Coinfection with koala retrovirus subtypes A and B and its impact on captive koalas in Japanese zoos.

Koala retrovirus (KoRV) is unique among endogenous retroviruses because its endogenization is still active. Two major KoRV subtypes, KoRV-A and B, have been described, and KoRV-B is associated with disease and poses a health threat to koalas. Here, we investigated the co-prevalence of KoRV-A and KoRV-B, detected by type-specific PCR and sequencing, and their impact on the health of koalas in three Japanese zoos. We also investigated KoRV proviral loads and found varying amounts of genomic DNA (gDNA) in peripheral blood mononuclear cells (PBMCs). We found that 100% of the koalas examined were infected with KoRV-A and 60% (12/20) were coinfected with KoRV-B. The KoRV-A sequence was highly conserved, whereas the KoRV-B sequence varied among individuals. Interestingly, we observed possible vertical transmission of KoRV-B in one offspring in which the KoRV-B sequence was similar to that of the father but not the mother. Moreover, we characterized the KoRV growth patterns in concanavalin-A-stimulated PBMCs isolated from KoRV-B-coinfected or KoRV-B-uninfected koalas. We quantified the KoRV provirus in gDNA and the KoRV RNA copy numbers in cells and culture supernatants by real-time PCR at days 4, 7, and 14 post-seeding. As the study population is housed in captivity, a longitudinal study of these koalas may provide an opportunity to study the transmission mode of KoRV-B. In addition, we characterized KoRV isolates by infecting tupaia cells. The results suggested that tupaia may be used as an infection model for KoRV. Thus, this study may enhance our understanding of KoRV-B coinfection and transmission in the captive koalas.

Characterization of very long chain fatty acid synthesis inhibition by ipfencarbazone.

Ipfencarbazone exhibits excellent herbicidal activity against Echinochloa spp. and is safe for rice. The effects of ipfencarbazone on very long chain fatty acid (VLCFA) elongation in rice and late watergrass and its inhibitory mechanism were investigated in this study. Although ipfencarbazone inhibited VLCFA elongation in the microsomes prepared from late watergrass and rice at low concentrations, the inhibitory effect was higher in late watergrass than in rice. These results suggested that the primary site of action of ipfencarbazone is VLCFA elongase (VLCFAE) and ipfencarbazone has a differential affinity between the VLCFAEs of the plants. The inhibitory activity of ipfencarbazone became higher in proportion to pre-incubation period with the VLCFAE. The degree of inhibition did not decrease by dilution of the VLCFAE-ipfencarbazone complex. These results suggested that ipfencarbazone binds to the VLCFAE irreversibly.

Effects of environmental factors on the herbicidal activity and phytotoxicity of ipfencarbazone.

Ipfencarbazone exhibits excellent herbicidal activity against Echinochloa spp. and is safe for transplanted rice at a dose of 250 g a.i./ha. However, the effect of various environmental factors on its activity has not been verified. The present study evaluated the factors affecting the herbicidal activity of ipfencarbazone against Echinochloa spp. and its phytotoxicity to transplanted rice. The herbicidal activity and phytotoxicity of ipfencarbazone were barely affected by temperature, soil texture, water leakage, or flooding water depth. When an overflow was conducted artificially 6 hr after application, the herbicidal activity was stable. Furthermore, ipfencarbazone completely inhibited the emergence of Echinochloa spp. for 56 days regardless of the soil texture, water leakage and overflow conditions. When the period between application and reflooding was within 24 hr of herbicide application, the phytotoxicity of ipfencarbazone on transplanted rice was slight. These results suggest that ipfencarbazone shows stable efficacy in practical use.

Identification and disruption of sperm-specific angiotensin converting enzyme-3 (ACE3) in mouse.

BACKGROUND: IZUMO1 is the only sperm protein which is proven to be essential for sperm-egg fusion. However, the IZUMO1 is a structurally simple protein with single Ig domain and seems not to include either a "fusogenic peptide" or a fusion machinery domain. This led us to assume the existence of an IZUMO1-interacting protein(s) which makes a functional fusion machine interacting with IZUMO1. METHODOLOGY/PRINCIPAL FINDINGS: We produced a transgenic mouse line which expresses His-tagged IZUMO1 in the Izumo1(-/-) genetic background. After solubilization of sperm membranes, we purified His-tagged IZUMO1 using anti-His affinity chromatography and found a protein that interacts with IZUMO1. After being separated on SDS-PAGE gel, the IZUMO1-interacting protein was subjected to LC-MS/MS analysis and from the partial fragments, we identified the protein as ACE3. We raised the antibody against ACE3 and found that ACE3 is localized on the acrosomal cap area as in the case of IZUMO1. However, ACE3 disappeared from sperm after acrosome reaction while IZUMO1 remained on sperm. In order to investigate the role of ACE3 in vivo, we generated Ace3-deficient mice by homologous recombination and examined the fertilizing ability of the males. Unexpectedly, the male mice showed no defect in fertilizing ability in in vivo or in an in vitro fertilization system. CONCLUSIONS/SIGNIFICANCE: We identified an IZUMO1-interacting protein in sperm, which we identified as testis specific ACE homologue ACE3. We produced an Ace3 disrupted mouse line, and found the localization of IZUMO1 spread in a little wider area on sperm, but the elimination of ACE3 did not result in a loss of sperm fertilizing ability, differing from the case of ACE disruption.

Molecular basis of the shish-kebab morphology in polymer crystallization.

In the rich and long-standing literature on the flow-induced formation of oriented precursors to polymer crystallization, it is often asserted that the longest, most extended chains are the dominant molecular species in the "shish" of the "shish-kebab" formation. We performed a critical examination of this widely held view, using deuterium labeling to distinguish different chain lengths within an overall distribution. Small-angle neutron-scattering patterns of the differently labeled materials showed that long chains are not overrepresented in the shish relative to their concentration in the material as a whole. We observed that the longest chains play a catalytic role, recruiting other chains adjacent to them into formation of the shish.