Characterization of California Isolates of Fusarium oxysporum f. sp. vasinfectum

Thirty isolates of Fusarium oxysporum f. sp. vasinfectum from California, Australia, China, and the American Type Culture Collection were characterized by partial sequences of translational elongation factor (EF-1α), phosphate permase (PHO), and beta-tubulin (BT) genes, restriction digests of the intergenic spacer (IGS) region of nuclear rDNA, and pathogenicity tests. Based on phylogenetic analysis of combined sequences of EF-1α, PHO, and BT genes, California isolates represented four lineages. Lineage I contained race 3, lineage II contained races 1, 2, and 6, lineage III contained race 8, and lineage IV contained race 4. The Australian isolates formed a strongly supported independent clade. There were nine haplotypes based on restriction digests of the IGS region. In greenhouse pathogenicity tests with California isolates, those from the race 4 lineage were highly aggressive on certain Pima cotton (Gossypium barbadense) cultivars and less aggressive on Upland cotton (Gossypium hirsutum) cultivars. All isolates belonging to the other lineages caused relatively mild symptoms on both Pima and Upland cultivars. This is the first report of the occurrence of races 3, 4, and 8 in California.

Reducing tobacco addiction through tobacco product regulation

Tobacco product regulation has the potential to help reduce tobacco attributable disease by reducing the toxicity of these products and by reducing the prevalence of tobacco use and addiction.

Unnatural proteins for the control of surface forces

We introduce a new method for the stabilization of colloidal particles via the synthesis and adsorption of unnatural proteins. Biosynthesis of protein-based polymers offers the advantages of preparation of complex sequences through control of the primary sequence, monodisperse polymers, ease of combinatorial search for anchor blocks, environmentally friendly synthesis, use of water as the solvent, and incorporation of a palette of known natural proteins. We have synthesized an unnatural protein with the sequence thioredoxin-Pro(39)Glu(10) for modification of the forces between alumina particles. The polyglutamate sequence, Glu(10), is anionic (pH > 3) and is designed to anchor the protein to positively charged solids, e.g. alumina in water (pH < 9). The polyproline sequence, Pro(39), is neutral. The thioredoxin is a recombinant form of the natural globular protein with a histidine patch (His-patch-thioredoxin) and is zwitterionic. The combined thioredoxin-Pro(39) sequence is hydrophilic with pI approximately 6.3. This block is designed to remain in solution, thereby providing a steric barrier to the approach of two particles in a range of salt and pH conditions. Ellipsometry experiments show that thioredoxin-Pro(39)Glu(10) does adsorb to alumina. Force measurements with the atomic force microscopy (AFM) colloid probe technique show that adsorption of thioredoxin-Pro(39)Glu(10) leads to repulsive forces that decay exponentially with the separation between the surfaces and are independent of salt concentration in the range 0.001-0.1 M KNO(3). This demonstrates that the repulsive forces are not electrostatic. We hypothesize that the repulsion is due to confinement and loss of solvent for the adsorbed polymer; the forces are similar to those expected for a polymer brush. Force measurements between thioredoxin-coated alumina surfaces also show a repulsive force, but the force has a decay length that is consistent with electrostatic double-layer forces: the thioredoxin has not neutralized the surface charge of the underlying alumina. Our results point to interesting future experiments where recombinant DNA technology could be used to synthesize fusion proteins containing useful natural proteins and an anchor. This may allow preparation, via single-step aqueous self-assembly, of anchored proteins that maintain their natural structure. Our technique is not limited to homopolymer blocks; more complex primary sequences can be used.

Clearing the airways: advocacy and regulation for smoke-free airlines

OBJECTIVE

To examine the advocacy and regulatory history surrounding bans on smoking in commercial airliners.

METHODS

Review of historical documents, popular press articles, and other sources to trace the timeline of events leading up to the US ban on smoking in airliners and subsequent efforts by airlines and other nations.

RESULTS

In early years, efforts by flight attendants and health advocates to make commercial airliners smoke-free were not productive. Advocacy efforts between 1969 and 1984 resulted in maintenance of the status quo, with modest exceptions (creation of smoking and non-smoking sections of aircraft, and a ban on cigar and pipe smoking). Several breakthrough events in the mid 1980s, however, led to an abrupt turnaround in regulatory efforts. The first watershed event was the publication in 1986 of the National Academy of Science's report on the airliner cabin environment, which recommended banning smoking on all commercial flights. Subsequently, following concerted lobbying efforts by health advocates, Congress passed legislation banning smoking on US domestic flights of less than two hours, which became effective in 1988. The law was made permanent and extended to flights of less than six hours in 1990. This landmark legislation propelled the adoption of similar rules internationally, both by airlines and their industry's governing bodies. Though the tobacco industry succeeded in stalling efforts to create smoke-free airways, it was ultimately unable to muster sufficient grassroots support or scientific evidence to convince the general public or policymakers that smoking should continue to be allowed on airlines.

CONCLUSIONS

The movement to ban smoking in aircraft represents a case study in effective advocacy for smoke-free workplaces. Health advocates, with crucial assistance from flight attendants, used an incremental advocacy process to push for smoking and non-smoking sections on US commercial flights, then for smoking bans on short domestic flights, and finally for completely smoke-free domestic and international flights. Through the course of the battle, advocates from all quarters of tobacco control presented a unified message, exhibited remarkable focus on an attainable goal, and effectively leveraged their relationships with champions in both government and the private sector.

Development of PCR-Based Assays for Detecting Xanthomonas campestris pv. carotae, the Carrot Bacterial Leaf Blight Pathogen, from Different Substrates

Detection of the carrot bacterial leaf blight pathogen, Xanthomonas campestris pv. carotae, was achieved using polymerase chain reaction (PCR) along with primer pairs developed from sequences of cloned random amplified polymorphic DNA (RAPD) fragments. Primer pairs 3S and 9B directed the amplification of ∼350-bp and ∼900-bp (or ∼2 kb) DNA fragments, respectively, from genomic DNA of all known X. campestris pv. carotae strains tested, but not from that of 13 other X. campestris pathovars or other bacterial species, including yellow non-xanthomonad bacteria isolated from carrot tissues and seeds. In tests conducted with an extensive collection of X. campestris pv. carotae-like strains isolated from different substrates from California, Idaho, Oregon, Washington, and Canada, the 3S primer pair directed the amplification of the ∼350-bp target fragment from all strains. These results indicated that the 3S primer pair is highly specific for X. campestris pv. carotae detection. Using the 3S primer pair, PCR assays were developed for detection of X. campestris pv. carotae from colonies on agar media, carrot leaf and stem tissues, and seeds. These tests could be performed in a single day. The PCR-based seed assay detected X. campestris pv. carotae from lots with contamination rates ranging from 2 × 10² to 2.3 × 10⁸ CFU per gram of seed. This assay gave results similar to a seed-wash dilution plating assay and proved more sensitive than an enzyme-linked immunosorbent assay (ELISA)-based assay.

Kids campaign against tobacco

Counter-advertising contests, in which children are encouraged to submit artwork promoting awareness about the harmful effects of smoking, provide an effective form of education.

Origin of Race 3 of Fusarium oxysporum f. sp. lycopersici at a Single Site in California

ABSTRACT Thirty-nine isolates of Fusarium oxysporum were collected from tomato plants displaying wilt symptoms in a field in California 2 years after F. oxysporum f. sp. lycopersici race 3 was first observed at that location. These and other isolates of F. oxysporum f. sp. lycopersici were characterized by pathogenicity, race, and vegetative compatibility group (VCG). Of the 39 California isolates, 22 were in VCG 0030, 11 in VCG 0031, and six in the newly described VCG 0035. Among the isolates in VCG 0030, 13 were race 3, and nine were race 2. Of the isolates in VCG 0031, seven were race 2, one was race 1, and three were nonpathogenic to tomato. All six isolates in VCG 0035 were race 2. Restriction fragment length polymorphisms (RFLPs) and sequencing of the intergenic spacer (IGS) region of rDNA identified five IGS RFLP haplotypes, which coincided with VCGs, among 60 isolates of F. oxysporum from tomato. Five race 3 isolates from California were of the same genomic DNA RFLP haplotype as a race 2 isolate from the same location, and all 13 race 3 isolates clustered together into a subgroup in the neighbor joining tree. Collective evidence suggests that race 3 in California originated from the local race 2 population.

Environmental Factors Affecting Rose Downy Mildew and Development of a Forecasting Model for a Nursery Production System

The effect of various environmental parameters on rose downy mildew caused by Peronospora sparsa was determined under controlled conditions and in the field. In growth chambers, optimal temperatures for infection and colonization of rose leaves were 15 to 20°C and 20 to 25°C, respectively. At optimal temperatures, infection required only 2 h of leaf wetness, although disease severity increased significantly with an increasing duration of leaf wetness up to 10 h. Infection of leaves occurred at temperatures as low as 5°C with 8 h of leaf wetness. The latent period of infection varied from 4 to 7 days. Weather and disease incidence data collected from natural field epidemics were used in the development of a predictive model of rose downy mildew. Logistic regression was used to identify those weather variables that explained the largest portion of the variation in disease incidence. The optimum regression model incorporated three weather variables calculated as cumulative totals over the previous 10 days: (i) hours of leaf wetness when temperatures were less than 20°C (positive correlation); (ii) hours between 15 and 20°C (negative correlation); and (iii) hours when temperatures exceeded 30°C (negative correlation). The simplest model, which was also a good fit, included only the 10-day cumulative number of hours of leaf wetness. The critical number of hours of leaf wetness for disease development was an average of 8.4 h per day over 10 days.

Detection and Management of Downy Mildew in Rose Rootstock

A technique utilizing the polymerase chain reaction (PCR) was developed to investigate the occurrence and location of Peronospora sparsain dormant, woody rose tissues. PCR primers were designed to amplify the internal transcribed spacer region of the ribosomal DNA of the pathogen. Inhibition of the reaction by plant compounds was minimized by optimizing the reagents used in the extraction of DNA from roses and in the amplification reaction. The PCR assay was capable of detecting as little as 2 pg of DNA from P. sparsa against a background of 4 ng of DNA from rose cane cortex. With this method, DNA of P. sparsa was detected in the cortex of stem and root tissues of symptomatic plants. Pathogen DNA also was detected in the cortex of crown tissues of asymptomatic mother plants used as a source of propagation materials. Epifluorescent and differential interference contrast microscopy were used to confirm the presence of abundant hyphae and oospores within the stem cortex of infected canes. Preplant treatments of dormant rootstock cuttings in fungicides or hot water were evaluated during natural outbreaks of the disease in commercial rose nurseries. In three trials conducted over 2 years, a 10-min preplant dip in the systemic fungicides metalaxyl or mefenoxam at rates of 100 to 10,000 mg a.i./liter reduced the area under the disease progress curve by 63 to 76% relative to nontreated plots. The evidence from PCR assays, microscopy, and fungicide trials all support the occurrence of perennating infections of P. sparsa within rose. A technique utilizing the polymerase chain reaction (PCR) was developed to investigate the occurrence and location of Peronospora sparsain dormant, woody rose tissues. PCR primers were designed to amplify the internal transcribed spacer region of the ribosomal DNA of the pathogen. Inhibition of the reaction by plant compounds was minimized by optimizing the reagents used in the extraction of DNA from roses and in the amplification reaction. The PCR assay was capable of detecting as little as 2 pg of DNA from P. sparsa against a background of 4 ng of DNA from rose cane cortex. With this method, DNA of P. sparsa was detected in the cortex of stem and root tissues of symptomatic plants. Pathogen DNA also was detected in the cortex of crown tissues of asymptomatic mother plants used as a source of propagation materials. Epifluorescent and differential interference contrast microscopy were used to confirm the presence of abundant hyphae and oospores within the stem cortex of infected canes. Preplant treatments of dormant rootstock cuttings in fungicides or hot water were evaluated during natural outbreaks of the disease in commercial rose nurseries. In three trials conducted over 2 years, a 10-min preplant dip in the systemic fungicides metalaxyl or mefenoxam at rates of 100 to 10,000 mg a.i./liter reduced the area under the disease progress curve by 63 to 76% relative to nontreated plots. The evidence from PCR assays, microscopy, and fungicide trials all support the occurrence of perennating infections of P. sparsa within rose.

Survival and Persistence of Alternaria dauci in Carrot Cropping Systems

Alternaria dauci was recovered in California from carrot crop residue and from volunteer carrot plants in fallow carrot fields. The fungus was not recovered from common weeds surrounding fallow fields. To evaluate further the survival of A. dauci on carrot crop residue, infected carrot leaf tissue was placed in fields or in soil in greenhouse pots, and recovered over time. In California, A. dauci was recovered from infected leaf tissue in both fallow and irrigated fields for as long as 1 year. In Florida, A. dauci was recovered from infected leaf tissue in fallow fields for up to 30 weeks. In greenhouse experiments, A. dauci was recovered from infected leaf tissue for as long as 1 year in dry soil, but only up to 30 weeks in soil that was watered weekly. To determine the infectivity of A. dauci borne on carrot crop residue, infected carrot crops were incorporated into organic and mineral field soils, and soil samples were collected over time. Carrot seed were planted in collected soil, and seedling infection by A. dauci was recorded. Seedling infection was detected up to 13 and 14 weeks after crop incorporation in organic and mineral soil, respectively. Seedling infection was detected for up to 5 weeks in soil that remained dry compared with 3 weeks in flooded soil.

Mefenoxam-Resistant Isolates of Pythium irregulare in an Ornamental Greenhouse in California

Root rot, caused by Pythium species, is a common malady in ornamental greenhouses in Monterey County, CA. In 2001, a root rot of Gerbera daisy (Gerbera jamesonii) and lisianthus (Eustoma grandiflora) caused plant losses in excess of 15 and 75%, respectively, in one greenhouse. Some plantings were total losses. Although mefenoxam was used repeatedly, no disease control was reported. P. irregulare was identified based on morphological structures produced on grass blades in water (1) and on the sequence of the rDNA internal transcribed spacer (ITS) region. Four isolates from each host were tested for sensitivity to mefenoxam in a laboratory bioassay. Using corn meal agar amended with mefenoxam at 0, 0.1, 1, 10, 50, or 100 μg a.i./ml, no inhibition of growth of any isolate occurred at concentrations of 10 μg/ml or less. At 50 and 100 μg/ml, radial growth of colonies was inhibited by approximately 20%. In contrast, 26 isolates of P. ultimum from various agricultural soils in California were completely inhibited by mefenoxam at 100 μg a.i./ml. At 0.1, 1, 10, and 50 μg/ml, growth of these isolates was inhibited by 33, 61, 78, and 96%, respectively. Each treatment was replicated three times, and the experiment was repeated with similar results. Mefenoxam was introduced in 1996 to replace metalaxyl. While metalaxyl contains a mixture of active and inactive enantiomers, mefenoxam contains only the active enantiomer. The intensive use of metalaxyl and mefenoxam in this greenhouse may have resulted in selection for resistant isolates. A resistant isolate (8-007 from Gerbera) has been submitted to the American Type Culture Collection: Manassas, VA. Reference: (1) A. J. van der Plaats-Niterink. Monograph of the Genus Pythium. Stud. Mycol. No. 21. Centraalbureau voor Schimmelcultures, Baarn, the Netherlands, 1981.

First Report of Xanthomonas Leaf Blight of Onion in California

In 2000 and 2001, severe leaf blight of fresh market onions occurred in several fields in the Antelope Valley of California, a high desert area located in northern Los Angeles County. In at least two fields, 70% of the canopy was affected, which resulted in an estimated yield reduction of over 50%. Both organically and conventionally grown onions were affected. Symptoms included numerous small chlorotic lesions that appeared first on older leaves. Lesions were often surrounded by water-soaked margins. As the season progressed, the lesions became elongated and necrotic. Entire leaf blades were often killed. The disease never progressed into the bulbs, but bulbs of infected plants never grew to full size. Yellow mucoid bacterial colonies were recovered on yeast extractdextrose-CaCO₃ agar from symptomatic tissue. All isolates were gram-negative rods with single polar flagella. Two representative isolates were identified as Xanthomonas campestris based on their carbon utilization profile (similarity index of 0.784 and 0.850; Biolog, Hayward, CA), fatty acid profile (similarity index of 0.588; MIS-TSBA, version 4.10, MIDI Inc., Newark, DE), and 16S-23S intergenic spacer DNA sequences (98% sequence identify with strains of X. campestris). In greenhouse pathogenicity tests, eight white globe onion plants were inoculated with a bacterial suspension (10⁶ CFU/ml) of each of the two isolates. Plants were inoculated by spraying the suspension on leaves lightly injured by rubbing with Carborundum or puncturing with needles dipped in the suspension. Controls were inoculated with water. All plants inoculated with the bacteria developed symptoms in 6 days. The bacterium was reisolated from all inoculated plants and confirmed as Xanthomonas. The trial was conducted twice. To our knowledge, this is the first report of Xanthomonas leaf blight of onion in California. In the United States, the disease has been reported in Texas and Colorado (1,2). References: 1. T. Isakeit et al. Plant Dis. 84:201, 2000. 2. H. F. Schwartz and K. Otto. Plant Dis. 84:922, 2000.

Obesity: assessment and management in primary care

Obesity is a complex, multifactorial condition in which excess body fat may put a person at health risk. National data indicate that the prevalence of obesity in the United States is increasing in children and adults. Reversing these trends requires changes in individual behavior and the elimination of societal barriers to healthy lifestyle choices. Basic treatment of overweight and obese patients requires a comprehensive approach involving diet and nutrition, regular physical activity, and behavioral change, with an emphasis on long-term weight management rather than short-term extreme weight reduction. Physicians and other health professionals have an important role in promoting preventive measures and encouraging positive lifestyle behaviors, as well as identifying and treating obesity-related comorbidities. Health professionals also have a role in counseling patients about safe and effective weight loss and weight maintenance programs. Recent evidence-based guidelines from the National Heart, Lung, and Blood Institute, as well as recommendations from the American Academy of Pediatrics, American Association of Clinical Endocrinologists/American College of Endocrinology, American Obesity Association, U.S. Clinical Preventive Services Task Force, Institute of Medicine, and World Health Organization can be consulted for information and guidance on the identification and management of overweight and obese patients.

Reaction kinetics of protease with substrate phage. Kinetic model developed using stromelysin

Peptide libraries generated using phage display have been widely applied to proteolytic enzymes for substrate selection and optimization, but the reaction kinetics between the enzyme and substrate phage are not well understood. Using a quantitative ELISA assay to monitor the disappearance of substrate, we have been able to follow the course of reaction between stromelysin, a metalloprotease, and its substrate phage. We found that under the proteolytic conditions where the enzyme was present in nanomolar concentration or higher, in excess over the substrate, the proteolysis of substrate phage was a single exponential event and the observed rate linear with respect to enzyme concentration. The enzyme concentration dependence could be described by pseudo first-order kinetic equations. Our data suggest that substrate binding is slow relative to the subsequent hydrolysis step, implying that the phage display selection process enriches clones that have high binding affinity to the protease, and the selection may not discriminate those of different chemical reactivity toward the enzyme. Considering that multiple substrate molecules may be present on a single phage particle, we regard the substrate phage reaction kinetic model as empirical. The validity of the model was ascertained when we successfully applied it to determine the binding affinity of a competitive inhibitor of stromelysin.

Unique phospholipid metabolism in mouse heart in response to dietary docosahexaenoic or alpha-linolenic acids

Diet and fatty acid metabolism interact in yet unknown ways to modulate membrane fatty acid composition and certain cellular functions. For example, dietary precursors or metabolic products of n-3 fatty acid metabolism differ in their ability to modify specific membrane components. In the present study, the effect of dietary 22:6n-3 or its metabolic precursor, 18:3n-3, on the selective accumulation of 22:6n-3 by heart was investigated. The mass and fatty acid compositions of individual phospholipids (PL) in heart and liver were quantified in mice fed either 22:6n-3 (from crocodile oil) or 18:3n-3 (from soybean oil) for 13 wk. This study was conducted to determine if the selective accumulation of 22:6n-3 in heart was due to the incorporation of 22:6n-3 into cardiolipin (CL), a PL most prevalent in heart and known to accumulate 22:6n-3. Although heart was significantly enriched with 22:6n-3 relative to liver, the accumulation of 22:6n-3 by CL in heart could not quantitatively account for this difference. CL from heart did accumulate 22:6n-3, but only in mice fed preformed 22:6n-3. Diets rich in non-22:6n-3 fatty acids result in a fatty acid composition of phosphatidylcholine (PC) in heart that is unusually enriched with 22:6n-3. In this study, the mass of PC in heart was positively correlated with the enrichment of 22:6n-3 into PC. The increased mass of PC was coincident with a decrease in the mass of phosphatidylethanolamine, suggesting that 22:6n-3 induced PC synthesis by increasing phosphatidylethanolamine-N-methyltransferase activity in the heart.

Progressive neurological signs associated with systemic mastocytosis in a dog

A 9-year-old dog was presented with nonregenerative anaemia and severe thrombocytopenia, diarrhoea, spinal hyperalgesia and progressive hindlimb paresis. A moderately well differentiated cutaneous mast cell tumour (MCT) was removed from the skin of the right elbow along with the enlarged right prescapular lymph node. Due to deterioration of the dog's neurological condition, euthanasia was performed. On necropsy examination, haemorrhage and accumulations of poorly differentiated mast cells were found in the lumbosacral region and cauda equina. This article describes an unusual presentation of systemic mastocytosis and the previously unreported finding of metastasis of mast cells to the spinal cord.