Reproductive ecology of mangrove trees Ceriops decandra (Griff.) Ding Hou and Ceriops tagal (Perr.) C.B. Robinson (Rhizophoraceae)

Ceriops decandra and C. tagal are evergreen trees in the inner mangrove forests in Andhra Pradesh, India. Ceriops decandra is primarily a landward species whereas C. tagal is a seaward and highly salt tolerant species. Ceriops decandra produces flowers and fruits continuously throughout the year while C. tagal produces flowers and fruits during winter only. Both species have amixed mating system with cross-pollination as the principal system and self-pollination, which is primarily vector-dependent. Ceriops decandra flowers have a simple pollination mechanism that is adapted for pollination by daytime foragers, Nomia bees and Odynerus wasps. In contrast, C. tagal flowers have an elaborate and explosive pollination mechanism. Flies and honey bees trip the flowers and contribute to explosive pollen release and subsequent self- and cross-pollination.Wind is also effective in tripping the pollination mechanism but it largely contributes to self-pollination. Bud abortion occurs only in C. decandra. Flower and fruit abortion occurs in both the species of Ceriops. Abortion at different stages of the reproductive unit has been considered to be a strategy by the plants to adjust the available maternal resources to the growing fruits and propagules. The paper provides the basis for further study for the conservation and management of Ceriops species in the study areas

Microwave-assisted synthesis of highly crystalline, multifunctional iron oxide nanocomposites for imaging applications

We report a reproducible single-step, microwave-assisted approach for the preparation of multifunctional magnetic nanocomposites comprising superparamagnetic iron oxide (Fe3O4) cores, a polyelectrolyte stabilizer and an organic dye with no requirement for post-processing. The stabilisers poly(sodium 4-styrenesulfonate) (PSSS) and sodium polyphosphate (SPP) have been thoroughly investigated and from analysis using electron microscopy, dynamic light scattering measurements, magnetic hysteresis and magnetic resonance (MR) imaging, we show that the higher degree of Fe3O4 nanoparticle crystallinity achieved with the PSSS stabiliser leads to enhanced magnetic behaviour and thus better contrast agent relaxivity compared to the less crystalline, poorly defined particles obtained when SPP is employed as a stabiliser. We also demonstrate the potential for obtaining a multifunctional magnetic-fluorescent nanocomposite using our microwave-assisted synthesis. In this manner, we demonstrate the intimate link between synthetic methodology (microwave heating with a polyelectrolyte stabilizer) and the resulting properties (particle size, shape, and magnetism) and how this underpins the functionality of the resulting nanocomposites as agents for biomedical imaging

A complete 3D numerical study of the effects of pseudoscalar-photon mixing on quasar polarizations

We present the results of three-dimensional simulations of quasar polarizations in the presence of pseudoscalar-photon mixing in the intergalactic medium. The intergalactic magnetic field is assumed to be uncorrelated in wave vector space but correlated in real space. Such a field may be obtained if its origin is primordial. Furthermore we assume that the quasars, located at cosmological distances, have negligible initial polarization. In the presence of pseudoscalar-photon mixing we show, through a direct comparison with observations, that this may explain the observed large scale alignments in quasar polarizations within the framework of big bang cosmology. We find that the simulation results give a reasonably good fit to the observed data.Comment: 15 pages, 8 figures, significant changes, to appear in EPJ

PEG–Polypeptide Block Copolymers as pH-Responsive Endosome-Solubilizing Drug Nanocarriers

Herein we report the potential of click chemistry-modified polypeptide-based block copolymers for the facile fabrication of pH-sensitive nanoscale drug delivery systems. PEG–polypeptide copolymers with pendant amine chains were synthesized by combining N-carboxyanhydride-based ring-opening polymerization with post-functionalization using azide–alkyne cycloaddition. The synthesized block copolymers contain a polypeptide block with amine-functional side groups and were found to self-assemble into stable polymersomes and disassemble in a pH-responsive manner under a range of biologically relevant conditions. The self-assembly of these block copolymers yields nanometer-scale vesicular structures that are able to encapsulate hydrophilic cytotoxic agents like doxorubicin at physiological pH but that fall apart spontaneously at endosomal pH levels after cellular uptake. When drug-encapsulated copolymer assemblies were delivered systemically, significant levels of tumor accumulation were achieved, with efficacy against the triple-negative breast cancer cell line, MDA-MB-468, and suppression of tumor growth in an in vivo mouse model.Novartis Institutes of Biomedical ResearchNational Institutes of Health (U.S.) (Centers for Cancer Nanotechnology Excellence Grant P30 CA14051)National Institutes of Health (U.S.) (Centers for Cancer Nanotechnology Excellence Grant 5 U54 CA151884-02)National Science Foundation (U.S.). Graduate Research FellowshipNatural Sciences and Engineering Research Council of Canada (Postdoctoral Fellowship

Repression of Flowering by the miR172 Target SMZ

The flowering repressors SMZ and FLM, members of the AP-2 and MADS domain transcription factor families, unexpectedly work together to regulate flowering time via their effects on expression of the FT gene

Expression Patterns of Genes Involved in Sugar Metabolism and Accumulation during Apple Fruit Development

Both sorbitol and sucrose are imported into apple fruit from leaves. The metabolism of sorbitol and sucrose fuels fruit growth and development, and accumulation of sugars in fruit is central to the edible quality of apple. However, our understanding of the mechanisms controlling sugar metabolism and accumulation in apple remains quite limited. We identified members of various gene families encoding key enzymes or transporters involved in sugar metabolism and accumulation in apple fruit using homology searches and comparison of their expression patterns in different tissues, and analyzed the relationship of their transcripts with enzyme activities and sugar accumulation during fruit development. At the early stage of fruit development, the transcript levels of sorbitol dehydrogenase, cell wall invertase, neutral invertase, sucrose synthase, fructokinase and hexokinase are high, and the resulting high enzyme activities are responsible for the rapid utilization of the imported sorbitol and sucrose for fruit growth, with low levels of sugar accumulation. As the fruit continues to grow due to cell expansion, the transcript levels and activities of these enzymes are down-regulated, with concomitant accumulation of fructose and elevated transcript levels of tonoplast monosaccharide transporters (TMTs), MdTMT1 and MdTMT2; the excess carbon is converted into starch. At the late stage of fruit development, sucrose accumulation is enhanced, consistent with the elevated expression of sucrose-phosphate synthase (SPS), MdSPS5 and MdSPS6, and an increase in its total activity. Our data indicate that sugar metabolism and accumulation in apple fruit is developmentally regulated. This represents a comprehensive analysis of the genes involved in sugar metabolism and accumulation in apple, which will serve as a platform for further studies on the functions of these genes and subsequent manipulation of sugar metabolism and fruit quality traits related to carbohydrates