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排序方式: 共有1006条查询结果,搜索用时 375 毫秒
71.
Gina Brito Tina Lopes João Loureiro Eleazar Rodriguez Conceição Santos 《Trees - Structure and Function》2010,24(4):723-732
Micropropagated plants from two wild-olive species, Olea maderensis and O. europaea ssp. europaea var. sylvestris were screened for genetic stability. O. maderensis shoots were elongated/multiplied on OMG medium with zeatin (9.12 μM), and rooted on 1/2 OMG with NAA (3.22 μM). O. europaea var. sylvestris shoots were elongated/multiplied on OM medium with zeatin, and rooting was optimal after a hormonal shock (IBA 100 μM) followed
by transfer to the same medium without growth regulators. In both species, acclimatization was successful and plants looked
normal and morphologically identical to the donor field trees. Genetic variability was assessed at several stages of the micropropagation
process using flow cytometry (FCM) and nuclear microsatellites (SSR). No changes in ploidy level were found among micropropagated
plants, though small deviations, putatively due to the negative effects of cytosolic compounds on propidium iodide staining,
between these and field plants were observed. In SSRs analyses, ten SSR markers were able to distinguish between genotypes.
No mutations were found in these tested SSR loci among the donor tree and micropropagated plants, suggesting, for the tested
markers, genetic uniformity throughout the process. The FCM and SSR results obtained do not exclude the occurrence of other
changes in the nuclear genome but, considering the morphological stability of micropropagated plants, indicate that both protocols
are suitable and efficient for large scale, true-to-type micropropagation of these two wild olive species. 相似文献
72.
The objective of this study was to describe sperm ultrastructure, morphometry, and abnormal morphology in American black bears. Electroejaculation was successful in 53.8% (7/13) of the attempts, but urine contamination was common. Epididymal sperm samples were also obtained from five bears. Sperm had a paddle-like head shape and the ultrastructure was similar to that of most other mammals. The most striking particularity of black bear sperm ultrastructure was a tightening of the nucleus in the equatorial region. Although the differences were not significant in all bears, the overall decrease in sperm nucleus dimensions during transport from the caput epididymis to the cauda suggested increasing compaction of the nucleus during maturation. For ejaculated sperm, nucleus length, width, and base width were 4.9, 3.7, and 1.8 μm, respectively, whereas sperm head length, width, and base width were 6.6, 4.8, and 2.3 μm, and midpiece, tail (including midpiece), and total sperm lengths were 9.8, 68.8, and 75.3 μm. Evaluation of sperm cytoplasmic droplets in the epididymis revealed that proximal droplets start migrating toward a distal position in the caput epididymis and that the process was mostly completed by the time sperm reached the cauda epididymis. The proportion of morphologically normal sperm in the ejaculate was 35.6%; the most prevalent sperm defects were distal cytoplasmic droplets and bent/coiled tails. The morphology of abnormal sperm and the underlying ultrastructural defects were similar to that in other large domestic animals thus suggesting similar underlying pathogenesis of specific sperm defects and similar effects on fertility. 相似文献
73.
Joana Tomomi Sumikawa Marlon Vilela de Brito Maria Ligia Rodrigues Macedo Adriana F. Uchoa Antonio Miranda Ana Paula U. Araujo Rosemeire A. Silva-Lucca Misako Uemura Sampaio Maria Luiza Vilela Oliva 《Phytochemistry》2010,71(2-3):214-220
Three plant proteinase inhibitors BbKI (kallikrein inhibitor) and BbCI (cruzipain inhibitor) from Bauhinia bauhinioides, and a BrTI (trypsin inhibitor) from B. rufa, were examined for other effects in Callosobruchus maculatus development; of these only BrTI affected bruchid emergence. BrTI and BbKI share 81% identities in their primary sequences and the major differences between them are the regions comprising the RGD and RGE motifs in BrTI. These sequences were shown to be essential for BrTI insecticidal activity, since a modified BbKI [that is a recombinant form (BbKIm) with some amino acid residues replaced by those found in BrTI sequence] also strongly inhibited insect development. By using synthetic peptides related to the BrTI sequence, YLEAPVARGDGGLA-NH2 (RGE) and IVYYPDRGETGL-NH2 (RGE), it was found that the peptide with an RGE sequence was able to block normal development of C. maculatus larvae (ED50 0.16% and LD50 0.09%), this being even more effective than the native protein. 相似文献
74.
75.
A secretory form of human α3-fucosyltransferase IX (sFUT9) was overexpressed in Spodoptera frugiperda (Sf9) insect cells using the stable expression vector pIB/V5-His-TOPO and the signal sequence of human interleukin 2 for
efficient secretion. sFUT9 was active and its three potential N-glycosylation sites were occupied. sFUT9 efficiently fucosylated the type II acceptors Galbeta4GlcNAC-R and Fucalpha2Galbeta4GlcNAc-R
(R = (CH2)3NHCO(CH2)5–NH-biotin) but not the corresponding sialylated acceptor, and only very poorly the type I (Galbeta3GlcNAc-R)
related acceptors. sFUT9 showed a clear preference for glycoproteins containing type II acceptors, with values of 121, 113
and 110 microU/million cell for asialofetuin, erythropoietin and asialoerythropoietin, respectively, values approximately
11-fold higher than those obtained for the small acceptors. 相似文献
76.
Júnior FA Brilhante RS Cordeiro RA Brito EH Sidrim JJ Rocha MF 《Journal of microbiological methods》2007,69(1):218-221
We describe simple and cost-effective methods using carbohydrates to improve the in vitro viability of dermatophytes. Glucose and sucrose in different concentrations (3, 6, 9 and 12%) were used to maintain fifteen strains of M. canis and T. mentagrophytes var. mentagrophytes at 4 and -20 degrees C. The strains were phenotypically analyzed before storage and reevaluated at 1, 3, 6 and 9 months. At 1 and 3 months, any alterations in the viability or phenotype pattern of the stored strains were noted. At 6 months, both dermatophytes were 100% viable, when preserved in glucose (3, 6, 9 and 12%) at -20 degrees C. All T. mentagrophytes strains were also viable in sucrose (12%), at 4 degrees C and -20 degrees C. However, sucrose failed to improve the viability of M. canis at both temperatures. At 9 months, the higher viabilities without pleomorphism were seen for both dermatophytes preserved in glucose (9 and 12%) at -20 degrees C. 相似文献
77.
J. Moutinho-Pereira N. Magalhães B. Gonçalves E. Bacelar M. Brito C. Correia 《Photosynthetica》2007,45(2):202-207
Optical characteristics, contents of photosynthetic pigments, total soluble sugars, and starch, rates of gas exchange, chlorophyll (Chl) a fluorescence, and leaf water relations were analysed in three Vitis vinifera L. cultivars, Tinto Cão (TC), Touriga Nacional (TN), and Tinta Roriz (TR), grown in Mediterranean climate. Chl content was significantly lower in TC than in TN and TR leaves, while the Chl a/b ratio was higher. TR had the lowest net photosynthetic rate, stomatal conductance, and contents of soluble sugars and starch than TN and TC. In spite of low Chl content, TC showed the lowest photon absorbance and the highest photochemical efficiency of photosystem 2. TC had the lowest predawn and midday leaf water potential. The capability for osmotic adjustment was similar among cultivars and the calculated modulus of elasticity was higher in TC leaves. The typical lighter green leaves of TC seemed to be an adaptive strategy to high irradiance and air temperature associated to water stress. 相似文献
78.
Laurentino EC Ruiz JC Brito LO Fiandt M Nicoletti LM Jamur MC Oliver C Tosi LR Cruz AK 《International journal for parasitology》2007,37(7):735-742
The use of transposable elements as a gene-trapping strategy is a powerful tool for gene discovery. Herein we describe the development of a transposable system, based on the bacterial Tn5 transposon, which has been used successfully in Leishmania braziliensis. The transposon carries the neomycin phosphotransferase gene, which is expressed only when inserted in-frame with a Leishmania gene present in the target DNA. Four cosmid clones from a L. braziliensis genomic library were used as targets in transposition reactions and four insertional libraries were constructed and transfected in L. braziliensis. Clones resistant to G418 were selected and analysed by immunofluorescence in order to identify the subcellular localisation of the protein coded by the trapped gene. A definitive subcellular localisation for neomycin phosphotransferase/targeted protein fusion was not obtained in any of the four Leishmania clones investigated. However, the constructed transposable element is highly efficient considering the frequency of insertion in large targets and is therefore a useful tool for functional genetic studies in Leishmania. Our data confirm the utility of the Tn5 transposon system for insertion of sequencing priming sites into target DNA. Furthermore, the high frequency of insertion and even distribution are important in studying genomic regions bearing long and polymorphic repetitive sequences. 相似文献
79.
Contrasting patterns of mitochondrial and microsatellite genetic structure among Western European populations of tawny owls (Strix aluco) 总被引:2,自引:2,他引:0
Brito PH 《Molecular ecology》2007,16(16):3423-3437
A recent study of mitochondrial phylogeography of tawny owls (Strix aluco) in western Europe suggested that this species survived the Pleistocene glaciations in three allopatric refugia located in Iberia, Italy, and the Balkans, and the latter was likely the predominant source of postglacial colonization of northern Europe. New data from seven microsatellite loci from 184 individual owls distributed among 14 populations were used to assess the genetic congruence between nuclear and mitochondrial DNA (mtDNA) markers. Microsatellites corroborated the major phylogeographical conclusions reached on the basis of the mtDNA sequences, but also showed important differences leading to novel inferences. Microsatellites corroborated the three major refugia and supported the Balkan origin of northern populations. When corrected for differences in effective population size, microsatellites and mtDNA yielded generally congruent overall estimates of population structure (N*ST=0.12 vs. RST=0.16); however, there was substantial heterogeneity in the RST among the seven nuclear loci that was not correlated with heterozygosity. Populations representing the Balkans postglacial expansion interact with populations from the other two refugia forming two clines near the Alps and the Pyrenees. In both cases, the apparent position of the contact zones differed substantially between markers due to the genetic composition of populations sampled in northern Italy and Madrid. Microsatellite data did not corroborate the lower genetic diversity of northern, recently populated regions as was found with mtDNA; this discrepancy was taken as evidence for a recent bottleneck recovery. Finally, this study suggests that congruence among genetic markers should be more likely in cases of range expansion into new areas than when populations interact across contact zones. 相似文献
80.
Correlations between environmental factors and the distribution of amphibian and reptile species richness were investigated
in a climate transition area, Peneda-Gerês National Park (PNPG), in North-Western Portugal. Using presence-data at a local-scale
(1 × 1 km), Ecological-Niche Factor Analysis (ENFA) identified a mixture of climatic (precipitation and number of days with
fog), topographical (altitude and relief) and habitat factors (number of watercourses and water surfaces, the type of the
largest water surface and tree diversity cover), as accurate predictors of species occurrence. Three factors were common for
both taxonomic groups, and consistently presented a positive relation with species occurrence: precipitation, number of water
surfaces, and tree diversity cover; suggesting a strong coincidence in the environmental correlates that influence amphibian
and reptile species richness. Distribution patterns of observed and predicted species richness were compared using a Geographical
Information System. Overall, three high species richness areas were predicted in common for both taxonomic groups and two
additional areas for amphibians only. These areas matched with the observed species richness but suggested larger areas of
high species richness. The location of the PNPG in a biogeographic crossroad, between Euro-Siberian and Mediterranean provinces,
emphasised species richness of amphibians and reptiles and suggests a high priority conservation status for this protected
area. Most of Central-Northern Portugal is located in a climatic transition area; therefore, increased species richness should
be expected for other areas. Local scale studies for other protected areas should be planned as a framework for the development
of multi-scale conservation planning by Portuguese authorities. 相似文献