Elucidation of intermediate (mobile) and slow (solidlike) protein motions in bovine lens homogenates by carbon-13 NMR spectroscopy

The motional dynamics of lens cytoplasmic proteins present in calf lens homogenates were investigated by two 13C nuclear magnetic resonance (NMR) techniques sensitive to molecular motion to further define the organizational differences between the cortex and nucleus. For the study of intermediate (mobile) protein rotational reorientation motion time scales [rotational correlation time (tau 0) range of 1-500 ns], we employed 13C off-resonance rotating frame spin-lattice relaxation, whereas for the study of slow (solidlike) motions (tau 0 greater than or equal to 10 microseconds) we used the solid-state NMR techniques of dipolar decoupling and cross-polarization. The frequency dependence of the peptide bond carbonyl off-resonance rotating frame spectral intensity ratio of the lens proteins present in native calf nuclear homogenate (42% protein) at 35 degrees C indicates the presence of a polydisperse mobile protein fraction with a tau 0,eff (mean) value of 57 ns. This mean value is consistent with the average value calculated from the known water-soluble nuclear lens protein polydispersity assuming a cytoplasmic viscosity 3 times that of pure water. Lowering the temperature to 1 degree C, a temperature which produces the cold cataract, results in an overall decrease in tau 0,eff to 43 ns, suggesting a selective removal of beta H-, LM-, and possibly gamma s-crystallins from the mobile lens protein population. The presence of solidlike or motionally restricted protein species was established by dipolar decoupling and cross-polarization. The fraction of motionally restricted protein in the nuclear region varied from 0.35 to 0.45 in the temperature range of 35-1 degree C. For native cortical homogenate (25% protein), the off-resonances rotating frame spectral intensity ratio frequency-dependent curves for the protein carbonyl resonance yielded tau 0,eff values of 34 and 80 ns at 35 and 1 degree C, respectively. Both values were reconciled with the known lens cortex soluble protein polydispersity using an assumed cytoplasmic viscosity 1.5 times that of pure water at the same temperature. Comparison of proton dipolar-decoupled and nondecoupled 13C NMR spectra of native cortical homogenate at 20 degrees C indicates the absence of significant contributions from slowly tumbling, motionally restricted species. This interpretation was confirmed by the failure to detect significant lens protein 13C-1H cross-polarization at this temperature. However, at 1 degree C, the fraction of solidlike protein was 0.15. Concentrated cortical homogenates at 20 degrees C (42% protein), by contrast, gave cross-polarization spectra with maximum absolute signal intensities 50-70% of native nuclear homogenates, but with similar magnetization parameters...     

Biological screening of rain forest plot trees from Palawan Island (Philippines)

Study plots totaling 0.2 Ha were established in primary forest in the highlands of central Palawan Island, Philippines. Samples of various anatomical parts [typically leaf + twig (If/tw), stem bark (sb), and root (rt)] were collected from all tree species represented within the plots by individuals having a diameter at breast height > or = 10 cm. In all, 211 distinct samples were obtained from 68 tree species, representing 35 families (not including samples from 4 indeterminate species). Methanol extracts of these samples were tested in in vitro antiplasmodial, brine shrimp toxicity, and cytotoxicity assays. The following samples showed an IC50 < or = 10 microg/mL against either chloroquine-sensitive or chloroquine-resistant clones of Plasmodium falciparum: Acronychia laurifolia (sb), Agathis celebica (lf/tw), Aglaia sp. 1 (sb), Aglaia sp. 2 (lf/tw, rt), Bhesa sp. 1 (rt), Cinnamomum griffithii (lf/tw), Croton leiophyllus (rt), Dysoxylum cauliflorum (rt), Garcinia macgregorii (sb), Lithocarpus sp. 1 (rt, sb), Meliosma pinnata ssp. macrophylla (lf/tw, rt), Myristica guatteriifolia (lf/tw), Ochrosia glomerata (rt, sb), Swintonia foxworthyi (lf/tw), Syzygium sp. 1 (rt), Turpinia pomifera (rt), and Xanthophyllum flavescens (sb). Secondly, those samples which displayed > or = 50% immobilization of brine shrimp at 100 microg/mL were: Acronychia laurifolia (lf/tw/fruit, rt, sb), Agathis celebica (lf/tw, sb), Aglaia sp. 1 (lf/tw), Alphonsea sp. 1 (rt), Ardisia iwahigensis (lf/tw), Arthrophyllum ahernianum (lf/tw, rt, sb), Castanopsis cf. evansii (rt), Cinnamomum griffithii (lf/tw, rt), Croton argyratus (lf/tw), C. leiophyllus (lf/tw, rt), Dysoxylum cauliflorum (fruit, lf/tw, rt), Euonymus javanicus (rt), Glochidion sp. 1 (rt), Polyosma sp. 1 (rt), Symplocos polyandra (rt), Timonius gammillii (sb), and Xanthophyllum flavescens (rt). Lastly, samples which exhibited an IC50 < or = 20 microg/mL against one or more of the cancer cell lines employed (LU1, KB, KB-V1, P-388, LNCaP, or ZR-75-1) include: Acronychia laurifolia (lf/tw/fruit, rt, sb), Aglaia sp. 1 (sb), Aglaia sp. 2 (rt), Alphonsea sp. 1 (rt), Ardisia iwahigensis (lf/tw, rt, sb), Astronia cumingiana (sb), Croton argyratus (lf/tw, rt, sb), C. leiophyllus (lf/tw, rt), Dimorphocalyx murina (lf/tw, rt, sb), Lithocarpus caudatifolius (rt, sb), Litsea cf. sibuyanensis (rt), Syzygium cf. attenuatum (rt, sb), S. confertum (sb), Ternstroemia gitingensis (rt), and Ternstroemia sp. 1 (rt, sb).     

Simulated sea level change alters anatomy, physiology, growth, and reproduction of red mangrove (Rhizophora mangle L.)

Tropical coastal forests – mangroves – will be one of the first ecosystems to be affected by altered sea levels accompanying global climate change. Responses of mangrove forests to changing sea levels depend on reactions of individual plants, yet such responses have not been addressed experimentally. We report data from a long-term greenhouse study that assessed physiological and individual growth responses of the dominant neotropical mangrove, Rhizophora mangle, to levels of inundation expected to occur in the Caribbean within 50–100 years. In this study, we grew potted plants in tanks with simulated semidiurnal (twice daily) high tides that approximated current conditions (MW plants), a 16-cm increase in sea level (LW plants), and a 16-cm decrease in sea level (HW plants). The experiment lasted 2½ years, beginning with mangrove seedlings and terminating after plants began to reproduce. Environmental (air temperature, relative humidity, photosynthetically active radiation) and edaphic conditions (pH, redox, soil sulfide) approximated field conditions in Belize, the source locale for the seedlings. HW plants were shorter and narrower, and produced fewer branches and leaves, responses correlated with the development of acid-sulfide soils in their pots. LW plants initially grew more rapidly than MW plants. However, the growth of LW plants slowed dramatically once they reached the sapling stage, and by the end of the experiment, MW plants were 10–20% larger in all measured growth parameters. Plants did not exhibit differences in allometric growth as a function of inundation. Anatomical characteristics of leaves did not differ among treatments. Both foliar C:N and root porosity decreased from LW through MW to HW. Relative to LW and HW plants, MW plants had 1–7% fewer stomata/mm², 6–21% greater maximum photosynthetic rates, 3–23% greater absolute relative growth rates (RGRs), and a 30% higher RGR for a given increase in net assimilation rate. Reduced growth of R. mangle under realistic conditions approximating future inundation depths likely will temper projected increased growth of this species under concomitant increases in the atmospheric concentration of CO₂.     

Dose-Dependent Regulation of Alternative Splicing by MBNL Proteins Reveals Biomarkers for Myotonic Dystrophy

Alternative splicing is a regulated process that results in expression ofspecific mRNA and protein isoforms. Alternative splicing factors determine therelative abundance of each isoform. Here we focus on MBNL1, a splicing factormisregulated in the disease myotonic dystrophy. By altering the concentration ofMBNL1 in cells across a broad dynamic range, we show that different splicingevents require different amounts of MBNL1 for half-maximal response, and respondmore or less steeply to MBNL1. Motifs around MBNL1 exon 5 were studied to assesshow cis-elements mediate the MBNL1 dose-dependent splicingresponse. A framework was developed to estimate MBNL concentration usingsplicing responses alone, validated in the cell-based model, and applied tomyotonic dystrophy patient muscle. Using this framework, we evaluated theability of individual and combinations of splicing events to predict functionalMBNL concentration in human biopsies, as well as their performance as biomarkersto assay mild, moderate, and severe cases of DM.     

Recent shoreline changes in the Volta River delta,West Africa: the roles of natural processes and human impacts§

The Volta River delta developed as an asymmetric lobe in a tectonic offset on the coast of Ghana. The delta comprises a large curvilinear spit that widens in its central portion due to the adjunction of successive sandy beach ridges. The appearance of a distinct spit, in lieu of a continuous barrier from the present mouth of the Volta River to the Bight of Benin coast, may be an outgrowth of a natural change in the location of the mouth of the Volta. The spit marks a segmentation of the unique sand drift cell that hitherto prevailed on this bight coast. Spit growth has been accompanied by a wave of erosion over the last century of the immediate downdrift sector of the bight coast, endangering the town of Keta. Erosion since the 1960s may have been aggravated by the construction of the Akosombo hydropower dam. The tip of the spit has recently welded to the shoreline, thus assuring resumption of sand supply from the Volta towards the rest of this formerly sand-starved sector of the bight coast. Blocking of sediment by the Akosombo Dam is, in due course, likely to become the overarching factor in delta shoreline stability.     

Inter- and intra-generic differences in growth,reproduction, and fitness of nine herbaceous annual species grown in elevated CO2 environments

In assessing the capacity of plants to adapt to rapidly changing global climate, we must elucidate the impacts of elevated carbon dioxide on reproduction, fitness and evolution. We investigated how elevated CO₂ influenced reproduction and growth of plants exhibiting a range of floral morphologies, the implications of shifts in allocation for fitness in these species, and whether related taxa would show similar patterns of response. Three herbaceous, annual species each of the genera Polygonum, Ipomoea, and Cassia were grown under 350 or 700 ppm CO₂. Vegetative growth and reproductive output were measured non-destructively throughout the full life span, and vegetative biomass was quantified for a subsample of plants in a harvest at first flowering. Viability and germination studies of seed progeny were conducted to characterize fitness precisely. Early vegetative growth was often enhanced in high-CO₂ grown plants of Polygonum and Cassia (but not Ipomoea). However, early vegetative growth was not a strong predictor of subsequent reproduction. Phenology and production of floral buds, flowers, unripe and abscised fruits differed between CO₂ treatments, and genera differed in their reproductive and fitness responses to elevated CO₂. Polygonum and Cassia species showed accelerated, enhanced reproduction, while Ipomoea species generally declined in reproductive output in elevated CO₂. Seed quality and fitness (in terms of viability and percentage germination) were not always directly correlated with quantity produced, indicating that output alone may not reliably indicate fitness or evolutionary potential. Species within genera typically responded more consistently to CO₂ than unrelated species. Cluster analyses were performed separately on suites of vegetative and reproductive characters. Some species assorted within genera when these reproductive responses were considered, but vegetative responses did not reflect taxonomic affinity in these plants. Congeners may respond similarly in terms of reproductive output under global change, but fitness and prognoses of population persistence and evolutionary performance can be inferred only rarely from examination of vegetative characters alone.     

Navigating north: how body mass and winds shape avian flight behaviours across a North American migratory flyway

The migratory patterns of birds have been the focus of ecologists for millennia. What behavioural traits underlie these remarkably consistent movements? Addressing this question is central to advancing our understanding of migratory flight strategies and requires the integration of information across levels of biological organisation, e.g. species to communities. Here, we combine species‐specific observations from the eBird citizen‐science database with observations aggregated from weather surveillance radars during spring migration in central North America. Our results confirm a core prediction of migration theory at an unprecedented national scale: body mass predicts variation in flight strategies across latitudes, with larger‐bodied species flying faster and compensating more for wind drift. We also find evidence that migrants travelling northward earlier in the spring increasingly compensate for wind drift at higher latitudes. This integration of information across biological scales provides new insight into patterns and determinants of broad‐scale flight strategies of migratory birds.     

Seasonal associations with urban light pollution for nocturnally migrating bird populations

The spatial extent and intensity of artificial light at night (ALAN) has increased worldwide through the growth of urban environments. There is evidence that nocturnally migrating birds are attracted to ALAN, and there is evidence that nocturnally migrating bird populations are more likely to occur in urban areas during migration, especially in the autumn. Here, we test if urban sources of ALAN are responsible, at least in part, for these observed urban associations. We use weekly estimates of diurnal occurrence and relative abundance for 40 nocturnally migrating bird species that breed in forested environments in North America to assess how associations with distance to urban areas and ALAN are defined across the annual cycle. Migratory bird populations presented stronger than expected associations with shorter distances to urban areas during migration, and stronger than expected association with higher levels of ALAN outside and especially within urban areas during migration. These patterns were more pronounced during autumn migration, especially within urban areas. Outside of the two migration periods, migratory bird populations presented stronger than expected associations with longer distances to urban areas, especially during the nonbreeding season, and weaker than expected associations with the highest levels of ALAN outside and especially within urban areas. These findings suggest that ALAN is associated with higher levels of diurnal abundance along the boundaries and within the interior of urban areas during migration, especially in the autumn when juveniles are undertaking their first migration journey. These findings support the conclusion that urban sources of ALAN can broadly effect migratory behavior, emphasizing the need to better understand the implications of ALAN for migratory bird populations.