Regulation of chlorophyll apoprotein expression and accumulation. Requirements for carotenoids and chlorophyll.

Chlorophyll apoprotein accumulation and expression were examined in mutants of Chlamydomonas reinhardtii blocked at specific steps of carotenoid or chlorophyll synthesis. In the absence of carotenoids: 1) apoproteins of the core and light-harvesting complexes of photosystem I (CCI and LHCI, respectively) and photosystem II (CCII and LHCII, respectively) do not accumulate; 2) mRNAs for the CCI, CCII, and LHCII apoproteins accumulate to normal levels; and 3) synthesis of the chlorophyll apoproteins is differentially affected, or in some cases, not affected. In the absence of chlorophylls: 1) the apoproteins fail to accumulate; 2) mRNA levels for CCI and CCII apoproteins are relatively unchanged; 3) levels of LHCII apoprotein mRNA, but not rates of LHCII mRNA synthesis, are reduced in a light-dependent chlorophyll-synthesis mutant (ya12); and 4) synthesis of chlorophyll apoproteins is differentially affected or not affected in the case of several chloroplast-encoded apoproteins. These results demonstrate a direct role for carotenoids as well as chlorophylls in the stabilization of certain chlorophyll apoproteins and, for others, possibly in their translation. The data also indicate a role for chlorophyll synthesis in the stability of LHCII mRNA.     

Replacement value of hatchery waste meal for fish meal in layer diets

An experiment was conducted in which hatchery waste meal (HWM) replaced fish meal (protein for protein) in layer diets at 0%, 33%, 66% and 100% levels. Both feed and protein intake were superior on HWM diets. The highest hen-day production of 73.97% was obtained on diet 2 in which 33% of fish meal was replaced with HWM. Egg weight and egg length were also superior on HWM diets. All birds fed on HWM diets had thicker egg shells (0.33 mm) than did those fed on the control diet, fish meal diet (0.32 mm). Results obtained for yolk weight were statistically different (P < 0.05). Highest values for yolk weight (16.91 g) and albumen weight (40.93 g) were recorded for birds fed with diet 4 in which 100% fish meal was replaced with HWM. HWM can replace fish meal completely in layer diets without adverse effect on egg quality characteristics.     

Resource seasonality and fish diets in an Illinois stream

Synopsis The purpose of this study was to evaluate the intensity of competition for food among 9 species of stream fishes that primarily eat aquatic invertebrates. The taxonomic and size composition, and numerical abundance of aquatic invertebrates were monitored for one year using drift and benthic samples. Diet data were obtained from stomachs of fishes captured at the same time and place that invertebrate sampling was done. Diet characteristics examined included taxonomic and size composition, number of prey per fish, and diet breadth. Drifting invertebrates were more abundant early in the year (March–June) than later (July–January). The summer-early fall scarcity of invertebrates was especially notable among those>3.6 mm long, which comprised the bulk of prey found in fish stomachs. Average prey size eaten by a fish species was positively correlated with fish mouth size, but interspecific overlap in prey size was extensive. Cyprinids as a group (5 species) ate proportionally fewer small (< 3.6 mm long) prey from July to January than did the centrarchids and stonecat. Taxonomic compositions of available invertebrates and fish diets varied markedly among sampling dates, but the use of prey taxa by fishes was not correlated with the availability of those taxa. Use of aquatic prey taxa was generally similar among fish species, but cyprinids as a group ate proportionally more terrestrial prey from July to January than did the centrarchids and stonecat. Diet breadths for all species increased as food levels declined, indicating that these fishes experienced resource depression. Food scarcity was evidently more severe for cyprinids since their stomachs contained few prey through the summer and fall relative to the centrarchids and stonecat. Though the fish species studied probably compete for food in the summer and fall, this competition did not account for the community structure observed.     

Carotenoids in fish. XXII. Changes in carotenoids in Cyprinus carpio L.

The author investigated the presence of various carotenoids in the different parts of the body of Cyprinus carpio L. by means of columnar and thinlayer chromatography.The material in the form of the fertilized eggs, week-old fry, month-old fry, four-months old fry, one-year old fry and marketable carp were investigated.Yugoslavian carp brought to Poland as fry, and hybrid the wild carp crossed with of the cultivation carp, were also taken for analysis. The carotenoid content of Cyprinus carpio bred in waters polluted by municipal wastes and specimens suffering from diseases of the airbladder was also determined.The content of carotenoids, the provitamin of vitamin A, in Cyprinus carpio depends of many factors existing during the cultivation of these fish.     

Accuracy of the use of energy conversion factors for compound fish diets

Conversion factors of 23.6, 39.5 and 17.2 MJ/kg for protein, lipid and carbohydrate contents, respectively, are frequently used in fish studies to calculate the gross energy (GE) content of compound diets. Values predicted according to the above resulted in linear relationships of observed GE values with similar R ² and mean prediction error (MPE) values when using either nitrogen-free extract (NFE) (R ² = 0.5713, RMSE = 1.3134, MPE = 0.0741, n = 129, 32 studies) or starch (R ² = 0.5665, RMSE = 1.6768, MPE = 0.0839, n = 190, 45 studies) as measurements of carbohydrate content. Apparent digestible carbohydrate content (either NFE or starch) was found to be linearly-related (R ² values of 0.7531 and 0.7460, respectively) to its dietary content in compound fish diets. Predicted apparent digestible protein (ADP), lipid (DL) and carbohydrate contents, together with energy conversion factors, presented R ² and MPE values of 0.6205 (RMSE = 1.2606) and 0.2051, respectively, between observed and predicted apparent digestible energy (ADE) content with NFE as measurement of carbohydrate content (n = 97, 17 studies, eight fish species). However, with carbohydrates quantified by starch content, an R ² value of 0.7017 (RMSE = 1.7556) and MPE of 0.1055 were obtained (n = 37, 10 studies, five fish species).     

The biochemical composition of chyme in fish species with different diets

The chyme contents of the main biochemical components in fish with different diets vary. Proteins are dominant in the chyme of piscivorous fish (burbot and pike). In the chyme of benthivores (roach and bream), ash is the dominating component. Typical for all fish is the descending lipid gradients with maxima in the proximal section and the ascending ash gradients with maxima in the distal section. The maximum amount of protein was found in the medial part of the intestine. As a rule, there are higher contents of lipids in the chyme of the proximal section and proteins in the chyme of the medial section than in the whole body of fish prey.     

Determination of carotenoids and all-trans-retinol in fish eggs by liquid chromatography-electrospray ionization-tandem mass spectrometry

A novel method was developed for the combined determination of carotenoids and retinoids in fish eggs, which incorporates prior analyte isolation using liquid-liquid partitioning to minimize analyte degradation, and fraction analysis using high-performance liquid chromatography-electrospray (positive)-quadrupole mass spectrometry (LC-ESI(+)-MS; SIM or MRM modes). Eggs from Chinook salmon (Oncorhynchus tshawytscha) were used as the model fish egg matrix. The methodology was assessed and validated for beta-carotene, lutein, zeaxanthin, and beta-cryptoxanthin (molecular ion radicals [M](+)), canthaxanthin and astaxanthin ([M+Na](+) adducts) and all-trans-retinol ([(M+H)-H(2)O](+)). Using replicate egg samples (n=5) spiked with beta-cryptoxanthin and beta-carotene before and after extraction, matrix-sourced ESI(+) enhancement was observed as evidenced by comparable %matrix effect and %process efficiency values for beta-cryptoxanthin and beta-carotene of 114-119%. In aquaculture-raised eggs from adult Chinook salmon astaxanthin, all-trans-retinol, lutein and canthaxanthin were identified and determined at concentrations of 4.12, 1.06, 0.12 and 0.45 microg/g (egg wet weight), respectively. To our knowledge, this is the first report on a method for LC-MS determination of carotenoids and retinoids in a fish egg matrix, and the first carotenoid-specific determination in any fish egg sample.     

Vertebrate diets derived from trophically transmitted fish parasites in the Bothnian Bay

Parasites that are transmitted through predator–prey interactions may be used as indicators of trophic relationships between organisms. Yet, they are rarely used as such in the construction of topological (predator–prey) food webs. We constructed food webs of vertebrate trophic interactions using observed diet alone, trophically transmitted parasites alone, and the combination of the two based on data from 31 species of fish from the Bothnian Bay, Finland. The fish food web contained 530 links derived from observed diet, 724 links inferred from parasitism, and 1,058 links calculated from a combination of both stomach contents and parasites. This sub-web constructed from stomach contents had a mean of 17.1 links per fish species, while that using parasites had 23.4 links per fish. Combining the two diet indicators yielded 34.1 links per fish species, illustrating the complementarity of the two methods. Mean number of prey species per fish species was 12.5 using observed diet items, 15.8 using parasites, and 24.5 using both measures together. Mean number of predators per fish species was 7.4 using observed diet, 11.7 using parasites and 15.0 using both. A positive correlation was found between the mean number of parasites and the number of prey taxa in the diet among the fishes. Omnivorous fish had the highest diversity of both parasite species and prey items, while benthophagous fish had among the lowest. Mean total abundance and mean total prevalence of parasites correlated positively with fish size, with piscivores being the largest with the highest abundance and prevalence, while planktivores and benthivores had the lowest. Trophically transmitted parasites may be used to help construct vertebrate sub-webs and derive information about food web processes. Parasites alone provided equivalent if not more information than observed diet. However, resolution is improved by using parasites and observed diet together.     

Intestinal absorption of fish oil in rats previously adapted to diets containing fish oil or corn oil.

A study was conducted to evaluate whether the composition of previous dietary fat affects the absorption and composition of lymph obtained after a meal of fish oil. Adult male Sprague-Dawley rats were fed diets containing either corn oil or fish oil (MaxEPA) for 2 weeks. They were then given intraduodenally a bolus of an emulsion of 0.5 ml of fish oil plus 0.5 ml of 20 mM sodium taurocholate. Intestinal lymph was collected from a cannula in the main intestinal lymph trunk for various times after oil administration. Rats proportion of the test dose fo fish oil than those fed corn oil. There was an effect of previous diet on the fatty acid composition of the lymph. Rats fed fish oil had a higher percentage of eicosapentaenoic and docosahexaenoic acids in the lymph lipids than those fed corn oil while those fed corn oil had a higher percentage of linoleic acid. These results rule out decreased intestinal absorption as a mechanism for the hypotriacylglycerolemic effect of dietary fish oils. They also indicate a significant contribution of endogenous lipids to the fatty acids in lymph.     

Self-design of fish diets by means of self-feeders: validation of procedures

In this paper, we show the results from four different experiments in which sea bass, maintained under laboratory conditions, could choose between two or three different diets through self-feeders, which gradually increased the complexity and potential range of selection, to design their own diet in accordance with their requirements. At first, sea bass were allowed to select between two complete diets differing in the proportion of protein (52-58%): this showed their capacity to distinguish between two diets made of the same ingredients. Next, two incomplete diets, containing a fixed amount of protein (56%) and lacking either fat or carbohydrate, were made available. Three mixed diets made up of pairs of macronutrients (protein-carbohydrate, protein-fat or fat-carbohydrate) were tested in the next experiment and, finally, three diets containing only one macronutrient (protein fat or carbohydrate) were made available to fish. Taking into account selection made by the fish in the first three experiments, in which macronutrient selection was statistically different, protein was the main macronutrient chosen by fish (278.15 kJ/kgBW/day, on average), followed by fat and carbohydrate (162.85 and 64.56 kJ/kgBW/day, respectively). In conclusion, the results reveal the ability of sea bass to select an appropriate diet from experimental diets containing two or three macronutrients and suggest that the proposed methodology is a powerful tool for studying the differing nutritional needs of different species of fish.     

High-fat diets rich in soy or fish oil distinctly alter hypothalamic insulin signaling in rats

Hypothalamic insulin inhibits food intake, preventing obesity. High-fat feeding with polyunsaturated fats may be obesogenic, but their effect on insulin action has not been elucidated. The present study evaluated insulin hypophagia and hypothalamic signaling after central injection in rats fed either control diet (15% energy from fat) or high-fat diets (50% energy from fat) enriched with either soy or fish oil. Soy rats had increased fat pad weight and serum leptin with normal body weight, serum lipid profile and peripheral insulin sensitivity. Fish rats had decreased body and fat pad weight, low leptin and corticosterone levels, and improved serum lipid profile. A 20-mU dose of intracerebroventricular (ICV) insulin inhibited food intake in control and fish groups, but failed to do so in the soy group. Hypothalamic protein levels of IR, IRS-1, IRS-2, Akt, mTOR, p70S6K and AMPK were similar among groups. ICV insulin stimulated IR tyrosine phosphorylation in control (68%), soy (36%) and fish (34%) groups. Tyrosine phosphorylation of the pp185 band was significantly stimulated in control (78%) and soy (53%) rats, but not in fish rats. IRS-1 phosphorylation was stimulated only in control rats (94%). Akt serine phosphorylation was significantly stimulated only in control (90%) and fish (78%) rats. The results showed that, rather than the energy density, the fat type was a relevant aspect of high-fat feeding, since blockade of hypothalamic insulin signal transmission and insulin hypophagia was promoted only by the high-fat soy diet, while they were preserved in the rats fed with the high-fat fish diet.     

General methods for identification of carotenoids

General methods for identification of usual carotenoids including C₁₈-HPLC retention time and spectroscopic methods, such as absorption spectra, mass spectra, NMR spectra, are briefly summarized.     

Effects of selenium deficiency on fatty acid metabolism in rats fed fish oil-enriched diets.

The hepatic fatty acid metabolism was investigated in rats stressed by selenium deficiency and enhanced fish oil intake. Changes in the composition of lipids, peroxides, and fatty acids were studied in the liver of rats fed either a Sedeficient (8 microg Se/kg) or a Se-adequate (300 microg Se/kg) diet, both rich in n-3 fatty acid-containing fish oil (100 g/kg diet) and vitamin E (146 mg alpha-tocopherol/kg diet). The two diets were identical except for their Se content. Se deficiency led to a decrease in hair coat density and quality as well as to changes in liver lipids, individual lipid fractions and phospholipid fatty acid composition of the liver. The low Se status did reduce total and reduced glutathione in the liver but did not affect the hepatic malondialdehyde level. In liver phospholipids (PL), Se deficiency significantly reduced levels of palmitic acid [16:0], fatty acids of the n-3 series such as DHA [22:6 n-3], and other long-chain polyunsaturates C-20-C-22, but increased n-6 fatty acids such as linoleic acid (LA) [18:2 n-6]. Thus, the conversion of LA to arachidonic acid was reduced and the ratio of n-6/n-3 fatty acids was increased. As in liver PL, an increase in the n-6/n-3 ratio was also observed in the mucosal total fatty acids of the small intestine. These results suggest that in rats with adequate vitamin E and enhanced fish oil intake, Se deficiency affects the lipid concentration and fatty acid composition in the liver. The changes may be related to the decreased levels of selenoenzymes with antioxidative functions. Possible effects of Se on absorption, storage and desaturation of fatty acids were also discussed.     

Fungal carotenoids

The Botanical Review -     

Superlative carotenoids

A selection of carotenoids beyond normal appearance or properties has been presented at the 16(th) International Symposium on Carotenoids. Some of the exceptional compounds shown at the conference cannot be reproduced in this proceeding since they have not yet been published. In addition, editorial space limitation does not allow illustrating all of the previously mentioned carotenoids.     

Bacterial carotenoids

Zeaxanthin dirhamnoside is the major carotenoid of Corynebacterium autotrophicum. The absolute configuration 3R,3R followed from CD-properties of its hexaacetate, -L-assignment and ¹C₄ conformation were concluded from ¹H NMR data by comparison with model compounds.No. XLIX: Acta chem. scand. (in press)Dedicated to Professor R. Y. Stanier on his 60th birthday in appreciation of his studies on the function and biosynthesis of carotenoids and influence on the scientific development of his co-workers