Comparative analysis of leaf trichome structure and composition of epicuticular flavonoids in Finnish birch species

The morphology, ultrastructure, density and distribution of trichomes on leaves of Betula pendula, B. pubescens ssp. pubescens, B. pubescens ssp. czerepanovii and B. nana were examined by means of light, scanning and transmission electron microscopy. The composition of flavonoids in ethanolic leaf surface extracts was analysed by high pressure liquid chromatography. All taxa examined contained both glandular and non-glandular trichomes (short and/or long hairs) but differed from each other in trichome ultrastructure, density and location on the leaf. Leaves of B. pubescens were more hairy than those of B. pendula, but the latter species had a higher density of glandular trichomes. Of the two subspecies of B. pubescens, leaves of ssp. pubescens had more short hairs on the leaf surface and four times the density of glandular trichomes of leaves of ssp. czerepanovii, whereas, in the latter subspecies, short hairs occurred largely on leaf veins, as in B. nana. The glandular trichomes were peltate glands, consisting of medullar and cortical cells, which differed structurally. Cortical cells possessed numerous small, poorly developed plastids and small vacuoles, whereas medullar cells had several large plastids with well-developed thylakoid systems and fewer vacuoles. In B. pubescens subspecies, vacuoles of the glandular cells contained osmiophilic deposits, which were probably phenolic, whereas in B. pendula, vacuoles of glandular trichomes were characterized by the presence of numerous myelin-like membranes. The composition of epicuticular flavonoids also differed among species. The two subspecies of B. pubescens and B. nana shared the same 12 compounds, but five of these occurred only in trace amounts in B. nana. Leaf surface extracts of B. pendula contained just six flavonoids, three of which occurred only in this species. In summary, the structure, density and distribution of leaf trichomes and the composition of epicuticular flavonoids represent good taxonomic markers for Finnish birch species.     

Influence of elevated CO2 and O3 on Betula pendula Roth crown structure

Elevated CO(2) and ozone effects were studied singly and in combination on the crown structure of two Betula pendula clones. Measurements were made at the end of the second fumigation period in an open-top-chamber experiment with 9-year-old trees. Shoot ramification (number of long and short daughter shoots), shoot length, and number of metamers, leaves and buds were measured at four positions in every tree. As a result of increased temperature, trees in chambers had longer shoots and more frequent shoot ramification than control trees not enclosed in chambers. Ozone treatment decreased shoot ramification significantly. Additionally, ozone treatment resulted in an increased number of metamers in one clone. There was no statistically significant interaction between ozone effect and crown position; however, there was a slight tendency for the lower crown to be more affected by ozone. Elevated CO(2) caused a significant increase in the number of long-shoot metamers. Therefore, 2x ambient CO(2) concentration partly ameliorated the negative effect of ozone because the increased number of leaves per shoot counteracted the decreased branching. Although the main effects of elevated ozone and CO(2) were similar in the two clones, slight, statistically insignificant, differences appeared in their responses when interactions with crown position were considered.     

Possibilities of subunit localization with fluorescent protein tags and electron microscopy examplified by a cyanobacterial NDH-1 study

Cyanobacterial NDH-1 is a multisubunit complex involved in proton translocation, cyclic electron flow around photosystem I and CO₂ uptake. The function and location of several of its small subunits are unknown. In this work, the location of the small subunits NdhL, -M, -N, -O and CupS of Synechocystis 6803 NDH-1 was established by electron microscopy (EM) and single particle analysis. To perform this, the subunits were enlarged by fusion with the YFP protein. After classification of projections, the position of the YFP tag was revealed; all five subunits are integrated in the membrane domain. The results on NDH-1 demonstrate that a GFP tag can be revealed after data processing of EM data sets of moderate size, thus showing that this way of labeling is a fast and reliable way for subunit mapping in multisubunit complexes after partial purification.     

Descending interneurones from the brain and suboesophageal ganglia and their role in the control of locust behaviour

Lesion and stimulation experiments suggest that the suboesophageal ganglion (SOG) plays a special role in the control of insect behaviour: in bilateral coordination and by maintaining ongoing motor activity. Anatomical observations indicate that there are descending interneurones (DINs) originating in the SOG in addition to those from the brain. An SOG preparation for sampling both types of DIN intracellularly in walking locusts is described. Forty-three units showing activity changes during leg movements and walking were recorded. Using dye injection six were shown to be through-running axons; one was an SOG ascending interneurone; and eight were SOG DINs, 7 contralateral, one ipsilateral. All fired before or during movements and received various sensory inputs. Many gave complex responses to different modalities, several showing directional preferences. Some SOG neurones showed spontaneous changes in activity; activity outlasting movements; or responses to passive as well as active movements. These preliminary results suggest neuronal substrates for the special functions of the SOG in behaviour. They also indicate that DINs, rather than being simple relays, are part of a dynamic network which includes the motor centres. Regulation of complex and subtle aspects of behaviour may be achieved by dynamic and sequential patterns of activity in groups of DINs, some of which may be multifunctional.     

Detailed identification of desert-originated bacteria carried by Asian dust storms to Japan

Several halotolerant bacteria were isolated from dust allowed to settle passively on saline medium in Higashi-Hiroshima, Japan during Asia dust events in 2005–2006. The primary identification, based on the sequence similarity of the 16S rRNA gene, revealed that these isolates were strains of Bacillus subtilis, B. licheniformis, Staphylococcus epidermidis, Gracillibacillus sp., and Halomonas venusta. A parallel investigation carried out on desert sand collected directly from sand dunes in Dunhuang, Gobi Desert, China resulted in the revivification of seven bacterial strains that were highly identical to the B. subtilis and B. licheniformis strains obtained in Higashi-Hiroshima (99.7 and 100% of 16S rDNA sequence similarity, respectively). A subsequent genetic analysis on the group of B. licheniformis isolates based on the universally house-keeping genes, gyrB and parE, revealed high sequence similarities in both genes among the strains of both locations (99.0–99.4%), which clustered them in a monophyletic line. Phenotype characterized by numerical taxonomy for 150 physiological tests confirmed the close relatedness between strains (similarity coefficient S _SM = 96.0%). The remarkable agreement between phenotype and genotype of the bacterial isolates allows us to conclude that there may have been an aerosolized dispersion of a Gobi Desert B. licheniformis by dust storms to Japan. This study provides evidence of microbial transport by yellow dust events in North-East Asia.     

Free-air exposure systems to scale up ozone research to mature trees

Because seedlings and mature trees do not necessarily respond similarly to O(3) stress, it is critically important that exposure systems be developed that allow exposure of seedlings through to mature trees. Here we describe three different O(3) Free-Air Exposure Systems that have been used successfully for exposure at all growth stages. These systems of spatially uniform O(3) release have been shown to provide reliable O(3) exposure with minimal, if any, impact on the microclimate. This methodology offers a welcome alternative to chamber studies which had severe space constraints precluding stand or community-level studies and substantial chamber effects on the microclimate and, hence physiological tree performance.     

黄海夏季虾类群落结构及其与环境因子的关系

根据2014年8月在黄海进行的渔业资源和环境综合调查数据,应用相对重要性指数、生物多样性指数和多元统计分析等方法对黄海夏季虾类群落结构及其与环境因子的关系进行了研究.结果表明： 本次调查共捕获虾类20种,隶属于3目10科16属.各调查站点虾类相对资源丰度为13～45047 g·h^-1,平均资源丰度为6838 g·h^-1.优势种为脊腹褐虾,常见种为中华安乐虾,偶见种为戴氏赤虾、葛氏长臂虾、口虾蛄.各站点多样性指数(H)变化范围为0.007～1.538,平均值为0.391;丰富度指数(D)变化范围为0.101～1.138,平均值为0.374;均匀度指数(J)变化范围为0.006～0.947,平均值为0.298.等级聚类分析(Cluster)与非度量多维标度分析(MDS)表明,调查范围基本以45 m等深线为界将所有站点分成两个组群：冷水团组群(Ⅰ)和沿岸组群(Ⅱ),ANOSIM分析表明两组群差异极显著.BIOENV分析表明,影响黄海夏季虾类群落空间结构的最主要环境因子是底层水温与底层盐度.黄海夏季虾类群落以冷水团组群占绝对优势,黄海冷水团对黄海夏季虾类群落的分布格局具有决定性的影响.     

Population genetic diversity of the clonal self‐incompatible herbaceous plant Linaria vulgaris along an urbanization gradient

How increasing urbanization affects biodiversity is one of the most understudied aspects of global change biology. It is, however, known that it may negatively affect plant population genetic diversity in numerous ways, for example through its negative effects on plant population size, between‐population connectivity, and reproductive success. Therefore, it is important to investigate to what extent different levels of urbanization result in these negative phenomena. Here we used microsatellite markers to investigate urbanization effects on the population genetic structure of 23 populations of the self‐incompatible, partially clonal herb Linaria vulgaris which were sampled across a gradient of urbanization. Clonal diversity as measured by the Pareto‐parameter varied between 1.11 and 2.97 and was negatively correlated to both the degree of urbanization and to population size. Urbanization and population size were not interrelated. The least clonally rich populations also experienced significantly reduced seed set. Irrespective of the degree of urbanization, L. vulgaris populations exhibited strong genetic differentiation (F_ST = 0.33) and there was no significant correlation between genetic and geographic distances, suggesting low gene flow among populations. In conclusion, we showed that urbanization negatively affected fitness of L. vulgaris populations through decreasing their clonal diversity and reproductive success, an effect that may be exacerbated by the low gene flow between populations. Although the effect was modest, the results could probably be extrapolated to bigger cities where it would be considerably more pronounced.     

Tree diversity in 30-year chronosequences of cool-humid forests

Tree data collected in four inventories of twelve permanent sampling plots during 30 years were analyzed to determine to what extent the abundance of the ubiquitous balsam fir (Abies balsamea) drives tree diversity in mixed stands of Eastern Cape Breton Island, Canada. Dominant deciduous species comprised yellow birch (Betula allegheniensis), sugar maple (Acer saccharum), and American beech (Fagus grandifolia). Tree species richness ranged from 2 to 6. The Shannon–Wiener diversity index indicated that high fir proportion decreased tree species diversity (H’) and structural evenness (J’). The basal area ratio for year 30 over year 1 provided an index of resilience (R) for forest stands subject to natural self-thinning and epidemic insect infestations. There was no significant effect of fir admixture on R since basal area losses due to fir decline were offset within the 30-year period largely by hardwood increases. Stand dynamics were however, structurally stratified due to low R-values for low-diameter trees. The indices H’, J’, and R are recommended for assessing the naturalness and apparent resilience function of tree diversity and large trees in mixed forests of low species richness.     

Spartina alterniflora invasions and effects on crab communities in a western Pacific estuary

We investigated Spartina alterniflora invasions, their relationship with shoreline dynamics and effects on crab communities in the Yellow River estuary, China, where shoreline dynamics have been accelerated due to human-mediated estuarine sediment deposition and sea-level rise. We determined the distribution of Spartina with extensive ground surveys, and quantified shoreline dynamics between 2001 and 2009 by interpreting satellite images. We used pitfall traps to sample crab populations in Spartina-invaded habitats and non-invaded mudflats in 2009 and 2010. Large areas (>0.5 km²) of Spartina plants were found at three locations in the estuary. The seaward limit of Spartina at each location generally coincided with the present shoreline, regardless of historical shoreline advance or retreat. Crab communities in Spartina-invaded habitats significantly differed from those in non-invaded habitats. The total number and biomass of crabs caught per trap were much higher in Spartina-invaded habitats than in non-invaded habitats, however, species richness and Shannon diversity were much lower. These results suggest that Spartina invasions are likely to keep pace with shoreline dynamics accelerated by global change and have significant ecological consequences for crab communities. These issues should be taken into account to improve the use and management of Spartina, especially in rapidly accreting estuaries with large-area mudflats that are important habitats but prone to Spartina invasions.