黄鳝二价染色体上地高辛配基标记随机引物原位DNA合成的研究

在黄鳝二价染色体上, 运用地高辛配基标记的随机引物原位DNA合成技术诱导出了明暗相间、基本稳定且类似于R带的带状结构。本文对该结果进行了较详细的分析和讨论。 Abstract:The dark bands alternating with light bands,relatively stable and R-band-like structure was showed on the pachytene bivalents of Rics-field eel(Monopterus albus Zuiew)by using the random-primed in situ digoxigenin-labelled DNA synthesis technique,and the results were analysed and discussed in detail.     

黄鳝二价染色体上地高辛配基标记随机引物原位DNA合成的研究

在黄鳝二价染色体上, 运用地高辛配基标记的随机引物原位DNA合成技术诱导出了明暗相间、基本稳定且类似于R带的带状结构。本文对该结果进行了较详细的分析和讨论。 Abstract:The dark bands alternating with light bands,relatively stable and R-band-like structure was showed on the pachytene bivalents of Rics-field eel(Monopterus albus Zuiew)by using the random-primed in situ digoxigenin-labelled DNA synthesis technique,and the results were analysed and discussed in detail.     

一种提高RAPD技术扩增效率的有效方法

RAPD技术是由Williams等于1990年首先创立的一种DNA分子标记技术。但是由于低的退火温度和短的引物序列等原因,常常使得RAPD技术的分辨率和可重复性低。本文介绍一种通过延长从退火到延伸的ramp时间,提高RAPD产物的分辨率和产量,由此提高RAPD技术的扩增效率的有效方法。 Abstract:The random amplified polymorphic DNA(RAPD)is a technique of DNA molecular marker,which was first established by Williams in 1990.The resolution and repetition is low because of the low annealed tempture and short primers in the RAPD.In this paper we introduce an improved method for increasing the efficiency of the technique of RAPD by prolonging the ramp time from annealing to extension and increasing the resolution and production.     

Use of Random Amplified Polymorphic DNA Analysis for Economically Important Food Crops

The objective of this review is to summarize numerous studies on the use of the random amplified polymorphic DNA （RAPD） technique on rice, corn, wheat, sorghum, barley, rye, and oats to examine its feasibility and validity for assessment of genetic variation, population genetics, mapping, linkage and marker assisted selection, phylogenetic analysis, and the detection of somaclonal variation. Also we discuss the advantages and limitations of RAPD. Molecular markers have entered the scene of genetic improvement in different fields of agricultural research. The simplicity of the RAPD technique made it ideal for genetic mapping, plant and animal breeding programs, and DNA fingerprinting, with particular utility in the field of population genetics.     

Study on gene sensor based on primer extension

Based on the fact that the resonant frequency of a piezoelectric crystal is the function of its surface deposit, and that the primer extends after it hybridizes with the template, the primer extension gene sensor technique was developed. The prominent feature of the technique is that fast and sensitive frequency signals are used as the monitoring system of gene hybridization and primer strand extension. Results show that this technique may be used in homologous analysis of nucleic acid, trace DNA detection, and determining the integration of DNA. It may also be used for isolation of target gene, gene mutation analysis, and predicting the location of a gene in its genome.     

家猪减数分裂粗线期二价体与有丝分裂中期染色体的比较研究

以性成熟公猪睾丸和外周血为材料,采用长低渗、高氯仿卡诺固定液固定和外周血细胞培养制备减数分裂粗线期二价体和有丝分裂中期染色体,通过对二价体和有丝分裂中期染色体分裂指数和长度的比较研究,发现二价体的分裂指数和长度分别是有丝分裂中期染色体的5倍和3.42倍(1.87～5.98);同时以12号染色体为例, 比较了二价体上的染色粒结构带与有丝分裂中期染色体G-带,表明染色粒结构带比中期染色体G-带带纹丰富,而与早中期G-带带纹吻合。 Abstract:Meiotic pachytene bivalents were obtained from porcine testes using prolonged hypotonic treatment combined with high chloroform Carnory's fixative solution. Mitotic metaphase chromosomes were prepared from blood cell culture. Comparative studies on division index and length of pachytene bivalents and mitosis metaphase chromosomes showed that those of the former are 5 times higher and 3.42(1.87～5.98) times longer than the latter, respectively. Chromomere maps of bivalents are more abundant than mitotic metaphase G-bands, while they are correspondent with mitotic early-metaphase G-bands. The result was found by using the chromosome 12 as a sample.     

Identification of Random Amplified Polymorphic DNA Markers Linked to Sex Determination in Calamus simplicifolius C. F. Wei.

The random amplified polymorphic DNA （RAPD） molecular marker technique was used to determine the sex of Calamus simplicifolius C. F. Wei In the present study, DNA samples were extracted individually from 10 male and 10 female plants. After a total of 1 040 decamer primers had been tested, an approximate 500-bp male-specific DNA fragment was generated with the S 1443 primer. It is feasible to identify sex at the early stages of plant life, which is beneficial for improving breeding programs of this dioecious species. In addition, we have obtained a proper RAPD protocol that is useful for other species of rattan.     

PCR方法制备地高辛标记DNA探针检测中国对虾非包涵体型杆状病毒

A pair of primers created from information of PmNOBⅢ genome DNA Sal I fragment produced a 355bp band by using Penaeus chinensis non occluded baculovirus (PcNOBV),the WSBV isolate from P.hinensis in mainland China,as the DNA template.The specific PCR product was cloned,sequenced and labeled with digoxigenin (DIG)DNA labeling kit(Boehringer Mannheim).The DIG labeled fragment was tested by dot blot hybridization for sensitivity and specificity with purified PcNOBV nucleocapsid,PcNOBV infected shrimp tissues and healthy shrimp tissues.The detection limit of the DNA probe is 6.8pg of purified PcNOBV DNA.No hybridization signals were observed using DNA from healthy shrimp as template.Healthy P.chinensis,artificially infected P.chinensis and pond reared adult P.chinensis were screened for PcNOBV infection by both PCR and the hybridization assay.The results showed a good relationship between PCR and the hybridization assay.These findings demonstrate that the DIG labeled probe can be used as a sensitive,specific and cost effective reagent for detection of PcNOBV.     

Construction of a DNA library from chromosome 4 of rice （Oryza sativa） by microdissection

A simple method to create a chromosome-specific DNA librqary of rice,including microdissection,amplification,charterization and cloning,is described.Rice chromosome 4 from a metaphase cell has been isolated and amplified by the Linker Adapter PCR (LA-PCR).The PCR products were labeled as probes with DIG-11-dUTP using the random priming method.Southern blot analysis with rice genomic DNA and specific RFLP markers demonstrated that the PCR products were derived from rice chromosome 4.A large library comprising over 100,000 recombinant plasmid microclones from rice chromosome 4 was constructed.Colony hybridization showed that 58% of the clones contained single or low-copy sequences and 42% contained repetitive sequences.The size of inserts generated by PCR ranged from 140bp to 500bp.This method will facilitate cloning of the specific chromosome DNA markers and important genes of rice.     

Colchicine promotes a change in chromosome structure without loss of sister chromatid cohesion in prometaphase I-arrested bivalents

In somatic cells colchicine promotes the arrest of cell division at prometaphase, and chromosomes show a sequential loss of sister chromatid arm and centromere cohesion. In this study we used colchicine to analyse possible changes in chromosome structure and sister chromatid cohesion in prometaphase I-arrested bivalents of the katydid Pycnogaster cucullata. After silver staining we observed that in colchicine-arrested prometaphase I bivalents, and in contrast to what was found in control bivalents, sister kinetochores appeared individualised and sister chromatid axes were completely separated all along their length. However, this change in chromosome structure occurred without loss of sister chromatid arm cohesion. We also employed the MPM-2 monoclonal antibody against mitotic phosphoproteins on control and colchicine-treated spermatocytes. In control metaphase I bivalents this antibody labelled the tightly associated sister kinetochores and the interchromatid domain. By contrast, in colchicine-treated prometaphase I bivalents individualised sister kinetochores appeared labelled, but the interchromatid domain did not show labelling. These results support the notion that MPM-2 phosphoproteins, probably DNA topoisomerase IIalpha, located in the interchromatid domain act as "chromosomal staples" associating sister chromatid axes in metaphase I bivalents. The disappearance of these chromosomal staples would induce a change in chromosome structure, as reflected by the separation of sister kinetochores and sister axes, but without a concomitant loss of sister chromatid cohesion.     

18 μm replication units of chromosomal DNA fibers of differentiated cells of Pea (Pisum sativum)

A technique is presented for investigating possible early terminalisation of chiasmata, based on the analysis of labelling patterns in autoradiographs in X₂-labelled diplotene bivalents. Terminalisation is expected to produce unlabelled gaps in otherwise labelled bivalents which, given even a moderate amount of movement, is capable of resolution by this technique. The method has been evaluated using diplotene spermatocytes of Schistocerca gregaria as a test system. Very few unlabelled gaps were actually observed in X₂-labelled bivalents, in fact no more than in X₁-labelled bivalents, where chiasma terminalisation is not expected to produce gaps. Consequently it is concluded that the gaps observed are due to technical causes and that early terminalisation is an unimportant factor determining chiasma distribution in this system.     

Chromosome-specific desynapsis in the n = 2 race of Haplopappus gracilis (Compositae)

During cytological screening for pollen sterility in a wild population of Haplopappus gracilis (n = 2), several partially sterile plants were found that had good pachytene pairing but varying numbers of univalents. Some plants had chromosome A bivalents or A univalents, while in the same cells chromosome B had only bivalents. In other plants the reverse condition occurred; the B chromosome had B bivalents or B univalents and only A bivalents. This demonstrates a chromosome-specific effect for the desynapsis genes. Hybridization between the two homozygous mutant genotypes produced only normal bivalents; this indicates the two mutants are not alleles and each is recessive. An F2 generation showed independent assortment of the desynaptic mutations. The chromosome A bivalent is the larger of the two and normally has one or two chiasmata; the B bivalent normally has a single chiasma. Chiasmata distribution was tested in the desynaptic mutant A bivalents and showed an acceptable fit to a binomial distribution. This occurs also in heterozygous, asynaptic pairing control gene mutations. Analysis of the NOR bivalent in two hologenomic desynaptic mutations in tomato also showed a good fit to a binomial distribution of chiasmata. This indicates the same methods are applicable to diverse species.     

Complete pachytene chromomere karyotypes of human spermatocyte bivalents

Summary Well-spread human pachytene spermatocyte bivalents were obtained allowing specific identification of each bivalent within its total complement according to its chromomere sequence combined with further staining of its centromeric heterochromatin. The total number of chromomeres was found to be related to the degree of bivalent contraction: 396 in condensed bivalents and 511 in decondensed bivalents. A striking correspondance between chromomeres and mitotic G-bands was observed; on account of the variability of bivalent contraction, condensed bivalents corresponded to prometaphase somatic chromosomes and decondensed bivalents to mid/late prophase chromosomes.     

Induced Bivalent Interlocking and the Course of Meiotic Chromosome Synapsis

WHEN chromosomes pair at meiosis the bivalents so formed do not normally interlock. Heat-treatments can, however, induce bivalent interlocking in the locust Locusta migratoria. Only the longest bivalents interlock and usually only two are found per cell; two “rod” bivalents, with single chiasmata, two “ring” bivalents, each with two or three chiasmata, or one “rod” and one “ring” bivalent (Fig. 1a, b and c). The nature of this interlocking and the metaphase orientational and congressional properties of interlocked bivalents are analysed in detail elsewhere¹.     

Pachytene chromosomes in male and female mice heterozygous for the Is(7;1)40H insertion

Pairing of pachytene chromosomes was studied in oocytes and spermatocytes of mice heterozygous for the male-sterile Is(7;1)40H insertion using light and electron microscopy for synaptonemal complex analysis in surface-spread, silver-stained preparations. The data comprised four males and four female embryos. The insertion/deletion configurations appeared as either two bivalents or one quadrivalent in both sexes, but the proportion of bivalents was higher in oocytes. Some insertion and deletion bivalents showed synaptic adjustment. The insertion/deletion configurations were associated with, or adjacent to, the XY bivalent in the majority of spermatocytes. End-to-end association of different bivalents was more frequent in oocytes than in spermatocytes. It is suggested that physiological differences between male and female gametocytes may lead to the difference in their reproductive potential.The authors warmly dedicate this paper to the Founder and Senior Editor of Chromosoma, Professor Hans Bauer, on the occasion of his 80th birthday.     

THE QUESTION OF POST-REDUCTION IN SPHAGNUM

The 19 spatially distinct chromosomal units at first meiotic metaphase in sporophytically diploid species of Sphagnum have usually been considered to be bivalents, but one investigator (Sorsa, 1956) has interpreted them as chromosomes from dissociated bivalents and meiosis as post-reductional. The present studies on diploid S. squarrosum (Pers.) Crome establish the chromosome number on the basis of the following evidence: there are in addition to m-chromosomes, 19 pairs of chromosomes in early prophase, 19 bivalents at diakinesis, 19 chromosomes in each of the two sets at second metaphase, 19 daughter chromosomes in each of the four sets at late second anaphase, and 19 chromosomes in gametophytic mitoses. The 19 bodies at first meiotic metaphase in diploid species are true bivalents in loose secondary association, which has led to their erroneous interpretation as chromosomes of dissociated bivalents. The gametic chromosome number in sporophytically diploid Sphagnum is therefore, without doubt, n = 19, and this evidence negates the claim for post-reduction in Sphagnum.     

Genetic induction of bivalent interlocking in common wheat

The frequency of interlocking bivalents at first meiotic metaphase of common wheat Triticum aestivum L., which is normally very low, is significantly increased by raising the dosage (from two to three, four and six) of the Ph1 gene, located on the long arm of chromosome 5B (5BL). In several cells more than three bivalents were interlocked in one chain configuration indicating involvement of non-homoeologous bivalents. Plants with reduced dose (one or zero) of Ph1 also exhibited an increased frequency of interlocking but to a lesser extent than those with high gene dosage. However, chains of more than three interlocked bivalents were never observed in these plants, suggesting that with one or zero doses of Ph1 interlocking is restricted to homoeologous bivalents only. Chromosomal arm 5BS affected interlocking in an opposite manner to 5BL; namely, two and four doses of 5BS markedly reduced interlocking frequency. The modification in the frequency of interlocking bivalents by these genetic manipulations represents the first successful attempt to affect interlocking by genetic means. The results are explained on the basis of the hypothesis that this gene system controls somatic and premeiotic association of both homologous and homoeologous chromosomes.     

Meiosis in Drosophila melanogaster

Chromosome pairing during meiosis I in D. melanogaster males was investigated ultrastructurally by examining complete bivalents in electron micrographs of serial thin sections. The XY bivalent is characterized by the presence of unique material located between the two half-bivalents at the site of synapsis. The material has a fibrillar appearance and is less electron dense than the surrounding chromatin. YY bivalents in XYY males and XY bivalents containing the X chromosome, In(1)sc ^4Lsc^8R, where the pairing sites of the X chromosome are inverted and partially deleted also possess this material. The material is not associated with autosomal bivalents and may represent a morphological manifestation of the hypothetical cohesive elements (collochores) which are thought to function in conjunction of the X and Y chromosomes (Cooper, 1964).     

Female meiosis in two species of tsetse fly (Genus Glossina)

Supernumerary chromosomes form bivalents during female meiosis in the tsetse fly and it is suggested that this is a control mechanism for their retention in the population. Chiasmata regularly form in the autosome and X chromosome bivalents.