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Biomedical subjects

H Xiao

Publications and source records attributed to H Xiao.

At least 19 recordsLinked to original sources

Chromosomal assignment of 46 brain cDNAs.

Expressed sequence tags (ESTs) have been obtained from several hundred brain cDNAs as an initial effort to characterize expressed brain genes. These ESTs will become tools for human genome mapping and they will also provide candidate causative genes for inherited disorders affecting the central nervous system. We have developed a procedure for the rapid chromosomal assignment of these ESTs: cDNA sequences are first analyzed by a computer program to determine regions likely not to be interrupted by introns in the genomic DNA. A pair of oligonucleotide primers is then designed to amplify this region by the polymerase chain reaction using DNA template from human-rodent somatic cell hybrid chromosomal panels. The chromosomal assignment of the cDNA is determined by studying the segregation of the amplified products in these panels. In this paper we describe the mapping of 46 brain ESTs, as well as observations on the amplification of rodent sequences.

Animals

[Molecular cytogenetic study of an extra small chromosome].

An extra small chromosome was observed in a three-generation family. Eight members of this family were involved, but their phenotypes were normal. Molecular cytogenetic study was carried out, using cytogenetic methods and chromosome in situ hybridization with 3H-labelled rDNA probe. The results showed that this chromosome was from the short arm of chromosome of D/G group. The origin and genetic effects of this chromosome and fertility of the carriers were also discussed were also discussed briefly.

Adult

Identification of three mammalian proteins that bind to the yeast TATA box protein TFIID.

The TATA box binding transcription factor TFIID of S. cerevisiae was used as a ligand for affinity chromatography. Polypeptides that bind specifically to yeast TFIID (TFIID-associated proteins, DAPs) were purified from human HeLa (heDAPs) and calf thymus (ctDAPs) whole cell extracts. Both heDAP and ctDAP fractions altered the binding of TFIID to the TATA element, and substituted for the TFIIA transcription activity in a reconstituted in vitro system. The heDAP fraction also behaved like TFIIA in its ability to form a promoter-TFIID-TFIIA complex and to recruit TFIIB to such a complex. The interaction of DAPs with TFIID can confer heat-resistance (47 degrees C) on recombinant yeast or human TFIID. SDS-PAGE analysis revealed that three polypeptides from HeLa extracts specifically bound to yTFIID columns (heDAP35, heDAP21, and heDAP12). These data suggest that a multi-subunit transcription factor with the properties of TFIIA can bind to TFIID in the absence of DNA.

Base Sequence