Bringing the State Back In

Book reviewed in this article:
Culture and Society in New Order Indonesia . Virginia Matheson Hooker , ed. Kuala Lumpur: Oxford University Press, 1993. 302 pp. Dissociated Identities: Ethnicity, Religion, and Class in an Indonesian Society . Rita Smith Kipp. Ann Arbor: University of Michigan Press, 1993. 320 pp.     

Sympathetic and sensory innervation of the urinary tract in young adult and aged rats: a semi-quantitative histochemical and immunohistochemical study

Summary The sympathetic innervation of the urinary tract of young adult (4 months) and aged (24+ months) rats has been examined by glyoxylic acid-induced fluorescence for the detection of noradrenaline and by immunofluorescence using antisera against tyrosine hydroxylase (TH) and neuropeptide Y (NPY). Immunostaining for calcitonin gene-related peptide (CGRP), known to be present in pelvic sensory nerves, was also performed. Semi-quantitative estimations of nerve densities were made of noradrenergic and peptidergic fibres innervating the smooth musculature of the ureter, bladder and urethra, and of the urinary tract vasculature. In the aged rats the overall patterns of innervation remained unchanged. However, with the exception of the vesical vasculature, the density of noradrenergic innervation decreased as did the intensity of histofluorescence. A similar pattern of results was observed by TH and NPY immunofluorescence. The results present evidence for a diminution in the sympathetic control of the urinary tract in aged rats. The pattern and density of CGRP-immunoreactive nerves was unchanged in the aged animals suggesting that pelvic visceral sensory innervation is more resistant to the effects of advancing age.     

Genomic structure,expression and evolution of the alfalfa aspartate aminotransferase genes

Genomic clones encoding two isozymes of aspartate aminotransferase (AAT) were isolated from an alfalfa genomic library and their DNA sequences were determined. The AAT1 gene contains 12 exons that encode a cytosolic protein expressed at similar levels in roots, stems and nodules. In nodules, the amount of AAT1 mRNA was similar at all stages of development, and was slightly reduced in nodules incapable of fixing nitrogen. The AAT1 mRNA is polyadenylated at multiple sites differing by more than 250 bp. The AAT2 gene contains 11 exons, with 5 introns located in positions identical to those found in animal AAT genes, and encodes a plastid-localized isozyme. The AAT2 mRNA is polyadenylated at a very limited range of sites. The transit peptide of AAT2 is encoded by the first two and part of the third exon. AAT2 mRNA is much more abundant in nodules than in other organs, and increases dramatically during the course of nodule development. Unlike AAT1, expression of AAT2 is significantly reduced in nodules incapable of fixing nitrogen. Phylogenetic analysis of deduced AAT proteins revealed 4 separate but related groups of AAT proteins; the animal cytosolic AATs, the plant cytosolic AATs, the plant plastid AATs, and the mitochondrial AATs.     

The ecological significance of nickel hyperaccumulation: a plant chemical defense

Nickel hyperaccumulating plants have more than 1000 mg Ni kg^–1 dry weight when grown on nickel-bearing soils. We hypothesized that Ni hyperaccumulation could serve as a chemical defense against herbivores In feeding experiments with potential insect herbivores and Ni hyperaccumulating plants, only those inseets fed leaves from plants grown on non-nickel-bearing soil survived or showed a weight gain. Among chemical parameters measured, only Ni content of plants was sufficient to explain this result. When subjected to herbivory by lepidopteran larvae, plants grown on Ni-amended soil showed greater survival and yield than plants on unamended soil. Ni hyperaccumulation may be an effective plant chemical defense against herbivores because of its high lethality, apparent low cost, and broad spectrum of toxicity.     

The evolutionary origin of the 35 kb circular DNA of Plasmodium falciparum: new evidence supports a possible rhodophyte ancestry

In common with other Apicomplexan parasites, Plasmodium falciparum carries two extrachromosomal DNAs, one of which, the 6 kb element, is undoubtedly mitochondrial. The second, generally referred to as the 35 kb circle, is of unknown provenance, but the nature and organization of its genetic content makes a mitochondrial association unlikely and the molecule has features reminiscent of plastid genomes. We now report the occurrence on the circle of an open reading frame specifying a predicted 470 amino acid protein that shares more than 50% identity with a gene currently known only on the plastome of red algae. This high degree of conservation confirms the 35 kb circle's plastid ancestry, and we speculate that it may have originated from the rhodoplast of an ancient red algal endosymbiont in the progenitor of the Apicomplexa.     

Illuminant precompensation for texture discrimination using filters

 Texture-discrimination algorithms have often been tested on images containing either mosaics of synthetic textures or artificially created mosaics of real textures – in any case, images in which most of the changes in intensity can be ascribed to the textures themselves. However, real images are not formed like this and may contain steep gradations in intensity which have nothing to do with local texture, such as those caused by incident shadows. A texture discrimination algorithm based on linear filters can fail in the presence of these strong gradations, as they may easily contain an order of magnitude more energy than the gradations in intensity due to texture in the image per se. In these cases, the mechanism may become responsive only to strong luminance effects, and not to texture. I have found that good performance on natural images containing texture can only be obtained from a filter-based texture detection scheme if it includes a stage which attempts to bring large intensity gradients within bounds. The exact nature of the best precompensator appears to depend somewhat on the way the filter outputs are processed. The fit to psychophysical data and the implications for more detailed models of human texture processing will be discussed. Received: 3 May 1993/Accepted in revised form: 7 June 1993     

Is there an energy conservation “system” in brain that protects against the consequences of energy depletion?

A poorly understood marked decrease (circa 50% of control) in local cerebral glucose utilization is caused by sublethal doses of NaCN. The decrease is global, occurring in essentially all brain regions and is entirely reversible within hours, leaving no obvious pathology. This event is not unique to NaCN in so far as a strikingly similar pattern of decreased glucose utilization occus with some other toxins. Nor can it be attributed to a direct action of NaCN since local application by microdialysis to the striatum produces a global depression. These results imply that some widely distributed system or substance is involved. We speculate the existence of a system possibly related to the reticular activating system that senses a fall in energy production and acts globally to make cells quiescent and thus would give some protection from excitotoxic driven damage.Special issue dedicated to Dr. Sidney Ochs.     

Volatile anesthetics inhibit NMDA-stimulated45Ca uptake by rat brain microvesicles

We have previously shown that volatile anesthetics inhibit glutamate-stimulated [³H]MK-801 binding to the ionophore of NMDA receptor complexes in rat brain. In the present study, we examined the influence of enflurane and halothane on NMDA-stimulated⁴⁵Ca uptake by a microvesicle fraction isolated from rat brain. NMDA stimulated⁴⁵Ca uptake (30 sec) by rat brain microvesicles by up to 70% with an EC₅₀ of 1.4±0.5 M. The NMDA-stimulated⁴⁵Ca uptake was inhibited by MK-801 and D-AP-5 with IC₅₀'s of 10 M. Enflurane and halothane inhibited⁴⁵Ca uptake stimulated by 100 M NMDA by as much as 60–80% with IC₅₀'s of 0.2–0.3 mM, concentrations achieved during routine clinical use. Basal⁴⁵Ca uptake measured in the absence of agonist was not affected by the anesthetics. Glycine did not affect the level of NMDA-stimulated⁴⁵Ca uptake, but markedly reduced the inhibition of uptake caused by enflurane and halothane. Preincubation of microvesicles with NMDA resulted in a desensitization of NMDA-stimulated⁴⁵Ca uptake, with a t_1/2 of 20 sec. Enflurane and halothane diminished both the extent and rate of development of this desensitization, as did glycine. These findings support the idea that volatile anesthetic interference with neurotransmission at NMDA receptor complexes contributes to the development of the anesthetic state.     

The role of tyrosine-114 in the enzymatic activity of the Shiga-like toxin I A-chain

Shiga-like toxin I (SLT-I), the potent cytotoxin produced by certain pathogenic strains of Escherichia coli, is a member of a burgeoning family of ribosome-inactivating proteins (RIPS), which share common structural and mechanistic features. The prototype of the group is the plant toxin ricin. Recently we proposed a structural model for the Slt-IA active site, based in part on the known geometry of the enzymatic subunit of the ricin toxin. The model places three aromatic residues within the putative Slt-IA active site cleft: tyrosine 77, tyrosine 114, and tryptophan 203. Here we present biochemical and biophysical data regarding, the phenotypes of conservative point mutants of Slt-IA in which tyrosine 114 is altered. We used oligonucleotide-directed mutagenesis to replace tyrosine 114 with either phenylalanine (Y114F) or serine (Y114S). Periplasmic extracts of E. coli containing wild-type or mutant Slt-IA were tested for their ability to inhibit protein synthesis in vitro. Relative to wild-type, the activity of mutant Y1 14F was attenuated about 30-fold, while the mutant Y114S was attenuated about 500 to 1000-fold. In order to address the possibility that differential activation of the mutants rather than local effects at the active site might account for their diminished activity, we engineered the same mutations into a truncated slt-IA cassette that directs expression of a product corresponding to the activated A₁ form of Slt-IA (wild-type-). The same general relationships held: relative to wild type-, Y114F- was attenuated about 7-fold, and Y114S- about 300-fold. Tryptic digestion profiles of the mutant proteins were similar to those of the corresponding wild-type, indicating that the amino acid substitutions had not caused major alterations in conformation. We conclude that Y114 plays a significant role in the activity of Slt-IA, one which is quantitatively similar to that of Y77, and one which is predicated on the presence of both its weakly acidic phenolic hydroxyl and its aromatic ring.