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971.
Background
Extracting biological information from high-density Affymetrix arrays is a multi-step process that begins with the accurate annotation of microarray probes. Shortfalls in the original Affymetrix probe annotation have been described; however, few studies have provided rigorous solutions for routine data analysis. 相似文献972.
Roberto Gamarra Emma Ortúñez Pablo Galán Cela Virginia Guadaño 《Plant Systematics and Evolution》2012,298(3):597-607
Seed micromorphology of 24 taxa of the genera Anacamptis and Orchis was examined under light and scanning electron microscopy. Seed qualitative characters appear very useful at the supraspecific
level in the subtribe Orchidinae. Based on our observations, the sculpturing of the periclinal walls of the medial testa cells,
the seed shape and several features of the anticlinal walls of the apical cells showed variability between the studied taxa,
with special relevance of the first character. According to this factor, we found one type of seed for Anacamptis and two for Orchis. The taxonomic value of seed coat characters is compared with the last taxonomic proposals for the genera Anacamptis and Orchis. 相似文献
973.
Biosynthesis of flavonoid derivatives requires enzyme(s) having high reactivity as well as regioselectivity. We have synthesized
3-O-kaempferol from naringenin using two enzymes. The first reaction, in which naringenin is converted to kaempferol, is mediated
by flavonol synthase (FLS). An FLS (PFLS) with strong catalytic activity was cloned and characterized from the genome sequence of the poplar (Populus deltoides). PFLS consists of a 1,008 bp ORF encoding a 38 kDa protein. PFLS was expressed in Escherichia coli with a glutathione-S-transferase (GST) tagging. The purified recombinant PFLS was characterized. Catalytically, it was more efficient than the
previously characterized FLSs. A mixture of two E. coli transformants harboring either PFLS or ROMT9 (a kaempferol 3-O-methyltransferase) converted naringenin into 3-O-methylkaempferol. 相似文献
974.
Wesley K. Savage 《Conservation Genetics》2008,9(6):1707-1710
Habitat loss is the single greatest threat to persistence of the critically threatened California tiger salamander (Ambystoma californiense). To aid management plans that designate critical habitat for this species, I developed and characterized 21 tetranucleotide
microsatellite markers using two native populations in Santa Barbara and Alameda Counties. Allelic variation and average heterozygosities
were lower in the endangered Santa Barbara population (allele range 1–4, mean 2.4; H
O = 0.308 H
E = 0.288) compared with the threatened Alameda population (allele range 2–10, mean 6.7; H
O = 0.712, H
E = 0.722). In-depth population studies using these markers will provide vital information for plans to assign critical habitat
that optimize gene flow among breeding populations, as well as for identifying non-native hybrid genotypes that threaten native
A. californiense stocks. Beyond the conservation goals for A. californiense, the close phylogenetic relationships within the tiger salamander complex also suggest a broad utility for population studies
using these markers. 相似文献
975.
Vinícius M. Barroso Liliana O. Rocha Tatiana A. Reis Gabriela M. Reis Aildson P. Duarte Marcos D. Michelotto Benedito Correa 《Mycotoxin Research》2017,33(2):121-127
Fusarium verticillioides is one of the main pathogens of maize, causing ear and stalk rots. This fungus is also able to produce high levels of fumonisins, which have been linked to various illnesses in humans and animals. Previous studies have shown that maize hybrids genetically modified with the cry genes from the bacterium Bacillus thuringiensis (Bt) presented lower incidence of F. verticillioides and fumonisin levels, presumably through the reduction of insects, which could act as vectors of fungi. The aim of this study was to assess the incidence of F. verticillioides and the concentration of fumonisins in Bt and isogenic non-Bt hybrids (2B710Hx, 30F35YG, 2B710, and 30F35, respectively). The samples of 2B710Hx and 30F35YG presented lower F. verticillioides frequency than 2B710 and 30F35 samples. However, there was no statistical difference between fumonisin contamination when Bt and non-Bt samples were compared (P > 0.05). The results suggest that other environmental parameters could possibly trigger fumonisin production during plant development in the field; consequently, other management strategies should be applied to aid controlling fumonisin contamination in maize. 相似文献
976.
Several chromosome types have been recognized in Citrus and related genera by chromomycin A3 (CMA) banding patterns and fluorescent in situ hybridization (FISH). They can be used to characterize cultivars and species
or as markers in hybridization and backcrossing experiments. In the present work, characterization of six cultivars of P. trifoliata (“Barnes”, “Fawcett”, “Flying Dragon”, “Pomeroy”, “Rubidoux”, “USDA”) and one P. trifoliata × C. limonia hybrid was performed by sequential analyses of CMA banding and FISH using 5S and 45S rDNA as probes. All six cultivars showed
a similar CMA+ banding pattern with the karyotype formula 4B + 8D + 6F. The capital letters indicate chromosomal types: B, a chromosome
with one telomeric and one proximal band; D, with only one telomeric band; F, without bands. In situ hybridization labeling
was also similar among cultivars. Three chromosome pairs displayed a closely linked set of 5S and 45S rDNA sites, two of them
co-located with the proximal band of the B type chromosomes (B/5S-45S) and the third one co-located with the terminal band
of a D pair (D/5S-45S). The B/5S-45S chromosome has never been found in any citrus accessions investigated so far. Therefore,
this B chromosome can be used as a marker to recognize the intergeneric Poncirus × Citrus hybrids. The intergeneric hybrid analyzed here displayed the karyotype formula 4B + 8D + 6F, with two chromosome types B/5S-45S
and two D/5S-45S. The karyotype formula and the presence of two B/5S-45S chromosomes clearly indicate that the plant investigated
is a symmetric hybrid. It also demonstrates the suitability of karyotype analyses to differentiate zygotic embryos or somatic
cell fusions involving trifoliate orange germplasm.
During the submission of this paper, we analyzed 25 other citrus cultivars with the same methodology and we found that the
chromosome marker reported here can indeed distinguish Poncirus trifoliata from grapefruits, pummelos, and one variegated access of Citrus, besides the previously reported access of limes, limons, citrons, and sweet-oranges. However, among 14 mandarin cultivars,
two of them displayed a single B/5S-45S chromosome, whereas in Citrus hystrix D.C., a far related species belonging to the Papeda subgenus, this chromosome type was found in homozygosis. Since these two mandarin cultivars are probably of hybrid origin,
we assume that for almost all commercial cultivars and species of the subgenus Citrus this B type chromosome is a useful genetic marker. 相似文献
977.
Influence of the Hydrological Cycle on the Bacterioplankton of an Impacted Clear Water Amazonian Lake 总被引:4,自引:0,他引:4
Abstract
Free-living and attached bacterial population sizes were determined fortnightly from December 1991 to December 1992 in natural
and disturbed areas of an Amazonian clear water lake (Batata Lake, Pará, Brazil) impacted by bauxite tailings. The bacterioplankton
showed distinct patterns during different phases of the hydrological cycle. Total bacterial population size and rates of thymidine
incorporation (measured during high and low water phases) were high during low water, with values ranging from 3.3 × 105 to 1.1 × 106 cells ml−1, and from 0.28 to 4.01 μg C l−1 h−1, respectively. The population size of free-living bacteria was larger at the natural station, while no differences were observed
between attached bacterial populations at both stations. However, production and turnover rate of attached bacteria were high
at the disturbed area. During low water, bacterial growth appeared to be driven mainly by the input of dissolved organic carbon
(DOC) from phytoplankton origin. During high water, bacterial abundance was reduced, probably as the result of dilution and
the input of less labile DOC from floodplains. The presence of bauxite tailings seems to influence bacterial dynamics in an
indirect way, probably due to shading of phytoplankton cells and, hence, reducing the DOC supply for bacterial growth. This
study, the first on the microbial ecology of an Amazonian clear water lake, demonstrated that water level variations exert
a strong influence on the bacterioplankton dynamics.
Received: 9 January 1996; Accepted 6 November 1996 相似文献
978.
Ozaki S Imai H Iwakiri T Sato T Shimoda K Nakayama T Hamada H 《Biotechnology letters》2012,34(3):475-481
A glucosyltransferase (GT) of Phytolacca americana (PaGT3) was expressed in Escherichia coli and purified for the synthesis of two O-β-glucoside products of trans-resveratrol. The reaction was moderately regioselective with a ratio of 4′-O-β-glucoside: 3-O-β-glucoside at 10:3. We used not only the purified enzyme but also the E. coli cells containing the PaGT3 gene for the synthesis of glycoconjugates. E. coli cell cultures also have other advantages, such as a shorter incubation time compared with cultured plant cells, no need for
the addition of exogenous glucosyl donor compounds such as UDP-glucose, and almost complete conversion of the aglycone to
the glucoside products. Furthermore, a homology model of PaGT3 and mutagenesis studies suggested that His-20 would be a catalytically
important residue. 相似文献
979.
Ozu M Dorr RA Teresa Politi M Parisi M Toriano R 《European biophysics journal : EBJ》2011,40(6):737-746
This work studies water permeability properties of human aquaporin 1 (hAQP1) expressed in Xenopus laevis oocyte membranes, applying a technique where cellular content is replaced with a known medium, with the possibility of measuring
intracellular pressure. Consequences on water transport—produced by well-known anisotonic gradients and by the intracellular
effect of probable aquaporin inhibitors—were tested. In this way, the specific intracellular inhibition of hAQP1 by the diuretic
drug furosemide was demonstrated. In addition, experiments imposing anisotonic mannitol gradients with a constant ionic strength
showed that the relationship between water flux and the applied mannitol gradient deflects from a perfect osmometer response
when the gradient is higher than 150 mosmol kgW−1. These results would indicate that the passage of water molecules through hAQP1 may have a maximum rate. As a whole, this
work demonstrates the technical advantage of controlling both intracellular pressure and medium composition in order to study
biophysical properties of hAQP1, and contributes information on water channel behavior under osmotic challenges and the discovery
of new inhibitors. 相似文献
980.
María Belén Hapon Carlos Gamarra-Luques Graciela A Jahn 《Reproductive biology and endocrinology : RB&E》2010,8(1):14