Use of fluorescent microscopy in defining a small ligule-like ovuliferous scale of a permineralized taxodiaceous cone from the upper cretaceous of Hokkaido,Japan

Fluorescent microscopy was proved to be effective for structural identification of permineralized plant tissues in calcite nodules from the Upper Cretaceous of Hokkaido, Japan. A minute, scale-like projection on the bract of a fossil Taxodiaceous cone is identified as a true ovuliferous scale because it is bordered with a continuous epidermis that exhibits prominent fluorescence. The presence of the ovuliferous scale suggests that the fossil is aTaiwania archetype.     

Knockout of the SREBP system increases production of the polyketide FR901512 in filamentous fungal sp. No. 14919 and lovastatin in Aspergillus terreus ATCC20542

Applied Microbiology and Biotechnology - In the production of useful microbial secondary metabolites, the breeding of strains is generally performed by random mutagenesis. However, because random...     

Peroxisomes of the nematode Caenorhabditis elegans: distribution and morphological characteristics

We analyzed the distribution and morphological characteristics of peroxisomes in the nematode Caenorhabditis elegans by routine electron microscopy, immunoelectron microscopy, and morphometry. Peroxisomes were mainly contained in the epithelial cells of the digestive tract and pharyngeal gland, but some were observed in other cells. Their shape varied from round to twisted. The matrix of most peroxisomes was coarse and uneven, and contained electron-dense nucleoids and frequently tubular substructures. The diameter of peroxisomes in the gut (0.185 micro m) was smaller than that in pharyngeal gland (0.262 micro m). The volume density of peroxisomes per 100 micro m(2) of cytoplasm was 1.86 in the gut and 1.75 in the pharyngeal gland. After treatment with clofibrate, the diameter of peroxisomes increased approximately 1.11-fold in the gut and 1.2-fold in the pharyngeal gland. The volume density of peroxisomes also increased by 2.2-fold in the gut and 2.6-fold in the pharyngeal gland. The labeling density for catalase-2 was almost identical between gut and pharyngeal gland peroxisomes. The results show that in C. elegans peroxisomes mainly distribute in the epithelial cells of the gut and pharyngeal gland. Peroxisomes of the pharyngeal gland are larger than those of the gut, but peroxisomes of both tissues contain catalase-2 at similar concentrations.     

Determinative mechanisms in secondary muscle lineages of ascidian embryos: development of muscle-specific features in isolated muscle progenitor cells

Muscle cells of the ascidian larva originate from three different lines of progenitor cells, the B-line, A-line and b-line. Experiments with 8-cell embryos have indicated that isolated blastomeres of the B-line (primary) muscle lineage show autonomous development of a muscle-specific enzyme, whereas blastomeres of the A-line and b-line (secondary) muscle lineage rarely develop the enzyme in isolation. In order to study the mechanisms by which different lines of progenitors are determined to give rise to muscle, blastomeres were isolated from embryos of Halocynthia roretzi at the later cleavage stages when conspicuous restriction of the developmental fate of blastomeres had already occurred. Partial embryos derived from B-line muscle-lineage cells of the 64-cell embryo (B7.4, B7.5 and B7.8) showed autonomous expression of specific features of muscle cells (acetylcholinesterase, filamentous actin and muscle-specific antigen). In contrast, b-line muscle-lineage cells, even those isolated from the 110-cell embryo (b8.17 and b8.19), did not express any muscle-specific features, even though their developmental fate was mainly restricted to generation of muscle. Isolated A-line cells from the 64-cell embryos (A7.8) did not show any features of muscle differentiation, whereas some isolated A-line cells from the 110-cell embryos (A8.16) developed all three above-mentioned features of muscle cells. This transition was shown to occur during the eighth cell cycle. These results suggest that the mechanism involved in the process of determination of the secondary-lineage muscle cells differs from that of the primary-lineage muscle cells. Interaction with cells of other lineages may be required for the determination of secondary precursors to muscle cells. The presumptive b-line and A-line muscle cells that failed to express muscle-specific features in isolation did not develop into epidermal cells. Thus, although interactions between cells may be required for muscle determination in secondary lineages, the process may represent a permissive type of induction and may differ from the processes of induction of mesoderm in amphibian embryos.     

Differential effects of reproductive interference by an alien congener on native Taraxacum species

Reproductive interference (RI) has been suggested to play a critical role in native plant displacement by alien congeners. However, although co-existence of native and alien congeners may provide an opportunity to refute the RI hypothesis, few studies have examined such a case. Using a native Japanese dandelion, Taraxacum longeappendiculatum, and a co-existing alien congener, Taraxacum officinale, we tested the hypothesis that differences in RI by the alien between native recipient congeners explain whether a native will co-exist with or be displaced by an alien. We conducted a field survey to investigate the effects of alien relative abundance on T. longeappendiculatum seed set, and a hand-pollination experiment to identify the extent of pollen interference by the alien on T. longeappendiculatum. We compared these results with those obtained previously for another Japanese native species, Taraxacum japonicum, which was displaced by the alien. In our field survey, alien relative abundance had little effect on seed set in nearby T. longeappendiculatum, and hand-pollination with mixed pollen grains produced no substantial decrease in seed set of the native species. Model selection supported these tendencies; the effect of RI by the alien differed between the two native species. Other potential factors, such as resource competition or habitat changes, could not explain the co-existence of T. longeappendiculatum with and exclusion of T. japonicum by the alien in the same explanatory framework. Considering the consistent explanatory power, the findings suggest that RI is a critical mechanism that can determine both co-existence with and displacement of native dandelions by an alien congener.     

Identification of miR-30e* Regulation of Bmi1 Expression Mediated by Tumor-Associated Macrophages in Gastrointestinal Cancer

Bmi1 is overexpressed in a variety of human cancers including gastrointestinal cancer. The high expression level of Bmi1 protein is associated with poor prognosis of gastrointestinal cancer patients. On the other hand, tumor-associated macrophages (TAMs) contribute to tumor growth, invasion, and metastasis by producing various mediators in the tumor microenvironment. The aim of this study was to investigate TAM-mediated regulation of Bmi1 expression in gastrointestinal cancer. The relationship between TAMs and Bmi1 expression was analyzed by immunohistochemistry and quantitative real-time PCR (qRT-PCR), and results showed a positive correlation with tumor-infiltrating macrophages (CD68 and CD163) and Bmi1 expression in cancer cells. Co-culture with TAMs triggered Bmi1 expression in cancer cell lines and enhanced sphere formation ability. miRNA microarray analysis of a gastric cancer cell line co-cultured with macrophages was conducted, and using in silico methods to analyze the results, we identified miR-30e* as a potential regulator of Bmi1 expression. Luciferase assays using miR-30e* mimic revealed that Bmi1 was a direct target for miR-30e* by interactions with the putative miR-30e* binding sites in the Bmi1 3′ untranslated region. qRT-PCR analysis of resected cancer specimens showed that miR-30e* expression was downregulated in tumor regions compared with non-tumor regions, and Bmi1 expression was inversely correlated with miR-30e* expression in gastric cancer tissues, but not in colon cancer tissues. Our findings suggest that TAMs may cause increased Bmi1 expression through miR-30e* suppression, leading to tumor progression. The suppression of Bmi1 expression mediated by TAMs may thus represent a possible strategy as the treatment of gastrointestinal cancer.     

Coordinated ciliary beating requires Odf2-mediated polarization of basal bodies via basal feet

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Highlights? Mice expressing truncated Odf2 cough and sneeze due to primary ciliary dyskinesia ? Full-length Odf2 is needed for the formation of basal body-associated basal feet ? In the absence of basal feet, basal bodies fail to align with planar polarity cues ? Polarization of basal bodies by Odf2 is required for coordinated ciliary beating     

Suppression of PI3K/mTOR pathway rescues LLC cells from cell death induced by hypoxia

Cancer cells in solid tumors are challenged by various microenvironmental stresses, including hypoxia, and cancer cells in hypoxic regions are resistant to current cancer therapies. To investigate the mechanism of resistance to hypoxia in cancer cells, we examined mouse Lewis lung carcinoma (LLC) cells, which died due to necrosis at high density under hypoxic but not under normoxic conditions. Levels of mammalian target of rapamycin (mTOR), a central regulator of cellular energy, are reported to be suppressed in hypoxia. We found that phosphorylation of two molecules downstream to it, ribosomal p70 S6 kinase (S6K) and ribosomal protein S6, was markedly suppressed by hypoxia. Overexpression of the active form of S6K increased the sensitivity of LLC cells to hypoxia. On the other hand, inhibition of PI3K or mTOR dramatically reduced hypoxia-induced cell death under hypoxic conditions. Under hypoxic conditions, blockade of the PI3K or mTOR pathway increased levels of intracellular ATP and delayed decreases in pH and glucose level in culture medium, without affecting the cell cycle.     

Effect of pre-treatment with St John's Wort on nephrotoxicity of cisplatin in rats

An herbal health care supplement, St John's Wort (SJW, Hypericum perforatum) has become widely used in the treatment of depression, and is known to interact with therapeutic drugs. Here we report a preventive effect of SJW on cisplatin nephrotoxicity in rats. Rats were given SJW (400 mg/kg/day, p.o.) for 10 consecutive days, and were injected with cisplatin (5 mg/kg, i.v.) on the day after the final SJW treatment. Cisplatin treatment increased the serum creatinine level, which is an index of nephrotoxicity, to 1.51+/-0.22 mg/dl (mean+/-SE) from 0.28+/-0.05 mg/dl (control) on day 5 after the cisplatin injection. This increase fell significantly to 0.86+/-0.13 mg/dl by pre-treatment with SJW. Cisplatin-induced histological abnormality of the kidney was blocked by pre-treatment with SJW. When SJW was administered for 10 days, the amounts of renal metallothionein (MT) and hepatic multidrug resistance protein 2 (Mrp2) were increased to 164.8+/-13.0% and 220.8+/-39.3% (mean+/-SE) of controls, respectively. GSH levels in the kidney and liver were not changed. Total and free cisplatin concentration in serum was not influenced by SJW treatment. In conclusion, the results suggest that pre-treatment with SJW may diminish cisplatin nephrotoxicity.