Cell-free translation system with artificial lipid-monolayer particles as a unique tool for characterizing lipid-monolayer binding proteins.

Methods for functional analysis of proteins specifically localizing to lipid monolayers such as rubber particles and lipid droplets are limited. We have succeeded in establishing a system in which artificially prepared lipid monolayer particles are added to a cell-free translation system to confirm the properties of proteins that specifically bind to lipid monolayers in a translation-coupled manner.

Acylated plastoquinone is a novel neutral lipid accumulated in cyanobacteria.

Although cyanobacteria do not possess bacterial triacylglycerol (TAG)-synthesizing enzymes, the accumulation of TAGs and/or lipid droplets has been repeatedly reported in a wide range of species. In most cases, the identification of TAG has been based on the detection of the spot showing the mobility similar to the TAG standard in thin-layer chromatography (TLC) of neutral lipids. In this study, we identified monoacyl plastoquinol (acyl PQH) as the predominant molecular species in the TAG-like spot from the unicellular Synechocystis sp. PCC 6803 (S.6803) as well as the filamentous Nostocales sp., Nostoc punctiforme PCC 73102, and Anabaena sp. PCC 7120. In S.6803, the accumulation level of acyl PQH but not TAG was affected by deletion or overexpression of slr2103, indicating that acyl PQH is the physiological product of Slr2103 having homology with the eukaryotic diacylglycerol acyltransferase-2 (DGAT2). Electron microscopy revealed that cyanobacterial strains used in this study do not accumulate lipid droplet structures such as those observed in oleaginous microorganisms. Instead, they accumulate polyhydroxybutyrate (PHB) granules and/or aggregates of alkane, free C16 and C18 saturated fatty acids, and low amounts of TAG in the cytoplasmic area, which can be detected by staining with a fluorescent dye specific to neutral lipids. Unlike these lipophilic materials, acyl PQH is exclusively localized in the membrane fraction. There must be DGAT2-like enzymatic activity esterifying de novo-synthesized C16 and C18 fatty acids to PQH2 in the thylakoid membranes.

Localization of Lipid Droplets in Embryonic Axis Radicle Cells of Soybean Seeds under Various Imbibition Regimes Indicates Their Role in Desiccation Tolerance.

Desiccation tolerance allows plant seeds to remain viable during desiccation and subsequent re-hydration. In this study, we tried to develop an experimental system to understand the difference between desiccation tolerant and desiccation sensitive radicle cells by examining excised embryonic axes after re-desiccation and subsequent imbibition under various regimes. Embryonic axes excised from soybean (Glycine max (L.) Merr.) seeds imbibed for 3 h to 15 h which remained attached to the cotyledons during imbibition would grow normally after 24 h of desiccation and re-imbibition on wet filter paper. By contrast, when the embryonic axes excised after 3 h imbibition of seeds were kept on wet filter paper for 12 h to 16 h, their growth was significantly retarded after 24 h of desiccation and subsequent re-imbibition. Numerous lipid droplets were observed lining the plasma membrane and tonoplasts in radicle cells of desiccation tolerant embryonic axes before and after desiccation treatment. By contrast, the lipid droplets lining the plasma membrane and tonoplasts became very sparse in radicle cells that were placed for longer times on wet filter paper before desiccation. We observed a clear correlation between the amount of lipid droplets lining plasma membranes and the ability to grow after desiccation and re-imbibition of the excised embryonic axes. In addition to the reduction of lipid droplets in the cells, a gradual increase in starch grains was observed. Large starch grains accumulated in the radicle cells of those axes that failed to grow further.

TEM observation of compacted DNA of Synechococcus elongatus PCC 7942 using DRAQ5 labeling with DAB photooxidation and osmium black.

To visualize the fine structure of compacted DNA of Synechococcus elongatus PCC 7942, which appears at a specific time in the regular light/dark cycle prior to cell division, ChromEM with some modifications was applied. After staining DNA with DRAQ5, the cells were fixed and irradiated by red laser in the presence of 3,3'-diaminobenzidine and subsequently fixed with OsO4. A system with He-Ne laser (633 nm) was set up for efficient irradiation of the bacterial cells in aqueous solution. The compacted DNA was visualized by transmission electron microscopy, in ultrathin sections as electron dense staining by osmium black.

Fine structure of Aldrovanda vesiculosa L: the peculiar lifestyle of an aquatic carnivorous plant elucidated by electron microscopy using cryo-techniques.

The aquatic carnivorous plant Aldrovanda vesiculosa L. is critically endangered worldwide; its peculiar lifestyle raises many questions and poses problems both intriguing on their own and relevant to conservation. While establishing a culture system for its propagation and restoring its natural habitat in Hozoji pond in Saitama, Japan, we conducted ultrastructural observations to examine the various aspects of Aldrovanda's way of life. Electron microscopic observation in combination with cryo-techniques produced novel information which could not be obtained by other methods. Some of the results are: phosphorous is stored in petiole cells of turions during winter; mucilaginous guides are provided for pollen tubes in parietal placental ovaries; storage of potassium in the vicinity of the midrib of carnivorous leaves may contribute to the rapid closing of the carnivorous leaves; dynamic sequential changes of the ultrastructure of digestive glands are involved in the synthesis and secretion of digestive enzymes, including protease and acid phosphatase. These results should contribute significantly to our understanding of Aldrovanda and the detailed mechanisms of its life.

Para-crystalline membrane structures resembling prolamellar bodies in the invasion zones of indeterminate root nodules of Vicia faba L.

Novel para-crystalline structures resembling prolamellar bodies in etioplasts were found in the invasion zones of indeterminate root nodules of Vicia faba, which possess persistent meristems and exhibit sequential developmental stages. The para-crystalline structures existed in most cells in the area of the invasion zone and a hexagonal arrangement of tubular membranes was recognized. Extensive membranes, apparently procured from the structures, were often in contact with the bacteria in young infected cells. We propose that the para-crystalline structures serve as a reservoir of membranes for the formation of the numerous symbiosomes that propagate and fill the infected cells, and suggest naming them pro-symbiosome membrane bodies.

Backscattered electron imaging of high pressure frozen soybean root nodules visualizes formation of symbiosome membranes.

High-pressure frozen soybean root nodules were fractured and backscattered electron images were obtained from uncoated samples in a low vacuum scanning electron microscope equipped with a cryo-transfer system. Structures of infected cells were well preserved: numerous symbiosomes, as well as nuclei, plastids and mitochondria were observed without ice crystal damage. After appropriate sublimation of water, bacteria included in symbiosomes were visualized. Membrane accumulation near nuclei, and vesicles and tubular membranes, which possibly contribute to symbiosome membrane formation, could be observed in a near native state. The method promises to be widely applicable to visualize interaction between membranes in various biological systems.

Complete substitution of a secondary cell wall with a primary cell wall in Arabidopsis.

The bulk of a plant's biomass, termed secondary cell walls, accumulates in woody xylem tissues and is largely recalcitrant to biochemical degradation and saccharification1. By contrast, primary cell walls, which are chemically distinct, flexible and generally unlignified2, are easier to deconstruct. Thus, engineering certain primary wall characteristics into xylem secondary walls would be interesting to readily exploit biomass for industrial processing. Here, we demonstrated that by expressing AP2/ERF transcription factors from group IIId and IIIe in xylem fibre cells of mutants lacking secondary walls, we could generate plants with thickened cell wall characteristics of primary cell walls in the place of secondary cell walls. These unique, newly formed walls displayed physicochemical and ultrastructural features consistent with primary walls and had gene expression profiles illustrative of primary wall synthesis. These data indicate that the group IIId and IIIe AP2/ERFs are transcription factors regulating primary cell wall deposition and could form the foundation for exchanging one cell wall type for another in plants.

Backscattered electron imaging and elemental analysis of rapidly frozen plant cells using variable accelerating voltage.

Rapidly frozen rosemary leaves were observed at variable accelerating voltages in a low-vacuum scanning electron microscope equipped with a cryo transfer system. After water was sublimated from the fractured face of the leaf, distinct backscattered electron (BSE) images were obtained depending on the accelerating voltages applied. At 5 kV, surface cell wall structure was observed, whereas at 10 and 15 kV chloroplasts lining the inside of the cell wall and membrane were visualized. With energy dispersive X-ray microanalysis, elemental information corresponding to the BSE images was obtained. Besides visualization of the structures and elemental composition close to the living state, information on layers at different depths from the surface could be detected by varying the accelerating voltage in this system.

Phosphorylation of neuronal nitric oxide synthase at Ser1412 in the dentate gyrus of rat brain after transient forebrain ischemia.

We previously demonstrated that calmodulin-dependent protein kinase IIα (CaM-KIIα) phosphorylates nNOS at Ser(847) in the hippocampus after forebrain ischemia; this phosphorylation attenuates NOS activity and might contribute to resistance to post-ischemic damage. We also revealed that cyclic AMP-dependent protein kinase (PKA) could phosphorylate nNOS at Ser(1412)in vitro. In this study, we focused on chronological and topographical changes in the phosphorylation of nNOS at Ser(1412) after rat forebrain ischemia. The hippocampus and adjacent cortex were collected at different times, up to 24h, after 15min of forebrain ischemia. NOS was partially purified from crude samples using ADP agarose gel. Neuronal NOS, phosphorylated (p)-nNOS at Ser(1412), PKA, and p-PKA at Thr(197) were studied in the rat hippocampus and cortex using Western blot analysis and immunohistochemistry. Western blot analysis revealed that p-nNOS at Ser(1412) significantly increased between 1 and 6h after reperfusion in the hippocampus, but not in the cortex. PKA was cosedimented with nNOS by ADP agarose gel. Immunohistochemistry revealed that phosphorylation of nNOS at Ser(1412) and PKA at Thr(197) occurred in the subgranular layer of the dentate gyrus. Forebrain ischemia might thereby induce temporary activation of PKA at Thr(197), which then phosphorylates nNOS at Ser(1412) in the subgranular layer of the dentate gyrus.

Different modifications of phosphorylated Smad3C and Smad3L through TGF-ß after spinal cord injury in mice.

Transforming growth factor-ß (TGF-ß) is an anti-inflammatory cytokine and is expressed in the injured spinal cord. TGF-ß signals through receptors to activate Smad proteins, which translocate into the nucleus. In the present study, we investigated the chronological alterations and cellular locations of the TGF-ß/Smad signaling pathway following spinal cord injury (SCI) in mice. ELISA analysis showed that the concentration of interleukin-6 (IL-6) in injured spinal cords significantly increases immediately after SCI, while the concentration of TGF-ß gradually increased after SCI, peaked at 2 days, and then gradually decreased. Immunohistochemical studies revealed that Smad3 was mainly expressed in neurons of the spinal cord. Phosphorylated Smad3 at the C-terminus (p-Smad3C) was stained within the motor neurons in the anterior horn, while phosphorylated Smad3 at the linker regions (p-Smad3L) was expressed in astrocytes within gray matter. These findings suggest that SCI induces gradual increases in TGF-ß and induces different activation of p-Smad3C and p-Smad3L. Phosphorylated Smad3C might be involved in neuronal degeneration after SCI, and p-Smad3L may play a role in glial scar formation by astrocytes.

Deficiency of schnurri-2, an MHC enhancer binding protein, induces mild chronic inflammation in the brain and confers molecular, neuronal, and behavioral phenotypes related to schizophrenia.

Schnurri-2 (Shn-2), an nuclear factor-κB site-binding protein, tightly binds to the enhancers of major histocompatibility complex class I genes and inflammatory cytokines, which have been shown to harbor common variant single-nucleotide polymorphisms associated with schizophrenia. Although genes related to immunity are implicated in schizophrenia, there has been no study showing that their mutation or knockout (KO) results in schizophrenia. Here, we show that Shn-2 KO mice have behavioral abnormalities that resemble those of schizophrenics. The mutant brain demonstrated multiple schizophrenia-related phenotypes, including transcriptome/proteome changes similar to those of postmortem schizophrenia patients, decreased parvalbumin and GAD67 levels, increased theta power on electroencephalograms, and a thinner cortex. Dentate gyrus granule cells failed to mature in mutants, a previously proposed endophenotype of schizophrenia. Shn-2 KO mice also exhibited mild chronic inflammation of the brain, as evidenced by increased inflammation markers (including GFAP and NADH/NADPH oxidase p22 phox), and genome-wide gene expression patterns similar to various inflammatory conditions. Chronic administration of anti-inflammatory drugs reduced hippocampal GFAP expression, and reversed deficits in working memory and nest-building behaviors in Shn-2 KO mice. These results suggest that genetically induced changes in immune system can be a predisposing factor in schizophrenia.

Activation of JAK-STAT3 signaling pathway in chronic subdural hematoma outer membranes.

Chronic subdural hematoma (CSDH) is an inflammatory disease, the mechanism of which still remains to be elucidated. Interleukin-6 (IL-6), one of the inflammatory cytokines regulating janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway, is expressed in human CSDH fluid. The status of this signaling pathway in human CSDH outer membranes was examined in the present study using outer membranes obtained during trepanation surgery. Concentrations of IL-6 in human CSDH fluids were measured using an enzyme immuno-assay kit. Expression patterns of JAK1, STAT1, phosphorylated (p)-STAT1 at Tyr(701) and at Ser(727), STAT3, p-STAT3 at Tyr(705) and at Ser(727) and actin in outer membranes were examined by Western blot analysis and immunohistochemistry. IL-6 is significantly expressed in human CSDH fluids compared with control cerebrospinal fluid. JAK1, STAT1 and STAT3 were detected in all cases. The expression of p-STAT3 at Tyr(705) is more significant compared with that of p-STAT1 at Tyr(701). In some cases, p-STAT3 at Ser(727) could also be detected, while p-STAT1 at Ser(727) could not. The localizations of STAT1 and STAT3 were revealed to be present in fibroblasts in human CSDH outer membranes, especially when p-STAT3 at Tyr(705) was in the nuclei of fibroblasts. These findings suggest that JAK1-STAT3 signaling is dominantly activated in fibroblasts of human CSDH outer membranes compared with STAT1 and indicate the possibility that this JAK1-STAT3 pathway might be activated by IL-6 and play a critical role in progression of human CSDH.

Activation of Ras/MEK/ERK signaling in chronic subdural hematoma outer membranes.

Chronic subdural hematoma (CSDH) is considered to be an angiogenic disease. Vascular endothelial growth factor (VEGF), one of the important growth factors regulating angiogenesis, is expressed in the neomembranes and also in hematoma fluid, and the Ras/MEK/ERK signaling pathway has been implicated in angiogenesis by VEGF. In the present study, the status of this signaling pathway in CSDH outer membranes was examined using outer membranes obtained during trepanation surgery. The expression levels of Ras, Ras-GAP, c-Raf, MEK, ERK, phosphorylated (p)-ERK, endothelial nitric oxide synthase (eNOS) and actin were examined by western blot analysis; the expression of p-ERK was also examined by immunohistochemistry. Ras, Ras-GAP, c-Raf, MEK, ERK and eNOS were detected in all cases. In addition, the expression of p-ERK was confirmed in all cases, and p-ERK was localized to the endothelial cells of the vessels in CSDH outer membranes. These findings indicated that Ras/MEK/ERK signaling is activated in the CSDH outer membranes and suggested the possibility that the Ras/MEK/ERK pathway might be activated by VEGF and play a critical role in the angiogenesis of CSDHs.

Activation of STAT1 in neurons following spinal cord injury in mice.

The signal transducer and activator of transcription 1 (STAT1) has been reported to be associated with neuronal cell death after cerebral ischemia. On the contrary, STAT3 has been revealed to regulate cell survival. We examined the chronological alteration and cellular localization of phosphorylated (p)-JAK1, p-STAT1 and p-STAT3 following mild spinal cord injury (SCI) in mice. Western blot analysis indicated that JAK1 is significantly phosphorylated, accompanied by the phosphorylation of STAT1 at Tyr(701) within a similar timeframe. Immunofluorescence staining indicated that signal transduction of STAT3 is introduced into the nucleus of the neurons within the anterior horns; however, in mirror sections, that of STAT1 is limited to the cytoplasm. These findings suggest that STAT3 signal is predominantly transduced into the nucleus and plays a stronger role in neuronal survival than STAT1. Modulation of the functional balance between STAT1 and STAT3 might determine the survival or death of neurons after SCI.

Activation of PI3 kinase/Akt signaling in chronic subdural hematoma outer membranes.

Chronic subdural hematoma (CSDH) is an angiogenic disease that is recognized as a cause of treatable dementia with unknown pathogenesis. Vascular endothelial growth factor (VEGF), a potent growth factor regulating angiogenesis through the phosphatidylinositol 3-kinase (PI3-kinase)/Akt pathway, has been implicated in its etiology. The status of this signaling pathway in CSDH outer membranes was examined in the present study, using outer membranes obtained during trepanation surgery. Expressions of PI3-kinase, PKB-kinase, Akt, phosphorylated Akt at Ser(473) (p-Akt), endothelial nitric oxide synthase (eNOS), vascular endothelial-cadherin (VE-cadherin), and actin were examined by Western blot analysis, together with their immunohistochemistry. PI3-kinase, Akt, eNOS, and VE-cadherin were detected in all cases. The magnitude of the expression of p-Akt varied among cases; however, the localization was revealed to be present in endothelial cells of vessels in CSDH outer membranes, together with VEGF and VE-cadherin detected in endothelial cells of vessels. These findings suggest that the PI3-kinase/Akt signaling is activated in CSDH outer membranes, and indicate the possibility that the PI3 kinase/Akt pathway might be activated by VEGF and play a critical role in the angiogenesis of CSDH.

Immunohistochemical localization of mitochondrial fatty acid ß-oxidation enzymes in Müller cells of the retina.

The presence of a mitochondrial fatty acid ß-oxidation system in the retina was shown by immunohistochemistry. Fatty acids are considered to serve as a major energy source metabolized by fatty acid ß-oxidation together with glucose metabolized by glycolysis in the organs of the entire body, but almost nothing is known about this metabolic system in the retina. Adult rat retinae were subjected to immunofluorescence and immuno-electron microscopy for the localization of fatty acid ß-oxidation enzymes, together with western blot analysis for quantitation of the amount of enzyme proteins and DNA microarray analysis for gene expression. All the enzymes examined were shown to be present in the retina, but in small amounts, with the amount of protein and gene expression in the retina being about 1/10 of those in the liver. Immunohistochemistry at light and electron microscopic levels revealed the enzymes to be more preferentially localized to the mitochondria of Müller cells than the retinal neurons. The Müller cells were isolated from the retina and confirmed for the presence of mitochondrial fatty acid ß-oxidation enzymes. A mitochondrial fatty acid ß-oxidation system was thus shown to be present in the retina heterogeneously.

Oxidative stress activates STAT1 in basilar arteries after subarachnoid hemorrhage.

The signal transducer and activator of transcription 1 (STAT1) is one of the most important signaling molecule transducing signals from the cell surface in response to cytokines or growth factors. Subarachnoid hemorrhage (SAH) results in production of cytokines and growth factors in the CSF. We here investigated whether this signaling molecule is activated in the rat basilar artery after SAH. In a rat single-hemorrhage model of SAH, basilar arteries were obtained at various times until 7days after SAH. Western blot analysis with phosphorylated (p)-STAT1 at Tyr(701), p-STAT1 at Ser(727), STAT1, and actin antibodies was performed. The expression of STAT1 and p-STAT1 at Tyr(701) in basilar arteries was also examined by immunohistochemistry. Intracisternal injection of interleukin-6 (IL-6), hydrogen peroxide, or hydroxyl radical scavenger was conducted to examine for phosphorylation of STAT1. Western blot analysis showed STAT1 to be significantly phosphorylated at Tyr(701) and Ser(727) within 2h of SAH and to gradually decrease thereafter. Immunohistochemistry revealed this phosphorylation of STAT1 to occur in the outer membranes of the basilar artery. Intracisternal injection of hydrogen peroxide, but not IL-6, also significantly increased phosphorylation of STAT1 at Tyr(701). Hydroxyl radical scavenger significantly reduced phosphorylation of STAT1. These results indicate that reactive oxygen species, produced in the CSF after SAH, activates STAT1 molecule in the outer membranes of basilar arteries. This STAT1 signaling might contribute to morphological arterial wall changes in cerebral vasospasm.

Immunohistochemical localization of mitochondrial fatty acid ß-oxidation enzymes in rat testis.

The testis consists of two types of tissues, the interstitial tissue and the seminiferous tubule, which have different functions and are assumed to have different nutritional metabolism. The localization of enzymes of the mitochondrial fatty acid ß-oxidation system in the testis was investigated to obtain a better understanding of nutrient metabolism in the testis. Adult rat testis tissues were subjected to immunoblot analysis for quantitation of the amounts of enzyme proteins, to DNA microarray analysis for gene expression, and to immunofluorescence and immunoelectron microscopy for localization. Quantitative analysis by immunoblot and DNA microarray revealed that enzymes occur abundantly in Leydig cells in the interstitial tissue but much less so in the seminiferous tubules. Immunohistochemistry revealed that Leydig cells in the interstitial tissue and Sertoli cells in the seminiferous tubules contain a full set of mitochondrial fatty acid ß-oxidation enzymes in relatively plentiful amounts among the cells in the testis, but that this is not so in spermatogenic cells. This characteristic localization of the mitochondrial fatty acid ß-oxidation system in the testis needs further elucidation in terms of a possible role for it in the nutritional metabolism of spermatogenesis.

Strain-dependent viral dynamics and virus-cell interactions in a novel in vitro system supporting the life cycle of blood-borne hepatitis C virus.

UNLABELLED: We developed an in vitro system that can be used for the study of the life cycle of a wide variety of blood-borne hepatitis C viruses (HCV) from various patients using a three-dimensional hollow fiber culture system and an immortalized primary human hepatocyte (HuS-E/2) cell line. Unlike the conventional two-dimensional culture, this system not only enhanced the infectivity of blood-borne HCV but also supported its long-term proliferation and the production of infectious virus particles. Both sucrose gradient fractionation and electron microscopy examination showed that the produced virus-like particles are within a similar fraction and size range to those previously reported. Infection with different HCV strains showed strain-dependent different patterns of HCV proliferation and particle production. Fluctuation of virus proliferation and particle production was found during prolonged culture and was found to be associated with change in the major replicating virus strain. Induction of cellular apoptosis was only found when strains of HCV-2a genotype were used for infection. Interferon-alpha stimulation also varied among different strains of HCV-1b genotypes tested in this study. CONCLUSION: These results suggest that this in vitro infection system can reproduce strain-dependent events reflecting viral dynamics and virus-cell interactions at the early phase of blood-borne HCV infection, and that this system can allow the development of new anti-HCV strategies specific to various HCV strains.