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Molecular characterization and chromosomal mapping of porcine adipose differentiation-related protein (ADRP).

ADRP plays an important role in regulating lipid storage in various cells. We investigated the ADRP gene as a candidate gene for intramuscular fat deposition and marbling traits in pigs. A full-length transcript of porcine ADRP was cloned by RT-PCR and RACE. The porcine ADRP cDNA (1848 bp) contains a 1377-bp open reading frame, encoding a deduced protein of 459 amino acids, which has amino acid sequence identities of 89, 89, 82 and 81% with cattle, human, mouse and rat ADRP genes respectively. The genomic structure and sequence of the porcine ADRP were also analysed using a BAC clone of a Korean native pig. Pig ADRP comprises eight exons spanning approximately 13 kb and is located on chromosome 1 q2.3-q2.7 between microsatellite markers SW2185 and SW974. Several sequence variations were detected from nine different pig breeds. The biological role of this gene and the mapping localization indicated that the porcine ADRP is a possible candidate gene for fat deposition and marbling traits.

Adipose Tissue↗

cDNA cloning, sequencing and chromosome mapping of a non-erythroid spectrin, human alpha-fodrin.

Several overlapping cDNA clones encompassing 2760 nucleotides of the alpha-subunit of a human non-erythroid spectrin (termed fodrin) were isolated from a human lung fibroblast cDNA library. DNA and RNA blot analyses indicated that a single copy alpha-fodrin gene encodes a 9-kb transcript. The cDNA clones were sequenced, and all were found to contain long open reading frames. The overlapping regions were identical except for a 60-nucleotide inframe insertion at position 1133 in the composite sequence. This result suggests that at least two distinct transcripts exist in fibroblast cells. The chromosomal location of human alpha-fodrin was assigned to 1p34-1p36.1 by hybridization to somatic cell hybrids, and it is thus distinct from that of human alpha-spectrin which has been mapped to 1q22-1q25. Alignment of the composite 919 amino acids of the predicted protein sequence of human alpha-fodrin with that of human alpha-spectrin indicated that alpha-fodrin has a similar 106-amino-acid repeating structure, which is homologous with alpha-spectrin repeats 7-15. Repeats 10 and 11 are anomalous in sequence and structure from other repeats. A comparison of nucleic acid and amino acid homologies between alpha-spectrin and the alpha-fodrin of several vertebrates indicated that human non-erythroid alpha-fodrin and the common alpha-subunit of erythroid and non-erythroid cells of non-mammalian vertebrates are closely related (90%-96% amino acid homology), whereas alpha-fodrin is only distantly related to the erythroid-specific alpha-spectrin subunit of mammals (55%-59% amino acid homology). These data suggest that mammalian erythroid alpha-spectrin evolved by duplication and rapid divergence from an ancestral alpha-fodrin-like gene.

Amino Acid Sequence↗

On the roles of heterochromatin and euchromatin in meiosis in drosophila: mapping chromosomal pairing sites and testing candidate mutations for effects on X-Y nondisjunction and meiotic drive in male meiosis.

Mapping of pairing sites involved in meiotic homolog disjunction in Drosophila has led to conflicting hypotheses about the nature of such sites and the role of heterochromatin in meiotic pairing. In the female-specific distributive system, pairing regions appear to be exclusively heterochromatic and map to broad regions encompassing many different sequences. In male meiosis, autosomal pairing sites appear to be distributed broadly within euchromatin but to be absent from heterochromatin, whereas the X-pairing site maps in the centric heterochromatin. The X site has been shown to coincide with the intergenic spacer (IGS) repeats within the rDNA arrays shared between the X and Y. It has not been clear whether the heterochromatic location of this pairing site has any significance. A novel assay for genic modifiers of X-Y chromosome pairing was developed based on the intermediate nondisjunction levels observed in males whose X chromosome lacks the native pairing site but contains two transgenic insertions of single rDNA genes. This assay was used to test several mutations in Su(var) (Suppressor of position effect variegation), PcG (Polycomb-Group) recombination defective, and repair-defective genes. No strong effects on disjunction were seen. However, the tests did uncover several mutations that suppress or enhance the meiotic drive (distorted X-Y recovery ratio) that accompanies X-Y pairing failure.

Animals↗

Chromosomal mapping of a middle-repetitive DNA sequence in a cluster of five species of Hawaiian Drosophila.

We describe the properties of a repetitive transposable element isolated from a chromosomal site close to the Adh (alcohol dehydrogenase gene) region of the Hawaiian Drosophila species, D. heteroneura. The cloned element is less than 2 kilobases in length. Although its polytene chromosome sites are constant in an individual, it shows a pattern of in situ hybridization that varies both within and between five species of the D. planitibia subgroup. These species are closely related, having diverged at various times from 0.5 to 5 million years ago. The distribution of the element appears to reflect the evolutionary relationships of the species except that the differences between D. planitibia and D. differens are ambiguous. Evidence of ragged excision of the element is found in one species.

Alcohol Dehydrogenase↗

Mapping chromosomal proteins in vivo by formaldehyde-crosslinked-chromatin immunoprecipitation.

Gene regulation is a complex process. Numerous factors appear to be required for the accurate temporal and spatial regulation of each gene. Often these factors are assembled into multiprotein complexes, contributing to specific gene regulation events. Understanding how all these factors are organized in the chromosome and how their function is regulated in vivo is a challenging task. One of the most useful techniques for studying this level of gene regulation is the in vivo fixation by formaldehyde crosslinking of proteins to proteins and proteins to DNA, followed by immunoprecipitation of the fixed material.

Animals↗

Genomic organization and chromosome mapping of the human homeobox gene HHEX.

In the present study, we report the genomic reconstruction of the human homeobox-containing gene HHEX by the use of the data available in public databases. This analysis allowed characterization of the gene organization showing that it is very similar to the mouse gene. Moreover the gene was mapped using FISH to 10q24.

Animals↗

Chromosomal mapping of the human genes for the calmodulin-dependent protein phosphatase (calcineurin) catalytic subunit.

Multiple catalytic subunits of the Ca2+ and calmodulin (CaM)-dependent protein phosphatase (PrP) ("calcineurin" or PrP-2B) are derived from at least two structural genes, type 1 ("calcineurin A alpha") and type 2 ("calcineurin A beta "), each of which can produce alternatively spliced transcripts. To examine the possible linkage of these genes, we analyzed genomic DNA from human/hamster hybrid cell lines using probes of 122 base pairs that were designed to bind selectively to exon 3 of the open reading frame. In this region, the nucleotide sequence of the type 2 murine cDNA that we cloned was greater than 99% identical to the type 2 human cDNA but only 78% identical to the type 1 human cDNA. Hybridization to Southern blots containing DNA from all human chromosomes showed that gene 1 was found on chromosome 4, whereas gene 2 segregated to chromosome 10. These data suggest that expression of the two calcineurin genes is not physically linked.

Amino Acid Sequence↗

Isolation and chromosomal mapping of the human homolog of perilipin (PLIN), a rat adipose tissue-specific gene, by differential display method.

Using the differential display technique, we isolated a cDNA clone encoding the human homolog of rat perilipin, a unique protein associated with intracellular neutral lipid droplets in adipocytes and steroidogenic cells. The full cDNA contains an open reading frame of 1566 nucleotides encoding 522 amino acids and bears 79% amino acid identity to rat perilipin. Northern blot analysis showed that among 20 human adult tissues examined, human perilipin was expressed specifically in adipose tissues. We determined the chromosomal location of the perilipin gene at 15q26 by means of fluorescence in situ hybridization.

Adipose Tissue↗

A structural homologue of the N-formyl peptide receptor. Characterization and chromosome mapping of a peptide chemoattractant receptor family.

Phagocytic cells of many higher species express calcium mobilizing G protein-coupled receptors for bacterial N-formyl peptides which mediate chemotaxis, degranulation, and the respiratory burst. cDNA encoding an N-formyl peptide receptor (FPR) has been reported. We now report the isolation of a closely related cDNA, 2.6 kilobase pairs in length, which we have designated as the FPRL1 receptor cDNA (FPRL1 = formyl peptide receptor like-1). FPR and the FPRL1 receptor derive from small, single-copy genes, both of which are located on human chromosome 19. The gene loci are designated FPR1 and FPRL1, respectively. Both FPR and FPRL1 cDNA cross-hybridize under high stringency conditions with a third gene, designated as FPRL2, which does not appear to be expressed in neutrophils. In contrast, transcripts for both the FPRL1 receptor and FPR are detected only in differentiated myeloid cells; the distribution of N-formyl peptide binding sites is also restricted to mature myeloid cells. FPRL1 cDNA encodes a 351-amino acid polypeptide whose sequence is 69% identical to that of FPR. G protein-coupled receptors that exhibit this degree of structural similarity typically possess a conserved ligand specificity. However, the FPRL1 receptor does not bind prototype N-formyl peptide ligands when expressed in heterologous cell types. These results suggest that FPR1 may be the only gene that is expressed by neutrophils that encodes a receptor capable of binding prototype N-formyl peptides. Moreover, discovery of the FPRL1 receptor indicates the existence of another as yet unidentified peptide that may recruit neutrophils to sites of inflammation.

Amino Acid Sequence↗

Chromosomal mapping of core histone acetylation by immunoselection.

Acetylation of specific lysine residues in the N-terminal domains of core histones is a biochemical marker of active genes. To determine the spatial and temporal distribution of this reversible posttranslational modification, affinity-purified polyclonal antibodies recognizing the epitope epsilon-acetyllysine have been used in immunoselection procedures with mononucleosomes and salt-soluble chromatin fragments generated by micrococcal nuclease. The DNA of the antibody-selected chromatin was slot-blotted and probed with a variety of gene sequences: an enhanced hybridization signal, with respect to that from the DNA of the input chromatin, demonstrated elevated acetylation levels on the histones associated with the probing sequences. Using chicken embryonic erythrocytes as chromatin source and probes from the beta globin locus, it was shown that both the embryonic epsilon and adult beta genes are acetylated at 5 and 15 days, and the acetylation uniformly covers the whole of the locus, precisely comapping with the 33 kb of open chromatin structure. Studies with proliferating human K562 cells show that the inactive but poised PDGF-beta gene is already hyperacetylated and that its acetylation status is not enhanced on induction. These results indicate that acetylation is not a consequence of transcription but a prerequisite and that it may be responsible for either generating or maintaining the open structure of poised and active genes.

Acetylation↗

A locus for familial skewed X chromosome inactivation maps to chromosome Xq25 in a family with a female manifesting Lowe syndrome.

In mammals, X-linked gene products can be dosage compensated between males and females by inactivation of one of the two X chromosomes in the developing female embryos. X inactivation choice is usually random in embryo mammals, but several mechanisms can influence the choice determining skewed X inactivation. As a consequence, females heterozygous for X-linked recessive disease can manifest the full phenotype. Herein, we report a family with extremely skewed X inactivation that produced the full phenotype of Lowe syndrome, a recessive X-linked disease, in a female. The X chromosome inactivation studies detected an extremely skewed inactivation pattern with a ratio of 100:0 in the propositus as well as in five out of seven unaffected female relatives in four generations. The OCRL1 "de novo" mutation resides in the active paternally inherited X chromosome. X chromosome haplotype analysis suggests the presence of a locus for the familial skewed X inactivation in chromosome Xq25 most likely controlling X chromosome choice in X inactivation or cell proliferation. The description of this case adds Lowe syndrome to the list of X-linked disorders which may manifest the full phenotype in females because of the skewed X inactivation.

Chromosomes, Human, X↗