Mitochondrial sequence analysis of Salamandra taxa suggests old splits of major lineages and postglacial recolonizations of central Europe from distinct source populations of Salamandra salamandra

Representatives of the genus Salamandra occur in Europe, Northern Africa and the Near East. Many local variants are known but species and subspecies status of these is still a matter of dispute. We have analysed samples from locations covering the whole expansion range of Salamandra by sequence analysis of mitochondrial D-loop regions. In addition, we have calibrated the rate of divergence of the D-loop on the basis of geologically dated splits of the closely related genus Euproctus. Phylogenetic analysis of the sequences suggests that six major monophyletic groups exist (S. salamandra, S. algira, S. infraimmaculata, S. corsica, S. atra and S. lanzai) which have split between 5 and 13 million years ago (Ma). We find that each of the Salamandra species occupies a distinct geographical area, with the exception of S. salamandra. This species occurs all over Europe from Spain to Greece, suggesting that it was the only species that has recolonized Central Europe after the last glaciation. The occurrence of specific east and west European haplotypes, as well as allozyme alleles in the S. salamandra populations suggests that this recolonization has started from at least two source populations, possibly originating in the Iberian peninsula and the Balkans. Two subpopulations of S. salamandra were found that are genetically very distinct from the other populations. One lives in northern Spain (S. s. bernardezi) and one in southern Italy (S. s. gigliolii). Surprisingly, the mitochondrial lineages of these subpopulations group closer together than the remainder S. salamandra lineages. We suggest that these populations are remnants of a large homogeneous population that had colonized Central Europe in a previous interglacial period, approximately 500 000 years ago. Animals from these populations were apparently not successful in later recolonizations. Still, they have maintained their separate genetic identity in their areas, although they are not separated by geographical barriers from very closely related neighbouring populations.

Serum neuron-specific enolase as early predictor of outcome after cardiac arrest

OBJECTIVE

To examine the prognostic value of serum neuron-specific enolase for early prediction of outcome in patients at risk for anoxic encephalopathy after cardiac arrest.

DESIGN

Prospective study.

SETTING

Coronary intensive care unit of the University of Heidelberg.

PATIENTS

Forty-three patients (66.8 +/- 12.7 [SD] yrs, range 33 to 85) who had had either primary or secondary cardiac arrest, followed by cardiopulmonary resuscitation (CPR).

INTERVENTIONS

Serial blood samples and clinical examinations.

MEASUREMENTS AND MAIN RESULTS

Serum neuron-specific enolase concentrations were determined after CPR on 7 consecutive days. Twenty-five patients remained comatose and subsequently died; 18 patients survived the first 3 months and had no relevant functional deficit at 3-month follow-up. Neuron-specific enolase concentrations were correlated with neurologic outcome. Concentrations of >33 ng/mL predicted persistent coma with a high specificity (100%) and a positive predictive value of 100%. Overall sensitivity was 80%, with a negative predictive value of 78%. Serum concentrations of neuron-specific enolase exceeded this cutoff value no more than 3 days after cardiac arrest in 95% of patients in whom these concentrations had exceeded 33 ng/mL.

CONCLUSIONS

In patients who have been resuscitated after cardiac arrest, serum neuron-specific enolase concentrations of >33 ng/mL predict persistent coma with a high specificity. Values below this cutoff level do not necessarily indicate complete recovery, because this method has a sensitivity of 80%.

Cyclische Diazastannylene, XVI [1]. Ringe und Käfige mit Ge(II), Sn(II) und Pb(II) / Cyclic Diazastannylenes, XVI [1]. Rings and Cages with Ge(II), Sn(II) and Pb(II)

1,3-Di-tert-butyl-2,2-dimethyl-1,3,2,4λ2-diazasilagermetidine (1) and its lead analogue (3), which have been synthesized from the dichlorides of germanium and lead and the dilithium salt of bis(tert-butylamino)dimetliylsilane, are compared with the corresponding tin compound 2 in their reactivity towards tert-butylamino. There is a clear dependence of the reaction rate on the nature of the element. The norcubane-like cage Ge3(NtBu)4H2 (5 a) and the cubane-like cages Ge4(NtBu)4 (6a) and Pb4(NtBu)4 (6c) result from these reactions. When 3 is treated with bis(methylamino)dimethylsilane, [(Me2Si)2(MeN)3Pb]n (7) precipi­tates from the reaction mixture. Sn3(NtBu)4H2 (5b) can be transformed into Sn3(NtBu)4Ge (8a) and Sn3(NtBu)4Pb (8b) when heated at high temperatures with 1 or 3, respectively. In these polycyclic compounds two low-valent elements of group IV are simultaneously present in one cage unit. As can be shown, 8b is less stable to bond cleavage than 8a and undergoes redistribution reactions at elevated temperatures to form Sn4(NtBu)4 (6b), Sn2Pb2(NtBu)4 (9). SnPb3(NtBu)4 (10) and Pb4(NtBu)4 (6c).

Climatic oscillations triggered post-Messinian speciation of Western Palearctic brown frogs (Amphibia, Ranidae)

Oscillating glacial cycles over the past 2.4 million years are proposed to have had a major impact on the diversity of contemporary species communities. We used mitochondrial and nuclear DNA sequence data to infer phylogenetic relationships within Western Palearctic brown frogs and to test the influence of Pliocene and Pleistocene climatic changes on their evolution. We sequenced 1976bp of the mitochondrial genes 16S rRNA and cytochrome b and of the nuclear rhodopsin gene for all current species and subspecies. Based on an established allozyme clock for Western Palearctic water frogs and substitution rate constancy among water frogs and brown frogs, we calibrated a molecular clock for 1425bp of the 16S and rhodopsin genes. We applied this clock to date speciation events among brown frogs. Western Palearctic brown frogs underwent a basal post-Messinian radiation about 4 million years ago (mya) into five major clades: three monotypic lineages (Rana dalmatina, Rana latastei, Rana graeca), an Anatolian lineage, and a lineage comprising Rana italica, Rana arvalis, and all Iberian taxa. Polytypic lineages radiated further in concordance with the onset of climatic oscillations ca. 3.2, 2.0, and 1.0-0.6 mya, respectively. The dated fossil record corroborates our paleobiogeographic scenario. We conclude that drastic climatic changes followed by successive temperature oscillations "trapped" most brown frog species in their southern European glacial refugia with enough time to speciate. Substantial dispersal was only possible during extensive interglacial periods of a constant subtropical climate.

Phylogeny and classification of poison frogs (Amphibia: dendrobatidae), based on mitochondrial 16S and 12S ribosomal RNA gene sequences

An analysis of partial sequences of the 16S ribosomal rRNA gene (582 bp) of 20 poison frog species (Dendrobatidae) confirmed their phylogenetic relationships to bufonid and leptodactylid frogs. Representatives of the ranoid families and subfamilies Raninae, Mantellinae, Petropedetinae, Cacosterninae, Arthroleptidae, Astylosternidae, and Microhylidae did not cluster as sister group of the Dendrobatidae. Similar results were obtained in an analysis using a partial sequence of the 12S gene (350 bp) in a reduced set of taxa and in a combined analysis. Within the Dendrobatidae, our data supported monophyly of the genus Phyllobates but indicated paraphyly of Epipedobates and Colostethus. Minyobates clustered within Dendrobates, contradicting its previously assumed phylogenetic position. Phobobates species clustered as a monophyletic unit within Epipedobates. Allobates was positioned in a group containing two Colostethus species, indicating that lack of amplexus, presence of skin alkaloids, and aposematic coloration evolved independently in Allobates and the remaining aposematic dendrobatids.

Cyclische Diazastannylene, III1 Die Kristall-und Molekülstruktur der monoklinen Phase von 1.3-Di-tert-butyl-2.2-dimethyl-1.3.2.4λ2 -diazasilastannetidin / The Crystal and Molecular Structure of the Monoclinic Phase of 1,3-Di-feri-butyl-2,2-dimethyl-1,3,2,4λ2 -diazasilastannetidine

The crystal and molecular structure of the monoclinic phase of 1,3-di-tert-butyl-2,2-dimethyl-1,3,2,4λ2 -diazasilastannetidine has been determined from three-dimensional X-ray data collected on a two-circle diffractometer at -120 °C (MoKa radiation, 2623 reflexions, R - 0,050). The crystals are monoclinic, space group C2/c, with cell dimensions a = 10.655(5), b = 25.75(1), c = 17.33(1) Å, β = 106.8(1)° and Z = 12. Four monomeric (crystal site symmetry 2 (C2)) and four dimeric units (crystal site symmetry 1̄ (Ci)) are present in the structure interacting over tin-tin (3.68 Å). Remarkable are the very short Sn-N bond (2.09 Å) in the monomer and the donation bond Sn-N (2.39 Å) in the dimer. The coordination of the tin atoms in the different units is discussed in detail.

Palaeoclimatic changes explain Anatolian mountain frog evolution: a test for alternating vicariance and dispersal events

Holarctic biodiversity has been influenced by climatic fluctuations since the Pliocene. Asia Minor was one of the major corridors for postglacial invasions in the Palearctic. Today this area is characterized by an extraordinarily rich fauna with close affiliation to European, Asian and Indo-African biota. However, exact scenarios of range expansion and contraction are lacking. Using a phylogeographical approach we (i). identify monophyletic lineages among Anatolian mountain frogs and (ii). derive a spatio-temporal hypothesis for the invasion process in Anatolia. We sequenced 540 bp of the mitochondrial 16S rRNA gene from 40 populations of mountain frogs from Anatolia, the Elburz Mountains and the Caucasus. Our samples comprise all known species and subspecies: Rana macrocnemis macrocnemis, R. m. tavasensis, R. m. pseudodalmatina, R. camerani and R. holtzi. They include the type localities of four of these taxa. We used a nested clade analysis (NCA) to infer historical and recurrent events that account for the observed geographical distribution of haplotypes. None of the extant species is monophyletic. Based on a molecular clock calibration using homologous sequences of Western Palearctic water frogs of the same genus, we estimated that a basic radiation into three lineages c. 2 Mya was followed by several dispersal and fragmentation events. The geographical distribution of resident and widespread haplotypes allows us to infer and date scenarios of range expansion and fragmentation that are aligned with dramatic climatic oscillations that have occurred during the last 600000 years. Consequently, Pliocene and Pleistocene climatic oscillations triggered the evolution of Anatolian mountain frogs through an interplay of vicariance and dispersal events.

The role of swarming sites for maintaining gene flow in the brown long-eared bat (Plecotus auritus)

Bat-swarming sites where thousands of individuals meet in late summer were recently proposed as 'hot spots' for gene flow among populations. If, due to female philopatry, nursery colonies are genetically differentiated, and if males and females of different colonies meet at swarming sites, then we would expect lower differentiation of maternally inherited genetic markers among swarming sites and higher genetic diversity within. To test these predictions, we compared genetic variance from three swarming sites to 14 nursery colonies. We analysed biparentally (five nuclear and one sex-linked microsatellite loci) and maternally (mitochondrial D-loop, 550 bp) inherited molecular markers. Three mtDNA D-loop haplolineages that were strictly separated at nursery colonies were mixed at swarming sites. As predicted by the 'extra colony-mating hypothesis', genetic variance among swarming sites (V(ST)) for the D-loop drastically decreased compared to the nursery population genetic variance (V(PT)) (31 and 60%, respectively), and genetic diversity increased at swarming sites. Relatedness was significant at nursery colonies but not at swarming sites, and colony relatedness of juveniles to females was positive but not so to males. This suggests a breakdown of colony borders at swarming sites. Although there is behavioural and physiological evidence for sexual interaction at swarming sites, this does not explain why mating continues throughout the winter. We therefore propose that autumn roaming bats meet at swarming sites across colonies to start mating and, in addition, to renew information about suitable hibernacula.

Cyclische Diazastannylene, XXX [1] Symmetrisch und asymmetrisch substituierte German- und Stannandiyle mit Amid-, Alkoholat- und Thiolat-Liganden, Teil I [2] / Cyclic Diazastannylenes, XXX [1] Symmetrically and Asymmetrically Substituted Germane- and Stannanediyls with Amide, Alcoholate and Thiolate Ligands, Part I [2]

Chelates of Ge(II) and Sn(II)

Symmetrically and unsymmetrically substituted germane- and stannanediyls as well as chelated bis(amino)- or aminooxogermanium- and -tinmonohalides have been obtained from cyclic bis(amino)germane- and stannanediyls by treatment with tert-butylamine, tert-butanol and tert-butylmercaptane. The following compounds have been synthesized: GeX2 (X = OtBu (5), StBu (6)), Sn(StBu), (9), GeXCl (X = N(H)tBu (21), OtBu (22)), SnXCl (X = N(H)tBu (23), OtBu (24), StBu (25), OMe (28)) and Sn(OtBu)Br (27). In the series of the chelates Me2Si(NtBu)(NHtBu)GeCl (13), Me2Si(NtBu)(OtBu)SnX (X = Cl (18), OMe (19)) and the bischelate [Me2Si(NtBu)(OtBu)]2Sn (20) have been prepared. When 18 is allowed to react with aluminiumtrimethyl Me2Si(NtBu)(OtBu)AlClMe is formed, a compound with a center of chirality at the aluminium atom. X-ray structure determinations have been performed on single crystals of 6, 8, 9, 13, 22 and 24. 6, 8, 22 and 24 form molecular dimers with c.n. of 3 at the Ge or Sn atoms, resp. While the tBu-S ligands are syn with respect to the central Ge2S2 ring in 6 (symmetry approaching C2v), the tBu-O ligands are anti to the central Sn2O2 ring in 8 (symmetry Ci). 9 forms a coordination polymer with all Sn atoms in a Ψ-trigonal-bipyramidal and all S atoms in a Ψ-tetrahedral environment. The germanium atom in 13 is coordinated by a chlorine, a λ3- and a λ4-nitrogen atom, the two nitrogen atoms being connected by as dimethylsilyl group. The hydrogen and chlorine atom of 13 are found at the same side of the four-membered chelate ring. The two unsymmetrically substituted, homologous compounds Ge(O/tBu)Cl (22) and Sn(OtBu)Cl (24) are found to form dimers via O→Ge resp. O→Sn bonds. While the chlorine atoms in 22 are syn with respect to the four-membered ring, they are anti in the case of molecule 24.

Alkoxistannate, II [1] Tri(tert-butoxi)alkalistannate(II): Darstellung und Strukturen / Alkoxistannate, II [1] Tri(tert-butoxi)alkalistannates(II): Synthesis and Structures

Tri(tert-butoxi)alkalistannates (M(O'Bu)3Sn, M = Li, Na, K, Rb, Cs) are obtained by reaction of alkali-fert-butanolates with tindi-tert-butoxide. If M equals Li or Na (1, 2) molecular com pounds are formed, which consist of two formula units. 1 crystallizes in a m onoclinic cell (space group P21/c; a = 966.5(3), b = 1819(1), c = 1014(1) pm. β = 107.1(1)°, Z = 4); 2 is triclinic (space group P1̄; a = 1041(1), b = 2046(1), c = 1033(1) pm. a = 92.3(2), β = 118.6(1), y = 108.3(3)° and Z = 4). The molecules 1 and 2 are closely related structurally despite their different space groups. The common structural feature is a Sn2O6M2 cage, which is built of two seco-norcubane Sn2M2O , units, sharing a M2O2 four-membered ring. Characteristic distances are: 1: Sn-O = 209.3, L i-O = 193.0 and 211.6 pm, 2: Sn-O = 210.5, Na-O = 227.4 and 240.7 pm. The tert/-butoxistannates of K, Rb and Cs (3, 4, 5) all crystallize in the orthorhombic crystal system, space group P212121 (cell constants of 3: a = 1907(1), b - 1060(1), c - 896(1) pm, Z = 4). Contrary to the lithium- and sodium derivates 3, 4 and 5 have a polymeric structure. The one dimensional polymer consists of distorted trigonal bipyramidal SnO3M “cages” (substituted at the oxygen atoms by tertbutyl groups), which align in a way to allow the metal atom to have a five-fold oxygen coordination. The tin atoms have trigonal pyramidal coordination. While the tin-oxygen bond lengths are essentially invariant (average value 206.7 pm ), the potassium-oxygen distances range from 256.4(5) pm to 318.8(6) pm

Cyclische Diazastannylene, II1 Intermolekulare Lewis-Säure-Base-Addukte bei 1.3.2.4λ2 -Diazasilastannetidinen / Cyclic Diazastannylenes, II1 Intermolecular Lewis-Acid-Base Adducts of 1, 3,2,4λ 2 -Diazasilastannetidines

1,3-Diorganyl-2,2-dimethyl-I,3,2,4λ2-diazasilastannetidines can be prepared as monomers (organyl = tert-butyl) or dimers (organyl = isopropyl) in nonpolar solvents, depending on the organic nitrogen substituent. The formation of the dimer, which is due to an intermolecular Lewis-acid-base interaction of Sn(II) with nitrogen, can be initiated by solidification. When the tertf-butyl compound is cooled below 0 °C two crystalline modifications are found: a monoclinic phase (C 2/c; a= 10.655(5); b = 24.75(1); c = 17.334(9) Å; β = 106.9(1)°) and a triclinic phase (P1̄; a = 10.68(1); b = 13.51(1); c = 12.36(1) Å; α = 96.2(1); β = 102.6(1); γ = 118.4(1)°). The crystal structures turn out to be built of dimeric and monomeric units in the first case and presumably only dimeric species in the second case. The isopropyl derivative crystallizes in the space group P 21/b (a = 10.77(1); b= 12.14(2); c = 11.15(2) Å; β = 120.2(2)°) with only dimeric units being present, as in the liquid. Interrelationships between the three structures are discussed.

First data on the molecular phylogeography of scincid lizards of the genus Mabuya

A 487-bp fragment of the mitochondrial 16S rRNA gene was sequenced in 26 species of the circumtropical lizard genus Mabuya and used to analyze phylogenetic relationships within the genus. The species from Africa and Madagascar formed a monophyletic group relative to the included Asian and South American taxa. The Malagasy species included (M. elegans, M. cf. dumasi, and M. comorensis) did not appear as a monophylum. Combined and separate analysis of the 16S data and additional sequences of the mitochondrial 12S rRNA, ND4, and cytochrome b genes (a total of 2255 bp) in one Asian, two Malagasy, and two African species also did not result consistently in a monophyletic grouping of the Malagasy taxa. However, a monophylum containing African and Malagasy taxa was strongly supported by the combined analysis. These preliminary results indicate that Mabuya probably colonized Madagascar from Africa through the Mozambique Channel.

Synthesis and evaluation of 17-aliphatic heterocycle-substituted steroidal inhibitors of 17alpha-hydroxylase/C17-20-lyase (P450 17)

In the search for potent inhibitors of P450 17, the key enzyme in androgen biosynthesis, a series of steroidal inhibitors were synthesized and tested toward rat and human P450 17. Small aliphatic heterocycles (aziridine, oxirane, thiirane, diaziridine, diazirine, azetidine) were introduced into the 17beta-position of anstrost-5-en-3beta-ol. After identifying that aziridine is the most suitable functional group to coordinate with the heme iron, modifications of the steroidal skeleton were performed for further optimization. A wide range of inhibitory potencies toward P450 17 were found for the 21 test compounds. The most potent inhibitors toward the human and rat enzyme were aziridine compounds 3 (IC(50) rat: 0.21 microM, K(i) = 3 nM; IC(50) human: 0.54 microM, K(i) = 8 nM), 5 (IC(50) rat: 0.43 microM, K(i) = 7 nM; IC(50) human: 0.29 microM, K(i) = 4 nM), and 8 (21R:21S = 1:1; IC(50) rat: 0.53 microM, K(i) = 9 nM; IC(50) human: 0.40 microM, K(i) = 6 nM) which were more potent than the reference ketoconazole (IC(50) rat: 67 microM; IC(50) human: 0.74 microM). The inhibitory potency depends markedly on the stereochemistry at C20 of the inhibitors. This effect is more pronounced for the rat enzyme. Tested for selectivity, the highly potent inhibitors show poor inhibitory activity toward P450 arom, P450 scc, P450 TxA(2), and 5alpha-reductase. Tested for in vivo activity, 3 and 8 (0.019 mmol/kg) decreased the plasma testosterone concentration in rats by 81% and 84% after 2 h.

Conflicting molecular phylogenies of European long-eared bats (Plecotus) can be explained by cryptic diversity

Conflicting phylogenetic signals of two data sets that analyse different portions of the same molecule are unexpected and require an explanation. In the present paper we test whether (i) differential evolution of two mitochondrial genes or (ii) cryptic diversity can better explain conflicting results of two recently published molecular phylogenies on the same set of species of long-eared bats (genus Plecotus). We sequenced 1714bp of three mitochondrial regions (16S, ND1, and D-loop) of 35 Plecotus populations from 10 European countries. A likelihood ratio test revealed congruent phylogenetic signals of the three data partitions. Our phylogenetic analyses demonstrated that the existence of a previously undetected Plecotus lineage caused the incongruities of previous studies. This lineage is differentiated on the species level and lives in sympatry with its sister lineage, Plecotus auritus, in Switzerland and Northern Italy. A molecular clock indicates that all European Plecotus species are of mid or late Pliocene origin. Plecotus indet. was previously described as an intergrade between P. auritus and Plecotus austriacus since it shares morphological characters with both. It is currently known from elevations above 800 m a.s.l. in the Alps, the Dinarian Alps and the Pindos mountains in Greece. Since we could demonstrate that incongruities of two molecular analyses simply arose from the mis-identification of one lineage, we conclude that molecular phylogenetic analyses do not free systematists from a thorough inclusion of morphological and ecological data.