Genetic Analysis of Adult Plant Resistance to Yellow Rust and Leaf Rust in Common Spring Wheat Quaiu 3.

Identifying and utilizing rust resistance genes in wheat has been hampered by the continuous and rapid emergence of new pathogen races. A major focus of many wheat breeding programs is achieving durable adult plant resistance (APR) to yellow (stripe) rust (YR) and leaf (brown) rust (LR), caused by Puccinia striiformis and P. triticina, respectively. This study aimed to determine the genetic basis of resistance to YR and LR in the common spring wheat 'Quaiu 3'. To that end, we evaluated 198 F5 recombinant inbred lines (RILs), derived from a cross of susceptible 'Avocet-YrA' with Quaiu 3, for APR to LR and YR in artificially inoculated field trials conducted in Mexico during the 2009 and 2010 growing seasons. High narrow-sense heritability (h2) estimates, ranging between 0.91 and 0.95, were obtained for both LR and YR disease severities for both years. The quantitative and qualitative approaches used to estimate gene numbers showed that, in addition to known resistance genes, there are at least two to three APR genes associated with LR and YR resistance in the RIL population. The moderately effective race-specific resistance gene Lr42 and the pleiotropic slow-rusting APR gene Lr46/Yr29 were found to interact with additional unidentified APR genes. The unidentified APR genes should be of particular interest for further characterization through molecular mapping, and for utilization by wheat breeding programs.

Cross-species transferability of microsatellite markers from six aphid (Hemiptera: Aphididae) species and their use for evaluating biotypic diversity in two cereal aphids.

The abundance and distribution of microsatellites, or simple sequence repeats (SSRs) were explored in the expressed sequence tag (EST) and genomic sequences of the pea aphid, Acyrthosiphon pisum (Harris), and the green peach aphid, Myzus persicae (Sulzer). A total of 108 newly developed, together with 40 published, SSR markers were investigated for their cross-species transferability among six aphid species. Genetic diversity among six greenbug, Schizaphis graminum (Rondani) and two Russian wheat aphid, Diuraphis noxia (Kurdjumov) biotypes was further examined with 67 transferable SSRs. It was found that the pea aphid genome is abundant in SSRs with a unique frequency and distribution of SSR motifs. Cross-species transferability of EST-derived SSRs is dependent on phylogenetic closeness between SSR donor and target species, but is higher than that of genomic SSRs. Neighbor-joining analysis of SSR data revealed host-adapted genetic divergence as well as regional differentiation of greenbug biotypes. The two Russian wheat aphid biotypes are genetically as diverse as the greenbug ones although it was introduced into the USA only 20 years ago. This is the first report of large-scale development of SSR markers in aphids, which are expected to have wide applications in aphid genetic, ecological and evolutionary studies.

Microsatellite markers associated with two Aegilops tauschii-derived greenbug resistance loci in wheat.

A new source of greenbug (Schizaphis graminum Rondani) resistance derived from Aegilops tauschii (Coss.) Schmal was identified in W7984, a synthetic hexaploid wheat line and one parent of the International Triticeae Mapping Initiative (ITMI) mapping population. Segregation analysis of responses to greenbug feeding in a set of recombinant inbred lines (RILs) identified a single, dominant gene governing the greenbug resistance in W7984, which was placed in chromosome arm 7DL by linkage analysis with molecular markers in the ITMI population. Allelism tests based on the segregation of responses to greenbug feeding in F2 and testcross plants revealed that the greenbug resistance in W7984 and Largo, another synthetic line carrying the greenbug resistance gene Gb3, was controlled by different but linked loci. Using the ITMI reference map and a target mapping strategy, we have constructed a microsatellite map of Gb3 in a mapping population of 130 F7 RILs from Largo x TAM 107 and identified one marker (Xwmc634) co-segregating with Gb3 and four markers (Xbarc76, Xgwm037, Xgwm428 and Xwmc824) closely linked with Gb3. Deletion mapping of selected microsatellite markers flanking the Gb3 locus placed this resistance gene into the distal 18% region of 7DL. Comparative mapping in the ITMI and Largo x TAM 107 populations using the same set of microsatellite markers provided further evidence that greenbug resistance in W7984 and Largo is conditioned by two different loci. We suggest that the greenbug resistance gene in W7984 be designated Gb7. The microsatellite map of Gb3 constructed from this study should be a valuable tool for marker-assisted selection of Gb3-conferred greenbug resistance in wheat breeding.

Introduction of corneal astigmatism through placement of a scleral fixation ring in eye bank eyes.

PURPOSE: To determine the effect of scleral fixation ring placement in induction of astigmatism by topographic analysis. METHODS: Baseline measurements were used in human eyes from the Utah Lions Eye Bank. In two control eyes, the effect of placing and replacing the eye in the holder was determined. In nine eyes, the effect of placing a 14-mm ring 2.0-mm from the limbus and an 18-mm ring 4.0-mm from the limbus, both in line with and between the rectus muscles, was determined. Induced astigmatism (IA) was determined by Alpins' vector analysis method. RESULTS: Control eyes had a mean variation of 0.26 +/- 0.18 diopters (D) (range, 0.07-0.65). The study eyes had a mean IA of 1.55 D with statistically significant differences noted when comparing 14-mm rings (0.92 +/- 2.00 D) versus 18-mm rings in line with the rectus (3.02 +/- 1.49 D; p = 0.02), with 18-mm rings in line with the rectus muscles (3.02 +/- 1.46 D) versus between the muscles (1.37 +/- 1.14 D; p = 0.03), and all measurements with the 14-mm ring (1.0 +/- 1.49 D) versus the 18-mm ring (2.14 +/- 1.51 D; p = 0.04.). CONCLUSIONS: Significant IA can occur with placement of fixation rings, especially when suture placement is near the insertions of the rectus muscles.

Methicillin-resistant Staphylococcus aureus keratitis after laser in situ keratomileusis.

A 50-year-old man had uneventful bilateral laser in situ keratomileusis (LASIK) for moderate myopia (-4.50 diopters sphere, both eyes). Twelve days postoperatively, he developed unilateral bacterial keratitis. Cultures revealed methicillin-resistant Staphylococcus aureus. The antibiotic regimen was adjusted, and he regained an uncorrected visual acuity of 20/40 and a best spectacle-corrected visual acuity (BSCVA) of 20/15. Bacterial keratitis after LASIK is a rare occurrence. Aggressive use of cultures and fortified antibiotics can prevent significant loss of BSCVA, even when a resistant organism is the cause.

The role of glaucoma therapy in the need for repeat penetrating keratoplasty.

PURPOSE: To evaluate the effects of medical and surgical therapy for glaucoma in patients requiring repeat penetrating keratoplasty (PK) for endothelial failure. METHODS: Retrospective review of the charts of all patients undergoing repeat PK at the Cornea Service at Wills Eye Hospital between January 1, 1989 and December 31, 1995. Study end-points were time to first rejection episode, number of rejection episodes, time to endothelial failure, and time to regraft. RESULTS: During the study period, 156 patients underwent repeat PK for irreversible endothelial failure. Ninety-four (60.3%) patients had a concomitant diagnosis of glaucoma. Of these 94, 27 (28.7%) underwent glaucoma surgery. The surgically treated group had a significantly higher percentage of patients with at least one rejection episode (55.6%) than those without glaucoma (32.8%; p = 0.04). Similarly, a significant difference existed in the percentage of both medically and surgically treated glaucoma patients having at least one rejection episode (50%) when compared with patients without glaucoma (32.8%; p = 0.04). Rejection episodes occurred sooner in the glaucoma patients than in the nonglaucoma group (18 months vs. 32 months; p = 0.01), irrespective of glaucoma therapy. Grafts in glaucoma patients failed 12 months earlier than those in patients without glaucoma. CONCLUSION: In a selected group of patients who required repeat PK for endothelial graft failure, a majority of patients were found to have a history of glaucoma. Among regraft patients, surgical therapy for glaucoma was found to increase the risk of rejection episodes when compared to patients without glaucoma. The patients with glaucoma were found to be at increased risk for early rejection and failure compared to patients without glaucoma.

Traumatically ruptured globes in children.

This retrospective study was designed to document the etiology of traumatically ruptured globes in children and to determine the prognostic value of several clinical parameters with respect to visual outcome. Forty-six children 16 years of age and under seen in the emergency room over a 2-year period were found to have full thickness penetration of the globe. Fifty-nine percent of injuries occurred during recreational activities, and 59% occurred outside of the home. Boys outnumbered girls by a 6:1 ratio. For children, initial visual acuity proved to be less valuable as a prognostic indicator with regard to final vision than has been reported in adults. Smaller corneal wounds offered better visual outcomes. Four eyes were enucleated. Ten ruptures (22%) were related to activity involving guns. Four of six BB gun injuries were the result of a ricocheted BB. Visual outcomes in gun-related injuries were particularly poor.