Opportunistic top predators partition food resources in a tropical freshwater ecosystem

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暗褐露尾甲成虫在海南豇豆上的空间分布型研究

2015年在海南省豇豆上发现中国新记录种暗褐露尾甲Epuraea picinus。本研究运用5种聚集度指标(m*/m、c、k、I、Ca)和两种回归模型(Taylor幂法则和Iwao回归分析法)研究分析了海南省7个乡镇8块豇豆地上的暗褐露尾甲的空间分布型。结果表明,暗褐露尾甲成虫在海南豇豆上在垂直空间和水平空间均为聚集分布,0.83头/百株时为随机分布。     

Mathematical modeling links Wnt signaling to emergent patterns of metabolism in colon cancer

Cell‐intrinsic metabolic reprogramming is a hallmark of cancer that provides anabolic support to cell proliferation. How reprogramming influences tumor heterogeneity or drug sensitivities is not well understood. Here, we report a self‐organizing spatial pattern of glycolysis in xenograft colon tumors where pyruvate dehydrogenase kinase (PDK1), a negative regulator of oxidative phosphorylation, is highly active in clusters of cells arranged in a spotted array. To understand this pattern, we developed a reaction–diffusion model that incorporates Wnt signaling, a pathway known to upregulate PDK1 and Warburg metabolism. Partial interference with Wnt alters the size and intensity of the spotted pattern in tumors and in the model. The model predicts that Wnt inhibition should trigger an increase in proteins that enhance the range of Wnt ligand diffusion. Not only was this prediction validated in xenograft tumors but similar patterns also emerge in radiochemotherapy‐treated colorectal cancer. The model also predicts that inhibitors that target glycolysis or Wnt signaling in combination should synergize and be more effective than each treatment individually. We validated this prediction in 3D colon tumor spheroids.     

Spatial Charge Storage within Honeycomb‐Carbon Frameworks for Ultrafast Supercapacitors with High Energy and Power Densities

Carbon‐based supercapacitors store charge through the adsorption of electrolyte ions onto the carbon surface. Therefore, it would be more attractive for the enhanced charge storage if the locations for storing charge can be extended from carbon surface to space. Here, a novel spatial charge storage mechanism based on counterion effect from Fe(CN)₆^3? ions bridged by oxygen groups and confined into honeycomb‐carbon frameworks is presented, which can provide additionally spatial charge storage for electrical double‐layer capacitances in a negative potential region and pseudocapacitances from Fe(CN)₆^3?/Fe(CN)₆^4? in a positive potential region. More importantly, an ultrafast supercapacitor based on this novelty carbon can be charged/discharged within 0.7 s to deliver both high specific energy of 15 W h kg^?1 and ultrahigh specific power of 79.1 kW kg^?1 in 1 m Na₂SO₄ electrolyte, much higher than those of previously reported asymmetric supercapacitors in aqueous electrolytes, as well as excellent cycling stability. These features suggest a new generation of ultrafast asymmetric supercapacitors as novel high‐performance energy storage devices.     

斑马鱼转座子时空表达特性

转座子是基因组中可移动和扩展的元件,能够插入新的位点,影响基因组和基因的结构和功能,是基因组进化的内在驱动。为探讨转座子的时空表达特性,首先通过生物信息学方法鉴定出斑马鱼9个疑似活性转座子,包括DNA转座子Tc1家族(Tc-a、Tc-b、Tc-c、Tc-d、Tc-e)、反转录转座子ERV家族(ERV-1、ERV-2)和LINE家族(L1-323、L1-21),然后采用实时荧光定量PCR法检测上述转座子在斑马鱼早期胚胎发育7个阶段及成鱼各主要脏器的表达活性。结果表明:Tc1家族在0.75、2.00、3.00 h各阶段无转录活性,在6.00、15.00、24.00、48.00 h各阶段各转座子均有较高转录活性;反转录转座子转录活性最早出现于3 h,最晚出现于15 h,且随着发育时间的延长,转录活性显著增强。9种转座子在成鱼心脏、大脑、肌肉、肝脏、睾丸和卵巢均有表达,且大脑和心脏中的表达水平显著高于其他组织,睾丸表达水平最低。分析表明转座子的表达具有时间和组织的特异性,可能参与斑马鱼胚胎和组织器官发育调控,尤其是大脑和心脏发育。这些结果为进一步研究转座子是否具有基因表达调控功能提供重要参考。     

Feeding preference as a main determinant of microscale patchiness among terrestrial nematodes

Soil biota are responsible for essential ecosystem services such as carbon storage, nutrient cycling and water retention. However, assessment of the condition of soil biota is hampered by an overwhelming level of diversity. With representatives in all trophic levels of the food web, nematode communities can be used as bioindicators. Accurate assessment of nematode assemblages requires insight into the distribution of specimens with distinct food preferences. With the availability of taxon‐specific quantitative PCR assays, distribution patterns of multiple nematode groups can be investigated simultaneously. Here, microscale patchiness of 45 nematode taxa was studied on 12 sampling sites (each with four adjacent microplots) located on arable fields or semi‐natural grasslands (‘system’), and on marine, river clay or sandy soils (‘soil type’). From each microplot, five composite samples were collected. Contrary to our expectations, an increase in the number of cores per composite sample did not result in more accurate measurements, and apparently the levels of microscale patchiness of the taxa are low compared to what has been reported for oligophagous plant‐parasites. System and soil type did not affect microscale distribution. To investigate the level of patchiness in more detail, detection probability (DP) and variability of abundances were calculated. Common and widespread bacterivorous and fungivorous taxa had DP ≥ 90%, confirming low level of microscale patchiness. With DPs of 40%–70%, predators and most omnivores showed degrees of local clustering. An overview of mean variabilities of abundances is presented that offers insight into how feeding preferences impact the microscale distribution both between and within trophic groups.     

Study design and parameter estimability for spatial and temporal ecological models

The statistical tools available to ecologists are becoming increasingly sophisticated, allowing more complex, mechanistic models to be fit to ecological data. Such models have the potential to provide new insights into the processes underlying ecological patterns, but the inferences made are limited by the information in the data. Statistical nonestimability of model parameters due to insufficient information in the data is a problem too‐often ignored by ecologists employing complex models. Here, we show how a new statistical computing method called data cloning can be used to inform study design by assessing the estimability of parameters under different spatial and temporal scales of sampling. A case study of parasite transmission from farmed to wild salmon highlights that assessing the estimability of ecologically relevant parameters should be a key step when designing studies in which fitting complex mechanistic models is the end goal.     

Bioclimatic transect networks: Powerful observatories of ecological change

Transects that traverse substantial climate gradients are important tools for climate change research and allow questions on the extent to which phenotypic variation associates with climate, the link between climate and species distributions, and variation in sensitivity to climate change among biomes to be addressed. However, the potential limitations of individual transect studies have recently been highlighted. Here, we argue that replicating and networking transects, along with the introduction of experimental treatments, addresses these concerns. Transect networks provide cost‐effective and robust insights into ecological and evolutionary adaptation and improve forecasting of ecosystem change. We draw on the experience and research facilitated by the Australian Transect Network to demonstrate our case, with examples, to clarify how population‐ and community‐level studies can be integrated with observations from multiple transects, manipulative experiments, genomics, and ecological modeling to gain novel insights into how species and systems respond to climate change. This integration can provide a spatiotemporal understanding of past and future climate‐induced changes, which will inform effective management actions for promoting biodiversity resilience.