Orchis × colemanii hybridization: Molecular and morphological evidence,seed set success,and evolutionary importance

Despite highly specialized pollination strategies, hybridization is a common phenomenon among Mediterranean deceptive orchids. Food-deceptive species sire a progeny of F₁ unfertile plants, which work as a late post-zygotic barrier. Conversely, when pre-zygotic barriers of sexually deceptive (Ophrys) species are absent, the hybrids are fertile and an extensive introgression may occur. Here, we have performed molecular analysis and hand pollination treatments to characterize a hybrid zone of two food-deceptive species, O. mascula and O pauciflora. Hybrids (called O. × colemanii) have shown different amounts of parental nrDNA, strongly supporting that they are F₂ and/or successive hybrid generations. Comparable high levels of reproductive success have been detected in natural conditions and in experimental crosses suggesting the absence of effective reproductive barriers either between hybrids, either between hybrids and parental species. In light of ecological and distributional features of O. × colemanii across its distribution range, we hypothesize that these populations have originated by secondary contact in the periglacial belt of Apennines. Moreover, the rare and localized O. pauciflora could benefit a genetic enrichment by hybridizing with a widespread related species. O. × colemanii is not a dead end population, but may have a role as potential reserve of adaptive variability and is an unusual stage along the speciation process.     

Developmental changes in antioxidant metabolites, enzymes, and pigments in fruit exocarp of four tomato (Lycopersicon esculentum Mill.) genotypes: β-carotene, high pigment-1, ripening inhibitor, and ‘Rutgers’

In surface cell layers of fleshy fruit, antioxidants must limit photooxidative reactions that generate reactive oxygen species (ROS) in high light. Our objective was to measure changes in the concentrations of antioxidant metabolites and pigments, and the activities of enzymes of the Mehler-peroxidase, ascorbate-glutathione cycle in fruit exocarp tissue under non-stress conditions of the following fruit-specific tomato (Lycopersicon esculentum Mill.=Solanum lycopersicum) mutants and their parent: (1) beta-carotene (B), (2) high pigment (hp-1), (3) ripening inhibitor (rin), and (4) the nearly isogenic wild-type 'Rutgers'. Developmental variables included days after anthesis (DAA) and fruit surface color. The highest total ascorbic acid (AsA) concentration was in the exocarp of immature green fruit of hp-1, being 32% higher than 'Rutgers'. The hp-1 mutant also had the highest chlorophyll and total carotenoid concentrations, comprised mostly of lycopene in red ripe fruit; whereas, beta-carotene comprised 90% of the carotenoids in B. Although enzyme activities varied within genotype, they generally increased with development, then decreased as fruit maturity was reached, being coupled with AsA and glutathione (GSH) concentrations. In all mutants, dark-green (DG) exocarp had more chlorophyll and protein, higher concentrations of reduced AsA and GSH, and usually lower enzyme activities than light-green (LG) exocarp taken from the same fruit.     

Inhibition of prostaglandin biosynthesis by c−5, c−8, c−11-eicosatrienoic acid

The enzyme prostaglandin H → E-isomerase (EC 5.3.99.3), which is present in sheep vesicular gland and needs glutathione as cofactor, is inhibited by c−5, c−8, c−11-eicosatrienoic acid, the fatty acid accumulating during essential fatty acid deficiency. The EFA-deficiency syndrome can partly be explained from a prostaglandin deficiency caused by lack of precursors. The present finding indicates that 5,8,11-eicosatrienoic acid could well be an additional factor in modifying the symptoms of EFA-deficiency.     

Plio-Pleistocene evolution of the genus Castor (Rodentia, Mammalia) in Europe: C. fiber plicidens of Pietrafitta (Perugia, Central Italy)

In the lignite sediments of Pietrafitta (Tiberino Basin, Umbria, Central Italy), a rich fossil assemblage of vertebrate, invertebrate and plant remains belonging to the Farneta Faunal Unit (Late Villafranchian, Early Pleistocene) was collected. Among them fossil beaver cranial remains are relatively abundant. Western-Central Europe Villafranchian beaver remains were assigned to C. plicidens by some authors because molar occlusal surface patterns show complex enamel crenulations. Several recent authors have classified them as C. fiber while analysing other morphological patterns. Our samples have been compared to Plio-Pleistocene fossil remains and to living European populations of the genus Castor. New morphometric parameters on molar occlusal surfaces have been defined and statistical analyses (One-Way MANOVA, Principal Component Analysis and Canonical Discriminant Analysis) have been performed on them. The results point out a subspecific separation between the Late Villafranchian beaver of Pietrafitta, Quarata and San Giovanni in Valdarno (Umbria and Tuscany) and C. fiber populations. St. Vallier (France) Late Pliocene and Mosbach 2 (Germany) Middle Pleistocene beavers classified respectively by Viret and Friant as C. plicidens, show a C. f. fiber molar teeth pattern. Therefore, C. fiber plicidens did not occur in Central-Western Europe and this subspecific name may be used only for the local populations of Valdarno and Tiberino Basin (San Giovanni in Valdarno, Quarata, Pietrafitta and a few localities of the same area), at that time peripheral populations, probably semi-isolated during the Late Villafranchian, and at the southern limit of the geographic range of C. fiber.     

Solvent roles in metal ion coordination: the NiCl2O-solvates, NiCl2 · 4MeOH, NiCl2 · 2MeOH · 0.5dioxan and NiCl2 · 2H2O · 2dioxan

Low-temperature, single crystal X-ray structural characterisations of trans-[NiCl₂(HOMe)₄], trans-O-[Ni(MeOH)₂(μ-Cl)_(2/2)2]_(∞∣∞) · 0.5dioxan and trans-trans-[Ni(H₂O)₂Cl₂(O-dioxan-O)_(2/2)]_(∞∣∞) · dioxan are recorded, offering intriguing insights into O-donor/Ni(II) relativities. All nickel atoms in all structures are located on crystallographic inversion centres, the last two compounds being one-dimensional polymers.     

Restriction fragment length polymorphism of ovine casein genes: close linkage between the αs1-,αs2-,ß- and k-casein loci

Restriction fragment length polymorphism (RFLP) of ovine casein genes was investigated. Genomic DNA from 56 rams was digested with 10 restriction endonucleases and Southern blots probed with the four ovine casein cDNAs (alpha s1-, beta-, alpha s2- and kappa-Cn). Five enzymes, namely, BglI, PvuII, RsaI, TaqI and HindIII revealed nine different RFLPs. The inheritance of six of these polymorphisms was studied by segregation analysis of gametes in nine rams' families, and each of them could be related to the existence of alleles at the relevant casein locus. A close linkage between the four ovine casein genes was demonstrated since no recombination within the four pairs of loci examined, alpha s1-beta-Cn, alpha s1-kappa-Cn, beta-kappa-Cn and alpha s2-kappa-Cn, was observed in the progeny of double heterozygous rams. The casein genes are thus clustered in the ovine species as in the case of other mammals.     

Los géneros Praectenodonta, Praenucula y Notonucula (Palaeotaxodonta : Bivalvia) en el Siluro-Devónico de Bolivia

Taxonomy of 57 bivalves, internal and external molds is described in this paper, corresponding to three paleotaxodontids genera Praectenodonta, Praenucula and Notonucula. Samples were collected from nine sites, where stratigraphic columns were measured in Silurian to Devonian series from Altiplano, Cordillera Oriental and Interandean of Bolivia. For the first time in Bolivia, Praectenodonta and Notonucula have been identified. Four species have been described, three of them are new: Praectenodonta boliviensis n. sp., Praenucula quichua n. sp. and Notonucula altiplanica n. sp. Paleogeography of new species and genera is proposed.