Can latent fingerprint disclose the sex of the donor? A preliminary test study using GC-MS analysis of latent fingerprints.

While fingerprints are a highly used means of identification, not every fingerprint left behind on a potential crime scene can be used for identification purposes. In some cases, the fingerprint may be smudged, partially preserved or overlapping with other prints hence distorting the ridge pattern and may therefore be not appropriate for identification. Further, fingermark residue yields a very low abundance of genetic material for DNA analysis. In such cases, the fingermark may be used to retrieve basic donor information such as sex. The focus of this paper was to assess the possibility of differentiating between the sexes of the donor of latent fingermarks. Analytical method was GC-MS analysis of the chemical compounds of latent fingermarks using 22 male and 22 female donors. Results showed 44 identified compounds. Two alcohols, octadecanol C18 and eicosanol C20 , were found to show a difference that was statistically significant between male and female donors. There is also some evidence for the possibility of distinguishing sex of the fingermark donor based on the distribution of branched chain fatty acids, as free compounds or esterified in wax esters.

Vertebral fracture as a risk factor for self-harm: a retrospective cohort study.

BACKGROUND: The prevention of self-harm is an international public health priority. It is vital to identify at-risk populations, particularly as self-harm is a risk factor for suicide. This study aims to examine the risk of self-harm in people with vertebral fractures. METHODS: Retrospective cohort study. Patients with vertebral fracture were identified within the Clinical Practice Research Datalink and matched to patients without fracture by sex and age. Incident self-harm was defined by primary care record codes following vertebral fracture. Overall incidence rates (per 10,000 person-years (PY)) were reported. Cox regression analysis determined risk (hazard ratios (HR), 95 % confidence interval (CI)) of self-harm compared to the matched unexposed cohort. Initial crude analysis was subsequently adjusted and stratified by median age and sex. RESULTS: The number of cases of vertebral fracture was 16,293, with a matched unexposed cohort of the same size. Patients were predominantly female (70.1 %), median age was 76.3 years. Overall incidence of self-harm in the cohort with vertebral fracture was 12.2 (10.1, 14.8) /10,000 PY. There was an initial crude association between vertebral fracture and self-harm, which remained after adjustment (HR 2.4 (95 %CI 1.5, 3.6). Greatest risk of self-harm was found in those with vertebral fractures who were aged below 76.3 years (3.2(1.8, 5.7)) and male (3.9(1.8, 8.5)). CONCLUSIONS: Primary care patients with vertebral fracture are at increased risk of self-harm compared to people without these fractures. Male patients aged below 76 years of age appear to be at greatest risk of self-harm. Clinicians need to be aware of the potential for self-harm in this patient group.

Rheumatic Conditions as Risk Factors for Self-Harm: A Retrospective Cohort Study.

OBJECTIVE: To examine the risk of self-harm in rheumatic conditions. METHODS: We conducted a retrospective cohort study using data from the Clinical Practice Research Datalink. Patients with ankylosing spondylitis, fibromyalgia, osteoarthritis, or rheumatoid arthritis were identified from 1990 to 2016 and matched to patients without these conditions. Incident self-harm was defined by medical record codes following a rheumatic diagnosis. Incidence rates (per 10,000 person-years) were reported for each condition, both overall and year-on-year (2000-2016). Cox regression analysis determined risk (hazard ratio [HR] and 95% confidence interval [95% CI]) of self-harm for each rheumatic cohort compared to the matched unexposed cohort. Initial crude analysis was subsequently adjusted and stratified by age and sex. Due to nonproportionality over time, osteoarthritis was also stratified by disease duration (<1 year, ≥1 to <5 years, ≥5 to <10 years, and ≥10 years). RESULTS: The incidence of self-harm was highest in patients with fibromyalgia (HR 25.12 [95% CI 22.45-28.11] per 10,000 person-years) and lowest for osteoarthritis (HR 6.48 [95% CI 6.20-6.76]). There was a crude association with each rheumatic condition and self-harm, except for ankylosing spondylitis. Although attenuated, these associations remained after adjustment for fibromyalgia (HR 2.06 [95% CI 1.60-2.65]), rheumatoid arthritis (HR 1.59 [95% CI 1.20-2.11]), and osteoarthritis (1 to <5 years HR 1.12 [95% CI 1.01-1.24]; ≥5 to <10 years HR 1.35 [95% CI 1.18-1.54]). Age and sex were weak effect modifiers for these associations. CONCLUSION: Primary care patients with fibromyalgia, osteoarthritis, or rheumatoid arthritis (but not ankylosing spondylitis) are at increased risk of self-harm compared to people without these rheumatic conditions. Clinicians need to be aware of the potential for self-harm in patients with rheumatic conditions (particularly fibromyalgia), explore mood and risk with them, and offer appropriate support and management.

Development and Quality of Barley Husk Adhesion Correlates With Changes in Caryopsis Cuticle Biosynthesis and Composition.

The caryopses of barley become firmly adhered to the husk during grain development through a cuticular cementing layer on the caryopsis surface. The degree of this attachment varies among cultivars, with poor quality adhesion causing "skinning", an economically significant grain quality defect for the malting industry. Malting cultivars encompassing a range of husk adhesion qualities were grown under a misting treatment known to induce skinning. Development of the cementing layer was examined by electron microscopy and compositional changes of the cementing layer were investigated with gas-chromatography followed by mass spectroscopy. Changes in gene expression during adhesion development were examined with a custom barley microarray. The abundance of transcripts involved early in cuticular lipid biosynthesis, including those encoding acetyl-CoA carboxylase, and all four members of the fatty acid elongase complex of enzymes, was significantly higher earlier in caryopsis development than later. Genes associated with subsequent cuticular lipid biosynthetic pathways were also expressed higher early in development, including the decarbonylation and reductive pathways, and sterol biosynthesis. Changes in cuticular composition indicate that lowered proportions of alkanes and higher proportions of fatty acids are associated with development of good quality husk adhesion, in addition to higher proportions of sterols.

Influence of Plant Species, Tissue Type, and Temperature on the Capacity of Shiga-Toxigenic Escherichia coli To Colonize, Grow, and Be Internalized by Plants.

Contamination of fresh produce with pathogenic Escherichia coli, including Shiga-toxigenic E. coli (STEC), represents a serious risk to human health. Colonization is governed by multiple bacterial and plant factors that can impact the probability and suitability of bacterial growth. Thus, we aimed to determine whether the growth potential of STEC for plants associated with foodborne outbreaks (two leafy vegetables and two sprouted seed species) is predictive of the colonization of living plants, as assessed from growth kinetics and biofilm formation in plant extracts. The fitness of STEC isolates was compared to that of environmental E. coli isolates at temperatures relevant to plant growth. Growth kinetics in plant extracts varied in a plant-dependent and isolate-dependent manner for all isolates, with spinach leaf lysates supporting the highest rates of growth. Spinach extracts also supported the highest levels of biofilm formation. Saccharides were identified to be the major driver of bacterial growth, although no single metabolite could be correlated with growth kinetics. The highest level of in planta colonization occurred on alfalfa sprouts, though internalization was 10 times more prevalent in the leafy vegetables than in sprouted seeds. Marked differences in in planta growth meant that the growth potential of STEC could be inferred only for sprouted seeds. In contrast, biofilm formation in extracts related to spinach colonization. Overall, the capacity of E. coli to colonize, grow, and be internalized within plants or plant-derived matrices was influenced by the isolate type, plant species, plant tissue type, and temperature, complicating any straightforward relationship between in vitro and in planta behaviors.IMPORTANCE Fresh produce is an important vehicle for STEC transmission, and experimental evidence shows that STEC can colonize plants as secondary hosts, but differences in the capacity to colonize occur between different plant species and tissues. Therefore, an understanding of the impact that these plant factors have on the ability of STEC to grow and establish is required for food safety considerations and risk assessment. Here, we determined whether growth and the ability of STEC to form biofilms in plant extracts could be related to specific plant metabolites or could predict the ability of the bacteria to colonize living plants. Growth rates for sprouted seeds (alfalfa and fenugreek) but not those for leafy vegetables (lettuce and spinach) exhibited a positive relationship between plant extracts and living plants. Therefore, the detailed variations at the level of the bacterial isolate, plant species, and tissue type all need to be considered in risk assessment.

Mirtazapine added to SSRIs or SNRIs for treatment resistant depression in primary care: phase III randomised placebo controlled trial (MIR).

OBJECTIVE: To investigate the effectiveness of combining mirtazapine with serotonin-noradrenaline reuptake inhibitor (SNRI) or selective serotonin reuptake inhibitor (SSRI) antidepressants for treatment resistant depression in primary care. DESIGN: Two parallel group multicentre phase III randomised placebo controlled trial. SETTING: 106 general practices in four UK sites; Bristol, Exeter, Hull, and Keele/North Staffs, August 2013 to October 2015. PARTICIPANTS: 480 adults aged 18 or more years who scored 14 or more on the Beck depression inventory, second revision, fulfilled ICD-10 (international classification of diseases, 10th revision) criteria for depression, and had used an SSRI or SNRI for at least six weeks but were still depressed. 241 were randomised to mirtazapine and 239 to placebo, both given in addition to usual SSRI or SNRI treatment. Participants were stratified by centre and minimised by baseline Beck depression inventory score, sex, and current psychological therapy. They were followed up at 12, 24, and 52 weeks. 431 (89.8%) were included in the (primary) 12 week follow-up. MAIN OUTCOME MEASURES: Depressive symptoms at 12 weeks after randomisation, measured using the Beck depression inventory II score as a continuous variable. Secondary outcomes included measures of anxiety, quality of life, and adverse effects at 12, 24, and 52 weeks. RESULTS: Beck depression inventory II scores at 12 weeks were lower in the mirtazapine group after adjustment for baseline scores and minimisation or stratification variables, although the confidence interval included the null (mean (SD) scores at 12 weeks: 18.0 (12.3) in the mirtazapine group, 19.7 (12.4) in the placebo group; adjusted difference between means -1.83 (95% confidence interval -3.92 to 0.27); P=0.09). Adverse effects were more common in the mirtazapine group and were associated with the participants stopping the trial drug. CONCLUSION: This study did not find evidence of a clinically important benefit for mirtazapine in addition to an SSRI or SNRI over placebo in a treatment resistant group of primary care patients with depression. This remains an area of important unmet need where evidence of effective treatment options is limited. TRIAL REGISTRATION: Current Controlled Trials ISRCTN06653773.

A feasibility study for NOn-Traditional providers to support the management of Elderly People with Anxiety and Depression: The NOTEPAD study Protocol.

BACKGROUND: Anxiety and depression are common among older people, with up to 20% reporting such symptoms, and the prevalence increases with co-morbid chronic physical health problems. Access to treatment for anxiety and depression in this population is poor due to a combination of factors at the level of patient, practitioner and healthcare system. There is evidence to suggest that older people with anxiety and/or depression may benefit both from one-to-one interventions and group social or educational activities, which reduce loneliness, are participatory and offer some activity. Non-traditional providers (support workers) working within third-sector (voluntary) organisations are a valuable source of expertise within the community but are under-utilised by primary care practitioners. Such a resource could increase access to care, and be less stigmatising and more acceptable for older people. METHODS: The study is in three phases and this paper describes the protocol for phase III, which will evaluate the feasibility of recruiting general practices and patients into the study, and determine whether support workers can deliver the intervention to older people with sufficient fidelity and whether this approach is acceptable to patients, general practitioners and the third-sector providers. Phase III of the NOTEPAD study is a randomised controlled trial (RCT) that is individually randomised. It recruited participants from approximately six general practices in the UK. In total, 100 participants aged 65 years and over who score 10 or more on PHQ9 or GAD7 for anxiety or depression will be recruited and randomised to the intervention or usual general practice care. A mixed methods approach will be used and follow-up will be conducted 12 weeks post-randomisation. DISCUSSION: This study will inform the design and methods of a future full-scale RCT. TRIAL REGISTRATION: ISRCTN, ID: ISRCTN16318986 . Registered 10 November 2016. The ISRCTN registration is in line with the World Health Organization Trial Registration Data Set. The present paper represents the original version of the protocol. Any changes to the protocol will be communicated to ISRCTN.

Twins as Participants in Randomized Controlled Trials: A Review of Published Literature.

Monozygotic (MZ) and dizygotic (DZ) twins participate in research that partitions variance in health, disease, and behavior into genetic and environmental components. However, there are other innovative roles for twins in medical research. One such way is involving MZ and/or DZ twins in co-twin control-designed randomized controlled trials (RCTs). To our knowledge, no reviews have been conducted that summarizes the involvement of twins in RCTs. Therefore, we conducted a systematic literature search using the U.S. Clinical Trials Database, NHS electronic databases, MEDLINE, EMBASE, and PsychINFO for RCTs on publications involving MZ and/or DZ twins as RCT participants. Out of the 186,027 clinical trials registered in the U.S. clinical trial register ClinicaTrails.gov, only six RCTs used twins as participants. From 1,598 articles identified in our search, 50 peer-reviewed English language publications met our pre-defined inclusion criteria. Sample sizes for RCTs have ranged from a total number of participants from 2 to 1,162; however, 32 (64%) studies had a sample size of 100 or less, and of those, 12 (24%) had fewer than 10. Both MZ and DZ twins have been recruited to the RCTs. In most instances (33/50) each twin from a pair were assigned to different study arms. Most of those studies included MZ twins only. Despite the methodological advantages, the use of MZ and DZ twins as participants in interventional RCTs appeared limited. The continuous development of innovative twin designs, especially RCTs, indicates that twin research can extend beyond the more widely recognized heritability estimates.

Field-based Evaluation of a Novel SPME-GC-MS Method for Investigation of Below-ground Interaction between Brassica Roots and Larvae of Cabbage Root Fly, Delia radicum L.

INTRODUCTION: Collection of volatiles from plant roots poses technical challenges due to difficulties accessing the soil environment without damaging the roots. OBJECTIVES: To validate a new non-invasive method for passive sampling of root volatiles in situ, from plants grown under field conditions, using solid phase micro-extraction (SPME). METHODS: SPME fibres were inserted into perforated polytetrafluoroethene (PTFE) tubes positioned in the soil next to broccoli plants for collection of root volatiles pre- and post-infestation with Delia radicum larvae. After sample analysis by gas chromatography-mass spectrometry (GC-MS), principal component analysis (PCA) was applied to determine differences in the profiles of volatiles between samples. RESULTS: GC-MS analysis revealed that this method can detect temporal changes in root volatiles emitted before and after Delia radicum damage. PCA showed that samples collected pre- and post-infestation were compositionally different due to the presence of root volatiles induced by D. radicum feeding. Sulphur containing compounds, in particular, accounted for the differences observed. Root volatiles emission patterns post-infestation are thought to follow the feeding and developmental progress of larvae. CONCLUSION: This study shows that volatiles released by broccoli roots can be collected in situ using SPME fibres within perforated PTFE tubes under field conditions. Plants damaged by Delia radicum larvae could be distinguished from plants sampled pre-infestation and soil controls on the basis of larval feeding-induced sulphur-containing volatiles. These results show that this new method is a powerful tool for non-invasive sampling of root volatiles below-ground. Copyright © 2016 John Wiley & Sons, Ltd.

Development and Validation of a SPME-GC-MS Method for In situ Passive Sampling of Root Volatiles from Glasshouse-Grown Broccoli Plants Undergoing Below-Ground Herbivory by Larvae of Cabbage Root Fly, Delia radicum L.

INTRODUCTION: Research on plant root chemical ecology has benefited greatly from recent developments in analytical chemistry. Numerous reports document techniques for sampling root volatiles, although only a limited number describe in situ collection. OBJECTIVES: To demonstrate a new method for non-invasive in situ passive sampling using solid phase micro extraction (SPME), from the immediate vicinity of growing roots. METHODS: SPME fibres inserted into polyfluorotetrafluoroethylene (PTFE) sampling tubes located in situ which were either perforated, covered with stainless steel mesh or with microporous PTFE tubing, were used for non-invasive sub-surface sampling of root volatiles from glasshouse-grown broccoli. Sampling methods were compared with above surface headspace collection using Tenax TA. The roots were either mechanically damaged or infested with Delia radicum larvae. Principal component analysis (PCA) was used to investigate the effect of damage on the composition of volatiles released by broccoli roots. RESULTS: Analyses by gas chromatography-mass spectrometry (GC-MS) with SPME and automated thermal desorption (ATD) confirmed that sulphur compounds, showing characteristic temporal emission patterns, were the principal volatiles released by roots following insect larval damage. Use of SPME with in situ perforated PTFE sampling tubes was the most robust method for out-of-lab sampling. CONCLUSION: This study describes a new method for non-invasive passive sampling of volatiles in situ from intact and insect damaged roots using SPME. The method is highly suitable for remote sampling and has potential for wide application in chemical ecology/root/soil research. Copyright © 2016 John Wiley & Sons, Ltd.

Relationship between volatile profile and sensory development of an oat-based biscuit.

The shelf-life of plain oatcakes and oatcakes containing a natural antioxidant (rosemary extract) was studied for 28 weeks. The biscuits were evaluated using several chemical analyses to determine oxidation (headspace analysis, free fatty acids profile, peroxide value and anisidine value), in addition to sensory testing. A selection of volatiles, including hexanal, were found to be positively correlated to three sensory parameters (aroma, flavour and aftertaste). These volatiles, responsible for the perception of off-flavour in oat biscuits, were predominantly secondary lipid breakdown products, primarily from the unsaturated fatty acids C18:1 and C18:2. The peroxide value was also found to be a useful tool to assess oxidation in oatcakes. The impact of the antioxidant was insufficient at the concentration tested to be used as a solution to prevent the development of off-flavour; however the antioxidant did appear to slow down the rancidity process.

Comparison of two headspace sampling techniques for the analysis of off-flavour volatiles from oat based products.

Two different headspace sampling techniques were compared for analysis of aroma volatiles from freshly produced and aged plain oatcakes. Solid phase microextraction (SPME) using a Carboxen-Polydimethylsiloxane (PDMS) fibre and entrainment on Tenax TA within an adsorbent tube were used for collection of volatiles. The effects of variation in the sampling method were also considered using SPME. The data obtained using both techniques were processed by multivariate statistical analysis (PCA). Both techniques showed similar capacities to discriminate between the samples at different ages. Discrimination between fresh and rancid samples could be made on the basis of changes in the relative abundances of 14-15 of the constituents in the volatile profiles. A significant effect on the detection level of volatile compounds was observed when samples were crushed and analysed by SPME-GC-MS, in comparison to undisturbed product. The applicability and cost effectiveness of both methods were considered.

Utilisation of the MVA pathway to produce elevated levels of the sesquiterpene α-copaene in potato tubers.

Potato flavour is a complex trait resulting from the presence of a combination of volatile and non-volatile compounds. The aim of this work was to investigate the effect of specifically altering the volatile content of tubers and assess its impact on flavour. Tuber-specific over-expression of a potato α-copaene synthase gene resulted in enhanced levels (up to 15-fold higher than controls) of the sesquiterpene α-copaene. A positive correlation (R(2)=0.8) between transgene expression level and α-copaene abundance was observed. No significant changes in the levels of volatiles other than α-copaene were detected. Non-volatile flavour compounds (sugars, glycoalkaloids, major umami amino acids and 5'-ribonucleotides) were also determined. Relationships between flavour compounds and sensory evaluation data were investigated. Evaluators could not detect any aroma differences in the transgenic samples compared with controls and no significant differences in taste attributes were found. Thus although successful engineering of potato tubers to accumulate high levels of the flavour volatile α-copaene was achieved, sensory analysis suggests that α-copaene is not a major component of potato flavour.

Relationships between volatile and non-volatile metabolites and attributes of processed potato flavour.

Although the flavour of processed potatoes (Solanum tuberosum L.) is important to consumers, the blend of volatile and non-volatile metabolites that impact on flavour attributes is not well-defined. Additionally, it is important to understand how potato flavour changes during storage. In this study, quantitative descriptive analysis of potato samples by a trained taste panel was undertaken, comparing tubers from S. tuberosum group Phureja with those from S. tuberosum group Tuberosum, both at harvest and following storage. The cooked tuber volatile profile was analysed by solid phase micro extraction followed by gas chromatography-mass spectrometry analysis in sub-samples of the tubers that were assessed by taste panels. A range of non-volatile metabolites including the major umami compounds, glycoalkaloids and sugars was also measured in tuber sub-samples. Correlation and principal component analyses revealed differences between the potato cultivars and storage conditions and demonstrated associations of metabolites with the different sensory attributes.

A metabolomics study of cultivated potato (Solanum tuberosum) groups Andigena, Phureja, Stenotomum, and tuberosum using gas chromatography-mass spectrometry.

Phytochemical diversity was examined by gas chromatography-mass spectrometry in tubers of genotypes belonging to groups Andigena, Phureja, Stenotomum, and Tuberosum of the potato, Solanum tuberosum. Polar extracts (mainly amino acids, organic acids, sugars, and sugar alcohols) and nonpolar extracts (mainly fatty acids, fatty alcohols, and sterols) were examined. There was a large range in levels of metabolites, including those such as asparagine, fructose, and glucose, that are important to tuber quality, offering considerable scope for selecting germplasm for breeding programmes. There were significant differences in the levels of many metabolites among the groups. The metabolite profiles of genotypes belonging to Phureja and Stenotomum were similar and different from those of Tuberosum and the majority of Andigena genotypes. There was some agreement with the phylogeny of the groups in that Stenotomum is believed to be the ancestor of Phureja and they are both distinct from Tuberosum. Andigena genotypes could be partially distinguished according to geographical origin, Bolivian genotypes being particularly distinct from those from Ecuador. Biosynthetic links between metabolites were explored by performing pairwise correlations of all metabolites. The significance of some expected and unexpected strong correlations between many amino acids (e.g., between isoleucine, lysine, valine, and other amino acids) and between several nonpolar metabolites (e.g., between many fatty acids) is discussed. For polar metabolites, correlation analysis gave essentially similar results irrespective of whether the whole data set, only Andigena genotypes, or only Phureja genotypes were used. In contrast, for the nonpolar metabolites, Andigena only and Phureja only data sets resulted in weaker and stronger correlations, respectively, compared to the whole data set, and may suggest differences in the biochemistry of the two groups, although the interpretation should be viewed with some caution.

Effect of disease severity and dopaminergic medication on recollection and familiarity in patients with idiopathic nondementing Parkinson's.

The effect of disease severity and dopaminergic medication on the assessment of familiarity and the recollection of episodic details during recognition in nondementing idiopathic Parkinson's is uncertain. Some studies have reported familiarity as deficient in mild Parkinson's yet others have found it intact even in moderate Parkinson's. Recollection has been found to be both preserved and deficient in mild and moderate Parkinson's. The extent to which these conflicting findings are explained by disease severity or dopaminergic medication or a combination of the two is uncertain, as all studies assessed patients in a medicated state, and disease severity has not always been consistently reported. Twelve patients with mild Parkinson's and 11 with moderate Parkinson's (medicated Hoehn and Yahr mean: 2.1 and 3.2, respectively), completed matched versions of a yes/no recognition memory test in a medicated and unmedicated condition (termed ON and OFF, respectively). Twenty-one matched healthy volunteers also completed both memory tasks in 2 separate sessions (termed Blue and Green, respectively). In the ON/Green condition, the moderate Parkinson's recollection performance was significantly poorer than the healthy volunteers and mild Parkinson's. By contrast, recognition memory and familiarity measures in both Parkinson's group were relatively spared. In the OFF/Blue condition, the moderate Parkinson's recollection was impaired, but only in relation to the healthy volunteer set. There were no significant differences in recollection performance between the mild and moderate Parkinson's groups. Again, recognition memory and familiarity measures in both Parkinson's group were relatively spared. Further analyses showed the moderate patients' recollection rates to be significantly poorer ON-medication compared to OFF. These findings are discussed in relation to the staging of disease progression on medial temporal areas which separately support recollection and familiarity, and the putative effects the different classes of dopaminergic drugs may have on these areas.

Transcriptional and metabolic profiles of Lolium perenne L. genotypes in response to a PEG-induced water stress.

Metabolic profiling was carried out in the forage grass Lolium perenne L. (perennial ryegrass) to uncover mechanisms involved in the plants response to water stress. When leaf and root materials from two genotypes, with a contrasting water stress response, were analysed by GC-MS, a clear difference in the metabolic profiles of the leaf tissue under water stress was observed. Differences were principally due to a reduction in fatty acid levels in the more susceptible Cashel genotype and an increase in sugars and compatible solutes in the more tolerant PI 462336 genotype. Sugars with a significant increase included: raffinose, trehalose, glucose, fructose and maltose. Increasing the ability of perennial ryegrass to accumulate these sugars in response to a water deficit may lead to more tolerant varieties. The metabolomics approach was combined with a transcriptomics approach in the water stress tolerant genotype PI 462336, which has identified perennial ryegrass genes regulated under water stress.

Expression profiling of potato germplasm differentiated in quality traits leads to the identification of candidate flavour and texture genes.

Quality traits such as flavour and texture are assuming a greater importance in crop breeding programmes. This study takes advantage of potato germplasm differentiated in tuber flavour and texture traits. A recently developed 44,000-element potato microarray was used to identify tuber gene expression profiles that correspond to differences in tuber flavour and texture as well as carotenoid content and dormancy characteristics. Gene expression was compared in two Solanum tuberosum group Phureja cultivars and two S. tuberosum group Tuberosum cultivars; 309 genes were significantly and consistently up-regulated in Phureja, whereas 555 genes were down-regulated. Approximately 46% of the genes in these lists can be identified from their annotation and amongst these are candidates that may underpin the Phureja/Tuberosum trait differences. For example, a clear difference in the cooked tuber volatile profile is the higher level of the sesquiterpene alpha-copaene in Phureja compared with Tuberosum. A sesquiterpene synthase gene was identified as being more highly expressed in Phureja tubers and its corresponding full-length cDNA was demonstrated to encode alpha-copaene synthase. Other potential 'flavour genes', identified from their differential expression profiles, include those encoding branched-chain amino acid aminotransferase and a ribonuclease suggesting a mechanism for 5'-ribonucleotide formation in potato tubers on cooking. Major differences in the expression levels of genes involved in cell wall biosynthesis (and potentially texture) were also identified, including genes encoding pectin acetylesterase, xyloglucan endotransglycosylase and pectin methylesterase. Other gene expression differences that may impact tuber carotenoid content and tuber life-cycle phenotypes are discussed.

Phytochemical diversity in tubers of potato cultivars and landraces using a GC-MS metabolomics approach.

Phytochemical diversity with respect to a range of polar (including amino acids, organic acids, sugars, and sugar alcohols) and nonpolar (including fatty acids, alkanols, and sterols) metabolites was examined within tubers from a total of 29 genetically diverse potato cultivars and Chilean landraces using a metabolomics approach by gas chromatography-mass spectrometry. From principal component analysis of the polar and nonpolar metabolite data there was insufficient variation to differentiate the majority of cultivars and landraces. Analysis of all polar metabolite profiles revealed separation of two cultivars (Glenna and Morag) from the other cultivars and landraces and a separate cluster of one landrace line, largely due to higher levels of sugars. Pentland Javelin was distinct in containing high levels of many amino acids. The two Solanum tuberosum group phureja cultivars (Inca Sun and Mayan Gold) were not particularly similar and were not separated from the S. tuberosum group tuberosum cultivars. Analysis of the nonpolar metabolite data revealed partial separation of two landrace lines and, on the basis of some minor fatty acids, Mayan Gold was distinct. The differences in metabolite profiles are considered in terms of the taxonomy and breeding history of the cultivars and possible influences from other factors such as developmental stage of the tuber. With a view to exploring biosynthetic links between metabolites, a pairwise correlation analysis was performed on all metabolites. The significance of high correlations between many amino acids and between several nonpolar metabolites is discussed.