Biomedical subjects

H R Huang

Publications and source records attributed to H R Huang.

5 recordsLinked to original sources

PubMed2001

Retrotransposition of a yeast group II intron occurs by reverse splicing directly into ectopic DNA sites.

Group II introns, the presumed ancestors of nuclear pre-mRNA introns, are site-specific retroelements. In addition to "homing" to unoccupied sites in intronless alleles, group II introns transpose at low frequency to ectopic sites that resemble the normal homing site. Two general mechanisms have been proposed for group II intron transposition, one involving reverse splicing of the intron RNA directly into an ectopic DNA site, and the other involving reverse splicing into a site in RNA followed by reverse transcription and integration of the resulting cDNA by homologous recombination. Here, by using an "inverted-site" strategy, we show that the yeast mtDNA group II intron aI1 retrotransposes by reverse splicing directly into an ectopic DNA site. This same mechanism could account for other previously described ectopic transposition events in fungi and bacteria and may have contributed to the dispersal of group II introns into different genes.

Base Sequence↗

PubMed2001

[Cluster analysis of Dendrobium by RAPD and design of specific primer for Dendrobium candidum].

OBJECTIVE: To analyze the genetic relationship of Dendrobium and design a specific primer to differentiate Dendrobium candidum effectively. METHOD: Random amplified polymorphic DNA (RAPD) technique was used to analyze the genetic relationships of 26 species of Dendrobium and one species of Ephemerantha. Dendrogram was constructed by UPGMA. According to the sequence of DNA fragment selected, Sangon 18 primer had been extended from 3' extreme to 20 bp in order to form a specific primer. RESULT AND CONCLUSION: This primer can be used to distinguish Dendrobium candidum from other Dendrobium effectively. Such a technique provides a new way for the identification of Chinese traditional medicines.

Cluster Analysis↗

PubMed1997

Purification and cloning of carp nephrosin, a secreted zinc endopeptidase of the astacin family.

We have purified a secreted proteinase of 23 kDa from carp head kidney by sequential column chromatography on a Reactive Blue 72-agarose dye affinity column and an FPLC Mono-P column. The secretion of this proteinase from carp head kidney can be stimulated by high concentrations of potassium. Since the carp proteinase is present mainly in the head kidney, kidney, and spleen (all of which are lymphohematopoietic organs), it is named nephrosin. The carp nephrosin is most sensitive to metal chelators, but not to inhibitors specific for other classes of proteinases. A cDNA clone has been isolated from a carp head kidney cDNA library by immunoscreening with a polyclonal antiserum raised against purified nephrosin. The cloned cDNA is 1086 base pairs in length and has an open reading frame encoding a protein of 273 amino acids, including a 19-amino acid signal peptide and 56-amino acid propeptide. The deduced amino acid sequence shows moderate levels of identity to medaka HCE1 (52.5%), medaka LCE (50.7%), crayfish astacin (33.2%), murine meprin-alpha (34%), and murine meprin-beta (33.5%), all members of the astacin family of zinc endopeptidases. Nephrosin is the first member of the astacin family found in lymphohematopoietic tissues.

Adrenal Cortex↗

PubMed1992

Internal jugular phlebectasia.

Phlebectasia, defined as abnormal venous dilation, may occur in a number of different sites. Two cases with definite diagnosis of internal jugular phlebectasia were reported. The first case was a 6-year-old girl with a bulging mass on right neck for 3 years. Angiography and CT scan showed definite diagnosis, and the bulging mass was resected from the internal jugular vein (IJV). The second case was a 66-year-old female patient, also complained of a bulging mass on her right neck. Sonogram and CT scan also showed the same diagnosis. Because it did not bother the patient, she was just under close observation. From the three kinds of diagnostic modalities, we found sonography is an effective technique because of its clarity, safety and low cost.

Aged↗

PubMed1990

In vivo cloning of proline genes and its expression in Escherichia coli.

The wild type proA+, B+ genes of E. coli were cloned in vivo using a plasmid containing a mini-Mu replicon, pEG5005. The cloning frequency was about 1.46 x 10(-3)/Kanr transductant. Genetic and biochemical analysis of these clones indicated that the proA+, B+ genes are on the plasmid pEG5005. The secretion of proline were assayed for 500 Pro+ clones. However, no proline accumulation was detected. A Pro+ clone pPR3 was mutagenized in vivo by NTG and the mutants resistant to D-proline were obtained. One of the Dpr mutants pPR7 was found to produce 0.35 mg/ml proline in a proA B deletion strain. When pPR7 was transferred into a proline producing strain, the yield of proline increased up to 2.5 mg/ml, which is 7 and 2.5 times higher than that of the donor and recipient respectively. The physical maps of pEG5005 and pPR3 were roughly established.

Chromosome Mapping↗