Single-photon-emitting optical centers in diamond fabricated upon Sn implantation

The fabrication of luminescent defects in single-crystal diamond upon Sn implantation and annealing is reported. The relevant spectral features of the optical centers (emission peaks at 593.5 nm, 620.3 nm, 630.7 nm and 646.7 nm) are attributed to Sn-related defects through the correlation of their photoluminescence (PL) intensity with the implantation fluence. Single Sn-related defects were identified and characterized through the acquisition of their second-order auto-correlation emission functions, by means of Hanbury-Brown-Twiss interferometry. The investigation of their single-photon emission regime as a function of excitation laser power revealed that Sn-related defects are based on three-level systems with a 6 ns radiative decay lifetime. In a fraction of the studied centers, the observation of a blinking PL emission is indicative of the existence of a dark state. Furthermore, absorption dependence from the polarization of the excitation radiation with about 45 percent contrast was measured. This work shed light on the existence of a new optical center associated with a group-IV impurity in diamond, with similar photo-physical properties to the already well-known Si-V and Ge-V emitters, thus providing results of interest from both the fundamental and applicative points of view.Comment: 10 pages, 4 figure

On the uneven distribution of the Copelata of the Fernando de Noronha area

Durante uma viagem à ilha Fernando de Noronha em Janeiro de 1954, a Dra. M. Vannucci e o Dr. E. F. Nonato coletaram amostras de plancton em várias estações ao norte e ao sul da ilha. A tabela 1 mostra o número das estações, sua posição geográfica, outros dados tais como salinidade, hora de coleta, profundidade local e da coleta, tipos de redes usados, etc, assim como o número e a porcentagem de cada espécie de Gopelata encontrada em cada amostra. Comparando a população de Copelatá capturada ao norte e ao sul da ilha verificou-se que havia uma diferença bem marcada nas porcentagens das diferentes espécies por amostra, e que as águas do sul e do norte da ilha mostraram um quadro diferente de freqüências (Fig. 1) assim como foi diferente de cada lado da ilha a porcentagem das Famílias Oikopleuridae e Fritillaridae. Estas predominaram ao sul enquanto aquelas predominaram ao norte da ilha. Para estes fatos existem duas explicações possíveis: - ou a ilha funcionou como obstáculo às águas da Corrente Sul Equatorial provocando no seu lado noroeste uma subida de água das camadas inferiores e modificando assim as condições hidrológicas características da região, ou as diferenças observadas de amostra para amostra (Fig. 2) foram devidas não a diferenças hidrológicas, mas, sim a diferentes "nuvens" de Gopelata que ocorreram ao norte e ao sul da ilha, durante a época em que foi feita a coleta. H. longicauda mostrou ligeiro acréscimo na porcentagem relativa às outras espécies, quando coletada com rede pelágica (A) na superfície, quando comparada com as porcentagens em que ocorre em amostras coletadas por outras redes em profundidades maiores. A ocorrência de espécies neríticas (O. dioica e F. abjörnseni) nas estações mais próximas da costa (2 e 7) ambas situadas sobre a plataforma insular, não vem confirmar a idéia de Lohmann (1896, p. 109) de que haja influência da costa brasileira sobre a ilha, pois a intensidade da corrente Sul Equatorial nessa região em direção NW torná-la-ia muito improvável, e sim confirma a teoria de Ekman (1953, p. 313) de que as pequenas ilhas oceânicas agem como costas. As estações ao norte da ilha mostraram como população de Gopelata característica nestas amostras, em porcentagem decrescente as espécies O. fusiformis, F. borealis; e S. longicauda ou vice-versa, F. pellucida, e F. formica e S. magnum ou vice-versa; as do sul da ilha, freqüências elevadas de F. borealis, H. longicauda e porcentagens menores de O. fusiformis, F. pellucida e F. formica

On the uneven distribution of the Copelata of the alcatrazes area

Neste trabalho são estudados os Copelata coletados durante a viagem do "Igaraty" à Ilha de Alcatrazes. A lista das estações, sua localização, as datas e outros dados sobre as águas da área pesquisada, assim como o número e a porcentagem de ocorrência de cada espécie em cada amostra estão na Tabela 1. Todas as coletas foram feitas com uma rede "standard" (Sverdrup et al - 1954, p. 379, fig. 91-d). Comparando os dados hidrográficos, fornecidos por informação pessoal do Dr. I. Emílsson, com os nossos, podemos concluir que, nestas amostras, as águas vindas do norte (vide estações 6, 7 e 9) são caracterizadas pela presença de O. rufescens em grande abundância; as águas costeiras, pela presença de F. pellucida (vide estações 1, 10 e 11) e as águas misturadas (vide estações 5 e 8, Tabela 1 e Figura 1) são caracterizadas pela ocorrência de II. longicauda, O. fusiformis e F. pellucida em freqüências elevadas. Houve ocorrência ainda de "nuvens" de F. haplostoma na estação 10, fato comum em águas costeiras e superficiais do Japão (Tokioka, 1951 e 1955). A influência da termoclina observada nas estações 5 e 9 não foi considerada significativa pois foi pequena a quantidade de água atravessada pela rede abaixo dela, em comparação com a grande quantidade ocorrida acima da mesma. O aparecimento de Tectillaria fertilis aumenta o limite sul de distribuição desta espécie no Atlântico, pois era conhecida apenas nas correntes quentes do hemisfério norte deste oceano (Lohmann, 1896, p. 30)

Export of functional Streptomyces coelicolor alditol oxidase to the periplasm or cell surface of Escherichia coli and its application in whole-cell biocatalysis

Streptomyces coelicolor A3(2) alditol oxidase (AldO) is a soluble monomeric flavoprotein in which the flavin cofactor is covalently linked to the polypeptide chain. AldO displays high reactivity towards different polyols such as xylitol and sorbitol. These characteristics make AldO industrially relevant, but full biotechnological exploitation of this enzyme is at present restricted by laborious and costly purification steps. To eliminate the need for enzyme purification, this study describes a whole-cell AldO biocatalyst system. To this end, we have directed AldO to the periplasm or cell surface of Escherichia coli. For periplasmic export, AldO was fused to endogenous E. coli signal sequences known to direct their passenger proteins into the SecB, signal recognition particle (SRP), or Twin-arginine translocation (Tat) pathway. In addition, AldO was fused to an ice nucleation protein (INP)-based anchoring motif for surface display. The results show that Tat-exported AldO and INP-surface-displayed AldO are active. The Tat-based system was successfully employed in converting xylitol by whole cells, whereas the use of the INP-based system was most likely restricted by lipopolysaccharide LPS in wild-type cells. It is anticipated that these whole-cell systems will be a valuable tool for further biological and industrial exploitation of AldO and other cofactor-containing enzymes.

Targeting the CoREST complex with dual histone deacetylase and demethylase inhibitors

Here we report corin, a synthetic hybrid agent derived from the class I HDAC inhibitor (entinostat) and an LSD1 inhibitor (tranylcypromine analog). Enzymologic analysis reveals that corin potently targets the CoREST complex and shows more sustained inhibition of CoREST complex HDAC activity compared with entinostat. Cell-based experiments demonstrate that corin exhibits a superior anti-proliferative profile against several melanoma lines and cutaneous squamous cell carcinoma lines compared to its parent monofunctional inhibitors but is less toxic to melanocytes and keratinocytes. CoREST knockdown, gene expression, and ChIP studies suggest that corin's favorable pharmacologic effects may rely on an intact CoREST complex. Corin was also effective in slowing tumor growth in a melanoma mouse xenograft model. These studies highlight the promise of a new class of two-pronged hybrid agents that may show preferential targeting of particular epigenetic regulatory complexes and offer unique therapeutic opportunities

CDH1 mutation distribution and type suggests genetic differences between the etiology of orofacial clefting and gastric cancer

Pathogenic variants in CDH1, encoding epithelial cadherin (E-cadherin), have been implicated in hereditary diffuse gastric cancer (HDGC), lobular breast cancer, and both syndromic and non-syndromic cleft lip/palate (CL/P). Despite the large number of CDH1 mutations described, the nature of the phenotypic consequence of such mutations is currently not able to be predicted, creating significant challenges for genetic counselling. This study collates the phenotype and molecular data for available CDH1 variants that have been classified, using the American College of Medical Genetics and Genomics criteria, as at least ‘likely pathogenic’, and correlates their molecular and structural characteristics to phenotype. We demonstrate that CDH1 variant type and location differ between HDGC and CL/P, and that there is clustering of CL/P variants within linker regions between the extracellular domains of the cadherin protein. While these differences do not provide for exact prediction of the phenotype for a given mutation, they may contribute to more accurate assessments of risk for HDGC or CL/P for individuals with specific CDH1 variants

CDH1 mutation distribution and type suggests genetic differences between the etiology of orofacial clefting and gastric cancer

Pathogenic variants in CDH1, encoding epithelial cadherin (E-cadherin), have been implicated in hereditary diffuse gastric cancer (HDGC), lobular breast cancer, and both syndromic and non-syndromic cleft lip/palate (CL/P). Despite the large number of CDH1 mutations described, the nature of the phenotypic consequence of such mutations is currently not able to be predicted, creating significant challenges for genetic counselling. This study collates the phenotype and molecular data for available CDH1 variants that have been classified, using the American College of Medical Genetics and Genomics criteria, as at least ‘likely pathogenic’, and correlates their molecular and structural characteristics to phenotype. We demonstrate that CDH1 variant type and location differ between HDGC and CL/P, and that there is clustering of CL/P variants within linker regions between the extracellular domains of the cadherin protein. While these differences do not provide for exact prediction of the phenotype for a given mutation, they may contribute to more accurate assessments of risk for HDGC or CL/P for individuals with specific CDH1 variants

Crystal structure and mechanism of human lysine-specific demethylase-1

The reversible methylation of specific lysine residues in histone tails is crucial in epigenetic gene regulation. LSD1, the first known lysine-specific demethylase, selectively removes monomethyl and dimethyl, but not trimethyl modifications of Lys4 or Lys9 of histone-3. Here, we present the crystal structure of LSD1 at 2.9-Å resolution. LSD1 forms a highly asymmetric, closely packed domain structure from which a long helical 'tower' domain protrudes. The active site cavity is spacious enough to accommodate several residues of the histone tail substrate, but does not appear capable of recognizing the different methylation states of the substrate lysine. This supports the hypothesis that trimethylated lysine is chemically rather than sterically discriminated. We present a biochemical analysis of LSD1 mutants that identifies crucial residues in the active site cavity and shows the importance of the SWIRM and tower domains for catalysis