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Dietary Omega-3 Oil Supplementation To Increase Omega-3 Polyunsaturated Fatty Acids In The Red Tilapia(Oreochromis Hybrid) And Catfish (Clarias Gariepinus)
Get PDFA study was carried out to determine the essential polyunsaturated fatty acid (PUFA)
profiles of the red tilapia (Oreochromis hybrid) and catfish (Clarias gariepinus) and
an attempt was made to increase the omega-3 polyunsaturated fatty acids by dietary
omega -3 oil supplementation. The fatty acid profiles of commercially farmed adult
fish were determined using standard extraction, fatty acid methylation and gas liquid
chromatographic procedures and the fatty acid concentration of dried fish tissues was
expressed in absolute amounts (mg/g) as a measure of the actual fatty acid content in
the fish tissues. The levels of total fatty acids, SFA, UFA, monoenes, total n-6, total
n-3, 18:2n-6 and 18:3n-3 were higher in the catfish compared to the red tilapia. The
higher (17-20% of the total fatty acids) n-6 PUFA found in both fish compared to n-3
PUFA (1.0 – 9.5 %) was characteristic for freshwater fish.
The absolute amounts of total n-6 and n-3 PUFA increased as the age of the fish
increased for both species of fish when measured from 10 to 75 days of age although
they decreased when expressed as a percentage of total fatty acids. The absolute amounts of total n-6 PUFA in the red tilapia increased from 10.0 ± 0.6 mg/g at 10
days to 26.6 ± 2.4 mg/g at 75 days of age. The absolute amounts of total n-3 PUFA
in the red tilapia increased from 3.6 ± 0.2 mg/g at 10 days to 9.4 ± 0.3 mg/g at 75
days of age. Similarly, the absolute amounts of total n-6 PUFA in the catfish
increased from 15.1 ±1.0 mg/g at 10 days to 36.5 ± 2.5 mg/g at 75 days of age whilst
the absolute amounts of total n-3 PUFA increased from 8.1 ± 0.2 mg/g at 10 days to
21.8 ± 1.5 mg/g at 75 days of age. The results were suggestive of a combined effect
of accumulation, desaturation and elongation and oxidation of the PUFA in the fish
tissues.
The Δ6 desaturase enzyme activity in the liver microsomes was measured in six of
each species of fish employing radiolabelled linoleic acid [1-14C] and argentation
thin layer chromatography. Desaturase activities were detected in both species but
the activity in the red tilapia (3.55 + 0.2%; 1.19 + 0.1 pmol/min/mg protein) was
higher, although not significant (p>0.05), than the catfish (3.07 ± 0.2%; 1.02 + 0.1
pmol/min/mg protein).
The antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase
(GSH-Px) and the lipid peroxidation value of malonaldehyde (MDA) were measured
in ten of each species of fish. The antioxidant activity was higher in the catfish whilst
the lipid peroxidation value was higher in the red tilapia. The activity of SOD (1.54 ±
0.1 U/g) and GSH-Px (0.37 ± 0.1 U/g) in the red tilapia was lower than the activity
of SOD (2.48 ± 0.1 U/g) and GSH-Px (1.18 ± 0.1 U/g) in the catfish. The MDA
values were 21.39 ± 0.5 nmol/g for the red tilapia compared to 19.15 ± 0.2 nmol/g
for the catfish. The dietary omega-3 oil supplementation trial was carried out for eight weeks where
the fish was reared in glass aquariums in under three dietary treatments, in triplicate.
The treatment diets were the control diet CON (with no oil added), or diets
containing added 10% or 20% flaxseed oil (10% FLAX or 20% FLAX) or added
10% or 20% cod-liver oil (10% COD, 20% COD). The desirable n-3 PUFA were not
increased by the 10% FLAX or 10% COD diets where the total n-3 PUFA
concentrations in the red tilapia were 3.2 + 0.1 mg/g (CON), 2.6 ± 0.2 mg/g (10%
FLAX) and 3.4 ± 0.2 mg/g (10% COD). The n-3 PUFA concentrations in the catfish
were 7.1 ± 0.4 mg/g (CON), 6.4 ± 0.1 mg/g (10% FLAX) and 6.4 ± 0.4 mg/g
(10%COD). However, the n-3 PUFA concentrations were significantly increased
(p<0.05) when fed the 20% FLAX and 20% COD diets. In the red tilapia the n-3
PUFA concentrations were 3.4 ± 0.1 mg/g (CON), 4.7 ± 0.1 mg/g (20% FLAX) and
3.8 ± 0.2 mg/g (20% COD). The n-3 PUFA concentrations in the catfish were 6.5 ±
0.3 mg/g (CON), 8.5 ± 0.6 mg/g (20% FLAX) and 9.0 ± 0.6 mg/g (20% COD).
However high mortality rates up to 60% were encountered when the 20% FLAX and
20% COD diets were used suggesting that the levels of the oils used in these diets
were toxic to the fish. Histological examinations carried out at post-mortem
confirmed the toxicological condition by the occurrence of several histopathological
lesions in the liver, kidney and small intestine.
In conclusion, the essential PUFA profiles of the red tilapia which has a herbivorous
mode of nutrition and the catfish which is more omnivorous, with different
desaturase and oxidative enzyme activities are somewhat different, where the former
represents a better source of desirable essential PUFA to the human consumer. The
concentrations of the desirable essential PUFA in both fishes can be increased by modifying their diets to contain added oils such as flaxseed or cod-liver oil but the
percentage of the added oils have to be between 10-20% of the diet to avoid toxicity
and high mortalities
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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