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Comparison of ovarian follicles at follicle wave emergence between heifers with high versus low numbers of follicles
No full textComparison of ovarian follicles at follicle wave emergence between heifers with high versus low numbers of follicles
AE Zielak1, F Ward1, N Forde1, F Mossa1, P Lonergan1, JJ Ireland2, and ACO Evans1
School of Agriculture Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland and 2Department of Animal Science, Michigan State University, East Lasting, Michigan 48824,USA (E-mail [email protected])
Introduction. Recent studies in cattle demonstrate that the numbers of antral follicles during follicular waves vary greatly among animals, but are highly repeatable within individuals. Although relatively high numbers of antral follicles are positively associated with fertility in numerous species, the causes and physiological significance of the high variation in follicle number during follicular waves in cattle is not known. The purpose of this study was to compare follicular fluid steroid concentrations, and mRNA levels for aromatase and LH and FSH receptors in follicles from heifers with low versus high numbers of follicles.
Materials and Methods. Cross-bread beef heifers (n=32) were synchronized with two injections of prostaglandin (PG) given 11 days apart. Ovarian follicle development was monitored on a daily basis in each heifer by transrectal ultrasonography. Heifers were then assigned into three groups based on the peak number of follicles (≥3 mm in diameter) per wave: Low (≤14 follicles, n=5), Intermediate (15≥26 follicles, n=22) or High (≥27 follicles, n=5). Animals in the Low and High group were slaughtered at emergence of the first follicle wave (12 to 24 hrs after ovulation). Pairs of ovaries were collected and weight. All follicles ≥3 mm were dissected from both ovaries and diameter was measured. Follicular fluid and granulosa and theca cells were isolated. Follicles were classified either individually within animal (F1 to F6 based on follicle diameter: when two follicles had the same diameter they were classified based on follicular fluid oestradiol concentrations) or in one of three size classes (4-4.5 mm, 5-5.5 mm and ≥6 mm). Oestradiol and progesterone concentrations in follicular fluid were measured by RIA and levels of mRNA were measured by Q-RT-PCR (and were expressed relative to β-Actin).
Results. Total weight of ovaries was greater (P0.05). The follicular fluid oestradiol concentrations of the largest (F1) and the second largest (F2) follicles were greater (P<0.05) in heifers with low versus high numbers of follicles (115.7±20.9 v 48.6±11.3; 106.1±18.6 v 40.5±10.3 ng/ml). Also heifers with low numbers of follicles had greater (P<0.05) E2:P4 ratio in the largest follicles than similar follicles in heifers with high number of follicles (4.8±1.0 v 2.3±0.9). Within different follicle size classes’ follicular fluid oestradiol concentrations were greater (P<0.05) in follicles ≥6 mm in diameter in heifers with low versus high numbers of follicles (105.3±15.9 v 41.2±10.2 ng/ml, n=10 v 7). The E2:P4 ratio was greater (P<0.05) in follicles in the 5-5.5 mm and ≥6 mm size classes in animals from the Low group compared to the High group (6.6±2.6 v 1.8±0.53, n=8 v 12; 4.0±0.7 v 1.9±0.6, n=10 v 7).
In granulosa cells, levels of mRNA for aromatase were greater (P0.05) between animals in the Low and High groups. In theca cells, mRNA levels for LH receptors were higher in the F2 (0.009±0.002 v 0.003±0.002) and F3 (0.005±0.001 v 0.014±0.004) follicles from heifers with low compared to high numbers of follicles, but there was no difference between F1 follicles (0.022±0.004 v 0.026±0.012).
Conclusion. We concluded that heifers with low numbers of ovarian follicles have smaller ovaries, and their follicles about the time of follicle wave emergence have higher follicular fluid oestradiol concentrations and more mRNA for the aromatase enzyme. The causes and significance of these differences remains to be established
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
Distribution of follicle numbers in dairy cows aged from 2 to 11 years
No full textDistribution of follicle numbers in dairy cows aged from 2 to 11 years
F. Mossa1, S.Butler2, P.Duffy1, F. Jimenez-Krassel3, J Folger3, G.W. Smith3, P. Lonergan1, J.J. Ireland3, A.C.O. Evans1
1School of Agriculture Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland, 2 Teagasc, Moorepark Dairy Research Centre, Fermoy, Co. Cork, Ireland, 3Department of Animal Science, Michigan State University, East Lasting, Michigan 48824,USA (E-mail [email protected])
Introduction. The number of antral follicles in cattle is highly repeatable in individuals, while being highly variable between animals (Burns et al., 2005; Ireland et al., 2007). Furthermore, a high antral follicle number is associated with a greater number of transferable embryos following superovulation (Singh et al, 2004; Ireland et al, 2007). However, the relation between age of the cow and follicle numbers has not been investigated. Furthermore, the ability to phenotypically classify cows with respect to follicle number based on a single rather than multiple ultrasound examinations would be desirable to rapidly identify cattle with high responsiveness to superovulation. The aim of this study was to investigate the accuracy of a single ultrasonographic examination, performed on a random day of the oestrous cycle, and to assess the variability in the number of follicles in dairy cows of different ages.
Materials and Methods. Transrectal ultrasonography was performed on 116 dairy cows, aged from 2.6 years to 10.8 years, to assess the number of ovarian follicles ≥3 mm in diameter on a random day of the oestrous cycle. Based on this scan, a subset of animals was selected as follows: cows with less than 15 antral follicles ≥3 mm in diameter (Low group n= 8) and those with more than 30 follicles≥3 mm in diameter (High group, n=10). Both groups were synchronized with 2 injections of PGF2α (Estrumate®, Loughrea, Co., Galway, Ireland) 11 days apart and the number of follicles ≥ 3 mm in diameter was counted daily during an entire oestrous cycle. The correlations between follicle number and animal age and between a single ultrasound examination and the maximal number of follicles during follicular waves were analyzed using ANOVA.
Results. Amongst the 116 animals, the number of antral follicles ≥3mm in diameter per animal ranged from 4 to 44, with a mean (±SEM) of 17.99±0.78 (Fig.1). Cow age was not related to the number of follicles detected on a random day of the oestrous cycle (R2 = 0.0086; P=0.31). Amongst the subsets of animals, the mean (±SEM) number of follicles was 35.9±1.50 in the High group and 8.13±0.71 in the Low group. No difference (P=0.89) was detected between the two groups in mean age (High=5.28±0.43 years, Low=5.38±0.62 years). Numbers of follicles at the initial random scan were highly correlated with the maximal number of follicles observed during follicular waves of a complete oestrous cycle (R2 =0.7756; P <0.0001).
Conclusion. The number of antral follicles in the ovaries of dairy cows is highly variable among cattle but apparently not linked with cow age. Cows with consistently high or low numbers of follicles can be reliably identified through transrectal ultrasonography performed on a single random day of the oestrous cycle
References.
Burns DS, Jimenez–Krassel F, Ireland J, Knight PG, Ireland JJ. Numbers of antral follicles during follicular waves in cattle: evidence for high variation among animals, very high repeatability in individuals, and an inverse association with serum-follicle-stimulating hormone concentrations. Biol. Reprod. 2005; 73:54-62.
Ireland JJ, Ward F, Jimenez-Krassel F, Ireland JLH, Smith GW, Lonergan P, Evans ACO. Follicle numbers are highly repeatable within animal but inversely correlated with FSH concentrations and the proportion of good quality embryos after superstimulation in cattle. Human Reprod. 2007 in press.
Singh J, Dominguez M, Jaiswal R, Adams GP. A simple ultrasound test to predict the superstimulatory response in cattle. Theriogenology. 2004; 62: 227-243
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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