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排序方式: 共有345条查询结果,搜索用时 15 毫秒
81.
Roberto Arrigoni Michael L. Berumen Jaroslaw Stolarski Tullia I. Terraneo Francesca Benzoni 《Cladistics : the international journal of the Willi Hennig Society》2019,35(3):301-328
Extant biodiversity can easily be underestimated owing to the presence of cryptic taxa, even among commonly observed species. Scleractinian corals are challenging to identify because of their ecophenotypic variation and morphological plasticity. In addition, molecular analyses have revealed the occurrence of cryptic speciation. Here, we describe a new cryptic lobophylliid genus and species Paraechinophyllia variabilis gen. nov., sp. nov., which is morphologically similar to Echinophyllia aspera and E. orpheensis. The new taxon occurs in Mayotte Island, Madagascar, the Gulf of Aden and the Red Sea. Six molecular markers (COI, 12S, ATP6-NAD4, NAD3-NAD5, histone H3 and ITS) and 46 morphological characters at three different levels (macromorphology, micromorphology and microstructure) were examined. The resulting molecular phylogenetic reconstruction showed that Paraechinophyllia gen. nov. represents a distinct group within the Lobophylliidae that diverged from the lineage leading to Echinophyllia and Oxypora in the Early Miocene, approximately 21.5 Ma. The morphological phylogenetic reconstruction clustered Paraechinophyllia gen. nov., Echinophyllia and Oxypora together in a single clade. A sole morphological character, calice relief, discriminated Paraechinophyllia gen. nov. from the latter two genera, suggesting that limited morphological variation has occurred over a long period. These results highlight the importance of cryptic taxa in reef corals, with implications for population genetics, ecological studies and conservation. 相似文献
82.
Wojciech Ciesielski Bohdan Achremowicz Piotr Tomasik Malgorzata Baczkowicz Jaroslaw Korus 《Carbohydrate polymers》1997,34(4):577-308
Several varieties of flours were subjected to thermolysis up to 400 °C. The thermal characteristics of 13 flours were similar for all flours except soy. The weight loss of these flours up to 400 °C ranged from 65 to 97%. Although flours began to decompose at lower temperatures than did corresponding starches, there was less radical decomposition in flours than in starches as proved by Electron Paramagnetic Resonance absorption (EPR) spectra. The order of heat resistance to the radical decomposition for starches and flours paralleled one another, however, flours generated radicals at temperatures approximately 20 °C higher than in corresponding starches. The data showed that cereals did not form free radicals before carbonization and thus they could be safely processed in the temperature intervals generally used in baking, roasting, and frying. 相似文献
83.
Sharakhova MV Hammond MP Lobo NF Krzywinski J Unger MF Hillenmeyer ME Bruggner RV Birney E Collins FH 《Genome biology》2007,8(1):R5
Background
The genome of Anopheles gambiae, the major vector of malaria, was sequenced and assembled in 2002. This initial genome assembly and analysis made available to the scientific community was complicated by the presence of assembly issues, such as scaffolds with no chromosomal location, no sequence data for the Y chromosome, haplotype polymorphisms resulting in two different genome assemblies in limited regions and contaminating bacterial DNA. 相似文献84.
AW Mailloux C Sugimori RS Komrokji L Yang JP Maciejewski MA Sekeres R Paquette TP Loughran AF List PK Epling-Burnette 《Journal of immunology (Baltimore, Md. : 1950)》2012,189(6):3198-3208
Myelodysplastic syndromes are premalignant diseases characterized by cytopenias, myeloid dysplasia, immune dysregulation with association to autoimmunity, and variable risk for acute myeloid leukemia transformation. Studies of FOXP3(+) regulatory T cells (Tregs) indicate that the number and/or activation state may influence cancer progression in these patients. Focusing on patients with a lower risk for leukemia transformation, 18 (34.6%) of 52 patients studied displayed an altered Treg compartment compared with age-matched controls. Delineation of unique Treg subsets revealed that an increase in the absolute number of CD4(+)FOXP3(+)CD25(+)CD127(low)CD45RA(-)CD27(-) Tregs (effector memory Tregs [Treg(EM)]) was significantly associated with anemia (p = 0.046), reduced hemoglobin (p = 0.038), and blast counts ≥5% (p = 0.006). In healthy donors, this Treg(EM) population constitutes only 2% of all Tregs (one to six Tregs per microliter) in peripheral blood but, when isolated, exhibit greater suppressive activity in vitro. With a median follow-up of 3.1 y (range 2.7-4.9 y) from sample acquisition, increased numbers of Treg(EM) cells proved to have independent prognostic importance in survival estimates, suggesting that enumeration of this Treg subset may be a more reliable indicator of immunological escape than FOXP3(+) T cells as a whole. Based on multivariate analyses, Treg(EM) impacted survival independently from myeloblast characteristics, cytopenias, karyotype, and comorbidities. Based on these findings, Treg(EM) cell expansion may be synonymous with human Treg activation and indicate microenvironmental changes conducive to transformation in myelodysplastic syndromes. 相似文献
85.
Andrew AJ Dutkiewicz R Knieszner H Craig EA Marszalek J 《The Journal of biological chemistry》2006,281(21):14580-14587
Jac1p is a conserved, specialized J-protein that functions with Hsp70 in Fe-S cluster biogenesis in mitochondria of the yeast Saccharomyces cerevisiae. Although Jac1p as well as its specialized Hsp70 partner, Ssq1p, binds directly to the Fe-S cluster scaffold protein Isu, the Jac1p-Isu1p interaction is not well understood. Here we report that a C-terminal fragment of Jac1p lacking its J-domain is sufficient for interaction with Isu1p, and amino acid alterations in this domain affect interaction with Isu1p but not Ssq1p. In vivo, such JAC1 mutations had no obvious phenotypic effect. However, when present in combination with a mutation in SSQ1 that causes an alteration in the substrate binding cleft, growth was significantly compromised. Wild type Jac1p and Isu1p cooperatively stimulate the ATPase activity of Ssq1p. Jac1p mutant protein is only slightly compromised in this regard. Our in vivo and in vitro results indicate that independent interaction of Jac1p and the Isu client protein with Hsp70 is sufficient for robust growth under standard laboratory conditions. However, our results also support the idea that Isu protein can be "targeted" to Ssq1p after forming a complex with Jac1p. We propose that Isu protein targeting may be particularly important when environmental conditions place high demands on Fe-S cluster biogenesis or in organisms lacking specialized Hsp70s for Fe-S cluster biogenesis. 相似文献
86.
Distinct DNA repair pathways involving RecA and nonhomologous end joining in Mycobacterium smegmatis
Korycka-Machala M Brzostek A Rozalska S Rumijowska-Galewicz A Dziedzic R Bowater R Dziadek J 《FEMS microbiology letters》2006,258(1):83-91
Mycobacterium smegmatis was used to study the relationship between DNA repair processes involving RecA and nonhomologous end joining (NHEJ). The effect of gene deletions in recA and/or in two genes involved in NHEJ (ku and ligD) was tested on the ability of bacteria to join breaks in plasmids transformed into them and in their response to chemicals that damage DNA. The results provide in vivo evidence that only NHEJ is required for the repair of noncompatible DNA ends. By contrast, the response of mycobacteria to mitomycin C preferentially involved a RecA-dependent pathway. 相似文献
87.
88.
Although microsatellites are a very efficient tool for many population genetics applications, they may occasionally produce "null" alleles, which, when present in high proportion, may affect estimates of key parameters such as inbreeding and relatedness coefficients or measures of genetic differentiation. In order to account for the presence of null alleles, it is first necessary to estimate their frequency within studied populations. However, the commonly used null allele frequency estimators are not of general applicability because they can produce upwardly biased estimates when a population under study experiences some inbreeding. In such a case, 2 formerly described approaches, population inbreeding model and individual inbreeding model, can be applied for simultaneous estimation of null allele frequencies and of the inbreeding coefficient. In this study, we demonstrate the properties and utility of these 2 methods and show that they outperform the commonly used approaches in the estimation of null allele frequencies based on genotypic data. The methods are applied to empirical data from a natural population of European beech (Fagus sylvatica L.), and results are briefly discussed. The methods presented in this paper are implemented in the Windows-based user-friendly INEST computer program (available free of charge at http://genetyka.ukw.edu.pl/INEst10_setup.exe). 相似文献
89.
90.
Thionins, ubiquitous plant toxins, are believed to act by lysing the membrane of pathogenic organisms. Several competing mechanisms
were proposed for the lysis of phospholipid membranes by the toxins. In order to study in more detail the proposed mechanisms
and possibly resolve among the competing proposals, the interactions of purothionins with a model lipid membrane in the form
of a monolayer were studied. The monolayer formed at the air-water interface was studied by synchrotron X-ray reflectivity
and grazing incidents diffraction methods. The model membrane was composed of 90:10 mol% DPPC:DPPS (dipylmitoyl phosphatidylcholine:dipylmitoyl
phosphatidylserine). The protein interaction with the monolayer disturbs the in-plane and out-of-plane order of phospholipids,
increases the amount of the liquid phase of the monolayer, and increases the average surface area per alkyl chain. The results
indicate that the protein is bound only transiently, and after ~4 h most of the properties of the monolayer are reminiscent
of the pure DPPC monolayer suggesting partial withdrawal of DPPS. Obtained electron density distributions perpendicular to
the membrane interface do not show any significant contribution from the adsorbed proteins, further supporting the withdrawal
hypothesis. 相似文献