Constitutive expression of a phenylalanine ammonia-lyase gene from Stylosanthes humilis in transgenic tobacco leads to enhanced disease resistance but impaired plant growth

Transgenic tobacco plants expressing a phenylalanine ammonia-lyase cDNA (ShPAL), isolated from Stylosanthes humilis, under the control of the 35S promoter of the cauliflower mosaic virus were produced to test the effect of high level PAL expression on disease resistance. The transgenic plants showed up to eightfold PAL activity and were slowed in growth and flowering relative to non-transgenic controls which have segregated out the transgene. The expression of the ShPAL transgene and elevated PAL levels were correlated and stably inherited. In T-1 and T-2 tobacco plants with increased PAL activity, lesion expansion was significantly reduced by up to 55% on stems inoculated with the Oomycete pathogen Phytophthora parasitica pv. nicotianae, Lesion area was significantly reduced by up to 50% on leaves inoculated with the fungal pathogen Cercospora nicotianae. This study provides further evidence that PAL has a role in plant defence. (C) 2002 Elsevier Science Ltd. All rights reserved.

Genetic linkage analysis of the lesser grain borer Rhyzopertha dominica identifies two loci that confer high-level resistance to the fumigant phosphine

High levels of inheritable resistance to phosphine in Rhyzopertha dominica have recently, been detected in Australia and hi art effort to isolate the genes responsible For resistance we have used random amplified DNA fingerprinting (RAF) to produce a genetic linkage map of R. dominica. The map consists of 94 dominant DNA markers with art average distance between markers of 4.6 cM and defines nine linkage groups with a total recombination distance of 390.1 cM. We have identified two loci that are responsible for high-level resistance. One provides similar to50x resistance to phosphine while the other provides 12.5x resistance and in combination, the two genes act synergistically to provide a resistance level 250 x greater than that of fully susceptible beetles. The haploid genome size has been determined to be 4.76 x 10(8) bp, resulting in an average physical distance of 1.2 Mbp per map unit. No recombination has been observed between either of the two resistance loci and their adjacent DNA markers in a population of 44 fully resistant F-5 individuals, which indicates that the genes are likely to reside within 0.91 cM (1.1 Mbp) of the DNA markers.

Rational combinatorial chemistry-based selection, synthesis and evaluation of an affinity adsorbent for recombinant human clotting factor VII

The selection, synthesis and chromatographic evaluation of a synthetic affinity adsorbent for human recombinant factor VIIa is described. The requirement for a metal ion-dependent immunoadsorbent step in the purification of the recombinant human clotting factor, FVIIa, has been obviated by using the X-ray crystallographic structure of the complex of tissue factor (TF) and Factor VIIa and has directed our combinatorial approach to select, synthesise and evaluate a rationally-selected affinity adsorbent from a limited library of putative ligands. The selected and optimised ligand comprises a triazine scaffold bis-substituted with 3-aminobenzoic acid and has been shown to bind selectively to FVIIa in a Ca2+-dependent manner. The adsorbent purifies FVIIa to almost identical purity (>99%), yield (99%), activation/degradation profile and impurity content (∼1000 ppm) as the current immunoadsorption process, while displaying a 10-fold higher static capacity and substantially higher reusability and durability. © 2002 Elsevier Science B.V. All rights reserved.

Adipose tissue as an endocrine organ

Adipose tissue is a highly active endocrine organ secreting a range of soluble products with both local and distant actions. These hormones have important roles in metabolism, reproduction, cardiovascular function and immunity. It is now evident that adipose endocrine function directly influences other organ systems, including the brain, liver and skeletal muscle. The endocrine function of adipose tissue is significantly regulated by nutritional status, and both are inextricably linked to the energy storage role of adipose tissue. This chapter highlights the endocrinology of adipose tissue by concentrating on functional aspects of the secreted products. The data of particular relevance to humans are highlighted, and areas in need of future research are suggested.

GH treatment in adults with chronic liver disease: A randomized, double-blind, placebo-controlled, cross-over study

Patients with chronic liver disease (CLD) are catabolic and GH-resistant. The effects of supraphysiological recombinant human GH (rhGH; 0.2 IU.kg(-1).d(-1)) treatment in adults with CLD were assessed in a randomized, double-blind, placebo-controlled cross-over trial (4-wk dietary run-in, 4-wk treatment, and 2-wk wash-out phases). Nine adults with mild- to moderate-severity CLD participated (median age, 49 yr; three males and six females; Child's classification A in six and B in three). Biopsy-proven etiologies were: alcohol (four patients), primary biliary cirrhosis (three patients), non-A, non-B, non-C hepatitis (one patient), and cryptogenic (one patient). Treatment with rhGH increased serum IGF-I (median increase over placebo, +93 mug.liter(-1); P = 0.004), IGF-binding protein-3 (+0.9 mg.liter(-1): P = 0.004), and acid labile subunit (+10.7 nM; P = 0.004). Total body potassium (+8.0 g; P = 0.023), body weight (+1.6 kg; P = 0.008), and total body water (by bioelectrical impedance; +4.9 kg; P = 0.004) increased. Resting metabolic rate (+313 ml.kg(-1).min(-1); P = 0.004) and lipid oxidation (+1072.0 kcal.d(-1); P = 0.032) increased. Metabolic changes included increased fasting plasma glucose (+1.2 mm; P = 0.008), insulin (+33.8 mU.liter(-1); P = 0.004), C-peptide (+0.7 nM; P = 0.004), and free-fatty acids (+0.1 mEq.liter(-1); P = 0.04). Clinical side effects included worsening edema and ascites. Hepatocellular function did not change. Therefore, rbGH treatment in CLD: 1) overcame hepatic GH resistance; 2) may have improved whole-body protein catabolism; 3) increased lipolysis and lipid oxidation; 4) increased insulin resistance; and 5) had potent antinatriuretic effects. Long-term safety and efficacy require further assessment.

Intrinsic regional differences in androgen receptors and dihydrotestosterone metabolism in human preadipocytes

Androgens play an important role in regulating the central obesity that is a strong risk factor for cardiovascular disease and insulin resistance. This study confirms that androgen receptors are present in subcultured human preadipocytes, with androgen receptor gene expression and saturable specific dihydrotestosterone binding, dissociation constant 1.02 - 2.56 nM and maximal binding capacity 30.8 - 55.7 fmol/mg protein. There was an intrinsic regional difference in androgen receptor complement, with more androgen receptors in visceral than in subcutaneous preadipocytes. Dihydrotestosterone was metabolised by human preadipocytes, with more androstanediol produced by subcutaneous than visceral preadipocytes. While dihydrotestosterone metabolism was insufficient to explain the regional variation in androgen binding, both of these differences would reduce the androgen responsiveness of the subcutaneous preadipocytes compared with visceral preadipocytes. There were no gender differences in androgen binding or metabolism. While the direct effects of androgens on human PAS remain uncertain, these regional differences suggest that AR-mediated regulation of certain PA functions influences adipose tissue distribution.

Breeding for resistance to lentil Ascochyta blight

Ascochyta blight, caused by Ascochyta lentis , is one of the most globally important diseases of lentil. Breeding for host resistance has been suggested as an efficient means to control this disease. This paper summarizes existing studies of the characteristics and control of Ascochyta blight in lentil, genetics of resistance to Ascochyta blight and genetic variations among pathogen populations (isolates). Breeding methods for control of the disease are discussed. Six pathotypes of A. lentis have been reported. Many resistant cultivars/lines have been identified in both cultivated and wild lentil. Resistance to Ascochyta blight in lentil is mainly under the control of major genes, but minor genes also play a role. Current breeding programmes are based on crossing resistant and high-yielding cultivars and multilocation testing. Gene pyramiding, exploring slow blighting and partial resistance, and using genes present in wild relatives will be the methods used in the future. Identification of more sources of resistance genes, good characterization of the host-pathogen system, and identification of molecular markers tightly linked to resistance genes are suggested as the key areas for future study.

Minor genes are involved in ascochyta blight resistance in lentils

In addition to a gene with major effect, minor genes were found to contribute to the genetic regulation of foliar resistance to Ascochyta blight in two crosses between two resistant and one susceptible lentil cultivars (lines). This was established by comparing inbred lines with and without the major resistance gene. The effects of minor genes were not large enough to change the phenotypic performance determined by its major gene qualitatively (from resistant to susceptible, or vice versa) based on the measurement scale used. However, they did substantially and significantly modify the resistance level. The major gene for foliar resistance was linked to the gene(s) for seed infection rate and/or had a positive pleiotrophic effect on seed infection rate. Similarly, the major gene for foliar resistance was linked to the gene(s) for seed yield/plant in disease free environments and/or had negative pleiotrophic effects on yield/plant. Selection for resistance and yield among inbreds with the same major resistance gene may be necessary to enhance the resistance level, and to reduce the negative effect on yield of the major resistance gene.

Peanut resistance to Sclerotinia minor and S-sclerotiorum

The fungi Sclerotinia minor and S. sclerotiorum are the causal agents of two similar diseases of peanut (Arachis hypogaea L.). Both diseases cause significant losses in the Australian peanut industry. Development of cultivars with resistance to Sclerotinia will be an important component of integrated control. The aims of this project are to generate information that will assist in breeding for Sclerotinia resistance in peanut: to identify Sclerotinia-resistant peanut germplasm, to understand the inheritance and estimate heritability of resistance, and to test the effectiveness of identified sources of resistance against both S. minor and S. sclerotiorum. This study has clearly established that material that shows resistance to S. minor in the USA is resistant to S. minor and likely to be resistant to S. sclerotiorum in Australia. The high level of resistance to both S. minor and S. sclerotiorum in germplasm from Texas, particularly TxAG-4, was confirmed. VA 93B showed good resistance in the field, which is primarily due to the open bush type rather than physiological resistance. Physiological resistance to S. minor was also identified in a cultivar and a landrace from Indonesia and a rust-resistant line from Queensland. All germplasm found to have high physiological resistance to S. minor belonged to the Spanish type. Inheritance of physiological resistance to S. minor was studied using a Generation Means Analysis (GMA) of the cross TxAG-4/VA 93B and its reciprocal. The broad-sense heritability of physiological resistance on a single plant basis was estimated at 47%, much higher than earlier estimates obtained in field studies. The average gene action of Sclerotinia resistance genes from TxAG-4 was found to be additive. No dominance effects were detected in the GMA. A small but significant reciprocal effect between TxAG-4 and VA 93B indicated that VA 93B passed on some physiological resistance maternally. An experiment was conducted to confirm the value of resistance against both S. minor and S. sclerotiorum. TxAG-4 was found to have physiological resistance to both S. minor and S. sclerotiorum. This resistance was expressed against both Sclerotinia species by progeny that were selected for resistance to S. minor. On the basis of the information obtained, the comparative advantages of 3 strategies for Sclerotinia-resistant cultivar development are discussed: (1) introduction of germplasm; (2) recurrent backcrossing with screening and crossing in the BCnF1 generation; and (3) pedigree selection. At present, introduction and backcrossing are recommended as the preferred strategies.