Effects of gama irradiation on nucellar callus production of lhe 'Valência' sweet orange (Citrus sinsensis) Osb. in vitro.

Os métodos convencionais pouco têm contribuído para o melhoramento das espécies cítricas. A utilização das técnicas de cultura in vitro associadas à indução de mutações deverão trazer inestimável contribuição. Nucelos extraídos de frutos em desenvolvimento, doze semanas após a polinização, foram cultivados in vitro em meio "MS" adicionado (em mg/ 1) de: tiamina HCQ - 0,2; piridoxina HCQ - 1,0; ácido nicotínico - 1,0; mesoinositol - 100; extrato de malte - 500; sacarose - 50.000; ágar - 8.000, com pH ajustado para 5,7. Procedeu-se à irradiação, apenas do meio ou do nucelo, ou de ambos, nas doses de 0,0, 0,5, 1,0, 2,0, 4,0, 8.0 e 12,0 kR. A irradiação apenas do nucelo mostrou um efeito similar ao obtido pela irradiação tanto do nucelo como do meio. Doses baixas de radiação (até 2 kR) reduzem o número de embrióides diferenciados. A irradiação do meio de cultura aumenta a proliferação de calos, principalmente em doses mais elevadas.The conventional methods of plant breeding have not given a significative contribution for the citrus breeding. A precious iniprovement by the techniques of tissues culture in vitro, associated with induced mutations, is expected. Nucelli extracted from developping fruits with twelve weeks after pollination were cultured in vitro, on medium supplemented (in mg/ 1) by: thiamine HCQ 0.2; piridoxine HCL 1.0;  icotinic acid 1.0; mesoinositol 100; malt extract; sucrose 50.000; and agar 8.000 with pi-! = 5.7. The irradiation at 0.0; 0.5; 1.0; 2.0; 4.0; 8.0 and 12.0 kR doses was applied on, only medium, only nucellus, and medium and nucellus together. Irradiation of only nucellus and both nucellus and medium, at the same time, showed similar effects. Low doses of irradiation (until 2 kR) decrease the number of differential embryoids. The irradiation of culture medium, mainly at high doses, increases callus proliferatio

Embriogênese nucelar em óvulos abortivos de laranja 'pera' cultivados in vitro

The breeding of citrus species is limited by apomixis, gametic sterility and incompatibility. Abortive ovules were exacted from various stages of developing fruits of 'Pera' sweet orange (Citrus sinensis Osb.) and cultured in vitro on "MS" medium. Embryogenesis was increased from the time of fruit set up to 1,62 mix 1,60 cm. Abortive ovules and pseudobulbils obtained from abortive ovules were cultured on "MS" media supplemented with different growth substances. The best results were observed with complex organic substances (casein hydrolysate, malt extract, coconut milk and yeast extract). The development of pseudobulbils were not affected by growth substances.Existem sérios obstáculos, como apomixia, esterilidade gamética e incompatibilidade ao melhoramento genético das espécies cítricas. Óvulos abortivos da laranja 'Pera' (Citrus sinensis Osb.) foram extraídos de (ratos em diferentes fases de desenvolvimento (desde antes da antese até o fruto com aproximadamente 3 cm de diâmetro) e cultivados em meio "MS". Constatou-se tendência de maior número de embrióides/óvulo a partir da fase em que o fruto apresentou 1,62 cm x 1,60 cm. Óvulos de frutos com 3 cm de diâmetro e pseudobulbilhos obtidos a partir de óvulos abortivos foram inoculados em meio "MS", acrescido de inúmeras substâncias promotoras do crescimento. Os índices embriogênicos mais elevados em óvulos abortivos foram observados na presença de substâncias orgânicas complexas (caseína hidrolizada, extrato de malte, água de coco e extrato de levedura). O desenvolvimento de pseudobulbilhos não foi influenciado pela adição de substâncias de crescimento ao meio "MS"

Influência de reguladores de crescimento sobre a embriogênese in vitro de nucelos de Citrus sinensis cv. Valência

This paper describes the attempts to determine the methodology for regeneration of plants from nucelli. Nucelli were extracted from 'Valência' fruits (C. sinensis Osb.) twelve weeks after pollination and cultivated in vitro on "MS" mineral salts supplemented with (mg/l): thiamine HCL, 0.2; pyridoxine HCL, 1.0; nicotinic acid, 1.0; mesoinositol, 100; malt extract, 500; sucrose, 50.000; agar, 8.000; pH, 5.7. The treatments were combinations of kinetin (0.0; 0.25; 0.50; 1.0 and 1.5 mg/l) and 2,4 - diclorofenoxyacetic acid (D) (0.0; 0.5; 1.0 and 2.0 mg/l) with ten replications in dark and ten in light (1.500 lux) at 27oC ± 2oC. It was possible to get twelve nucellar embryos from a single nucellus. Kinetin and 2,4-D inhibited the embryogenesis. Ocasionally the formation of globular callus with high embryogenic potential was observed mainly in 0,25 mg/l kinetin and 0,5 mg/l 2,4-D medium. Objetivou-se determinar a metodologia de regeneração de plantas in vitro a partir de núcleos. Foram extraídos núcleos de frutos da cv. Valência (Citrus sinensis Osb.) doze semanas após a polinização, e cultivados em meio constituído pelos macro e micronutrientes do meio "MS", adicionado de (em mg/l): tiamina HCL, 0,2; piridoxina HCL, 1,0; ácido nicotínico, 1,0; mesoinositol, 100; extrato de malte, 500; sacarose, 50.000; ágar, 8.000; e pH, 5,7. Os tratamentos consistiram das combinações em dialélico de cinetina (0,0; 0,25; 0,50; 1,0 e 1,5 mg/l) e 2,4-D (0,0; 0,5; 1,0 e 2,0 mg/l), sendo que dez repetições foram mantidas no escuro e outras dez sob luz (1.500 lux) durante 16 horas diárias a 27oC ± 2oC, em delineamento inteiramente casualizado. Foram obtidos até doze embrióides diretamente de um único núcleo, e a adição de cinetina e 2,4-D inibiu esta embriogênese, principalmente com adição de 0,25 mg/l de cinetina + 0.5 mg/l de 2,4-D em culturas mantidas no escuro.

Variabilidade isoenzimática de acessos de mandioca de diferentes regiões do Brasil

A mandioca (Manihot esculenta Crantz) pertence à família Euphorbiaceae, gênero Manihot, cultivada em todo o país. É a única do gênero utilizada na alimentação. O presente trabalho teve como objetivo o estudo da variabilidade isoenzimática de 200 acessos de mandioca obtidos junto ao banco de germoplasma da Embrapa Amazônia Oriental. Os acessos foram agrupados de acordo com o local de origem, obtendo-se desta forma sete grupos: 1-Amazonas, 2-Amapa, 3-Bahia, 4-Para, 5-Rondonia, 6-Diversos, incluindo-se neste grupo os acessos que se apresentavam em pequena quantidade por local de origem (um ou no máximo dois indivíduos), e 7- Acessos de origem desconhecida. Os acessos foram também avaliados como um todo. Para a corrida eletroforética, foram utilizadas amostras de folhas jovens em gel de amido a 12%. Foram avaliados oito sistemas isoenzimáticos: glutamato desidrogenase (GTDH), fosfatase ácida (ACP), leucina aminopeptidase (LAP), isocitrato desidrogenase (IDH), xiquimato desidrogenase (SKDH), enzima málica (ME), malato desidrogenase (MDH) e glucose-6-fosfato desidrogenase (G6PDH). A análise revelou um loco polimórfico por sistema. O material avaliado apresentou grande variabilidade isoenzimática. O número médio de alelos por loco variou de 2,3 a 2,5, a heterozigosidade média observada (;) variou de 0,381 a 0,615, e o índice de diversidade de 0,479 a 0,559. Observou-se maior variabilidade genética dentro dos grupos do que entre grupos, sugerindo um padrão de distribuição de variabilidade genética semelhante ao esperado para populações naturais de espécies alógamas.Cassava (Manihot esculenta Crantz) belongs to the Euphorbiaceae family, and is widely cultivated in Brazil. The objective of this study was to evaluate the isoenzymatic variability of 200 cassava accessions from the germplasm bank of Embrapa Amazonia Oriental. Seven groups were formed according to their origin: 1-Amazonas, 2-Amapa, 3-Bahia, 4-Para, 5-Rondonia, 6-Various, for accessions with a maximum of three individuals per place of origin, and 7 - Accessions of indefinite origin. The accessions were also evaluated as a whole. For the electrophoretic analyses, samples of young leaves were used in a 12% starch gel. Eight isoenzymatic systems were evaluated: acid phosphatase (ACP), leucine aminopeptidase (LAP), glucose-6-phosphate dehydrogenase (G6PDH), malate dehydrogenase (MDH), shikimate dehydrogenase (SKDH), malic enzyme (ME), glutamate dehydrogenase (GTDH) and isocitrate dehydrogenase (IDH). Analysis revealed a polymorphic locus for each system and high isoenzymatic variability among accessions. The average number of alleles per locus varied from 2.3 to 2.5. Average observed heterozigosity varied from 0.381 to 0.615 and the diversity index varied from 0.479 to 0.559. Genetic variability within groups was greater than among groups, suggesting a distribution pattern similar to what can be expected for natural populations of outcrossing plants

End-to-End Joint Target and Non-Target Speakers ASR

This paper proposes a novel automatic speech recognition (ASR) system that can transcribe individual speaker's speech while identifying whether they are target or non-target speakers from multi-talker overlapped speech. Target-speaker ASR systems are a promising way to only transcribe a target speaker's speech by enrolling the target speaker's information. However, in conversational ASR applications, transcribing both the target speaker's speech and non-target speakers' ones is often required to understand interactive information. To naturally consider both target and non-target speakers in a single ASR model, our idea is to extend autoregressive modeling-based multi-talker ASR systems to utilize the enrollment speech of the target speaker. Our proposed ASR is performed by recursively generating both textual tokens and tokens that represent target or non-target speakers. Our experiments demonstrate the effectiveness of our proposed method.Comment: Accepted at Interspeech 202

Multiwalled carbon nanotubes grown in hydrogen atmosphere : An x-ray diffraction study

X-ray diffraction study of multiwalled carbon nanotube (MWNT) grown by arc discharge in hydrogen atmosphere is presented. It is found that the thermal-expansion coefficient along the radial direction of MWNT is widely distributed in a range from 1.6×10-5 K-1 to 2.6×10-5 K-1, indicating the existence of both of Russian doll MWNT and highly defective MWNT. Russian doll MWNT is suggested to have the outer diameter less than ∼100  Å . Thicker MWNT's are typically highly defective, and may have the jelly roll (scroll) or defective polygonal structure consisting of flat graphite domains

Current Performance and On-Going Improvements of the 8.2 m Subaru Telescope

An overview of the current status of the 8.2 m Subaru Telescope constructed and operated at Mauna Kea, Hawaii, by the National Astronomical Observatory of Japan is presented. The basic design concept and the verified performance of the telescope system are described. Also given are the status of the instrument package offered to the astronomical community, the status of operation, and some of the future plans. The status of the telescope reported in a number of SPIE papers as of the summer of 2002 are incorporated with some updates included as of 2004 February. However, readers are encouraged to check the most updated status of the telescope through the home page, http://subarutelescope.org/index.html, and/or the direct contact with the observatory staff.Comment: 18 pages (17 pages in published version), 29 figures (GIF format), This is the version before the galley proo

A cell-based high-throughput screening method to directly examine transthyretin amyloid fibril formation at neutral pH

Transthyretin (TTR) is a major amyloidogenic protein associated with hereditary (ATTRm) and nonhereditary (ATTRwt) intractable systemic transthyretin amyloidosis. The pathological mechanisms of ATTR-associated amyloid fibril formation are incompletely understood, and there is a need for identifying compounds that target ATTR. C-terminal TTR fragments are often present in amyloid-laden tissues of most patients with ATTR amyloidosis, and on the basis of in vitro studies, these fragments have been proposed to play important roles in amyloid formation. Here, we found that experimentally-formed aggregates of full-length TTR are cleaved into C-terminal fragments, which were also identified in patients' amyloid-laden tissues and in SH-SY5Y neuronal and U87MG glial cells. We observed that a 5-kDa C-terminal fragment of TTR, TTR81–127, is highly amyloidogenic in vitro, even at neutral pH. This fragment formed amyloid deposits and induced apoptosis and inflammatory gene expression also in cultured cells. Using the highly amyloidogenic TTR81–127 fragment, we developed a cell-based high-throughput screening method to discover compounds that disrupt TTR amyloid fibrils. Screening a library of 1280 off-patent drugs, we identified two candidate repositioning drugs, pyrvinium pamoate and apomorphine hydrochloride. Both drugs disrupted patient-derived TTR amyloid fibrils ex vivo, and pyrvinium pamoate also stabilized the tetrameric structure of TTR ex vivo in patient plasma. We conclude that our TTR81–127–based screening method is very useful for discovering therapeutic drugs that directly disrupt amyloid fibrils. We propose that repositioning pyrvinium pamoate and apomorphine hydrochloride as TTR amyloid-disrupting agents may enable evaluation of their clinical utility for managing ATTR amyloidosis