264 research outputs found
Estudo das características fisiológicas de genótipos de milho contrastantes para tolerância a seca.
Fundus Autofluorescence and Spectral Domain OCT in Central Serous Chorioretinopathy
Background. To describe the standard autofluorescence (FAF), the near infrared autofluorescence (NIA) and optical coherence tomography (OCT) patterns in central serous chorioretinopathy, correlating them with fluorescein angiography. Methods. Cross-sectional observational study, in which patients with at least seven months of CSC underwent ophthalmologic examination, fundus photography, FAF, NIA, fluorescein angiography (FA), and spectral-domain OCT. Results. Seventeen eyes of thirteen patients were included. the presentation features were a mottled hyperFAF in the detached area and areas with pigment mottling. NIA images showed areas of hyperNIA similar to FAF and localized areas of hypoNIA, which correlated with the points of leakage in the FA. OCT showed pigment epithelium detachment at the location of these hypoNIA spots. Discussion. FAF showed increased presence of fluorophores in the area of retinal detachment, which is believed to appear secondary to lipofuscin accumulation in the RPE or the presence of debris in the subretinal fluid. NIA has been related to the choroidal melanin content and there were areas of both increased and decreased NIA, which could be explained by damage ahead the retina, basically RPE and choroid. These findings, along with the PEDs found in the areas of hypoNIA, support the notion of a primary choroidal disease in CSC.Universidade Federal de São Paulo, Dept Ophthalmol, Paulista Sch Med, BR-04025011 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Ophthalmol, Paulista Sch Med, BR-04025011 São Paulo, BrazilWeb of Scienc
The Genetic Architecture of Noise-Induced Hearing Loss: Evidence for a Gene-by-Environment Interaction.
The discovery of environmentally specific genetic effects is crucial to the understanding of complex traits, such as susceptibility to noise-induced hearing loss (NIHL). We describe the first genome-wide association study (GWAS) for NIHL in a large and well-characterized population of inbred mouse strains, known as the Hybrid Mouse Diversity Panel (HMDP). We recorded auditory brainstem response (ABR) thresholds both pre and post 2-hr exposure to 10-kHz octave band noise at 108 dB sound pressure level in 5-6-wk-old female mice from the HMDP (4-5 mice/strain). From the observation that NIHL susceptibility varied among the strains, we performed a GWAS with correction for population structure and mapped a locus on chromosome 6 that was statistically significantly associated with two adjacent frequencies. We then used a "genetical genomics" approach that included the analysis of cochlear eQTLs to identify candidate genes within the GWAS QTL. In order to validate the gene-by-environment interaction, we compared the effects of the postnoise exposure locus with that from the same unexposed strains. The most significant SNP at chromosome 6 (rs37517079) was associated with noise susceptibility, but was not significant at the same frequencies in our unexposed study. These findings demonstrate that the genetic architecture of NIHL is distinct from that of unexposed hearing levels and provide strong evidence for gene-by-environment interactions in NIHL
Performance fotossintética em dois genótipos de milho contrastantes para a tolerância ao déficit hídrico.
Caracterização do sistema radicular e dos componentes da produtividade em quatro genótipos de milho cultivados sob déficit hídrico.
Nesse trabalho foram combinadas avaliações de parâmetros agronômicos com morfometria de raízes usando o programa WinRhizo, a fim de detectar características no sistema radicular que permitam a manutenção da produtividade em quatro materiais genéticos de milho (BRS1010, 2B710, DKB390 e BRS1055), cultivados em dois níveis de água no solo (CC- capacidade de campo, e DH- déficit hídrico). Plantas oriundas dos genótipos DKB390 e BRS1055 sob DH mantiveram valores de produção de grão similares aos de seus respectivos controles, sob CC. Por sua vez, plantas oriundas dos genótipos 2B710 e BRS1010 apresentaram perdas substanciais na produção de grãos com a imposição do DH. Cabe ressaltar que plantas oriundas do genótipo BRS 1055 apresentaram estratégia abaixo do solo de evitação à seca, por aumentarem a área superficial de raízes finas e muito finas, sendo esse um ponto de divergência em relação ao também tolerante genótipo DKB 390.bitstream/item/122152/1/bol-111.pd
Analysis of maize photosyntheis parameters and whole plant oxidative damage under long-term drought.
We test if maize maintain yield under long-term drought throught improvement of photosyntheis (A) coupled with up-regulation of the antioxidant system induced by increase in levels of abscisic acid (ABA). Four maize genotypes with constrasting drought tolerance: BRS1010 and 2B710 (sensitive) and DKB 390 and BRS1055 (tolerant) in two soil water levels, field capacity (FC) and water deficit (WD) were used. WD was applied at the pre-flowering stage for 12 days, and oxidative damage was measured as malondialdehyde (MDA) accumulation in whole plant. Plants from tolerant genotypes DKB390 and BRS1055 showed higher A and had no signal of oxidative damage compared to sensitive genotypes 2B710 and BRS1010 under WD, resulting in a higher yield attributes. For our surprising, it was dissociated from up-regulation of the antioxidant system ABA-mediated. In turn, plants from two sensitive genotypes under WD showed compared to FC consistent reduction of A due to mesophyll conductance (gm) limitation. Only WD plants from sensitive genotype BRS1010 presented leaf ABA levels increased related to its counterparts under FC; however, due to the inactivation of catalase activity the oxidative damage control was not effective, resulting a hardly MDA acumulation in both leaves and roots. The maize tolerance under long-term drought is linked to scape of gm decline
Corn root morphoanatomy at different development stages and yield under water stress.
The objective of this work was to characterize the morphoanatomy of roots and the yield traits of two corn hybrids contrasting for drought tolerance (DKB 390, tolerant; and BRS 1030, sensitive), at different stages of development. Water deficit was imposed for ten days, in a greenhouse, at three growth stages: V5, VT, and R3. These treatments were combined to generate cumulative stress during the plant cycle, as: V5VT, V5R3, VTR3, and V5VTR3. The following were analyzed: root anatomy; proportion of aerenchyma in the cortex; metaxylem number and diameter; phloem thickness; as well as morphological characteristics, such as root length, volume, and surface area, specific root length, length of fine roots, grain yield, and ear length and diameter. Development stage affected the responses to stress: DKB 390 showed the best performance for root morphoanatomy and yield traits, under drought stress, at the reproductive stages, mainly R3, and in the treatments with cumulative stress, especially V5VTR3; whereas BRS 1030 presented higher means for the studied parameters, mainly at the V5 and VT stages, but did not show a higher grain yield under water stress. The greater tolerance of the DKB 390 hybrid to water deficit is probably linked with a memory of pre?exposure to water stress at different growth stages
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