Fine mapping of the tomato I-3 gene for fusarium wilt resistance and elimination of a co-segregating resistance gene analogue as a candidate for I-3

The I-3 gene from the wild tomato species Lycopersicon pennellii confers resistance to race 3 of the devastating vascular wilt pathogen Fusarium oxysporum f. sp. lycopersici. As an initial step in a positional cloning strategy for the isolation of I-3, we converted restriction fragment length polymorphism and conserved orthologue set markers, known genes and a resistance gene analogue (RGA) mapping to the I-3 region into PCR-based sequence characterised amplified region (SCAR) and cleaved amplified polymorphic sequence (CAPS) markers. Additional PCR-based markers in the I-3 region were generated using the randomly amplified DNA fingerprinting (RAF) technique. SCAR, CAPS and RAF markers were used for high-resolution mapping around the I-3 locus. The I-3 gene was localised to a 0.3-cM region containing a RAF marker, eO6, and an RGA, RGA332. RGA332 was cloned and found to correspond to a putative pseudogene with at least two loss-of-function mutations. The predicted pseudogene belongs to the Toll interleukin-1 receptor-nucleotide-binding site-leucine-rich-repeat sub-class of plant disease resistance genes. Despite the presence of two RGA332 homologues in L. esculentum, DNA gel blot and PCR analysis suggests that no other homologues are present in lines carrying I-3 that could be alternative candidates for the gene.

Application of the quartz crystal microbalance to the evaporation of colloidal suspension droplets

An investigation into the evaporation of sessile droplets of latex and clay particle suspensions is presented in this work. The quartz crystal microbalance (QCM) has been used to study the interfacial phenomena during the drying process of these droplets. Characteristic changes of the crystal oscillating frequency and crystal resistance (damping of the oscillating energy) have been observed and related to the different stages of the evaporation process. Measurements have been made for latex particle sizes from 1.9 to 10 microm and for rough and polished crystals using drops from 0.3 to 1.5 microL. The behavior of the QCM is shown to depend strongly on the size of particles present and on the morphology of the crystal surface. One of the most striking features is a drastic damping of the oscillation energy and corresponding rise in frequency observed during the final stages of evaporation, particularly for the clay suspensions.

Long-distance signaling in nodulation directed by a CLAVATA1-like receptor kinase

Proliferation of legume nodule primordia is controlled by shoot-root signaling known as autoregulation of nodulation (AON). Mutants defective in AON show supernodulation and increased numbers of lateral roots. Here, we demonstrate that AON in soybean is controlled by the receptor-like protein kinase GmNARK (Glycine max nodule autoregulation receptor kinase), similar to Arabidopsis CLAVATA1 (CLV1). Whereas CLV1 functions in a protein complex controlling stem cell proliferation by short-distance signaling in shoot apices, GmNARK expression in the leaf has a major role in long-distance communication with nodule and lateral root primordia.

Thyroid function in mixed and pure manic episodes

OBJECTIVES

Associations of both overt thyroid disease as well as subclinical thyroid abnormalities with affective disorders have been well established. Similar associations have been reported with mixed mania and rapid cycling bipolar disorder. We tested for differences in overt and subclinical thyroid disease and subclinical differences in a large series of bipolar patients examined during mixed or pure manic episodes.

METHODS

Rates of previously diagnosed thyroid disease were compared by sex, race and manic subtype (mixed versus pure) in 443 patients. Serum thyroid stimulating hormone (TSH) and free thyroxine (FT4) concentrations obtained from patients with no clinical thyroid disease collected during manic and mixed bipolar episodes were compared using ANOVA statistics. Race was also included in the model and age was covaried.

RESULTS

Rates of thyroid disease, in particular hypothyroidism, were higher in females and white people, and increased with advancing age. No differences were noted between subjects sampled during mixed or pure manic episodes. In patients with no history of thyroid disease, serum TSH and FT4 concentrations did not differ between manic subtypes or between sexes. TSH levels however, were significantly lower in African Americans.

CONCLUSIONS

We did not confirm past reports of associations of overt or subclinical thyroid disease with mixed manic episodes. African Americans had significantly lower serum TSH concentrations than white people, while FT4 levels did not differ.

Inheritance and mapping of 11 avirulence genes in Phytophthora sojae

Two new crosses involving four races (races 7, 16, 17, and 25) of the soybean root and stem rot pathogen Phytophthora sojae were established (7/16 cross; 17/25 cross). An F2 population derived from each cross was used to determine the genetic basis of avirulence towards 11 different resistance genes in soybean. Avirulence was found to be dominant and determined by a single locus for Avr1b, 1d, 1k, 3b, 4, and 6, as expected for a simple gene-for-gene model. We also observed several cases of segregation, inconsistent with a single dominant gene being solely responsible for avirulence, which suggests that the genetic background of the different crosses can affect avirulence. Avr4 and 6 cosegregated in both the 7/16 and 17/25 crosses and, in the 7/16 cross, Avr1b and 1k were closely linked. Information from segregating RAPD, RFLP, and AFLP markers screened on F2 progeny from the two new crosses and two crosses described previously (a total of 212 F2 individuals, 53 from each cross) were used to construct an integrated genetic linkage map of P. sojae. This revised genetic linkage map consists of 386 markers comprising 35 RFLP, 236 RAPD, and 105 AFLP markers, as well as 10 avirulence genes. The map is composed of 21 major linkage groups and seven minor linkage groups covering a total map distance of 1640.4cM.

Sociodemographic and clinical predictors of mortality in geriatric depression

OBJECTIVE

It is well documented that depression and early mortality are related, and current research suggests that depression may influence vascular causes of death. The authors report on prospectively observed mortality in elderly depressed patients, comparing differences in sex and vascular risk.

METHODS

The subjects were 338 patients with unipolar major depression; patients with neurological or other psychiatric disorders were excluded. All subjects received a clinical evaluation and a standardized interview to establish DSM-III depression diagnosis. The cohort had a mean age of 67.2 years and was followed up at approximately 10 years from last contact.

RESULTS

Mortality was associated with older age, older age at depression onset, and being male. Also, in men, mortality was associated with higher baseline CES-D scores, and, in women, with having a higher vascular risk rating or late age at depression onset.

CONCLUSION

This is the first study demonstrating a gender-by-vascular condition interaction effect on mortality. Women with vascular risk factors may require closer follow-up to control vascular conditions. The relationship between greater depression and increased mortality risk among men is interesting, and further studies will be required to replicate and understand it.

Ageing, stress and the brain

Ageing of the brain is an important factor in overall ageing and mortality, and new insights have clarified the relationship between neuroregulation and ageing. First, neuronal loss in normal ageing is now known to be a minor change. Loss of synapses through dystrophic neuronal change is the hallmark of normal ageing. Second, similar dystrophic changes occur in the brain with chronic stress. In both instances, forebrain sites experience loss of synaptic input from brainstem regulatory nuclei. Third, functional ageing is attributed in part to lifetime stress, under the concept of 'allostatic load'. Being inseparable from the functions of appraising and responding to stress, the brain is an ultimate mediator of stress-related mortality, through hormonal changes that lead to proximate pathologies like hypertension, glucose intolerance, cardiovascular disease and immunological impairment. In chronic stress the brain shows clear allostatic compensations that lead to pathology. Two subtle and chronic mechanisms that may mediate brain pathology and accelerated ageing in chronic stress are proposed. These are abnormal glucocorticoid receptor (GR) occupancy over the 24 h cycle, and elevated body temperature. These factors lead to GR-mediated tissue changes and to acceleration of general cellular ageing mechanisms. Human depression is discussed as an exemplary demonstration of these principles.

Hypocholesterolemia during mixed manic episodes

BACKGROUND

An association of relatively low serum cholesterol with both depression and suicide has been reported. Depressive symptoms, including suicidality, are defining features of mixed mania. Few studies have considered differences in cholesterol levels in subjects during mixed bipolar episodes.

METHODS

Fasting serum cholesterol levels obtained from 174 subjects evaluated during mixed and pure manic episodes were compared using ANOVA statistics. Sex was included in the analysis and age was used as a covariate. Cholesterol levels in the total manic cohort and in the mixed and pure manic subgroups were compared with national norms.

RESULTS

Fasting serum cholesterol levels were lower in the mixed manic subtype compared to the pure manic subtype. As expected, cholesterol levels increased with age. No differences were noted between males and females. Cholesterol levels were lower in both the mixed and pure manic subtypes when compared with national norms.

CONCLUSION

Fasting serum cholesterol levels are low in manic patients, especially during mixed bipolar episodes. Cholesterol, which has been reported to be a negative acute phase reactant, may be lower during mixed states as a result of an immune activation.

Symptom profile consistency in recurrent manic episodes

Few studies have addressed whether symptom profiles remain consistent between episodes of mania. Those that have done so focused on mood only and adopted the strictly categorical approach. We evaluated 77 subjects during two discrete manic episodes (mean interval, 2 years, 2 weeks). Episodes were characterized on five established symptom factors of mania and on overall severity of classic manic symptoms (i.e., excluding dysphoric symptoms). Pearson correlation coefficients were computed to compare symptom profiles across episodes. Four symptom factors (dysphoria, hedonic activation, psychosis, and irritable aggression) were significantly correlated across episodes, as was manic severity. Psychomotor symptoms were not significantly correlated. Manic symptomatology remains generally similar in bipolar subjects during different episodes. The characterization of manic episodes by the empirical dimensions of symptom factors, as suggested by Kraepelin nearly a century ago, may provide additional information for biological and treatment response studies of manic states that is not captured by categorical subtype diagnosis focused solely on mood symptoms (i.e., mixed v pure manic episodes).

Effects of ECT on Polysomnographic Sleep: A Prospective Investigation

The authors describe a pilot investigation using ambulatory polysomnography (PSG) to assess rapid eye movement (REM) latency in 11 depressed inpatients before and after a course of electroconvulsive therapy (ECT). Prior to beginning ECT, all subjects had REM latencies of 56 minutes or less (mean 22 min). A course of ECT was associated with clinical improvement in every patient and a statistically significant (p < 0.0002) increase of 67% in mean REM latency (37 min). However, individual patients showed marked variability in REM latency both during and after the course of ECT, and 7 of the 11 responders continued to exhibit shortened REM latencies of 34 min or less. Technical considerations related to PSG studies during ECT are reviewed and the clinical and theoretical implications of our findings are discussed.

Vascular risk factors in late onset mania

BACKGROUND

Previous researches have suggested that late onset mania is a distinct subtype associated with medical and neurological disorders. Few studies, however, have focused on vascular risk factors.

METHODS

Records of 366 bipolar patients were reviewed and age of first psychiatric hospitalization determined. Late-onset cases were determined empirically from a distribution histogram. Late onset cases were matched to early onset cases and histories of vascular disease/risks and current cholesterol levels compared.

RESULTS

The distribution of age of first psychiatric hospitalization was bimodal with an intermode at age 47. Using that threshold, 6.3% of the cohort was classified as having late onset mania. Vascular risks factors were greater and current cholesterol levels higher in the late onset group.

CONCLUSIONS

Late onset mania is associated with greater vascular risk factors. The bimodal appearance of age of first psychiatric hospitalization in this study provides further support of late onset mania as a distinct manic subtype with possibly a different, vascular aetiology. Control of these vascular risks may impact on the incidence of late onset mania, as well as on its clinical management.

Seasonal variation of mixed and pure episodes of bipolar disorder

BACKGROUND

Although seasonal patterns of manic episodes have been reported, the seasonal variation of mixed states of bipolar disorder has received little attention. In the current report we address that concern as well as the overall seasonality of manic episodes.

METHODS

The seasonal pattern of 304 psychiatric hospital admissions for treatment of mixed or manic bipolar episodes over a 3-year period were analyzed employing two definitions of mixed manic states: DSM-III-R and an ROC derived definition.

RESULTS

The frequency of all manic episodes combined peaked in early spring, with a nadir in late fall. Pure manic admissions showed a similar pattern. Mixed manic admissions had a significantly different pattern, with a peak in late summer and a nadir in November. The differences between pure and mixed manic admissions were demonstrated with the use of the ROC definition for mixed states.

LIMITATIONS

Effects of medications and medication non-compliance may dampen natural seasonal patterns of episodes.

CONCLUSIONS

The different seasonal pattern of mixed and pure manic episodes support the separation of mixed episodes as a distinct clinical subtype.

Randomly Amplified DNA Fingerprinting: A Culmination of DNA Marker Technologies Based on Arbitrarily-Primed PCR Amplification

Arbitrarily-primed DNA markers can be very useful for genetic fingerprinting and for facilitating positional cloning of genes. This class of technologies is particularly important for less studied species, for which genome sequence information is generally not known. The technologies include Randomly Amplified Polymorphic DNA (RAPD), DNA Amplification Fingerprinting (DAF), and Amplified Fragment Length Polymorphism (AFLP). We have modified the DAF protocol to produce a robust PCR-based DNA marker technology called Randomly Amplified DNA Fingerprinting (RAF). While the protocol most closely resembles DAF, it is much more robust and sensitive because amplicons are labelled with either radioactive 33P or fluorescence in a 30-cycle PCR, and then separated and detected on large polyacrylamide sequencing gels. Highly reproducible RAF markers were readily amplified from either purified DNA or alkali-treated intact leaf tissue. RAF markers typically display dominant inheritance. However, a small but significant portion of the RAF markers exhibit codominant inheritance and represent microsatellite loci. RAF compares favorably with AFLP for efficiency and reliability on many plant genomes, including the very large and complex genomes of sugarcane and wheat. While the two technologies detect about the same number of markers per large polyacrylamide gel, advantages of RAF over AFLP include: (i) no requirement for enzymatic template preparation, (ii) one instead of two PCRs, and (iii) overall cost. RAF and AFLP were shown to differ in the selective basis of amplification of markers from genomes and could therefore be used in complementary fashion for some genetic studies.

Leukocytosis and hypoalbuminemia in mixed bipolar states: evidence for immune activation

OBJECTIVE

Although activation of an immune response during major depressive episodes has been reported, less is known about changes during manic and mixed bipolar episodes.

METHOD

Albumin and leukocyte levels were compared between subjects in manic and mixed bipolar episodes. Neutrophil, lymphocyte and monocyte levels were compared between the two groups.

RESULTS

Albumin levels were lower in mixed manic subjects as opposed to pure manic subjects and in the combined groups levels were lower in females than in males. Leukocyte levels were higher in mixed manic patients compare with pure manic patients. Both neutrophil and monocyte levels were higher in the mixed manic patients but lymphocyte levels were no different.

CONCLUSION

Leukocytosis and hypoalbuminemia during mixed manic states suggest immune activation in mixed mania similar to depression. This finding also tends to support the recognition of mixed mania as a distinct bipolar state.

A DNA fingerprinting procedure for ultra high-throughput genetic analysis of insects

Existing procedures for the generation of polymorphic DNA markers are not optimal for insect studies in which the organisms are often tiny and background molecular information is often non-existent. We have used a new high throughput DNA marker generation protocol called randomly amplified DNA fingerprints (RAF) to analyse the genetic variability in three separate strains of the stored grain pest, Rhyzopertha dominica. This protocol is quick, robust and reliable even though it requires minimal sample preparation, minute amounts of DNA and no prior molecular analysis of the organism. Arbitrarily selected oligonucleotide primers routinely produced approximately 50 scoreable polymorphic DNA markers, between individuals of three independent field isolates of R. dominica. Multivariate cluster analysis using forty-nine arbitrarily selected polymorphisms generated from a single primer reliably separated individuals into three clades corresponding to their geographical origin. The resulting clades were quite distinct, with an average genetic difference of 37.5 +/- 6.0% between clades and of 21.0 +/- 7.1% between individuals within clades. As a prelude to future gene mapping efforts, we have also assessed the performance of RAF under conditions commonly used in gene mapping. In this analysis, fingerprints from pooled DNA samples accurately and reproducibly reflected RAF profiles obtained from individual DNA samples that had been combined to create the bulked samples.

A prospective study of inter-episode consistency of manic and mixed subtypes of bipolar disorder

BACKGROUND

Few studies have compared symptom presentations across manic or mixed episodes in manic-depressive patients.

METHODS

In the current study we report on symptom presentations of 68 prospectively-evaluated subjects diagnosed with Bipolar Disorder during two discrete manic or mixed episodes. Each episode was categorized using DSM-IIIR criteria for Bipolar Disorder, manic or mixed, as well as a less restrictive definition for manic and mixed states derived from receiver operating characteristic (ROC) analysis of symptoms.

RESULTS

The occurrence of mixed bipolar episodes was not random using either the DSM-IIIR or ROC-derived definitions of mixed episodes.

LIMITATIONS

Subjects were not all fully medication-free at the time of evaluation which may have altered symptom presentation. The total duration of the study was limited, with the longest inter-episode interval under 6 years.

CONCLUSIONS

Although there was variability in mixed symptomatology between episodes, the occurrence of mixed episodes was not random. Manic and mixed episodes tend to recur true to type.

Corticotropin secretory dynamics in humans under low glucocorticoid feedback

To explore the mechanisms of homeostatic adaptation of the hypothalamo-pituitary-adrenal axis to an experimental low-feedback condition, we quantitated pulsatile (ultradian), entropic (pattern-sensitive), and 24-h rhythmic (circadian) ACTH secretion during high-dose metyrapone blockade (2 g orally every 2 h for 12 h, and then 1 g every 2 h for 12 h). Plasma ACTH and cortisol concentrations were sampled concurrently every 10 min for 24 h in nine adults. The metyrapone regimen reduced the amplitude of nyctohemeral cortisol rhythm by 45% (P = 0.0013) and delayed the time of the cortisol maximum (acrophase) by 7.1 h (P = 0.0002). Attenuated cortisol negative feedback stimulated a 7-fold increase in the mean (24-h) plasma ACTH concentration, which rose from 24 +/- 1.6 to 169 +/- 31 pg/ml (ng/liter) (P < 0.0001). Augmented ACTH output was driven by a 12-fold amplification of ACTH secretory burst mass (integral of the underlying secretory pulse) (21 +/- 3.1 to 255 +/- 64 pg/ml; P < 0.0001), yielding a higher percentage of ACTH secreted in pulses (53 +/- 3.5 vs. 92 +/- 1.3%; P < 0.0001). There were minimal elevations in basal (nonpulsatile) ACTH secretion (by 50%; P = 0.0049) and ACTH secretory burst frequency (by 36%; P = 0.031). The estimated half-life of ACTH (median, 22 min) and the calculated ACTH secretory burst half-duration (pulse event duration at half-maximal amplitude) (median, 23 min) did not change. Hypocortisolemia evoked remarkably more orderly subordinate patterns of serial ACTH release, as quantitated by the approximate entropy statistic (P = 0.003). This finding was explained by enhanced regularity of successive ACTH secretory pulse mass values (P = 0.032). In contrast, there was no alteration in serial ACTH interpulse-interval (waiting-time) regularity. At the level of 24-h ACTH rhythmicity, cortisol withdrawal enhanced the daily rhythm in ACTH secretory burst mass by 29-fold, elevated the mesor by 16-fold, and delayed the acrophase by 3.4 h from 0831 h to 1154 h (each P < 10(-3)). In summary, short-term glucocorticoid feedback deprivation primarily (>97% of effect) amplifies pulsatile ACTH secretory burst mass, while minimally elevating basal/nonpulsatile ACTH secretion and ACTH pulse frequency. Reduced cortisol feedback paradoxically elicits more orderly (less entropic) patterns of ACTH release due to emergence of more regular ACTH pulse mass sequences. Cortisol withdrawal concurrently heightens the amplitude and mesor of 24-h rhythmic ACTH release and delays the timing of the ACTH acrophase. In contrast, the duration of underlying ACTH secretory episodes is not affected, which indicates that normal pulse termination may be programmed centrally rather than imposed by rapid negative feedback. Accordingly, we hypothesize that adrenal glucocorticoid negative feedback controls hypothalamo-pituitary-adrenal axis dynamics via the 3-fold distinct mechanisms of repressing the mass of ACTH secretory bursts, reducing the orderliness of the corticotrope release process, and modulating the intrinsic diurnal rhythmicity of the hypothalamo-corticotrope unit.

Subtypes of mania determined by grade of membership analysis

Classical descriptions of mania subtypes extend back to Kraepelin; however, in marked contrast to the study of depression subtypes, validation of mania subtypes by multivariate statistical methods has seldom been attempted. We applied Grade of Membership (GOM) analysis to the rated clinical features of 327 inpatients with DSM-III-R mania diagnoses. GOM is a type of latent structure multivariate analysis, which differs from others of this type in making no a priori distributional assumptions about groupings. We obtained 5 GOM Pure Types with good face validity. The major Kraepelinian forms of "hypomania," "acute mania," "delusional mania," and "depressive or anxious mania" were validated. The major new finding is of two mixed mania presentations, each with marked lability of mood. The first of these displayed a dominant mood of severe depression with labile periods of pressured, irritable hostility and paranoia, and the complete absence of euphoria or humor. The second mixed mania Pure Type displayed a true, incongruous mixture of affects: periods of classical manic symptoms with euphoria, elation, humor, grandiosity, psychosis, and psychomotor activation, switching frequently to moderately depressed mood with pressured anxiety and irritability. This multivariate analysis validated classical clinical descriptions of the major subtypes of mania. Two distinct forms of mixed manic episodes were identified. DSM-III-R criteria did not reliably identify either of these two natural groups of mixed bipolar patients. As occurs in depression, this clinical heterogeneity of mania may influence response to drug treatments.