The Genetic Drivers of Juvenile, Young, and Early-Onset Parkinson's Disease in India

BACKGROUND

Recent studies have advanced our understanding of the genetic drivers of Parkinson's disease (PD). Rare variants in more than 20 genes are considered causal for PD, and the latest PD genome-wide association study (GWAS) identified 90 independent risk loci. However, there remains a gap in our understanding of PD genetics outside of the European populations in which the vast majority of these studies were focused.

OBJECTIVE

The aim was to identify genetic risk factors for PD in a South Asian population.

METHODS

A total of 674 PD subjects predominantly with age of onset (AoO) ≤50 years (encompassing juvenile, young, or early-onset PD) were recruited from 10 specialty movement disorder centers across India over a 2-year period; 1376 control subjects were selected from the reference population GenomeAsia, Phase 2. We performed various case-only and case-control genetic analyses for PD diagnosis and AoO.

RESULTS

A genome-wide significant signal for PD diagnosis was identified in the SNCA region, strongly colocalizing with SNCA region signal from European PD GWAS. PD cases with pathogenic mutations in PD genes exhibited, on average, lower PD polygenic risk scores than PD cases lacking any PD gene mutations. Gene burden studies of rare, predicted deleterious variants identified BSN, encoding the presynaptic protein Bassoon that has been previously associated with neurodegenerative disease.

CONCLUSIONS

This study constitutes the largest genetic investigation of PD in a South Asian population to date. Future work should seek to expand sample numbers in this population to enable improved statistical power to detect PD genes in this understudied group. © 2023 Denali Therapeutics and The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Parallel CRISPR-Cas9 screens identify mechanisms of PLIN2 and lipid droplet regulation

Despite the key roles of perilipin-2 (PLIN2) in governing lipid droplet (LD) metabolism, the mechanisms that regulate PLIN2 levels remain incompletely understood. Here, we leverage a set of genome-edited human PLIN2 reporter cell lines in a series of CRISPR-Cas9 loss-of-function screens, identifying genetic modifiers that influence PLIN2 expression and post-translational stability under different metabolic conditions and in different cell types. These regulators include canonical genes that control lipid metabolism as well as genes involved in ubiquitination, transcription, and mitochondrial function. We further demonstrate a role for the E3 ligase MARCH6 in regulating triacylglycerol biosynthesis, thereby influencing LD abundance and PLIN2 stability. Finally, our CRISPR screens and several published screens provide the foundation for CRISPRlipid (http://crisprlipid.org), an online data commons for lipid-related functional genomics data. Our study identifies mechanisms of PLIN2 and LD regulation and provides an extensive resource for the exploration of LD biology and lipid metabolism.

Identification of structurally diverse FSP1 inhibitors that sensitize cancer cells to ferroptosis

Ferroptosis is a regulated form of cell death associated with the iron-dependent accumulation of phospholipid hydroperoxides. Inducing ferroptosis is a promising approach to treat therapy-resistant cancer. Ferroptosis suppressor protein 1 (FSP1) promotes ferroptosis resistance in cancer by generating the antioxidant form of coenzyme Q10 (CoQ). Despite the important role of FSP1, few molecular tools exist that target the CoQ-FSP1 pathway. Through a series of chemical screens, we identify several structurally diverse FSP1 inhibitors. The most potent of these compounds, ferroptosis sensitizer 1 (FSEN1), is an uncompetitive inhibitor that acts selectively through on-target inhibition of FSP1 to sensitize cancer cells to ferroptosis. Furthermore, a synthetic lethality screen reveals that FSEN1 synergizes with endoperoxide-containing ferroptosis inducers, including dihydroartemisinin, to trigger ferroptosis. These results provide new tools that catalyze the exploration of FSP1 as a therapeutic target and highlight the value of combinatorial therapeutic regimes targeting FSP1 and additional ferroptosis defense pathways.

Protocol for performing pooled CRISPR-Cas9 loss-of-function screens

Phenotypic screens involving pooled CRISPR-Cas9 libraries offer a powerful, rapid yet affordable approach to evaluate gene functions on a global scale. Here, we present a protocol for performing pooled CRISPR-Cas9 loss-of-function screens to identify genetic modifiers using either fluorescence-based or cell death phenotypic readouts. We describe steps for designing and amplifying the library and generating and screening cells. We then detail deep sequencing and statistical analysis using cas9 High Throughput maximum Likelihood Estimator. For complete details on the use and execution of this protocol, please refer to Bersuker et al. (2019),¹ Li et al. (2022),² and Roberts et al. (2022).³.

VPS13A and VPS13C Influence Lipid Droplet Abundance

Lipid transfer proteins mediate the exchange of lipids between closely apposed membranes at organelle contact sites and play key roles in lipid metabolism, membrane homeostasis, and cellular signaling. A recently discovered novel family of lipid transfer proteins, which includes the VPS13 proteins (VPS13A-D), adopt a rod-like bridge conformation with an extended hydrophobic groove that enables the bulk transfer of membrane lipids for membrane growth. Loss of function mutations in VPS13A and VPS13C cause chorea acanthocytosis and Parkinson's disease, respectively. VPS13A and VPS13C localize to multiple organelle contact sites, including endoplasmic reticulum (ER) - lipid droplet (LD) contact sites, but the functional roles of these proteins in LD regulation remains mostly unexplored. Here we employ CRISPR-Cas9 genome editing to generate VPS13A and VPS13C knockout cell lines in U-2 OS cells via deletion of exon 2 and introduction of an early frameshift. Analysis of LD content in these cell lines revealed that loss of either VPS13A or VPS13C results in reduced LD abundance under oleate-stimulated conditions. These data implicate two lipid transfer proteins, VPS13A and VPS13C, in LD regulation.

Protein Quality Control and Lipid Droplet Metabolism

Lipid droplets (LDs) are endoplasmic reticulum-derived organelles that consist of a core of neutral lipids encircled by a phospholipid monolayer decorated with proteins. As hubs of cellular lipid and energy metabolism, LDs are inherently involved in the etiology of prevalent metabolic diseases such as obesity and nonalcoholic fatty liver disease. The functions of LDs are regulated by a unique set of associated proteins, the LD proteome, which includes integral membrane and peripheral proteins. These proteins control key activities of LDs such as triacylglycerol synthesis and breakdown, nutrient sensing and signal integration, and interactions with other organelles. Here we review the mechanisms that regulate the composition of the LD proteome, such as pathways that mediate selective and bulk LD protein degradation and potential connections between LDs and cellular protein quality control.

Organelle Biogenesis: ER Shape Influences Lipid Droplet Nucleation

Lipid droplets (LDs) are neutral lipid storage organelles assembled at the endoplasmic reticulum (ER). A new study reveals that the high membrane curvature of ER tubules catalyzes the nucleation of a neutral lipid lens, an early step in LD biogenesis.

The CoQ oxidoreductase FSP1 acts parallel to GPX4 to inhibit ferroptosis

Ferroptosis is a form of regulated cell death that is caused by the iron-dependent peroxidation of lipids1,2. The glutathione-dependent lipid hydroperoxidase glutathione peroxidase 4 (GPX4) prevents ferroptosis by converting lipid hydroperoxides into non-toxic lipid alcohols3,4. Ferroptosis has previously been implicated in the cell death that underlies several degenerative conditions2, and induction of ferroptosis by the inhibition of GPX4 has emerged as a therapeutic strategy to trigger cancer cell death5. However, sensitivity to GPX4 inhibitors varies greatly across cancer cell lines6, which suggests that additional factors govern resistance to ferroptosis. Here, using a synthetic lethal CRISPR-Cas9 screen, we identify ferroptosis suppressor protein 1 (FSP1) (previously known as apoptosis-inducing factor mitochondrial 2 (AIFM2)) as a potent ferroptosis-resistance factor. Our data indicate that myristoylation recruits FSP1 to the plasma membrane where it functions as an oxidoreductase that reduces coenzyme Q10 (CoQ) (also known as ubiquinone-10), which acts as a lipophilic radical-trapping antioxidant that halts the propagation of lipid peroxides. We further find that FSP1 expression positively correlates with ferroptosis resistance across hundreds of cancer cell lines, and that FSP1 mediates resistance to ferroptosis in lung cancer cells in culture and in mouse tumour xenografts. Thus, our data identify FSP1 as a key component of a non-mitochondrial CoQ antioxidant system that acts in parallel to the canonical glutathione-based GPX4 pathway. These findings define a ferroptosis suppression pathway and indicate that pharmacological inhibition of FSP1 may provide an effective strategy to sensitize cancer cells to ferroptosis-inducing chemotherapeutic agents.

Lipid disequilibrium disrupts ER proteostasis by impairing ERAD substrate glycan trimming and dislocation

The endoplasmic reticulum (ER) mediates the folding, maturation, and deployment of the secretory proteome. Proteins that fail to achieve their native conformation are retained in the ER and targeted for clearance by ER-associated degradation (ERAD), a sophisticated process that mediates the ubiquitin-dependent delivery of substrates to the 26S proteasome for proteolysis. Recent findings indicate that inhibition of long-chain acyl-CoA synthetases with triacsin C, a fatty acid analogue, impairs lipid droplet (LD) biogenesis and ERAD, suggesting a role for LDs in ERAD. However, whether LDs are involved in the ERAD process remains an outstanding question. Using chemical and genetic approaches to disrupt diacylglycerol acyltransferase (DGAT)-dependent LD biogenesis, we provide evidence that LDs are dispensable for ERAD in mammalian cells. Instead, our results suggest that triacsin C causes global alterations in the cellular lipid landscape that disrupt ER proteostasis by interfering with the glycan trimming and dislocation steps of ERAD. Prolonged triacsin C treatment activates both the IRE1 and PERK branches of the unfolded protein response and ultimately leads to IRE1-dependent cell death. These findings identify an intimate relationship between fatty acid metabolism and ER proteostasis that influences cell viability.

The two-minute walking test: a sensitive index of mobility in the rehabilitation of elderly patients

The usefulness of a timed walking test adapted for use as an index of mobility in elderly subjects undergoing rehabilitation was assessed. The 95% confidence interval for repeatability in 27 subjects was found to be -27% to +38%. The test was able to detect a significant improvement ( p < 0.01) in a group of subjects undergoing active rehabilitation, whereas no improvement was detected by a conventional rating scale. The two-minute walking test is a simple and sensitive index of mobility in the elderly.

Atlantic bluefin tuna Thunnus thynnus feeding ecology in the northern Gulf of Mexico: a preliminary description of diet from the western Atlantic spawning grounds

A combination of stomach contents, nitrogen stable-isotope and tissue C:N values are presented to demonstrate feeding activity of Atlantic bluefin tuna Thunnus thynnus on the Gulf of Mexico (GOMEX) spawning grounds. Diets include teleosts, cephalopods, crustaceans and a pelagic tunicate (Pyrosoma atlanticum). Results reveal the need to classify the GOMEX as a T. thynnus feeding ground.

Increased hyaluronan expression at distinct time points in acute lymphedema

Lymphatic dysfunction in lymphedema results in chronic accumulation of interstitial fluid and life-long tissue swelling. In the absence of restored lymphatic drainage via adequate lymphangiogenesis, the interstitial environment can remodel in ways that decrease the elevated interstitial stress. Presently, relatively little is known about the glycosaminoglycans (GAGs) that become upregulated in the interstitium during lymphedema. We employed a mouse tail model of acute lymphedema that reproduces important features of the chronic human condition to establish a relationship between hyaluronan (HA) and sulfated GAG concentration with tissue swelling. We found that HA was upregulated by tissue injury at day 5 and became upregulated again by skin swelling (HA content increasing by 27% relative to controls at days 15 and 20). Surprisingly, the second phase of HA expression was associated with the declining phase of the tail skin swelling (tail diameter significantly decreasing by 17% from day 10 peak to day 20), demonstrating that HA is upregulated by tissue swelling and may help to counteract the edema in the mouse tail. This finding was confirmed by intradermal injection of an HA degrading enzyme (hyaluronidase) to the swollen tail, which was found to worsen the tail swelling. Sulfated GAGs, including chondroitin sulfate (CS), were not regulated by tissue swelling. The results demonstrate that HA, but not sulfated GAGs, is upregulated in the interstitium by acute tissue swelling. We speculate that HA expression during lymphedema may be part of a natural adaptive mechanism of the interstitial environment to reduce capillary filtration and increase interstitial fluid outflow following lymphatic obstruction and fluid accumulation.

Liposome behavior in capillary electrophoresis

The behavior of liposomes in capillary electrophoresis is studied for the purpose of developing a potential method for characterizing liposomes prepared for use in industrial and analytical applications. This study characterizes the electrophoretic behavior of liposomes under various conditions to provide information about electrophoretic mobility and liposome-capillary surface interactions. The results of this method are compared with the results obtained using traditional laser light-scattering methods to obtain size information about liposome preparations. Additionally, reactions of liposomes and the surfactant n-octyl-β-d-glucopyranoside are performed off-line in bulk solution experiments and on-line in the capillary. Automated delivery of lysis agents by multiple electrokinetic injections is demonstrated as a general method for inducing on-capillary reactions between liposomes and other reagents. Furthermore, some preliminary evidence on the use of liposomes as a hydrophobic partitioning medium for analytical separations is presented.

[Rational antibacterial therapy of acute surgical diseases of abdominal organs]

Comparative analysis of medical documents, concerning 1055 patients, aged 18-92 yrs old, operated for an acute surgical diseases of abdominal organs in 2007-2009 yrs, was performed. Preoperative antibioticotherapy was performed in all the patients, in 877 of them ceftazidim (ceftadim) was administered as the main antibacterial preparation and in 178--other antibacterial preparations. Application of ceftadim, as a basic preparation in antibioticotherapy, had permitted to lower the purulent-septic complications rate by 61% and to reduce the stationary treatment duration of the patients.

Lymphangiogenesis-independent resolution of experimental edema

Vascular endothelial growth factor (VEGF)-C is necessary for lymphangiogenesis, and excess VEGF-C has been shown to be ameliorative for edema produced by lymphatic obstruction in experimental models. However, it has recently been shown that edema can resolve in the mouse tail even in the complete absence of capillary lymphangiogenesis when distal lymph fluid crosses the regenerating wound site interstitially. This finding has raised questions about the action of VEGF-C/VEGF receptor (VEGFR) signaling during the resolution of experimental edema. Here, the roles of VEGFR-2 and VEGFR-3 signaling in edema resolution were explored. It was found that edema resolved following neutralization of either VEGFR-2 or VEGFR-3 in the mouse tail skin, which inhibited lymphangiogenesis. Neutralization of either VEGFR-2 or VEGFR-3 reduced angiogenesis at the site of obstruction at day 10 (9.2 +/- 1.2% and 11.5 +/- 1.0% blood capillary coverage, respectively) relative to controls (14.3 +/- 1.5% blood capillary coverage). Combined VEGFR-2/-3 neutralization more strongly inhibited angiogenesis (6.9 +/- 1.5% blood capillary coverage), leading to a reduced wound repair of the lymphatic obstruction and extended edema in the tail skin. In contrast, improved tissue repair of the obstruction site increased edema resolution. Macrophages in the swollen tissue were excluded as contributing factors in the VEGFR-dependent extended edema. These results support a role for VEGFR-2/-3-combined signaling in the resolution of experimental edema that is lymphangiogenesis independent.

Survey of the characteristics of cats owned by households in the UK and factors affecting their neutered status

Data were collected on 1260 cats owned by a random sample of UK households in 2007, by means of telephone questionnaires, which were completed by 33 per cent of the households contacted. Cats were owned by 26 per cent of these households, 42 per cent of which owned more than one cat. The owners of 622 female cats reported a total of 110 unplanned litters of kittens. Excluding cats with an unknown neutered status 92 per cent of the cats aged six months or more were neutered, but only 66 per cent of the cats aged six to 12 months were neutered. Multivariable logistic regression, based on data collected for one randomly selected cat aged four months or more in each cat-owning household, was used to identify factors affecting the cats' neutered status. Analysis of 48 sexually entire cats and 501 neutered cats showed that cats aged 10 months or more, with indoor access, that had been vaccinated within the last year or were currently registered with a veterinary practice, were more likely to be neutered than cats aged less than 10 months, without indoor access, that had been vaccinated more than one year ago or were not registered with a veterinary practice.

The resolution of lymphedema by interstitial flow in the mouse tail skin

Lymphangiogenesis is considered a promising approach for increasing fluid drainage during secondary lymphedema. However, organization of lymphatics into functional capillaries may be dependent upon interstitial flow (IF). The present study was undertaken to determine the importance of lymphangiogenesis for lymphedema resolution. We created a lymphatic obstruction that produces lymphedema in mouse tail skin. The relatively scar-free skin regeneration that occurred across the obstruction allowed the progression of lymphangiogenesis to be observed and compared with the evolution of lymphedema. The role of vascular endothelial growth factor-C (VEGF-C)/VEGF receptor (VEGFR)-3 signaling in lymphedema resolution was investigated by exogenous administration of VEGF-C or neutralizing antibodies against VEGFR-3. VEGF-C protein improved lymphedema at 15 days [reducing dermal thickness from 742 ± 105 to 559 ± 141 μm with 95% confidence intervals (CIs), P < 0.05] without increasing lymphatic capillary coverage (11.6 ± 6.4% following VEGF-C treatment relative to 9.6 ± 6.2% with 95% CIs, P > 0.50). Blocking VEGFR-3 signaling did not inhibit lymphedema resolution at 25 days (dermal thickness of 462 ± 127 μm following VEGFR-3 inhibition relative to 502 ± 87 μm with 95% CIs) or inhibit IF, although VEGFR-3 blocking prevented lymphangiogenesis (reducing lymphatic coverage to 0.2 ± 0.7% relative to 8.7 ± 7.3% with 95% CIs, P < 0.005). A second mouse tail lymphedema model was employed to investigate the ability of VEGF-C to increase fluid drainage across a scar. We found that neither neutralization of VEGFR-3 nor administration of VEGF-C affected the course of skin swelling over 25 days. These findings suggest that resolution of lymphedema in the mouse tail skin may be more dependent upon IF and regeneration of the extracellular matrix across the obstruction than lymphatic capillary regeneration.

Fish oil for kidney transplant recipients

BACKGROUND

Calcineurin inhibitors used in kidney transplantation for immunosuppression have adverse effects that may contribute to nephrotoxicity and increased cardiovascular risk profile. Fish oils are rich in very long chain omega-3 fatty acids, which may reduce nephrotoxicity by improving endothelial function and reduce rejection rates through their immuno-modulatory effects. They may also modify the cardiovascular risk profile. Hence, fish oils may potentially prolong graft survival and reduce cardiovascular mortality.

OBJECTIVES

To assess the benefits and harms of fish oil supplementation on kidney transplant recipients on a calcineurin inhibitor-based immunosuppressive regimen.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL in The Cochrane Library, issue 2 2005), MEDLINE (1966-April 2005) and EMBASE (1980-April 2005).

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs of fish oils in kidney transplant recipients on a calcineurin inhibitor-based immunosuppressive regimen. RCTs of fish oil versus statins were included.

DATA COLLECTION AND ANALYSIS

Data was extracted and the quality of studies assessed by two authors, with differences resolved by discussion with a third independent author. Dichotomous outcomes were reported as relative risk (RR) and continuous outcome measures were reported as the mean difference (MD) with 95% confidence intervals using the random effects model. Heterogeneity was assessed using a Chi(2) test on n-1 degrees of freedom and the I(2) statistic. Data not suitable for pooling were tabulated and described.

MAIN RESULTS

Sixteen studies (733 patients) were suitable for analysis. Fish oil did not significantly affect patient or graft survival, acute rejection rates, calcineurin inhibitor toxicity or renal function, when compared to placebo. Fish oil treatment was associated with a lower diastolic blood pressure (MD 4.5 mmHg; P = 0.004) compared to placebo. Patients receiving fish oil for more than six months had a modest increase in HDL (MD 0.12 mmol/L; P = 0.01) compared to placebo. Fish oil effects on lipids were not significantly different from low-dose statins. There was insufficient data to analyse cardiovascular outcomes. Fishy aftertaste and gastrointestinal upset were common but did not result in significant patient drop-out.

AUTHORS' CONCLUSIONS

There is insufficient evidence from currently available RCTs to recommend fish oil therapy to improve renal function, rejection rates, patient survival or graft survival. The improvements in HDL cholesterol and diastolic blood pressure were too modest to recommend routine use. To determine a benefit in clinical outcomes, future RCTs will need to be adequately powered with these outcomes in mind.

A developmental study of the Tinker Toy test: normative and clinical observations

Tinker Toy test performance is presented for a normative group of 5- to 12-year-old children. Contrary to reported findings for some executive function tasks, developmental trends in Tinker Toy Test performance were not found. Results from a large group (N=55) of children who had sustained traumatic brain injury demonstrated that Tinker Toy Test performance was sensitive to the effects of traumatic brain injury and significantly associated with separate clinical ratings of functional or executive impairment. Present findings support the utility of the Tinker Toy Test as one component of the pediatric neuropsychological evaluation following traumatic brain injury.

Supernumerary pregnancy, collective harm, and two forms of the nonidentity problem

An interesting question, in both the moral and the legal context, is whether babies born of an infertility treatment-induced supernumerary pregnancy (or ITISP) are properly considered to have been harmed. One might wonder how such a question could even arise in the face of data that clearly demonstrate that ITISP leaves an unduly large number of babies blind, deaf, and palsied, and facing lifelong disabilities. In fact, however, a number of arguments, based on the problem of collective form and two forms of the so-called "nonidentity problem," challenge the claim of harm in the ITISP context. The purpose of the present paper is to establish, as against these arguments, that harm has been imposed on the ITISP-damaged offspring.

Single and serial measurements of cardiac troponin I in asymptomatic patients on chronic hemodialysis

AIMS

Coronary artery disease is the major cause of death in patients with end-stage renal failure on dialysis. This study aimed to assess the predictive value of a single cardiac troponin I (cTnI), and also the kinetics of serial values.

METHODS

Since cTnI is a potential biomarker of cardiac outcome, the present study examined single cTnI measurements (n = 88 patients) and its predictive value for future cardiac events, and a kinetic substudy of serial weekly cTnI measured for 8 weeks (n = 57) in a group of patients on hemodialysis.

RESULTS

Single cTnI measurements: 9 patients (10.2%) had a detectable cTnI at baseline and 79 patients (89.8%) had a negative baseline cTnI. There were no significant differences in age, sex, history of ischemic heart disease, diabetes, smoking or dyslipidemia between patients with detectable and negative cTnI. At the end of 9 months, the rate of combined primary endpoints, which included myocardial infarction, cardiac death and cardiac revascularization, was significantly higher in the patients with a detectable baseline cTnI (55.6%), compared to patients with a negative cTnI (6.3%) (p = 0.0007). Serial weekly cTnI measurements: significant fluctuations in cTnI were noted over time; 27% of patients with an undetectable cTnI measured at baseline had subsequent detectable levels in the serial follow-up.

CONCLUSION

A single detectable cTnI in asymptomatic patients on hemodialysis defines patients at high risk of future cardiac events. However, the incidence of detectable cTnI levels is markedly increased when serial weekly measurements are performed. The clinical significance of detectable serial measurements of cTnI is the focus of ongoing studies.

Treatment for lupus nephritis

BACKGROUND

Lupus nephritis is the renal manifestation of systemic lupus erythematosus (SLE) - a disease mainly affecting young women with substantial morbidity and mortality. It is classified by the World Health Organization (WHO) criteria I - VI based on histology. WHO Class IV is a diffuse proliferative glomerulonephritis which has the worst prognosis without treatment, with a reported 17% five year survival in the era 1953-1969. This survival was 82% in the early 1990's and continues to improve. An important factor behind this has been the use of cytotoxics such as cyclophosphamide in addition to steroids.

OBJECTIVES

To assess the benefits and harms of different treatments in biopsy-proven proliferative lupus nephritis (LN).

SEARCH STRATEGY

We searched the Cochrane Renal Group's specialised register (January 2003), the Cochrane Central Register of Randomised Controlled Trials (CENTRAL - The Cochrane Library issue 1, 2003), MEDLINE (1966 - 31 January 2003), EMBASE (1980 - 31 January 2003) and handsearched reference lists of retrieved articles.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing treatments for PLN in both adult and paediatric patients with Class III, IV, Vc, Vd lupus nephritis were included. All treatments were considered.

DATA COLLECTION AND ANALYSIS

Data was extracted and quality assessed independently by two reviewers, with differences resolved by discussion. Dichotomous outcomes are reported as relative risk (RR) and measurements on continuous scales are reported as weighted mean differences (WMD) with 95% confidence intervals. Subgroup analysis by study quality, drug type and drug route have been performed where possible to explore reasons for heterogeneity.

MAIN RESULTS

Of 920 articles identified, 25 were RCTs suitable for inclusion, which enrolled 915 patients. The majority compared cyclophosphamide or azathioprine plus steroids versus steroids alone. Cyclophosphamide plus steroids reduced the risk of doubling of serum creatinine (RR 0.59, 95% CI 0.40 to 0.88) compared to steroids alone but had no impact on mortality (RR 0.98, 95% CI 0.53 to 1.82). The risk of ovarian failure was significantly increased (RR 2.18, 95% CI 1.10 to 4.34). Azathioprine plus steroids reduced the risk of all cause mortality compared to steroids alone (RR 0.60, 95% CI 0.36 to 0.99), but did not alter renal outcomes. Neither therapy was associated with increased risk of major infection. No benefit was found with addition of plasma exchange to cyclophosphamide or azathioprine plus steroids for mortality ( RR 0.71, 95% CI 0.50 to 1.02), doubling of serum creatinine (RR 0.17, 95% CI 0.02 to 1.26) or end-stage renal failure (RR 1.24, 95% CI 0.60 to 2.57). There was also no increased risk of major infection (RR 0.69, 95% CI 0.35 to 1.37).

REVIEWER'S CONCLUSIONS

Until future RCTs of newer agents are completed, the current use of cyclophosphamide combined with steroids remains the best option to preserve renal function in proliferative LN. The smallest effective dose and shortest duration of treatment should be used to minimise gonadal toxicity, without compromising efficacy.

Molecular and mesoscale structures in hydrophobically driven aqueous solutions

Since Kauzmann's seminal 1959 paper, the hydrophobic interaction has dominated thinking on the forces that control protein folding and stability. Despite its wide importance in chemistry and biology, our understanding of this interaction at the molecular level remains poor, with little experimental evidence to support the idea of water ordering close to a non-polar group that is at the centre of the standard model for the source of the entropic driving force. Developments over recent years in neutron techniques now enable us to see directly how a non-polar group actually affects the molecular structure of the water in its immediate neighbourhood. On the basis of such work on aqueous solutions of small alcohols, the generally accepted standard model is found to be wanting, and alternative sources of the entropic driving force are suggested. Moreover, the fact that we can now follow changes in hydrogen bonding as the alcohol concentration is varied gives us the possibility of explaining the concentration dependence of the enthalpy of mixing. Complementary studies of solute association on the mesoscopic scale show a rich concentration and temperature behaviour, which reflects a complex balance of polar and non-polar interactions. Unravelling the detailed nature of this balance in simple aqueous amphiphiles may lead to a better understanding of the forces that control biomolecular structural stability and interactions.

Molecular analysis of the Drosophila miniature-dusky ( m-dy) gene complex: m-dy mRNAs encode transmembrane proteins with similarity to C. elegans cuticulin

Mutations in the Drosophila miniature-dusky ( m-dy) gene complex were first reported by Morgan and Bridges about 90 years ago. m-dy mutants have abnormally small wings, a phenotype attributed to a cell-autonomous reduction in the size of the epidermal cells comprising the differentiated wing. Using a molecular genetic approach, we have characterized the m-dy chromosomal interval and identified a pair of adjacent transcription units corresponding to m and dy. A dy mutant known as dy (And) has a single base substitution within the protein-coding region that is predicted to result in an amber stop codon and premature translational termination. We show that dy mRNA is expressed at two discrete periods during the life cycle--one during embryonic development and early larval instars, the second during adult development, coincident with wing differentiation. In agreement with the phenotypic similarity of m and dy mutants, sequence comparisons reveal a similarity between the predicted MINIATURE and DUSKY proteins, and indicate that the m and dy genes are members of a larger Drosophila gene family. Both m and dy, as well as other members of this superfamily, are predicted to encode transmembrane proteins with similarity to C. elegans cuticle proteins known as cuticulins. We postulate that m, dy and other members of this protein superfamily function as structural components of the Drosophila cuticulin layer. Such a role for m and dy products in wing differentiation is sufficient to explain the morphological phenotypes associated with m-dy mutants.

Microarray data analysis: a practical approach for selecting differentially expressed genes

BACKGROUND

The biomedical community is rapidly developing new methods of data analysis for microarray experiments, with the goal of establishing new standards to objectively process the massive datasets produced from functional genomic experiments. Each microarray experiment measures thousands of genes simultaneously producing an unprecedented amount of biological information across increasingly numerous experiments; however, in general, only a very small percentage of the genes present on any given array are identified as differentially regulated. The challenge then is to process this information objectively and efficiently in order to obtain knowledge of the biological system under study and by which to compare information gained across multiple experiments. In this context, systematic and objective mathematical approaches, which are simple to apply across a large number of experimental designs, become fundamental to correctly handle the mass of data and to understand the true complexity of the biological systems under study.

RESULTS

The present report develops a method of extracting differentially expressed genes across any number of experimental samples by first evaluating the maximum fold change (FC) across all experimental parameters and across the entire range of absolute expression levels. The model developed works by first evaluating the FC across the entire range of absolute expression levels in any number of experimental conditions. The selection of those genes within the top X% of highest FCs observed within absolute expression bins was evaluated both with and without the use of replicates. Lastly, the FC model was validated by both real time polymerase chain reaction (RT-PCR) and variance data. Semi-quantitative RT-PCR analysis demonstrated 73% concordance with the microarray data from Mu11K Affymetrix GeneChips. Furthermore, 94.1% of those genes selected by the 5% FC model were found to lie above measurement variability using a SDwithin confidence level of 99.9%.

CONCLUSION

As evidenced by the high rate of validation, the FC model has the potential to minimize the number of required replicates in expensive microarray experiments by extracting information on gene expression patterns (e.g. characterizing biological and/or measurement variance) within an experiment. The simplicity of the overall process allows the analyst to easily select model limits which best describe the data. The genes selected by this process can be compared between experiments and are shown to objectively extract information which is biologically & statistically significant.

Semantic processing in visual word recognition: activation blocking and domain specificity

Lexical decision to a target is typically facilitated when a related prime is simply read, but is typically eliminated if subjects carry out a letter search on the prime when probe and prime appear simultaneously. Three experiments involving the addition of a task-irrelevant word to this prime search paradigm address (1) Stolz and Besner's (1996, 1998) account in which semantic priming is eliminated because letter search on the prime instantiates an activation block between lexical and semantic levels of representation, (2) Chiappe, Smith, and Besner's (1996) account that activation blocking is domain specific, and (3) Neely and Kahan's (2001) claim that semantic activation is context independent and capacity free. The results are (1) consistent with the account that activation blocking is general to a level, rather than item specific, (2) consistent with the account that activation blocking is domain specific, and (3) inconsistent with the claim that semantic activation is context independent and capacity free.

Protein energy supplements in unwell elderly patients--a randomized controlled trial

BACKGROUND

To determine whether oral protein energy supplements, prescribed during hospitalization to elderly medical admissions, affect nutritional status and if baseline nutritional state influences this status. We also considered the effects on mortality, length of hospital stay, functional recovery, and institutionalization.

METHODS

A prospective randomized controlled trial with no placebo. Consenting patients were stratified in 3 nutritional categories, and patients from each stratum were randomized into treatment or control. Observers were blinded to randomization. The participants were emergency admissions from home to a Medicine for the Elderly Unit in a Scottish hospital. The inclusion criteria were as follows: no known malignancy, the ability to swallow, and nonobesity (BMI < 75th percentile). The intervention was a prescription of 120 mL sip feed, 3 times daily (540 kcal, 22.5 g protein per day) throughout hospitalization, using the medicine prescription chart. The trial was powered to detect change in mean percentage weight. The following outcomes were also considered: anthropometry; mortality, length of hospital stay, functional recovery, and rates of institutionalization.

RESULTS

Included in the trial were 381 patients. Nutritional supplementation was associated with significantly better energy intake (p = .001) and weight gain (p = .003) pooled across all nutritional categories. In the most poorly nourished patients, the intervention was associated with reduced mortality (5/34 versus 14/40, p < .05) and more patients improved functionally (17/25 versus 11/28, p < .04). Overall mortality results were 21/186 versus 33/195, odds ratio (OR) 0.62, 95% confidence interval (CI) 0.35, 1.13.

CONCLUSIONS

Prescribing sip feed supplements in the medicine prescription chart during hospital stay reduces weight loss. Our data also support other evidence for a reduction in mortality noted in elderly patients on nutritional supplementation. There were suggestions of other clinical benefits.

Genomics: food and nutrition

Nutrition is traditionally a multidisciplinary field applying principles of molecular biochemistry and statistical epidemiology to integrative metabolism and population health. Genomics, with its global perspective, is now reinventing the future of human metabolic health. Creative experimental designs are addressing metabolic questions in nutrition ranging from energy regulation to aging, and from mechanisms of absorption to the interspecies molecular crosstalk of bacteria and human cells within the intestine.

Genetic analysis of functional domains within the Drosophila LARK RNA-binding protein

LARK is an essential Drosophila RNA-binding protein of the RNA recognition motif (RRM) class that functions during embryonic development and for the circadian regulation of adult eclosion. LARK protein contains three consensus RNA-binding domains: two RRM domains and a retroviral-type zinc finger (RTZF). To show that these three structural domains are required for function, we performed a site-directed mutagenesis of the protein. The analysis of various mutations, in vivo, indicates that the RRM domains and the RTZF are required for wild-type LARK functions. RRM1 and RRM2 are essential for viability, although interestingly either domain can suffice for this function. Remarkably, mutation of either RRM2 or the RTZF results in the same spectrum of phenotypes: mutants exhibit reduced viability, abnormal wing and mechanosensory bristle morphology, female sterility, and flightlessness. The severity of these phenotypes is similar in single mutants and double RRM2; RTZF mutants, indicating a lack of additivity for the mutations and suggesting that RRM2 and the RTZF act together, in vivo, to determine LARK function. Finally, we show that mutations in RRM1, RRM2, or the RTZF do not affect the circadian regulation of eclosion, and we discuss possible interpretations of these results. This genetic analysis demonstrates that each of the LARK structural domains functions in vivo and indicates a pleiotropic requirement for both the LARK RRM2 and RTZF domains.

Separation of iota-, kappa and lambda-carrageenans by capillary electrophoresis

The present study reports a novel method for the separation of the high-molecular-weight anionic polysaccharides, iota, kappa, and lambda carrageenans, in capillary electrophoresis (CE). Carrageenan samples are first derivatised with 9-aminopyrene-1,4,6-trisulfonic acid (APTS), separated in an ammonium acetate background electrolyte (BGE) and detected with laser-induced fluorescence (LIF). The effects of changes of instrumental parameters (temperature, injection mode, field strength) and the composition of the BGE (concentration and pH) are reported, and are explained in terms of the physical chemistry of the BGE and the biopolymers. Optimal separation conditions for kappa, iota, and lambda carrageenans, including an APTS internal standard, were found in a polyvinyl alcohol coated capillary with an ammonium acetate BGE of low concentration (25 mM) and moderate pH (8.0). This BGE gave the best reproducibility in tests on iota/kappa mixtures, with relative standard deviations (RSDs) in migration times and normalised peak areas (relative to the APTS internal standard) of less than 0.1% and 1%, respectively. Using this BGE at 50 degrees C and a voltage of 30 kV, all three carrageenan subtypes were separated in a run time of 3 min.

Use of randomly amplified polymorphic DNA as a means of developing genus- and strain-specific Streptomyces DNA probes

We have analyzed 20 randomly amplified polymorphic DNA (RAPD) primers against 36 Streptomyces strains, including 17 taxonomically undefined strains, 25 nonstreptomycete actinomycetes, and 12 outgroups consisting of gram-positive and -negative species. Most of the primers were useful in identifying unique DNA polymorphisms of all strains tested. We have used RAPD techniques to develop a genus-specific probe, one not necessarily targeting the ribosomal gene, for Streptomyces, and a strain-specific probe for the biological control agent Streptomyces lydicus WYEC108. In the course of these investigations, small-scale DNA isolations were also developed for efficiently isolating actinomycete DNA. Various modifications of isolation procedures for soil DNA were compared, and the reliability and specificity of the RAPD methodology were tested by specifically detecting the S. lydicus WYEC108 in DNA isolated from soil.

Predictors of adult height and weight in boys treated with methylphenidate for childhood behavior problems

OBJECTIVE

To examine associations between childhood treatment with methylphenidate (MPH) and adult height and weight.

METHOD

Subjects were 97 boys, aged 4 to 12 years, with behavior problems who were (1) referred to a child psychiatry outpatient clinic, (2) treated clinically with MPH for an average of 36 months, and (3) reevaluated between ages 21 and 23 years. Hierarchical analyses predicted adult height and weight from sets of non-medication and medication-related variables.

RESULTS

Medicated subjects' age, height, and parental socioeconomic status (SES) at referral predicted 44.8% of variation in adult height. Medicated subjects' birth weight, age, height and weight at referral, and parental SES predicted 61.8% of variation in adult weight. With these non-medication variables held constant, initial nausea and vomiting side effects predicted 4.4% incremental variation in adult height, and MPH maintenance dose predicted 3.2% incremental variation in adult weight.

CONCLUSIONS

Medicated individuals who had attained their final stature did not differ in average height or weight from family, community, or unmedicated controls. Most aspects of medication were not associated with adult height or weight. In some individuals, nausea and vomiting side effects and treatment with higher doses of MPH were associated with adult growth decrements.

Cryosolvents useful for protein and enzyme studies below -100 degrees C

For the study of protein structure, dynamics, and function, at very low temperatures it is desirable to use cryosolvents that resist phase separation and crystallisation. We have examined these properties in a variety of cryosolvents. Using visual and X-ray diffraction criteria, methanol:ethanediol (70%:10%), methanol:glycerol (70%:10%), acetone:methoxy-ethanol:ethanediol (35%:35%:10%), dimethylformamide:ethanediol (70%:10%), dimethylformamide (80%), methoxyethanol (80%), and methoxyethanol:ethanediol (70%:10%) were all found to be free of phase-changes down to at least -160 degrees C. The least viscous of these, methanol:ethanediol (70%:10%), was miscible down to -125 degrees C and showed no exo or endothermic transitions when examined using DSC. It is therefore potentially particularly suitable for very low temperature cryoenzymology.

The use of cyclic voltammetry for the evaluation of antioxidant capacity

Low-molecular weight antioxidants (LMWAs) play a major role in protecting biological systems against reactive oxygen-derived species and reflect the antioxidant capacity of the system. Cyclic voltammetry (CV), shown to be convenient methodology, has been validated for quantitation of the LMWA capacity of blood plasma, tissue homogenates, and plant extracts. Analysis of the CV tracing yields the values of (i) the biological oxidation potential, E and E(1/2), which relate to the nature of the specific molecule(s); (ii) the intensity (Ia) of the anodic current; and (iii) the area of the anodic wave (S). Both Ia and S relate to the concentration of the molecule(s). LMWA components of human plasma and animal tissues were identified and further validated by reconstruction of the CV tracing and by high-performance liquid chromatography-electrochemical detection. To reflect the oxidative stress status, the use of an additional parameter, R, has been proposed. R represents the level (%) of oxidized ascorbate (compared with total ascorbate) and is measured by high-performance liquid chromatography-electrochemical detection. All these parameters were monitored in healthy human subjects as well as in chronic (diabetes mellitus) and acute care patients (subjected to total body irradiation before bone marrow transplantation). The electroanalytical methodologies presented here could be widely employed for rapid evaluation of the status of subjects (in health and disease) for monitoring of their response to treatment and/or nutritional supplementation as well as for screening of specific populations.

Organisation of services for acute stroke in Scotland--report of the Scottish stroke services audit

An audit was undertaken of hospital service provision for acute strokes in Scotland, using as a template key recommendations in the four SIGN guidelines on management of stroke. A questionnaire and structured interview was undertaken of key personnel in the 43 Trusts and three directly managed units providing in-patient stroke care in Scotland, and the 15 Health Boards commissioning stroke care. All Trusts and Health Boards participated and a complete set of information for each was recorded on a data-base and analysed. This report gives an overview for 14 key components of an integrated stroke service with results presented in four bands according to Trust type determined by the number of strokes admitted. No Trust provided all key components and for a few components a lack of provision was widespread, e.g. fast-track assessment clinics for TIA and minor stroke, access to CT scanning within 48 hours. Variation occurred between Trusts of similar size, between Trusts of different sizes. Overall the Health Boards were at a preliminary stage in the development of stroke specific service specifications. The results of the audit are a view of stroke services around April 1998, and should enable commissioners and providers to consider how to progress implementation of the clinical guidelines on stroke care.

Induction and characterization of Ph1 wheat mutants

The cloning of genes for complex traits in polyploid plants that possess large genomes, such as hexaploid wheat, requires an efficient strategy. We present here one such strategy focusing on the homologous pairing suppressor (Ph1) locus of wheat. This locus has been shown to affect both premeiotic and meiotic processes, possibly suggesting a complex control. The strategy combined the identification of lines carrying specific deletions using multiplex PCR screening of fast-neutron irradiated wheat populations with the approach of physically mapping the region in the rice genome equivalent to the deletion to reveal its gene content. As a result, we have located the Ph1 factor controlling the euploid-like level of homologous chromosome pairing to the region between two loci (Xrgc846 and Xpsr150A). These loci are located within 400 kb of each other in the rice genome. By sequencing this region of the rice genome, it should now be possible to define the nature of this factor.

An extraretinally expressed insect cryptochrome with similarity to the blue light photoreceptors of mammals and plants

Photic entrainment of insect circadian rhythms can occur through either extraretinal (brain) or retinal photoreceptors, which mediate sensitivity to blue light or longer wavelengths, respectively. Although visual transduction processes are well understood in the insect retina, almost nothing is known about the extraretinal blue light photoreceptor of insects. We now have identified and characterized a candidate blue light photoreceptor gene in Drosophila (DCry) that is homologous to the cryptochrome (Cry) genes of mammals and plants. The DCry gene is located in region 91F of the third chromosome, an interval that does not contain other genes required for circadian rhythmicity. The protein encoded by DCry is approximately 50% identical to the CRY1 and CRY2 proteins recently discovered in mammalian species. As expected for an extraretinal photoreceptor mediating circadian entrainment, DCry mRNA is expressed within the adult brain and can be detected within body tissues. Indeed, tissue in situ hybridization demonstrates prominent expression in cells of the lateral brain, which are close to or coincident with the Drosophila clock neurons. Interestingly, DCry mRNA abundance oscillates in a circadian manner in Drosophila head RNA extracts, and the temporal phasing of the rhythm is similar to that documented for the mouse Cry1 mRNA, which is expressed in clock tissues. Finally, we show that changes in DCry gene dosage are associated predictably with alterations of the blue light resetting response for the circadian rhythm of adult locomotor activity.

The epidemiology of women's rugby injuries

OBJECTIVE

The purpose of this study was to identify all injuries to members of an elite women's rugby team and to compare these injuries with published data on injuries in other women's contact and collision sports.

DESIGN

This was a prospective cohort observational study conducted using a monthly log completed by the team's certified athletic therapist to closely monitor attendance at practices and games along with the type and severity of injuries.

SETTING

Rugby games and practices held in Ontario, Quebec, and the Netherlands.

PARTICIPANTS

Forty members of the Ontario Women's Senior Provincial Rugby Team over the 1997 season and the 1998 World Championships.

MAIN OUTCOME MEASURES

An injury was defined as a rugby-related event that kept a player out of practice or competition for >24 hours or required the attention of a physician (e.g., suturing lacerations) and in addition included all dental, eye, and nerve injuries and concussions.

RESULTS

There were a total of 35 injuries in 4,958 player-hours and 2,926 athletic exposures. This resulted in a rugby injury rate of 7.1+/-0.4 per 1,000 player-hours and 12.0+/-2 per 1,000 athletic exposures.

CONCLUSION

The incidence of injuries in women's rugby is comparable with that in other women's contact and collision sports, indicating that the sport may be safer than stated in the literature and media.

Biogenesis and biological function of marine algal oxylipins

The biogenetic source of most marine algal oxylipins, which are many and of diverse structure, can logically be unified through a common lipoxygenase-derived hydroperoxide to epoxy allylic carbocation transformation. The biological role of oxylipins in algae remains an enigma, although numerous ideas have been put forth. Herein, we hypothesize and provide some evidence for an osmoregulatory role for these metabolites.

Serological response to influenza vaccination and nutritional and functional status of patients in geriatric medical long-term care

INTRODUCTION

in the UK the Department of Health recommends influenza vaccination for elderly people resident in institutional care. However, the efficacy of vaccination may be reduced in very frail elderly people with functional impairment, undernutrition and multiple pathologies. Nutritional and functional status is claimed to affect vaccine responses in healthy elderly subjects. We wished to determine if a relationship could be seen between nutritional and functional status and seroconversion in patients receiving long- term care.

METHODS

all patients in geriatric medical long-term care were offered vaccine. Consenting patients had pre- and post-vaccine serology measured using single radial haemolysis. Anthropometry was measured to enable body mass index (BMI) to be calculated. Functional independence was assessed using the 20-point Barthel index.

RESULTS

of 260 patients who received influenza vaccine, 137 (36 male, 101 female) consented to venesection for serology and thus form the study population. Mean age was 82 years (SD 7.9). The median Barthel score was 3/20 and the mean BMI was 21.6 (SD 4.6, range 13-36.2). Antibodies to influenza A were undetectable both pre- and post-vaccination in 63/137 patients. In 49 patients the antibody titre rose after vaccination and 25 had detectable antibody titres pre-vaccination which failed to rise post-vaccine. There were no significant associations between post-vaccination influenza antibody responses and BMI, Barthel score or age.

CONCLUSION

frail elderly patients in geriatric medical long-term care had a poor antibody response to influenza vaccination. Within this group, serological responses could not be predicted by nutritional or functional status.

Cognitive outcome in children and adolescents following severe traumatic brain injury: influence of psychosocial, psychiatric, and injury-related variables

Previous studies of childhood traumatic brain injury (TBI) have emphasized injury-related variables rather than psychiatric or psychosocial factors as correlates of cognitive outcomes. We addressed this concern by recruiting a consecutive series (N = 24) of children age 5 through 14 years who suffered a severe TBI, a matched group who sustained a mild TBI, and a second matched group who sustained an orthopedic injury. Standardized intellectual, memory, psychiatric, family functioning, family psychiatric history, neurological, and neuroimaging assessments were conducted at an average of 2 years following injury. Severe TBI, when compared to mild TBI and orthopedic injury, was associated with significant decrements in intellectual and memory function. A principal components analysis of independent variables that showed significant (p < .05) bivariate correlations with the outcome measures yielded a neuropsychiatric factor encompassing severity of TBI indices and postinjury psychiatric disorders and a psychosocial disadvantage factor. Both factors were independently and significantly related to intellectual and memory function outcome. Postinjury psychiatric disorders added significantly to severity indices and family functioning and family psychiatric history added significantly to socioeconomic status in explaining several specific cognitive outcomes. These results may help to define subgroups of children who will require more intensive services following their injuries.

Angular resolution of parallel foils on a synchrotron powder diffractometer

In an attempt to improve the resolution in flat-plate diffraction geometry, a new set of parallel foils, 100 microm spacing, 365 mm long with an aperture of 20 x 20 mm(2), has been commissioned. The study was carried out using the two-circle diffractometer of station 2.3 at the SRS. In order to properly quantify the improvements, a detailed and comparative study of the instrumental resolution using the new and existing foils, of 200 micron spacing, is reported. A number of cubic materials, BaF2, Si and CeO2, that are known to show well defined Bragg peaks over the full 2theta angular range available, were investigated.

Small-scale isolation of genomic DNA from Streptomyces mycelia or spores

We have developed a small-scale method for isolating high-quality chromosomal DNA from Streptomyces species. The entire procedure may be carried out in 2-mL microcentrifuge tubes in one day. It has been tested both quantitatively and qualitatively to ensure reliability and reproducibility. DNA yields from a variety of Streptomyces species ranged from 30 micrograms DNA/50 mg cells to over 225 micrograms DNA/50 mg cells. We used the method to isolate DNA from cells grown in liquid culture, on solid media and from spore suspensions. DNA yields and quality were assessed by spectrophotometry, restriction endonuclease digestion and random-amplified polymorphic DNA-PCR (RAPD-PCR) analysis. These confirmed that this procedure is an efficient method for isolating large amounts of high-quality DNA from a wide range of Streptomyces species.

A simple PCR-based method for scoring the ph1b deletion in wheat

The amplified fragment length polymorphism (AFLP) technique was used to isolate DNA sequences present in the euploid wheat Chinese Spring but not in the Chinese Spring ph1b mutant (which has a deletion of the Ph1 gene, a suppressor of homoeologous chromosome pairing). The polymorphic DNA fragments identified by AFLP were then cloned, sequenced, and used to design two primer pairs. These primers were used in a PCR-based assay to specifically amplify products from the Chinese Spring euploid but not from the ph1b mutant. This PCR assay can be carried out from extracted genomic DNA or directly from alkaline-treated wheat leaves, and the reaction products can be scored on a plus-minus basis, making the screening amenable to automation. The reliability of the assay was tested using a F1-derived doubled-haploid population of 55 lines which segregate for the ph1b deletion. This PCR-screening technique is less time and labour consuming, and more accurate and reliable, than cytologically based conventional methods.

Redefining reductive sulfate assimilation in higher plants: a role for APS reductase, a new member of the thioredoxin superfamily?

The reaction steps leading from the intermediate adenosine 5'-phosphosulfate (APS) to sulfide within the higher plant reductive sulfate assimilation pathway are the subject of controversy. Two pathways have been proposed: a 'bound intermediate' pathway in which the sulfo group of APS is first transferred by APS sulfotransferase to a carrier molecule to form a bound sulfite intermediate and is then further reduced by thiosulfonate reductase to bound sulfide; and a 'free intermediate' pathway in which APS is further activated to 3'-phosphoadenosine 5'-phosphosulfate (PAPS) by APS kinase followed by reduction of the sulfo group to free sulfite by PAPS reductase. Sulfite is then reduced to free sulfide by sulfite reductase. Sulfide, either free or bound, is then incorporated into organic form (as cysteine) by the enzyme O-acetylserine (thiol) lyase. In order to better characterize the pathway we attempted to clone PAPS reductase cDNAs by functional complementation of an Escherichia coli cysH mutant to prototrophy. We found no evidence for PAPS reductase cDNAs but did identify cDNAs that encode a small family of novel, chloroplast-localized proteins with APS reductase activity that are new members of the thioredoxin superfamily. We show here that the thioredoxin domain of these proteins is functional. We speculate that rather than proceeding via either of the pathways proposed above, reductive sulfate assimilation proceeds via the reduction of APS to sulfite by APS reductase and the subsequent reduction of sulfite to sulfide by sulfite reductase. In this scheme the product of the APS kinase reaction, PAPS, is not a direct intermediate in the pathway but rather acts as a substrate for sulfotransferase action and perhaps as a store of activated sulfate that can be returned to the pathway as APS via phosphohydrolase action on PAPS. Interactions between enzyme isoforms within the chloroplast stroma may bring about substrate channeling of APS and contribute to the partitioning of APS between sulfotransferase reactions on the one hand and the synthesis of cysteine and related metabolites via the reductive sulfate assimilation pathway on the other.