The phylogenetic relationships and evolution of the Canarian laurel forest endemicIxanthus viscosus (Aiton) Griseb. (Gentianaceae): Evidence frommatK and ITS sequences, and floral morphology and anatomy

The phylogenetic relationships of the Canarian laurel forest endemicIxanthus viscosus (Aiton) Griseb. (Gentianaceae) are investigated through a cladistic analysis of sequence variation of parts of the chloroplast genematK and the ITS region of nuclear ribosomal DNA. The floral anatomical and morphological characteristics ofIxanthus based on paraffin sections and SEM studies are also discussed. In the molecular analysesIxanthus is part of a clade of mostly temperate Erythraeinae and Chironiinae sensu Gilg, in which it is sister to the mostly Mediterranean annualBlackstonia. This relationship is supported by farreaching similarities in flower morphology and anatomy, and the shared possession of at least some perfoliate leaves. This finding contradicts most former classifications in whichIxanthus was placed either in subtribe Gentianinae which never includedBlackstonia, or in a subtribe of its own which was suggested to connect woody tropical with herbaceous temperate taxa. The phylogenetic relationships found here show that 1) the sister group ofIxanthus is distributed in the Mediterranean area, and that 2) its habit as a basally woody suffrutescent herb is best interpreted as an advanced character state.     

The comparative biology of the closely related Senecio nebrodensis and S. viscosus, a narrow endemic and a widespread ruderal

The closely related Senecio nebrodensis , a perennial herb from four mountain ranges in Spain, and S. viscosus , an annual herb widespread in Europe, are being compared by the study of herbarium material and comparative cultivation. In cultivation, S. nebrodensis behaved as an annual, completing its life cycle within a shorter period of time than S. viscosus . The formation of basal leaf rosettes is much more pronounced in S. nebrodensis than in S. viscosus . The main difference between the two species, however, is their breeding system. While S. nebrodensis is self-incompatible, S. viscosus is self-compatible. Differences in reproductive morphology (mainly size and number of ray florets) are suggested to be related to this difference in breeding system. Despite differences in disc floret number and capitulum number observed in the cultivated material, the potential reproductive output of the two species is roughly comparable. Senecio viscosus is believed to be a descendant of S. nebrodensis . It is postulated that the former differentiated from thelatter at the latest in glacial or early postglacial times. Following postglacial climatic changes, S. nebrodensis retreated into high altitudes, while S. viscosus , adapting to these changes, expanded northwards. The strikingly different degree to which the two species exploit man-made disturbances is interpreted as being due to a difference in opportunity: In its climatically defined range S. nebrodensis experiences little disturbance. Senecio viscosus , on the other hand, inhabits areas strongly disturbed by human activity. It is concluded that S. viscosus shows no obvious adaptations to its habitat, but is well preadapted.     

From descriptive to predictive distribution models: a working example with Iberian amphibians and reptiles

Background

The two sympatric species of Tunisian desert ants, Cataglyphis bicolor and C. mauritanica, do not exhibit any differences in their foraging ecology, e.g. in food preferences and in their spatial and temporal activity patterns. Here we show that instead the two species markedly differ in their life histories.

Results

We analysed mtDNA of specimens that were collected along a 250-km transect. C. bicolor exhibited a genetically unstructured population (with the genetic and geographic distances among colonies not being correlated). On the contrary the populations of the polygynous C. mauritanica were clearly structured, i.e. exhibited a strong correlation between genetic and geographic distances. This difference is in accordance with large queen dispersal distances due to far-reaching mating flights in C. bicolor and small queen dispersal distances due to colony foundation by budding in C. mauritanica. Furthermore, wherever we found populations of both species to coexist within the same habitat, the habitat was used agriculturally. Mapping nest positions over periods of several years showed that plowing dramatically decreased the nest densities of either species.

Conclusion

We conclude that owing to its greater queen dispersal potential C. bicolor might be more successful in quickly re-colonizing disturbed areas, while the slowly dispersing C. mauritanica could later out-compete C. bicolor by adopting its effective nest-budding strategy. According to this scenario the observed sympatry of the two species might be an intermediate stage in which faster colonization by one species and more powerful exploitation of space by the other species have somehow balanced each other out. In conclusion, C. bicolor and C. mauritanica represent an example where environmental disturbances in combination with different life histories might beget sympatry in congeneric species with overlapping niches.     

Colocalization within the nucleolus of two highly related IFN-induced human nuclear phosphoproteins with nucleolin.

We have previously reported the identification of two interferon (IFN)-induced cDNAs which code for two proteins, named 41 and 75, which have homology to a number of proteins involved in regulating gene expression. Here we establish that these cDNAs correspond to in vivo synthesized mRNAs. Expression of the 41 and 75 cDNAs, both in vitro and in vivo, generated proteins of 30 and 68 kDa, respectively. In a variety of mammalian cells, 41 and 75 were found to be located in the nucleus, with 41 being localized to the nucleolus, whereas 75, although it is mainly concentrated at the periphery of the nucleolus, is also found throughout the nucleoplasm. Treatment with interferon results in a translocation of 41 to the periphery of the nucleolus and it is in this region that the two proteins colocalize. 41 and 75 were found to colocalize with nucleolin but not with B23 or fibrillarin, three nucleolar proteins involved in ribosome synthesis. This colocalization was not affected by low concentrations of actinomycin D. In view of this and since 41 and 75 have homology to proteins involved in regulating gene expression, we suggest that, in association with nucleolin, they play a role in ribosome biogenesis.     

Genetic evidence for divergent selection on Oenanthe conioides and Oe. aquatica (Apiaceae), a candidate case for sympatric speciation

The opportunity for habitat shift in sympatry is thought to be an important factor in sympatric speciation by facilitating assortative mating and offering opportunities for divergent selection. Oenanthe conioides (Apiaceae) is a narrow endemic from the lower Elbe river area (Germany) where it is restricted to areas experiencing fresh water tides inundating the plants twice a day. The species was shown to have originated from Oe. aquatica which is widely distributed in Europe and grows in still or slowly flowing fresh water. Reciprocal transplant experiments have previously shown that in both habitats the non‐native species is less fit than the native, and several phenotypic traits have been linked to this difference in fitness. We performed an amplified fragment length polymorphism genome scan with 333 polymorphic markers searching for candidate markers for divergent selection. A relatively small fraction (2.1%) of the markers was identified as divergence outliers which fits theoretical expectations for speciation with gene flow. Some of the markers that were potentially under divergent selection showed evidence of being clustered in the genome. This suggests that there may have been a role for mechanisms that reduce breaking‐up of trait complexes in the speciation process. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 50–56.     

Inhibition of mTOR affects protein stability of OGT

Autophagy regulates cellular homeostasis through degradation of aged or damaged subcellular organelles and components. Interestingly, autophagy-deficient beta cells, for example Atg7-mutant mice, exhibited hypoinsulinemia and hyperglycemia. Also, autophagy response is diminished in heart of diabetic mice. These results implied that autophagy and diabetes are closely connected and affect each other. Although protein O-GlcNAcylation is up-regulated in hyperglycemia and diabetes, and O-GlcNAcylated proteins play an important role in metabolism and nutrient sensing, little is known whether autophagy affects O-GlcNAc modification and vice versa. In this study, we suppressed the action of mTOR by treatment of mTOR catalytic inhibitors (PP242 and Torin1) to induce autophagic flux. Results showed a decrease in global O-GlcNAcylation, which is due to decreased OGT protein and increased OGA protein. Interestingly, knockdown of ATG genes or blocking of lysosomal degradation enhanced protein stability of OGT. In addition, when proteasomal inhibitor was treated together with mTOR inhibitor, protein level of OGT almost recovered to control level. These data suggest that mTOR inhibition is a more efficient way to reduce protein level of OGT rather than that of CHX treatment. We also showed that not only proteasomal degradation regulated OGT stability but autophagic degradation also affected OGT stability in part. We concluded that mTOR signaling regulates protein O-GlcNAc modification through adjustment of OGT stability.     

Salicornia L. (Amaranthaceae) in South Africa and Namibia: rapid spread and ecological diversification of cryptic species

In Salicornia, morphology does not provide reliable diagnostic characters supporting the true extent of evolutionary divergence in the genus, and species concepts have been challenged by molecular analyses. Here, we report the results of an analysis of 91 accessions of the S. meyeriana complex from South Africa and Namibia using the measurements of 38 morphological traits and external transcribed spacer (ETS) sequence data. Morphological data were analysed using discriminant analysis, principal coordinate analysis and nonmetric multidimensional scaling. Phylogenetic divergence was compared with the geographical and ecological diversity of the sampled populations. Tree topology corresponds to geography and ecology, but not to morphology. Most clades have distinct distribution areas and ecological profiles related to tidal, supratidal or inland saline habitats. Salicornia probably diversified in habitats that have experienced regular fragmentation by marine transgression/regression cycles during the Pleistocene. We suggest that this radiation produced young, but genetically, geographically and ecologically well‐defined lineages. The lack of morphological signal reveals the existence of cryptic species in Salicornia and demonstrates the necessity of using molecular data to define taxa in this genus. We propose the recognition of two subspecies in the S. meyeriana complex: S. meyeriana subsp. meyeriana and S. meyeriana subsp. knysnaensis. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172 , 175–186.     

Three new species of <Emphasis Type="Italic">Sarcocornia</Emphasis> (Chenopodiaceae) from South Africa

Sarcocornia decussata, S. freitagii and S. tegetaria from South Africa are described as new taxa. Sarcocornia decussata and S. freitagii are narrow endemics of the West Coast of South Africa where they are found in inland saline habitats (quartz patches, salt pans and saline alluvia) while S. tegetaria is an endemic of southern African coasts (spanning Namibia, South Africa and Mozambique) where it is confined to low-lying intertidal habitats of estuaries.