Syntheses of Female Sex Pheromone Analogues of the German Cockroach and Their Biological Activity

Several analogues of 3,1l-dimethyl-2-nonacosanone, one component of the sex pheromone of the German cockroach, were synthesized. Their activity for the male to raise his wings was assayed and summerized in Tables I and II.     

Mutational analysis of an actin-binding site of cofilin and characterization of chimeric proteins between cofilin and destrin.

Cofilin and destrin are two related low molecular weight mammalian actin-binding proteins. Cofilin is an F-actin side-binding and pH-dependent actin-depolymerizing protein, and destrin is a pH-independent actin-depolymerizing protein. We have introduced a few point mutations within an actin-binding sequence of cofilin. Biochemical analyses of these mutant proteins have clearly shown that Lys112 and Lys114 of cofilin are crucially but differently involved in its interaction with actin and phosphatidylinositol 4,5-bisphosphate. This is the first example among actin-binding proteins whose point mutations inactivate their interaction with actin in vitro. We have also made and characterized a series of chimeric proteins between cofilin and destrin to identify the regions responsible for the pH dependence and the F-actin side binding activity of cofilin. Our results suggest that a central region consisting of 42 amino acid residues and a carboxyl-terminal quarter of cofilin are both involved in regulation of the pH-dependent actin depolymerizing activity and the activity to bind along F-actin.     

Phase relationships of an equivalent mixture of sulfated polyvinyl alcohol and aminoacetalyzed polyvinyl alcohol in microsalt aqueous solution

A new type of polymer salt was prepared from an equivalent mixture of partly sulfated polyvinyl alcohol (polyanion, Q^?) and partly aminoacetalyzed polyvinyl alcohol (polycation, P⁺). With respect to a three-component system composed of this polymer salt (P⁺Q^?), water, and a microsalt (K⁺A^?), phase relationships, as represented by complex coacervation, were investigated. Experimental results were discussed according to a theoretical equation for the free energy of mixing derived by taking into account the entropy and enthalpy contributions as ascribed for non-ionic polymer solution, and the electrostatic free energy expression as derived by Voorn.     

Purification of Isomeric Forms of Acyl-[Acyl-Carrier-Protein]:Glycerol-3-Phosphate Acyltransferase from Greening Squash Cotyledons

Acyl-[acyl-carrier-protein]:glycerol-3-phosphate acyltransferasewas purified from greening cotyledons of squash (Cucurbita moschataDuch. cv. Shirakikuza) by [acyl-carrier proteinj-affinity columnchromatography in addition to conventional purification procedures.Three isomeric forms designated as ATI, AT2 and AT3 were found:ATI was separated from the other two isomeric forms by anion-exchangecolumn chromatography, whereas AT2 and AT3 were separated byhydroxyapatite column chromatography. ATI was purified 24,000-foldon the basis of specific activity; AT2 and AT3 were purifiedto single components after 40,000- and 32,000-fold purification,respectively. The isoelectric points of ATI, AT2 and AT3 at4?C were 6.6, 5.6 and 5.5, respectively. Gel-filtration columnchromatography and sodium dodecylsulfate gel electrophoresisindicated that the respective isomeric forms were monomers withapparent molecular masses of about 30 kDa, 40 kDa and 40 kDa.The isoelectric focusing of the chloroplast stroma proteinsfrom the squash cotyledons suggested that ATI, AT2 and AT3 areall localized in the chloroplast stroma. ¹ On leave from Institut f?r Allgemeine Botanik, Universit?tHamburg, Ohnhorststra?e 18, 2000 Hamburg, F.R.G. (Received April 17, 1987; Accepted June 12, 1987)     

Photocontrol of immobilized trypsin activity

Trypsin was coupled on an agarose gel which was modified with a spiropyran compound. The trypsin–spiropyran (agarose) gel showed reverse photochromism. The activity of the trypsin–spiropyran gel in the dark was 12% of that of native trypsin, and it was higher than that under visible light. The apparent Michaelis constant of the trypsin–spiropyran gel in the dark was larger than that under visible light. On the other hand, the maximum velocity in the dark was higher than that under visible light. The optimum pH of the trypsin–spiropyran gel in the dark was the same as that under visible light. Immobilized trypsin was stable in the pH range from 3 to 9. The trypsin–spiropyran gel was more stable against heat than the native trypsin.     

Thrombopoietin/MPL signaling regulates hematopoietic stem cell quiescence and interaction with the osteoblastic niche

Maintenance of hematopoietic stem cells (HSCs) depends on interaction with their niche. Here we show that the long-term (LT)-HSCs expressing the thrombopoietin (THPO) receptor, MPL, are a quiescent population in adult bone marrow (BM) and are closely associated with THPO-producing osteoblastic cells. THPO/MPL signaling upregulated beta1-integrin and cyclin-dependent kinase inhibitors in HSCs. Furthermore, inhibition and stimulation of THPO/MPL pathway by treatments with anti-MPL neutralizing antibody, AMM2, and with THPO showed reciprocal regulation of quiescence of LT-HSC. AMM2 treatment reduced the number of quiescent LT-HSCs and allowed exogenous HSC engraftment without irradiation. By contrast, exogenous THPO transiently increased quiescent HSC population and subsequently induced HSC proliferation in vivo. Altogether, these observations suggest that THPO/MPL signaling plays a critical role of LT-HSC regulation in the osteoblastic niche.     

Insulin-like growth factor I stimulates recovery of bone lost after a period of skeletal unloading.

IGF-I stimulates osteoblast proliferation, bone formation, and increases bone volume in normal weight-bearing animals. During skeletal unloading or loss of weight bearing, bone becomes unresponsive to the anabolic effects of insulin-like growth factor I (IGF-I). To determine whether skeletal reloading after a period of unloading increases bone responsiveness to IGF-I, we examined bone structure and formation in response to IGF-I under different loading conditions. Twelve-week-old rats were divided into six groups: loaded (4 wk), unloaded (4 wk), and unloaded/reloaded (2/2 wk), and treated with IGF-I (2.5 mg x kg(-1) x day(-1)) or vehicle during the final 2 wk. Cortical bone formation rate (BFR), cancellous bone volume and architecture in the secondary spongiosa (tibia and vertebrae), and total volume and calcified volume in the primary spongiosa (tibia) were assessed. Periosteal BFR decreased during unloading, remained low during reloading in the vehicle-treated group, but was dramatically increased in IGF-I-treated animals. Cancellous bone volume decreased with unloading and increased with reloading, but the effect was exaggerated in the tibia of IGF-I-treated animals. Total and calcified volumes in the primary spongiosa decreased during unloading in the vehicle-treated animals. IGF-I treatment prevented the loss in volume. These data show that reloading after a period of skeletal unloading increases bone responsiveness to IGF-I, and they suggest that IGF-I may be of therapeutic use in patients who have lost bone as a consequence of prolonged skeletal disuse.