气候因素对黑线姬鼠种群动态影响的非线性效应

受全球气候变化的影响,气候因素与害鼠种群变化之间的关系成为害鼠防治研究中的热点问题。以西安市长安区周边分布的黑线姬鼠为研究对象,通过标志重捕法进行种群动态监测,掌握其种群数量的动态变化规律,并结合非线性的统计方法广义可加模型,对该地区2015—2018年黑线姬鼠种群密度和气候因素数据进行分析,探讨该鼠种群变化与气候因素之间的关系。结果表明,该地区黑线姬鼠种群数量总体显现为下降趋势。黑线姬鼠种群密度存在显著的正向自我调节效应(F_(1.00, 5.77)=27.062,P0.01),且与上一月种群密度存在线性的正相关。当月平均温度与该鼠种群密度之间存在显著的非线性效应(F_(1.90, 5.77 )=4.696,P0.05),两者之间显现为钟型关系,当温度21℃时,两者之间显现为正相关,黑线姬鼠种群密度随温度的升高而升高,反之显现为负相关。当月累计降雨量与其种群密度之间也存在显著的非线性效应(F_(1.87, 5.77)=3.879,P0.05),同样,两者之间也显现为钟型关系,当降雨量90 mm时,两者之间显现为负相关,种群密度随降雨量的增加而降低,反之显现为正相关。因此,温度和降雨对黑线姬鼠种群变化具有调节作用,低温干旱和高温多雨均不适合该鼠的繁殖与生长。     

中国人均生态足迹与生物承载力变化的EMD分析及情景预测

利用经验模态分解(EMD)方法分解并提取1961～2001年中国人均生态足迹与生物承载力变化的波动周期,建立具有周期性波动的非线性动力学预测模型,提出未来50a中国人均生态足迹和生物承载力变化的3种预测情景。结果表明:(1)40a来,中国人均生态足迹在波动中不断增加,具有明显的3.5a和8a两个波动周期;中国人均生物承载力在波动中不断减少,具有明显的2.7a和28a两个周期。(2)若一切照旧,即未来50a中国人均生态足迹与生物承载力保持过去40a的年均变化率不变,则人均生态足迹会持续上升,2050年达到3.391g.hm2;人均生物承载力持续下降,2050年降为0.490g.hm2;而人均生态赤字急剧拉大,2050年为3.024g.hm2,可持续发展形势非常严峻。(3)若缓慢变化,即未来20a中国人均生态足迹保持年均增长率1.195%、人均生物承载力年均减少率0.614%不变,则2025年人均生态足迹为1.849g.hm2、人均生物承载力为0.860g.hm2、人均赤字0.989g.hm2。(4)若人均生态足迹快速减少,即2025～2050年中国人均生态足迹年均减少率为0.996%、人均生物承载力年均减少率为0.614%不变,则2050年人均生态足迹为1.381g.hm2、人均生物承载力0.739g.hm2、人均生态赤字0.641g.hm2,但这需要中国经济发展和技术水平的极大提高、能源消费结构的多元化、居民消费意识和消费模式的快速转变、人民生活质量的极大改善。这样,中国的生态发展才有助于实现全球水平的生态可持续发展,在促进世界可持续发展的道路上起到积极的推动作用。     

A rating scale for wildness and ease of handling laboratory mice: results for 21 inbred strains tested in two laboratories

Rating scales for difficulty in capturing and holding mice were devised that proved to be easy to use and highly sensitive to differences among mouse strains on the A and B priority lists of the Mouse Phenome Project. The simplicity of the scales makes it feasible to rate wildness during behavioral test sessions without adding much to testing time or distracting the technician from the principal task at hand. Overall wildness and placidity ratings obtained by combining capture and hold ratings provide a good impression of the difficulties encountered while working with lab mice in the course of complex experiments. Ratings of 21 inbred strains during the course of 15 behavioral tests in two laboratories demonstrated that the SPRET/Ei, PERA/Ei, CAST/Ei and SWR/J strains were particularly difficult to handle. The NOD/LtJ strain posed no special challenge in the Edmonton laboratory but was very difficult to handle in the Portland lab. The rating scales should be useful for judging the difficulties in working with novel targeted or induced mutations in mice as well as effects of a variety of environmental treatments or drugs.     

Allometric Models for Predicting Aboveground Biomass in Two Widespread Woody Plants in Hawaii

Allometric models are important for quantifying biomass and carbon storage in terrestrial ecosystems. Generalized allometry exists for tropical trees, but species‐ and site‐specific models are more accurate. We developed species‐specific models to predict aboveground biomass in two of the most ubiquitous natives in Hawaiian forests and shrublands, Metrosideros polymorpha and Dodonaea viscosa. The utility of the M. polymorpha allometry for predicting biomass across a range of sites was explored by comparing size structure (diameter at breast height vs. tree height) of the trees used to develop the models against trees from four M. polymorpha‐dominated forests along a precipitation gradient (1630–2380 mm). We also compared individual tree biomass estimated with the M. polymorpha model against existing generalized equations, and the D. viscosa model with an existing species‐specific model. Our models were highly significant and displayed minimal bias. Metrosideros polymorpha size structures from the three highest precipitation sites fell well within the 95% confidence intervals for the harvested trees, indicating that the models are applicable at these sites. However, size structure in the area with the lowest precipitation differed from those in the higher rainfall sites, emphasizing that care should be taken in applying the models too widely. Existing generalized allometry differed from the M. polymorpha model by up to 88 percent, particularly at the extremes of the data range examined, underestimating biomass in small trees and overestimating in large trees. The existing D. viscosa model underestimated biomass across all sizes by a mean of 43 percent compared to our model. The species‐specific models presented here should enable more accurate estimates of biomass and carbon sequestration in Hawaiian forests and shrublands.     

人类最大可持续海洋足迹的模拟

在William Rees ＆ Mathis Wackernagel最初提出的生态足迹模型理论所划分的六类基本生态生产性土地面积中,海洋以其能为人类提供鱼类等海产品而被单独列为水域一项。海洋生物资源是一种典型的可再生资源,人类只有采取合理的开发策略方可保证海洋生物资源最大的可持续生产量。借用生态足迹、生物承载力概念的内涵,提出海洋足迹、海洋承载力两个新概念;运用非线性科学理论在海洋足迹与海洋承载力呈二次非线性关系的假设下,建立海洋承载力二次非线性开发的动力模式,并运用稳定性分析理论对其求解、分析。结果表明：（1）海洋承载力与其增长率呈正相关关系,与海洋足迹增长率呈负相关关系;（2）为保证海洋生物资源的可持续利用,人类必须控制最大海洋足迹增长率为r/xm（r为海洋承载力增长率,xm为最大海洋承载力）,方可获得可持续的最大海洋足迹为rxm/4,此时海洋承载力可以维持在稳定的平衡态（为其最大承载力的一半）。     

基于非线性热扩散效应的亚衍射极限光声二次谐波显微成像技术

本文提出了一种基于非线性热扩散效应的光声二次谐波显微SH-PAM成像技术,用于实现亚衍射极限光声成像。生物组织受到强度调制的高斯激光束辐射时,组织吸收光子形成高斯分布的温度场,由于热扩散系数非线性热效应引起的非线性光声PA效应,从而产生光声二次谐波信号。模拟和试验结果均表明,重建后的光声二次谐波成像的横向分辨率超过了传统光学成像分辨率。本文通过仿体样品验证了该方法的可行性,并且对人表层皮肤细胞进行了成像,以证明其对生物样品的成像能力。该方法扩展了传统光声成像的范围,为超分辨成像开辟了新的可能性,为生物医学成像和材料检测提供了新的方法。     

ACOUSTIC COMMUNICATION SIGNALS OF MYSTICETE WHALES

ABSTRACT

Mysticete (baleen) whales produce a variety of vocalizations and sounds, but relatively few of these have been well described with accompanying behavior. This review concentrates on the vocalizations consistently associated with behavioral interactions or acoustic exchanges between or among conspecifics. These communication “signals” have been categorized for this review as contact calls of single animals outside of the breeding season (including cow-calf pairs), vocalizations reported during the breeding season (often designated as “songs”), and calls produced by active groups of whales that may or may not have a reproductive function. While much remains unknown, the data obtained thus far indicate that the social vocalizations of baleen whales have structural/functional similarities with those of other mammals and birds.     

Stability analysis of an artificial biomolecular oscillator with non-cooperative regulatory interactions

Oscillators are essential to fuel autonomous behaviours in molecular systems. Artificial oscillators built with programmable biological molecules such as DNA and RNA are generally easy to build and tune, and can serve as timers for biological computation and regulation. We describe a new artificial nucleic acid biochemical reaction network, and we demonstrate its capacity to exhibit oscillatory solutions. This network can be built in vitro using nucleic acids and three bacteriophage enzymes, and has the potential to be implemented in cells. Numerical simulations suggest that oscillations occur in a realistic range of reaction rates and concentrations.     

The Macroscopic Rate of Nucleic Acid Translocation by Hepatitis C Virus Helicase NS3h Is Dependent on Both Sugar and Base Moieties

The nonstructural protein 3 helicase (NS3h) of hepatitis C virus is a 3′-to-5′ superfamily 2 RNA and DNA helicase that is essential for the replication of hepatitis C virus. We have examined the kinetic mechanism of the translocation of NS3h along single-stranded nucleic acid with bases uridylate (rU), deoxyuridylate (dU), and deoxythymidylate (dT), and have found that the macroscopic rate of translocation is dependent on both the base moiety and the sugar moiety of the nucleic acid, with approximate macroscopic translocation rates of 3 nt s^− 1 (oligo(dT)), 35 nt s^− 1 (oligo(dU)), and 42 nt s^− 1 (oligo(rU)), respectively. We found a strong correlation between the macroscopic translocation rates and the binding affinity of the translocating NS3h protein for the respective substrates such that weaker affinity corresponded to faster translocation. The values of K_0.5 for NS3h translocation at a saturating ATP concentration are as follows: 3.3 ± 0.4 μM nucleotide (poly(dT)), 27 ± 2 μM nucleotide (poly(dU)), and 36 ± 2 μM nucleotide (poly(rU)). Furthermore, results of the isothermal titration of NS3h with these oligonucleotides suggest that differences in TΔS⁰ are the principal source of differences in the affinity of NS3h binding to these substrates. Interestingly, despite the differences in macroscopic translocation rates and binding affinities, the ATP coupling stoichiometries for NS3h translocation were identical for all three substrates (∼ 0.5 ATP molecule consumed per nucleotide translocated). This similar periodicity of ATP consumption implies a similar mechanism for NS3h translocation along RNA and DNA substrates.