Art and Agency: A Reassessment

In his book, Art and agency , Alfred Gell presents a theory of art based neither on aesthetics nor on visual communication. Art is defined by the distinctive function it performs in advancing social relationships through 'the abduction of agency'. Art objects are indexes of the artist's or model's agency. This article examines Gell's use of agency, particularly in relation to the ritual art that is central to his argument. Focusing on Gell's employment of Peirce's term 'index' (out of his triad of index, icon, and symbol), I note that Peirce's approach deflects attention from signification towards the link between art works and the things to which they refer. I consider what Peirce meant by abduction, and conclude that while Gell makes a good case for the agency of art objects he does not explain the distinctive ways in which art objects extend their maker's or user's agency. Gell lacked the time to make detailed revisions before publication and I acknowledge that, given more time, he might have revised some parts of the book.     

The rabbit alpha-like globin gene cluster is polymorphic both in the sizes of BamHI fragments and in the numbers of duplicated sets of genes

The alpha-like globin gene cluster in rabbits contains embryonic zeta- globin genes, an adult alpha-globin gene, and theta-globin genes of undetermined function. The basic arrangement of genes, deduced from analysis of cloned DNA fragments, is 5'-zeta 0-zeta 1-alpha 1-theta 1- zeta 2-zeta 3-theta 2-3'. However, the pattern of restriction fragments containing zeta- and theta-globin genes varies among individual rabbits. Analysis of BamHI fragments of genomic DNA from 24 New Zealand white rabbits revealed eight different patterns of fragments containing zeta-globin genes. The large BamHI fragments containing genes zeta 0 and zeta 1 are polymorphic in length, whereas a 1.9-kb fragment containing the zeta 2 gene and the 3.5-kb fragment containing the zeta 3 gene do not vary in size. In contrast to this constancy in the size of the restriction fragments, the copy number of the zeta 2 and zeta 3 genes does vary among different rabbits. No length polymorphism was detected in the BamHI fragments containing the theta-globin genes, but again the copy number varies for restriction fragments containing the theta 2 gene. The alpha 1- and theta 1-globin genes are located in a nonpolymorphic 7.2-kb BamHI fragment. The combined data from hybridization with both zeta and theta probes shows that the BamHI cleavage pattern does not vary within the region 5'-alpha 1-theta 1- zeta 2-zeta 3-theta 2-3', but the pattern genomic blot-hybridization patterns for the progeny of parental rabbits with different zeta-globin gene patterns shows that the polymorphic patterns are inherited in a Mendelian fashion. Two different haplotypes have been mapped based on the genomic blot-hybridization data. The variation in the alpha-like globin gene cluster in the rabbit population results both from differences in the copy number of the duplication block containing the zeta-zeta-theta gene set and from the presence or absence of polymorphic BamHI sites.      

The osmotic/calcium stress theory of brain damage: Are free radicals involved?

This overview presents data showing that glucose use increases and that excitatory amino acids (i.e., glutamate, aspartate), taurine and ascorbate increase in the extracellular fluid during seizures. During the cellular hyperactive state taurine appears to serve as an osmoregulator and ascorbate may serve as either an antioxidant or as a pro-oxidant. Finally, a unifying hypothesis is given for seizure-induced brain damage. This unifying hypothesis states that during seizures there is a release of excitatory amino acids which act on glutamatergic receptors, increasing neuronal activity and thereby increasing glucose use. This hyperactivity of cells causes an influx, of calcium (i.e. calcium stress) and water movements (i.e., osmotic stress) into the cells that culminate in brain damage mediated by reactive oxygen species.Special issue dedicated to Dr. Frederick E. Samson     

Assignment of orthologous relationships among mammalian alpha-globin genes by examining flanking regions reveals a rapid rate of evolution

In order to study the relationships among mammalian alpha-globin genes, we have determined the sequence of the 3' flanking region of the human alpha 1 globin gene and have made pairwise comparisons between sequenced alpha-globin genes. The flanking regions were examined in detail because sequence matches in these regions could be interpreted with the least complication from the gene duplications and conversions that have occurred frequently in mammalian alpha-like globin gene clusters. We found good matches between the flanking regions of human alpha 1 and rabbit alpha 1, human psi alpha 1 and goat I alpha, human alpha 2 and goat II alpha, and horse alpha 1 and goat II alpha. These matches were used to align the alpha-globin genes in gene clusters from different mammals. This alignment shows that genes at equivalent positions in the gene clusters of different mammals can be functional or nonfunctional, depending on whether they corrected against a functional alpha-globin gene in recent evolutionary history. The number of alpha-globin genes (including pseudogenes) appears to differ among species, although highly divergent pseudogenes may not have been detected in all species examined. Although matching sequences could be found in interspecies comparisons of the flanking regions of alpha- globin genes, these matches are not as extensive as those found in the flanking regions of mammalian beta-like globin genes. This observation suggests that the noncoding sequences in the mammalian alpha-globin gene clusters are evolving at a faster rate than those in the beta-like globin gene clusters. The proposed faster rate of evolution fits with the poor conservation of the genetic linkage map around alpha-globin gene clusters when compared to that of the beta-like globin gene clusters. Analysis of the 3' flanking regions of alpha-globin genes has revealed a conserved sequence approximately 100-150 bp 3' to the polyadenylation site; this sequence may be involved in the expression or regulation of alpha-globin genes.      

Catabolic plasmids of environmental and ecological significance

The environmental and ecological significance of catabolic plasmids and their host strains are discussed in the context of their potential application for environmental biotechnology. Included is a comprehensive list of naturally occurring discrete catabolic plasmids isolated from either natural habitats or selective enrichment studies. General properties, such as plasmid maintenance, stability and transfer, are discussed together with the techniques for plasmid detection and monitoring in the environment. The issues concerning the construction of catabolic strains with new or broader substrate ranges and the uses of monocultures or consortia for in situ treatment are addressed.     

Cometabolic oxidation of polychlorinated biphenyls in soil with a surfactant-based field application vector.

Polychlorinated biphenyl (PCB)-degradative genes, under the control of a constitutive promoter, were cloned into a broad-host-range plasmid and a transposon. These constructs were inserted into a surfactant-utilizing strain, Pseudomonas putida IPL5, to create a field application vector (FAV) in which a surfactant-degrading organism cometabolizes PCB. By utilizing a surfactant not readily available to indigenous populations and a constitutive promoter, selective growth and PCB-degradative gene expression are decoupled from biphenyl. Since PCB degradation via the biphenyl degradation pathway is nonadaptive in the absence of biphenyl, there is no selective pressure for PCB gene maintenance. The recombinant strains exhibited degradative activity against 25 of 33 PCB congeners in Aroclor 1248 in the absence of biphenyl. Whole-cell enzyme assays indicated that PCB-degradative activity of a recombinant strain carrying the PCB genes on a plasmid was approximately twice that of the same strain carrying the PCB genes on a transposon. Plasmid loss rates in the absence of antibiotic selection averaged 7.4% per cell division and were highly variable between experiments. Surfactant-amended slurries of PCB-contaminated electric power plant substation soil were inoculated with approximately 10(5) recombinant cells per ml. The populations of the added strains increased to greater than 10(9) cells per ml in 2 days, and cell growth coincided with PCB degradation. By 15 days, 50 to 60% of the indicator congener 2,3,2',5'-tetrachlorobiphenyl was degraded. The effectiveness of PCB degradation by the plasmid-containing strain depended on plasmid stability. The transposon-encoded PCB genes were much more stable, and in surfactant-amended soil slurries, PCB degradation was more consistent between experiments.     

Audit of prenatal diagnosis for haemoglobin disorders in the United Kingdom: the first 20 years.

OBJECTIVES: To audit services for prenatal diagnosis for haemoglobin disorders in the United Kingdom. DESIGN: Comparison of the annual number of cases recorded in a United Kingdom register of prenatal diagnoses for haemoglobin disorders, with the annual number of pregnancies at risk of these disorders, by ethnic group and regional health authority. The number of pregnancies at risk was estimated using data on ethnic group from the 1991 census and data from the United Kingdom thalassaemia register, which records the number of babies born with thalassaemia. SETTING: The three national prenatal diagnosis centres for haemoglobin disorders. SUBJECTS: 2068 cases of prenatal diagnosis for haemoglobin disorders in the United Kingdom from 1974 to 1994. MAIN OUTCOME MEASURES: Utilisation of prenatal diagnosis by risk, ethnic group, and regional health authority. Proportion of referrals in the first trimester and before the birth of any affected child. RESULTS: National utilisation of prenatal diagnosis for haemoglobin disorders was around 20%. During the past 10 years it has remained steady at about 50% for thalassaemias and risen from 7% to 13% for sickle cell disorders. Utilisation for sickle cell disorders varies regionally from 2% to 20%. Utilisation for thalassaemias varies by ethnic group. It is almost 90% for Cypriots and ranges regionally for British Pakistanis from 0% to over 60%. About 60% of first prenatal diagnoses are done for couples without an affected child. Less than 50% of first referrals are in the first trimester. CONCLUSIONS: National utilisation of prenatal diagnosis for haemoglobin disorders is far lower than expected, and there are wide regional variations. A high proportion of referrals are still in the second trimester and after the birth of an affected child. The findings point to serious shortcomings in present antenatal screening practice and in local screening policies and to inadequate counselling resources, especially for British Pakistanis.     

Evidence for 4-chlorobenzoic acid dehalogenation mediated by plasmids related to pSS50.

The biodegradation of 4-chlorobiphenyl usually proceeds through the intermediate 4-chlorobenzoate. Few bacterial strains can degrade 4-chlorobiphenyl to 4-chlorobenzoate and 4-chlorobenzoate to CO2. This study demonstrates that the 4-chlorobiphenyl-degrading Alcaligenes sp. strain ALP83 can degrade 4-chlorobenzoate to 4-hydroxybenzoate. The dehalogenase activity is correlated with a 10-kb fragment carried on plasmid pSS70.     

Production of MUC1 and MUC2 mucins by human tumor cell lines.

A mucus secreting, clonal derivative (HT29-SB) of the human colonic adenocarcinoma cell line HT29, and the LS174T colon cancer cell line, secrete mucin into the culture medium as a viscoelastic gel. Mab BC2, which defines a peptide epitope present in the variable number of tandem repeats (VNTR) of the MUC1 core protein, reacted with this material after deglycosylation. Two high molecular weight bands were detected in TFMSA treated gel-formed mucin from HT29-SB and LS174T by western blotting (Mr 580 kDa and 420 kDa). A similar pattern of reactivity was seen with the culture supernatants from HT29-SB, the ovarian tumor cell line COLO-316, and the breast cancer cell line MCF-7. Mab CCP58 (anti-MUC2 VNTR) reacted with a 580 kDa band in gel-formed mucin produced by LS174T, but was not reactive with mucin produced by the other cell lines. The findings indicate that human colonic cell lines, in addition to breast and ovarian cell lines, may both express and secrete the MUC1 protein core, and that the LS174T cell line expresses and secretes both the MUC1 and MUC2 core proteins.     

Comparative genetic organization of incompatibility group P degradative plasmids.

Plasmids that encode genes for the degradation of recalcitrant compounds are often examined only for characteristics of the degradative pathways and ignore regions that are necessary for plasmid replication, incompatibility, and conjugation. If these characteristics were known, then the mobility of the catabolic genes between species could be predicted and different catabolic pathways might be combined to alter substrate range. Two catabolic plasmids, pSS50 and pSS60, isolated from chlorobiphenyl-degrading strains and a 3-chlorobenzoate-degrading plasmid, pBR60, were compared with the previously described IncP group (Pseudomonas group P-1) plasmids pJP4 and R751. All three of the former plasmids were also members of the IncP group, although pBR60 is apparently more distantly related. DNA probes specific for known genetic loci were used to determine the order of homologous loci on the plasmids. In all of these plasmids the order is invariant, demonstrating the conservation of this "backbone" region. In addition, all five plasmids display at least some homology with the mercury resistance transposon, Tn501, which has been suggested to be characteristic of the beta subgroup of the IncP plasmids. Plasmids pSS50 and pSS60 have been mapped in detail, and repeat sequences that surround the suspected degradation genes are described.