Single Common Origin Research Articles

Timely signs, dominance, and vernal celebrations in late imperial Southern China

The aim of this essay is to contribute to the anthropological exploration of “traditional culture” in the Chinese south. Focussing on a description of one early-spring celebration in a township in Jiangxi Province, it suggests that these ceremonies are connected only superficially with local society and therefore lack a local message. A brief comparison suggests that there was nationwide conformity in the staging of these ceremonies, a degree of conventionality pointing to a single common origin —the discourse of the imperial state. Supreme dominance was articulated in ways that made the idea of the omnipotent emperor blessing his country manifest locally. Historically foreign to local southern societies, the festival was concerned with political incorporation, while still maintaining a degree of social alienation in that its main rituals were performed by the local state administrators alone. Demotic responses in local southern cultural contexts were limited and different.

3-D imaging reveals four extraordinary cases of convergent evolution of acoustic communication in crickets and allies (Insecta)

When the same complex trait is exhibited by closely related species, a single evolutionary origin is frequently invoked. The complex stridulatory apparatus present in the forewings of extant crickets, mole crickets, katydids, and prophalangopsids, is currently interpreted as sharing a single common origin due to their similarity and unique function. An alternative hypothesis of convergent evolution in these ensiferan groups has challenged this common view, but remained controversial because of competing interpretations of wing venation. Here we propose another hypothesis for the widely and long debated homology of ensiferan stridulatory apparatus, performing the first 3D reconstruction of hidden structures at the wing bases. This approach allowed defining the homology of each vein from its very origin rather than after its more distal characteristics, which may be subjected to environmental pressure of selection. The stridulatory apparatus involves different veins in these four singing clades. In light of the most recent phylogenetic evidence, this apparatus developed four times in Ensifera, illustrating extraordinary convergent evolutions between closely related clades, by far exceeding the number of evolutionary steps ever proposed for calling ability in this group.

Polycystic ovary syndrome: Understanding the role of the brain.

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder and the leading cause of anovulatory infertility. Characterised by hyperandrogenism, menstrual dysfunction and polycystic ovaries, PCOS is a broad-spectrum disorder unlikely to stem from a single common origin. Although commonly considered an ovarian disease, the brain is now a prime suspect in both the ontogeny and pathology of PCOS. We discuss here the neuroendocrine impairments present in PCOS that implicate involvement of the brain and review evidence gained from pre-clinical models of the syndrome about the specific brain circuitry involved. In particular, we focus on the impact that developmental androgen excess and adult hyperandrogenemia have in programming and regulating brain circuits important in the central regulation of fertility. The studies discussed here provide compelling support for the importance of the brain in PCOS ontogeny and pathophysiology and highlight the need for a better understanding of the underlying mechanisms involved.

Bilaterian Giant Ankyrins Have a Common Evolutionary Origin and Play a Conserved Role in Patterning the Axon Initial Segment.

In vertebrate neurons, the axon initial segment (AIS) is specialized for action potential initiation. It is organized by a giant 480 Kd variant of ankyrin G (AnkG) that serves as an anchor for ion channels and is required for a plasma membrane diffusion barrier that excludes somatodendritic proteins from the axon. An unusually long exon required to encode this 480Kd variant is thought to have been inserted only recently during vertebrate evolution, so the giant ankyrin-based AIS scaffold has been viewed as a vertebrate adaptation for fast, precise signaling. We re-examined AIS evolution through phylogenomic analysis of ankyrins and by testing the role of ankyrins in proximal axon organization in a model multipolar Drosophila neuron (ddaE). We find giant isoforms of ankyrin in all major bilaterian phyla, and present evidence in favor of a single common origin for giant ankyrins and the corresponding long exon in a bilaterian ancestor. This finding raises the question of whether giant ankyrin isoforms play a conserved role in AIS organization throughout the Bilateria. We examined this possibility by looking for conserved ankyrin-dependent AIS features in Drosophila ddaE neurons via live imaging. We found that ddaE neurons have an axonal diffusion barrier proximal to the cell body that requires a giant isoform of the neuronal ankyrin Ank2. Furthermore, the potassium channel shal concentrates in the proximal axon in an Ank2-dependent manner. Our results indicate that the giant ankyrin-based cytoskeleton of the AIS may have evolved prior to the radiation of extant bilaterian lineages, much earlier than previously thought.

Методика номинализации значений высотных реперов нивелирных сетей

Abstract: The article proposes a method of so-called frames nominalization of normal height, which can lead normal values heights old or new frames in a single start. By nominalization, we will realize the establishment of the normal height of the existing or new frames for any high-altitude systems. The main property of these frames will be that they are based on a single common origin – the surface, the actual potential W0 is equal to the potential U0 of the normal gravity field common terrestrial ellipsoid, i.e. W U 0 0 = . The enough to have at least one value of height anomalies ζ(B,L) in a predetermined area for the selected common terrestrial ellipsoid to implement this methodology. The use of this methodology can significantly reduce the number of calculation grid reference points of height anomalies (hundreds of thousands of times).

Genetic evidence for two founding populations of the Americas.

Genetic studies have been consistent with a single common origin of Native American groups from Central and South America1-4. However, some morphological studies have suggested a more complex picture, whereby the northeast Asian affinities of present-day Native Americans contrast with a distinctive morphology seen in some of the earliest American skeletons, which share traits with present-day Australasians (indigenous groups in Australia, Melanesia, and island southeast Asia)5-8. Here we analyze genome-wide data to show that some Amazonian Native Americans descend partly from a Native American founding population that carried ancestry more closely related to indigenous Australians, New Guineans and Andaman Islanders than to any present-day Eurasians or Native Americans. This signature is not present to the same extent or at all in present-day Northern and Central Americans or a ~12,600 year old Clovis genome, suggesting a more diverse set of founding populations of the Americas than previously accepted.

Multiple molecular mechanisms for chronic myeloid leukemia progression, but a possible single common origin: the genetic instability

La leucemie myeloide chronique (LMC) s’apparente a un modele simple d’oncogenese puisqu’une anomalie – la translocation reciproque t(9;22)(q34;q11) conduisant a la fusion des genes BCR et ABL – suffit a poser le diagnostic. Sa progression se caracterise par des variations genotypiques et phenotypiques de la cellule cancereuse engagee dans la differenciation myeloide : le progeniteur granulocyte-macrophage perd ses capacites de differenciation cellulaire et d’apoptose, et retrouve des proprietes de cellules souches. Ces modifications moleculaires s’accompagnent de l’accumulation de nombreuses lesions et du changement du profil d’expression des genes. Fait surprenant, a la succession de trois phases d’evolution de la maladie (phase chronique, phase acceleree et phase blastique) se superpose, au niveau moleculaire, deux phases seulement de variations du profil du transcriptome, les profils d’expression de la phase acceleree et de la phase blastique etant similaires. Cela suggere un phenomene d’irreversibilite de la progression. Par ailleurs, la grande heterogeneite des lesions observees ne permet pas de definir un profil particulier, et revele la complexite des mecanismes pouvant intervenir dans la progression de la maladie. Seule la source de ces variabilites est tres probablement commune : elle pourrait etre liee a une augmentation du stress oxydatif de la cellule souche cancereuse. En effet, la production d’especes oxygenees reactives (ROS) est a l’origine des mutations et des cassures de l’ADN. De plus, BCR-ABL favoriserait l’augmentation de ROS et la persistance des lesions par des mecanismes de reparations alteres. Les cellules souches leucemiques sont donc une sorte de reservoir de cellules susceptibles d’initier la progression de la maladie. Or, ces cellules sont insensibles aux inhibiteurs de tyrosine kinases, n’etant pas dependantes du signal BCR-ABL pour leur survie. Cela explique le risque eleve d’echec des therapies ciblees dans les phases avancees de la maladie. Dans cette revue de la litterature, nous essayons de dresser un etat des connaissances sur les mecanismes de la progression de la LMC, qui, s’il n’est pas exhaustif, est du moins illustratif de la multiplicite et de la complexite des procedes mis en jeu. Concernant les perspectives therapeutiques : ce sont les strategies d’associations medicamenteuses ciblant a la fois BCR-ABL et les mecanismes essentiels a la persistance des cellules souches leucemiques, associations encore en developpement preclinique plus la plupart, et dont nous rapportons quelques exemples, qui sont a l’etude. Ainsi, actuellement, eradiquer la maladie pour maitriser sa progression reste encore un defi.

The Evolutionary Histories of Clinical and Environmental SHV β-Lactamases are Intertwined

The rise of antibiotic-resistant pathogens focuses our attention on the source of antibiotic resistance genes, on the existence of these genes in environments exposed to little or no antibiotics, and on the relationship between resistance genes found in the clinic and those encountered in non-clinical settings. Here, we address the evolutionary history of a class of resistance genes, the SHV β-lactamases. We focus on bla SHV genes isolated both from clinical and non-clinical sources and show that clinically important resistance determinants arise repeatedly from within a diverse pool of bla SHV genes present in the environment. While our results argue against the notion of a single common origin for all clinically derived bla SHV genes, we detect a characteristic selective signature shaping this protein in clinical environments. This clinical signature reveals the joint action of purifying and positive selection on specific residues, including those known to confer extended-spectrum activity. Surprisingly, antibiotic resistance genes isolated from non-clinical-and presumably antibiotic-free-settings also experience the joint action of purifying and positive selection. The picture that emerges undercuts the notion of a separate reservoir of antibiotic resistance genes confined only to clinical settings. Instead, we argue for the presence of a single extensive and variable pool of antibiotic resistance genes present in the environment.

Phylogenetic and Phyletic Studies of Informational Genes in Genomes Highlight Existence of a 4th Domain of Life Including Giant Viruses

The discovery of Mimivirus, with its very large genome content, made it possible to identify genes common to the three domains of life (Eukarya, Bacteria and Archaea) and to generate controversial phylogenomic trees congruent with that of ribosomal genes, branching Mimivirus at its root. Here we used sequences from metagenomic databases, Marseillevirus and three new viruses extending the Mimiviridae family to generate the phylogenetic trees of eight proteins involved in different steps of DNA processing. Compared to the three ribosomal defined domains, we report a single common origin for Nucleocytoplasmic Large DNA Viruses (NCLDV), DNA processing genes rooted between Archaea and Eukarya, with a topology congruent with that of the ribosomal tree. As for translation, we found in our new viruses, together with Mimivirus, five proteins rooted deeply in the eukaryotic clade. In addition, comparison of informational genes repertoire based on phyletic pattern analysis supports existence of a clade containing NCLDVs clearly distinct from that of Eukarya, Bacteria and Archaea. We hypothesize that the core genome of NCLDV is as ancient as the three currently accepted domains of life.

Breakpoint structure of the Anopheles gambiae 2Rb chromosomal inversion

BackgroundAlternative arrangements of chromosome 2 inversions in Anopheles gambiae are important sources of population structure, and are associated with adaptation to environmental heterogeneity. The forces responsible for their origin and maintenance are incompletely understood. Molecular characterization of inversion breakpoints provides insight into how they arose, and provides the basis for development of molecular karyotyping methods useful in future studies.MethodsSequence comparison of regions near the cytological breakpoints of 2Rb allowed the molecular delineation of breakpoint boundaries. Comparisons were made between the standard 2R+b arrangement in the An. gambiae PEST reference genome and the inverted 2Rb arrangements in the An. gambiae M and S genome assemblies. Sequence differences between alternative 2Rb arrangements were exploited in the design of a PCR diagnostic assay, which was evaluated against the known chromosomal banding pattern of laboratory colonies and field-collected samples from Mali and Cameroon.ResultsThe breakpoints of the 7.55 Mb 2Rb inversion are flanked by extensive runs of the same short (72 bp) tandemly organized sequence, which was likely responsible for chromosomal breakage and rearrangement. Application of the molecular diagnostic assay suggested that 2Rb has a single common origin in An. gambiae and its sibling species, Anopheles arabiensis, and also that the standard arrangement (2R+b) may have arisen twice through breakpoint reuse. The molecular diagnostic was reliable when applied to laboratory colonies, but its accuracy was lower in natural populations.ConclusionsThe complex repetitive sequence flanking the 2Rb breakpoint region may be prone to structural and sequence-level instability. The 2Rb molecular diagnostic has immediate application in studies based on laboratory colonies, but its usefulness in natural populations awaits development of complementary molecular tools.

Independent Origins of New Sex-Linked Chromosomes in the melanica and robusta Species Groups of Drosophila

BackgroundRecent translocations of autosomal regions to the sex chromosomes represent important systems for identifying the evolutionary forces affecting convergent patterns of sex-chromosome heteromorphism. Additions to the sex chromosomes have been reported in the melanica and robusta species groups, two sister clades of Drosophila. The close relationship between these two species groups and the similarity of their rearranged karyotypes motivates this test of alternative hypotheses; the rearranged sex chromosomes in both groups are derived through a common origin, or the rearrangements are derived through at least two independent origins. Here we examine chromosomal arrangement in representatives of the melanica and the robusta species groups and test these alternative hypotheses using a phylogenetic approach.ResultsTwo mitochondrial and two nuclear gene sequences were used to reconstruct phylogenetic relationships of a set of nine ingroup species having fused and unfused sex chromosomes and representing a broad sample of both species groups. Different methods of phylogenetic inference, coupled with concurrent cytogenetic analysis, indicate that the hypothesis of independent origins of rearranged sex chromosomes within each species group is significantly more likely than the alternative hypothesis of a single common origin. An estimate tightly constrained around 8 My was obtained for the age of the rearranged sex chromosomes in the melanica group; however, a more loosely constrained estimate of 10–15 My was obtained for the age of the rearrangement in the robusta group.ConclusionIndependent acquisition of new chromosomal arms by the sex chromosomes in the melanica and robusta species groups represents a case of striking convergence at the karyotypic level. Our findings indicate that the parallel divergence experienced by newly sex-linked genomic regions in these groups represents an excellent system for studying the tempo of sex chromosome evolution.

Molecular evidence for a single common origin of chromalveolate plastids

Plastids (photosynthetic organelles of plants and algae) are known to have spread between eukaryotic lineages by secondary endosymbiosis, or the uptake of a eukaryotic alga by another eukaryote, but the number of times this has taken place is controversial. This is particularly so in the case of eukaryotes with plastids derived from red algae, which are numerous and diverse. Despite their diversity, it has been suggested that all these eukaryotes share a recent common ancestor and that their plastids originated in a single endosymbiosis, the so‐called “chromalveolate hypothesis”. Here, we describe a novel molecular character that supports the chromalveolate hypothesis. Fructose‐1,6‐bisphosphate aldolase (FBA) is a glycolytic/Calvin cycle enzyme that exists as one of two non‐homologous types, class I and class II. Red algal plastid‐targeted FBA is a class I enzyme related to homologues from plants and green algae, and it would be predicted that the plastid‐targeted FBA from algae with red algal secondary endosymbionts should be related to this class I enzyme. However, we show that heterokonts, cryptomonads, haptophytes and dinoflagellates (all photosynthetic chromalveolates) encode two paralogous class II enzymes, one of which strongly supports a specific relationship between chromalveolates. Exactly where chromalveolates got their plastid‐targeted FBA genes is presently uncertain, but their common possession of this unexpected plastid characteristic is compelling evidence for their close relationship and a common origin for their plastids.

Molecular phylogeny of Asian termites (Isoptera) of the families Termitidae and Rhinotermitidae based on mitochondrial COII sequences

The families Termitidae and Rhinotermitidae are the most evolved and diverse groups of the social insects, termites (Order Isoptera), showing elaborated morphology and complex behavior. Molecular phylogeny of termites with the emphasis on these families was examined by Bayesian and maximum-likelihood analyses based on DNA sequence of mitochondrial cytochrome oxidase II (COII) gene of 31 genera sampled in Asia (mainly Thailand and Japan) along with those reported previously. Termitidae was monophyletic and originated from within polyphyletic Rhinotermitidae. Among the four subfamilies of Termitidae, Macrotermitinae was monophyletic suggesting a single common origin of fungus-growing habit characteristic for this subfamily, and was placed in the basal position in the family. A group consisting of other subfamilies Termitinae and Nasutitermitinae, though some important groups were still untouched, was the most apical but neither Termitinae nor Nasutitermitinae formed a monophyletic lineage. It was implied that, as defense systems of the soldier castes, the appearance of snapping mandibles has occurred at a single event, but the development of nasus for chemical secretion has probably not. Our tree provides some evidence concerning contradictions in the previously proposed phylogeny of termites.

Nuclear-encoded, plastid-targeted genes suggest a single common origin for apicomplexan and dinoflagellate plastids.

The phylum Apicomplexa encompasses a large number of intracellular protozoan parasites, including the causative agents of malaria (Plasmodium), toxoplasmosis (Toxoplasma), and many other human and animal diseases. Apicomplexa have recently been found to contain a relic, nonphotosynthetic plastid that has attracted considerable interest as a possible target for therapeutics. This plastid is known to have been acquired by secondary endosymbiosis, but when this occurred and from which type of alga it was acquired remain uncertain. Based on the molecular phylogeny of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes, we provide evidence that the apicomplexan plastid is homologous to plastids found in dinoflagellates-close relatives of apicomplexa that contain secondary plastids of red algal origin. Surprisingly, apicomplexan and dinoflagellate plastid-targeted GAPDH sequences were also found to be closely related to the plastid-targeted GAPDH genes of heterokonts and cryptomonads, two other groups that contain secondary plastids of red algal origin. These results address several outstanding issues: (1) apicomplexan and dinoflagellate plastids appear to be the result of a single endosymbiotic event which occurred relatively early in eukaryotic evolution, also giving rise to the plastids of heterokonts and perhaps cryptomonads; (2) apicomplexan plastids are derived from a red algal ancestor; and (3) the ancestral state of apicomplexan parasites was photosynthetic.

Multiplicity of macrolide-lincosamide-streptogramin antibiotic resistance determinants.

Bacteria can resist macrolide, lincosamide, and streptogramin (MLS) antibiotics enzymically by alteration of the target site or detoxification of the antibiotic. N6-dimethylation of adenine in 23 S ribosomal RNA confers resistance to M, L, and S B-type (MLSB) antibiotics. Investigation, by DNA annealing, of the relationship between the genes specifying this resistance mechanism from Streptococcus (groups A,B,D, and H, and pneumoniae), Staphylococcus aureus, Bacillus licheniformis, Bacteroides fragilis, Lactobacillus casei, and Streptomyces erythreus indicated substantial sequence diversity among the MLSB resistance (R) determinants. A minimum of four distinct classes of MLSB R determinants could be defined: classes A and B for the Gram-positive cocci (streptococci pmeumococci and staphylococci), class C for B. licheniformis, and class D for Bact. fragilis. These data do not support the hypothesis that the R determinants were acquired recently from a single common origin and suggest an easy exchange of genetic information among the Gram-positive cocci. The genetic classes do not correlate with differences in phenotypic expression or in regulation (inducibility or constitutivity) of resistance towards MLSB antibiotics. Inactivation of the drug confers resistance to M and/or L and/or S or SA or SB antibiotics and has been detected in strains of Streptococcus, Staph. aureus, Lactobacillus, C. perfringens, Streptomyces, and recently in the Gram-negative organism Escherichia coli. We have cloned and sequenced a DNA fragment conferring high level resistance (MIC greater than 2 g/l) to erythromycin by hydrolysis of the antibiotic. The distribution of this 'new' character in enterobacteria isolated from human faeces was studied by colony hybridization using an intragenic probe. The gene for the erythromycin esterase was detected in numerous strains of E. coli belonging to various biotypes, in Klebsiella pneumoniae, Enterobacter agglomerans, and in one 'coliform'. Moreover, our results indicated the existence of at least two classes of genes specifying resistance to erythromycin by inactivation of the antibiotic in enterobacteria.

Courtship and Mating Behavior in the Yellow Mud Turtle, Kinosternon flavescens flavescens

Courtship and mating behavior were observed in captive Kinosternon flavescens flavescens. Members of this species have, in part, a specialized and unique pattern that otherwise conforms with previous descriptions of such behavior in kinosternid turtles. The same courtship and mating procedure was also observed in Kinosternon baurii palmarum. Courtship and mating were divided into 3 general phases: tactile; initial mounting; and copulatory. Observations suggest that species of Sternotherus and Kinosternon have each developed their own specialized courtship and mating pattern that may have been derived from a single common origin.

Interspecific Sterility

THE implications of modern genetics have been so little considered by biologists in this country that the criticism of my address by Dr. Cunningham (NATURE, June 17), though in purpose destructive, is not unwelcome. Of the points he raises one chiefly calls for reply. I directed once more the attention of naturalists to the fact that we still await the production of an indubitably sterile hybrid from completely fertile parents which have arisen under critical observation from a single common origin. So far as our knowledge goes, all the domesticated races—for example, of dogs, of pigeons, of fowls among animals; and of cabbages, of peas, of Primula sinensis, and many more among plants—when intercrossed among themselves never produce this sterility in their mongrels, though the races are often distinct enough to pass for species. But if we begin crossing natural species, even those which on our reckoning must be very closely allied, we constantly find either that they will not interbreed, or that, if they can be crossed, the result is more or less sterile. Dr. Cunningham takes exception to my speaking of this interspecific sterility as the chief attribute of species, but he will not dispute that it is a chief attribute of species.