Distribution of Membrane-Associated Calcium in Fertilized Sea Urchin Eggs during Mitosis*

The distribution of membrane-associated calcium in dividing sea urchin eggs was examined with chlortetracycline as a fluorescent chelate probe. The fluorescence of bound chlortetracycline in fertilized eggs was initially evenly distributed, but began to gather around the nucleus in prophase, and formed a dumb-bell shaped condensation enclosing the mitotic apparatus by metaphase. During anaphase and telophase, the fluorescence was observed in kinetochore-to-pole regions of the spindle, with little fluorescence in the interkinetochore region. The astral regions showed intense fluorescence. The distribution of the chlortetracycline-fluorescence coincided with that of ER-like membranes seen in electron micrographs. The distribution of the fluorescence was obscure and the birefringence of spindles disappeared on perfusion on perfusion of the cells in metaphase with 1 mM tetracaine, which is known to displace membrane-bound calcium. These results suggest that intracellular free calcium ions are sequestered in the membrane system associated with the mitotic apparatus during mitosis.     

FORMATION AND CHARACTERIZATION OF THREE TYPES OF YEAST INVERTASE

Three types of invertase (invertase I, II and III) are separatedfrom the soluble and insoluble fractions (4,500xg, 10 min supernatantand pellets of the homogenate, respectively) of baker's yeastby a DEAE cellulose column chromatography. The invertases Iand II are eluted with 0.1 M sodium acetate buffer (pH 3.9)and with 0.1 M sodium acetate buffer (pH 6.2) containing 0.1M NaCl from DEAE cellulose respectively, whereas the invertase-IIIremains adsorbed on the cellulose under these conditions. Theyare present in proportions of 2.5: 1 : 0.06 in the soluble fractionand 1.4: 1 : 0.12 in the insoluble fraction of the fresh baker'syeast cells. While in-vertase-II remains at a constant level,invertases I and III in the soluble fraction increase upon incubationof cells for the formation of invertase under the continuoussupply of sucrose. Invertases I and II differ from each other considerably in theoptimum pH and slightly in the response to (activation and inactivationby) crude papain and are identical with respect to the heatstability and probably to the affinity for sucrose. ¹Present address: Chemical Laboratory, Nippon Medical School,Konodai, Ichikawa-shi, Chiba-ken.     

Growth Response to Hormones by a New Rat Ovary Cell Line

SEVERAL endocrine cell lines established in recent years show a functional response to hormones in vitro¹ but, except for one mammary cell line², none of them exhibits the normal hormone requirement for growth in vivo. We have now isolated a rat ovarian cell line whose growth in vitro is markedly stimulated by bovine luteinizing hormone (LH-NIH-B7), a pituitary gonadotrophin and by dexamethasone, a synthetic glucocorticoid. This cell line provides the first permanent in vitro system for studying the growth stimulation of gonadal cells by hormones.     

Life history and host specificity of the Japanese flea beetles Trachyaphthona sordida and T. nigrita (Coleoptera: Chrysomelidae), potential biological control agents against skunk vine, Paederia foetida (Rubiaceae), in the southeastern parts of the United States and Hawaii

Skunk vine, Paederia foetida (Rubiaceae), is native to Asia and has been recognized as an invasive weedy vine of natural areas in Florida and Hawaii. Two insects, Trachyaphthona sordida and Trachyaphthona nigrita (Coleoptera: Chrysomelidae) from Japan are being considered as potential biological control agents against skunk vine. To gather fundamental information on their biology, we carried out field surveys and laboratory experiments in Kyushu, southern Japan, between 2003 and 2006. We found that T. sordida is commonly distributed in Kyushu and T. nigrita is restricted to the southern parts of Kagoshima Prefecture on the southern part of Kyushu. These species are fundamentally univoltine and adults appear in late April to early July. Trachyaphthona sordida overwinters as mature larvae and T. nigrita as mature larvae or rarely as adults. Larvae of both species feed on fine roots of P. foetida in the field and Serissa foetida (Rubiaceae) under rearing conditions, and they appear to have tribe‐level host specificity in their host range. On the basis of these results, we suggest that both species are suitable as biological control agents.     

Quantitative Analysis of Protein Synthesis Altered by Estrogen in Cultured Xenopus Liver Parenchymal Cell

Using the primary culture system of male Xenopus laevis hepatocytes consisting of more than 95% parenchymal cells, the effect of estradiol-17 β (10⁻⁶M) on protein synthesis was quantitatively analyzed by ³H-leucine incorporation kinetics and the estimation of specific radioactivity of newly synthesized secretory protein. The cells in a well defined culture revealed high plating efficiency and very low DNA synthetic activity. The cultured cells could synthesize several secretory proteins containing serum albumin. The pattern of secreted proteins in SDS-polyacrylamide gel electrophoresis (SDS-PAGE) did not alter with culture time but secretion rate of protein increased for 7 days, starting on the third day following inoculation. Estradiol added to the culture media extensively induced the synthesis of yolk precursor protein vitellogenin which accounted for 40–50% of the overall secretory protein synthesis and 20–30% of the total protein synthesis on day 7 of estradiol treatment. Ultimately, the total protein synthesis and secretory protein synthesis were stimulated 1.2–1.3 fold and 2.0–2.2 fold, respectively, over those of the control cells cultured in the absence of estradiol. These results indicated that the stimulation of protein synthesis was largely due to vitellogenin production. Such an estradiol-dependent stimulation of protein synthesis was also detected in the low molecular weight protein(s). On the other hand, albumin synthesis was evidently reduced by estradiol. Thus, estradiol had two different effects on protein synthesis.
The results obtained in this study will be discussed in relation to the findings o in vivo experiments.     

DIFFERENCE IN INDUCTIVE EFFECT OF LIVER TISSUES WITH AND WITHOUT PERISINUSOIDAL BASEMENT MEMBRANE

Differential inductive capacities among liver tissues of several animals were examined by anticipating the correlation between the capacity and the completness of perisinusoidal basement membrane.
The reacting tissue was competent ectoderm of gastrula of Triturus pyrrhogaster , and the inductive effects of livers on the ectoderm were tested by explantation method. The inductive effect of livers being devoid of the membrane (chick and guinea pig) was neural and the tissues having the dense well-developed membrane (reptiles) produced an assembly of neural and meso-dermal tissues, such as notochord and somite or muscle. The livers with the membrane being of intermediate grade of development ( calf, Triturus and mouse) induce mesodermal tissues, but not frequently, together with neural tissue or alone. The liver tissue was more active in mesodermal induction in proportion to the completeness of the perisinusoidal basement membrane.
On the basis of these data the difference in inductive capacity among liver tissues from different kinds of animals were discussed.     

BIOCHEMICAL CHANGES IN YEAST DURING SPORULATION. II. ACETATE METABOLISM

Acetate metabolism was studied with Saccharomyces cerevisiae diploid strain G2-2 in sporulating culture, asporogenic diploid strains 3c × a and 3c × 3a, and respiratory deficient haploid strain 3c (asporogenic). Acetate in a sporulating medium was utilized by sporogenic and asporogenic diploid yeasts linearly with time. Activities of aconitase, NADP-linked isocitrate dehydrogenase, and succinate dehydrogenase initially increased in the cell-free homogenate of either strain. Activity of glucose-6-phosphate dehydrogenase decreased. Isocitrate lyase activity increased remarkably in the sporogenic strain but not in the asporogenic strain. The rate of production of ¹⁴CO₂ from ¹⁴C-1-acetate was accelerated more than from ¹⁴C-2-acetate in intact cells of the sporogenic strain during sporulating culture. Fractionation of radioactive cell substances showed remarkable lipid synthesis. Accumulation and reutilization of cold acid-soluble precursor substances occurred during sporogenesis. The role of glyoxylate and tricarboxylate cycle enzymes in sporulation is discussed.     

A roundtable on responsible innovation with autologous stem cells in Australia,Japan and Singapore

We report on a roundtable event hosted in Singapore that sought to identify some of the ethical and regulatory challenges in translating autologous cell-based interventions, particularly those claiming to involve stem cells, into safe and effective therapies and to propose some solutions to encourage responsible innovation with these products. Challenges are identified in the three areas of cell manufacturing and processing, innovative uses of autologous cells in clinical practice and standards of evidence. Proposed solutions are discussed within a co-operative model of statutory laws and regulations that can enable product development with autologous cells and professional codes and standards that can encourage ethical conduct in clinical practice. Future research should be directed toward establishing regional networks for the development of internationally consistent standards in manufacturing and ethical codes of conduct for innovating with stem cells, and other autologous cells, and fostering ongoing exchange between jurisdictions.     

A NEW ELASMOSAURID PLESIOSAUR FROM THE UPPER CRETACEOUS OF FUKUSHIMA, JAPAN

Abstract:  A new genus and species of an elasmosaurid plesiosaur, Futabasaurus suzukii , is described based on a partial skeleton from the Inoceramus amakusensis Zone (Lower Santonian, Upper Cretaceous) of the Irimazawa Member of the Tamayama Formation, Futaba Group, in Fukushima Prefecture, Japan. The new taxon is characterized by a number of characters such as the wide space between the orbit and external naris, posterior extension of the interclavicle, relatively long humerus and prominent femoral muscle scar. The holotype includes a partial skull and mandible, posterior cervicals to sacrals, ribs, clavicular arch, pelvic girdle and four limbs. The remains are mostly in articulation, and exhibit evidence of predation/scavenging by sharks. The distribution of elasmosaurid species in the circum-Pacific region remains unclear due to the lack of diagnostic materials. The occurrence of F. suzukii is geographically and stratigraphically significant, because it allows species-level comparison; as a diagnosable elasmosaurid specimen, F. suzukii is the first and the oldest from the northern Pacific.