julilili42/papers huggingface dataset:
Coevolved reproductive strategies in the oligolectic bee Callonychium petuniae (Apoidea, Andrenidae) and three purple flowered Petunia species (Solanaceae) in southern Brazil
2009-04-27

Females of Callonychium petuniae were found to be oligolectic foragers on three sympatric purple flowered Petunia species in Rio Grande do Sul, southern Brazil. Males patrol patches of Petunia flowers in search for females. They also wait for females in or on the flowers and perch for mates in the vicinity of blossoms. Copulation is always initiated on Petunia flowers. Flying in copulation posture, the couple visits Rrther flowers where the female continues to collect pollen. The mates land outside the Petunia patch to copulate for up to 20 min. and then take ofr separately. We interprete the flights in copula posture as male strateies to prevent the female from returning to the area of high competitor abundance for further pollen collecting after copulation. Thereby males may increase their chances to be the last male to mate before the eggs are fertilized. Femals and males of C. petuniae are the most frequent pollinators of purple flowered Petunia species and indiscriminately transfer pollen between them. Cytogenetic analyses of chromosome numbers and meiotic phases in individuals of two sympatric Petunia species and in presumable hybrids showed, however, that the species maintain their integrity. Spontaneous color choices in multicolored patches of dummy flowers revealed that C. petuniae bees have a high preference for Petunia-purple color tones, as seen by the human eye. We discuss the significance of color selectivity by C. petuniae bees and of the visual signals exhibited by purple flowered Petunia species to keep the coevolved reproductive strategies stable.
Satellite DNA and speciation: A species specific satellite DNA of Drosophila guanchel
2009-04-27

The heterochromatin of the chromosomes of Drosophila gunche consists mainly of a satellite DNA composed of multiple, tandemly arranged copies of a 290 b p basic sequence. Five clones containing one or two copies of the basic unit were sequenced. As expected from CsCl density centrifugation and AT specific staining of mitotic chromosomes the sequence is AT rich. The average nucleotid variability between the cloned sequences is 11.6%. In situ hybridization on the mitotic chromosomes revealed, that this satellite DNA is present in the centromeric regions of all chromosomes but the Y. The nucleotide variability between copies of different tandem clusters seems to be higher than between members of the same cluster. The copy number of the sequence in the haploid genome was estimated to be approximately 80000. The sequence is species specific and is not present in the genome of sibling species D. subobscura and D. madeiren-sis. The evolutionary origin of the satellite DNA and its possible role in species formation is discussed.
Restriction fragment patterns as molecular markers for species identification and phylogenetic analysis in the genus Enchytraeus (Oligochaeta)1
2009-04-27

Species identification in the Enchytraeidae is extremely difficult as in many groups of lower invertebrates. Clear-cut morphological character differences which would allow an unambiguous delimitation are almost totally lacking between numerous species. Consequently, their identification and their phylogenetic relationships cannot be discerned by classical morphological methods alone. We show in this study that comparative analysis of DNA fragment variation found by restriction endonuclease digestions provide a suitable means for both species identification and analysis of their phylogenetic relationships. We have studied fragment length variation of ubiquitin and 18S rRNA genes in ten different populations of the genus Enchytraeus. Two populations which belong to the two species E. albidus and E. fragmentosus can be clearly identified by their restriction fragment patterns. The remaining eight populations are grouped into four clusters. The fragment patterns are identical within each group but differ considerably between these groups. Since the differences between these groups and between the two well characterized species are in the same range, it is suggested that these four groups may represent four different Enchytraeus-species. Phylogenetic analysis using Wagner maximum parsimony reveals a clearly defined pattern of relationships of the species studied.
Genetic differentiation of the millipede Pycnotropis epiclysmus inhabiting seasonally inundated and non-flooded Amazonian forests
2009-04-27

The millipede Pycnotropis epiclysmus Hoffman, 1995 (Diplopoda: Polydesmida: Platyrhacidae) is frequently found in Central Amazonian white-and mixed-water inundation forests along the Solimöes-Amazon River near Manaus, Brazil. It also inhabits non-flooded disturbed forest areas adjacent to this river. Populations from both biotopes were genetically studied. The specific pPeP172 satellite DNA family identified in P. epiclysmus has been analyzed in order to elucidate the systematic rank of morphologically indistinguishable individuals from the different habitat types. Nucleotide sequence data, sequence variability and copy number estimates of the pPeP172 satellite DNA do not discriminate the respective populations into genetically different ecotypes. The study of enzyme variability, however, revealed genotypic differences among the three populations: the populations from two geographically more distant inundation forests are genetically rather similar; and the geographically closer populations, one found in a non-flooded and the other in an inundation forest, have a genetic distance which is of similar magnitude to that of the two geographically more distant populations. The genetic data suggest that individuals from different habitats belong to populations of a single species. Genotypic structuring among and within local populations indicates processes of genetic differentiation which can be the result of the migration ability of this millipede.
Taxonomic and molecular studies on Drosophila sinobscura and D. hubeiensis, two sibling species of the D. obscura group*
2009-04-27

Allozyme electrophoresis and three different DNA sequences (ATOC180 satellite DNA, 5SrDNA repeats, and parts of the Adh gene) were used to compare the two closely related East Asian sibling species Drosophila sinobscura and D. hubeiensis producing fertile hybrids in the laboratory. The data were also applied to establish their phylogenetic relationships to the other species of the D. obscura group. Genetic divergence in 5SrDNA repeats and specifically in the Adh gene separate the two species clearly from each other and justify their species status. Both species are related to the European species of the D. obscura group but the presence of members of the ATOC 180 satellite DNA family, specific and common to the species triad D. ambigua, D. tristis and D. obscura, in the genomic DNA of D. sinobscura and D. hubeiensis put the two sibling species in their close neighbourhood.
The land-snail species of cochlicopa (Gastropoda: Pulmonata: Cochlicopidae): presentation of taxon-specific allozyme patterns, and evidence for a high level of self-fertilization
2009-04-27

Genetic differentiation in the four nominal species C. nitens (Gallenstein, 1848), C. lubricella (Porro, 1838), C. lubrica (O. F. Müller, 1774) and C. repentina Hudec, 1960 was studied by investigating 21 isoenzyme loci. Allozymic markers exist, which clearly separate the first three taxa from each other, including in sympatric areas. By contrast, C. repentina and C. lubrica exhibit almost no isozymic differentiation and therefore, C. repentina should not be considered as a separate species, but as a member of C. lubrica sensu lato. The high frequency of homozygotes within all populations of all species shows that self-fertilization is the main breeding system of Cochlicopa. Genetic relationships between the various populations were inferred with different tree-constructing methods. In all phenograms, populations of C. nitens appear in one distinct cluster, whereas the grouping of C. lubricella changes when different clustering-procedures are used. Therefore, it remains unclear whether the three populations of C. lubricella have a common origin or whether they are polyphyletic with at least two independent ancestors.
Gravitational radiation from collapsing magnetized dust. II. Polar parity perturbation
2009-04-27

With the gauge-invariant perturbation theory, we study the effects of the stellar magnetic fields on the polar gravitational waves emitted during the homogeneous dust collapse. We found that the emitted energy in gravitational waves depends strongly not only on the initial stellar radius but also on the rasio between the poloidal and toroidal magnetic components. The polar gravitational wave output of such a collapse can be easily up to a few order of magnitude larger than what we get from the nonmagnetized collapse. The changes due to the existence of magnetic field could be helpful to extract some information of inner magnetic profiles of progenitor from the detection of the gravitational waves radiated during the black hole formation, which results from the stellar collapse.
Histone gene transposition in the phylogeny of the Drosophila obscura group
2009-04-27

The chromosomal location of the histone genes was determined in seven species of the Drosophila obscura group by in situ hybridization. Histone genes occur on more than one site per genome and on non-homologous chromosome elements. In addition, the metaphase karyotypes and the banding pattern of the polytene chromosomes were compared. Based on chromosomal characters, the cladogenesis of the D. obscura group was established. From the distribution of histone sites in different species, analysed in this paper and in previous studies, the phylogenetic history of histone gene transposition was derived. The molecular mechanisms responsible for the generation of new histone sites are discussed.
An alternative methionine aminopeptidase, MAP-A, is required for nitrogen starvation and high-light acclimation in the cyanobacterium Synechocystis sp. PCC 6803
2009-04-27

Methionine aminopeptidases (MetAPs or MAPs, encoded by map genes) are ubiquitous and pivotal enzymes for protein maturation in all living organisms. Whereas most bacteria harbour only one map gene, many cyanobacterial genomes contain two map paralogues, the genome of Synechocystis sp. PCC 6803 even three. The physiological function of multiple map paralogues remains elusive so far. This communication reports for the first time differential MetAP function in a cyanobacterium. In Synechocystis sp. PCC 6803, the universally conserved mapC gene ( sll0555 ) is predominantly expressed in exponentially growing cells and appears to be a housekeeping gene. By contrast, expression of mapA ( slr0918 ) and mapB ( slr0786 ) genes increases during stress conditions. The mapB paralogue is only transiently expressed, whereas the widely distributed mapA gene appears to be the major MetAP during stress conditions. A mapA -deficient Synechocystis mutant shows a subtle impairment of photosystem II properties even under non-stressed conditions. In particular, the binding site for the quinone Q B is affected, indicating specific N-terminal methionine processing requirements of photosystem II components. MAP-A-specific processing becomes essential under certain stress conditions, since the mapA -deficient mutant is severely impaired in surviving conditions of prolonged nitrogen starvation and high light exposure.
Comparative study of allozyme variation in six species of the Drosophila obscura-group
2009-04-27

Summary Seasonal occurrence at a trapping site near Tubingen and allelic variation at eight enzyme loci were studied in six species of the Drosophila obscura-group. In the two common species D. subobscura and D. obscura the amount of intraspecific polymorphism was found to be significantly higher than in the rare species D. subsilvestris, D. helvetica, D. tristis, and D. ambigua. Based on the allele frequencies derived from the electrophoretic data the coefficients of genetic identity between the species were calculated, and a phylogenetic tree was constructed. In some cases the identity of electromorphs shared by different species was further examined by additional techniques (electrophoresis under varying conditions, thermostability tests). This investigation revealed considerable heterogeneity within the electrophoretic classes distinguished by the standard method. The practical consequences of this finding are discussed. Zusammenfassung Vergleichende Untersuchung der Allozym-Variation bei sechs Arten der Drosophila obscura-Gruppe Die jahreszeitliche Häufigkeit an einem Fangplatz in der Nahe Tübingens sowie die genetische Variabilität von acht Enzymgenen wurden bei sechs Arten der Drosophila obscura-Gruppe untersucht. Bei den beiden häufigen Arten D. subobscura und D. obscura konnte ein wesentlich höherer innerartlicher Polymorphismus festgestellt werden als bei den seltenen Arten D. subsilvestris, D. helvetica, D. tristis und D. ambigua. Basierend auf den aus den Elektrophoresedaten gewonnenen Allelhäufigkeiten wurden die Koeffizienten für die genetische Identität zwischen den Arten berechnet und ein phylogenetischer Stammbaum erstellt. In einigen Fällen, wo die gleiche Allozymvariante bei verschiedenen Arten auftrat, wurde die Identität der Enzyme mittels zusätzlicher Techniken (Elektrophorese unter verschiedenen Bedingungen, Thermostabilitätstests) überprüft. Diese Untersuchung zeigte, daß die nach der Standardmethode unterschiedenen Allelklassen in sich betrachtlich heterogen sind. Die praktischen Auswirkungen dieses Befundes werden diskutiert.
The importance of geographic isolation, structural rearrangement and speciation for the genetic divergence of chromosome O in Drosophila subobscura, Drosophila guanche and Drosophila madeirensis
2009-04-27

Summary Genic divergence of the distal end of chromosome O was investigated in the related species D. subobscura, D. guanche and D. madeirensis. The polymorphic loci Acph, Lap and Pep were used as genetic markers. The position of the three loci with respect to the inversion breakpoints was determined by establishing a linkage map of this region for D. subobscura. The electrophoretic techniques applied in different laboratories for the assay of the three enzymes were compared and a correspondence of the different systems of nomenclature for the allozymes was achieved. The co-ordination of the alleles made it possible to combine the data published by different authors and to consider them in -a new context. Starting with the concept that chromosomal inversions represent isolated gene pools, we calculated allelic frequencies of the three loci separately for different chromosomal arrangements. Based on this set of data genetic identity values were computed between samples of a particular chromosomal arrangements from different populations, between different chromosomal arrangements and between the three species. The degrees of genetic divergence at the three levels of differentiation was compared and a dendrogram was constructed. A phylogenetic interpretation of the dendrogram is discussed. Zusammenfassung Die Bedeutung von geographischer Isolation, chromosomalem Umbau und Artbildung fúr die genetische Divergenz des O-Chromosoms von Drosophila subobscura, Drosophila guanche und Drosophila madeirensis Die genetische Divergenz des distalen Bereiches von Chromosom O wurde in den verwandten Arten D. subobscura, D. guanche und D. madeirensis untersucht. Die polymorphen Genloci Acph, Lap und Pep dienten als Markierungsgene. Die Lage der drei Gene zu den Inversionsbruchstellen wurde bestimmt and vine Austauschkarte dieses Chromosomenabschnittes für D. subobscura erstellt. Die für die Untersuchung der drei Enzyme in verschiedenen Laboratorien verwendeten Elektrophoresetechniken wurden verglichen and die Bezeichnungssysteme für die Benennung der Allozyme in Ubereinstimmung gebracht. Die Zuordnung der Allele machte es möglich, die Ergebnisse verschiedener Autoren zusammenzufassen und in einem neuen Zusammenhang zu betrachten. Ausgehend von der Idee, daß chromosomale Inversionen isolierte Genpools darstellen, wurden die Allelhäufigkeiten der drei Loci für jeden der verschiedenen chromosomalen Strukturtypen getrennt bestimmt. Aus diesen Daten wurden genetische Identitätswerte berechnet und der Grad der genetischen Divergenz auf verschiedenen Stufen verglichen: zwischen Stichproben desselben Strukturtyps aus verschiedenen Populationen, zwischen verschiedenen Strukturtypen und zwischen den drei Arten. Basierend auf den Identitatswerten wurde ein Dendrogramm konstruiert und die Möglichkeit einer phylogenetischen Interpretation diskutiert.
Identification and phylogenetic analysis of four Tisbe species (Copepoda, Harpacticoida) using DNA restriction site variation1
2009-04-27

Since the analysis of phylogenetic relationship in the taxon Tisbe (Copepoda, Harpacticoida) by using morphological methods often leads to controversial results we have tested a molecular approach as an alternative. The restriction site variation in four species of Tisbe and in Artemia salina which was used as an outgroup was analyzed. Eleven different restriction enzymes were used and six different genes (ribosomal, actin-, histone-, ubiquitin-, α- and β-tubulin genes) were tested using heterologous hybridization probes in search of suitable differences which allow a clear identification of the species and which are useful for a phylogenetic analysis. The best results were obtained with 18S rRNA gene sequences which were amplified in vitro by the polymerase chain reaction technique prior to restriction enzyme analysis. The in vitro amplification solved the problems which were encountered with the other analyses due to the relatively small amounts of highly purified DNA which could be isolated from the cultured animals. Every species can be recognized by a typical restriction fragment pattern. No intraspecific variation could be detected in the conserved gene sequences tested. However, even the highly conserved 18SrDNA sequences exhibit sufficient interspecific variation for a phylogenetic analysis. A phylogenetic tree was inferred from the data with a computer program using the Wagner maximum parsimony method. It is discussed that the presented analysis technique can presumably be scaled down to the level of a single animal.
The Form of the Maxim as the Determining Ground of the Will (The Critique of Practical Reason: §§4–6, 27–30)
2009-04-27

In the 'Analytic of Pure Practical Reason', Book I of the second The Critique of Practical Reason, Immanuel Kant undertakes to show that pure reason can be practical. Sections 4-6 are primarily concerned with the second, third, and fourth steps in an ultimately seven-part argument (with the concepts of pure form, universal legislation, and transcendental freedom, respectively). The fifth, sixth, and seventh steps of the overall argument (the 'fundamental law', the 'fact of reason', and the concept of 'autonomy', respectively), constitute the essential core of the 'Analytic'. In the first step of the ensuing argument Kant comes to negative conclusion that no maxims originate from an empirical will and the governing principle of an empirical will. The second step in Kant's demonstration consists in an argument e contrario. The determining ground of the free will lies in the legislating form contained in the maxim, in accordance with the third step.
ChemInform Abstract: The Versatility of Solid‐State Metathesis Reactions: From Rare Earth Fluorides to Carbodiimides.
2009-04-27

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Introduction
2009-04-27

The widespread influence of Immanuel Kant's moral and legal philosophy is a striking exception to the division that can often be found between the approaches of modern European philosophy and the Anglophone analytic tradition. Although Kant's system as a whole exhibits a deeply cosmopolitan orientation even in its general foundations, his philosophy has become especially relevant in our time primarily because of the numerous practical implications of its central ideal of autonomy, which still determines the dominant liberal views of history, law, and politics.
ChemInform Abstract: Preparation of Some Glycosyl Amino Acid Building Blocks via Click Reaction and Construction of a Glycotetrapeptide Library Using Spot Synthesis.
2009-04-27

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Enhanced Glucose Tolerance by SK4 Channel Inhibition in Pancreatic β-Cells
2009-04-28

OBJECTIVE Ca2+-regulated K+ channels are involved in numerous Ca2+-dependent signaling pathways. In this study, we investigated whether the Ca2+-activated K+ channel of intermediate conductance SK4 (KCa3.1, IK1) plays a physiological role in pancreatic β-cell function. RESEARCH DESIGN AND METHODS Glucose tolerance and insulin sensitivity were determined in wild-type (WT) or SK4 knockout (SK4-KO) mice. Electrophysiological experiments were performed with the patch-clamp technique. The cytosolic Ca2+ concentration ([Ca2+]c) was determined by fura-2 fluorescence. Insulin release was assessed by radioimmunoassay, and SK4 protein was detected by Western blot analysis. RESULTS SK4-KO mice showed improved glucose tolerance, whereas insulin sensitivity was not altered. The animals were not hypoglycemic. Isolated SK4-KO β-cells stimulated with 15 mmol/l glucose had an increased Ca2+ action potential frequency, and single-action potentials were broadened. These alterations were coupled to increased [Ca2+]c. In addition, glucose responsiveness of membrane potential, [Ca2+]c, and insulin secretion were shifted to lower glucose concentrations. SK4 protein was expressed in WT islets. An increase in K+ currents and concomitant membrane hyperpolarization could be evoked in WT β-cells by the SK4 channel opener DCEBIO (100 μmol/l). Accordingly, the SK4 channel blocker TRAM-34 (1 μmol/l) partly inhibited KCa currents and induced electrical activity at a threshold glucose concentration. In stimulated WT β-cells, TRAM-34 further increased [Ca2+]c and broadened action potentials similar to those seen in SK4-KO β-cells. SK4 channels were found to substantially contribute to Kslow (slowly activating K+ current). CONCLUSIONS SK4 channels are involved in β-cell stimulus-secretion coupling. Deficiency of SK4 current induces elevated β-cell responsiveness and coincides with improved glucose tolerance in vivo. Therefore, pharmacologic modulation of these channels might provide an interesting approach for the development of novel insulinotropic drugs.