Calma y revuelta : Teorías solipsistas del relato

Este ensayo pretende llamar la atención, siguiendo especialmente a Jean-Marc Ferry en Les Puissances de l'expérience: essai sur l'identité contemporaine (1991: 103 y ss), acerca de cómo una buena parte de la teoría contemporánea sobre la narración ha quedado substraída al refugio solipsista de las identidades personales, negándose de ese modo para el relato la posibilidad de jugar un papel determinante en los debates públicos. Estos dogmatismos de la facticidad han acuñado dos formas que, simplificando demasiado, podemos nombrar como conservadoras y progresistas. En el primer caso, se trata de teorías que ponen en el centro de sus reflexiones la autoridad de la tradición en el seno de una comunidad lingüística y literaria que se forja a sí misma, sobre la base de una hermenéutica de sus propios valores (Ricoeur, MacIntyre); en el segundo, se trata de las subjetividades en revuelta que han elegido como mecanismo de emancipación el refugio en la vida psíquica por encima de la racionalidad contenida en el mundo de la acción (Kristeva)

Calma y revuelta : Teorías solipsistas del relato

Este ensayo pretende llamar la atención, siguiendo especialmente a Jean-Marc Ferry en Les Puissances de l'expérience: essai sur l'identité contemporaine (1991: 103 y ss), acerca de cómo una buena parte de la teoría contemporánea sobre la narración ha quedado substraída al refugio solipsista de las identidades personales, negándose de ese modo para el relato la posibilidad de jugar un papel determinante en los debates públicos. Estos dogmatismos de la facticidad han acuñado dos formas que, simplificando demasiado, podemos nombrar como conservadoras y progresistas. En el primer caso, se trata de teorías que ponen en el centro de sus reflexiones la autoridad de la tradición en el seno de una comunidad lingüística y literaria que se forja a sí misma, sobre la base de una hermenéutica de sus propios valores (Ricoeur, MacIntyre); en el segundo, se trata de las subjetividades en revuelta que han elegido como mecanismo de emancipación el refugio en la vida psíquica por encima de la racionalidad contenida en el mundo de la acción (Kristeva)

Resolving taxonomic uncertainty in vulnerable elasmobranchs : are the Madeira skate (Raja maderensis) and the thornback ray (Raja clavata) distinct species?

We are grateful to all those who helped with sample collection. This includes the MEDITS survey programme (IEO Mallorca) for Mediterranean samples. Portugal mainland samples were collected under the EU Data Collection Framework (DCF, PNAB). Azores specimens from the Department of Oceanography and Fisheries (DOP) of the University of the Azores (UAc) were collected under the project DEMERSAIS “Monitorização das espécies demersais dos Açores” financed by the Azorean government, and the project DEECON “Unravelling population connectivity for sustainable fisheries in the Deep Sea” project approved by the European Science Foundation (ESF) under the EUROCORES programme (proposal No 06-EuroDEEP-FP-008 & SFRH-EuroDEEP/0002/2007). This study was funded by the UK Natural Environment Research Council (NERC) Oceans 2025 Strategic Research Programme Theme 6 (Science for Sustainable Marine Resources). REB was supported by the Fisheries Society of the British Isles (FSBI), BSP was funded by the Fundação para a Ciência e a Tecnologia, SFRH/BPD/72351/2010 and JL was supported by The Alasdair Downes Marine Conservation Fund.

Human Search for a Target on a Textured Background is Consistent with a Stochastic Model

This research was supported by the James S. McDonnell Foundation (ARH). Early version was supported by EPSRC grants EP/F02553X/1 and EP/D059364/1.

Molecular cloning of a family of xenobiotic-inducible drosophilid cytochrome P450s: Evidence for involvement in host-plant allelochemical resistance

Cytochrome P450s constitute a superfamily of genes encoding mostly microsomal hemoproteins that play a dominant role in the metabolism of a wide variety of both endogenous and foreign compounds. In insects, xenobiotic metabolism (i.e., metabolism of insecticides and toxic natural plant compounds) is known to involve members of the CYP6 family of cytochrome P450s. Use of a 3′ RACE (rapid amplification of cDNA ends) strategy with a degenerate primer based on the conserved cytochrome P450 heme-binding decapeptide loop resulted in the amplification of four cDNA sequences representing another family of cytochrome P450 genes (CYP28) from two species of isoquinoline alkaloid-resistant Drosophila and the cosmopolitan species Drosophila hydei. The CYP28 family forms a monophyletic clade with strong regional homologies to the vertebrate CYP3 family and the insect CYP6 family (both of which are involved in xenobiotic metabolism) and to the insect CYP9 family (of unknown function). Induction of mRNA levels for three of the CYP28 cytochrome P450s by toxic host-plant allelochemicals (up to 11.5-fold) and phenobarbital (up to 49-fold) corroborates previous in vitro metabolism studies and suggests a potentially important role for the CYP28 family in determining patterns of insect–host-plant relationships through xenobiotic detoxification.

A serotonin transporter gene intron 2 polymorphic region, correlated with affective disorders, has allele-dependent differential enhancer-like properties in the mouse embryo

Polymorphic regions consisting of a variable number of tandem repeats within intron 2 of the gene coding for the serotonin transporter protein 5-HTT have been associated with susceptibility to affective disorders. We have cloned two of these intronic polymorphisms, Stin2.10 and Stin2.12, into an expression vector containing a heterologous minimal promoter and the bacterial LacZ reporter gene. These constructs were then used to produce transgenic mice. In embryonic day 10.5 embryos, both Stin2.10 and Stin2.12 produced consistent β-galactosidase expression in the embryonic midbrain, hindbrain, and spinal cord floor plate. However, we observed that the levels of β-galactosidase expression produced by both the Stin2.10 and Stin2.12 within the rostral hindbrain differed significantly at embryonic day 10.5. Our data suggest that these polymorphic variable number of tandem repeats regions act as transcriptional regulators and have allele-dependent differential enhancer-like properties within an area of the hindbrain where the 5-HTT gene is known to be transcribed at this stage of development.

Reprogramming the Cell Cycle for Endoreduplication in Rodent Trophoblast Cells

Differentiation of trophoblast giant cells in the rodent placenta is accompanied by exit from the mitotic cell cycle and onset of endoreduplication. Commitment to giant cell differentiation is under developmental control, involving down-regulation of Id1 and Id2, concomitant with up-regulation of the basic helix-loop-helix factor Hxt and acquisition of increased adhesiveness. Endoreduplication disrupts the alternation of DNA synthesis and mitosis that maintains euploid DNA content during proliferation. To determine how the mammalian endocycle is regulated, we examined the expression of the cyclins and cyclin-dependent kinases during the transition from replication to endoreduplication in the Rcho-1 rat choriocarcinoma cell line. We cultured these cells under conditions that gave relatively synchronous endoreduplication. This allowed us to study the events that occur during the transition from the mitotic cycle to the first endocycle. With giant cell differentiation, the cells switched cyclin D isoform expression from D3 to D1 and altered several checkpoint functions, acquiring a relative insensitivity to DNA-damaging agents and a coincident serum independence. The initiation of S phase during endocycles appeared to involve cycles of synthesis of cyclins E and A, and termination of S was associated with abrupt loss of cyclin A and E. Both cyclins were absent from gap phase cells, suggesting that their degradation may be necessary to allow reinitiation of the endocycle. The arrest of the mitotic cycle at the onset of endoreduplication was associated with a failure to assemble cyclin B/p34cdk1 complexes during the first endocycle. In subsequent endocycles, cyclin B expression was suppressed. Together these data suggest several points at which cell cycle regulation could be targeted to shift cells from a mitotic to an endoreduplicative cycle.

Three-dimensional structure of poliovirus receptor bound to poliovirus

Poliovirus initiates infection by binding to its cellular receptor (Pvr). We have studied this interaction by using cryoelectron microscopy to determine the structure, at 21-Å resolution, of poliovirus complexed with a soluble form of its receptor (sPvr). This density map aided construction of a homology-based model of sPvr and, in conjunction with the known crystal structure of the virus, allowed delineation of the binding site. The virion does not change significantly in structure on binding sPvr in short incubations at 4°C. We infer that the binding configuration visualized represents the initial interaction that is followed by structural changes in the virion as infection proceeds. sPvr is segmented into three well-defined Ig-like domains. The two domains closest to the virion (domains 1 and 2) are aligned and rigidly connected, whereas domain 3 diverges at an angle of ≈60°. Two nodules of density on domain 2 are identified as glycosylation sites. Domain 1 penetrates the “canyon” that surrounds the 5-fold protrusion on the capsid surface, and its binding site involves all three major capsid proteins. The inferred pattern of virus–sPvr interactions accounts for most mutations that affect the binding of Pvr to poliovirus.

Structural invariance of constitutively active and inactive mutants of Acanthamoeba myosin IC bound to F-actin in the rigor and ADP-bound states

The three single-headed monomeric myosin I isozymes of Acanthamoeba castellanii (AMIs)—AMIA, AMIB, and AMIC—are among the best-studied of all myosins. We have used AMIC to study structural correlates of myosin’s actin-activated ATPase. This activity is normally controlled by phosphorylation of Ser-329, but AMIC may be switched into constitutively active or inactive states by substituting this residue with Glu or Ala, respectively. To determine whether activation status is reflected in structural differences in the mode of attachment of myosin to actin, these mutant myosins were bound to actin filaments in the absence of nucleotide (rigor state) and visualized at 24-Å resolution by using cryoelectron microscopy and image reconstruction. No such difference was observed. Consequently, we suggest that regulation may be affected not by altering the static (time-averaged) structure of AMIC but by modulating its dynamic properties, i.e., molecular breathing. The tail domain of vertebrate intestinal brush-border myosin I has been observed to swing through 31° on binding of ADP. However, it was predicted on grounds of differing kinetics that any such effects with AMIC should be small [Jontes, J. D., Ostap, E. M., Pollard, T. D. & Milligan, R. A. (1998) J. Cell Biol. 141, 155–162]. We have confirmed this hypothesis by observing actin-associated AMIC in its ADP-bound state. Finally, we compared AMIC to brush-border myosin I and AMIB, which were previously studied under similar conditions. In each case, the shape and angle of attachment to F-actin of the catalytic domain is largely conserved, but the domain structure and disposition of the tail is distinctively different for each myosin.

Confidential inquiry into quality of care before admission to intensive care

Objective: To examine the prevalence, nature, causes, and consequences of suboptimal care before admission to intensive care units, and to suggest possible solutions.

Translocation pathway of protein substrates in ClpAP protease

Intracellular protein degradation, which must be tightly controlled to protect normal proteins, is carried out by ATP-dependent proteases. These multicomponent enzymes have chaperone-like ATPases that recognize and unfold protein substrates and deliver them to the proteinase components for digestion. In ClpAP, hexameric rings of the ClpA ATPase stack axially on either face of the ClpP proteinase, which consists of two apposed heptameric rings. We have used cryoelectron microscopy to characterize interactions of ClpAP with the model substrate, bacteriophage P1 protein, RepA. In complexes stabilized by ATPγS, which bind but do not process substrate, RepA dimers are seen at near-axial sites on the distal surface of ClpA. On ATP addition, RepA is translocated through ≈150 Å into the digestion chamber inside ClpP. Little change is observed in ClpAP, implying that translocation proceeds without major reorganization of the ClpA hexamer. When translocation is observed in complexes containing a ClpP mutant whose digestion chamber is already occupied by unprocessed propeptides, a small increase in density is observed within ClpP, and RepA-associated density is also seen at other axial sites. These sites appear to represent intermediate points on the translocation pathway, at which segments of unfolded RepA subunits transiently accumulate en route to the digestion chamber.