[Identification and analysis of a novel microsatellite marker flanking porcine myostatin gene (MSTN)].

In animal breeding, microsatellite marker plays an important role in constructing genetic maps, QTL mapping and function analysis of structural genes. Myostatin, also known as GDF8, is a negative regulator of skeletal muscle mass and, in swine, it is evidenced to be related to birth weight and average daily gain from 60 kg to 100 kg of body weight. In present study, by subcloning and sequencing,we identified a novel microsatellite marker which is useful for fine QTL mapping for meat traits. A BAC clone containing porcine MSTN was extracted and digested with EcoR I to recover the fragment of > 4 kb for subcloning in pGEM-3zf (+). Sequencing and alignment results showed that this subcloned fragment was not from porcine MSTN, but included a tandem repeat of (TG) 13, which is a novel microsatellite marker (GenBank accession number: AF454400) flanking MSTN. To exclude its vector origin we designed specific primers flanking this marker and successfully amplified this fragment from porcine genome. Through a pedigree analysis of a double-muscled Yorshire strain, we found that it is inherited in a co-dominant manner. We also checked the gene frequencies of this locus in 381 unrelated individuals of 7 pig breeds, namely Laiwu,Landrace, Yorkshire,Duroc, Peterian, Min and Erhualian. Only two alleles were detected, the repeating number of which are 13 (allele A) and 19 (allele B) respectively, which indicated that it is a low poly morphic microsatellite marker. In addition, the frequencies of the two alleles are different between the two types of pig breeds, while allele A is dominant in Chinese local breeds, allele B is dominant in imported breeds. Alignment with AY208121 indicate that this locus is located 42 kb downstream of porcine MSTN. We speculate that this microsatellite DNA is an important marker both in fine QTL mapping for meat traits and in the expression study of porcine MSTN.

Residential radon and lung cancer risk in a high-exposure area of Gansu Province, China.

In the general population, evaluation of lung cancer risk from radon in houses is hampered by low levels of exposure and by dosimetric uncertainties due to residential mobility. To address these limitations, the authors conducted a case-control study in a predominantly rural area of China with low mobility and high radon levels. Included were all lung cancer cases diagnosed between January 1994 and April 1998, aged 30-75 years, and residing in two prefectures. Randomly selected, population-based controls were matched on age, sex, and prefecture. Radon detectors were placed in all houses occupied for 2 or more years during the 5-30 years prior to enrollment. Measurements covered 77% of the possible exposure time. Mean radon concentrations were 230.4 Bq/m(3) for cases (n = 768) and 222.2 Bq/m(3) for controls (n = 1,659). Lung cancer risk increased with increasing radon level (p < 0.001). When a linear model was used, the excess odds ratios at 100 Bq/m(3) were 0.19 (95% confidence interval: 0.05, 0.47) for all subjects and 0.31 (95% confidence interval: 0.10, 0.81) for subjects for whom coverage of the exposure interval was 100%. Adjusting for exposure uncertainties increased estimates by 50%. Results support increased lung cancer risks with indoor radon exposures that may equal or exceed extrapolations based on miner data.

Cooking oil fumes and risk of lung cancer in women in rural Gansu, China.

Cooking oil fumes have been suggested to increase the risk of lung cancer in Chinese women by exposing them to mutagenic substances. We investigated the association between lung cancer and locally made rapeseed and linseed oils in a population-based case-control study in Gansu Province, China. Two hundred and thirty-three incident, female lung cancer cases diagnosed from 1994-98 were identified. A control group of 459 women was selected from census lists and were frequency matched on age and prefecture. Interviewers obtained information on cooking practices and cooking oil use. The odds ratio (OR) for lung cancer associated with ever-use of rapeseed oil, alone or in combination with linseed oil, was 1.67 (95% CI 1.0-2.5), compared to use of linseed oil alone. ORs for stir-frying with either linseed or rapeseed oil 15-29, 30 and > or =31 times per month were 1.96,1.73, and 2.24, respectively (trend, P=0.03), relative to a lower frequency of stir-frying. Lung cancer risks also increased with total number of years cooking (trend, P<0.09). Women exposed to cooking fumes from rapeseed oil appeared to be at increased risk of lung cancer, and there was some evidence that fumes from linseed oil may have also contributed to the risk.