51 research outputs found
Tomato: a crop species amenable to improvement by cellular and molecular methods
Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures.
In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.
Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy
We review HB stars in a broad astrophysical context, including both variable
and non-variable stars. A reassessment of the Oosterhoff dichotomy is
presented, which provides unprecedented detail regarding its origin and
systematics. We show that the Oosterhoff dichotomy and the distribution of
globular clusters (GCs) in the HB morphology-metallicity plane both exclude,
with high statistical significance, the possibility that the Galactic halo may
have formed from the accretion of dwarf galaxies resembling present-day Milky
Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the
second-parameter problem is presented. A technique is proposed to estimate the
HB types of extragalactic GCs on the basis of integrated far-UV photometry. The
relationship between the absolute V magnitude of the HB at the RR Lyrae level
and metallicity, as obtained on the basis of trigonometric parallax
measurements for the star RR Lyrae, is also revisited, giving a distance
modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are
studied. Finally, the conductive opacities used in evolutionary calculations of
low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and
Space Scienc
Art dĂ©co e indĂșstria: Brasil, dĂ©cadas de 1930 e 1940
Este artigo analisa as caracterĂsticas assumidas pela arquitetura de tendĂȘncia art dĂ©co em construçÔes ligadas Ă indĂșstria - moradias, igrejas, escolas, clubes, fĂĄbricas etc. - erguidas no Brasil nas dĂ©cadas de 1930 e 1940, investigando o repertĂłrio formal utilizado em diferentes tipologias. Faz uma anĂĄlise mais detalhada das construçÔes criadas pela Companhia Industrial Fiação de Tecidos Goyanna, em Pernambuco, no perĂodo entre 1937 e o final da dĂ©cada de 1940. Trata-se de um conjunto notĂĄvel pela unidade formal, vinculada Ă linguagem art dĂ©co, e pelo emprego de soluçÔes inovadoras em termos de forma e de programa.The aim of this article is to analyze the characteristics of Art Deco tendencies in buildings related to the industry - as houses, churches, schools, clubs, plants etc - in Brazil during the 1930s and 1940s. It studies the formal repertory used in different types of construction and develops a more detailed analysis of a complex of constructions by the firm Companhia Industrial Fiação de Tecidos Goyanna, in the state of Pernambuco, built during the period between 1937 and the end of 1940s. The presented group of constructions is notable for the formal coherence, associated with the Art Deco language, and for the use of innovative program and form solutions
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Gaia Early Data Release 3: The celestial reference frame (Gaia-CRF3)
Context. Gaia-CRF3 is the celestial reference frame for positions and proper motions in the third release of data from the Gaia mission, Gaia DR3 (and for the early third release, Gaia EDR3, which contains identical astrometric results). The reference frame is defined by the positions and proper motions at epoch 2016.0 for a specific set of extragalactic sources in the (E)DR3 catalogue. Aims. We describe the construction of Gaia-CRF3 and its properties in terms of the distributions in magnitude, colour, and astrometric quality. Methods. Compact extragalactic sources in Gaia DR3 were identified by positional cross-matching with 17 external catalogues of quasi-stellar objects (QSO) and active galactic nuclei (AGN), followed by astrometric filtering designed to remove stellar contaminants. Selecting a clean sample was favoured over including a higher number of extragalactic sources. For the final sample, the random and systematic errors in the proper motions are analysed, as well as the radio-optical offsets in position for sources in the third realisation of the International Celestial Reference Frame (ICRF3). Results. Gaia-CRF3 comprises about 1.6 million QSO-like sources, of which 1.2 million have five-parameter astrometric solutions in Gaia DR3 and 0.4 million have six-parameter solutions. The sources span the magnitude range G = 13-21 with a peak density at 20.6 mag, at which the typical positional uncertainty is about 1 mas. The proper motions show systematic errors on the level of 12 ÎŒas yr-1 on angular scales greater than 15 deg. For the 3142 optical counterparts of ICRF3 sources in the S/X frequency bands, the median offset from the radio positions is about 0.5 mas, but it exceeds 4 mas in either coordinate for 127 sources. We outline the future of Gaia-CRF in the next Gaia data releases. Appendices give further details on the external catalogues used, how to extract information about the Gaia-CRF3 sources, potential (Galactic) confusion sources, and the estimation of the spin and orientation of an astrometric solution
Microsatellite analysis of pacu broodstocks used in the stocking program of Paranapanema River, Brazil
Monitoring the genetic diversity has fundamental importance for fish stocking programs. This experiment aims to evaluate the genetic diversity in two hatchery stations (A and B) with pacu Piaractus mesopotamicus (Holmberg, 1887) in AndirĂĄ, state of ParanĂĄ, Brazil used in stocking programs of Paranapanema River. Six microsatellite loci were amplified using DNA extracted from 60 fin-clipping samples. The broodstock B had the average number of alleles and the mean heterozygosity (alleles: 3.7 and H O: 0.628) higher than the broodstock A (alleles: 3.5 and H O: 0.600). Alleles with low frequency levels were observed in the both broodstocks. The positive coefficients of endogamy in the locus Pme2 (broodstock A: F IS = 0.30 and broodstock B: F IS = 0.20), Pme5 (broodstock B: F IS = 0.15), Pme14 (broodstock A: F IS = 0.07) and Pme28 (broodstock A: F IS = 0.24 and broodstock B: F IS = 0.20) indicated deficiency of heterozygotes. Presence of null allele in the locus Pme2 was detected. The negative estimates in loci Pme4 (broodstock A: F IS = - 0.43 and broodstock B: F IS = - 0.37), Pme5 (broodstock A: F IS= - 0.11), Pme14 (broodstock B: F IS= - 0.15) and Pme32 (broodstock A: F IS = - 0.93 and broodstock B: F IS = - 0.60) were indicating the excess of heterozygotes. Evidence of linkage disequilibrium and lower allelic richness was found only in the broodstock A. Nei's gene diversity was high in both broodstocks. The genetic distance (0.085) and identity (0.918) showed similarity between broodstocks, which reflects a possible common origin. 6.05% of the total genetic variance was due to differences among broodstocks. Recent bottleneck effect in two broodstocks was observed. The results indicated a higher genetic diversity in the two broodstocks and they presented low genetic difference. This was caused by the reproductive management in both hatchery stations, reduction of population size and genetic exchange between the hatchery stations.O monitoramento da diversidade genĂ©tica Ă© fundamental em um programa de repovoamento. Avaliouse a diversidade genĂ©tica de pacu Piaractus mesopotamicus (Holmberg, 1887) em duas estaçÔes de piscicultura em AndirĂĄ -ParanĂĄ, Brasil, utilizadas no programa de repovoamento do Rio Paranapanema. Foram amplificados seis loci microssatĂ©lite para avaliar 60 amostras de nadadeira. O estoque de reprodutores B apresentou maior nĂșmero de alelos e heterozigose (alelos: 22 e H O: 0,628) que o estoque de reprodutores A (alelos: 21 e H O: 0,600). Alelos com baixos nĂveis de frequĂȘncia foram observados nos dois estoques. Os coeficientes positivos de endogamia no locus Pme2 (estoque A: F IS = 0,30 e estoque B: F IS = 0,20), Pme5 (estoque B: F IS = 0,15), Pme14 (estoque A: F IS = 0,07) e Pme28 (estoque A: F IS = 0,24 e estoque B: F IS = 0,20), indicaram deficiĂȘncia de heterozigotos. Foi detectada a presença de um alelo nulo no lĂłcus Pme2. As estimativas negativas nos loci Pme4 (estoque A: F IS = -0,43 e estoque B: F IS= -0,37), Pme5 (estoque A: F IS = - 0,11), Pme14 (estoque B: F IS = - 0,15) e Pme32 (estoque A: F IS = - 0,93 e estoque B: F IS = - 0,60) foram indicativas de excesso de heterozigotos. Foi evidenciado desequilĂbrio de ligação e riqueza alĂ©lica baixa sĂł no estoque A. A diversidade genĂ©tica de Nei foi alta nos dois estoques. A distĂąncia (0,085) e identidade (0,918) genĂ©tica mostraram similaridade entre os estoques, o qual reflete uma possĂvel origem comum. 6,05% da variĂąncia genĂ©tica total foi devida a diferenças entre os estoques. Foi observado um recente efeito gargalo nos dois estoques. Os resultados indicaram uma alta diversidade genĂ©tica nos estoques de reprodutores e baixa diferenciação genĂ©tica entre eles, o que foi causado pelo manejo reprodutivo das pisciculturas, redução do tamanho populacional e intercĂąmbio genĂ©tico entre as pisciculturas
Brain-based classification of youth with anxiety disorders: transdiagnostic examinations within the ENIGMA-Anxiety database using machine learning
Neuroanatomical findings on youth anxiety disorders are notoriously difficult to replicate, small in effect size and have limited clinical relevance. These concerns have prompted a paradigm shift toward highly powered (that is, big data) individual-level inferences, which are data driven, transdiagnostic and neurobiologically informed. Here we built and validated supervised neuroanatomical machine learning models for individual-level inferences, using a caseâcontrol design and the largest known neuroimaging database on youth anxiety disorders: the ENIGMA-Anxiety Consortium (Nâ=â3,343; ageâ=â10â25 years; global sitesâ=â32). Modest, yet robust, brain-based classifications were achieved for specific anxiety disorders (panic disorder), but also transdiagnostically for all anxiety disorders when patients were subgrouped according to their sex, medication status and symptom severity (area under the receiver operating characteristic curve, 0.59â0.63). Classifications were driven by neuroanatomical features (cortical thickness, cortical surface area and subcortical volumes) in fronto-striato-limbic and temporoparietal regions. This benchmark study within a large, heterogeneous and multisite sample of youth with anxiety disorders reveals that only modest classification performances can be realistically achieved with machine learning using neuroanatomical data.NWORubicon 019.201SG.022Advanced Behavioural Research MethodsHealth and Well-bein
Gaia Early Data Release 3: acceleration of the solar system from Gaia astrometry
Stars and planetary system
Gaia early data release 3: summary of the contents and survey properties (Corrigendum)
ERRATUMThis article is an erratum for:[https://doi.org/10.1051/0004-6361/202039657]âââââââInstrumentatio
Gaia Data Release 3: reflectance spectra of Solar System small bodies
Stars and planetary system
Gaia Early Data Release 3: the Gaia catalogue of nearby stars
Stars and planetary system
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