300 research outputs found
Cloning plants by seeds: inheritance models and candidate genes to increase fundamental knowledge for engineering apomixis in sexual crops.
No full textApomixis is desirable in agriculture as a reproductive strategy for cloning plants by seeds. Because embryos derive from the parthenogenic development of apomeiotic egg cells, apomixis excludes fer- tilization in addition to meiotic segregation and recombination, resulting in offspring that are exact replicas of the parent. Introgression of apomixis from wild relatives to crop species and transforma- tion of sexual genotypes into apomictically reproducing ones are long-held goals of plant breeding. In fact, it is generally accepted that the introduction of apomixis into agronomically important crops will have revolutionary implications for agriculture. This review deals with the current genetic and molec- ular findings that have been collected from model species to elucidate the mechanisms of apomeiosis, parthenogenesis and apomixis as a whole. Our goal is to critically determine whether biotechnology can combine key genes known to control the expression of the processes miming the main components of apomixis in plants. Two natural apomicts, as the eudicot Hypericum perforatum L. (St. John’s wort) and the monocot Paspalum spp. (crowngrass), and the sexual model species Arabidopsis thaliana are ide- ally suited for such investigations at the genomic and biotechnological levels. Some novel views and original concepts have been faced on this review, including (i) the parallel between Y-chromosome and apomixis-bearing chromosome (e.g., comparative genomic analyses revealed common features as repres- sion of recombination events, accumulation of transposable elements and degeneration of genes) from the most primitive (Hypericum-type) to the most advanced (Paspalum-type) in evolutionary terms, and (ii) the link between apomixis and gene-specific silencing mechanisms (i.e., likely based on chromatin remodelling factors), with merging lines of evidence regarding the role of auxin in cell fate specification of embryo sac and egg cell development in Arabidopsis. The production of engineered plants exhibiting apomictic-like phenotypes is critically reviewed and discussed
Borsa vecchia di Trieste
No full textIl dipinto ad olio, opera dello scenografo veronese Pietro Pupilli, rappresenta piazza della Borsa come appariva nel 1849 (data di esecuzione del dipinto). Domina la composizione l’edificio della Borsa, costruito su progetto del marchigiano Antonio Mollari. La posa della prima pietra avvenne il 17 maggio 1802, e la costruzione fu inaugurata il 6 settembre 1806. La facciata principale dell’edificio, realizzato in stile neoclassico, è costituita da un pronao in stile dorico che sorregge una trabeazione decorata con triglifi e metope e culmina con un timpano ospitante al suo interno un orologio affiancato da due figure alate. Il tetto a terrazza è delimitato da una balaustra ornata di statue. L’edificio ospita oggi la Camera di commercio, industria, artigianato ed agricoltura, mentre le attività della Borsa furono trasferite dapprima (1844) presso il Tergesteo, in seguito (1928) nell’ex Palazzo Dreher, non visibile nel dipinto in quanto edificato nel 1909-10. (Descrizione sintetica dell'opera: Architettura: Trieste: palazzo della Borsa; Tergesteo. Figure: uomini; donne. Mezzi di trasporto: carri. Oggetti: scale; casse. Animali: cavalli; buoi; cane.)olio su telaIn basso a sinistra: F. Pupilli 1850Dipartimento di Studi Umanistici (Via del Lazzaretto Vecchio 8, Trieste
Large-angle scattering of multi-GeV muons on thin Lead targets
No full textThe probability of large-angle scattering for multi-GeV muons in lead targets with a thickness of O(10 ^- 1) radiation lengths is studied. The new estimates presented here are based both on simulation programs (GEANT4 libraries) and theoretical calculations. In order to validate the results provided by simulation, a comparison is drawn with experimental data from the literature. This study is particularly relevant when applied to muons originating from νμ CC interactions of CNGS beam neutrinos. In that circumstance the process under study represents the dominant background for the νμ → ντ search in the τ→ μ channel for the OPERA experiment at LNGS. Finally we also investigate, in the CNGS context, possible contributions from the muon photo-nuclear process which might in principle also produce a large-angle muon scattering signature in the detector.The probability of large-angle scattering for multi-GeV muons in thin () lead targets is studied. The new estimates presented here are based both on simulation programs (GEANT4 libraries) and theoretical calculations. In order to validate the results provided by simulation, a comparison is drawn with experimental data from the literature. This study is particularly relevant when applied to muons originating from interactions of CNGS beam neutrinos. In that circumstance the process under study represents the main background for the search in the channel for the OPERA experiment at LNGS. Finally, we also investigate, in the CNGS context, possible contributions from the muon photo-nuclear process which might in principle also produce a large-angle muon scattering signature in the detector
Plant regeneration from callus cultures of Lotus pedunculatus Cav.
No full textPlant regeneration from callus cultures of Lotus pedunculatus Cav
Plant regeneration from callus protoplasts of Onobrychis viciifolia Scop.
No full textPlant regeneration from callus protoplasts of Onobrychis viciifolia Scop
A reappraisal of the evolutionary and developmental pathway of apomixis and its genetic control in angiosperms
No full textApomixis sensu stricto (agamospermy) is asexual reproduction by seed. In angiosperms it represents an easy byway of life cycle renewal through gamete-like cells that give rise to maternal embryos without ploidy reduction (meiosis) and ploidy restitution (syngamy). The origin of apomixis still represents an unsolved problem, as it may be either evolved from sex or the other way around. This review deals with a reappraisal of the origin of apomixis in order to deepen knowledge on such asexual mode of reproduction which seems mainly lacking in the most basal angiosperm orders (i.e., Amborellales, Nymphaeales and Austrobaileyales, also known as ANA-grade), while it clearly occurs in different forms and variants in many unrelated families of monocots and eudicots. Overall findings strengthen the hypothesis that apomixis as a whole may have evolved multiple times in angiosperm evolution following different developmental pathways deviating to different extents from sexuality. Recent developments on the genetic control of apomixis in model species are also presented and adequately discussed in order to shed additional light on the antagonist theories of gain-and loss-of-function over sexuality
Transformation of Medicago sativa using a Ti plasmid derived vector.
No full textTransformation of Medicago sativa using a Ti plasmid derived vector
Did apomixis evolve from sex or was it the other way around?
No full textIn angiosperms, there are two pathways of reproduction through seeds: sexual, or amphimictic, and asexual, or apomictic. The essential feature of apomixis is that an embryo in an ovule is formed autonomously. It may form from a cell of the nucellus or integuments in an otherwise sexual ovule, a process referred to as adventitious embryony. Alternatively, the embryo may form by parthenogenesis from an unreduced egg that forms in an unreduced embryo sac. The latter may form from an ameiotic megasporocyte, in which case it is referred to as diplospory, or from a cell of the nucellus or integument, in which case it is referred to as apospory. Progeny of apomictic plants are generally identical to the mother plant. Apomixis has been seen over the years as either a gain- or loss-of-function over sexuality, implying that the latter is the default condition. Here, we consider an additional point of view, that apomixis may be anciently polyphenic with sex and that both reproductive phenisms involve anciently canalized components of complex molecular processes. This polyphenism viewpoint suggests that apomixis fails to occur in obligately sexual eukaryotes because genetic or epigenetic modifications have silenced the primitive sex apomixis switch and/or disrupted molecular capacities for apomixis. In eukaryotes where sex and apomixis are clearly polyphenic, apomixis exponentially drives clonal fecundity during reproductively favorable conditions, while stress induces sex for stress-tolerant spore or egg formation. The latter often guarantees species survival during environmentally harsh seasons
Corrigendum to “SELNET clinical practice guidelines for bone sarcoma” Critical reviews in oncology/hematology, vol. 174 (2022), 1–10 (Critical Reviews in Oncology / Hematology (2022) 174, (S1040842822001093), (10.1016/j.critrevonc.2022.103685))
No full textThe authors regret, the “IRCCS Istituto Ortopedico Rizzoli, University of Bologna, Via Pupilli, 1, 40136 Bologna, Italy” related author affiliations reported in the article is not correct; therefore, we kindly ask you to forward a request for rectification. E Palmerini 2, D M Donati2, T Frisoni 2, A Righi 2, K Scotlandi2. 2 - IRCCS Istituto Ortopedico Rizzoli, Via Pupilli, 1, 40136, Bologna, Italy. The authors would like to apologise for any inconvenience caused
Obtainment of inter-subspecific hybrids in olive (Olea europaea L.)
No full textTo enrich the source of germplasm of cultivated olive (Olea europaea subsp. europaea L.), inter-subspecific hybrid plants have been produced by experimental crosses between several varieties of cultivated olive and Asian and African accessions of the wild related subspecies cuspidata. Germination of putative hybrid seeds was enhanced by using in vitro embryo culture. The genetic make-up of germinated seedlings was assayed with the aid of both AFLP and SSR molecular markers and their hybrid nature was proved by the presence of male-specific alleles in their molecular patterns. Most of the parent specific alleles showed segregation among F-1 progenies indicating high heterozygosity content of the parental lines. The majority of the hybrids derived from crosses in which an African accession of cuspidata was used as female parent. The overall morphological aspect of hybrids resembled that of the female parent. The production of inter-subspecific hybrid plants in Olea is discussed in relation to the genetic improvement of cultivated olive
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