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Focus groups were used to gain insight into the nutrition-related attitudes and motivations of overweight African-American adolescents and young adults enrolled in the Atlanta Job Corps Center in preparation for designing an effective and culturally appropriate nutrition intervention for this population. Eighteen students and 18 staff members participated in six different focus groups. Focus group themes suggest that an intervention with this target group should address overeating, proper diet composition, emotional eating, long-term consequences of a poor diet, group work, and incentives. Limiting food portions, offering healthy, appealing food choices, and displaying nutritional content of foods in the cafeteria were also suggested. It was also suggested that the intervention should be ongoing and led by someone who is patient, supportive, and has overcome an overweight problem. An intervention based on these recommendations can be specifically tailored to this target group and, potentially, be effective in changing dietary behaviors and lifestyle. [ABSTRACT FROM AUTHOR]

Background: This study assessed patient-reported outcomes (PRO) of active-duty U.S. Military Servicemembers following refractive surgery., Methods: We retrospectively reviewed the medical records of 375 U.S. Servicemembers who underwent LASIK (118 eyes), photorefractive keratectomy (PRK, 550 eyes), or small incision lenticule extraction (SMILE, 82 eyes). Surgeries occurred at the former Walter Reed Army Medical Centers Center for Refractive Surgery or the current FBCHs Warfighter Refractive Eye Surgery Program and Research Center (WRESP-RC) from 2004 to 2019. Preoperative and 6-month postoperative data included "Quality of Vision and Patient Satisfaction Before and After Refractive Surgery" questionnaire. Outcome measures included uncorrected distance visual acuity (UDVA)., Results: In this study, 95% LASIK, 94% PRK, and 94% SMILE achieved UDVA 20/20 or better with no between-group differences (P=.308). There were no differences between groups in efficacy (P=.204) or the safety index (P=.066). Postoperative QOV was comparable between groups for far vision (P=.292) and night vision (P=.505). From before to after the operation, far vision significantly improved in LASIK (P=.009) and PRK (P<.001) but not SMILE (P=.384). Postoperative glare was comparable (P=.258). Driving difficulty was significantly different between treatments (P=.025), with significant improvements in PRK and LASIK. There were no significant differences between groups for activity limitations (P=.093) or being bothered by glare, halos, or lack of sharpness of vision (P=.131)., Conclusion: This study found comparable or improved PRO six months after LASIK, PRK, and SMILE. All three yielded excellent visual outcomes with minimal visual symptoms, allowing the performance of daily activities with less difficulty and limitation., (2024.)

Purpose: To assess early visual outcomes and military task performance after small-incision lenticule extraction (SMILE) among U.S. military service members., Setting: Warfighter Refractive Eye Surgery Program and Research Center and Night Vision and Electronic Sensors Directorate, Fort Belvoir, Virginia., Design: Single-center, prospective, observational study., Methods: The study was composed of active duty service members (n = 37) electing to undergo SMILE for myopia or myopic astigmatism. Testing performed preoperatively and at 1 month and 3 months postoperatively included uncorrected (UDVA) and corrected (CDVA) distance visual acuities, wavefront aberrometry, low-contrast visual acuity (LCVA), contrast sensitivity, and vision-related questionnaire. 14 participants underwent rifle marksmanship with spectacle correction before and without correction at 6 to 8 weeks postoperatively., Results: At 3 months postoperatively, the efficacy index was 0.96 and the safety index was 1.03. UDVA was ≥20/20 in 69 (96%) of eyes. LCVA change from baseline was significant under night vision condition. Eye problems contributed to 10% work and 20% activity impairments, both of which decreased to 0% (P = .001). The overall satisfaction rating for SMILE was high at 90.9 (95% CI, 85.3 to 96.5), and 95% of participants would be willing to undergo the procedure again. The median scores between preoperative and 6 to 8 weeks postoperative firing performance were comparable (34 vs 35, with and without correction, respectively; P = .247)., Conclusions: After the early recovery period, SMILE seems to preserve quality of vision, which appears to facilitate the accomplishment of tasks related to their work as military service members as well as performing activities outside of work., (Copyright © 2021 Published by Wolters Kluwer on behalf of ASCRS and ESCRS.)

Purpose: To assess the visual outcomes of small-incision lenticule extraction (SMILE) after the first year of treatments at a military refractive surgery center and compare with photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) outcomes during the same period., Setting: Warfighter Refractive Eye Surgery Program and Research Center, Fort Belvoir, VA., Design: Retrospective study., Methods: Records of service members who underwent SMILE, PRK, or LASIK for myopia from March 2017 to February 2018 were reviewed. Preoperative and up to 6-month postoperative data were collected. Visual outcomes were compared between treatments., Results: Of 563 treated eyes, 173 (30.7%) underwent SMILE, 304 (54.0%) PRK, and 86 (15.3%) LASIK. In comparing SMILE with PRK 1 month postoperatively, SMILE (145 eyes [87.9%]) attained uncorrected distance visual acuity (UDVA) ≥20/20 more vs PRK (214 eyes [73.8%]; P < .01). Similarly, SMILE (152 eyes [94.4%]) achieved more eyes with manifest spherical equivalent (MSE) within ±0.50 diopters (D) from intended target vs PRK (250 eyes [85.9%]; P = .01). None lost ≥1 line of corrected distance visual acuity in SMILE vs PRK (16 eyes [5.5%]; P < .01). Thereafter, there were no other significant differences except SMILE had 117 eyes (95.1%) vs PRK with 224 eyes (99.6%) achieving UDVA ≥20/20 at 3 months postoperatively (P = .01). In assessing SMILE vs LASIK, all parameters were comparable; however, 77 SMILE eyes (96.3%) had MSE within ±0.50 D from target vs 31 LASIK eyes (83.8%) at 6 months postoperatively (P = .02)., Conclusions: The first year after SMILE treatments in a U.S. military center demonstrated early postoperative outcomes superior to PRK. SMILE seemed more predictable compared with LASIK.

Purpose: To assess whether densitometry analysis appropriately monitors the development of haze in myopic patients after photorefractive keratectomy (PRK) when compared to subjective slit-lamp haze grade examinations, and whether sutureless cryo-preserved amniotic membrane reduced postoperative haze development when compared to the standard bandage contact lens., Methods: In this retrospective cohort at the Center for Refractive Surgery, Walter Reed National Military Medical Center, a secondary analysis of prospectively collected data was performed. In the prospective study, participants underwent PRK for myopia. Postoperatively, a standard bandage contact lens was applied to the dominant eye and a sutureless cryo-preserved amniotic membrane graft to the nondominant eye. Participants were evaluated at 1, 3, and 6 months postoperatively for haze formation and corneal densitometry using slit-lamp biomicroscopy and Scheimpflug imaging, respectively., Results: Densitometry measurements at 6 months postoperatively were positively and significantly associated with the presence or absence of haze as assessed by slit-lamp examination in 39 patients (78 eyes; age range: 21 to 44 years). Eyes with increased densitometry measurements had 2.3 to 3.4 times the odds (P ⩽ .014) of having clinical haze on slit-lamp examination. Eyes with the amniotic membrane graft showed a positive correlation with increased corneal densitometry throughout most layers of the cornea., Conclusions: Densitometry analysis appears to be a useful tool to supplement slit-lamp examination in monitoring haze development after PRK. The amniotic membrane failed to show a reduction in corneal densitometry in myopic eyes after PRK. [J Refract Surg. 2020;36(5):293-299.]., (Copyright 2020, SLACK Incorporated.)

Background: This study evaluated the VIsion PERformance (VIPER) simulator's ability to assess the functional visual performance in warfighters conducting civilian and military tasks., Methods: Thirty service members, aged 25-35 years old with a best corrected distance visual acuity (VA) better than or equal to 20/20 or logarithm of the minimum angle of resolution (logMAR) 0.00, were randomized to locate and identify road signs and mock improvised explosive devices (IEDs) under either daytime conditions or with infrared imagery, with (cc) and without (sc) wearing their habitual correction. Participants also underwent binocular uncorrected (UDVA) and corrected (CDVA) visual assessment, refraction, contrast sensitivity testing and wavefront aberrometry., Results: The mean age was 28.47 years. The manifest spherical equivalent was - 3.16 ± 1.75 diopters (D), the UDVA in both eyes (OU) was logMAR 0.83 ± 0.47, and the CDVA OU was - 0.11 ± 0.06. For VIPER, the mean difference in the detection distance (DD) for road signs ccDD vs. scDD was 76.7 ± 52.8 m (P < 0.001). The average difference in identification distance (ID) ccID vs. scID was 13.9 ± 6.3 m (P < 0.001). The mean accuracies were 83.5 and 27.9% for cc and sc, respectively (P < 0.001). The regression analysis indicated that a 1.6 m change in the distance accounts for a 1% change in the accuracy (P = 0.002). Without correction, a 4.1 m change accounts for a 1% change in the accuracy (P < 0.001). The average IED ccDD was 29.9 ± 8.2 m, and that for scDD was 13.2 ± 13.6 m (P < 0.001). The average IED ccID was 32.2 ± 6.2 m and that for the scID was 7.4 ± 10.3 m (P < 0.001). The mean IED identification accuracy was 46.7 and 11.4% for cc and sc, respectively (P < 0.001)., Conclusions: The preliminary results reflect VIPER's ability to assess functional visual performance when detecting and identifying signs and IEDs. Furthermore, VIPER is able to detect performance changes with and without correction.

Purpose: To compare contrast sensitivity among participants undergoing wavefront-guided or wavefront-optimized photorefractive keratectomy (PRK) or LASIK for the treatment of myopia or myopic astigmatism 12 months after surgery., Methods: In a prospective, randomized clinical trial, 215 participants with myopia ranging from -0.50 to -7.25 diopters (D) and less than -3.50 D of manifest astigmatism electing to undergo either LASIK or PRK were randomized to receive wavefront-guided or wavefront-optimized treatment. Corrected Super Vision Test (Precision Vision, La Salle, IL) high contrast and small letter contrast sensitivity, uncorrected postoperative contrast sensitivity function, and uncorrected and corrected distance visual acuity were measured preoperatively and at 1, 3, 6, and 12 months postoperatively., Results: There was a significant difference within each of the four groups over time when measuring high contrast visual acuity (P < .001) and small letter contrast sensitivity (P < .001), with the most significant decrease occurring 1 month postoperatively. However, there were no significant differences when comparing the four groups for high contrast sensitivity (P = .22) or small letter contrast sensitivity (P = .06). The area under the logarithm of contrast sensitivity function did not differ significantly over time (P = .09) or between groups (P = .16). A pairwise comparison of preoperative to 12-month CDVA showed a significant improvement in all groups (P < .017). The change in CDVA was also significantly different between groups as determined by one-way analysis of variance (P = .003)., Conclusions: Wavefront-guided and wavefront-optimized PRK and LASIK procedures maintained high contrast, small letter contrast sensitivity, and contrast sensitivity function 12 months postoperatively. Although the recovery period for visual performance was longer for PRK versus LASIK, there was no significant difference in treatment type or treatment profile at 12 months postoperatively. [J Refract Surg. 2018;34(9):590-596.]., (Copyright 2018, SLACK Incorporated.)

Purpose: To assess vision-related quality of life and military readiness and capabilities among active duty U.S. military service members undergoing refractive surgery., Methods: In this prospective, single-center, observational study, active duty U.S. military service members electing to undergo refractive surgery were asked to complete a military performance questionnaire and the National Eye Institute Refractive Error Quality of Life Instrument (NEI RQL-42) preoperatively and at 6 months postoperatively. On the military performance questionnaire, participants rated (1 = very bad to 5 = very good) how they felt their vision affected their military readiness and capabilities after refractive surgery., Results: Among 360 participants at 6 months postoperatively, the overall mean military performance score increased from 3.6 ± 0.8 to 4.8 ± 0.3, a change of 1.2, with 91.7% of the participants indicating an overall improvement in readiness and capability (P < .001). Scores measuring overall individual readiness, contribution to unit's mission, use of night vision goggles, function at night, weapons sighting ability, employment of personal masks, weather extreme environmental conditions, and optical support were significantly higher postoperatively (P < .001). For the NEI RQL-42, scores were significantly higher postoperatively for the subscales clarity of vision, expectations, near vision, far vision, diurnal fluctuations, activity limit, glare, dependence on correction, worry, appearance, and satisfaction with correction (all P < .001), but not for symptoms after refractive surgery (P = .403)., Conclusions: Refractive surgery significantly improves military readiness and capabilities and vision-related quality of life of active duty U.S. military service members with refractive error. [J Refract Surg. 2018;34(9):597-603.]., (Copyright 2018, SLACK Incorporated.)

In 2015, a laboratory of the United States Department of Defense (DoD) inadvertently shipped preparations of gamma-irradiated spores of Bacillus anthracis that contained live spores. In response, a systematic evidence-based method for preparing, concentrating, irradiating, and verifying the inactivation of spore materials was developed. We demonstrate the consistency of spore preparations across multiple biological replicates and show that two different DoD institutions independently obtained comparable dose-inactivation curves for a monodisperse suspension of B. anthracis spores containing 3 × 10 10 CFU. Spore preparations from three different institutions and three strain backgrounds yielded similar decimal reduction (D 10 ) values and irradiation doses required to ensure sterility (D SAL ) to the point at which the probability of detecting a viable spore is 10 -6 Furthermore, spores of a genetically tagged strain of B. anthracis strain Sterne were used to show that high densities of dead spores suppress the recovery of viable spores. Together, we present an integrated method for preparing, irradiating, and verifying the inactivation of spores of B. anthracis for use as standard reagents for testing and evaluating detection and diagnostic devices and techniques. IMPORTANCE The inadvertent shipment by a U.S. Department of Defense (DoD) laboratory of live Bacillus anthracis (anthrax) spores to U.S. and international destinations revealed the need to standardize inactivation methods for materials derived from biological select agents and toxins (BSAT) and for the development of evidence-based methods to prevent the recurrence of such an event. Following a retrospective analysis of the procedures previously employed to generate inactivated B. anthracis spores, a study was commissioned by the DoD to provide data required to support the production of inactivated spores for the biodefense community. The results of this work are presented in this publication, which details the method by which spores can be prepared, irradiated, and tested, such that the chance of finding residual living spores in any given preparation is 1/1,000,000. These irradiated spores are used to test equipment and methods for the detection of agents of biological warfare and bioterrorism.

Purpose: To evaluate the effect of sutureless cryopreserved amniotic membrane (Prokera) on corneal wound healing after photorefractive keratectomy (PRK)., Setting: Center for Refractive Surgery, Walter Reed Army Medical Center, Washington, DC, USA., Design: Prospective nonrandomized control trial., Methods: Patients had PRK for myopia with or without astigmatism. A 20% ethanol solution was used to create a standard 9.0 mm epithelial defect followed by photoablation with the Allegretto Wave Eye-Q 400 Hz laser. After surgery, a high-oxygen-transmissible bandage contact lens (Acuvue Oasys) was applied on the dominant eye and cryopreserved amniotic membrane on the nondominant eye. The postoperative regimen was otherwise identical for both eyes. Postoperatively, patients were evaluated daily until complete corneal reepithelialization occurred in both eyes and then at 2 weeks and 1, 3, 6, and 12 months. Reepithelialization was assessed daily with slitlamp examination, fluorescein staining, and photography. Secondary outcome measures included adverse effects, ocular comfort, visual outcomes, and corneal haze., Results: Forty patients were enrolled. The amniotic membrane graft sped corneal reepithelialization 1 day after PRK but was not better than the bandage contact lens in hastening complete reepithelialization of the cornea. Visual outcomes, corneal clarity, and optical quality of the cornea were comparable between the amniotic membrane graft eyes and bandage contact lens eyes., Conclusion: Although the amniotic membrane graft was reasonably well tolerated with few significant adverse effects, the role of amniotic membrane in modulating wound healing after PRK remains speculative., (Published by Elsevier Inc.)

Effective microbial forensic analysis of materials used in a potential biological attack requires robust methods of morphological and genetic characterization of the attack materials in order to enable the attribution of the materials to potential sources and to exclude other potential sources. The genetic homogeneity and potential intersample variability of many of the category A to C bioterrorism agents offer a particular challenge to the generation of attributive signatures, potentially requiring whole-genome or proteomic approaches to be utilized. Currently, irradiation of mail is standard practice at several government facilities judged to be at particularly high risk. Thus, initial forensic signatures would need to be recovered from inactivated (nonviable) material. In the study described in this report, we determined the effects of high-dose gamma irradiation on forensic markers of bacterial biothreat agent surrogate organisms with a particular emphasis on the suitability of genomic DNA (gDNA) recovered from such sources as a template for whole-genome analysis. While irradiation of spores and vegetative cells affected the retention of Gram and spore stains and sheared gDNA into small fragments, we found that irradiated material could be utilized to generate accurate whole-genome sequence data on the Illumina and Roche 454 sequencing platforms., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Purpose: To report the use of combined intravitreal triamcinolone and foscarnet therapy in a patient with active acute retinal necrosis., Methods: Retrospective case report. A 40-year-old white woman with a history of ulcerative proctitis, intolerant to oral steroids, developed an aggressive case of acute retinal necrosis complicated by severe optic nerve edema resulting in 20/200 vision., Results: Intravitreal foscarnet provided an initial improvement of the vitritis and retinitis; however, optic nerve edema and 20/200 vision persisted. After 2 weeks, intravitreal triamcinolone was combined with the foscarnet dose. Four days later, the optic nerve edema had resolved, the vision returned to 20/40, and the herpetic infection remained controlled. Eight months later, the patient had not experienced a retinal detachment, and acuity was 20/20. Oral steroids are an accepted adjunct to antiviral therapy in acute retinal necrosis; however, combined intravitreal steroid and antiviral therapy has not been previously reported. After combined intravitreal therapy was attempted, the patient experienced a rapid resolution of symptoms without exacerbating her retinitis., Conclusion: In select patients, combined intravitreal triamcinolone and foscarnet may be effective in treating acute retinal necrosis and its inflammatory sequelae.

Objective. To describe a case of acute zonal occult outer retinopathy (AZOOR) in an active duty patient. Methods. In this paper we studied fundus photographs, optical coherence tomograph, Humphrey visual field 30-2, fundus autofluorescence images, fluorescein angiograms, and electroretinography. Results. Exam findings on presentation: a 34-year-old American Indian female presented with bilateral photopsias, early RPE irregularity, and an early temporal visual field defect. Progression RPE damage and visual field defect along with ERG findings support final diagnosis of AZOOR. Conclusion. AZOOR may initially be identified as a broader category of disease called the "AZOOR complex of disorders". Specific visual field defects, ERG results, and clinical exam findings will help distinguish AZOOR from other similar disorders.

A variant of Bacillus thuringiensis subsp. kurstaki containing a single, stable copy of a uniquely amplifiable DNA oligomer integrated into the genome for tracking the fate of biological agents in the environment was developed. The use of genetically tagged spores overcomes the ambiguity of discerning the test material from pre-existing environmental microflora or from previously released background material. In this study, we demonstrate the utility of the genetically "barcoded" simulant in a controlled indoor setting and in an outdoor release. In an ambient breeze tunnel test, spores deposited on tiles were reaerosolized and detected by real-time PCR at distances of 30 m from the point of deposition. Real-time PCR signals were inversely correlated with distance from the seeded tiles. An outdoor release of powdered spore simulant at Aberdeen Proving Ground, Edgewood, MD, was monitored from a distance by a light detection and ranging (LIDAR) laser. Over a 2-week period, an array of air sampling units collected samples were analyzed for the presence of viable spores and using barcode-specific real-time PCR assays. Barcoded B. thuringiensis subsp. kurstaki spores were unambiguously identified on the day of the release, and viable material was recovered in a pattern consistent with the cloud track predicted by prevailing winds and by data tracks provided by the LIDAR system. Finally, the real-time PCR assays successfully differentiated barcoded B. thuringiensis subsp. kurstaki spores from wild-type spores under field conditions.

Background: Various case reports have shown possible associations between optic neuritis and different vaccines. Some of the vaccines include influenza, hepatitis B and anthrax, Purpose: To present evidence for a causal relationship between optic neuritis and Live Attenuated Influenza Vaccine (LAIV), administered as nasal flu vaccine., Methods: Case Report. In a 13-year-old male with bilateral optic neuritis, detailed clinical history, neuro-ophthalmologic examination, magnetic resonance imaging, stereo-disc photos, visual field testing, ocular coherence tomography, blood tests and cerebral spinal fluid analysis were performed., Results: Exam findings on presentation: BCVA: 20/CF OD; 20/LP OS. Positive relative afferent pupil defect OD. Unremarkable anterior segment and posterior segment exam. No papillitis or papilledema. Global visual field defect OU based on Humphrey 30-2. MRI: diffuse enlargement of Optic Chiasm with inflammation of distal optic nerves bilateral. Blood cultures and CSF were negative. Patient received 3 divided doses of methyl prednisone with mild improvement of vision upon hospital discharge and marked improvement of vision at 2 month follow up., Conclusion: In this child, no infectious, vascular, granulomatous, viral or immune-related cause of optic neuritis was identified. This case provides compelling evidence that supports the nasal flu vaccination as a cause of optic neuritis.

Stylar proteins involved in the self-incompatible (SI) response of Lycopersicon hirsutum have been identified and mapped to the locus that controls SI (S locus). L. esculentum, a self-compatible (SC) species of cultivated tomato, does not display these proteins. Hybrids between SC L. esculentum and SI L. hirsutum are self-sterile despite these individuals bearing pollen containing the S allele of L. esculentum. In progeny derived from backcrossing the hybrids to L. esculentum, there was a strong correlation between the presence of the S allele from L. hirsutum and self-infertility. However, this relationship was uncoupled in a number of backcross (BC) progeny. The SI response appeared to be nonexistent in two self-fertile BC individuals that were heterozygous for the S allele of L. hirsutum, based on Mendelian segregation of a tightly linked DNA marker, CD15, in selfed progeny. Among these progeny self-fertile individuals that were homozygous for the L. hirsutum allele of the linked marker were also determined to be homozygous for an S-related proteins are not sufficient to elicit a self-incompatible response in L. esculentum and that there is a mutation(s) in L. esculentum somewhere other than the S locus that leads to self-compatibility.

Lily pollen tubes possess a steep, tip-focused intracellular Ca2+ gradient and a tip-directed extracellular Ca2+ influx. Ratiometric ion imaging revealed that the gradient extends from above 3.0 microM at the apex to approximately 0.2 microM within 20 microns from the tip, while application of the Ca(2+)-specific vibrating electrode indicated that the extracellular influx measured between 1.4 and 14 pmol cm-2 sec-1. We examined the relationship between these phenomena and their role in tube growth by using different 1,2-bis(o-aminophenoxy)ethane N,N,N',N'-tetraacetic acid (BAPTA)-type buffers and hypertonic media. Injection of active BAPTA-type buffers or application of elevated levels of sucrose reversibly inhibited growth, destroyed tip zonation of organelles, and modified normal patterns of cytoplasmic streaming. Simultaneously, these treatments dissipated both the intracellular tip-focused gradient and the extracellular Ca2+ flux. Of the BAPTA-type buffers, 5,5'-dibromo-BAPTA (dissociation constant [Kd] is 1.5 microM) and 4,4'-difluoro-BAPTA (Kd of 1.7 microM) exhibited greater activity than those buffers with either a higher affinity (5,5'-dimethyl-BAPTA, Kd of 0.15 microM; BAPTA, Kd of 0.21 microM; 5,5'-difluoro-BAPTA, Kd of 0.25 microM) or lower affinity (5-methyl, 5'-nitro-BAPTA, Kd of 22 microM) for Ca2+. Our findings provide evidence that growing pollen tubes have open Ca2+ channels in their tip and that these channels become inactivated in nongrowing tubes. The studies with elevated sucrose support the view that stretching of the apical plasma membrane contributes to the maintenance of the Ca2+ signal.

A cDNA encoding a stylar protein was cloned from flowers of self-incompatible wild tomato (Lycopersicon peruvianum). The corresponding gene was mapped to the S locus, which is responsible for self-incompatibility. The nucleotide sequence was determined for this allele, and compared to other S-related sequences in the Solanaceae. The S allele was used to probe DNA from 92 plants comprising 10 natural populations of Lycopersicon peruvianum. Hybridization was conducted under moderate and permissive stringencies in order to detect homologous sequences. Few alleles were detected, even under permissive conditions, underscoring the great sequence diversity at this locus. Those alleles that were detected are highly homologous. Sequences could not be detected in self-incompatible Nicotiana alata, self-compatible L. esculentum (cultivated tomato) or self-compatible L. hirsutum. However, hybridization to an individual of self-incompatible L. hirsutum revealed a closely related sequence that maps to the S locus in this reproductively isolated species. This supports the finding that S locus polymorphism predates speciation. The extraordinarily high degree of sequence diversity present in the gametophytic self-incompatibility system is discussed in the context of other highly divergent systems representing several kingdoms.