The complex polyploid genome architecture of sugarcane.

Sugarcane, the world's most harvested crop by tonnage, has shaped global history, trade and geopolitics, and is currently responsible for 80% of sugar production worldwide1. While traditional sugarcane breeding methods have effectively generated cultivars adapted to new environments and pathogens, sugar yield improvements have recently plateaued2. The cessation of yield gains may be due to limited genetic diversity within breeding populations, long breeding cycles and the complexity of its genome, the latter preventing breeders from taking advantage of the recent explosion of whole-genome sequencing that has benefited many other crops. Thus, modern sugarcane hybrids are the last remaining major crop without a reference-quality genome. Here we take a major step towards advancing sugarcane biotechnology by generating a polyploid reference genome for R570, a typical modern cultivar derived from interspecific hybridization between the domesticated species (Saccharum officinarum) and the wild species (Saccharum spontaneum). In contrast to the existing single haplotype ('monoploid') representation of R570, our 8.7 billion base assembly contains a complete representation of unique DNA sequences across the approximately 12 chromosome copies in this polyploid genome. Using this highly contiguous genome assembly, we filled a previously unsized gap within an R570 physical genetic map to describe the likely causal genes underlying the single-copy Bru1 brown rust resistance locus. This polyploid genome assembly with fine-grain descriptions of genome architecture and molecular targets for biotechnology will help accelerate molecular and transgenic breeding and adaptation of sugarcane to future environmental conditions.

Association of gene expression with syringyl to guaiacyl ratio in sugarcane lignin.

KEY MESSAGE: A transcriptome analysis reveals the transcripts and alleles differentially expressed in sugarcane genotypes with contrasting lignin composition. Sugarcane bagasse is a highly abundant resource that may be used as a feedstock for the production of biofuels and bioproducts in order to meet increasing demands for renewable replacements for fossil carbon. However, lignin imparts rigidity to the cell wall that impedes the efficient breakdown of the biomass into fermentable sugars. Altering the ratio of the lignin units, syringyl (S) and guaiacyl (G), which comprise the native lignin polymer in sugarcane, may facilitate the processing of bagasse. This study aimed to identify genes and markers associated with S/G ratio in order to accelerate the development of sugarcane bioenergy varieties with modified lignin composition. The transcriptome sequences of 12 sugarcane genotypes that contrasted for S/G ratio were compared and there were 2019 transcripts identified as differentially expressed (DE) between the high and low S/G ratio groups. These included transcripts encoding possible monolignol biosynthetic pathway enzymes, transporters, dirigent proteins and transcriptional and post-translational regulators. Furthermore, the frequencies of single nucleotide polymorphisms (SNPs) were compared between the low and high S/G ratio groups to identify specific alleles expressed with the phenotype. There were 2063 SNP loci across 787 unique transcripts that showed group-specific expression. Overall, the DE transcripts and SNP alleles identified in this study may be valuable for breeding sugarcane varieties with altered S/G ratio that may provide desirable bioenergy traits.

Betaine aldehyde dehydrogenase in plants.

Plant betaine aldehyde dehydrogenases (BADHs) have been the target of substantial research, especially during the last 20 years. Initial characterisation of BADH as an enzyme involved in the production of glycine betaine (GB) has led to detailed studies of the role of BADH in the response of plants to abiotic stress in vivo, and the potential for transgenic expression of BADH to improve abiotic stress tolerance. These studies have, in turn, yielded significant information regarding BADH and GB function. Recent research has identified the potential for BADH as an antibiotic-free marker for selection of transgenic plants, and a major role for BADH in 2-acetyl-1-pyrroline-based fragrance associated with jasmine and basmati style aromatic rice varieties.

A novel highly differentially expressed gene in wheat endosperm associated with bread quality.

Analysis of gene expression in developing wheat seeds was used to identify a gene, wheat bread making (wbm), with highly differential expression (~1000 fold) in the starchy endosperm of genotypes varying in bread making quality. Several alleles differing in the 5'-upstream region (promoter) of this gene were identified, with one present only in genotypes with high levels of wbm expression. RNA-Seq analysis revealed low or no wbm expression in most genotypes but high expression (0.2-0.4% of total gene expression) in genotypes that had good bread loaf volume. The wbm gene is predicted to encode a mature protein of 48 amino acids (including four cysteine residues) not previously identified in association with wheat quality, possibly because of its small size and low frequency in the wheat gene pool. Genotypes with high wbm expression all had good bread making quality but not always good physical dough qualities. The predicted protein was sulphur rich suggesting the possibility of a contribution to bread loaf volume by supporting the crossing linking of proteins in gluten. Improved understanding of the molecular basis of differences in bread making quality may allow more rapid development of high performing genotypes with acceptable end-use properties and facilitate increased wheat production.

Evaluating the potential of SSR flanking regions for examining taxonomic relationships in the Vitaceae.

Three EST-derived microsatellite loci from Vitis vinifera were amplified and sequenced across eight species of Vitaceae from four different genera. Phylogenetic analysis of the microsatellite's flanking regions produced informative results in congruence with previous studies. Generic relationships were respected and the data produced sufficient inter-specific variation to distinguish between Cayratia acris and Cayratia saponaria, two very closely related species. Overall, the sequence alignments showed that priming sites were conserved, whereas microsatellite repeats were present in most cases but structurally variable. The sequence data provided information on the evolutionary patterns of various microsatellite repeats and their correlation to evolutionary relationships among taxa.

Influence of operatory size and nitrous oxide concentration upon scavenger effectiveness.

Concern regarding environmental health hazards for dental personnel chronically exposed to waste nitrous oxide (N2O) prompted this investigation. The influence on ambient N2O levels of scavenging, operatory size, and N2O concentration delivered to the patient was evaluated during treatment of 36 pediatric dental patients. The results showed that scavenging significantly reduced ambient N2O levels measured at 50-56 cm from the patient's nose. Scavenged ambient N2O levels were also observed to decrease when N2O concentrations administered to the patient were reduced from 50 to 30%. This concentration effect was not observed in the non-scavenged groups. ANOVA showed that operatory size exerted a non-significant influence on ambient N2O. The data collected during routine treatment of pediatric dental patients demonstrated that the scavenging system tested significantly reduced waste N2O in the operator's breathing zone, nearly approximating the 25-ppm recommendation established by the National Institute for Occupational Safety and Health (NIOSH).

Operatory ventilation and scavenger evacuation rate influence on ambient nitrous oxide levels.

Investigations have shown that greater than Federally-recommended levels of ambient nitrous oxide often exist in the dental workplace. The purposes of this investigation were to examine the influences of (1) operatory ventilation rate and (2) scavenger evacuation rate on ambient nitrous oxide concentrations within a closed dental operatory. This laboratory investigation utilized a scavenging nasal mask assembly (Porter/Brown) to deliver 40% nitrous oxide in oxygen, at a total flow rate of 5 L/min, to a mannequin positioned supinely in a dental chair. Eight experimental groups were assigned based on combinations of operatory air exchange rates (0, 5, 10, or 15 room air changes per hour) and scavenger evacuation rates (18.8 L/min and 21.4 L/min). Ambient nitrous oxide levels were monitored at four locations (0, 15.3, 30.7, and 61.4 cm) from the nasal mask by means of an infrared spectrophotometer (Miran 1B). The operatory air exchange rate was measured with a flow hood (Short Ridge) and manipulated to one of the desired ventilation rates. Time-weighted average (TWA) concentrations of ambient nitrous oxide (ppm) were continuously recorded at 15-second intervals with a microprocessor (DL332F Datalogger) connected directly to a microcomputer. The results demonstrated that significantly reduced (p < 0.05) ambient nitrous oxide levels were achieved with increasing room air exchange rates and the high scavenger evacuation rate. It was concluded that operatory ventilation and scavenger evacuation rates were significant control measures available for reduction of ambient nitrous oxide to Federally recommended levels.

Influence of chronic ethanol exposure on nitrous oxide analgesia in mice.

The purpose of this study was to determine whether sensitivity to nitrous oxide analgesia was altered by chronic ethanol exposure. Control mice exposed to 25%, 50%, and 75% nitrous oxide in oxygen demonstrated a concentration-related analgesic effect, as measured by the acetic acid abdominal constriction test. Other mice previously exposed to ethanol vapors for 72 h exhibited a significantly reduced sensitivity to nitrous oxide analgesia. The dose-response curve of the chronic ethanol-exposed group was shifted to the right of that of the control mice. These findings suggest the possibility that subjects with a history of alcohol abuse might have reduced responsiveness to nitrous oxide in a clinical setting.

An improved procedure for the methylation analysis of oligosaccharides and polysaccharides.

An improved procedure for the methylation analysis of oligosaccharides and polysaccharides is described. Steps in the procedure were examined and optimised for quantitative recovery and speed. Methylation was shown to be complete by using [14C]methyl iodide. All operations were performed in the same tube and the need to concentrate solutions containing acetylated alditols of methylated sugars was eliminated, thus minimising losses due to volatilization. The method is convenient, gives high recoveries of acetylated alditols of methylated sugars, and allows analysis of the glycosyl linkages of oligo- or poly-saccharides to be completed within a working day. A wide range of oligo- and poly-saccharides were methylated by this procedure.

Malignant melanoma of the vulva. Australian experience.

Malignant melanoma is an uncommon but aggressive tumor, and the vulva seems to have an increased predisposition for developing it. Vulvar melanoma appears to behave similarly to truncal melanoma, but its later presentation, due to its less accessible and less visible site, gives the false impression of more aggressive behavior. In spite of that the survival, stage by stage, is not markedly different from that of truncal melanoma. Traditionally it has been treated in the same manner as vulvar squamous cell carcinoma, with extreme but often therapeutically inadequate radical surgery. For lesions less than 0.75 mm in depth, wide excision with a 2-cm margin is adequate. Deeper lesions require radical local excision and bilateral groin lymphadenectomy through separate incisions.

Assessing environmental health concerns associated with nitrous oxide.

Concerns about the effects of occupational exposure to nitrous oxide have existed for a decade. Unfortunately, data are lacking that document biologically tolerable exposure levels. Current guidelines regarding use of N2O are reviewed.

Ambient nitrous oxide levels during pediatric sedations.

Various studies have implicated generalized health problems with chronic exposure to trace levels of nitrous oxide. Recent investigations have reported that higher-than-recommended levels of nitrous oxide exist in the breathing zone of the dental staff. This study was undertaken to accurately determine waste nitrous oxide levels during pediatric sedations and to evaluate the effect of scavenging in reducing environmental exposure. Conscious sedations were performed on 20 uncooperative 2-4-year old children. Each child was assigned randomly to one of two groups, a scavenged group and a nonscavenged control. Sedations were accomplished with oral administration of chloral hydrate and hydroxyzine. All patients received nitrous oxide (40%) in oxygen throughout the procedure. Waste nitrous oxide levels were monitored 22-24 in from the dentist's nose using an infrared spectrophotometer and recorded by a microprocessor. Results indicate that environmental levels of nitrous oxide exceed the National Institute for Occupational Safety and Health (NIOSH) recommendations by 12 times, regardless of whether a scavenging system was employed or not. It is concluded that the scavenging system tested in this investigation may not be as efficient as previously thought at complying with NIOSH recommendations.

A labially positioned mesiodens: case report.

This case report describes a labially positioned maxillary midline mesiodens in an 8-year-old male. The clinical and radiographic appearance and therapeutic considerations are presented. The purpose of this article is to alert the clinician to the importance of radiographic localization prior to surgical intervention, because in some instances a labial surgical approach is preferred over the traditional palatal technique. In this case a labial surgical approach was utilized which allowed for greater conservation of alveolar bone and improved access during removal of the mesiodens.

The influence of midazolam and nitrous oxide on respiratory depression in laboratory rats.

Midazolam in combination with nitrous oxide (N2O) is a commonly used sedative approach for pediatric dental patients. Respiratory morbidity and mortality have been reported with midazolam administration, particularly when used in combination with other drugs in the absence of supplemental oxygen. Thus, the purpose of this investigation was to determine the effect of midazolam alone and in combination with N2O on respiration in laboratory rats by measuring arterial blood gas levels. Sixty-four Sprague-Dawley rats, weighing 250-320 g, were assigned to one of eight groups (eight per group). Groups were allocated based upon the dosage of midazolam administered (0, 1.0, 2.0 or 4.0 mg/kg i.p.) and exposure to N2O/02 (50%/50%) or room air. Arterial blood was obtained from a femoral artery catheter and pH, O2, CO2 (mm Hg), and oxygen saturation (%) were determined. Samples were analyzed using a System 1306 pH/Blood Gas Analyzer. Baseline arterial blood gasses were obtained for each animal and at 15-min intervals following midazolam administration throughout the 45-min experiment. Following midazolam administration, animals were placed into a sealed chamber through which flowed either N2O or room air. Group comparisons demonstrated that: 1) arterial CO2 levels increased in midazolam-exposed animals breathing room air, but not in those exposed to N2O (P < 0.05), and 2) as expected, N2O/O2-exposed animals showed an increase in arterial O2 and a %saturation that was not observed in room air groups (P < 0.01). This investigation demonstrated that coadministration of N2O/O to midazolam-exposed animals did not result in hypercarbia, an early indicator of respiratory depression.

The effects of various dental procedures and patient behaviors upon nitrous oxide scavenger effectiveness.

This prospective study of 36 children, ages 44-93 months, receiving nitrous oxide-oxygen under standardized conditions during routine dental procedures was conducted to determine what influence eight selected dental procedures and three patient behaviors had on ambient nitrous oxide (N2O) levels in the dentist's breathing zone. Half the children received nitrous oxide-oxygen via a scavenging nasal mask. An infrared spectrophotometer analyzed the ambient N2O level continuously throughout the procedure and the time-weighted average (TWA) for consecutive 15-sec intervals was recorded by a microprocessor. A video camera was used to synchronize the coded dental procedures and patient behaviors to the TWA ambient N2O levels recorded. The results demonstrated that scavenging significantly reduced the dentist's exposure to ambient N2O (P less than 0.05, nonscavenged mean = 284.7 ppm; scavenged mean = 36.6 ppm), but the mean TWA N2O concentration remained significantly higher, P less than 0.05, than the 25-ppm level recommended by the National Institute for Occupational Safety and Health (NIOSH). Supplemental oral evacuation was the only dental procedure capable of reducing ambient N2O to below NIOSH's recommendation when scavenging was employed. The administration of local anesthesia consistently created a significant increase in ambient N2O levels. Patient behaviors of talking, crying, and movement also resulted in significant increases from baseline ambient N2O levels.

A pharmacokinetic study of midazolam in dogs: nasal drop vs. atomizer administration.

PURPOSE: The purpose of this investigation was to compare the pharmacokinetics of midazolam following intravenous, intranasal drop, and nasal-atomizer administration in beagle dogs. METHODS: Six animals weighing 9-13 kg were used in a repeated-measure design, group assignment based on route of drug administration. Midazolam (1.5 mg/kg) was administered with the delivery route based on group assignment. Blood samples were obtained at baseline and at 1, 3, 5, 7, 10, 15, 20, 30, and 45 min after administration. Cerebrospinal fluid samples (CSF) were obtained at 5 and 10 min after administration. Plasma and CSF concentrations of midazolam were determined by electron-capture gas-liquid chromatography. RESULTS: Comparison between groups and over time demonstrated that both nasal routes resulted in significantly higher CSF concentrations relative to corresponding plasma levels, and that nasal-atomizer administration produced significantly higher CSF concentrations compared to the drop approach.

Dental management of children with asthma.

Asthma affects about 1 in 10 children. The condition is characterized by acute respiratory distress brought on by environmental factors. The condition is treated with medications aimed to reduce reaction to stimulants by the airway. Dental management involves attention to the status of the patient and awareness of stimulants of the reactive airway. Clinical recommendations are provided.

Pediatric dental emergencies.

Odontogenic infections and orofacial trauma are the most common types of pediatric dental emergencies. The avulsion of a child's permanent tooth or spread of an odontogenic infection through facial planes present serious medical problems requiring expedited care to achieve a favorable prognosis.

Cardiovascular influences of nitrous oxide in spontaneously hypertensive rats.

Cardiovascularly compromised outpatients undergoing minor elective oral surgical or dental care have not frequently received the anxiolytic and analgesic benefits of nitrous oxide ostensibly because of the reported likelihood of sympathetic nervous stimulation and possible exacerbation of hypertension or cardiac complication. Recent studies, though, have shown that the hemodynamic effects of nitrous oxide are negligible and possibly even beneficial. The present study was conducted to determine the cardiovascular effects of nitrous oxide and nitrogen (as control gas) in the spontaneously hypertensive rat (SHR) and its normotensive Wistar-Kyoto counterpart (WKY). SHRs exposed to nitrogen did not exhibit any significant change in SBP or HR, but SHRs exposed to nitrous oxide exhibited a generally concentration-related reduction in both SBP and HR. WKYs, however, displayed reductions in SBP and HR when exposed to either nitrous oxide or nitrogen. These findings indicate a difference in the hemodynamic responses of SHRs and WKYs to nitrous oxide and nitrogen. The specificity and mechanism of the nitrous oxide effects in hypertension were not determined in this study, however, these findings do indicate that nitrous oxide does not exacerbate hypertension in normal or hypertensive rats.

The influence of meperidine and nitrous oxide on respiratory depression in rats.

Narcotic sedation is commonly accomplished with nitrous oxide (N2O) coadministration. Concerns regarding respiratory morbidity and mortality with drug combinations have been reported in the literature, particularly in patients not receiving supplemental oxygen (O2). The purpose of this investigation was to determine the effect of meperidine alone and in combination with N2O on respiration in laboratory rats by evaluating cardiovascular and arterial blood gas data. Fifty-four Sprague-Dawley rats were assigned to one of six groups (nine per group). Groups were allocated based upon the dosage of meperidine administered (0, 4.0, or 8.0 mg/kg intraperitoneally [i.p.]) and exposure to N2O (50% with oxygen) or O2 (100%). Following meperidine administration, animals were placed into a sealed chamber through which flowed either N2O or O2. Arterial blood was obtained, at baseline and at 15-min intervals, from a femoral artery catheter and pH, O2, CO2 (mm Hg), and oxygen saturation (%) were determined. Plasma samples were analyzed using a System 1306 pH/blood gas analyzer. Group comparisons demonstrated that: (a) N2O coadministration, in animals pretreated with meperidine, did not result in increased arterial CO2 levels, and (b) as expected, arterial O2 levels in all groups increased significantly from preexposure baseline values (P < 0.05). This investigation demonstrated that the coadministration of N2O to meperidine-sedated animals did not enhance respiratory depression.