A region-specific microdissection library for human chromosome 2p23-->p21 and the analysis of an interstitial deletion of 2p21

Microdissection and painting of the Y chromosome in spinach (Spinacia oleracea)

Spinach has long been used as a model for genetic and physiological studies of sex determination and expression. Although trisomic analysis from a cross between diploid and triploid plants identified the XY chromosome as the largest chromosome, no direct evidence has been provided to support this at the molecular level. In this study, the largest chromosomes of spinach from mitotic metaphase spreads were microdissected using glass needles. Degenerate oligonucleotide primed polymerase chain reaction was used to amplify the dissected chromosomes. The amplified products from the Y chromosome were identified using the male-specific marker T11A. For the first time, the largest spinach chromosome was confirmed to be a sex chromosome at the molecular level. PCR products from the isolated chromosomes were used in an in situ probe mixture for painting the Y chromosome. The fluorescence signals were mainly distributed on all chromosomes and four pair of weaker punctate fluorescence signal sites were observed on the terminal region of two pair of autosomes. These findings provide a foundation for the study of sex chromosome evolution in spinach.

The development of chromosome microdissection and microcloning technique and its applications in genomic research

The technique of chromosome microdissection and microcloning has been developed for more than 20 years. As a bridge between cytogenetics and molecular genetics, it leads to a number of applications: chromosome painting probe isolation, genetic linkage map and physical map construction, and expressed sequence tags generation. During those 20 years, this technique has not only been benefited from other technological advances but also cross-fertilized with other techniques. Today, it becomes a practicality with extensive uses. The purpose of this article is to review the development of this technique and its application in the field of genomic research. Moreover, a new method of generating ESTs of specific chromosomes developed by our lab is introduced. By using this method, the technique of chromosome microdissection and microcloning would be more valuable in the advancement of genomic research.

Detailed analysis of a 17q21 microdissection library by sequence bioinformatics and isolation of region-specific clones

A region-specific microdissection library originating from human chromosome 17q21, was constructed using the MboI linker-adaptor microcloning technique. DNA sequencing of 241 microclones resulted in the identification of 74 novel coding sequences, paralogs of known genes, and known, but previously unmapped, genes or expressed sequence tags that were "virtually" mapped to chromosome 17q21. By pooling the microclones as multiplexed hybridization probes, and by virtue of their origin on 17q21, we were able to identify approximately 150 P1 clones from the human Reference Library Data Base P1 Library that potentially map to chromosome 17q21. Verification of the 17q21 location of 16 P1 clones was accomplished by PCR analysis with STS primer pairs to known 17q21 genes or by FISH. Our results demonstrate the substantial advantage of combining the sequence analysis of microclones with multiplex hybridization strategies for gene discovery and mapping specific gene rich regions of the genome.

Construction and characterization of three region-specific microdissection libraries for human chromosome 18

Three region-specific libraries for the entire human chromosome 18 were constructed using microdissection and Mbol linker-adaptor microcloning techniques. The libraries included 18pter-p11.1 (designated 18P library), 18q11.1-q12.3 (18Q1 library), and 18q21.1-qter (18Q2 library). Samples of the microclones from each library were analyzed in detail. The insert sizes ranged between 50-600 bp, with a mean of 180-220 bp for the three libraries. The libraries contained approximately 40-60% microclones with unique sequence inserts. More than 30 unique sequence microclones from each library were analyzed by Southern blot hybridization to demonstrate that they are human specific and were derived from chromosome 18. The human genomic HindIII fragments hybridized to each microclone were determined and microclones cross-hybridized to rodent species were identified. These region-specific libraries and the unique sequence microclones from the libraries are useful reagents for (1) isolating highly polymorphic microsatellite markers for refined linkage analysis, (2) identifying corresponding YAC, BAC or other clones with large inserts for contig assembly and high resolution physical mapping, (3) isolating cDNA clones from the dissected region, and (4) convenient sequencing of the microclones to prepare high density markers and sequence-tagged sites (STSs). Such applications have been demonstrated in a series of similarly constructed microdissection libraries from other regions of the human genome.

Molecular characterization of breakpoints in patients with holoprosencephaly and definition of the HPE2 critical region 2p21

Holoprosencephaly (HPE) is a common developmental defect involving the brain and face in humans. Cytogenetic deletions in patients with HPE have localized one of the HPE genes (HPE2) to the chromosomal region 2p21. Here we report the molecular genetic characterization of nine HPE patients with cytogenetic deletions or translocations involving 2p21. We have determined the parental origin of the deleted chromosomes and defined the HPE2 critical region between D2S119 and D2S88/D2S391. As a first step towards cloning the HPE2 gene which is crucial for normal brain development we have constructed a YAC contig which spans the smallest region of deletion overlap. Several of these YACs could be identified which span three different 2p21 breakpoints in HPE patients. These YACs narrow the HPE2 critical region to less than 1 Mb and are now being further analyzed to identify the gene causing holoprosencephaly on chromosome 2.

Complete set of eleven region-specific microdissection libraries for human chromosome 2

The construction and characterization of 11 region-specific libraries for the entire human chromosome 2 have been completed, including four libraries for the short arm and six libraries for the long arm, plus a library for the centromere region. These libraries were constructed using the chromosome microdissection and microcloning technology. Eight libraries have been described previously. This paper presents the final three libraries: 2q21-q22 (designated 2Q5 library), 2q11-q14 (2Q6). and 2p11.1-q11.1 (2CEN). The sizes of the dissected regions ranged between 20 and 30 Mb, with the centromere region of about 4 Mb. All these libraries are large, potentially comprising hundreds of thousands of recombinant microclones. Between 77% and 97% of the microclones were shown to derive from respective dissected regions. From 26 to 66 unique sequence microlones were isolated and characterized in detail for each library. The microclones have short inserts, ranging between 50 and 600 bp, with a mean of about 200 bp. The short inserts can be conveniently sequenced as STSs to provide high density probes for the dissected region. A plasmid sub-library containing at least 20,000 microclones, and usually more, has been prepared from each library and deposited to ATCC for general distribution. The libraries have been used effectively in constructing high resolution physical maps and for contig assembly, as well as in positional cloning of disease genes assigned to the dissected region. Comparing to other chromosomes with detailed mapping information and densely populated probes, chromosome 2 remains largely under-exploited. The availability of a complete set of region-specific libraries and unique sequence microclones from the libraries should provide valuable resources for genome analysis, high resolution physical mapping, region-specific cDNA isolation, and positional cloning for chromosome 2.

Three region-specific microdissection libraries for the long arm of human chromosome 2, regions q33-q35, q31-q32, and q23-q24

Three region-specific libraries have been constructed from the long arm of human chromosome 2, including regions 2q33-35 (2Q2 library), 2q31-32 (2Q3) and 2q23-24 (2Q4). Chromosome microdissection and the MboI linker-adaptor microcloning techniques were used in constructing these libraries. The libraries comprised hundreds of thousands of microclones in each library. Approximately half of the microclones in the library contained unique or low-copy number sequence inserts. The insert sizes ranged between 50 and 800 bp, with a mean of 130-190 bp. Southern blot analysis of individual unique sequence microclones showed that 70-94% of the microclones were derived from the dissected region. 31 unique sequence microclones from the 2Q2 library, 31 from 2Q3, and 30 from 2Q4, were analyzed for insert sizes, the hybridizing genomic HindIII fragment sizes, and cross-hybridization to rodent species. These libraries and the short insert microclones derived from the libraries should be useful for high resolution physical mapping, sequence-ready reagents for large scale genomic sequencing, and positional cloning of disease-related genes assigned to these regions, e.g. the recessive familial amyotrophic lateral sclerosis assigned to 2q33-q35, and a type I diabetes susceptibility gene to 2q31-q33.

Construction and characterization of region-specific microdissection libraries and single-copy microclones for short arm of human chromosome 2

The short arm of human chromosome 2, comprising approximately 93 million bp, has been divided into four regions to construct region-specific microdissection libraries to facilitate physical mapping and gene cloning. These four regions include 2p23-p25 (designated 2P1), 2p21-p23 (2P2), 2p14-p16 (2P3), and 2p11-p13 (2P4). Together with three previously constructed microdissection libraries of 2P1, 2P2 and 2P4, a fourth library for the region 2p14-p16 (2P3) has been constructed and characterized to complete all four region-specific libraries for the entire 2p. The 2P3 library is very large, potentially comprising 1,000,000 recombinant microclones with insert sizes ranging between 50 and 800 bp and a mean of 250 bp. Approximately 40% of the microclones contain unique sequences. Of the 77 single-copy microclones analyzed, 66 clones (86%) hybridized to both human and chromosome 2 DNAs, indicating that they were derived from human and are chromosome 2 specific. The hybridizing HindIII genomic fragments for the 66 microclones have also been determined.