Xylem Cavitation in Nodes and Internodes of Whole Chorisia insignis H.B. et K. Plants Subjected to Water Stress: Relations Between Xylem Conduit Size and Cavitation

Measurements of cavitation occurring in xylem conduits of differentstem parts in whole Chorisia insignis H.B. et. K. plants subjectedto water stress are reported. Pre-stressed plants were shownto undergo cavitation over 10 times greater than watered ones.The most vulnerable parts of plants were one-year-old twigswhere cavitation reached a peak of over 50 acoustic emissions(AE) min^–1 while in two-year-old twigs AE min^–1were about one half this value. Stem zones were found wherecavitation was typically very low even during water stress:these were one-year-old nodes and junctions where branches meet.Measurements of the inside diameters of xylem conduits and distributionof conduit ends in stem parts where AE were detected, showedthat nodes have a significantly larger percentage of narrowxylem conduits than internodes. Similar ‘constricted zones’were found injunctions with respect to two-year-old twigs. Hereabout 50 per cent of the xylem conduits were as narrow as 20to 50 µm in diameter. The distribution of xylem conduitends show about 3 per cent of them ending in the nodes and 1per cent in the internodes of one-year-old twigs. About 11.6per cent of xylem conduits end in the junctions and about ahalf in two-year-old internodes. Our data would give furtherexperimental evidence to the functional concept of ‘plantsegmentation’ into zones (internodes) more efficient inwater conduction, i.e. with wider xylem conduits but more vulnerableto cavitation and others (nodes and junctions) with oppositecharacteristics. Chorisia insignis, acoustic emissions, water stress, nodes, internodes, xylem conduit size, vessel ends     

Root hydraulic conductance of six forest trees: possible adaptive significance of seasonal changes

ABSTRACT

Root hydraulic conductance (K_R was measured in terms of the ratio of volume flow through roots (F) and to the pressure (P) driving the flow in six forest trees growing in habitats characterized by different water availabilities Le. Acer campestre L., Castanea sativa Miller, Fraxinus ornus L., Fraxinus oxycarpa Bieb., Ceratonia siliqua L. and Olea oleaster Hoffmg. et Link. Measurements were made in May, August and November 1996. K_R as normalized for unit leaf surface area (K_RL), was higher in species growing in humid environments (A. campestre and C. sativa) than in others (C. siliqua and O. oleaster) typical of aria zones. A. campestre and C. sativa showed declining K_RL values from spring to autumn while the latter had highest K_RL values in summer. This is in agreement with the typical drought avoidance strategy of C. siliqua which is based on large water losses balanced by equal water uptake from the soil. Plots of F and of A (leaf surface area) to K_RL as well as annual percent changes in F, A_L and K_RL suggest that changes in K_RL are mainly due to analogous changes in F, except for O. oleaster where opposite balanced changes in F and A_L contributed in maintaining the K_RL constant from August to November.     

Widespread hybridization between the Greater Spotted Eagle Aquila clanga and the Lesser Spotted Eagle Aquila pomarina (Aves: Accipitriformes) in Europe

Hybridization is a significant threat for endangered species and could potentially even lead to their extinction. This concern applies to the globally vulnerable Greater Spotted Eagle Aquila clanga, a species that co‐occurs, and potentially interbreeds, with the more common Lesser Spotted Eagle Aquila pomarina in a vast area of Eastern Europe. We applied single nucleotide polymorphism (SNP) and microsatellite markers in order to study hybridization and introgression in 14 European spotted eagle populations. We detected hybridization and/or introgression in all studied sympatric populations. In most regions, hybridization took place prevalently between A. pomarina males and A. clanga females, with introgression to the more common A. pomarina. However, such a pattern was not as obvious in regions where A. clanga is still numerous. In the course of 16 years of genetic monitoring of a mixed population in Estonia, we observed the abandonment of A. clanga breeding territories and the replacement of A. clanga pairs by A. pomarina, whereby on several occasions hybridization was an intermediate step before the disappearance of A. clanga. Although the total number of Estonian A. clanga × A. pomarina pairs was twice as high as that of A. clanga pairs, the number of pairs recorded yearly were approximately equal, which suggests a higher turnover rate in interbreeding pairs. This study shows that interspecific introgressive hybridization occurs rather frequently in a hybrid zone at least 1700‐km wide: it poses an additional threat for the vulnerable A. clanga, and may contribute to the extinction of its populations. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 725–736.     

Feasibility Study of Using Centrifuge for Investigating LNAPL Migration in Unsaturated Soils

Centrifuge modeling appears potentially useful for studying geo-environmental problems such as pollutant migration in subsurface systems. In this study, the “modeling of models” technique was used to validate the feasibility of using a geotechnical centrifuge to model the transport behavior of light non-aqueous phase liquids (LNAPLs) in unsaturated soils. All the experiments were conducted to simulate a gasoline spill from a leaking underground storage tank (UST) and the subsequent subsurface migration of the gasoline. When the gravity in the centrifuge reached the desired g-level, the gasoline was released from the UST and then it migrated in the unsaturated soil corresponding to a prototype time equivalent of one year. After the centrifuge tests, soil samples were collected using sampling tubes and the concentrations of individual constituent in the LNAPL were directly measured by means of gas chromatograph analysis. Results obtained from the centrifuge tests at different g-levels show that similar migration patterns are found for LNAPL transport in unsaturated porous media. The location of the peak concentration and the behavior of lateral spreading can be adequately described. In addition, centrifuge test data show that the migration pattern of LNAPLs is related to the soil type and the physical properties of individual constituents in the LNAPLs.     

Extreme climatic events reduce ocean productivity and larval supply in a tropical reef ecosystem

Increasing ocean temperatures due to global warming are predicted to have negative effects on coral reef fishes. El Niño events are associated with elevated water temperatures at large spatial (1000s of km) and temporal (annual) scales, providing environmental conditions that enable temperature effects on reef fishes to be tested directly. We compared remote sensing data of sea surface temperature (SST) anomalies, surface current flow and chlorophyll‐a (Chl‐a) concentration with monthly patterns in larval supply of coral reef fishes in nearshore waters around Rangiroa Atoll (French Polynesia) from January 1996 to March 2000. This time included an intense El Niño (April 1997–May 1998) event between two periods of La Niña (January–March 1996 and August 1998–March 2000) conditions. There was a strong relationship between the timing of the El Niño event, current flow, ocean productivity (as measured by Chl‐a) and larval supply. In the warm conditions of the event, there was an increase in the SST anomaly index up to 3.5 °C above mean values and a decrease in the strength of the westward surface current toward the reef. These conditions coincided with low concentrations of Chl‐a (mean: 0.06 mg m^?3, SE ± 0.004) and a 51% decline in larval supply from mean values. Conversely, during strong La Niña conditions when SST anomalies were almost 2 °C below mean values and there was a strong westward surface current, Chl‐a concentration was 150% greater than mean values and larval supply was 249% greater. A lag in larval supply suggested that productivity maybe affecting both the production of larvae by adults and larval survival. Our results suggest that warming temperatures in the world's oceans will have negative effects on the reproduction of reef fishes and survival of their larvae within the plankton, ultimately impacting on the replenishment of benthic populations.     

超选择性股动脉内骨髓单个核细胞移植治疗股骨头坏死187例

目的 研究自体骨髓单个核细胞移植对股骨头坏死患者缺血状态的改善程度和治疗效果.方法 选取2004 年7 月至2010 年11 月期间187 例252 髋股骨头坏死患者,应用自体骨髓单个核细胞移植治疗,分别采集 187 例患者骨髓200 -360 ml,采用 Ficoll 密度梯度离心法分离单个核细胞,单个核细胞总数为（2.4 ~ 7.8）× 108 个,流式细胞仪检测 CD34＋ 细胞和 CD133＋ 细胞在所分离出的干细胞悬液中的含量分别为2.47﹪± 0.58﹪和1.29﹪± 0.35﹪,然后将单个核细胞用生理盐水制备成细胞悬液 20 - 30 ml,使用数字减影血管造影技术（DSA）行超选择性股骨头供血动脉内干细胞移植术.按世界骨循环研究学会（ARCO）对骨坏死分期,设自身前后对照观察疗效.移植术后第 3、6、12、24、36 和48 个月,根据髋关节 Harris 评分评价疗效,移植术后6 个月通过复查患者股骨头供血动脉 DSA,观察其新生血管形成情况,以后每隔 6 个月采用影像学方法观察股骨头形态学变化.结果 （1）临床疗效：对接受自体骨髓单个核细胞移植治疗的187 例患者随访 3 ~ 48（24.2 ± 4.5）个月,其中髋关节疼痛缓解者 158 例（占患者总数的 84.5﹪）,髋关节功能改善者 146 例（占患者总数的 78.1﹪）,行走间距延长者 149 例（占患者总数的 79.7﹪）;（2）影像学检查：干细胞移植术后 6 个月187 例患者中54 例行股骨头供血动脉 DSA 检查,48 例显示供血动脉较移植术前明显增多、增粗,血流速度增快,12 ~ 24个月后 72 例患者股骨头区骨质病变获得改善.结论 超选择性动脉内骨髓单个核细胞移植方法简便、安全有效,对因缺血导致坏死的股骨头无再次损伤,能够有效治疗缺血性股骨头坏死.