PPAR gamma is required for the differentiation of adipose tissue in vivo and in vitro

The process of adipogenesis is known to involve the interplay of several transcription factors. Activation of one of these factors, the nuclear hormone receptor PPAR gamma, is known to promote fat cell differentiation in vitro. Whether PPAR gamma is required for this process in vivo has remained an open question because a viable loss-of-function model for PPAR gamma has been lacking. We demonstrate here that mice chimeric for wild-type and PPAR gamma null cells show little or no contribution of null cells to adipose tissue, whereas most other organs examined do not require PPAR gamma for proper development. In vitro, the differentiation of ES cells into fat is shown to be dependent on PPAR gamma gene dosage. These data provide direct evidence that PPAR gamma is essential for the formation of fat.

The genome sequence of Schizosaccharomyces pombe

We have sequenced and annotated the genome of fission yeast (Schizosaccharomyces pombe), which contains the smallest number of protein-coding genes yet recorded for a eukaryote: 4,824. The centromeres are between 35 and 110 kilobases (kb) and contain related repeats including a highly conserved 1.8-kb element. Regions upstream of genes are longer than in budding yeast (Saccharomyces cerevisiae), possibly reflecting more-extended control regions. Some 43% of the genes contain introns, of which there are 4,730. Fifty genes have significant similarity with human disease genes; half of these are cancer related. We identify highly conserved genes important for eukaryotic cell organization including those required for the cytoskeleton, compartmentation, cell-cycle control, proteolysis, protein phosphorylation and RNA splicing. These genes may have originated with the appearance of eukaryotic life. Few similarly conserved genes that are important for multicellular organization were identified, suggesting that the transition from prokaryotes to eukaryotes required more new genes than did the transition from unicellular to multicellular organization.

Langerin, a novel C-type lectin specific to Langerhans cells, is an endocytic receptor that induces the formation of Birbeck granules

We have identified a type II Ca2+-dependent lectin displaying mannose-binding specificity, exclusively expressed by Langerhans cells (LC), and named Langerin. LC are uniquely characterized by Birbeck granules (BG), which are organelles consisting of superimposed and zippered membranes. Here, we have shown that Langerin is constitutively associated with BG and that antibody to Langerin is internalized into these structures. Remarkably, transfection of Langerin cDNA into fibroblasts created a compact network of membrane structures with typical features of BG. Langerin is thus a potent inducer of membrane superimposition and zippering leading to BG formation. Our data suggest that induction of BG is a consequence of the antigen-capture function of Langerin, allowing routing into these organelles and providing access to a nonclassical antigen-processing pathway.

Antidepressant- and cocaine-sensitive human serotonin transporter: molecular cloning, expression, and chromosomal localization

A Na(+)- and Cl(-)-coupled serotonin (5-hydroxytryptamine, 5HT) transporter is expressed on human neuronal, platelet, placental, and pulmonary membranes. The brain 5HT transporter appears to be a principal site of action of therapeutic antidepressants and may mediate behavioral and/or toxic effects of cocaine and amphetamines. Oligonucleotides derived from consensus transporter sequences were used to identify human placental cDNAs highly related to the rat brain 5HT carrier. Transfection of one of these cDNAs into HeLa cells yields a high-affinity (Km = 463 nM), Na(+)- and Cl(-)-dependent 5HT transport activity which can be blocked by selective 5HT transport inhibitors, including paroxetine, fluoxetine, and imipramine, and which is antagonized by cocaine and amphetamine. Sequence analysis reveals a 630-amino acid open reading frame bearing 92% identity to the cloned rat brain 5HT transporter, with identical predicted topological features and conserved sites for posttranslational modifications. Unlike the rodent, where a single mRNA appears to encode 5HT transporters, multiple hybridizing RNAs are observed in human placenta and lung. Somatic cell hybrid and in situ hybridization studies are consistent, however, with a single gene encoding the human 5HT transporter, localized to chromosome 17q11.1-17q12.

Exercise treatment for major depression: maintenance of therapeutic benefit at 10 months

OBJECTIVE

The purpose of this study was to assess the status of 156 adult volunteers with major depressive disorder (MDD) 6 months after completion of a study in which they were randomly assigned to a 4-month course of aerobic exercise, sertraline therapy, or a combination of exercise and sertraline.

METHODS

The presence and severity of depression were assessed by clinical interview using the Diagnostic Interview Schedule and the Hamilton Rating Scale for Depression (HRSD) and by self-report using the Beck Depression Inventory. Assessments were performed at baseline, after 4 months of treatment, and 6 months after treatment was concluded (ie, after 10 months).

RESULTS

After 4 months patients in all three groups exhibited significant improvement; the proportion of remitted participants (ie, those who no longer met diagnostic criteria for MDD and had an HRSD score <8) was comparable across the three treatment conditions. After 10 months, however, remitted subjects in the exercise group had significantly lower relapse rates (p = .01) than subjects in the medication group. Exercising on one's own during the follow-up period was associated with a reduced probability of depression diagnosis at the end of that period (odds ratio = 0.49, p = .0009).

CONCLUSIONS

Among individuals with MDD, exercise therapy is feasible and is associated with significant therapeutic benefit, especially if exercise is continued over time.

Measurement of lipid peroxidation

Lipid peroxidation results in the formation of conjugated dienes, lipid hydroperoxides and degradation products such as alkanes, aldehydes and isoprostanes. The approach to the quantitative assessment of lipid peroxidation depends on whether the samples involve complex biological material obtained in vivo, or whether the samples involve relatively simple mixtures obtained in vitro. Samples obtained in vivo contain a large number of products which themselves may undergo metabolism. The measurement of conjugated diene formation is generally applied as a dynamic quantitation e.g. during the oxidation of LDL, and is not generally applied to samples obtained in vivo. Lipid hydroperoxides readily decompose, but can be measured directly and indirectly by a variety of techniques. The measurement of MDA by the TBAR assay is non-specific, and is generally poor when applied to biological samples. More recent assays based on the measurement of MDA or HNE-lysine adducts are likely to be more applicable to biological samples, since adducts of these reactive aldehydes are relatively stable. The discovery of the isoprostanes as lipid peroxidation products which can be measured by gas chromatography mass spectrometry or immunoassay has opened a new avenue by which to quantify lipid peroxidation in vivo, and will be discussed in detail.

Factors controlling long- and short-term sequestration of atmospheric CO2 in a mid-latitude forest

Net uptake of carbon dioxide (CO2) measured by eddy covariance in a 60- to 80-year-old forest averaged 2.0 +/- 0.4 megagrams of carbon per hectare per year during 1993 to 2000, with interannual variations exceeding 50%. Biometry indicated storage of 1.6 +/- 0.4 megagrams of carbon per hectare per year over 8 years, 60% in live biomass and the balance in coarse woody debris and soils, confirming eddy-covariance results. Weather and seasonal climate (e.g., variations in growing-season length or cloudiness) regulated seasonal and interannual fluctuations of carbon uptake. Legacies of prior disturbance and management, especially stand age and composition, controlled carbon uptake on the decadal time scale, implying that eastern forests could be managed for sequestration of carbon.

Global distribution of neutrons from Mars: results from Mars odyssey

Global distributions of thermal, epithermal, and fast neutron fluxes have been mapped during late southern summer/northern winter using the Mars Odyssey Neutron Spectrometer. These fluxes are selectively sensitive to the vertical and lateral spatial distributions of H and CO2 in the uppermost meter of the martian surface. Poleward of +/-60 degrees latitude is terrain rich in hydrogen, probably H2O ice buried beneath tens of centimeter-thick hydrogen-poor soil. The central portion of the north polar cap is covered by a thick CO2 layer, as is the residual south polar cap. Portions of the low to middle latitudes indicate subsurface deposits of chemically and/or physically bound H2O and/or OH.

Assessing the performance of the Oxford Nanopore Technologies MinION

The Oxford Nanopore Technologies (ONT) MinION is a new sequencing technology that potentially offers read lengths of tens of kilobases (kb) limited only by the length of DNA molecules presented to it. The device has a low capital cost, is by far the most portable DNA sequencer available, and can produce data in real-time. It has numerous prospective applications including improving genome sequence assemblies and resolution of repeat-rich regions. Before such a technology is widely adopted, it is important to assess its performance and limitations in respect of throughput and accuracy. In this study we assessed the performance of the MinION by re-sequencing three bacterial genomes, with very different nucleotide compositions ranging from 28.6% to 70.7%; the high G + C strain was underrepresented in the sequencing reads. We estimate the error rate of the MinION (after base calling) to be 38.2%. Mean and median read lengths were 2 kb and 1 kb respectively, while the longest single read was 98 kb. The whole length of a 5 kb rRNA operon was covered by a single read. As the first nanopore-based single molecule sequencer available to researchers, the MinION is an exciting prospect; however, the current error rate limits its ability to compete with existing sequencing technologies, though we do show that MinION sequence reads can enhance contiguity of de novo assembly when used in conjunction with Illumina MiSeq data.

Production of cytokines by mouse B cells: B lymphomas and normal B cells produce interleukin 10

We have examined a panel of murine Ly-1+ B lymphomas and purified normal murine peritoneal B cells separated into subsets on the basis of expression of the Ly-1 surface antigen, for their ability to produce cytokines. Where possible, we have used a combination of cytokine detection methods in order to compensate for differences in sensitivity and specificity, and the possibility of inhibitors masking an activity. All the lymphomas tested were shown to constitutively express TGF-beta and CSIF/IL-10. In addition, varying levels of IL-6, TNF-alpha and TNF-beta, and G-CSF, were demonstrable in most of the lymphomas, and variants of one lymphoma (CH12) additionally produced varying levels of IL-3, IL-4, and GM-CSF. FACS purified normal Ly-1+ and Ly-1- peritoneal B cells, were also shown to express RNA encoding CSIF/IL-10, IL-6, TNF-alpha and TNF-beta, and very low levels of G-CSF, following stimulation with LPS. These data were supported by the detection of IL-6 and CSIF/IL-10 in supernatants from LPS-stimulated Ly-1+ and Ly-1- B cells using specific immunoassays. None of the lymphomas or B cell preparations produced IL-1 alpha, IL-2, IL-5, IL-7, or IFN-gamma. The purity of our normal B cell populations was assessed by phenotypic analysis on the FACS and also by the disappearance of certain mRNA transcripts after purification, e.g. CD4, c-fms, GM-CSF, and IFN-gamma, most of which could be detected in LPS-stimulated total peritoneal cell populations. This suggested that our B cell purification method had reduced, to a level undetectable in our assays, contaminating T cells (CD4), macrophages (c-fms, GM-CSF), and NK cells (IFN-gamma). Absence of IL-3, IL-4, IL-5, and GM-CSF expression by LPS-stimulated Ly-1+ and Ly-1- B cells reduced the concern that contaminating peritoneal mast cells could account for the observed cytokine production. We therefore believe our data provide strong support for production of a subset of cytokines by LPS-stimulated normal B cells. Both the Ly-1+ B lymphomas and normal Ly-1+ and Ly-1- B cells appear capable of expressing IL-6, TNF-alpha, TNF-beta, and CSIF/IL-10.(ABSTRACT TRUNCATED AT 400 WORDS)

Plasma endothelin immunoreactivity in liver disease and the hepatorenal syndrome

BACKGROUND

Severe renal vasoconstriction is central to the pathogenesis of renal failure in the hepatorenal syndrome. Endothelin-1 and endothelin-3 are potent, long-acting vasoconstrictors, and endothelin-1 has selective potency as a renal vasoconstrictor. These properties suggest a role for endothelins in the hepatorenal syndrome.

METHODS

We measured plasma endothelin-1 and endothelin-3 concentrations using specific radioimmunoassays in subjects with hepatorenal syndrome, liver disease but normal renal function, chronic renal failure, acute renal failure, liver dysfunction and renal impairment, or normal liver and kidney function.

RESULTS

The patients with the hepatorenal syndrome had markedly elevated mean (+/- SE) plasma concentrations of endothelin-1 (36 +/- 5 ng per liter [14.5 +/- 1.8 pmol per liter]) and endothelin-3 (43 +/- 3 ng per liter [16.3 +/- 1.0 pmol per liter]) as compared with the normal subjects (endothelin-1, 4 +/- 1 ng per liter [1.7 +/- 0.2 pmol per liter]; and endothelin-3, 18 +/- 1 ng per liter [6.8 +/- 0.4 pmol per liter]; P < 0.001) and with the patients in the other four groups (P < 0.001 to P < 0.05). The plasma endothelin-1, but not endothelin-3, concentrations in these four patient groups were significantly higher than in the normal subjects (P < 0.001 to P < 0.05). The concentrations of endothelin-1 in renal arterial plasma and renal venous plasma, measured in five patients with the hepatorenal syndrome and three with chronic liver disease and normal renal function, were 20 +/- 4 ng per liter (7.9 +/- 1.8 pmol per liter) and 24 +/- 4 ng per liter (9.5 +/- 1.5 pmol per liter), respectively (P < 0.05).

CONCLUSIONS

The increase in plasma endothelin-1 and endothelin-3 concentrations in patients with the hepatorenal syndrome is consistent with the hypothesis that these substances have a role in the pathogenesis of the disease.

Duloxetine vs placebo in the treatment of stress urinary incontinence: a four-continent randomized clinical trial

OBJECTIVES

To further assess, in a phase 3 study, treatment with duloxetine for women with stress urinary incontinence (SUI) in other geographical regions, including Argentina, Australia, Brazil, Finland, Poland, South Africa and Spain, as previous trials in North America and Europe provided evidence for the safety and efficacy of duloxetine as a pharmacological treatment for SUI in women.

PATIENTS AND METHODS

The study included 458 women aged 27-79 years enrolled in a double-blind, placebo-controlled trial. The patients with predominantly SUI were identified using a validated clinical algorithm. They were randomly assigned to receive placebo (231) or duloxetine 40 mg twice daily (227) for 12 weeks. The primary outcome variables included the incontinence episode frequency (IEF) and the Incontinence Quality of Life (I-QOL) questionnaire. Van Elteren's test was used to analyse the percentage changes in IEF where the stratification variable was weekly baseline IEF (IEF < 14 and > or = 14). Analysis of covariance was used to analyse I-QOL scores.

RESULTS

The mean baseline IEF was 18.4/week; 55% of patients had a baseline IEF of > or = 14. There was a significantly greater median decrease in IEF with duloxetine with placebo (54% vs 40%, P = 0.05), with comparable significant improvements in quality of life (I-QOL score increases of 10.3 vs 6.4, P = 0.007). The improvements with duloxetine were associated with significantly greater increases in voiding intervals than with placebo (20.4 vs 8.5 min, P < 0.001). The placebo response was 10.7% and 12.5% higher than those reported in two European and North American phase 3 trials. This may have been related to more patients being naïve for incontinence management in the current trial. Discontinuation rates for adverse events were 1.7% for placebo and 17.2% for duloxetine (P < 0.001), with nausea being the most common reason for discontinuation (3.1%); it was the most common adverse event with duloxetine, but was mild or moderate in most (81%), did not worsen in any patient and resolved within 7 days in 60% and within 1 month in 86% of continuing patients; 88% of women who experienced nausea while taking duloxetine completed the trial.

CONCLUSIONS

These results show improvements in incontinence and quality of life with duloxetine 40 mg twice daily for 12 weeks that are in keeping with those reported in two other recently completed phase 3 trials in Europe and North America.

A lag in intracellular degradation of mutant alpha 1-antitrypsin correlates with the liver disease phenotype in homozygous PiZZ alpha 1-antitrypsin deficiency

Liver injury in PiZZ alpha 1-antitrypsin (alpha 1-AT) deficiency probably results from toxic effects of the abnormal alpha 1-AT molecule accumulating within the ER of liver cells. However, only 12-15% of individuals with this same genotype develops liver disease. Therefore, we predicted that other genetic traits that determine the net intracellular accumulation of the mutant alpha 1-AT molecule would also determine susceptibility to liver disease. To address this prediction, we transduced skin fibroblasts from PiZZ individuals with liver disease or without liver disease with amphotropic recombinant retroviral particles designed for constitutive expression of the mutant alpha 1-AT Z gene. Human skin fibroblasts do not express the endogenous alpha 1-AT gene but presumably express other genes involved in postsynthetic processing of secretory proteins. The results show that expression of human alpha 1-AT gene was conferred on each fibroblast cell line. Compared to the same cell line transduced with the wild-type alpha 1-AT M gene, there was selective intracellular accumulation of the mutant alpha 1-AT Z protein in each case. However, there was a marked delay in degradation of the mutant alpha 1-AT Z protein after it accumulated in the fibroblasts from ZZ individuals with liver disease ("susceptible hosts") as compared to those without liver disease ("protected hosts"). Appropriate disease controls showed that the lag in degradation in susceptible hosts is specific for the combination of PiZZ phenotype and liver disease. Biochemical characteristics of alpha 1-AT Z degradation in the protected hosts were found to be similar to those of a common ER degradation pathway previously described in model experimental cell systems for T-cell receptor alpha subunits and asialoglycoprotein receptor subunits, therefore, raising the possibility that the lag in degradation in the susceptible host is a defect in this common ER degradation pathway. Thus, these data provide evidence that other genetic traits that affect the fate of the abnormal alpha 1-AT Z molecule, at least in part, determine susceptibility to liver disease. These data also validate a system for elucidating the biochemical/genetic characteristics of these traits and for examining the relevance to human disease of pathways for protein degradation in the ER.

Particle nucleation in the tropical boundary layer and its coupling to marine sulfur sources

New particle formation in a tropical marine boundary layer setting was characterized during NASA's Pacific Exploratory Mission-Tropics A program. It represents the clearest demonstration to date of aerosol nucleation and growth being linked to the natural marine sulfur cycle. This conclusion was based on real-time observations of dimethylsulfide, sulfur dioxide, sulfuric acid (gas), hydroxide, ozone, temperature, relative humidity, aerosol size and number distribution, and total aerosol surface area. Classic binary nucleation theory predicts no nucleation under the observed marine boundary layer conditions.

Challenging behaviours: prevalence and topographies

BACKGROUND

Variations in reported prevalence of challenging behaviour indicate the need for further epidemiological research to support accurate planning of future service provision.

METHODS

All services providing for people with learning disabilities across seven unitary authorities, with a total population of 1.2 million, were screened to identify people with challenging behaviour. Interviews were conducted with primary carers to gain data on identified individuals' characteristics and support. Measures designed for a similar study conducted in Manchester University were incorporated to allow direct comparison with earlier findings, together with standardized tools to assess adaptive behaviour and social impairment.

RESULTS

In total, 4.5 (2.5-7.5) people per 10 000 population were rated as seriously challenging, representing 10% (5.5-16.8%) of the learning disability population; the most prevalent general form was other difficult/disruptive behaviour, with non-compliance being the most prevalent topography. The majority showed multiple behaviours and multiple topographies within each general behaviour category. Also identified were substantial numbers of additional people reported as presenting challenging behaviours at lower degrees of severity.

CONCLUSIONS

Prevalence rates for seriously challenging behaviours were comparable to those reported in the earlier studies, thus confirming previous findings. The prevalence of less serious challenging behaviour also has major clinical significance and emphasizes the need for enhanced understanding and skills among personnel within primary- and secondary-tier health, education and social care services, and for strengthening the capacity of community teams to provide behavioural expertise.

Alginates from wound dressings activate human macrophages to secrete tumour necrosis factor-alpha

Alginates are used to manufacture a number of wound dressings. Clinical observations indicate that they may initiate or accelerate healing of chronic wounds after treatment of underlying pathology. Wound granulation tissue contains large numbers of macrophages and they are thought to regulate the healing process. As purified alginates have been demonstrated to activate macrophages this study was initiated to determine whether alginates present within wound dressings may interact with wound macrophages. Alginate fibres taken from four commercially available dressings were co-cultured with the human histiocytic lymphoma cell line U937 following its differentiation with PMA. Activation was assessed by measurement of TNFalpha production. Two of the dressings, Seasorb and Tegagen, had a minimal effect whilst Sorbsan at 1 mg/ml induced 302 + 19 pg/ml TNFalpha. This effect was inhibited by polymyxin B indicating that activation was due to endotoxin contamination. Kaltostat induced production of 839 + 36 pg/ml TNFalpha. This effect was induced both by polymyxin inhibitable endotoxin and a direct interaction with the alginate fibres. These data indicate that some alginate containing dressings have the potential to activate macrophages within the chronic wound bed and generate a pro-inflammatory signal which may initiate a resolving inflammation characteristic of healing wounds.

SecA protein, a peripheral protein of the Escherichia coli plasma membrane, is essential for the functional binding and translocation of proOmpA

We have reconstituted protein translocation across plasma membrane vesicles of Escherichia coli using purified proOmpA and trigger factor, a 63 kd soluble protein. Treatment of membrane vesicles with urea inactivates them for translocation unless a factor present in cytoplasmic extracts is added during the translocation reaction. Sedimentation analysis showed that the stimulatory activity is of distinctly higher mol. wt than trigger factor. Cytoplasmic extracts from a strain that greatly overproduces the SecA protein are highly enriched in the stimulatory activity for untreated membranes and restore translocation to urea-treated membranes, suggesting that this protein is the stimulatory factor. This assay was used to monitor the isolation of SecA protein from the overproducing strain. The purified protein is soluble, yet binds peripherally to membranes with high affinity and supports translocation. Using pure proOmpA, SecA protein, trigger factor and urea-treated membranes, the protein export process was resolved into binding and translocation steps. We find that proOmpA binds to membrane vesicles with or without SecA protein, but that translocation only occurs when SecA was bound prior to proOmpA.

A chemiluminescense-based assay for S-nitrosoalbumin and other plasma S-nitrosothiols

The lack of a simple assay for the quantification of S-nitrosothiols in complex biological matrices has hampered our understanding of their contribution to normal physiology and pathophysiological states. In this paper we describe an assay based upon the release of nitric oxide by reaction with a mixture consisting of Cu(I), iodine and iodide with subsequent quantification by chemiluminescense. With this method we can detect levels of S-nitrosothiols down to 5 nM in plasma. Following alkylation of free thiols with N-ethylmaleimide, and removal of nitrite with acidified sulfanilamide, we were able to measure known amounts of S-nitrosoalbumin added to plasma or whole blood, with an inter-assay variation for plasma S-nitrosothiols of approximately 4%. Further studies showed that the mean concentration of circulating S-nitrosothiols in venous plasma of healthy human volunteers was 28+/-7 nM.

Ontogeny of place learning in children as measured in the radial arm maze, Morris search task, and open field task

Children and adults were tested on 3 place learning tasks. Children under the age of 7 were inferior to older subjects in solving the tasks by using spatial relational solutions, but subjects of all ages were equally proficient in solving the task by using simple stimulus-reward associations (cued solutions). Accurate performance on the cued versions suggests that neither the general response demands nor the large size of testing environments rendered the tasks differentially inappropriate for young children. Instead, the nature of the cognitive demands were responsible for different levels of performance across the age groups. Because, in animal studies, spatial relational solutions but not cued solutions of these tests require mature and undamaged medial temporal lobe structures, the results suggest that these systems are not fully developed in humans before approximately 7 years of age.

Quantification of the major urinary metabolite of 15-F2t-isoprostane (8-iso-PGF2alpha) by a stable isotope dilution mass spectrometric assay

The isoprostanes (IsoPs) are a series of novel prostaglandin (PG)-like compounds generated from the free radical-catalyzed peroxidation of arachidonic acid. The first series of IsoPs characterized contained F-type prostane rings analogous to PGF2alpha. One F-ring IsoP, 15-F2t-IsoP (8-iso-PGF2alpha) has been shown to be formed in abundance in vivo and to exert potent biological activity. As a means to assess the endogenous production of this compound, we developed a method to quantify the major urinary metabolite of 15-F2t-IsoP, 2,3-dinor-5,6-dihydro-15-F2t-IsoP (2,3-dinor-5, 6-dihydro-8-iso-PGF2alpha), by gas chromotography/negative ion chemical ionization mass spectrometry. This metabolite was chemically synthesized and converted to an 18O2-labeled derivative for use as an internal standard. After purification, the compound was analyzed as a pentafluorobenzyl ester trimethylsilyl ether. Precision of the assay is +/-4% and accuracy is 97%. The lower limit of sensitivity is approximately 20 pg. Levels of the urinary excretion of this metabolite in 10 normal adults were found to be 0. 39 +/- 0.18 ng/mg creatinine (mean +/- 2 SD). Substantial elevations in the urinary excretion of the metabolite were found in situations in which IsoP generation is increased and antioxidants effectively suppressed metabolite excretion. Levels of 2,3-dinor-5, 6-dihydro-15-F2t-IsoP were not affected by cyclooxygenase inhibitors. Thus, this assay provides a sensitive and accurate method to assess endogenous production of 15-F2t-IsoP as a means to explore the pathophysiological role of this compound in human disease.

Quantitation of 8-oxoguanine and strand breaks produced by four oxidizing agents

Reactive oxygen species, produced endogenously or by exposure to environmental chemicals and ionizing radiation, induce a wide range of DNA lesions. The variety of chemistries associated with different oxidants suggests that each will produce a unique spectrum of DNA damage products. To extend our efforts to relate genotoxin chemistry to DNA damage, we measured both strand breaks and 8-oxoguanine (8-oxoG) in DNA after exposure to gamma-radiation, Fe(II)-EDTA/H2O2, Cu(II)/H2O2, and peroxynitrite at concentrations approaching physiological relevance. We found that the ratio of 8-oxoG to strand breaks varied more than 10-fold depending on the oxidizing agent: approximately 0.4 for Cu(II)/H2O2 and peroxynitrite and approximately 0.03 for Fe-(II)-EDTA/ H2O2 and gamma-radiation. In the case of Cu(II)/H2O2, the relative proportion of 8-oxoG and strand breaks was found to vary more than 2-fold (0.14-0.37) for different Cu(II) concentrations, consistent with other studies. We were able to detect 8-oxoG formation by peroxynitrite by using low peroxynitrite concentrations in conjunction with a sensitive immunoaffinity/HPLC-ECD methodology. The level of 8-oxoG relative to strand breaks produced by peroxynitrite was higher than that produced by Fe(II)-EDTA/H2O2 and gamma-radiation, which is consistent with the altered reactivity or accessibility of a non-hydroxyl radical species produced by peroxynitrite.

Analysis of HMW glutenin subunits encoded by chromosome 1A of bread wheat (Triticum aestivum L.) indicates quantitative effects on grain quality

A gene encoding the high-molecular-weight (HMW) subunit of glutenin 1Ax1 was isolated from bread wheat cv Hope. Comparison of the deduced amino acid sequence with that previously reported for an allelic subunit, 1Ax2(*), showed only minor differences, which were consistent with both subunits being associated with good bread-making quality. Quantitative analyses of total protein extracts from 22 cultivars of bread wheat showed that the presence of either subunit 1Ax1 or 1Ax2(*), when compared with a null allele, resulted in an increase in the proportion of HMW subunit protein from ca. 8 to 10% of the total. It is suggested that this quantitative increase in HMW subunit protein may account for the association of 1Ax subunits with good quality.