mediating Rac1 anti- versus pro-migratory effects, respectively. Importantly, via conducting a quantitative proteomic screen, we identified distinct changes in the Rac1 interactome following activation by either GEF, indicating that these opposing effects are mediated through GEF modulation of the Rac1 interactome. Here, we present the full list of identified Rac1 interactors together with functional annotation of the differentially regulated Rac1 binding partners. In light of this data, we also provide additional insights into known and novel signaling cascades that might account for the GEF-mediated Rac1-driven cellular effects.     

太湖贡湖湾食物网特征研究

应用稳定性同位素技术(13C和15N)研究了太湖贡湖湾食物网特征, 结果显示由于食物来源变化多样性影响, 导致贡湖的食物网结构和营养级关系变化较为复杂, 贡湖主要生物类群13C、15N值表现出较大的种间差异。消费者13C值从摇蚊幼虫的-32.3到锯齿米虾的-22.1, 其值大小与营养级的关系没有规律性。消费者平均15N值从褶纹冠蚌的10.3到位于顶端间下鳙的19.0, 随营养级位置而升高。群落中所有种类的15N、13C值之间没有相关性(r=0.1835, P0.05), 表明该食物网是非线性食物网。研究结果验证了杂食性生物有机体普遍存在于富营养化的贡湖水域生态系统中, 且13C结果表明, 浮游植物、固着藻类以及沉水植物为贡湖食物网中大多数生物有机体的主要碳源。贡湖食物链长度为4.44营养级。     

黑龙江省2010～2020年猩红热发病与气象因素的关联性研究

分析黑龙江省气象因素与猩红热发病的关系,建立时间序列模型,为今后制定更科学有效的猩红热防控策略提供参考依据。收集黑龙江省2010～2020年猩红热月发病数据以及同期气温、气压等气象资料,应用广义相加模型分析气象因素与猩红热发病之间的关联程度和形式。结果发现: 猩红热全年均有发病而且呈现出较为典型的双峰型特征,在春季的4～5月份和冬季的11～12月份发病数达到高峰;月平均气压、月平均相对湿度、月日照时数和月平均风速的P值均小于0.05,表明具有统计学意义。同时,RR(相对危险度Risk Ratio)值均小于1,即猩红热发病与四个气象因素呈负相关。黑龙江省猩红热发病每年存在两个流行高峰,主要以冬季为主,发病数随着月平均相对湿度、月日照时数、月平均风速与月平均气压的升高而降低。     

Bone defect repair in rat tibia by TGF-β1 and IGF-1 released from hydrogel scaffold

Bone repair is one of the major challenges facing reconstructive surgery. Bone regeneration is needed for the repair of large defects and fractures. The ability of TGF-β1 and IGF-1 incorporated into hydrogel scaffold to induce bone regeneration was evaluated in a rat tibia segmental defect model. External fixation was performed prior to the induction of the segmental bone defect in order to stabilize the defect site. Hydrogel scaffold containing either TGF-β, IGF-1, TGF-β + IGF-1, hydrogel containing saline or saline, were inserted in the defect. Calcified material was observed in the defects treated with TGF-β 2 weeks following the start of treatment. Bone defects treated with TGF-β, IGF-1 or TGF-β + IGF-1 revealed significant bone formation after 4 and 6 weeks when compared to the control specimens. X-ray images showed that solid bone was present at the defect site after 6 weeks of treatment with TGF-β or TGF-β + IGF-1. A less pronounced bone induction was observed in the control specimens and bones treated with IGF-1. Percent closure ratio of bone defects after 6 weeks were 40, 80, 89, and 97% for saline, hydrogel, IGF-1, TGF-β and IGF-1 + TGF-β groups, respectively. It is concluded that hydrogel scaffold can serve as a good osteoconductive matrix for growth factors, and that it provides a site for bone regeneration and enhances bone defect healing and could be used as alternative graft material. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evolution of trophic types in emperor fishes ( Lethrinus,Lethrinidae, Percoidei) based on cytochrome B gene sequence variation

Three trophic categories exist within emperor fishes, genus Lethrinus, relating to body form and dentition type. One group contains low-bodied, high speed, stalking predators with conical teeth. Another group comprises high-bodied, slow speed carnivores with molariform teeth capable of crushing hard-shelled benthic prey. A third group is also high-bodied but with conical teeth feeding mostly on small or soft-shelled benthic prey. Inferring the evolution of these trophic types within Lethrinus using morphology is problematic since these characters are typically correlated with feeding mode and are potentially homoplasious. We use mitochondrial DNA sequences, to independently determine a phylogenetic hypothesis for Lethrinus, which are not dependent on morphological characters relating to trophic categories. We analyzed complete cytochrome b gene sequences (1140 bp) for 20 species of Lethrinus, representing the three trophic types, and for 13 outgroup species, including four other representatives of the Lethrinidae. A monophyletic Lethrinidae did not resolve, but the monophyly of Lethrinus is well supported. In addition, two major clades within Lethrinus are well supported. One of these clades exclusively contains low-bodied species with conical teeth while the other clade only comprises the high-bodied species with molariform teeth. A high-bodied species with conical teeth, Lethrinus miniatus, appears most ancestral and sister to all other Lethrinus species. We hypothesize that this generalist trophic type was the evolutionary precursor to both of the other primary trophic types.