植物光合结构与非光合结构的功能平衡：来自三种亚热带乔木树种的实验证据

植物的地上部分和地下部分存在功能性平衡现已十分清楚,但植物的地上部分是否在其光合结构（叶组织）和非光合结构（枝和茎）之间也存在功能性平衡尚不明晰,本文提出两个研究假设并检验之：1）植物地上部分在其光合与非光合结构之间存在功能性平衡;2）此功能性平衡的维持依赖于对光合和非光合结构生物量分配的调节,为验证此假设,采用枝叶修剪的方式（连续两年修剪,四个修剪强度：0,20%,50%,70%）对3种亚热带乔木树种榕（Ficus microcarpa),黄桷树（Ficus virens)和樟（Cinnamomum camphora)进行了研究。结果表明,修剪使所有树种地上部分的光合与非光合结构生物量比率（P/NP）立即下降,下降程度随修剪强度的程式高而增大,但不论是首次修剪还是第二次修剪,修剪处理一年后,修剪株地上部分的光合与非光合结构生物量比率升高,且此生物量比率不低于非修剪株的光合与非光合结构生物量比率。此研究结果证实了植物地上部分光合与非光合结构间存在功能性平衡的假设,与假设一致。植株的生物量分配在修剪后发生了改变;修剪株加大了对光合结构（叶组织）的生物量分配（大量的新生产地上部分生物量被分配到光合结构）,同时却减少了对非光合结构（枝和茎）的分配,此分析格局的改变保证了光合与非光合结构功能性平衡的恢复与维持,可以认为,通过改变生物量分配格局以维持光合与非光合结构功能平衡是植物低御外来干扰和/或损伤的一种有效策略。     

秦岭火地塘林区锐齿栎群落中6种植物光合特性研究

用Li-6400便携式光合测定系统测定了火地塘林区主要成林树种锐齿栎群落中6种植物的光合特性。结果表明：（1）从林冠层到草本层,光合有效辐射强度明显减弱,并且乔木层、灌木层和草本层之间的差异均达到了显著水平（P〈0．05）;（2）乔木层锐齿栎的光合速率日变化为“双峰”曲线,表现出明显的“午休”现象,而林下植物灌木层和草本层光合速率日变化整体上呈“单峰”曲线,无“午休”现象;（3）光饱和点和光补偿点均表现为乔木〉灌木〉草本。表明植物光合“午休”现象是由中午高光强、高气温和低湿度引起的。并非某些植物的特性．植物的光合特性与其生境特点相符。     

不同支持物对攀援植物--葎草雌雄株光合特性及生物量结构的影响

葎草[Humulus scandens(Lour.)Merr.]为草本雌雄异株攀援植物,采用野生种群人为控制的方法,设置分枝找到乔木支持物(高度(3±0.5)m)、灌木支持物(高度(1±0.5)m)和无支持物3种生长方式,测定雌(♀)、雄(♂)株分枝的叶面积参数、光合参数、叶绿素含量、可溶性糖含量及茎、叶、花在分枝、构件、单株水平下生物量分配比等指标,分析支持物对分枝光合特性和生物量结构的影响,探讨雌、雄分枝利用支持物的性别差异及响应支持物的生态适应差异。结果表明:(1)分枝的单叶面积、总叶面积、叶面积比率、比叶面积对支持物响应存在性别差异,♀株叶面积参数均大于♂株;支持物差异主要影响叶绿素a含量,对叶绿素b、叶绿素a/b影响不显著。(2)支持物差异对分枝叶片的光合参数均有显著的影响(P0.05),支持物对光合参数影响顺序为GsPnTrCi,性别差异影响顺序为GsTrPnCi;可溶性糖含量在性别间、支持物间均表现出极显著的差异(P0.01),♂株糖含量显著高于♀株。(3)在分枝水平下,♀株叶、茎及花生物量分配比都未受到支持物不同的影响(P≥0.05),而♂株在叶、茎的生物量分配比方面受影响显著(P0.05);在构件水平下,支持物差异显著影响了♂株分枝间的营养生长构件分配比,显著影响了♀株分枝间的生殖生长构件分配比;在单株水平下,叶分配比仅在支持物间差异显著(P0.05),而茎、花分配比在性别间、支持物间均有显著差异。(4)雌雄分枝的光合特性和生物量结构对不同支持物的响应差异明显,使葎草单株的生理整合性和适应性大幅度提高。研究以雌雄异株攀援植物为材料,从分枝水平分析支持物对雌雄株光合特性及生物量结构的影响,研究结果对探讨雌雄异株攀援植物的生态适应性具一定的价值。     

重庆地区几种常见单叶与复叶树种叶内生物量分配及异速生长分析

以6种复叶和7种单叶树种为材料,对叶内光合结构和支撑结构的生物量分配及异速生长关系在单叶和复叶树种中的变化规律进行研究.结果显示:单叶树种支撑结构的生物量投资比例显著大于复叶.单叶树种的支撑结构质量比与叶大小(叶面积和总叶干重)无明显的相关性,其光合结构与支撑结构呈等速生长关系;复叶树种的支撑结构质量比随叶大小的增加而...     

古田山自然保护区地下芽植物多样性及其生物量分配策略

地下芽植物能够通过地下储存器官占据生境资源、储存营养物质等策略来获得生态优势,其地下储存器官多样性以及生物量分配策略,对地下芽植物物种组成以及生态系统功能产生重要影响。然而,以往研究多关注草地生态系统的地下芽植物,对森林地下芽植物的了解仍然缺乏。采集了古田山国家级自然保护区不同海拔分布的693个草本植物个体,分析了地下芽植物及其地下储存器官的类型与多样性,比较了地下芽植物与非地下芽植物的地上、地下各器官的绝对、相对生物量。结果显示：（1）地下芽植物的相对丰富度为69.1%,相对多度为88.2%。大多为根状茎植物,主要由禾本科、莎草科、堇菜科和蕨类植物组成。（2）除茎外,地下芽植物各器官的绝对生物量（叶：1.94g,根：0.65g,地上部分：2.0g,地下部分：4.1g）均大于非地下芽植物（叶：0.26g,根：0.13g,地上部分：0.68g,地下部分：0.13g）。（3）地下芽植物叶（0.40）与茎（0.14）的相对生物量小于非地下芽植物（叶：0.48,茎：0.35）,地下部分相对生物量（0.56）大于非地下芽植物（0.17）。本研究表明,以根状茎植物为主的地下芽植物是古田山亚热带森林生态系统草本植物的主要构成者,且个体普遍较大,倾向于将生物量投资于地下器官。这些结果为认识地下芽植物的生态策略与功能以及草本植物群落管理提供了科学依据。     

静电场对植物光合器官结构和功能变化的影响

静电场促进水萝卜对矿质元素的吸收,叶片光合色素的含量及光合、呼吸活性增加,使叶片光合细胞的数目、细胞中叶绿体数目、叶绿体中基粒及类囊体片尾数都趋增加。结果表明,先合结构及活性的改善与静电场促进植物的离子吸收有关,从而改善了植物的营养状况。     

5种木本豆科植物的光合特性研究

本文测定了鹤山丘陵地豆科阔叶混交林中５种植物（大叶相思、马占相思、绢毛相思、海南红豆和新银合欢）在林地条件下的光合速率、呼吸速率和叶绿素含量以及５种植物光合速率的日变化和季节变化。结果表明：植物在冬季和春季的光合速率较低,夏季和秋季都相对较高。年日平均光合速率（μｍｏｌＣＯ２ｍ－２ｓ－１）绢毛相思最高６．１３,海南红豆最低４．６５;植物的呼吸各异,其中新银合欢的呼吸作用最强,海南红豆最低;叶绿素含量与光合速率不存在相关关系。从国外引种植物（包括新银合欢和３种相思树）的光合速率高于乡土树种海南红豆,表明这几种引种植物适应南亚热带丘陵地区的自然环境。     

不同光强下生长的两种榕树叶片光合能力与比叶重、氮含量及分配的关系

观测了不同光强下生长的两种榕树幼苗叶片的光合能力、比叶重(LMA)、氮含量及在光合机构中的分配.结果表明,两种榕树幼苗的最大净光合速率(Pmax)均随生长光强的升高而升高,这与LMA、单位面积氮含量(NA)和光合氮利用效率随生长光强的升高而升高有关.除36%光强下外,相同光强下生长的喜光的斜叶榕(Ficus tinctoria)的Pmax均显著高于耐荫的假斜叶榕(Ficus subulata),这与其叶片中氮在羧化组份和生物力能学组份中的分配系数、LMA和NA较高有关.     

不同种群小桐子光合及形态特性的比较

研究了小桐子（Jatropha curcas）9个种群的叶氮分配、光合能力、生物量积累及分配、种子产量等一系列生理及形态特征。结果表明：小桐子叶片的最大光合速率与叶氮在光合机构中的分配系数有显著的正相关关系;小桐子的最终生物量受光合能力和形态特征的共同影响;生物量与种子产量之间没有必然的联系。多数参数在小桐子不同种群之间存在显著差异,表明种群之间存在遗传差异,但对生长环境的适应性不是小桐子种群产生遗传差异的主要原因。与其他8个种群相比,瑞丽种群的各项生理指标、生物量及种子产量均处于较优水平,在今后小桐子的大面积推广及杂交育种时可优先考虑该种源,但对于其适生范围及抗逆能力需要进一步研究。     

不同倍性大青杨的光合特性及叶片解剖结构比较

通过对二年生二倍体、三倍体和四倍体大青杨叶片结构和光合特性的研究,探讨不同倍性大青杨生长性状差异的原因。结果表明：不同倍性大青杨的净光合速率（Pn）、光饱和点（LSP）、光补偿点（LCP）等光合指标差异显著。三倍体的最大净光合速率（Pmax）高出二倍体21%。叶片厚度、表皮细胞厚度、栅栏组织厚度、栅栏组织与海绵组织厚度的比值,都是三倍体和四倍体大青杨比二倍体高,且均呈现增加的趋势。其中,四倍体大青杨表皮细胞最厚,上下表皮分别高出二倍体64%和17%。三倍体大青杨的栅栏组织厚度及栅栏组织与海绵组织厚度的比值最大,比值高出二倍体50%。通过叶片光合特性和解剖结构比较证明,三倍体和四倍体大青杨对光的适应性和光合作用能力强于二倍体。     

The genetic relationships between the kringle domains of human plasminogen,prothrombin, tissue plasminogen activator,urokinase, and coagulation factor XII

Summary A computer-based statistical evaluation of the optimal alignments of the kringle domains of human plasminogen, human prothrombin, human tissue plasminogen activator, human urokinase, and human coagulation Factor XIIa, as well as the putative kringle of human haptoglobin, has been performed. A variety of different alignments has been examined and scores calculated in terms of the number of standard deviations (SD) of a given match from randomness. With the exception of human haptoglobin, it was found that very high alignment scores (8.9–23.0 SD from randomness) were obtained between each of the kringles, with the kringle 1 and kringle 5 regions of human plasminogen displaying the highest similarity, and the S kringle of human prothrombin and the human Factor XII kringle showing the least similarity. The relationships obtained were employed to construct an evolutionary tree for the kringles. The predicted alignments have also allowed nucleotide mutations in these regions to be evaluated more accurately. For those regions for which nucleotide sequences are known, we have employed the maximal alignments from the protein sequences to assess nucleotide sequence similarities. It was found that a range of approximately 40–55% of the nucleotide bases were placed at identical positions in the kringles, with the highest number found in the alignment of the two kringles of human tissue plasminogen activator and the lowest number in the alignment of the S kringle of prothrombin with the second kringle of tissue plasminogen activator. From both protein and nucleotide alignments, we conclude that haptoglobin is not statistically homologous to any other kringle.Secondary structural comparisons of the kringle regions have been predicted by a combination of the Burgess and Chou-Fasman methods. In general, the kringles display a very high number of -turns, and very low -helical contents. From analysis of the predicted structures in relationship to the functional properties of these domains, it appears as though many of their functional differences can be related to possible conformational alterations resulting from amino acid substitutions in the kringles.     

2D Metal Zn Nanostructure Electrodes for High‐Performance Zn Ion Supercapacitors

Recent supercapacitors show a high power density with long‐term cycle life time in energy‐powering applications. A supercapacitor based on a single metal electrode accompanying multivalent cations, multiple charging/discharging kinetics, and high electrical conductivity is a promising energy‐storing system that replaces conventionally used oxide and sulfide materials. Here, a hierarchically nanostructured 2D‐Zn metal electrode‐ion supercapacitor (ZIC) is reported which significantly enhances the ion diffusion ability and overall energy storage performance. Those nanostructures can also be successfully plated on various flat‐type and fiber‐type current collectors by a controlled electroplating method. The ZIC exhibits excellent pseudocapacitive performance with a high energy density of 208 W h kg^?1 and a power density from 500 W kg^?1, which are significantly higher than those of previously reported supercapacitors with oxide and sulfide materials. Furthermore, the fiber‐type ZIC also shows high energy‐storing performance, outstanding mechanical flexibility, and waterproof characteristics, without any significant capacitance degradation during bending tests. These results highlight the promising possibility of nanostructured 2D Zn metal electrodes with the controlled electroplating method for future energy storage applications.     

The monofunctionalized 1,4,7-triazacyclononane derivatives 1,4,7-triazacyclononane-N-acetate (L) and N-(2-hydroxybenzyl-1,4,7-triazacyclononane (HL) and their complexes with vanadium(IV)/(V). Localized and delocalized electronic structures in compounds containing the mixed valent [OV---O---VO] core

The synthesis of the tetradentate pendant arm macrocycles 1,4,7-triazacyclononane-N-acetate (L¹) and N-(2-hydroxybenzyl)-1,4,7-triazacyclononane (HL²) and their coordination chemistry with vanadium(IV) and (V) are reported. The following mononuclear species have been prepared and characterized by UV-Vis, IR spectroscopy: [L¹V^IVO(NCS)] (1), [L¹VO₂]·H₂O (2), [L²VO(NCS)] (3), [L²VO(NCS)]Cl (4), and [L²VO₂] (5). In addition, the dinuclear, mixed valent complexes [L₂¹V₂O₃]Br (6), [L₂²V₂O₃](ClO₄)·0.5acetone (7), and the homovalent complex [L₂²V₂O₃](ClO₄)₂ (8) have been synthesized. Complexes 2, 3, 6 and 7 have been characterized by single crystal X-ray crystallography. Crystal data: 2, space group P2₁c,a=9.944(4),b=6.701(3),c=18.207(8)Å, β=102.88(3)°, V=1182.7 ų, Z=4, D_calc=1.51 g cm⁻³, R=0.049 based on 4760 reflections; 3, space group Pbca, A=11.003(6), b=14.295(7), C=20.21(1) Å, V=3178.8 ų, Z=8, D_calc=1,50 g cm⁻³, R=0.057 based on 1049 reflections; 6, space Pbcn, a=12.922(3), B=13.852(3), C=12.739(3) Å, V=2280.3 ų, Z=4, D_calc=1,75 g cm⁻³, R=0.047 based on 1172 reflections; 7, space group C2/c, A=23.553(9), B=13.497(5), C=20.951(8) Å, β=90.03(3)°, V=6660.2 ų, Z=8, D_calc=1.49 g cm⁻³, R=0.053 based on 3698 reflections. Complexes 6 and 7 are mixed valent V(IV)/(V) complexes containing the [OV---O---VO]³⁺ core. In the solid state 6 belongs to class III (delocalized) and 7 to class I (localized) according to the Robin and Day classification of mixed valent compounds. A rationale for these differing electronic structures is given.     

Rationally Designed Hierarchical TiO2@Fe2O3 Hollow Nanostructures for Improved Lithium Ion Storage

Hollow and hierarchical nanostructures have received wide attention in new‐generation, high‐performance, lithium ion battery (LIB) applications. Both TiO₂ and Fe₂O₃ are under current investigation because of their high structural stability (TiO₂) and high capacity (Fe₂O₃), and their low cost. Here, we demonstrate a simple strategy for the fabrication of hierarchical hollow TiO₂@Fe₂O₃ nanostructures for the application as LIB anodes. Using atomic layer deposition (ALD) and sacrificial template‐assisted hydrolysis, the resulting nanostructure combines a large surface area with a hollow interior and robust structure. As a result, such rationally designed LIB anodes exhibit a high reversible capacity (initial value 840 mAh g^?1), improved cycle stability (530 mAh g^?1 after 200 cycles at the current density of 200 mA g^?1), as well as outstanding rate capability. This ALD‐assisted fabrication strategy can be extended to other hierarchical hollow metal oxide nanostructures for favorable applications in electrochemical and optoelectronic devices.     

Analysis of loop boundaries using different local structure assignment methods

Loops connect regular secondary structures. In many instances, they are known to play important biological roles. Analysis and prediction of loop conformations depend directly on the definition of repetitive structures. Nonetheless, the secondary structure assignment methods (SSAMs) often lead to divergent assignments. In this study, we analyzed, both structure and sequence point of views, how the divergence between different SSAMs affect boundary definitions of loops connecting regular secondary structures. The analysis of SSAMs underlines that no clear consensus between the different SSAMs can be easily found. Because these latter greatly influence the loop boundary definitions, important variations are indeed observed, that is, capping positions are shifted between different SSAMs. On the other hand, our results show that the sequence information in these capping regions are more stable than expected, and, classical and equivalent sequence patterns were found for most of the SSAMs. This is, to our knowledge, the most exhaustive survey in this field as (i) various databank have been used leading to similar results without implication of protein redundancy and (ii) the first time various SSAMs have been used. This work hence gives new insights into the difficult question of assignment of repetitive structures and addresses the issue of loop boundaries definition. Although SSAMs give very different local structure assignments capping sequence patterns remain efficiently stable.     

MicroED in drug discovery

The cryo-electron microscopy (cryo-EM) method microcrystal electron diffraction (MicroED) was initially described in 2013 and has recently gained attention as an emerging technique for research in drug discovery. As compared to other methods in structural biology, MicroED provides many advantages deriving from the use of nanocrystalline material for the investigations. Here, we review the recent advancements in the field of MicroED and show important examples of small molecule, peptide and protein structures that has contributed to the current development of this method as an important tool for drug discovery.     

Retrospective Estimate of the Individual History of Life in Population Studies on Mammals

Analysis of the recording structures in mammals, such as dentine, cementum, or bone tissue, makes it possible to estimate the parameters of individual history of life: age at the moment of death, seasons of death and birth, growth rate, age of sexual maturation, etc. Using the reindeer (Rangifer tarandus) as an example, it has been shown what specific life features essential for population studies may be estimated when only mandibles with teeth are available.     

In vitro initiation of adventitious structures in relation to the abscission zone in needle explants of Picea abies: anatomical considerations

A comparison of the regeneration potential of needles of different ages in Picea abies emphasized the importance of taking into account the manner of explantation as well as the state of differentiation of the abscission zone. Generally, response in terms of initiation of adventitious structures decreased progressively not only with needle age (5 to 10 to 15 mm long) but also with the distance from the abscission zone towards the tip, that is, distally. On a bud-induction medium adventitious shoot but primordia were produced proximally and distally (except for the very tip) of the weakly-developed abscission zone in needles ca. 5 mm and shorter. In needles between 5 and 10 mm long the various cell types of the abscission zone commenced differentiation, and adventitious structures (shoot bud and other primordia) were formed proximal and immediately distal to it. In needles ca. 15 mm long, in which the abscission zone's hyaline, separation and protective layers became well-developed and where senescence of the distal part commenced, response was limited to proximal tissues. Divisions giving rise to adventitious primordia distal to the abscission zone arose from epidermal cells proper and, in a more acropetal position, also from subsidiary cells of the stomata. Cells of the hypodermis contributed only in the near-distal region of the abscission zone in younger needles, and before commencing differentiation into fibres.
When excised carefully, the explant consists of a leaf plus a peg-like cushion of axillary, meristematic tissue proximal to the abscission zone and capable of ready regeneration. In view of the apparent relationship between age and the stage of development of the abscission zone, it was concluded that there exists a critical needle length which should not be exceeded when attempting in vitro induction of organ primordia.     

Further observations on a cytoplasmic structure in the hamster oocyte

Summary Cytoplasmic structures consisting of two loops of “unit membrane” connected by a region of straight or curved 7-layered membrane are described. It is suggested that this appearance is caused by the collapse of a vesicle lined with a thin coating of electron-dense material.