1,720,961 research outputs found
Cytoplasmic differences between the pollen grains of two cultivars of Malus domestica borkh. correlated with viability and germination
No full textThe ultramicroscopic study of pollen grains from two cultivars of Malus domestica, Starkrimson and Golden Delicious, revealed well-developed mitochondria and conspicuous endoplasmic reticulum in the first variety, suggesting greater metabolic activity. Incorporation of tritiated thymidine and uridine in the hydrated grains of both cultivars indicated replication of DNA and transcription within both mitochondria and plastids
Brassica seed coat peroxidase [Perossidasi nel tegumento del seme di Brassica]
No full textPeroxidase activity was tested in Brassica oleracea seed integument during germination. POD activity increases from 24 to 72 h after seed imbibition with no significative changes from 72 to 144 h. Maximum level of enzyme activity was reached 48 h after the radicle protrusion. After germination the enzyme has been localized in the cell walls of palizade, pigmented and aleurone layers and in the cytoplasm of aleurone cells
In vitro pollen grain germination and starch content in species with different reproductive cycle. I. Lycopersicum peruvianum Mill
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Dynamics of Pollen Grain Germination in Two Cultivars of Malus domestica: the Influence of Actinomycin D on Fresh and Stored Pollen Grains
No full textThe pattern of germination has been detected in the presence or in the absence of Actinomycin D (AmD) in fresh and stored binucleate pollen grains of' Golden Delicious' (GD) and' Starkrimson' (S). Pollen tube growth consisted of two distinct phases, autotrophic and heterotrophic, in both fresh and stored pollen grains. The pollens of the two cultivars differ: (i) in the length of the first phase, being 3 h in GD and 2 h in S, and (ii) in the response to storage. As far as the response to storage is concerned the cultivar S seems to be more
damaged than GD when the storage effect is evaluated as the first phase length; less damaged than GD when the effect is expressed as tube length
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
Genome modifications during male gametogenesis in vitro in Narcissus papyraceus Ker-Gawl
No full textViability of stored pollen grains of malus domestica borkh as evaluated by the incorporation of labelled nucleic acid precursors
No full textViability of stored pollen grains of Malus domestica Borkh, cultivars "Golden delicious" and "Starkrimson" is expressed as: 1) percentage of labelled generative and vegetative cells after feeding with 3H-thymidine and 3H-uridine; 2) percentage of germinated pollen grains. The ability to incorporate nucleic acid precursors ecreases during storage; the vegetative cytoplasm response to storage is slower than the nuclear response, in respect to both 3H-thymidine and 3H-uridine incorporation. The germination ability is not influenced by the investigated storage. No relationship between the capacity of incorporating nucleic acid precursors and pollen grains germination is therefore detectable
Dynamics of pollen grain germination in two cultivars of Malus domestica: the influence of actinomycin D on fresh and stored pollen grains
No full textVariations 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
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