Relationship between quiet standing position and perceptibility of standing position in the anteroposterior direction

We investigated the relationship between an individual's center of pressure in the anteroposterior direction in quiet standing (QS) and perceptibility of different standing positions. The position of the center of pressure in the anteroposterior direction (CoPy position) while standing was represented as the percentage distance (%FL) from the hindmost point of the heel in relation to foot length. CoPy position in QS was located from 31 to 58%FL. Perceptibility of standing position was evaluated by the difference between the reference position and the subject's attempt to reproduce that position. Subjects were tested for their ability to reproduce reference positions selected randomly from a total of 13 positions at 5%FL increments from 20 to 80%FL. Using an approximation formula curve, we identified the relationship between reference position and reproduction absolute error. The standing position range with reproduction error exceeding 90% of the difference between the maximum and minimum errors was defined as the low perceptibility range of standing position. The approximation curve had one peak near QS. CoPy positions in QS were located in the low perceptibility range, except for five subjects with a more posterior location. The correlation coefficient between CoPy positions in QS (x) and reference position (y) showing maximum error was 0.70 and the regression line was y=0.464x+28.2; the intersection point with y=x was 53%FL. Reproduction absolute errors in reference positions at 20-30%FL and 70-80%FL were significantly smaller than those at 40-60%FL (p<0.05). We concluded the following. (1) Standing positions showing the lowest perceptibility are located close to the QS position; however, in subjects whose QS position is located more posteriorly, the standing position showing maximum error is more anterior. (2) Perceptibility of extreme forward- and backward-leaning positions is very high and independent of individual QS position.     

Roles of the human Rad51 L1 and L2 loops in DNA binding

The human Rad51 protein, a eukaryotic ortholog of the bacterial RecA protein, is a key enzyme that functions in homologous recombination and recombinational repair of double strand breaks. The Rad51 protein contains two flexible loops, L1 and L2, which are proposed to be sites for DNA binding, based on a structural comparison with RecA. In the present study, we performed mutational and fluorescent spectroscopic analyses on the L1 and L2 loops to examine their role in DNA binding. Gel retardation and DNA-dependent ATP hydrolysis measurements revealed that the substitution of the tyrosine residue at position 232 (Tyr232) within the L1 loop with alanine, a short side chain amino acid, significantly decreased the DNA-binding ability of human Rad51, without affecting the protein folding or the salt-induced, DNA-independent ATP hydrolysis. Even the conservative replacement with tryptophan affected the DNA binding, indicating that Tyr232 is involved in DNA binding. The importance of the L1 loop was confirmed by the fluorescence change of a tryptophan residue, replacing the Asp231, Ser233, or Gly236 residue, upon DNA binding. The alanine replacement of phenylalanine at position 279 (Phe279) within the L2 loop did not affect the DNA-binding ability of human Rad51, unlike the Phe203 mutation of the RecA L2 loop. The Phe279 side chain may not be directly involved in the interaction with DNA. However, the fluorescence intensity of the tryptophan replacing the Rad51-Phe279 residue was strongly reduced upon DNA binding, indicating that the L2 loop is also close to the DNA-binding site.     

Direct determination of glucuronide and sulfate of p-hydroxymethamphetamine in methamphetamine users' urine

Two conjugates of p-hydroxymethamphetamine (p-OHMA), p-OHMA-glucuronide (p-OHMA-Glu) and p-OHMA-sulfate (p-OHMA-Sul) have been identified in methamphetamine (MA) users' urine by using liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS-MS). The synthesis of p-OHMA-Glu and p-OHMA-Sul, and an LC-MS procedure for the simultaneous determination of MA and its four metabolites, amphetamine (AP), p-OHMA, p-OHMA-Glu and p-OHMA-Sul, in urine have also been established. After deproteinizing urine samples with methanol, LC-MS employing a C(18) semi-micro column with a gradient elution program provided the successful separations and MS determinations of these analytes within 20 min. Based on the established method, p-OHMA-Sul was detected at higher concentrations than p-OHMA-Glu in all of the three urine samples tested. These data suggest that sulfation is a major pathway in the MA phase II metabolism.     

Wnt signals can function as positional cues in establishing cell polarity

Wnt signaling plays important roles in cell polarization in diverse organisms, and loss of cell polarity is an early event in tumorigenesis caused by mutations in Wnt pathway genes. Despite this, the precise roles of Wnt proteins in cell polarization have remained elusive. In no organism has it been shown that the asymmetric position of a Wnt signal is essential to establishing a cell's polarity. Attempts to test this by ubiquitous expression of Wnt genes have suggested that Wnt signals might act only as permissive factors in cell polarization. Here we find, by using cell manipulations and ectopic gene expression in C. elegans, that the position from which Wnt signals are presented can determine the polarity of both embryonic and postembryonic cells. Furthermore, the position from which a Wnt signal is presented can determine the polarity of Frizzled receptor localization, suggesting that the polarizing effect of Wnt is likely to be direct. These results demonstrate that Wnt proteins can function as positional cues in establishing cell polarity.     

Role of hepatic STAT3 in brain-insulin action on hepatic glucose production

STAT3 regulates glucose homeostasis by suppressing the expression of gluconeogenic genes in the liver. The mechanism by which hepatic STAT3 is regulated by nutritional or hormonal status has remained unknown, however. Here, we show that an increase in the plasma insulin concentration, achieved either by glucose administration or by intravenous insulin infusion, stimulates tyrosine phosphorylation of STAT3 in the liver. This effect of insulin was mediated by the hormone's effects in the brain, and the increase in hepatic IL-6 induced by the brain-insulin action is essential for the activation of STAT3. The inhibition of hepatic glucose production and of expression of gluconeogenic genes induced by intracerebral ventricular insulin infusion was impaired in mice with liver-specific STAT3 deficiency or in mice with IL-6 deficiency. These results thus indicate that IL-6-STAT3 signaling in the liver contributes to insulin action in the brain, leading to the suppression of hepatic glucose production.     

The Plasmodium vivax homolog of the ookinete adhesive micronemal protein, CTRP

The Plasmodium circumsporozoite protein/thrombospondin-related anonymous protein-related protein (CTRP) is expressed at the mosquito midgut ookinete stage and is considered to be a transmission-blocking vaccine candidate. CTRP is composed of multiple von Willebrand factor A (vWA) and thrombospondin type 1 domains in the extracellular portion of the molecule, and a short acidic cytoplasmic domain that interacts with the actomyosin machinery. As a means to predict functionally relevant domains within CTRP we determined the nucleotide sequences of CTRP from the Plasmodium vivax Sall and the Plasmodium yoelii 17XL strains and characterized the conservation of domain architectures and motifs across Plasmodium genera. Sequence alignments indicate that the CTRP 1st to 4th vWA domains exhibit greater conservation, and thereby are perhaps functionally more important than the 5th and 6th domains. This point should be considered for the development of a transmission-blocking vaccine that includes CTRP recombinant subunit. To complement previous cellular studies on CTRP, we further determined the expression and cellular localization of CTRP protein in P. vivax and P. yoelii.     

Agrobacterium-mediated transformation of the ectomycorrhizal basidiomycete Tricholoma matsutake that produces commercially valuable fruit bodies, matsutake

Using agroinfection with a T-DNA vector carrying a hygromycin resistance marker, the recombinants were generated for the first time from the ectomycorrhizal basidiomycete Tricholoma matsutake, which produces commercially valuable fruit bodies, matsutake, during association with Pinus sp. plants. The transformation system may be useful in the genetic analysis of T. matsutake.     

Interactions between nitrogen and cytokinin in the regulation of metabolism and development

Inorganic nitrogen is a substrate for nitrogen assimilation and also functions as a signal triggering widespread changes in gene expression that modulate metabolism and development. To integrate the actions of the nitrogen signal at the whole plant level, plants use multiple signaling routes that communicate internal and external nitrogen status. One route depends on nitrate itself and one uses cytokinin as a messenger. Recent genome-wide research has shown that the nitrate-specific signal regulates a wide variety of metabolic processes including nitrogen and carbon metabolism, and cytokinin biosynthesis. Cytokinin-mediated signaling is related to the control of development, protein synthesis and acquisition of macronutrients. The coordination and interaction of both regulatory pathways is important for normal plant growth under variable nitrogen supply conditions.