Acute effects on perch (Perca fluviatilis) and long-term effects on whitefish (Coregonus lavaretus pallasi) of liming of an acidified lake

The acute effects on perch and long‐term effects on whitefish were studied after liming one side of a lake [initial pH: 4.6–5.5; aluminium (Al): 29–54 μg L^?1; Ca²⁺: 0.02–0.07 mmol L^?1] that was divided into two parts with a plastic curtain. Some Al precipitation was observed on the gill surface of perch 1 day after liming; the concentration of plasma sodium of perch females in the limed side was also higher than in the acidic side. Nearly 6 months after liming, at the spawning time of whitefish, the plasma chloride concentration of whitefish in the limed side was higher and blood glucose concentration lower than in the acidic side. Four of five whitefish males from the limed side, but only one of five males and none of the five females from the acidic side, were ready to spawn. The growth of whitefish in the limed side was also more rapid. These changes illustrate that liming had no acute harmful effects on perch, and allowed whitefish to recover from acidity‐related physiological stress.     

Dietary betaine accumulates in the liver and intestinal tissue and stabilizes the intestinal epithelial structure in healthy and coccidia-infected broiler chicks

The aim of this experiment was to study the patterns of betaine accumulation into intestinal tissue, liver and plasma of broiler chicks with or without coccidial infection. The chicks were raised on a corn-based, low-betaine diet with or without 1000 ppm betaine supplementation and with or without intestinal microparasite (Eimeria maxima) challenge to the age of 21 days. Plasma, liver, intestinal tissue and digesta of non-challenged (NC) birds and plasma and intestinal tissue of coccidiosis challenged (CC) birds were analysed for betaine content. NC birds were also analyzed for homocysteine in plasma and S-adenosylmethionine (S-AM) in liver. The jejunal epithelium was histologically examined for the presence of coccidia and the crypt-villus ratio was measured. Dietary betaine supplementation decreased the plasma homocysteine concentration but had no effect on liver S-AM of NC birds. The data suggest that chicks on a low-betaine diet accumulate betaine into the intestinal tissue. When the diet was supplemented with betaine, betaine accumulated heavily into liver and to a lesser degree into intestinal tissue. The concentration of betaine in jejunal and ileal digesta was low suggesting that dietary betaine was mainly absorbed from the proximal small intestine. The coccidial challenge decreased the concentration of betaine in the liver, but greatly increased that in the intestinal tissue. The crypt-villus ratio was decreased by the dietary betaine supplementation in healthy and challenged chicks, suggesting that dietary betaine both protects the jejunal villi against coccidial infection and also stabilizes the mucosal structure in healthy broiler chicks. These results support our earlier findings suggesting that betaine is likely to act as an important intestinal osmolyte in broiler chicks.     

Betaine aids in the osmoregulation of duodenal epithelium of broiler chicks, and affects the movement of water across the small intestinal epithelium in vitro.

In Experiment 1, the water holding capacity of broiler chick intestinal tissue was studied in vitro. The chicks were fed with corn-based diets with or without a 0.2% betaine supplementation in the drinking water. Slices from duodenum and jejunum were incubated in iso-osmotic (300 mM) or hyperosmotic saline (600 mM) with or without 10 mM betaine. The water volume of tissue slices was studied by adding tritiated water in the incubation medium while [14C]inulin was used to correct for the adherent water. After 30 min of incubation, by which time the steady-state of tritium influx had been achieved, the 3H and 14C-activities of the tissue slices were measured. The ileal and duodenal tissues incubated in the hyperosmotic saline accumulated less tritium than those incubated in iso-osmotic saline. Duodenal slices incubated in hyperosmotic saline with the presence of betaine showed a tritium content similar to slices incubated in iso-osmotic saline. The data suggest that the presence of betaine helped the duodenal, but not jejunal, epithelium to maintain water balance in hyperosmotic conditions. The dietary betaine supplementation diminished the differences between the incubation treatments in duodenal, but not in ileal tissue. In Experiment 2, the same double labeling method, but with shorter incubation times, was used to assess the rate of water flux from the incubation medium to duodenal or jejunal slices. The dietary treatments (as in Experiment 1) had little effect on the results. Betaine in the hyperosmotic saline significantly decreased the rate of tritium accumulation into the tissue slices, indicating that betaine slowed down the influx of water to the epithelium. We suggest that betaine affects the movement of water across the intestinal epithelium and has a role in the osmoregulation of small intestine of broiler chicks.     

Whitefish stocking in acidified lakes: ecological and physiological responses

In autumn 1986, six small lakes at different stages of acidification were stocked with one-summer-old whitefish, Coregonus pallasi Valenciennes 1848, in order to see whether whitefish stocking would be a suitable method for the mitigation of acidification effects. In two of the lakes the introduction was a complete failure: the whitefish did not survive, evidently due to high acidity and high aluminium concentrations of the lake waters. In one of the most acidified lakes (pH 4.3–4.8, Al_lab 29–125 g 1^–1) and in two less acidic lakes (pH 5.0–5.2 and 5.4–6.4), introduction was successful. Three years after the introduction, the mean weights of the fish in those three lakes were 580, 250 and 360 g respectively, with the weight and also the condition factor of stocked whitefish being highest in the most acidified lake. In that lake there were few or no fish present during the introduction, whereas in the less acid lakes there were dense populations of perch and therefore a potential interspecific competition for food. Different availability of food in the lakes was presumed to be the main reason for the growth differences. Plasma Na⁺ and Cl^– concentrations of whitefish were lower in the acidic lakes than in the lake with pH around 6 three years after stocking. This suggests that, despite the good growth and highest condition factor of whitefish in the most acid lake, the fish still experienced some acid stress.     

Intestinal uptake of betaine in vitro and the distribution of methyl groups from betaine, choline, and methionine in the body of broiler chicks

The efficiency of betaine absorption into small intestinal slices of broiler chicks was studied in vitro with 14C-labeled betaine. The relative proportion of Na+-coupled betaine uptake, as well as the total uptake capacity was larger in the duodenum than in the jejunum. Dietary betaine increased the Na+-coupled uptake in the duodenum. In in vivo-experiments, methyl-14C-labeled betaine, methionine, or choline was fed to broiler chicks. Betaine appeared in the blood more rapidly, and reached a higher total concentration than choline or methionine. The data suggest that choline and methionine were associated with plasma lipoproteins whereas betaine remained free in the plasma. The label distribution in liver, kidney, and intestinal tissues was studied 24 h after label ingestion. Most of the label from betaine was found in the aquaeous phase in the muscle, while in the liver and jejunum the label from betaine was distributed more evenly between the aquaeous, lipid, and protein phases. Label from choline accumulated in the lipid fraction, particularly so in the liver, whereas label from methionine showed a more variable distribution pattern. The distribution results are interpreted in terms of specific roles of betaine, choline, and methionine in methyl group metabolism.