A TSH/dibutyryl cAMP activated Cl-/I- channel in FRTL-5 cells.

An iodide (I) and chloride (Cl) channel has been identified in the continuously cultured FRTL-5 thyroid cell line using a cell attached patch clamp technique. The channel is activated by TSH and dibutyryladenosine cyclic monophosphate (Bt2-cAMP) but not by phorbol 12-myristate 13-acetate (TPA). Gluconate can not replace chloride or iodide and the channel is impermeable to Na+,K+ and tetraethylammonium ions. The current-voltage relationship demonstrates that the single channel current is a linear function of the clamp voltage. Single channel currents reversed at a pipette potential close to 0 mV. The mean single channel conductance was 60 pS for Cl- and 50 pS for I-. From the I-V relationship there was a strong outward rectification with Cl-, and a complete block with I-, in the single channel current above +40 mV. The feature of the channel is manifested in the single channel records by four distinct, equally spaced conductance levels. We suggest the channel is important for the transport of I and Cl ions across the apical membrane into the colloid space and is important for hormone synthesis and follicle formation.     

The release of iron from horse spleen ferritin by reduced flavins

Ferritin-Fe(III) was rapidly and quantitatively reduced and liberated as Fe(II) by FMNH₂, FADH₂ and reduced riboflavin. Dithionite also released Fe(II) from ferritin but at less than 1% of the rate with FMNH₂. Cysteine, glutathione and ascorbate gave a similar slower rate and yielded less than 20% of the total iron from ferritin within a few hours. The reduction of ferritin-Fe(III) by the three riboflavin compounds gave complex second-order kinetics with overlapping fast and slow reactions. The fast reaction appeared to be non-specific and may be due to a reduction of Fe(III) of a lower degree of polymerization, equilibrated with ferritin iron. The amount of this Fe³⁺ ion initially reduced was small, less than 0.3% of the total iron. Addition of FMN to the ferritin–dithionite system enhanced the reduction; this is due to the reduction of FMN by dithionite to form FMNH₂ which then reduces ferritin-Fe(III). A comparison of the thermodynamic parameters of FMNH₂–ferritin and dithionite–ferritin complex formation showed that FMNH₂ required a lower activation energy and a negative entropy change, whereas dithionite required 50% more activation energy and showed a positive entropy change in ferritin reduction. The effectiveness of FMNH₂ in ferritin–Fe(III) reduction may be due to a specific binding of the riboflavin moiety to the protein portion of the ferritin molecule.     

Biotic Interaction between a Rust Fungus, Uromyces erythronii Pass., and its Host Plant, Erythronium japonicum Decne. (Liliaceae)

Abstract A characteristic pattern of infection by a rust fungus, Uromyces erythronii Pass, on its host plant, Erythronium japonicum Decne. (Liliaceae) was observed in a field population for three years from 1981 to 1983. Due to the primary infection by teliospores of U. erythronii in the soil layer, spermogonia and aecia were formed on the abaxial leaf surface along the midrib of E. japonicum. In the case of flowering individuals, however, spermogonia and aecia were only formed on the larger of the two leaves. An increase of individuals bearing telia was restricted by rapid decaying of leaf tissue of the host plant. A high percentage of rusted individuals was observed in the Erythronium populations, and U. erythronii obviously has some effects on the growth of its host plant. However, its infection does not appear to be a direct cause of the death of Erythronium individuals in the field populations.     

Cyclic phosphatidic acid decreases proliferation and survival of colon cancer cells by inhibiting peroxisome proliferator-activated receptor γ

Cyclic phosphatidic acid (cPA), a structural analog of lysophosphatidic acid (LPA), is one of the simplest phospholipids found in every cell type. cPA is a specific, high-affinity antagonist of peroxisome proliferator-activated receptor gamma (PPARγ); however, the molecular mechanism by which cPA inhibits cellular proliferation remains to be clarified. In this study, we found that inhibition of PPARγ prevents proliferation of human colon cancer HT-29 cells. cPA suppressed cell growth, and this effect was reversed by the addition of a PPARγ agonist. These results indicate that the physiological effects of cPA are partly due to PPARγ inhibition. Our results identify PPARγ as a molecular mediator of cPA activity in HT-29 cells, and suggest that cPA and the PPARγ pathway might be therapeutic targets in the treatment of colon cancer.     

Tumor suppressive microRNA-133a regulates novel targets: moesin contributes to cancer cell proliferation and invasion in head and neck squamous cell carcinoma

Recently, many studies suggest that microRNAs (miRNAs) contribute to the development, invasion and metastasis of various types of human cancers. Our recent study revealed that expression of microRNA-133a (miR-133a) was significantly reduced in head and neck squamous cell carcinoma (HNSCC) and that restoration of miR-133a inhibited cell proliferation, migration and invasion in HNSCC cell lines, suggesting that miR-133a function as a tumor suppressor. Genome-wide gene expression analysis of miR-133a transfectants and TargetScan database showed that moesin (MSN) was a promising candidate of miR-133a target gene. MSN is a member of the ERM (ezrin, radixin and moesin) protein family and ERM function as cross-linkers between plasma membrane and actin-based cytoskeleton. The functions of MSN in cancers are controversial in previous reports. In this study, we focused on MSN and investigated whether MSN was regulated by tumor suppressive miR-133a and contributed to HNSCC oncogenesis. Restoration of miR-133a in HNSCC cell lines (FaDu, HSC3, IMC-3 and SAS) suppressed the MSN expression both in mRNA and protein level. Silencing study of MSN in HNSCC cell lines demonstrated significant inhibitions of cell proliferation, migration and invasion activities in si-MSN transfectants. In clinical specimen with HNSCC, the expression level of MSN was significantly up-regulated in cancer tissues compared to adjacent non-cancerous tissues. These data suggest that MSN may function as oncogene and is regulated by tumor suppressive miR-133a. Our analysis data of novel tumor-suppressive miR-133a-mediated cancer pathways could provide new insights into the potential mechanisms of HNSCC oncogenesis.     

Birth of Healthy Offspring following ICSI in In Vitro-Matured Common Marmoset (Callithrix jacchus) Oocytes

Intracytoplasmic sperm injection (ICSI), an important method used to treat male subfertility, is applied in the transgenic technology of sperm-mediated gene transfer. However, no study has described successful generation of offspring using ICSI in the common marmoset, a small non-human primate used as a model for biomedical translational research. In this study, we investigated blastocyst development and the subsequent live offspring stages of marmoset oocytes matured in vitro and fertilized by ICSI. To investigate the optimal timing of performing ICSI, corrected immature oocytes were matured in vitro and ICSI was performed at various time points (1–2 h, 2–4 h, 4–6 h, 6–8 h, and 8–10 h after extrusion of the first polar body (PB)). Matured oocytes were then divided randomly into two groups: one was used for in vitro fertilization (IVF) and the other for ICSI. To investigate in vivo development of embryos followed by ICSI, 6-cell- to 8-cell-stage embryos and blastocysts were nonsurgically transferred into recipient marmosets. Although no significant differences were observed in the fertilization rate of blastocysts among ICSI timing after the first PB extrusion, the blastocyst rate at 1–2 h was lowest among groups at 2–4 h, 4–6 h, 6–8 h, and 8–10 h. Comparing ICSI to IVF, the fertilization rates obtained in ICSI were higher than in IVF (p>0.05). No significant difference was noted in the cleaved blastocyst rate between ICSI and IVF. Following the transfer of 37 ICSI blastocysts, 4 of 20 recipients became pregnant, while with the transfer of 21 6-cell- to 8-cell-stage ICSI embryos, 3 of 8 recipients became pregnant. Four healthy offspring were produced and grew normally. These are the first marmoset offspring produced by ICSI, making it an effective fertilization method for marmosets.