The Caenorhabditis elegans eukaryotic initiation factor 5A homologue, IFF-1, is required for germ cell proliferation, gametogenesis and localization of the P-granule component PGL-1

Eukaryotic initiation factor 5A (eIF-5A) was originally isolated as a translation initiation factor. However, this function has since been reconsidered, with recent studies pointing to roles for eIF-5A in mRNA metabolism and trafficking [Microbiol. Mol. Biol. Rev. 66 (2002) 460; Eur. Mol. Biol. Org. J. 17 (1998) 2914]. The Caenorhabditis elegans genome contains two eIF-5A homologues, iff-1 and iff-2, whose functions in vivo were examined in this study. The iff-2 mutation causes somatic defects that include slow larval growth and disorganized somatic gonadal structures in hermaphrodites. iff-2 males show disorganized tail sensory rays and spicules. On the other hand, iff-1 mRNA is expressed in the gonad, and the lack of iff-1 activity causes sterility with an underproliferated germline resulting from impaired mitotic proliferation in both hermaphrodites and males. In spite of underproliferation, meiotic nuclei are observed, as revealed by presence of immunoreactivity to the anti-HIM-3 antibody; however, no gametogenesis occurs in the iff-1 gonads. These phenotypes are in part similar to the mutants affected in the components of P granules, which are the C. elegans counterparts of germ granules [Curr. Top Dev. Biol. 50 (2000) 155]. We found that localization of the P-granule component PGL-1 to P granules is disrupted in the iff-1 mutant. In summary, the two C. elegans homologues of eIF-5A act in different tissues: IFF-2 is required in the soma, and IFF-1 is required in the germline for germ cell proliferation, for gametogenesis after entry into meiosis, and for proper PGL-1 localization on P granules.     

Mutations affecting somite formation in the Medaka (Oryzias latipes)

The metameric structure of the vertebrate trunk is generated by repeated formation of somites from the unsegmented presomitic mesoderm (PSM). We report the initial characterization of nine different mutants affecting segmentation that were isolated in a large-scale mutagenesis screen in Medaka (Oryzias latipes). Four mutants were identified that show a complete or partial absence of somites or somite boundaries. In addition, five mutations were found that cause fused somites or somites with irregular sizes and shapes. In situ hybridization analysis using specific markers involved in the segmentation clock and antero-posterior (A-P) polarity of somites revealed that the nine mutants can be compiled into two groups. In group 1, mutants exhibit defects in tailbud formation and PSM prepatterning, whereas A-P identity in the somites is defective in group 2 mutants. Three mutants (planlos, pll; schnelles ende, sne; samidare, sam) have characteristic phenotypes that are similar to those in zebrafish mutants affected in the Delta/Notch signaling pathway. The majority of mutants, however, exhibit somitic phenotypes distinct from those found in zebrafish, such as individually fused somites and irregular somite sizes. Thus, these Medaka mutants can be expected to provide clues to uncovering novel components essential for somitogenesis.     

Anti-angiogenic effects of thalidomide: expression of apoptosis-inducible active-caspase-3 in a three-dimensional collagen gel culture of aorta

The anti-angiogenic properties of thalidomide have led to the use of the agent as a remedy for multiple myeloma. Nevertheless, the anti-angiogenic moiety of thalidomide remains unidentified. In this study we examined the anti-angiogenic effects of thalidomide in an in vitro model using a three-dimensional collagen gel culture. Angiogenesis was significantly inhibited when the culture was treated with thalidomide plus cytochrome P-450 (CYP2B4), and the migrating cells and tubules were positive for active-caspase-3 in an accompanying immunohistochemical investigation. Transmission electron microscopic observation also confirmed that active-caspase-3-positive cells demonstrated apoptotic characteristics. This study is the first to morphologically demonstrate the effect of thalidomide in directly inducing the apoptosis of new tubules and migrating cells on a three-dimensional collagen gel culture of aorta. Taken together with earlier findings, our new results indicate that the thalidomide-induced inhibition of angiogenesis involves apoptosis in addition to the suppression of TNF- and inhibition of cell migration from aorta explants, i.e., the factors important for capillarogenesis.     

Six1 controls patterning of the mouse otic vesicle

Six1 is a member of the Six family homeobox genes, which function as components of the Pax-Six-Eya-Dach gene network to control organ development. Six1 is expressed in otic vesicles, nasal epithelia, branchial arches/pouches, nephrogenic cords, somites and a limited set of ganglia. In this study, we established Six1-deficient mice and found that development of the inner ear, nose, thymus, kidney and skeletal muscle was severely affected. Six1-deficient embryos were devoid of inner ear structures, including cochlea and vestibule, while their endolymphatic sac was enlarged. The inner ear anomaly began at around E10.5 and Six1 was expressed in the ventral region of the otic vesicle in the wild-type embryos at this stage. In the otic vesicle of Six1-deficient embryos, expressions of Otx1, Otx2, Lfng and Fgf3, which were expressed ventrally in the wild-type otic vesicles, were abolished, while the expression domains of Dlx5, Hmx3, Dach1 and Dach2, which were expressed dorsally in the wild-type otic vesicles, expanded ventrally. Our results indicate that Six1 functions as a key regulator of otic vesicle patterning at early embryogenesis and controls the expression domains of downstream otic genes responsible for respective inner ear structures. In addition, cell proliferation was reduced and apoptotic cell death was enhanced in the ventral region of the otic vesicle, suggesting the involvement of Six1 in cell proliferation and survival. In spite of the similarity of otic phenotypes of Six1- and Shh-deficient mice, expressions of Six1 and Shh were mutually independent.     

Synergistic interaction of three ERECTA-family receptor-like kinases controls Arabidopsis organ growth and flower development by promoting cell proliferation

Growth of plant organs relies on coordinated cell proliferation followed by cell growth, but the nature of the cell-cell signal that specifies organ size remains elusive. The Arabidopsis receptor-like kinase (RLK) ERECTA regulates inflorescence architecture. Our previous study using a dominant-negative fragment of ERECTA revealed the presence of redundancy in the ERECTA-mediated signal transduction pathway. Here, we report that Arabidopsis ERL1 and ERL2, two functional paralogs of ERECTA, play redundant but unique roles in a part of the ERECTA signaling pathway, and that synergistic interaction of three ERECTA-family RLKs define aerial organ size. Although erl1 and erl2 mutations conferred no detectable phenotype, they enhanced erecta defects in a unique manner. Overlapping but distinct roles of ERL1 and ERL2 can be ascribed largely to their intricate expression patterns rather than their functions as receptor kinases. Loss of the entire ERECTA family genes led to striking dwarfism, reduced lateral organ size and abnormal flower development, including defects in petal polar expansion, carpel elongation, and anther and ovule differentiation. These defects are due to severely reduced cell proliferation. Our findings place ERECTA-family RLKs as redundant receptors that link cell proliferation to organ growth and patterning.     

Determination of potato glycoalkaloids using high-pressure liquid chromatography-electrospray ionisation/mass spectrometry

A method for quantifying two toxic glycoalkaloids, alpha-solanine and alpha-chaconine, in potato (Solanum tuberosum) tuber tissue was developed using HPLC-electrospray ionisation (ESI)/MS. Potato samples were extracted with 5% aqueous acetic acid, and the extracts were subjected directly to HPLC-ESI/MS after filtration. By determining the intensities of the protonated molecules of alpha-solanine (m/z 868) and alpha-chaconine (m/z 852) using selected ion monitoring (positive ion mode), a sensitive assay was attained with detection limits of 38 and 14 ppb for the two glycoalkaloids, respectively. The high sensitivity and selectivity of MS detection effectively reduced the time of analysis thus enabling a high throughput assay of glycoalkaloids in potato tubers.     

Japanese attitudes towards foreign languages

The purpose of this study is to clarify Japanese attitudes towards foreign languages based on the kinds and changes of TV and radio programs that aired on the Japanese national broadcasting station (NHK) between 1955 and 2000. Foreign language programs are classified into three groups according to their content: 1) cultivation, 2) education, or 3) communication. For Japanese people, foreign languages are the measures of intelligence and intellect. Studying a foreign language is considered a sign of intelligence whether or not it is used for actual communication. The number of foreign language programs has increased tremendously since 1965 in part because the global economy has brought many countries in such close contact. Since 1990, programs for the purpose of communication have increased because of the necessity to communicate with foreign people. Japanese attitudes towards studying foreign languages have been changing gradually from an intellectual purpose to a communication purpose.