Degenerative changes and carotenoid uptake in the silk gland of the silkworm Bombyx mori

In the middle silk gland of the silkworm Bombyx mori, especially in the middle region, structural changes were studied in relation to absorbing activity, using a transplantation method. The physiologically active gland, which was prepared by the decapitation at the feeding stage of the fourth larval instar, maintained a normal structure when placed in the larval body cavity during the middle stage of the fourth instar or during the early stage of the fifth (last) larval instar. But, if the gland was placed there during the fourth larval-larval pharate stage, histolytic changes, e.g. invagination of tunica propria, its separation from the cell and contraction of the cell, took place in the tissue. These results suggest that, once activated, cells in the middle region of the middle silk gland undergo degenerative changes even in the presence of the corpus allatum hormone during the larval-larval pharate period.     

Effect of Tween 80 on glucosyltransferase production in Streptococcus mutans.

Glucan production from sucrose by Streptococcus mutans OMZ 176 was stimulated approximately threefold in the presence of 0.1% Tween 80. When OMZ 176 was grown in a medium containing glucose, the glucosyltransferase level in the medium was also increased about fivefold in the presence of 0.1% Tween 80. The glucosyltransferase level increased in proportion to the logarithm of the concentration of Tween 80 in the glucose medium. Tween 80 affected neither bacterial growth nor the activity of glucosyltransferase. The appearance of glucosyltransferase in the glucose medium was inhibited immediately by chloramphenicol and actinomycin D and, after a lag, by rifampin as well. It was observed that the fatty acid composition of the cells grown with Tween 80 was altered. These results suggest that Tween 80 stimulates glucosyltransferase synthesis either directly, or indirectly by promoting glucosyltransferase secretion.     

Production of itaconic acid by Aspergillus terreus immobilized in polyacrylamide gels

Summary Living Aspergillus terreus cells were entrapped in polyacrylamide gels and employed in both replacement batch and continuous column reactors to produce itaconic acid from glucose.With the replacement batch reactor, maximum itaconic acid productivity was observed under the following conditions: pH 2.50, temperature at 35°C, addition of NH₄H₂PO₄ and MgSO₄·7H₂O. Using the continuous reactor, the maximum itaconic acid yield was 60 mg/h/40 g of gel. The biocatalyst activity or half-life was about 10 days.     

Molecular cloning and sequencing of cDNA encoding the phosphatidylinositol kinase from rat brain.

A complementary DNA (cDNA) clone that encodes phosphatidylinositol 4-kinase (PI 4-kinase) was isolated from a rat brain cDNA library. The deduced amino acid sequence of 697 residues revealed that the protein contains two putative transmembrane sequences and that the N-terminal part of the protein has several sequences representing potential phosphorylation sites for cAMP- and calmodulin-dependent kinase. The C-terminal region is probably a phosphotransferase domain homologous to the kinase region of protein kinase family proteins. Specific antibody against the protein expressed in Escherichia coli successfully immunoprecipitated rat brain PI 4-kinase. The messenger RNA for PI 4-kinase was found predominantly in brain and rat neural cell lines. This PI kinase may play a specific role in neural signal transduction.     

A case of renin producing leiomyosarcoma originating in the lung.

A 54-year-old woman was referred to our hospital for the treatment of a tumor of the right chest wall. Clinical examination revealed hypertension, hypokalemia, metabolic alkalosis, hyperaldosteronism and hyperreninemia. Computed tomography and an abdominal echogram indicated a tumor in the right phrenic area and two tumors in the retroperitoneum near the pancreas head. After the surgical resection of these tumors, the primary reninism was diminished. The pathological diagnosis of these tumors was leiomyosarcoma. Plasma active and inactive (trypsin-activated) renin activities (PRA) were 85.7 and 38.9 ng angiotensin I/ml/h, respectively. These PRA did not respond to either postural stimulation or suppression by the volume expansion. Active and inactive renin activities in a right phrenic area tumor were 208 and 32 ng angiotensin I/mg protein /h, respectively. Those of an abdominal tumor were 196 and 30 ng angiotensin I/mg protein/h, respectively. Renin mRNA identical in molecular size to that of the human kidney was identified by northern blot analysis. This is the first case report of renin producing leiomyosarcoma derived from the lung, which is characterized by relatively lower plasma prorenin concentrations.     

Hydration of oligosaccharides: anomalous hydration ability of trehalose.

The disaccharide trehalose extensively exists in anhydrobiotic organism and is considered to play an important role in preserving the integrity of biomembrane. However, the preserving mechanism remains unclear. In this report, we examine the hydration abilities of trehalose and several oligosaccharides composed of alpha-D-glucopyranosyl residues. The unfrozen water fraction per molecule was determined from differential scanning calorimetry measurements of their aqueous solutions. Further, the NMR relaxation time of the natural abundance 17O of water is measured for several saccharide solutions. These results indicate that trehalose has the highest hydration ability among the saccharides studied. In other words, trehalose can effectively lower the mobility of water molecules hydrogen-bonded with saccharides. It is thus reasonable that, among the disaccharides studied, trehalose exhibits the maximum stabilizing effect on the bilayer structure of lipid whose acyl chains are bonded with each other by the apolar interaction, because the apolar interaction is strengthened with the stabilization of the surrounding water structure.     

Roles of Inorganic Nitrogen in Gametophytic Growth and in Initiation and Development of Sporophytic Shoots of Equisetum arvense

The formation of sporophytic shoots, which is induced by treatmentwith benzylaminopurine of gametophyte tissue of Equisetum arvense,can be divided into initiation and developmental phases. Thenitrogen in MS medium was suitable for two phases as well as gametophytic growth, buta reduction in the concentration of available nitrogen was neededfor the development of shoots. ions alone were effective for gametophytic growth and the initiationof sporophytic shoots, but both and ions was required for the developmental phase. (Received February 18, 1992; Accepted April 14, 1992)     

Receptors for modified low-density lipoproteins on human endothelial cells: different recognition for acetylated low-density lipoprotein and oxidized low-density lipoprotein

We examined the uptake pathway of acetylated low-density lipoprotein and oxidatively modified LDL (oxidized LDL) in human umbilical vein endothelial cells in culture. Proteolytic degradation of 125I-labeled Ac-LDL or Ox-LDL in the confluent monolayer of human endothelial cells was time-dependent and showed saturation kinetics in the dose-response relationship, which suggests that their incorporation is receptor-mediated. Cross-competition studies between acetylated LDL and oxidized LDL showed that the degradation of 125I-labeled acetylated LDL was almost completely inhibited by excess amount of unlabeled acetylated LDL, while only partially inhibited by excess unlabeled oxidized LDL. On the other hand, the degradation of 125I-labeled oxidized LDL was equally inhibited by excess amount of either acetylated or oxidized LDL. Cross-competition results of the cell-association assay paralleled the results shown in the degradation assay. These data indicate that human endothelial cells do not have any additional receptors specific only for oxidized LDL. On the contrary, they may have additional receptors, as we previously indicated on mouse macrophages, which recognize acetylated LDL, but not oxidized LDL.     

Atrial natriuretic peptide reduces the basal level of cytosolic free Ca2+ in guinea pig cardiac myocytes

The cytosolic free Ca2+ concentration ([Ca2+]i) was monitored in quiescent atrial and ventricular myocytes isolated from guinea-pig hearts by the fura-2 fluorescence ratio technique. Recombinant human atrial natriuretic peptide (ANP) was found to reduce their basal [Ca2+]i level in a dose-dependent manner. Dibutyryl-cGMP mimicked the effect of ANP. Neither the prior application of caffeine nor removal of extracellular Na+ impaired the ANP effect. ANP had no inhibitory effect on voltage-gated Ca2+ currents measured by a whole-cell patch clamp technique. The ANP-induced [Ca2+]i decrease was abolished by orthovanadate. Thus, it is concluded that ANP reduces the basal [Ca2+]i presumably through the cGMP-mediated activation of the plasma membrane Ca2(+)-pump in cardiac myocytes.     

Identification of a membrane glycoprotein overexpressed in murine lymphoma sublines resistant to cis-diamminedichloroplatinum(II)

A series of murine thymic lymphoma cell sublines was selected in vitro for resistance to cis-diamminedichloroplatinum(II) (CDDP). The level of CDDP resistance correlated with reduced drug accumulation in these cells. A rabbit antiserum was raised against the plasma membrane of a CDDP-resistant subline and used in Western blot analyses. Increased expression of a surface antigen of approximately 200 kDa was observed and found to correlate with the degree of resistance. Further biochemical and immunological studies demonstrated that this is a plasma membrane glycoprotein. However, it is different from the multidrug resistance-associated P-glycoprotein with a molecular weight of about 170,000. We have called this unique CDDP resistance-associated membrane protein CPR-200.