Heme Requirement of a Novel Yeast-lysing Bacterium

A novel yeast-lysing bacterium (YLM-1) grew on nutrient agar containing yeast cell-free extract, but not on nutrient agar. We searched for the growth factor for YLM-1, which turned out to be hemin or hemoproteins, catalase or horseradish peroxidase. Also, the effects of growth accelerators and inhibitors on H₂O₂ metabolism were discussed.     

New information on host plants and distribution ranges of an invasive gall midge, <Emphasis Type="Italic">Contarinia maculipennis</Emphasis> (Diptera: Cecidomyiidae), and its congeners in Japan

Gall midges of the genus Contarinia (Diptera: Cecidomyiidae) that infest the flower buds of various plant species have been newly found in Japan in recent years. Those infesting the flower buds of Pseuderanthemum laxiflorum (A. Gray) Hubbard ex Baillon (Amaranthaceae) and Jasminum sambac (Linnaeus) Aiton (Oleaceae) in Okinawa Prefecture, and Dendrobium spp. (Orchidaceae) in Mie Prefecture were identified, on the basis of morphological features and molecular information, as an invasive gall midge, C. maculipennis Felt. C. maculipennis was recorded in Mie Prefecture for the first time, and P. laxiflorum is newly regarded as one of the host plants of C. maculipennis. Three other Contarinia gall midges that we found infesting the flower buds of Lycopersicon esculentum Miller, Capsicum annuum Linnaeus (Solanaceae), and Oxalis corniculata Linnaeus (Oxalidaceae) were not identical with C. maculipennis. Among these, the first two, which infested solanaceous plants, were identical. However, the species other than C. maculipennis could not be identified to the species level because morphological differences were obscure and DNA sequencing data of allied congeners have not yet been registered on GenBank.     

Histone deacetylase inhibitors de-repress tyrosine hydroxylase expression in the olfactory bulb and rostral migratory stream

Most olfactory bulb (OB) interneurons are derived from neural stem cells in the subventricular zone (SVZ) and migrate to the OB via the rostral migratory stream (RMS). Mature dopaminergic interneurons in the OB glomerular layer are readily identified by their synaptic activity-dependent expression of tyrosine hydroxylase (TH). Paradoxically, TH is not expressed in neural progenitors migrating in the RMS, even though ambient GABA and glutamate depolarize these progenitors. In forebrain slice cultures prepared from transgenic mice containing a GFP reporter gene under the control of the Th 9 kb upstream regulatory region, treatment with histone deacetylase (HDAC) inhibitors (either sodium butyrate, Trichostatin A or Scriptaid) induced Th-GFP expression specifically in the RMS independently of depolarizing conditions in the culture media. Th-GFP expression in the glomerular layer was also increased in slices treated with Trichostatin A, but this increased expression was dependent on depolarizing concentrations of KCl in the culture media. Th-GFP expression was also induced in the RMS in vivo by intra-peritoneal injections with either sodium butyrate or valproic acid. Quantitative RT-PCR analysis of neurosphere cultures confirmed that HDAC inhibitors de-repressed Th expression in SVZ-derived neural progenitors. Together, these findings suggest that HDAC function is critical for regulating Th expression levels in both neural progenitors and mature OB dopaminergic neurons. However, the differential responses to the combinatorial exposure of HDAC inhibitors and depolarizing culture conditions indicate that Th expression in mature OB neurons and neural progenitors in the RMS are regulated by distinct HDAC-mediated mechanisms.     

Lectin-mediated resistance impairs plant virus infection at the cellular level

Plants possess a multilayered defense response, known as plant innate immunity, to infection by a wide variety of pathogens. Lectins, sugar binding proteins, play essential roles in the innate immunity of animal cells, but the role of lectins in plant defense is not clear. This study analyzed the resistance of certain Arabidopsis thaliana ecotypes to a potexvirus, plantago asiatica mosaic virus (PlAMV). Map-based positional cloning revealed that the lectin gene JACALIN-TYPE LECTIN REQUIRED FOR POTEXVIRUS RESISTANCE1 (JAX1) is responsible for the resistance. JAX1-mediated resistance did not show the properties of conventional resistance (R) protein-mediated resistance and was independent of plant defense hormone signaling. Heterologous expression of JAX1 in Nicotiana benthamiana showed that JAX1 interferes with infection by other tested potexviruses but not with plant viruses from different genera, indicating the broad but specific resistance to potexviruses conferred by JAX1. In contrast with the lectin gene RESTRICTED TEV MOVEMENT1, which inhibits the systemic movement of potyviruses, which are distantly related to potexviruses, JAX1 impairs the accumulation of PlAMV RNA at the cellular level. The existence of lectin genes that show a variety of levels of virus resistance, their targets, and their properties, which are distinct from those of known R genes, suggests the generality of lectin-mediated resistance in plant innate immunity.     

Role of oxygen-derived free radicals in Helicobacter pylori water extract-induced mouse skin carcinogenesis

Helicobacter pylori (H. pylori) infection, the main cause of chronic gastritis, increases gastric cancer risk. The infection causes inflammatory cells to produce reactive oxygen metabolites that may damage DNA and promote carcinogenesis. However, its precise role in gastric carcinogenesis is as yet unknown. Recently we reported that H. pylori water extract (HPE) has an initiating activity on two-stage mouse skin carcinogenesis. In this study, we investigated the effects of anti-oxidants, ascorbic acid and a combination of superoxide dismutase (CuZnSOD)and catalase, on two-stage mouse skin carcinogenesis. Ascorbic acid and CuZnSOD/catalase were given to mice during the period of HPE-initiation. Both the ascorbic acid and CuZnSOD/catalase treatment attenuated the incidence of tumor formation. The present results suggest that HPE induces tumor formation via reactive oxygen species (ROS) production.     

Detection of an invasive gall-inducing pest, Quadrastichus erythrinae (Hymenoptera: Eulophidae), causing damage to Erythrina variegata L. (Fabaceae) in Okinawa Prefecture, Japan

In 2005, Quadrastichus erythrinae Kim, 2004 (Hymenoptera: Eulophidae), which induces stem, petiole, and leaf galls on Erythrina variegata L. (Fabaceae), was found on the following six islands in Okinawa Prefecture, Japan: Okinawa, Kume, Miyako, Ishigaki, Iriomote, and Hateruma. Galls were also found in Vietnam. In Japan, no further infestation records have been reported from any of Japan's other south‐western prefectures where Erythrina species grow. Because no Erythrina galls were observed in Okinawa Prefecture before 2005, Q. erythrinae seems to have invaded quite recently.     

Early sexual dimorphism in the developing gut microbiome of northern elephant seals

The gut microbiome is an integral part of a species' ecology, but we know little about how host characteristics impact its development in wild populations. Here, we explored the role of such intrinsic factors in shaping the gut microbiome of northern elephant seals (Mirounga angustirostris) during a critical developmental window of 6 weeks after weaning, when the pups stay ashore without feeding. We found substantial sex differences in the early‐life gut microbiome, even though males and females could not yet be distinguished morphologically. Sex and age both explained around 15% of the variation in gut microbial beta diversity, while microbial communities sampled from the same individual showed high levels of similarity across time, explaining another 40% of the variation. Only a small proportion of the variation in beta diversity was explained by health status, assessed by full blood counts, but clinically healthy individuals had a greater microbial alpha diversity than their clinically abnormal peers. Across the post‐weaning period, the northern elephant seal gut microbiome was highly dynamic. We found evidence for several colonization and extinction events as well as a decline in Bacteroides and an increase in Prevotella, a pattern that has previously been associated with the transition from nursing to solid food. Lastly, we show that genetic relatedness was correlated with gut microbiome similarity in males but not females, again reflecting early sex differences. Our study represents a naturally diet‐controlled and longitudinal investigation of how intrinsic factors shape the early gut microbiome in a species with extreme sex differences in morphology and life history.     

Involvement of autocrine CXCL12/CXCR4 system in the regulation of ovarian carcinoma cell invasion

Ovarian carcinomas are often highly invasive, especially in the peritoneal cavity; however, the mechanism involved in invasion is not yet fully understood. In the present research, we studied the role of NF-κB in the invasiveness of ovarian carcinoma cells by using (−)-DHMEQ, a specific inhibitor of NF-κB. (−)-DHMEQ inhibited invasion in vitro and the expression of CXCL12 and CXCR4. We found that neutralizing antibody against CXCR4 or knockdown of CXCR4 suppressed the invasion. Proteomic analysis revealed that CXCR4-siRNA treatment lowered the secretion of several invasion-related proteins, such as MMP-9 and uPA. These data imply that (−)-DHMEQ suppressed ovarian cell invasion via inhibition of the NF-κB-regulated autocrine system of CXCL12-CXCR4.     

Dehydrozingerone exerts beneficial metabolic effects in high‐fat diet‐induced obese mice via AMPK activation in skeletal muscle

Dehydrozingerone (DHZ) exerts beneficial effects on human health; however, its mechanism of action remains unclear. Here, we found that DHZ suppressed high‐fat diet‐induced weight gain, lipid accumulation and hyperglycaemia in C57BL/6 mice and increased AMP‐activated protein kinase (AMPK) phosphorylation and stimulated glucose uptake in C2C12 skeletal muscle cells. DHZ activated p38 mitogen‐activated protein kinase (MAPK) signalling in an AMPK‐dependent manner. Inhibiting AMPK or p38 MAPK blocked DHZ‐induced glucose uptake. DHZ increased GLUT4 (major transporter for glucose uptake) expression in skeletal muscle. Glucose clearance and insulin‐induced glucose uptake increased in DHZ‐fed animals, suggesting that DHZ increases systemic insulin sensitivity in vivo. Thus, the beneficial health effects of DHZ could possibly be explained by its ability to activate the AMPK pathway in skeletal muscle.     

Purification and cDNA cloning of a novel protease inhibitor secreted into culture supernatant by MDCK cells.

The infectivity of influenza viruses to host cells depends on the activation of the viral glycoprotein hemagglutinin (HA) by proteases. Starting from the observation that influenza virus replication in MDCK (Madin Darby canine kidney) cells was impaired by inactivation of trypsin in the culture fluids, we demonstrated that the inhibitory activity was resolved into two Trypsin-inactivating factors (TF), TF A (15 kDa) and TF B (11 kDa). N-terminal protein sequences of the factors revealed that TF A was a known Submandibular Protease Inhibitor (SPI) secreted in dog saliva, while TF B was a novel protein (renamed CKPI; canine kidney protease inhibitor). Following peptide mapping and protein sequencing of CKPI we obtained a 390 bp cDNA encoding a 130-amino-acid protein from MDCK cell total RNA. Protein sequence comparison showed a 63.8% identity with human secretory leukocyte protease inhibitor (SLPI), the molecule containing two conserved whey acidic protein (WAP) motifs, and we suggest that CKPI is thought to be the canine analogue of human SLPI. These results suggest that the inhibitory factors are secreted from MDCK cells, which are involved in prevention of virus replication, and applicable to the protection of host cells from virus infection.