Posttranslational control of membrane-skeleton (ankyrin and alpha beta- spectrin) assembly in early myogenesis

Adult chicken skeletal muscle cells express polypeptides that are antigenically related to alpha-spectrin (Mr 240,000) and beta-spectrin (Mr 220,000-225,000), the major components of the erythrocyte membrane- skeleton, and to ankyrin (Mr 237,000; also termed goblin in chicken erythrocytes), which binds spectrin to the transmembrane anion transporter in erythrocytes. Comparative immunoblotting of SDS- solubilized extracts of presumptive myoblasts and fully differentiated myotubes cultured in vitro demonstrated that there is a dramatic accumulation of ankyrin and alpha- and beta-spectrin during myogenesis and a concomitant switch in the subunit composition of spectrin from alpha gamma to alpha beta. Analysis of early time points in myogenesis (12-96 h) revealed that these changes occur shortly after the main burst of cell fusion. To determine the temporal relationship between cell fusion and the accumulation of ankyrin and alpha- and beta- spectrin, we treated presumptive myoblasts with 2 mM EGTA, which resulted in the complete inhibition of cell fusion. The incorporation of [35S]methionine into total protein and, specifically, into alpha-, gamma-, and beta-spectrin remained the same in EGTA-treated and control cells. Analysis by immunoblotting of the amounts of ankyrin and alpha- and beta-spectrin in fusion-blocked cells revealed that there was no effect on accumulation for the first 19 h. However, there was then a dramatic cessation in their accumulation, and thereafter, the amount of each protein at steady state remained constant. Upon release from the EGTA block, the cells fused rapidly (less than 11 h), and the accumulation of ankyrin and alpha- and beta-spectrin was reinitiated after a lag period of 3-5 h at a rate similar to that in control cells. The inhibition in the accumulation of newly synthesized ankyrin, alpha- spectrin, and beta-spectrin in EGTA-treated myoblasts was not characteristic of all structural proteins, since the accumulation of the muscle-specific intermediate filament protein desmin was the same in control and fusion-blocked cells. These results show that in myogenesis, the synthesis of ankyrin and alpha- and beta-spectrin and their accumulation as a complex, although concurrent, are not coupled events. We hypothesize that the extent of assembly of these components of the membrane-skeleton in muscle cells is determined by a control mechanism(s) operative at the posttranslational level that is triggered near the time of cell fusion and the onset of terminal differentiation

A visible hand: the Fed's involvement in the check payments system

It is common knowledge that the Federal Reserve System was originally set up to provide the nation with a stable currency and a sound banking system. Less well known, however, is why the Fed was given an operating role in the nation's payments system. In this article, James N. Duprey and Clarence W. Nelson describe the problems of the check payments system before the Fed was created, suggest reasons why the private sector was unable to resolve them, and indicate how the framers of the Federal Reserve Act intended to have the Fed resolve them. Duprey and Nelson argue that while a unified national check-clearing system clearly would have been more efficient than the fragmented system that then existed, both private and Fed initiatives to reform the payments system met strong resistance from the banking community -- especially smaller nonpar banks. These banks were reluctant to give up their profitable practice of nonpar payment (paying less than the written amount of checks drawn on their accounts). Duprey and Nelson conclude that, despite the banking community's resistance, the Fed did improve the efficiency of the check payments system.Clearinghouses (Banking) ; Check collection systems ; Federal Reserve System - History ; Banks and banking - History

Avian lens spectrin: subunit composition compared with erythrocyte and brain spectrin

Chicken lens spectrin is composed predominantly of equimolar amounts of two polypeptides with solubility properties similar, but not identical, to erythrocyte spectrin. The larger polypeptide, Mr 240,000 (lens alpha- spectrin), co-migrates with erythrocyte and brain alpha-spectrin on one- and two-dimensional SDS polyacrylamide gels and cross-reacts with antibodies specific for chicken erythrocyte alpha-spectrin; the smaller polypeptide, Mr 235,000 (lens gamma-spectrin), co-migrates with brain gamma-spectrin and does not cross-react with either the alpha-spectrin antibodies specific for chicken erythrocyte beta-spectrin. Minor amounts of polypeptides antigenically related to erythrocyte beta- spectrin with a greater electrophoretic mobility than lens gamma- spectrin are also detected in lens. The equimolar ratio of lens alpha- and gamma-spectrin is invariantly maintained during the extraction of lens plasma membranes under different conditions, or after immunoprecipitation of whole extracts of lens with erythrocyte alpha- spectrin antibodies. Two-dimensional peptide mapping reveals that whereas alpha-spectrins from chicken erythrocytes, brain, and lens are highly homologous, the gamma-spectrins, although related, have some cell-type-specific peptides and are substantially different from erythrocyte beta-spectrin. Thus, the expression of cell-type-specific gamma- and beta-spectrins may be the basis for the assembly of a spectrin-plasma membrane complex whose molecular composition is tailored to the functional requirements of the particular cell-type

Comparison of Wechsler Memory Scale–Fourth Edition (WMS–IV) and Third Edition (WMS–III) dimensional structures: Improved ability to evaluate auditory and visual constructs

Dimensional structures underlying the Wechsler Memory Scale–Fourth Edition (WMS–IV) and Wechsler Memory Scale–Third Edition (WMS–III) were compared to determine whether the revised measure has a more coherent and clinically relevant factor structure. Principal component analyses were conducted in normative samples reported in the respective technical manuals. Empirically supported procedures guided retention of dimensions. An invariant two-dimensional WMS–IV structure reflecting constructs of auditory learning/memory and visual attention/memory (C1 = .97; C2 = .96) is more theoretically coherent than the replicable, heterogeneous WMS–III dimension (C1 = .97). This research suggests that the WMS–IV may have greater utility in identifying lateralized memory dysfunction

Andrés Laguna in Papal Rome: the documents of the Mozoncillo ecclesiastical benefice

The article renders public and presents the archival documents, hitherto unpublished, regarding an ecclesiastical benefice in the town of Mozoncillo, which Andrés Laguna obtained in 1548. Through the said benefice, obtained, very likely, through the intervention of an important Spanish prelate, Laguna strove to obtain influence and legitimacy for himself and his family in his hometown and contribute to the eradication of the "stain" of his family's converso origins. The documents attest to an important and decisive moment in Laguna's life and career

Orbital transfer vehicle concept definition and system analysis study, 1985. Volume 3: System and program trades

The key system and program trade studies performed to arrive at a preferred Orbital Transfer Vehicle (OTV) system concept and evolutionary approach to the acquisition of the requisite capabilites is documented. These efforts were expanded to encompass a Space Transportation Architecture Study (STAS) mission model and recommended unmanned cargo vehicle. The most important factors affecting the results presented are the mission model requirements and selection criteria. The reason for conducting the OTV concept definition and system analyses study is to select a concept and acquisition approach that meets a delivery requirement reflected by the mission model

From the Atlantic to the Mediterranean: the voyage of Rui Teixeira to the Italian Peninsula from Portugal

De l’Atlàntic al Mediterrani: el viatge de Rui Teixeira a la península italiana des de Portugal L’article considera l’interès que tenien les comunitats mercantils i a la diàspora a l’hora de cercar refugi segur a la Itàlia moderna a partir de l’exemple delmercader Rui Teixeira, que l’any 1593 va ser convidat tant per Roma com pel Gran Ducat de la Toscana a establir-se a Itàlia amb la seva família. Atesa laseva condició de resident a Portugal i al Brasil durant molts anys, va aprofitar l’experiència americana per obtenir la invitació per sortir de Portugal juntament amb la seva família. Aquest fet suggereix que pertànyer a una minoria mòbil amb vincles comercials que travessaven l’Atlàntic despertava un interès pel món atlàntic que ja hi havia, especialment a la Toscana de finals del segle XVI.The article deals with the interest that mercantile and diasporic communities had in securing safe havens for themselves in early modern Italy through the example of the Portuguese New Christian merchant Rui Teixeira, who in 1593 managed to be invited by both Rome and Tuscany. In his condition as a longtime resident of Portugal and Brazil, he cultivated interest about himself to secure his invitation to leave Portugal along with his family. This suggests that belonging to a mobile minority with commercial links that criss-crossed the Atlantic fed into an existing interest in the Atlantic world, especially in Tuscany, at the end of the sixteenth century.Del Atlántico al Mediterráneo: el viaje de Rui Teixeira a la península italiana desde PortugalEl artículo considera el interés que tenían las comunidades mercantiles y diaspóricas a la hora de asegurarse refugio seguro en la Italia moderna a través del ejemplo del mercader Rui Teixeira quien, en 1593, fue invitado tanto por Roma como por el Gran Ducado de la Toscana para afincarse en Italia junto a sufamilia. Dada su condición de residente en Portugal y Brasil durante largos años, aprovechó la experiencia americana para asegurarse la invitación parasalir de Portugal junto con su familia. Esto sugiere que el hecho de pertenecer a una minoría móvil con vínculos comerciales que surcaban el Atlántico alimentaba un interés ya existente por el mundo atlántico, especialmente en la Toscana de finales del siglo XVI