Habitat use and social structure of a brown lemur hybrid population in the Berenty Reserve, Madagascar

The population of brown lemurs has rapidly grown since their founders were introduced to the Berenty Reserve. The founders consist of two species (Eulemur fulvus rufus and E. collaris). To characterize the behavior of the population and to examine whether these characteristics affect population growth, I investigated the habitat use and social structure of the population of brown lemurs at Berenty (Berenty Eulemur). Behavior data were collected focusing on horizontal and vertical habitat use, activity rhythms, and intergroup relationships. These data were compared with the data of E. fulvus in other areas, with the previous studies done at Berenty, and with data on Berenty Lemur catta. Berenty Eulemur maintained a home range size comparable to E. f. rufus in the western deciduous dry forest, but was found at a lower level of the forest and had larger overlapping home ranges. Berenty Eulemur use food resources earlier in the morning than L. catta, intergroup conflict was avoided by vocal communication, and Berenty Eulemur made suitable use of their limited habitat. I suggest that a number of behavioral characteristics of Berenty Eulemur may contribute to their population growth.     

Downregulation of the NbNACa1 gene encoding a movement-protein-interacting protein reduces cell-to-cell movement of Brome mosaic virus in Nicotiana benthamiana

The 3a movement protein (MP) plays a central role in the movement of the RNA plant virus, Brome mosaic virus (BMV). To identify host factor genes involved in viral movement, a cDNA library of Nicotiana benthamiana, a systemic host for BMV, was screened with far-Western blotting using a recombinant BMV MP as probe. One positive clone encoded a protein with sequence similarity to the alpha chain of nascent-polypeptide-associated complex from various organisms, which is proposed to contribute to the fidelity of translocation of newly synthesized proteins. The orthologous gene from N. benthamiana was designated NbNACa1. The binding of NbNACa1 to BMV MP was confirmed in vivo with an agroinfiltration-immunoprecipitation assay. To investigate the involvement of NbNACa1 in BMV multiplication, NbNACa1-silenced (GSNAC) transgenic N. benthamiana plants were produced. Downregulation of NbNACa1 expression reduced virus accumulation in inoculated leaves but not in protoplasts. A microprojectile bombardment assay to monitor BMV-MP-assisted viral movement demonstrated reduced virus spread in GSNAC plants. The localization to the cell wall of BMV MP fused to green fluorescent protein was delayed in GSNAC plants. From these results, we propose that NbNACa1 is involved in BMV cell-to-cell movement through the regulation of BMV MP localization to the plasmodesmata.     

Alterations in mRNA Expression of Myelin Proteins in the Sciatic Nerves and Brains of Streptozotocin-induced Diabetic Rats

Diabetic neuropathy is the most common complication of diabetes. We examined the levels and the mRNA expression of myelin proteins in the sciatic nerves and the brains of streptozotocin-induced diabetic rats. The diabetic rats exhibited a decrease in body weight, elevation of the blood glucose level and a decrease in motor nerve conduction velocity at 2 weeks after streptozotocin injection. In the sciatic nerves of diabetic rats, the level of P0 protein and its mRNA expression were markedly reduced at 20 weeks after the injection. In the brains, the levels of proteolipid protein and myelin-associated glycoprotein and their mRNA expression were selectively decreased at 20 weeks after the injection. This affected expression of myelin proteins was found even when no histological abnormalities were detectable. Considering the functional significance of myelin proteins, this impairment of protein expression is possibly involved in the pathogenesis of diabetic neuropathy, including that in brain disorders.     

DEAD‐box polypeptide 43 facilitates piRNA amplification by actively liberating RNA from Ago3‐piRISC

The piRNA amplification pathway in Bombyx is operated by Ago3 and Siwi in their piRISC form. The DEAD‐box protein, Vasa, facilitates Ago3‐piRISC production by liberating cleaved RNAs from Siwi‐piRISC in an ATP hydrolysis‐dependent manner. However, the Vasa‐like factor facilitating Siwi‐piRISC production along this pathway remains unknown. Here, we identify DEAD‐box polypeptide 43 (DDX43) as the Vasa‐like protein functioning in Siwi‐piRISC production. DDX43 belongs to the helicase superfamily II along with Vasa, and it contains a similar helicase core. DDX43 also contains a K‐homology (KH) domain, a prevalent RNA‐binding domain, within its N‐terminal region. Biochemical analyses show that the helicase core is responsible for Ago3‐piRISC interaction and ATP hydrolysis, while the KH domain enhances the ATPase activity of the helicase core. This enhancement is independent of the RNA‐binding activity of the KH domain. For maximal DDX43 RNA‐binding activity, both the KH domain and helicase core are required. This study not only provides new insight into the piRNA amplification mechanism but also reveals unique collaborations between the two domains supporting DDX43 function within the pathway.     

Regulation of the KNOX-GA Gene Module Induces Heterophyllic Alteration in North American Lake Cress

Plants show leaf form alteration in response to changes in the surrounding environment, and this phenomenon is called heterophylly. Although heterophylly is seen across plant species, the regulatory mechanisms involved are largely unknown. Here, we investigated the mechanism underlying heterophylly in Rorippa aquatica (Brassicaceae), also known as North American lake cress. R. aquatica develops pinnately dissected leaves in submerged conditions, whereas it forms simple leaves with serrated margins in terrestrial conditions. We found that the expression levels of KNOTTED1-LIKE HOMEOBOX (KNOX1) orthologs changed in response to changes in the surrounding environment (e.g., change of ambient temperature; below or above water) and that the accumulation of gibberellin (GA), which is thought to be regulated by KNOX1 genes, also changed in the leaf primordia. We further demonstrated that exogenous GA affects the complexity of leaf form in this species. Moreover, RNA-seq revealed a relationship between light intensity and leaf form. These results suggest that regulation of GA level via KNOX1 genes is involved in regulating heterophylly in R. aquatica. The mechanism responsible for morphological diversification of leaf form among species may also govern the variation of leaf form within a species in response to environmental changes.     

Proteomic Characterization of Helicobacter pylori CagA Antigen Recognized by Child Serum Antibodies and Its Epitope Mapping by Peptide Array

Serum antibodies against pathogenic bacteria play immunologically protective roles, and can be utilized as diagnostic markers of infection. This study focused on Japanese child serum antibodies against Helicobacter pylori, a chronically-infected gastric bacterium which causes gastric cancer in adults. Serological diagnosis for H. pylori infection is well established for adults, but it needs to be improved for children. Serum samples from 24 children, 22 H. pylori (Hp)-positive and 2 Hp-negative children, were used to catalogue antigenic proteins of a Japanese strain CPY2052 by two-dimensional electrophoresis followed by immunoblot and LC-MS/MS analysis. In total, 24 proteins were identified as candidate antigen proteins. Among these, the major virulence factor, cytotoxin-associated gene A protein (CagA) was the most reactive antigen recognized by all the Hp-positive sera even from children under the age of 3 years. The major antigenic part of CagA was identified in the middle region, and two peptides containing CagA epitopes were identified using a newly developed peptide/protein-combined array chip method, modified from our previous protein chip method. Each of the epitopes was found to contain amino acid residue(s) unique to East Asian CagA. Epitope analysis of CagA indicated importance of the regional CagA antigens for serodiagnosis of H. pylori infection in children.     

Organic anion transporting polypeptide-C mediates arsenic uptake in HEK-293 cells

Summary Arsenic is an established human carcinogen. The role of aquaglyroporins (AQPs) in arsenic disposition was recently identified. In order to examine whether organic anion transporting polypeptide-C (OATP-C) also plays a role in arsenic transport, OATP-C cDNA was transfected into cells of a human embryonic kidney cell line (HEK-293). Transfection increased uptake of the model OATP-C substrate, estradiol-17β-D-glucuronide, by 10-fold. In addition, we measured uptake and cytotoxicity of arsenate, arsenite, monomethylarsonate(MMA^V), and dimethylarsinate (DMA^V). Transfection of OATP-C increased uptake and cytotoxicity of arsenate and arsenite, but not of MMA^V or DMA^V. Rifampin and taurocholic acid (a substrate of OATP-C) reversed the increased toxicity of arsenate and arsenite seen in OATP-C-transfected cells. The increase in uptake of inorganic arsenic was not as great as that of estradiol-17β-D-glucuronide. Our results suggest that OATP-C can transport inorganic arsenic in a (GSH)-dependent manner. However, this may not be the major pathway for arsenic transport.