Montana Kaimin, March 5, 1981

Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/8304/thumbnail.jp

Representative sagittal sections of the buccopharyngeal cavity of Atlantic salmon juveniles at various time points (days post hatch [dph]).

<p><b>(A)</b> General overview of alevin head at 46 dph; <b>(B-C)</b> Development of anterior region of oral cavity: two visible oral valves, squamous epithelium scattered with mucus cells and taste buds, presence of mandibular teeth and lingual teeth at 7 dph (B); increase in number of mucus cells, taste buds and teeth at 54 dph (C); <b>(D-E)</b> Development of pharynx: squamous epithelium scattered with mucus cells and taste buds, and presence of pharyngeal teeth indicating by the dental alveoli at 7 dph (D); large increased number of mucus cells, taste buds and pharyngeal teeth at 54 dph. Abbreviations: b, bone; ct, connective tissue; da, dental alveolus; mc, mucus cell; ov, oral valve; t, tooth; tb, taste bud. Scale bar: (A) = 400 μm; (B-E) = 50 μm.</p

Primer pair sequences, amplicon size (AS; in basepairs [bp]), PCR efficiency (Eff.) and Genbank accession number (Acc. No.) for the genes used for quantitative real-time PCR.

<p>* Two Atlantic salmon ghrl isoforms have been reported [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124179#pone.0124179.ref039" target="_blank">39</a>]. The primer set used in this study has a perfect match to both isoforms, and will therefore not discriminate between them.</p><p>^# The <i>cck-l</i> isoform was chosen based on higher expression in the intestine [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124179#pone.0124179.ref039" target="_blank">39</a>].</p><p>Primer pair sequences, amplicon size (AS; in basepairs [bp]), PCR efficiency (Eff.) and Genbank accession number (Acc. No.) for the genes used for quantitative real-time PCR.</p

Development of the expression of transporter genes of juvenile Atlantic salmon as a function of time (days post hatch), differentiated by the pre-feeding period and the period following start-feeding (indicated by the vertical dotted line at 46 days post hatch) with the experimental diets (fishmeal or soybean meal diets).

<p>Values are mean fold change as compared to the respective time point of first detection; n = 3 pooled samples of 3 individual fish per tank (three tanks per diet) with standard error represented by vertical bars. Abbreviations: <i>pept</i>, peptide transporter; <i>sglt1</i>, sodium/glucose cotransporter 1; <i>cd36</i>, cluster of differentiation 36; <i>npc1l1</i>, Nieman Pick C1-like 1; <i>abcg5</i>, ATP-binding cassette G5; <i>aqp8ab</i>, aquaporin 8ab. See also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124179#pone.0124179.s002" target="_blank">S2 Table</a> for mean values and results of post-hoc one-way ANOVA with time as the main variable.</p

Formulation and proximate composition (as fed basis) of the experimental diets.

<p>^aNorseco-LT, Norsildmel, Bergen, Norway</p><p>^bExtracted Soybean meal, Denofa As, Fredrikstad, Norway</p><p>^cNorSalmOil, Norsildmel, Bergen, Norway</p><p>^dNormin AS, Hønefoss, Norway. Diets supplied with following vitamins per kg diet: vitamin D3, 3000 I.E; vitamin E (Rovimix, 50%), 160mg; thiamine, 20mg; riboflavin, 30mg; pyridoxine-HCl, 25mg; vitamin C (Riboflavin Stay C 35%), 200mg; calcium pantothenate, 60mg; biotin, 1mg; folic acid, 10mg; niacin, 200mg; vitamin B12, 0.05 mg; menadione bisulphate, 20mg.</p><p>^eNormin AS, Hønefoss, Norway. Diets supplied with following minerals per kg diet: magnesium, 750mg; potassium, 800mg; zinc, 120mg; iron, 60 mg; manganese, 30mg; copper, 6mg and selenium; 0.3mg.</p><p>^fGross energy was calculated using the energy concentrations of 39.5 for lipid, 23.6 for protein, and 17.2 kJ/g for carbohydrates (carbohydrate levels in diets were calculated as: 100 –[water + crude protein + crude lipid + ash]).</p><p>Formulation and proximate composition (as fed basis) of the experimental diets.</p

Ontogeny of the Digestive System of Atlantic Salmon (<i>Salmo salar</i> L.) and Effects of Soybean Meal from Start-Feeding

<div><p>Despite a long history of rearing Atlantic salmon in hatcheries in Norway, knowledge of molecular and physiological aspects of juvenile development is still limited. To facilitate introduction of alternative feed ingredients and feed additives during early phases, increased knowledge regarding the ontogeny of the digestive apparatus in salmon is needed. In this study, we characterized the development of the gastrointestinal tract and accessory digestive organs for five months following hatch by using histological, biochemical and molecular methods. Furthermore, the effects of a diet containing 16.7% soybean meal (SBM) introduced at start-feeding were investigated, as compared to a fishmeal based control diet. Salmon yolk sac alevins and fry were sampled at 18 time points from hatch until 144 days post hatch (dph). Histomorphological development was investigated at 7, 27, 46, 54 and 144 dph. Ontogenetic expression patterns of genes encoding key digestive enzymes, nutrient transporters, gastrointestinal peptide hormones and T-cell markers were analyzed from 13 time points by qPCR. At 7 dph, the digestive system of Atlantic salmon alevins was morphologically distinct with an early stomach, liver, pancreas, anterior and posterior intestine. About one week before the yolk sac was internalized and exogenous feeding was started, gastric glands and developing pyloric caeca were observed, which coincided with an increase in gene expression of gastric and pancreatic enzymes and nutrient transporters. Thus, the observed organs seemed ready to digest external feed well before the yolk sac was absorbed into the abdominal cavity. In contrast to post-smolt Atlantic salmon, inclusion of SBM did not induce intestinal inflammation in the juveniles. This indicates that SBM can be used in compound feeds for salmon fry from start-feeding to at least 144 dph and/or 4-5 g body weight.</p></div

Representative sagittal sections of intestine, liver and pancreas of Atlantic salmon juveniles at various time points (days post hatch [dph]).

<p><b>(A)</b> General overview of the intestine at 27 dph; <b>(B-E)</b> Development of the proximal intestine; absence of pyloric caeca at 7 dph (B), appearance of pyloric caeca buds at 27 dph (C), and more developed pyloric caeca at 46 and 54 dph (D and E); <b>(F-I)</b> Development of the distal intestine; presence of incipient mucosal folds without goblet cells at 7 dph (F), appearance of mucosal folds scattered with goblet cells (arrows) within epithelium at 27, 46 and 54 dph (G-I), and presence of low level of supranuclear vacuoles at 54 dph (I); <b>(J-K)</b> Development of the mid intestine; simple epithelium without goblet cells at 7 dph (J), and following appearance of mucosal folds scattered with goblet cells at 46 dph (K); <b>(L-M)</b> Development of the rectum (re); epithelium consisting of cuboidal cells devoid of mucus cells at 7 (L) and 46 (M) dph; <b>(N-P)</b> Development of the liver (li) consisting of polygonal hepatocytes with a prominent basophilic nucleus and eosinophilic cytoplasm irregularly arranged along the sinusoids around a central vein; increasing accumulation of glycogen-containing vacuoles (arrows) in hepatocytes from 7 (N) to 46 (O) dph; low level of glycogen deposit in liver following start-feeding at 54 dph (P); <b>(Q)</b> Fully differentiated pancreatic tissue composed of exocrine cells with zymogen granules (arrows), endocrine cells grouped in Langerhans islets, and pancreatic ducts at 7 dph. Abbreviations: bd, bile duct; ct, connective tissue; cv, central vein; di, distal intestine; e, epithelium; en, endocrine pancreas (Langerhans islet); ex, exocrine pancreas; gb, gallbladder; gc, goblet cell; li, liver; lp, lamina propria containing connective tissue; mf, mucosal folds; mi, mid intestine; pa, pancreas; pc, pyloric caeca with simple, columnar epithelium and goblet cells; pd, pancreatic duct; pi, proximal intestine; pyb, pyloric caeca bud; re, rectum; snv, supranuclear vacuoles; st, stomach; u, urinary opening; vs, vitelline syncytium; y, yolk; ylm, yolk-like material; ys, yolk sac. Scale bar: (B-E) = 100 μm or (C, insert) = 50 μm; (F-Q) = 50 μm.</p

Mean body weight (g; left figure) and length (cm; right figure) of juvenile Atlantic salmon as a function of time (days post hatch) just before start-feeding at 46 days post hatch (indicated by vertical dotted line) and the period following start-feeding with the experimental diets (fishmeal or soybean meal diets).

<p>Values are means of n = 30–51 individual fish with standard error represented by vertical bars. See also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124179#pone.0124179.s001" target="_blank">S1 Table</a> for mean values and results of post-hoc one-way ANOVA with time as the main variable.</p

Development of the expression of gastric (<i>pep</i>) and pancreatic (<i>trp-ia</i>, <i>bal</i> and <i>amy</i>) digestive enzyme genes of juvenile Atlantic salmon as a function of time (days post hatch), differentiated by the pre-feeding period and the period following start-feeding (indicated by the vertical dotted line at 46 days post hatch) with the experimental diets (fishmeal or soybean meal diets).

<p>Values are mean fold change (log₁₀) as compared to the respective time point of first detection; n = 3 pooled samples of 3 individual fish per tank (three tanks per diet) with standard error represented by vertical bars. Abbreviations: <i>pep</i>, pepsinogen; <i>trp-ia</i>, trypsinogen 1a; <i>bal</i>, bile salt-activated lipase; <i>amy</i>, alpha-amylase. See also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124179#pone.0124179.s002" target="_blank">S2 Table</a> for mean values and results of post-hoc one-way ANOVA with time as the main variable.</p

Development of the expression of signaling peptide genes of juvenile Atlantic salmon as a function of time (days post hatch), differentiated by the pre-feeding period and the period following start-feeding (indicated by the vertical dotted line at 46 days post hatch) with the experimental diets (fishmeal or soybean meal diets).

<p>Values are mean fold change as compared to the respective time point of first detection; n = 3 pooled samples of 3 individual fish per tank (three tanks per diet) with standard error represented by vertical bars. Abbreviations: <i>ghrl</i>, ghrelin; <i>cck-I</i>, cholecystokinin L; <i>pyy</i>, peptide yy. See also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124179#pone.0124179.s002" target="_blank">S2 Table</a> for mean values and results of post-hoc one-way ANOVA with time as the main variable.</p