The chromosomal location of rye AFLP bands

23 AFLP bands were assigned to different rye chromosomes by means of two different sets of wheat-rye addition lines. Only one AFLP band could be assigned to 4R, and no specific AFLPs were found on the 5R chromosome. Only one AFLP band was explicitly assigned to 4R, and no specific AFLPs were found on the 5R chromosome. At least seven co-migrating AFLPs showed the same chromosomal location in both sets of addition lines. A total of 22 AFLPs were assigned to chromosome 1R using wheat-rye substitution lines. Six of them have counterparts in one of the addition lines analyzed, but only four have the same chromosomal location. Six and four of the total AFLPs located using addition (23) and substitution (22) lines segregated in the mapping population DS2 x RXL10, but only six were simultaneously assigned to the same chromosome by both approaches. Although co-migrating AFLPs could be located on different rye chromosomes using addition and substitution lines, we believe that AFLPs can be useful as rye chromosome markers.     

Extensive chromosome rearrangements distinguish the karyotype of the hypovirulent species Candida dubliniensis from the virulent Candida albicans

Candida dubliniensis and Candida albicans, the most common human fungal pathogen, have most of the same genes and high sequence similarity, but C. dubliniensis is less virulent. C. albicans causes both mucosal and hematogenously disseminated disease, C. dubliniensis mostly mucosal infections. Pulse-field electrophoresis, genomic restriction enzyme digests, Southern blotting, and the emerging sequence from the Wellcome Trust Sanger Institute were used to determine the karyotype of C. dubliniensis type strain CD36. Three chromosomes have two intact homologues. A translocation in the rDNA repeat on chromosome R exchanges telomere-proximal regions of R and chromosome 5. Translocations involving the remaining chromosomes occur at the Major Repeat Sequence. CD36 lacks an MRS on chromosome R but has one on 3. Of six other C. dubliniensis strains, no two had the same electrophoretic karyotype. Despite extensive chromosome rearrangements, karyotypic differences between C. dubliniensis and C. albicans are unlikely to affect gene expression. Karyotypic instability may account for the diminished pathogenicity of C. dubliniensis.     

Tissue-Specific Differences in the Spatial Interposition of X-Chromosome and 3R Chromosome Regions in the Malaria Mosquito Anopheles messeae Fall.

Spatial organization of a chromosome in a nucleus is very important in biology but many aspects of it are still generally unresolved. We focused on tissue-specific features of chromosome architecture in closely related malaria mosquitoes, which have essential inter-specific differences in polytene chromosome attachments in nurse cells. We showed that the region responsible for X-chromosome attachment interacts with nuclear lamina stronger in nurse cells, then in salivary glands cells in Anopheles messeae Fall. The inter-tissue differences were demonstrated more convincingly in an experiment of two distinct chromosomes interposition in the nucleus space of cells from four tissues. Microdissected DNA-probes from nurse cells X-chromosome (2BC) and 3R chromosomes (32D) attachment regions were hybridized with intact nuclei of nurse cells, salivary gland cells, follicle epithelium cells and imaginal disсs cells in 3D-FISH experiments. We showed that only salivary gland cells and follicle epithelium cells have no statistical differences in the interposition of 2BC and 32D. Generally, the X-chromosome and 3R chromosome are located closer to each other in cells of the somatic system in comparison with nurse cells on average. The imaginal disсs cell nuclei have an intermediate arrangement of chromosome interposition, similar to other somatic cells and nurse cells. In spite of species-specific chromosome attachments there are no differences in interposition of nurse cells chromosomes in An. messeae and An. atroparvus Thiel. Nurse cells have an unusual chromosome arrangement without a chromocenter, which could be due to the special mission of generative system cells in ontogenesis and evolution.     

Loss of chromosomes 2R and 5RS in octoploid triticale selected for agronomic traits

The advanced lines of octoploid triticale which have been bred for nearly a half century in China show significant improvements in agronomic traits such as plant height, fertility, threshability, maturity and seed plumpness, although no intentional cytological selection had been performed. In this study, eight primary and six advanced lines were analyzed by fluorescence and genomic in situ hybridization to elucidate their chromosome constitutions. In the advanced lines, about 70% of the plants examined had 2n = 56 chromosomes (range: 50 to 58). Almost all advanced lines, however, had lost rye chromosome 2R and the short arm of 5R (5RS). The exceptions were lines Y1005 and Y4683: The former had lost only the 2R chromosome and the latter only 5RS. The reduction of rye chromosomes was compensated by an extra pair of 2D or A-genome (possibly 2A) chromosomes in plants with 2n = 56. This suggests that the loss of 2R and 5RS chromosomes contributes to the improvement of octoploid triticale. Since the plants with chromosome 2R are non-free threshing and chromosome 2D of synthetic wheat is known to carry the Tg (tenacious glumes) gene, it is possible that chromosome 2R carries a gene affecting the threshability, and we carried out selection to remove it. We also discuss the possible relationshipbetween 5RS and the genetic stability of octoploid triticale.     

Interaction of the IciA protein with AT-rich regions in plasmid replication origins.

A set of AT-rich repeats is a common motif in prokaryotic replication origins. We have screened for proteins binding to the AT-rich repeat region in plasmids F, R1 and pSC101 using an electrophoretic mobility shift assay with PCR-amplified DNA fragments from the origins. The IciA protein, which is known to bind to the AT-rich repeat region in the Escherichia coli origin of chromosome replication, oriC, was found to bind to the corresponding region from plasmids F (oriS) and R1, but not to pSC101. DNase I footprint analysis showed that IciA interacted with the AT-rich region in both F and R1. When the IciA gene was deleted, the copy number of plasmid F increased somewhat, whereas there was no major effect on the replication of pSC101 and R1, or on the E. coli chromosome.     

Suppression of an Escherichia coli dnaA mutation by the integrated R factor R.100.1: Change of chromosome replication origin in synchronized cultures.

We have followed, by deoxyribonucleic acid-deoxyribonucleic acid hybridization, the order of replication of three chromosomal markers during a synchronous round of replication in three strains of Escherichia coli carrying a dnaAts mutation: one strain in which the F-like R factor R.100.1 was established as a plasmid and two strains in which the dnaA mutation was suppressed by the integration of R.100.1 into the chromosome. In the R+ strain at 30C, replication of the plasmid took place simultaneously with the initiation of chromosome replication at the normal origin. In the integratively suppressed Hfr strains, at 42.5 C, chromosome replication was initiated preferentially from the integrated plasmid; little or no initiation occurred at the normal origin. Similar results were obtained for the one strain tested at 30 C. For both Hfr strains at 42.5 C, the data suggest that at least part of the population replicated bidirectionally. This conclusion had been confirmed using an autoradiographic procedure. Both types of experiment indicate a wide variation in the rate of travel of individual replication forks within the population.     

Incorporation of the ampicillin resistance transposon into the Escherichia coli K-12 chromosome and into plasmids]

The mutant pEG1 of R-factor RP4 with temperature-sensitive defect in replication, carrying a transposable ampicillin resistance element Tn1 was used to define the frequency of insertion of this element into Escherichia coli K-12 chromosome and some other plasmids. Our results indicate that the frequency of colony forming by bacteria with pEG1-factor on ampicillin medium in non-permissive conditions corresponds to the frequency of Tn1 insertion into bacterial chromosome or some other plasmid (in case when the strains are carrying a second plasmid). The frequency of Tn1 insertion into the chromosome is about 4.10(-4). The defect in recA gene produce no serious change in the frequency of Tn1 insertion into the bacterial chromosome. The translocation of Tn1 element from pEG1-factor to R483, R6 and ColE1 plasmids occurs at 10 to 100-fold-higher frequency than from the plasmid to the chromosome. The insertion of Tn1 into the F'-factor KLF10 and R-factor R64-11 occurs at far lower frequency than that to plasmids R6, R483, or ColE1.     

Introgression of crown rust (Puccinia coronata) resistance from meadow fescue (Festuca pratensis) into Italian ryegrass (Lolium multiflorum) and physical mapping of the locus

Resistance was found in the meadow fescue (Festuca pratensis) to crown rust (Puccinia coronata), originating from ryegrasses (Lolium spp). A backcrossing programme successfully transferred this resistance into diploid Italian ryegrass (Lolium multiflorum) and genomic in situ hybridisation (GISH) was used to identify the introgressed fescue chromosome segment. The resistant (R) plants in two BC3 lines all carried an introgressed segment on a single chromosome, which in one of the lines was confined to the short arm of the chromosome. Susceptible (S) plants either contained no introgressed chromosome segment or a segment which was physically smaller than the segments in resistant plants. Using GISH the resistance locus could be physically mapped to the midpoint of a short arm. Segregation ratios of the progeny of BC3 plants, when crossed as R x S and R x R, were in agreement with the hypothesis that the resistance was controlled by a single gene or very closely linked genes. No R plants were produced by crossing S x S plants.     

Mutations in TRIOBP, which encodes a putative cytoskeletal-organizing protein, are associated with nonsyndromic recessive deafness

In seven families, six different mutant alleles of TRIOBP on chromosome 22q13 cosegregate with autosomal recessive nonsyndromic deafness. These alleles include four nonsense (Q297X, R788X, R1068X, and R1117X) and two frameshift (D1069fsX1082 and R1078fsX1083) mutations, all located in exon 6 of TRIOBP. There are several alternative splice isoforms of this gene, the longest of which, TRIOBP-6, comprises 23 exons. The linkage interval for the deafness segregating in these families includes DFNB28. Genetic heterogeneity at this locus is suggested by three additional families that show significant evidence of linkage of deafness to markers on chromosome 22q13 but that apparently have no mutations in the TRIOBP gene.     

Chromosome mapping in Pseudomonas aeruginosa PAT.

A linkage map of Pseudomonas aeruginosa PAT has been derived from the results of conjugation experiments using the plasmids FP2-2, R68, R91-5, and R68.45. FP2-2 and R68 each mobilize the chromosome from single, distinct transfer origins. R91-5 appears to mobilize the chromosome from two such origins, and R68.45 utilizes a number of transfer origins. R68 and R91-5 have both been shown to mobilize the chromosome with a polarity opposite to that by FP2-2. The locations of the transfer origins of these plasmids are such that it has not been possible to demonstrate chromosomal circularity by means of interrupted mating experiments. However, the available time-of-entry data combined with linkage data from plate mating experiments support the conclusion that the chromosome of P. aeruginosa is circular.     

利用微分离黑麦1R染色体的体外扩增产物进行染色体着染研究

首先对显微分离出的黑麦（ＳｅｃａｌｅｃｅｒｅａｌｅＬ．）１Ｒ染色体进行了两轮Ｓａｕ３Ａ连接接头介导的ＰＣＲ扩增（ＬＡ＿ＰＣＲ）。经Ｓｏｕｔｈｅｒｎ杂交证实这些染色体扩增片段来源于基因组ＤＮＡ之后,再利用１Ｒ染色体的第二轮扩增产物、黑麦基因组ＤＮＡ、ｒＤＮＡ基因为探针,与其根尖细胞中期分裂相进行染色体原位杂交,发现微分离的１Ｒ染色体体外扩增产物中包含大量的非该染色体特异性重复序列,而其信息量却较黑麦总基因组少;当以适量的黑麦基因组ＤＮＡ进行封阻时,微分离染色体的体外扩增产物成功地被重新定位在中期分裂相的一对１Ｒ染色体上,说明微分离１Ｒ染色体的ＰＣＲ扩增产物中的确包含了该染色体特异性的片段。此外,以从１Ｒ染色体微克隆文库中筛选出的一单、低拷贝序列和一高度重复序列分别为探针,染色体原位杂交检测发现,这一高度重复序列可能为端粒相关序列;而单、低拷贝序列却未检测到杂交信号。这些结果从不同侧面反映出染色体着染技术是证实微分离、微切割染色体的真实来源及筛选染色体特异性探针的有利工具。建立了可供参考的植物染色体着染实验体系,为染色体微克隆技术在植物中的进一步应用提供了便利。     

Karyological studies of some orophyte taxa of the genus Ranunculus L.from the Iberian Peninsula

The somatic chromosome number and detailed chromosome morphology have been studied in populations of seven species of Ranunculus, namely Ranunculus alpestris L., R.glacialis L., R. Thora L., R.seguieri Vill., R. Aconitifolius L., R.platanifolius L. And R. Acetosellifolius Boiss., from the Iberian Peninsula. Diploid levels have been found for these species in the samples studied. From the karyological data (karyograms, idiograms and asymmetry) relationships between these taxa are discussed.     

The human interleukin-10 receptor gene maps to chromosome 11q23.3

The human interleukin-10 receptor (IL-10R) gene has previously been mapped to chromosome 11. Here, we have determined the precise location of the human IL-10R gene by the fluorescence in situ hybridization method, and have found that the IL-10R gene maps to chromosome 11q23.3.     

Preferential elimination of chromosome 5R of rye in the progeny of 5R5D dimonosomics

Transmission of chromosome 5R of rye (Secale cereale L.) and chromosome 5D of common wheat (Triticum aestivum L.) through gametes of 5R5D dimonosomics (2n = 42, 20W″ + 5R′ + 5D′) was studied. Chromosome 5R was found to have lower competitiveness as compared to 5D. Gametes with the rye chromosome were two times less often involved in the formation of a progeny. The combined frequency of the karyotypes of wheat (5D5D) and wheat monosomics (5D) was 11.6-fold higher than the frequency of the karyotypes of substitution lines (5R5R) and monosomics for the rye chromosome (5R). The karyotypes of 10.38% of hybrid plants had aberrant 5R chromosomes with different translocations formed as a result of breakages in the centromere and in the proximal region of the long arm. Telocentrics for the short arm t5RS, i5RS isochromosomes, and chromosomes with a terminal deletion T5RS.5RL-del were identified. The absence of amplification of SSR markers mapped on 5RS and the detection of PCR products for a number of 5RL markers (including the genome-specific rye marker Xrms115) permitted nine plants carrying only the long arm of chromosome 5R to be revealed. Since t5RL telocentrics were not detected by the cytological analysis, the results obtained allow us to suggest the presence of small intercalary translocations of the long arm of chromosome 5R in chromosome 5D or in other wheat chromosomes.     

柱穗山羊草2C染色体诱发中国春小麦背景中黑麦1R染色体结构变异的研究

当柱穗山羊草(Aegilops cylindrica Host．)2C染色体单体添加到普通小麦品种中国春和以中国春为背景的派生系时,减数分裂时,不含2C染色体的配子会发生染色体结构变异。为了制备一套黑麦1R染色体缺失系以用于定位黑麦1R染色体上的控制重要农艺性状的基因,把一条2C染色体导人到小黑麦1R二体附加系(21″ 1R″)中,然后让这些个体(21″ 1R″ 2C′,2n=45)自交,以便产生1R染色体结构变异体。实验共检测了345粒F,种子,83粒种子带有结构变异的黑麦1R染色体(24．1％)。通过C分带和原位杂交检测,对来自于23株F2的46个F3植株所带有的异常1R染色体进行了归类：其中1RL端体为39．1％,1RL等臂染色体为2．2％,1RL易位系为32．6％。1RS端体为4．3％,1RS等臂染色体为4．3％,切点在长臂上的缺失体为2．2％。在6．5％的植株中同时含有2种类型的1R染色体结构变异。其余8．7％带有异常1R染色体的个体因为没有原位杂交结果而无法判断是属于哪种类型。已获得的1R结构变异株将有可能进一步发展成为一套可用于定位黑麦1R染色体上重要功能基因的遗传材料。另外,还探讨了综合应用细胞学和分子标记方法鉴定易位染色体中小麦染色体片段的尝试,并对所获结果进行了讨论。     

Inheritance of plant height in hexaploid triticales with R/D substitution

Inheritance of plant height has been studied in combinations of R/D-substituted forms of hexaploid triticale and specimens that have a complete chromosome set of rye and carry various genes determining dwarfism. Analysis of F1-F3 hybrids has demonstrated an additive effect of the dwarfism genes and the genetic component of chromosome D affecting the plant height. Deviations in the segregation with respect to plant height found in F2 combinations involving R/D-substituted forms and specimens with a complete chromosomal set of the R genome may be caused by meiotic disturbances resulting from the R/D substitution and an increase frequency of the transmission of the heterologous chromosome in the monosomically substituted form.     

Genetic mapping of cytological and isozyme markers on chromosomes 1R, 3R, 4R and 6R of rye

Cytogenetic maps involving chromosomes 1R, 3R, 4R and 6R have been developed from the analysis of offspring of crosses between multiple heterozygous rye plants. The maps include isozyme loci GpiR1, Mdh-R1 and Pgd2 (located in chromosome 1R), Mdh-R2 (located in chromosome 3R), Pgm-R1 (located in chromosome 4R) and Aco-R1 (located in chromosome 6R). Various telomeric and interstitial C-bands of these four chromosomes, the centromere split of chromosome 3R, and translocation TR01 were used as cytological markers. By means of electron microscope analysis of spread pachytene synaptonemal complexes, the breakpoint of TR01 was physically mapped in chromosome arms 4RS and 6RL. From the linkage data, conclusions were derived concerning the cytological locations of the isozyme loci and the physical extent of the evolutive translocations involving chromosome arm 6RL.     

Double-minute chromatin bodies in HL-60 leukemia cells sensitive and resistant to differentiation inducing agents

We studied the chromosome characteristics of HL-60 promyelocytic leukemia cells sensitive and resistant to differentiation inducing agents (DI). The karyotypic analysis of sensitive (HL-60 S) and resistant (HL-60 R) cells revealed the presence of identical chromosome abnormalities such as loss of chromosomes 5, 9, 10, 14, 16, 17 and X; and gain of chromosome 18. HL-60 S and HL-60 R cells also share five common markers. The difference between the two cell lines consisted essentially of the loss of an unidentifiable chromosome segment in the HL-60 R cell line. In addition, the two sublines showed marked differences in the content of double-minute chromatin bodies (DM), which were abundant in HL-60 S but rarely found in HL-60 R cells. Contrary to a previous report by others, there was no evidence of chromosome rearrangement of the DM as homogeneously stained regions (HSR) or abnormally banding regions (ABR) in the resistant HL-60 R cells. The presence of DM as an expression of gene amplification may be of relevance in the determination of susceptibility of HL-60 cells to DI.     

Formation of chromosomal tandem arrays of the SXT element and R391, two conjugative chromosomally integrating elements that share an attachment site

The SXT element, a conjugative, self-transmissible, integrating element (a constin) originally derived from a Vibrio cholerae O139 isolate from India, and IncJ element R391, originally derived from a South African Providencia rettgeri isolate, were found to be genetically and functionally related. Both of these constins integrate site specifically into the Escherichia coli chromosome at an identical attachment site within the 5' end of prfC. They encode nearly identical integrases, which are required for chromosomal integration, excision, and extrachromosomal circularization of these elements, and they have similar tra genes. Therefore, these closely related constins have virtually identical mechanisms for chromosomal integration and dissemination. The presence of either element in a recipient cell did not significantly reduce its ability to acquire the other element, indicating that R391 and SXT do not encode surface exclusion determinants. In cells harboring both elements, SXT and R391 were integrated in tandem fashion on the chromosome, and homologous recombination appeared to play little or no role in the formation of these arrays. Interference between R391 and SXT was detected by measuring the frequency of loss of an unselected resident element upon introduction of a second selected element. In these assays, R391 was found to have a stronger effect on SXT stability than vice versa. The level of expression and/or activity of the donor and recipient integrases may play a role in the interference between these two related constins.     

Cytogenetic analysis of forms produced by crossing hexaploid triticale with common wheat

Summary Hexaploid triticales were crossed with common wheats, and the resultant froms were selected for either triticale (AD 213/5-80) or common wheat (lines 381/80, 391/80, 393/80). The cytogenetic analysis showed that all forms differ in their chromosome composition. Triticale AD 213/5-80 and wheat line 381/80 were stable forms with 2n = 6x = 42. Lines 391/80 and 393/80 were cytologically unstable. In triticale AD 213/5-80, a 2R (2D) chromosome substitution was found. Each of the three wheat lines had a chromosome formed by the translocation of the short arm of IR into the long arm of the IB chromosome. In line 381/80, this chromosome seems to be inherited from the Kavkaz wheat variety. In lines 391/80 and 393/80, this chromosome apparently formed de novo since the parent forms did not have it. The karyotype of line 381/80 was found to contain rye chromosomes 4R/7R, 5R and 7R/4R. About 15% of the cells in line 391/80 contained an isochromosome for the 5R short arm and also a chromosome which arose from the translocation of the long arms of the 5D and 5R chromosomes. About one-third of the cells in the common wheat line 393/80 contained the 5R chromosome. This chromosome was normal or rearranged. Practical applications of the C-banding technique in the breeding of triticale is discussed.