A hot water extract of Aralia cordata activates bone marrow‐derived macrophages via a myeloid differentiation protein 88‐dependent pathway and protects mice from bacterial infection

In traditional Asian medicine, Aralia cordata (AC) is a known as a pain reliever and anti‐inflammatory drug. Although several of its biological activities have been reported, the immunomodulatory effects of a hot water extract of AC (HAC) have not yet been described. The aim of this study was to investigate whether HAC modulates the activation of macrophages, which play important roles in innate immune responses against microbial pathogens, and if so, to determine the molecular mechanisms by which HAC mediates this process. It was found that HAC activates bone marrow‐derived macrophages (BMDM) and increases amounts of nitric oxide and proinflammatory cytokines in a dose‐dependent manner. In addition, HAC was found to induce phosphorylation of NF‐κB and mitogen‐activated protein kinases (MAPKs), including c‐Jun N‐terminal kinases, extracellular signal‐regulated kinases and p38. Interestingly, these effects were absent in BMDM prepared from myeloid differentiation protein 88‐knockout mice. Polysaccharides from HAC exerted stronger immunostimulatory effects than HAC itself. Furthermore, orally administered HAC clearly enhanced clearance of the intracellular pathogen Listeria monocytogenes by boosting innate immune responses. These results demonstrate that HAC exerts immunostimulatory effects through the TLR/MyD88 and NF‐κB/MAPK signal transduction pathways.     

Vegetation differentiation in the patterned landscape of the central Everglades: importance of local and landscape drivers

Aim We present a model to account for self‐assembly of the slough–ridge–tree island patterned landscape of the central Everglades in southern Florida via feedbacks among landforms, hydrology, vegetation and biogeochemistry. We test aspects of this model by analysing vegetation composition in relation to local and landscape‐level drivers. Location We quantified vegetation composition and environmental characteristics in central Water Conservation Area (WCA) 3A, southern WCA‐3A and southern WCA‐3B in southern Florida, based on their divergence in water management and flow regimes over the past 50 years. Methods In 562 quadrats, we estimated species coverages and quantified maximum, minimum and average water depth, soil depth to bedrock, normalized difference vegetation index (NDVI) and proximity to the nearest tree island. We used non‐metric multi‐dimensional scaling (NMS) to relate compositional variation to local and landscape‐level factors, and evaluated environmental differences among eight a priori vegetation types via anova . Results Water depth and hydroperiod decreased from sloughs to ridges to tree islands, but regions also differed significantly in the abundance of several community types and the hydroregimes characterizing them. NMS revealed two significant axes of compositional variation, tied to local gradients of water depth and correlated factors, and to a landscape‐scale gradient of proximity to tall tree islands. Sawgrass height and soil thickness increased toward higher ridges, and NDVI was greatest on tree islands. Main conclusions This study supports four components of our model: positive feedback of local substrate height on itself, woody plant invasion and subsequent P transport and concentration by top predators nesting on taller tree islands, compositional shifts in sites close to tree islands due to nutrient leakage, and flow‐induced feedback against total raised area. Regional divergence in the relationship of community types to current hydroregimes appears to reflect a lag of a few years after shifts in water management; a longer lag would be expected for shifts in landscape patterning. Both local and landscape‐level drivers appear to shape vegetation composition and soil thickness in the central Everglades.     

Adaptation of the photosynthetic apparatus of the immature broadleaf trees to the flood-plain conditions

We studied the mechanisms of adaptation of immature broadleaf trees to natural placor and flood-plain conditions. Changes in the anatomical and physiological features of plants inhabiting different ecotops are considered an adaptive response of the photosynthetic apparatus.     

广东省中山市2种红树林有害生物风险分析及防控策略

【目的】了解红树林有害生物风险及其防控,维护红树林健康生长,发挥红树林的生态功能。【方法】2018—2019年,连续2年对广东省中山市红树林有害生物种类进行系统调查监测,并对薇甘菊和星天牛2种有害生物在中山市的分布状况、定殖和扩散的可能性、潜在危害性、受害对象的重要性、防控难度等进行分析,结合红树林的生态效益,参照国际有害生物风险性分析方法对两者在中山市红树林的危害风险性进行综合分析评估。【结果】调查发现,中山市红树林主要有害生物有23种,其中薇甘菊、星天牛最为严重,评估风险性R值分别为1.63和1.61,属中度危险的林业有害生物。【结论】薇甘菊和星天牛目前仅在中山市红树林局部地区发生危害,但具有明显扩散蔓延趋势,应该建立以应急除治、生物防治、生态修复等多种技术相结合的生态控制技术体系。     

梭鱼草叶片抗氧化酶、抗坏血酸-谷胱甘肽循环与乙二醛酶系统对铅胁迫的响应

本研究以液培法考察了不同浓度Pb2+胁迫下梭鱼草叶片丙二醛（MDA）与叶绿素含量、抗氧化酶活性、抗氧化剂含量及乙二醛酶系统的变化规律。结果表明：经5.0 mg L-1 Pb2+胁迫14 d和21 d时，梭鱼草叶片叶绿素含量、抗氧化酶活性[过氧化氢酶（CAT）、超氧化物歧化酶（SOD）和抗坏血酸过氧化物酶（APX）]、抗氧化剂含量[抗坏血酸（AsA）、脱氢抗坏血酸（DHA）、谷胱甘肽（GSH）、非蛋白巯基总肽（NPT）和植物螯合肽（PCs）]没有明显变化；同时，21 d时叶片细胞中甲基乙二醛（MG）含量显著增加，而MDA含量无明显增加。经10.0 mg L-1 Pb2+处理21 d时，梭鱼草叶片MDA、MG、GSH及NPT含量及过氧化物酶（POD）活性明显增加，而脱氢抗坏血酸还原酶（DHAR）、甲基乙二醛酶Ⅱ（GlyⅡ）活性呈相反变化趋势。在15.0 mg L-1 Pb2+处理期间，叶片MDA含量显著增加，此时GSH、NPT、PCs被诱导合成以螯合细胞中过量积累的Pb2+；同时，叶片POD、SOD、APX活性和AsA含量显著增加。经15.0 mg L-1 Pb2+处理21 d时，虽然梭鱼草叶片甲基乙二醛酶I（GlyI）活性明显增加，但是MG含量仍然增加，且GlyⅡ活性明显下降，此时乙二醛酶系统已经不能缓解高浓度Pb2+胁迫诱发的羰基胁迫。梭鱼草叶片对5.0 mg L-1 Pb2+具有良好的耐受性。在较高浓度（≧10.0 mg L-1）Pb2+胁迫下，梭鱼草叶片细胞膜脂过氧化作用加剧，此时其主要通过合成非蛋白巯基化合物、增加抗氧化酶活性及AsA含量以减缓氧化损伤。在试验期间，梭鱼草叶片乙二醛酶系统没有表现出明显的解毒作用。     

Genetic and clonal structures of the tree species Tilia cordata mill. in remnants of ancient forests in Denmark

The insect-pollinated forest tree Tilia cordata Mill. grows today in small fragmented populations in Denmark and other western European countries but was, in prehistoric times, a dominating species and is considered an indicator species for ancient forest. The species is known to propagate both sexually and vegetatively, forming clonal groups. Few studies have been made on the species' population genetics and on how clonality affects the population structure. The aim of this study is to evaluate the Danish gene pool by estimating genetic diversity and differentiation, as well as through exhaustive sampling describe clonal structures in some of the populations. Genetic analysis was carried out using nine nuclear microsatellite markers in nine populations, of which four were exhaustively or partly exhaustively sampled. The markers showed a high degree of genetic diversity but low differentiation between populations, with no geographic-related structure. Clonal structures were found in eight out of the nine populations. In the exhaustively sampled populations, recruitment strategies included both sexual and clonal reproduction with indications that clonality may be enhanced by management and other disturbances.