The rice Xa21 gene, which confers resistance to Xanthomonas oryzae pv. oryzae race 6, was isolated by positional cloning. Fifty transgenic rice plants carrying the cloned Xa21 gene display high levels of resistance to the pathogen. The sequence of the predicted protein, which carries both a leucine-rich repeat motif and a serine-threonine kinase-like domain, suggests a role in cell surface recognition of a pathogen ligand and subsequent activation of an intracellular defense response. Characterization of Xa21 should facilitate understanding of plant disease resistance and lead to engineered resistance in rice.

Background and ObjectivesWith the increasing survival of preterm infants, pulmonary hypertension (PH) related to bronchopulmonary dysplasia (BPD) has become an important complication. The aim of this study was to investigate the characteristics and outcome of PH in preterm infants with BPD and to identify the risk factors for PH.Subjects and MethodsWe reviewed the records of 116 preterm infants with BPD cared for at a single tertiary center between 2004 and 2008.ResultsTwenty-nine (25%) infants had PH >2 months after birth. PH occurred initially at a median age of 65 days (range, 7-232 days). Severe BPD, a birth weight <800 g, long-term ventilator care and oxygen supplementation, a high ventilator setting, infection, and a patent ductus arteriosus (PDA) were related to PH based on univariate analysis (p<0.05). The infants who had longer oxygen supplementation were significantly more likely to have PH (odds ratio, 18.5; 95% confidence interval, 4.1-84.6; p<0.001). PH was improved in 76% of infants after a median of 85 days (range, 20-765 days). Four infants (14%) died. The death of 3 infants was attributed to PH.ConclusionBPD was frequently complicated by PH. Although PH resolved in the majority of infants, PH in preterm infants with BPD can be fatal. Regular screening for PH and adequate management are required.

Plant pathogenic Pseudomonas syringae deliver type III effector proteins into the host cell, where they function to manipulate host defense and metabolism to benefit the extracellular bacterial colony. The activity of these virulence factors can be monitored by plant disease resistance proteins deployed to ''guard'' the targeted host proteins. The Arabidopsis RIN4 protein is targeted by three different type III effectors. Specific manipulation of RIN4 by each of them leads to activation of either the RPM1 or RPS2 disease resistance proteins. The type III effector AvrRpt2 is a cysteine protease that is autoprocessed inside the host cell where it activates RPS2 by causing RIN4 disappearance. RIN4 contains two sites related to the AvrRpt2 cleavage site (RCS1 and RCS2). We demonstrate that AvrRpt2-dependent cleavage of RIN4 at RCS2 is functionally critical in vivo. This event leads to proteasome-mediated elimination of all but a membrane-embedded Ϸ6.4-kDa C-terminal fragment of RIN4. One or more of three consecutive cysteines in this C-terminal fragment are required for RIN4 localization; these are likely to be palmitoylation and͞or prenylation sites. AvrRpt2-dependent cleavage at RCS2, and release of the remainder of RIN4 from the membrane, consequently prevents RPM1 activation by AvrRpm1 or AvrB. RCS2 is contained within the smallest tested fragment of RIN4 that binds AvrB in vitro. Thus, at least two bacterial virulence factors target the same domain of RIN4, a Ϸ30-aa plant-specific signature sequence found in a small Arabidopsis protein family that may be additional targets for these bacterial virulence factors. disease resistance ͉ plant immune system P lant disease resistance (R) genes control the plant immune response upon pathogen recognition. R proteins initiate cellular events that efficiently limit pathogen reproduction (1). Most plant R proteins defined to date possess a central nucleotide binding (NB) domain together with C-terminal leucinerich repeats (LRR), and hence are termed NB-LRR proteins. NB-LRR proteins are specific in that each is activated by a particular pathogen-encoded molecule. These are polymorphic across the pathogen population. The proteins from Gramnegative plant-pathogenic bacteria that trigger NB-LRR action are type III effector proteins delivered into plant cells through the type III secretion system (2). These are called avirulence (Avr) proteins because their presence renders a given pathogen strain avirulent on a resistant plant genotype (R). Avr proteins, however, can also contribute to pathogen virulence on susceptible plant genotypes (r).An Avr ligand-R receptor model could explain the genetic specificity of disease resistance, although experimental support for this model is limited. Rather, accumulating evidence suggests that Avr proteins from pathogenic bacteria can be recognized indirectly by their action on one or more host targets (1, 3, 4). In this model, type III effector proteins manipulate host targets, thereby contributing to pathogen virulence. The plant NB-LRR pro...

To determine the immunologic effects of oropharyngeal colostrum administration in extremely premature infants. METHODS:We conducted a double-blind, randomized, placebo-controlled trial involving 48 preterm infants born before 28 weeks' gestation. Subjects received 0.2 mL of their mother's colostrum or sterile water via oropharyngeal route every 3 hours for 3 days beginning at 48 to 96 hours of life. To measure concentrations of secretory immunoglobulin A, lactoferrin, and several immune substances, urine and saliva were obtained during the first 24 hours of life and at 8 and 15 days. Clinical data during hospitalization were collected.RESULTS: Urinary levels of secretory immunoglobulin A at 1 week (71.4 vs 26.5 ng/g creatinine, P = .04) and 2 weeks (233.8 vs 48.3 ng/g creatinine, P = .006), and lactoferrin at 1 week (3.5 vs 0.9 mg/g creatinine, P = .01) were significantly higher in colostrum group. Urine interleukin-1b level was significantly lower in colostrum group at 2 weeks (55.3 vs 91.8 mg/g creatinine, P = .01). Salivary transforming growth factor-b1 (39.2 vs 69.7 mg/mL, P = .03) and interleukin-8 (1.2 vs 4.9 ng/mL, P = .04) were significantly lower at 2 weeks in colostrum group. A significant reduction in the incidence of clinical sepsis was noted in colostrum group (50% vs 92%, P = .003).CONCLUSIONS: This study suggests that oropharyngeal administration of colostrum may decrease clinical sepsis, inhibit secretion of pro-inflammatory cytokines, and increase levels of circulating immune-protective factors in extremely premature infants. Larger studies to confirm these findings are warranted. WHAT'S KNOWN ON THIS SUBJECT:Immunerelated bioactive proteins are highly concentrated in the colostrum of mothers who deliver preterm infants. Oropharyngeal administration was proposed as a safe and feasible alternative method of providing colostrum to immunocompromised premature infants. WHAT THIS STUDY ADDS:Oropharyngeally administered colostrum during the first few days of life increased urinary secretory immunoglobulin A and lactoferrin, decreased urinary interleukin-1b, reduced salivary transforming growth factor-b1 and interleukin-8, and reduced the occurrence of clinical sepsis in extremely premature infants.