Vinyldiaminotriazine-acridine conjugate as G-quadruplex alkylating agent

Higher-order structures of nucleic acids have become widely noted for their biological consequences and the discovery of an alkylating small molecule for these structures has been of interest due to its therapeutic potential. We previously developed the vinyldiaminotriazine (VDAT)-acridine conjugate as a T-T mismatch alkylating agent. In this report, we focused on the finding of the alkylation to the G-quadruplex (G4) DNA with VDAT-acridine conjugates. The VDAT-acridine conjugates exhibited a considerable alkylation ability to G4 under mild conditions. Moreover, the investigation of properties with the alkylated G4 revealed that alkylation by this conjugate significantly increased the stability of the G4 structure. This study provides a starting point in the further development of selective G4 alkylating small molecules.     

Impact of leopards on a working ranch in Laikipia,Kenya

This study of leopard predation on livestock was carried out on the Lolldaiga Hills ranch (200 km²) in the Laikipia District in Kenya between September 1989 and August 1995. The aims of the study were to find out whether leopards depend on livestock as a food resource on the ranch, and to quantify the economic impact of leopards on the livestock production systems. The density of leopards was estimated in three ways, and the biomass density of potential prey for leopards, both wild and domestic. Diet analysis of leopards revealed that leopards are not relying on livestock as an important food resource. To quantify the effects of leopards, an approach used in the economic assessment of agricultural development schemes was adopted ( Gittinger, 1982 ) and models were derived by following those criteria. It was found that leopards, not being persecuted, live at a relatively high density on the ranch but have less of an adverse impact on livestock than might be expected. Wildlife as a food resource for leopards and a buffer against the killing of livestock could be of benefit on a working ranch to reduce the economic impact of predators on the production system.     

Histamine monoclonal antibody for brain immunocytochemistry.

Among five monoclonal antibodies (AHA-1 to 5 mAbs) prepared against glutaraldehyde (GA)-conjugated histamine (HA) in our previous study, only mAb AHA-2 was found to detect HA specifically in rat brain neurons by an immunocytochemistry method (ICC) using GA as a tissue fixative. All the other mAbs, except for AHA-5, reacted with HA in the enterochromaffin-like cells (ECL cells) of rat stomach [Fujiwara et al. (1997) Histochem. Cell Biol. 107, 39-45]. Enzyme-linked immunosorbent assay (ELISA) binding and inhibition tests demonstrated that AHA-2 is specific for HA, with almost no detectable cross-reaction with any other established or putative amino acid neurotransmitters, LH-RH, TRH, or peptides with N-terminal histidines. ELISA assays also suggested that the AHA-2 mAb recognizes a HA epitope structure different from the one recognized by the AHA-1 mAb. The immunostaining patterns with AHA-2 mAb, as seen in the five subgroups of the tuberomammillary nuclei in the rat posterior hypothalamus, were very similar to those described by Inagaki et al. [(1988) Brain Res. 439, 402-405; (1990) Exp. Brain Res. 80, 374-380] and Panula et al. [(1984) Proc. Natl. Acad. Sci. USA 81, 2572-2576; (1988) J. Histochem. Cytochem. 36, 259-269] using polyclonal anti-HA serum. However, it was also noted that moderate numbers of immunoreactive nerve fibers projected into the median eminence. The present HA ICC method using AHA-2 mAb allows highly sensitive HA detection in brain, and thus might permit detailed studies of HA localization hitherto impossible using previously available anti-HA polyclonal antibodies produced against carbodiimide-conjugated HA.     

Identification of small RNAs in late developmental stage of rice anthers

Small RNAs including microRNA (miRNA) and small interfering RNA (siRNA) are known as repressors of gene expression. There are many plant proteins involved in small RNA-mediated gene silencing, such as Dicer ribonucleases and RNA-dependent RNA polymerases. However, most of these proteins have been reported to be absent in the late developmental stage of the plant male gamete, pollen. In order to clarify the existence of the small RNAs during maturation of pollen, we cloned and sequenced small RNAs from rice anthers including tricellular pollen. From fifty six candidates of small RNAs, we identified two known miRNAs (miR166 and miR167), eight potential miRNAs, and ten putative heterochromatic siRNAs (hc-siRNAs). RNA gel blot analyses clearly showed that miR166 and miR167 were accumulated in the uninuclear pollen stage of anther development and remained until the tricellular pollen stage. Our cloning and RNA gel blot analyses of small RNAs led us to propose a possible function of small RNA-mediated gene regulation for the development of male gametes in rice.     

Phosphorylation of Phospholipase C‐δ1 Regulates its Enzymatic Activity

Phosphorylation of phospholipase C‐δ₁ (PLC‐δ₁) in vitro and in vivo was investigated. Of the serine/threonine kinases tested, protein kinase C (PKC) phosphorylated the serine residue(s) of bacterially expressed PLC‐δ₁ most potently. It was also demonstrated that PLC‐δ₁ directly bound PKC‐α via its pleckstrin homology (PH) domain. Using deletion mutants of PLC‐δ₁ and synthetic peptides, Ser35 in the PH domain was defined as the PKC mediated in vitro phosphorylation site of PLC‐δ₁. In vitro phosphorylation of PLC‐δ₁ by PKC stimulated [³H]PtdIns(4,5)P₂ hydrolyzing activity and [³H]Ins(1,4,5)P₃‐binding of the PLC‐δ₁. On the other hand, endogenous PLC‐δ₁ was constitutively phosphorylated and phosphoamino acid analysis revealed that major phosphorylation sites were threonine residues in quiescent cells. The phosphorylation level and the species of phosphoamino acid were not changed by various stimuli such as PMA, EGF, NGF, and forskolin. Using matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry, we determined that Thr209 of PLC‐δ₁ is one of the constitutively phosphorylated sites in quiescent cells. The PLC activity was potentiated when constitutively phosphorylated PLC‐δ₁ was dephosphorylated by endogenous phosphatase(s) in vitro. Additionally, coexpression with PKC‐α reduced serine phosphorylation of PLC‐δ₁ detected by an anti‐phosphoserine antibody and PLC‐δ₁‐dependent basal production of inositol phosphates in NIH‐3T3 cells, suggesting PKC‐α activates phosphatase or inactivates another kinase involved in PLC‐δ₁ serine phosphorylation to modulate the PLC‐δ₁ activity in vivo. Taken together, these results suggest that PLC‐δ₁ has multiple phosphorylation sites and phosphorylation status of PLC‐δ₁ regulates its activity positively or negatively depends on the phosphorylation sites. J. Cell. Biochem. 108: 638–650, 2009. © 2009 Wiley‐Liss, Inc.     

Protective Role of Fas-FasL Signaling in Lethal Infection with Herpes Simplex Virus Type 2 in Mice

Herpes simplex virus type 2 (HSV-2) induces acute local infection followed by latent infection in the nervous system and often leads to the development of lethal encephalitis in immunocompromised hosts. The mechanisms of immune protection against lethal HSV-2 infection, however, have not been clarified. In this study, we examined the roles of Fas-Fas ligand (FasL) signaling in lethal infection with HSV-2 by using mice with mutated Fas (lpr) or FasL (gld) in C57BL/6 background. Both lpr and gld mice exhibited higher mortality than wild-type (WT) C57BL/6 mice after infection with virulent HSV-2 strain 186 and showed significantly increased viral titers in the spinal cord compared with WT mice 9 days after infection, just before the mice started to die. There were no differences in the numbers of CD4⁺ and CD8⁺ T cells infiltrated in the spinal cord or in the levels of HSV-2-specific gamma interferon produced by those cells in a comparison of lpr and WT mice 9 days after infection. Adoptive transfer studies demonstrated that CD4⁺ T cells from WT mice protected gld mice from lethal infection by HSV-2. Furthermore, CD4⁺ T cells infiltrated in the spinal cord of HSV-2-infected WT mice expressed functional FasL that induced apoptosis of Fas-expressing target cells in vitro. These results suggest that FasL-mediated cytotoxic activity of CD4⁺ T cells plays an important role in host defense against lethal infection with HSV-2.Fas-Fas ligand (FasL) signaling-induced apoptotic cell death has pleiotropic roles in T-cell-mediated host defense mechanisms. First, Fas and FasL are expressed on activated T cells and thereby limit their number by inducing suicide or fratricide. It is generally accepted that Fas-mediated activation-induced cell death plays a predominant role during chronic infection, whereas starvation-induced cell death mediated by the proapoptotic BH3-only subgroup of the Bcl-2 protein family is the main mechanism for T-cell death during termination of immune responses in acute infection (30). Fas-FasL signaling might also play a role in T-cell development, as suggested by an accumulation of T-cell receptor αβ-positive (TCR αβ⁺) CD4⁻ CD8⁻ T cells expressing B220 in lymphoid organs of mice with mutated Fas (lpr) or FasL (gld) although the origin and functions of such double-negative T cells are still a matter of debate (21). Lastly, Fas-FasL interaction can be directly involved in host defense by inducing apoptosis of infected cells to facilitate pathogen clearance (23). Therefore, the roles of Fas-FasL signaling in immune responses for host defense might vary depending on the pathogen.Herpes simplex virus type 2 (HSV-2) is an alphaherpesvirus that causes genital herpes, the most common viral sexually transmitted disease (29). After initial infection in the vaginal epithelium, HSV-2 invades local nerve termini, travels via retrograde axonal transport to neuronal cell bodies in sensory ganglia, and establishes latent infection (13). However, especially in neonates and immunocompromised hosts, HSV-2 can cause lethal central nervous system (CNS) infection, which indicates the importance of immune systems in limiting the pathogenicity of HSV-2. Immune responses against HSV-2 have been studied in various murine models using different strains of virus and routes of inoculation, with or without vaccination with an attenuated strain of HSV-2. In such vaccination models, CD4⁺ T cells producing gamma interferon (IFN-γ) predominantly conferred protection against challenge with a virulent strain of HSV-2 (11, 19), whereas various subsets of lymphocytes, including NK cells, NK T cells, and TCR γδ T cells as well as CD4⁺ T cells were reported to be involved in host defense against primary infection with virulent HSV-2 (3, 15, 24), in which IFN-γ also played an important role (9). Fas-FasL signaling was shown to be dispensable for the clearance of an attenuated strain of HSV-2, which lacks thymidine kinase and causes only transient mild vaginal pathologies but not neurologic diseases (6, 16). Similarly Fas-mediated apoptosis was not involved in the vaccination effect of the attenuated HSV-2 (11). However, the roles of Fas-FasL signaling in host defense against a virulent strain of HSV-2 have not been clarified.In this study, we examined the roles of Fas-FasL signaling in a murine model of HSV-2 infection by using a highly virulent HSV-2 strain 186 with lpr and gld mice. We found that FasL-Fas signaling plays an important role in host defense against lethal HSV-2 infection.     

Functional phenotypes and gene expression profiles of peripheral blood mononuclear cells in chronic hepatitis C patients who developed non-Hodgkin’s B-cell lymphoma

Epidemiological data have indicated a close relationship between chronic HCV infection and non-Hodgkin’s B-cell lymphoma (B-NHL). In this study, functional phenotypes and gene expression profiles of PBMCs were analyzed in chronic hepatitis C (CHC) patients who developed B-NHL. The frequencies of effector CD8⁺ T cells and cytotoxic natural killer cells increased in CHC patients with B-NHL compared to those in CHC patients without B-NHL. These phenotypic changes may reflect the host’s immune response to neoplasia. The mRNA expression levels of several oncogenes increased in CHC patients without B-NHL, but were much higher in CHC patients with B-NHL, while mRNA levels of type I IFNs were decreased in CHC patients without B-NHL and were nearly negligible in CHC patients with B-NHL. Interestingly, the mRNA expression levels of activation-induced cytidine deaminase and caspase recruitment domain-containing proteins markedly increased in CHC patients without B-NHL but decreased in CHC patients with B-NHL. These results are discussed in view of the possible involvement of HCV infection in B-cell lymphomagenesis.