The phylogeny of the Casque‐headed Treefrogs (Hylidae: Hylinae: Lophyohylini)

The South American and West Indian Casque‐headed Treefrogs (Hylidae: Hylinae: Lophyohylini) include 85 species. These are notably diverse in morphology (e.g. disparate levels of cranial hyperossification) and life history (e.g. different reproductive modes, chemical defences), have a wide distribution, and occupy habitats from the tropical rainforests to semiarid scrubland. In this paper, we present a phylogenetic analysis of this hylid tribe based on sequence fragments of up to five mitochondrial (12S, 16S, ND1, COI, Cytb) and six nuclear genes (POMC, RAG‐1, RHOD, SIAH, TNS3, TYR). We included most of its species (> 96%), in addition to a number of new species. Our results indicate: (i) the paraphyly of Trachycephalus with respect to Aparasphenodon venezolanus; (ii) the nonmonophyly of Aparasphenodon, with Argenteohyla siemersi, Corythomantis galeata and Nyctimantis rugiceps nested within it, and Ap. venezolanus nested within Trachycephalus; (iii) the polyphyly of Corythomantis; (iv) the nonmonophyly of the recognized species groups of Phyllodytes; and (v) a pervasive low support for the deep relationships among the major clades of Lophyohylini, including C. greeningi and the monotypic genera Itapotihyla and Phytotriades. To remedy the nonmonophyly of Aparasphenodon, Corythomantis, and Trachycephalus, we redefined Nyctimantis to include Aparasphenodon (with the exception of Ap. venezolanus, which we transferred to Trachycephalus), Argenteohyla, and C. galeata. Additionally, our results indicate the need for taxonomic work in the following clades: (i) Trachycephalus dibernardoi and Tr. imitatrix; (ii) Tr. atlas, Tr. mambaiensis and Tr. nigromaculatus; and (iii) Phyllodytes. On the basis of our phylogenetic results, we analyzed the evolution of skull hyperossification and reproductive biology, with emphasis on the multiple independent origins of phytotelm breeding, in the context of Anura. We also analyzed the inter‐related aspects of chemical defences, venom delivery, phragmotic behaviour, co‐ossification, and prevention of evaporative water loss.     

Testing Methods: The Evaluation of Discovery Operations in Evolutionary Biology

Scientific discovery requires both abstract, theoretically defined concepts and discovery operations formed by sets of rules that permit the empirical detection of instances of those concepts. In this paper, I examine the ontological status of discovery operations and the tests employed to evaluate them in evolutionary biology. Attention is drawn to the distinction between nomothetic (universal, predictive) and ideographic (historical, retrodictive) discovery operations, and between complementary and exclusive discovery operations. Three types of tests of discovery operations are commonly employed in evolutionary biology. Theoretical tests aim to show that a discovery operation is inconsistent with accepted, well-corroborated, empirical theories. Empirical tests evaluate the performance of competing discovery operations in terms of their results when applied to the same empirical data sets. Philosophical tests aim to show that an operation is inconsistent with logical and epistemological principles. Appropriately designed theoretical and philosophical tests of ideographic discovery operations may be scientifically valid. Empirical tests, however, are incapable of evaluating the scientific merits of competing discovery operations. Nonetheless, empirical comparisons (not tests ) of competing discovery operations may provide insight into the ways discovery operations may be misleading and therefore may play an important role in stimulating critical debate and eventually establishing a scientifically optimal operation. In practice, theoretical and philosophical tests are often combined to test competing discovery operations as rigorously as possible.     

Biotechnological synthesis of ribavirin. Effect of ribavirin and its various combinations on the reproduction of Vaccinia virus

The biotechnological method of synthesis of ribavirin, vidarabin, and 6-azauridine by the use of immobilized recombinant enzymatic preparations of nucleoside phosphorylase was improved. The effect of ribavirin and its combinations with the other synthesized nucleosides on the reproduction of Vaccinia virus was studied using cultures of Vero cells. The combination of ribavirin and vidarabin was shown to provide an antiviral effect at lesser concentrations than when these compounds were taken separately. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 6; see also http://www.maik.ru.     

Spontaneous Resolution and Super-coiling in Xerogels of the Products of Photo-Induced Formose Reaction

This work addresses the supramolecular self-organization in the xerogels of formose reaction products. The UV-induced formose reaction was held in over-saturated formaldehyde solutions at 70^°C without a catalyst. The solutions of the obtained carbohydrates were dried on a glass slide, and the obtained xerogels demonstrated a prominent optical activity, while the initial solutions were optically inactive. The xerogels contained highly elongated crystalline elements of a helical structure as well as the isometric ones. Thus xerogel formation was accompanied by a spontaneous resolution of enantiomers and separation of different-shaped supramolecular structures. The thick helices were twisted of thinner ones, while the latter were twisted of elementary structures having a diameter much smaller than 400 nm. Similar structural hierarchy is typical of biological macromolecules (DNA, proteins, and cellulose). Summarizing the obtained results, we proposed a hypothetical mechanism explaining the amplification of the initial enantiomeric excess, as well as chiral and chemical purification of the substances which were essential for the evolution of Life to start.

     

Phylogeny of Riama (Squamata: Gymnophthalmidae), impact of phenotypic evidence on molecular datasets,and the origin of the Sierra Nevada de Santa Marta endemic fauna

Riama is the most speciose genus of the Neotropical lizard family Gymnophthalmidae. Its more than 30 montane species occur throughout the northern Andes, the Cordillera de la Costa (CC) in Venezuela, and Trinidad. We present the most comprehensive phylogenetic analysis of Riama to date based on a total evidence (TE) approach and direct optimization of molecular and morphological evidence. Analyses use DNA sequences from four loci and 35 phenotypic characters. The dataset consists of 55 ingroup terminals representing 25 of the 30 currently recognized species of Riama plus five undescribed taxa, including an endemic species from the Sierra Nevada de Santa Marta (SNSM) in Colombia, and 66 outgroup terminals of 47 species. Analysis results in a well‐supported hypothesis in which Riama is polyphyletic, with its species falling into three clades. The Tepuian Anadia mcdiarmidi nests within one clade of Riama, and the recently resurrected Pantodactylus nests within Cercosaura. Accordingly, we propose a monophyletic taxonomy that reflects historical relationships. Analysis of character evolution indicates that the presence/absence of prefrontals—a cornerstone of the early genus‐level taxonomy of cercosaurines—is optimally explained as having been plesiomorphically present in the most recent common ancestor of Cercosaurinae and lost in that of the immediately less inclusive clade. Multiple independent reversals to present and subsequent returns to absent occur within this clade. To evaluate the impact of phenotypic evidence on our results, we compare our TE results with results obtained from analyses using only molecular data. Although phenotypic evidence comprises only 1.2% of the TE matrix, its inclusion alters both the topology and support values of the clades that do not differ. Finally, current phylogenetic evidence reveals a SNSM–CC–Trinidad–tepuis biogeographical link. We hypothesize that an ancient connection facilitated the exchange of species between the SNSM and the CC.     

Calculation of the field and current density distributions in a non-self-sustained discharge in the discharge chamber of a CO laser

Two-dimensional spatial distributions of the electric field and current density in a non-self-sustained discharge controlled by a fast electron beam were calculated in the quasineutral plasma approximation. The calculations were carried out for a gas-discharge chamber with an antistreamer electrode grid placed in parallel to the output window of the ionizer. The voltage drop near the grid surface that appears due to the inhomogeneity of the spatial distribution of the current density was calculated. The fraction of the discharge current that passes the grid and flows onto the foil separating the vacuum volume of the ionizer from the gas-discharge chamber was estimated. The dependence of the calculated values on the geometric parameters of the electrode grid and its position with respect to the output of the ionizer was analyzed.     

Synthesis and antibacterial activity of analogues of the N-terminal fragment of the sarcotoxin IA antimicrobial peptide

Three 18-membered analogues of the N-terminal fragment of the sarcotoxin IA cationic antimicrobial peptide were synthesized by the solid phase method of peptide synthesis with the use of swellographic monitoring. The ability of these peptides to inhibit the growth of various bacteria in culture medium and their hemolytic activity in experiments on human erythrocytes were studied. The analogue completely corresponding to the N-terminal amino acid sequence of the natural sarcotoxin IA with the amide group on its C-terminus exhibited higher antibacterial activity. The presence of carboxyl group on the C-terminus or the substitution of Tyr for Trp2 resulted in a decrease in the antimicrobial activity of the peptide. Our results indicate that the amphiphilic N-terminal peptide corresponding to the 1-18 sequence of sarcotoxin IA involves the moieties responsible for the antimicrobial activity of the antibiotic.