Dielectric properties of nucleated erythrocytes as simulated by the double spherical-shell model

The dielectric properties of nucleated erythrocytes from bullfrogs were measured in a frequency range of 10 kHz–110 MHz.The complex permittivity(ε*),complex conductivity(κ*),and complex resistivity(ρ*)were analyzed and compared in the 10.63%to 37.58%haematocrit(Hct)range.The relaxation behavior,the passive electrical properties,and the cellular structure parameters,including the cell membrane,the cytoplasm,the nuclear membrane,and the nucleoplasm of the nucleated erythrocyte suspensions were investigated.The method used is based on the binomial Cole–Cole equation and the double spherical-shell physical models.Upon the elimination of the electrode polarization effect,two definite relaxations related to the interfacial polarization are observed on low-and high-frequency dispersions.The permittivity values and the characteristic frequency values differ by one order of magnitude:the low-frequency relaxation increments[?ε1=(5.63±1.43)×103]and the characteristic frequency[fc1=(297.06±14.48)kHz]derived from the cell membrane,the high-frequency relaxation increments[?ε2=(5.21±1.20)×102]and the characteristic frequency[fc2=(3.73±0.06)MHz]derived from the dielectric response to the external electric field of the nuclear membrane,respectively.Moreover,the other core dielectric parameters,such as the relative permittivity of the cell membrane[εm=(7.57±0.38)]and the nuclear envelope[εne=(23.59±4.39)],the conductivity of the cytoplasm(hemoglobin,κHb=(0.50±0.13)S/m]and the nuclear endoplasm[κnp=(2.56±0.75)S/m],and the capacitance of the bilayer membranes[Cm:(0.84±0.04)μF/cm2],and Cne:(0.52±0.10)μF/cm2]were also accurately and reliably measured.This work presents a feasible method to evaluate the dielectric parameters and the cellular structure of the erythrocytes of bullfrogs.Moreover,it paves the way for new studies on the haematology of frogs and the detection of nucleated cells via dielectric impedance spectroscopy.

中国海洋生物地理学研究进展和热点:物种分布模型及其应用

海洋生物地理学是研究海洋生物地理分布时空格局、形成过程及其影响因素的学科,对于生物多样性保护、生态系统结构稳定以及海洋资源可持续利用具有重要支撑作用。物种分布模型是研究物种地理分布变化的重要手段,其发展对于海洋生物地理学的发展具有重要的推动作用。本文综述了中国海洋生物地理学的发展历程和现状;提供了物种分布模型的定义、类型、发展历程及相关重要数据库;整理分析了中国海洋生物地理学研究中的部分热点问题,主要涉及全球变化下海洋生物分布区变化、海洋生物谱系地理结构、海洋生物入侵、种群连通性、海洋保护规划、海洋生态修复、海洋生物对极端环境适应、海洋渔业资源管理和海水养殖规划等。本文同时对海洋生物地理学研究的未来发展进行了展望,强调了改进物种分布模型的重要性,提出要强化环境和生物数据库建设,加强海洋生物地理学与其他学科的交叉融合等。本综述对于今后我国海洋生物地理学的研究,尤其是物种分布模型在相关领域中的应用具有参考价值。

Incorporating adaptive genomic variation into predictive models for invasion risk assessment

Global climate change is expected to accelerate biological invasions,necessitating accurate risk forecasting and management strategies.However,current invasion risk assessments often overlook adaptive genomic variation,which plays a significant role in the persistence and expansion of invasive populations.Here we used Molgula manhattensis,a highly invasive ascidian,as a model to assess its invasion risks along Chinese coasts under climate change.Through population genomics analyses,we identified two genetic clusters,the north and south clusters,based on geographic distributions.To predict invasion risks,we employed the gradient forest and species distribution models to calculate genomic offset and species habitat suitability,respectively.These approaches yielded distinct predictions:the gradient forest model suggested a greater genomic offset to future climatic conditions for the north cluster(i.e.,lower invasion risks),while the species distribution model indicated higher future habitat suitability for the same cluster(i.e,higher invasion risks).By integrating these models,we found that the south cluster exhibited minor genome-niche disruptions in the future,indicating higher invasion risks.Our study highlights the complementary roles of genomic offset and habitat suitability in assessing invasion risks under climate change.Moreover,incorporating adaptive genomic variation into predictive models can significantly enhance future invasion risk predictions and enable effective management strategies for biological invasions in the future.

Earthworm biomass and population structure are negatively associated with changes in organic residue nitrogen concentration during vermicomposting

Vermicomposting is an efficient and environmentally friendly technology to dispose of agricultural organic residues.The efficiency of organic residue decomposition during vermicomposting is directly affected by the biomass and population structure of earthworms.In this study,we investigated how the earthworm biomass and population structure responded to changes in the physicochemical properties of six types of organic residue(cattle dung,herbal waste,rice straw,soybean straw,garden waste,and tea residues)during vermicomposting.Each type of organic residues was placed in a pot with earthworms Eisenia fetida,and the physicochemical properties of the organic residues and earthworm growth dynamics were recorded at 0,30,60,and 90 d of vermicomposting.The biomass and population structure of earthworms were stable or increased in rice straw,garden waste,and cattle dung within 60 d of vermicomposting,whereas in tea residues and herb waste,very little earthworm activity(3 adults and 2 cocoons)was recorded on day 30.Among the physicochemical parameters,the substrate C/N ratio was negatively correlated with earthworm growth dynamics.Decomposing organic residues showed higher NH_(4)^(+)-N and NH_(3)^(-)-N concentrations but a lower total organic carbon content,which negatively affected earthworm growth and reproduction.We recommend that chemical properties of vermicomposting systems should be monitored regularly.At the threshold levels of decomposing organic residue NH_(4)^(+)-N and NH_(3)^(-)-N concentrations,earthworms should be removed and the vermicompost can be harvested.Small-and large-scale farmers thus need to monitor the physicochemical properties of vermicompost to sustain active earthworm populations.

Zooplankton biodiversity monitoring in polluted freshwater ecosystems:A technical review

Freshwater ecosystems harbor a vast diversity of micro-eukaryotes(rotifers,crustaceans and protists),and such diverse taxonomic groups play important roles in ecosystem functioning and services.Unfortunately,freshwater ecosystems and biodiversity therein are threatened by many environmental stressors,particularly those derived from intensive human activities such as chemical pollution.In the past several decades,significant efforts have been devoted to halting biodiversity loss to recover services and functioning of freshwater ecosystems.Biodiversity monitoring is the first and a crucial step towards diagnosing pollution impacts on ecosystems and making conservation plans.Yet,bio-monitoring of ubiquitous micro-eukaryotes is extremely challenging,owing to many technical issues associated with micro-zooplankton such as microscopic size,fuzzy morphological features,and extremely high biodiversity.Here,we review current methods used for monitoring zooplankton biodiversity to advance management of impaired freshwater ecosystems.We discuss the development of traditional morphologybased identification methods such as scanning electron microscope(SEM)and ZOOSCAN and FlowCAM automatic systems,and DNA-based strategies such as metabarcoding and real-time quantitative PCR.In addition,we summarize advantages and disadvantages of these methods when applied for monitoring impacted ecosystems,and we propose practical DNA-based monitoring workflows for studying biological consequences of environmental pollution in freshwater ecosystems.Finally,we propose possible solutions for existing technical issues to improve accuracy and efficiency of DNA-based biodiversity monitoring.