Comparative cytogenetics of bats (Chiroptera): The prevalence of Robertsonian translocations limits the power of chromosomal characters in resolving interfamily phylogenetic relationships

Although the monophyly of Chiroptera is well supported by many independent studies, higher-level systematics, e.g. the monophyly of microbats, remains disputed by morphological and molecular studies. Chromosomal rearrangements, as one type of rare genomic changes, have become increasingly popular in phylogenetic studies as alternatives to molecular and other morphological characters. Here, the representatives of families Megadermatidae and Emballonuridae are studied by comparative chromosome painting for the first time. The results have been integrated into published comparative maps, providing an opportunity to assess genome-wide chromosomal homologies between the representatives of eight bat families. Our results further substantiate the wide occurrence of Robertsonian translocations in bats, with the possible involvement of whole-arm reciprocal translocations (WARTs). In order to search for valid cytogenetic signature(s) for each family and superfamily, evolutionary chromosomal rearrangements identified by chromosomal painting and/or banding comparison are subjected to two independent analyses: (1) a cladistic analysis using parsimony and (2) the mapping of these chromosomal changes onto the molecularly defined phylogenetic tree available fromthe literature. Both analyses clearly indicate the prevalence of homoplasic events that reduce the reliability of chromosomal characters for resolving interfamily relationships in bats.

Chromosomal aberrations induced by C-12(6+) ions and Co-60 gamma-rays in mouse immature oocytes

The ovaries of Kun-Ming strain mice (3 weeks) were irradiated with different doses of C-12(6+) ion or Co-60 gamma-ray. Chromosomal aberrations were analyzed in metaphase II oocytes at 7 weeks after irradiation. The relative biological effectiveness (RBE) of C C-12(6+) ion was calculated with respect to Co-60 gamma-ray for the induction of chromosornal aberrations. The C-12(6+) ion and Co-60 gamma-ray dose-response relationships for chromosomal aberrations were plotted by linear quadratic models. The data showed that there was a dose-related increase in frequency of chromosomal aberrations in all the treated groups compared to controls. The RBE values for C-12(6+) ions relative to (CO)-C-60 gamma-rays were 2.49, 2.29, 1.57, 1.42 or 1.32 for the doses of 0.5, 1.0, 2.07 4.0 or 6.0 Gy, respectively. Moreover, a different distribution of the various types of aberrations has been found for C-12(6+) ion and Co-60 gamma-ray irradiations. The dose-response relationships for C-12(6+) ion and (CO)-C-60 gamma-ray exhibited positive correlations. The results from the present study may be helpful for assessing genetic damage following exposure of immature oocytes to ionizing radiation.

The level and distribution of chromosomal aberration of tomato seeds at different penetration depths of carbon ions

The relationship between the penetration depth and the level and distribution of chromosomal aberration of the root tip cells were investigated by exposure of the superposed tomato seeds to 80 MeV/u carbon ions. The results showed that on the entrance of the beam the chromosomal aberration level was low. Damage such as breaks and gaps were dominant. At the Bragg peak, the chromosomal aberration level was high. The yields of dicentrics, rings and disintegrated small chromosomes increased but the yields of breaks and gaps decreased. These results are consistent with the distribution of the physical depth dose pro. le of carbon ions. It is effective to deposit the Bragg peak on the seeds to induce hereditary aberration in the mutation breeding with heavy ions.

Chromosomal localization and molecular marker development of the lipopolysaccharide and beta-1,3-glucan binding protein gene in the Zhikong scallop Chlamys farreri (Jones et Preston) (Pectinoida, Pectinidae)

Zhikong scallop Chlamys farreri(Jones et Preston) is an economically important species in China. Understanding its immune system would be of great help in controlling diseases. In the present study, an important immunity-related gene, the Lipopolysaccharide and Beta-1,3-glucan Binding Protein (LGBP) gene, was located on C. farreri chromosomes by mapping several lgbp-containing BAC clones through fluorescence in situ hybridization (FISH). Through the localization of various BAC clones, it was shown that only one locus of this gene existed in the genome of C. farreri, and that this was located on the long arm of a pair of homologous chromosomes. Molecular markers, consisting of eight single nucleotide polymorphism (SNPs) markers and one insertion-deletion (indel), were developed from the LGBP gene. Indel marker testing in an F1 family revealed slightly distorted segregation (p = 0.0472). These markers can be used to map the LGBP gene to the linkage map and assign the linkage group to the corresponding chromosome. Segregation distortion of the indel marker indicated genes with deleterious alleles might exist in the surrounding region of the LGBP gene.

Chromosomal mapping of 5S ribosomal RNA genes in the eastern oyster, Crassostrea virginica gmelin by fluorescence in situ hybridization

Chromosomal location of the 5S ribosomal RNA gene was studied in the eastern oyster, Crassostrea virginica Gmelin. using fluorescence in situ hybridization (FISH). Metaphase chromosomes were obtained from early embryos, and the FISH probe was made by PCR (polymerase chain reaction) amplification of the 5S rRNA gene and labeled by incorporation of digoxigenin-1 1-dUTP during PCR. Hybridization was detected with fluorescein-labeled antidigoxigenin antibodies. Two pairs of FISH signals were observed on metaphase chromosomes. Karyotypic analysis showed that the 5S rRNA gene cluster is interstitially located on short arms of chromosomes 5 and 6. On chromosome 5, the 5S rRNA genes were located immediately next to the centromere, whereas on chromosome 6, they were located approximately half way between the telomere and the centromere. Chromosomes of C. virginica are difficult to identify because of their similarities in size and arm ratio, and the chromosomal location of 5S rRNA genes provides unambiguous identification of chromosomes 5 and 6. Previous studies have mapped the major rRNA gene cluster (18S-5.8S-28S) to chromosome 2. and this study shows that the 5S rRNA gene cluster is not linked to the major rRNA genes and duplicated during evolution.

Chromosomal rearrangement in Pectinidae revealed by rRNA loci and implications for bivalve evolution

Karyotype and chromosomal localization of major (18-5.8-28S) and minor (5S) ribosomal RNA genes were studied in two species of Pectinidae, zhikong (Chlamys farreri) and bay (Argopecten irradians irradians) scallops. using fluorescence in situ hybridization (FISH). C. farreri had a haploid number of 19 with a karyotype of 3m + 4sm + 7sm-st + 4st + 1st-t, and A. i. irradians had a haploid number of 16 with a karyotype of 5st + 11t. In C. farreri, the major and minor rRNA genes had one locus each and were mapped to the same chromosome-Chromosome 5. In A. i. irradians, the major rRNA genes had two loci, located on Chromosomes 4 and 8, and the 5S rRNA gene was found at a third chromosome-Chromosome 10. Results of this and other studies indicate that karyotype of A. i. irradians (n = 16, 21 arms) is secondary and derived from an ancestral karyotype similar to that of C. farreri (n = 19, 38 arms) through considerable chromosomal loss and rearrangements. The ability to tolerate significant chromosomal loss suggests that the modal karyotype of Pectinidae and possibly other bivalves with a haploid number of 19 is likely tetraploid; i.e., at least one genome duplication has occurred during the evolution of Bivalvia.

Chromosomal mapping of major ribosomal rRNA genes in the hard clam (Mercenaria mercenaria) using fluorescence in situ hybridization

Karyotype and chromosomal location of the major ribosomal RNA genes were studied in the hard clam (Mercenaria mercenaria Linnaeus) using fluorescence in situ hybridization (FISH). Metaphase chromosomes were obtained from early embryos. Internal transcribed spacers (ITS) between major RNA genes were amplified and used as FISH probes. The probes were labeled with digoxigenin-11-dUTP by polymerase chain reaction and detected with fluorescein-labeled anti-digoxigenin antibodies. FISH with the ITS probes produced two to four signals per nucleus or metaphase. M. mercenaria had a haploid number of 19 chromosomes with a karyotype of seven metacentric, four metacentric or submetacentric, seven submetacentric, and one submetacentric or subtelocentric chromosomes (7M + 4M/SM + 7SM + 1SM/ST). Two ITS loci were observed: one located near the centromere on the long arm of Chromosome 10 and the other at the telomere of the short arm of Chromosome 12. FISH signals on Chromosome 10 are strong and consistent, while signals on Chromosome 12 are variable. This study provides the first karyotype and chromosomal assignment of the major RNA genes in M. mercenaria. Similar studies in a wide range of species are needed to understand the role of chromosomal changes in bivalve evolution.

Chromosomal mapping of the major ribosomal RNA genes in the dwarf surfclam (Mulinia lateralis Say)

Chromosomal location of the major ribosomal RNA genes (rRNA) were studied in the dwarf surfclam (Mulinia lateralis, Say) using fluorescence in situ hybridization (FISH). FISH probes for the rRNA genes were made by polymerase chain reaction (PCR), labeled with digoxigenin-11-dUTP and detected with fluorescein-labeled antidigoxigenin antibodies. Mulinia lateralis had a diploid number of 38 chromosomes and all chromosomes were telocentric. FISH with the rRNA probe produced positive and consistent signals on two pairs of chromosomes: Chromosome 15 with a relative length of 4.6% and Chromosome 19, the shortest chromosome. Both loci were telomeric. The rRNA location provides the first physical landmark of the M. lateralis genome.

Telomerase Activity and Microgravity-Dependent Apoptosis in Human Leukemia HL-60 Cells

Mammalian cells subjected to conditions of spaceflight and the microgravity environment ofspace; manifest a number of alterations in structure and function. Among the most notable changes incells flown on the Space Shuttle are reduced growth activation and decline in growth rate in the totalpopulation. Other changes include chromosomal aberrations, inhibited locomotion, alteredcytokine production, changes in PKC distribution, and increased apoptos.

沿阶草族的染色体研究及系统学问题的探讨

本论文对沿阶草族Ophiopogoneae(Endl.)Kunth的研究历史作了回顾，从染色体、形态学和解剖学角度对此族作了研究，并作了数值分类和分支 系统学分析的尝试，在此基础上探讨了这个族的系统学问题． 1)本论文对此族三属37种123居群的染色体数目、基数及核型不对称性作了研究，其中19种的染色体为首次报道．它们是：P．macrostegiaHance， P.yunnanensis Wang et Tang，P.ophiopogonoides Wang et Tang,O. sarmentosus Wang et Dai,O.tienensis Wang et Tang, O.sylvicola Wang et Tang, O.fooningensis Wang et Dai, O.mairei L6vl.，O.szechuanensis Wang et Tang, O.angustiatus (Wang et Tang) S.C.Chen, O.amblyphyllus Wang et Dai,O.clavatus Wright ex Oliver,O.clivioidesD.M.Zhang et Hong, O.longiscaposus D.M.Zhang et Hong,O.umbraticola Hance,O.fuiD.M.Zhang ntHong,O.zingiberaceus Wang et Dai,O.gangxiensisd.M.Zhang et Hong,O. lo fouense L6vl. 2)在此族中首次报道了2n = 2x = 34的异基数二倍体，同时在O.umbraticola，O.japonicus,O.cLarkei中报道了2n=68的异基数二倍体，过核型和减数分裂等证明异基数是在二倍体水平上形成，并发展成倍性系列的． 3)在此族中首次报道了B染色体的存在，已确证了两种(P.macrostegia和D.tienensis)．一种尚需进一步确证(O.Larkei)． 4)通过对随体位置的系统研究，发现在此族中随体位置具有分类价值． 5)通过对8个种内多倍体、4个多倍体种的研究，表明多倍体分布于较北、海拔较高的地方，而亚洲热带地区的种，则无多倍体，同时在具异基数种类和核型较不对称种类上亦有这种分布特征;在确定了分布的多度中心的基础上，提出喜马拉雅_横断山脉到川西、川南一带是沿阶草属和山麦冬属的近代分化中心． 6)通过染色体结构和数目几个角度的研究，表明球子草属与其他两属在。染色体水平上已发生很大分化，但其属内的分化则不表现在染色体上．其他二属内部则有基数、倍性和核型不对称方面的分化．综观此族，染色体具有由核 型对称向不对称、由二倍体向多倍体、由种内多倍体向多倍体种，由单一基数向种内异基数几个方向进化的趋势． 7)通过对此族的形态观察和分析，提出茎或根状茎分枝方式是属下分类的重要依据;认为本族植物的花序是由圆锥花序简化而来，但残留着圆锥花序特征;并提出了本族花、茎、叶、根几个方面的形态演化趋势． 8)通过对此族二属21种的子房解剖，发现三属均有半下位子房，因而认为子房半下位作为分属检索性状是不合适的．此外还观察到子房着生位置在种内亦有变异，对这种变异的意义进行了探讨． 9)通过此族三属46种2变种的数值分类处理，表明本族由球子草群和沿阶草一山麦冬群两大类群组成，山麦冬属仅是与沿阶草属一个组（葶花组）并列的分类单元，其内部分化较小，而沿阶草属则较大． 10)通过46个性状计算了山麦冬属和沿阶草属共6个广布的“群内总体相 似度”(IOS)，表明山麦冬属3个种种内个体之间、种间个体之间的分化很小，且可能有杂交现象，结合染色体资料和分布特征，认为这个属的发生是个相当晚近的事件． 11)本文从形态和染色体角度，认为沿阶草族是一个自然类群;由分支系 统学分析表明，此族由二个单系类群（球子草属和沿阶草属）组成，沿阶草属含两个单系的组，其中各含3个系，山麦冬属为其中一个系．这一结果与数值 分类结果和染色体资料相符． 12)为避免单一分类方法可能导致的不合理结果，本文以自拟的一种综合分类方法，把谱系、进化、分化诸因素均予考虑，得出一个三维图象，以图象 上相对等径的球作为分类依据，得出的结果与分支系统学和数值分类结果基本一致．因此，山麦冬属作为与沿阶草属等阶的分类地位，应予重新考虑． 13）本文最后对这个族的全面修订提出几点建议. 14）此外，本文还描述了沿阶草属4个新种.

中国华中铁角蕨复合体和铁角蕨复合体几个种的生物系统学研究

本文综合形态学、孢粉学和细胞学以及等位酶分析的实验证据，阐明了中国华中铁角蕨复合体（Asplenium sarelii Hook. Complex）中两个四倍体种的起源问题，并从生物系统学的角度讨论了其中多个种的分类学问题。过去认为的四倍体的“华中铁角蕨”被证明是起源于二倍体华中铁角蕨（A. sarelii Hook.）和二倍体细茎铁角蕨（A. tenuicaule Hayata）的杂交，并被处理为新种：武当铁角蕨（A. wudangense Z.R. Wang et X. Hou, sp. nov.）。 而变异铁角蕨（A. varians Wall., Hook. et Grev.）则被认为起源于二倍体细茎铁角蕨（A. tenuicaule Hayata）和二倍体尖齿铁角蕨（A. argutum Ching）的杂交或二者同源四倍体的杂交。根据原细茎铁角蕨（A. tenuicaule Hayata）和尖齿铁角蕨（A. argutum Ching）在宏观和微观特征上的相似性，以及二者的遗传一致度（0.581～0.705），本文将这两个种处理为细茎铁角蕨（A. tenuicaule Hayata）的两个亚种：细茎亚种(ssp. tenuicaule）和尖齿亚种（ssp. argutum （Ching） Vaine, Rashbach et Reichst., ined.）。依据形态和遗传上的相似性以及各自占有一定部分重叠的分布区域，原云南铁角蕨（A. yunnanense Franch.）、宝兴铁角蕨（A. moupinense Franch.）和云南铁角蕨深裂铁角蕨变种（A. yunnanense Franch. var daraeiforme（Franch.）H. S. Kung）被处理为云南铁角蕨（A. yunnanense Franch.）的三个亚种：云南铁角蕨亚种（ssp. yunnanense）、宝兴铁角蕨亚种（ssp. moupinense （Franch.）Z. R. Wang et X. Hou, st. nov.）和深裂铁角蕨亚种（ssp. daraeiforme（Franch.）Z. R. Wang et X. Hou, st. nov.）。 同时，本文运用孢粉学、细胞学、生态学和形态学的综合手段，处理了中国铁角蕨（Asplenium trichomanes L. s. l.）的种下分类问题，划分了中国该种的四个亚种：原亚种A. trichomanes L. ssp. trichomanes，喜钙亚种A. trichomanes L. ssp. inexpectans Lovis，四倍亚种A. trichomanes L. ssp. quadrivalens D. E. Meyer emend. Lovis，粗轴亚种A. trichomanes L. ssp. pachyrachis （Christ） Lovis et Reichst.，并将一个变种：哈如变种A. trichomanes L. var. harovii Moore emend. Midle，归并入粗轴亚种ssp. pachyrahcis (Christ) Lovis et Reichst.，同时提供了它们在中国的分布情况。查阅研究PE的标本时发现一些定名为为A. trichomanes L. var. centrochinense Christ（中国变种）的模式标本碎片，因在形态上和倍性上均不同于已知分类群，认为应给予种的分类地位。

松属单维管束亚属植物rDNA的染色体定位研究

松属植物的基因组十分庞大（大于20000Mbp），其中约90%是由重复序列组成的，我们对其结构和组成仍知之甚少。松属在系统分类上分为两个亚属:单维管束亚属和双维管束亚属。基因组大小研究发现单维管束亚属植物的基因组更大。rDNA作为一类有功能的多基因家族重复序列，其自身特性决定了它在基因组研究中的重要性。FISH技术为rDNA在染色体上物理定位提供了有力的工具。尽管现在对松属rDNA FISH已有不少报道，但主要集中在双维管束亚属，对单维管束亚属的研究几乎是空白。本研究选择5个单维管束亚属松属植物P. bungeana, P. koraiensis, P. armandii, P. wallichiana, P. strobus，进行rDNA FISH研究。旨在弄清18S-25S rDNA和5S rDNA在单维管束亚属植物染色体上的位点数目和分布模式。结合前人对松属双维管束亚属植物的工作，对单、双维管束亚属植物之间rDNA FISH结果进行比较，从而可以从整体上认识松属植物的18S-25S rDNA和5S rDNA在染色体上的分布式样。在此基础上进一步探讨18S-25S rDNA和5S rDNA这些重复序列在松属植物基因组结构和组成中的地位和作用。本研究主要结果如下： 1.rDNA FISH在松属染色体核型分析中的作用 本研究中5种松属单维管束亚属植物染色体数目均为2n=24，除最短一条染色体为亚中部着丝粒染色体外，其余11条均为中部着丝粒染色体，长度和臂比也十分接近，同源染色体的不容易鉴定，很难排出精确的核型。在我们的研究结果中，5个松属植物中，除了白皮松外，18S-25S rDNA和5S rDNA分布在12对染色体中的10对染色体上，这些位点可作为染色体标记，大大提高了同源染色体鉴定的准确度，但是染色体之间排序问题依然没有很好地解决。核型比较认为种间是否存在部分同源染色体关系也不是十分明确，仅Ⅺ号和Ⅻ号染色体有这种关系，这主要由于Ⅺ号和Ⅻ号染色体容易准确地鉴别出来。核型分析的精确仍有待增加标记来提高。 2．rDNA位点数目在松属两个亚属间的比较及其与基因组大小的关系 松属植物18S-25S rDNA位点通常为5-10个，5S rDNA位点为1-4个。其中单维管束亚属18S-25S rDNA位点通常为9-10个（除白皮松为4个外），5S rDNA位点为2- 4个;双维管束亚属为18S-25S rDNA位点通常为5-10个，5S rDNA位点通常为1-2个。而二倍体被子植物18S-25S rDNA位点通常为1-5个5S rDNA位点为1-3个。暗示18S-25S rDNA和5S rDNA位点数目多少和基因组大小还是有一定的相关性。因为松属植物的基因组比典型的二倍体被子植物大得多，单维管束亚属植物的的C-值又普遍比双维管束亚属植物的高。白皮松虽有些例外，18S-25S rDNA位点数目少，但信号强度大得多，代表拷贝数高，因此其基因组大小可以从rDNA拷贝数上得到解释。 3．18S-25S rDNA和5S rDNA位点在松属两个亚属之间的分布模式比较 18S-25S rDNA和5S rDNA位点在松属两个亚属染色体上的分布方式有明显不同，每个亚属均有两种分布形式，并形成各自稳定的分布模式。在单维管束植物中，18S-25S rDNA和5S rDNA位点或相邻分布于同一染色体同一臂上，5S rDNA位于臂的远端;或两位点分布于不同的染色体。而在双维管束植物中18S-25S rDNA和5S rDNA或相邻分布于同一染色体同一臂上，18S-25S rDNA在臂的远端;或两位点分布于同一染色体两条臂上。在两个亚属中，当18S-25S rDNA和5S rDNA位点位于同一条染色体臂上时，相对位置正好相反。这完全不同的rDNA分布模式的形成，可能与松属这两个亚属植物的物种形成和分化过程中染色体发生倒位或易位有关，暗示这两个亚属的基因组结构存在分化。但这各自的分布模式是否可以作为判断亚属的特征依据仍有待加大样本量证实。 4．rDNA 位点分布及变异具有系统学意义 rDNA FISH 结果符合分类中亲缘关系越近，分布模式越相似的原则，因而认为rDNA 位点在染色体上的分布模式，具有系统学意义。基于已知的松属植物rDNA FISH结果构建的系统关系，符合传统分类系统中对亚组划分。rDNA FISH结果与分子系统学的研究结果相比较认为，松属单维管亚属5种松中，以乔松和北美乔松关系最近，与同一个亚组的华山松稍远，与另一个亚组的红松更远。而白皮松作为一个特有的孑遗类群，系统位置比较特殊，分子系统学研究认为其处于基部的位置，本研究表明其rDNA位点有明显的特点：位点数目少，但信号强，反映了拷贝数多。那是否它就代表了祖先类群的位点分布模式，需要更多的基部类群的rDNA FISH结果支持。

芍药属两物种染色体结构变异杂合性研究

芍药属由大约35个灌木和多年生草本种组成，分为三个组：牡丹组(Sect. Moutan)、北美芍药组(Sect. Onaepia)和芍药组(Sect. Paeonia)。四川牡丹(Paeonia decomposita Handel-Mazzetti)和块根芍药(P. intermedia Meyer)分别隶属于牡丹组和芍药组。在该属的所有种中，染色体基数均为 x = 5，最短的五号染色体是端部着丝粒染色体，很容易辨认。 本论文研究了块根芍药三个居群22个个体和四川牡丹两个居群13个个体的减数分裂。减数分裂异常广泛发生，以至于发现所有被研究的个体都有数量不等的桥、断片和单价体。结果表明在中期I，块根芍药第一个居群平均每个小孢子母细胞有2.17个棒状二价体和2.7个环形二价体，第二个居群平均每个细胞有2.04个棒状二价体和2.86个环形二价体，第三个居群平均每个细胞有2.21个棒状二价体和2.71个环形二价体。而在四川牡丹中，第一个居群平均每个小孢子母细胞有2.09个棒状二价体和2.81个环形二价体，第二个居群平均每个细胞有1.85个棒状二价体和3.08个环形二价体。 块根芍药第一个居群的平均减数分裂染色体构型是2n = 10 = 0.25 I + 4.87 II，第二个居群是2n = 10 = 0.20 I + 4.90 II，第三个居群是2n = 10 = 0.17 I + 4.92 II，在该种的平均构型是2n = 10 = 0.21 I + 4.89 II。四川牡丹第一个居群的平均减数分裂染色体构型是2n = 10 = 0.21 I + 4.90 II，第二个居群是2n = 10 = 0.14 I + 4.93 II，在该种的平均构型是2n = 10 = 0.20 I + 4.90 II。在块根芍药中，不同个体的配对系数变化范围在69.5%和81.07%之间，在四川牡丹中在72.97%和81.37%之间。 在后期I和末期I，出现了染色体桥、断片、落后染色体、不等分离等异常现象。最明显的减数分裂异常是后期I桥/断片。尽管在不同的居群中桥/断片异常出现的频率有所变化(块根芍药居群一是26.03%，居群二是11.67%，居群三是13.39%;四川牡丹居群一是7.59%，居群二是9%)，但是这种异常出现在所有个体中(块根芍药平均为18.67%，四川牡丹平均为7.69%)。结果表明，所有的个体都是染色体臂内倒位结构杂合体，广泛存在于野生自然居群中，可能存在某些选择优势。而且，桥的出现频率和断片的大小在个体之间是变化的，这因此表明在这两个种中存在不同的倒位。然而，这两个种在野生居群中是如何维持染色体结构杂合的，其维持机制还有待于进一步阐明，还需要更进一步的证据。 该研究还揭示了块根芍药和四川牡丹这两个种具有共同的第五号染色体减数分裂异常：与长臂相比，短臂在遗传距离和物理距离之间存在巨大的背离。短臂的遗传距离，通过交叉频率计算出来，约是长臂的三十分之一（块根芍药）。然而，物理距离用臂的比率表示，大约是长臂的三分之一，物理距离是遗传距离的十倍。 在四川牡丹红心桥居群和其它居群之间，臂比存在微小的差异，而且在芍药属不同的种内也发现了存在差异。在四川牡丹中，环形二价体(两个臂形成交叉)和棒状二价体(仅一个臂形成交叉)的比率是1.94 : 98.06，而在块根芍药中是3.42 : 96.58。在这两个种中，棒状二价体大大多于环形二价体。在第五号染色体的短臂上可能存在某些“搭车效应”，这表明第五号染色体的短臂上存在高度永久杂合，导致短臂高度保守、极为稳定。这与芍药属古老的分布格局、进化历史长可能存在某些联系。四川牡丹第五号染色体的后期I倒位桥出现频率非常低，仅为0.51 - 3.47%，平均为1.43%。而且断片长度是变化的，其变化范围在1.7 - 10.8 µm之间。

丁香属（Syringa L.）的分类学修订

丁香属隶属于木犀科，分布于东南欧和东亚至喜马拉雅地区，我国是丁香属的现代分布中心。《中国植物志》（61卷，1992）记录了我国野生丁香种类16种;《Flora of China》（15卷，1996）记录了中国原产丁香种类16种，并认为全世界大约有20种。丁香属属下分类等级划分分歧较大，很多种的划分也存在争议。花叶丁香、四川丁香等种类是根据栽培植物描述的，没有指定模式标本，给分类处理带来了一定困难。另外，丁香属很多分类群的性状变异非常复杂，仅根据有限的标本很难做出合理的分类处理。本研究通过广泛查阅文献和标本，同时进行野外居群取样和性状观察，对各类群的性状在居群内和居群间的变异进行统计学分析，判断其分类价值，并运用多变量分析的方法，为各类群的合理划分提供依据。结合性状分析和地理分布等证据，做出分类处理。 作者查阅了国内外16个标本馆的近2000份标本，其中模式标本约70份。对我国12个省市的40余个居群进行了取样和观察，采集标本500余份，涉及了《中国植物志》61卷收录的除了藏南丁香以外的所有类群。通过对9个复合体的40余个性状在居群内和居群间的变异进行统计分析，发现叶片类型、叶柄长度、花序着生类型、花冠大小、花丝长度、花药颜色在不同类群间差异明显，可以用作划分种的依据;叶片形状、叶片毛被、花序轴毛被、花冠管形状等性状在有些复合体内的居群间呈现连续的变异，只能用作种下等级（亚种）的划分;叶片大小、花序轴形状、花药着生在花冠的位置、蒴果是否被皮孔等性状在不同复合体的居群间呈现间断或连续的变异，视不同情况可以用作种间或种下等级的划分依据，或作种内变异处理;而叶脉、花色、花萼齿裂、花冠裂片形状等性状在居群间差异不大，不适合用作分类依据。 在性状分析和多变量分析的基础上，本文将丁香属划分为2组2系12种13亚种，其中短花冠管组有1种3亚种;长花冠管组的顶生花序系有5种5亚种，侧生花序系有6种5亚种，并指定了各组和系的模式种;编制了属下各组、系、种和亚种划分的检索表，对12种13亚种进行了形态描述、标本引证，给出了地理分布图和生境，并提出了分类处理依据。文中对巧玲花、皱叶丁香、红丁香和云南丁香等复合体内的一些分类群进行了归并，做出4个新组合：S. pubescens ‘Meyer’、S. villosa subsp. wolfii、S. yunnanensis subsp. sweginzowii和S. yunnanensis subsp. tomentella，处理了11个新异名（S. fauriei H. Lév.、S. julianae C. K. Schneid.、S. meyeri var. spontanea M. C. Chang、S. pinetorum W. W. Sm.、S. wardii W. W. Sm.、S. oblata var. donaldii R. B. Clark et J. L. Fiala、S. afghanica C. K. Schneid.、S. protolaciniata P. S. Green et M. C. Chang、S. tibetica P. Y. Bai、S. reflexa C. K. Schneid. 、S. wilsonii C. K. Schneid.）。作者指定了3种4亚种(S. reticulata subsp. reticulata、 S. reticulata subsp. amurensis、S. pubescens subsp. microphylla、S. oblata subsp. dilatata的后选模式，并对其它10个名称指定了后选模式。文中还提出了分类处理原则，对我国丁 香属的分布及各地方植物志的记载进行了评述，并对丁香属的分布格局提出了作者的看法。 作者还对13个分类群的16号材料进行了染色体观察，发现除了毛丁香有染色体2n=48外，其它均为2n=46，其中朝阳丁香的染色体数目为首次报道。对小叶巧玲花不同异名（包括小叶蓝丁香、小叶巧玲花与小叶蓝丁香的杂交种）的材料进行染色体观察时，发现它们之间差异很小，进一步佐证了作者将其合并的合理性。另外野生的花叶丁香（华丁香）与栽培的花叶丁香在染色体数目上也无差异，支持了作者认为二者为同物异名的观点。