Characterization of the Variation Potential in Sunflower

A major candidate for intercellular signaling in higher plants is the stimulus-induced systemic change in membrane potential known as variation potential (VP). We investigated the mechanism of occurrence and long-distance propagation of VP in sunflower (Helianthus annuus L.) plants. Here we present evidence of the relationship among injury-induced changes in xylem tension, turgor pressure, and electrical potential. Although locally applied wounding did trigger a change in membrane potential, it evoked even faster changes in tissue deformation, apparently resulting from pressure surges rapidly transmitted through the xylem and experienced throughout the plant. Externally applied pressure mimicked flame wounding by triggering an electrical response resembling VP. Our findings suggest that VP in sunflower is not a propagating change in electrical potential and not the consequence of chemicals transmitted via the xylem, affecting ligand-modulated ion channels. Instead, VP appears to result from the surge in pressure in the xylem causing a change in activity of mechanosensitive, stretch-responsive ion channels or pumps in adjacent, living cells. The ensuing ion flux evokes local plasma membrane depolarization, which is monitored extracellularly as VP.     

The Log-Linear Relationship between Sexual Isolation and Sequence Divergence in Bacillus Transformation Is Robust

The relationship between sexual isolation and sequence divergence in Bacillus transformation was previously shown to be log linear. In the present study, we have shown that this relationship is robust with respect to naturally occurring genetic variation among recipient strains of Bacillus subtilis and B. mojavensis. Naturally occurring restriction endonuclease activity was shown not to affect this relationship. Also, seven out of eight recombination mutants tested for their sensitivity to sequence divergence have shown the same relationship between sequence divergence and sexual isolation; a mutant for recH was more sensitive to sequence divergence, suggesting that the product of this gene may be involved in resolution of mismatches in heterogamic transformation. We have also shown that the relationship between sexual isolation and sequence divergence is robust with respect to variation in the conditions of transformation, including variation in the length of donor DNA, the concentration of donor DNA, and intracellular competition between donor-derived and recipient-derived DNA. The robustness of the relationship between sexual isolation and sequence divergence among naturally occurring strains and across transformation conditions allows us to predict the eventual outcome of sequence divergence among B. subtilis and its closest relatives.     

Transcontinental dispersal,ecological opportunity and origins of an adaptive radiation in the Neotropical catfish genus Hypostomus (Siluriformes: Loricariidae)

Ecological opportunity is often proposed as a driver of accelerated diversification, but evidence has been largely derived from either contemporary island radiations or the fossil record. Here, we investigate the potential influence of ecological opportunity on a transcontinental radiation of South American freshwater fishes. We generate a species‐dense, time‐calibrated molecular phylogeny for the suckermouth armored catfish subfamily Hypostominae, with a focus on the species‐rich and geographically widespread genus Hypostomus. We use the resulting chronogram to estimate ancestral geographical ranges, infer historical rates of cladogenesis and diversification in habitat and body size and shape, and test the hypothesis that invasions of previously unoccupied river drainages accelerated evolution and contributed to adaptive radiation. Both the subfamily Hypostominae and the included genus Hypostomus originated in the Amazon/Orinoco ecoregion. Hypostomus subsequently dispersed throughout tropical South America east of the Andes Mountains. Consequent to invasion of the peripheral, low‐diversity Paraná River basin in southeastern Brazil approximately 12.5 Mya, Paraná lineages of Hypostomus, experienced increased rates of cladogenesis and ecological and morphological diversification. Contemporary lineages of Paraná Hypostomus are less species rich but more phenotypically diverse than their congeners elsewhere. Accelerated speciation and morphological diversification rates within Paraná basin Hypostomus are consistent with adaptive radiation. The geographical remoteness of the Paraná River basin, its recent history of marine incursion, and its continuing exclusion of many species that are widespread in other tropical South American rivers suggest that ecological opportunity played an important role in facilitating the observed accelerations in diversification.     

Hypostomus sertanejo (Siluriformes: Loricariidae), new armoured catfish species from north‐eastern Brazil

A re‐evaluation of the armoured catfish species of Hypostomus in the Rio Jaguaribe, north‐eastern Brazil, was prompted by the discovery of specimens with pale spots on a dark background collected from that basin c. 1936 and deposited at the Academy of Natural Sciences of Philadelphia. Recent field collections in the Rio Jarguaribe basin confirmed the presence of the pale‐spotted specimens and its distinctiveness as a new species. Hypostomus sertanejo n. sp. is diagnosed from other species of Hypostomus by having fins and dermal‐plated regions of head and body with pale spots or vermiculations on darker background, teeth slender, asymmetrically bicuspid and numerous (34–75) on dentary and premaxilla, depressed dorsal‐fin spine not reaching adipose spine, unbranched pectoral‐fin spine longer than unbranched pelvic‐fin ray, seven branched dorsal‐fin rays and one (rarely two) predorsal plate(s) bordering supraoccipital. Ancistrus salgadae Fowler 1941 is hypothesized to be a junior synonym of Hypostomus carvalhoi (Miranda‐Ribeiro, 1937), a dark‐spotted Hypostomus described from the Rio Granjeiro, a tributary to the upper Rio Salgado.     

Evidence-based policymaking when evidence is incomplete: The case of HIV programme integration

Jan Hontelez and co-authors discuss the use of different types of evidence to inform HIV program integration.

Summary points

• Sustainable Development Goal 3 aims to “ensure healthy lives and promote well-being for all at all ages” and has set a target of achieving global universal health coverage, representing a major policy shift away from mostly disease-specific “vertical programmes”.
• While health service integration can be a promising strategy to improve healthcare coverage, health outcomes, and efficiency, the exact impact of integration in different settings is hard to predict, and policy makers need to choose from a large variety of integration strategies and opportunities with varying levels of scientific evidence.
• Using the case of health service integration for HIV in low- and middle-income countries, we outline implementation strategies for integration opportunities with lacking or scarce high-level causal evidence, based on existing frameworks and methodologies from within and beyond healthcare and implementation science.
• Proper use of scientific evidence in other contexts requires adequate and systematic assessments of the transportability of an intervention. Several methods exist that allow for judging transferability and comprehensively identifying key context-specific indicators across studies that can affect the reported impact of interventions.
• When (transferable) evidence is absent, we propose that by drawing on well-established design and implementation methodologies—underpinned by ongoing learning and iterative improvement of local service delivery strategies—countries could substantially improve decision-making even in the absence of scientific evidence.
• Reaching the goal of making the HIV response an integral part of a larger, universal, people-centred health system that meets the needs and requirements of citizens can be facilitated by applying lessons learned from implementation science and novel design methodologies.

     

Evolutionary and biogeographic history of the subfamily Neoplecostominae (Siluriformes: Loricariidae)

Freshwater fish evolution has been shaped by changes in the earth's surface involving changes in the courses of rivers and fluctuations in sea level. The main objective of this study is to improve our knowledge of the evolution of loricariids, a numerous and adaptive group of freshwater catfish species, and the role of geological changes in their evolution. We use a number of different phylogenetic methods to test the relationships among 52 representative taxa within the Neoplecostominae using 4676 bps of mitochondrial and nuclear DNA. Our analysis revealed that the subfamily Neoplecostominae is monophyletic, including Pseudotocinclus, with three lineages recognized. The first lineage is composed of part of Pareiorhina rudolphi, P. cf. rudolphi, and Pseudotocinclus; the second is composed of Isbrueckerichthys, Pareiorhaphis, Kronichthys, and the species Neoplecostomus ribeirensis; and the third is composed of Pareiorhina carrancas, P. cf. carrancas, Pareiorhina sp. 1, a new genus, and all the species of the genus Neoplecostomus, except N. ribeirensis. The relaxed molecular clock calibration provides a temporal framework for the evolution of the group, which we use for a likelihood‐based historical biogeographic analysis to test relevant hypotheses on the formation of southeast Brazil. We hypothesize that headwater capture events and marine regressions have shaped the patterns of distribution within the subfamily Neoplecostominae throughout the distinct basins of southeast Brazil.     

Indications for and results of treatment of carotid artery stenosis

The authors discuss own experience with the treatment of carotid artery stenosis. Diagnostic principles and indications to surgical treatment, technique of block anesthesia, an operation and obtained results are also discussed. Internal carotid artery stenosis was treated surgically in 90 patients within 1985-1988. Block anesthesia enabling intraoperational control of patients' consciousness was used in 72 cases. Satisfactory early results were noted in 92.9% of patients. Two patients died after surgery whereas 5 patients suffered from neurological complications. Favourable late results (follow-up period ranged from 6 to 48 months) were noted in 64 out of 70 patients which reported to clinical examination (91.4%).     

Pyrimidine arabinofuranosyl nucleosides with 5-substituted long, branched and unsaturated chains: synthesis and antiherpes properties

Several procedures have been applied to the preparation of 5-alkyl analogues of araU and araC via condensation of the appropriate 2,4-bis-O-(trimethylsilyl)-5-alkylpyrimidine with 2,3,5-tri-O-benzyl-alpha-D-arabinofuranosyl chloride. The resulting O'-benzylated nucleosides were deblocked with the aid of BF3 . Et2O in C2H5SH. The araC analogues were also prepared by conversions of the corresponding 5-alkyl-araU derivatives. The chloromercuri derivatives of araU and araC, were reacted with allyl chloride in the presence of Li2PdCl4. The resulting 5-allyl derivatives were catalytically reduced to the corresponding 5-propyl analogues. Catalysed condensation of 2,4-bis-O-(trimethylsilyl)-5-vinyluracil with 2,3,5-tri-O-benzyl-alpha-D-arabinosyl chloride, as well as with 1-O-acetyl-2,3,5-tri-O-benzoylarabinofuranose, was carried out under a variety of different conditions. Deblocking of the benzylated nucleosides with various reagents led invariably to addition to the vinyl substituent. In the case of benzoylated nucleosides, deblocking yielded largely the alpha-anomers. The antiherpes activities of the 5-alkyl compounds have been evaluated, as well as the susceptibility of the araC analogues to enzymatic deamination.     

Thirty-Year Repeat Measures of Mangrove Above- and Below-Ground Biomass Reveals Unexpectedly High Carbon Sequestration

Ecosystems - Mangrove ecosystems store large quantities of organic carbon for long periods of time. This study explores organic carbon stock change through the first comparative study of...