Cryptic lineages and potential introgression in a mixed-ploidy species (Phragmites australis) across temperate China

Polyploidization and hybridization are very common in natural plant species, and mixed-ploidy species provide a unique opportunity to study the effects of evolutionary history, local abundance, and ploidy level on the direction and extent of introgression between intraspecific lineages. First, we delimited two morphologically cryptic lineages of Phragmites australis Trin. ex Steud. in temperate China using 11 nuclear microsatellites and two chloroplast DNA fragments with 225 samples from China as well as 11 samples from Oceania and Europe. Our evidence supported that haplotype O and haplotype P were two relatively independent lineages with low and high ploidy levels, respectively; haplotype M might be ancient and could have undergone a complex evolutionary history. Then we examined the lineage divergence and compared the introgression patterns between two major lineages along geographical and abundance gradients with a large number of samples (n = 1067) collected from China. The sympatric coexistence of two lineages in north and northeast China implies an ongoing or potential introgression between them. Cline analysis showed that the level of genetic admixture were significantly correlated with longitude rather than latitude. Our results also suggested that ploidy level could deeply influence the introgression asymmetry, and the effect of the current local abundance on introgression might be covered by the past coexistence time driven by phylogeographic history. Our study draws a baseline for future research on the ecological and evolutionary consequences of migration and introgression of Chinese P. australis under global change.     

Multilocus sequence analysis of Fusarium pseudograminearum reveals a single phylogenetic species

Fusarium pseudograminearum causes crown rot of wheat in Australia and most other wheat growing regions, but its evolutionary history is largely unknown. We demonstrate for the first time that F. pseudograminearum is a single phylogenetic species without consistent lineage development across genes. Isolates of F. pseudograminearum, F. graminearum sensu lato, and F. cerealis, were collected from four countries and four single copy, nuclear genes were partially sequenced, aligned with previously published sequences of these and related species, and analysed by maximum parsimony and Bayesian inference. Evolutionary divergence varied between genes, with high phylogenetic incongruence occurring between the gene genealogies. The absence of geographic differentiation between isolates indicates that the introduction of new fungal strains to a region has the potential to introduce new pathogenic and toxigenic genes into the native population through sexual recombination.     

Multiple Pleistocene refugia and recent diversification for Streptocarpus ionanthus (Gesneriaceae) complex: Insights from multiple molecular sources

Streptocarpus ionanthus (Gesneriaceae) is endemic to Tanzania and Kenya, distributed in Tanga, Morogoro, and Kilifi regions. The species houses nine subspecies characterized by complex morphotypes and poorly understood evolutionary relationships, and thus is an ideal model for investigating evolutionary dynamics over time. Using multiple methods, we sought to test our hypothesis that the infraspecific taxa in Str. ionanthus are slightly variable and evolving populations. We first examined the genetic diversity, population differentiation, and phylogeographic structure among the populations of Str. ionanthus using both chloroplast and nuclear markers. We then estimated the divergence time of Str. ionanthus lineages and modeled past and future distribution. Despite Str. ionanthus exhibiting bottleneck events across its range, the populations maintain relatively high genetic diversity attributed to historical population admixture or local adaptation arising from habitat heterogeneity. The phylogeographic and genetic structure revealed a high connection among the Usambara mountains populations, while molecular dating suggested most diversification of haplotypes began ~1.32–0.18 million years ago and intensified toward the present, a conclusion of recent diversification. Phylogenetic relationship of Str. ionanthus cpDNA haplotypes revealed five main lineages with unique haplotypes that could be suggestive of past isolated refugia during the Pleistocene climate shifts. According to niche modeling, the stability of suitable areas during the Last Glacial Maximum (LGM) offered protective micro-habitats that have preserved the genetic diversity of Str. ionanthus to date. In conclusion, our findings suggest a complex Str. ionanthus with slightly variable lineages or populations attributed to multiple refugia and on the verge of divergence.     

Population genetic structure of the giant panda staple food bamboo (Fargesia spathacea complex) and its taxonomic implications

The taxonomy of woody bamboo presents many difficulties due to its long blooming interval and complex morphological variation. Whether the current taxonomy reflects genuine species divergence within woody bamboo is an intriguing question. The Fargesia spathacea Franch. complex comprises 15 closely related species with a sympatric distribution in China. Their classification has long been controversial because only a handful of vegetative traits are available, providing a good opportunity to explore the evolutionary relationships and genetic differentiation in woody bamboo. Here, we present a study involving 750 individuals from 39 representative populations in the F. spathacea complex using 14 simple sequence repeat markers. We found varying degrees of genetic diversity across populations of the F. spathacea complex (He = 0.07–0.81) and largely negative F-values at the population level, implying an excess of heterozygotes in the populations. Phylogenetic analyses revealed that all populations were divided into two major groups (clusters A and B), with the majority of the 15 species representing distinct genetic lineages. Based on population genetic analysis along with morphological evidence, we confirmed the identity of three species (F. decurvata J. L. Lu, F. spathacea, and F. murielae Gamble) and suggested the invalidation of four other species (F. scabrida T. P. Yi, F. robusta T. P. Yi, F. denudata T. P. Yi F. murielae (Gamble) T. P. Yi, and F. nitida (Mitford) Keng f. ex T. P. Yi). The delimitation of the remaining eight species has yet to be explored. The analysis of ecological factors and spatial autocorrelation suggested that altitudinal differences might account for the distinct genetic divergence between the two major groups.     

丹霞梧桐群体遗传结构及其遗传分化

丹霞梧桐(Firmiana danxiaensis)是分布于我国韶关地区北部丹霞地貌的特有物种, 其分布范围狭窄, 种群数量小。本文利用EST-SSR分子标记位点, 分析丹霞梧桐群体(丹霞山组群和南雄组群)的遗传多样性和遗传结构, 研究群体的分化历史, 探讨该物种的可能分布和科学保护策略。结果表明: 丹霞梧桐总的遗传多样性中等(Ht = 0.631), 群体内遗传多样性较高(Hs = 0.546), 遗传变异主要存在于群体内(79.66%), 但不同地理组群间存在显著的遗传分化(F_ST = 0.150)。长期地理隔离和现代人为干扰是形成丹霞梧桐当前遗传变异模式的主要原因。STRUCTURE分析可将研究群体划分为清晰的两个基因库(gene pool), 其遗传结构与系统发育地理格局之间有密切关系。丹霞梧桐不同地理群体经历了独立的进化路线, 但丹霞山群体的杂合性高, 遗传背景更为复杂。近似贝叶斯运算法(Approximate Bayesian Computation, ABC)分析表明, 丹霞山和南雄地理群体在10万年前由同一个祖先群体分化而来, 分化时有效群体大小分别为7,290和5,550。结合丹霞梧桐的遗传变异和生态位信息, 可推测丹霞梧桐曾广泛分布于南岭地区, 受第四纪第三次亚冰期的影响, 南岭北部的丹霞梧桐群体因气候剧烈变化而灭绝, 仅在南岭南部适宜的环境中得以保存并繁衍至今, 丹霞山和南雄是丹霞梧桐最主要的两个冰期避难所。在全面掌握丹霞梧桐的自然分布, 开展就地保护的基础上, 通过建立种质资源圃、人工种苗扩繁、自然回归试验等措施, 对于该物种的异地保护、种群恢复和开发利用具有重要意义。     

青藏高原岷县龙胆的遗传分化与种群动态历史分析

青藏高原是全球生物多样性中心之一,是研究物种形成和适应性进化的热点地区。岷县龙胆（Gentiana algida var. purdomii）是青藏高原地区特有植物,具有很高的药用价值。本研究以岷县龙胆种群为对象,基于不同遗传方式的分子标记,通过种群遗传结构、遗传分化、种群动态历史和物种分布模型等分析,探讨其在青藏高原的分化历史。结果表明：岷县龙胆具有高的遗传多样性,叶绿体数据表明种内遗传分化程度很高（F_ST=0.452）,但核基因数据表明种内遗传分化程度很低（F_ST=0.022）,揭示岷县龙胆种内存在强烈的基因流。种群动态历史分析表明岷县龙胆种群大小经历了近期扩张,物种分布模型的结果表明岷县龙胆在末次盛冰期以来分布范围略有扩张。分子钟模型的结果表明岷县龙胆种内的遗传分化主要发生在第四纪冰期以来。以上结果一致表明,第四纪气候波动是岷县龙胆分化的主要外部因素。本研究为龙胆属及青藏高原植物类群的物种分化、适应性研究以及资源开发与保护提供了参考。     

Evolutionary history of endangered and relict tree species Dipteronia sinensis in response to geological and climatic events in the Qinling Mountains and adjacent areas

Geological and climatic events are considered to profoundly affect the evolution and lineage divergence of plant species. However, the evolutionary histories of tree species that have responded to past geological and climate oscillations in central China''s mountainous areas remain mostly unknown. In this study, we assessed the evolutionary history of the endangered and relict tree species Dipteronia sinensis in the Qinling Mountains (QM) and adjacent areas in East Asia based on variations in the complete chloroplast genomes (cpDNA) and reduced‐genomic scale single nucleotide polymorphisms (SNPs). Population structure and phylogenetic analysis based on the cpDNA variations suggested that D. sinensis could be divided into two intraspecific genetic lineages in the eastern and western sides of the QM (EQM and WQM, respectively) in East Asia. Molecular dating suggested that the intraspecific divergence of D. sinensis occurred approximately 39.2 million years ago during the later Paleogene. It was significantly correlated with the orogeny of the QM, where the formation of this significant geographic barrier in the region may have led to the divergence of independent lineages. Bayesian clustering and demographic analysis showed that intraspecific gene flow was restricted between the EQM and WQM lineages. Isolation‐with‐migration analysis indicated that the two genetic lineages experienced significant demographic expansions after the Pleistocene ice ages. However, the genetic admixture was determined in some populations between the two lineages by the large scale of SNP variations due to DNA incompatibility, the large significant population size, and rapid gene flow of nuclear DNA markers. Our results suggest that two different conservation and management units should be constructed for D. sinensis in the EQM and WQM areas. These findings provide novel insights into the unprecedented effects of tectonic changes and climatic oscillations on lineage divergence and plant population evolution in the QM and adjacent areas in East Asia.     

Differentiation induction of human leukemia cells (HL60) by a combination of 1,25-dihydroxyvitamin D3 and retinoic acid (all trans or 9-cis)

1,25(OH)₂D₃ and two stereoisomers of retinoic acid, all trans and 9-cis retinoic acid, are regulators of cell proliferation and differentiation. The aim of this study was to evaluate the effects of a combination of 1,25(OH)₂D₃ and retinoic acid (all trans or 9-cis) on proliferation and cell differentiation of the human promyelocytic leukemia cell line HL60, and to test the reversibility of the induced differentiation. Cell proliferation was inhibited as expected by 1,25(OH)₂D₃ and all trans retinoic acid alone (IC₅₀ of cell survival was 4 × 10⁻⁷ M, 9 × 10⁻⁶ M and 9 × 10⁻⁷ M for 1,25(OH)₂D₃, all trans and 9-cis retinoic acid, respectively). Combination of 1,25(OH)₂D₃ and either form of retinoic acid resulted in a partially additive decrease in cell proliferation. 1,25(OH)₂D₃ induced a monocytic differentiation (100% CD14+ cells with 10⁻⁷ M 1,25(OH)₂D₃), while retinoic acid led to a predominantly granulocytic differentiation (36 and 42% CD67+ cells with 10⁻⁶ M all trans and 9-cis retinoic acid, respectively). Additive effects on differentiation were observed upon combination of subtherapeutical doses of the drugs, achieving a mainly monocytic population, demonstrating the dominant role of 1,25(OH)₂D₃ in determining the direction of differentiation. The effects on proliferation and differentiation of the solitary drugs were reversible, while the proliferation arrest and differentiation induced by the combination persisted and even progressed after withdrawal of the drugs. We conclude that 1,25(OH)₂D₃ and retinoic acid (all trans or 9-cis) exert additive effects on inhibition of proliferation and induction of cell differentiation of HL60 cells, leading to a persistent differentiation, even after drug withdrawal.     

Intraspecific differentiation of Allium wallichii (Amaryllidaceae) inferred from chloroplast DNA and internal transcribed spacer fragments

In the present study, we used two chloroplast DNA (cpDNA) fragments (trnL-F and rps16) and the nuclear ribosomal internal transcribed spacer (ITS) sequence data to examine intraspecific differentiation and phylogeographical history of Allium wallichii. Based on wide scale sampling (28 populations and 174 individuals) across the entire distribution range of this species, 33 cpDNA haplotypes and 25 ITS ribotypes were detected in our investigation. These cpDNA haplotypes were divided into three major lineages, which was further supported by the ITS phylogenetic results. High haplotype/ribotype diversity and population differentiation, together with most of the haplotypes/ribotypes being exclusive to single populations, implied restricted gene flow among populations and significant geographical isolation. Nearly all populations with high haplotype/ribotype diversity were found in the Hengduan Mountain Region (HMR), whereas the populations of the Himalayas and Nanling Mountains showed a lower level, suggesting the HMR might serve as a potential divergence center for A. wallichii. The main lineages of A. wallichii diverged from each other between Mid–Late Pliocene and Early Quaternary based on two sets of molecular markers, indicating that the Quaternary climatic fluctuation could not have contributed greatly to the divergence of the main lineages of A. wallichii. Instead, the intricate topography and heterogeneous habitats resulting from the drastic uplift of the Qinghai–Tibet Plateau from the Late Pliocene could be responsible for the intraspecific differentiation of A. wallichii. The present study further highlights the importance of geographic isolation and habitat heterogeneity in shaping and maintaining high species diversity within the HMR.     

Vitamin D: A modulator of cell proliferation and differentiation

1,25-Dihydroxyvitamin D₃, [1,25(OH)₂D₃], the biologically most active metabolite of vitamin D₃, is involved in the regulation of calcium homeostasis and bone metabolism. Recently, receptors for 1,25(OH)₂D₃ have also been shown in cells and tissues not directly related to calcium homeostasis. Experimental data obtained with leukemic and cancer cell lines, both in vitro and in vivo, showed the effects of 1,25(OH)₂D₃ on cell differentiation and proliferation. However, high doses of the sterol have to be used to observe these effects. Additional studies are needed to establish whether 1,25(OH)₂D₃ or suitable analogues have a therapeutic potential in malignant diseases without unacceptable toxicity like the development of hypercalcemia.     

极小种群濒危植物广西火桐、丹霞梧桐的叶绿体基因组特征

广西火桐(Firmiana kwangsiensis)和丹霞梧桐(F. danxiaensis)是我国南方特有物种, 其分布范围狭窄, 种群数量少。为了解其叶绿体基因组结构及系统发生关系, 本文通过高通量测序方法获得广西火桐和丹霞梧桐的浅层基因组数据, 通过生物信息学方法对叶绿体全基因组进行组装, 并对其结构特征进行分析。结果表明: 广西火桐和丹霞梧桐的叶绿体基因组大小分别为160,836 bp和161,253 bp, 具有典型被子植物叶绿体基因组环状四分体结构, 包含长度分别为89,700 bp、90,142 bp的大单拷贝区(large single copy, LSC), 长度分别为19,970 bp、20,067 bp的小单拷贝区(small single copy, SSC)及长度分别为25,583 bp、25,522 bp的2个反向重复序列区(inverted repeat sequence, IR)。两个物种的叶绿体基因组共注释得到131个基因, 包括86个蛋白编码基因、37个tRNA基因和8个rRNA基因。广西火桐的叶绿体基因组中共检测出26个正向重复序列、2个反向重复序列、21个回文重复序列、21个串联重复序列和98个简单重复序列; 丹霞梧桐叶绿体基因组中共检测出23个正向重复序列、5个反向重复序列、21个回文重复序列、30个串联重复序列和107个简单重复序列。系统发生分析结果表明5种梧桐属(Firmiana)植物构成两个强烈支持的分支(支持率100%), 一个分支为广西火桐、美丽火桐(F. pulcherrima)和火桐(F. colorata), 其中广西火桐与美丽火桐构成姐妹群; 另一分支是互为姐妹群的丹霞梧桐和云南梧桐(F. major)。综上所述, 广西火桐和丹霞梧桐的叶绿体基因组结构、基因排列及重复序列具有较高的相似性, 系统进化树将5种梧桐属物种分为两个分支, 其中广西火桐和美丽火桐最近; 而丹霞梧桐与云南梧桐关系最近。本研究鉴定的SSR位点可为梧桐属物种系统发生、进化关系的研究提供遗传信息。     

珍稀濒危植物阜康阿魏的遗传多样性及遗传结构

明确珍稀濒危小种群阜康阿魏(Ferula fukanensis)的遗传多样性和遗传结构,是对其制定有效的保护和管理策略的基础和前提。本研究基于10对多态性好且可以稳定扩增的SSR引物对来源于3个居群87个珍稀濒危植物阜康阿魏的遗传多样性和遗传结构进行分析。结果显示：小种群的阜康阿魏具有相对较高的遗传多样性,居群间Nei’s基因多样性指数(h_S)为0.514,总的Nei’s基因多样性指数(h_T)为0.516,观测杂合度(H_o)为0.881,期望杂合度(H_e)为0.512,香农信息指数(I)为0.836,多态位点百分率(P_PB)为100%,遗传分化程度较低(F_st=0.007),95.9%的变异发生在居群内,遗传距离与地理距离无显著相关性,66.7%的居群遭遇了遗传瓶颈。结果表明,阜康阿魏遗传变异丰富,有较高的进化潜力。结合该种野外种群现状,建议建立保护区,开展就地保护,并加强引种和人工繁育等迁地保护措施,辅助阜康阿魏保育。本研究可为阜康阿魏植物资源保护提供理...     

Limiting steps in Photosystem II and water decomposition in Chlorella and spinach chloroplasts

1. 1. By varying the redox potential of a chloroplast suspension, we obtained new evidence for an equilibrium between states S₀ and S₁ in the model of Kok, B., Forbush, B. and McGloin, N. (1970, Photochem. Photobiol. 11, 457–475). The mid-point potential of the S₀ to S₁ couple is close to that for the pool of the electron acceptor of System II, A to A⁻.

2. 2. The limiting steps between two consecutive photoreactions of System II in Chlorella and spinach chloroplasts, have been studied.

2.1. (a) The limiting step from S₁ to S₂ (noted γ₁ (Δt)) is not exponential. Its temperature coefficient becomes greater as the reaction proceeds. The shape of the kinetics is an intrinsic property of each center. Chloroplasts fixed with 2% glutaraldehyde, show simple first order kinetics.

2.2. (b) The limiting step from S₀ to S₁ (γ₀ (Δt)) exhibits the same characteristics as γ₁ (Δt)).

2.3. (c) The limiting step from S₂ to S₃ (γ₂ (Δt)) shows sigmoidal kinetics; two reactions are involved. One of the reactions exhibits the same properties as γ₀ (Δt) and γ₁ (Δt).

2.4. (d) The limiting step from S₃ to S₀ (γ₃ (Δt)) is a first order reaction, two times slower than the other transitions. This reaction is interpretated in terms of oxygen release.

3. 3. We also studied the limiting steps in the presence of low concentrations (50 μM) of hydroxylamine. The results favor the binding of two molecules of hydroxylamine to every photochemical center.

Diplatinum(III) complexes with bridging 1-methylcytosinate ligands and variable axial ligands, including guanine nucleobases

A series of diplatinum(III) complexes derived from cis-(NH₃)₂Pt^II and the model nucleobase 1-methylcytosine (1-MeC) has been prepared and X-ray structurally characterized, all of which contain two anionic base ligands (1-MeC⁻) in a head–tail (ht) arrangement: ht-cis-[(ONO₂)(NH₃)₂Pt(1-MeC⁻-N3,N4)₂Pt(NH₃)₂(ONO₂)](NO₃)₂·HNO₃·3H₂O (2b), ht-cis-[(NO₂) (NH₃)₂ Pt(1-MeC⁻-N3,N4)₂Pt(NH₃)₂(OH₂)](ClO₄)₃·3.5H₂O (3), ht-cis-[(OH₂)(NH₃)₂Pt(1-MeC⁻-N3,N4)₂Pt(NH₃)₂(OH₂)](ClO₄)₄·H₂O (4b), and ht-cis-[(9-EtGH-N7)(NH₃)₂Pt(1-MeC⁻-N3,N4)₂Pt (NH₃)₂(9-EtGH-N7)](NO₃)₄·9H₂O (7b) (9-EtGH=9-ethylguanine). Several other compounds, differing in the nature of the axial ligands, have been isolated and or observed in solution by ¹H and ¹⁹⁵Pt NMR spectroscopy. The chemistry of these diplatinum(III) compounds is dominated by facile substitution reactions of the axial ligands. Of particular interest in this context is the ready reaction of 2b or 3 with guanine nucleobases. Since similar compounds are not obtained with any of the other common nucleobases, 2b and 3 can be considered guanine-specific chemical probes.     

Molecular structures and some properties of tris(2-aminoethyl) amine cobalt(III) complexes with thiocarboxylato-O,S such as 3-mercaptopropionato, 2-mercaptoacetato and their derivatives

Cobalt(III) complexes with a thiolate or thioether ligand, t-[Co(mp)(tren)]⁺ (2), t-[Co(mtp)(tren)]²⁺ (1Me) and t-[Co(mta)(tren)]²⁺ (2Me), (mp = 3-mercaptopropionate, MA = 3-(methylthio)propionate and MTA = 2-(methylthio)acetate) have been prepared in aqueous solutions. The crystal structures of 1, 2, 1Me and 2Me were determined by X-ray diffraction methods. The crystal data are as follows, t-[Co(mp)(tren)]ClO₄ (1CIO₄): monoclinic, P2₁/n, A = 10.877(8), B = 11.570(4), c = 12.173(7) Å, β = 92.20(5)°, V = 1531(1) ų, Z = 4 and R = 0.060; t-[Co(ma)(tren)]Cl·3H₂O (2Cl·3H₂O): monoclinic, P2₁/n, a = 7.7688(8), B = 27.128(2), C = 7.858(1) Å, β = 100.63(1)°, V = 1627.7(3) ų, Z = 4 and R = 0.066; (+)₄₆₅^CD-t-[Co(mtp)(tren)](ClO₄)₂ ((+)₄₆₅^CD-1Me(ClO₄)₂): orthorhombic, P2₁2₁2₁, A = 10.6610(7), B = 11.746(1), C = 15.555(1) Å, V = 1947.9(3) ų, Z = 4 and R = 0.068; (+)₄₆₅^CD-t-[Co(mta)(tren)](ClO₄)₂ ((+)₄₆₅^CD-2Me(ClO₄)₂): orthorhombic, P2₁2₁2₁, a = 10.564(1), B = 11.375(1), C = 15.434(2) Å, V = 1854.7(4) ų, Z = 4 and R = 0.047. All central Co(III) atoms have approximately octahedral geometry, coordinated by four N, one O, and one S atoms. All of the complexes are only isomer, of which the sulfur atom in the didentate-O,S ligands are located at the trans position to the tertiary amine nitrogen atom of tren. 1 and 1Me contain six-membered chelate ring, and 2 and 2Me do five-membered chelate ring in the didentate ligand. The chirality of the asymmetric sulfur donor atom in (+)₄₆₅^CD-1Me is the S configuration and that in (+)₄₆₅^CD-2Me is the R one. The ¹H NMR, ¹³C NMR and electronic absorption spectral behaviors and electrochemical properties of the present complexes are discussed in relation to their stereochemistries.     

多基因联合揭示海南鲌的遗传结构与遗传多样性

海南鲌(Culter recurviceps)是我国华南地区重要经济鱼类, 由于受到近些年水利开发、过度捕捞、环境污染等诸多因素的影响, 其资源量快速下降, 亟需得到更多的关注和保护。为保护和合理开发海南鲌种质资源, 本研究采集了华南地区23个地理群体207尾海南鲌样本, 测定了2个线粒体基因(Cytb和ND2)并从Barcode of Life Data System数据库获得相对应线粒体COI基因, 结合多种分析方法(系统发育分析、分化时间估算、单倍型网状图、群体遗传分析和Mantel检验)对海南鲌的遗传结构和遗传多样性展开研究。系统发育分析和单倍型网状图表明华南地区海南鲌群体被分成3个谱系(I、II和III), 其中谱系I和III由珠江的群体组成, 谱系II由海南岛的群体组成。分化时间估算发现3个谱系之间的分化时间介于0.028-0.251 Ma之间, 表明华南地区更新世气候变化可能是造成海南鲌谱系分化的重要原因。群体遗传分析发现海南鲌群体之间存在极显著的遗传分化(F_ST = 0.511, P < 0.001), 并且符合距离隔离模式(R = 0.348, P = 0.0010)。群体动态历史分析表明, 海南鲌群体可能在0.010-0.025 Ma经历了群体扩张, 表明更新世的气候波动也影响了海南鲌的群体大小和分布。综上所述, 海南鲌群体由3个谱系组成, 更新世气候变化是导致3个谱系分化和影响海南鲌群体动态历史的重要因素。此外, 海南鲌群体之间的遗传分化也可能受到了空间距离的影响。     

Ruthenium complexes containing tertiary phosphines and imidazole or 2,2′-bipyridine ligands

Complexes RuCl₃(PPh₃)L₂ (L = MeIm (1a, Im (1b)) and [RuCl₂(PPh₃)₂(bipy)]Cl·4H₂O (2) have been synthesized via the ruthenium(III) precursor RuCl₃(PPh₃)₂ (DMA), and characterized, including an X-ray structural analysis for 1a (MeIm = N-methylimidazole, Im = imidazole, bipy = 2,2′-bipyridyl, and DMA = N, N′-dimethylacetamide). Crystals of 1a are monoclinic, space group P2₁/n, A = 10.5491(5), B = 20.4934(9), C = 12.8285(4) Å, β = 90.166(4)°, Z = 4. The structure, which reveals a mer configuration for the chlorides, and cis-methylimidazoles, was solved by conventional heavy atom methods and was refined by full-matrix least-square procedures to R = 0.041 and R_w = 0.042 for 3328 reflections with I 3σ(I). From the RuCl₂(PPh₃)₃ precursor, the ruthenium(II) complexes RuCl₂(PPh₃)₂L₂ and [RuCl(PPh₃)L₄]Cl have been made (L = Im or MeIm), while [RuCl(dppb)Im₃]Cl has been made from [RuCl₂(dppb)]₂(μ-dppb) (dppb = Ph₂P(CH₂)₄PPh₂).     

Stable persistence of relict populations involved evolutionary shifts of reproductive characters in the genus Tanakaea (Saxifragaceae)

Tertiary relicts often show evolutionary stasis in morphology and ecology and have been hypothesized to retain stable population sizes in refugia. However, recent studies have reported that some relicts evolutionarily shifted their physiology, ecology, and morphology and experienced various patterns of demography. To understand the historical survival of relict plants, a multidimensional study investigating the evolution of ecological and morphological traits as well as population demographic history is needed. The genus Tanakaea (Saxifragaceae) comprises two species in China and Japan. These species share most vegetative characteristics and are sometimes treated as a single species. The distribution pattern is relictual, as the populations are confined to small areas in mesic warm temperate forests less influenced by Quaternary glacial climates. Focusing on the relictual plant group, this study tested the hypotheses of evolutionary stasis and population stability in long-term refugia. Genetic analyses using plastome sequences and genome-wide single-nucleotide polymorphisms revealed divergence of the two species approximately 6.8 million years ago and strong genetic differentiation of the regional populations. Demographic analysis revealed that almost all populations retained stable population sizes during glacial–interglacial climate changes, supporting the traditional view. However, morphological assessments revealed a simultaneous shift in breeding systems (from hermaphrodite to dioecy/non-clonal to clonal reproduction) in Japanese species and intraspecific differentiation of leaf traits. Therefore, the relict species do not show evolutionary stasis in every aspect. Changes in reproductive characteristics may have contributed to their long-term in situ survival.     

Structural determinations, magnetic and EPR studies of complexes involving the Cr(OH)2Cr unit

Five heterometallic compounds with formulae [Ba(H₂O)₄Cr₂(μ-OH)₂(nta)₂] · 3H₂O (I), [M(bpy)₂(H₂O)₂] [Cr₂(OH)₂(nta)₂] · 7H₂O, where M²⁺ = Zn, (II); Ni, (III); Co, (IV) and [Mn(H₂O)₃(bpy)Cr₂(OH)₂(nta)₂] · (bpy) · 5H₂O (V); bpy = 2,2′-bipyridine, (nta = nitrilotriacetate ion) have been prepared by reaction of I with the corresponding M^II-sulfates in the presence of 2,2′-bipyridine. Substances I–V have been characterized by magnetic susceptibility measurements, EPR and X-ray determinations. I represents a 2D coordination polymer formed by coordination of centrosymmetrical dimeric chromium(III) units and Barium cations. The 10-coordinate Ba polyhedron is completed by four water molecules. Compounds II–IV are isostructural and consist of non-centrosymmetric dimeric anions [Cr₂(μ-OH)₂(nta)₂]²⁻, complex cations [M^II(bpy)₂(H₂O)₂]²⁺ and solvate water molecules. The octahedral coordination of chromium atoms implies four donor atoms of the nta³⁻ ligands and two bridging OH groups. Multiple hydrogen bonds of coordinated and solvate water molecules link anions and cations in a 3D network. A similar [Cr₂(μ-OH)₂(nta)₂]²⁻ unit is found in V. The bridging function is performed by a carboxylate oxygen atom of the nta ligand that leads to the formation of a trinuclear complex [Mn(bpy)(H₂O)₂Cr₂(μ-OH)₂(nta)₂]. Experimental and calculated frequency and temperature dependences of EPR spectra of these compounds are presented. The fine structure appearing on the EPR spectra of compound V is analyzed in detail at different temperatures. It is established that the main part of the EPR signals is due to the transitions in the spin states of a spin multiplet with S = 2. Analyses of experimental and calculated spectra confirm the absence of interaction between metal ions (M^II) and Cr-dimers in complexes III and IV and the presence of weak Mn–Cr interactions in V. The temperature dependence of magnetic susceptibilities for I–V was fitted on the basis of the expression derived from isotropic Hamiltonian including a bi-quadratic exchange term.