1,720,981 research outputs found
Comparison of changes in root transcriptome of two maize inbred lines in response to nitrate treatment
No full textLo5 line responded to NO3
-‐ treatment (induction) faster than T250 line at each concentration assayed. Even if
the two inbred lines reached highest induction at different times (2 h for 500 μM and 4 h for 200 μM for Lo5 and 8
h for 500 μM and 12 h for 200 μM for T250), they showed similar values of NO3
-‐ uptake rate. On the basis of this
different behaviour, roots were sampled at different times (1, 2 and 4 h for Lo5 and 5, 11 and 12 h for T250) after
NO3
-‐ treatment (200 μM) in order to perform a “genome-‐wide” transcriptional characterization. Data analysis of
microarray experiments, performed with a chip that allows monitoring the expression of about 60000 maize
transcripts, showed that roots of Lo5 and T250 inbred lines responded to different periods of NO3
-‐ contact through
a modulation of a different number of transcripts. Changes in root Lo5 transcriptome involved a higher number of
transcripts (about 5000 at 2 h) relative to T250 (about 1900 at 12 h). After the peak, transcripts modulated by the
treatment in Lo5 decreased, with the behaviour different from T250 where the number increased linearly up to 12
h. In addition, NO3
-‐ treatment affected the Lo5 and T250 Gene Ontology (GO) terms in a different way. PAGE
analysis performed in Lo5 suggests that processes related to protein modifications (i.e. protein phosphorylation)
and translation were positively affected at 1 h and 4 h, passing through a negative phase of regulation at 2 h. On
the contrary, “protein metabolic process” terms were down-‐regulated at all sampling time points in T250 relative
to Lo5 and only in T250 was a positive modulation of transcripts related to nitrogen metabolism (“nitrogen
compound of metabolic process”) recorded at 5 and 11 h. Furthermore, in the two lines only about 400 transcripts
were modulated in common in response to NO3
-‐
Sulphur deprivation limits Fe-deficiency responses in tomato plants
No full textThe aim of this work was to clarify the role of S supply in the development of the response to Fe depletion in Strategy I plants. In S-sufficient plants, Fe-deficiency caused an increase in the Fe(III)-chelate reductase activity, 59Fe uptake rate and ethylene production at root level. This response was associated with increased expression of LeFRO1 [Fe(III)-chelate reductase] and LeIRT1 (Fe2+ transporter) genes. Instead, when S-deficient plants were transferred to a Fe-free solution, no induction of Fe(III)-chelate reductase activity and ethylene production was observed. The same held true for LeFRO1 gene expression, while the increase in 59Fe2+ uptake rate and LeIRT1 gene over-expression were limited. Sulphur deficiency caused a decrease in total sulphur and thiol content; a concomitant increase in 35SO4 2- uptake rate was observed, this behaviour being particularly evident in Fe-deficient plants. Sulphur deficiency also virtually abolished expression of the nicotianamine synthase gene (LeNAS), independently of the Fe growth conditions. Sulphur deficiency alone also caused a decrease in Fe content in tomato leaves and an increase in root ethylene production; however, these events were not associated with either increased Fe(III)-chelate reductase activity, higher rates of 59Fe uptake or over-expression of either LeFRO1 or LeIRT1 genes. Results show that S deficiency could limit the capacity of tomato plants to cope with Fe-shortage by preventing the induction of the Fe(III)-chelate reductase and limiting the activity and expression of the Fe2+ transporter. Furthermore, the results support the idea that ethylene alone cannot trigger specific Fe-deficiency physiological responses in a Strategy I plant, such as tomato. © 2009 Springer-Verlag
Sulphur deprivation limits Fe-deficiency responses in tomato plants
No full textThe aim of this work was to clarify the role of S supply in the development of the response to Fe depletion in Strategy I plants. In S-sufficient plants, Fe-deficiency caused an increase in the Fe(III)-chelate reductase activity, (59)Fe uptake rate and ethylene production at root level. This response was associated with increased expression of LeFRO1 [Fe(III)-chelate reductase] and LeIRT1 (Fe(2+) transporter) genes. Instead, when S-deficient plants were transferred to a Fe-free solution, no induction of Fe(III)-chelate reductase activity and ethylene production was observed. The same held true for LeFRO1 gene expression, while the increase in (59)Fe(2+) uptake rate and LeIRT1 gene over-expression were limited. Sulphur deficiency caused a decrease in total sulphur and thiol content; a concomitant increase in (35)SO(4) (2-) uptake rate was observed, this behaviour being particularly evident in Fe-deficient plants. Sulphur deficiency also virtually abolished expression of the nicotianamine synthase gene (LeNAS), independently of the Fe growth conditions. Sulphur deficiency alone also caused a decrease in Fe content in tomato leaves and an increase in root ethylene production; however, these events were not associated with either increased Fe(III)-chelate reductase activity, higher rates of (59)Fe uptake or over-expression of either LeFRO1 or LeIRT1 genes. Results show that S deficiency could limit the capacity of tomato plants to cope with Fe-shortage by preventing the induction of the Fe(III)-chelate reductase and limiting the activity and expression of the Fe(2+) transporter. Furthermore, the results support the idea that ethylene alone cannot trigger specific Fe-deficiency physiological responses in a Strategy I plant, such as tomato
Influenza della nutrizione solfatica sulla risposta alla Fe-carenza in piante di pomodoro
No full text
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
Response of barley plants to Fe deficiency and Cd contamination as affected by S starvation
No full textBoth Fe deficiency and Cd exposure induce rapid changes in the S nutritional requirement of plants. The aim of this
work was to characterize the strategies adopted by plants to cope with both Fe deficiency (release of
phytosiderophores) and Cd contamination [production of glutathione (GSH) and phytochelatins] when grown under
conditions of limited S supply. Experiments were performed in hydroponics, using barley plants grown under S
sufficiency (1.2 mM sulphate) and S deficiency (0 mM sulphate), with or without FeIII-EDTA at 0.08 mM for 11 d and
subsequently exposed to 0.05 mM Cd for 24 h or 72 h. In S-sufficient plants, Fe deficiency enhanced both root and
shoot Cd concentrations and increased GSH and phytochelatin levels. In S-deficient plants, Fe starvation caused
a slight increase in Cd concentration, but this change was accompanied neither by an increase in GSH nor by an
accumulation of phytochelatins. Release of phytosiderophores, only detectable in Fe-deficient plants, was strongly
decreased by S deficiency and further reduced after Cd treatment. In roots Cd exposure increased the expression of
the high affinity sulphate transporter gene (HvST1) regardless of the S supply, and the expression of the Fe
deficiency-responsive genes, HvYS1 and HvIDS2, irrespective of Fe supply. In conclusion, adequate S availability is
necessary to cope with Fe deficiency and Cd toxicity in barley plants. Moreover, it appears that in Fe-deficient plants
grown in the presence of Cd with limited S supply, sulphur may be preferentially employed in the pathway for
biosynthesis of phytosiderophores, rather than for phytochelatin production
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
- …
