Genetic mapping of a gene causing hypertension in the stroke-prone spontaneously hypertensive rat.

The stroke-prone spontaneously hypertensive rat (SHRSP) is a well-characterized model for primary hypertension in humans. High blood pressure in SHRSP shows polygenic inheritance, but none of the loci responsible have previously been identified. To locate genes controlling this quantitative trait, we mapped a large collection of DNA polymorphisms in a cross between SHRSP and the normotensive WKY strain. Here we report strong genetic evidence that a gene, Bp1, having a major effect on blood pressure maps to rat chromosome 10 with a LOD score of 5.10 and is closely linked to the rat gene encoding angiotensin-converting enzyme (ACE), an enzyme that plays a major role in blood pressure homeostasis and is an important target of anti-hypertensive drugs. We also find significant, albeit weaker, linkage to a locus, Bp2, on chromosome 18. We discuss the implications of genetic dissection of quantitative disease-related phenotypes in mammals.     

The Combination of SMAD4 Expression and Histological Grade of Dysplasia Is a Better Predictor for the Malignant Transformation of Oral Leukoplakia

Oral leukoplakia (OL) is the most common premalignancy in the oral cavity and can progress to oral squamous cell carcinoma (OSCC). SMAD4 is a tumor suppressor implicated in multiple cancer types including OSCC. To assess the role of SMAD4 in oral leukoplakia malignant transformation, the authors investigated SMAD4 expression patterns in OL and OSCC using a highly specific antibody and correlated the patterns with the risk of malignant transformation oral leukoplakia. Immunohistochemistry and a quantitative imaging system were used to measure SMAD4 expression in OL from 88 OL patients, including 22 who later went through malignant transformation, and their OSCC counterpart. Forty-three (48.9%) of the 88 OL patients had strong SMAD4 expression. SMAD4 expression had no significant correlation with patients'' clinicopathological parameters. Interestingly, 17 (39.5%) of the 43 OL lesions with strong SMAD4 expression went through malignant transformation whereas only 5 (11.1%) of the 45 OL lesions with weak SMAD4 expression did so (p = 0.002). The SMAD4 expression in OL was much higher than that in their OSCC counterpart. Kaplan-Meier analysis revealed that the combination of SMAD4 expression and histological grade of dysplasia (p = 0.007) is a better predictor for the malignant transformation of oral leukoplakia. In the multivariate analysis, both SMAD4 expression and grade of dysplasia were identified as independent factors for OL malignant transformation risk (p = 0.013 and 0.021, respectively). It was concluded that high SMAD4 expression may be indicative of an early carcinogenic process in OL and serve as an independent biomarker in assessing malignant transformation risk in patients with OL, and the combination of SMAD4 expression and histological grade of dysplasia is a better predictor for the malignant transformation of oral leukoplakia.     

Instrumented Indentation Investigation on the Viscoelastic Properties of Porcine Cartilage

Articular cartilage lubricates the contact surfaces in human joints and provides a shock-absorbing effect which protects the joint under dynamic loading. However, this shock-absorbing effect is gradually reduced as the result of normal wear, tear and aging-related cartilage loss. Thus, with the increasing average human life expectancy, the issue of joint health has attracted significant interest in recent decades. In developing new materials for the repair or regeneration of damaged articular cartilage, it is essential that the difference in the mechanical properties of healthy and damaged cartilages is well-understood. In the present study, the hardness and Young＇s modulus of damaged and healthy porcine articular cartilage samples are evaluated via a quasi-static nanoindentation technique. A dynamic mechanical analysis method is then applied to determine the viscoelastic properties of the two samples. The results presented in this study provide a useful insight into the mechanical properties of articular cartilage at the mesoscale, and therefore fill an important gap in the literature.     

Molecular cloning and characterization of AAAS-V2, a novel splice variant of human AAAS

Triple-A syndrome (MIM 231550; also known as Allgrove syndrome) is an autosomal recessive disorder characterized by adrenocorticotropin hormone (ACTH)-resistant adrenal insufficiency, achalasia of the oesophageal cardia and alacrima. Much initial molecular analysis supported that Triple-A syndrome was caused by mutations in AAAS, a WD-repeat protein gene. Here we report cloning and characterization of a novel splice variant of human AAAS, which we named AAAS-v2, which is located on the human chromosome 12p13. The cDNA is 1703bp, encoding a 513-amino acid polypeptide, which contains three WD40 domains, one less than the original which we called AAAS-v1 (Gen Bank: NM_015665.3). RT-PCR analysis in our work revealed that AAAS-v2 and AAAS-v1 were ubiquitously detected in human multiple tissue cDNA (MTC) panels (CLONTECH).The nucleotide sequence reported in this paper has been submitted to GenBank under accession number AY237818.Xin Li: These two authors contributed equally to this paper.Chaoneng Ji: These two authors contributed equally to this paper.     

Genetic diversity and population structure assessment of Chinese <Emphasis Type="Italic">Senna obtusifolia</Emphasis> L. by molecular markers and morphological traits of seed

Senna obtusifolia L. is an important medicinal plant in Asia. This study was the first report on the genetic diversity and population structure of S. obtusifolia which were collected from 47 geographic populations widespread in China. Inter-Simple Sequence Repeat (ISSR) and Start Codon Target Polymorphism (SCoT) combined with seeds morphological traits were used to investigate the relationship of 47 populations. 11 ISSR primers yielded 98 polymorphic bands with 81.67% polymorphism. 24 SCoT primers yielded 267 polymorphic bands with 89.59% polymorphism. The number of allele (Na), the number of effective allele (Ne), Nei’s diversity index (H), and Shannon’s information index (I) reflected a high level of genetic diversity of S. obtusifolia species. The greatest genetic distance (G _D) existed between Southwest and Northwest (0.4022_ISSR/0.5019_SCoT), while the Eastern and Northern showed the least genetic distance (0.1751_ISSR/0.2186_SCoT). The genetic differentiation (Gst) was 0.4875_ISSR/0.4434_SCoT, and the gene flow (Nm) was 0.5256_ISSR/0.6275_SCoT, which indicated that gene exchange among four regions was limited. 47 samples were divided into four clusters mainly according to their geographic distribution through clustering and structure analysis. The analysis on the combined data of ISSR and SCoT showed more reliable and superior results than single analysis of ISSR and SCoT. This study explored the effectiveness of ISSR and SCoT markers to evaluate the genetic diversity and population structure of S. obtusifolia and provided useful information for S. obtusifolia germplasm research and breeding program.