Facilitation between extensor carpi radialis and pronator teres in humans: A study using a post-stimulus time histogram method

Group I muscle afferents modulate the excitability of motor neurons through excitatory and inhibitory spinal reflexes. Spinal reflex relationships between various muscle pairs are well described in experimental animals but not in the human upper limb, which exhibits a fine control of movement. In the present study, spinal reflexes between the extensor carpi radialis (ECR) and pronator teres (PT) muscles were examined in healthy human subjects using a post-stimulus time histogram method. Electrical stimulation of low-threshold afferents of ECR nerves increased the motor neuron excitability in 31 of 76 PT motor units (MUs) in all eight subjects tested, while stimulation of low-threshold afferents of PT nerves increased the motor neuron excitability in 36 of 102 ECR MUs in all 10 subjects. The estimated central synaptic delay was almost equivalent to that of homonymous facilitation. Mechanical stimulation (MS) of ECR facilitated 16 of 30 PT MUs in all five subjects tested, while MS of PT facilitated 17 of 30 ECR MUs in all six subjects. These results suggest excitatory reflex (facilitation) between PT and ECR. Group I afferents should mediate the facilitation through a monosynaptic path.     

Identification of a Novel Hypocholesterolemic Protein,Major Royal Jelly Protein 1, Derived from Royal Jelly

Royal jelly (RJ) intake lowers serum cholesterol levels in animals and humans, but the active component in RJ that lowers serum cholesterol level and its molecular mechanism are unclear. In this study, we set out to identify the bile acid-binding protein contained in RJ, because dietary bile acid-binding proteins including soybean protein and its peptide are effective in ameliorating hypercholesterolemia. Using a cholic acid-conjugated column, we separated some bile acid-binding proteins from RJ and identified the major RJ protein 1 (MRJP1), MRJP2, and MRJP3 as novel bile acid-binding proteins from RJ, based on matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Purified MRJP1, which is the most abundant protein of the bile acid-binding proteins in RJ, exhibited taurocholate-binding activity in vitro. The micellar solubility of cholesterol was significantly decreased in the presence of MRJP1 compared with casein in vitro. Liver bile acids levels were significantly increased, and cholesterol 7α-hydroxylase (CYP7A1) mRNA and protein tended to increase by MRJP1 feeding compared with the control. CYP7A1 mRNA and protein levels were significantly increased by MRJP1 tryptic hydrolysate treatment compared with that of casein tryptic hydrolysate in hepatocytes. MRJP1 hypocholesterolemic effect has been investigated in rats. The cholesterol-lowering action induced by MRJP1 occurs because MRJP1 interacts with bile acids induces a significant increase in fecal bile acids excretion and a tendency to increase in fecal cholesterol excretion and also enhances the hepatic cholesterol catabolism. We have identified, for the first time, a novel hypocholesterolemic protein, MRJP1, in RJ. Interestingly, MRJP1 exhibits greater hypocholesterolemic activity than the medicine β-sitosterol in rats.     

Classification and quantification of bacteriophage taxa in human gut metagenomes

Bacteriophages have key roles in microbial communities, to a large extent shaping the taxonomic and functional composition of the microbiome, but data on the connections between phage diversity and the composition of communities are scarce. Using taxon-specific marker genes, we identified and monitored 20 viral taxa in 252 human gut metagenomic samples, mostly at the level of genera. On average, five phage taxa were identified in each sample, with up to three of these being highly abundant. The abundances of most phage taxa vary by up to four orders of magnitude between the samples, and several taxa that are highly abundant in some samples are absent in others. Significant correlations exist between the abundances of some phage taxa and human host metadata: for example, ‘Group 936 lactococcal phages'' are more prevalent and abundant in Danish samples than in samples from Spain or the United States of America. Quantification of phages that exist as integrated prophages revealed that the abundance profiles of prophages are highly individual-specific and remain unique to an individual over a 1-year time period, and prediction of prophage lysis across the samples identified hundreds of prophages that are apparently active in the gut and vary across the samples, in terms of presence and lytic state. Finally, a prophage–host network of the human gut was established and includes numerous novel host–phage associations.     

Se14, Encoding a JmjC Domain-Containing Protein,Plays Key Roles in Long-Day Suppression of Rice Flowering through the Demethylation of H3K4me3 of RFT1

Floral transition from the vegetative to the reproductive growth phase is a major change in the plant life cycle and a key factor in reproductive success. In rice (Oryza sativa L.), a facultative short-day plant, numerous flowering time and flower formation genes that control floral transition have been identified and their physiological effects and biochemical functions have been clarified. In the present study, we used a Se14-deficient mutant line (HS112) and other flowering mutant lines to investigate the photoperiodic response, chromosomal location and function in the photoperiod sensitivity of the Se14 gene. We also studied the interactive effects of this locus with other crucial flowering time genes. We found that Se14 is independent of the known photoperiod-sensitive genes, such as Hd1 and Ghd7, and is identical to Os03g0151300, which encodes a Jumonji C (JmjC) domain-containing protein. Expression analysis revealed that the expressions of RFT1, a floral initiator known as a “florigen-like gene”, and Ehd1 were up-regulated in HS112, whereas this up-regulation was not observed in the original variety of ‘Gimbozu’. ChIP assays of the methylation states of histone H3 at lysine 4 (H3K4) revealed that the trimethylated H3K4 in the promoter region of the RFT1 chromatin was significantly increased in HS112. We conclude that Se14 is a novel photoperiod-sensitivity gene that has a suppressive effect on floral transition (flowering time) under long day-length conditions through the modification of chromatin structure by H3K4me3 demethylation in the promoter region of RFT1.     

Multidetector Computed Tomography-Based Microstructural Analysis Reveals Reduced Bone Mineral Content and Trabecular Bone Changes in the Lumbar Spine after Transarterial Chemoembolization Therapy for Hepatocellular Carcinoma

Purpose

It is well recognized that therapeutic irradiation can result in bone damage. However, long-term bone toxicity associated with computed tomography (CT) performed during interventional angiography has received little attention. The purpose of this study was to determine the prevalence of osteoporosis and trabecular microstructural changes in patients after transarterial chemoembolization (TACE) for hepatocellular carcinoma therapy using an interventional-CT system.

Materials and Methods

Spinal microarchitecture was examined by 64-detector CT in 81 patients who underwent TACE, 35 patients with chronic hepatitis, and 79 controls. For each patient, the volumetric CT dose index (CTDIv) during TACE (CTDIv (TACE)), the dose-length product (DLP) during TACE (DLP (TACE)), and CTDIv and DLP of routine dynamic CT scans (CTDIv (CT) and DLP (CT), respectively), were calculated as the sum since 2008. Using a three dimensional (3D) image analysis system, the tissue bone mineral density (tBMD) and trabecular parameters of the 12th thoracic vertebra were calculated. Using tBMD at a reported cutoff value of 68 mg/cm³, the prevalence of osteoporosis was assessed.

Results

The prevalence of osteoporosis was significantly greater in the TACE vs. the control group (39.6% vs. 18.2% for males, P<0.05 and 60.6% vs. 34.8% for females, P<0.01). Multivariate regression analysis demonstrated that sex, age, and CTDIv (CT) significantly affected the risk of osteoporosis. Of these indices, CTDIv (CT) had the highest area under the curve (AUC) (0.735). Correlation analyses of tBMD with cumulative radiation dose revealed weak correlations between tBMD and CTDIv (CT) (r ² = 0.194, P<0.001).

Conclusion

The prevalence of osteoporosis was significantly higher in post TACE patients than in control subjects. The cumulative radiation dose related to routine dynamic CT studies was a significant contributor to the prevalence of osteoporosis.     

Metabolic Engineering of a Glycerol-Oxidative Pathway in Lactobacillus panis PM1 for Utilization of Bioethanol Thin Stillage: Potential To Produce Platform Chemicals from Glycerol

Lactobacillus panis PM1 has the ability to produce 1,3-propanediol (1,3-PDO) from thin stillage (TS), which is the major waste material after bioethanol production, and is therefore of significance. However, the fact that L. panis PM1 cannot use glycerol as a sole carbon source presents a considerable problem in terms of utilization of this strain in a wide range of industrial applications. Accordingly, L. panis PM1 was genetically engineered to directly utilize TS as a fermentable substrate for the production of valuable platform chemicals without the need for exogenous nutrient supplementation (e.g., sugars and nitrogen sources). An artificial glycerol-oxidative pathway, comprised of glycerol facilitator, glycerol kinase, glycerol 3-phosphate dehydrogenase, triosephosphate isomerase, and NADPH-dependent aldehyde reductase genes of Escherichia coli, was introduced into L. panis PM1 in order to directly utilize glycerol for the production of energy for growth and value-added chemicals. A pH 6.5 culture converted glycerol to mainly lactic acid (85.43 mM), whereas a significant amount of 1,3-propanediol (59.96 mM) was formed at pH 7.5. Regardless of the pH, ethanol (82.16 to 83.22 mM) was produced from TS fermentations, confirming that the artificial pathway metabolized glycerol for energy production and converted it into lactic acid or 1,3-PDO and ethanol in a pH-dependent manner. This study demonstrates the cost-effective conversion of TS to value-added chemicals by the engineered PM1 strain cultured under industrial conditions. Thus, application of this strain or these research findings can contribute to reduced costs of bioethanol production.     

Sarcoptes scabiei var. hominis: Three-dimensional structure of a female imago and crusted scabies lesions by X-ray micro-CT

The three-dimensional structure of scabies mites (Sarcoptes scabiei var. hominis) and keratin layers affected by crusted scabies lesions were obtained using X-ray computed tomography at sub-micrometer and micrometer resolution, respectively (X-ray micro-CT). Clear three-dimensional images including internal structure of scabies mites were obtained. Utilizing reconstructed micro-CT data, the sections of the capitulum (head part), digestive organs, and legs are shown. The reconstructed capitulum shows a jaw-like structure capable of penetrating the keratin layer of the skin. The tip of the forelegs of female scabies mites has a flat disk structure that may be used to grasp the skin surface. The keratin layer of a crusted scabies lesion spontaneously exfoliated from a patient was also reconstructed by the X-ray micro-CT technique. Extracted sections from CT data revealed a network structure of tunnels made by scabies mites with numerous larvae and eggs inside the tunnels.     

β2-Chimaerin binds to EphA receptors and regulates cell migration

Ephrins and Eph receptors have key roles in regulation of cell migration during development. We found that the RacGAP β2-chimaerin (chimerin) bound to EphA2 and EphA4 and inactivated Rac1 in response to ephrinA1 stimulation. EphA4 bound to β2-chimaerin through its kinase domain and promoted binding of Rac1 to β2-chimaerin. In addition, knockdown of endogenous β2-chimaerin blocked ephrinA1-induced suppression of cell migration. These results suggest that β2-chimaerin is activated by EphA receptors and mediates the EphA receptor-dependent regulation of cell migration.

Structured summary

MINT-7013428: EphA1 (uniprotkb:Q60750) physically interacts (MI:0218) with Chimaerin beta 2 (uniprotkb:Q80XD1-2) and EphA4 (uniprotkb:O08542) by anti tag coimmunoprecipitation (MI:0007)MINT-7013515: Chimaerin beta 2 (uniprotkb:Q80XD1-2) physically interacts (MI:0218) with Rac1 (uniprotkb:P63001) by anti tag coimmunoprecipitation (MI:0007)MINT-7013410: EphA1 (uniprotkb:Q60750) physically interacts (MI:0218) with Chimaerin beta 1 (uniprotkb:Q80XD1-1) and EphA4 (uniprotkb:O08542) by anti tag coimmunoprecipitation (MI:0007)MINT-7013503: Chimaerin beta 1 (uniprotkb:Q80XD1-1) physically interacts (MI:0218) with EphA4 (uniprotkb:O08542) by anti tag coimmunoprecipitation (MI:0007)MINT-7013472: Chimaerin beta 2 (uniprotkb:Q80XD1-2) physically interacts (MI:0218) with EphA2 (uniprotkb:O43921) by anti tag coimmunoprecipitation (MI:0007)MINT-7013450: EphA1 (uniprotkb:Q60750) physically interacts (MI:0218) with EphA2 (uniprotkb:O43921) and Chimaerin beta 2 (uniprotkb:P52757-1) by anti tag coimmunoprecipitation (MI:0007)MINT-7013491: Chimaerin beta 2 (uniprotkb:Q80XD1-2) physically interacts (MI:0218) with EphA4 (uniprotkb:O08542) by anti tag coimmunoprecipitation (MI:0007)     

Molecular Chaperone BiP Interacts with Borna Disease Virus Glycoprotein at the Cell Surface

Borna disease virus (BDV) is characterized by highly neurotropic infection. BDV enters its target cells using virus surface glycoprotein (G), but the cellular molecules mediating this process remain to be elucidated. We demonstrate here that the N-terminal product of G, GP1, interacts with the 78-kDa chaperone protein BiP. BiP was found at the surface of BDV-permissive cells, and anti-BiP antibody reduced BDV infection as well as GP1 binding to the cell surface. We also reveal that BiP localizes at the synapse of neurons. These results indicate that BiP may participate in the cell surface association of BDV.Borna disease virus (BDV) belongs to the Bornaviridae family of nonsegmented, negative-strand RNA viruses and is characterized by highly neurotropic and noncytopathic infection (18, 33). BDV infects a wide variety of host species and causes central nervous system (CNS) diseases in animals, which are frequently associated with behavioral disorders (14, 19, 29, 31). BDV cell entry is mediated by endocytosis, following the attachment of viral envelope glycoprotein (G) to the cellular receptor (2, 7, 8). BDV G is translated as a precursor protein, GP, which is posttranslationally cleaved by the cellular protease furin to generate two functional subunits of the N (GP1) and C (GP2) termini (28). Recent studies revealed that GP1 is involved in virus interaction with as-yet-unidentified cell surface receptor(s) and that GP2 mediates a pH-dependent fusion event between viral and cell membranes (2, 7, 27). In addition, a previous work using a hippocampal culture system suggested that BDV G is required for viral dissemination in neurons (2); however, cellular factors involved in BDV cell entry, especially cell surface association, remain to be elucidated.To extend our understanding of the role of BDV G in the interaction with the cell plasma membrane, we transfected GP1 fused with hemagglutinin-tobacco etch virus protease cleavage site-FLAG tags (GP1-TAP) into human oligodendroglioma OL cells. GP1-TAP was purified using anti-FLAG M2 affinity gel (Sigma). To verify that GP1-TAP binds to OL cells, the cells were incubated with 4 μg/ml GP1-TAP, and binding was detected by anti-FLAG M2 antibody (Sigma). A flow cytometric analysis indicated that GP1-TAP binds to OL cells (Fig. ​(Fig.1A).1A). To further validate the binding of GP1-TAP, we tested whether GP1-TAP inhibits BDV infection. OL cells were pretreated with 4 μg/ml GP1-TAP for 30 min. Proteins purified from mock-transfected cells using an anti-FLAG M2 affinity gel served as a control. The cells were then mixed with cell-free BDV. After 1 h of absorption, the supernatants were removed and fresh medium was added. At 3 days postinfection, the viral antigens were stained with anti-nucleoprotein (N) monoclonal and anti-matrix (M) polyclonal antibodies. As shown in Fig. ​Fig.1B,1B, GP1-TAP reduced BDV infection by 40% compared to levels for mock-treated cells. This result was consistent with earlier reports showing that recombinant GP1 protein binds to the cell surface and inhibits BDV infection (6, 20).Open in a separate windowFIG. 1.BDV GP1 binds to the cell surface. (A) Binding of BDV GP1 to OL cells. OL cells were incubated with GP1-TAP (solid line), and its binding was detected using anti-FLAG M2 antibody and flow cytometry. As a control, cells incubated with proteins purified from mock-transfected cells were detected by an anti-FLAG M2 antibody (dotted line). (B) Inhibition of BDV infection by GP1. OL cells pretreated with GP1-TAP were inoculated with the BDV huP2br strain. Values are the means + standard deviations (SD) from three independent experiments. **, P < 0.01.To investigate the host factor(s) that mediates the interaction of GP1 with the cell surface, a combination of tandem affinity purification (TAP) and liquid chromatography tandem mass spectrometry analyses was designed (13). We transfected GP1-TAP into OL cells and then purified GP1 from cell homogenates using a TAP strategy. We compared the purified proteins from the whole-cell and cytosol fractions (Fig. ​(Fig.2A),2A), and the bands detected only in the whole-cell fraction were determined as GP1-binding proteins in the membrane and/or nuclear fractions. In addition to GP1 protein (Fig. ​(Fig.2A,2A, arrow), we identified a specific band around 80 kDa in the whole-cell homogenate, but not in the cytosol fraction (Fig. ​(Fig.2A,2A, arrowhead), and determined that the band corresponded to the BiP (immunoglobulin heavy chain-binding protein) molecular chaperone, also called glucose-regulated protein 78 (GRP78), by mass spectrometry analysis. We confirmed the specific interaction between endogenous BiP and BDV G in infected cells by immunoprecipitation analysis (Fig. ​(Fig.2B).2B). To map the binding domain on BiP to GP1, we constructed a series of deletion mutants of the green fluorescent protein (GFP)-tagged BiP plasmid (Fig. ​(Fig.2C).2C). We transfected the mutant plasmids into BDV-infected OL cells and then performed an immunoprecipitation assay using anti-GFP antibody (Invitrogen). As shown in Fig. ​Fig.2D,2D, BDV G was coimmunoprecipitated with truncated BiP mutants, except for BiPΔN-GFP, which lacks the ATP-binding domain of BiP (lane 3), suggesting that BiP interacts with GP1 via its N-terminal region.Open in a separate windowFIG. 2.BDV GP1 interacts with BiP molecular chaperone. (A) TAP analysis of BDV GP1. Proteins coimmunoprecipitated with GP1-TAP in OL cells were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and visualized by silver staining. Cyt, cytosol fraction; Wc, whole-cell homogenate. Arrow, GP1-TAP; arrowhead, BiP. (B) Coimmunoprecipitation (IP) of BDV G and endogenous BiP. BDV G was immunoprecipitated from BDV-infected OL cells by anti-BDV G polyclonal antibody. Endogenous BiP was then detected by anti-BiP monoclonal antibody (Becton Dickinson). IgG, immunoglobulin G. (C) Schematic representation of deletion mutants of recombinant BiP-GFP. The known functional regions are indicated. (D) Immunoprecipitation analysis of BiP-GFP mutants in BDV-infected OL cells. The deletion plasmids were transfected and immunoprecipitated by anti-GFP antibody. Specific binding was detected using anti-BDV G antibody. Lane 1, GFP; lane 2, BiP-GFP; lane 3, BiPΔN-GFP; lane 4, BiPΔPB-GFP; lane 5, BiPΔC-GFP.BiP is known to be resident primarily in the endoplasmic reticulum and functions as a molecular chaperone involved in the folding process of nascent proteins, mostly through interaction with its peptide-binding domain (12, 17, 21). On the other hand, BiP has been reported to serve as a coreceptor of certain viruses at the plasma membrane (15, 34). Recent studies also revealed that cell surface BiP mediates the internalization of its ligands into cells (1, 10). We first investigated whether BiP is expressed on the cell surface of BDV-permissive OL and 293T cells using an anti-BiP polyclonal antibody (H-129; Santa Cruz Biotechnology, Inc.). As shown in Fig. ​Fig.3A,3A, BiP expression is detected on the surface of both cell lines. This result is in agreement with recent observations that BiP is expressed on the surface of various types of cells (9, 10, 15, 23, 24, 34). We also investigated whether BiP is expressed on the cell surface of BDV-nonpermissive cell lines, such as HeLa and CHO cells. As shown in Fig. ​Fig.3A,3A, we detected BiP expression on the surface of HeLa, but not CHO, cells. These observations were confirmed by immunofluorescence analysis (Fig. ​(Fig.3B).3B). Note that BiP is clearly detected at the endoplasmic reticulum in the permeabilized CHO cells by the antibody (see Fig. S1 in the supplemental material), suggesting that BiP is expressed at a very low level, if at all, on the surface of CHO cells. We next examined whether cell surface BiP serves as a binding molecule of BDV GP1. To test this, we performed an inhibition assay using an anti-BiP polyclonal antibody (N-20; Santa Cruz Biotechnology, Inc.) which recognizes the N terminus of BiP. As shown in Fig. ​Fig.3C,3C, the antibody inhibited GP1 binding to the cell surface by 40%. Furthermore, BDV infection was found to decrease by 70% when cells were treated with the antibody (Fig. ​(Fig.3D3D).Open in a separate windowFIG. 3.Cell surface BiP mediates cell association of BDV. (A) Flow cytometric analysis was performed with anti-BiP antibody (H-129) in BDV-permissive (OL and 293T) and -nonpermissive (HeLa and CHO) cells (solid lines). Cells stained with normal rabbit immunoglobulin G were used as a control (dotted lines). (B) Immunofluorescence analysis was performed by using anti-BiP antibody (H-129) with BDV-permissive and -nonpermissive cells. Arrows indicate BiP staining at the membrane. Scale bars, 10 μm. (C) Inhibition of GP1 binding by anti-BiP antibody (N-20). OL cells were pretreated with anti-BiP antibody, followed by labeling with GP1. GP1 binding on the cell surface was detected using flow cytometry. Values are the means + SD from three independent experiments. *, P < 0.05. (D) Inhibition of BDV infection by anti-BiP antibody. OL cells were incubated with 10 μg/ml anti-BiP antibody or normal goat immunoglobulin G and then the cells were mixed with cell-free BDV. After 1 h absorption, the supernatants were replaced with fresh medium. Virus infection was measured by immunofluorescence analysis using anti-N and -M antibodies at 3 days postinfection. Values are the means + SD from three independent experiments. *, P < 0.05. IgG, immunoglobulin G.To investigate the role of cell surface BiP in the infection of BDV, the BiP expression was inhibited by short interfering RNA (siRNA) in OL cells (see Fig. S2A in the supplemental material). We selected an siRNA (Hs_HSPA5_4; Qiagen, Inc.) which could partially downregulate the cell surface expression of BiP (see Fig. S2B in the supplemental material). However, siRNA treatment of BiP did not influence the infectivity of BDV in OL cells (see Fig. S2C in the supplemental material). This may be due to an incomplete reduction of BiP expression on the cell surface. Alternatively, while BiP mediates at least in part the cell surface association of BDV particles, this result may exhibit the presence of another, as-yet-unidentified BDV G-binding protein that is involved in the binding and subsequent cell entry of BDV.Previous studies demonstrated that BDV can be traced centripetally and transsynaptically after olfactory, ophthalmic, or intraperitoneal inoculation (3, 25). Migration of BDV to the CNS after footpad infection can be prevented by sciatic nerve transection (3). These observations suggest that BDV may disseminate primarily via neural networks. Recently, it has been demonstrated that BDV G was expressed at the termini of neurites or at contact sites of neurites (2), suggesting that local assembly of BDV may take place at the presynaptic terminals of synapses, similar to assembly of other neurotropic viruses (22, 26, 32). If BiP localizes at synapse sites, BiP may efficiently participate in the transmission of BDV particles at the synapses. To evaluate this hypothesis, we examined BiP localization in primary culture of mouse hippocampal neurons. After in vitro culture for 17 days, BiP localization was determined by an immunofluorescence assay without permeabilization. As shown in Fig. ​Fig.4A,4A, BiP signals were clearly detected at neurites, including the contact sites between dendrites and axons, as punctate staining (arrows), suggesting that BiP is expressed at the neuronal surface, most likely at the synapses. We next examined the localization of BiP with postsynaptic density 95 (PSD-95), a marker of postsynaptic density (5). Although BiP signals were detected mainly in the perinuclear area of the hippocampal neurons, punctate staining was also found at neurites colocalized with PSD-95 (Fig. ​(Fig.4B,4B, arrows). Taken together, these observations suggested that BiP is distributed at the synaptic surface, including the postsynaptic membrane, of neurons, a possible site for BDV budding and entry (2).Open in a separate windowFIG. 4.BiP localizes at the synaptic surface of hippocampus neurons. (A) Localization of BiP at synaptic surface. Hippocampal neurons were immunostained with anti-BiP antibody (N-20) without permeabilization. A differential interference contrast (DIC) image is shown. Dotted lines in the Merge panel indicate the dendrite outline. Arrows indicate BiP staining at the contact sites between axons and dendrites. (B) Colocalization between BiP and a postsynaptic protein. Hippocampal neurons were immunostained with anti-BiP (N-20) and anti-PSD-95 (Millipore) antibodies. Arrows indicate colocalized signals of BiP and PSD-95 at neurites. Scale bars, 10 μm.In summary, this study demonstrates that BiP is a GP1-binding protein at the synaptic surface. This is the first report showing the BDV G-binding factor on the cell surface. The first step of BDV entry might be mediated by the interaction of GP1 with as-yet-unidentified cell surface receptors, which may form a complex with other molecules, such as BiP. We showed that treatment with anti-BiP antibody affects BDV infection as well as GP1 binding to the cell surface (Fig. ​(Fig.3).3). Furthermore, synaptic distribution of BiP was found in hippocampal primary neurons (Fig. ​(Fig.4).4). These findings strongly suggest that BiP plays critical roles in BDV association with the neuronal surface via interaction with GP1. On the other hand, a BDV-nonpermissive cell line, HeLa, appeared to express BiP on the cell surface, suggesting that the cell surface BiP may not be necessarily involved in the infectivity of BDV. A recent study by Clemente et al. (6) revealed that following initial attachment to the cell surface, BDV is recruited to the plasma membrane lipid raft (LR) prior to internalization of the particles. The study suggested that BDV may use the LR as a platform to interact with additional host cell factor(s) required for efficient BDV internalization. Because BiP does not contain transmembrane regions, BiP needs another host protein(s) with transmembrane regions on the cell surface. It has been reported that cell surface BiP interacts with diverse proteins, such as major histocompatibility complex class I molecules (34), the voltage-dependent anion channel (9), and the DnaJ-like protein MTJ-1 (4), all of which associate with LR in the plasma membrane (16, 24, 35). Once BDV has attached to the cell surface, it might utilize such BiP-associated LR proteins for efficient cell surface attachment or internalization. Previously, it has been proposed that kainate 1 (KA-1) receptor might represent the BDV receptor within the CNS (11). Because some glutamate receptors are shown to bind to BiP (30), KA-1 receptors might interact with BiP and serve as a receptor complex for BDV. Further studies are required for a full understanding of the cell association processes, especially receptor binding, of BDV.      

Changes in composition and content of mycolic acids in glutamate-overproducing Corynebacterium glutamicum

Overproduction of glutamate by Corynebacterium glutamicum is induced by biotin limitation or by the supplementation of specific detergents, sublethal amounts of penicillin, or cerulenin. But, it remains unclear why these different treatments, which have different sites of primary action, produce similar effects.In this study, it was found that the cellular content of mycolic acids--characteristic constituents of Corynebacterineae that are synthesized from fatty acids and form a cell surface layer--decreased under all conditions that induced glutamate overproduction. Furthermore, short mycolic acids increased under conditions of biotin limitation and cerulenin supplementation. These results suggest that different treatments produce the same effect that causes defects in the mycolic acid layer. This is perhaps one of the key factors in overproduction of glutamate by C. glutamicum.