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961.
Enrique Arbeláez-Cortes María Fernanda Castillo-Cárdenas Nelson Toro-Perea Heiber Cárdenas-Henao 《Hydrobiologia》2007,583(1):321-330
Rhizophora mangle, one of the five species of the genus Rhizophora, is found widely distributed along the American and West African coasts. This species is one of the principal constituents
of the mangrove ecosystem in Colombia and is also found within the most important economic activities for the communities
that inhabit the littoral. In order to assess the degree of genetic diversity of R. mangle in five populations of the Colombian Pacific, nuclear microsatellite molecular markers were used. In 92 individuals sampled,
it was found that 100% of the loci were polymorphic
, and no private alleles were detected. The population structure of R. mangle in the Colombian Pacific, was highly significant (P < 0.001); however, the greatest differentiation was detected at the within-population level (94.62%). For the populations
of La Plata, Virudó and Charambirá, the tendency toward panmixia could be the cause of the low differentiation among these
three locations. Within populations, the genetic diversity revealed a deviation from Hardy–Weinberg equilibrium with high
significance in Virudó and Tumaco, where it appears the intense anthropogenic activity has exercised strong pressure on the
red mangrove, resulting in the possible fragmentation of the local landscape and therefore an increase in the rate of endogamy
within these populations. Despite this situation, our study―one of the first developed in genetics of the red mangrove in
Colombia―did not show evidence of recent bottleneck effects or deterioration in its genetic composition, which could be exploited
to propose management and restoration programs for the zones where the forests of this species are degraded.
Handling editor: K. Martens 相似文献
962.
Burgos JM Altcheh J Bisio M Duffy T Valadares HM Seidenstein ME Piccinali R Freitas JM Levin MJ Macchi L Macedo AM Freilij H Schijman AG 《International journal for parasitology》2007,37(12):1319-1327
Congenital transmission of Trypanosoma cruzi may occur in some or all the gestations from a T. cruzi-infected mother. Variable rates of congenital transmission have been reported in different geographical areas where different parasitic strains predominate, suggesting that parasitic genotypes might play a role in the risk of congenital transmission. Moreover, in cases of transmission it is unknown if the whole maternal T. cruzi population or certain clones are preferentially transmitted by the transplacental route. In this study, bloodstream T. cruzi lineages were identified in blood samples from congenitally infected children, transmitting and non-transmitting mothers and unrelated Chagas disease patients, using improved PCR strategies targeted to nuclear genomic markers. T. cruzi IId was the prevalent genotype among 36/38 PCR-positive congenitally infected infants, 5/5 mothers who transmitted congenital Chagas disease, 12/13 mothers who delivered non-infected children and 28/34 unrelated Chagas disease patients, all coming from endemic localities of Argentina and Bolivia. These figures indicate no association between a particular genotype and vertical transmission. Furthermore, minicircle signatures from the maternal and infants' bloodstream trypanosomes were profiled by restriction fragment length polymorphism of the 330-bp PCR-amplified variable regions in seven cases of mothers and congenitally infected infants. Minicircle signatures were nearly identical between each mother and her infant/s and unique to each mother-infant/s case, a feature that was also observed in twin deliveries. Moreover, allelic size polymorphism analysis of microsatellite loci from populations transmitted to twins showed that all clones from the maternal polyclonal population were equally infective to both siblings. 相似文献
963.
964.
Prieto MA 《Journal of bacteriology》2007,189(2):289-290
965.
Sánchez-Sutil MC Gómez-Santos N Moraleda-Muñoz A Martins LO Pérez J Muñoz-Dorado J 《Journal of bacteriology》2007,189(13):4887-4898
Myxococcus xanthus is a soil bacterium that undergoes a unique life cycle among the prokaryotes upon starvation, which includes the formation of macroscopic structures, the fruiting bodies, and the differentiation of vegetative rods into coccoid myxospores. This peculiarity offers the opportunity to study the copper response in this bacterium in two different stages. In fact, M. xanthus vegetative rods exhibit 15-fold-greater resistance against copper than developing cells. However, cells pre-adapted to this metal reach the same levels of resistance during both stages. Analysis of the M. xanthus genome reveals that many of the genes involved in copper resistance are redundant, three of which encode proteins of the multicopper oxidase family (MCO). Each MCO gene exhibits a different expression profile in response to external copper addition. Promoters of cuoA and cuoB respond to Cu(II) ions during growth and development; however, they show a 10-fold-increased copper sensitivity during development. The promoter of cuoC shows copper-independent induction upon starvation, but it is copper up-regulated during growth. Phenotypic analyses of deletion mutants reveal that CuoB is involved in the primary copper-adaptive response; CuoA and CuoC are necessary for the maintenance of copper tolerance; and CuoC is required for normal development. These roles seem to be carried out through cuprous oxidase activity. 相似文献
966.
Bacterial resistance to mercury (Hg) was investigated in strains isolated from Hg-contaminated tailing ponds located in the
gold mining area of El Callao (Bolívar State, Venezuela). High frequencies of resistance were detected to both inorganic-Hg
and organomercurials among these strains. A broad range of resistance levels was observed when determining minimal inhibitory
concentrations of Hg2+. Some strains were able to grow in liquid medium containing 25 μM Hg2+, whereas others grew at 300 μM Hg2+. Of 190 Hg-resistant strains tested, 58.2% were additionally shown to be resistant to ampicillin (40 mg/L), 33.3% to chloramphenicol
(30 mg/L), 24.9% to streptomycin (30 mg/L), 23.3% to tetracycline (30 mg/L), and 1.6% to kanamycin (30 mg/L). Furthermore,
we found that 20% of the Hg-resistant strains were simultaneously resistant to as many as four of these antibiotics, at the
concentrations tested. The presence of large plasmids in 62.9% of 53 Hg-resistant strains screened prompted us to investigate
the horizontal transfer of resistance determinants. Mating experiments were performed using Escherichia coli and Pseudomonas aeruginosa as recipient strains. The results obtained confirmed that indigenous Hg-resistant bacteria colonizing the tailing ponds can
effectively transfer the phenotype to potentially pathogenic species. 相似文献
967.
Liffourrena AS Massimelli MJ Forrellad MA Lisa AT Domenech CE Lucchesi GI 《Current microbiology》2007,55(6):530-536
Pseudomonas aeruginosa expresses hemolytic phospholipase C (PlcH) with choline or under phosphate-limiting conditions. PlcH from these conditions
were differently eluted from the Celite-545 column after application of an ammonium sulfate linear reverse gradient. The PlcH
from supernatants of bacteria grown in the presence of choline was eluted with 30% ammonium sulfate and was more than 85%
inhibited by tetradecyltrimethylammonium. PlcH from supernatants of bacteria grown with succinate and ammonium ions in a low-phosphate
medium was eluted as a peak with 10% of salt and was less than 10% inhibited by tetradecyltrimethylammonium. PlcH from low
phosphate was purified associated with a protein of 17 kDa. This complex was dissociated and separated on a Sephacryl S-200
column with 1% (w/v) sodium dodecyl sulfate. After this dissociation, the resulting protein of 70 kDa, corresponding to PlcH,
was inhibited by tetradecyltrimethylammonium, showing a protection effect of the accompanying protein. RT-PCR analyses showed
that in choline media, the plcH gene was expressed independently of plcR. In low-phosphate medium, the plcH gene was expressed as a plcHR operon. Because plcR encodes for chaperone proteins, this result correlates with the observation that PlcH from supernatants of bacteria grown
in the presence of choline was purified without an accompanying protein. The consequence of the absence of this chaperone
was that tetradecyltrimethylammonium inhibited the PlcH activity. 相似文献
968.
Responses of transformed Catharanthus roseus roots to femtomolar concentrations of salicylic acid. 总被引:1,自引:0,他引:1
Ileana Echevarría-Machado Rosa María Escobedo-G M Alfonso Larqué-Saavedra 《Plant Physiology and Biochemistry》2007,45(6-7):501-507
Catharanthus roseus transformed roots were cultured in the presence of salicylic acid (SA) at concentrations between 0.1 fM and 100 pM and the effect on root growth was evaluated. Significant morphological changes in the lateral roots were recorded on day two in the SA treatment. Presence of SA increased root cap size and caused the appearance of lateral roots closer to the root tip. The bioassay was sensitive enough to allow testing of low concentrations of other growth regulators that may affect root morphology and physiology. 相似文献
969.
García-Mayoral MF Hollingworth D Masino L Díaz-Moreno I Kelly G Gherzi R Chou CF Chen CY Ramos A 《Structure (London, England : 1993)》2007,15(4):485-498
The AU-rich element (ARE) RNA-binding protein KSRP (K-homology splicing regulator protein) contains four KH domains and promotes the degradation of specific mRNAs that encode proteins with functions in cellular proliferation and inflammatory response. The fourth KH domain (KH4) is essential for mRNA recognition and decay but requires the third KH domain (KH3) for its function. We show that KH3 and KH4 behave as independent binding modules and can interact with different regions of the AU-rich RNA targets of KSRP. This provides KSRP with the structural flexibility needed to recognize a set of different targets in the context of their 3'UTR structural settings. Surprisingly, we find that KH4 binds to its target AREs with lower affinity than KH3 and that KSRP's mRNA binding, and mRNA degradation activities are closely associated with a conserved structural element of KH4. 相似文献
970.
Gregorio C Eduardo S Rodrigues LC Regueira MA Fraga R Riveiros R Maestro M Mouriño A 《The Journal of steroid biochemistry and molecular biology》2007,103(3-5):227-230
Hapten derivatives of 25-hydroxyvitamin D(3) and 1alpha,25-dihydroxyvitamin D(3) were synthesized using the Wittig-Horner approach. Both haptens bearing a carboxylic group at the side chain that can be linked to a protein for raising antibodies of potential utility for the determination of 25-hydroxyvitamin D(3), 1alpha,25-dihydroxyvitamin D(3) and 1alpha-hydroxylated vitamin D(3) analogues. 相似文献