Gene mapping by chromosome microdissection and microisolation in the chicken

A chromosome microdissection and microisolation technique in combination with filter hybridization was developed for chromosomal localization of cloned chicken genes. The DNA was obtained from microdissected chromosome regions of metaphase spreads. Dissected DNA was amplified by polymerase chain reaction (PCR). The chicken MHC gene located on the nucleolar chromosome and beta-actin gene located on chromosome 2q were chosen as tests for the procedure and then detected by dot blot analysis using amplified chromosomal DNA probed with biotinylated DNA. The study establishes the technique of using chromosome microdissection and microisolation for localization of cloned genes as a complementary or alternative approach to both in situ DNA/chromosome hybridization and fluorescent in situ hybridization.

Molecular cloning and sequence analysis of the cDNA for northern pike (Esox lucius) growth hormone

The complete nucleotide sequence of the northern pike (Esox lucius) cDNA for pregrowth hormones was determined from clones derived from a pituitary gland cDNA library. Seventeen cDNA clones were isolated from a single mRNA species. A cDNA of 1,227 nucleotides was sequenced and found to encode a polypeptide of 209 amino acid residues, which included a putative signal sequence of 22 amino acid residues. Sequence comparison of the northern pike growth hormone gene to other known growth hormone genes revealed similarities closest to other members of the superorder Protacanthopterygii, which includes the Salmonidae family (i.e., salmon and trout).

Characterization of AluI repeats of zebrafish (Brachydanio rerio)

Two families of repetitive DNA sequences were isolated from the zebrafish genome and characterized. Eight different sequences were sequenced and classified by two standards, their (G + C) composition and their lengths. For convenience, the sequences were first divided into two types. Type I was (A + T)-rich, was repeated approximately 500,000 times, and constituted approximately 5% of the zebrafish genome. Type II was (G + C)-rich, was reiterated approximately 90,000 times, and comprised approximately 0.5% of the genome. Agarose gel electrophoresis of zebrafish DNA cleaved with AluI revealed three distinguishable bands of repetitive fragments: large (approximately 180 bp, designated RFAL), medium (approximately 140 bp, RFAM), and small (approximately 90 bp, RFAS). The RFAL fragments contained both type I and type II sequences. Limited digestion of genomic DNA indicated that RFAL and RFAM were tandemly arranged in the genome, whereas RFAS showed a mixed pattern of both tandem and interspersed repeated arrangements. Although inclusion of a repetitive sequence in a transgenic construct did not appreciably accelerate homologous integration of transgenes into the zebrafish genome, the AluI sequences could facilitate transgene mapping following chromosomal integration.

Importance of the CArG box in regulation of beta-actin-encoding genes

The beta-actin-encoding gene (Act) in carp is regulated by several cis-acting regulatory elements including the evolutionarily conserved CC(A/T)6GG (CArG box or serum-response element) sequences positioned in the promoter region between the CAAT and TATA boxes and in the first intron. To address the roles of the two CArG boxes on gene expression, we replaced them with linker sequences. The CArG box in the proximal promoter was not required for promoter activity in tissue-cultured cells, but was required in conjunction with a second CArG box in the first intron to give full expression in transgenic embryos. Likewise, the geometry of cis-acting transcriptional elements in the proximal promoter was more important for expression of transgenic constructs in developing embryos than in tissue-cultured fibroblasts. Mobility-shift and exonuclease mapping experiments indicated that the same or similar protein factors bind around the two CArG boxes, suggesting that interactions between the promoter and the first intron are involved in Act regulation.

Mapping of the growth hormone gene by in situ hybridization to chicken chromosome 1

In situ hybridization of a tritium-labeled chicken growth hormone cDNA to 62 chicken metaphase chromosome spreads was examined by analysis of silver grain distribution. A total of 554 chromosomally located grains were recorded. There was a highly significant P value for the association of silver grains to the long arm of chromosome 1. The chicken growth hormone gene can be assigned to chromosomal G-band region 1q4 because 41.3% of silver grains on chromosome 1q were located in this region.

Development of expression vectors for transgenic fish

Genetic alteration of fish is important for aquatic biotechnology as well as for investigating molecular interactions that occur during vertebrate development. The numerous, large, transparent, and externally fertilized eggs of many fish species make them ideally suitable for genetic manipulation, especially for production of transgenic animals. Genetic engineering of fish requires suitable expression vectors. Accordingly, we developed two fish expression vectors, FV-1 and FV-2, which contain the proximal promoter and enhancer regulatory elements of the carp beta-actin gene and the polyadenylation signal from the salmon growth hormone gene. The two fish expression vectors were tested in microinjected fish eggs and in tissue cultured fish and mammalian cells. These two "all-fish" expression vectors should be useful for genetic engineering of fish and have been used with growth-enhancing genes in transgenic fish.

The improbability of irradiated spermatozoa as gene transfer vectors in chickens

It is concluded that chromatin fragments derived from irradiated chicken spermatozoa are not viable vectors for gene transfer. In three experiments conducted at sequential intervals over a period of 1 1/2 years, no marker traits were found in 1,065 G0 progeny from irradiated spermatozoa of Minnesota Dominant Marker males inseminated into recessive Rhode Island Red and White Leghorn females. The inability to secure transformants is ascribed to the following factors: a maximum of five and probably fewer potential vector fragments for each G0 progeny because of irradiation effect on spermatozoan ability to enter the germinal disc; uncertainty of DNA integrity from highly irradiated chromatin; no known mechanism for release of chromatin fragments from irradiated spermatozoa supernumerary pronuclei; and the uncertainty of selective integration into the zygotic nucleus.

Borate G-banding technique applicable to in situ deoxyribonucleic acid/deoxyribonucleic acid hybridized chicken chromosomes

The borate G-banding technique produced excellent longitudinal bands similar to trypsin G-bands on chicken chromosomes prepared from embryo material. Aged chromosome preparations on slides were pretreated in borate buffer (pH 9.2) for 10 to 30 s at 37 C, then stained in Giemsa solution. This simple G-banding procedure gave high-resolution chromosome banding and permitted the visualization of silver grains that localized cloned gene sequences or cloned DNA fragments to specific regions by in situ hybridization.

Functional analysis of elements affecting expression of the beta-actin gene of carp

Regulatory regions of the beta-actin gene of the common carp (Cyprinus carpio) have been examined by linking upstream, 5'-flanking sequences and regions of the first intron to a bacterial chloramphenicol acetyltransferase (CAT) reporter gene. By analysis of the mRNA products and encoded CAT activity, we have identified four putative regions that influence expression: (i) a negative regulatory region 2,300 to 1,100 base pairs (bp) ahead of the gene; (ii) a proximal promoter element, containing the highly conserved CCAAT, CC(A/T)6GG, and TATA boxes, that is within the first 204 bp upstream of the initiation site; (iii) a negative element of 426 bp in the 5' region of the first intron; and (iv) a positive 304-bp element near the end of the first intron that contains highly conserved sequences found in all characterized beta-actin genes. The positive intron element is not a classical enhancer; it is position and orientation dependent, as has been observed in other housekeeping genes in vertebrates. Depending on the elements joined together, CAT gene expression can be modulated more than 500-fold in transfected mouse cells.

Chromosomal localization of chicken sequences homologous to the beta-actin gene by in situ hybridization

In situ DNA/chromosome hybridization techniques were used to localize the cytoplasmic beta-actin gene in the chicken. Hybridization of a beta-actin cDNA probe to metaphase chromosome spreads indicated that sequences complementary to this probe are located on the long arm of chromosome 2 (2q) and one of chromosomes 9 through 12.

Restriction enzymes MspI, HpaII, HaeIII, and HinfI applied to chicken mitotic chromosomes

The restriction enzymes MspI, HpaII, HaeIII, and HinfI were applied in situ to chicken metaphase chromosomes to determine if they denatured specific regions to produce banding patterns. Human metaphase chromosomes were treated simultaneously to serve as controls. The MspI, HpaII, and HaeIII enzymes produced no visible banding patterns in chicken chromosomes. There was slight banding on a few chromosomes in HinfI preparations, which was similar to the occasional spontaneous banding observed in chicken chromosome preparations. The results indicate that these four enzymes do not denature C-band regions in sufficient magnitude to be detected in chicken metaphase chromosomes.

5-azacytidine-induced increase in plasma prolactin levels of immature turkeys

Immature female turkeys (7 wk old) were treated with 5-azacytidine, a cytidine analog that has been shown to inhibit cytosine methylation in eukaryotic DNA. Such methylation has been repeatedly implicated in the control of specific gene expression in higher vertebrates. Turkeys administered 5-azacytidine (5 mg/kg) by intravenous injection daily for 5 days exhibited elevated (P less than .05) circulating prolactin (Prl) levels, whereas hens treated with saline, cytidine, or 6-azathymine did not show altered circulating Prl levels. Absence of response upon treatment with the normal nucleoside cytidine or the 6-aza analog of thymine reasonably eliminates nonspecific drug-induced stress as the cause of Prl level elevation. Based on these findings, DNA methylation is implicated in the control of circulating Prl levels in the young turkey.

Conserved repetitive DNA sequences (Bkm) in normal equine males and sex-reversed females detected by in situ hybridization

In situ hybridization with a cloned banded krait sex-specific repetitive DNA probe (Bkm) indicates a high concentration of Bkm sequences on the horse Y chromosome in both normal XY males and XY sex-reversed females. Lesser, but still significant, concentrations of Bkm sequences were mapped to horse chromosomes 3, 4, and 30.

Tissue specific methylation of c-myc in adult chickens

Methylation of cytosine in DNA has long been correlated with modulation of specific gene expression in eukaryotes. Methylation of the c-myc locus was examined in six tissues from adult Leghorn chickens. The c-myc locus was found to be variably methylated in all examined tissues, except blood, where erythrocytic DNA showed no evidence of significant methylation of c-myc. This is contrasted with the observed sever methylation of the beta actin locus and the generally high methylation patterns found in avian erythrocytic DNA.

Cloning, sequencing, and expression of cDNA for human beta-glucuronidase

We report here the cDNA sequence for human placental beta-glucuronidase (beta-D-glucuronoside glucuronosohydrolase, EC 3.2.1.31) and demonstrate expression of the human enzyme in transfected COS cells. We also sequenced a partial cDNA clone from human fibroblasts that contained a 153-base-pair deletion within the coding sequence and found a second type of cDNA clone from placenta that contained the same deletion. Nuclease S1 mapping studies demonstrated two types of mRNAs in human placenta that corresponded to the two types of cDNA clones isolated. The NH2-terminal amino acid sequence determined for human spleen beta-glucuronidase agreed with that inferred from the DNA sequence of the two placental clones, beginning at amino acid 23, suggesting a cleaved signal sequence of 22 amino acids. When transfected into COS cells, plasmids containing either placental clone expressed an immunoprecipitable protein that contained N-linked oligosaccharides as evidenced by sensitivity to endoglycosidase F. However, only transfection with the clone containing the 153-base-pair segment led to expression of human beta-glucuronidase activity. These studies provide the sequence for the full-length cDNA for human beta-glucuronidase, demonstrate the existence of two populations of mRNA for beta-glucuronidase in human placenta, only one of which specifies a catalytically active enzyme, and illustrate the importance of expression studies in verifying that a cDNA is functionally full-length.

Isolation and expression in Escherichia coli of a cDNA clone encoding human beta-glucuronidase

Mucopolysaccharidosis type VII is a lysosomal storage disease resulting from a deficiency of beta-glucuronidase (BG) activity. To facilitate the investigation of mutation in the disease and provide molecular diagnostic tools for affected families, we have isolated human BG cDNA clones. The SV40-transformed human fibroblast cDNA library of Okayama and Berg [Mol. Cell. Biol. 3 (1982) 280-289] was screened with a fragment of a murine BG cDNA clone (pGUS-1). The 17 human cDNA clones (pHUG) isolated were identical by restriction mapping, varying only in length. The pHUG clones show 80% DNA sequence homology with pGUS-1 in a 198-bp PvuII-SstI restriction fragment. Both pGUS-1 and the pHUG clones contained an open reading frame (ORF) throughout the sequenced region with a predicted amino acid sequence homology of 73%. Expression in Escherichia coli of a 1150-bp fragment of pHUG-1 subcloned in pUC9 resulted in an isopropyl-thio-beta-galactoside (IPTG)-inducible 35-kDal fusion protein which was specifically immunoprecipitated by goat anti-human BG immunoglobulin G (IgG). This evidence provides direct confirmation that the pHUG cDNA clones correspond to human BG.

Isolation of human fibroblast catalase cDNA clones. Sequence of clones derived from spliced and unspliced mRNA

We report the isolation and sequence of partial cDNA clones coding for human catalase. These clones were recovered from a human fibroblast cDNA library by screening with mixtures of oligonucleotide probes deduced from the amino acid sequence of human erythrocyte catalase. A comparison of their nucleotide sequence with the known protein sequence and mapping of homologous DNA sequences to the short arm of chromosome 11 in somatic cell hybrids confirmed that they coded for catalase. One of these clones contained a 462-base insertion interrupting the coding sequence with stop codons in all three reading frames. The 5' and 3' ends of the insertion correspond to the donor and acceptor consensus sequences of introns. Inspection of clones lacking the insertion confirm the location of the splice sites. We suggest this clone corresponds to the product of reverse transcription of an unspliced mRNA species. The catalase gene is the closest genetic marker mapped to Wilms tumor, one of the most prevalent of childhood cancers. Catalase cDNA probes will be useful to the examination of mitotic recombination in the etiology of this disease and may provide a useful starting point to the search for the putative Wilms tumor gene.