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The Viviparidae, commonly known as River Snails, is a dominant group of freshwater snails with a nearly worldwide distribution that reaches its highest taxonomic and morphological diversity in Southeast Asia. The rich fossil record is indicative of a probable Middle Jurassic origin on the Laurasian supercontinent where the group started to diversify during the Cretaceous. However, it remains uncertain when and how the biodiversity hotspot in Southeast Asia was formed. Here, we used a comprehensive genetic data set containing both mitochondrial and nuclear markers and comprising species representing 24 out of 28 genera from throughout the range of the family. To reconstruct the spatiotemporal evolution of viviparids on a global scale, we reconstructed a fossil-calibrated phylogeny. We further assessed the roles of cladogenetic and anagenetic events in range evolution. Finally, we reconstructed the evolution of shell features by estimating ancestral character states to assess whether the appearance of sculptured shell morphologies was driven by major habitat shifts. The molecular phylogeny supports the monophyly of the three subfamilies, the Bellamyinae, Lioplacinae, and Viviparinae, but challenges the currently accepted genus-level classification in several cases. The almost global distribution of River Snails has been influenced both by comparatively ancient vicariance and more recent founder events. In Southeast Asia, Miocene dispersal was a main factor in shaping the modern species distributions. A recurrent theme across different viviparid taxa is that many species living in lentic waters exhibit sculptured shells, whereas only one strongly sculptured species is known from lotic environments. We show that such shell sculpture is habitat-dependent and indeed evolved several times independently in lentic River Snails. Considerably high transition rates between shell types in lentic habitats probably caused the co-occurrence of morphologically distinct shell types in several lakes. In contrast, directional evolution toward smooth shells in lotic habitats, as identified in the present analyses, explains why sculptured shells are rarely found in these habitats. However, the specific factors that promoted changes in shell morphology require further work. [biogeographical analyses; fossil-calibrated phylogeny; fossil-constrained analyses; Southeast Asia; stochastic character mapping.].
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Distribuição Animal , Biodiversidade , Ecossistema , Caramujos/anatomia & histologia , Caramujos/classificação , Exoesqueleto/anatomia & histologia , Animais , Evolução BiológicaRESUMO
The paramagnetic pyrazolylborates Tp2M and Tp*2M (M = Cu, Ni, Co, Fe, Mn, Cr, V) as well as [Tp2M]+ and [Tp*2M]+ (M = Fe, Cr, V) have been synthesized and their NMR spectra recorded. The 1H signal shift ranges vary from â¼30 ppm (Cu(II) and V(III)) to â¼220 ppm (Co(II)), and the 13C signal shift ranges from â¼180 ppm (Fe(III)) to â¼1150 ppm (Cr(II)). The 11B and 14N shifts are â¼360 and â¼730 ppm, respectively. Both negative and positive shifts have been observed for all nuclei. The narrow NMR signals of the Co(II), Fe(II), Fe(III), and V(III) derivatives provide resolved 13C,1H couplings. All chemical shifts have been calculated from first-principles on a modern version of Kurland-McGarvey theory which includes optimized structures, zero-field splitting, and g tensors, as well as signal shift contributions. Temperature dependence in the Fe(II) spin-crossover complex results from the equilibrium of the ground singlet and the excited quintet. We illustrate both the assignment and analysis capabilities, as well as the shortcomings of the current computational methodology.
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Stylommatophora is a main clade of Gastropoda that encompasses approximately 112 gastropod families and may exceed a total of 30,000 species. Twenty-four complete stylommatophoran mitogenomes have been sequenced to date, yet our understanding of mitochondrial evolution in stylommatophorans is still in its infancy. To further expand the set of available mitogenomes, we sequenced the mitogenome of Meghimatium bilineatum (Arionoidea: Philomycidae), a widespread land slug in East Asia. This is the first report on a mitogenome of the superfamily Arionoidea, and indeed on a terrestrial slug. The mitogenome of Meghimatium bilineatum comprises 13,972â¯bp and exhibits a novel, highly distinctive gene arrangement among the Stylommatophora. Phylogenetic reconstructions based on the sequences of all protein-coding genes consistently recovered Meghimatium bilineatum as sister-group of the Succineidae. A phylogenetic reconstruction based on gene order, however, suggested a highly divergent tree topology, which is less credible when taking into account prior knowledge of stylommatophoran relationships. Our CREx (Common interval Rearrangement Explorer) analysis suggested that three successive events of tandem duplication random loss (TDRL) best explain the evolutionary process of gene order rearrangement in Meghimatium bilineatum from an ancestral stylommatophoran mitogenome. The present example offers new insights into the mechanisms of mitogenome rearrangements in gastropods at large and into the usefulness of mitogenomic gene order as a phylogenetic marker.
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Gastrópodes/genética , Rearranjo Gênico , Genoma Mitocondrial , Animais , Sequência de Bases , Mapeamento Cromossômico , Ásia Oriental , Ordem dos Genes , Mitocôndrias/genética , FilogeniaRESUMO
The local magnetic structure in the [FeIII (Tp)(CN)3 ]- building block was investigated by combining paramagnetic Nuclear Magnetic Resonance (pNMR) spectroscopy and polarized neutron diffraction (PND) with first-principle calculations. The use of the pNMR and PND experimental techniques revealed the extension of spin-density from the metal to the ligands, as well as the different spin mechanisms that take place in the cyanido ligands: Spin-polarization on the carbon atoms and spin-delocalization on the nitrogen atoms. The results of our combined density functional theory (DFT) and multireference calculations were found in good agreement with the PND results and the experimental NMR chemical shifts. Moreover, the ab-initio calculations allowed us to connect the experimental spin-density map characterized by PND and the suggested distribution of the spin-density on the ligands observed by NMR spectroscopy. Interestingly, significant differences were observed between the pseudo-contact contributions of the chemical shifts obtained by theoretical calculations and the values derived from NMR spectroscopy using a simple point-dipole model. These discrepancies underline the limitation of the point-dipole model and the need for more elaborate approaches to break down the experimental pNMR chemical shifts into contact and pseudo-contact contributions.
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Progressive aridification since the mid-Miocene has had a significant influence on the evolution of the biota in the arid zone of central Australia. Especially moisture sensitive groups, such as snails, are often restricted to topographically complex areas, which have acted as refugia in an otherwise inhospitable environment. This historical fragmentation is deemed to be a potent agent of allopatric lineage diversification. Camaenid land snails are amongst only a few terrestrial gastropods that have managed to survive in the arid zone probably due to their ability to escape desiccation through aestivation. Here, we present the first study of the mitochondrial lineage differentiation in an endemic land snail genus from the Australian 'Red Centre', Granulomelon Iredale, 1933. Exposing significant incongruence between mtDNA phylogeny and morphology-based taxonomy, we completely revise the species and genus level taxonomy of this camaenid group. We demonstrate that this genus contains three species, G. grandituberculatum, G. adcockianum and G. squamulosum, which have so far been assigned to different genera: Granulomelon Iredale, 1933 (junior synonym: Baccalena Iredale, 1937), Basedowena Iredale, 1937 and Pleuroxia Ancey, 1887. Two of these species are widespread comprising multiple divergent mitochondrial lineages. Based on a molecular clock estimate, these lineages diverged approximately during the mid-Pleistocene, a period of particularly severe aridification. The phylogeographic patterns are consistent with an isolation-by-distance model in one species but not the other. We suggest that these differences can be attributed to their distinctive aestivation behavior.
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Clima Desértico , Estivação/fisiologia , Filogenia , Caramujos/classificação , Caramujos/fisiologia , Animais , Austrália , Evolução Biológica , DNA Mitocondrial/genética , Masculino , Mitocôndrias/genética , Filogeografia , Caramujos/genéticaRESUMO
North-western Australia harbours more than 300 species of camaenid land snail in 41 genera exhibiting considerable and well documented morphological diversity. We performed Bayesian and Maximum Likelihood analyses of concatenated nuclear (28S) and mitochondrial (COI, 16S) DNA sequences from 140 species of 37 of these genera plus an additional 27 extralimital species in order to resolve their phylogenetic relationships and to address the significance of morphological characters for the delineation of monophyletic taxa. While north-western Australian Camaenidae in their entirety are not monophyletic with respect to extralimital groups, they underwent extensive in situ-diversification in several independent phylogenetic radiations. A Maximum Likelihood-based character history reconstruction revealed extensive convergence in all studied shell characters and in three out of four genital features across this group. However, in some genera close morphological similarity is best explained by the retention of ancestral characters. We hypothesize that both morphological stasis in some groups and convergent character evolution in others can to a large extent be attributed to adaptive transformations in response to historically increasing aridity throughout north-western Australia in concert with structural constraints.
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Evolução Biológica , Filogenia , Caramujos/classificação , Exoesqueleto/anatomia & histologia , Animais , Austrália , Teorema de Bayes , Genitália/anatomia & histologia , Funções Verossimilhança , Modelos Genéticos , Análise de Sequência de DNA , Caramujos/anatomia & histologia , Caramujos/genéticaRESUMO
The (133)Cs magic-angle spinning NMR spectra of the paramagnetic compounds CsM(II)[M(III)(CN)6], M(II) = Ni, Co, Fe, Mn; M(II) = Co, Fe, yield unusually large and temperature-dependent signal shifts (up to -950 ppm relative to CsCl at 298 K). Comparison with the spectra of the diamagnetic analogues CsM[Co(CN)6], M = Zn, Cd, shows that the shifts are largely due to the unpaired electrons. This is ascribed to through-bond transfer of spin to the Cs(+) ions, while the through-space effect of the magnetic moments on the signal shifts is shown to be virtually negligible. The mechanism inducing negative spin at Cs(+) is discussed. The magnitude of the spin density (average: |5.8 × 10(-3)| (a.u.) (-3)) suggests that Cs(+) is involved in magnetic exchange interactions of corresponding Prussian blue derivatives.
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With the aim of probing the spin density distribution in the open-shell cyanometallates Cs2K[M(CN)6] (M = Cr, Mn, Fe), K3[M(CN)6] (M = Mn, Fe), K4[M(CN)6] (M = Cr, Mn), and K4[V(CN)7] have been studied by solid-state (13)C and (15)N NMR spectroscopy. The signals appear in strongly shifted and broad ranges ((13)C, -2100 to -8900 ppm; (15)N, -1900 to 2400 ppm) except K4[V(CN)7], which is NMR-silent. Analysis of the isotropic signal shifts yields negative spin density in all carbon 2s orbitals (up to 12.2% at the six ligands of [Mn(CN)6](3-)) and positive spin density in all nitrogen 2s orbitals (up to 1.1% at the six ligands of [Mn(CN)6](4-) and [Fe(CN)6](3-)). This is in accord with the induction of alternating spin at the CN ligands by successive polarization of σ bonds triggered by the spin center M(n+). The signal shift anisotropies are related to spin in the carbon and nitrogen 2pπ and 2pσ orbitals. In the case of Cs2K[Cr(CN)6] and K4[Cr(CN)6] much positive spin is found in the nitrogen 2pπ orbitals, which corresponds to direct M â N spin transfer. On Cs2K[M(CN)6] (M = Mn, Fe), the 2pπ spin density at nitrogen is negative. The results are in accord with and extend the data of polarized neutron diffraction and EPR spectroscopy. Owing to high signal resolution, small deviations of the [M(CN)6](n-) ions from octahedral symmetry and disorder of crystal layers have been detected. This corresponds to the crystal symmetry and to Jahn-Teller distortion. The disorder entails a scatter of spin densities. In the case of K4[Mn(CN)6] it reaches 19% for the C 2s orbitals and 80% for the N 2s orbitals with regard to the respective smallest spin population.
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The Western Australian Kimberley region harbours a diverse fauna of camaenid land snails characterised by marked patterns of narrow range endemism. The recently described genus Australocosmica comprised three species that are endemic to single offshore islands or island groups. Material of a further seven candidate species recognised by the late Alan Solem has been examined. Six of these manuscript species, NSP 40 (= A. rotunda n. sp.), NSP 76 (= A. pallida n. sp.), NSP 77 (= A. buffonensis n. sp.), NSP 78 (= A. bernoulliensis n. sp.), NSP 79 (= A. crassicostata n. sp.), and NSP 80 (= A. nana n. sp.), are here newly described based on examination of shell morphology and penial anatomy. Based on our findings, we are presenting an updated generic diagnosis of Australocosmica. Statistical analyses revealed that species exhibit similar shell characters (colouration, sculpture, dimensions), which render the delimitation of species based only on shells difficult. However, species were found to differ significantly in their penial anatomy. Although the material studied was not suitable for DNA extraction, the anatomical differences were considered sufficient to permit the description of distinct species.
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Caramujos/anatomia & histologia , Caramujos/classificação , Animais , Feminino , Masculino , Austrália OcidentalRESUMO
The factors that influence population structure and connectivity are unknown for most terrestrial invertebrates but are of particular interest both for understanding the impacts of disturbance and for determining accurate levels of biodiversity and local endemism. The main objective of this study was to determine the historical patterns of genetic differentiation and contemporary gene flow in the terrestrial snail, Austrochloritis kosciuszkoensis (Shea & O. L. Griffiths, 2010). Snails were collected in the Mt Buffalo and Alpine National Parks in Victoria, in a bid to understand how populations of this species are connected both within continuous habitat and between adjacent, yet separate environments. Utilising both mitochondrial DNA (mtDNA) and single nucleotide polymorphism (SNP) data, the degree of population structure was determined within and between sites. Very high levels of genetic divergence were found between the Mt Buffalo and Alpine snails, with no evidence for genetic exchange detected between the two regions, indicating speciation has possibly occurred between the two regions. Our analyses of the combined mtDNA and nDNA (generated from SNPs) data have revealed patterns of genetic diversity that are consistent with a history of long-term isolation and limited connectivity. This history may be related to past cycles of changes to the climate over hundreds of thousands of years, which have, in part, caused the fragmentation of Australian forests. Within both regions, extremely limited gene flow between separate populations suggests that these land snails have very limited dispersal capabilities across existing landscape barriers, especially at Mt Buffalo: here, populations only 5 km apart from each other are genetically differentiated. The distinct genetic divergences and clearly reduced dispersal ability detected in this data explain the likely existence of at least two previously unnamed cryptic Austrochloritis species within a 30-50 km radius, and highlight the need for more concentrated efforts to understand population structure and gene flow in terrestrial invertebrates.
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The superfamily Orthalicoidea comprises approximately 2,000 species of terrestrial gastropods, mostly concentrated in the Neotropics but also present in southern Africa and Oceania. We provide a multi-marker molecular phylogeny of this superfamily, reassessing its family- and genus-level classification. We exclude two families from the group, Odontostomidae and Vidaliellidae, transferring them to Rhytidoidea based on their phylogenetic relationships as recovered herein. Two new families are recognized herein as members of Orthalicoidea, Tomogeridae and Cyclodontinidae fam. nov. The family Megaspiridae and the subfamily Prestonellinae are paraphyletic but are retained herein for taxonomic stability. The subfamily Placostylinae is synonymized with Bothriembryontinae. The new genera Alterorhinus gen. nov. and Sanniostracus gen. nov. containing some Brazilian species are described here to better reflect the phylogeny. The fossil record and paleobiogeographic history of the group is explored under the new phylogenetic framework.
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Caramujos , Humanos , Animais , Filogenia , Caramujos/genética , África Austral , BrasilRESUMO
In the past years several developments have occurred in the care for patients with pancreatic cancer in the Netherlands. New palliative chemotherapy strategies using FOLFRINOX or gemcitabine/nab-paclitaxel were introduced for patients with advanced disease. Due to centralization of pancreatic surgery, introduction of neoadjuvant therapy, and the implementation of standardized postoperative care more patients became enable for resection, postoperative mortality decreased, and survival improved. Within the randomized PREOPANC trial of the Dutch Pancreatic Cancer Group (DPCG), neoadjuvant therapy using chemoradiation for (borderline) resectable pancreatic cancer improved five-year survival from 7% to 21%. Furthermore, due to nationwide training programs, the use of minimally invasive surgery has increased. Regardless of these developments, the survival of patients with pancreatic cancer is still low and 61% of Dutch patients with pancreatic cancer patients do not receive any tumor targeted therapy. The DPCG is active to improve quality of care through auditing, research, guideline development, and education.
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Gencitabina , Neoplasias Pancreáticas , Humanos , Desoxicitidina/uso terapêutico , Países Baixos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Pancreáticas/patologiaRESUMO
DNA barcoding has been used worldwide to identify biological specimens and to delimit species. It represents a cost-effective, fast, and efficient way to assess biodiversity with help of the public Barcode of Life Database (BOLD) accounting for more than 236,000 animal species and more than 10 million barcode sequences. Here, we performed a meta-analysis of available barcode data of central European Coleoptera to detect intraspecific genetic patterns among ecological groups in relation to geographic distance with the aim to investigate a possible link between infraspecific variation and species ecology. We collected information regarding feeding style, body size, as well as habitat and biotope preferences. Mantel tests and two variants of Procrustes analysis, both involving the Principal Coordinates Neighborhood Matrices (PCNM) approach, were applied on genetic and geographic distance matrices. However, significance levels were too low to further use the outcome for further trait investigation: these were in mean for all ecological guilds only 7.5, 9.4, or 15.6% for PCNM + PCA, NMDS + PCA, and Mantel test, respectively, or at best 28% for a single guild. Our study confirmed that certain ecological traits were associated with higher species diversity and foster stronger genetic differentiation. Results suggest that increased numbers of species, sampling localities, and specimens for a chosen area of interest may give new insights to explore barcode data and species ecology for the scope of conservation on a larger scale. We performed a meta-analysis of available barcode data of central European beetles to detect intraspecific genetic patterns among ecological groups in relation to geographic distance, regarding feeding style, body size, as well as habitat and biotope preferences. Our study confirmed that certain ecological traits were associated with higher species diversity and foster stronger genetic differentiation. However, significance levels were too low to further use the outcome for further trait investigation.
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We introduce a new method of estimating accepted species diversity by adapting mark-recapture methods to comparisons of taxonomic databases. A taxonomic database should become more complete over time, so the error bar on an estimate of its completeness and the known diversity of the taxon it treats will decrease. Independent databases can be correlated, so we use the time course of estimates comparing them to understand the effect of correlation. If a later estimate is significantly larger than an earlier one, the databases are positively correlated, if it is significantly smaller, they are negatively correlated, and if the estimate remains roughly constant, then the correlations have averaged out. We tested this method by estimating how complete MolluscaBase is for accepted names of terrestrial gastropods. Using random samples of names from an independent database, we determined whether each name led to a name accepted in MolluscaBase. A sample tested in August 2020 found that 16.7% of tested names were missing; one in July 2021 found 5.3% missing. MolluscaBase grew by almost 3,000 accepted species during this period, reaching 27,050 species. The estimates ranged from 28,409 ± 365 in 2021 to 29,063 ± 771 in 2020. All estimates had overlapping 95% confidence intervals, indicating that correlations between the databases did not cause significant problems. Uncertainty beyond sampling error added 475 ± 430 species, so our estimate for accepted terrestrial gastropods species at the end of 2021 is 28,895 ± 630 species. This estimate is more than 4,000 species higher than previous ones. The estimate does not account for ongoing flux of species into and out of synonymy, new discoveries, or changing taxonomic methods and concepts. The species naming curve for terrestrial gastropods is still far from reaching an asymptote, and combined with the additional uncertainties, this means that predicting how many more species might ultimately be recognized is presently not feasible. Our methods can be applied to estimate the total number of names of Recent mollusks (as opposed to names currently accepted), the known diversity of fossil mollusks, and known diversity in other phyla.
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Gastrópodes , Animais , Moluscos , Fósseis , Bases de Dados Factuais , Projetos de PesquisaRESUMO
Magic-angle spinning (MAS) NMR spectroscopy is used to study the local structure and spin delocalisation in Prussian blue analogues (PBAs). We selected two common archetypes of PBAs (A(I)M(II)[M(III)(CN)(6)]·xH(2)O and M(II)(3)[M(III)(CN)(6)](2)·xH(2)O, in which A(I) is an alkali ion, and M(II) and M(III) are transition-metal ions) that exhibit similar cubic frameworks but different microscopic structures. Whereas the first type of PBA contains interstitial alkali ions and does not exhibit any [M(III)(CN)(6)](3-) vacancies, the second type of PBA exhibits [M(III)(CN)(6)](3-) vacancies, but does not contain inserted alkali ions. In this study, we selected Cd(II) as a divalent metal in order to use the (113)Cd nuclei (I=1/2) as a probe of the local structure. Here, we present a complete MAS NMR study on two series of PBAs of the formulas Cd(II)(3)[Fe(III)(x)Co(III)(1-x)(CN)(6)](2)·15H(2)O with x=0 (1), 0.25 (2), 0.5 (3), 0.75 (4) and 1 (5), and CsCd(II)[Fe(III)(x)Co(III)(1-x)(CN)(6)]·0.5H(2)O with x=0 (6), 0.25 (7), 0.5 (8), 0.75 (9) and 1 (10). Interestingly, the presence of Fe(III) magnetic centres in the vicinity of the cadmium sites has a magnifying-glass effect on the NMR spectrum: it induces a striking signal spread such that the resolution is notably improved compared to that achieved for the diamagnetic PBAs. By doping the sample with varying amounts of diamagnetic Co(III) and comparing the NMR spectra of both types of PBAs, we have been able to give a view of the structure which is complementary to that usually obtained from X-ray diffraction studies. In particular, this study has shown that the vacancies are not randomly distributed in the mesoporous PBAs. Moreover the cadmium chemical shift, which is a measure of the hyperfine coupling, allows the estimation of the spin density on the cadmium nucleus, and consequently, the elucidation of the spin delocalisation mechanism in these compounds along with its dependency on structural parameters.
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1,4-Diazidobuta-1,3-dienes (Z,Z)-10, 17, and 21 were photolyzed and thermolyzed to yield the pyridazines 13, 20, and 23, respectively. To explain these aromatic final products, the generation of highly strained bi-2H-azirin-2-yls 12, 19, and 22 and their valence isomerization were postulated. In the case of meso- and rac-22, nearly quantitative formation from diazide 21, isolation as stable solids, and complete characterization were possible. On the thermolysis of 22, aromatization to 23 was only a side reaction, whereas equilibration of meso- and rac-22 and fragmentation, which led to alkyne 24 and acetonitrile, dominated. Prolonged irradiation of 22 gave mainly the pyrimidine 25. The change of the configuration at C-2 of the 2H-azirine unit was observed not only in the case of bi-2H-azirin-2-yls 22 but also for simple spirocyclic 2H-azirines 29 at a relatively low temperature (75 °C). The fragmentation of rac-22 to give alkyne 24 and two molecules of acetonitrile was also studied by high-level quantum chemical calculations. For a related model system 30 (methyl instead of phenyl groups), two transition states TS-30-31 of comparable energy with multiconfigurational electronic states could be localized on the energy hypersurface for this one-step conversion. The symmetrical transition state complies with the definition of a coarctate mechanism.
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Mountain regions are centers of biodiversity endemism at a global scale but the role of arid-zone mountain ranges in shaping biodiversity patterns is poorly understood. Focusing on three guilds of taxa from a desert upland refugium in Australia, we sought to determine: (a) the relative extent to which climate, terrain or geological substrate predict endemism, and (b) whether patterns of endemism are complimentary across broad taxonomic guilds. We mapped regional endemism for plants, land snails, and vertebrates using combined Species Distribution Models (SDMs) for all endemic taxa (n = 82). We then modelled predictors of endemism using Generalised Additive Models (GAMs) and geology, terrain, and climate variables. We tested for the presence of inter- and intraguild hotspots of endemism. Many individual plant and land snail taxa were tightly linked with geology, corresponding to small distributions. Conversely, most vertebrate taxa were not constrained to specific geological substrates and occurred over larger areas. However, across all three guilds climate was the strongest predictor of regional endemism, particularly for plants wherein discrete hotspots of endemism were buffered from extreme summer temperatures. Land snail and vertebrate endemism peaked in areas with highest precipitation in the driest times of the year. Hotspots of endemism within each guild poorly predicted endemism in other guilds. We found an overarching signal that climatic gradients play a dominant role in the persistence of endemic taxa in an arid-zone mountain range system. An association with higher rainfall and cooler temperatures indicates that continuing trends toward hotter and drier climates may lead to range contractions in this, and potentially other, arid-zone mountain biotas. Contrasting patterns of endemism across guilds highlight the need to couple comprehensive regional planning for the protection of climate refugia, with targeted management of more localized and habitat specialist taxa.
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A 5' truncated non-LTR CR1-like retrotransposon, named RanaCR1, was identified in the serum albumin intron-1 (SAI-1) of at least seven species of western Palearctic water frogs (WPWF). Based on sequence similarity of the carboxy-terminal region (CTR) of ORF2 and/or the highly conserved 3' untranslated region (3' UTR), RanaCR1-like elements occur also in the genome of Xenopus tropicalis and Rana temporaria. Unlike other CR1 elements, RanaCR1 contains a CA microsatellite in its 3' UTR. The low nucleotide diversity of the 3' UTR compared to the CTR and to SAI-1 suggests that this region still plays a role in WPWF, either as a structure-stabilizing element, or within a species-specific transcriptional network. Length variation of water frog SAI-1 sequences is caused by deletions that extend in some cases beyond the 5' or 3' ends of RanaCR1, probably a result of selection for structural and functional stability of the primary transcript. The impact of RanaCR1 on SAI-1 evolution is also indicated by the significant negative correlation between the length of both SAI-1 and RanaCR1 and the percentage GC content of RanaCR1. Both SAI-1 and RanaCR1 sequences support the sister group relationship of R. perezi and R. saharica, which are placed in the phylogenetic tree at a basal position, the sister clade to other water frog taxa. It also supports the monophyly of the R. lessonae group; of Anatolian water frogs (R. cf. bedriagae), which are not conspecific with R. bedriagae, and of the European ridibunda group. Within the ridibunda clade, Greek frogs are clearly separated, supporting the hypothesis that Balkan water frogs represent a distinct species. Frogs from Atyrau (Kazakhstan), the type locality of R. ridibunda, were heterozygous for a ridibunda and a cf. bedriagae specific allele.
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Anuros/genética , Evolução Molecular , Filogenia , Retroelementos , Albumina Sérica/genética , Animais , Anuros/classificação , Clonagem Molecular , Íntrons , Repetições de Microssatélites , Análise de Sequência de DNA , Deleção de SequênciaRESUMO
No legendary Prussian order! The distribution of vacancies in Prussian blue analogues is not random, and the spin density on the Cd(2+) ion varies depending on the number of paramagnetic ions in its surroundings. This conclusion follows from (113)Cd solid-state magic-angle spinning NMR studies of [Cd(3){Fe/Co(CN)(6)}(2)] x 15 H(2)O, where the presence of small but significant spin density on the observed (113)Cd nucleus leads to improved spectral resolution.
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Herein, we described the complete mitochondrial genome ('mitogenome') of the Chinese land snail Cyclophorus martensianus, which is the first published mitogenome for the caenogastropod family Cyclophoridae. This mitogenome is 15,308â¯bp long consisting of 37 genes: 13 protein-coding genes (PCGs), 22 tRNA genes and two rRNA genes. The Aâ¯+â¯T content (69.6%) is distinctly higher than the GC content (30.4%). Most PCGs start with ATN as initiation codons, and all PCGs have the conventional stop codons TAA and TAG. Overall, the biochemical properties and gene order of the cyclophorid mitogenome are very similar to those of other documented caenogastropod mitogenomes. We corroborate the findings of earlier studies that mitochondrial gene order is rather conserved among caenogastropods. Caenogastropoda are the taxonomically, morpho-anatomically and ecologically most diverse group of living gastropods comprising lineages inhabiting marine, freshwater, and terrestrial environments. Traditionally, the three most speciose groups of non-marine caenogastropods have all been placed in a single group, the Architaenioglossa. This group contains two freshwater lineages, the Viviparoidea and Ampullaroidea, and the terrestrial Cyclophoroidea. However, architaenioglossan relationships have remained controversial with several morphology-based on molecular phylogenetic analyses supporting contradicting phylogenetic hypotheses. In order to more robustly resolve the relationships among the Architaenioglossa, we have performed phylogenetic analyses of caenogastropod mitogenomes including the new mitogenome of Cyclophorus martensianus. Our phylogenetic reconstructions are based on the amino acid sequences of all protein-coding genes and consistently recovered Architaenioglossa as non-monophyletic.