1,721,214 research outputs found
Characterization of AtMYB59 transcription factor
No full textanalysis of a transcription factor induced by cadmium and affecting plant developmen
The maize PIN gene family of auxin transporters
Full text linkAuxin is a key regulator of plant development and its differential distribution in plant tissues, established by a polar cell to cell transport, can trigger a wide range of developmental processes. A few members of the two families of auxin efflux transport proteins, PIN-formed (PIN and P-glycoprotein (ABCB/PGP, have so far been characterized in maize. Nine new Zea mays auxin efflux carriers PIN family members and two maize PIN-like genes have now been identified. Four members of PIN1 (named ZmPIN1a-d cluster, one gene homologous to AtPIN2 (ZmPIN2, three orthologs of PIN5 (ZmPIN5a-c, one gene paired with AtPIN8 (ZmPIN8, and three monocot-specific PINs (ZmPIN9, ZmPIN10a, and ZmPIN10b were cloned and the phylogenetic relationships between early-land plants, monocots, and eudicots PIN proteins investigated, including the new maize PIN proteins. Tissue-specific expression patterns of the 12 maize PIN genes, 2 PIN-like genes and ZmABCB1, an ABCB auxin efflux carrier, were analyzed together with protein localization and auxin accumulation patterns in normal conditions and in response to drug applications. ZmPIN gene transcripts have overlapping expression domains in the root apex, during male and female inflorescence differentiation and kernel development. However, some PIN family members have specific tissue localization: ZmPIN1d transcript marks the L1 layer of the shoot apical meristem and inflorescence meristem during the flowering transition and the monocot-specific ZmPIN9 is expressed in the root endodermis and pericycle. The phylogenetic and gene structure analyses together with the expression pattern of the ZmPIN gene family indicate that subfunctionalization of some maize PINs can be associated to the differentiation and development of monocot-specific organs and tissues and might have occurred after the divergence between dicots and monocots. © 2012 Forestan, Farinati and Varotto
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
In vitro buffering properties of 3 composite resins
No full textAIM:
A dental composite resin, Ariston pHc, has been described as having a cariostatic effect by buffering acid saliva and preventing decalcification and infiltration of restorations. The buffering effect has been reported due to the release of OH- originated from the alkaline glass embedded in the resin. The release would occur only in the presence of low salivary pH values. The aim of this in vitro investigation was to evaluate pH variations induced by Ariston pHc and 2 other composite resins (P60 and Z100).
METHODS:
Eighteen samples were prepared for each composite and 5 specimens of each brand were embedded in artificial saliva according to Brugirar and Mazille, at 3 different pH values. A 1(st) group of 5 specimens of each tested resin was immersed in neutral artificial saliva at pH 7.7, a 2(nd) group in acidified artificial saliva at pH 5.45 and a 3(rd) group in alkalised saliva at pH 9.25. Three other samples of each resin were immersed in tubes containing distilled water at pH 7.23 and served as controls. Twelve tubes were filled only with neutral, alkalised and acidified artificial saliva and distilled water at the above mentioned pH values. Measurements of pH modifications were taken after 1, 3, 9, 14, 31 days. RESULTS. Ariston pHc raised the pH of distilled water up to 9.59 after 1 day, and to 8.42 after 31 days. This pH modification shown by Ariston pHc in distilled water, compared to those of the other 2 composites were statistically highly significant, with p<0.001, while the pH variations of saliva containing the 3 resins were negligible, except for acidified saliva with Ariston pHc, where a slight pH enhancement with some statistical significance (p=0.04) was found. However, acidified saliva without any resin embedded was found to shift to neutrality as well.
CONCLUSION:
These results strongly suggest that none of the 3 tested materials can achieve an effective buffering action in vitro on low salivary pH values. However, the ability of Ariston pHc to raise the pH in distilled water, and to a lesser degree in acidified saliva, suggests that an in vivo buffering effect cannot be excluded
Current perspectives on the hormonal control of seed development in Arabidopsis and maize: a focus on auxin
Full text linkThe seed represents the unit of reproduction of flowering plants, capable of developing into another plant, and to ensure the survival of the species under unfavorable environmental conditions. It is composed of three compartments: seed coat, endosperm and embryo. Proper seed development depends on the coordination of the processes that lead to seed compartments differentiation, development and maturation. The coordination of these processes is based on the constant transmission/perception of signals by the three compartments. Phytohormones constitute one of these signals; gradients of hormones are generated in the different seed compartments, and their ratios comprise the signals that induce/inhibit particular processes in seed development. Among the hormones, auxin seems to exert a central role, as it is the only one in maintaining high levels of accumulation from fertilization to seed maturation. The gradient of auxin generated by its PIN carriers affects several processes of seed development, including pattern formation, cell division and expansion. Despite the high degree of conservation in the regulatory mechanisms that lead to seed development within the Spermatophytes, remarkable differences exist during seed maturation between Monocots and Eudicots species. For instance, in Monocots the endosperm persists until maturation, and constitutes an important compartment for nutrients storage, while in Eudicots it is reduced to a single cell layer, as the expanding embryo gradually replaces it during the maturation. This review provides an overview of the current knowledge on hormonal control of seed development, by considering the data available in two model plants: Arabidopsis thaliana, for Eudicots and Zea mays L., for Monocots. We will emphasize the control exerted by auxin on the correct progress of seed development comparing, when possible, the two species. © 2014 Locascio, Roig-Villanova, Bernardi and Varotto
Biodiversity of local Italian grapevine cultivars detected by SSR markers
No full textGrapevine cultivation is an age-old tradition in the Veneto region of Italy where many ancient cultivars are still grown. Some of these cultivars are recognised as producing important Controlled Designations of Origin (D.O.C.) wines, while other local types have been lost through substitution by international cultivars. Despite the large number of ancient cultivars present in the Veneto region, many are not registered in the Italian Ampelographic Catalogue and therefore risk extinction. Moreover, synonyms and homonyms have often become popular at the local level, thus rendering correct varietal identification tricky. Our aim was to characterize ancient local cultivars to preserve the germoplasm and investigate their genetic relationships. Genetic variability was assessed in 18 local varieties using nuclear simple sequence repeat (SSR) markers to identify the most similar groups and verify if these groupings are in agreement with the known history of the cultivars
UNDERSTANDING EPIALLELES FORMATION IN RESPONSE TO ENVIRONMENTAL CUES AND THEIR HERITABILITY IN PLANTS
No full textEpigenetics is defined as the study of heritable
traits that do not depend on the primary DNA sequence.
The discovery of epigenetic mechanisms acting
on chromatin to regulate global gene expression has revealed
how heritable variation need not be sequencebased.
Particularly, environmental factors can induce novel
variation through the activation of specific epigenetic
mechanisms that determine mutations of spatial and temporal
pattern of gene expression. The carriers of epigenetic
information are identified in DNA methylation, histone
tails post-translation modifications and histone variants.
Specific combinations of these marks can influence
chromatin structure that in turn affects transcription and
genome stability. The environment can induce various
types of epigenetic changes leading to alternative gene
expression patterns, which can either be restricted to somatic
and vegetative tissues or propagated through mitotic
cell divisions. Of particular interest is the distinction between
transient and stable changes in epigenetic marks
and the formation and maintenance of epialles. Epigenetic
alleles or epialleles show different distribution of epigenetic
marks in their sequence and can exhibit distinct
phenotypes. The search for natural occurring epialles and
the understanding of the mechanisms leading to their formation
and maintenance, particularly in response to environmental
cues, is a great challenge for the future
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