Functional and Structural Chromosome Analyses in Autotetraploid Silene latifolia

Recent immunocytological and molecular data show that heterochromaticnuclear regions, both constitutive and facultative, are modifieddifferently (cytosine hypermethylation and histone hypoacetylation)and late replicating, when compared to euchromatin. Intrusiveand/or additive (supernumerary) DNA sequences are often functionallysilenced; this is accompanied by their heterochromatinization.In this work we present a number of karyological studies onautotetraploid female cells of Silene latifolia (syn. Melandriumalbum). Immunofluorescence analyses do not indicate any globaldifferences in DNA methylation, histone H4 acetylation, andchromosome replication patterns which could arise as a consequenceof the duplication of the whole chromosome set of the originaldiploid genome. Similarly, the number of silver-positive nucleoliroughly correlates to the ploidy level. Early replication andH4 hyperacetylation have been detected at all subterminal chromosomeregions. This, together with cDNA in situ hybridization patterns,indicates the localization of gene-rich regions. DNA methylationand chromosome replication patterns, but not histone H4 acetylation,show differences among the four X chromosomes present: one tothree X chromosomes were observed as hypermethylated and/orlate replicating. Taken together, the data demonstrate thatthere is no overall silencing of the additional two sets ofautosomes in the tetraploid cells, but the X chromosomes couldbe subject to an irregular dosage compensation. Copyright 1999Annals of Botany Company DNA methylation, histone acetylation, polyploidy, replication patterns, sex chromosomes, Silene latifolia (syn.Melandrium album ).     

Multiple origins of viviparity,or reversal from viviparity to oviparity? The European common lizard (Zootoca vivipara,Lacertidae) and the evolution of parity

The evolution of viviparity in squamates has been the focus of much scientific attention in previous years. In particular, the possibility of the transition from viviparity back to oviparity has been the subject of a vigorous debate. Some studies have suggested this reversal is more frequent than previously thought. However, none of them provide conclusive evidence. We investigated this problem by studying the phylogenetic relationships between oviparous and viviparous lineages of the reproductively bimodal lizard species Zootoca vivipara . Our results show that viviparous populations are not monophyletic, and that several evolutionary transitions in parity mode have occurred. The most parsimonious scenario involves a single origin of viviparity followed by a reversal back to oviparity. This is the first study with a strongly supported phylogenetic framework supporting a transition from viviparity to oviparity.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 1–11.     

Early Cretaceous record of microboring organisms in skeletons of growing corals

Ko?odziej, B., Golubic, S., Bucur, I.I., Radtke, G. & Tribollet, A. 2011: Early Cretaceous record of microboring organisms in skeletons of growing corals. Lethaia, Vol. 45, pp. 34–45. A spectacularly preserved assemblage of microbial euendoliths, penetrating into skeletons of growing scleractinian corals, has been recognized in Early Aptian (Early Cretaceous) reef limestone of the Rar?u Mountains (East Carpathians, NE Romania). Microboring euendolithic filaments were found in five coral colonies of the suborder Microsolenina. They remained in part well‐preserved, often impregnated with iron oxides, which made them visible even in strongly recrystallized parts of coral skeletons. Filaments of a wide range of sizes (2–40 μm in diameter) were concentrated within medium parts of coral septa, oriented along the septa in the direction of the coral growth. The larger filaments were tubular, occurring in bundles and branched into finer, often tapering branches. Their behaviour and organization were quite similar to the modern euendolithic siphonalean chlorophyte Ostreobium. Filament diameters exceeded those reported for the modern species, but covered a similarly wide size range. Narrower frequently branching filaments, 4–8 μm in diameter, resemble distal branching patterns of modern Ostreobium quekettii. Some very thin filaments (ca. 1–2 μm) observed within skeleton or inside the large tubular filaments, sometimes associated with globular swellings, may represent euendolithic fungi. The recrystallization of coral skeleton had limited effect on preservation of euendoliths due to their impregnation with iron oxides; microbial euendoliths were subjected to different taphonomic changes. □Chlorophytes, Early Cretaceous, fungi, microbial euendoliths, Romania, scleractinian corals.     

Forest snail faunas from Transylvania (Romania) and their relationship to the faunas of Central and Northern Europe

Forty‐three forest sites in seven sampling areas in mountainous parts of Transylvania were sampled to obtain inventories of their snail faunas, and to make comparisons between these and the faunas of similar sites further north along the Carpathian chain. Sampling areas ran from close to the Ukrainian border in the north to Retezat in the south‐west. Altogether, 83 species were found, as well as between 19 and 40 species at individual sites. Sites within the same sampling area had more species in common than in among‐area comparisons, although differences between areas did not relate to the distance between them. Such differences appear to be related more to ecological factors than to geography. Faunas of all areas were very similar to those recorded from the Polish and Ukrainian Carpathians; distance from these northern faunas had little effect on similarity. More broadly, the fauna of these forests shows a much greater affinity to those of countries to the north than to those of countries to the south. Despite the survival of forests through the last glacial period of the Pleistocene, and the greater proximity to potential Mediterranean refugia, these faunas appear to be mainly a subset of those found further north. They represent a rather small proportion of the known Romanian fauna, in which there are many endemics restricted to other habitats. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 471–479.