An Arabidopsis gene regulatory network for secondary cell wall synthesis.

The plant cell wall is an important factor for determining cell shape, function and response to the environment. Secondary cell walls, such as those found in xylem, are composed of cellulose, hemicelluloses and lignin and account for the bulk of plant biomass. The coordination between transcriptional regulation of synthesis for each polymer is complex and vital to cell function. A regulatory hierarchy of developmental switches has been proposed, although the full complement of regulators remains unknown. Here we present a protein-DNA network between Arabidopsis thaliana transcription factors and secondary cell wall metabolic genes with gene expression regulated by a series of feed-forward loops. This model allowed us to develop and validate new hypotheses about secondary wall gene regulation under abiotic stress. Distinct stresses are able to perturb targeted genes to potentially promote functional adaptation. These interactions will serve as a foundation for understanding the regulation of a complex, integral plant component.

Cell division, one-carbon metabolism and methionine synthesis in a metK-deficient Escherichia coli mutant, and a role for MmuM.

An E. coli K-12 mutant deficient in S-adenosylmethionine (SAM) synthesis, i.e ΔmetK, but expressing a rickettsial SAM transporter, can grow in glucose minimal medium if provided with both SAM and methionine. It uses the externally provided (R)-enantiomer of SAM as methyl donor to produce most but not all of its methionine, by methylation of homocysteine catalysed by homocysteine methyltransferase (MmuM). The ΔmetK cells are also altered in growth and are twice as long as those of the parent strain. When starved of SAM, the mutant makes a small proportion of very long cells suggesting a role of SAM and of methylation in the onset of crosswall formation.

Freud's unfortunates: reflections on haunted beings who know the disaster of severe trauma.

The forms of dissociation are multiplex and must include a type of dissociation that represents human beings' fundamental inability to process and represent severe trauma. This article posits a form of dissociation--resulting from trauma--linked to disastrous knowledge, signifying a person's incapacity to use language and symbol to organize the core of the traumatic experience in terms of semantically structured self-in-relation. Catastrophic knowledge of severe trauma is unexperienced experience that paradoxically stands for an indescribable core of an event that undermines self-in-relation and the concomitant capacities for language, narrative, and knowledge. This irretrievable unexperienced experience continues to haunt despite a person's recovery. This perspective points to the limits of therapy and the necessity to establish and maintain a relationship of trust and loyalty in the face of an event that annihilates self-in-relation. Included in this work are the therapeutic tasks of serving as a witness and a container of the unnamable horror.

The birth of reality: psychoanalytic developmental considerations.

In this article, utilizing an emended version of Winnicott's notion of transitional objects and recent parent-infant research, the author offers a perspective on the development of individuals' experience of being alive and real in relation to objects and persons. Primary transitional objects, which represent parent-infant interactions, facilitate the infant's transition from early undifferentiated, bodily, and global experiences of being real and alive to the infant's yoking and extending these subjective organizations to recognized not-me objects. Secondary transitional objects make their appearance when the child begins to acquire the capacities for self-reflexivity, symbolization, and language. These objects provide the child with opportunities to gain confidence and courage in extending, yoking, and making use of his/her subjective experiences of being alive and real in relation to cultural symbols and rituals. More importantly, secondary transitional objects are paths toward mutual recognition, acceptance, and sharing experiences of being alive and real.

Responsibility and evil imagination.

In this Niebuhrian perspective on hostile and violent discourse the author utilizes H. R. Niebuhr's fourfold notion of responsibility and his concept of evil imagination to examine relations marred by protracted hostility toward hated "other" or "others." The author argues that violent and hostile discourse manifests a particular form of responsibility whereby persons expressing hostility toward hated "others" construct, by way of negative representations, maligned histories and identities for the "other" and at the same time construct an idealized or glorified history and identity for themselves. These positive and negative representations and histories, then, are utilized to answer questions regarding interpretation, accountability, and solidarity. Niebuhr's concept of evil imagination is employed to hypothesize about the intransigence of this form of responsibility and to suggest reasons why elevated and maligned representations, identities, and histories are, more often than not, inextricably and tragically linked.

Orthogonal expansions: their applicability to signal extraction in electrophysiological mapping data.

The applicability of orthogonal expansions (singular-value decomposition, Karhunen-Loève transform and principal-component analysis) for the purpose of identifying source distributions associated with definite electrophysiological events in the heart and brain is explored with a current dipole source model. By definition, the expansion eigenvectors are orthogonal, and as such will extract the features of one specific source only if all other secondary signals are orthogonal to that first source. The number of significant eigenvectors can be related to the number of original components forming a signal, but there is not a one-to-one correspondence between these eigenvectors and the individual components. Furthermore, many eigenvectors may be needed to faithfully represent even a single source, if that source is nonstationary. We conclude that generally it would be inappropriate to ascribe any physiological significance to the data resulting from such expansions.

The effect of torso geometry on magnetocardiographic isofield maps.

Using a computer model of a realistically shaped human torso with lungs and intraventricular blood masses, we have assessed how torso geometry and composition affect the extracorporal magnetic field produced by a current dipole in the centre of the ventricular mass. The magnetic induction vector B arising from the dipole has been calculated at points of a precordial measuring grid and the influence of boundaries has been assessed qualitatively, by comparing contour maps of the B component normal to the torso's frontal plane. We found that the maps reflected relatively faithfully the underlying dipolar source for the homogeneous torso and even for the torso with lungs. However, the intraventricular blood masses caused a noticeable rotation of the maps' extrema. Both lungs and blood masses tended to swing the distribution towards the distribution that would have been caused by a dipole oriented along the anatomical axis of the heart.

Paragonimus mexicanus: an antigenic analysis.

El extracto antigenico obtenido de adultos de la especie Paragonimus mexicanus se analiso por inmunodifusion doble y por inmunoelectroforesis empleando el suero hi perinmune de un conejo y los sueros de gatos infectados experimentalmente. Por inmunoelectroforesis se formaron de una banda de identid entre el suero de conejo y los de los gatos. El extracto antigenico contiene trece proteinas, segun fue revelado en un gel de poliacrilamida con dodecil sulfato de sodio

Apollo 16 Geochemical X-ray Fluorescence Experiment: Preliminary Report.

The lunar surface was mapped with respect to magnesium, aluminum, and silicon as aluminum/ silicon and magnesium/ silicon intensity ratios along the projected ground tracks swept out by the orbiting Apollo 16 spacecraft. The results confirm the observations made during the Apollo 15 flight and provide new data for a number of features not covered before. The data are consistent with the idea that the moon has a widespread differentiated crust (the highlands). The aluminum/ silicon and magnesium/ silicon concentration ratios correspond to those for anorthositic gabbros through gabbroic anorthosites or feldspathic basalts. The x-ray results suggest the occurrence of this premare crust or material similar to it at the Descartes landing site.

Apollo 15 Geochemical X-ray Fluorescence Experiment: Preliminary Report.

Although only part of the information from the x-ray fluorescence geochemical experiment has been analyzed, it is clear that the experiment was highly successful. Significant compositional differences among and possibly within the maria and highlands have been detected. When viewed in the light of analyzed lunar rocks and soil samples, and the data from other lunar orbital experiments (in particular, the Apollo 15 gamma-ray spectroscopy experiment), the results indicate the existence of a differential lunar highland crust, probably feldspathic. This crust appears to be related to the plagioclase-rich materials previously found in the samples from Apollo 11, Apollo 12, Apollo 14, Apollo 15, and Luna 16.