Inclusive taxon sampling suggests a single,stepwise origin of ectolecithality in Platyhelminthes

Ectolecithality is a form of oogenesis unique within Metazoa but common in Platyhelminthes, in which almost yolkless oocytes and tightly associated yolk cells are deposited together in egg capsules. Despite profound impacts on the embryogenesis and morphology of its beneficiaries, the origins of this developmental phenomenon remain obscure. Traditionally, all ectolecithal flatworms were grouped in a clade called Neoophora. However, there are also morphological arguments for multiple origins of ectolecithality and, to date, Neoophora has seen little support from molecular phylogenetic research, largely as a result of gaps in taxon sampling. Accordingly, we present a molecular phylogeny focused on resolving the deepest divergences among the free‐living Platyhelminthes. Species were chosen to completely span the diversity of all major endo‐ and ectolecithal clades, including several aberrant species of uncertain systematic affinity and, additionally, a thorough sampling of the ‘lecithoepitheliate’ higher taxa Prorhynchida and Gnosonesimida, respectively, under‐ and unrepresented in phylogenies to date. Our analyses validate the monophyly of all classical higher platyhelminth taxa, and also resolve a clade possessing distinct yolk‐cell and oocyte generating organs (which we name Euneoophora new taxon ). Furthermore, implied‐weights parsimony and Bayesian mixture model analyses suggest common ancestry of this clade with the lecithoepitheliates, implying that these taxa may retain a primitive form of ectolecithality. This topology thus corroborates the classical hypothesis of homology between yolk cells and oocytes in all Neoophora, and should serve to guide future evolutionary research on this unique developmental innovation in Platyhelminthes. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 570–588.     

A novel homoplasmic mutation in mtDNA with a single evolutionary origin as a risk factor for cardiomyopathy

To clarify the relationship between variation in mtDNA and the development of cardiomyopathy (CM), the complete sequences of mtDNAs of two brothers with dilated CM were compared with those of 181 patients who had CM and with those of 168 control subjects. Five patients with CM shared a novel homoplasmic point mutation (G12192A tRNA(His)), and all of them demonstrated the evolutionarily related D-loop sequence. The results suggest that this novel mutation originated from the same ancestor and that its presence strongly predisposes carriers to CM.     

Advantages and disadvantages of large colony size in a halictid bee: the queen's perspective

The size of the group of social species might influence basicaspects of productivity and social interactions. In many primitivelysocial insects, foundress queens are basically in control ofthe number of workers in their first brood. We examined factorsthat might influence the optimal number of workers a queen shouldproduce during the solitary founding phase in Lasioglossum malachurum(Hymenoptera, Halictidae). A priori, it seems plausible thatshe should produce as many workers as possible (1) to maximizecolony productivity and (2) to minimize the impact of broodparasitoids. However, there might also be unfavorable consequencesof a large colony size from the queen's perspective. First,the queen might incur disproportionately high costs that decreaseher potential for subsequent reproduction. Second, the queenmight not be able to suppress the development of ovaries ina large number of workers. As a clear advantage of a large colonysize, we found an increased production of sexuals. Contraryto our expectation, in the first worker phase, nests that wereparasitized by Sphecodes bees had more workers than did unparasitizednests. We found no evidence that the production of the firstworker brood entailed costs to the queen. However, the degreeof development of worker ovaries increased with colony size,and some degree of development was detectable with as few asfour workers. This study shows that the number of workers aqueen produces might depend on the interaction of several factors,some of which have not been considered in detail yet.     

RbcL sequences indicate a single evolutionary origin of multinucleate cells in the red algal tribe Callithamnieae

In the Ceramiaceae, one of the largest families of the red algae, there are from 1 to 4000 nuclei in each vegetative cell, but each tribe is homogeneous with respect to the uninucleate/multinucleate character state, except for the Callithamnieae. The goals of this study were to analyze rbcL gene sequences to clarify the evolution of taxa within the tribe Callithamnieae and to evaluate the potential evolutionary significance of the development of multinucleate cells in certain taxa. The genus Aglaothamnion, segregated from Callithamnion because it is uninucleate, was paraphyletic in all analyses. Callithamnion (including Aristothamnion) was monophyletic although not robustly so, apparently due to variations between taxa in rate of sequence evolution. Morphological synapomorphies were identified at different depths in the tree, supporting the molecular phylogenetic analysis. The uninucleate character state is ancestral in this tribe. The evolution of multinucleate cells has occurred once in the Callithamnieae. Multiple nuclei in each cell may combine the benefits of small C values (rapid cell cycle) with large cells (permitting morphological elaboration) while maintaining a constant ratio of nuclear volume: cytoplasmic volume.     

A single Banana streak virus integration event in the banana genome as the origin of infectious endogenous pararetrovirus

Sequencing of plant nuclear genomes reveals the widespread presence of integrated viral sequences known as endogenous pararetroviruses (EPRVs). Banana is one of the three plant species known to harbor infectious EPRVs. Musa balbisiana carries integrated copies of Banana streak virus (BSV), which are infectious by releasing virions in interspecific hybrids. Here, we analyze the organization of the EPRV of BSV Goldfinger (BSGfV) present in the wild diploid M. balbisiana cv. Pisang Klutuk Wulung (PKW) revealed by the study of Musa bacterial artificial chromosome resources and interspecific genetic cross. cv. PKW contains two similar EPRVs of BSGfV. Genotyping of these integrants and studies of their segregation pattern show an allelic insertion. Despite the fact that integrated BSGfV has undergone extensive rearrangement, both EPRVs contain the full-length viral genome. The high degree of sequence conservation between the integrated and episomal form of the virus indicates a recent integration event; however, only one allele is infectious. Analysis of BSGfV EPRV segregation among an F1 population from an interspecific genetic cross revealed that these EPRV sequences correspond to two alleles originating from a single integration event. We describe here for the first time the full genomic and genetic organization of the two EPRVs of BSGfV present in cv. PKW in response to the challenge facing both scientists and breeders to identify and generate genetic resources free from BSV. We discuss the consequences of this unique host-pathogen interaction in terms of genetic and genomic plant defenses versus strategies of infectious BSGfV EPRVs.     

A single origin of Batesian mimicry among hybridizing populations of admiral butterflies (Limenitis arthemis) rejects an evolutionary reversion to the ancestral phenotype

Batesian mimicry is a fundamental example of adaptive phenotypic evolution driven by strong natural selection. Given the potentially dramatic impacts of selection on individual fitness, it is important to understand the conditions under which mimicry is maintained versus lost. Although much empirical and theoretical work has been devoted to the maintenance of Batesian mimicry, there are no conclusive examples of its loss in natural populations. Recently, it has been proposed that non-mimetic populations of the polytypic Limenitis arthemis species complex represent an evolutionary loss of Batesian mimicry, and a reversion to the ancestral phenotype. Here, we evaluate this conclusion using segregating amplified fragment length polymorphism markers to investigate the history and fate of mimicry among forms of the L. arthemis complex and closely related Nearctic Limenitis species. In contrast to the previous finding, our results support a single origin of mimicry within the L. arthemis complex and the retention of the ancestral white-banded form in non-mimetic populations. Our finding is based on a genome-wide sampling approach to phylogeny reconstruction that highlights the challenges associated with inferring the evolutionary relationships among recently diverged species or populations (i.e. incomplete lineage sorting, introgressive hybridization and/or selection).     

Molecular phylogeny suggests a single origin of insect symbiosis in the Pucciniomycetes with support for some relationships within the genus Septobasidium

In the Pucciniomycetes, a class of fungi that includes the plant pathogenic rust fungi, insect parasitism is restricted to a single family, the Septobasidiaceae. The Septobasidiaceae form a variety of symbioses with scale insects and have remained largely unstudied since the 1930s. Transitions between plant and animal parasitism and between mutualism and parasitism cannot be fully addressed in the Basidiomycota without a clear phylogenetic hypothesis for the Septobasidiales. Here, molecular phylogenetic methods were applied to understand the origin of scale insect parasitism, test the monophyly of the order Septobasidiales, and evaluate the infrageneric concepts in the largest genus of scale insect parasites, Septobasidium. DNA sequence data from rRNA genes were used to infer higher-level relationships within the Pucciniomycetes, and data from translation elongation factor 1-alpha (tef1) were added for phylogenetic inference within the Septobasidiaceae. Data from tef1 revealed different intron arrangements within Septobasidium, but the molecule did not provide much additional phylogenetically informative data. Likelihood-model-based phylogenetic analyses of 44 Pucciniomycotina taxa provided moderate support for a single origin of insect parasitism. Within the Septobasidiaceae, there was little or no support for a monophyletic Septobasidium, and well-resolved subclades of Septobasidium species contradict previous morphological delimitations of groups within the genus.     

The analysis of three markers flanking GJB2 gene suggests a single origin of the most common 35delG mutation in the Moroccan population

In Caucasian populations a single mutation, 35delG, accounts for the majority of GJB2 gene mediated hearing loss, with carrier frequencies estimated between 2-4%, possibly resulting from a founder effect rather than from a mutational hot spot. In Moroccan population, the 35delG mutation accounts for 90.8% of all GJB2 mutated alleles in deaf patients with a carrier frequency of 2.65%. The aim of this study was to evaluate whether the 35delG mutation has derived from a single origin in the Moroccan population. We enrolled 30 unrelated deaf patients homozygous for the 35delG mutation and 165 unrelated control individuals negative for this mutation, and genotyped three microsatellite markers flanking the GJB2 region: D13S141, D13S175 and D13S143. Data analysis revealed that the 35delG mutation is associated with particular alleles of these markers, with significant linkage disequilibrium for the 125 and 105 nucleotide long alleles of D13S141 and D13S175, and that a single specific haplotype accounts for 68% of the chromosomes carrying the 35delG mutation. The estimate age of 35delG mutation is 135 generations or approximately 2700 years old. Like in other Mediterranean populations, our results suggest that in the Moroccan population the 35delG mutation has derived from a single origin in a common founder process.     

A single origin of gall association in a group of parasitic wasps with disparate morphologies

The braconid wasp subfamily Doryctinae mainly comprises idiobiont ectoparasitoids of other insect larvae. In recent years, however, members of a few genera have been discovered to be associated with galls from various unrelated host plant families, with some of these being gall inducers whereas others are suspected as being predators of gallers. Because of their considerable morphological differences, these gall-associated taxa traditionally have been placed in separate tribes or even in other subfamilies. In this study, we investigate the phylogenetic relationships among representatives of a number of different doryctine genera, including five of its seven gall-associated genera using two genetic markers. Here we analyzed the length-variable 28S sequence data based on secondary structure both excising the unalignable regions and recoding them according to indel length. In addition, multiple alignments were carried out with a range of gap-opening and extension parameters. The combined (28S+CO1) phylogenetic hypotheses obtained, both excluding and recoding the unalignable regions, recover a clade comprising the five gall-associated genera, and most of the analyses using multiple alignments also support this relationship. These results support a scenario in which secondary phytophagy evolves from initially attacking primary gall-forming hosts. The relationships recovered are also more congruent with a model that explains the macroevolution of insect plant association in the Doryctinae as reflecting geographic proximity rather than host plant relationships. Further, our phylogenetic hypotheses consistently show that one of the main morphological features employed in the higher level classification of the Doryctinae is actually highly homoplastic.     

A multigene phylogeny of Galliformes supports a single origin of erectile ability in non-feathered facial traits

Many species in the avian order Galliformes have bare (or fleshy) regions on their head, ranging from simple featherless regions to specialized structures such as combs or wattles. Sexual selection for these traits has been demonstrated in several species within the largest galliform family, the Phasianidae, though it has also been suggested that such traits are important in heat loss. These fleshy traits exhibit substantial variation in shape, color, location and use in displays, raising the question of whether these traits are homologous. To examine the evolution of fleshy traits, we estimated the phylogeny of galliforms using sequences from four nuclear loci and two mitochondrial regions. The resulting phylogeny suggests multiple gains and/or losses of fleshy traits. However, it also indicated that the ability to erect rapidly the fleshy traits is restricted to a single, well-supported lineage that includes species such as the wild turkey Meleagris gallopavo and ring-necked pheasant Phasianus colchicus . The most parsimonious interpretation of this result is a single evolution of the physiological mechanisms that underlie trait erection despite the variation in color, location, and structure of fleshy traits that suggest other aspects of the traits may not be homologous.     

A novel technology allowing immunohistochemical staining of a tissue section with 50 different antibodies in a single experiment.

Immunohistochemical (IHC) examination is frequently necessary for a histological differential diagnosis of tumors. To simplify IHC examination, we have developed a novel device called a "multiplex-immunostain chip (MI chip)." The chip is a panel of antibodies contained in a silicon rubber plate that consists of 50 2-mm-diameter wells. A tissue section slide is placed on the plate and is fastened tightly with a specially designed clamp. The plate with the slide is then turned upside down, which applies the antibodies to the section. This technology allows IHC staining of a tissue section with 50 different antibodies in a single experiment, reducing the time, effort, and expense of IHC analysis. In addition, it enables pathologists to compare expression of multiple antigens on a tissue section simply by changing microscopic fields on a single slide. These features are unique to the MI chip technology. The method requires no expensive instruments. This device can be used in various applications in differential diagnosis of tumors and the field of cell biology.     

A factor analysis of associations among self-reported immune related symptoms in a large twin sample.

We examined the cumulative prevalences of 22 symptoms thought to reflect immune system function reported in a questionnaire mailed to 7616 Australian twins. The associations between symptoms and demographic variables were expressed in terms of polychoric or polyserial correlations, and a principal components analysis performed. Factors representing underlying propensities respectively to allergic disease, various minor infections, diseases associated with aging such as arthritis, skin disease, and respiratory tract infection were extracted. Possible processes underlying these symptom clusters and the relative strengths and weaknesses of this type of analysis are discussed.     

A system for analyzing the event timing profile of single cells by using a model of neurite maturation in PC12D cells

Nerve growth factor (NGF)-induced neurite maturation in PC12D cells involves neuritogenesis and neurite outgrowth. Actions of compounds affecting the neurite maturation are sometimes invisible behind the individually variable events in nature even in the clonal population. In this study, we designed a time-lapse imaging system to determine the timing of each event in individual PC12D cells. To examine the system, we analyzed the effect of staurosporine on the neurite maturation in PC12D cells. By using the system, we obtained four event timing data sets (stimulation by NGF with and without staurosporine at the concentrations of 0.01, 0.1, and 1 microM). A permutation test of these data sets revealed that staurosporine caused an early induction of neurite outgrowth during neurite maturation in PC12D cells. These results suggest that the time-lapse imaging system to determine the timing of each event in individual cells can provide a novel insight into features of a cell mass by single-cell analysis and is expected to be utilized for profiling of compounds that can serve as candidate drugs.     

A novel method for estimating substitution rate variation among sites in a large dataset of homologous DNA sequences

We present here a novel method to estimate the site-specific relative variability in large sets of homologous sequences. It is based on the simple idea that the more closely related are the compared sequences, the higher the probability of observing nucleotide changes at rapidly evolving sites. A simulation study has been carried out to support the reliability of the method, which has been applied also to analyzing the site variability of all available human sequences corresponding to the two hypervariable regions of the mitochondrial D-loop.     

A comparison of trends in population size and life history features of Atlantic salmon (Salmo salar) and anadromous and non-anadromous Brown trout (Salmo trutta) in a single catchment over 116 years

Hydrobiologia - We use a long time series of catch abundance from a recreational fishery over 116 years to look for population trends in Atlantic salmon, and anadromous (sea trout) and...