Differential transcriptional modulation of duplicated fatty acid-binding protein genes by dietary fatty acids in zebrafish (Danio rerio): evidence for subfunctionalization or neofunctionalization of duplicated genes

<p>Abstract</p> <p>Background</p> <p>In the Duplication-Degeneration-Complementation (DDC) model, subfunctionalization and neofunctionalization have been proposed as important processes driving the retention of duplicated genes in the genome. These processes are thought to occur by gain or loss of regulatory elements in the promoters of duplicated genes. We tested the DDC model by determining the transcriptional induction of fatty acid-binding proteins (Fabps) genes by dietary fatty acids (FAs) in zebrafish. We chose zebrafish for this study for two reasons: extensive bioinformatics resources are available for zebrafish at zfin.org and zebrafish contains many duplicated genes owing to a whole genome duplication event that occurred early in the ray-finned fish lineage approximately 230-400 million years ago. Adult zebrafish were fed diets containing either fish oil (12% lipid, rich in highly unsaturated fatty acid), sunflower oil (12% lipid, rich in linoleic acid), linseed oil (12% lipid, rich in linolenic acid), or low fat (4% lipid, low fat diet) for 10 weeks. FA profiles and the steady-state levels of <it>fabp </it>mRNA and heterogeneous nuclear RNA in intestine, liver, muscle and brain of zebrafish were determined.</p> <p>Result</p> <p>FA profiles assayed by gas chromatography differed in the intestine, brain, muscle and liver depending on diet. The steady-state level of mRNA for three sets of duplicated genes, <it>fabp1a/fabp1b.1/fabp1b.2</it>, <it>fabp7a/fabp7b</it>, and <it>fabp11a</it>/<it>fabp11b</it>, was determined by reverse transcription, quantitative polymerase chain reaction (RT-qPCR). In brain, the steady-state level of <it>fabp7b </it>mRNAs was induced in fish fed the linoleic acid-rich diet; in intestine, the transcript level of <it>fabp1b.1 </it>and <it>fabp7b </it>were elevated in fish fed the linolenic acid-rich diet; in liver, the level of <it>fabp7a </it>mRNAs was elevated in fish fed the low fat diet; and in muscle, the level of <it>fabp7a </it>and <it>fabp11a </it>mRNAs were elevated in fish fed the linolenic acid-rich or the low fat diets. In all cases, induction of the steady-state level of <it>fabp </it>mRNAs by dietary FAs correlated with induced levels of hnRNA for a given <it>fabp </it>gene. As such, up-regulation of the steady-state level of <it>fabp </it>mRNAs by FAs occurred at the level of initiation of transcription. None of the sister duplicates of these <it>fabp </it>genes exhibited an increase in their steady-state transcript levels in a specific tissue following feeding zebrafish any of the four experimental diets.</p> <p>Conclusion</p> <p>Differential induction of only one of the sister pair of duplicated <it>fabp </it>genes by FAs provides evidence to support the DDC model for retention of duplicated genes in the zebrafish genome by either subfunctionalization or neofunctionalization.</p

Molecular Mechanism Involved in Carotenoid Metabolism in Post-Smolt Atlantic Salmon: Astaxanthin Metabolism During Flesh Pigmentation and Its Antioxidant Properties

A better understanding of carotenoid dynamics (transport, absorption, metabolism, and deposition) is essential to develop a better strategy to improve astaxanthin (Ax) retention in muscle of Atlantic salmon. To achieve that, a comparison of post-smolt salmon with (+ Ax) or without (− Ax) dietary Ax supplementation was established based on a transcriptomic approach targeting pyloric, hepatic, and muscular tissues. Results in post-smolts showed that the pyloric caeca transcriptome is more sensitive to dietary Ax supplementation compared to the other tissues. Key genes sensitive to Ax supplementation could be identified, such as cd36 in pylorus, agr2 in liver, or fbp1 in muscle. The most modulated genes in pylorus were related to absorption but also metabolism of Ax. Additionally, genes linked to upstream regulation of the ferroptosis pathway were significantly modulated in liver, evoking the involvement of Ax as an antioxidant in this process. Finally, the muscle seemed to be less impacted by dietary Ax supplementation, except for genes related to actin remodelling and glucose homeostasis. In conclusion, the transcriptome data generated from this study showed that Ax dynamics in Atlantic salmon is characterized by a high metabolism during absorption at pyloric caeca level. In liver, a link with a potential of ferroptosis process appears likely via cellular lipid peroxidation. Our data provide insights into a better understanding of molecular mechanisms involved in dietary Ax supplementation, as well as its beneficial effects in preventing oxidative stress and related inflammation in muscle.publishedVersio

Red and white chinook salmon (Oncorhynchus tshawytscha): Differences in the transcriptome profile of muscle, liver, and pylorus

Astaxanthin (Ax), the main carotenoid responsible for the distinct red flesh color in salmonids (Oncorhynchus, Salvelinus, Salmo, and Parahucho), is added to the diet of farmed fish at a substantial cost. Despite the great economical value for the salmon industry, the key molecular mechanisms involved in the regulation of muscle coloration are poorly understood. Chinook salmon (Oncorhynchus tshawytscha) represent an ideal model to study flesh coloration because they exhibit a distinct color polymorphism responsible for two color morphs, white and red flesh pigmented fish. This study was designed to identify the molecular basis for the development of red and white coloration of fish reared under the same experimental conditions and to better understand the absorption mechanism of Ax in salmonids. Pyloric caeca, liver, and muscle of both groups (n = 6 each) were selected as the most likely critical target organs to be involved respectively in the intestinal uptake, metabolism, and retention of Ax. Difference in the transcriptome profile of each tissue using next-generation sequencing technology was conducted. Ten KEGG pathways were significantly enriched for differentially expressed genes between red and white salmon pylorus tissue, while none for the transcriptome profile in the other two tissues. Differential expressed gene (DE) analyses showed that there were relatively few differences in muscle (31 DE genes, p < 0.05) and liver (43 DE genes, p < 0.05) of white and red Chinook salmon compared approximately 1125 DE genes characterized in the pylorus tissue, with several linked to Ax binding ability, absorption, and metabolism.publishedVersio

Global variations in diabetes mellitus based on fasting glucose and haemogloblin A1c

Fasting plasma glucose (FPG) and haemoglobin A1c (HbA1c) are both used to diagnose diabetes, but may identify different people as having diabetes. We used data from 117 population-based studies and quantified, in different world regions, the prevalence of diagnosed diabetes, and whether those who were previously undiagnosed and detected as having diabetes in survey screening had elevated FPG, HbA1c, or both. We developed prediction equations for estimating the probability that a person without previously diagnosed diabetes, and at a specific level of FPG, had elevated HbA1c, and vice versa. The age-standardised proportion of diabetes that was previously undiagnosed, and detected in survey screening, ranged from 30% in the high-income western region to 66% in south Asia. Among those with screen-detected diabetes with either test, the agestandardised proportion who had elevated levels of both FPG and HbA1c was 29-39% across regions; the remainder had discordant elevation of FPG or HbA1c. In most low- and middle-income regions, isolated elevated HbA1c more common than isolated elevated FPG. In these regions, the use of FPG alone may delay diabetes diagnosis and underestimate diabetes prevalence. Our prediction equations help allocate finite resources for measuring HbA1c to reduce the global gap in diabetes diagnosis and surveillance.peer-reviewe

Correction: Lall, S.P.; Kaushik, S.J. Nutrition and Metabolism of Minerals in Fish. Animals 2021, 11, 2711

The authors found some omissions and errors in the original paper [...

The health benefits of farmed salmon: Fish oil decontamination processing removes persistent organic pollutants

Peer reviewed: YesNRC publication: Ye

Nutrition, feeding, and behavior of fish

Nutrition and feeding influence growth, reproduction, and health of fish and their response to physiologic and environmental stressors and pathogens. The basics of fish metabolism are similar to those of warm-blooded animals in that they involve food intake, digestion, absorption, and transport of nutrients to the various tissues. Fish, however, being the most primitive form of vertebrates, possess some distinguishing features which will be discussed. Unlike warm-blooded animals, which are homoeothermic, fish are poikilothermic, so their body temperature and metabolic rate depends on the water temperature and this has practical implications for the nutrition, feeding and health of fish. Several behavioral responses have been linked to methods of feeding, feeding habits, frequency of feeding, mechanisms of food detection, and food preferences. Fish are also unique among vertebrates in their ability to absorb minerals not only from their diets but also from water through their gills and skin.NRC publication: Ye

Urinary phosphorus excretion in haddock, Melanogrammus aeglefinus (L.) and Atlantic salmon, Salmo salar (L.)

The discharge of urinary and fecal phosphorus (P) from fish farms is a major environmental concern. In this study, urine P excretion in a potential aquaculture species, haddock was quantified and compared with values for Atlantic salmon. Fish were fed a commercial haddock diet containing 1.4% phosphorus, at a rate of 3% body weight for 3 weeks. Urine was collected four times a day (0, 3, 6 and 17 h after feeding). Urine volume, urine pH, urine phosphate concentration, and the relationship between urine volume and amount of food in the gut during urine collection were measured. Haddock and salmon excreted the highest quantity of urine at 3 and 6 h after ingestion of a meal. The total volume of urine measured at these periods was 83.0\uc2\ub15.18 and 243.8\uc2\ub110.51 \uc2\ub5l kg-1 body weight (BW) urine, respectively. Urine phosphate concentrations of haddock and salmon were 4.6\uc2\ub10.08 and 1.0\uc2\ub10.08 mmol l-1 and urine pH was 6.2\uc2\ub10.25 and 7.5\uc2\ub10.01, respectively. The maximum urine volume was observed at 3-h post-feeding in haddock and 6 h in Atlantic salmon. The relationship between haddock urine volume and the gut content was best fitted by the quadratic equation: Haddock urine volume (\uc2\ub5l kg-1 BW)=155.6\u20134.68 (% gut content)+ 0.049 (% gut content)2. This experiment was repeated and similar results were obtained.Peer reviewed: YesNRC publication: Ye

Urinary phosphorus excretion in haddock, Melanogrammus aeglefinus (L.) and Atlantic salmon, Salmo salar (L.)

The discharge of urinary and fecal phosphorus (P) from fish farms is a major environmental concern. In this study, urine P excretion in a potential aquaculture species, haddock was quantified and compared with values for Atlantic salmon. Fish were fed a commercial haddock diet containing 1.4% phosphorus, at a rate of 3% body weight for 3 weeks. Urine was collected four times a day (0, 3, 6 and 17 h after feeding). Urine volume, urine pH, urine phosphate concentration, and the relationship between urine volume and amount of food in the gut during urine collection were measured. Haddock and salmon excreted the highest quantity of urine at 3 and 6 h after ingestion of a meal. The total volume of urine measured at these periods was 83.0\uc2\ub15.18 and 243.8\uc2\ub110.51 \uc2\ub5l kg-1 body weight (BW) urine, respectively. Urine phosphate concentrations of haddock and salmon were 4.6\uc2\ub10.08 and 1.0\uc2\ub10.08 mmol l-1 and urine pH was 6.2\uc2\ub10.25 and 7.5\uc2\ub10.01, respectively. The maximum urine volume was observed at 3-h post-feeding in haddock and 6 h in Atlantic salmon. The relationship between haddock urine volume and the gut content was best fitted by the quadratic equation: Haddock urine volume (\uc2\ub5l kg-1 BW)=155.6\u20134.68 (% gut content)+ 0.049 (% gut content)2. This experiment was repeated and similar results were obtained.Peer reviewed: YesNRC publication: Ye

Vitamin K deficiency inhibits mineralization and enhances deformity in vertebrae of haddock (Melanogrammus aeglefinus L.)

Vitamin K has been known to regulate bone formation through osteocalcin synthesis by osteoblasts, which is important for mineralization and bone structure. The mechanism underlying the relationship of vitamin K with the changes of microanatomy is not fully understood, and our goal is to test whether bone deformities develop in association with vitamin K deficiency. Fish were fed a semi-purified diet containing either devoid (0.00 mg/kg diet) or adequate (40.0 mg/kg diet supplemented but 20.8 mg/kg analyzed) levels of vitamin K (menadione sodium bisulphite) for 20 weeks. At the end of 8 and 20 weeks, fish were subjected to gross examination and X-ray, and mineral content of the vertebrae was measured. The vertebrae were also subjected to histological, histomorphometric and enzyme histochemical examinations to determine the bone formation and resorption. Vitamin K deficiency primarily decreased bone mineralization and subsequently a decrease in bone mass thus resulted in an increased susceptibility to bone deformity. The occurrence of bone deformities coincided with an increased amount of osteoid tissue and decreased bone mineral content. Number of osteoblasts and osteoclasts were not affected by dietary vitamin K. In conclusion, vitamin K deficiency can impair bone mineralization and enhances bone deformities.Peer reviewed: YesNRC publication: Ye