Bacteriopheophytin triplet state in Rhodobacter sphaeroides reaction centers

It is well established that photoexcitation of Rhodobacter sphaeroides reaction centers (RC) with reduced quinone acceptors results in the formation of a triplet state localized on the primary electron donor P with a significant yield. The energy of this long-lived and therefore potentially damaging excited state is then efficiently quenched by energy transfer to the RC spheroidenone carotenoid, with its subsequent decay to the ground state by intersystem crossing. In this contribution, we present a detailed transient absorption study of triplet states in a set of mutated RCs characterized by different efficiencies of triplet formation that correlate with lifetimes of the initial charge-separated state P+HA- . On a microsecond time scale, two types of triplet state were detected: in addition to the well-known spheroidenone triplet state with a lifetime of ~4 μs, in some RCs we discovered a bacteriopheophytin triplet state with a lifetime of ~40 μs. As expected, the yield of the carotenoid triplet increased approximately linearly with the lifetime of P+HA-, reaching the value of 42 % for one of the mutants. However, surprisingly, the yield of the bacteriopheophytin triplet was the highest in RCs with the shortest P+HA- lifetime and the smallest yield of carotenoid triplet. For these the estimated yield of bacteriopheophytin triplet was comparable with the yield of the carotenoid triplet, reaching a value of ~7 %. Possible mechanisms of formation of the bacteriopheophytin triplet state are discussed.</p

Mudanças fonológicas obtidas no tratamento pelo Modelo de Oposições Múltiplas Phonological Changes obtained in the treatment based on the Multiple Opposition Approach

OBJETIVO: analisar as mudanças fonológicas decorrentes da aplicação do Modelo de Oposições Múltiplas no que se refere ao Percentual de Consoantes Corretas-Revisado (PCC-R), no número de fonemas adquiridos no inventário fonológico e nos tipos de generalização. MÉTODO: o grupo pesquisado foi constituído por cinco sujeitos com desvio fonológico. Foram realizadas avaliações fonoaudiológicas e complementares. Os dados da fala foram coletados e analisados por meio da avaliação fonológica pré e pós-tratamento. Os sujeitos foram submetidos à terapia pelo Modelo de Oposições Múltiplas. RESULTADOS: constatou-se que houve diferença estatisticamente significante no que tange ao PCC-R, ao número de fonemas adquiridos, à generalização a itens lexicais não utilizados no tratamento, para outra posição da palavra e para outras classes de sons. Não houve diferença estatística para a generalização dentro de uma classe de sons, porém, observou-se um aumento do percentual no pós-tratamento. CONCLUSÃO: o Modelo de Oposições Múltiplas foi efetivo para o tratamento desses sujeitos falantes do Português Brasileiro, pois proporcionou mudanças no PCC-R, no número de fonemas adquiridos e algumas generalizações (a itens lexicais não utilizados no tratamento, para outra posição na palavra, dentro de uma classe de sons, para outras classes de sons).<br>PURPOSE: to analize the phonological changes resulting from the application of the Multiple Opposition Approach concerning the Percentage of Consonants Correct - Revised (PCC-R), on the number of phonemes that were acquired in the phonological inventory and on the types of generalization. METHOD: the researched group included five subjects with phonological disorders. It was carried out phonological and complementary assessments. The speech data were transcribed and analyzed through the phonological assessment pre and post-treatment. The subjects underwent the treatment based on the Multiple Opposition Approach. RESULTS: an increase in PCC-R, number of acquired phonemes and presence of different types of generalization in the final assessment, which was statistical difference, except the results of the generalization within sound class were not statistical difference in the pos-treatment. CONCLUSION: the Multiple Oppositions Approach was effective for the treatment of Brazilian Portuguese speakers because the model provided changes in the PCC-R, number of acquired phonemes and some generalizations (to lexical items non used during treatment, to another position of the word, inside a sound class and to other sound class)

Stickler syndrome caused by COL2A1 mutations: genotype–phenotype correlation in a series of 100 patients

Stickler syndrome is an autosomal dominant connective tissue disorder caused by mutations in different collagen genes. The aim of our study was to define more precisely the phenotype and genotype of Stickler syndrome type 1 by investigating a large series of patients with a heterozygous mutation in COL2A1. In 188 probands with the clinical diagnosis of Stickler syndrome, the COL2A1 gene was analyzed by either a mutation scanning technique or bidirectional fluorescent DNA sequencing. The effect of splice site alterations was investigated by analyzing mRNA. Multiplex ligation-dependent amplification analysis was used for the detection of intragenic deletions. We identified 77 different COL2A1 mutations in 100 affected individuals. Analysis of the splice site mutations showed unusual RNA isoforms, most of which contained a premature stop codon. Vitreous anomalies and retinal detachments were found more frequently in patients with a COL2A1 mutation compared with the mutation-negative group (P<0.01). Overall, 20 of 23 sporadic patients with a COL2A1 mutation had either a cleft palate or retinal detachment with vitreous anomalies. The presence of vitreous anomalies, retinal tears or detachments, cleft palate and a positive family history were shown to be good indicators for a COL2A1 defect. In conclusion, we confirm that Stickler syndrome type 1 is predominantly caused by loss-of-function mutations in the COL2A1 gene as >90% of the mutations were predicted to result in nonsense-mediated decay. On the basis of binary regression analysis, we developed a scoring system that may be useful when evaluating patients with Stickler syndrome