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Biomedical subjects

Y L Fan

Publications and source records attributed to Y L Fan.

At least 19 recordsLinked to original sources
PubMed2003

Fabrication and performance of a medium-dependent SiO2/Si photonic heterostructure device.

An optical device based on a photonic bandgap heterostructure is designed, fabricated, and characterized. The sample contains two sets of Si/SiO2 photonic crystals with different periods. When the device is working in air, it reflects omnidirectionally both TE and TM mode lights at the wavelength near 1.3 microm. The reflectivity measured in the bandgap is higher than 98% in an incident angle range 0 degrees-70 degrees. When the device is surrounded with silica (n > 1.33), it permits the total transmission for the TM mode but prevents the TE mode from propagating, thus behaving as a polarization splitter. The experimental extinction ratio of the reflected TE/TM is approximately 31 dB. The uniformity of the device performance over a large sample area is demonstrated.

Journal Article↗
PubMed2001

[Cloning of neutral phytase gene nphy from Bacillus subtilis and its expression in Escherichia coli].

The gene encoding the neutral phytase nphy was cloned from Bacillus subtilis by polymerase chain reaction (PCR). Nucleotide sequence analysis of nphy revealed the presence of an open reading frame of 1152 bp coding for 383 aa. The start codon was followed by a sequence coding for a putative signal peptide of 26 aa in length. The nphy without original signal peptide encoding sequence was cloned into E. coli expression plasmid pTYB40. The result of SDS-PAGE of the phytase expressed in E. coli showed that the nphy had been overexpressed. The expressed phytase was over 40% of the total soluble protein of E. coli, and has normal bioactivity.

6-Phytase↗
PubMed2000

[Molecular biology and gene engineering of phytase].

Phytase is a new-style enzyme used in monogastric animal feed. The addition of phytase to feed can increase phosphorus availability, decrease environmental phosphorus pollution and improve the performance of animal. This paper reviews the research progress and trend in recent studies related to molecular biology and gene engineering of phytase.

6-Phytase↗
PubMed2000

[Insect-resistant transgenic poplar expressing AaIT gene].

Insect-specific scorpion neurotoxin AaIT gene inserted into a binary vector was transferred into a hybrid poplar clone N-106(P. deltoides x P. simonii) growing in the Southern of China. We obtained sixty-two regenerated plants by Agrobacterium tumefaciens transferring system. PCR and PCR-Southern analysis showed that AaIT gene was incorporated into the genome of some recovered poplar plants. One of the transformed plants named A5 was significantly resistant to feeding by first instar larvae of Lymantria dispar, compared with the untransformed control plant. It caused a decrease in leaf consumption by larvae, a lower larval weight gain and a higher larval motality rate of Lymantria dispar. ELISA analysis proved that AaIT gene was expressed in this transfomed poplar plant.

Animals↗
PubMed2000

[Regeneration of HNP transgenic alfalfa plants by Agrobacterium mediated gene transfer].

Transgenic plants regenerated from cotyledons of M. sativa L. infected using Agrobacterium tumefaciens A281 with plasmid pBF649 containing a gene encoding protein of high sulfur-amino acid content (HNP) were obtained successfully. The plants grew and fertiled well in field. Cotyledon explants were better recipient for transformation of M. sativa L. Environment of suitable temperature (15 degrees C) and high humidity on high viability of the plants transplanted into soil were essential conditions.

Amino Acids, Sulfur↗
PubMed2000

[Research on improving rice resistance to the pest by B.t. and SBTi genes].

B.t. gene alone or and SBTi gene together were introduced into two elite indica rice varieties grown in South China by bombardment. And 21 independent transgenic lines containing B.t. gene and 4 independent transgenic lines containing B.t. gene and SBTi gene were obtained. Molecular and genetics analysis for R1 plants showed integration of multiple transgenes occurred at one genetic locus. Northern blot result proved B.t. gene expressed in R2 transgenic plants stably. Bioassays using R2 transgenic plants with leaf-folder (Cnaphalocrosis medinalis), indicated that transgenic rice plants are more resistant to the pest than untransformed control plants. And those transgenic plants containing B.t. and SBTi genes showed more resistance compared with those plants containing B.t. gene.

Bacillus thuringiensis Toxins↗
PubMed1999

[Fertile transgenic indica rice from microprojectile bombardment of embryogenic callus].

A reproducible and efficient transformation system for indica rice was developed based on microprojectile bombardment of embryogenic callus. Sufficient globular embryogenic calli were produced within 2-6 weeks from 3-4 week old calli derived from mature embryos. The embryogenic calli were bombarded with the plasmid pFWZ16 containing bar gene and B.t. delta-endotoxin gene. Selection, pre-regeneration, regeneration and rooting were carried out on media with 2-4 mg/L Basta. Partial desiccation treatment was used to increase the efficiency of regeneration. Transformed plantlets were recovered within 4-5 months after mature seeds were plated. From 821 bombarded embryogenic calli of two elite rice varieties popularized in South China, 477 Basta resistant plants of 48 lines were obtained. Results of PCR, Southern blotting, RNA dot blotting, and topical application of Basta demonstrated that the foreign bar gene and B.t. gene were integrated into the genome of transgenic rice plants, and also expressed. 87.5% of the transgenic plants were fertile. Mendelian segregation of the foreign genes was indicated by Basta application and Southern blot analysis of R1 plants.

Blotting, Southern↗
PubMed1997

[Effects of microinjection of sodium glutamate and glycine into ventrolateral nucleus of tractus solitarius on the discharges of phrenic nerve in rabbits].

The effects of microinjection of sodium glutamate and glycine into ventrolateral nucleus of tractus solitarius (VLNTS) on the discharges of phrenic nerve were observed on 40 anaesthetized, vagotomized, paralyzed and artificially ventilated rabbits. The results were as follows: Phrenic nerve discharges were increased, inspiratory duration prolonged, expiratory duration shortened and respiratory frequency not changed by microinjection of sodium glutamate into VLNTS. While by microinjection of glycine, phrenic nerve discharges were decreased, even abolished, inspiratory duration shortened, expiratory duration irregularly prolonged and respiratory frequency decreased. The above results show that VLNTS exert important effects on the genesis of respiratory rhythm.

Animals↗
PubMed1995

[Effect of microinjection of sodium giutamate and glycine into ventrolateral nucleus of tractus solitarius on the evoked potentials of arcuatus nucleus in rabbits].

Experiments were performed on 66 anaesthetized, vagotomized, paralyzed and artificially ventilated rabbits. The effects of microinjection sodium glutamate and glycine into ventrolateral nucleus of tractus solitarius (VLNTS) on hypothalamic arcuatus nucleus evoked potentials were observed. The main results obtained were as follows: (1) Phrenic nerve discharges were increased and the amplitude of P2 and N2 waves of arcuatus nucleus evoked potentials were decreased by microinjection of sodium glutamate into VLNTS. Phrenic nerve discharges were decreased and the amplitude of P2 and N2 waves of arcuatus nucleus evoked potentials were increased by microinjection of glycine into VLNTS. (2) After intravenous injection of naloxone, the phrenic nerve discharges could still be excited by microinjection of sodium glutamate as before, but the effects on the amplitude of P2 and N2 waves of arcuatus nucleus evoked potentials, unlike that of sodium glutamate, were reversed. The results suggest that the excitatory action of respiratory neurons in the VILTS may affect on the sensory function of arcuatus nucleus. The mechanism involved was discussed.

Animals↗
PubMed1993

The endosperm-specific expression of a rice prolamin chimaeric gene in transgenic tobacco plants.

The 5' upstream region (-680 to +40), containing the potential promoter and complete signal peptide coding sequence of the rice seed storage prolamin gene was amplified in vitro using the polymerase chain reaction from the genome of Chinese rice cultivar Zhonghua 8. The physical map and DNA sequence analysis show strong homology with the 5' flanking region of the rice prolamin gene published by Kim and Okita (1988a). No change in the signal peptide coding sequence and a long leader sequence with several small open reading frames were found. The chimaeric gene containing the 5' flanking region of the prolamin gene (-680 to -18) was transcriptionally fused with the beta-glucuronidase (GUS) reporter gene and the fusion junction was confirmed by both physical mapping and DNA sequence analysis. The resultant chimaeric gene was used to transform tobacco explants, using the Ti binary system of Agrobacterium tumefaciens LBA4404. Three transgenic tobacco plants with as many as 20 copies of the chimaeric GUS gene (confirmed by dot and Southern hybridization) were analysed further. Histochemical analysis revealed GUS activity in the endosperm tissue of tobacco seed at the developmental stage about 20 days after flowering (DAF). No GUS activity was found in leaves, stems, roots and flowers of the transgenic tobacco plants. Therefore, we conclude that the 5' upstream region from -680 to -18 was sufficient to confer the endosperm-specific expression of the rice prolamin gene.

Base Sequence↗
PubMed1993

5'-flanking region responsible for endosperm-specific expression of rice prolamine chimeric gene in transgenic tobacco.

The 5' upstream region (-680-(+)40) containing the complete signal peptide coding sequence of the rice seed storage prolamine gene was amplified in vitro with polymerase chain reaction from the genome of Chinese super rice cultivar Zhonghua 8. Physical map and DNA sequence analysis showed strong homology with the 5'-flanking region of rice prolamine gene reported by Kim in 1988. No changes in the signal peptide coding sequence and a long leader sequence with several small ORFs were found. Chimeric gene containing 5'-flanking region of the prolamine gene has been transcriptionally fused with the beta-glucuronidase reporter gene. The fusion junction was confirmed by both physical map and DNA sequence analysis. The resultant chimeric gene was used to transform the tobacco explants by Ti binary system of Agrobacterium tumefaciens LBA4404. With dot and Southern blotting hybridization, three transgenic tobacco plants with the copies of chimeric GUS genes as many as 20 were obtained. Histochemical analysis revealed that the GUS activity in the endosperm tissues of tobacco seeds at the developmental stage was about 20 DAP. No GUS activity was found in leaves, stems, roots and flowers of the transgenic tobacco plants. Therefore, we concluded that the 5'-upstream cis-elements from -680 to -18 were enough to confer the endosperm-specific and temporal expression of rice prolamine gene.

Base Sequence↗
PubMed1991

Location of 43 kD mosquito-larvicidal toxin gene of highly toxic Bacillus sphaericus 10.

The direct evidence of the location of the mosquito-larvicidal gene of Bacillus sphaericus 10 (isolated from Jiangsu Province of China) on megaplasmid pFW1 was given by molecular cloning. The clone (pFL109) containing the 1.4 kb HindIII DNA fragment from pFW1 expressed the mosquito-larvicidal toxin protein (43 kD). The location of the gene coding for the 43 kD toxin protein within the XhoI B fragment on the restriction map of pFW1 was confirmed by Southern blotting using the 1.4 kb HindIII DNA fragment as a probe. The non-toxic strains of Bacillus sphaericus were revealed to be 43 kD toxin gene deletion mutants by Southern and Western analyses. The 1.4 kb HindIII fragment of pFL109 can be used as a probe for differentiating the non-toxic strains of Bacillus sphaericus from the toxic ones.

Animals↗
PubMed1990

Plant regeneration from protoplasts of a super Chinese rice (Oryza sativa L.) cultivar--Zhonghua NO.8.

Green rice plants were regenerated from protoplasts, which were derived from cell suspension of Oryza sativa L. cut. Zhonghua No. 8, a super Chinese rice cultivar with high productivity, good quality and high resistance to both bacterial blight and blast. The embryogenic calli were initiated from mature embroys. It took about 4 months to establish the cell suspenion. The regeneration plants from protoplasts were obtained in 2 months after the isolation of protoplasts.

Cells, Cultured↗
PubMed1990

Cloning and expression of mosquito larvicidal protein gene from a highly toxic local strain of Bacillus sphaericus.

Bacillus sphaericus strain 10 (BS10), isolated from Jiangsu Province of China, is highly toxic to the mosquito larvae. During sporulation, BS10 produces a parasporal crystalline protein which is toxic to the larvae of a number of mosquito species, and extremely toxic against the larvae of Culex pipiens. Using the Escherichia coli cloning vector pAT153, two clones which hybridized with the synthesizing 18-bases oligonucleotides probe have been obtained. One of the recombinants, TG1 (pFL37), contains a 4.0 kb HindIII DNA fragment from BS10, and produces the 43 kd larvicidal toxin protein. Western blotting analysis and biological assay of mosquito larvicidal activity confirm that larvicidal toxin gene of BS10 is expressed in E. coli.

Animals↗
PubMed1989

Molecular cloning and expression of Bacillus thuringiensis subsp. galleriae insecticidal crystal protein genes in Escherichia coli.

The location of the toxin gene of B. thuringiensis subsp. galleriae (H5ab) on the Mr-130Md plasmid is determined by molecular cloning. Double digestion fragments (BamHI and SalI) and PstI restriction fragments as well, from the 130 Md plasmid, of B. thuringiensis subsp. galleriae, are ligated with the cloning vector pAT 153 respectively and transformed into E. coli strain HB 101. Out of 208 transformants, three colonies (FG2, FG9, FG19) give positive hybridization reaction using the HD-1 delta-endotoxin gene as a probe. They are presumed to contain the delta-endotoxin gene of B. thuringiensis subsp. galleriae. Western blot assays indicate that Mr-130 kDal and 68 kDal, crystal proteins produced by clone FG2 react with anticrystal protein antibody. The protein extracts of clone FG2 are lethal to Ostrinia furnacalis (Guenee). This is the first report with regard to the cloning and expression of the B. thuringiensis subsp. galleriae (H5ab) delta-endotoxin gene.

Bacillus thuringiensis↗
PubMed1989

Restriction map of large plasmid pFW1 in Bacillus sphaericus strain 10.

Some strains of Bacillus sphaericus have been found to be toxic to mosquito larvae (1). They differ from Bacillus thuringiensis var. israelensis (BTI) (2,3) in the following aspects: BTI is relatively ineffective in polluted water, and its residual activity in most habitats is limited to a few days after treatment, whereas BS isolates are effective in such habitats, particularly against species of Culex; BS also remains effective longer, as a result of either persistence or recycling. B. sphaericus strain 10 (BS10) was isolated by the Lixiahe Institute of Agricultural Sciences in Jiangsu Province. Its larvicidal activity is much higher than that of BS1593, which was recommended by the World Health Organization for widespread use as a standard strain (1). The mosquito-larvicide gene of BS1593 has been cloned and expressed in E. coli and B. subtilis (4, 5). In the present study, BS10 was investigated to establish whether it contains the plasmid and whether homology exists between the mosquito-larvicide gene in BS and that in BTI.

Animals↗
PubMed1988

Complementation of mutants of the stability locus of IncFII plasmid NR1. Essential functions of the trans-acting stbA and stbB gene products.

A series of unstable mutants of the stability (stb) locus of IncFII plasmid NR1 was subjected to a complementation analysis. The mutant collection included plasmids with point, insertion and deletion mutations in stb. These mutations affected the tandem genes stbA and stbB, which encode stability proteins StbA and StbB, or the PAB transcription promoter, which is located upstream from stbA in a region that contains an essential cis-acting site. Deletion mutants that lacked the region containing promoter PAB could not be complemented (stabilized) by providing StbA and StbB in trans. Deletion mutants that lacked stbA and stbB but retained the PAB region were complemented in trans but required both StbA and StbB, indicating that both proteins were essential for stable inheritance. stbA- point mutants were complemented in trans by either wild-type or stbA+ stbB- clones of the stability region. However, mutants with insertions in stbA were complemented only by wild-type clones, which suggested the insertions were polar on expression of the downstream stbB gene. A plasmid with a stbB- point mutation was complemented in trans by wild-type but not by stbA- stbB+ clones. In addition, plasmid clones that expressed StbB in the absence of StbA caused destabilization of (were incompatible with) stb+ derivatives of NR1 in trans, whereas clones that expressed only wild-type StbA or both StbA plus StbB did not. Plasmid clones that contained only the essential cis-acting PAB region did not cause destabilization of stb+ plasmids in trans. These results suggest that an excess of StbB protein provided in trans may cause a depletion of the essential StbA protein. Therefore, these results may be consistent with the hypothesis that StbB is an autorepressor of the stbAB operon.

Bacterial Proteins↗