Peter Ray

IN a previous note on ``A New Type of Complex Silver Compounds with Tervalent Silver''1, the composition of ethylenebiguanide was represented as that given by Dittler2 as, well as by Dübsky and co-workers3. This is, however, not correct. It has now been found that the so-called ethylenebiguanide, as prepared by us following the method described by Dittler and also by Dübsky and co-workers, is really an ethylene dibiguanide, En(BigH)2, of the composition C6N10H16. It behaves as a quadridentato molecule with four points of attachment to the central silver atom instead of being bidentate like the so-called ethylenebiguanide. This difference was not detected before, as we had no reason to suspect the composition of the compound and satisfied ourselves only with the estimation of nitrogen and sulphate in a sample of the substance, which, however, agreed with those given by Dübsky and co-workers. A subsequent estimation of carbon and water both in the substance under discussion and in its complex silver salt revealed this difference; 2 C4N5H9.H2SO4 gives almost the same values for nitrogen and sulphate as C6N10H162H2SO4.1.5H2O.

Large fires are uncommon in Alaskan arctic tundra. However, the frequency of lightning strikes on the North Slope of Alaska has increased greatly in the past two decades as climate has warmed. The Anaktuvuk River Fire (ARF) of 2007 burned 1000 km2 on the Alaskan North Slope, and was unprecedented in terms of area burned and severity for tundra fires north of 68o N, with more than 80% of the area burned with moderate to high severity. In 2008, we established 24 permanent transects in burned areas, covering a range of vegetation types and burn severities. In 2008 and 2010, we established an additional 17 reference transects in unburned areas in the vicinity of the ARF, matched to vegetation types sampled within the ARF. In 2008, 2009, and 2010, we followed vegetation cover along these transects, active layer thickness, and N availability using ion exchange resin bags (in a subset of transects). We also measured soil pH in organic soils in 2010. Despite the unusually high severity of the fire, vegetation cover has recovered substantially over the first three years. By 2009, relative cover of live vascular plant cover in the ARF transects was approximately two-thirds of that found in the reference transects, while non-vascular plant cover was approximately 1/3 of that in the reference transects. Most of the vascular plant cover is comprised of resprouting biomass from individuals present before the fire, which were damaged but not completely killed. Tussocks of Eriophorum vaginatum resprouted vigorously in the first year following the fire, and tussock mortality was estimated at only 10%. Shrub mortality appeared to be much higher, >50%, but was hard to estimate due to consumption of stems and roots. Resprouting of shrubs was more evident in 2009 and 2010 than in 2008. At present, graminoid cover is greater than shrub cover, but shrub cover increased more than graminoid cover between 2008 and 2010. No non-native vascular plant species have colonized in our ARF transects so far, although certain grass species found at low abundance in the reference transects are more abundant in severely burned transects. In contrast, much of the cover of non-vascular vegetation is comprised of species that were not abundant in tundra before the fire, but are common following fire in boreal forest. These include the liverwort Marchantia polymorpha, and the mosses Ceratodon purpureus and Pohlia nutans. Soil inorganic nitrogen and phosphorus availability, as measured with resin bags, was approximately 3 times higher in the burned transects than in reference transects in 2009. Thawing and subsidence occurred in a minority of the transects, where there was evidence of previous frost-scarring, and numerous thermokarst features have been documented in the ARF by other researchers. However, over most of the landscape that we sampled, the terrestrial ecosystem appears to be resilient, and vegetation recovery is rapid.

When dark-grown maize (Zea mays L.) seedlings were exposed to red light (R), Golgi-localized glucan synthetase activity in the mesocotyl began to decrease within 1 h, and fell by approx. 70% in 12 h. The response required at least 10(-2) μmol m(-2) R and saturated at 100 μmol m(-2). Far-red light (FR) alone inhibited glucan synthetase, and FR reversed the inhibition by R back to the level caused by FR alone. Density gradient fractionation indicated that of the major membrane markers only the Golgi-localized glucan-synthetase activity was affected by R. Golgi-localized latent inosine-diphosphatase activity was unaffected. The kinetics of the response, the photon fluence dependence, and the reversibility by FR all correlated with the inhibition by light of elongation of the mesocotyl, indicating that light inhibits growth and glucan synthetase activity by a similar mechanism.

Auxin promotes the liberation of a xlyoglucan polymer from the cell walls of elongating pea (Pisum sativum) stem segments. The released polymer can be isolated from the polysaccharide fraction of the water-soluble portion of tissue homogenates, thus providing as assay for this kind of metabolism. Promotion of xyloglucan metabolism by auxin begins within 15 minutes of hormone presentation. The effect increases with auxin concentration in a manner similar to the hormone effect on elongation. However, the xyloglucan effect of auxin occurs perfectly normally when elongation is completely blocked by mannitol. Metabolic inhibitors and Ca(2+), on the other hand, inhibit auxin promotion of elongation and of xyloglucan metabolism in parallel. The results suggest that the changes in xyloglucan reflect the means by which auxin modifies the cell wall to cause elongation.

When cytoplasmie streaming in oat and maize coleoptile cells is completely inhibited by cytochalasin B (CB), polar transport of auxin (indole-3-acetic acid) continues at a slightly reduced rate. Therefore, cytoplasmic streaming is not required for polar transport. Auxin induces elongation in CB-inhibited coleoptile and pea stem segments, but elongation rate is reduced about 40% by CB. Therefore, stimulation of cytoplasmic streaming cannot be the means by which auxin promotes cell elongation, but streaming may be beneficial to elongation growth although not essential to it. A more severe inhibition of elongation develops after several hours in CB. With coleoptiles this could be due to inhibition of sugar uptake; in pea tissue it may be due to permeability changes and cytoplasmic degeneration. CB does not disorganize or disorient microfilament bundles when it inhibits streaming in maize, but appears instead to cause hypercondensation of microfilament material.

The cytoplasm of maize coleoptile cells was displaced to either the apical or basal ends of the cells by centrifuging (1750xg for 10 min) segments in which protoplasmic streaming had been stopped by pretreatment with cytochalasin B. Centrifugation toward the base of the segment promotes the subsequent basipetal transport of indole-3-acetic acid, whereas apical centrifugation dramatically inhibits this transport. Apical centrifugation neither promotes acropetal transport nor reverses the polarity of auxin transport. Experiments in which the amyloplasts were separated from the bulk of the cytoplasm indicate that the basipetal transport is independent of both the position and pressure exerted by the amyloplasts but is strongly dependent on the amount of cytoplasm at the basal end of the cells. These effects of centrifugation on auxin transport lead to the conclusion that the metabolic component of the transport is a polar secretion of auxin localized in the basal plasma membrane of each cell.

(31)P-Nuclear-magnetic-resonance spectra of maize (Zea mays L.) root tips, that had been induced to extrude large amounts of H(+) in response to fusicoccin (FC) in the presence of potassium salts, indicate that the cytoplasmic pH does not become higher than that of controls. In fact, the cytoplasmic pH may become slightly (approx. 0.1 pH unit) lower in cells extruding H(+). Estimations of the buffer capacity of the cells show that without active intracellular pH regulation, H(+) extrusion caused by FC would cause the intracellular pH to rise by at least 0.6 pH unit h(-1). Our results indicate that intracellular pH is tightly regulated even during extreme rates of acid extrusion, and that a rise in cytoplasmic pH is not the signal linking H(+) extrusion with enhanced organic-acid synthesis or other intracellular responses to H(+) pumping.

The possibility of an auxin effect on the permeability of pea (Pisum sativum L. ev. Alaska) segments to tritium-labeled water has been investigated by three separate laboratories, and the combined results are presented. We were unable to obtain any indication of a rapid effect of indoleacetic acid on the efflux of (3)HHO when pea segments previously "loaded" for 90 minutes with (3)HHO were transferred to unlabeled aqueous medium with indoleacetic acid. We were able to confirm that segments pretreated with (3)HHO plus indoleacetic acid for 60 to 90 minutes can show an enhanced (3)HHO release as compared with minus indoleacetic acid controls. However, this phenomenon appears to be due to an increased uptake of (3)HHO during the prolonged indoleacetic acid pretreatment, and therefore we conclude that auxin does not alter the permeability of pea segments to (3)HHO in either short term or long term tests. We confirm previous reports that the uptake of (3)HHO in pea segments proceeds largely through the cut surfaces, and that the cuticle is a potent barrier to (3)HHO flux.

A mung bean (Vigna radiata) pectin acetyl esterase (CAA67728) was heterologously expressed in tubers of potato (Solanum tuberosum) under the control of the granule-bound starch synthase promoter or the patatin promoter in order to probe the significance of O-acetylation on cell wall and tissue properties. The recombinant tubers showed no apparent macroscopic phenotype. The enzyme was recovered from transgenic tubers using a high ionic strength buffer and the extract was active against a range of pectic substrates. Partial in vivo de-acetylation of cell wall polysaccharides occurred in the transformants, as shown by a 39% decrease in the degree of acetylation (DA) of tuber cell wall material (CWM). Treatment of CWM using a combination of endo-polygalacturonase and pectin methyl esterase extracted more pectin polymers from the transformed tissue compared to wild type. The largest effect of the pectin acetyl esterase (68% decrease in DA) was seen in the residue from this extraction, su...

Biallelic loss-of-function mutations in SPG11 cause a wide spectrum of recessively inherited, neurodegenerative disorders including hereditary spastic paraplegia (HSP), amyotrophic lateral sclerosis, and Charcot-Marie-Tooth disease. By comprehensive screening of three large cohorts of HSP index patients we identified 83 alleles with "small" mutations, and 13 alleles that carry large genomic rearrangements. Including relevant data from previous studies, we estimate that copy number variants (CNVs) account for ∼19% of pathogenic SPG11 alleles. The breakpoints for all novel and some previously reported CNVs were determined by long range PCR and sequencing. This revealed several Alu-associated recombination hotspots. We also found evidence for additional mutational mechanisms, including for a two-step event in which an Alu retrotransposition preceded the actual rearrangement. Apparently independent samples with identical breakpoints were analyzed by microsatellite PCRs. The resulting haplotypes suggested the existence of two rearrangement founder alleles. Our findings widen the spectra of mutations and mutational mechanisms in SPG11, underscore the pivotal role played by Alus, and are of high diagnostic relevance for a wide spectrum of clinical phenotypes including the most frequent form of recessive HSP. This article is protected by copyright. All rights reserved.

The precise genetic cause remains elusive in nearly 50% of patients with presumed neurogenetic disease, representing a significant barrier for clinical care. This is despite significant advances in clinical genetic diagnostics, including the application of whole-exome sequencing and next-generation sequencing-based gene panels. In this study, we identify a deep intronic mutation in the DMD gene in a patient with muscular dystrophy using both conventional and RNAseq-based transcriptome analyses. The implications of our data are that noncoding mutations likely comprise an important source of unresolved genetic disease and that RNAseq is a powerful platform for detecting such mutations.

Phenotypic overlap among the inherited bone marrow failure syndromes (IBMFSs) frequently limits the ability to establish a diagnosis based solely on clinical features. >70 IBMFS genes have been identified, which often renders genetic testing prolonged and costly. Since correct diagnosis, treatment and cancer surveillance often depend on identifying the mutated gene, strategies that enable timely genotyping are essential. To overcome these challenges, we developed a next-generation sequencing assay to analyse a panel of 72 known IBMFS genes. Cases fulfilling the clinical diagnostic criteria of an IBMFS but without identified causal genotypes were included. The assay was validated by detecting 52 variants previously found by Sanger sequencing. A total of 158 patients with unknown mutations were studied. Of 75 patients with known IBMFS categories (eg, Fanconi anaemia), 59% had causal mutations. Among 83 patients with unclassified IBMFSs, we found causal mutations and established the...

Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder resulting from loss of normal ciliary function. Symptoms include neonatal respiratory distress, chronic sinusitis, bronchiectasis, situs inversus and infertility. Clinical features may be subtle and highly variable making the diagnosis of PCD challenging. The diagnosis can be confirmed with ciliary ultrastructure analysis and/or molecular genetic testing of 32 PCD associated genes. However, due to this genetic heterogeneity, comprehensive molecular genetic testing is not considered standard of care, and the most efficient molecular approach has yet to be elucidated. Here, we propose a cost-effective and time-efficient molecular genetic algorithm in solving PCD cases. We conducted targeted copy number variation (CNV) analysis and/or whole exome sequencing (WES) on 20 families (22 patients) from a subset of 45 families (52 patients) with a clinical diagnosis of PCD who did not have a molecular genetic diagnosis after ...

Reading maxillofacial computed tomography (CT) scans is a basic skill for any surgeon who operates on the face. A standard systematic approach for how to read a maxillofacial CT scan from a surgeon's perspective is lacking in literature, particularly for those in the early stages of training. We present a method of initial rapid analysis which our residents in training have responded to and report to be conceptually simple to apply. The senior author reviewed over 250 consults for face trauma and performed a detailed composite of the most common elements of each consult as well as the clinically relevant decision points. These elements were then bundled into a conceptual sketch of the skull-face-mandible with an accompanying standardized clinical data list. The new residents were then guided through a systematic approach to reading the scans while sketching the injuries identified. The authors then performed a survey to establish if the new method was helpful to early learners p...

Craniosynostosis is a clinically and genetically heterogeneous condition. Knowledge of the specific genetic diagnosis in patients presenting with this condition is important for surgical and medical management. The most common single gene causes of syndromic craniosynostosis are mutations in FGFR1, FGFR2, FGFR3, TWIST1, and EFNB1. Recently, a new single gene cause of craniosynostosis was published, together with phenotype data that highlight the clinical importance of making this specific molecular diagnosis. Phenotypic features of "ERF-related craniosynostosis" include sagittal or multiple-suture synostosis, Chiari malformation, and language delay. In order to determine the contribution of ERF mutations to genetically undiagnosed patients with craniosynostosis, we sequenced the coding regions of ERF in 40 patients with multi-suture or sagittal suture synostosis. We identified heterozygous ERF mutations in two individuals (5%). One mutation positive individual had pansynos...

We report a consanguineous couple that has experienced three consecutive pregnancy losses following the foetal ultrasound finding of short limbs. Post-termination examination revealed no skeletal dysplasia, but some subtle proximal limb shortening in two foetuses, and a spectrum of mildly dysmorphic features. Karyotype was normal in all three foetuses (46, XX) and comparative genomic hybridization microarray analysis detected no pathogenic copy number variants. Whole-exome sequencing and genome-wide homozygosity mapping revealed a previously reported frameshift mutation in the OBSL1 gene (c.1273insA p.T425nfsX40), consistent with a diagnosis of 3-M Syndrome 2 (OMIM #612921), which had not been anticipated from the clinical findings. Our study provides novel insight into the early clinical manifestations of this form of 3-M syndrome, and demonstrates the utility of whole exome sequencing as a tool for prenatal diagnosis in particular when there is a family history suggestive of a rec...

Irradiation of etiolated pea (Pisum sativum L.) seedlings with white light affects two proteins, both of monomer molecular mass near 120 kDa. Both proteins have been detected in association with plasma membrane fractions. The first is identifiable in that it becomes heavily phosphorylated when the membranes are incubated with exogenous ATP. The second of these proteins is phytochrome, as determined by electrophoretic transfer (Western) blot analysis. Measurable phosphorylation and phytochrome (the latter detected by antigenicity) decline when the tissue is irradiated with white light prior to membrane isolation and in vitro phosphorylation. The phosphorylated protein is probably not phytochrome for three reasons. (i) It shows a slightly different distribution in sucrose gradients. (ii) Red light causes a gradual decline in the phytochrome that is associated with membrane fractions but has a negligible effect on the phosphorylatable protein; blue light, on the other hand, causes sign...