1,721,124 research outputs found
Study of the role of the DOF transcription factor DAG1 in the control of seedling development in Arabidopsis thaliana
Full text linkSeedling development relies on environmental conditions; indeed, once seeds have germinated, they undergo photomorphogenesis or skotomorphogenesis, depending on the presence or absence of light. Photomorphogenesis is a multi-traits process characterised by inhibition of hypocotyl elongation, open and expanded cotyledons, and chloroplast development, whereas skotomorphogenesis is characterised by long hypocotyls and small unfolded cotyledons. Hypocotyl elongation is influenced by both environmental and hormonal cues and it has been extensively studied as a model for cell expansion. Nevertheless, the molecular network underlying this process is not yet fully elucidated.
The Arabidopsis Dof protein DAG1 (Dof Affecting Germination1) is a repressor of seed germination, and a key player of the seed-to seedling transition, a crucial developmental phase positively controlled by light, as well as by the phytohormones ABA (abscissic acid) and GA (gibberellins). Indeed, DAG1 controls the ratio of ABA and GA, which play opposite roles, as ABA represses germination whereas GAs promote it.
We have previously shown that inactivation of DAG1 affects inhibition of hypocotyl elongation. Indeed, light-grown dag1 mutant seedlings show significant shorter hypocotyls compared to the wild-type, suggesting that DAG1 is a negative component of this light-mediated process. To gain some insight into the molecular network in which DAG1 is involved, we have analysed the transcriptome profile of both dag1 and wild-type hypocotyls and seedlings. We have identified more than 250 genes that are differentially expressed in dag1 hypocotyls, and the analysis of this data suggests that DAG1 is mainly involved in promoting hypocotyl elongation. In addition, a number of the DE genes identified are correlated to the
response to ABA stimulus. ABA plays a role in inhibition of hypocotyl elongation, although the molecular mechanism remains unclear.
Therefore, we investigated the effect of ABA on hypocotyl development, and our results showed that ABA negatively controls cell expansion in hypocotyls, by acting on GA metabolism, and repressing auxin biosynthesis. Consistently, addition of exogenous ABA can revert the hypocotyl phenotype of dag1 mutant seedlings.
In conclusion, our results prove that DAG1 is likely to be an element of a molecular network which controls cell expansion by modulating hormonal response, namely auxin, ABA and GAs
Ferritin nanocages for theranostic applications
Full text linkFerritin is a ubiquitous protein involved in iron storage composed of 24 subunits assembled in a hollow spherical nano-cage architecture. Channels formed between the intersection of peptide subunits are lined with polar aminoacids and allow for the entry and exit of cations. Ferritin can be successfully used as an highly biocompatible nanocarrier, due to the ability of being recognized and uptaken by TfR-1 overexpressing tumour cells. Furthermore, both inner or outer surface can be easily functionalized conferring multiple functionalities onto a single molecule. For these reasons, ferritins are emerging as novel biotech platforms for biomedical applications (both diagnostical and therapeutic) due to their ability to encapsulate cargo molecules, broad functionalization possibilities and selective targeting properties.
In this framework, the present work has been focused on the development and characterization of engineered recombinant mammalian and archaeal ferritin constructs to expand the scope of their nanotechnological applications.
With the aim of investigating the biological and biophysical properties of prokaryotic homopolymers and characterizing the permeability of the prokaryotic protein shell toward diffusants, two ferritins from Archaea have been chosen as model. A set of engineered mutants of Pyrococcus furiosus ferritin (Pf-Ft) and Archaeoglobus fulgidus ferritin (Af-Ft) have been obtained by placing a reactive cysteine residue per subunit in the same topological positions either inside or outside the internal cavity. These mutants differ from each other by the aminoacid composition of ferritin channels and the related “open” versus “closed” ferritin architecture. The molecular diffusion through the ferritin cavity has been characterized by studying within these mutants the cysteine reactivity toward the bulky and negatively charged DTNB molecule (5,5'-dithiobis-2-nitrobenzoic acid).
Moreover, Archaeoglobus fulgidus ferritin has been genetically engineered by changing the surface exposed loop connecting helices B and C to mimic the sequence of the analogous human H-chain ferritin loop. This novel “humanized” chimeric construct (named HumAf-Ft) thus combines the unique open structure and self-assembly properties of Af-Ft with the typical humanH-ferritin ability to bind the Transferrin Receptor TfR-1, which is overexpressed in several types of tumor cells. HumAfFt has been structurally and biophysically characterized and the improved cellular uptake has been demonstrated on HeLa cell line.
Lastly, to exploit lanthanide fluorescence properties and develop an intrinsically fluorescent nanoparticle, a novel construct has been developed by genetically fusing at the C-terminal end of mouse H-ferritin a lanthanide binding tag (LBT). LBTs are short peptides that selectively bind lanthanide ions at low-nanomolar affinities and, due to the presence of a tryptophan residue, provide strong FRET sensitization. This novel construct (named HFt-LBT) has been designed by locating the tag inside the inner cavity, so that the lanthanide ions diffusing through the surface pores can eventually bind to the LBT sequence. HFt-LBT would thus act both as carrier targeted to TfR-1 receptor and as a FRET sensitizer. Fluorescence improvement and lanthanide binding properties have been investigated by spectrophotometric measurements using Tb+3 as lanthanide probe. The structural characterization has been carried out and cellular uptake by HeLa cell line has been assessed as well
Insulin-sperm interaction: effects on plasma membrane and binding to acrosome
No full textIn in vitro studies, viable, intact human spermatozoa took up free radioinsulin with an apparently non-receptor-mediated mechanism. However, when a colloidal gold-insulin complex was substituted for the radiotracer, no surface binding was visualized at the ultrastructural level. Upon sperm incubation in the presence of free insulin, a dose-dependent release of phospholipid phosphorus occurred, with a concomitant derangement of head cell membrane. After head membrane removal, spermatozoa-bound radioinsulin in a time- and concentration-dependent manner, the binding was displaceable by unlabeled insulin, and an exclusive localization of the colloidal gold-insulin complex was visualized at the acrosome level. On the basis of this evidence, both the plasma membrane and the acrosome seem to represent cytological targets for insulin
A case of complete albinism in Lissotriton vulgaris meridionalis
Full text linkNew case of albinism in a Lisootriton vulgaris. The first record for L. vulgaris. meridionalis
Rediscovered presences: women as builders in the building sites of Rome and Latium between 16th and 18th century
No full textThe presence of women in Roman and Latium building sites in the modern age was not episodic. Yet, for a long time, gender identity prevailed over labour identity, and activities related to the construction of architecture were long considered the exclusive prerogative of men. On the contrary, construction sites have welcomed many female workers, employed in different, even heavy, roles. They deserve redemption from a persistent prejudice, which has erased their memory. An important contribution has come from the research conducted by the author in collaboration with the Archives of the Fabbrica of St. Peter’s in the Vatican, where one would never have imagined finding women permanently employed in the roles of the building site. As documented in notarial deeds relating to the production and trade of bricks and other similar activities in the Papal States, female employment also affected the entrepreneurial sphere of construction. The building trade in the Modern Age is therefore configured as a multiform reality, in which custom and necessity concurred to emancipate the female condition, overcoming the historical prejudice of the preclusion of certain jobs to women. The distinction was much less defined than is commonly believed, despite the persistent exclusion of women from trade guilds. Between the 16th and 18th centuries, a large sector of women's employment in the Papal States consisted of the building industry and related activities.
The various roles assigned to women are documented both in the Fabbrica of St. Peter’s and in numerous private construction sites in Rome and the provincial fiefdoms. The tasks performed by women carters, transporters, and bricklayers are surprising not only for the substantial equality of pay compared to men, but also for the strength and determination shown by these exceptional women. The same equality is found in the relations between the Fabbrica of St. Peter’s and the suppliers of building materials, among whom the 'carter women' stood out for their entrepreneurial skills. If evidence of the presence of women bricklayers in St. Peter's building site is rare, it is instead widely documented in other building sites of the 17th century, from Abruzzo to the noble fiefdoms of Lazio. Here, the work of several female bricklayers is documented until the 18th century. An example are the building sites in Palestrina, a fief of the Barberini family, where several 'masonry women', 'spicconatrici' (breakers with a pickaxe) and 'garzone' (apprentices) worked. For instance, several women were active in the building sites of the monastery of Sant'Andrea (18th cent.) and the church of Santa Rosalia (17th cent.). This essay reconstructs the activities and roles of these strong-willed women in order to bring to light their history, memory and professional dignity, now forgotte
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
Reduced expression of thyroid hormone receptors and beta-adrenergic receptors in human failing cardiomyocytes.
Full text linkAn altered thyroid hormone profile has been reported in patients with congestive heart failure. However, information regarding the status of thyroid hormone receptors in human failing cardiomyocytes is lacking. Therefore the expression of thyroid hormone and beta-adrenergic receptors was investigated in human ventricular cardiomyocytes isolated from patients with end-stage heart failure (FM, n=12), or from tentative donors (C, n=4). The expression of thyroid (TRalpha1, and TRbeta1) and beta-adrenergic receptors (ARB1 and ARB2) was measured at both the gene, and at the protein level. In FM the reduced mRNA expression of ARB1 (p<0.05, -37\%) and ARB2 (p<0.05, -42\%) was associated with a reduction of the messenger for TRalpha1 (p<0.05, -85\%) and TRalpha2 (p<0.05, -73\%). These findings were confirmed at the protein level for ARB1, ARB2 and TRalpha1. These data reveal that in human heart failure the reduction of beta-adrenergic receptors is associated with reduced expression of both TRalpha1 and TRalpha2 isoforms of thyroid hormone receptors
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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