1,721,005 research outputs found
The role of proline in Arabidopsis development
No full textDurante il mio dottorato di ricerca, abbiamo dimostrato, attraverso l’alterazione del gene biosintetico della prolina P5CS1, che la modulazione della prolina influenza, in piante di Arabidopsis, la transizione fiorale e la proliferazione delle gemme ascellari. Inoltre abbiamo investigato il ruolo relativo del gene P5CS2, un gene omologo al P5CS1 e abbiamo scoperto un ruolo non ridondante di questi due geni nell’embriogenesi, mentre un ruolo ridondante nella transizione fiorale. Durante l’ultimo anno abbiamo cercato di mettere in relazione la prolina con una o alcune delle diverse vie di segnalazione fiorale. Dati preliminari di RT-PCR relativa e quantitativa hanno rivelato un significativo aumento dei livelli di espressione del gene FLC, suggerendo un interazione della prolina con il pathway autonomo.During my PhD we showed, by the alteration of proline biosynthetic gene P5CS1, that the modulation of proline affects, in Arabidopsis plants, the flower transition and axillary bud proliferation. Morover we investigated the role and the relative contribution in flowering and development of P5CS2, a gene homolog to P5CS1 and we discovered a non redundant role of these two genes in embryo development while a their redundant role in flower transition. In the last year of my PhD thesis we are investigated the floral pathway proline is involved in. Preliminary data, from relative and quantitative RT-PCR, revealed a significative upregulation of the floral integrator gene FLC, strongly suggesting that proline interacts with the autonomous pathway
Proline accumulation in plants: not only stress.
No full textIn addition to its role in protein synthesis and the plant cells' response to environmental stresses, circumstantial evidence suggest that proline may also play a role in flowering and development both as a metabolite and as a signal molecule. Although there is a growing consensus that proline is of special importance throughout the reproductive phase (from flower transition to seed development) a general agreement on the molecular and genetic mechanisms proline is involved in, is yet to be established. In this paper we shall review and critically discuss most of the evidence supporting a role for proline in plant development, paying special attention to the recently reported role of proline in flower transition
Multiple roles of proline in plant stress tolerance and development.
No full textThe recent progresses of the research on proline will be described, focusing on plants and covering proline metabolism and signal transduction as well as the role of this iminoacid in stress response. Furthermore, the recently described developmental role of proline in flowering and reproduction will be illustrated and discussed
Commentary: Elucidating the mechanisms underlying left ventricular function recovery in patients with ischemic heart failure undergoing surgical remodeling: Physiology versus Empiricism
No full textProline is required for male gametophyte development in Arabidopsis
Full text linkAbstract Background In crosses between the proline-deficient mutant homozygous for p5cs1 and heterozygous for p5cs2 (p5cs1 p5cs2/P5CS2), used as male, and different Arabidopsis mutants, used as females, the p5cs2 mutant allele was rarely transmitted to the outcrossed progeny, suggesting that the fertility of the male gametophyte carrying mutations in both P5CS1 and P5CS2 is severely compromised. Results To confirm the fertility defects of pollen from p5cs1 p5cs2/P5CS2 mutants, transmission of mutant alleles through pollen was tested in two ways. First, the number of progeny inheriting a dominant sulfadiazine resistance marker linked to p5cs2 was determined. Second, the number of p5cs2/p5cs2 embryos was determined. A ratio of resistant to susceptible plantlets close to 50%, and the absence of aborted embryos were consistent with the hypothesis that the male gametophyte carrying both p5cs1 and p5cs2 alleles is rarely transmitted to the offspring. In addition, in reciprocal crosses with wild type, about 50% of the p5cs2 mutant alleles were transmitted to the sporophytic generation when p5cs1 p5cs2/P5CS2 was used as a female, while less than 1% of the p5cs2 alleles could be transmitted to the outcrossed progeny when p5cs1 p5cs2/P5CS2 was used as a male. Morphological and functional analysis of mutant pollen revealed a population of small, degenerated, and unviable pollen grains, indicating that the mutant homozygous for p5cs1 and heterozygous for p5cs2 is impaired in pollen development, and suggesting a role for proline in male gametophyte development. Consistent with these findings, we found that pollen from p5cs1 homozygous mutants, display defects similar to, but less pronounced than pollen from p5cs1 p5cs2/P5CS2 mutants. Finally, we show that pollen from p5cs1 p5cs2/P5CS2 plants contains less proline than wild type and that exogenous proline supplied from the beginning of another development can partially complement both morphological and functional pollen defects. Conclusions Our data show that the development of the male gametophyte carrying mutations in both P5CS1 and P5CS2 is severely compromised, and indicate that proline is required for pollen development and transmission.</p
Proline Accumulation in Pollen Grains as Potential Target for Improved Yield Stability Under Salt Stress
Full text linkSeed yield, a major determinant for the commercial success of grain crops, critically depends on pollen viability, which is dramatically reduced by environmental stresses, such as drought, salinity, and extreme temperatures. Salinity, in particular, is a major problem for crop yield known to affect about 20% of all arable land and cause huge economic losses worldwide. Flowering plants are particularly sensitive to environmental stress during sexual reproduction, and even a short exposure to stressing conditions can severely hamper reproductive success, and thus reduce crop yield. Since proline is required for pollen fertility and accumulates in plant tissues in response to different abiotic stresses, a role of proline in pollen protection under salt stress conditions can be envisaged. In this perspective, we analyze old and new data to evaluate the importance of pollen development under saline conditions, and discuss the possibility of raising proline levels in pollen grains as a biotechnological strategy to stabilize seed yield in the presence of salt stress. The overall data confirm that proline is necessary to preserve pollen fertility and limit seed loss under stressful conditions. However, at present, we have not enough data to conclude whether or not raising proline over wildtype levels in pollen grains can effectively ameliorate seed yield under saline conditions, and further work is still required.publishe
Proline modulates root meristem size and root growth in Arabidopsis
No full textBeside its role in protein synthesis, proline plays a special role in plants
both under stress and non-stress conditions. In most plant species this
amino acid accumulates in response to a number of abiotic and biotic
stresses, probably as an adaptive mechanism to improve stress tolerance.
Under non-stress conditions proline accumulates in reproductive organs
and is involved in developmental processes related to reproduction,
such as flowering, pollen development and embryogenesis. Recently
proline has been shown to modulate root meristem size in Arabidopsis
by controlling the ratio between cell division and cell differentiation.
The effects of proline on meristem size are parallel to, and independent
from, hormonal pathways, and do not involve the expression of genes
controlling cell differentiation at the transition zone, such as ARR1,
ARR12 and SHY2. On the contrary, proline appears to control specifically
cell division in early stages of postembryonic root development, as
shown by the expression of the G2/M-specific CYCB1;1 gene. We are
currently investigating the molecular and genetic mechanisms through
which proline exerts its effects on root development
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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