The shifting influence of drought and heat stress for crops in northeast Australia

Characterization of drought environment types (ETs) has proven useful for breeding crops for drought‐prone regions. Here, we consider how changes in climate and atmospheric carbon dioxide (CO₂) concentrations will affect drought ET frequencies in sorghum and wheat systems of northeast Australia. We also modify APSIM (the Agricultural Production Systems Simulator) to incorporate extreme heat effects on grain number and weight, and then evaluate changes in the occurrence of heat‐induced yield losses of more than 10%, as well as the co‐occurrence of drought and heat. More than six million simulations spanning representative locations, soil types, management systems, and 33 climate projections led to three key findings. First, the projected frequency of drought decreased slightly for most climate projections for both sorghum and wheat, but for different reasons. In sorghum, warming exacerbated drought stresses by raising the atmospheric vapor pressure deficit and reducing transpiration efficiency (TE), but an increase in TE due to elevated CO₂ more than offset these effects. In wheat, warming reduced drought stress during spring by hastening development through winter and reducing exposure to terminal drought. Elevated CO₂ increased TE but also raised radiation‐use efficiency and overall growth rates and water use, thereby offsetting much of the drought reduction from warming. Second, adding explicit effects of heat on grain number and grain size often switched projected yield impacts from positive to negative. Finally, although average yield losses associated with drought will remain generally higher than that for heat stress for the next half century, the relative importance of heat is steadily growing. This trend, as well as the likely high degree of genetic variability in heat tolerance, suggests that more emphasis on heat tolerance is warranted in breeding programs. At the same time, work on drought tolerance should continue with an emphasis on drought that co‐occurs with extreme heat.     

Improved tumor targeting of polymer-based nanovesicles using polymer-lipid blends

Block copolymer-based vesicles have recently garnered a great deal of interest as nanoplatforms for drug delivery and molecular imaging applications due to their unique structural properties. These nanovesicles have been shown to direct their cargo to disease sites either through enhanced permeability and retention or even more efficiently via active targeting. Here, we show that the efficacy of nanovesicle targeting can be significantly improved when prepared from polymer-lipid blends compared with block copolymer alone. Polymer-lipid hybrid nanovesicles were produced from the aqueous coassembly of the diblock copolymer, poly(ethylene oxide)-block-polybutadiene (PEO-PBD), and the phospholipid, hydrogenated soy phosphatidylcholine (HSPC). The PEG-based vesicles, 117 nm in diameter, were functionalized with either folic acid or anti-HER2/neu affibodies as targeting ligands to confer specificity for cancer cells. Our results revealed that nanovesicles prepared from polymer-lipid blends led to significant improvement in cell binding compared to nanovesicles prepared from block copolymer alone in both in vitro cell studies and murine tumor models. Therefore, it is envisioned that nanovesicles composed of polymer-lipid blends may constitute a preferred embodiment for targeted drug delivery and molecular imaging applications.     

Neurofeedback for Insomnia: A Pilot Study of <Emphasis Type="Italic">Z</Emphasis>-Score SMR and Individualized Protocols

Insomnia is an epidemic in the US. Neurofeedback (NFB) is a little used, psychophysiological treatment with demonstrated usefulness for treating insomnia. Our objective was to assess whether two distinct Z-Score NFB protocols, a modified sensorimotor (SMR) protocol and a sequential, quantitative EEG (sQEEG)-guided, individually designed (IND) protocol, would alleviate sleep and associated daytime dysfunctions of participants with insomnia. Both protocols used instantaneous Z scores to determine reward condition administered when awake. Twelve adults with insomnia, free of other mental and uncontrolled physical illnesses, were randomly assigned to the SMR or IND group. Eight completed this randomized, parallel group, single-blind study. Both groups received fifteen 20-min sessions of Z-Score NFB. Pre-post assessments included sQEEG, mental health, quality of life, and insomnia status. ANOVA yielded significant post-treatment improvement for the combined group on all primary insomnia scores: Insomnia Severity Index (ISI p < .005), Pittsburgh Sleep Quality Inventory (PSQI p < .0001), PSQI Sleep Efficiency (p < .007), and Quality of Life Inventory (p < .02). Binomial tests of baseline EEGs indicated a significant proportion of excessively high levels of Delta and Beta power (p < .001) which were lowered post-treatment (paired z-tests p < .001). Baseline EEGs showed excessive sleepiness and hyperarousal, which improved post-treatment. Both Z-Score NFB groups improved in sleep and daytime functioning. Post-treatment, all participants were normal sleepers. Because there were no significant differences in the findings between the two groups, our future large scale studies will utilize the less burdensome to administer Z-Score SMR protocol.     

Myosin-Va transports the endoplasmic reticulum into the dendritic spines of Purkinje neurons

Extension of the endoplasmic reticulum (ER) into dendritic spines of Purkinje neurons is required for cerebellar synaptic plasticity and is disrupted in animals with null mutations in Myo5a, the gene encoding myosin-Va. We show here that myosin-Va acts as a point-to-point organelle transporter to pull ER as cargo into Purkinje neuron spines. Specifically, myosin-Va accumulates at the ER tip as the organelle moves into spines, and hydrolysis of ATP by myosin-Va is required for spine ER targeting. Moreover, myosin-Va is responsible for almost all of the spine ER insertion events. Finally, attenuation of the ability of myosin-Va to move along actin filaments reduces the maximum velocity of ER movement into spines, providing direct evidence that myosin-Va drives ER motility. Thus, we have established that an actin-based motor moves ER within animal cells, and have uncovered the mechanism for ER localization to Purkinje neuron spines, a prerequisite for synaptic plasticity.     

CAF01 potentiates immune responses and efficacy of an inactivated influenza vaccine in ferrets

Trivalent inactivated vaccines (TIV) against influenza are given to 350 million people every year. Most of these are non-adjuvanted vaccines whose immunogenicity and protective efficacy are considered suboptimal. Commercially available non-adjuvanted TIV are known to elicit mainly a humoral immune response, whereas the induction of cell-mediated immune responses is negligible. Recently, a cationic liposomal adjuvant (dimethyldioctadecylammonium/trehalose 6,6'-dibehenate, CAF01) was developed. CAF01 has proven to enhance both humoral and cell-mediated immune responses to a number of different experimental vaccine candidates. In this study, we compared the immune responses in ferrets to a commercially available TIV with the responses to the same vaccine mixed with the CAF01 adjuvant. Two recently circulating H1N1 viruses were used as challenge to test the vaccine efficacy. CAF01 improved the immunogenicity of the vaccine, with increased influenza-specific IgA and IgG levels. Additionally, CAF01 promoted cellular-mediated immunity as indicated by interferon-gamma expressing lymphocytes, measured by flow cytometry. CAF01 also enhanced the protection conferred by the vaccine by reducing the viral load measured in nasal washes by RT-PCR. Finally, CAF01 allowed for dose-reduction and led to higher levels of protection compared to TIV adjuvanted with a squalene emulsion. The data obtained in this human-relevant challenge model supports the potential of CAF01 in future influenza vaccines.     

Regulated expression of endothelial lipase by porcine brain capillary endothelial cells constituting the blood-brain barrier

Normal neurological function depends on a constant supply of polyunsaturated fatty acids to the brain. A considerable proportion of essential fatty acids originates from lipoprotein-associated lipids that undergo uptake and/or catabolism at the blood-brain barrier (BBB). This study aimed at identifying expression and regulation of endothelial lipase (EL) in brain capillary endothelial cells (BCEC), major constituents of the BBB. Our results revealed that BCEC are capable of EL synthesis and secretion. Overexpression of EL resulted in enhanced hydrolysis of extracellular high-density lipoprotein (HDL)-associated sn-2-labeled [(14)C]20 : 4 phosphatidylcholine. [(14)C]20 : 4 was recovered in cellular lipids, indicating re-uptake and intracellular re-esterification. To investigate local regulation of EL in the cerebrovasculature, BCEC were cultured in the presence of peroxisome-proliferator activated receptor (PPAR)- and liver X receptor (LXR)-agonists, known to regulate HDL levels. These experiments revealed that 24(S)OH-cholesterol (a LXR agonist), bezafibrate (a PPARalpha agonist), or pioglitazone (a PPARgamma agonist) resulted in down-regulation of EL mRNA and protein levels. Our findings implicate that EL could generate fatty acids at the BBB for transport to deeper regions of the brain as building blocks for membrane phospholipids. In addition PPAR and LXR agonists appear to contribute to HDL homeostasis at the BBB by regulating EL expression.     

Continuing education alternatives for professional development

Continuing education is an important, and often required, activity for those involved in laboratory animal science to remain abreast of developments in the field. The authors contrast many of the different professional development opportunities, from on-campus courses, to online programs, to correspondence courses, helping readers to determine which form best meets their individual needs.     

Nano-to-micro scale dynamics of P-selectin detachment from leukocyte interfaces. III. Numerical simulation of tethering under flow

Transient capture of cells or model microspheres from flow over substrates sparsely coated with adhesive ligands has provided significant insight into the unbinding kinetics of leukocyte:endothelium adhesion complexes under external force. Whenever a cell is stopped by a point attachment, the full hydrodynamic load is applied to the adhesion site within an exceptionally short time-less than the reciprocal of the hydrodynamic shear rate (e.g., typically <0.01 s). The decay in numbers of cells or beads that remain attached to a surface has been used as a measure of the kinetics of molecular bond dissociation under constant force, revealing a modest increase in detachment rate at growing applied shear stresses. On the other hand, when detached under steady ramps of force with mechanical probes (e.g., the atomic force microscope and biomembrane force probe), P-selectin:PSGL-1 adhesion bonds break at rates that increase enormously under rising force, yielding 100-fold faster off rates at force levels comparable to high shear. The comparatively weak effect of force on tether survival in flow chamber experiments could be explained by a possible partition of the load amongst several bonds. However, a comprehensive understanding of the difference in kinetic behavior requires us to also inspect other factors affecting the dynamics of attachment-force buildup, such as the interfacial compliance of all linkages supporting the adhesion complex. Here, combining the mechanical properties of the leukocyte interface measured in probe tests with single-bond kinetics and the kinetics of cytoskeletal dissociation, we show that for the leukocyte adhesion complex P-selectin:PSGL-1, a detailed adhesive dynamics simulation accurately reproduces the tethering behavior of cells observed in flow chambers. Surprisingly, a mixture of 10% single bonds and 90% dimeric bonds is sufficient to fully match the data of the P-selectin:PSGL-1 experiments, with the calculated decay in fraction of attached cells still appearing exponential.     

Effect of microvillus deformability on leukocyte adhesion explored using adhesive dynamics simulations

Leukocyte rolling on the endothelium via selectin molecules is an important step in the adhesion cascade, which allows leukocytes in the bloodstream to reach sites of infection. We improve upon Adhesive Dynamics simulations by incorporating deformable microvilli on which adhesion molecules are clustered. As determined in micropipette experiments, microvilli deform like an elastic spring at small forces and a combination of yield and viscous dissipation at high forces. First, we create a modified version of the state diagram for adhesion which includes microvillus deformation, and find four adhesion states-firmly bound; landing; rolling; and no-adhesion. Then, we simulate the effects of receptor clustering on the tips of microvilli, number of adhesion molecules on the cell, and the spring constant of the bonds, within the context of deformable microvilli. We also explore how the microvillus rheology itself controls the dynamics of adhesion. A minimum in rolling velocity occurs at an intermediate value of the microvillus membrane viscosity, remarkably close to the reported physiological value, suggesting that the mechanics of microvilli have evolved ideally for rolling and adhesion of leukocytes. We find that a larger degree of association between the membrane and cytoskeleton leads to slower rolling, and stiffer microvilli result in faster rolling. Decreasing the overall deformability of the microvilli greatly reduces a simulated cell's ability to roll. A comparison to experimental results of in vitro cell rolling agrees with the simulation at low shear rates. Furthermore, simulated rolling trajectories of cells with deformable microvilli display periods of rolling interdispersed with pauses, consistent with that seen in experiments where microvilli were observed to stretch.     

Balinese Y-chromosome perspective on the peopling of Indonesia: genetic contributions from pre-neolithic hunter-gatherers, Austronesian farmers, and Indian traders

The island of Bali lies near the center of the southern chain of islands in the Indonesian archipelago, which served as a stepping-stone for early migrations of hunter-gatherers to Melanesia and Australia and for more recent migrations of Austronesian farmers from mainland Southeast Asia to the Pacific. Bali is the only Indonesian island with a population that currently practices the Hindu religion and preserves various other Indian cultural, linguistic, and artistic traditions (Lansing 1983). Here, we examine genetic variation on the Y chromosomes of 551 Balinese men to investigate the relative contributions of Austronesian farmers and pre-Neolithic hunter-gatherers to the contemporary Balinese paternal gene pool and to test the hypothesis of recent paternal gene flow from the Indian subcontinent. Seventy-one Y-chromosome binary polymorphisms (single nucleotide polymorphisms, SNPs) and 10 Y-chromosome-linked short tandem repeats (STRs) were genotyped on a sample of 1,989 Y chromosomes from 20 populations representing Indonesia (including Bali), southern China, Southeast Asia, South Asia, the Near East, and Oceania. SNP genotyping revealed 22 Balinese lineages, 3 of which (O-M95, O-M119, and O-M122) account for nearly 83.7% of Balinese Y chromosomes. Phylogeographic analyses suggest that all three major Y-chromosome haplogroups migrated to Bali with the arrival of Austronesian speakers; however, STR diversity patterns associated with these haplogroups are complex and may be explained by multiple waves of Austronesian expansion to Indonesia by different routes. Approximately 2.2% of contemporary Balinese Y chromosomes (i.e., K-M9*, K-M230, and M lineages) may represent the pre-Neolithic component of the Indonesian paternal gene pool. In contrast, eight other haplogroups (e.g., within H, J, L, and R), making up approximately 12% of the Balinese paternal gene pool, appear to have migrated to Bali from India. These results indicate that the Austronesian expansion had a profound effect on the composition of the Balinese paternal gene pool and that cultural transmission from India to Bali was accompanied by substantial levels of gene flow.