The influence of implant number and abutment design on the biomechanical behaviour of bone for an implant-supported fixed prosthesis: a finite element study in the upper anterior region

It is always recommended to use more implants for supporting a prosthesis in the immediate loading condition than in the classical two-stage treatment procedure. By means of the finite element (FE) method, the influence of the number of implants used in immediately loaded fixed partial prosthesis (FPP) on the load distribution was investigated, considering the abutment geometry. Two 3D FE models were studied employing four implants to support a FPP in the premaxilla. One model was designed with straight abutments and the other with 20°-angled abutments. The results concerning implant displacements, stresses and strains were compared with those of two implant-supported FPPs, obtained in a previous study. A noticeable reduction in the determined biomechanical bone loading was observed with the use of more implants in supporting an immediately loaded prosthesis. This study confirms that the use of additional numbers of implants in an immediately loaded prosthesis is highly recommended.     

Mineral element distribution in organs of dual-toxin transgenic (Bt+CpTI) cotton seedling

Abstract

Being a new cultivar, the physiology of transgenic cotton, especially dual-toxin transgenic (Bt+CpTI) cotton, is not yet completely understood. Twelve elements in three organs of dual-toxin transgenic cotton seedlings were analyzed by ICP-MS. The distributions of the 12 elements were substantially different from those of non-transgenic cotton. In particular, the contents of B, Mg, P, K and Ca were the highest in leaves, while those of Si, Fe, Rb and Cu were the highest in roots; other elements had similar contents in the two organs, which were higher than those in the stem. Compared with non-transgenic cotton, the 12 elements could be classified into four groups according to their contents and distributions in the three organs: (a) P, K and Cu: their contents in transgenic cotton were remarkably lower, especially contents of P and K in leaves that were one times lower than those in leaves of non-transgenic cotton; (b) B, Mg and Mo: their contents in leaves and roots of transgenic cotton were higher, but lower in stems, compared with non-transgenic cotton; (c) Si, Mn, Fe, Rb and Zn: compared with non-transgenic cotton, these were lower in leaves and stems, but higher in roots of transgenic cotton; and (d) Ca: compared with non-transgenic cotton, its content was higher in all three organs of the transgenic counterpart. The decrease in soluble proteins and the expression of Bt and CpTI genes could be responsible for these changes. Further studies are needed to verify this hypothesis.     

The past,present and future of thermophilous Cyperus polystachyos Rottb. (Cyperaceae) on the island of Ischia (southern Italy)

Cyperus polystachyos is a hygrophilous, thermophilous and heliophilous plant with a punctiform distribution in southern Italy, where it is almost exclusively found on Ischia, an island in the Bay of Naples characterized by widespread volcanic hydrothermal activity. This species is a native of tropical and subtropical areas and there is evidence for ancient isolation events in the creation of its current distribution pattern. We have studied the historical literature available for this plant since 1800 and collected temporal and spatial presence data of this species in order to develop a habitat suitability map based on a GIS approach and using a multiple linear regression model. Moreover, we have used univariate and multivariate statistical analysis. The results show the importance of the environmental mosaic around fumaroles to preserve the species; urbanization and geothermal energy use of fumaroles in the past and the combination of abandonment of the typical agricultural system and the natural occurrence of reforestation in the present are the main causes of the decline in the number of populations.     

Investigating the origin of transoceanic distributions: Mtdna shows Mabuya lizards (Reptilia,Scincidae) crossed the Atlantic twice

Phylogenies with even a rough time scale can be used to investigate the history of non‐volant taxa with disjunct distributions in widely separated land areas that were once connected. Basic methods for doing this are discussed. A partial phylogeny of Mabuya based on mtDNA (305 bp cytochrome b, 379 bp 12S rRNA and 388 bp 16S rRNA) is used to show that this genus invaded tropical America from Africa twice in the last 9 Myr, once reaching the American mainland and once the oceanic island of Fernando de Noronha, two journeys each of at least 3000 km. In general, phylogenetic evidence for multiple invasions is less equivocal than that suggesting a single invasion, which is more prone to sampling artefacts. Two alternative hypotheses explaining the presence of Mabuya in both Africa and tropical America are refuted on the basis of molecular clock considerations, namely that the occurrence of Mabuya in these continents pre‐dated their separation over 100 My ago and that it was introduced from one continent to the other by human activities. Like several other lizard groups that have made successful long‐distance transmarine colonizations, Mabuya has done this on many occasions. Phylogenetic results are also compatible with a SE Asian or Australasian origin of Mabuya followed by westward expansion.     

Phytogeographical affinities at the crossroads of two continents: Distribution patterns of Lamiaceae in Chios Island (East Aegean Islands,Greece) and Çeşme–Karaburun Peninsula (West Anatolia,Turkey)

The East Aegean (East Aegean Islands, Greece and West Anatolia, Turkey) is a biogeographically transitional region, where biodiversity elements from Europe and Asia join. However, affinities in the region were until recently scarcely explored. We assess biogeographical affinities in the East Aegean focusing on distribution patterns of Lamiaceae plants in Chios Island and its adjacent Çe?me–Karaburun Peninsula. Detailed in-situ record was acquired for 48 native species. These were grouped based on their habitat and geological substrate preference, their distribution was mapped in grid cells and distribution patterns were analysed in relation to species groupings. In both Chios and Çe?me–Karaburun, species follow five distribution patterns: widespread, locally widespread, locally restricted, sporadic and rare. Fifty to 62% of the species exhibit similar distribution patterns, trends in habitat and geological substrate preference in Chios and Çe?me–Karaburun, results complying with previous evidence of close biogeographical affinities of the East Aegean Islands and neighbouring Anatolia. Differences observed between the two regions may be attributed to insularity effects, human impact and the melange, an old rock matrix known for its key role in elucidating regional geodynamic evolution. Distributions of widespread and locally widespread species in Chios give evidence of density compensation and niche shifts responses, however, the actual occurrence of these phenomena in island plant populations is still to be elucidated. Overall, the species distribution patterns, particularly those of rare ones, reflect the complex geological history, palaeogeography and human influence in the Aegean region.     

Are all Mexican odonate species documented? An assessment of species richness

With the aim of protecting Mexican diversity, one current governmental task is to complete national biological inventories. In the case of odonate insects, several researchers have hypothesized that species richness is complete (205 dragonflies and 151 damselflies), but there has not been any formal exercise to test this. Thus, we have investigated whether odonate species richness (for Mexican endemics, dragonflies (suborder Anisoptera), damselflies (suborder Zygoptera) and total species) is complete using sample-based and coverage-based rarefaction curves. Along with this, we also showed how good distribution data are in the country. The rarefaction curves have indicated 100% completeness for all groups suggesting that the inventory is complete. However, species' distribution data is highly patchy regarding areas either well (e.g. central Mexico) or badly (e.g. coast of Guerrero and Oaxaca) collected. We encourage researchers to continue odonate sampling in order to support at least three conservation actions: (i) conservation assessment of endangered species; (ii) knowledge of range shifts given rising global temperatures; and (iii) increase public interest and awareness in protected, touristic areas.     

The introduction to Japan of the Titan barnacle,Megabalanus coccopoma (Darwin, 1854) (Cirripedia: Balanomorpha) and the role of shipping in its translocation

The Titan Acorn barnacle, Megabalanus coccopoma, a native of the tropical eastern Pacific, has become established in the western Atlantic (Brazil and the northern Gulf of Mexico to the Carolinas), northwestern Europe and the western Indian Ocean (Mauritius), and therefore its dispersal capabilities are well known. This study reports its introduction to Japan and confirms its occurrence in Australia. In an attempt to determine the source of this introduction, phylogeographic techniques, involving cytochrome c oxidase I sequences of various widely separate populations of M. rosa and M. volcano, were utilized. No significant genetic differentiation or haplotype patterns between widely separated populations of each of the three species were found. Lack of such differentiation indicates recent geographical isolation and thus negates a null hypothesis predicting that the occurrence of one of more of these species in Australia was natural.