Ecological speciation in sympatric palms: 2. Pre- and post-zygotic isolation.

We evaluated reproductive isolation in two species of palms (Howea) that have evolved sympatrically on Lord Howe Island (LHI, Australia). We estimated the strength of some pre- and post-zygotic mechanisms in maintaining current species boundaries. We found that flowering time displacement between species is consistent across in and ex situ common gardens and is thus partly genetically determined. On LHI, pre-zygotic isolation due solely to flowering displacement was 97% for Howea belmoreana and 80% for H. forsteriana; this asymmetry results from H. forsteriana flowering earlier than H. belmoreana and being protandrous. As expected, only a few hybrids (here confirmed by genotyping) at both juvenile and adult stages could be detected in two sites on LHI, in which the two species grow intermingled (the Far Flats) or adjacently (Transit Hill). Yet, the distribution of hybrids was different between sites. At Transit Hill, we found no hybrid adult trees, but 13.5% of younger palms examined there were of late hybrid classes. In contrast, we found four hybrid adult trees, mostly of late hybrid classes, and only one juvenile F1 hybrid in the Far Flats. This pattern indicates that selection acts against hybrids between the juvenile and adult stages. An in situ reciprocal seed transplant between volcanic and calcareous soils also shows that early fitness components (up to 36 months) were affected by species and soil. These results are indicative of divergent selection in reproductive isolation, although it does not solely explain the current distribution of the two species on LHI.

Ecological speciation in sympatric palms: 1. Gene expression, selection and pleiotropy.

Ecological speciation requires divergent selection, reproductive isolation and a genetic mechanism to link the two. We examined the role of gene expression and coding sequence evolution in this process using two species of Howea palms that have diverged sympatrically on Lord Howe Island, Australia. These palms are associated with distinct soil types and have displaced flowering times, representing an ideal candidate for ecological speciation. We generated large amounts of RNA-Seq data from multiple individuals and tissue types collected on the island from each of the two species. We found that differentially expressed loci as well as those with divergent coding sequences between Howea species were associated with known ecological and phenotypic differences, including response to salinity, drought, pH and flowering time. From these loci, we identified potential 'ecological speciation genes' and further validate their effect on flowering time by knocking out orthologous loci in a model plant species. Finally, we put forward six plausible ecological speciation loci, providing support for the hypothesis that pleiotropy could help to overcome the antagonism between selection and recombination during speciation with gene flow.

The complex history of the olive tree: from Late Quaternary diversification of Mediterranean lineages to primary domestication in the northern Levant.

The location and timing of domestication of the olive tree, a key crop in Early Mediterranean societies, remain hotly debated. Here, we unravel the history of wild olives (oleasters), and then infer the primary origins of the domesticated olive. Phylogeography and Bayesian molecular dating analyses based on plastid genome profiling of 1263 oleasters and 534 cultivated genotypes reveal three main lineages of pre-Quaternary origin. Regional hotspots of plastid diversity, species distribution modelling and macrofossils support the existence of three long-term refugia; namely the Near East (including Cyprus), the Aegean area and the Strait of Gibraltar. These ancestral wild gene pools have provided the essential foundations for cultivated olive breeding. Comparison of the geographical pattern of plastid diversity between wild and cultivated olives indicates the cradle of first domestication in the northern Levant followed by dispersals across the Mediterranean basin in parallel with the expansion of civilizations and human exchanges in this part of the world.

A comparative analysis of the mechanisms underlying speciation on Lord Howe Island.

On Lord Howe Island, speciation is thought to have taken place in situ in a diverse array of distantly related plant taxa (Metrosideros, Howea and Coprosma; Proc. Natl Acad. Sci. USA 108, 2011, 13188). We now investigate whether the speciation processes were driven by divergent natural selection in each genus by examining the extent of ecological and genetic divergence. We present new and extensive, ecological and genetic data for all three genera. Consistent with ecologically driven speciation, outlier loci were detected using genome scan methods. This mechanism is supported by individual-based analyses of genotype-environment correlations within species, demonstrating that local adaptation is currently widespread on the island. Genetic analyses show that prezygotic isolating barriers within species are currently insufficiently strong to allow further population differentiation. Interspecific hybridization was found in both Howea and Coprosma, and species distribution modelling indicates that competitive exclusion may result in selection against admixed individuals. Colonization of new niches, partly fuelled by the rapid generation of new adaptive genotypes via hybridization, appears to have resulted in the adaptive radiation in Coprosma - supporting the 'Syngameon hypothesis'.

Evaluating the transmission risk of SARS-CoV-2 from sewage pollution.

The presence of SARS-CoV-2 in untreated sewage has been confirmed in many countries but its incidence and infection risk in contaminated waters is poorly understood. The River Thames in the UK receives untreated sewage from 57 Combined Sewer Overflows (CSOs), with many discharging dozens of times per year. This study investigated if such discharges provide a pathway for environmental transmission of SARS-CoV-2. Samples of wastewater, surface water, and sediment collected close to six CSOs on the River Thames were assayed over eight months for SARS-CoV-2 RNA and infectious virus. Bivalves were also sampled as an indicator species of viral bioaccumulation. Sediment and water samples from the Danube and Sava rivers in Serbia, where raw sewage is also discharged in high volumes, were assayed as a positive control. No evidence of SARS-CoV-2 RNA or infectious virus was found in UK samples, in contrast to RNA positive samples from Serbia. Furthermore, this study shows that infectious SARS-CoV-2 inoculum is stable in Thames water and sediment for <3 days, while SARS-CoV-2 RNA is detectable for at least seven days. This indicates that dilution of wastewater likely limits environmental transmission, and that detection of viral RNA alone is not an indication of pathogen spillover.

Hybrid external fixation in treatment of proximal tibial fractures: a good outcome in AO/ASIF type-C fractures.

INTRODUCTION: The treatment of proximal tibial fractures is often challenging, and internal fixation is occasionally associated with problems in wound healing due to frequently co-existing soft tissue injuries. External fixation of these fractures have yielded satisfactory results, but some studies have reported problems in the achievement and maintenance of fracture reduction. The purpose of the present study was to evaluate the performance of a hybrid external fixator in the treatment of different types of proximal tibial fractures. MATERIALS AND METHODS: Thirty-three proximal tibial fractures, of which 20 were high energetic, were treated with a hybrid external fixator (Tenxor Strker-Howmedica) in the acute phase. Fracture categorisation was done according to AO/ASIF, and the reduction was performed most often by closed means or through mini-open reduction (26/78.8%). The patients were followed up to an average of 12.7 months (range 10-22) and were evaluated with radiographs and clinical examinations. RESULTS: Five AO/ASIF type-C intraarticular fractures had a poor postoperative reduction, and were thus treated with internal fixation in a second operation. Of the remaining 28 patients, local and transient pin tract infection was observed in seven patients, and one had septic arthritis of the knee. All 13 C1 and five of six C2/C3 fractures united in mean time of 15.1 weeks, whereas three of nine type-A fractures failed to unite, albeit an adequate reduction, and needed a second operation (odds ratio 11.4, 95% CI 1.0-143, compared with type-C fractures). For the remaining six type-A fractures, the mean healing time was 24 weeks (mean difference 8.9, 95% CI 6-12 weeks compared with type-C fractures). Age over 48 and the presence of an open fracture, but not fracture type, gender, or the level of injury energy, correlated to a poor subjective outcome. CONCLUSIONS: The hybrid external fixation method we have used is safe, and type-C1 fractures are particularly suitable to be treated with this method. However, even C2/C3 fractures may be candidates for this method, but a meticulous fracture reduction should be performed. Type-A fractures are liable to healing problems when the fixator is used as a rigid complex.

Phylogeny, biogeography, and ecology of Ficus section Malvanthera (Moraceae).

We conducted the first molecular phylogenetic study of Ficus section Malvanthera (Moraceae; subgenus Urostigma) based on 32 Malvanthera accessions and seven outgroups representing other sections of Ficus subgenus Urostigma. We used DNA sequences from the nuclear ribosomal internal and external transcribed spacers (ITS and ETS), and the glyceraldehyde-3-phosphate dehydrogenase (G3pdh) region. Phylogenetic analysis using maximum parsimony, maximum likelihood and Bayesian methods recovered a monophyletic section Malvanthera to the exclusion of the rubber fig, Ficus elastica. The results of the phylogenetic analyses do not conform to any previously proposed taxonomic subdivision of the section and characters used for previous classification are homoplasious. Geographic distribution, however, is highly conserved and Melanesian Malvanthera are monophyletic. A new subdivision of section Malvanthera reflecting phylogenetic relationships is presented. Section Malvanthera likely diversified during a period of isolation in Australia and subsequently colonized New Guinea. Two Australian series are consistent with a pattern of dispersal out of rainforest habitat into drier habitats accompanied by a reduction in plant height during the transition from hemi-epiphytic trees to lithophytic trees and shrubs. In contradiction with a previous study of Pleistodontes phylogeny suggesting multiple changes in pollination behaviour, reconstruction of changes in pollination behaviour on Malvanthera, suggests only one or a few gains of active pollination within the section.

Age-dependent association of apolipoprotein E genotype with coronary and aortic atherosclerosis in middle-aged men: an autopsy study.

BACKGROUND: Apolipoprotein E (apoE) polymorphism is one of the genetic determinants of serum cholesterol values. The apoE epsilon4 allele has been associated with advanced coronary heart disease (CHD) diagnosed by angiography, but the role of the apoE genotype in atherosclerosis has not been confirmed at vessel-wall level, nor is any age-dependent effect of the apoE genotype on the development of CHD known. METHODS AND RESULTS: The right and left anterior descending coronary arteries (RCA and LAD) and the aorta from 700 male autopsy cases (Helsinki Sudden Death Study) in 1981-1982 and 1991-1992 (average age 53 years, range 33 to 70 years) were stained for fat, and all areas covered with fatty streaks, fibrotic plaques, and complicated lesions were measured. In the RCA and LAD, the apoE genotype was significantly associated with the area of total atherosclerotic lesions in men <53 years old but not with that in older men (P=0.0085 and P=0.041, respectively, for age-by-genotype interaction). Men <53 years old with the epsilon4/3 genotype showed 61% larger total atherosclerotic lesion area in the RCA (P=0.0027) and 26% larger area in the LAD (P=0.12) than did men with the epsilon3/3. The apoE epsilon4/3 was also associated with atherosclerotic lesions in the abdominal (P=0.014) and thoracic (P=0.12) aorta, but this effect, unlike that of the coronary arteries, was not age-related. CONCLUSIONS: In men, the apoE epsilon4 allele is a significant genetic risk factor for coronary atherosclerosis in early middle age. This suggests that at older age, other known risk factors of CHD play a more important role in the atherosclerotic process than apoE polymorphisms.

Pertrochanteric femoral fractures treated with a dynamic hip screw or a proximal femoral nail. A randomised study comparing post-operative rehabilitation.

We treated 108 patients with a pertrochanteric femoral fracture using either the dynamic hip screw or the proximal femoral nail in this prospective, randomised series. We compared walking ability before fracture, intra-operative variables and return to their residence. Patients treated with the proximal femoral nail (n = 42) had regained their pre-operative walking ability significantly (p = 0.04) more often by the four-month review than those treated with the dynamic hip screw (n = 41). Peri-operative or immediate post-operative measures of outcome did not differ between the groups, with the exception of operation time. The dynamic hip screw allowed a significantly greater compression of the fracture during the four-month follow-up, but consolidation of the fracture was comparable between the two groups. Two major losses of reduction were observed in each group, resulting in a total of four revision operations. Our results suggest that the use of the proximal femoral nail may allow a faster post-operative restoration of walking ability, when compared with the dynamic hip screw.

Evolutionary rates and species diversity in flowering plants.

Genetic change is a necessary component of speciation, but the relationship between rates of speciation and molecular evolution remains unclear. We use recent phylogenetic data to demonstrate a positive relationship between species numbers and the rate of neutral molecular evolution in flowering plants (in both plastid and nuclear genes). Rates of protein and morphological evolution also correlate with the neutral substitution rate, but not with species numbers. Our findings reveal a link between the rate of neutral molecular change within populations and the evolution of species diversity.

The GPIIIa Pl(A) polymorphism in the progression of abdominal aortic atherosclerosis.

Glycoprotein IIIa is expressed in platelets as part of the fibrinogen receptor and also in vascular endothelium where it mediates smooth muscle cell proliferation. The association between the glycoprotein GPIIIa Pl(A) polymorphism and the stage of atherosclerosis in the abdominal aorta was studied in a prospective autopsy study series of 300 middle-aged men (33-69 years). The Pl(A) genotype was determined by RFLP-PCR. The stage of atherosclerosis in the abdominal aorta was determined by computer-assisted morphometry. Elevated, fibrous lesions were more frequently (P=0.05) found in the abdominal aortas of men with the Pl(A1) homozygous genotype compared to men with the A2 allele (OR 2.3; 95% CI 0.99-5.2). The area of complicated lesions was significantly greater in men with Pl(A2)-positive genotypes compared to A1 homozygotes. The association with complicated lesions was especially strong in men over 60 (P=0.002). These results suggest that Pl(A) polymorphism is involved in the progression of atherosclerosis in the abdominal aorta. The association of men possessing the Pl(A2) allele with slower development of fibrous lesions and with greater area of complicated lesions in the abdominal aorta may result from genotypic differences in the smooth muscle cell proliferation after slight injuries to the endothelium mediated by glycoprotein IIIa or from genotypic differences in platelet fibrinogen binding or both.

Association of FXIII Val34Leu with decreased risk of myocardial infarction in Finnish males.

Factor XIII is a transglutaminase that crosslinks fibrin in the last steps of the coagulation process. A few polymorphic sites have been identified in this gene, one of them being a point mutation (FXIII Val34Leu), leading to an amino acid change of valine to leucine. Recently, in British patients, FXIII 34Leu allele was suggested to be associated with a decreased incidence of myocardial infarction (MI). PAI-1 4G/4G genotype seemed to lessen the beneficial effect of FXIII 34Leu allele. The aim of our study was to further investigate the possible protective role of the FXIII 34Leu allele against MI and its suggested interaction with the PAI-1 4G/5G polymorphism. We carried out genotype analyses for FXIII Val34Leu using solid-phase minisequencing in two independent Finnish study groups. In our study, the FXIII 34Leu allele was associated with a lower risk of MI (P = 0.009), however, the PAI-1 4G allele showed no interaction with this polymorphism. To establish the population frequency of the FXIII 34Leu allele and to study the possible variations in Finland four DNA pools from different geographical areas of Finland were genotyped. No significant differences in the allele frequencies were observed (21-28%) except in the Eastern Kainuu area (13%), an area with an increased risk of mortality from coronary artery disease (CAD), supporting the results presented above. The association of FXIII 34Leu variant with a lower incidence of myocardial infarction suggests a new role for FXIII in a polygenic thrombotic disease.

Evolution of the angiosperms: calibrating the family tree.

Growing evidence of morphological diversity in angiosperm flowers, seeds and pollen from the mid Cretaceous and the presence of derived lineages from increasingly older geological deposits both imply that the timing of early angiosperm cladogenesis is older than fossil-based estimates have indicated. An alternative to fossils for calibrating the phylogeny comes from divergence in DNA sequence data. Here, angiosperm divergence times are estimated using non-parametric rate smoothing and a three-gene dataset covering ca. 75% of all angiosperm families recognized in recent classifications. The results provide an initial hypothesis of angiosperm diversification times. Using an internal calibration point, an independent evaluation of angiosperm and eudicot origins is performed. The origin of the crown group of extant angiosperms is indicated to be Early to Middle Jurassic (179-158 Myr), and the origin of eudicots is resolved as Late Jurassic to mid Cretaceous (147-131 Myr). Both estimates, despite a conservative calibration point, are older than current fossil-based estimates.

Colonic pseudo-tumor linked to Ogilvie's syndrome.

We present a case of a giant colonic pseudolipoma in a patient with colonic dysmotility due to chronic Ogilvie's syndrome.

Impedance spectroscopy in monitoring the maturation of stem cell-derived retinal pigment epithelium.

The development and differentiation of stem cell-derived impermeable retinal pigment epithelium (RPE) with tight junctions (TJs) is a gradual process that is, at confluence, controlled by cell-to-cell contact. The objective of this study was to evaluate the use of electric impedance spectroscopy (EIS) to follow the maturation and development of barrier function in human embryonic stem cell-derived RPE (hESC-RPE). Barrier function was assessed using EIS, permeability measurements, and microscopic inspection in intact cells and following calcium sequestration with ethylene glycol tetraacetic acid (EGTA). The results showed that the cultures with the most mature morphology had the highest impedance and the lowest permeability values. The EIS of samples of high integrity fitted well to the equivalent model of a single RC circuit, whereas the semicircular shape of the Nyquist plots was distorted for samples of lower integrity. EGTA treatment resulted in lower impedance values and changes in the shapes of plots. Our results show that EIS-as a measure of overall maturity and integrity of the epithelium-is useful when evaluating the maturity of cell cultures. It is highly warranted in future transplantation therapies and in in vitro cell culture models in drug development.

Measuring the fate of plant diversity: towards a foundation for future monitoring and opportunities for urgent action.

Vascular plants are often considered to be among the better known large groups of organisms, but gaps in the available baseline data are extensive, and recent estimates of total known (described) seed plant species range from 200000 to 422000. Of these, global assessments of conservation status using International Union for the Conservation of Nature (IUCN) categories and criteria are available for only approximately 10000 species. In response to recommendations from the Conference of the Parties to the Convention on Biological Diversity to develop biodiversity indicators based on changes in the status of threatened species, and trends in the abundance and distribution of selected species, we examine how existing data, in combination with limited new data collection, can be used to maximum effect. We argue that future work should produce Red List Indices based on a representative subset of plant species so that the limited resources currently available are directed towards redressing taxonomic and geographical biases apparent in existing datasets. Sampling the data held in the world's major herbaria, in combination with Geographical Information Systems techniques, can produce preliminary conservation assessments and help to direct selective survey work using existing field networks to verify distributions and gather population data. Such data can also be used to backcast threats and potential distributions through time. We outline an approach that could result in: (i) preliminary assessments of the conservation status of tens of thousands of species not previously assessed, (ii) significant enhancements in the coverage and representation of plant species on the IUCN Red List, and (iii) repeat and/or retrospective assessments for a significant proportion of these. This would result in more robust Sampled Red List Indices that can be defended as more representative of plant diversity as a whole; and eventually, comprehensive assessments at species level for one or more major families of angiosperms. The combined results would allow scientifically defensible generalizations about the current status of plant diversity by 2010 as well as tentative comments on trends. Together with other efforts already underway, this approach would establish a firmer basis for ongoing monitoring of the status of plant diversity beyond 2010 and a basis for comparison with the trend data available for vertebrates.