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Biomedical subjects

G S Li

Publications and source records attributed to G S Li.

17 recordsLinked to original sources
PubMed1991

Further investigation on nuclear transplantation in different orders of teleost: the combination of the nucleus of Tilapia (Oreochromis nilotica) and the cytoplasm of Loach (Paramisgurnus dabryanus).

The nucleus of a blastula cell from Tilapia (Oreochromis nilotica, family Cichlidae, order Perciformes) was transplanted into an enucleated egg of Loach (Paramisgurnus dabryanus, family Cobitidae, order Cypriniformes). From among 3747 nucleo-cytoplasmic hybrid (NCH) eggs two NCH larval fish (0.05%) were obtained; one died on the 6th day and the other died on the 12th day after the operation. Morphological examinations showed that both NCH larval fish had developed normally with an opened mouth except they could not take food after complete utilization of their egg yolk on the 5th day of development. The possible mechanisms for obtaining such inter-order NCH larval fish are discussed. This is the first report indicating that inter-order NCH larval fish can be obtained in spite of their evolutionary divergence.

Animals↗
PubMed1990

The study on transgenic mice.

The structural gene coding for human growth hormone (hGH) was fused to the promoter of the mouse gene for metallothionein-1. These fusion genes were introduced into pronuclei of the fertilized eggs of mice by micro-injection. We have injected MT-hGH genes into 121 mouse eggs which were transferred into the oviducts of eleven pseudo-mothers. Seven out of eleven mothers gave birth. Forty-three litters were born. These litters were grown-up and their tails were cut for isolating the DNA. The DNA of each mouse was examined by dot hybridization and Southern blotting. We found that eighteen mice had incorporated the fusion genes and grew larger than control mice. Synthesis of human growth hormone was induced further by zinc, which normally induces metallothionein gene expression. We also isolated the RNA from the livers of transgenic mice. The RNA was hybridized with hGH gene. It showed that on the transcription level the hGH gene was transcribed into mRNA in the transgenic mice. Using the same method to examine the second and third generation of the transgenic mice, we found that the incorporated gene could be inherited for generations. But the body-weight of transgenic mice appeared to decrease in the progeny. The offspring obtained from different combinations of parents (carrying or not carrying hGH gene) were different.

Animals↗
PubMed1990

Developmental incompatibility between cell nucleus and cytoplasm as revealed by nuclear transplantation experiments in teleost of different families and orders.

Teleosts from different families and orders were used as materials for nuclear transplantation experiments. (1) The nuclei of goldfish (Carassius auratus, family Cyprinidae, order Cypriniformes) were transplanted into the enucleated egg cytoplasm of loach (Paramisgurnus dabryanus, family Cobitidae, order Cypriniformes) and vice-versa. (2) The nuclei of Tilapia (oreochromis nilotica, order Perciformes) were transplanted into the enucleated egg cytoplasm of goldfish (Carassius auratus, order Cypriniformes). The chromosome number of the nucleus donor fish is different from that of the cytoplasmic recipient fish in each of the two combinations. In the first case, only a few early nucleo-cytoplasmic hybrid (NCH) larval fish were obtained in each combination. In second case, even though a high percentage of NCH blastulas were also obtained, the majority of them died at the same developmental stage, except a few which survived until early gastrula stage. The examination of the metaphase chromosome figures of the NCH blastulas or embryos obtained in all three combinations indicated that they were of nucleus-donor type. The developmental rates of all the NCH eggs were similar to those of cytoplasmic-recipient type. Scanning electronmicroscopy examination showed that the morphology of NCH blastula cells, which were obtained from the combination of Tilapia nucleus and goldfish cytoplasm, manifested obviously abnormal features and the cells were arrested at different stages of cell disintegration. Two-dimension polyacrylamide gel electrophoretograms of the homogenates of Tilapia, goldfish and their NCH blastula cells showed that the protein synthetic pattern of NCH blastula was similar to that of Tilapia nucleus type. The results of experiments which failed to obtain NCH adult fish in all three combinations can be explained as a result of developmental incompatibility between the donor nucleus and the enucleated recipient egg cytoplasm, which were from distantly related fish species. And the chromosome numbers of all the component fish of the three combinations which were examined in the experiment and shown to be quite different from each other in the tested fish, should not be overlooked as one of the essential factors causing the developmental incompatibility in NCH fish in this experiment.

Animals↗
PubMed1988

A new bilirubin-degrading enzyme from orange peels.

A novel enzyme activity that catalyzes the degradation of unconjugated bilirubin (Bu) has been demonstrated in extracts of the peels of edible oranges. Unlike the few known bilirubin-oxidizing enzymes, the orange enzyme does not produce biliverdin as a product, does not seem to require oxygen, and has a unique absorption spectrum of its products. Even at the crude stage, the enzyme has a specific activity that is 10 and 20 times higher, respectively, than those reported for the crude or partially purified Bu-degrading enzymes from mushrooms and rat liver. The enzyme has a pH optimum near 7.5 and a Km value of 50-100 microM for Bu. The enzyme is remarkably stable, retaining over 50% activity after prolonged digestion with proteinase K or heating at 100 degrees C. Similar treatments inactivated the bilirubin oxidase from Myrothecium verrucaria MT-1. The enzyme is poorly soluble in water but can be partially solubilized with cholic acid, with a doubling in specific activity.

Bilirubin↗
PubMed1985

Keshan disease: an endemic cardiomyopathy in China.

Keshan disease is an endemic cardiomyopathy in China. Morphologically, the condition is characterized by multifocal necrosis and replacement fibrosis of the myocardium, resulting in acute or chronic heart failure. Some patients with Keshan disease show the clinical features of congestive (dilated) cardiomyopathy, but the pathologic features of the two conditions are different. The etiology of Keshan disease remains unknown. It is likely that numerous agents work synergistically to cause the disease.

Adolescent↗
PubMed1984

Nuclear transplantation in teleosts. Hybrid fish from the nucleus of crucian and the cytoplasm of carp.

Hybrid fish are obtained from the combination of nucleus and cytoplasm from two genera of fresh-water teleosts using the technique of nuclear transplantation (i.e. the combination of the nucleus of crucian (Carassius auratus) and the cytoplasm of carp (Cyprinus carpio]. Morphological characteristics of these hybrid fish that have been examined so far indicate that some features such as barbs, pharyngeal teeth, the number of scales along the lateral line, and the number of vertebrae are similar to those of crucian. Some of the hybrid fish grow to normal adult fish.

Animals↗
PubMed1975

Ergot alkaloids. Synthesis of 6-methyl-8-ergolenes as inhibitors of prolactin release.

A general synthetic route from elymoclavine (4a) to a variety of C-17 substituted 8-ergolenes has been established. [The C-17 position is the carbon attached to C-8 of the ergoline (1) skeleton as indicated in structure 2.] This route involves displacement reactions on the allylic chloride (4h) prepared from 4a by reaction with thionyl chloride. Conversion of the naturally occurring tricyclic clavines, chanoclavine I (5a) and isochanoclavine I (5b), to the tetracyclic clavine, agroclavine (4i), has been achieved. The new compounds prepared were tested for prolactin-inhibiting ability and were found to possess activity. One of the compounds prepared, 6-methyl-8-ergolenylacetamide (4k), was very potent, comparing favorably in activity to the best prolactin inhibitors reported to date.

Animals↗
PubMed1975

Effect of hydrogen peroxide treatment on the nutritional quality of rapeseed flour fed to weanling rats.

The effect of treating rapeseed flours with hydrogen peroxide on the glucosinolate content and nutritional value of the protein was examined. Four flours were prepared from Target variety rapeseed (Brassica napus) by dehulling and defatting the seed (sample RF), by heat treating and water washing the dehulled seed prior to defatting (sample WWRF), and by treating a part of samples RF and WWRF with solutions of 7 and 3% hydrogen peroxide, respectively. Chemical analysis showed that the hydrogen peroxide treatment lowered the glucosinolate content of the flour but was not as effective as the water extraction. The hydrogen peroxide treatment also oxidized methionine to its sulfoxide and sulfone and cysteine to cysteic acid. In the first experiment, weanling rats were fed for 3 weeks diets in which casein or each of the flour preparations provided 5, 10, or 20% protein. Rats fed the high glucosinolate-containing flour (sample RF) at the 10 to 20% protein level died, while those fed 5% survived but lost weight. Those fed the hydrogen peroxide-treated flours survived, but weight gains and food consumption were low compared with the values of the caseinor WWRF-fed groups. Rats fed sample RF exhibited enlarged thyroids. Those fed the peroxide-treated samples had high plasma levels of methionine sulfoxide and sulfone. In the second experiment, additions of 0.15 or 0.30% methionine to the 10% protein diets resulted in increased weight gains of the groups fed the peroxide-treated flours. It was concluded that the hydrogen peroxide treatment was effective in reducing the glucosinolate content of the rapeseed flour. However, the production of the oxidized sulfur amino acids, in particular methionine sulfone, reduced considerably the nutritional value of the protein.

Animal Feed↗