Comparación de diferentes métodos de extracción de ADN genómico en babosas plagas (mollusca: gasterópoda)

La presente investigación fue planteada con el objetivo de comparar tres métodos de extracciónde ADN en muestras de tejido epitelial de babosa (Mollusca: Gasterópoda). Se utilizaron losprotocolos: (1) Extracción con SDS (SDS); (2) Extracción con CTAB y 2β-mercaptoetanol (CTABβ); y (3) Extracción con SDS y proteinasa K (SDSpK); para determinar el método más apropiadode obtención de ADN, de alto peso molecular y pureza, para ser utilizado en análisis genético.Se utilizó la especie de babosa (Arion subfuscus) y seis repeticiones, para un total de 18observaciones. La concentración y pureza del ADN se estimó espectrofotométricamentemidiendo su absorbancia a 260 nm y la relación Abs260/Abs280 nm, respectivamente. Esos datosfueron utilizados para realizar el análisis estadístico, de acuerdo a un diseño completamente alazar con seis repeticiones. En el análisis de la varianza se detectaron diferencias significativas(p<0,01) para la cantidad, concentración y pureza entre los protocolos. En la prueba decomparación entre medias de Tukey, el protocolo (SDSpK) permitió obtener ADN con mayorpeso molecular (2 514,90±291,56) y pureza (1,97±0,02). La calidad del ADN de cada protocolofue verificada mediante PCR-RAPD. Se observó poca reproducibilidad para el cebador OPA-02,del ADN obtenido mediante el procedimiento de extracción SDS; mientras que en los otrosmétodos se logró obtener ADN sin degradación y puro, lo cual permitió observar perfiles deamplificación de alta resolución y bandas reproducibles. Se recomienda utilizar el protocolo(SDSpK) para la obtención de ADN genómico de alto peso molecular, calidad y pureza enbabosas.

Elasticity and energy dissipation in the double network hydrogel adhesive of the slug Arion subfuscus

The slug Arion subfuscus produces a mucus-based defensive secretion that is remarkably tough. This glue appears to be a double network hydrogel, gaining its toughness through the synergistic actions of two networks of polymers, a relatively stiff network and a relatively deformable network. The double network mechanism has great potential to guide the development of synthetic adhesives. Mechanical tests were performed to analyse key predictions of the mechanism. Stress relaxation tests and tensile tests support the presence of stable cross-links. Cyclic stress–strain tests demonstrate that the glue dissipates a great deal of energy through the failure of these cross-links as sacrificial bonds. Energy dissipation by failure of sacrificial bonds rather than viscous processes is supported by the minimal effect of the time course of the experiments on the measured properties. These sacrificial bonds appear able to reform within minutes after failure. Finally, the glue's stiffness decreases at pH values below 5.5, whereas magnesium and calcium rapidly dissociate from the glue at all pH values tested. Thus, these ions may not be the primary cross-linkers generating the glue's stiffness. This article is part of the theme issue ‘Transdisciplinary approaches to the study of adhesion and adhesives in biological systems’.

A discreet invasion: distribution, origins, and expansion of the European slug complex Arion subfuscus s.l. in Quebec

Accurate identification of species and their geographic origins is crucial to assess the impacts of exotic species. This is particularly relevant when multiple introductions are suspected. Species complexes are therefore problematic, as different species can be treated as a single taxon. The highly diversified European complex Arion subfuscus (Draparnaud, 1805) s.l. is abundant throughout northeastern North America. However, surveys performed in the United States have reported a low mitochondrial diversity associated with a single species. To assess whether regions characterized by different human activities harbor different diversities, the taxonomic identities, distributions, and origins of the species of this complex in Quebec (Canada) were determined. The mitochondrial 16S rDNA gene was analyzed in 526 specimens from 69 locations. Both Arion fuscus (O.F. Müller, 1774) and Arion subfuscus (Draparnaud, 1805) s. str. (lineages S1 and S2) were detected. Arion fuscus was the most abundant species, contrasting with previous studies conducted in North America. An explosive range expansion occurred during the last 50 years. Moreover, the presence of different haplotypes confirmed multiple introductions of these species. These results emphasize the importance of not considering an exotic species complex as a single taxon, especially in regions with different human activities.

Are Non-Native Gastropods a Threat to Endangered Lichens?

Extensive grazing by gastropods was found on endangered Boreal Felt Lichen (Erioderma pedicellatum) at Sixth Lake, Nova Scotia, in 2004. At least 80% of arboreal gastropods observed at the site were the introduced species Arion subfuscus. Subsequent surveys at five other locations in Nova Scotia showed 90% of arboreal gastropod individuals observed were introduced species. Potential impact on native lichen species, and in particular on rare and endangered species, is discussed.

Měkkýši NPR Strabišov – Oulehla u Litenčic (jižní Morava, Česká republika) [Molluscs of the Strabišov – Oulehla National Nature Reserve near Litenčice village (South Moravia, Czech Republic)]

The paper presents an inventory of molluscan fauna of the Strabišov-Oulehla NNR near the village of Litenčice (South Moravia, Czech Republic). This is the first report concerning Mollusca of this reserve. Altogether 32 mollusc species have been recorded during years 2004-2005. Forest fringe vegetation, Carpathian Oak – Hornbeam forest, broad – leaved dry grassland and riparian vegetation- habitats were investigated. The species Cepaea vindobonensis, Xerolenta obvia, Granaria frumentum, Chondrula tridens, and Euomphalia strigella were recorded in broad-leaved dry grassland habitats, thermophilous oak forests and Carpathian Oak – Hornbeam forests which were inhabited by Monachoides incarnatus, Alinda biplicata, Merdigera obscura, Fruticicola fruticum, Limax cinereoniger, and Arion subfuscus, on the moister places Carychium tridentatum and Columella edentula was also found. The forest fringe vegetation was a habitat of Euomphalia strigella, Cepaea vindobonensis, Xerolenta obvia, and Helix pomatia; in riparian vegetation of the nameless tributary of the Litava River Trichia hispida, Helix pomatia, Monachoides incarnatus, Arion silvaticus, Laciniaria plicata, Cochlicopa lubrica were also recorded.