191 research outputs found

    The intergenic spacer region of the rDNA in Haplopappus gracilis (Nutt.) Gray

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    In this paper we provide further information on the genome organization of Haplopappus gracilis, one of the six angiosperms showing the lowest chromosome number, i.e. 2n=4, by determining the nucleotide sequence of the Intergenic Spacer region of the rRNA genes and its cytological localization on metaphase chromosomes. DNA sequence analysis reveals the occurring of a product of 4,382 bp in length, characterized by the presence of four blocks of different repeated sequences. Our analysis also evidenced putative promoter regions with three Transcription Initiation Sites for Polymerase I, as previously reported in Artemisia absinthium, belonging to the same Asteraceae family. A fluorescent in situ hybridization with the Intergenic Spacer probe indicates the presence of rDNA genes only in the satellited chromosomes of H. gracilis; besides differences in the signal intensity between homologous chromosomes were frequently observed, so suggesting, for these chromosome sites, the presence of a variable number of rDNA gene copies, even if a divergent chromatin organization in corresponding regions can not be ruled out

    Karyological and molecular characterisation of subgenus Vicia (Fabaceae)

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    In the present report, we have analysed the subgenus Vicia by karyological and molecular approaches with the aim to clarify the relationships among Vicia species included in this subgenus by previously evidenced morphological investigations. Multivariate analysis using several karyomorphological parameters in addition to symmetry indices has allowed the construction of a dendrogram of linkage distances very useful to compare and to include in a phylogenetic tree obtained by internal transcribed spacer (ITS) rDNA sequences. Moreover, a separate analysis was performed combining our molecular data on ITS sequences with those reported in the literature for the section Vicilla. Our analyses partly confirm the monophyletic status of the various sections in which the subgenus Vicia has been divided, however questioning, in some cases, the real need to maintain all the nine sections so far accepted and the placement of some individual species in the two subgenera Vicia and Vicilla

    Synsedimentary tectonics and sedimentation in the Tertiary Piedmont Basin, Northwestern Italy

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    The Late Oligocene/Early Miocene tectonic and sedimentary evolution of the eastern sector of the Langhe Sub-Basin (Tertiary Piedmont Basin) is proposed and discussed. The area is located between the villages of Roccaverano and Mombaldone, along the western side of the Bormida di Spigno River Valley (see attached geologic map). Synsedimentary tectonics strongly influenced the geologic evolution of the region during the time span examined, being particularly evident at three specific "times" that were chosen as models. During "Time 1" (Late Oligocene) gentle anticlines, aligned WNW-ESE and NW-SE, started to form, affecting only hemipelagic mudstones and creating structural highs that controlled the areal distribution of both turbidites (i.e. T. Ovrano High) and a thick pelitic slump sheet (i.e. M. Pisone High). During "Time 2" (Aquitanian) the C. Mazzurini Half-Graben developed, separated by W-E and WNW-ESE growth faults from the M. Ovrano High to the north and gradually connecting, through a gently sloping ramp, with the Rocchetta High to the south. Turbidity currents and debris flows were channeled into the half-graben, while hemipelagic limestones were deposited onto the adjacent higher areas. During "Time 3" (Early Burdigalian) the depocenter of the depression shifted southward, while the half-graben evolved into a wide trough (Piantivello Trough) characterized by turbidites. Subsequently, the strongly irregular topography was progressively leveled to the quite homogeneous landscape on which the Cortemilia Formation (Late Burdigalian) was deposited

    The Lords of the Rent

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    The present paper aims at evaluating which factors affect farmland rents, measuring their relative importance through an empirical analysis based on a hedonic pricing model

    The Effect of Biogas Production on Farmland Rental Prices : Empirical Evidences from Northern Italy

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    In the last decade, increased environmental awareness has prompted the adoption of incentives for exploiting renewable energy sources. Among these, biogas production has received a certain attention in developed countries. Nonetheless, the subsidies provided have posed the problem of an activity (the production of bioenergy) that engages in direct competition with food and feed production for limited resources, like agricultural land. Even if this competition may be softened by allocating marginal land and/or using dedicated non-agricultural crops, empirical evidence shows that biogas plants have been developed in highly-productive agricultural areas, using increasing amounts of maize silage as feedstock. Thus, studies aimed at measuring the effect of biogas production on agricultural activities are needed in order to avoid this socially undesirable outcome. The paper presents an econometric estimation of the impact of biogas plants on farmland rental values of a Northern Italian rural area. Results show that biogas has a non-linear effect on rental prices, suggesting that incentive schemes specifically accounting for plants\u2019 dimensions and technologies would improve the social sustainability of the bioenergy sector and its coexistence with agricultural activity
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