Biomedical subjects

Jun-Feng Li

Publications and source records attributed to Jun-Feng Li.

5 recordsLinked to original sources

PubMed2007

Effects of hypomagnetic field on noradrenergic activities in the brainstem of golden hamster.

Previous studies found that elimination of the geomagnetic field (GMF) interferes with the normal brain functions, but the underlying mechanism remains unknown. The present study examined the effects of long-term exposures to a near-zero magnetic environment on the noradrenergic activities in the brainstem of golden hamsters. Both the content of norepinephrine (NE) and the density of NE-immunopositive neurons in the tissue decreased significantly after the treatment, and the effects could be progressive with time. These variations may substantially contribute to behavioral and mood disorders reported in other studies when animals are shielded from the GMF.

Animals↗

PubMed2006

Rapid determination of gold in geological samples using flow injection solid-phase chemiluminescence.

The solid-phase chemiluminescence analysis of gold on the surface of an anion-exchange resin was studied. A method for the fast determination of gold using flow injection was established. The anion-exchange resin was used as an adsorbent of gold ion in the form of AuCl4-. The cation-exchange resin was used for the on-line separation of cations in the matrix. To obtain the best results, the preconcentration and separation conditions, chemiluminescence conditions, interfering ions and their elimination conditions were optimized. The linear range of the calibration curve of AuCl4- is from 0 microg ml(-1) to 5.00 microg ml(-1). The detection limit of AuCl4- is 0.012 microg ml(-1). The method has been used for the determination of gold in geological samples (standard ores). The results are in agreement with certified value of gold standard samples with relative standard deviation from 2.22% to 8.97%. Through the use of flow injection, the preconcentration and separation can be performed automatically.

Journal Article↗

PubMed2005

[A method for DNA template preparation using a single embryo].

We established a simple method for the preparation of DNA template from a single oocyte or early embryo by KOH/DTT-Triton X disintegration. The PCR amplification efficiency of DNA template prepared by this method was compared with that prepared by TE-proteinase K. Single oocyte, 2-cell embryo, 8-cell embryo, morula or blastocyst were separately treated by KOH/DTT-Triton X, then the DNA template was directly used to amplify mitochondrial DNA segment by PCR. The overall PCR success rate of the 3 pairs of primers was 100% (70/70), while the overall PCR success rate of single oocyte treated by TE-proteinase K was 92.9% (65/70). Difference between the two results was significant (P<0.05), and the PCR false positive rates in both groups were 0. The designed KOH/DTT-Triton X disintegrate method was efficient to the preparation of DNA template of a single early embryo. It needed only one cycle of PCR amplification to get clear aimed DNA stripe and the efficiency was high enough to meet the need of early embryonic genetic material detection.

Animals↗

PubMed2004

Inositol and phosphatidylinositol mediated mediated glucose derepression, gene expression and invertase secretion in yeasts.

Glucose repression occurs in many yeast species and some filamentous fungi, and it represses the expression and secretion of many intracellular and extracellular proteins. In recent years, it has been found that many biochemical reactions in yeast cells are mediated by phosphatidylinositol (PI)-type signaling pathway. However, little is known about the relationships between PI-type signaling and glucose repression, gene expression and invertase secretion in yeasts. Many evidences in our previous studies showed that glucose repression, invertase secretion, gene expression and cell growth were mediated by inositol and PI in Saccharomyces and Schizosaccharomyces. The elucidation of the new regulatory mechanisms of protein secretion, gene expression and glucose repression would be an entirely new aspect of inositol and PI-type signaling regulation in yeasts.

Gene Expression Regulation, Fungal↗

PubMed2004

[Progress in ooplasmic transfer].

Many studies indicated mitochondria in oocytoplasm affects obviously the fertilization of the oocytes and early embryo development. The decrease of ATP content and mitochondrial DNA(mtDNA) content, and mtDNA defects can make the fertilization of oocytes and embryo development decreased, which is the key one of reason that the reproductive ability is low in aged women and aged animal. Ooplasmic transfer increases the fertilizability of the aged oocytes and the early embryonic viability, it has led to the birth of health babies, and become a hotspot in the realm of human assisted reproduction biotechnology and animal clone. However, Ooplasmic transfer can lead to mtDNA become heteroplastic, which is the mtDNA of donor and recipient coexist in offspring. At present, how the heterogeneous ooplasm influences the embryogenesis and development is not entirely clear. This paper reviews the ooplasmic transfer in summary, the relation between ooplasm and fertilization and embryo development, the hereditary behavior of heterogeneous mitochondria DNA and it's examination after ooplasmic transfer.

Animals↗