Membrane-trafficking RabA4c involved in the effect of glycine betaine on recovery from chilling stress in Arabidopsis

Glycine betaine (GB) can confer tolerance to several types of stress at low concentrations, either after application to plants or in transgenics engineered to overproduce GB. Based on earlier studies on levels of GB in plants and evidence for effects on gene expression, we hypothesized that at least part of this effect could be ascribed to the activation of the expression of stress tolerance genes. Using a strategy based on high-throughput gene expression analysis with microarrays followed by confirmation with northern blots, we identified Arabidopsis genes upregulated in roots that reinforce intracellular processes protecting cells from oxidative damage and others that appear to be involved in reinforcing a scavenging system for reactive oxygen species (ROS) in cell walls. Upregulated genes in roots include those for the membrane-trafficking RabA4c, the root-specific NADPH-dependent ferric reductase (FRO2) localized to the plasma membrane, mitochondrial catalase 2 and the cell wall peroxidase ATP3a. Comparative studies with wild-type Arabidopsis and knockout mutants for the membrane-trafficking RabA4c gene demonstrated that the mutants respond only slightly to GB, if at all, compared with wild-type in relation to root growth recovery after chilling stress, demonstrating the role of RabA4c in relation to the GB effect. The results point toward links between oxidative stress, gene expression, membrane trafficking and scavenging of ROS such as superoxide and hydrogen peroxide in relation to GB effects on chilling tolerance in plants.     

Suffering, justice, and the politics of becoming

To suffer is to undergo, to bear, to endure. Suffering exists on the underside of agency; it is as important to ethics as agency. The experience of suffering is never entirely captured by the ethical, political, medical and spiritual categories in which it is represented. Perhaps an engagement with suffering can open up hidden connections between these domains. After examining John Caputo and Friedrich Nietzsche comparatively on the relation between suffering and ethics, this essay explores the relation of the politics of becoming to suffering. The politics of becoming is a paradoxical process by which a new cultural identity is drawn into being and yet is irreducible to the energies and motives that spurred its initiators to action. To exemplify and think the politics of becoming is to call into question the sufficiency of existing paradigms of morality. A critical examination of the Rawlsian model of justice brings out, for example, the insufficiency of justice to the politics of becoming. It suggests the need, first, to pursue an ethics of engagement between several parties drawing upon a variety of sources of ethical inspiration and, second, to cultivate ldcritical responsiveness to new social movements that struggle to place new identities onto the cultural register. If the latter movements sometimes modify general understandings of suffering, identity, justice and medical practice they also indicate the role cultural thinkers can play in re-examining periodically established codes of interaction between these domains.A paper presented, with commentaries, as the 1995 Roger Allan Moore Lecture at Harvard Medical School, Center for the Study of Culture and Medicine, May 11, 1995.     

Asymmetric competition between plant species

Despite extensive interest in the role of plant size in competition, few formal attempts have been made to quantify the magnitude of asymmetric competition, particularly for interactions between members of different species. This paper introduces the concept of asymmetric interspecific competition at the population livel (i.e. mean plant performance) in mixtures of species. It proposes an index of interspecific competitive asymmetry which allows for a progressively greater asymmetric effect as the average size differences between competing species increase, and allows for such an effect whether individuals of focal species are larger or smaller, on average, than competitors. This index of competitive asymmetry is evaluated in the study of interactions between two widely coexisting annuals of disturbed habitats, Stellaria media and Poa annua. An experiment was conducted in which the density, relative frequency and relative seedling sizes (emergence times) of Poa and Stellaria individuals were varied. The relative growth rate (RGR) for both species was measured over a 22-day period. An inverse linear model was fitted for each species, relating the RGR of the focal species to the initial biomass of each species. Each response model included an asymmetry coefficient () to assess whether the impact of a unit of initial biomass of the associate species changed with the relative sizes of seedlings of the two species. A zero value of implies symmetric competition between the two populations; i.e. the competitive effect of a unit of associate species biomass does not change with its initial seedling size. If is positive the smaller the initial relative size of seedlings of the associate species, the smaller their per unit biomass effect on the response of the focal species. The model fitted our data for Stellaria and Poa well and was validated by an alternative modelling approach. Asymmetry coefficients were estimated as 0.508 (P<0.05) for the effect of Poa in the Stellaria model, and 0.0001 (NS) for the effect of Stellaria in the Poa model; i.e. the effect of Poa on Stellaria was asymmetric while the effect of Stellaria on Poa was symmetric. Differences in interspecific species asymmetric competitive effects are discussed within the context of shoot architecture, and the relative importance of competition for light versus soil resources. Finally, we discuss the relationship of this model to earlier models of competitive asymmetry, and consider the implications of interspecific competitive asymmetry for a number of current theories of plant competition and community organisation.     

Refining the region of branchio-oto-renal syndrome and defining the flanking markers on chromosome 8q by genetic mapping.

Branchio-oto-renal syndrome (BOR) is an autosomal dominant disorder associated with external-, middle-, and inner-ear malformations, branchial cleft sinuses, cervical fistulas, mixed hearing loss, and renal anomalies. The gene for BOR was mapped to the long arm of chromosome 8q. Several polymorphic dinucleotide repeat markers were investigated for linkage in two large BOR families, and the region of localization was refined. Two-point linkage analysis yielded the maximum lod scores of 7.44 at theta = .03 and 6.71 at theta = .04, with markers D8S279 and D8S260, respectively. A multipoint analysis was carried out to position the BOR gene with a defined region using markers D8S165, D8S285, PENK, D8S166, D8S260, D8S279, D8S164, D8S286, D8S84, D8S275, D8S167, D8S273, and D8S271. Haplotype analysis of recombination events at these polymorphic loci was also performed in multigeneration BOR kindreds. The linkage analysis and analysis of recombination events identified markers that clearly flank the BOR locus. The order was determined to be D8S260-BOR-D8S279 at odds > 10(3):1 over the other possible orders. This flanking markers provide a resource for high-resolution mapping toward cloning and characterizing the BOR gene.     

Synthesis and properties of oligodeoxynucleotides containing the analogue 2'-deoxy-4'-thiothymidine.

The 2'-deoxythymidine analogue 2'-deoxy-4'-thiothymidine has been incorporated, using standard methodology, into a series of dodecadeoxynucleotides containing the EcoRV restriction endonuclease recognition site (GATATC). The stability of these oligodeoxynucleotides and their ability to act as substrates for the restriction endonuclease and associated methylase have been compared with a normal unmodified oligodeoxynucleotide. No problems were encountered in the synthesis despite the presence of a potentially oxidisable sulfur atom in the sugar ring. The analogue had very little effect on the melting temperature of the self-complementary oligoeoxynucleotides so synthesised and all had a CD spectrum compatible with a B-DNA structure. The oligodeoxynucleotide containing one analogue in each strand within the recognition site, adjacent to the bond to be cleaved (i.e. GAXATC, where X is 2'-deoxy-4'-thiothymidine), was neither a substrate for the endonuclease nor was recognized by the associated methylase. When still within the recognition hexanucleotide but two further residues removed from the site of cleavage (i.e. GATAXC), the oligodeoxynucleotide was a poor substrate for both the endonuclease and methylase. Binding of the oligodeoxynucleotide to the endonuclease was unaffected but the kcat value was only 0.03% of the value obtained for the parent oligodeoxynucleotide. These results show that the incorporation of 2'-deoxy-4'-thionucleosides into synthetic oligodeoxynucleotides may shed light on subtle interactions between proteins and their normal substrates and may also show why 2'-deoxy-4'-thiothymidine itself is so toxic in cell culture.     

What are the complications of influenza and can they be prevented? Experience from the 1989 epidemic of H3N2 influenza A in general practice.

OBJECTIVES--In an epidemic: to measure the incidence and risk of complications of influenza; to determine the effect of pre-existing disease on complications; to estimate vaccine uptake and efficacy. DESIGN--Case-control study. SETTING--Primary care: two group practices. SUBJECTS--342 of the 395 cases of clinically diagnosed influenza reported to the general practice surveillance of infectious diseases scheme of the Public Health Laboratory Service during the 1989 epidemic, and 342 age and sex matched controls. INTERVENTIONS--Examination of records. MAIN OUTCOME MEASURES--Documented recognised complications; hospital admission; previous vaccination. RESULTS--Of 15 recognised complications, bronchitis was the commonest (rate 190.1/1000 cases) and significantly commoner in cases (summary odds ratio 9.7) after adjusting for higher consultation rates (mean 6.1 per annum v 4.2 among controls; p < 0.0001). No deaths were recorded. The risk of bronchitis complicating influenza was higher in patients with pre-existing illnesses regarded as an indication for vaccination (odds ratio 3.3; p < 0.0001). Observed vaccination efficacy in those with pre-existing illnesses and in elderly subjects was high (63% and 77% respectively) but uptake was low (4.5% and 6.1% respectively). CONCLUSIONS--Bronchitis complicates about one fifth of all cases of influenza presenting to general practitioners. Patients with pre-existing illnesses regarded as an indication for vaccination are particularly at risk. Vaccine uptake is extremely low, precluding an unequivocal demonstration of a protective effect.