Mapping and characterization of Rf 5: a new gene conditioning pollen fertility restoration in A1 and A2 cytoplasm in sorghum (Sorghum bicolor (L.) Moench).

With an aim to further characterize the cytoplasmic male sterility-fertility restoration system in sorghum, a major fertility restoration gene was mapped along with a second locus capable of partial restoration of pollen fertility. The major fertility restoration gene, Rf(5), was located on sorghum chromosome SBI-05, and was capable of restoring pollen fertility in both A(1) and A(2) male sterile cytoplasms. Depending on the restorer parent, mapping populations exhibited fertility restoration phenotypes that ranged from nearly bimodal distribution due to the action of Rf(5), to a more normalized distribution reflecting the action of Rf(5) and additional modifier/partial restoration genes. A second fertility restoration locus capable of partially restoring pollen fertility in A(1) cytoplasm was localized to chromosome SBI-04. Unlike Rf(5), this modifier/partial restorer gene acting alone resulted in less than 10% seed set in both A(1) and A(2) cytoplasms, and modified the extent of restoration conditioned by the major restorer Rf(5) in A(1) cytoplasm. In examining the genomic regions spanning the Rf(5) locus, a cluster of pentatricopeptide gene family members with high homology to rice Rf (1) and sorghum Rf (2) were identified as potential candidates encoding Rf(5).

Molecular mapping and candidate gene identification of the Rf2 gene for pollen fertility restoration in sorghum [Sorghum bicolor (L.) Moench].

The A1 cytoplasmic-nuclear male sterility system in sorghum is used almost exclusively for the production of commercial hybrid seed and thus, the dominant genes that restore male fertility in F(1) hybrids are of critical importance to commercial seed production. The genetics of fertility restoration in sorghum can appear complex, being controlled by at least two major genes with additional modifiers and additional gene-environment interaction. To elucidate the molecular processes controlling fertility restoration and to develop a marker screening system for this important trait, two sorghum recombinant inbred line populations were created by crossing a restorer and a non-restoring inbred line, with fertility phenotypes evaluated in hybrid combination with three unique cytoplasmic male sterile lines. In both populations, a single major gene segregated for restoration which was localized to chromosome SBI-02 at approximately 0.5 cM from microsatellite marker, Xtxp304. In the two populations we observed that approximately 85 and 87% of the phenotypic variation in seed set was associated with the major Rf gene on SBI-02. Some evidence for modifier genes was also observed since a continuum of partial restored fertility was exhibited by lines in both RIL populations. With the prior report (Klein et al. in Theor Appl Genet 111:994-1012, 2005) of the cloning of the major fertility restoration gene Rf1 in sorghum, the major fertility restorer locus identified in this study was designated Rf2. A fine-mapping population was used to resolve the Rf2 locus to a 236,219-bp region of chromosome SBI-02, which spanned ~31 predicted open reading frames including a pentatricopeptide repeat (PPR) gene family member. The PPR gene displayed high homology with rice Rf1. Progress towards the development of a marker-assisted screen for fertility restoration is discussed.

QTL analysis of ergot resistance in sorghum.

Sorghum ergot, caused predominantly by Claviceps africana Frederickson, Mantle, de Milliano, is a significant threat to the sorghum industry worldwide. The objectives of this study were firstly, to identify molecular markers linked to ergot resistance and to two pollen traits, pollen quantity (PQ) and pollen viability (PV), and secondly, to assess the relationship between the two pollen traits and ergot resistance in sorghum. A genetic linkage map of sorghum RIL population R931945-2-2 x IS 8525 (resistance source) was constructed using 303 markers including 36 SSR, 117 AFLP , 148 DArT and two morphological trait loci. Composite interval mapping identified nine, five, and four QTL linked to molecular markers for percentage ergot infection (PCERGOT), PQ and PV, respectively, at a LOD >2.0. Co-location/linkage of QTL were identified on four chromosomes while other QTL for the three traits mapped independently, indicating that both pollen and non pollen-based mechanisms of ergot resistance were operating in this sorghum population. Of the nine QTL identified for PCERGOT, five were identified using the overall data set while four were specific to the group data sets defined by temperature and humidity. QTL identified on SBI-02 and SBI-06 were further validated in additional populations. This is the first report of QTL associated with ergot resistance in sorghum. The markers reported herein could be used for marker-assisted selection for this important disease of sorghum.

Proliferation of human fibroblasts in vitro after exposure to orbital implants.

BACKGROUND: Porous orbital implants allow fibrovascular ingrowth and integration with the extraocular muscles. The available implants have different structural characteristics, which may influence orbital response. We studied the proliferation of orbital fibroblasts in vitro after exposure to four different orbital implants. METHODS: Four orbital implant biomaterials were studied: hydroxyapatite (Bio-Eye), synthetic hydroxyapatite, porous polyethylene (Medpor) (pore sizes 150 microm and 400 microm) and aluminium oxide (Bioceramic implant). Human fibroblasts obtained from orbital fat at the time of elective blepharoplasty were cultured and then exposed to the individual implants. Cell growth was assessed with immunocytochemical analysis using bromodeoxyuridine, a thymidine analogue. After DNA denaturation, the cells were washed, incubated with secondary antibody and visualized. RESULTS: The fibroblasts growing on the Bio-Eye, synthetic hydroxyapatite, and 150-microm and 400-microm Medpor implants all had debris associated with them. The Bioceramic implant was free of this debris. The Bioceramic implant and the 150-microm Medpor implant had the greatest number of fibroblasts on the coverslips. INTERPRETATION: The proliferation of fibroblasts, as determined by visualization of actively dividing cells with bromodeoxyuridine, differed on the various implants studied. The lack of debris associated with the Bioceramic implant may be related to the crystalline structure of the implant.

The bioceramic orbital implant: a new generation of porous implants.

PURPOSE: The authors describe a new generation of porous orbital implant made of aluminum oxide (Al2O3) and compare it with the hydroxyapatite orbital implants (Bio-Eye and FCI hydroxyapatite). METHODS: The authors examined the new implant macroscopically, with chemical analysis and microscopically with scanning electron microscopy. Animal implantation studies were performed using six adult male New Zealand albino rabbits. Implant vascularization was evaluated by means of magnetic resonance imaging and histopathologic sectioning. RESULTS: The Bioceramic orbital implant was found to have very uniform pore structure with an average pore size of 500 microm. The implant was 99.9% aluminum oxide on x-ray diffraction. Magnetic resonance imaging in vivo vascularization studies demonstrated enhancement of the implant to its center by 4 weeks after implantation in the rabbit. Histopathologically, fibrovascularization occurred uniformly throughout the implant and was noted by 4 weeks. CONCLUSIONS: The Bioceramic orbital implant represents a new porous orbital implant that has a very regular and extensive interconnected pore system, is as biocompatible as hydroxyapatite, is easy to manufacture, structurally strong, and free of contaminants. It is manufactured with no disruption to marine life ecosystems as may occur in the harvesting of coral for other orbital implants. It is less expensive than currently available hydroxyapatite implants and was approved by the U.S. Food and Drug Administration in April 2000.

Mucoepidermoid carcinoma of the conjunctiva: a series of three cases.

OBJECTIVE: To detail the clinical presentation and outcomes of currently available treatments for mucoepidermoid carcinoma of the conjunctiva (MCC). DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Three patients ranging from 40 to 63 years of age with MCC participated. INTERVENTION: Excisional biopsies and various therapies were performed. MAIN OUTCOME MEASURES: Clinical and surgical outcomes were measured. RESULTS: Patient 1 is a 55-year-old man with right temporal MCC. He underwent two local excisions with adjuvant cryotherapy and has had no recurrence at 31 months follow-up. Patient 2 is a 63-year-old man with right temporal MCC who underwent fractionated iodine 125 plaque radiotherapy. He had a recurrence approximately 8 months after plaque treatment and subsequently underwent enucleation of the right eye. Clinical follow-up examinations revealed no further recurrence at 17 months. Patient 3 is a 40-year-old woman treated for right MCC with carbon dioxide laser with recurrence at 3 weeks. She subsequently underwent radiation treatment with the development of regional lymph node metastases 16 months later. CONCLUSIONS: MCC is a rare neoplasm that displays an extraordinary capacity for aggressive local invasion. This series of three case reports demonstrates the high recurrence rate of MCC and the response of this tumor to different current modalities of treatment. Extended follow-up is required with this tumor because distant metastases can occur very late.

Scanning electron microscopic examination of porous orbital implants.

OBJECTIVE: To compare the structural makeup of five porous orbital implants: two made of coralline hydroxyapatite (Bio-Eye and Chinese implant), one of synthetic hydroxyapatite (FCI), one of porous polyethylene (Medpor) and one of alumina. The Bio-Eye, Medpor and alumina implants are currently available in Canada. OUTCOME MEASURES: Pore size, pore interconnectivity and microcrystalline architecture. RESULTS: The Bio-Eye had multiple interconnected pores ranging from 300 microns to 700 microns in width; higher-power views showed coarse-appearing crystals approximately 2 microns wide. The FCI implant showed similar interconnectivity of the pores but fewer pores, which were about 300 microns to 500 microns in size. Higher-power views showed hexagonal crystals about 1 micron to 5 microns in size. The Chinese hydroxyapatite implant had multiple interconnected pores ranging from 200 microns to 700 microns in size. The crystals were similar in appearance to those of the Bio-Eye but were smaller and more granular. The 150-micron pore size Medpor implant had irregularly shaped pores ranging from 100 microns to 500 microns in size. The 400-micron pore size implant had pores that looked more like channels that coalesced; the pores and channels ranged in size from 125 microns to 1000 microns. In both cases higher-power views showed a woven texture. In the alumina implant the pores were well connected and evenly distributed and were approximately 500 microns in size. On high-power studies the implant showed a cobblestone-like pattern of crystals approximately 4 microns to 5 microns wide. CONCLUSIONS: There are notable differences in pore size, pore interconnectivity and microcrystalline architecture between the implants studied. These features may be important in the overall biocompatibility of the implant.

Necrotizing fasciitis caused by group A streptococcus infection after laser blepharoplasty.

PURPOSE: To describe a patient who developed early signs of necrotizing fasciitis after undergoing laser blepharoplasty. METHODS: A 36-year-old woman developed wound discharge, wound dehiscence, and facial swelling 66 hours postblepharoplasty. Cloxacillin was administered but changed to high-dose intravenous penicillin G and clindamycin when the eyelid cultures grew group A streptococcus (an organism capable of causing necrotizing fasciitis organism). RESULTS: The patient was treated with intravenous antibiotics for 10 days followed by 3 weeks of oral medications. The wounds healed spontaneously with an excellent result. CONCLUSIONS: Infection postblepharoplasty is rare. When it occurs, tissue destruction can be potentially devastating. Prompt diagnosis, intravenous antibiotics, and close follow-up are essential.

Avoiding blood loss in outpatient dacryocystorhinostomy.

The control of perioperative hemorrhage is a concern in dacryocystorhinostomy, which has traditionally been done as an inpatient procedure, often with general anesthesia. The trend now is toward outpatient surgery under local anesthesia. With proper patient selection and education, adequate anesthesia, and a meticulous surgical technique aimed at preventing blood loss, complications related to outpatient dacryocystorhinostomy can be minimal and associated with a high degree of patient acceptance. This article reviews my technique and experience in preventing blood loss in 434 procedures over 3 years.

The potential damaging effects of light on the eye (Part II).

The electromagnetic spectrum consists of radiant energy that is classified according to specific wavelengths. Man is constantly exposed to a portion of the electromagnetic spectrum, particularly to radiation in the ultraviolet, visible and infrared regions. The tissues of the eye and skin are particularly sensitive to the non-ionizing wavelengths of radiant energy. Although both tissues possess endogenous protective mechanisms to minimize the effects of such exposure, problems still occur due to the absorption of radiation. The cornea, lens and retina have been shown to be susceptible to damage from light in the ultraviolet, visible and infrared range. Part I of this two-part article, which examined the structures of the eye that are most susceptible to light damage, appeared in the October issue of the Journal; in this, the second and final part of his article, the author focuses on eye protection.