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51.
MARK A. CARINE LAVINIA ROBBA ROBERT LITTLE STEVE RUSSELL ARNOLDO SANTOS GUERRA 《Botanical journal of the Linnean Society. Linnean Society of London》2007,154(2):187-204
Morphological data and molecular data from the chloroplast trn H- psb A region and nuclear ribosomal ITS region are used to test the hypothesis that the problematic Canary Island endemic Convolvulus floridus var. virgatus is a hybrid between the endemic species C. floridus and C. scoparius . Analysis of mean leaf length and width of 58 individuals indicates that accessions referable to C. floridus var. virgatus are intermediate between the parental taxa in leaf dimensions. Direct sequencing of the ITS region of C. scoparius and C. floridus revealed two species-specific ribotypes distinguished by 10 base differences. Examination of ITS chromatograms for putative hybrids revealed polymorphisms at those sites that are diagnostic between species in all except one putative hybrid. Morphological intermediacy and ITS additivity therefore support the hybrid status of C. floridus var. virgatus . An analysis of intraindividual ITS variation confirmed the co-occurrence of both parental ribotypes in putative hybrids and demonstrated that some hybrid individuals contained chimaeric ITS types. It is proposed that chimaeric ITS types are the result of recombination following backcrossing. Sequencing of the trn H- psb A region revealed four haplotypes. Three were, for the most part, confined to C. floridus and putative hybrids although one C. scoparius accession was also found to share this haplotype. The remaining haploype was only found in C. scoparius and putative hybrid accessions. Patterns of haplotype distribution between parental and hybrid accessions suggest multiple, bidirectional hybridization events between C. floridus and C. scoparius . The nomenclature of the hybrid is discussed and the necessary new name C. × despreauxii is proposed. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 187–204. 相似文献
52.
POLYANNA DA CONCEIÇÃO BISPO MÁRCIO DE MORISSON VALERIANO JOÃO ROBERTO DOS SANTOS 《Austral ecology》2012,37(4):491-499
The objective of this study was to identify the effects of local geomorphometry on the abundance, richness and floristic composition of tree species in the central Brazilian Amazon. Forty‐six 0.25‐ha plots in different phyto‐ecologic sites were sampled, and their trees were inventoried. Geomorphometric data (elevation, slope, aspect, plan and profile curvatures) were derived from Shuttle Radar Topography Mission data. A detrended correspondence analysis (DCA) was used to examine the floristic distribution patterns among plots. In addition, geomorphometric variables were submitted to multiple regression analysis to identify the variables influencing floristic composition (represented by the first DCA component), abundance and species richness. Correlation analyses between the number of individuals from each species and the first DCA component were performed to evaluate the contribution of each species. Analysis of the results could not confirm an effect of geomorphometry alone on species richness and abundance, although floristic composition was significantly influenced by profile curvature and elevation. Despite the relatively low variation in altitude at the study site, species were found to be sensitive to terrain peculiarities such as elevation and profile curvature, which can constrain particular ecologic niches and contribute to the spatial distribution patterns of species. 相似文献
53.
ANTE VUJI GUNILLA STÅHLS SANTOS ROJO SNEANA RADENKOVI SMILJKA IMI 《Zoological Journal of the Linnean Society》2008,152(3):507-536
We studied the phylogeny and systematics of the tribe Paragini (Diptera: Syrphidae) using morphological and molecular data. The paper presents separate parsimony analyses of both adult morphological characters and partial DNA sequence data from mitochondrial cytochrome c oxidase I and nuclear ribosomal 28S rRNA gene, as well as a combined analysis of all the data. The data set of morphological characters included some features of the male terminalia (i.e. shape of the ejaculatory apodeme; relative position of elements of the aedeagal complex; shape of surstylar apodeme; shape of the aedeagal apodeme) not previously used in the systematics of the Paragini. The trees obtained from separate parsimony analyses of molecular and morphological data produced almost identical topologies. Four lineages are supported by the combined data set, and we establish two new subgenera, i.e. Serratoparagus Vujić et Radenković subgen. nov., and Afroparagus Vujić et Radenković subgen. nov., and redefine Pandasyopthalmus Stuckenberg, 1954 stat. rev. and Paragus Latreille, 1804, stat. rev. The monophyly of the Pandasyopthalmus clade, including the species fitting neither of the current species groups ( jozanus -group) of Paragini, is established. Diagnoses of all known species groups are presented, including a new arrangement of almost all valid species of Paragini. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 507–536. 相似文献
54.
Carbon dioxide exchange above a Mediterranean C3/C4 grassland during two climatologically contrasting years 总被引:1,自引:0,他引:1
LUIS MIGUEL IGREJA AIRES CASIMIRO ADRIÃO PIO JOÃO SANTOS PEREIRA† 《Global Change Biology》2008,14(3):539-555
Eddy‐covariance measurements of net ecosystem carbon exchange (NEE) were carried out above a grazed Mediterranean C3/C4 grassland in southern Portugal, during two hydrological years, 2004–2005 and 2005–2006, of contrasting rainfall. Here, we examine the seasonal and interannual variation in NEE and its major components, gross primary production (GPP) and ecosystem respiration (Reco), in terms of the relevant biophysical controls. The first hydrological year was dry, with total precipitation 45% below the long‐term mean (669 mm) and the second was normal, with total precipitation only 12% above the long‐term mean. The drought conditions during the winter and early spring of the dry year limited grass production and the leaf area index (LAI) was very low. Hence, during the peak of the growth period, the maximum daily rate of NEE and the light‐use and water‐use efficiencies were approximately half of those observed in the normal year. In the summer of 2006, the warm‐season C4 grass, Cynodon dactylon L., exerted an evident positive effect on NEE by converting the ecosystem into a carbon sink after strong rain events and extending the carbon sequestration for several days, after the end of senescence of the C3 grasses. On an annual basis, the GPP and NEE were 524 and 49 g C m?2, respectively, for the dry year, and 1261 and ?190 g C m?2 for the normal year. Therefore, the grassland was a moderate net source of carbon to the atmosphere, in the dry year, and a considerable net carbon sink, in the normal year. In these 2 years of experiment the total amount of precipitation was the main factor determining the interannual variation in NEE. In terms of relevant controls, GPP and NEE were strongly related to incident photosynthetic photon flux density on short‐term time scales. Changes in LAI explained 84% and 77% of the variation found in GPP and NEE, respectively. Variations in Reco were mainly controlled by canopy photosynthesis. After each grazing event, the reduction in LAI affected negatively the NEE. 相似文献
55.
HELENA C. BARROS NEWTON V. VERBISCK SOLANGE DA SILVA MARCIA F. ARAGUTH RENATO A. MORTARA 《The Journal of eukaryotic microbiology》1997,44(4):332-344
ABSTRACT. In this study we have examined the distribution of epitopes defined by monoclonal antibodies raised against Trypanosoma cruzi amastigotes during the intraceullar life cycle of the parasite. We have raised monoclonal antibodies towards amastigote forms and performed preliminary immunochemical characterization of their reactivities. MAB 1D9, 3G8, 2B7, 3B9, and 4B9, and 4B9 react with carbohydrate epitopes of the parasite major surface glycoprotein—Ssp-4 defined by MAB 2C2 [5]: MAB 4B5 reacts with a noncarbohydrate epitope in all developmental stages of the parasite, and MAB 3B2 also detects a noncarbohydrate epitope preferentially in T. cruzi flagellared forms. Vero cells infected with tissue culture-derived trypomastigotes of clone D11 (G strain) were fixed at different times during the intraceullular proliferation of parasites, and processed for immjno-electron microscopy and confocal immunoflurescence with the different monoclonal antibodies. We observed that while the surface distribution of MAB 2C2 and 4B9 epitopes was uniform throughout the cycle, MAB 1D9, 3G8, and 2B7 reacted with cytoplasmic membrance-bound compartments of the amastigotes. MAB 3B9 displayed a unique surface dentate pattern in some amastigotes. MAB 4B5 recognized a curved-shaped structure at the flagellar pocket region in some intracellular amastigotes and localized to the membrane in dividing forms. In intracellular trypomastigotes, MAB 4B5 also displayed a punctate pattern near the flagellar pocket. 相似文献
56.
HELENA C. BARROS SOLANGE DA SILVA NEWTON V. VERBISCK MARCIA F. ARAGUTH ROBERTO C. TEDESCO DANIELA O. PROCOPIO RENATO A. MORTARA 《The Journal of eukaryotic microbiology》1996,43(4):275-285
ABSTRACT. Upon incubation at 37° C onto glass coverslips coated with Concanavalin A, poly-L-lysine, or a monoclonal antibody (1D9) directed to the parasite major surface glycoprotein Ssp-4, extracellular Trypanosoma cruzi amastigotes release trails of material barely visible by light microscopy. This release is not associated with parasite movements. Immunolabeling studies confirmed that the material is derived from the parasite's membrane since thin section through samples labeled with 1D9 revealed that the trails are membrane-bound structures. Scanning electron microscopy showed that the ∼0.1-μm thick trails of material emerging from the amastigotes can be uniform or beaded, indicating a tendency to vesiculation. The trails are preferentially released from the flagellar pocket region and/or at the opposite posterior end of the parasite body, and seem to be devoid of microtubules. The release is time and temperature-dependent and fixed parasites do not form trails. All attempts to inhibit trail release using drugs (antimycin A, sodium azide, cytochalasin D, nocodazole, genistein, staurosporine, EGTA) failed. The observation of trails associated with intracellular parasites and amastigotes invading Vero cells suggests that this is probably a physiological process. 相似文献
57.
Abstract. The influence of different nitrogen levels was studied in the CAM facultative Kalanchoë lateritia by watering some plants with Hoagland's solution (which contains, besides other ions, NO3?= 14.47mol m?3and NH4+= 1.04mol m?3; N group), and others with the same solution but with combined nitrogen concentration reduced to either one fifth (NO3?= 2.894mol m?3 and NH4+= 0.208mol m?3; N/5 group) or one tenth (NO3?= 1.447mol m?3and NH4+= 0.104mol m-3;N/10 group). The influence of the three nitrogen levels on CAM expression was assessed through activities of PEP-Case, PPD and RuBisCo, diurnal fluctuation of titratable acidity, mesophyll succulence, soluble protein, chlorophyll, nitrate, starch contents, pattern of nocturnal CO2 exchange and electron microscopy. CAM photosynthesis was more intense in N/5 plants which also had the highest Sm value. The activity of RuBisCo showed no significant differences in the three situations (expressed on chlorophyll basis) whereas both PEP-Case and PPD had higher values in N/5” plants. Chlorophyll and soluble protein were more abundant in the N plants followed by N/5 and N/10 plants. Nitrate was higher in N plants and starch content in N/5 plants. IRGA determination of CO2 nocturnal uptake showed that N/5 plants began CO2 capture earlier and at a more intense rate and for a longer period than plants from other groups also having a daily variation of titratable acidity (97.71 ± 10.8 μeq. G?1 f.w.) indicative of performing strong CAM. Electron microscope morphometric analysis revealed larger chloroplasts in N plants and smaller in N/10 plants, with starch fractional volume higher in N/5 plants, correlating with more intense CAM activity of these plants. 相似文献
58.
59.
A review of the genus Semele (Ruscaceae) systematics in Madeira 总被引:2,自引:0,他引:2
MIGUEL ÂNGELO ALMEIDA PINHEIRO DE CARVALHO CHRISTOPHER CHARLES WILCOCK TERESA MARIA MARQUES DOS SANTOS IOLANDA CATARINA VALE LUCAS JOSÉ FILIPE TEIXEIRA GANANÇA EMANUEL FRANCO DEVARAJAN THANGADURAI DOULATHABAD MURALIDHARA RAO NÉLIA FREITAS SOUSA 《Botanical journal of the Linnean Society. Linnean Society of London》2004,146(4):483-497
The present study attempts to review the systematics of Semele (Ruscaceae) in Madeira, based on phenotypic diversity. The variation in some vegetative (climbing shoot, second-order branches or 'phylloclades') and sexual (inflorescence and flowers) characters was analysed in 115 plant specimens from 30 field populations, herbaria of the Costa collection and Madeira Botanical Garden (MADJ) and certain gardens. Thirty-one quantitative and qualitative characters have been utilized in the analysis. Kaiser–Meyer–Olkin (KMO) analysis indicates adequate sampling. Principal component analysis (PCA) reveals that the spatial distribution of individuals has a discontinuous behaviour. Principal coordinate analysis (PCO) utilizing the Gower coefficient on standardized data revealed a significantly discontinuous distribution of individuals, such that two different clusters can be defined. The Student's t -test and Tukey test on separate characters, when individuals were classified according to the Costa classification, confirms the significant differences between grouping accessions. This leads to the recognition of two species within the genus in Madeira. Literature and herbarium studies show that these two taxa are conspecific with Semele androgyna (L.) Kunth sensu stricto (s.s.) and Semele menezesi Costa sensu lato (s.l.) . A separated statistical analysis of the S. androgyna cluster shows the possible existence of additional subgroups. Based on field population distribution, ecological behaviour and variation in features, we propose the recognition of two species, S. androgyna (L.) Kunth and S. menezesi (Costa) Pinheiro de Carvalho, and two subspecies S. androgyna (L.) Kunth androgyna Pinheiro de Carvalho and S. androgyna (L.) Kunth pterygophora Pinheiro de Carvalho. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 483–497. 相似文献
60.
DAVID A. ANDOW JULIANO R. FARIAS RENATO J. HORIKOSHI DANIEL BERNARDI ANTONIO R. B. NASCIMENTO CELSO OMOTO 《Ecological Entomology》2015,40(3):229-236
1. Antagonistic interactions in herbivorous insects are often density‐dependent, so rates are predicted to vary dynamically over time as density changes. Fatal intraspecific interactions, especially cannibalism, occur between equal‐aged larvae in young first‐ and second‐instar Spodoptera frugiperda (J.E. Smith). 2. A cannibalism experiment was conducted, starting with seven different densities of neonate S. frugiperda larvae, each replicated 50 times. Larvae were examined daily for the duration of the first and second instars (7 days). Seven‐day mortality was density‐dependent. 3. A stochastic mathematical model was developed in which per‐capita mortality from antagonistic interactions among equal‐aged larvae varies dynamically as density changes. A maximum likelihood method was developed to estimate the conditional per‐capita mortality rate from antagonistic interactions given an intraspecific encounter. An alternative model with mean‐mortality from antagonistic interactions that depends only on the initial larval density was also developed. 4. The models were fitted to the experimental data, and compared using log‐likelihood. The dynamic model fitted the cannibalism data significantly better than the time‐averaged mortality model for all starting densities for the experimental data, implying that density‐dependent mortality varied dynamically over time even within short 7‐day periods. 5. The conditional per‐capita mortality rate from antagonistic interactions was also density‐dependent, possibly because encounters became more aggregated at higher density, or because the probability that a larva died from the interaction was higher at higher density, or both. 相似文献