1,720,960 research outputs found
Structural changes of in vitro matured buffalo and bovine oocytes following cryopreservation.
No full textThe aim of this work was to evaluate chromatin and spindle organization of buffalo and bovine in vitro matured oocytes after vitrification/warming by Cryotop and after their exposure to cryoprotectants (CP). In vitro matured oocytes were vitrified/warmed and exposed to the vitrification/warming solutions containing ethylene glycol (EG), dimethyl sulfoxide (DMSO) and sucrose as CP. Two hours after warming, oocytes were fixed and immunostained for microtubules and nuclei and examined by fluorescence microscopy. Data were analyzed by Chi Square test. A higher percentage of Telophase II stage oocytes was found in the toxicity (26 and 34% in bovine and buffalo) and the vitrification groups (13 and 7% in bovine and buffalo) compared to the control, indicating occurrence of activation. An increased percentage of oocytes with abnormal spindle and chromosome organization was found in oocytes exposed to CP (24 and 13% in bovine; 32 and 30% in buffalo respectively) and in those vitrified (26 and 31% in bovine; 26 and 29% in buffalo respectively) compared to the control (0 in bovine and 2.5% in buffalo)
HYALURONIC ACID IMPROVES CRYOTOLERANCE OF BUFFALO (BUBALUS BUBALIS) IN VITRO-DERIVED EMBRYOS
No full textAlthough in vitro embryo production efficiency in buffalos has greatly improved over the years, the in vitro-produced embryos show lower viability and resistance to cryopreservation. Therefore, it is necessary to optimize the in vitro culture conditions to improve embryo quality. Hyaluronic acid, a glycosaminoglican present in oviducal and uterine fluids, has been shown to successfully support in vitro development of bovine embryos (Stojkovic et al. 2002 Reproduction 124, 141-153). The aim of this study was to evaluate the influence of high concentrations of hyaluronic acid (HA) during late in vitro culture on blastocyst development, as well as on their cryotolerance after cryotop vitrification in buffalos. In vitro matured and fertilized buffalo oocytes (n=1007) from slaughterhouse ovaries were cultured for 4 days in SOFaa supplemented by 8mgmL(-1) of BSA in a controlled gas atmosphere consisting of 5% CO(2), 7% O(2) and 88% N(2), in humidified air, at 38.5degreesC. On Day 4, cleavage rate was assessed (75.2%) and all of the cleaved elements were divided into 3 different late culture groups: 8mgmL(-1) of BSA (n=244; group A), 8mgmL(-1) of BSA supplemented by 6mgmL(-1) of HA (n=251; group B) and 1mgmL(-1) of BSA supplemented by 6mgmL(-1) of HA (n=262; group C). On Day 7 after IVF, embryo outcome was assessed and all of the embryos were vitrified by cryotop [De Rosa et al. 2007 Ital. J. Anim. Sci. 6 (Suppl 2), 747-750] and cultured for 24h. The resistance to cryopreservation was evaluated by assessing the survival rate on the basis of morphological criteria and the percentage of embryos reaching a more advanced developmental stage after 24h culture. Data were analysed by the chi-square test. No differences in blastocyst rate were recorded among groups (43.9, 44.3 and 40.0%, respectively in A, B and C groups). However, out of the total embryos, a higher percentage of Grade 1 hatched blastocysts (Robertson and Nelson 1998 Manual of the International Embryo Transfer Society 9, 103-16) was observed in group C (P<0.05) than in groups A and B (14.3, 18.8 and 25.5% in A, B and C groups, respectively). Although the supplementation with HA did not improve the survival rates following vitrification-warming (51.1, 59.4 and 58.4% in A, B and C groups, respectively), the percentage of vitrified-warmed embryos that resumed development and reached a more advanced developmental stage after culture increased (P<0.01) in group C (20.7, 27.7 and 37.6% in A, B and C groups, respectively). In conclusion, the addition of 6mgmL(-1) of HA, together with a limited protein source (i.e. 1mgmL(-1) of BSA), during late culture improved buffalo embryo quality, indicated by both the greater percentage of advanced-stage embryos and by the resumption of development after post-warming culture
Energy source during in vitro culture (IVC) and sex ratio of bovine embryos
No full textMost systems for producing mammalian embryos in vitro use glucose as an energy source despite putative toxic effects. It is known that female embryos are more sensitive to negative effects of glucose during IVC. The aim of this work was to evaluate whether replacing glucose with myo-inositol and citrate during IVC affects sex ratio. Abattoir-derived oocytes were matured and fertilized in vitro using standard procedures. After 20–22 h of gametes co-incubation, zygotes were denuded and cultured in SOF containing either 1.5 mM glucose or 2.77 mM myo-inositol and 0.34 mM citrate, for 7 days. The percentages of blastocysts were recorded and the embryos (on average 122 per group) were sexed by PCR as previously described (Alomar, 2008, Anim. Reprod. Sci. 107 48-61.). Differences in blastocyst rates and in the percentages of female embryos between groups were analyzed by Chi-Square test. The results of this study showed that myo-inositol-citrate increased both blastocyst yield (37.4 vs 29.5 %, respectively; P<0.01) and the percentage of female embryos compared to glucose (61.5 vs 45.6 % respectively; P<0.05). In conclusion, these results suggest to use myo-inositol and citrate in culture media to switch embryo sex ratio towards females
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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