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1.
Over four decades ago, Pierre Dansereau, the noted North American ecologist, proposed six features of New Zealand vegetation as being problematic or unusual in a global context. We examine his propositions in the light of current ecological knowledge to determine whether or not these can still be considered unusual characteristics of New Zealand vegetation. (1) ‘Climatic change is still progressing’ resulting in disequilibrium between species' distributions and the present climate. New data and methods of analysis now available have removed the impression that Dansereau gained of imprecise zonation, unclear vegetation/climate relations and missing vegetation types. Communities cited as having regeneration failure can now be seen as even‐aged stands that developed after major disturbance, although there are other, also non‐climatic, explanations. However, the cause of the Westland ‘Nothofagus gap’ has become more, rather than less, controversial. (2) ‘Continuity of community composition defies classification’ and ‘Very few New Zealand associations have faithful species' are correct observations, but perhaps equally true of vegetation elsewhere. Dansereau's assertion of low species richness in New Zealand is not supported by the comparative data available. (3) ‘Lack of intolerant [i.e. mid‐seral] trees …’ is not evident with newer information. The order of species in succession, seen as unclear by Dansereau, has been determined by a range of approaches, largely confirming each other. (4) ‘Discrepancies of form and function …’ in divaricate shrubs and widespread heteroblasty are still controversial, with many more explanations. Several abiotic explanations have failed to stand up to investigation. Explanations in terms of herbivory have been well supported, although the extinction of the large avian herbivores makes certainty impossible. (5) ‘Incidence of hybridization …’ remains problematic. We do not know whether the incidence is unusually high, as Dansereau alleged, but the limited comparative data available suggest not. (6) The ‘overwhelming … competing power of exotics' is strongly context dependent. They are prominent in many non‐forest habitats. It seems that they are drivers of the vegetation change in some habitats, yet passengers after disturbance in others. Invasions can be slow, and may still be very incomplete in some ecosystem types. Whether exotics will eventually take over in most communities, or whether the native species will ‘laugh them to scorn’ as Cockayne suggested, only time will tell. In conclusion, some aspects of New Zealand's vegetation seem less unusual with increased knowledge, but others remain ‘problems’.  相似文献   

2.
This article examines the significance of pockets for controlling money in Highland Papua New Guinea. Contextualizing elaborate ‘systems’ for compartmentalizing monies in separate pockets, I draw upon the connection Highlanders make between transaction and skin. Pockets, I argue, offer opportunities to hide one's wealth reserves while gifting, keeping intentions opaque and leaving interlocutors guessing at the meaning of donors' speech, and forcing recipients to perceive their gift as ample. The article suggests that expectations are deliberately conventionalized in order to be exceeded, drawing parallels with Roy Wagner's notion of obviation. After characterizing Gorokan pockets and their gifting ‘logic’, I analyse how pocket‐users are themselves conventionalized as forthright or selfish in local discourse, based upon the pockets they display and where their clothes come from. Giving people clothing that includes pockets is therefore a way to regain control over their capacity to reveal wealth from their pockets.  相似文献   

3.
To improve the poor water solubility and dissolution rate of the oral hypoglycemic drug glibenclamide, it was molecularly dispersed in Neusilin® UFL2, an amorphous synthetic form of magnesium aluminometasilicate, at different proportions; the physicochemical and biopharmaceutical properties, as well as the stability of the four different batches recovered were characterised, and it was determined that complete dispersion of glibenclamide in the amorphous polymer was obtained at the drug to Neusilin ratio of 1 to 2.5. Completely amorphous dispersion was proven by Thermal Analysis and X-Ray Powder Diffractometry. Very small particles were obtained, ranging from approximately 200 to 400 nm. The amorphous batches were physically and chemically stable for the entire duration of experiments. The physicochemical properties of the four batches were compared to those of the starting materials and physical mixtures of Neusilin® UFL2 and glibenclamide, the latter showing the typical behaviour of simple mixes, i.e., the additivity of properties of single components. The dissolution studies of the four solid dispersions revealed a very high dissolution rate of the completely amorphous batches (Batches 3 and 4), behaviour that was ascribed to their high Intrinsic dissolution rate due to the amorphous characteristics of the solid dispersions, to their very small particle size, and to the presence of polysorbate 80 that improved solid wettability. The technique under investigation thus proved effective for recovering stable amorphous dispersions of very small particle sizes.  相似文献   

4.
A new nucleoside antibiotic, mildiomycin D, was isolated from the culture broth of Streptoverticillium rimofaciens B-98891 as a minor component. The molecular formula of the antibiotic purified by silica gel and ion exchange resin column chromatographies was determined to be C19H30N8O8 ? (2H2O) from its physicochemical data. The ultraviolet and infrared spectra were very similar to those of mildiomycin, a major component. On the basis of 1H and 13C-NMR spectra and acidic hydrolysates of the compound, the chemical structure of the antibiotic was determined as a deoxy compound at the C8′ position in mildiomycin. Mildiomycin D showed weak activities against Gram-positive and negative bacteria, phytopathogenic fungi and some yeasts, and its activity against Rhodotorula rubura was about 40% that of mildiomycin.  相似文献   

5.
Rabu C  High S 《Current biology : CB》2007,17(12):R472-R474
The integration of tail-anchored membrane proteins at the endoplasmic reticulum occurs via a specialised ATP-dependent pathway, but the cytosolic factors involved have proven elusive. A novel ATPase that mediates this process has now been identified.  相似文献   

6.
Waters JM  Roy MS 《Molecular ecology》2004,13(9):2797-2806
New Zealand's (NZ) geographical isolation, extensive coastline and well-characterized oceanography offer a valuable system for marine biogeographical research. Here we use mtDNA control region sequences in the abundant endemic sea-star Patiriella regularis to test the following literature-based predictions: that coastal upwelling disrupts north-south gene flow and promotes population differentiation (hypothesis 1); and that an invasive Tasmanian population of the species was introduced anthropogenically from southern New Zealand (hypothesis 2). We sequenced 114 samples from 22 geographical locations, including nine sites from North Island, nine from South Island, one from Stewart Island and three from Tasmania. Our analysis of these sequences revealed an abundance of shallow phylogenetic lineages within P. regularis (68 haplotypes, mean divergence 0.9%). We detected significant genetic heterogeneity between pooled samples from northern vs. southern New Zealand (FST = 0.072; P = 0.0002), consistent with the hypothesis that upwelling disrupts gene flow between these regions (hypothesis 1). However, we are currently unable to rule out the alternative hypothesis that Cook Strait represents a barrier to dispersal (North Island vs. South Island; FST = 0.031; P = 0.0467). The detection of significant spatial structure in NZ samples is consistent with restricted gene flow, and the strong structure evident in northern NZ may be facilitated by distinct ocean current systems. Four shared haplotypes and nonsignificant differentiation (FST = 0.025; P = 0.2525) between southern New Zealand and Tasmanian samples is consistent with an anthropogenic origin for the latter population (hypothesis 2).  相似文献   

7.
The three-step synthesis of new mixed P/N/N′/O-donor ligands C6H3(OH){2-NHC(O)CH2NCHC6H4PPh2}(4-CH3) 3a·HH and C6H4(OH){3-NHC(O)CH2NCHC6H4PPh2} 3b·HH, by Schiff base condensation of the 1° amines C6H3(OH){2-NHC(O)CH2NH2}(4-CH3) 2a or C6H4(OH){3-NHC(O)CH2NH2} 2b with C6H4(CHO)(2-PPh2) in refluxing EtOH, is described. Reaction of 1 equiv. of 3a·HH or 3b·HH with MCl2(cod) (M = Pt, Pd; cod = cycloocta-1,5-diene) affords the κ2-PN-chelate complexes MCl2(3a·HH) (M = Pd 4a; M = Pt 4b) and MCl2(3b·HH) (M = Pt 4c). The dichlorometal(II) complexes 4d and 4e, bearing instead a pendant 4-phenolic group, were similarly prepared (in >90% yield). Chloro-bridge cleavage of [Pd(μ-Cl)(η3-C3H5)]2 with 3a·HH or 3b·HH gave the monocationic κ2-PN-chelate complexes [Pd(η3-C3H5)(3a·HH)]Cl 5a or [Pd(η3-C3H5)(3b·HH)]Cl 5b, respectively. Elimination of cod, and single CH3 protonation, from Pt(CH3)2(cod) upon reaction with 1 equiv. of 3a·HH or 3b·HH in C7H8 at room temperature afforded the neutral complexes C6H3(OH){2-NC(O)CH2NCHC6H4PPh2Pt(CH3)}(4-CH3) 6a and C6H4(OH){3-NC(O)CH2NCHC6H4PPh2Pt(CH3)} 6b, respectively bearing a monoanionic (3a·H or 3b·H) κ3-PNN′-tridentate ligand. Amide and phenol deprotonation were readily achieved, using KOtBu as base, to give high yields of the κ4-PNN′O-tetradentate complexes C6H3(O){2-NC(O)CH2NCHC6H4PPh2Pd}(4-CH3) 7a and C6H3(O){2-NC(O)CH2NCHC6H4PPh2Pt}(4-CH3) 7b bearing the dianionic ligand 3a2−. All new compounds have been characterised by multinuclear NMR, FTIR, mass spectroscopy and microanalysis. Single crystal X-ray studies have been performed on compounds 1b·1.5CH2Cl2, 3b·HH·0.5Et2O, 6b·CHCl3 and 7b·0.5Et2O.  相似文献   

8.
A new artificial gene encoding human ω-amidase (Nit2) adapted for highly efficient expression in E. coli has been established. A pQE-Nit2 plasmid construct controlled by the T5 promoter has been engineered for its expression. The nit2 gene within the pQE-Nit2 construct has optimized codon usage and an artificial 6His-tag sequence inserted directly after the ATG initiation codon. This tag provides the possibility of single-step purification of a product via metal chelate chromatography. The codon-usage optimization involves the inclusion of several codons of extremely rare occurrence in natural E. coli ORFs within a 30 a.a-long N-terminal region. Other codons included in the N-terminus have moderate occurrence in E. coli. The subsequent sequence of the artificial gene has been composed of the most frequently occurring codons in E. coli. The recombinant producer based on the pQE-Nit2 construct allowed purification of the enzyme with an activity of 6.2 ± 0.2 μmol/min/mg protein, which corresponds to or slightly exceeds the specific activity of rat liver Nit2. The omega-amidase preparation is necessary for the screening of potential inhibitors that can be used as candidate drugs to cure hyperammonemia disorders in liver pathologies and oncological diseases.  相似文献   

9.
As we begin 2005, plant biologists have great opportunities to unlock the secrets of plant life. The realization of the importance of biodiversity and global ecology has promoted increasing efforts in understanding individual, population, and community plant biology. At the same time, the advances in plant molecular biology, genetics,  相似文献   

10.
In this work we isolated a novel crotamine like protein from the Crotalus durissus cascavella venom by combination of molecular exclusion and analytical reverse phase HPLC. Its primary structure was:YKRCHKKGGHCFPKEKICLPPSSDLGKMDCRWKRK-CCKKGS GK. This protein showed a molecular mass of 4892.89 Da that was determined by Matrix Assisted Laser Desorption Ionization Time-of-flight (MALDI-TOF) mass spectrometry. The approximately pI value of this protein was determined in 9.9 by two-dimensional electrophoresis. This crotamine-like protein isolated here and that named as Cro 2 produced skeletal muscle spasm and spastic paralysis in mice similarly to other crotamines like proteins. Cro 2 did not modify the insulin secretion at low glucose concentration (2.8 and 5.6 mM), but at high glucose concentration (16.7 mM) we observed an insulin secretion increasing of 2.7–3.0-fold than to control. The Na+ channel antagonist tetrodoxin (6 mM) decreased glucose and Cro 2-induced insulin secretion. These results suggested that Na+ channel are involved in the insulin secretion. In this article, we also purified some peptide fragment from the treatment of reduced and carboxymethylated Cro 2 (RC-Cro 2) with cyanogen bromide and protease V8 from Staphylococcus aureus. The isolated pancreatic -cells were then treated with peptides only at high glucose concentration (16.7 mM), in this condition only two peptides induced insulin secretion. The amino acid sequence homology analysis of the whole crotamine as well as the biologically-active peptide allowed determining the consensus region of the biologically-active crotamine responsible for insulin secretion was KGGHCFPKE and DCRWKWKCCKKGSG.  相似文献   

11.
A method for repeated PCR-mediated promoter replacement in the yeast Saccharomyces cerevisiae is described. It was proposed to use the DNA fragment comprising the marker gene that enables both positive and negative selection (a selectable/counter-selectable marker) surrounded by direct repeats of the desired promoter as a promoter replacement cassette. This fragment is integrated upstream of the target gene because of PCR-added terminal sequences for homologous recombination with the target locus. Subsequent marker excision via homologous recombination between the copies of the two promoters leaves one copy of the desired promoter upstream of the target genes, without any heterologous scar sequence. To test this method, a set of plasmids bearing the S. cerevisiae URA3 gene surrounded by two copies of the ADH1 or PGK1 promoter was constructed. Using these cassettes, the native promoters of the GSH1 and GSH2 genes were replaced in the ura3Δ0 recipient strains. The proposed method is useful for research applications due to simple marker excision, and for construction of “self-cloning” industrial strains, because no heterologous DNA is retained in the genome of the resulting strain after marker excision.  相似文献   

12.
A response to Serendipitous discovery of Wolbachia genomes in multiple Drosophila species by SL Salzberg, JC Dunning Hotopp, AL Delcher, M Pop, DR Smith, MB Eisen and WC Nelson. Genome Biology 2005, 6:R23  相似文献   

13.
We have purified a new violet pigment derived from Shewanella violacea DSS12 to determine its chemical structure. The pigment colored blue in tetrahydrofuran (THF) or chloroform and showed a broad absorption spectrum from 500 to 700 nm. X-ray diffraction analysis of single crystals showed that the chemical structure of this pigment was 5,5′-didodecylamino-4,4′-dihydroxy-3,3′-diazodiphenoquinone-(2,2′), containing the same chromophore as an indigoidine known as microbial blue pigment. The violet color of this pigment was due to hypsochromic shift (blue shift) caused by the side-by-side orientation of this pigment molecule, revealed by X-ray structural analyses of a single crystal. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.  相似文献   

14.
《新西兰生态学杂志》2011,32(1):108-112
Both tree and ground wētā have been proposed as potential seed dispersers of some New Zealand fruit. We examine evidence for coevolution of ground wētā and fleshy fruits as suggested by Burns (2006). We found that although ground wētā consume fruits from Gaultheria depressa and G. antipoda, they do not do so in a way that would suggest they had coevolved as dispersers with these or other New Zealand plants (Coprosma, Muehlenbeckia, Leucopogon). In our experiments, ground wētā ate fruits piecemeal and avoided most seeds even when these were very small (<1 mm) as in Gaultheria. We also found a positive preference for eating fruits of plants with seeds that were too big for ground wētā to ingest. Several lines of reasoning we explore lend no support to the proposal that ground wētā have coevolved with New Zealand plants resulting in the unusual characteristics displayed by many species (pale fruit presented within a divaricating canopy).  相似文献   

15.
16.
As a part of a comprehensive survey of macroparasites of commercially exploited fish species off the coast of Otago, New Zealand, the parasite fauna of the New Zealand sole Peltorhamphus novaezeelandiae Günther was recently studied. Steringotrema robertpoulini n. sp. is described from this host and compared with known species of Steringotrema Odhner, 1911. The new species is readily distinguished from all of its congeners, except for S. divergens (Rudolphi, 1809) Odhner, 1911, by having the follicular vitellarium divided in four zones rather than two, and can be differentiated from S. divergens mainly by the posterior extent of the intestinal caeca in the hindbody, as well as by host association and geographical distribution. DNA sequences of the 28S ribosomal gene were generated and phylogenetic analyses were undertaken using maximum likelihood and Bayesian inference to assess the phylogenetic position of the new species within the family Fellodistomidae Nicoll, 1909. Analyses included the available sequences for 14 species of the family distributed among eight genera, along with nine species of other members of the order Plagiorchiida La Rue, 1957 as outgroups. The resulting topology shows that the new species of Steringotrema is nested as the sister species of Steringophorus dorsolineatus (Reimer, 1985) Bray, 1995. However, low nodal support indicates that relationships among these species are not fully resolved and require further revision and denser taxon sampling for more detailed molecular work. More information is required to draw further conclusions about the taxonomic status of the genera Steringotrema and Steringophorus Odhner, 1905.  相似文献   

17.
Candomblé is an African-Brazilian religion that resulted from the adaptation of West African (especially Yoruba) beliefs in Brazil during and after the slave trade. This study seeks to understand the current evolution of Candomblé ethnobotanical knowledge as it travels from Brazil to New York City (NYC), therefore going through a second adaptation process. We identified which Brazilian plant species are still in use, which are being incorporated and/or replaced, and what factors are contributing to the ethnobotanical adaptation that is taking place in NYC. To accomplish this, we compiled an inventory of liturgical plants used by five highly skilled Candomblé practitioners living in NYC and then compared the vernacular and binomial Latin names of these plants to inventories previously published in Brazil by other authors. By doing this, we were able to distinguish patterns of knowledge continuity, assimilation, or substitution. Nearly two-thirds of the species identified in NYC’s inventory were cases of knowledge continuity, where most plants were used by at least four practitioners. Many of these frequently used species have survived the adaptation process from Africa to Brazil, and now from Brazil to NYC. Practitioners also assimilated (20%) and substituted (16%) some species. The assimilation process was mainly influenced by Santería, another Yoruba-derived religion widely practiced in NYC. Substitutions, however, were driven by two distinct forces. In one cohort (7%), species were morphologically and organoleptically similar to the original material, and replacements were mostly influenced by the easy accessibility of botanical materials. The other cohort (9%) was marked by a logical substitution process based on Yoruba rules of plant classification. Our results show that Candomblé practitioners in NYC are maintaining a notable level of cultural continuity, while cautiously assimilating new species and consciously or subconsciously replacing others. Although both accessibility of plant material and cultural forces play a role in the adaptation mechanism, the latter appears to be the most relevant to these highly skilled practitioners.  相似文献   

18.
Bergmann's rule describes the macroecological pattern of increasing body size in response to higher latitudes and elevations. This pattern is extensively documented in endothermic vertebrates, within and among species; however, studies involving ectotherms are less common and suggest no consistent pattern for amphibians and reptiles. Moreover, adaptive traits, such as epidermal features like scales, have not been widely examined in conjunction with Bergmann's rule, even though these traits affect physiological processes, such as thermoregulation, which are hypothesized as underlying mechanisms for the pattern. Here, we investigate how scale characters correlate with elevation among 122 New World pitviper species, representing 15 genera. We found a contra‐Bergmann's pattern, where body size is smaller at higher elevations. This pattern was mainly driven by the presence of small‐bodied clades at high elevations and large‐bodied clades at low elevations, emphasizing the importance of taxonomic scope in studying macroecological patterns. Within a subset of speciose clades, we found that only Crotalus demonstrated a significant negative relationship between body size and elevation, perhaps because of its wide elevational range. In addition, we found a positive correlation between scale counts and body size but no independent effect of elevation on scale numbers. Our study increases our knowledge of Bergmann's rule in reptiles by specifically examining characters of squamation and suggests a need to reexamine macroecological patterns for this group.  相似文献   

19.
Cirsium arvense (L.) Scop. (Californian, Canada, or creeping thistle) is an exotic perennial herb indigenous to Eurasia that successfully established in New Zealand (NZ) approximately 130 years ago. Presently, C. arvense is considered one of the worst invasive weeds in NZ arable and pastoral productions systems. A mechanism commonly invoked to explain the apparent increased vigour of introduced weeds is release from natural enemies. The enemy-release hypothesis (ERH) predicts that plants in an introduced range should experience reduced herbivory, particularly from specialists, and that release from this natural enemy pressure facilitates increased plant performance in the introduced range. In 2007, surveys were carried out in 13 populations in NZ (7 in the North Island and 6 in the South Island) and in 12 populations in central Europe to quantify and compare growth characteristics of C. arvense in its native versus introduced range. Altitude and mean annual precipitation for each population were used as covariates in an attempt to explain differences or similarities in plant traits among ranges. All plant traits varied significantly among populations within a range. Shoot dry weight was greater in the South Island compared to Europe, which is in line with the prediction of increased plant performance in the introduced range; however, this was explained by environmental conditions. Contrary to expectations, the North Island was not different from Europe for all plant traits measured, and after adjustment for covariates showed decreased shoot density and dry weight compared to the native range. Therefore, environmental factors appear to be more favourable for growth of C. arvense in both the North and South Islands. In accordance with the ERH, there was significantly greater endophagous herbivory in the capitula and stems of shoots in Europe compared to both NZ ranges. In NZ, capitulum attack from Rhinocyllus conicus was found only in the North Island, and no stem-mining attack was found anywhere in NZ. Thus, although C. arvense experiences significantly reduced natural enemy pressure in both the North and South Islands of NZ there is no evidence that it benefits from this enemy release.  相似文献   

20.
Random sampling is an important statistical assumption, but virtually impossible when sampling a wild species as we cannot know where all the individuals exist. While interpopulation or intrataxa sampling methods have been developed, there are currently few intrataxon sampling methods to objectively decide where to sample wild taxa. We suggest a new sampling method which computes appropriate sampling locations from coordinates, assuming geographical autocorrelation of phylogeny within a taxon (isolation‐by‐distance). The computed locations encompass the highest genetic diversity, providing a genetically representative sample. In addition, it can utilize presence/absence information during sampling to reoptimize sampling scheme. Comparing to the single existing method of the similar purpose, the merits of ours is unnecessity of environmental data resulting in easy application, and is theoretically deduced. We tested this method using published phylogeographical data. The test result was generally encouraging, but the method failed where species showed uniform genetic structure or recent distribution expansion which violate the assumption of geographical autocorrelation of phylogeny. Though simple, our method constructs a methodological and statistical foundation for sampling wild species, and is applicable to revising taxonomic study and conservation biology.  相似文献   

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