(Z,Z)-Selanediylbis(2-propenamides): Novel Class of Organoselenium Compounds with High Glutathione Peroxidase-Like Activity. Regio- and Stereoselective Reaction of Sodium Selenide with 3-Trimethylsilyl-2-propynamides.

The efficient regio- and stereoselective synthesis of (Z,Z)-3,3'-selanediylbis(2-propenamides) in 76-93% yields was developed based on the reaction of sodium selenide with 3-trimethylsilyl-2-propynamides. (Z,Z)-3,3'-Selanediylbis(2-propenamides) are a novel class of organoselenium compounds. To date, not a single representative of 3,3'-selanediylbis(2-propenamides) has been described in the literature. Studying glutathione peroxidase-like properties by a model reaction showed that the activity of the obtained products significantly varies depending on the organic moieties in the amide group. Divinyl selenide, which contains two lipophilic cyclohexyl substituents in the amide group, exhibits very high glutathione peroxidase-like activity and this compound is considerably superior to other products in this respect.

The use of microsatellite markers for species delimitation in Antarctic Usnea subgenus Neuropogon.

Lichens are symbiotic associations consisting of a fungal (mycobiont) and one or more photosynthetic (photobionts) partners and are the dominant component, and most important primary producers, of Antarctic terrestrial ecosystems. The most common lichens in the maritime Antarctic are Usnea antarctica and U. aurantiacoatra, a so-called "species pair" in which U. antarctica shows asexual reproduction and propagation via soredia and U. aurantiacoatra forms ascospores in apothecia. Previous molecular analyses were not able to unambiguously distinguish the two morphotypes as species. Therefore, the goal of this study was to find out whether fast-evolving SSR (single sequence repeat) markers are able to separate morphotypes more clearly and help to clarify their taxonomy. We investigate 190 individuals from five mixed stands of both morphotypes collected in King George Island and Elephant Island (South Shetland Islands, Antarctica). Based on 23 microsatellite markers designed from sequenced genomes, discriminant analysis of principal components (DAPC), Bayesian clustering analysis, and coalescent-based estimation of gene flow show clear evidence for the existence of two different species distinguishable by reproductive mode. We did not detect any statistical association between genetic clusters and three previously reported chemical races of each species.

Diversity of the lichenized fungi in King George Island, Antarctica, revealed by phylogenetic analysis of partial large subunit rDNA sequences.

Lichens are predominant and important components of flora in the terrestrial ecosystem of Antarctica. However, relatively few researches on the phylogenetic position of Antarctic lichen-forming fungi have been accomplished. In this study, partial sequences of nuclear large subunit rDNAs from 50 Antarctic specimens were obtained and the phylogeny was reconstructed. Antarctic lichen species were distributed among 4 orders, including the monophyletic order Agyrales, paraphyletic orders Pertusariales and Teloschistales, and polyphyletic order Lecanorales. Species diversity was highest in the order Lecanorales, followed by Teloschistales and Pertusariales. Based on the phylogeny and sequence similarity analyses, it is proposed that the taxonomy of Stereocaulon alpinum, Physcia caesia, Usnea aurantiacoatra, and Cladonia species should be revised by careful examination of their phenotypic and molecular characteristics. Six species known to be endemic to Antarctica, Catillaria corymbosa, Himantormia lugubris, Leptogium puberulum, Pertusaria pertusa, Rhizoplaca aspidophora, and Umbilicaria antarctica, formed unique lineages, implying independent origins in the Antarctic area.

Lichen flora around the Korean Antarctic Scientific Station, King George Island, Antarctic.

As part of the long-term monitoring projects on Antarctic terrestrial vegetation in relation to global climate change, a lichen floristical survey was conducted around the Korean Antarctic Station (King Sejong Station), which is located on Barton Peninsula, King George Island, in January and February of 2006. Two hundred and twenty-five lichen specimens were collected and sixty-two lichen species in 38 genera were identified by morphological characteristics, chemical constituents, TLC analysis and ITS nucleotide sequence analysis.