Academic literature on the topic 'CHROMATIC RESTITUTION'

During recent years unmanned aerial vehicles (UAVs) have been increasingly used for research and application in both agriculture and forestry. Nevertheless, most of this work has been devoted to improving accuracy and explanatory power, often at the cost of usability and affordability. We tested a low-cost UAV and a simple workflow to apply four different greenness indices to the monitoring of pine (Pinus sylvestris and P. nigra) post-fire regeneration in a Mediterranean forest. We selected two sites and measured all pines within a pre-selected plot. Winter flights were carried out at each of the sites, at two flight heights (50 and 120 m). Automatically normalized images entered an structure from motion (SfM) based photogrammetric software for restitution, and the obtained point cloud and orthomosaic processed to get a canopy height model and four different greenness indices. The sum of pine diameter at breast height (DBH) was regressed on summary statistics of greenness indices and the canopy height model. Excess green index (ExGI) and green chromatic coordinate (GCC) index outperformed the visible atmospherically resistant index (VARI) and green red vegetation index (GRVI) in estimating pine DBH, while canopy height slightly improved the models. Flight height did not severely affect model performance. Our results show that low cost UAVs may improve forest monitoring after disturbance, even in those habitats and situations where resource limitation is an issue.

Meiosis drives reciprocal genetic exchanges and produces gametes with halved chromosome number, which is important for the genetic diversity, plant viability, and ploidy consistency of flowering plants. Alterations in chromosome dynamics and/or cytokinesis during meiosis may lead to meiotic restitution and the formation of unreduced microspores. In this study, we isolated an Arabidopsis mutant male meiotic restitution 1 (mmr1), which produces a small subpopulation of diploid or polyploid pollen grains. Cytological analysis revealed that mmr1 produces dyads, triads, and monads indicative of male meiotic restitution. Both homologous chromosomes and sister chromatids in mmr1 are separated normally, but chromosome condensation at metaphase I is slightly affected. The mmr1 mutant displayed incomplete meiotic cytokinesis. Supportively, immunostaining of the microtubular cytoskeleton showed that the spindle organization at anaphase II and mini-phragmoplast formation at telophase II are aberrant. The causative mutation in mmr1 was mapped to chromosome 1 at the chromatin regulator Male Meiocyte Death 1 (MMD1/DUET) locus. mmr1 contains a C-to-T transition at the third exon of MMD1/DUET at the genomic position 2168 bp from the start codon, which causes an amino acid change G618D that locates in the conserved PHD-finger domain of histone binding proteins. The F1 progenies of mmr1 crossing with knockout mmd1/duet mutant exhibited same meiotic defects and similar meiotic restitution rate as mmr1. Taken together, we here report a hypomorphic mmd1/duet allele that typically shows defects in microtubule organization and cytokinesis.

Aim. Despite significant progress in the investigation of cytomixis its functional role and effect on the course of meiosis as well as mechanisms of 2n pollen grains formation is still not completely clear. We have studied the destination of cytomictic chromatin as well the mechanisms of unreduced microspores formation in species of monocots with spontaneous cytomixis. Methods. Light and fluorescent microscopy. Results. The cytomictic chromatin forms additional meiotic chromosomes in the recipient microsporocytes. Many of these meiotic chromosomes undergo rearrangement and fragmentation but retain their bivalent organization. Conclusions. Cytogenetic anomalies of microsporogenesis caused by activation of cytomixis in prophase may reflect meiosis stabilization mechanisms by assimilation and adaptation or diminution and reutilization of the introduced DNA. The main mechanism of polyploidization of microsporocytes and pollen grains in studied monocots is the restitution of the first meiotic division via the formation of a meta-anaphase 1 block.Keywords: cytomixis, microsporogenesis, additional (recipient) chromosomes, meta-anaphase 1 block, Lilium croceum Chaix., Allium cepa L., Allium fistulosum L.

In first division restitution (FDR)-type meiosis, univalents congregate on the metaphase I plate and separate sister chromatids in an orderly fashion, producing dyads with somatic chromosome numbers. The second meiotic division is abandoned. The separation of sister chromatids requires separation of otherwise fused sister centromeres and a bipolar attachment to the karyokinetic spindle. This study analyzed packaging of sister centromeres in pollen mother cells (PMCs) in a wheat–rye F1 hybrid with a mixture of standard reductional meiosis and FDR. No indication of sister centromere separation before MI was observed; such separation was clearly only visible in univalents placed on the metaphase plate itself, and only in PMCs undergoing FDR. Even in the FDR, PMCs univalents off the plate retained fused centromeres. Both the orientation and configuration of univalents suggest that some mechanism other than standard interactions with the karyokinetic spindle may be responsible for placing univalents on the plate, at which point sister centromeres are separated and normal amphitelic interaction with the spindle is established. At this point it is not clear at all what univalent delivery mechanism may be at play in the FDR.

<p>The morphology of cell nuclei in callus obtained from root-tip meristems of <em>Allium fistulosum</em> L. (Monocotyledoneae, Alliaceae) was analysed. The most interesting phenomena observed in long-term callus culture were the different mechanisms of cell polyploidization, enlargement of telomeric segments of heterochromatin, and extensive chromatin elimination, associated with instability of nuclei size and DNA content.</p><p>Protruding heterochromatin "spikes" were observed on the surface of some di- and polyploid nuclei. The presence of these spikes was connected with the formation of small heterochromatic micronuclei frequently found in the cytoplasm. It is suggested that these micronuclei are produced by direct elimination of heterochromatin from the interphase nuclei.</p><p>Polyploid cells accumulated with each successive cell collection. The ploidy level attained by highly polyploid cells was 15C-220C. The shape of the nuclei and heterochromatin distribution suggest that polyploid nuclei in <em>A. fistulosum</em> tissue culture are produced by endoreduplication and by restitution cycles.</p>

Cytological investigation revealed desynapsis in microsporogenesis of a wild diploid clone of Vaccinium darrowi. Expression of desynapsis appears variable among the pollen mother cells (PMCs). In the PMCs expressing desynapsis, all or most chromosomes appeared to be completely desynapsed before anaphase I (AI) since bivalents were rare at this stage. In some PMCs complete separation of chromatids was also observed before AI. Consequently, one or both meiotic divisions were lacking, which in turn suggests either a lack of spindle formation or function. Lack of spindle function was hypothesized from the observation that in PMCs with only separated chromatids (daughter chromosomes) before AI or anaphase II (AII), their subsequent movement to anaphase poles was not observed. Thus, spindle formation or function appears to be dependent on paired homologues (bivalents) or minimally joined sister chromatids (univalents) being present. Omission of meiosis II could lead to formation of fertile 2n pollen (~5%), since a balanced chromosome complement would be expected with an equational division of the entire chromosome complement at AI. The genetic constitution of the 2n gamete would be equivalent to first division restitution (FDR) origin. If chiasmata are lacking then recombination would be absent, and 100% transmission of parental heterozygosity would be expected with FDR 2n gametes. Because desynapsis may arise from the lack of effective chiasmata between the paired homologues, a high level of parental heterozygosity is expected to be retained in the 2n gametes. The potential usage of the 2n gametes in blueberry breeding was discussed.Key words: desynapsis, spindle abnormality, 2n pollen, blueberry.

Abstract Background Unreduced gametes, a driving force in the widespread polyploidization and speciation of flowering plants, occur relatively frequently in interspecific or intergeneric hybrids. Studies of the mechanisms leading to 2n gamete formation, mainly in the wheat tribe Triticeae have shown that unreductional meiosis is often associated with chromosome asynapsis during the first meiotic division. The present study explored the mechanisms of meiotic nonreduction leading to functional unreduced gametes in an interspecific Trifolium (clover) hybrid with three sub-genomes from T. ambiguum and one sub-genome from T. occidentale. Results Unreductional meiosis leading to 2n gametes occurred when there was a high frequency of asynapsis during the first meiotic division. In this hybrid, approximately 39% of chromosomes were unpaired at metaphase I. Within the same cell at anaphase I, sister chromatids of univalents underwent precocious separation and formed laggard chromatids whereas paired chromosomes segregated without separation of sister chromatids as in normal meiosis. This asynchrony was frequently accompanied by incomplete or no movement of chromosomes toward the poles and restitution leading to unreduced chromosome constitutions. Reductional meiosis was restored in progeny where asynapsis frequencies were low. Two progeny plants with approximately 5 and 7% of unpaired chromosomes at metaphase I showed full restoration of reductional meiosis. Conclusions The study revealed that formation of 2n gametes occurred when asynapsis (univalent) frequency at meiosis I was high, and that normal gamete production was restored in the next generation when asynapsis frequencies were low. Asynapsis-dependent 2n gamete formation, previously supported by evidence largely from wheat and its relatives and grasshopper, is also applicable to hybrids from the dicotyledonous plant genus Trifolium. The present results align well with those from these widely divergent organisms and strongly suggest common molecular mechanisms involved in unreduced gamete formation.

Il tema centrale della tesi di dottorato è relativo alla realizzazione e all’utilizzo di modelli parametrici per la descrizione del patrimonio costruito. Negli ultimi anni l’aderenza geometrica di questi elaborati ha raggiunto livelli di approssimazione molto bassi rispetto al reale, sia grazie alla precisione e all’accuratezza degli strumenti di acquisizione che allo sviluppo di pacchetti integrati di programmi che consentono di operare all’interno di uno stesso framework. In particolare questa ricerca affronta il tema del texturing nei modelli parametrici del patrimonio architettonico realizzati a partire da dati morfometrici e cromatici desunti mediante operazioni di rilevamento digitale. Vengono affrontate la questione della semplificazione del dettaglio geometrico, tipica delle procedure di modellazione parametrica, e quella relativa alla gestione del colore apparente attraverso l’uso delle Bitmap Maps. Il tema, seppure largamente trattato nell’ambito della documentazione del patrimonio culturale, è stato relegato ad un secondo piano nei software per HBIM. Nell’ottica di facilitare il management dell’intero processo che va dalla documentazione del bene ai piani-programma di manutenzione per mezzo di un unico modello tridimensionale e, possibilmente, tramite un solo software o pacchetto di programmi facenti parte di una stessa piattaforma (con evidenti vantaggi sia in termini di tempo che economici), è necessario predisporre dei modelli ad hoc che consentano di visualizzare l’intera mole delle informazioni morfometriche e cromatiche acquisite mediante le odierne metodologie di rilevamento digitale. Nei modelli parametrici, ad esempio, non è comune restituire le variazioni nella forma e/o nel colore dei materiali a seguito di fenomeni di degrado quali la decoesione, l’alveolizzazione o le alterazioni cromatiche. Non risulta conveniente, infatti, né modellare tutte le necessarie discontinuità in grado di descrivere i suddetti fenomeni direttamente in ambiente parametrico, né ricorrere ad altri software per generare delle superfici NURBS o mesh da integrare successivamente al modello parametrico principale. È plausibile invece visualizzare tali informazioni attraverso l’utilizzo di Bitmap Maps e, in particolare, delle Normal Maps, in grado di simulare l’andamento delle superfici che definiscono la frontiera degli elementi. Il ricorso alle Bitmap Maps consente a sua volta di rappresentare il colore apparente con la necessaria affidabilità. Una parte rilevante della tesi è finalizzata, pertanto, a sottolineare il ruolo fondamentale che le Bitmap Maps rivestono per i modelli parametrici in ambito HBIM. In particolare, viene mostrato come sia preferibile generare le Normal Maps a partire dai modelli high-poly, attraverso procedure di baking, piuttosto che derivarle dalle Diffuse Color Maps e utilizzare le mappe del colore apparente desunte attraverso operazioni Structure from Motion (SfM) nel descrivere an-che gli aspetti legati alla riflettanza (reflectance), alla ruvidità (roughness), alla traslucidità (translucency) e all’emissività (emissivity). Lo studio accurato dello stato dell’arte ha rappresentato un imprescindibile punto di partenza per definire la direzione che avrebbe dovuto prendere la tesi. Il caso studio ha influenzato in larga parte questa decisione perché ha messo in evidenza la necessità di approfondire le modalità di descrizione del colore apparente nei modelli parametrici costruiti per la gestione del cantiere di restauro. La messa a punto di una serie di procedure per ottenere risultati soddisfacenti nella realizzazione degli elaborati che rappresentano la superficie esterna (in tutte le sue declinazioni) dei vari elementi che compongono un fabbricato consente ad altri studiosi di valutare l’efficacia delle pipeline proposte, garantendo al contempo la necessaria trasparenza richiesta dagli odierni metodi di ricerca. La riproduzione quanto più esatta possibile del dato morfometrico e di quello cromatico della struttura superficiale può garantire la trasmissione di dati (raccolti al momento dell’acquisizione) che altrimenti andrebbero persi nella semplificazione introdotta dalla parametrizzazione, oltre che fornire informazioni utili nel momento della realizzazione del progetto di restauro. La tesi è divisa in quattro sezioni, ciascuna delle quali ha lo scopo di approfondire uno degli ambiti che concorrono alla definizione del tema centrale della tesi. Nella Sezione 1 vengono riassunte le principali prerogative del rilievo digitale e descritto il flusso di lavoro ritenuto più idoneo affinché i dati acquisiti con sensori attivi e passivi possano essere efficacemente utilizzati e integrati per la realizzazione di modelli tridimensionali all’interno di software parametrici. La Sezione 2 affronta lo stato dell’arte relativo alla realizzazione e gestione dei modelli 3D, al texturing e all’HBIM. Viene inoltre descritta la modalità di creazione e applicazione dei materiali all’interno del software Autodesk Revit, uno dei più usati in Europa, che dal 2019 consente la generazione di materiali PBR (Physically Based Rendering). Nella Sezione 3 viene presentato il caso studio sul quale è stata verificata la bontà del procedimento elaborato e descritto nella sezione successiva. Tra le finalità del Progetto di Cooperazione Internazionale Italia-Cuba ¡Que no baje el telón!, del quale il Dipartimento di Architettura dell’Università di Firenze (DIDA) è uno degli attori principali, vi è quello di realizzare uno strumento informatico basato sull’utilizzo dei processi BIM per la gestione del progetto di restauro, consolidamento e successiva manutenzione del complesso di fabbricati che compone la Facultad de Arte Teatral (FAT) dell’Universidad de las Artes de La Habana (ISA). Viene pertanto presentato il contesto entro il quale si collocano i manufatti, le loro caratteristiche morfometriche e materiche, gli strumenti e le procedure utilizzate per l’acquisizione dei dati metrici e cromatici, mettendo in evidenza le problematiche riscontrate e le soluzioni adottate. La Sezione 4, infine, descrive la procedura proposta in relazione al caso studio, analizzandone criticamente i vantaggi e gli svantaggi e riassumendone tutti i passaggi, anche quelli che riproducono procedure note di rilevamento e restituzione digitale, attraverso uno schema. Si traggono inoltre le conclusioni e si delineano i possibili sviluppi futuri. Conclude la tesi un glossario dei termini tecnici utilizzati, che consente anche ad un pubblico di non specialisti di comprendere quanto trattato in questo volume. The central theme of the doctoral thesis is related to creation and use of parametric models for the description of the built heritage. In the lasts years the geometric adherence of these works has reached very low approximation levels compared to the real, thanks both to precision and accuracy of the acquisition tools and the development of integrated packages of software allowing to operate within the same framework. In particular, this research deals with the texturing in parametric models of architectural heritage made from morphometric and chromatics data derived from digital survey operations. The question of the simplification of geometric detail, typical of parametric modelling procedures, and that on apparent colour management through the use of Bitmap Maps are addressed. The theme, albeit broadly treated in the context of heritage documentation cultural, has been relegated to a second level in software for HBIM. In order to facilitate the management of the entire process that goes from the documentation of the artifact to the plan maintenance through a single three-dimensional model and, possibly, through an only software or package of programs that are part of of the same platform (with obvious advantages both in time and economic), it is necessary to prepare ad hoc models to display the entire volume of morphometric and chromatic information acquired through digital technologies. In parametric models, for example, it is not common show changes in the shape and/or colour of the materials following degradation phenomena such as decohesion, alveolization or chromatic alterations. It is not convenient, in fact, neither to model all necessary gaps that can describe the above phenomena directly in a parametric environment, or use other software to generate NURBS or mesh surfaces to be integrated to the main parametric model. It is plausible instead view that information through the use of Bitmap Maps and, in particular, of the Normal Maps, able to simulate the trend of surfaces that define the boundary of the elements. The use of Bitmap Maps allows represent the apparent color with the necessary reliability. A relevant part of the thesis is aimed, therefore, to underline the fundamental role that Bitmaps Maps cover for parametric HBIM models. In particular, it is shown how it is preferable generate the Normal Maps from the mesh high-poly, through baking procedures, rather than derive them from Diffuse Color Maps, and use the apparent color maps derived through Structure from Motion (SfM) in describing also aspects related to reflectance, to roughness, translucency and emissivity. The careful study of the state of the art represented an essential starting point to define the direction that the thesis should have taken. The case study largely influenced this decision because it highlighted the necessity to learn more about how to describe apparent color in parametric models built for management of the restoration site. The development of a series of procedures to obtain satisfactory results in the realization of the drawings representing the external surface (in all its declinations) of the various elements that make up a building allows other scholars to evaluate the effectiveness of the proposed pipelines, guaranteeing at the same time the necessary transparency required by the modern research methods. The reproduction of the morphometric and chromatic data as exact as possible of the superficial structure can guarantee the transmission of data (collected at the time of acquisition), that otherwise would be lost in the simplification introduced by the parameterization, as well as providing information useful in the moment of the realization of the restoration project. The thesis is divided into four sections, each of which aims to deepen one of the competing areas to the definition of the central theme of the thesis. Section 1 summarizes the main prerogatives of the digital survey and described the workflow deemed more suitable so that the data acquired with active and passive sensors can be effectively used and integrated for the creation of three-dimensional models within parametric software. Section 2 deals with the state of the art relating to creation and management of 3D models, texturing and to HBIM. It also describes how to create and applicate materials within the Autodesk Revit software, one of the most used in Europe, which since 2019 allows the generation of materials PBR (Physically Based Rendering). Section 3 presents the case study on which the correctness of the procedure was verified elaborated and described in the next section. Between the aims of the International Cooperation Project Italy-Cuba ¡Que no baje el telón! of which the Department of Architecture of the University of Florence (DIDA) is one of the main actors, there is to create a computer tool based on the use of BIM processes for management, restoration, consolidation and subsequent maintenance project of the complex of buildings that makes up the Facultad de Arte Teatral (FAT) of the Universidad de las Artes de La Habana (ISA). It is therefore presented the context within which the artifacts are placed, their morphometric and material characteristics, the tools and procedures used for the acquisition of the metric and chromatic data, highlighting the problems encountered and the solutions adopted. Finally, Section 4 describes the proposed procedure in relation to the case study, critically analyzing it the advantages and disadvantages and summarizing all the passages, even those that reproduce digital survey acquisition and restitution procedures, through a scheme. In addition, conclusions are drawn and possible future developments are outlined. The thesis concludes with a glossary of the technical terms used, which also allows a non-specialist public to understand what is treated in this volume.