Phylogeography of Wild Musk Shrew (Suncus Murinus) Populations in Asia Based on Blood Protein/Enzyme Variation

The musk shrew (Suncus murinus) is an insectivore species that inhabits tropical and subtropical Asia widely. To clarify the genetic relationship among wild musk shrew populations, we examined the electrophoretic variants of biparentally inherited genetic markers at 10 loci coding for eight blood proteins/enzymes in a total of 639 animals and compared the results obtained from the mitochondrial DNA data. The principal-component analysis performed using the allele frequency data revealed that the 17 populations could be divided into two major groups, a South Asian group and a Southeast Asian group that includes several island populations bound by Myanmar. The degrees of genetic divergence among populations were higher within the Southeast Asian group than within the South Asian group. This finding was incongruent with the mtDNA diversity. Analysis conducted at the individual level showed that a shrew from the central region in Myanmar that carries a South Asian type of mtDNA showed the electrophoretic variants specific to the Southeast Asian group, suggesting that this region is a contact zone between the two major groups.     

Interaction of a magainin-PGLa hybrid peptide with membranes: insight into the mechanism of synergism

The antimicrobial peptides magainin 2 and PGLa isolated from the skin of the African clawed frog Xenopus laevis show marked functional synergism. We have proposed that the two peptides form a heterodimer composed of parallel helices with strong membrane permeabilizing activity [Hara, T., Mitani, Y., Tanaka, K., Uematsu, N., Takakura, A., Tachi, T., Kodama, H., Kondo, M., Mori, H., Otaka, A., Fujii, N., and Matsuzaki, K. (2001) Biochemistry 40, 12395-12399]. In this study, to elucidate the molecular mechanism of the synergy, we synthesized a chemically fixed heterodimer and investigated in detail the interaction of the hybrid peptide with bacteria, erythrocytes, and lipid bilayers. The hybrid peptide showed antimicrobial activity and membrane permeabilizing activity against negatively charged membranes, similar to or even stronger than those of a physical equimolar mixture of magainin and PGLa, indicating that the synergy is due to the formation of a parallel heterodimer. The heterodimer assumed a more oblique orientation than the component peptides. In contrast, the cross-linking of the two peptides significantly strengthened the action against erythrocytes and zwitterionic lipid bilayers by enhancing the affinity for membranes without changing the basic mode of action. Thus, the separate production of mutually recognizing peptides without cross-linking appears to be a good way to increase selective toxicity.     

Histone acetyltransferase MOZ acts as a co-activator of Nrf2-MafK and induces tumour marker gene expression during hepatocarcinogenesis

HATs (histone acetyltransferases) contribute to the regulation of gene expression, and loss or dysregulation of these activities may link to tumorigenesis. Here, we demonstrate that expression levels of HATs, p300 and CBP [CREB (cAMP-response-element-binding protein)-binding protein] were decreased during chemical hepatocarcinogenesis, whereas expression of MOZ (monocytic leukaemia zinc-finger protein; MYST3)--a member of the MYST [MOZ, Ybf2/Sas3, Sas2 and TIP60 (Tat-interacting protein, 60 kDa)] acetyltransferase family--was induced. Although the MOZ gene frequently is rearranged in leukaemia, we were unable to detect MOZ rearrangement in livers with hyperplastic nodules. We examined the effect of MOZ on hepatocarcinogenic-specific gene expression. GSTP (glutathione S-transferase placental form) is a Phase II detoxification enzyme and a well-known tumour marker that is specifically elevated during hepatocarcinogenesis. GSTP gene activation is regulated mainly by the GPE1 (GSTP enhancer 1) enhancer element, which is recognized by the Nrf2 (nuclear factor-erythroid 2 p45 subunit-related factor 2)-MafK heterodimer. We found that MOZ enhances GSTP promoter activity through GPE1 and acts as a co-activator of the Nrf2-MafK heterodimer. Further, exogenous MOZ induced GSTP expression in rat hepatoma H4IIE cells. These results suggest that during early hepatocarcinogenesis, aberrantly expressed MOZ may induce GSTP expression through the Nrf2-mediated pathway.     

Protective Efficacy of Passive Immunization with Monoclonal Antibodies in Animal Models of H5N1 Highly Pathogenic Avian Influenza Virus Infection

Highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype often cause severe pneumonia and multiple organ failure in humans, with reported case fatality rates of more than 60%. To develop a clinical antibody therapy, we generated a human-mouse chimeric monoclonal antibody (MAb) ch61 that showed strong neutralizing activity against H5N1 HPAI viruses isolated from humans and evaluated its protective potential in mouse and nonhuman primate models of H5N1 HPAI virus infections. Passive immunization with MAb ch61 one day before or after challenge with a lethal dose of the virus completely protected mice, and partial protection was achieved when mice were treated 3 days after the challenge. In a cynomolgus macaque model, reduced viral loads and partial protection against lethal infection were observed in macaques treated with MAb ch61 intravenously one and three days after challenge. Protective effects were also noted in macaques under immunosuppression. Though mutant viruses escaping from neutralization by MAb ch61 were recovered from macaques treated with this MAb alone, combined treatment with MAb ch61 and peramivir reduced the emergence of escape mutants. Our results indicate that antibody therapy might be beneficial in reducing viral loads and delaying disease progression during H5N1 HPAI virus infection in clinical cases and combined treatment with other antiviral compounds should improve the protective effects of antibody therapy against H5N1 HPAI virus infection.     

Contact Doping with Sub‐Monolayers of Strong Polyelectrolytes for Organic Photovoltaics

Barriers to charge transfer at electrode‐semiconductor contacts are ubiquitous and limit the applicability of organic semiconductors in electronic devices. Molecular or ionic doping near contacts can alleviate charge injection or extraction problems by enabling charge tunneling through contact barriers, but the soft nature of organic materials allows for small molecule dopants to diffuse and migrate, degrading the performance of the device and limiting effective interfacial doping. Here, it is demonstrated that contact doping in organic electronics is possible through ionic polymer dopants, which resist diffusion or migration due to their large size. Sub‐monolayer deposition of non‐conjugated strong polyelectrolytes, e.g., sulfonated poly(sulfone)s, at the anode‐semiconductor interface of organic photovoltaics enables efficient hole extraction at the anode. The performance of contact‐doped organic photo­voltaics nearly matches the performance of devices composed of traditional hole transport layers such as poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The degree of sulfonation of the dopant polymer and the thickness of the ionic dopant layer is shown to be critical for optimizing doping and the efficiency of the device.     

Morphological and molecular characterization of Tulasnella spp. fungi isolated from the roots of Epidendrum secundum,a widespread Brazilian orchid

Tulasnella spp. are the main fungal symbionts of Brazilian Epidendrum orchids. The taxonomy of these fungi is largely based on ITS rDNA similarity, but culture dependent techniques are still essential to establish the true biological entity of the mycobiont. The aim of this study was to characterize morphologically and molecularly 16 Tulasnella spp. fungi isolated from three different populations of E. secundum and to test the coincidences between morphological and molecular characterization. Two uninucleate rhizoctonia fungi, obtained from Oncidium barbaceniae, and two phytopathogenic isolates were included as outgroups. Qualitative and quantitative morphological characteristics were analyzed using multivariate statistics and were able to distinguish Ceratobasidium, Tulasnella and Thanatephorus genera and separate the isolates of Tulasnella spp. into two groups. Analysis of RAPD (Random Amplified Polymorphic DNA) and ITS rDNA sequences validated the morphological data. Symbionts of O. barbaceniae presented identity to ITS sequences of Ceratobasidium genus, while E. secundum isolates presented identity to two species of Tulasnella. We observed homogeneity among Tulasnella spp. obtained from a single population and from neighboring populations, but there was higher variability among isolates obtained from populations of regions that were farther apart. Morphological data associated with multivariate statistics proved to be a useful tool in the multi-level taxonomy of these orchid-associated fungi and in estimating the diversity of orchid mycorrhizal fungi.