122 research outputs found
Recollements of Module Categories
We establish a correspondence between recollements of abelian categories up
to equivalence and certain TTF-triples. For a module category we show,
moreover, a correspondence with idempotent ideals, recovering a theorem of
Jans. Furthermore, we show that a recollement whose terms are module categories
is equivalent to one induced by an idempotent element, thus answering a
question by Kuhn.Comment: Comments are welcom
Study of O-Phosphorylation Sites in Proteins Involved in Photosynthesis-Related Processes in Synechocystis sp Strain PCC 6803: Application of the SRM Approach
O-Phosphorylation has been shown in photosynthesis related proteins in a cyanobacterium Synechocystis sp. strain PCC 6803 (thereafter Synechocystis 6803), suggesting that phosphorylation of S, T, and Y residues might be important in photosynthesis-related processes. Investigation of biological roles of these phosphorylation events requires confident knowledge of the phosphorylated sites and prospects for their individual assessment. We performed phosphoproteomic analysis of Synechocystis 6803 using TiO2 enrichment of the phosphopeptides, followed by LC-MS/MS, and discovered 367 phosphorylation sites in 190 proteins participating in various cellular functions. Furthermore, we focused on the large group of phosphoproteins that are involved in light harvesting, photosynthesis driven electron flow, photoprotection, and CO2 fixation. The SRM approach was applied to verify/improve assignments of phosphorylation sites in these proteins and to investigate possibilities for analysis of phosphopeptide isomers. The SRM assays were designed for peptides comprising 45 phosphorylation sites. The assays contain peptide iRT values and Q1/Q3 transitions comprising those discriminating between phosphopeptide isoforms. The majority of investigated phosphopeptides and phosphorylated isoforms could be individually assessed with the SRM technique. The assays could be potentially used in future quantitative studies to evaluate an extent of phosphorylation in photosynthesis related proteins in Synechocystis 6803 cells challenged with various environmental stresses
Corrosione delle armature in calcestruzzo armato allo stadio G. Meazza di Milano - Il monitoraggio delle strutture del primo e del secondo anello
The structures of the three rings of the stadium "Giuseppe Meazza" in Milan, built in different stages from 1926 until 1990, is a remarkable evidence of the use of reinforced and prestressed concrete in the last century. If, on the one hand, these structures represent an icon for the potential of this material, on the other hand they also highlight its vulnerability. Reinforced concrete structures of the first and second rings are more than 60 years old and suffer from the effects of corrosion of the steel reinforcement. The municipality of Milan, being the owner of the stadium, has set up a collaboration with Politecnico di Milano aimed at the assessment of the conservation condition of the structures and planning of remedial works necessary to preserve and, at the same time, ensure the correct use of this important infrastructure. This paper describes the investigations carried out on the structures of the first and second ring (dating to 1926-37 and 1955 respectively), which allowed the definition of the extension of carbonation of concrete and the state of corrosion of the reinforcement. The opportunity to monitor the progress of the reinforcement corrosion was also highlighted in order to plan repair works. For this purpose, a monitoring system based on probes for measuring the corrosion potential of the reinforcement and electrical resistivity of concrete is under development
ABaCo: Assessment Battery for Communication
\ud
Human communication is\ud
one of the most complex social\ud
activity: it is a process of meaning\ud
construction which cooperatively\ud
involves all participants taking\ud
part in the interaction. Various\ud
clinical conditions may lead to\ud
impairments of communicative\ud
abilities: developmental disorders\ud
(e.g., autism, specific language\ud
impairment, Down syndrome),\ud
brain pathologies (e.g., closed\ud
head injury, right hemisphere\ud
damage, aphasia), psychiatric disorders\ud
(schizophrenia), disorders\ud
of old age (e.g. dementia). The\ud
assessment of a patient’s abilities\ud
and disabilities is the crucial starting\ud
point for planning an efficient\ud
rehabilitation path, where\ud
residual capacities are strengthen\ud
and, whenever possible, impaired\ud
components are restored. However,\ud
while the phonological,\ud
syntactic and semantic components\ud
of language can be assessed\ud
by numerous tests, instruments\ud
for the evaluation of pragmatic\ud
aspects of communication are\ud
scarce (see Sacco et al., 2008 for a\ud
more detailed analysis of the existing\ud
instruments for the assessment\ud
of communication).\ud
The Assessment Battery for\ud
Communication (ABaCo) has\ud
been created to be a theoretically\ud
grounded, wide-range clinical\ud
instrument. Its theoretical bases\ud
stem from Cognitive Pragmatics\ud
theory (Airenti, Bara & Colombetti,\ud
1993; Bara, 2010), a theory of\ud
the cognitive processes underlying\ud
human communicative exchanges,\ud
framed within the inferential\ud
model of communication (Grice,\ud
1975) and the speech acts perspective\ud
(Austin, 1962; Searle, 1969).\ud
The theory has been shown to\ud
be able to make predictions on\ud
typically developing children (Bucciarelli,\ud
Colle & Bara, 2003; Bosco,\ud
Bucciarelli & Bara, 2004; 2006;\ud
Bosco & Buciarelli, 2008; Bosco,\ud
Vallana & Bucciarelli, 2012), atypically\ud
developing children (Bara,\ud
Bosco & Bucciarelli, 1999; Bara,\ud
Bucciarelli & Colle, 2001; De\ud
Marco, Colle & Bucciarelli, 2007),\ud
patients with traumatic brain injury\ud
(Bara, Tirassa & Zettin, 1997;\ud
Bara, Cutica & Tirassa, 2001; Angeleri\ud
et al., 2008), patients with right\ud
and left focal brain lesions (Cutica,\ud
Bucciarelli & Bara, 2006), patients\ud
with Alzheimer’s disease (Bara,\ud
Bucciarelli & Geminiani, 2000)\ud
and patients with schizophrenia\ud
(Bosco, Bono & Bara, 2012). In\ud
this view, communication is the\ud
ability to comprehend and produce\ud
linguistic and extralinguistic\ud
communication acts, accompanied\ud
by suitable paralinguistic features,\ud
appropriate with respect to discourse\ud
and social norms, and fluently\ud
integrated within the conversation.\ud
The ABaCo assesses each of\ud
these components, encompassing\ud
the major aspects involved in communication.\ud
In this paper, we will\ud
briefly describe the features of the\ud
battery, and summarize its psychometric\ud
properties, providing some\ud
suggestions for clinical application
Evolutionary conservation and post-translational control of S-adenosyl-L-homocysteine hydrolase in land plants
Trans-methylation reactions are intrinsic to cellular metabolism in all living organisms. In land plants, a range of substrate-specific methyltransferases catalyze the methylation of DNA, RNA, proteins, cell wall components and numerous species-specific metabolites, thereby providing means for growth and acclimation in various terrestrial habitats. Trans-methylation reactions consume vast amounts of S-adenosyl-L-methionine (SAM) as a methyl donor in several cellular compartments. The inhibitory reaction by-product, S-adenosyl-L-homocysteine (SAH), is continuously removed by SAH hydrolase (SAHH), which essentially maintains trans-methylation reactions in all living cells. Here we report on the evolutionary conservation and post-translational control of SAHH in land plants. We provide evidence suggesting that SAHH forms oligomeric protein complexes in phylogenetically divergent land plants and that the predominant protein complex is composed by a tetramer of the enzyme. Analysis of light-stress-induced adjustments of SAHH inArabidopsis thalianaandPhyscomitrella patensfurther suggests that regulatory actions may take place on the levels of protein complex formation and phosphorylation of this metabolically central enzyme. Collectively, these data suggest that plant adaptation to terrestrial environments involved evolution of regulatory mechanisms that adjust the trans-methylation machinery in response to environmental cues
In the lycophyte Selaginella martensii is the "extra-qT" related to energy spillover? Insights into photoprotection in ancestral vascular plants
Lycophytes are early diverging vascular plants, representing a minor
group as compared to the dominating euphyllophytes, mostly angiosperms.
Having maximally developed in a CO2-rich atmosphere, extant
lycophytes are characterized by a low carbon fixing capacity, which is
compensated by a marked ability to induce the non-photochemical
quenching of chlorophyll fluorescence (NPQ). Different kinetic
components contribute to NPQ, in particular the fast relaxing
high-energy quenching qE, the middle relaxing qT, and the slowly
relaxing qI. Unlike angiosperms, lycophytes enhance the qT component
under high light, originating from an "extra-qT". In this research, we
analyze whether in Selaginella martensii the extra-qT can reflect a
photosystem (PS) I-based quenching mechanism activated upon saturation
of qE capacity. From comparative analyses of fluorescence quenching
parameters, carbon fixation, in vivo low- and room-temperature
fluorescence spectroscopy, and thylakoid protein phosphorylation, it is
proposed that the extra-qT is not mechanistically separate from the
ordinary qT. The results suggest a relationship between qT and
photoprotective energy spillover to PSI, which is activated upon sensing
the excitation energy pressure inside PSII and is possibly facilitated
by phosphorylation of Lhcb6, a minor antenna protein of PSII. Energy
spillover emphasizes 77K fluorescence emission from PSI core (F714) and
becomes more relevant at irradiance levels corresponding to the CO2-limited,
potentially photoinhibiting phase of photosynthesis. At the highest
irradiances, when Lhcb6 phosphorylation potential has been saturated,
the major LHCII increases in turn its phosphorylation level, probably
leading to the full exploitation of PSI as a safe excitation sink. It is
suggested that the low photosynthetic capacity of lycophytes could
allow an easier experimental access to the use of PSI as a safe
excitation quencher for PSII, a debated, emerging issue about thylakoid
photoprotection in angiosperms.</p
Ambient and substrate energy influence decomposer diversity differentially across trophic levels
The species-energy hypothesis predicts increasing biodiversity with increasing energy in ecosystems. Proxies for energy availability are often grouped into ambient energy (i.e., solar radiation) and substrate energy (i.e., non-structural carbohydrates or nutritional content). The relative importance of substrate energy is thought to decrease with increasing trophic level from primary consumers to predators, with reciprocal effects of ambient energy. Yet, empirical tests are lacking. We compiled data on 332,557 deadwood-inhabiting beetles of 901 species reared from wood of 49 tree species across Europe. Using host-phylogeny-controlled models, we show that the relative importance of substrate energy versus ambient energy decreases with increasing trophic levels: the diversity of zoophagous and mycetophagous beetles was determined by ambient energy, while non-structural carbohydrate content in woody tissues determined that of xylophagous beetles. Our study thus overall supports the species-energy hypothesis and specifies that the relative importance of ambient temperature increases with increasing trophic level with opposite effects for substrate energy
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