Cytoplasmic oxysterol-binding proteins: sterol sensors or transporters?

Families of oxysterol-binding protein (ORP) homologues are present in eukaryotes from yeast to man. Their hallmark feature is a characteristic ligand binding domain that, for several family members, has been shown to accommodate different oxysterols and/or cholesterol. ORPs of the “long” subtype contain targeting determinants for the endoplasmic reticulum and to other organelle membranes, the most prominent of which are phosphoinositide-binding pleckstrin homology domains, while “short” ORPs comprise a ligand binding domain with little additional sequences. There is increasing evidence that both long and short ORPs can be enriched at membrane contact sites, junctions of the endoplasmic reticulum with other organelles, where they are suggested to execute regulatory or sterol transfer functions. In this review we discuss the current evidence for putative roles of ORPs as sterol sensors or transporters.     

Plastic changes in head size during juvenile development of the butterfly <Emphasis Type="Italic">Pieris napi</Emphasis>

Among herbivorous insects, the ability to change adaptive traits plastically in response to novel host plants is advantageous for coping with sudden environmental shifts. The host plants in our study were two closely related species, viz., Arabis flagellosa (tougher leaves, i.e., they are physically defended) and A. gemmifera (softer leaves that are physiologically defended). We demonstrated that young larvae of the butterfly Pieris napi are able to plastically change head size during development in response to changes in food plant species. When larvae were fed the physically defended A. flagellosa, the head sizes of third instar larvae emerging from eggs originally collected from leaves of both A. flagellosa and A. gemmifera became identically larger. When larvae fed on the physiologically defended A. gemmifera, the head sizes of third instar larvae emerging from eggs originally collected from leaves of both A. flagellosa and A. gemmifera became identically smaller. When leaves of A. flagellosa were presented to fourth instars reared on A. flagellosa, larvae with larger heads consumed more food than those with smaller heads. In contrast, when leaves of the physiologically defended A. gemmifera were presented to fourth instar larvae reared on A. gemmifera, larvae with smaller heads processed more food than those with larger heads. Hence, larvae of P. napi retain the capacity for adaptive plastic responses to novel host plant species.     

Vitamin K suppresses the lipopolysaccharide-induced expression of inflammatory cytokines in cultured macrophage-like cells via the inhibition of the activation of nuclear factor κB through the repression of IKKα/β phosphorylation

Vitamin K is essential for blood coagulation and bone metabolism in mammals. This vitamin functions as a cofactor in the posttranslational synthesis of γ-carboxyglutamic acid (Gla) from glutamic acid residues. However, other functions of vitamin K have been reported recently. We previously found that vitamin K suppresses the inflammatory reaction induced by lipopolysaccharide (LPS) in rats and human macrophage-like THP-1 cells. In this study, we further investigated the mechanism underlying the anti-inflammatory effect of vitamin K by using cultures of LPS-treated human- and mouse-derived cells. All the vitamin K analogues analyzed in our study exhibited varied levels of anti-inflammatory activity. The isoprenyl side chain structures, except geranylgeraniol, of these analogues did not show such activity; warfarin did not interfere with this activity. The results of our study suggest that the 2-methyl-1,4-naphtoquinone ring structure contributes to express the anti-inflammatory activity, which is independent of the Gla formation activity of vitamin K. Furthermore, menaquinone-4, a form of vitamin K₂, reduced the activation of nuclear factor κB (NFκB) and inhibited the phosphorylation of IKKα/β after treatment of cells with LPS. These results clearly show that the anti-inflammatory activity of vitamin K is mediated via the inactivation of the NFκB signaling pathway.     

Differences in host plant selection among three Athalia sawflies feeding on crucifers in Japan

Abstract 1. The ways of using host plants were compared among the three Athalia sawflies [ A. japonica (Klug), A. rosae ruficornis Jakovlev, and A. infumata (Marlatt)] feeding on crucifers in Japan to determine whether host specialisation can explain the difference in their life-history traits. The occurrence of their larvae was examined on each crucifer species in the field, and the suitability of each crucifer species for the three successive steps of host use by the sawflies was evaluated: microhabitat selection by adult females, female oviposition, and larval growth.
2. There were 11 species of crucifer in the study area, and A. japonica , A. rosae , and A. infumata used nine, seven, and eight species respectively. Thus, sawfly host ranges overlapped.
3. Adult females of A. japonica , A. rosae , and A. infumata preferred shady clumps of crucifers, sunny clumps of crucifers, and disturbed areas respectively.
4. Unsuitable hosts for larval performance such as Brassica oleracea and Arabis plants were eliminated from the host ranges of the three sawflies.
5. Once they chose microhabitats, the suitability of each host plant for female oviposition and larval growth was similar.
6. Because of the divergent preferences for microhabitats, the host plants that were suitable for all the three steps were restricted to different sets of plants among the sawflies: Cardamine for A. japonica , cultivated crucifers ( Raphanus and Brassica ) for A. rosae , and Rorippa for A. infumata . These plants could be recognised as the respective primary host plants.
7. The spatio-temporal distributions of primary hosts were consistent with and explained the pattern of diapause and migration of each sawfly, suggesting that host specialisation caused their life-history traits to differentiate.     

A neutrophil elastase inhibitor (ONO-5046) reduces neurologic damage after spinal cord injury in rats

In view of a cytoprotective effect of elastase inhibitor on chemokine-mediated tissue injury, we examined the neuroprotective effect of ONO-5046, a specific inhibitor of neutrophil elastase, in rats with spinal cord injury. Standardized spinal cord compression markedly increased cytokine-induced neutrophil chemo-attractant (CINC)-1 mRNA and protein. Their increases correlated with neurologic severity of injured rats. Immunohistochemically, CINC-1 protein was detected sequentially in vascular endothelial cells at 4 h, in perivascular neutrophils at 8 h, and in neutrophils infiltrating into cord substance at 12 h. Pretreatment with ONO-5046 (50 mg/kg) markedly ameliorated motor disturbance in injured rats, and reduced CINC-1 protein and mRNA expression. ONO-5046 also significantly reduced the increase of neutrophil accumulation or infiltration estimated by myeloperoxidase activity, and the extent of vascular permeability by Evans blue extravasation in the injured cord segment in comparison to control animals receiving vehicle. These results suggest that CINC-1 contributed to inflammation in rat spinal cord injury and ONO-5046 attenuated neurologic damage partly by blocking CINC-1 production of the chemoattractant, preventing neutrophil activation and vascular endothelial cell injury.     

Erratum to "Parathyroid hormone-related peptide is involved in protection against invasion of tooth germs by bone via promoting the differentiation of osteoclasts during tooth development"

Proteoglycans, the molecules of extracellular matrix, carry a highly negative charge due to their glycosaminoglycan (GAG) chains and large volumes. They were considered to play a secondary role in activities like cell division, adhesion, blood coagulation, etc. until the importance of their sugar chains in the fibroblast growth factor (FGF) signalling was discovered (Science 252 (1991) 1705; Cell 64 (1991) 841). Studies of mutations in the genes sugarless(sgl) and sulfateless (sfl) have proved that the proteoglycans involved in Wg signalling contain heparan sulfate GAG chains (Development 124 (1997) 2623; Development 124 (1997) 3055; Development 124 (1997) 3565; Development 126 (1999) 3715). This has led to the attribution of specific functions to these molecules (J. Cell Biol. 148 (2000) 227). The Glypican family of heparan sulfate proteoglycans (HSPGs) is characterized by core proteins with conserved cysteine residues and attachment to the cell surface by a glycosylphosphatidyl inositol (GPI) anchor. This may lead to endocytic pathways that are different from other HSPGs, higher lateral mobility and possible apical localisation in a cell (Proc. Natl. Acad. Sci, USA 85 (1988) 9557). Variations in their HS contents may effect binding properties and localisation (J. Cell Biol. 124 (1994) 149; J. Cell Biol. 132 (1996) 487), thus specialising each member for a unique biological function. Glypicans play important roles in morphogenetic pathways, e.g. human glypican 3 (GPC3) is mutated in Simpson-Golabi-Behmel syndrome making an individual prone to tumours (Nat. Genet. 12 (1996) 241). Dally, the first Drosophila member of the family, is essential for the wingless and decapentaplegic signalling pathways (Development 121 (1995) 3687; Development 124 (1997) 4113). Here, we report a new Drosophila glypican, dally-like protein (dlp) with all the features of a glypican. Based on expression studies we report its colocalisation with Wg.     

Sequential rapid adaptation of indigenous parasitoid wasps to the invasive butterfly Pieris brassicae

The introduction of a new species can change the characteristics of other species within a community. These changes may affect discontiguous trophic levels via adjacent trophic levels. The invasion of an exotic host species may provide the opportunity to observe the dynamics of changing interspecific interactions among parasitoids belonging to different trophic levels. The exotic large white butterfly Pieris brassicae invaded Hokkaido Island, Japan, and quickly spread throughout the island. Prior to the invasion, the small white butterfly P. rapae was the host of the primary parasitoid Cotesia glomerata, on which both the larval hyperparasitoid Baryscapus galactopus and the pupal hyperparasitoid Trichomalopsis apanteroctena depended. At the time of the invasion, C. glomerata generally laid eggs exclusively in P. rapae. During the five years following the invasion, however, the clutch size of C. glomerata in P. rapae gradually decreased, whereas the clutch size in P. brassicae increased. The field results corresponded well with laboratory experiments showing an increase in the rate of parasitism in P. brassicae. The host expansion of C. glomerata provided the two hyperparasitoids with an opportunity to choose between alternative hosts, that is, C. glomerata within P. brassicae and C. glomerata within P. rapae. Indeed, the pupal hyperparasitoid T. apanteroctena shifted its preference gradually to C. glomerata in P. brassicae, whereas the larval hyperparasitoid B. galactopus maintained a preference for C. glomerata in P. rapae. These changes in host preference may result from differential suitability of the two host types. The larval hyperparasitoid preferred C. glomerata within P. rapae to C. glomerata within P. brassicae, presumably because P. brassicae larvae attacked aggressively, thereby hindering the parasitization, whereas the pupal hyperparasitoid could take advantage of the competition-free resource by shifting its host preference. Consequently, the invasion of P. brassicae has changed the host use of the primary parasitoid C. glomerata and the pupal hyperparasitoid T. apanteroctena within a very short time.     

Long-term microstructural analyses of hydroxyapatite implanted in rats using laser-Raman spectrometry and scanning electron microscopy.

To investigate the long-term surface microstructure of a synthetic auditory ossicle (Apaceram) composed of dense hydroxyapatite (HA), thin HA disks were implanted subcutaneously into the interscapular regions of 12 rats. After 6, 14 and 20 months, implanted HA surfaces were observed using stereoscopic microscopy, scanning electron microscopy (SEM) and laser-Raman spectrometry. Visual observation by SEM at 6 months and by stereoscopic microscopy at 14 months indicated a progressive degradation of the HA disk surfaces implanted in the subcutaneous tissue. Visual observation by SEM at 14 and 20 months and by stereoscopic microscopy at 20 months indicated a progressive redeposition on the surfaces of the implants. Raman spectra compared half-peak breadths of v1 signal (PO4(3-), 960 cm(-1)) on the gray and white surface areas of implanted HA disks observed by stereoscopic microscopy. Analysis demonstrates that demineralization at 14 months and remineralization at 20 months occur on the gray areas; demineralization at 6 months and remineralization at 14 months occur on the white areas.     

A pitfall in using BODIPY dyes to label lipid droplets for fluorescence microscopy

The lipid droplet (LD) has become a focus of intense research. Fluorescence labeling is indispensable for the cell biological analysis of the LD, and a lipophilic fluorescence dye, BODIPY 493/503, which emits bright green fluorescence has been used extensively for LD labeling. The dye is convenient for double fluorescence labeling, but we noticed that it emits red fluorescence under certain conditions, which could lead to erroneous interpretations. We propose a protocol to preclude such a possibility.     

Lysosomal accumulation of mTOR is enhanced by rapamycin

The mammalian target of rapamycin (mTOR) is a key regulator of cell growth that integrates signals from growth factors and nutrients. Recent studies have shown that an mTOR-containing complex, mTORC1, is targeted to lysosomes in the presence of amino acids and activated by Rheb GTPase resident in that compartment. In this study, we found that treatment with the mTOR inhibitors rapamycin and Torin1 significantly enhanced lysosomal accumulation of mTOR and Raptor. This phenomenon was not observed in the absence of amino acids but was restored upon addition of l-leucine or protein synthesis inhibitors. mTOR was not concentrated in autophagosomes that were induced by rapamycin. These results suggest that the lysosome harbors both active and inactive forms of mTOR in the presence of amino acids.