Transcription Factor MYB26 Is Key to Spatial Specificity in Anther Secondary Thickening Formation.

Successful fertilization relies on the production and effective release of viable pollen. Failure of anther opening (dehiscence), results in male sterility, although the pollen may be fully functional. MYB26 regulates the formation of secondary thickening in the anther endothecium, which is critical for anther dehiscence and fertility. Here, we show that although the MYB26 transcript shows expression in multiple floral organs, the MYB26 protein is localized specifically to the anther endothecium nuclei and that it directly regulates two NAC domain genes, NST1 and NST2, which are critical for the induction of secondary thickening biosynthesis genes. However, there is a complex relationship of regulation between these genes and MYB26. Using DEX-inducible MYB26 lines and overexpression in the various mutant backgrounds, we have shown that MYB26 up-regulates both NST1 and NST2 expression. Surprisingly normal thickening and fertility rescue does not occur in the absence of MYB26, even with constitutively induced NST1 and NST2, suggesting an additional essential role for MYB26 in this regulation. Combined overexpression of NST1 and NST2 in myb26 facilitates limited ectopic thickening in the anther epidermis, but not in the endothecium, and thus fails to rescue dehiscence. Therefore, by a series of regulatory controls through MYB26, NST1, NST2, secondary thickening is formed specifically within the endothecium; this specificity is essential for anther opening.

Effect of strontium citrate on bone consolidation during mandibular distraction osteogenesis.

OBJECTIVES/HYPOTHESIS: Mandibular distraction osteogenesis (MDO) involves a lengthy consolidation phase where complications can occur. Strontium is an element that has been shown to improve bone healing. The objective of this study was to determine whether strontium citrate can be used to enhance bone healing during MDO in a rabbit model. STUDY DESIGN: Prospective animal model study. METHODS: Custom-made MDO devices were placed on 20 New Zealand White rabbits. After a 7-day latency period, distraction was performed at 1 mm/day for 5 days. The study group rabbits (n = 10) received oral strontium citrate; the other 10 rabbits served as controls. Mandibles were removed at the end of the consolidation period (4 weeks). Formation and healing of new bone were evaluated with microcomputed tomography, histology, and a three-point bending mechanical test. RESULTS: New bone formed in all animals, but the consolidation process was enhanced in rabbits that received strontium. The histological analysis showed that study group rabbits had more mature bone. Microcomputed tomographic images demonstrated significantly higher bone density for study group animals, and the three-point bending test results demonstrated that the maximum load of the study group specimens was significantly greater than that of the control group mandibles. CONCLUSIONS: Strontium citrate improved the formation of new bone in the current rabbit model of MDO. The prolonged consolidation period may be shortened with strontium citrate, which may also have the potential to reduce complications. LEVEL OF EVIDENCE: NA Laryngoscope, 127:E212-E218, 2017.

Electrosurgical transurethral resection of the prostate and transurethral incision of the prostate (monopolar techniques).

INTRODUCTION: We summarize the current guidelines, techniques, efficacy and complications associated with monopolar transurethral resection of the prostate (TURP) and transurethral incision of the prostate (TUIP) for benign prostatic hyperplasia (BPH). Patients who elect to have endoscopic surgical bladder outlet reduction are faced with an abundance of evolving treatment options. As new technology comes and goes, TURP and TUIP remain the gold standard for which new treatments are compared. MATERIALS AND METHODS: A review of past and contemporary data including American and European guidelines was performed. Techniques, efficacy, durability, short term and long term complications of TURP and TUIP are summarized. RESULTS: Small prostate sizes < 30 mL without a median lobe can be effectively treated with TUIP with decreased perioperative complications and sexual side effects compared to TURP. Monopolar TURP demonstrates significant improvements in IPSS, peak flow rate (Qmax), and quality of life (QoL) with durable (8 year-22 year) outcomes. Secondary intervention increases by 1%-2% annually. Thirty-day mortality rate is low (0.1%) as well as incidence of TUR syndrome (< 1.1%). Short term and long term complications include bleeding requiring transfusion, clot retention, acute urinary retention (AUR), and urinary tract infections as well as incontinence, bladder neck contracture, urethral stricture, and sexual dysfunction. CONCLUSIONS: Monopolar TURP and TUIP are effective endoscopic treatments for BPH with durable long term results. While the short term and long term complication rates are acceptable, new technologies aim to increase tolerability of bladder outlet reduction by decreasing treatment related morbidity.

Characterization of the fungal gibberellin desaturase as a 2-oxoglutarate-dependent dioxygenase and its utilization for enhancing plant growth.

The biosynthesis of gibberellic acid (GA(3)) by the fungus Fusarium fujikuroi is catalyzed by seven enzymes encoded in a gene cluster. While four of these enzymes are characterized as cytochrome P450 monooxygenases, the nature of a fifth oxidase, GA(4) desaturase (DES), is unknown. DES converts GA(4) to GA(7) by the formation of a carbon-1,2 double bond in the penultimate step of the pathway. Here, we show by expression of the des complementary DNA in Escherichia coli that DES has the characteristics of a 2-oxoglutarate-dependent dioxygenase. Although it has low amino acid sequence homology with known 2-oxoglutarate-dependent dioxygenases, putative iron- and 2-oxoglutarate-binding residues, typical of such enzymes, are apparent in its primary sequence. A survey of sequence databases revealed that homologs of DES are widespread in the ascomycetes, although in most cases the homologs must participate in non-gibberellin (GA) pathways. Expression of des from the cauliflower mosaic virus 35S promoter in the plant species Solanum nigrum, Solanum dulcamara, and Nicotiana sylvestris resulted in substantial growth stimulation, with a 3-fold increase in height in S. dulcamara compared with controls. In S. nigrum, the height increase was accompanied by a 20-fold higher concentration of GA(3) in the growing shoots than in controls, although GA(1) content was reduced. Expression of des was also shown to partially restore growth in plants dwarfed by ectopic expression of a GA 2-oxidase (GA-deactivating) gene, consistent with GA(3) being protected from 2-oxidation. Thus, des has the potential to enable substantial growth increases, with practical implications, for example, in biomass production.

The final split: the regulation of anther dehiscence.

Controlling male fertility is an important goal for plant reproduction and selective breeding. Hybrid vigour results in superior growth rates and increased yields of hybrids compared with inbred lines; however, hybrid generation is costly and time consuming. A better understanding of anther development and pollen release will provide effective mechanisms for the control of male fertility and for hybrid generation. Male sterility is associated not only with the lack of viable pollen, but also with the failure of pollen release. In such instances a failure of anther dehiscence has the advantage that viable pollen is produced, which can be used for subsequent rescue of fertility. Anther dehiscence is a multistage process involving localized cellular differentiation and degeneration, combined with changes to the structure and water status of the anther to facilitate complete opening and pollen release. After microspore release the anther endothecium undergoes expansion and deposition of ligno-cellulosic secondary thickening. The septum separating the two locules is then enzymatically lysed and undergoes a programmed cell death-like breakdown. The stomium subsequently splits as a consequence of the stresses associated with pollen swelling and anther dehydration. The physical constraints imposed by the thickening in the endothecium limit expansion, placing additional stress on the anther, so as it dehydrates it opens and the pollen is released. Jasmonic acid has been shown to be a critical signal for dehiscence, although other hormones, particularly auxin, are also involved. The key regulators and physical constraints of anther dehiscence are discussed.