A.A. Guimarães

Infantile neuroaxonal dystrophy: What's most important for the diagnosis?

BACKGROUND AND AIMS Infantile neuroaxonal dystrophy is a rare neurodegenerative disorder, with onset in the first 2 years of life. Mutations in the PLA2G6 gene were identified in patients with infantile neuroaxonal dystrophy. Our purpose was to review clinical, neurophysiologic, neuroradiologic and neuropathological features of our patients in order to identify the earliest signs of disease. We also correlate these data with the genotype in the mutation positive patients. METHODS We reviewed the clinical reports, neurophysiologic and neuropathological studies and brain imaging of our patients. In five patients molecular analysis of the PLA2G6 gene was performed. RESULTS We report 10 patients with infantile neuroaxonal dystrophy. Earliest symptoms presented between 6 and 18 months of age. The first manifestations were arrest in the acquisition of milestones or regression. The first neurological signs were generalized hypotonia and pyramidal signs. Fast rhythms on EEG were observed in all patients. Brain imaging studies showed cerebellar atrophy in all patients, with signal hyperintensity in the cerebellar cortex on T2-weighted images in five. All cases had characteristic axonal spheroids on skin biopsy. Mutations in the PLA2G6 gene were identified in the five patients studied. Three of them had the same homozygous mutations 2370T> G, Y790X. CONCLUSIONS Though mutations were detected in the patients studied, a clear genotype-phenotype correlation could not be ascertained. In the appropriate clinical context, characteristic brain imaging and fast rhythms on EEG can support the decision to perform molecular analysis and avoid skin biopsy to confirm diagnosis.

Persistência de sulfentrazone em Argissolo Vermelho-Amarelo cultivado com cana-de-açúcar

The objective of this study was to evaluate sulfentrazone persistence in Typic Hapludalf and its effect on the microbiota of soil cultivated with sugar-cane. The treatments consisted of herbicide application only in 2003, in 2003 with reapplication in 2004 and control without herbicide. Herbicide distribution in the soil profile (0-10 and 10-20 cm of depth) and persistence in 467/24, 517/74, 550/107 and 640/197 days after application (DAA), were studied in the split-plots and split-split-plots, respectively. Indirect quantification of the residues was accomplished by bioassay and C-CO2 evolution together with microbial biomass (CBM) determination were evaluated in soil collected 640/197 DAA. Reduction of dry mass of the aerial part of Sorghum vulgare was verified during the entire evaluated period when the herbicide was applied in 2003 and reapplied in 2004. Most of the residues were detected at the depth of 010 cm, with their leaching potential in the soil being of little significance under environmental conditions. Sulfentrazone influenced the evolution of C-CO2 and CBM of the soil, with the largest accumulated value of C-CO2 being observed for the treatment without herbicide application. Sulfentrazone presented high persistence in PVA, with a negative effect on soil microorganisms, but without posing leaching risks in its profile.

Atividade microbiana em solo cultivado com cana-de-açúcar após aplicação de herbicidas

The objective of this work was to evaluate the impact of the herbicides ametryn and trifloxysulfuron-sodium, singly or combined, and 2,4-D, on respiratory rate, microbial biomass, and metabolic quotient on sugar cane-cultivated soil. A completely randomized design was adopted in a split-plot scheme with four replications. The effect of the herbicides was evaluated in the plots and the effect of time after herbicide application in the split-plots. The herbicide doses, in kg ha-1, were: 1.30 (2,4-D), 1.00 (ametryn), 0.0225 (trifloxysulfuron-sodium), and 1.463 + 0.0375 for the mixture ametryn + trifloxysulfuron-sodium,, respectively. At 60 days after shoot emergence, the herbicides were sprayed on the sugarcane plants. At 15, 30, 45, and 60 days after herbicide application, rhizospheric and non-rhizospheric soil samples were collected and analyzed for respiratory rate (RR) microbial biomass (MB), metabolic quotient (qCO2), and total C-CO2 evolved from the soil (TCE). Ametryn applied singly or combined with trifloxysulfuron-sodium led to higher RR, while 2,4-D alone had little influence on this variable. Higher TCEs were verified in the soils of the treatments with trifloxysulfuron-sodium, ametryn, and with the compounds combined. Soil MB was reduced in the presence of ametryn applied singly or combined. These treatments resulted in higher values of qCO2 at 45 and 60 days of application, respectively.

Potencial competitivo de biótipos de azevém (Lolium multiflorum)

The objective of this work was to evaluate the competitiveness of ryegrass biotypes resistant and susceptible to glyphosate, as well as their interference in wheat growth at different densities. At harvesting, 50 days after emergence, tillering, height, and leaf area of ryegrass plants were evaluated and shoot and roots of ryegrass and wheat were collected and their root, stalk and leaf dry mass was determined. Based on the data, the following variables were evaluated for ryegrass and wheat: crop growth rate (TCC = MSA/Ndays), with MSA being shoot dry mass and Ndays the number of days between emergence and plant harvesting; specific leaf area (SLA = Af /MSf),with Af being the leaf area and MSf leaf dry mass; and leaf area index (IAF = Af/St), St being soil area, indicating leaf area per soil area. Plant height, dry mass and leaf area of the susceptible ryegrass showed smaller reductions and better phenotypic plasticity, in function of the increasing density per soil area, compared to the resistant one. The susceptible biotype showed to be more competitive and its interference in wheat development was more visible at lower densities. It was concluded that the susceptible ryegrass biotype is more competitive than the resistant one.

Ação de herbicidas sobre microrganismos solubilizadores de fosfato inorgânico em solo rizosférico de cana-de-açúcar

The objective of this work was to evaluate the impact of the herbicides ametryn and trifloxysulfuron-sodium, singly or combined, and 2,4-D, on the activity of inorganic phosphate-solubilizing microorganisms and the populational density of fungi and bacteria in sugarcane rhizosphere. Sugarcane plants with three to four fully expanded leaves and fungi were sprayed with ametryn, trifloxysulfuron-sodium, and ametryn + trifloxysulfuron-sodium at the doses of 1.30, 1.00, 0.0225 and 1.463 + 0.0375 kg ha-1, respectively. A completely randomized design was adopted in a split plot scheme with four replications. The effect of the herbicides was evaluated in the whole plots and the effect of time after application in the split-plots. At 15, 30, 45, and 60 days after spraying (DAS), rhizospheric and non-rhizospheric soil samples were collected and immediately analyzed for the populational densities of bacteria and fungi and the potential and relative inorganic phosphate solubilization activity in the soil. 2,4-D reduced the bacterial density in the soil for all the evaluation times, densities of bacterial populations in the rhizosphere for all periods of time showing a higher sensitivity of this group to this compound. At 15 DAS, all herbicides tested reduced the number of fungi in the soil. Trifloxysulfuron-sodium and 2,4-D led to higher inorganic phosphate solubilization at 15, 30, and 45 DAS, and 15 and 30 DAS, respectively, without affecting microbial biomass. The highest relative inorganic phosphate solubilization was observed in the soils treated with ametryn + trifloxysulfuron-sodium. This work showed that herbicide application on sugarcane shoots affects the number of microorganisms and phosphate solubilization activity in the rhizosphere.

Novel synonymous substitution in POMGNT1 promotes exon skipping in a patient with congenital muscular dystrophy

AbstractWalker-Warburg syndrome, muscle-eye-brain disease, Fukuyama congenital muscular dystrophy, congenital muscular dystrophy type 1C, and congenital muscular dystrophy type 1D are overlapping clinical entities belonging to a subgroup of the congenital muscular dystrophies (CMD), collectively designated dystroglycanopathies, in which the common underlying defect is hypoglycosylation of alfa-dystroglycan. Currently, six different genes are known to be implicated in these diseases: POMT1, POMT2, POMGNT1, FCMD, FKRP, and LARGE. We report the molecular characterization of a patient presenting clinical features of CMD and reduced immunostaining for alfa-dystroglycan in muscle. Three candidate genes (FCMD, POMT1 and POMGNT1) were analyzed, and a total of 18 sequence variants were detected: 15 polymorphisms in POMT1 [including three unreported single nucleotide polymorphisms (SNPs)], two polymorphisms in FCMD, and the exonic silent mutation c.636C > T in POMGNT1. Expression analysis revealed that this apparently silent mutation compromises correct premessenger RNA (mRNA) splicing, promoting skipping of the entire exon 7, with a consequent frameshift. In silico analysis of this mutation did not predict alterations in the canonical splice sequences, but rather the creation of a new exonic splice silencer. The recognition of such disease-causing elements may contribute to the further understanding of RNA processing and assist mutation screening in routine diagnosis, where such changes may be underestimated. To aid clinical diagnosis, we generated publicly available LOVD-powered Locus Specific Databases for these three genes and recorded all known sequence variants (http://www.dmd.nl).

Chemical composition of the epicuticular wax of Italian ryegrass biotypes resistant and susceptible to glyphosate

The objective of this work was to determine the chemical composition of epicuticular wax of Italian ryegrass (Lolium multiflorum) biotypes resistant and susceptible to glyphosate, searching for relationships between their characteristics and the resistance of the biotypes to the product. The epicuticular wax was extracted and quantified, and its constituents analyzed by gas chromatography, coupled to mass spectrometer (CG-EM). To determine the chemical composition, leaf blade samples were obtained 30 days after plant emergence, the first leaf being collected with totally visible ligule. The amount of epicuticular wax did not differ between the biotypes. Alcohols are the most abundant among the compounds constituting the epiticular wax, represented by only one compound, hexacosan-1-ol (46.80% in the resistant biotype and 52.20% in the susceptible). When comparing the polarity of the epicuticular wax of the Italian ryegrass biotypes, it was verified that both in the resistant and susceptible biotypes, the epicuticular wax presented more than 50% of polar compounds (alcohols and aldehydes) in its constitution, with that value being equal to 69.80% in the resistant biotype and 64.94% in the susceptible. Thus, it can be stated that small differences exist in the epicuticular wax of Italian ryegrass biotypes resistant and susceptible to glyphosate. The resistant biotype presented a slightly higher polarity degree than the susceptible biotype but such difference cannot be considered sufficiently relevant to determine a greater or smaller tolerance of either biotype to glyphosate.

Private dysferlin exon skipping mutation (c.5492G>A) with a founder effect reveals further alternative splicing involving exons 49-51.

The allelic muscle disorders known as limb-girdle muscular dystrophy type 2B (LGMD2B), Miyoshi myopathy and distal anterior compartment myopathy result from defects in dysferlin—a sarcolemma-associated protein involved in membrane repair. Mutation screening in the dysferlin gene (DYSF) enabled the identification of seven Portuguese patients presenting the variant c.5492G>A, which was observed to promote skipping of exon 49 (p.Gly1802ValfsX17). Several residually expressed products of alternative splicing also involving exons 50 and 51 were detected in the leukocytes and muscle of both patients and normal controls. Quantitative transcript analysis confirmed these results and revealed that Δ49/Δ50 transcripts were predominant in blood. Although the patients were apparently unrelated, the c.5492G>A mutation was found in linkage disequilibrium with a particularly rare haplotype in the population, corroborating the hypothesis of a common origin. Despite the presence of the same mutation on the same haplotype background, onset of the disease was heterogeneous, with either proximal or distal muscle involvement.