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.     

The APC/C activator Cdh1 regulates the G2/M transition during differentiation of placental trophoblast stem cells

Differentiation of placental trophoblast stem (TS) cells to trophoblast giant (TG) cells is accompanied by transition from a mitotic cell cycle to an endocycle. Here, we report that Cdh1, a regulator of the anaphase-promoting complex/cyclosome (APC/C), negatively regulates mitotic entry upon the mitotic/endocycle transition. TS cells derived from homozygous Cdh1 gene-trapped (Cdh1^GT/GT) murine embryos accumulated mitotic cyclins and precociously entered mitosis after induction of TS cell differentiation, indicating that Cdh1 is required for the switch from mitosis to the endocycle. Furthermore, the Cdh1^GT/GT TS cells and placenta showed aberrant expression of placental differentiation markers. These data highlight an important role of Cdh1 in the G2/M transition during placental differentiation.     

Polyclonal Antibody Production in Murine Spleen Cells Induced by Staphylococcus

Polyclonal plaque-forming cell (PFC) responses in murine spleen cells induced by Staphylococcus aureus and S. epidermidis were studied. Injection of Balb/c mice with S. aureus strain 248βH resulted in the generation of anti-trinitrophenyl (TNP) and anti-sheep red blood cell PFC in their spleens. Cultures of Balb/c spleen cells in the presence of S. aureus 248βH, Cowan I, or a protein A-deficient mutant yielded many anti-TNP PFC. The larger the number of organisms that were added to the cultures, the better was the PFC response. Both living and killed organisms, were capable of inducing the response, but an excess of living 248βH organisms in the cultures abrogated the response. All of the organisms (12 strains of S. aureus and 11 strains of S. epidermidis) freshly isolated from patients had the ability to induce the polyclonal PFC response in cell cultures. These organisms stimulated cultured C3H/HeJ mouse spleen cells, which were unresponsive to bacterial lipopolysaccharide (LPS). Cultured cells from the spleens of athymic nu/nu mice also responded to these organisms, and the number of PFC in nu/nu cell cultures was always greater than that in nu/+ cells prepared from a haired litter mate. Moreover, the responses of nu/nu spleen cell cultures to which nylon wool column-filtered splenic nu/+ T cells were added were lower than expected. These findings suggest that the polyclonal PFC response to staphylococci is thymus independent, but that the magnitude of the response is regulated by mature T cells. Cultures of macrophage-depleted spleen cells responded to the organisms to an extent similar to that of the control. The 248βH organisms were less capable of stimulating spleen cells of 2-week-old mice (i.e., early maturing B cells) than LPS. However, spleen cells from adult (7-week-old) and aged (9-month-old) mice responded well to both the organisms and LPS. Previous sensitization with the organisms in vivo did not affect any polyclonal responses of spleen cells in vitro to either the organisms or LPS. The role of staphylococcal protein A in the polyclonal PFC response to staphylococci is discussed.     

LiCl treatment releases a nickase implicated in genetic transformation of Streptococcus pneumoniae.

When cells competent for genetic transformation of Streptococcus pneumoniae which could bind and enable entry of extracellular DNA molecules were treated with LiCl, they released a nickase that introduced nicks into a double-stranded DNA in the presence of EDTA. The nickase was specific for competent cells and coupled with DNA-binding activity. Furthermore, when noncompetent cells were treated with LiCl, they released the putative receptors for the competence activator.     

Reassessment of insulin effects on the Vmax and Km values of hexose transport in isolated rat epididymal adipocytes

Effects of insulin on the kinetic parameters of hexose transport in rat epididymal adipocytes were re-examined. The transport activity was assessed by measuring the rate of uptake of 3-O-[3H]methyl-D-glucose (MeGlc) under equilibrium exchange and zero-trans conditions. The incubation was carried out at 37 degrees C in an infant incubator. During the incubation, the cell suspension (25%, v/v, in a total volume of 48 microliter) was mechanically swirled at a rate of 600 rpm (r = 2 mm). The swirling facilitated the rapid uptake of MeGlc without stimulating the basal transport activity by "mechanical agitation". The basal and insulin-treated cells were incubated under identical conditions, except for the length of the incubation period. The incubation was terminated by the addition of 350 microliters of 1 mM phloretin, which inhibited transport in approximately 0.06 s. The time course of MeGlc uptake was consistent with the view that the process was a multiple-phase reaction. The initial phase of the reaction was completed when the intracellular distribution space of MeGlc was approximately 1% of the total cell volume. Insulin (10 nM) increased the Vmax value of MeGlc uptake 16-fold in equilibrium exchange experiments and 18-fold in zero-trans experiments. At the same time, the hormone decreased the Km value of MeGlc uptake from 11.7 to 5.4 mM in equilibrium exchange experiments and from 9.7 to 4.8 mM in zero-trans experiments. It is concluded that the major effect of insulin on MeGlc uptake is to increase the Vmax value, but the hormone has the additional effect of lowering the apparent Km value.     

Anomeric specificity of glucose effect on cAMP, fructose 1,6-bisphosphatase, and trehalase in yeast

The addition of beta-D-glucose (final concentration, 50 mM) to a cell suspension of Saccharomyces cerevisiae in stationary phase caused a rapid 4-fold increase in the concentration of cAMP, while a 2-fold increase of cAMP was observed by the addition of alpha-D-glucose. beta -D-Glucose was also more effective than alpha-D-glucose in the inactivation of fructose 1,6-bisphosphatase and the activation of trehalase. These results, taken together with the previous report that alpha-D-glucose is transported more rapidly than beta-D-glucose in Saccharomyces cerevisiae, do not support the view currently proposed by some investigators that cotransport of D-glucose with protons causes the depolarization of the cell membrane, resulting in the activation of adenylate cyclase. The present data, however, provides supporting evidence for the view that cAMP-dependent protein kinase is implicated in the inactivation of fructose 1,6-bisphosphatase and the activation of trehalase.     

Extensin Secreted into the Culture Medium by Tobacco Cells I. Purification and Some Properties

The medium of 12-day-old culturs of tobacco cells (Nicotianatabacum L., var Xanthi; line XD-6S) contain c.a. 160mg/literof protein, of which 14% of the constituent ami no acids werefound to be hydroxyproline. By sequential column chromatographiesand CsCl density-gradient centrifugation, a basic hydroxyproline-richglycoprotein was purified from the medium and found to havean amino acid composition typical of extensin; with a high levelof hydroxyproline (33mole%), tyrosine (13%), and lysine (14%).The glycoprotein contained 42% (w/w) of sugars, among whicharabinose was the major component (85%). The proportion of thisextensin in the proteins in the culture medium was estimatedto be much higher than that of arabino-galactan protein (about5 times higher) on a protein basis, with extensin comprisingbetween 25% and 41%, and probably about 37% of the proteinsin the medium. (Received September 19, 1988; Accepted December 26, 1988)     

Cord transferrin and ferritin values for erythropoiesis in newborn infants of diabetic mothers

Neonatal polycythemia is a perinatal complication in infants of diabetic mothers. The cord CBC (complete blood counts), serum iron, transferrin and ferritin concentrations were studied in newborn infants of 9 GDM (gestational diabetes), 21 NIDDM (noninsulin-dependent diabetes mellitus), and 8 IDDM (insulin-dependent diabetes mellitus) mothers. The RBC (red blood cell) count, Hb (hemoglobin) and Hct (hematocrit) of these infants were higher than control infants. There was no difference between the serum iron concentration of the infants of each group diabetic mothers and the infants in the control group, but the transferrin concentration was significantly higher and the ferritin was significantly lower in the infants of diabetic mothers than in those of control mothers. There was a significant negative correlation between transferrin and ferritin (r = -0.491 p less than 0.001). Erythropoiesis is considered to be enhanced in the fetuses of diabetic mothers, and the iron needed for erythropoiesis is reportedly transported from the mother to the fetus according to the demands of the fetus, but the iron storage was shown to be reduced in the fetuses of diabetic mothers.     

Immunohistochemical localization of proteoglycans in interstitial elements of human pancreas and biliary system

Summary The immunohistochemical localization of large proteoglycan and small proteoglycan was observed, using antibodies 2B1 and 6B6 (Sobueet al., 1988, 1989a), in fetal and adult pancreas and biliary system as well as in tumour tissues, obtained from 11 autopsies and 74 biopsies. The distribution of chondroitin 4- and 6-sulphate side chains, type I and IV collagen and elastin were also studied. In adult pancreas and all the biliary tracts examined, periductal fibrous tissues consisted mainly of dermatan sulphate small proteoglycan with networks of fibrous elements, which were composed of large proteoglycan, elastin, type I collagen and type IV collagen. In the interstitial components of cystadenoma of pancreas and biliary duct carcinoma, similar small proteoglycan-rich components were relatively abundant, although large proteoglycan was present in much larger amounts than that in non-neoplastic adult tissues. In some cholangiomas, the extra-and intracellular hyaline globules formed by the carcinoma cells were found to contain chondroitin sulphate large proteoglycan, laminin and fibronectin.The distribution of proteoglycans was observed to be different in the arterial walls of the interlobular tissues of the adult and the fetal pancreas. The biological significance of large and small proteoglycans in the interstitial connective tissues was discussed.     

Transient expression of the β-glucuronidase gene introduced into barley coleoptile cells by microinjection

A -glucuronidase gene was introduced directly into barley (Hordeum vulgare L. cv. Kobinkatagi) coleoptile cells by microinjection and transient expression of the gene was examined. Inner epidermis tissue of coleoptiles was excised and injected with plasmid DNA, pBI221, carrying cauliflower mosaic virus 35S promoter, -glucuronidase gene, and a nopaline synthase polyadenylation region. Histochemical assay for -glucuronidase production showed positive enzyme activity only in coleoptile cells injected with plasmid DNA. Expression of the -glucuronidase gene was examined chronologically using honogenates of injected coleoptile tissues. Glucuronidase activity first appeared after 6 hr, reached the maximum level 24 hr after injection, and decreased afterwards. These results suggest that microinjection of coleoptile tissues may be a useful approach for the genetic engineering of Gramineae plants in which protoplast regeneration is difficult.