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Biomedical subjects

F Yeh

Publications and source records attributed to F Yeh.

8 recordsLinked to original sources
PubMed2006

Identification of quantitative trait loci (QTL) for oil and protein contents and their relationships with other seed quality traits in Brassica juncea.

A detailed RFLP-genomic map was used to study the genetics of oil, seed and meal protein and sum of oil and seed/meal protein contents in a recombinant doubled-haploid population developed by crossing black- and yellow-seeded Brassica juncea lines. Two yellow seed color genes (SC-B4, SC-A6) and one QTL for erucic acid content (E(1b)) showed pleiotropic effect for oil, protein and sum of oil and seed/meal protein contents. Six (O-A1, O-A6, O-A9, O-B3, O-B4, O-B5) and five (SP-A1, SP-A9, SP-B4, SP-B6, SP-C) QTLs were significant for oil and seed protein contents, respectively. Tight linkage of three of these QTLs (SP-A1, SP-A9, SP-B4, O-A1, O-A9, O-B4), with opposite effects, poses challenge to the plant breeders for simultaneous improvement of negatively correlated (r = -0.7**) oil and seed protein contents. However, one QTL for oil content (O-B3) and two for seed protein content (SP-B6, SP-C) were found to be unlinked, which offer the possibility for simultaneous improvement of these two traits. QTLs significant for meal protein (MP-A1, MP-A6, MP-A9, MP-B5, MP-B6) were significant at least for oil, seed protein or sum of oil and seed/meal protein contents (T-A6, T-A7, T-B4, T-B5). Sum of oil and seed protein contents and sum of oil and meal protein contents had a perfect correlation, as well as same epistatic interactions and QTLs with similar additive effect. This indicates that protein in seed or meal has practically the same meaning for breeding purposes. Epistatic interactions were significant for the quality traits, and their linkage reflected association among the traits.

Agriculture↗
PubMed2003

RFLP linkage analysis and mapping genes controlling the fatty acid profile of Brassica juncea using reciprocal DH populations.

An RFLP linkage map, comprising 300 linked and 16 unlinked loci, was constructed using reciprocal DH populations of Brassica juncea. The linked loci were organized into 18 linkage groups and seven unlinked segments, covering a total map distance of 1,564 cM. The A and B genomes were identified. The chi(2) test showed that 96.1% of the common intervals in the two populations differed non-significantly for recombination fractions, thus strongly suggesting the absence of sex-based differences for recombination fractions in B. juncea. Two QTLs, E(1a) and E(1b), significantly affected erucic acid content, and individually explained 53.7% and 32.1%, respectively, and collectively 85.8% of the phenotypic variation in the population. The QTLs E(1a) and E(1b) showed epistasis, and the full model including epistasis explained nearly all of the phenotypic variation in the population. The QTLs E(1a) and E(1b) were also associated with contents of oleic, linoleic and linolenic acids. Three additional QTLs (LN(2), LN(3) and LN(4)) significantly influenced linolenic acid content. The QTL LN(2) accounted for 35.4% of the phenotypic variation in the population. Epistatic interactions were observed between the QTLs E1a and LN(2). The stability of the detected QTLs across years and locations, and breeding strategies for improving the fatty acid profile of B. juncea, are discussed.

Canada↗
PubMed2003

Molecular mapping of seed aliphatic glucosinolates in Brassica juncea.

An RFLP genomic map with 316 loci was used to study the inheritance of aliphatic glucosinolates in Brassica juncea using doubled-haploid (DH) populations developed from a cross between RLM-514, an agronomically superior non-canola quality B. juncea (high erucic acid and high glucosinolates), and an agronomically poor canola quality B. juncea breeding line. Two QTLs (GSL-A2a and GSL-A2b) associated with 3-butenyl were consistent across years and locations, and explained 75% of the phenotypic variance in the population. Three QTLs (GSL-A2a, GSL-F, GSL-B3) affected 2-propenyl and explained 78% of the phenotypic variance in the population. For total aliphatic glucosinolates, five QTLs explained 30% to 45% of the total phenotypic variance in the population in different environments. Several QTLs (GSL-A7 and GSL-A3) were highly inconsistent in different environments. Major QTLs (GSL-A2a and GSL-A2b) associated with individual glucosinolates were non-significant for total aliphatic glucosinolates. A marker-assisted selection strategy based on QTLs associated with individual glucosinolates rather than total aliphatic glucosinolates is proposed for B. juncea.

Chromosome Mapping↗
PubMed2001

Dislocation-controlled perforated layer phase in a PEO- b-PS diblock copolymer.

Small angle x-ray analyses show that the shear-induced hexagonal perforated layer phase in a poly(ethylene oxide)- b-polystyrene diblock copolymer consists of trigonal (R3;m) twins and a hexagonal (P6(3)/mmc) structure, with trigonal twins being majority components. Transmission electron microscopy reveals that the hexagonal structure is generated through sequential intrinsic stacking faults on the second layer from a previous edge dislocation line, while the trigonal twins are formed by successive intrinsic stacking faults on neighboring layers due to the plastic deformation under mechanical shear.

Journal Article↗
PubMed1991

The malZ gene of Escherichia coli, a member of the maltose regulon, encodes a maltodextrin glucosidase.

We have characterized a maltodextrin glucosidase, previously described as a maltose-inducible, cytoplasmic enzyme that cleaves p-nitrophenyl-alpha-maltoside in Escherichia coli. The gene encoding the enzyme activity, referred to as malZ, is located at 9.3 min on the chromosomal map. We cloned the gene in a high copy number vector and purified the enzyme. It is a monomer, with an apparent molecular weight of 65,000. The enzyme degrades maltodextrins, ranging from maltotriose to maltoheptaose, to shorter oligosaccharides, the final hydrolysis products being maltose and glucose. We measured the kinetic parameters, Km and Vmax, for the hydrolysis to glucose of the five different substrates. The binding of the substrate is enhanced by increasing the number of glucosyl residues in the maltodextrin. In contrast, the maximum rate of hydrolysis (Vmax) is fastest for maltotriose. To study the mode of action of the enzyme, we quantitatively measured the amount of free glucose liberated from the different maltodextrin substrates after a long incubation. More glucose is liberated from the long dextrins, as compared to the shorter ones, showing that the primary hydrolysis product was glucose, not maltose. Furthermore, [14C]maltotriose, specifically labeled at the reducing end, was hydrolyzed to [14C]glucose and unlabeled maltose. These data demonstrate that the malZ gene product is a maltodextrin glucosidase, liberating glucose from the reducing end of malto-oligosaccharides. The nucleotide sequence of malZ and the deduced amino acid sequence showed that malZ encodes a protein with a molecular weight of 68,960. Homology to glucosidases, alpha-amylases, and pullulanases were observed. Conserved regions thought to represent active sites in dextrin hydrolases were found in the MalZ protein.

Amino Acid Sequence↗
PubMed1988

Sequential dose injections. A new technique for technetium-99m colloid gastrointestinal bleeding studies.

For Tc-99m colloid bleeding studies to be positive, the patient must be actively bleeding while the colloid is circulating in the blood pool. A simple technique of sequential dose injections (SDI) is presented where five injections of 2 mCi each are made at 5-minute intervals. Image acquisition is performed after each injection. This technique results in an increase in the effective plasma residence time of the colloidal particles from 10-15 minutes to 35-40 minutes. A case report is presented in which the bleeding site was identified only after the fifth serial injection of a fractionated dose of Tc-99m microaggregated albumin colloid.

Aged↗
PubMed1979

Simple computer quantitation of spleen-to-liver ratios in the diagnosis of hepatocellular disease.

Increased splenic uptake of radiocolloids is a helpful sign in the scintigraphic diagnosis of various hepatocellular diseases, but little attempt has been made to quantify this physiologic phenomenon. We have devised a simple computer method that compares average splenic activity to average right-lobe liver activity. The method is reproducible (r = 0.97) and exhibits little interobserver variation (r = 0.99). One hundred clinically normal subjects were found to have a nearly symmetrical distribution of S/L ratios around a mean of 0.77, with a s.d. of 0.20. Fifteen subjects normal by biopsy were found to have a similar mean spleen-to-liver (S/L) ratio of 0.74. Based upon a normal range of 0.37 to 1.17 (0.77 +/- 2 s.d.), elevated S/L ratios were found in fatty metamorphosis (85%), cirrhosis (67%), and chronic hepatitis (43%). Abnormal S/L ratios in the range from 1.17 to approximately 1.4 were not visually obvious. Overall sensitivity of the S/L ratio in these three diseases is 69%. When combined with the other scintigraphic indications of hepatocellular disease (nonhomogenous colloid uptake, hepatomegaly, splenomegaly, and bone-marrow colloidal uptake), the liver scan was found to have a sensitivity of 93%.

Colloids↗