Exogenous spermidine alleviates fruit granulation in a <Emphasis Type="Italic">Citrus</Emphasis> cultivar (<Emphasis Type="Italic">Huangguogan</Emphasis>) through the antioxidant pathway

The role of exogenous spermidine (Spd) in alleviating fruit granulation in the grafted seedlings of a Citrus cultivar (Huangguogan) was investigated. Granulation resulted in increased electrical conductivity, cell membrane permeability, and total pectin, soluble pectin, cellulose, and lignin contents. However, it decreased the activities of superoxide dismutase, peroxidase, and catalase, as well as the (Spd + Spm):Put ratio. The application of exogenous Spd onto Huangguogan seedlings significantly increased proline and ascorbate contents, but decreased the H₂O₂ and O ₂ ^?· levels, which suggested that exogenous Spd provided some protection from oxidative damage. In addition, exogenous Spd decreased cell membrane permeability and MDA content, and increased the (Spd + Spm):Put ratio. The activities of antioxidant enzymes, such as catalase, peroxidase, and superoxide dismutase, were increased in Spd-treated seedlings affected by fruit granulation, resulting in a decrease in oxidative stress levels. The protective effects of Spd were reflected by a decrease in superoxide levels through osmoregulation, increased proline and ascorbate contents, and increased antioxidant activities. Our observations reveal the importance of exogenous Spd in alleviating citrus fruit granulation.     

云南普通马矮型马蛋白多态性及其品种分化关系

本文运用蛋白电泳技术对来自云南省文山州马关县和麻栗坡县的２１匹普通马和１４匹矮型马进行了分析。共分析遗传座位４４个,其中有１０个座位检测到多态性。根据分子钟假说和相应的公式,推算两者的分歧时间约为１８．５万年。     

Microscopical observations on four marine Dysteria species (Ciliophora, Cyrtophorida)

Four interesting strains of marine ciliates belonging to the genus Dysteria, collected from the coastal area of Qingdao, China, were investigated using living observations and silver impregnation methods. New data are supplied in redefinitions of three poorly known species, all of which had two contractile vacuoles. D. crassipes Claparède and Lachmann, 1859 has a rectangular body about 65 x 35 microm in vivo, with a podite subcaudal on the ventral side and a dorsal spine on some specimens; it has four right kineties, the rightmost two of which extend dorso-apically; both plates of examined specimens had a covering of ectosymbiotic bacteria. D. semilunaris (Gourret and Roeser, 1886) Kahl, 1931 has an oval body about 30 x 16 microm in vivo, with a caudal podite and a groove on the left plate; it also has four right kineties, the rightmost two of which extend dorso-apically. D. pectinata (Nowlin, 1913) Kahl, 1931 also has an oval body and caudal podite, but is larger at about 85 x 40 microm in vivo; it has seven right kineties, the rightmost two of which extend dorso-apically and the leftmost one is short and posterior. The fourth strain was D. brasiliensis Faria et al., 1922, which was found to vary in both shape and the presence or absence of a dorsal spine, it also hosts numerous rod-shaped ectosymbiotic bacteria on both plates of the cell. Based on information available, a key to the marine species that have been investigated by silver impregnation is updated.     

Mutations in the regulatory domain of phenylalanine hydroxylase and response to tetrahydrobiopterin

Tetrahydrobiopterin (BH4) is a co-factor that enhances the activity of other enzymes, and this co-factor level is found to be affected in phenylketonuria (PKU), an amino acid metabolism disorder. The present study was aimed at understanding the effect of BH4 on mutations in the regulatory domain of phenylalanine hydroxylase (PAH). Among 14 patients, 5 patients were classical PKU, 3 were atypical PKU, and 6 were mild PKU. All of these patients had at least one mutation in the regulatory domain. Patients were given 10 mg/kg BH4, and the response of blood phenylalanine (Phe) levels was monitored following treatment. The level of blood Phe decreased after BH4 treatment in all of the patients. These studies suggest that mutations in the regulatory domain also responded to BH4 even if the patient had classical PKU.     

Different probiotic properties for Lactobacillus fermentum strains isolated from swine and poultry

Systematic procedures were used to evaluate the probiotic properties of Lactobacillus fermentum (L. fermentum) strains isolated from swine and poultry. The major properties included their capabilities to adhere to the intestinal epithelium of swine and poultry, the inhibition on pathogenic bacteria, and their tolerance to the gastric juice and bile salts. Results showed that L. fermentum strains from poultry digestive tract showed better adherence to the swine intestine and chicken crop epithelial cells as compared to those strains from the swine origin. In addition, six strains from poultry and one strain from swine showed adhesion specificity to their own intestinal epithelium. Four poultry isolates and one swine isolate were able to adhere to the epithelial cells from both swine and chicken. For gastric juice and bile tolerance, most of the strains isolated from swine or poultry were acid tolerant but less strains were bile intolerant. The spent culture supernatant (SCS) of these L. fermentum strains showed antagonistic effect against the indicator bacteria, such as Escherichia coli, Salmonella spp., Shigella sonnei and some enterotoxigenic Staphylococcus aureus. From the above studies, some L. fermentum strains isolated from poultry were found to have the probiotic properties required for use in animal feed supplement. This study suggested that poultry digestive tract may serve as potential source for the isolation of probiotic lactic acid bacteria.     

Linker molecules between laminins and dystroglycan ameliorate laminin-alpha2-deficient muscular dystrophy at all disease stages

Mutations in laminin-alpha2 cause a severe congenital muscular dystrophy, called MDC1A. The two main receptors that interact with laminin-alpha2 are dystroglycan and alpha7beta1 integrin. We have previously shown in mouse models for MDC1A that muscle-specific overexpression of a miniaturized form of agrin (mini-agrin), which binds to dystroglycan but not to alpha7beta1 integrin, substantially ameliorates the disease (Moll, J., P. Barzaghi, S. Lin, G. Bezakova, H. Lochmuller, E. Engvall, U. Muller, and M.A. Ruegg. 2001. Nature. 413:302-307; Bentzinger, C.F., P. Barzaghi, S. Lin, and M.A. Ruegg. 2005. Matrix Biol. 24:326-332.). Now we show that late-onset expression of mini-agrin still prolongs life span and improves overall health, although not to the same extent as early expression. Furthermore, a chimeric protein containing the dystroglycan-binding domain of perlecan has the same activities as mini-agrin in ameliorating the disease. Finally, expression of full-length agrin also slows down the disease. These experiments are conceptual proof that linking the basement membrane to dystroglycan by specifically designed molecules or by endogenous ligands, could be a means to counteract MDC1A at a progressed stage of the disease, and thus opens new possibilities for the development of treatment options for this muscular dystrophy.     

Adipocyte differentiation induced using nonspecific siRNA controls in cultured human mesenchymal stem cells

RNA interference (RNAi) is gene silencing induced by double-stranded RNA of 21-23 nucleotides in length, termed small interfering RNA, or siRNA. RNAi-based techniques have been widely applied to elucidate gene function, identify drug targets, and used in trials as a promising adjunct to silence disease-causing genes. However, emerging evidence suggests unexpected changes in expression of untargeted genes as a consequence of an off-target effect by RNAi in mammalian cells. To date, our understanding of such effects on stem cells is limited. We transfected human fetal femur-derived mesenchymal stem cells using commercially available nonspecific siRNA controls and examined adipocyte differentiation in the cells using morphology, histochemistry, and quantitative real-time PCR to examine the expression of key genes for adipogenic or osteogenic differentiation. We report here the induction of adipocyte differentiation in human mesenchymal stem cells using nonspecific siRNAs raising concerns as to the specificity of RNAi in stem cells and, critically, a need to understand and delineate the rules governing the specificity of RNAi.