[A new teaching mode improves the effect of comprehensive experimental teaching of genetics].

To improve the research atmosphere in genetics experimental teaching and develop students' creativity in research, we carried out a reform in comprehensive experimental teaching which is one of important modules for genetics practice. In our new student-centered teaching mode, they chose research topics, performed experiments and took innovative approaches independently. With the open laboratory and technical platform in our experimental teaching center, students finished their experiments and were required to write a mini-research article. Comprehensive experimental teaching is a scientific research practice before they complete their thesis. Through this teaching practice, students' research skills in experimental design and operation, data analysis and results presentation, as well as their collaboration spirit and innovation consciousness are strengthened.

[Research progress on the cloning of Mendel's gene in pea (Pisum sativum L.) and its application in genetics teaching].

One hundred and fifty years ago, Gregor Mendel investigated the segregation of seven traits in pea (Pisum sativum) and established the law of segregation and the law of independent assortment in genetics. After the two laws of genetics were rediscovered in 1900, the seven traits have been extensively investigated in the fields of plant physiology and biochemistry as well as in the cell and molecular levels. Recently, with the development of molecular technology in genetics, four genes for seed shape (R), stem length (Le), cotyledon colour (I), and flower colour (A) have been cloned and sequenced; and another three genes for immature pod colour (Gp), fasciation (Fa) and pod form (V) have been located in the linkage groups, respectively. The identification and cloning of the four Mendel's genes will help deeply understand the basic concept of gene in many respects: like the diversity of gene function, the different origins for gene mutation in molecular level, and the molecular nature of a dominant gene or a recessive gene. In teaching of genetics, the introduction of most recent research advancements of cloning of Mendel's genes to the students and the interpretation of the Mendel's laws in molecular level will help students promote their learning interests in genetics and help students grasp the whole content from classical genetics to molecular genetics and the developmental direction of this subject.

[Effect of three-stage sequential method on interleukin-5 mRNA expression in the lung tissue of asthmatic model rat treated with steroid].

OBJECTIVE: To observe the effect of three-stage sequential method (TSSM) on interleukin-5 (IL-5) mRNA expression in the lung tissue of asthmatic rat model treated with steroid. METHODS: SD rats were randomly divided into 8 groups, the normal control group (GA), the model group (GB), the model with steroid intervention group (GC) and the 5 treated groups (GD - GH). Excepting those in the GA, all rats were established into the asthma model and rats in GC-GH were intervened by dexamethasone, with the dosage reduced by 0.1 mg/kg per week starting from the 3rd week and withdrawn completely till the 7th week. At the same time, rats in GD - GH were treated with TSSM, and the 1st, 2nd and 3rd recipe of TSSM, as well as pulmicort respules (as positive control) respectively. IL-5 mRNA expression in the lung tissue of rats was detected at different time points by in situ hybridization. RESULTS: Comparisons of GD with other groups in IL-5 mRNA expression showed: it was remarkably lowered than that in GB and GC at all time points (P < 0.01); compared to GH, the difference was insignificant at the end of the 2nd week, but significant at the end of the 7th and 9th week (P < 0.01); as for the difference between GD with GE, GF and GG, it showed very significant difference (P < 0.01) at all the time points besides that at the end of the 2nd week, it showed insignificance to GE (P > 0.05) and significance to GF (P < 0.05). The dynamic changes of IL-5 mRNA expression in GD during the steroid withdrawal period showed the lowering was more significantly at the end of the 7th and 9th week than that at the end of the 2nd week (P < 0.05, P < 0.01), but its levels were equal at the former two time points; its lowest level appeared at the end of the 9th week, which approaching the level in GA (P > 0.05). CONCLUSION: Three-stage sequential method could remarkably inhibit IL-5 mRNA expression in the lung tissue of asthmatic rats undergoing steroid treatment.

Development of a wide population of chromosome single-segment substitution lines in the genetic background of an elite cultivar of rice (Oryza sativa L.).

Naturally occurring allelic variations underlying complex traits are useful resources for the functional analysis of plant genes. To facilitate the genetic analysis of complex traits and the use of marker-assisted breeding in rice, we developed a wide population consisting of 217 chromosome single-segment substitution lines (SSSLs) using Oryza sativa L. 'Hua-Jing-Xian74' (HJX74), an elite Indica cultivar, as recipient, and 6 other accessions, including 2 Indica and 4 Japonica, as donors. Each SSSL contains a single substituted chromosome segment derived from 1 of the 6 donors in the genetic background of HJX74. The total size of the substituted segments in the SSSL population was 4695.0 cM, which was 3.1 times that of rice genome. To evaluate the potential application of these SSSLs for quantitative trait loci detection, phenotypic variations of the quantitative traits of days to heading and grain length in the population consisting of 210 SSSLs were observed under natural environmental conditions. The results demonstrated that there was a wide range of phenotypic variation in the traits in the SSSL population. These genetic materials will be powerful tools to dissect complex traits into a set of monogenic loci and to assign phenotypic values to different alleles at the locus of interest.

[Developing single segment substitution lines (SSSLs) in rice (Oryza sativa L.) using advanced backcrosses and MAS].

A novel population consisted of 86 single segment substitution lines (SSSLs) were developed from advanced backcrosses between the recipient, Huajingxian 74 and six donors by microsatellite marker-assisted selection (MAS). Fifty-two SSSLs were selected in BC3F2, and 34 others were selected in BC3F3. Every SSSL contains a single chromosome segment introgressed from one donor on the genetic background of Huajingxian 74. The substituted segments in SSSLs were distributed on 12 rice chromosomes. The estimated length of the substituted segments in SSSLs ranged from 1.5 cM to 56.3 cM with an average of 23.0 cM. Total of the substituted segments covered 57.1% of the rice genome.