Effects of DNA Damage and Oxidative Stress in Human Bronchial Epithelial Cells Exposed to PM2.5 from Beijing, China, in Winter.

Epidemiological studies have corroborated that respiratory diseases, including lung cancer, are related to fine particulate matter (<2.5 µm) (PM2.5) exposure. The toxic responses of PM2.5 are greatly influenced by the source of PM2.5. However, the effects of PM2.5 from Beijing on bronchial genotoxicity are scarce. In the present study, PM2.5 from Beijing was sampled and applied in vitro to investigate its genotoxicity and the mechanisms behind it. Human bronchial epithelial cells 16HBE were used as a model for exposure. Low (67.5 µg/mL), medium (116.9 µg/mL), and high (202.5 µg/mL) doses of PM2.5 were used for cell exposure. After PM2.5 exposure, cell viability, oxidative stress markers, DNA (deoxyribonucleic acid) strand breaks, 8-OH-dG levels, micronuclei formation, and DNA repair gene expression were measured. The results showed that PM2.5 significantly induced cytotoxicity in 16HBE. Moreover, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and cellular heme oxygenase (HO-1) were increased, and the level of glutathione (GSH) was decreased, which represented the occurrence of severe oxidative stress in 16HBE. The micronucleus rate was elevated, and DNA damage occurred as indicators of the comet assay, γ-H2AX and 8-OH-dG, were markedly enhanced by PM2.5, accompanied by the influence of 8-oxoguanine DNA glycosylase (OGG1), X-ray repair cross-complementing gene 1 (XRCC1), and poly (ADP-ribose) polymerase-1 (PARP1) expression. These results support the significant role of PM2.5 genotoxicity in 16HBE cells, which may occur through the combined effect on oxidative stress and the influence of DNA repair genes.

Functional Access to Neuron Subclasses in Rodent and Primate Forebrain.

Viral vectors enable foreign proteins to be expressed in brains of non-genetic species, including non-human primates. However, viruses targeting specific neuron classes have proved elusive. Here we describe viral promoters and strategies for accessing GABAergic interneurons and their molecularly defined subsets in the rodent and primate. Using a set intersection approach, which relies on two co-active promoters, we can restrict heterologous protein expression to cortical and hippocampal somatostatin-positive and parvalbumin-positive interneurons. With an orthogonal set difference method, we can enrich for subclasses of neuropeptide-Y-positive GABAergic interneurons by effectively subtracting the expression pattern of one promoter from that of another. These methods harness the complexity of gene expression patterns in the brain and significantly expand the number of genetically tractable neuron classes across mammals.

Vasoactive Intestinal Polypeptide-Expressing Interneurons in the Hippocampus Support Goal-Oriented Spatial Learning.

Diverse computations in the neocortex are aided by specialized GABAergic interneurons (INs), which selectively target other INs. However, much less is known about how these canonical disinhibitory circuit motifs contribute to network operations supporting spatial navigation and learning in the hippocampus. Using chronic two-photon calcium imaging in mice performing random foraging or goal-oriented learning tasks, we found that vasoactive intestinal polypeptide-expressing (VIP+), disinhibitory INs in hippocampal area CA1 form functional subpopulations defined by their modulation by behavioral states and task demands. Optogenetic manipulations of VIP+ INs and computational modeling further showed that VIP+ disinhibition is necessary for goal-directed learning and related reorganization of hippocampal pyramidal cell population dynamics. Our results demonstrate that disinhibitory circuits in the hippocampus play an active role in supporting spatial learning. VIDEO ABSTRACT.

The efficacy, biodistribution and safety of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis.

DNA vaccines, the third-generation vaccines, were extensively studied. The attenuated Salmonella choleraesuis (S. choleraesuis) was widely focused as a carrier to deliver DNA vaccines in the chromosome-plasmid balanced-lethal system. The efficacy of inhibin DNA vaccine delivered by attenuated S. choleraesuis was proved in mice and cows in our previous studies. In this study, the efficacy of inhibin DNA vaccine was confirmed in rhesus monkeys. To further study the biodistribution and safety, the mice were immunized under laboratory conditions. The results of the rhesus monkeys showed the plasma IgA and IgG titres against inhibin were elevated, and the oestradiol (E2 ) and progesterone (P4 ) levels were increased with immunizing inhibin DNA vaccine. The biodistribution and safety assessment displayed the body weight, pathological change and haematology indexes where there is no significant difference between vaccinated mice and control. And the genomics analysis showed there was no integration of the inhibin gene into the mouse genome 2 months after immunization. This study indicated the inhibin DNA vaccine delivered by attenuated S. choleraesuis was safe. And this vaccine was a potential means to improve their reproductive traits in primates and other animals.

[Chilling damage comprehensive assessment methods for rice.] / 水稻低温冷害综合评估方法.

Based on the grey correlation analysis method, the chilling damage inducing factors and yield structure traits of rice in different growth stages, and the yield structure traits and final yield of rice were regarded as two grey systems. By seeking the grey relations of the grey systems and using the multi level grey correlation analysis method, the comprehensive assessment model of rice chil-ling damage was constructed, and the comprehensive assessment indices of chilling damages in sepa rate stages were established. The rice chilling damages at 27 stations in Northeast China from 1961 to 2015 were assessed separately. The results showed that there was a good corresponding relationship between the chilling damage and the rice yield. The low temperature during the vegetative growth stage, the vegetative growth and reproductive stage, the pollination stage or the grain filling stage significantly decreased the panicle number per plant, the average panicle grain number or the thousand kernel mass, and increased the empty grain rate. A good correspondence existed between temperature and rice yield in the typical chilling damage years.

Machine Learning Capabilities of a Simulated Cerebellum.

This paper describes the learning and control capabilities of a biologically constrained bottom-up model of the mammalian cerebellum. Results are presented from six tasks: 1) eyelid conditioning; 2) pendulum balancing; 3) proportional-integral-derivative control; 4) robot balancing; 5) pattern recognition; and 6) MNIST handwritten digit recognition. These tasks span several paradigms of machine learning, including supervised learning, reinforcement learning, control, and pattern recognition. Results over these six domains indicate that the cerebellar simulation is capable of robustly identifying static input patterns even when randomized across the sensory apparatus. This capability allows the simulated cerebellum to perform several different supervised learning and control tasks. On the other hand, both reinforcement learning and temporal pattern recognition prove problematic due to the delayed nature of error signals and the simulator's inability to solve the credit assignment problem. These results are consistent with previous findings which hypothesize that in the human brain, the basal ganglia is responsible for reinforcement learning, while the cerebellum handles supervised learning.

Thrombin Stimulated Platelet-Derived Exosomes Inhibit Platelet-Derived Growth Factor Receptor-Beta Expression in Vascular Smooth Muscle Cells.

BACKGROUND/AIMS: It is difficult to predict acute thrombotic cardiovascular events in the clinic. Few studies have reported the presence of plasma exosomes containing microRNAs (miRNAs) in cardiovascular events. Therefore, we aimed to investigate the levels of miR-223, miR-339 and miR-21 in plasma exosomes before thrombosis in mouse models of carotid tandem stenosis, as well as the mechanisms underlying the origin and function of these exosomal miRNAs. METHODS: Plasma samples were collected from the carotid tandem stenosis and sham control groups of our successfully developed atherothrombosis mouse models before thrombosis. Platelets from healthy volunteers and mice were purified to obtain thrombin stimulated platelet-derived exosomes. Exosomes were isolated via differential ultracentrifugation, and western blotting and transmission electron microscopy were used for their identification. The total RNA was extracted, and quantitative real-time PCR was performed to determine the expression levels of miR-223, miR-339 and miR-21. DAVID Tools were used to analyze the pathways that were enriched among the miRNA target genes. Immuno-fluorescence staining was performed to identify the protein expression levels of platelet-derived exosome target genes in vascular smooth muscle cells (SMCs) in vitro and in vivo. RESULTS: The levels of miR-223, miR-339 and miR-21, which are associated with platelet activation, were elevated in pooled mouse plasma exosomes before thrombosis and enriched in thrombin-stimulated platelet-derived exosomes in vitro. Platelet-derived growth factor receptor-beta (PDGFRß) was a target of these miRNAs, and PDGFRß expression in vascular smooth muscle cells (SMCs) was inhibited following incubation with platelet-derived exosomes. Platelet-derived exosomes could also inhibit PDGF-stimulated SMC proliferation. Furthermore, a decrease in PDGFRß expression was observed in vascular SMCs around thrombotic areas in vivo. CONCLUSIONS: Our data indicate that activated platelet-derived exosomes containing miR-223, miR-339 and miR-21 could be transferred into SMCs and inhibit PDGFRß expression; these exosomal miRNAs may be a biomarker for predicting atherothrombosis.

Palladium-catalyzed asymmetric cycloadditions of vinylcyclopropanes and in situ formed unsaturated imines: construction of structurally and optically enriched spiroindolenines.

A palladium-catalyzed (3 + 2) cycloaddition of vinyl cyclopropane and α,ß-unsaturated imines generated in situ from aryl sulfonyl indoles is reported. The reaction proceeds with high diastereoselectivity to provide the optically enriched spirocyclopentane-1,3'-indolenines in up to 74% yield and with up to 97% ee, which contains an all-carbon quaternary center and two tertiary stereocenters. The reaction involves a first conjugate addition of the carbon anion of zwitterionic π-allylpalladium complex from vinyl cyclopropane to the in situ formed unsaturated imine followed by a palladium-catalyzed intramolecular C3-allylation of indole.

Baptisms of fire or death knells for acute-slice physiology in the age of 'omics' and light?

With increasing use of various techniques to record optically and electrophysiologically from awake behaving animals and the growing developments of brain-machine interfaces, one might wonder if the use of acute-slice physiology is on its deathbed. Have we actually arrived at a stage where we can abandon the use of acute slices, with most of the information about brain functions coming from in vivo experiments? We do not believe that this is the case, given that our understanding of the nuts and bolts of the nervous system, such as ion channels and transporters in near-native state, neuronal compartmentalization, and single-neuron computation, is far from complete. We believe that in the foreseeable future, questions in these fields will still be best addressed by acute-slice physiology. We approach this review from the perspective of improving acute-slice physiology so it can continue to provide relevant and valuable contributions to neuroscience. We conclude that the death of acute-slice physiology is an obituary prematurely written, merely due to waxing and waning trends in science and the shortsightedness of investigators. Acute-slice physiology has at least one more life to live after the hype around new techniques has passed, but it needs to reinvent itself in light of current knowledge.

Using a million cell simulation of the cerebellum: network scaling and task generality.

Several factors combine to make it feasible to build computer simulations of the cerebellum and to test them in biologically realistic ways. These simulations can be used to help understand the computational contributions of various cerebellar components, including the relevance of the enormous number of neurons in the granule cell layer. In previous work we have used a simulation containing 12000 granule cells to develop new predictions and to account for various aspects of eyelid conditioning, a form of motor learning mediated by the cerebellum. Here we demonstrate the feasibility of scaling up this simulation to over one million granule cells using parallel graphics processing unit (GPU) technology. We observe that this increase in number of granule cells requires only twice the execution time of the smaller simulation on the GPU. We demonstrate that this simulation, like its smaller predecessor, can emulate certain basic features of conditioned eyelid responses, with a slight improvement in performance in one measure. We also use this simulation to examine the generality of the computation properties that we have derived from studying eyelid conditioning. We demonstrate that this scaled up simulation can learn a high level of performance in a classic machine learning task, the cart-pole balancing task. These results suggest that this parallel GPU technology can be used to build very large-scale simulations whose connectivity ratios match those of the real cerebellum and that these simulations can be used guide future studies on cerebellar mediated tasks and on machine learning problems.

A low concentration of ethanol impairs learning but not motor and sensory behavior in Drosophila larvae.

Drosophila melanogaster has proven to be a useful model system for the genetic analysis of ethanol-associated behaviors. However, past studies have focused on the response of the adult fly to large, and often sedating, doses of ethanol. The pharmacological effects of low and moderate quantities of ethanol have remained understudied. In this study, we tested the acute effects of low doses of ethanol (∼7 mM internal concentration) on Drosophila larvae. While ethanol did not affect locomotion or the response to an odorant, we observed that ethanol impaired associative olfactory learning when the heat shock unconditioned stimulus (US) intensity was low but not when the heat shock US intensity was high. We determined that the reduction in learning at low US intensity was not a result of ethanol anesthesia since ethanol-treated larvae responded to the heat shock in the same manner as untreated animals. Instead, low doses of ethanol likely impair the neuronal plasticity that underlies olfactory associative learning. This impairment in learning was reversible indicating that exposure to low doses of ethanol does not leave any long lasting behavioral or physiological effects.

Olfactory conditioning in the third instar larvae of Drosophila melanogaster using heat shock reinforcement.

Adult Drosophila melanogaster has long been a popular model for learning and memory studies. Now the larval stage of the fruit fly is also being used in an increasing number of classical conditioning studies. In this study, we employed heat shock as a novel negative reinforcement for larvae and obtained high learning scores following just one training trial. We demonstrated heat-shock conditioning in both reciprocal and non-reciprocal paradigms and observed that the time window of association for the odor and heat shock reinforcement is on the order of a few minutes. This is slightly wider than the time window for electroshock conditioning reported in previous studies, possibly due to lingering effects of the high temperature. To test the utility of this simplified assay for the identification of new mutations that disrupt learning, we examined flies carrying mutations in the dnc gene. While the sensitivity to heat shock, as tested by writhing, was similar for wild type and dnc homozygotes, dnc mutations strongly diminished learning. We confirmed that the learning defect in dnc flies was indeed due to mutation in the dnc gene using non-complementation analysis. Given that heat shock has not been employed as a reinforcement for larvae in the past, we explored learning as a function of heat shock intensity and found that optimal learning occurred around 41 °C, with higher and lower temperatures both resulting in lower learning scores. In summary, we have developed a very simple, robust paradigm of learning in fruit fly larvae using heat shock reinforcement.

Image enhancement for tracking the translucent larvae of Drosophila melanogaster.

Drosophila melanogaster larvae are model systems for studies of development, synaptic transmission, sensory physiology, locomotion, drug discovery, and learning and memory. A detailed behavioral understanding of larvae can advance all these fields of neuroscience. Automated tracking can expand fine-grained behavioral analysis, yet its full potential remains to be implemented for the larvae. All published methods are unable to track the larvae near high contrast objects, including the petri-dish edges encountered in many behavioral paradigms. To alleviate these issues, we enhanced the larval contrast to obtain complete tracks. Our method employed a dual approach of optical-contrast boosting and post-hoc image processing for contrast enhancement. We reared larvae on black food media to enhance their optical contrast through darkening of their digestive tracts. For image processing we performed Frame Averaging followed by Subtraction then Thresholding (FAST). This algorithm can remove all static objects from the movie, including petri-dish edges prior to processing by the image-tracking module. This dual approach for contrast enhancement also succeeded in overcoming fluctuations in illumination caused by the alternating current power source. Our tracking method yields complete tracks, including at the edges of the behavioral arena and is computationally fast, hence suitable for high-throughput fine-grained behavioral measurements.