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21.
Claudia Raedig Carsten F. Dormann Anke Hildebrandt Sven Lautenbach 《Biodiversity and Conservation》2010,19(6):1523-1546
Monographic data rely on specimens deposited in herbaria and museums, which have been thoroughly revised by experts. However,
monographic data have been rarely used to map species richness at large scale, mainly because of the difficulties caused by
spatially heterogeneous sampling effort. In this paper we estimate patterns of species richness and narrow endemism, based
on monographic data of 4,055 Neotropical angiosperm species. We propose a geometric interpolation method to derive species
ranges at a 1° grid resolution. To this we apply an inverse distance-weighted summation scheme to derive maps of species richness
and endemism. In the latter we also adjust for heterogeneous sampling effort. Finally, we test the robustness of the interpolated
species ranges and derived species richness by applying the same method but using a leave-one-out-cross-validation (LOOCV).
The derived map shows four distinct regions of elevated species richness: (1) Central America, (2) the Northern Andes, (3)
Amazonia and (4) the Brazilian Atlantic coast (‘Mata Atlantica’). The region with the highest estimated species richness is
Amazonia, with Central America following closely behind. Centers of narrow endemism are located over the entire Neotropics,
several of them coinciding with regions of elevated species richness. Sampling effort has a minor influence on the interpolation
of overall species richness, but it substantially influences the estimation of regions of narrow endemism. Thus, in order
to improve maps of narrow endemism and resulting conservation efforts, more collection and identification activity is required. 相似文献
22.
P C de Visser N M A J Kriek P A V van Hooft A Van Schepdael D V Filippov G A van der Marel H S Overkleeft J H van Boom D Noort 《The journal of peptide research》2003,61(6):298-306
As part of a program towards the development of novel antibiotics, a convenient method for solid-phase synthesis of the cyclic cationic peptide polymyxin B1 and analogues thereof is described. The methodology, based on cleavage-by-cyclization using Kenner's safety-catch linker, yields crude products with purities ranging from 37-67%. Antibacterial assays revealed that analogues 23-26, in which the (S)-6-methyloctanoic acid moiety is replaced with shorter acyl chains, exhibit distinct antimicrobial activity. The results suggest that the length of the acyl chain is rather critical for antimicrobial activity. On the other hand, substitution of the hydrophobic ring-segment D-Phe-6/Leu-7 in polymyxin B1 with dipeptide mimics (i.e. analogues 27-33) resulted in almost complete loss of antimicrobial activity. 相似文献
23.
K I Savitskaia A A Vorob'ev G G Sinitsina 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1986,(12):24-31
The results of the inoculation of material taken from the anterior section of the nasal cavity and from the pharyngeal mucosa of 50 healthy young children and 298 acute pneumonia patients were analyzed. 23 microbial species were isolated. In the samples taken from the anterior section of the nasal cavity, monocultures were detected in 86 samples and 54 variants of associations including 2-4 species, in 139 samples. In the samples taken from the pharynx, monocultures were detected in 59 samples and 180 variants of associations including 2-6 species, in 282 samples. Differences in the contamination of the nasal cavity and the pharynx in healthy children and in pneumonia patients were revealed. These differences were manifested in the structure of the microflora (monocultures, associations, their composition), the assortment of microbial species and their concentration. In young children with pneumonia the microflora of the upper respiratory tract was found to reflect the severity of acute pneumonia and the intensity of the pathological process in the lungs (uncomplicated, pyodestructive pneumonia, pyodestructive pneumonia with fatal termination, acute purulent pleurisy). 相似文献
24.
Experiments on conscious rabbits were made to elaborate motor conditioned reflexes through pairing stimuli with electrocutaneous reinforcement applied every 30 s. Neuronal activity in the sensorimotor cortex and putamen was recorded during formation and reproduction of the conditioned reflexes before and after haloperidol injection (0.2 mg/kg i. v.). In the putamen, haloperidol increased the number of neurons exhibiting trace conditioned activity and made the intensity and duration of these processes rise. The changes seen in the sensorimotor cortex were opposite in nature. Inhibition of trace conditioned activity in the sensorimotor cortex depended mainly on the decreased amplitude of the reaction conditioned component. The role of the dopaminergic system in the interaction of the neostriatum and sensorimotor cortex and in formation and reproduction of trace conditioned activity of both the structures is discussed. 相似文献
25.
26.
M S Bortnik A V Skurat I R Eshba T V Bulargina E S Severin 《Biokhimii?a (Moscow, Russia)》1985,50(4):589-594
Changes in the properties of adenylate cyclase from the lungs of tuberculotic guinea pigs were revealed. The number of beta-adrenergic receptors in the lungs was found to be reduced by 30% at the second and by 70% at the third stage of the disease. The degree and the value of Ka for adenylate cyclase activation by isoproterenol remained thereby unchanged. The basal activity of adenylate cyclase was increased by 20% against the control level at the second stage and decreased by 20% at the third stage of the disease. At these periods, the stimulating effects of guanylyl imidodiphosphate, NaF and forskolin on lung adenylate cyclase were diminished. The experimental results point to the significant role of the enzymes of cAMP metabolism and reflect the course of the tuberculosis process in experimental animals. 相似文献
27.
V V Sviridov E V Kozhevnikova 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1985,(9):67-70
The immunization of mice with the protein fraction of B. pertussis strain 305 has made it possible to obtain hybridomas producing monoclonal antibodies to B. pertussis antigens. Ascitic fluids containing monoclonal antibodies react in the ELISA in high titers and actively agglutinate B. pertussis strains 305 and 475. 相似文献
28.
Immunological characterization of the cytochrome o terminal oxidase from Escherichia coli 总被引:13,自引:0,他引:13
The cytochrome o terminal oxidase from Escherichia coli was immunochemically purified and monospecific antiserum toward cytochrome o was obtained. This antiserum is able to precipitate 100% of the ubiquinol-1 oxidase activity in Triton X-100 extracts of membranes from an E. coli strain in which cytochrome o is the only terminal oxidase. Cytochrome o was analyzed and quantitated using crossed immunoelectrophoresis, rocket immunoelectrophoresis, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows that cytochrome o is composed of four subunits of approximate equimolar stoichiometry with molecular weights of 51,000, 28,500, 18,000, and 12,700. The low temperature (77 K) reduced - oxidized spectrum of the immunoprecipitate shows two peaks at 555 and 562 nm, indicating b-type cytochromes. With the anti-cytochrome o and antiserum toward the cytochrome d terminal oxidase complex which was previously obtained, it is possible to immunochemically assay for all the cytochromes in the cytoplasmic membrane of aerobically grown E. coli. Preliminary results indicate that the biosynthesis of cytochrome o is repressed when cytochrome d is induced by lowering the dissolved oxygen concentration during cell growth. 相似文献
29.
1. Tissue capillarity in muscle was modelled as square-ordered arrays with capillary-to-fiber ratios (C/F) from 0.5 to 'infinity'. 2. C/F up to two had marked effects on diffusion distances, but C/F above had only slight effects on average distances and almost no effect on maximal distances. 3. Capillary growth during normal maturation results in C/F around two. Thus, capillary growth in adult muscle may not be an adaptive mechanism for reducing diffusion distances. 相似文献
30.
A hitherto unknown defect in the immune responsiveness of B lymphocytes from SJL mice has enabled us to distinguish two qualitatively distinct classes of signal delivered to B cells by C8-substituted guanine ribonucleosides. This defect renders B cells from SJL mice unresponsive to the inductive (early acting) signal of 8-mercaptoguanosine (8MGuo) that culminates in mitogenesis and nonspecific secretion of immunoglobulin. Unresponsiveness is not attributable to a shift in either the dose-response or kinetic profiles, nor can the presence of suppressor cells be demonstrated. In striking contrast, however, SJL B cells exhibit normal responsiveness to the differentiative (T cell-like, or late acting) signal provided by the substituted nucleoside. This signal enables SJL B cells, depleted of T cells, to respond to T cell-dependent antigens, and synergizes with T cell-derived lymphokines. These data suggest 1) that nonspecific secretion of immunoglobulin is dependent on both inductive and differentiative signals, 2) that antigen alone can supply an effective inductive signal for antigen-specific responses, and 3) that the SJL mouse will provide a useful model for selective study of inductive vs differentiative events. 相似文献