1,720,966 research outputs found
Effects of Trehalose and Catalase on the Viability and Kinetic Parameters of Cryopreserved Ram Sperm
Full text linkBackground: Most part of ram spermatozoa membrane has unsaturated fatty acids (phospholipids). Membrane structure of cells is composed of double ordered phospholipid layers adorned with mosaic-like protein, glycoprotein and glycolipids. Sperm freezing protocols could be negatively affected on ram sperm motility, viability and acrosome integrity during cryopreservation. For these reasons, researchers were designed their topics has led to the search for effective antioxidant systems against peroxidative damage and spermatozoon dysfunction. There are three protective enzymatic systems against reactive oxygen species (ROS) damage in sperm. These include superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase / reductase cycles Catalase (CAT) is a hemo-protein in the enzyme tetramer structure. The aim of this study was to investigate the effects of trehalose, catalase and their combinations on ram sperm parameters after the cryopreservation/thawing process.Materials, Methods & Results: At the out of breeding season (March-May) seven rams (1-3 years of age) were used in this study. Ejaculates were collected by electro-ejaculator twice a week. Pooled ejaculates were at 37°C, divided into six aliquots, diluted with the Tris based extender containing Trehalose 25 mM (Group-1), Trehalose 50 mM (Group-2), Catalase 200 µg (Group-3), Catalase 400 µg (Group-4), Trehalose 50 mM + Catalase 400 µg (Group-5) and no anti-oxidant (control), respectively, were cooled to 5°C than frozen in 0.25 mL French straws on the nitrogen vapour and stored in liquid nitrogen. The extender supplemented with Group 1 (54.1 ± 1.53; 73.1 ± 4.37), 50 mM (58.3 ± 4.01; 63.1 ± 0.30) and Group 5 (56.6 ± 1.05; 58.3 ± 0.55) resulted in higher subjective motility in comparison to the control (40.0 ± 3.87; 40.5 ± 0.22) group respectively (P < 0.05). Besides, Group 1 (60.16 ± 4.39) and Group 5 (59.60 ± 2.21) led to higher CASA total motility when compared to control (44.40 ± 8.13) group (P < 0.05). Sperm progressive motility was better in Group 1 (20.57 ± 6.90) than the Group 3 (10.63 ± 3.59) [P < 0.05]. Casa kinetic parameters of catalase 200 (Group 3) was higher values than other groups in VCL, VSL, VAP, LIN parameters (P < 0.05). There were no statistically significant differences on the membrane integrity parameter between the groups (P > 0.05).Discussion: Freezing ram sperm is extremely difficult process when compared bull and dog semen. Previous studies showed that antioxidants which were adding into the ram freezing extender gave positive effects solely or combination. In this study similar results were taken at trehalose 25, 50 mM and trehalose 50 mM + catalase 400 µg except 200 and 400 µg catalase groups. These findings supported some researches but lots of them opposite of catalase results. Catalase is found semen and ameliorates the sperm parameters when adding the liquid storage. Also after diluted and equilibrated catalase groups motilities were better than the control group. During the freezing stage catalase efficiency has been restricted. On the other hand when it combined with the trehalose 50 mM, catalase activity was triggered. Trehalose acts on sperm as non-permanent had a protective action related both osmotic effect and specific interactions with membrane phospholipids. Our data suggest that solely Trehalose 50 mM or combination with Catalase 400 µg can be added to Tris based extender for improving the post-thawed sperm quality in ram semen
Cryopreservation and evaluation of Akkaraman ram semen with 7-dehydrocholesterol
No full textThe experiment was conducted to determine the in vitro results of 7-dehydrocholesterol loaded cyclodextrin compound (7-DCLC) addition to tris extenders for freezing ram semen. Three Akkaraman rams, local species in Turkey, were used. Semen samples were extended with tris containing 0 mg (control), 1.5 mg, 2.5 mg and 3.5 mg/120x10(6) 7-DCLC and they were equilibrated to 4 degrees C and frozen in mini straws then stored in liquid nitrogen. Straws were thawed at 37 degrees C for 30 s in water bath for spermatological examination. Statistically significant differences were observed between 7-DCLC and control groups in terms of acrosome integrity, CASA motility, HOS test and viability after thawing (P<0.001). In all these parameters, control group had the lowest percentages. There was no statistically significant difference between groups in terms of DNA fragmentation, abnormal spermatozoa ratio, mitochondrial activation, lipid peroxidation and apoptosis level (P>0.05). In conclusion, it can be said that adding 7-DCLC to Akkaraman ram semen improved cell membrane cryosurvival. Besides, 7-DCLC can be used in tris extender instead of cholesterol loaded cyclodextrin (CLC) compounds for sperm cryopreservation
Genomewide association of male reproductive traits in Aksaray Malakli dogs
No full textWOS: 000449849900037PubMed: 30085374Male reproductive parameters are often used for the functional examination and evaluation of predicted genetic values for future aspects. However, these traits are relatively reliable until the measurable effects are expressed on desired traits. Therefore, we aimed to associate the single nucleotide polymorphism (SNP) genotype of the investigated characteristics and reproductive loci. A total of 46 male dogs are divided into three age groups (I = 7 years, n = 8). The testis, scrotum and body weight, libido sexualis and ejaculation time for each fraction were monitored as functional traits, while the pH, fractional semen volume, motility, concentration, and abnormal and dead spermatozoa rate were recorded as spermatological traits. The Affymetrix Canine 127 K SNP genotyping array v2 (Affymetrix Inc., California, USA) was used for SNP genotyping. In the primary results, the scrotal circumference was found to be higher in group II compared to other groups (p < 0.05) and the lowest total abnormal spermatozoa rate was found in group I (p < 0.05). The normal spermatozoa rate was found to be significantly above the threshold in relation to the SNP in chromosome 17. In conclusion, this study represents an exciting first step towards SNP association with dog semen spermatological parameters. Future studies might be undertaken to evaluate this SNP region for gene-knockout and expression analysis and for fine mapping to validate and/or discover the exact position of the effect region.Scientific and Technological Research Council of Turkey (TUBITAK) [114O636]Scientific and Technological Research Council of Turkey (TUBITAK), Grant/Award Number: 114O63
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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