Phylogenetic diversity of non-nodulating Rhizobium associated with pine ectomycorrhizae

Most Rhizobium species described are symbionts that form nodules on legume roots; however, non-nodulating strains of Rhizobium are also widespread in nature. Unfortunately, knowledge of non-nodulating Rhizobium is quite limited compared with nodulating Rhizobium . Here, we studied the phylogenetic diversity of Rhizobium species that inhabit Japanese red pine roots ( Pinus densiflora ). Because fine roots of pine trees are usually colonized by ectomycorrhizal fungi in nature, we mainly used ectomycorrhizal root tips for bacterial isolation. Out of 1195 bacteria isolated from 75 independent root samples from the field and greenhouse experiments, 102 isolates were confirmed to be Rhizobium following partial 16S rRNA gene analysis. Rhizobium species were occasionally dominant in culturable bacterial communities, whereas no Rhizobium species were isolated from the soil itself. Molecular phylogenetic analyses using 16S rRNA, atpD , and recA gene sequences revealed that isolated Rhizobium strains were phylogenetically diverse and that several were distantly related to known Rhizobium species. Considering that a single species of pine is associated with unique and phylogenetically diverse Rhizobium populations, we should pay more attention to non-nodulating strains to better understand the diversity, ecology, and evolution of the genus Rhizobium and plant– Rhizobium associations.     

Endometrial Cancer as a Familial Tumor: Pathology and Molecular Carcinogenesis (Review)

Some cases of endometrial cancer are associated with a familial tumor and are referred to as hereditary nonpolyposis colorectal cancer (HNPCC or Lynch syndrome). Such tumors are thought to be induced by germline mutation of the DNA mismatch repair (MMR) gene, but many aspects of the pathology of familial endometrial cancer are unclear and no effective screening method has been established. However, the pathology of endometrial cancer with familial tumor has been progressively clarified in recent studies. At present, about 0.5% of all cases of endometrial cancers meet the clinical diagnostic criteria for HNPCC. A recent analysis of the three MMR genes (hMLH1, hMSH2 and hMSH6) revealed germline mutations in 18 of 120 cases (15.0%) of endometrial cancer with familial accumulation of cancer or double cancer, with a frameshift mutation of the hMSH6 gene being the most common. Many cases with mutation did not meet the current clinical diagnostic criteria for HNPCC, indicating that familial endometrial cancer is often not diagnosed as HNPCC. The results suggest that the hMSH6 gene mutation may be important in carcinogenesis in endometrial cancer and germline mutations of the MMR gene may be more prevalent in cases associated with familial accumulation of cancer. An international large-scale muticenter study is required to obtain further information about the pathology of endometrial cancer as a familial tumor.Key Words: HNPCC, Endometrial cancer, DNA mismatch repair gene, hMLH1, hMSH6.     

Phosphorylation of the amino-terminal region of X11L regulates its interaction with APP

X11-like (X11L) is neuronal adaptor protein that interacts with the amyloid β-protein precursor (APP) and regulates its metabolism. The phosphotyrosine interaction/binding (PI/PTB) domain of X11L interacts with the cytoplasmic region of APP695. We found that X11L–APP interaction is enhanced in osmotically stressed cells and X11L modification is required for the enhancement. Amino acids 221–250 (X11L^221–250) are required for the enhanced association with APP in osmotically stressed cells; this motif is 118 amino acids closer to the amino-terminal end of the protein than the PI/PTB domain (amino acids 368–555). We identified two phosphorylatable seryl residues, Ser236 and Ser238, in X11L^221–250 and alanyl substitution of either seryl residue diminished the enhanced association with APP. In brain Ser238 was found to be phosphorylated and phosphorylation of X11L was required for the interaction of X11L and APP. Both seryl residues in X11L^221–250 are conserved in neuronal X11, but not in X11L2, a non-neuronal X11 family member that did not exhibit enhanced APP association in osmotically stressed cells. These findings indicate that the region of X11L that regulates association with APP is located outside of, and amino-terminal to, the PI/PTB domain. Modification of this regulatory region may alter the conformation of the PI/PTB domain to modulate APP binding.     

Inhibition of hepatic damage and liver fibrosis by brain natriuretic peptide

Anti-fibrotic and organ protective effects of brain natriuretic peptide (BNP) have been reported. In this study, effects of BNP on liver fibrosis were examined in the carbon tetrachloride (CCl₄)-induced liver fibrosis model using BNP-transgenic (Tg) and wild-type (WT) mice. Twice-a-week intraperitoneal injections of CCl₄ for 8 weeks resulted in massive liver fibrosis, augmented transforming growth factor (TGF)-β₁ and type I procollagen α₁ chain (Col1a1) mRNA expression, and the hepatic stellate cell (HSC) activation in WT mice, all of which were significantly suppressed in Tg mice. These observations indicate that BNP inhibits liver fibrosis by attenuating the activation of HSCs.     

Human Induced Pluripotent Stem Cells on Autologous Feeders

Background

For therapeutic usage of induced Pluripotent Stem (iPS) cells, to accomplish xeno-free culture is critical. Previous reports have shown that human embryonic stem (ES) cells can be maintained in feeder-free condition. However, absence of feeder cells can be a hostile environment for pluripotent cells and often results in karyotype abnormalities. Instead of animal feeders, human fibroblasts can be used as feeder cells of human ES cells. However, one still has to be concerned about the existence of unidentified pathogens, such as viruses and prions in these non-autologous feeders.

Methodology/Principal Findings

This report demonstrates that human induced Pluripotent Stem (iPS) cells can be established and maintained on isogenic parental feeder cells. We tested four independent human skin fibroblasts for the potential to maintain self-renewal of iPS cells. All the fibroblasts tested, as well as their conditioned medium, were capable of maintaining the undifferentiated state and normal karyotypes of iPS cells. Furthermore, human iPS cells can be generated on isogenic parental fibroblasts as feeders. These iPS cells carried on proliferation over 19 passages with undifferentiated morphologies. They expressed undifferentiated pluripotent cell markers, and could differentiate into all three germ layers via embryoid body and teratoma formation.

Conclusions/Significance

These results suggest that autologous fibroblasts can be not only a source for iPS cells but also be feeder layers. Our results provide a possibility to solve the dilemma by using isogenic fibroblasts as feeder layers of iPS cells. This is an important step toward the establishment of clinical grade iPS cells.     

Extinction of anciently associated gut bacterial symbionts in a clade of stingless bees

Animal-microbe symbioses are often stable for millions of years. An example is the clade consisting of social corbiculate bees—honeybees, bumblebees, and stingless bees—in which a shared ancestor acquired specialized gut bacteria that subsequently diversified with hosts. This model may be incomplete, however, as few microbiomes have been characterized for stingless bees, which are diverse and ecologically dominant pollinators in the tropics. We surveyed gut microbiomes of Brazilian stingless bees, focusing on the genus Melipona, for which we sampled multiple species and biomes. Strikingly, Melipona lacks Snodgrassella and Gilliamella, bacterial symbionts ubiquitous in other social corbiculate bees. Instead, Melipona species harbor more environmental bacteria and bee-specific Starmerella yeasts. Loss of Snodgrassella and Gilliamella may stem from ecological shifts in Melipona or the acquisition of new symbionts as functional replacements. Our findings demonstrate the value of broadly sampling microbiome biodiversity and show that even ancient symbioses can be lost.Subject terms: Symbiosis, Microbiome, Microbial ecology, Metagenomics, Microbial ecology     

15-Deoxy-Δ-prostaglandin J2 enhanced the anti-tumor activity of camptothecin against renal cell carcinoma independently of topoisomerase-II and PPARγ pathways

Renal cell carcinoma (RCC) is chemoresistant cancer. Although several clinical trials were conducted to explore effective medications, the chemoresistance of RCC has not yet been conquered. An endogenous ligand for peroxisome proliferator-activated receptor-γ (PPARγ), 15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂), induces apoptosis in RCC. Here, we examined synergistic effects of several carcinostatics on the anti-tumor activity of 15d-PGJ₂ in Caki-2 cell line by MTT assay. A topoisomerase-I inhibitor, camptothecin (CPT), exhibited synergistically toxicity with 15d-PGJ₂, but neither 5-fluorouracil nor cisplatin did. The combination of 15d-PGJ₂ and a topoisomerase-II inhibitor, doxorubicine, did not cause synergistic cell growth inhibition. The synergistic effect of topoisomerase-I and II inhibitors was not also detected. A PPARγ antagonist, GW9662, did not prevent Caki-2 from undergoing 15d-PGJ₂-induced cytotoxicity. The treatment of CPT combined with 15d-PGJ₂ activated caspase-3 more than the separate treatment. These results suggest that 15d-PGJ₂ exhibited the anti-tumor activity synergistically with CPT independent of topoisomerase-II and PPARγ.     

15-Deoxy-Δ12,14-prostaglandin J2 enhanced the anti-tumor activity of camptothecin against renal cell carcinoma independently of topoisomerase-II and PPARγ pathways

Renal cell carcinoma (RCC) is chemoresistant cancer. Although several clinical trials were conducted to explore effective medications, the chemoresistance of RCC has not yet been conquered. An endogenous ligand for peroxisome proliferator-activated receptor-γ (PPARγ), 15-deoxy-Δ(12,14)-prostaglandin J(2) (15d-PGJ(2)), induces apoptosis in RCC. Here, we examined synergistic effects of several carcinostatics on the anti-tumor activity of 15d-PGJ(2) in Caki-2 cell line by MTT assay. A topoisomerase-I inhibitor, camptothecin (CPT), exhibited synergistically toxicity with 15d-PGJ(2), but neither 5-fluorouracil nor cisplatin did. The combination of 15d-PGJ(2) and a topoisomerase-II inhibitor, doxorubicine, did not cause synergistic cell growth inhibition. The synergistic effect of topoisomerase-I and II inhibitors was not also detected. A PPARγ antagonist, GW9662, did not prevent Caki-2 from undergoing 15d-PGJ(2)-induced cytotoxicity. The treatment of CPT combined with 15d-PGJ(2) activated caspase-3 more than the separate treatment. These results suggest that 15d-PGJ(2) exhibited the anti-tumor activity synergistically with CPT independent of topoisomerase-II and PPARγ.