Different Genetic Ways for Conditional Gene Regulation in the Mouse Brain

Summary: The conditional gene expression system controlled by the tetracyclineresponsive trans-activator (tTA) in transgenic mice is an important and well characterized genetic tool. In my studies I investigated the function of the Tetregulated genes in the brain when inserted into the chromosome and when applied as extra-chromosomal elements with recombinant Adeno-Associated Virus (rAAV). First, the pool of tTA expressing mouse lines was increased by generating eight functional itTA-expressing TgThy-1.2(xx)-itTAnls transgenic mouse lines. Since for tTA expression the Thy-1.2 promoter was used, which is known to be highly integration-site dependent, lines were obtained which all differed in tTA expression level, expression pattern and ontogenetic profile in the central nervous system (CNS). These mice are a valuable tool for studies on physiological functions of different neuron populations during various developmental stages. Second, the effect of the chromosomal insertion site of Tet-responder genes on their expression was analyzed. In three different Tet-responder mouse lines, the precise integration sites and copy number of tet-responder genes were determined. No correlation between copy number of the Tet-responder gene and its expression was detected, supporting the finding that the chromosomal insertion site has strong effects on the expression of the transgene. Strong Tet-responder gene expression was observed in mice of the transgenic line SA87.5, which has three copies of a transgene inserted in the Pik3c3 gene locus. By retargeting the same position of the Pik3c3 gene locus in embryonic stem cells, only one copy of the transgene was introduced. However, due to the presence of the neo selection marker the single Tet-responsive transgene showed poor induction by tTA. After Cre-virus mediated neo removal, the expression of the Tet-responsive transgene was improved. The limitations of chromosomally inserted Tet-regulated gene elements can be overcome by using the recombinant Adeno-Associated virus (rAAV) mediated gene delivery system to introduce the different elements of the Tet-system into the CNS. It is shown that both Tet-activators and Tet-responder genes are functionally delivered by rAAV vectors, and tissue specific, homogeneous, rapid and robust expression of multiple proteins simultaneously controlled by tTA in rAAV infected CNS areas can be achieved. Moreover these viruses were used to demonstrate that the transcriptionally inactive Tet-responder genes are often epigenetically silenced during development when inserted into the host chromosome, but remain inducible when introduced extra-chromosomally after development

Circuit Neuroscience in Zebrafish

A central goal of modern neuroscience is to obtain a mechanistic understanding of higher brain functions under healthy and diseased conditions. Addressing this challenge requires rigorous experimental and theoretical analysis of neuronal circuits. Recent advances in optogenetics, high-resolution in vivo imaging, and reconstructions of synaptic wiring diagrams have created new opportunities to achieve this goal. To fully harness these methods, model organisms should allow for a combination of genetic and neurophysiological approaches in vivo. Moreover, the brain should be small in terms of neuron numbers and physical size. A promising vertebrate organism is the zebrafish because it is small, it is transparent at larval stages and it offers a wide range of genetic tools and advantages for neurophysiological approaches. Recent studies have highlighted the potential of zebrafish for exhaustive measurements of neuronal activity patterns, for manipulations of defined cell types in vivo and for studies of causal relationships between circuit function and behavior. In this article, we summarize background information on the zebrafish as a model in modern systems neuroscience and discuss recent results

Service selection strategic analysis for selfoperated e-commerce platforms under settlement

In order to study whether e-commerce platforms carry out service cooperation after settlement in-depth, this paper focuses on service selection strategic analysis for agent channels on some self-operated e-commerce platforms settled in hybrid e-commerce platforms. We present multi-leader-follower models in two different scenarios with the platforms as leaders and the manufacturers as followers and give some numerical experiments to analyze the impacts of service selection strategies for self-operated platforms on all supply chain members. Our finding shows that if the service cost efficiency is moderate or low, the self-operated platform prefers to provide its service for the agent; otherwise, its selection mainly depends on the unit product service fee. In addition, fierce service competition and high unit service fee are unfavorable to all members, while high service cost efficiency may hurt both the platform and the manufacturer

Biomass-derived carbons for sodium-ion batteries and sodium-ion capacitors

In the past decade, the rapid development of portable electronic devices, electric vehicles, and electrical devices has stimulated extensive interest in fundamental research and the commercialization of electrochemical energy-storage systems. Biomass-derived carbon has garnered significant research attention as an efficient, inexpensive, and eco-friendly active material for energy-storage systems. Therefore, high-performance carbonaceous materials, derived from renewable sources, have been utilized as electrode materials in sodium-ion batteries and sodium-ion capacitors. Herein, the charge-storage mechanism and utilization of biomass-derived carbon for sodium storage in batteries and capacitors are summarized. In particular, the structure–performance relationship of biomass-derived carbon for sodium storage in the form of batteries and capacitors is discussed. Despite the fact that further research is required to optimize the process and application of biomass-derived carbon in energy-storage devices, the current review demonstrates the potential of carbonaceous materials for next-generation sodium-related energy-storage applications.</p

Standard isometric contraction has higher reliability than maximum voluntary isometric contraction for normalizing electromyography during level walking among older adults with knee osteoarthritis

Introduction: Electromyography (EMG) normalization often relies on maximum voluntary isometric contraction (MVIC), which may not be suitable for knee osteoarthritis (KOA) patients due to difficulties in generating maximum joint torques caused by pain. This study aims to assess the reliability of standard isometric contraction (SIC) for EMG normalization in older adults with KOA, comparing it with MVIC.Methods: We recruited thirty-five older adults with KOA and collected root mean square EMG amplitudes from seven muscles in the affected limb during level walking, SIC, and MVIC tests. EMG data during level walking were normalized using both SIC and MVIC methods. This process was repeated after at least 1 week. We calculated intra-class correlation coefficients (ICCs) with 95% confidence intervals to evaluate between- and within-day reliabilities.Results: SIC tests showed higher between- (ICC: 0.75–0.86) and within-day (ICC: 0.84–0.95) ICCs across all seven muscles compared to MVIC tests. When normalized with SIC, all seven muscles exhibited higher between- (ICC: 0.67–0.85) and within-day (ICC: 0.88–0.99) ICCs compared to MVIC normalization.Conclusion: This study suggests that SIC may offer superior movement consistency and reliability compared to MVIC for EMG normalization during level walking in older adults with KOA

Different wildfire types promoted two-step terrestrial plant community change across the Triassic-Jurassic transition

Frequent wildfires associated with emplacement of the Central Atlantic Magmatic Province (CAMP) are thought to have been important drivers of two significant changes in terrestrial plant communities and diversity during the Triassic-Jurassic Mass Extinction (TJME, ca. 201.51 Ma). ​However, it remains to be investigated whether these two changes are potentially related to different wildfire types. To better understand this relationship, we used a new method to reanalyze fossil pollen and spores across the Triassic-Jurassic transition in the Jiyuan Basin from the North China Plate. Results show that two peaks in wildfire frequency experienced different types of wildfires, with each linked to significant changes in plant communities and diversity losses. In the first wildfire peak, canopy fires dominated and are accompanied by significant losses of canopy forming plants, while in the second wildfire peak, ground cover fires dominated accompanied by significant losses of ground cover plants. ​Changes in atmospheric humidity conditions were an important control on the two different wildfire peaks. Relatively humid climatic conditions corresponded to the prevalence of canopy fires and hindered the spread and development of ground cover fires in wet surface conditions. Conversely, relatively arid climatic conditions corresponded with the prevalence of ground cover fires in dry surface environments. Our results provide a potential relationship between terrestrial plant communities and wildfire types, which is important to further understanding of terrestrial environmental and floral changes driven by Large Igneous Provinces

Different wildfire types promoted two-step terrestrial plant community change across the Triassic-Jurassic transition

Frequent wildfires associated with emplacement of the Central Atlantic Magmatic Province (CAMP) are thought to have been important drivers of two significant changes in terrestrial plant communities and diversity during the Triassic-Jurassic Mass Extinction (TJME, ca. 201.51 Ma). ​However, it remains to be investigated whether these two changes are potentially related to different wildfire types. To better understand this relationship, we used a new method to reanalyze fossil pollen and spores across the Triassic-Jurassic transition in the Jiyuan Basin from the North China Plate. Results show that two peaks in wildfire frequency experienced different types of wildfires, with each linked to significant changes in plant communities and diversity losses. In the first wildfire peak, canopy fires dominated and are accompanied by significant losses of canopy forming plants, while in the second wildfire peak, ground cover fires dominated accompanied by significant losses of ground cover plants. ​Changes in atmospheric humidity conditions were an important control on the two different wildfire peaks. Relatively humid climatic conditions corresponded to the prevalence of canopy fires and hindered the spread and development of ground cover fires in wet surface conditions. Conversely, relatively arid climatic conditions corresponded with the prevalence of ground cover fires in dry surface environments. Our results provide a potential relationship between terrestrial plant communities and wildfire types, which is important to further understanding of terrestrial environmental and floral changes driven by Large Igneous Provinces

Floral response to the Late Triassic Carnian Pluvial Episode

The Late Triassic Carnian Pluvial Episode (CPE; ca. 234–232 Ma) was characterized by dramatic global temperature and humidity increases, which in many terrestrial settings was accompanied by changes from arid to humid vegetation types. This study reviews current evidence of terrestrial floral composition and distribution during the CPE and analyzes spatial and temporal variation with relation to potential environmental driving mechanisms. Available evidence suggests the CPE was a globally significant event that triggered significant increases in the abundance of ferns and hygrophytes in terrestrial floras and freshwater algae in fluvial and lacustrine settings. These changes ended a long interval of relatively arid terrestrial climatic conditions since the early Triassic and are linked temporally with eruptions of the oceanic plateau Wrangellia Large Igneous Province (LIP). The massive release of greenhouse gasses including isotopically light CO2 during 3–4 distinct pulses of Wrangellia volcanism appears to have been the main driver of CPE climate change. Each pulse enhanced global atmospheric circulation and the hydrological cycle and resulted in changes from arid to humid conditions that affected floral abundance and composition. Higher terrestrial primary productivity in humid phases facilitated increased burial of terrestrial organic carbon and led to the recommencement of peat accumulation, ending the coal gap that had persisted since the earliest Triassic times. Enhanced movement of carbon from the atmosphere through the biosphere into the geosphere may have counteracted the warming effects of Wrangellia volcanic greenhouse gas emissions and ultimately led to the return of a steady climate state that terminated the warm and humid conditions of the CPE

Observation of the Anomalous Hall Effect in a Collinear Antiferromagnet

Time-reversal symmetry breaking is the basic physics concept underpinning many magnetic topological phenomena such as the anomalous Hall effect (AHE) and its quantized variant. The AHE has been primarily accompanied by a ferromagnetic dipole moment, which hinders the topological quantum states and limits data density in memory devices, or by a delicate noncollinear magnetic order with strong spin decoherence, both limiting their applicability. A potential breakthrough is the recent theoretical prediction of the AHE arising from collinear antiferromagnetism in an anisotropic crystal environment. This new mechanism does not require magnetic dipolar or noncollinear fields. However, it has not been experimentally observed to date. Here we demonstrate this unconventional mechanism by measuring the AHE in an epilayer of a rutile collinear antiferromagnet RuO$_2$. The observed anomalous Hall conductivity is large, exceeding 300 S/cm, and is in agreement with the Berry phase topological transport contribution. Our results open a new unexplored chapter of time-reversal symmetry breaking phenomena in the abundant class of collinear antiferromagnetic materials.Comment: 33 pages, 14 figures, 2 table