Magnitude of hybrid vigor retained in double haploid lines of some heterotic rice hybrids

Sixty one double haploid (DH) lines were evaluated for yield components and yield and compared with the three corresponding hybrids from which they were derived through anther culture. Analysis of a 6×6 diallel experiment led to the selection of these hybrids based on their high heterosis and revealed the nature of gene action of the characters under evaluation. The DH lines along with the hybrids and parents were planted following a simple lattice design with two replications. The results show that in DH lines the values of the characters expressing predominantly additive genetic effects could reach the heterotic level of the hybrids. For characters including yield showing predominantly dominance effects, values in the DH lines were significantly lower than those of the corresponding hybrids. The promising DH lines, however, possess a higher yield potential than the better parents.     

Association of Polymorphisms and Haplotypes in the Insulin-Like Growth Factor 1 Receptor (IGF1R) Gene with the Risk of Breast Cancer in Korean Women

The insulin-like growth factor (IGF) signaling pathway plays an important role in cancer biology. The IGF 1 receptor (IGF1R) overexpression has been associated with a number of hematological neoplasias and solid tumors including breast cancer. However, molecular mechanism involving IGF1R in carcinogenic developments is clearly not known. We investigated the genetic variations across the IGF1R polymorphism and the risk of breast cancer risk in Korean women. A total of 1418 individuals comprising 1026 breast cancer cases and 392 age-matched controls of Korean were included for the analysis. Genomic DNA was extracted from whole blood and single nucleotide polymorphisms (SNPs) were analyzed on the GoldenGate Assay system by Illumina’s Custom Genetic Analysis service. SNPs were selected for linkage disequilibrium (LD) analysis by Haploview. We genotyped total 51 SNPs in the IGF1R gene and examined for association with breast cancer. All the SNPs investigated were in Hardy-Weinberg equilibrium. These SNPs tested were significantly associated with breast cancer risk, after correction for multiple comparisons by adjusting for age at diagnosis, BMI, age at menarche, and age at first parturition. Among 51 IGF1R SNPs, five intron located SNPs (rs8032477, rs7175052, rs12439557, rs11635251 and rs12916884) with homozygous genotype (variant genotype) were associated with decreased risk of breast cancer. Fisher’s combined p-value for the five SNPs was 0.00032. Three intron located SNPs with heterozygous genotypes also had decreased risk of breast cancer. Seven of the 51 IGF1R SNPs were in LD and in one haplotype block, and were likely to be associated with breast cancer risk. Overall, this case-control study demonstrates statistically significant associations between breast cancer risk and polymorphisms in IGF1R gene.     

Metformin alleviates hepatosteatosis by restoring SIRT1-mediated autophagy induction via an AMP-activated protein kinase-independent pathway

Metformin activates both PRKA and SIRT1. Furthermore, autophagy is induced by either the PRKA-MTOR-ULK1 or SIRT1-FOXO signaling pathways. We aimed to elucidate the mechanism by which metformin alleviates hepatosteatosis by examining the molecular interplay between SIRT1, PRKA, and autophagy. ob/ob mice were divided into 3 groups: one with ad libitum feeding of a standard chow diet, one with 300 mg/kg intraperitoneal metformin injections, and one with 3 g/d caloric restriction (CR) for a period of 4 wk. Primary hepatocytes or HepG2 cells were treated with oleic acid (OA) plus high glucose in the absence or presence of metformin. Both CR and metformin significantly improved body weight and glucose homeostasis, along with hepatic steatosis, in ob/ob mice. Furthermore, CR and metformin both upregulated SIRT1 expression and also stimulated autophagy induction and flux in vivo. Metformin also prevented OA with high glucose-induced suppression of both SIRT1 expression and SIRT1-dependent activation of autophagy machinery, thereby alleviating intracellular lipid accumulation in vitro. Interestingly, metformin treatment upregulated SIRT1 expression and activated PRKA even after siRNA-mediated knockdown of PRKAA1/2 and SIRT1, respectively. Taken together, these results suggest that metformin alleviates hepatic steatosis through PRKA-independent, SIRT1-mediated effects on the autophagy machinery.     

Effective suppression of HIV-1 by artificial bispecific miRNA targeting conserved sequences with tolerance for wobble base-pairing

The high genetic diversity and mutability of HIV pose a major problem for RNAi-mediated antiviral therapy. Simultaneous targeting of multiple highly conserved viral sequences has been suggested for durable cross-clade inhibition. Here we validate the approach of co-targeting two conserved sequences in the Tat and Vif genes. When coexpressed as artificial microRNA from a PolII driven miR-155-based vector, the sequences together mediated effective and sustained inhibition of HIV replication without virus breakout. To understand the nature of this efficient control, we analyzed genome sequences of 625 HIV-1 isolates in the Los Alamos Sequence database. Interestingly most natural variants were capable of wobble binding with the Tat/Vif siRNAs. Efficient silencing of reporter luciferase constructs bearing these variants residues verified that the Tat/Vif sequences together tolerated wobble binding and mediated functional RNAi. We propose the rationale of targeting highly conserved HIV sequences where wobble substitutions permit functional RNAi for global HIV repression.     

Integrin beta1-mediated matrix assembly and signaling are critical for the normal development and function of the kidney glomerulus

The human kidneys filter 180 l of blood every day via about 2.5 million glomeruli. The three layers of the glomerular filtration apparatus consist of fenestrated endothelium, specialized extracellular matrix known as the glomerular basement membrane (GBM) and the podocyte foot processes with their modified adherens junctions known as the slit diaphragm (SD). In this study we explored the contribution of podocyte β1 integrin signaling for normal glomerular function. Mice with podocyte specific deletion of integrin β1 (podocin-Cre β1-fl/fl mice) are born normal but cannot complete postnatal renal development. They exhibit detectable proteinuria on day 1 and die within a week. The kidneys of podocin-Cre β1-fl/fl mice exhibit normal glomerular endothelium but show severe GBM defects with multilaminations and splitting including podocyte foot process effacement. The integrin linked kinase (ILK) is a downstream mediator of integrin β1 activity in epithelial cells. To further explore whether integrin β1-mediated signaling facilitates proper glomerular filtration, we generated mice deficient of ILK in the podocytes (podocin-Cre ILK-fl/fl mice). These mice develop normally but exhibit postnatal proteinuria at birth and die within 15 weeks of age due to renal failure. Collectively, our studies demonstrate that podocyte β1 integrin and ILK signaling is critical for postnatal development and function of the glomerular filtration apparatus.     

Glycated albumin induces superoxide generation in mesangial cells.

BACKGROUND/AIMS: Reactive oxygen species are involved in the pathogenesis of diabetic nephropathy. Amadori-modified glycated albumin modulates signaling pathways in mesangial cells that contribute to the development of diabetic nephropathy. However, the effects of glycated albumin on mesangial cell superoxide (O2-) production are unknown. Thus, we examined whether glycated albumin induces mesangial cell O2- generation and whether increased O2- production elicits cell growth. METHODS: Quiescent human mesangial cells (HMC) were exposed to bovine serum albumin (BSA) or glycated BSA (Gly-BSA) with or without diphenylene iodonium (DPI) or apocynin, inhibitors of NAD(P)H oxidase, GF109203X (GFX), a protein kinase C (PKC) inhibitor. RESULTS: Gly-BSA increased PKC activity, particularly PKC-alpha and -alpha1, within 15 min of incubation with HMC, which decreased to the control value at 2 h. Gly-BSA incubated with HMC increased O2- production by 2 times vis-á-vis BSA-treated cells. The Gly-BSA-induced increased O2- generation was suppressed by DPI or GFX. Gly-BSA significantly increased mesangial [3H]-leucine incorporation, whereas these processes were abrogated by DPI, apocynin or GFX. CONCLUSIONS: Gly-BSA induces PKC/NAD(P)H oxidase-dependent O2- production in HMC, which in turn results in cell hypertrophy. Thus, O2- induced by glycated albumin might cause mesangial cell alterations in diabetes participating in the pathophysiology of diabetic nephropathy.     

Biochemical characterization and sequence analysis of a xylanase produced by an exo-symbiotic bacterium of <Emphasis Type="Italic">Gryllotalpa orientalis</Emphasis>, <Emphasis Type="Italic">Cellulosimicrobium</Emphasis> sp. HY-12

An exo-symbiotic bacterium capable of hydrolyzing xylan was isolated from the gut of the mole cricket, Gryllotalpa orientalis, and identified as Cellulosimicrobium sp. HY-12. The xylanase (XylA _CspHY-12) of this organism bound tightly to both DEAE and mono Q resins, and its molecular mass (M _r) was about 39.0 kDa. The highest xylanase activity was observed at pH 6.0 and 60°C. The enzyme was greatly suppressed by Ca²⁺, Cu²⁺, Co²⁺, and Fe²⁺ ions but not by Mg²⁺ and Mn²⁺. Although XylA _CspHY-12 was capable of hydrolyzing various types of xylosic compounds, it could not decompose carboxymethyl cellulose or xylobiose. The xylA _CspHY-12 gene consisted of an 1,188 bp open reading frame that encoded a polypeptide of 395 amino acids with a deduced molecular mass of 42,925 Da. The domain structure of XylA _CspHY-12 was most similar to those of the glycoside hydrolase (GH) family 10 endoxylanases. However its sequence identity with any of the enzymes in this family was below 52%. The results of this study suggest that the XylA _CspHY-12 is a new cellulase-free endo-β-1,4-xylanase with some properties that are distinct from those of GH family 10.