947 resultados para Silent valley microalgae
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This paper presents a gravimetric study (based on 382 gravimetric stations in an area about 32 km2) of a nearly flat basin: the Low Andarax valley. This alluvial basin, close to its river mouth, is located in the extreme south of the province of Almería and coincides with one of the existing depressions in the Betic Cordillera. The paper presents new methodological work to adapt a published inversion approach (GROWTH method) to the case of an alluvial valley (sedimentary stratification, with density increase downward). The adjusted 3D density model reveals several features in the topography of the discontinuity layers between the calcareous basement (2,700 kg/m3) and two sedimentary layers (2,400 and 2,250 kg/m3). We interpret several low density alignments as corresponding to SE faults striking about N140?145°E. Some detected basement elevations (such as the one, previously known by boreholes, in Viator village) are apparently connected with the fault pattern. The outcomes of this work are: (1) new gravimetric data, (2) new methodological options, and (3) the resulting structural conclusions.
Viability of the biochar production from different manure wastes in the Amblés Valley (Ávila, Spain)
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In the last years, intensive animal husbandry production has led to a large concentration of animals in small areas. This has resulted in the production of excessive amounts of manures with insufficient nearby land for application. One of this areas is the Amblés Valley located in the centre of Spain, near to Ávila city, with an extension of 167472 ha of which 88.9% is agricultural land. This valley has an important livestock focused on pig, cattle, chicken production which is associated with the generation of more than 200,000 t/year of manure. There are a number of environmental problems associated with these intensive agricultural systems, including N and P pollution of water bodies, methane emissions and odour pollution. These serious environmental threats are called for innovative environmental management approaches. A feasible technology for the management of manures, offering a potential to valorise these wastes, is pyrolysis, which results in the production of biochar. The objective of this work is evaluated the technical and economic feasibility of the production of biochar in Amblés Valley (Spain).
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Lloyd Gaines was born in Water Valley, Mississippi in 1911. Gaines’ family was sharecroppers outside the small Mississippi town, toiling in the cotton fields which caused Lloyd’s school attendance to be quite sporadic.
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The HML and HMR mating loci of Saccharomyces cerevisiae are bound in silent chromatin, which is assembled at the flanking E and I transcriptional silencers. The retrotransposon Ty5 preferentially integrates into regions of silent chromatin, and Ty5 insertions near the HMR-E silencer account for ≈2% of total transposition events. Most Ty5 insertions occur within 800 bp on either side of the autonomously replicating consensus sequence within HMR-E. Ty5 target preference is determined by silent chromatin, because integration near HMR-E is abolished in strains with silencer mutations that alleviate transcriptional repression. The recognition of specific DNA sequences per se does not direct integration, rather, it is the protein complex assembled at the silencers. As demonstrated here for Ty5, recognition of specific chromatin domains may be a general mechanism by which retrotransposons and retroviruses determine integration sites.
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We report the identification and cloning of a 28-kDa polypeptide (p28) in Tetrahymena macronuclei that shares several features with the well studied heterochromatin-associated protein HP1 from Drosophila. Notably, like HP1, p28 contains both a chromodomain and a chromoshadow domain. p28 also shares features with linker histone H1, and like H1, p28 is multiply phosphorylated, at least in part, by a proline-directed, Cdc2-type kinase. As such, p28 is referred to as Hhp1p (for H1/HP1-like protein). Hhp1p is missing from transcriptionally silent micronuclei but is enriched in heterochromatin-like chromatin bodies that presumably comprise repressed chromatin in macronuclei. These findings shed light on the evolutionary conserved nature of heterochromatin in organisms ranging from ciliates to humans and provide further evidence that HP1-like proteins are not exclusively associated with permanently silent chromosomal domains. Our data support a view that members of this family also associate with repressed states of euchromatin.
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DNA methylation of tumor suppressor genes is a common feature of human cancer. The cyclin-dependent kinase inhibitor gene p16/Ink4A is hypermethylated in a wide range of malignant tissues and the p14/ARF gene located 20 kb upstream on chromosome 9p21 is also methylated in carcinomas. p14/ARF (ARF, alternative reading frame) does not inhibit the activities of cyclins or cyclin-dependent kinase complexes; however, the importance of the two gene products in the etiology of cancer resides in their involvement in two major cell cycle regulatory pathways: p53 and the retinoblastoma protein, Rb, respectively. Distinct first exons driven from separate promoters are spliced onto the common exons 2 and 3 and the resulting proteins are translated in different reading frames. Both genes are expressed in normal cells but can be alternatively or coordinately silenced when their CpG islands are hypermethylated. Herein, we examined the presence of methyl-CpG binding proteins associated with aberrantly methylated promoters, the distribution of acetylated histones H3 and H4 by chromatin immunoprecipitation assays, and the effect of chemical treatment with 5-aza-2′-deoxycytidine (5aza-dC) and trichostatin A on gene induction in colon cell lines by quantitative reverse transcriptase–PCR. We observed that the methyl-CpG binding protein MBD2 is targeted to methylated regulatory regions and excludes the acetylated histones H3 and H4, resulting in a localized inactive chromatin configuration. When methylated, the genes can be induced by 5aza-dC but the combined action of 5aza-dC and trichostatin A results in robust gene expression. Thus, methyl-CpG binding proteins and histone deacetylases appear to cooperate in vivo, with a dominant effect of DNA methylation toward histone acetylation, and repress expression of tumor suppressor genes hypermethylated in cancers.
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Mass-spectrometric disequilibrium analysis was applied to investigate CO2 uptake and HCO3− transport in cells and chloroplasts of the microalgae Dunaliella tertiolecta and Chlamydomonas reinhardtii, which were grown in air enriched with 5% (v/v) CO2 (high-Ci cells) or in ambient air (low-Ci cells). High- and low-Ci cells of both species had the capacity to transport CO2 and HCO3−, with maximum rates being largely unaffected by the growth conditions. In high- and low-Ci cells of D. tertiolecta, HCO3− was the dominant inorganic C species taken up, whereas HCO3− and CO2 were used at similar rates by C. reinhardtii. The apparent affinities of HCO3− transport and CO2 uptake increased 3- to 9-fold in both species upon acclimation to air. Photosynthetically active chloroplasts isolated from both species were able to transport CO2 and HCO3−. For chloroplasts from C. reinhardtii, the concentrations of HCO3− and CO2 required for half-maximal activity declined from 446 to 33 μm and 6.8 to 0.6 μm, respectively, after acclimation of the parent cells to air; the corresponding values for chloroplasts from D. tertiolecta decreased from 203 to 58 μm and 5.8 to 0.5 μm, respectively. These results indicate the presence of inducible high-affinity HCO3− and CO2 transporters at the chloroplast envelope membrane.
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Background. The extraction of salt from seawater by means of coastal solar salterns is a very well-described process. Moreover, the characterization of these environments from ecological, biochemical and microbiological perspectives has become a key focus for many research groups all over the world over the last 20 years. In countries such as Spain, there are several examples of coastal solar salterns (mainly on the Mediterranean coast) and inland solar salterns, from which sodium chloride is obtained for human consumption. However, studies focused on the characterization of inland solar salterns are scarce and both the archaeal diversity and the plant communities inhabiting these environments remain poorly described. Results. Two of the inland solar salterns (termed Redonda and Penalva), located in the Alto Vinalopó Valley (Alicante, Spain), were characterized regarding their geological and physico-chemical characteristics and their archaeal and botanical biodiversity. A preliminary eukaryotic diversity survey was also performed using saline water. The chemical characterization of the brine has revealed that the salted groundwater extracted to fill these inland solar salterns is thalassohaline. The plant communities living in this environment are dominated by Sarcocornia fruticosa (L.) A.J. Scott, Arthrocnemum macrostachyum (Moris) K. Koch, Suaeda vera Forsk. ex Gmelin (Amaranthaceae) and several species of Limonium (Mill) and Tamarix (L). Archaeal diversity was analyzed and compared by polymerase chain reaction (PCR)-based molecular phylogenetic techniques. Most of the sequences recovered from environmental DNA samples are affiliated with haloarchaeal genera such as Haloarcula, Halorubrum, Haloquadratum and Halobacterium, and with an unclassified member of the Halobacteriaceae. The eukaryote Dunaliella was also present in the samples. Conclusions. To our knowledge, this study constitutes the first analysis centered on inland solar salterns located in the southeastern region of Spain. The results obtained revealed that the salt deposits of this region have marine origins. Plant communities typical of salt marshes are present in this ecosystem and members of the Halobacteriaceae family can be easily detected in the microbial populations of these habitats. Possible origins of the haloarchaea detected in this study are discussed.
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Microalgae are very effective microorganisms for CO2 capturing and a promising source of lipids for biodiesel as well as other interesting compounds. Many different ways of exploitation of these organisms are being tested. This work presents a review of the state of the art of the research and development of thermochemical conversion of microalgae with a special focus on pyrolysis and hydrothermal liquefaction. Aspects related to the type of reactors, the products obtained and the analytical applications are covered. The actual reaction scheme of pyrolysis of microalgae is extremely complex because of the formation of over hundreds of intermediate products. Various kinetic models reported in the literature and in a previous study with experimental validations are presented in this review to provide the current status of the study.
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New archaeological survey data are combined with previous evidence to examine the rural landscape during the Iberian Iron Age in the Valencia region of eastern Spain. One goal was to understand the settlement pattern and agricultural intensification through manuring. The second objective was to address the socioeconomic aspects of changes in the landscape. It is possible to trace the emergence of a hierarchical settlement pattern in the Iberian Iron Age in which large fortified settlements carried out the most important functions of control and exploitation of the territory, extending their authority over small rural villages and farmsteads. This pattern is associated with the complex socioeconomic structures and political organization of early Iberian states.
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n.s. no.16(1991)
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n.s. no.34(2003)