偏孟德尔分离的遗传学实验设计与探讨

本文将科研中发现的一个含调控杂种花粉不育基因座(S23)的水稻材料(DSSL)应用于教学,设计了一个基于SSR分子标记对比经典孟德尔分离和偏孟德尔分离的综合性实验。利用位于水稻两条染色体上的4个SSR标记对两亲本及其杂交构建的F_2代群体进行单株基因型检测,用显微图像观察与统计分析亲本及杂种F1的花粉育性,不仅从分子水平上验证了分离定律,更从基因型到表型的观察实验中完整展现了水稻的偏孟德尔分离现象及其原因,加深了学生对植物遗传规律、基因型与表型关系的理解,激发了学生对实验的兴趣与探究动机,增强了学生对实验学习的自觉性和积极性。并在此基础上构思一个科研成果转化至教学应用的可持续发展思路,以推动实验教学的改革与创新。

Partitioning tree water usage into storage and transpiration in a mixed forest

Background:Water migration and use are important processes in trees.However,it is possible to overestimate transpiration by equating the water absorbed through the plant roots to that diffused back to the atmosphere through stomatal transpiration.Therefore,it is necessary to quantify the water transpired and stored in plants.Method:The δ^(2)H/δ^(18)O technique and heat ratio method were used to explore the water usage of coniferous and broad-leaved tree species,including the proportions of water used for transpiration and water storage.Results:Platycladus orientalis and Quercus variabilis had strong plasticity in their water usage from different sources.Platycladus orientalis primarily used groundwater(30.5%)and the 60-100-cm soil layer(21.6%)throughout the experimental period and was sensitive to precipitation,absorbing water from the 0-20-cm layer(26.6%)during the rainy season.Quercus variabilis absorbed water from all sources(15.7%-36.5%)except from the 40-60-cm soil layer during the dry season.In addition,it did not change its water source but increased its groundwater uptake during the rainy season.The annual mean water fluxes of P.orientalis and Q.variabilis were 374.69 and 469.50 mm·year−1,with 93.49% and 93.91% of the water used for transpiration,respectively.However,nocturnal sap flow in P.orientalis and Q.variabilis was mainly used for water storage in the trunk rather than transpiration,which effectively alleviated drought stress and facilitated the transport of nutrients.Conclusions:The water stored in both species comprised 6%-7% of the total water fluxes and,therefore,should be considered in water balance models.

Variation in water supply leads to different responses of tree growth to warming

Background:Global climate change,characterized by changes in precipitation,prolonged growing seasons,and warming-induced water deficits,is putting increased pressure on forest ecosystems globally.Understanding the impact of climate change on drought-prone forests is a key objective in assessing forest responses to climate change.Methods:In this study,we assessed tree growth trends and changes in physiological activity under climate change based on measurements of tree ring and stable isotopes.Additionally,structural equation models were used to identify the climate drivers influencing tree growth for the period 1957–2016.Results:We found that the mean basal area increment decreased first and then increased,while the water use efficiency showed a steady increase.The effects of climate warming on tree growth switched from negative to positive in the period 1957–2016.Adequate water supply,especially snowmelt water available in the early critical period,combined with an earlier arrival of the growing season,allowed to be the key to the reversal of the effects of warming on temperature forests.The analysis of structural equation models(SEM)also demonstrated that the growth response of Pinus tabuliformis to the observed temperature increase was closely related to the increase in water availability.Conclusions:Our study indicates that warming is not the direct cause of forest decline,but does indeed exacerbate droughts,which generally cause forest declines.Water availability at the beginning of the growing season might be critical in the adaptation to rising temperatures in Asia.Temperate forests may be better able to withstand rising temperatures if they have sufficient water,with boosted growth even possible during periods of rising temperatures,thus forming stronger carbon sinks.

Polyanionic hydrogel electrolyte enables reversible and durable Zn anode for efficient Zn-based energy storage

Aqueous Zn-ion energy storage systems,which are expected to be integrated into intelligent electronics as a secure power supply,suffer poor reversibility of Zn anodes,predominantly associated with dendritic growth and side reactions.This study introduces a polyanionic strategy to address these formidable issues by developing a hydrogel electrolyte(PACXHE)with carboxyl groups.Notably,the carboxyl groups within the hydrogel structure establish favorable channels to promote the transport of Zn^(2+)ions.They also expedite the desolvation of hydrated Zn^(2+)ions,leading to enhanced deposition kinetics.Additionally,these functional groups confine interfacial planar diffusion and promote preferential deposition along the(002)plane of Zn,enabling a smooth surface texture of the Zn anode.This multifaceted regulation successfully achieves the suppression of Zn dendrites and side reactions,thereby enhancing the electrochemical reversibility and service life during plating/stripping cycles.Therefore,such an electrolyte demonstrates a high average Coulombic efficiency of 97.7%for 500 cycles in the Zn‖Cu cell and exceptional cyclability with a duration of 480 h at 1 mA cm^(-2)/1 mA h cm^(-2)in the Zn‖Zn cell.Beyond that,the Zn-ion hybrid micro-capacitor employing PACXHE exhibits satisfactory cycling stability,energy density,and practicality for energy storage in flexible,intelligent electronics.The present polyanionic-based hydrogel strategy and the development of PACXHE represent significant advancements in the design of hydrogel electrolytes,paving the way for a more sustainable and efficient future in the energy storage field.

Highly inhibited transport of dissolved thallium(I) in manganese oxide-coated sand: Chemical condition effects and retention mechanisms

Thallium contamination in water can cause great danger to the environment.In this study,we synthesized manganese oxide-coated sand(MOCS)and investigated the transport and retention behaviors of Tl(I)in MOCS under different conditions.Characterization methods combined with a two-site nonequilibrium transport model were applied to explore the retentionmechanisms.The results showed that Tl(I)mobility was strongly inhibited in MOCS media,and the retention capacity calculated from the fitted model was 510.41 mg/g under neutral conditions.The retention process included adsorption and oxidative precipitation by the manganese oxides coated on the sand surface.Cotransport with the same concentration of Mn(II)led to halving Tl(I)retention due to competition for reactive sites.Enhanced Tl(I)retention was observed under alkaline conditions,as increasing pH promoted electronegativity on the media surface.Moreover,the competitive cation Ca^(2+)significantly weakened Tl(I)retention by occupying adsorption sites.These findings provide new insights into understanding Tl(I)transport behavior in water-saturated porous media and suggest that manganese oxide-coated sand can be a cost-effective filter media for treating Tl-contaminated water.

Divergent responses of growth rate and antioxidative system of ten Bacillus strains to acid stresses

Response of growth rate and antioxidative system of ten Bacillus strains to acid stresses was assayed.Strong acid treatment significantly decreased the growth rate of the strains.Acid stresses increased the GPX activity and GSSG content of the tested strains.Divergent changes occurred in ROS and antioxidative system(SOD,CAT,GR,MDA and GSH).Environmental changes including soil acidification exert obvi-ous stresses on soil ecosystems and influence soil microor-ganisms.In this study,ten microbial strains were incubated under different acid treatments to investigate responses of microbial growth and antioxidative system to acid stress.All the strains belong to Bacillus genus,but exhibit distinct ecological functions.We observed that these microbial strains had obviously different pH tolerance threshold,in spite of the close phylogenetic classification among strains.Acid stresses exerted significant effects on microbial antiox-idative system,including superoxide dismutase(SOD),cata-lase(CAT)and glutathione transferring enzymes(GPX and GR)and reactants(GSH and GSSH),but the effects were strain specific.Furthermore,we found acid stress effects on total variances of the investigated microbial antioxidative system along the first two principal components(PCs).Activities of CAT and SOD contributed substantially to PC1 that reflected obvious acid effects on NC7 and ZC4,and closely related to intracellular malondialdehyde content.The GSSG activities and GSH/GSSG contributed greatly to PC2 that unveiled acid stress effects on most of the microbial strains.Our results highlight substantially heterogeneous responses of microbial strains to acid stress and support that phylogenetic closeness does not imply functional similarity of soil microorganisms under environmental changes.

Nitrogen doped hollow carbon nanospheres as efficient polysulfide restricted layer on commercial separators for high-performance lithium-sulfur batteries

The polysulfide shuttle limits the development of lithium-sulfur(Li-S) batteries with high energy density and long lifespan. Herein, nitrogen doped hollow carbon nanospheres(NHCS) derived from polymerization of dopamine on SiO_(2)nanospheres are employed to modify the commercial polypropylene/polyethylene/polypropylene tri-layer separators(PP/PE/PP@NHCS). The abundant nitrogen heteroatoms in NHCS exhibit strong chemical adsorption toward polysulfides, which can effectively suppress the lithium polysulfides shuttle and further enhance the utilization of active sulfur. Lithium-sulfur batteries employing the PP/PE/PP@NHCS deliver an initial discharge capacity of 1355 mAh/g and retain high capacity of 921 mAh/g after 100 cycles at 0.2 C. At a high rate of 2 C, the lithium-sulfur batteries exhibit capacity of 461 mAh/g after 1000 cycles with a capacity fading rate of 0.049% per cycle. This work demonstrates that the NHCS coated PP/PE/PP separator is promising for future commercial applications of lithium-sulfur batteries with improved electrochemical performances.

Redox deracemization of α-substituted 1,3-dihydroisobenzofurans

Chiralα-substituted 1,3-dihydroisobenzofurans are key scaffolds in a number of bioactive natural products and synthetic pharmaceuticals.However,catalytic asymmetric approaches have been rarely developed.Here,a redox deracemization technology is adopted to address the catalytic asymmetric synthesis.A broad range ofα-aryl substituted 1,3-dihydroisobenzofurans are effectively deracemized in high efficiency with excellent ee.α-Alkynyl substituted ethers were also compatible with the deracemization technology.