Chromosomal in situ hybridization of Cyprinus carpio genomic DNA repetitive sequence CR1

Common carp Cyprinus carpio genomic DNA repetitive sequence CR1 has been DIG-labeled and hybridized in situ against chromosomes of red common carp (Cyprinus carpio L. Xingguo red var.). It is found that the repetitive sequence CR1 is mainly localized at the centromeric regions of chromosomes of the red common carp, The application of the chromosomal in situ hybridization technique on fish and the relationship between CR1 repetitive sequence distribution and its function have been discussed.

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.

The effect of electric field maximum on the Rabi flopping and generated higher frequency spectra

We investigate the effect of the electric field maximum on the Rabi flopping and the generated higher frequency spectra properties by solving Maxwell-Bloch equations without invoking any standard approximations. It is found that the maximum of the electric field will lead to carrier-wave Rabi flopping (CWRF) through reversion dynamics which will be more evident when the applied field enters the sub-one-cycle regime. Therefore, under the interaction of sub-one-cycle pulses, the Rabi flopping follows the transient electric field tightly through the oscillation and reversion dynamics, which is in contrast to the conventional envelope Rabi flopping. Complete or incomplete population inversion can be realized through the control of the carrier-envelope phase (CEP). Furthermore, the generated higher frequency spectra will be changed from distinct to continuous or irregular with the variation of the CEP. Our results demonstrate that due to the evident maximum behavior of the electric field, pulses with different CEP give rise to different CWRFs, and then different degree of interferences lead to different higher frequency spectral features.

半导体量子阱中传播效应对子带间拉比振荡的影响

通过求解麦克斯韦-布洛赫方程组，分别在存在传播效应和无传播效应两种情况下，研究了调制掺杂的半导体量子阱中子带间的拉比振荡。研究发现，与电子-电子之间的相互作用的非线性相比较，传播效应对拉比振荡的影响更大；在不考虑传播效应时，脉冲可以使量子阱中的电子实现一次完整的布居反转，但是当传播效应存在情况下，完全的粒子数反转已不能实现。另外，研究还发现通过改变载流子的密度可以改变传播效应所产生的影响。

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.