Isolation and characterization of cDNAs encoding mitochondrial phosphate transporters in soybean,maize, rice,and Arabidopsis

cDNA clones encoding mitochondrial phosphate transporters were isolated from four herbaceous plants. The cDNAs for the soybean, maize and rice transporters contained entire coding regions, whereas the Arabidopsis cDNA lacked the 5 portion. The hydropathy profiles of the deduced amino acid sequences predicted the existence of six membrane-spanning domains which are highly conserved in the mitochondrial transporter family. In soybeans, the mRNA level for the transporter was high in tissues containing dividing cells. It was suggested that there are multiple copies of transporter genes in both dicots and monocots. The soybean transporter was expressed as inclusion bodies in Escherichia coli, solubilized with detergents, and then reconstituted into liposomes. The resulting proteoliposomes exhibited high phosphate transport activity. The activity was inhibited by N-ethylmaleimide, like those of mammalian phosphate transporters.     

Urinary Neutrophil Gelatinase-Associated Lipocalin: A Useful Biomarker for Tacrolimus-Induced Acute Kidney Injury in Liver Transplant Patients

Tacrolimus is widely used as an immunosuppressant in liver transplantation, and tacrolimus-induced acute kidney injury (AKI) is a serious complication of liver transplantation. For early detection of AKI, various urinary biomarkers such as monocyte chemotactic protein-1, liver-type fatty acid-binding protein, interleukin-18, osteopontin, cystatin C, clusterin and neutrophil gelatinase-associated lipocalin (NGAL) have been identified. Here, we attempt to identify urinary biomarkers for the early detection of tacrolimus-induced AKI in liver transplant patients. Urine samples were collected from 31 patients after living-donor liver transplantation (LDLT). Twenty recipients developed tacrolimus-induced AKI. After the initiation of tacrolimus therapy, urine samples were collected on postoperative days 7, 14, and 21. In patients who experienced AKI during postoperative day 21, additional spot urine samples were collected on postoperative days 28, 35, 42, 49, and 58. The 8 healthy volunteers, whose renal and liver functions were normal, were asked to collect their blood and spot urine samples. The urinary levels of NGAL, monocyte chemotactic protein-1 and liver-type fatty acid-binding protein were significantly higher in patients with AKI than in those without, while those of interleukin-18, osteopontin, cystatin C and clusterin did not differ between the 2 groups. The area under the receiver operating characteristics curve of urinary NGAL was 0.876 (95% confidence interval, 0.800–0.951; P<0.0001), which was better than those of the other six urinary biomarkers. In addition, the urinary levels of NGAL at postoperative day 1 (p = 0.0446) and day 7 (p = 0.0006) can be a good predictive marker for tacrolimus-induced AKI within next 6 days, respectively. In conclusion, urinary NGAL is a sensitive biomarker for tacrolimus-induced AKI, and may help predict renal event caused by tacrolimus therapy in liver transplant patients.     

Comparison of vildagliptin twice daily vs. sitagliptin once daily using continuous glucose monitoring (CGM): Crossover pilot study (J-VICTORIA study)

Background

The role of Lipoprotein (a) cholesterol {Lp(a)-C}as an additional and/or independent risk factor for cardiovascular disease (CVD) is not clear. We evaluated the associations between Lp(a)-C and other CVD risk factors including plasma lipoprotein concentrations and body fatness in overweight and obese African American children.

Methods

A cross-sectional analysis was carried out using data from a sample of 121 African American children aged 9-11 years with Body Mass Index (BMI)'s greater than the 85th percentile. Body height, weight and waist circumference (WC) were measured. Fasting plasma concentrations of Lp(a)-C, Total cholesterol (TC), High density lipoprotein cholesterol (HDL-C), Very low density lipoprotein cholesterol (VLDL-C), Intermediate density lipoprotein cholesterol (IDL-C), Low density lipoprotein cholesterol (LDL-C), and Triacylglycerides (TAG) were analyzed using the vertical auto profile (VAP) cholesterol method.

Results

After adjusting for child age, gender, and pubertal status, Lp(a)-C was positively associated with both HDL-C and TC, and negatively associated with VLDL-C and TAG. Including BMIz and WC as additional covariates did not alter the direction of the relationships between Lp(a)-C and the other lipoproteins. Finally, after adjusting for the other plasma lipoproteins, Lp(a)-C remained strongly associated with HDL-C, whereas the associations of Lp(a)-C with the other lipoproteins were not significant when HDL-C was simultaneously included in the regression models.

Conclusions

Lp(a)-C was positively associated with HDL-C and this association is not influenced by other lipoprotein subclasses or by the degree of obesity. We conclude that Lp(a) cholesterol is not an independent risk factor for CVD in African American children.     

Comparative studies of phosphoenolpyruvate carboxylase from c(3) and c(4) plants

Phosphoenolpyruvate carboxylase (PEPC) from several C₃ plants was compared to maize PEPC by immunoblotting using an antibody against maize PEPC and by peptide mapping. In C₃ gramineous plants, PEPCs of slightly different monomeric sizes were detected as two bands for wheat and barley leaves, as three bands for etiolated maize leaves and as four bands for rice leaves by SDS-polyacrylamide gel electrophoresis and immunoblotting, whereas only one PEPC band was detected for maize leaves, a C₄ plant, or tobacco leaves, a dicotyledonous C₃ plant. The peptide fragment patterns of the lower molecular weight PEPC (major band in immunoblotting) in wheat leaves was similar to that of maize PEPC in peptide mapping by protein staining or by immunological detection, but the upper one (minor band) had a different pattern from the lower one in peptide mapping by immunological detection and few peptide fragments from this were recognized by the anti-(maize) PEPC antibody. These results suggest that there are multiple forms of PEPC subunits in the gramineous plants tested, and the major PEPC has a primary structure similar to that of maize PEPC. To obtain information about the expression of PEPCs in C₃ plants, changes in the amount of PEPC protein were investigated during the greening of rice and wheat seedlings. Judging from the regulation by light, there were two types of PEPCs in greening rice seedlings, one induced by light and the other reduced by it. Greening wheat seedlings also show a PEPC band induced by light. These findings indicate that some PEPCs in C₃ gramineous plants not only have structures similar to that of maize PEPC, but also are regulated by light in a similar manner.     

A brief review of bone adaptation to unloading

Weight-bearing bone is constantly adapting its structure and function to mechanical environments. Loading through routine exercises stimulates bone formation and prevents bone loss, but unloading through bed rest and cast immobilization as well as exposure to weightlessness during spaceflight reduces its mass and strength. In order to elucidate the mechanism underlying unloading-driven bone adaptation, ground-based in vitro and in vivo analyses have been conducted using rotating cell culturing and hindlimb suspension. Focusing on gene expression studies in osteoblasts and hindlimb suspension studies, this minireview introduces our recent understanding on bone homeostasis under weightlessness in space. Most of the existing data indicate that unloading has the opposite effects to loading through common signaling pathways. However, a question remains as to whether any pathway unique to unloading （and not to loading） may exist.     

Cytoplasmic domain of influenza B virus BM2 protein plays critical roles in production of infectious virus

Influenza B virus BM2 is a type III integral membrane protein that displays H⁺ ion channel activity. Analysis of BM2 knockout mutants has suggested that this protein is a necessary component for the capture of M1-viral ribonucleoprotein (vRNP) complex at the plasma membrane and for incorporation of vRNP complex into the virion during the assembly process. BM2 comprises 109 amino acid residues and possesses a longer cytoplasmic domain than the other 3 integral membrane proteins (hemagglutinin, neuraminidase, and NB). To explore whether the cytoplasmic domain of BM2 is important for infectious virus production, a series of BM2 deletion mutants lacking three to nine amino acid residues at the carboxyl terminus, BM2Δ107-109, BM2Δ104-109, and BM2Δ101-109, was generated by reverse genetics. Intracellular transport and incorporation into virions were indistinguishable between truncated BM2 proteins and wild-type BM2. The BM2Δ107-109 mutant produced levels of infectious virus similar to those of wild-type virus and displayed a spherical shape. However, the BM2Δ104-109 and BM2Δ101-109 mutants produced viruses containing dramatically reduced vRNP complex, as with BM2 knockout mutants, and formed enlarged, irregularly shaped virions. Moreover, gradient separation of membranes indicated that membrane association of M1 from mutants was greatly affected by carboxyl-terminal truncations of BM2. Studies of alanine substitution mutants further suggested that amino acid sequences in the 98-109 region are variable while those in the 86-97 region are a prerequisite for innate BM2 function. These results indicate that the cytoplasmic domain of the BM2 protein is required for firm association of the M1 protein with lipid membranes, vRNP complex incorporation into virions, and virion morphology.     

Glutamate levels control HT22 murine hippocampal cell death by regulating biphasic patterns of Erk1/2 activation: role of metabolic glutamate receptor 5

Extracellular glutamate concentration is a critical determinant of neuronal cell fate. We recently demonstrated that HT22 murine hippocampal cell viability was reduced by exposure to high concentrations of glutamate, whereas low concentrations promoted cell survival. Extracellular signal-regulated kinase (Erk)1/2 activation by glutamate is important for both glutamate-induced cell death and survival. In this study, we investigated the role of glutamate-induced or hydrogen peroxide (H₂O₂)-induced Erk1/2 activation in HT22 cell fate determination. Glutamate and H₂O₂ treatment similarly induced early (<1 h) Erk1/2 phosphorylation regardless of concentration. On the other hand, persistent Erk1/2 phosphorylation (16–24 h) was observed only in the presence of excess glutamate. Only the latter contributed to glutamate-induced cell death, which involved metabolic glutamate receptor 5. Our findings suggest that glutamate concentration modulates two distinct phases of Erk1/2 activation, which can explain the glutamate concentration-dependent determination of HT22 cell fate.     

Band Edge Engineering of Oxide Photoanodes for Photoelectrochemical Water Splitting: Integration of Subsurface Dipoles with Atomic‐Scale Control

One of the crucial parameters dictating the efficiency of photoelectrochemical water‐splitting is the semiconductor band edge alignment with respect to hydrogen and oxygen redox potentials. Despite the importance of metal oxides in their use as photoelectrodes, studies to control the band edge alignment in aqueous solution have been limited predominantly to compound semiconductors with modulation ranges limited to a few hundred mV. The ability to modulate the flat band potential of oxide photoanodes by as much as 1.3 V, using the insertion of subsurface electrostatic dipoles near a Nb‐doped SrTiO₃/aqueous electrolyte interface is reported. The tunable range achieved far exceeds previous reports in any semiconductor/aqueous electrolyte system and suggests a general design strategy for highly efficient oxide photoelectrodes.     

Diterpene phytoalexins are biosynthesized in and exuded from the roots of rice seedlings

Rice (Oryza sativa L.) produces a variety of diterpene phytoalexins, such as momilactones, phytocassanes, and oryzalexins. Momilactone B was previously identified as an allelopathic substance exuded from the roots of rice. We identified in this present study momilactone A and phytocassanes A-E in extracts of, and exudates from, the roots of rice seedlings. The concentration of each compound was of the same order of magnitude as that of momilactone B. Expression analyses of the diterpene cyclase genes responsible for the biosynthesis of momilactones and phytocassanes suggest that these phytoalexins found in roots are primarily biosynthesized in those roots. None of phytocassanes B-E exhibited allelopathic activity against dicot seedling growth, whereas momilactone A showed much weaker allelopathic activity than momilactone B. The exudation of diterpene phytoalexins from the roots might be part of a system for defense against root-infecting pathogens.