1,721,022 research outputs found
Linaria genistifolia (linnaeus) miller subsp. genistifolia sulu ekstrelerinin genotoksik ve mutajenik özelliklerinin allium ve ames testi ile araştırılması
No full textBu çalışmada, Linaria genistifolia (Linnaeus) Miller subsp. genistifolia, Plantaginaceae, bitkisinin toprak üstü kısımlarının sulu ekstresinin (Lg-ekstresi) genotoksik ve mutajenik etkileri sırasıyla A. cepa meristamatik kök hücreleri ve bakteriyel revertant mutasyon deneyinde Salmonella typhimurium TA98 and TA100 suşları kullanılarak metabolik aktivasyon (S9) varlığında ve yokluğunda araştırıldı. Allium kök büyüme inhibisyon testinde EC50 değeri yaklaşık olarak 15 g/L olarak belirlendi ve Lg-ekstresinin 0,5xEC50, EC50 and 2xEC50 konsantrasyonları soğan kök hücrelerine uygulanmıştır. Distile su ve metil metan sülfanat (MMS, 10 mg/L) sırasıyla negatif ve pozitif kontrol grubu olarak kullanıldı. Test edilen preparasyonların neden olduğu karakteristik etkisi mitotik indeks (Mİ) değerinin 7,5 g/L ve 15 g/L ( 24 ve 96 saatlik uygulamar hariç ) artması ve aynı şekilde mitotik indeks değerinin 30 g/L ve MMS'de azalmasıdır. Anafaz telofaz hücrelerinde yapışıklık, köprüler, kalgın kromozom ve bozulmuş anafaz telofaz gözlemlenirken diğer hücrelerde c-metafaz, prometafaz, poliploidi ve binüklear hücreler gözlemlendi. Lg-ekstresinin, S. typhimurium TA 98 ve TA100 suşlarında S9 varlığı ve yokluğunda mutajenik etkisi bulunmadı. Sonuçlar aynı zamanda istatistiksel olarak SPSS for Windows paket programında Duncan çoklu değişim testi ile değerlendirildi. Bu sonuçlar Lg-ekstresinin A. cepa kök meristematik hücrelerinde genotoksik aktivite gösterdiğini fakat Ames test sisteminde mutajenik aktivite göstermediğini ortaya koymuştur.In this study, genotoxic and mutagenic effects of aqueous extract from aerial parts Linaria genistifolia (Linnaeus) Miller subsp. genistifolia, Plantaginaceae (Lg-ext) were investigated by using both Allium cepa root meristematic cells and bacterial reverse mutation assay in Salmonella typhimurium TA98 and TA100 with or without metabolic activation system (S9), respectively. In Allium root growth inhibition test, EC50 value was determined approximately 15 g/L and 0.5xEC50, EC50 and 2xEC50 concentrations of Lg-ext were introduced to onion tuber roots and distilled water and methyl methane sulfonate (MMS, 10 mg/L) used as a negative and positive control, respectively. The characteristic effect caused by tested preparations was an increase of mitotic index (MI) in 7.5 g/L and 15 g/L (except 24 and 96 h) and simultaneous decrease of MI in 30 g/L and in MMS. While stickiness, bridges, chromosome laggards and disturbed anaphase-telophase were observed in anaphase-telophase cells, c-metaphase, pro-metaphase, polyploidy and binuclear cells were observed in other cells. Lg-ext was not found to be mutagenic on S. typhimurium TA 98 and TA100 with or without S9. The results were also analyzed statistically by using SPSS for Windows, and Duncan?s multiple range tests were performed respectively. These results indicate that Lg-ext exhibits genotoxic activity in A. cepa root meristematic cells but not mutagenic activity in Ames test system
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Cytogenetıc Effects of Imazethapyr Herbıcıde on The Root Merıstem Cells of Allium Cepa L.
No full textIn this study, the mitotic division and chromosomal effects of İmazethapyr herbicide on Allium cepa root meristematic cells were investigated. In Allium root growth inhibition test, EC50 value was determined as 20 ppm and 0.5xEC50, EC50 and 2xEC50 concentrations of Imazethapyr herbicide were introduced to onion tuber roots and distilled water and methyl methane sulfonate (MMS, 10 mg/L) used as a negative and positive control, respectively. Since A. cepa cell cycle is 24 hours, application process was carried out 24, 48, 72 and 96 hours. Mitotic index and mitotic phase frequences were calculated separately for each dose introduced. All the doses applied showed the decreased mitotic indexes as to control group and these declines were found to be statistically meaningful. While chromosome laggards, disturbed anaphase-telophase, stickiness and anaphase bridges were observed in anaphase-telophase cells, pro-metaphase, c-metaphase, polyploidy and binuclear cells were observed in other cells. The results were also analyzed statistically by using SPSS for Windows, and Duncan’s multiple range tests were performed. These results indicate that imazethapyr herbicide exhibits cytotoxic activity but not genotoxic activity (except 10 ppm) in A. cepa root meristematic cells.Bu çalışmada, imazethapyr herbisitinin Allium cepa kök ucu hücrelerindeki mitoz bölünme ve kromozomlar üzerine olan etkileri incelendi. Allium kök büyüme inhibisyon testinde EC50 değeri 20 ppm olarak belirlendi ve İmazethapyr herbisitinin 0,5xEC50, EC50 and 2xEC50 konsantrasyonları soğan kök hücrelerine uygulandı. Distile su ve metil metan sülfanat (MMS, 10 ppm) sırasıyla negatif ve pozitif kontrol grubu olarak kullanıldı. A. cepa’nın hücre döngüsü 24 saat olduğu için uygulama süresi 24, 48, 72 ve 96 saat olarak belirlendi. Mitotik indeks ve mitotik faz frekansları her bir doz ve süre için ayrı ayrı hesaplandı. Mitotik indeksteki değişiklikler tüm doz ve uygulamalarda kontrol grubuna göre azalmış olup bu azalışlar istatistiksel açıdan anlamlı bulundu. Anafaz telofaz hücrelerinde kalgın kromozom, bozulmuş anafaz telofaz, yapışıklık ve anafaz köprüsü gözlemlenirken diğer hücrelerde prometafaz, c-metafaz, poliploidi ve binüklear hücreler gözlemlendi. Sonuçlar aynı zamanda istatistiksel olarak SPSS for Windows paket programında Duncan çoklu değişim testi ile değerlendirildi. Bu sonuçlar imazethapyr herbisitinin A. cepa kök meristematik hücrelerinde sitotoksik etki gösterdiğini ve 10 ppm’lik doz hariç genotoksik aktivite göstermediğini ortaya koymuştur
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Streptomyces Coelicolor'daki metabolik değişiklikler üzerine bir araştırma
Full text linkTez (doktora) - Anadolu ÜniversitesiAnadolu Üniversitesi, Fen Bilimleri Enstitüsü, Biyoloji Anabilim DalıKayıt no: 450179Streptomisetler antibiyotikleri de içeren sekonder metabolitleri üretme yeteneğine sahip olmalarıyla bilinen başlıca toprak bakterileridir. Bu grubun üyeleri aynı zamanda sporulasyon olarak bilinen düzenli bölünme işlemi geçiren havasal hiflerin ereksiyonunu içeren çok kompleks morfolojik farklılıklar göstermektedirler. Streptomyces coelicolor Streptomiset genetik çalışmaları için model organizmadır ve genom dizisi belirlenmiştir. SCO2836 ve SCO2837'nin açık okuma çerçeveleri Streptomyces coelicolor A3(2) genomunun temel hücresel fonksiyonlar için gerekli genleri içeren korunmuş merkez çekirdek bölge içerisinde bulunmaktadır. SCO2836 ve SCO2837 genleri sırasıyla glikozil transferaz ve galaktoz oksidaz domaini içerdigi sanılan proteinleri kodlar. Bu çalışmada SCO2836 ve SCO2837 genleri in vitro olarak Tn5062 transpozonu ile mutasyona uğratıldı ve bu mutasyonların fenotipik etkileri farklı ortamlarda araştırıldı. Her iki mutantta da ortam koşullarına bağlı olarak havasal gelişmede gecikme gösterdi. Bu mutasyonlar Southern Blot ile doğrulandı. Ayrıca bu iki genin promotor bölgesinin oldugu kısım pRLux87 plazmitine aktarılarak farklı besiyerlerinde lusiferaz aktivitesine de bakıldı
Genotoxic effects of bismuth (III) oxide nanoparticles by allium and comet assay
No full textPubMed ID: 23790828Genotoxic effects of Bismuth (III) oxide nanoparticles (BONPs) were investigated on the root cells of Allium cepa by Allium and Comet assay. A. cepa roots were treated with the aqueous dispersions of BONPs at five different concentrations (12.5, 25, 50, 75, and 100. ppm) for 4. h. Exposure of BONPs significantly increased mitotic index (MI) except 12.5. ppm, total chromosomal aberrations (CAs) in Allium test. While stickiness chromosome laggards, disturbed anaphase-telophase and anaphase bridges were observed in anaphase-telophase cells, pro-metaphase and c-metaphase in other cells. A significant increase in DNA damage was also observed at all concentrations of BONPs except 12.5. ppm by Comet assay. The results were also analyzed statistically by using SPSS for Windows; Duncan's multiple range test was performed. These results indicate that BONPs exhibit genotoxic activity in A. cepa root meristematic cells. © 2013 Elsevier Ltd
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