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1.
Croton churutensis is described as a new species ofCroton sectionCyclostigma endemic to lowland deciduous forests in coastal Ecuador. Its red latex is used locally in Guayas Province to treat wounds, stomach ulcers, and some skin conditions caused by fungal infections. The new species differs from its closest apparent relative,Croton hibiscifolius, in its arching-pendent inflorescences, short-pedicellate female flowers with quadrifid stigmas, more numerous stamens, laciniate stipules, and lower elevation habitat.  相似文献   

2.
The faunistic composition of pelagic ostracods of regions situated to the north and northwest of the d’Urville Sea (60°–65°S, 148°–136° and 136°–113°E) is largely similar to that of the area adjacent to the Somov Sea at the same latitudes. Alacia hettacra is the most abundant species here; Austrinoecia isocheira, Boroecia antipoda, and Obtusoecia antarctica are common species. The maximum abundance of pelagic ostracods is observed in the 100–200 m depth range; the largest contribution to it is contributed by A. hettacra. The number of species increases with increasing depth. The 64°–65°S region between 148° and 113° E is regarded as the northern boundary of the “Polar Antarctic zone.”  相似文献   

3.
At scales from microsites to entire ranges, species’ distributions reflect limited adaptation and/or limited dispersal. To what extent are specific distribution patterns and processes similar across scales? We investigated environmental effects—presumed because of adaptation—and independent spatial effects—presumed because of dispersal—on distribution at two scales (landscape patches of approximately 1,300 m2, sampled along transects, and 4-m2 cells, sampled in contiguous grids within populations) and on individual performance (water status, reproduction) in the California annual, Clarkia xantiana ssp. xantiana. Because water limitation helps set this species’ regional borders, we expected occupancy and performance at smaller scales to correlate with topographic and soil features affecting water relations. At the patch scale, environmental features associated with reduced water stress (i.e., steep slopes that face north; coarse, soft soils; igneous rather than metasedimentary parent rock) predicted occupancy. Spatial aggregation was not detected, but incomplete occupancy of apparently suitable patches indicated that dispersal limits occupancy. At the scale of small cells, relationships between environmental variables, occupancy, density, and performance varied among populations. Associations sometimes resembled those at the patch scale but sometimes opposed them. Spatial aggregation in cell occupancy and/or density occurred in all populations, implying limited dispersal, whereas spatial aggregation of water potential values in some populations might have arisen from spatially structured unmeasured environmental variables. Limited adaptation to drought and limited patch colonization appear to affect patch occupancy in C. xantiana ssp. xantiana, whereas smaller-scale patterns indicate consistent effects of limited dispersal and somewhat variable environmental effects.  相似文献   

4.
The species ofChamaesyce classified by Boissier as the “Pleiadeniae” are revised in light of presently available collections. Six species are accepted and new combinations are proposed forC. nana, C. setosa, C. tamanduana, andC. viscoides. Although these herbaceous perennials of cerrado vegetation of Brazil, northern Argentina, and adjacent countries are distinctive ecologically and geographically, cladistic analysis does not support their recognition as a monophyletic group.  相似文献   

5.
We studied assemblages of soft-walled, single-chambered foraminifera (monothalamids) at eight stations in the area of Zernov's Phyllophora Field (ZPF) on the NW continental shelf of the Black Sea. This work is based on samples collected during Cruise 70 of the RV Professor Vodyanitsky and provides the first analysis of the taxonomic composition of monothalamids from this region. These delicate, poorly known foraminifera were found at all stations in the studied area. They were represented by nine forms that are identified to species or genus level as well as 14 undescribed species, nine of which are found in the Black Sea for the first time. Four species, Psammophaga sp., Vellaria pellucida, Goodayia rostellata and Krymia fusiformis, were most abundant, with Psammophaga sp. being the dominant species overall. Previous studies have suggested a link between members of this genus and eutrophication. There are a number of taxonomic parallels between these ZPF assemblages and those from the Adriatic Sea, e.g. the occurrence of the genera Goodayia, Psammophaga and Vellaria, although it is possible that some other taxa are endemic to the Black Sea.  相似文献   

6.
Abstract

This article discusses some drawbacks of a universally applicable 200‐mile limit for seabed resources in terms of the artificial nature of this limit, the jeopardy to the proposed international regime to govern deep seabed resources, and the views of land‐locked and shelf‐locked countries. Given the uncertain political acceptability of a 200‐mile limit, a systems approach is suggested as a means of devising a compromise solution that would maximize the objectives of: respect of existing internationally agreed conventions; promotion of the rational development of deep seabed resources; provision of equitable distribution of seabed resources and provision of acceptable benefits to all major groups of countries. One possible solution would be to have the limit of coastal jurisdiction over seabed resources defined in terms of the continental margin coupled with a system for sharing the “take”; in the area between 12 miles and the limit of the margin. The share payable to the international seabed authority would increase progressively with the distance of exploitation from the coast but would be moderated by the relative income level of the coastal State.  相似文献   

7.
The DagA product of Streptomyces coelicolor is an agarase with a primary translation product (35 kDa) of 309 amino acids, including a 30-amino acid signal peptide. Although dagA expression in Streptomyces lividans under the control of its own set of promoters was previously reported, its enzymatic properties have never been elucidated. To develop an improved expression system for dagA, three types of strong promoters for the Streptomyces host were linked to dagA, and their efficiencies in DagA production were compared in S. lividans TK24. All of the transformants with dagA grew at improved rates and produced larger amounts of DagA in the modified R2YE medium containing 0.5% agar as the sole carbon source. Of the three transformants, the S. lividans TK24/pUWL201-DagA (ermE promoter) produced the highest agarase activity (A 540 = 4.24), and even the S. lividans TK24/pHSEV1-DagA (tipA promoter) and S. lividans TK24/pWHM3-DagA (sprT promoter) produced higher agarase activity (A 540 = 0.24 and 0.12, respectively) than the control (A 540 = 0.01) in the modified R2YE medium. The mature form of DagA protein (32 kDa) was successfully purified by one-step affinity column chromatography by using agarose beads with excellent yield. The purified DagA was found to exhibit maximal agarase activity at 40°C and pH 7.0. The K m, V max, and K cat values for agarose were 2.18 mg/ml (approximately 1.82 × 10−5 M), 39.06 U/mg of protein, and 9.5 × 103/s, respectively. Thin layer chromatography (TLC) analysis, matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry, and Fourier transform nuclear magnetic resonance (FT-NMR) spectrometry of the hydrolyzed products of agarose by DagA revealed that DagA is an endo-type β-agarase that degrades agarose into neoagarotetraose and neoagarohexaose.  相似文献   

8.
Lycianthes moziniana is an agrestic (weedy) perennial encouraged by traditional farmers for its edible, sweet-tasting fruits. This species is endemic to the Mexican highland plateau and Oaxaca where the ethnotaxonomic and ethnohistoric data reflect a long-standing relationship with human populations. Today, the fruits of this plant are used for domestic consumption, small-scale commercialization, and ceremonial purposes. To ensure the production of fruits, traditional farmers afford the plants a special management which has evolutionary repercussions. Recently, modern agricultural practices have placed this species in danger of extinction. Preliminary chemical analyses and yield data suggest thatL. moziniana is particularly well-suited for development as a “new” crop for Mexico.  相似文献   

9.
The sawfly Cibdela janthina (Hymenoptera: Argidae) native to Sumatra was introduced on La Réunion (France, Indian Ocean) in 2007 to control the giant bramble Rubus alceifolius (Rosaceae), one of the most invasive plants on this island. We determined the influence of temperature on the development duration and survival of C. janthina preimaginal stages in controlled conditions in order to parameterize a survival model and to relate the predicted survival with observed patterns of defoliation of the host plant at different altitudes. We adjusted the Régnière model to survival data, combined with the Lactin-2 model on development rate of the three preimaginal stages of C. janthina. This model adequately predicts the observed defoliation and the altitudinal limit of the biological control agent. Our results also show that studies on temperature-related constraints on the biology of an agent introduced for weed control should be emphasized both in the pre-release and the post-release phases of a biological control program to evaluate the potential success of the control programme.  相似文献   

10.
The “Maca” (Lepidium meyenii), a little known food plant of peru   总被引:1,自引:0,他引:1  
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11.
The eggshell of Reeve's pheasant (Syrmaticus reevesii) collected from the Dongzhai National Nature Reserve in Henan Province,China was studied.By using scanning electron microscopy and inductively coupled plasma (ICP) spectrometry,the ultrastructure and elemental composition of the eggshell was determined.The study showed that the average thickness of the surface layer of crystals,the palisade and cone layer,and the eggshell membrane were 20.8,220.8 and 62.5 larn,respectively,accounting for 6.8%,72.6% and 20.6% of the total thickness of the eggshell.There were many vesicular holes in the palisade layer with an average diameter of 0.32±0.08 μm(n = 30).The function of these holes might be significant to air exchange.The shape of the eggshell pore on the surface layer of crystals is round or elliptical.The fracture surface of the pore is funnel-shaped.Some granules filled the upper part of the eggshell pores.The content of 21 elements in the eggshell of wild and captive Reeve's pheasants was compared and presented.It indicated that among the elements that made up the eggshell of the wild pheasant,the content of Ca,Mg,P and S was much higher,ω> 1 mg/g,with ω (Ca) being higher than 40% of the eggshell.The contents of Na,Si,Sr,K and A1 were ω = 0.1-1 mg/g,while Fe,Zn,Pb,Mn,Cu,V and Ti had lower concentrations (ω = 1-100 μg/g).The ω ofNi,Cr,Co,Se,Cd were lower than 1 μg/g.The elemental composition in the eggshell of the captive Reeve's pheasant kept in the Dongzhai National Natural Reserve was significantly different from that of the wild species,with a difference of over 20% on S,Cu,Fe,AI,Mn,Si,Sr,Se and Cr.The lower intake of Fe,Mn,Si and Sr on the one hand and the higher intake of S,Cu,Al and Cr on the other hand might be responsible for the low fertility of captive Reeve's pheasants in the Dongzhai National Nature Reserve.In order to ensure that the pheasants are receiving the proper amount of nutrition and to improve their breeding success,the amount of certain elements in the food should be adjusted.  相似文献   

12.
Plants with extrafloral nectaries attract a variety of ant species, in associations commonly considered mutualistic. However, the results of such interactions can be context dependent. Turnera subulata is a shrub widely distributed among disturbed areas which has extrafloral nectaries at the base of leaves. Here, we evaluated whether the ants associated with T. subulata (i) vary in space and/or time; (ii) respond to simulated herbivory, and (iii) reduce herbivory rates. For this, we quantified the abundance and species richness of ants associated with T. subulata throughout the day in six different sites and the defensive capability of these ants under simulated herbivory in the leaves and stems of T. subulata plants (N = 60). We also checked the proportion of the lost leaf area and quantified leaf damage by chewing herbivores in the host plant. We found that a total of 21 ant species associated with the host plant. Species composition showed significant variation across the sampled sites and throughout the day. Visitation rates and predation by ants were higher in plant stems than in leaves. In general, herbivory rates were not correlated with ant association or activity, with the exception of the proportion of leaf area consumed; there was a significant lower herbivory rate on plants in which ants defended the leaves. Our results suggest that the benefits of association may depend on the ecological context. This context dependence may mask the correlation between the defense of ants and herbivory rates.  相似文献   

13.
Novel dichlorobis(β-diketonato)titanium(IV) Ti(C6H5COCHCOR)2Cl2 and (2,2′-biphenyldiolato)bis(β-diketonato)titanium(IV) Ti(C6H5COCHCOR)2biphen complexes with R = CH3, C6H5 and CF3, are synthesized and characterized by X-ray crystallography and further physical methods. There is a good agreement between DFT calculated and experimental structural data. A configurational analysis gives a calculated isomer distribution that is in agreement with the experimental data derived from low temperature 1H NMR spectroscopy. The Ti(C6H5COCHCOR)2biphen complexes exhibit high hydrolytic stability.  相似文献   

14.
Ichthyological Research - The geographical distribution and intraspecific genetic diversity of an endangered freshwater goby, Gymnogobius sp. “Chokai-endemic species”, was surveyed...  相似文献   

15.
16.
A 94 kD pigment-polypeptide, which is presumed to be involved in anchoring the phycobilisomes to the thylakoids, was isolated from Nostoc phycobilisomes by gel filtration in 63 mM formic acid. The isolation condition did not require detergents or denaturating reagents, as in previous procedures, and enzymatic degradation was not observed at the low pH of 2.5. The anchor polypeptide thus obtained had absorption (Abs) and fluorescence maxima (Em) at 658 and 673 nm, respectively, in 63 mM formic acid at room temperature. The maxima shifted to longer wavelengths in 100 mM potassium phosphate (pH 6.8), Abs 665 and Em 683 nm at room temperature, and Abs 665 and Em 684 nm at liquid nitrogen temperature. The fluorescence maxima at both temperatures correspond to the longest wavelength component resolved in phycobilisomes from second derivative spectra. A minor blue polypeptide was also found by this isolation method. The molecular weight of this polypeptide was ca. 18,000 and is probably similar to a polypeptide which has been found in the phycobilisome core of other cyanobacteria.Abbreviations used -APB -subunit of allophycocyanin B - APC allophycocyanin - kD kilodalton - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis - PBS phycobilisome - PE phycoerythrin - PC phycocyanin - PS pigment system  相似文献   

17.
The leaf-beetle Leptomona russica (Gmelin, 1790) known from the Caucasus, Kazakhstan, and Middle Asia was found in Orenburg Province for the first time. It is the first record of this species from Europe and the first record of the genus Leptomona from European Russia. The diagnostic characters of the two Russian Leptomona species are included.  相似文献   

18.
19.

Purpose

A scalable life cycle inventory (LCI) model of a permanent magnet electrical machine, containing both design and production data, has been established. The purpose is to contribute with new and easy-to-use data for LCA of electric vehicles by providing a scalable mass estimation and manufacturing inventory for a typical electrical automotive traction machine. The aim of this article (part I of two publications) is to present the machine design, the model structure, and an evaluation of the models’ mass estimations.

Methods

Data for design and production of electrical machines has been compiled from books, scientific papers, benchmarking literature, expert interviews, various specifications, factory records, and a factory site visit. For the design part, one small and one large reference machine were constructed in a software tool, which linked the machines’ maximum ability to deliver torque to the mass of its electromagnetically active parts. Additional data for remaining parts was then gathered separately to make the design complete. The two datasets were combined into one model, which calculates the mass of all motor subparts from an input of maximum power and torque. The range of the model is 20–200 kW and 48–477 Nm. The validity of the model was evaluated through comparison with seven permanent magnet electrical traction machines from established brands.

Results and discussion

The LCI model was successfully implemented to calculate the mass content of 20 different materials in the motor. The models’ mass estimations deviate up to 21% from the examples of real motors, which still falls within expectations for a good result, considering a noticeable variability in design, even for the same machine type and similar requirements. The model results form a rough and reasonable median in comparison to the pattern created by all data points. Also, the reference motors were assessed for performance, showing that the electromagnetic efficiency reaches 96–97%.

Conclusions

The LCI model relies on thorough design data collection and fundamental electromagnetic theory. The selected design has a high efficiency, and the motor is suitable for electric propulsion of vehicles. Furthermore, the LCI model generates representative mass estimations when compared with recently published data for electrical traction machines. Hence, for permanent magnet-type machines, the LCI model may be used as a generic component estimation for LCA of electric vehicles, when specific data is lacking.
  相似文献   

20.
The eggshell of Reeve’s pheasant (Syrmaticus reevesii) collected from the Dongzhai National Nature Reserve in Henan Province, China was studied. By using scanning electron microscopy and inductively coupled plasma (ICP) spectrometry, the ultrastructure and elemental composition of the eggshell was determined. The study showed that the average thickness of the surface layer of crystals, the palisade and cone layer, and the eggshell membrane were 20.8, 220.8 and 62.5 μm, respectively, accounting for 6.8%, 72.6% and 20.6% of the total thickness of the eggshell. There were many vesicular holes in the palisade layer with an average diameter of 0.32 ± 0.08 μm (n = 30). The function of these holes might be significant to air exchange. The shape of the eggshell pore on the surface layer of crystals is round or elliptical. The fracture surface of the pore is funnel-shaped. Some granules filled the upper part of the eggshell pores. The content of 21 elements in the eggshell of wild and captive Reeve’s pheasants was compared and presented. It indicated that among the elements that made up the eggshell of the wild pheasant, the content of Ca, Mg, P and S was much higher, ω > 1 mg/g, with ω (Ca) being higher than 40% of the eggshell. The contents of Na, Si, Sr, K and Al were ω = 0.1–1 mg/g, while Fe, Zn, Pb, Mn, Cu, V and Ti had lower concentrations (ω = 1–100 μg/g). The ω of Ni, Cr, Co, Se, Cd were lower than 1 μg/g. The elemental composition in the eggshell of the captive Reeve’s pheasant kept in the Dongzhai National Natural Reserve was significantly different from that of the wild species, with a difference of over 20% on S, Cu, Fe, Al, Mn, Si, Sr, Se and Cr. The lower intake of Fe, Mn, Si and Sr on the one hand and the higher intake of S, Cu, Al and Cr on the other hand might be responsible for the low fertility of captive Reeve’s pheasants in the Dongzhai National Nature Reserve. In order to ensure that the pheasants are receiving the proper amount of nutrition and to improve their breeding success, the amount of certain elements in the food should be adjusted. Translated from Journal of Beijing Normal University (Natural Science), 2006, 42(1): 78–82 [译自: 北京师范大学学报 (自然科学版)]  相似文献   

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