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1.
There is a pressing need for volunteer amateur naturalists to participate in data collection for biodiversity monitoring programmes in Europe. It is being addressed in some countries, but less so in others. This paper discusses the results from qualitative research using semi-structured interviews, focus groups and participant observation within nine Participatory Monitoring Network (PMN) organisations in six European countries. The paper examines the features that facilitate recruitment, retention and motivations of volunteers to participate in biodiversity monitoring, including the social and cultural milieus in which they operate. The paper concludes that volunteers place a high degree of significance on their social experience within PMNs. Successful creation and management of PMNs thus requires that similar levels of attention be paid to social aspects of the organisation as are paid to the generation and management of data.  相似文献   

2.
Summary Sixteen elements were determined in 156 specimens of 47 species of New Caledonian Flacourtiaceae including the genera Casearia, Homalium, Lasiochlamys and Xylosma. The data were used to study inter-elemental relationships, particularly those involving nutrient elements, magnesium and phytotoxic elements such as chromium, cobalt and nickel. Phytotoxic chromium was not accumulated to any marked degree by any taxon. Cobalt was inversely correlated with boron and sodium, and nickel with both nutrients as well as manganese. The data seemed to indicate the overriding controlling factor of reduced nutrient uptake caused by elements present in high concentrations in serpentinic substrates. It would seem that this reduced uptake is a major factor in the serpentine problem, at least as far as the Flacourtiaceae and the New Caledonian environment is concerned. By contrast, the toxic effects of elements such as nickel, cobalt and chromium seems less important.  相似文献   

3.
Binding of a transition metal ion to specific sites in concanavalin A induces the formation of specific Ca(2+) ion-binding sites. Sites for binding alpha-methyl d-glucopyranoside exist only when a transition metal ion and Ca(2+) ion are bound.  相似文献   

4.
The mammalian steroid hormone progesterone actuates a signalling pathway in the zygomycete Rhizopus nigricans which includes heterotrimeric G proteins. To investigate the possibility that the Gβ subunit of these proteins is involved in the signalling, a cDNA library from R. nigricans exposed to progesterone was prepared and a sequence coding for a Gβ subunit was searched for. Using degenerate primers, two sequences, RnGPB1 and RnGPB2, were identified that exhibited a high degree of identity with those for Gβ from other filamentous fungi, but not from yeast. The presence of more than one Gβ subunit is very rare among the fungi, and it has been to date reported only for Rhizopus oryzae. We have shown that progesterone increases the expression of RnGPB1, but has no influence on the expression of RnGPB2. Therefore, our studies imply the involvement of Gβ subunit 1 in the response of R. nigricans to progesterone. Moreover, the Gβ subunit is subjected to endogenous ADP-ribosylation in the presence of NAD, which could be important in some, as yet unknown, cell process. Article from a special issue on steroids and microorganisms.  相似文献   

5.
14ß-Cyanomethyl derivatives of estrone and estradiol have been synthesized starting from 3-benzoyloxyestra-1,3,5(10),14,16-pentaen-17-yl acetate. A comparative study of their cytotoxicity in breast carcinoma ZR-75-1, cervix uteri carcinoma M-HeLa, uterus leiomyosarcoma SK-UT-1B, breast adenocarcinoma MCF-7, ovary teratocarcinoma PA-1, acute myelogenous leukemia KG-1, and Burkitt’s lymphoma Raji cells has been performed.  相似文献   

6.
cDNA sequences obtained from polymerase chain reaction products of reverse-transcribed RNA from sheep thymus showed the presence of a large number of members of the TRDV1 gene family. Some are TRDV1 genes also found in peripheral blood lymphocytes, while four genes had not been described so far. The cDNA sequences also showed extensive junctional diversity and a preferential usage of the three TRDJ elements. We characterized the genomic organization of the sheep TRDJ locus and detected a correlation between the nonrandom usage of TRDJ elements during development and their chromosomal order.  相似文献   

7.
Two experiments are reported. In the first, six different strawberry genotypes were each grown in vitro on media containing five different concentrations of 6-benzylaminopurine (BAP) ranging from 0.5 M to 8.0 M. Responses of the genotypes to different BAP levels varied and the optimum levels for maximum proliferation were between 1 M and 8 M. In the second experiment the six genotypes were split into two groups of three and all crosses between the two groups were made. Seedlings from the nine progenies were then grown on media with the same five levels of BAP. Of the 12% of seedlings that did not proliferate, most were on media with the two lowest BAP levels (0.5 and 1.0 M). Seedlings from crosses involving the cv. Bogota proliferated least, while the three progenies with the breeding line ES652 as a parent had the highest mean proliferation rates. One cross, Bogota × Providence, had a particularly low mean proliferation rate. It was concluded that to optimize proliferation rate the medium must be tailored to the genotype. The best medium could not be reliably predicted from knowledge of the pedigree of a genotype.  相似文献   

8.
You XJ  Xu C  Lu JQ  Zhu XY  Gao L  Cui XR  Li Y  Gu H  Ni X 《PloS one》2011,6(8):e23788

Background

Human uterus undergoes distinct molecular and functional changes during pregnancy and parturition. Hydrogen sulfide (H2S) has recently been shown to play a key role in the control of smooth muscle tension. The role of endogenous H2S produced locally in the control of uterine contractility during labour is unknown.

Methodology/Principal Findings

Human myometrium biopsies were obtained from pregnant women undergoing cesarean section at term. Immunohistochemistry analysis showed that cystathionine-γ-lyase (CSE) and cystathionine-β-synthetase (CBS), the principle enzymes responsible for H2S generation, were mainly localized to smooth muscle cells of human pregnant myometrium. The mRNA and protein expression of CBS as well as H2S production rate were down-regulated in labouring tissues compared to nonlabouring tissues. Cumulative administration of L-cysteine (10−7–10−2 mol/L), a precursor of H2S, caused a dose-dependent decrease in the amplitude of spontaneous contractions in nonlabouring and labouring myometrium strips. L-cysteine at high concentration (10−3 mol/L) increased the frequency of spontaneous contractions and induced tonic contraction. These effects of L-cysteine were blocked by the inhibitors of CBS and CSE. Pre-treatment of myometrium strips with glibenclamide, an inhibitor of ATP-sensitive potassium (KATP) channels, abolished the inhibitory effect of L-cysteine on spontaneous contraction amplitude. The effects of L-cysteine on the amplitude of spontaneous contractions and baseline muscle tone were less potent in labouring tissues than that in nonlabouring strips.

Conclusion/Significance

H2S generated by CSE and CBS locally exerts dual effects on the contractility of pregnant myometrium. Expression of H2S synthetic enzymes is down-regulated during labour, suggesting that H2S is one of the factors involved in the transition of pregnant uterus from quiescence to contractile state after onset of parturition.  相似文献   

9.
Abstract. An entomological inventory was conducted between 1993 and 1996 to obtain information on the diversity of mosquitoes (Diptera: Culicidae) in the Jaú National Park, State of Amazonas, Brazil. A total of 10,159 adult (91%) and immature mosquito specimens, representing 130 taxa (species + morphospecies) in 16 genera, was collected. A species list for the family Culicidae is presented, including 30 new records for the State of Amazonas. The collecting localities were restricted to the alluvial subregion of the Open Tropical Forest found in the park. Most of the specimens (71%) were collected in forest habitats and the rest in areas of second growth and peridomicile. The majority of immature specimens (46%) were collected in bodies of water along the edges of rivers, flooded forests, lakes and streams. Among the various collection methods used, the Centre for Disease Control (CDC) and Shannon traps together were responsible for capturing 60% of the adults. More than 90% of the material collected belongs to the genera Culex (65%), Psorophora (19%), Wyeomyia (4%), and Anopheles (3%), which together represent 70% of the identified taxa. The genus Culex presented the largest number of species (45). The species Culex (Melanoconion) vaxus, Cx. (Mel.) pedroi, Psorophora amazonica, Cx. (Mel.) portesi and Cx. (Mel.) theobaldi together (< 4% of the recorded species) represent more than 63% of the material collected and identified to the species level. The most abundant species was Cx. (Mel.) vaxus, representing 17% of the material identified to species. The possible epidemiological and ecological implications of the species hereby recorded in the Jaú National Park are presented and discussed.  相似文献   

10.
Populations of the Chalcolithic Levant as defined by archaeological excavations has in many cases reinforced the traditional scheme that a number of “races” are present. This scheme is usually based not only on differential cultural traditions as identified by archeologists, but also on the available skeletal evidence as discussed by physical anthropologists. Recently this view has been challenged and it has been suggested that the metrical and anatomical range of variability as identified within Chalcolithic populations can be subsumed into a single population or “racial” range. This paper examines both the available biological and archaeological evidence from the Chalcolithic Levant and concludes that there is no strong archaeological or biological evidence to support a multiple “racial” origin for the Chalcolithic of the Levant.  相似文献   

11.
S. C. Fry 《Planta》1979,146(3):343-351
The insoluble cell wall polymers of cultured spinach cells contained esterified ferulic acid at 2–5 mg g-1 dry weight. Gibberellic acid (GA3, 10-11–10-6 M) promoted the expansion of these cells and simultaneoulsy suppressed peroxidase secretion, reduced the activity of cellular phenylanine ammonia-lyase and favoured the accumulation of wall-esterified ferulate and of extracellular soluble phenolic aglycones. When growth was prevented with 0·7 M sorbitol, GA3 still evoked the phenolic and peroxidase effects. It is suggested that peroxidase restricts growth by rigidifying the cell wall in two ways: (a) covalently by catalysing the conversion of feruloyl side-chains into diferuloyl cross-links and (b) non-covalently by catalysing the conversion of soluble phenolics into hydrophobic quinones (or polymers). GA3 is hypothesised to prevent this rigidification by inhibiting peroxidase secretion.Abbreviations A 28 absorbance at 280 nm - a 1cnt 1% absorptivity coefficient - 2,4-D 2,4-dichlorophenoxyacetic acid - EtOAc ethylacetate - GA3 gibberellic acid - mol wt molecular weight - PAL phenylalanine ammonia-lyase - PCV packed cell volume - sh shoulder or inflection - TLC thin-layer chromatography - UV ultra-violet - wavelength - IAA indoleacetic acid  相似文献   

12.
The ability of saprotrophic bacterium Pseudomonas fluorescens 32 gfp and of two enteropathogenic bacteria Salmonella enterica var. Typhimurium MAE 110 gfp and Escherichia coli O157:H7 gfp to pass through the gastrointestinal tract (GIT) of birds (domestic chicken) and the survival dynamics of these bacteria in chicken excrement and after transmission to water have been detected. Chickens were fed with combined feed inoculated with the mentioned bacteria at a density of 107 cells/g of dry combined feed. The quantity of the surviving bacteria was assessed in chicken excrement that was subsequently used for inoculation of nonsterile and sterile pond water. Dynamics of labeled bacteria in water were also taken into consideration. Good survival rate of all investigated bacteria was demonstrated in all studied substrates. This fact points to the capability of bacterial transfer, even pathogenic for human, in nature through a number of substrates and niches during the cycle and of infection of these niches and substrates, even used as food by humans.  相似文献   

13.
Cyanophycin, inclusions in cyanobacteria discovered by the Italian scientist Borzi in 1887, were characterized as a polyamide consisting of aspartic acid and arginine. Its synthesis in cyanobacteria was analyzed regarding growth conditions, responsible gene product, requirements, polymer structure and properties. Heterologous expression of diverse cyanophycin synthetases (CphA) in Escherichia coli enabled further enzyme characterization. Cyanophycin is a polyamide with variable composition and physiochemical properties dependent on host and cultivation conditions in contrast to the extracellular polyamides poly-γ-glutamic acid and poly-ε-l-lysine. Furthermore, recombinant prokaryotes and transgenic eukaryotes, including plants expressing different cphA genes, were characterized as suitable for production of insoluble cyanophycin regarding higher yields and modified composition for other requirements and applications. In addition, cyanophycin was characterized as a source for the synthesis of polyaspartic acid or N-containing bulk chemicals and dipeptides upon chemical treatment or degradation by cyanophycinases, respectively. Moreover, water-soluble cyanophycin derivatives with altered amino acid composition were isolated from transgenic plants, yeasts and recombinant bacteria. Thereby, the range of dipeptides could be extended by biological processes and by chemical modification, thus increasing the range of applications for cyanophycin and its dipeptides, including agriculture, food supplementations, medical and cosmetic purposes, synthesis of the polyacrylate substitute poly(aspartic acid) and other applications.  相似文献   

14.
The present study evaluated the reproducibility of measurements of the forearm thresholds for warm (WT) and cold (CT) sensation, and their dependence on gender. The Middlesex Thermal Testing System was used for this purpose. CT did not differ between the five consecutive trials, whereas WT fell significantly. A minimum of two trial tests are therefore recommended prior to the assessment of WT. Furthermore, CT and WT were induced by significantly smaller skin temperature changes (lower thresholds) in females as compared to males. Should this gender specific difference in thermosensitivity also be observed in other skin regions, then females would be more sensitive to thermal stimulation than males.  相似文献   

15.
16.
A check-list of the macroalgae which colonize the artificial structures “dykes” formed by limestone blocks, placed between the northern Adriatic Sea and the Venice Lagoon to protect the wide sea inlets of Lido and Malamocco, the stone breakwaters and the submerged reefs parallel and perpendicular to the sea coastline of the Lido island “Murazzi” is presented. Macroalgae have been sampled monthly during one-year period (February 2007–January 2008) both in the lagoon inlets and along the marine coast. Flora was represented by 213 taxa: 61 Chlorophyta, 114 Rhodophyta, 38 Ochrophyta (37 Phaeophyceae, 1 Xanthophyceae), with the richest and luxuriant vegetation in the lagoon inlet areas. The application of the Rhodophyta/Chlorophyta (R/C) index and the Expert-Macrophyte Quality Index (E-MaQI) highlighted the “High” ecological status (EQR > 0.9) of the lagoon inlet areas.As E-MaQI is not applicable in marine areas, an adaptation of CARLIT to the anthropic structures of the north-western coasts of the northern Adriatic Sea and its integration with the dominant taxa is proposed.The application of the revised index to the Lido dykes and breakwaters placed along the marine littorals shows “Moderate” conditions.  相似文献   

17.
Pseudomonas chlororaphis PCL1606 (PcPCL1606) displays plant-colonizing features and exhibits antagonistic traits against soil-borne phytopathogenic fungi. Biofilm formation could be relevant for the PcPCL1606 lifestyle, and in this study the role of some putative extracellular matrix components (EMC; Fap-like fibre, alginate and Psl-like polysaccharides) in the biofilm architecture and biocontrol activity of this bacterium were determined. EMC such as the Fap-like fibre and alginate polysaccharide play secondary roles in biofilm formation in PcPCL1606, because they are not fundamental to its biofilm architecture in flow cell chamber, but synergistically they have shown to favour bacterial competition during biofilm formation. Conversely, studies on Psl-like polysaccharide have revealed that it may contain mannose, and that it is strongly involved in the PcPCL1606 biofilm architecture and niche competition. Furthermore, the Fap-like fibre and Psl-like exopolysaccharide play roles in early surface attachment and contribute to biocontrol activity against the white root rot disease caused by Rosellinia necatrix in avocado plants. These results constitute the first report regarding the study of the extracellular matrix of the PcPCL1606 strain and highlight the importance of a putative Fap-like fibre and Psl-like exopolysaccharide produced by PcPCL1606 in the biofilm formation process and interactions with the host plant root.  相似文献   

18.
A cellulase and a laminaranase have been purified from a Streptomyces lytic enzyme complex. Lipase and protease were separated from glucanases. A combination of the purified glucanases produced protoplasts fromPythium sp. PRL 2142. Lipase was shown to act as an adjuvant in this process.National Research Council of Canada Postdoctorate Fellow 1965–67.  相似文献   

19.
The Aβ(16–22) sequence KLVFFAE spans the hydrophobic core of the Aβ peptide and plays an important role in its self-assembly. Apart from forming amyloid fibrils, Aβ(16–22) can self-associate into highly ordered nanotubes and ribbon-like structures depending on the composition of solvent used for dissolution. The Aβ(16–22) sequence which has FF at the 19th and 20th positions would be a good model to investigate peptide self-assembly in the context of aromatic interactions. In this study, self-assembly of Aβ(16–22) and its aromatic analogs obtained by replacement of F19, F20 or both by Y or W was examined after dissolution in fluorinated alcohols and their aqueous mixtures in solvent cluster forming conditions. The results indicate that the presence of aromatic residues Y and W and their position in the sequence plays an important role in self-assembly. We observe the formation of amyloid fibrils and other self-assembled structures such as spheres, rings and beads. Our results indicate that 20% HFIP is more favourable for amyloid fibril formation as compared to 20% TFE, when F is replaced with Y or W. The dissolution of peptides in DMSO followed by evaporation of solvent and dissolution in water appears to greatly influence peptide conformation, morphology and cross-β content of self-assembled structures. Our study shows that positioning of aromatic residues F, Y and W have an important role in directing self-assembly of the peptides.  相似文献   

20.
The basis for the differentiation of l-glycerol-3-phosphate dehydrogenase (-GPDH) into larval and adult isozymes in Drosophila melanogaster was investigated by the correlation of a lack of appearance of each isozyme during development within Drosophila bearing -GPDH null alleles and by the study of a putative conversion factor. Conversion studies indicate the presence of a heat-labile RNase-resistant conversion factor present in crude larval extracts with the ability to convert GPDH-1 to GPDH-2 and GPDH-3 but not vice versa. In addition, null mutations at the Gpdh locus obliterate all isozymatic species of -GPDH in all developmental stages. These observations suggest that all -GPDH isozymes are the product of a single structural gene and that the multiple forms of this enzyme arise during successive developmental stages through an epigenetic modification of the primary Gpdh + polypeptide. Finally, observations are reported which bear on the functional divergence of the -glycerophosphate cycle in the adult and larval stage of development.This investigation was supported in part by NIH Research Grant No. GM-15691 and Genetics Training Grant No. 2 TI GM-685 at the University of North Carolina and by NIH Research Grant No. GM-11546 at North Carolina State University.Paper No. 5054 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, North Carolina.  相似文献   

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