芒蛱蝶西藏一个新纪录及川藏地区黄缘蛱蝶的历史记录

在2017年6-7月对藏东南地区蝶类资源进行调查时,于墨脱县采集到了2枚芒蛱蝶Euripusnyctelius(鳞翅目:蛱蝶科)标本,经鉴定为西藏新纪种,同时也是首次在西藏发现芒蛱蝶属;于察隅县采集到1枚黄缘蛱蝶Nymphalisantiopa(鳞翅目:蛱蝶科),兹此列举诸多川藏地区黄缘蛱蝶的历史采集记录;并结合西藏处于古北区和东洋区生物交界带的地理位置,对在西藏发现两种蝴蝶的特殊意义进行了简要讨论。     

Direct and indirect effects of additions of chromophoric dissolved organic matter on zooplankton during large‐scale mesocosm experiments in an oligotrophic lake

相似文献   

The importance of species pool size for community composition

We investigated if an increase in species pool size leads to more pronounced turnover in local communities and assessed if this increase relates to stronger competition for environmental niches or to more random placement of species. We compared compositional turnover of pteridophytes (ferns and lycophytes) at 15 sites in mountain ecosystems on 13 islands in southeast Asia and Melanesia that mainly differed in the size of their species pool. Each site was sampled with 16 plots of 20 × 20 m². Using multiple regression on distance matrices, we investigated the relationship between environmental distance and compositional turnover at different spatial extents within sites with different species pool sizes. Additionally, we tested the hypothesis that the intensity of competition increases with increasing species pool size. This was done by assessing how realized niche overlap and unevenness of communities relate to environmental distance and species pool size. With increasing species pool size, there was an increase in: a) proportional turnover in community composition, b) the importance of environmental distance for explaining turnover in community composition and c) a decrease in environmental niche overlap between species indicating an increasing importance of competition for community composition. Our results support the idea that increasing species pool size increases the competition for available environmental niches, and thereby leads to a tighter connection between environmental factors and community composition.     

Ordered Network of Interconnected SnO2 Nanoparticles for Excellent Lithium‐Ion Storage

An ordered network of interconnected tin oxide (SnO₂) nanoparticles with a unique 3D architecture and an excellent lithium‐ion (Li‐ion) storage performance is derived for the first time through hydrolysis and thermal self‐assembly of the solid alkoxide precursor. Mesoporous anodes composed of these ≈9 nm‐sized SnO₂ particles exhibit substantially higher specific capacities, rate performance, coulombic efficiency, and cycling stabilities compared with disordered nanoparticles and commercial SnO₂. A discharge capacity of 778 mAh g^–1, which is very close to the theoretical limit of 781 mAh g^–1, is achieved at a current density of 0.1 C. Even at high rates of 2 C (1.5 A g^–1) and 6 C (4.7 A g^–1), these ordered SnO₂ nanoparticles retain stable specific capacities of 430 and 300 mAh g^–1, respectively, after 100 cycles. Interconnection between individual nanoparticles and structural integrity of the SnO₂ electrodes are preserved through numerous charge–discharge process cycles. The significantly better electrochemical performance of ordered SnO₂ nanoparticles with a tap density of 1.60 g cm^–3 is attributed to the superior electrode/electrolyte contact, Li‐ion diffusion, absence of particle agglomeration, and improved strain relaxation (due to tiny space available for the local expansion). This comprehensive study demonstrates the necessity of mesoporosity and interconnection between individual nanoparticles for improving the Li‐ion storage electrochemical performance of SnO₂ anodes.     

A cyclic-di-GMP receptor required for bacterial exopolysaccharide production

Bis-(3',5')-cyclic-dimeric-guanosine monophosphate (c-di-GMP) has been shown to be a global regulatory molecule that modulates the reciprocal responses of bacteria to activate either virulence pathways or biofilm formation. The mechanism of c-di-GMP signal transduction, including recognition of c-di-GMP and subsequent phenotypic regulation, remain largely uncharacterized. The key components of these regulatory pathways are the various adaptor proteins (c-di-GMP receptors). There is compelling evidence suggesting that, in addition to PilZ domains, there are other unidentified c-di-GMP receptors. Here we show that the PelD protein of Pseudomonas aeruginosa is a novel c-di-GMP receptor that mediates c-di-GMP regulation of PEL polysaccharide biosynthesis. Analysis of PelD orthologues identified a number of conserved residues that are required for c-di-GMP binding as well as synthesis of the PEL polysaccharide. Secondary structure similarities of PelD to the inhibitory site of diguanylate cyclase suggest that a common fold can act as a platform to bind c-di-GMP. The combination of a c-di-GMP binding site with a variety of output signalling motifs within one protein domain provides an explanation for the specificity for different cellular responses to this regulatory dinucleotide.     

Nitrogen deficiency in Arabidopsis affects galactolipid composition and gene expression and results in accumulation of fatty acid phytyl esters

Nitrogen is an essential nutrient for plants because it represents a major constituent of numerous cellular compounds, including proteins, amino acids, nucleic acids and lipids. While N deprivation is known to have severe consequences for primary carbon metabolism, the effect on chloroplast lipid metabolism has not been analysed in higher plants. Nitrogen limitation in Arabidopsis led to a decrease in the chloroplast galactolipid monogalactosyldiacylglycerol (MGDG) and a concomitant increase in digalactosyldiacylglycerol (DGDG), which correlated with an elevated expression of the DGDG synthase genes DGD1 and DGD2. The amounts of triacylglycerol and free fatty acids increased during N deprivation. Furthermore, phytyl esters accumulated containing medium-chain fatty acids (12:0, 14:0) and a large amount of hexadecatrienoic acid (16:3). Fatty acid phytyl esters were localized to chloroplasts, in particular to thylakoids and plastoglobules. Different polyunsaturated acyl groups were found in phytyl esters accumulating in Arabidopsis lipid mutants and in other plants, including 16:3 and 18:3 species. Therefore N deficiency in higher plants results in a co-ordinated breakdown of galactolipids and chlorophyll with deposition of specific fatty acid phytyl esters in thylakoids and plastoglobules of chloroplasts.     

Plastoglobules: versatile lipoprotein particles in plastids

Plastoglobules are plastid-localized lipoprotein particles that contain tocopherols and other lipid isoprenoid-derived metabolites, as well as structural proteins named plastoglobulins. Surprisingly, recent publications show that plastoglobules contain enzymes involved in the metabolism of these secondary metabolites, as well as enzymes of unknown function. The size and number of plastoglobules vary during plastid development and differentiation, and strongly increase during light stress, senescence and in mutants blocked in thylakoid formation. Given that plastoglobules are contiguous with the outer lipid leaflet of the thylakoid membrane, it is highly plausible that a function of plastoglobules is the active channeling of lipid molecules and lipid breakdown products. Understanding the function of plastoglobules should provide a foundation for improving the nutritional value and yield of plants.     

Vertical stratification of vascular epiphytes in submontane and montane forest of the Bolivian Andes: the importance of the understory

We studied species richness, composition, and vertical distribution of vascular epiphytes at two sites in the Bolivian Andes. To account for the epiphyte flora on understory trees, epiphytes on shrubs and small trees were sampled in 20 × 20 m² subplots around each sampled canopy tree; this understory zone U is introduced as an addition to the well-established five vertical Johansson tree zones. More than 20% of about 500 species recorded were found only in the understory subplots, including ca. 40% of aroids, 35%–40% of piperoids, and 25%–30% of ferns. Habitat generalists (occurring in three or more zones) were most common, contributing about 50% of all species, specialists (occurring only in two zones, or in three continuous ones) 34%–42%, and hemiepiphytes 6%–16%. Canopy epiphytes (occurring > 90% in tree zones Z3–5) were mainly represented by orchids and ferns, many with special adaptations to drought stress such as pseudobulbs, succulence, and poikilohydry. Trunk epiphytes ( > 90% in understory and tree zones Z1–2) reached highest relative species numbers among piperoids and ferns. Most hemiepiphytes were also trunk epiphytes, due to their characteristic growth pattern, and included mainly aroids. The vertical distribution of epiphytes within a tree is determined by several microenvironmental gradients, with light intensity, wind speed, and air temperature increasing and air humidity decreasing from the ground level to the canopy.