Hypoxia-inducible factor 1α regulates branching morphogenesis during kidney development

The kidneys are exposed to hypoxic conditions during development. Hypoxia-inducible factor (HIF), an important mediator of the response to hypoxia, is believed to have an important role in development. However, the relationship between HIF and branching morphogenesis has not been elucidated clearly.     

Human hand impedance characteristics during maintained posture

Received: 23 June 1993 / Accepted in revised form: 15 September 1994     

Fragile X expression in thymidine-prototrophic and auxotrophic human-mouse somatic cell hybrids under low and high thymidylate stress conditions

Expression of the fragile X site fra(X)(q27.3) was studied in thymidine-prototrophic and auxotrophic human-mouse somatic cell hybrids. In these cells, low thymidylate stress, achieved by 5-fluoro-2'-deoxyuridine (FdU) treatment and by limiting the exogenous supply of thymidine (dT), induced fragile X expression. High thymidylate stress, produced by supplying excess amounts of dT, was also effective in inducing fragile X expression, even in a hybrid clone that retained a fragile X chromosome as the only human chromosome; addition of deoxycytidine (dC) completely abolished this effect. In contrast, 5-bromo-2'-deoxyuridine (BrdU) did not induce fragile X expression. Cell-cycle analysis of BrdU-deprived thymidine-auxotrophic hybrid cells indicated that one round of DNA replication under thymidylate stress conditions is sufficient for fragile X expression. Our results suggest that the expression is an intrinsic property of the fragile site itself, which is believed to be composed of replicon clusters with pyrimidine-rich DNA sequence(s).     

Solubilization of membrane-bound acid alpha-glucosidase by proteolysis

The membrane-bound acid alpha-glucosidase was purified partially (400-fold) from human placenta by solubilization with trypsin, concanavalin A-Sepharose chromatography, Ultrogel AcA-34 gel filtration, and Sephadex G-100 affinity chromatography. Two molecular forms of the enzyme were found in the final preparation of the purified enzyme. They were identical in molecular weight with a precursor (110 kDa) and an early intermediate form (105 kDa) of this enzyme. Also direct incubation of the membrane fraction without trypsin resulted in a release mainly of the 105 kDa form, which was inhibited by N-ethylmaleimide, but not by leupeptin, pepstatin or phenylmethylsulfonylfluoride. It was concluded that the precursor of acid alpha-glucosidase is an intrinsic membrane protein, which is transported into lysosomes after solubilization by proteolysis.     

Light-Controlled Cytoplasmic Streaming in Vallisneria Mesophyll Cells

The effect of light irradiation on cytoplasmic streaming inVallisneria mesophyll cells was investigated. Red light (     

Automation of microbial enumeration: development of a disposable hydrophobic grid-membrane filter unit

A disposable filter unit containing a hydrophobic grid-membrane filter (HGMF) was developed. The unit is liquid tight to serve as a specimen transport container and, by removal of the funnel extender (175- or 300-ml capacity), the unit becomes less than the height of two stacked petri plates to save space during in situ incubation. The polyethylene mesh which supports the HGMF facilitates rinse removal of any substance(s) that would interfere with microbial growth. The correlations between a pour plate, a conventional square HGMF, and a disposable filter unit on microbial enumeration were examined. Characteristics (e.g., clumping, spreading, etc.) of some microorganisms limit the linear counting range to less than 1,000 CFU per filter.     

Determination of trace levels of fatty acid metal salts by high-performance liquid chromatography with fluorescence prelabeling

A simple method is described for picomole determinations of fatty acid metal salts. Fatty acid salts are directly labeled with 4-bromomethyl-7-methoxycoumarin in the presence of excess ethylenediaminetetraacetic acid tripotassium salt without any solvent extractions. The fluorescence derivatives of fatty acids are separated by reverse-phase high-performance liquid chromatography followed by fluorometric detection. The response of each fatty acid (C8-C18) calcium salt is linear from 1 to 50 micrograms/ml of samples. The detection limit is about 7 pmol. Good recoveries are obtained for the calcium salts of myrystic acid and soap (C8-C18, C18:1,2). The new method is successfully applied to the study on biodegradation of fatty acids in river water.     

Fluorophotometric enzyme immunoassay of thyroid-stimulating hormone.

A method for enzyme immunoassay of thyroid-stimulating hormone (TSH) is described, TSH was conjugated with horseradish peroxidase according to periodate oxidation method. Separation of the bound and free was obtained by double-antibody solid-phase technique using Sepharose 4B-anti-rabbit immunogiobulin G (IgG)-geat IgG. The fluorescence reaction using tyramine and hydrogen peroxide as substrates was used for the determination of enzyme activity in order to increase the sensitivity of enzyme immunoassay. The standard curve for serum TSH was satisfactory to recognize TSH concentrations as 0.06 μU/tube. TSH values obtained by this method correlated well with those obtained by radioimmunoassay (r, 0.96). The coefficients of variation were 1.8 to 5.3% (within assay) and 5.1 to 10.5% (between assay). The method is about equal to radioimmunoassay with respect to sensitivity. Since it requires minimal equipment and is less expensive than radioimmunoassay, it is possible to perform routine assays even in laboratories with limited facilities.