以梅山猪和长白猪的背最长肌为材料，利用抑制性消减杂交技术，成功构建了梅山猪与长白猪肌肉组织间正反向消减cDNA文库。以管家基因G3PDH作为消减指标，检测梅山猪和长白猪两个消减文库的消减效率分别高达210和25倍，表明某些特异于两种肌肉组织的差异表达基因的富集效率也分别接近210和25倍。从两个消减文库中分别筛选到了709和673个有效阳性克隆，PCR鉴定插入片段长度主要分布于150～750 bp之间。不同猪种肌肉组织间消减cDNA文库的构建为进一步分离和鉴定影响肌肉生长和肉质的基因奠定了基础，对探讨肌肉生长机理和肉质决定因素，以及应用于分子育种具有重要意义。

Human leptin expressed by E. coli had been used to treat human obesity in American and scientists had achieved good effects, the researchers here wanted to know whether human leptin can be expressed in the mammary glands of transgenic animas. In this study, human leptin gene about 1.0kb, the terminator of rabbit whey acid protein gene (rWAP) about 0.2kb and the promoter including the distal upstream region and part of the first exon of rWAP gene about 6.3kb were used to construct a expression vector. Before we did the subclonings, the sequences of the human leptin gene were sequenced by ABI377 DNA Sequencer, the results showed that the fragment of human leptin gene included the last nine base pairs of the first exon, the complete sequences of the second exon (172bp) and parts of the third exon (including part of the encoding sequences and part of the 3' untranslated region). The final expression vector was digested with NotI and a fragment of 7.5kb was collected and dissolved in TE (10mmol/L Tris? C1, pH7.4; 0.1mmol/L EDTA) for later microinjection. The concentration of DNA was about 2¦Ìg/mL, the copy number in lmL was about 2.4×l011, every 1 to 2pL of the prepared DNA solution was microinjected into the mouse embryos at pronucleus stage. After standard microinjection procedures, 48 live mice were obtained. The tails of the mice were cut (about 0.lg) at four weeks of age, genomic DNA was extracted and digested completely with EcoRI, two were confirmed to be transgenic mice (both were female) by Southern hybridization using DIG labeled human leptin gene as probe, transgenic rat among the mice born was about 4% (2/48). The two female transgenic mice (2# and C3) were mated with nontransgenic male mice. The two founder transgenic mice were segregated with their baby mice for at least three hours at the fifth day after parturition and were milked by intraperitoneal injection of 0.3 IU of oxytocin and udder massage. SDS-PAGE was used to analyze whether there were expression of human leptin in the milk of the two founder transgenic mice with the milk of non-transgenic mouse at fifth day after parturition as control. SDS-PAGE results showed that compared with the control there was a new band in both of the founder transgenic mice milk, and its molecular weight was about 16kD, which was quite similar with that of the human leptin. The researchers estimated that the expression level of this protein in the milk of the transgenic mice was about 1～2mg/mL.

激素敏感脂肪酶（HSL）是动物体脂肪分解的关键酶。采用PCR-SSCP法研究猪HSL基因的启动于区。部分5'-端转录非翻译区、第7外显于区、第8外显子区和3'-端部分转录非翻译区域DNA多态性。结果在对应于HSL基因第8外显子区域发现1 DNA片段的SSCP，表现出3种基因型MM、MN和NN,脂肪型猪种梅山猪和通城猪含有更多的等位基因M（频率分别为0.690和0.740），而瘦肉型猪种大白猪和长白猪则含有更多的等位基因N（频率分别为0.847和0.845）；该DNA片段经测序分析，发现位于基因cDNA第2249和2280处发生碱基序列的改变（均为A→G），使天冬酰胺变为天冬氨酸（Asa→Asp）和谷氨酸变为甘氨酸（Glu→Gly）。

The fragment in intron Ⅰ of FSH-βgene was amplified by PCR. According to the polymorphism, we analyzed the distribution of FSH-βretroposon in different pig breeds, its inheritance pattern in Large White×Meishan reference family, and the association of FSH-βretroposon with litter size, female reproductive organs measurement, ultrasonic backfat and other traits. The results showed that almost each Chinese indigenous pig had retroposon, while foreign pig breeds rarely had; the frequencies of porcine FSH-βretroposon were strongly associated with breeds (p<0.01); the pattern of inheritance is consistent with Mendelian fashion. Total number born (TNB) and number born alive (NBA) were increased per FSH-β retroposon (p<0.01) with additive effects of 1.2-1.8 and 1.4-1.8 pigs/litter, respectively; between the FSH-βretroposon carriers and non-carries, there was an insignificant difference in the measurement of female reproductive organs, body weight at birth, backfat thickness, loin meat height, lean meat percentage, teat number, days to 100kg, and average daily gain.

In aiming to identify the genes or genetic regions responsible for quantitative traits, a swine reference population had been constructed using three Large White boars and seven Meishan dams as parents. Five F1 males and 23 F1 females were intercrossed to generate 147 F2 offspring. Thirty-one microsatellite markers covering Sus scrofa our chromosomes (SSC) 2, 4, 6 and 7 were genotyped for all members. Construction of genetic microsatellite maps was performed using the CRIMAP software package. The lengths of these chromosomes were longer than MARC maps. They were 158.6cM, 180.3cM, 197.3cM and 171.4cM, respectively. A two modified orders of markers were observed for SSC6 and SSC7. The female map on SSC6 was shorter than male map, and the contrary was on SSC 2, 4 and 7.