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Mechanisms for the uptake and transport of carotenoids, essential nutrients for humans, are not well understood in any animal system. The Y (Yellow blood) gene, a critical cocoon color determinant in the silkworm Bombyx mori, controls the uptake of carotenoids into the intestinal mucosa and the silk gland. Here we provide evidence that the Y gene corresponds to the intracellular carotenoid-binding protein (CBP) gene. In the Y recessive strain, the absence of an exon, likely due to an incorrect mRNA splicing caused by a transposon-associated genomic deletion, generates a nonfunctional CBP mRNA, resulting in colorless hemolymph and white cocoons. Enhancement of carotenoid uptake and coloration of the white cocoon was achieved by germ-line transformation with the CBP gene. This study demonstrates the existence of a genetically facilitated intracellular process beyond passive diffusion for carotenoid uptake in the animal phyla, and paves the way for modulating silk color and lipid content through genetic engineering. carotenoid transport | cocoon color | transgenic silkworm

The effects of the dual action of testosterone and the competition for carotenoids on the allocation tradeoffs with the immune system that signals honesty in the sexual relationships are studied. The analysis clearly indicates that the testosterone treatment upregulates the circulating lipoproteins, in addition to an increase in the bio-availability of carotenoids, which enhances the sexual coloration.

Androgens and carotenoids play a fundamental role in the expression of secondary sex traits in animals that communicate information on individual quality. In birds, androgens regulate song, aggression, and a variety of sexual ornaments and displays, whereas carotenoids are responsible for the red, yellow, and orange colors of the integument. Parallel, but independent, research lines suggest that the evolutionary stability of each signaling system stems from tradeoffs with immune function: androgens can be immunosuppressive, and carotenoids diverted to coloration prevent their use as immunostimulants. Despite strong similarities in the patterns of sex, age and seasonal variation, social function, and proximate control, there has been little success at integrating potential links between the two signaling systems. These parallel patterns led us to hypothesize that testosterone increases the bioavailability of circulating carotenoids. To test this hypothesis, we manipulated testosterone levels of red-legged partridges Alectoris rufa while monitoring carotenoids, color, and immune function. Testosterone treatment increased the concentration of carotenoids in plasma and liver by >20%. Plasma carotenoids were in turn responsible for individual differences in coloration and immune response. Our results provide experimental evidence for a link between testosterone levels and immunoenhancing carotenoids that (i) reconciles conflicting evidence for the immunosuppressive nature of androgens, (ii) provides physiological grounds for a connection between two of the main signaling systems in animals, (iii) explains how these signaling systems can be evolutionary stable and honest, and (iv) may explain the high prevalence of sexual dimorphism in carotenoid-based coloration in animals. honest signaling | immune function | immunocompetence handicap hypothesis | coloration

A novel approach for carotenoid analysis has been developed. Orange essential oil and juice carotenoids were separated by means of comprehensive dual-gradient elution HPLC, using normal phase with a microbore silica column in the first dimension (first D), reversed phase with a monolithic C 18 column in the second dimension (second D), and a 10-port switching valve as an interface. An on-line photodiode array detector was used in order to obtain absorption spectra. Peak identification was obtained by combining retention data with the UN-visible spectra.

Carotenoids are important photoprotectant and light-harvesting pigments within the photosynthetic apparatus. Little information is available regarding carotenoid physiology in creeping bentgrass (Agrostis stolonifera L.). Research was conducted to investigate relative high and low irradiance adaptation of creeping bentgrass with respect to [beta]carotene and xanthophyll composition. 'Crenshaw' creeping bentgrass plants were acclimated for 7 d to relative high [47.9 mol [m.sup.-2] [d.sup.-1] photosynthetically active radation (PAR)] or low irradiance (4.7 mol [m.sup.-2] [d.sup.-1] PAR). After the acclimation period, plants were transferred from high to low (low irradiance treatment) and low to high (high irradiance treatment) irradiance. Clippings were harvested at 0, 24, 72, and 168 h after the acclimation period. Zeaxanthin and antheraxanthin decreased from 5.1 and 3.4 to 0.9 and 0.6 mg 100 [g.sup.-1] fresh weight (FW), respectively, over 168 h in low irradiance. As the turf adapted to low irradiance, violaxanthin, lutein, and lutein-5,6-epoxide (epoxylutein) increased at 24 h, but levels decreased from 24 to 168 h. Zeaxanthin and antheraxanthin increased in high irradiance, while violaxanthin and [beta]-carotene decreased. Lutein was the predominant carotenoid quantified regardless of irradiance treatment. Cumulative zeaxanthin, antheraxanthin, and violaxanthin increased as a percentage of the total carotenoids as the turfgrass adapted to high irradiance, but decreased in low irradiance. Conversely, neoxanthin and [beta]-carotene decreased in high irradiance and increased in low irradiance. Creeping bentgrass produces carotenoid amounts comparable to other plant species potentially attributable to selection efforts of more stress-tolerant varieties.

There is widespread interest in the roles that carotenoids play as yolk and shank pigments, antioxidants, and immune-system regulators in chickens, but nothing is known of such functions in the wild ancestors of chickens--the Red Junglefowl (Gallus gallus). We manipulated carotenoid access in the diet of captive male and female Red Junglefowl to investigate its effects on the coloration of the red comb and buff-brown legs and beak as well as on several indices of immunocompetence. Comb, leg, and beak did not differ in coloration between control and carotenoid-supplemented groups; in fact, biochemical analyses showed that, unlike in chickens, leg and beak tissue contained no carotenoids. Carotenoids showed variable effects on immunological performance, boosting the potency of whole blood in males to kill bacterial colonies, while inhibiting the ability of macrophages to phagocytize bacterial cells and having no significant effect on the accumulation of haptoglobin--an acute-phase protein whose production was induced by a simulated infectious challenge with lipopolysaccharide. These results bring into question interpretations of the evolutionary significance of carotenoid-based and sexually dichromatic shank coloration in domestic chickens, which was apparently derived through artificial selection, and suggest that carotenoids can exert different, mechanism-specific actions on the many lines of immune defense in birds. Key words: carotenoid pigmentation, chickens, diet, Gallus gallus, immunocompetence, Red Junglefowl, sexual selection. Existe un amplio interes en el papel que tienen los carotenoides como pigmentos de la yema y parte inferior de las patas, asi como tambien en antioxidantes y reguladores del sistema inmunologico en gallinas, pero nada se sabe sobre estas funciones en el ancestro silvestre de las gallinas, Gallus gallus. Manipulamos el acceso a carotenoides en la dieta de machos y hembras en cautiverio de G. gallus para investigar los efectos sobre la coloracion roja de la cresta y coloracion cafe de las patas y el pico, como asi tambien en varios indices de inmuno-competencia. La cresta, las patas y el pico no difirieron en coloracion entre el grupo control y el suplementado con carotenoides. De hecho, los analisis bioquimicos mostraron que, contrariamente a lo observado en las gallinas, los tejidos de las patas y el pico no contienen carotenoides. Los carotenoides mostraron efectos variados sobre el desempeno inmunologico. En los machos, impulsaron el potencial del tejido sanguineo para matar colonias bacterianas, mientras que inhibieron la habilidad de los macrofagos de fagocitar celulas bacterianas y no tuvieron un efecto significativo sobre la acumulacion de haptoglobina--una proteina de fase aguda cuya produccion fue inducida por una infeccion simulada con lipo-polisacaridos. Estos resultados cuestionan las interpretaciones del significado evolutivo de la coloracion con carotenoides y de la coloracion di-cromatica sexual de la parte inferior de las patas en gallinas domesticas, la cual aparentemente derivo a partir de seleccion artificial y sugiere que los carotenoides pueden ejercer acciones mecanicas especificas y diferentes sobre las variadas lineas de defensa inmunologica en aves.

Great apes are the closest living relatives of humans. Physiological similarities between great apes and humans provide clues to identify which biological features in humans are primitive or derived from great apes. Vitamin A (VA) and carotenoid metabolism have been only partially studied in great apes, and comparisons between great apes and humans are not available. We aimed to investigate VA and carotenoid intake and plasma concentrations in great apes living in captivity, and to compare them to healthy humans. Dietary intakes of humans (n = 20) and, among the great apes, chimpanzees (n = 15) and orangutans (n = 5) were calculated. Plasma retinol (ROH), retinol-binding protein (RBP), retinyl esters, and major carotenoids were analyzed. The great ape diet was higher in VA than in humans, due to high intake of provitamin A carotenoids. Plasma ROH concentrations in great apes were similar to those in humans, but retinyl esters were higher in great apes than in humans. Differences in plasma carotenoid concentrations were observed between great apes and humans. Lutein was the main carotenoid in great apes, while [beta]-carotene was the main carotenoid for humans. RBP concentrations did not differ between great apes and humans. The molar ratio of ROH to RBP was close to 1.0 in both great apes and humans. In conclusion, great apes show homeostatic ROH regulation, with high but physiological retinyl esters circulating in plasma. Furthermore, great apes show great selectivity in their plasmatic carotenoid concentration, which is not explained by dietary intake. KEY WORDS vitamin A; diet; retinol-binding protein; chimpanzee; orangutan

The green sulfur bacterium Chlorobium tepidum produces chlorobactene as its primary carotenoid. Small amounts of chlorobactene are hydroxylated by the enzyme CrtC and then glucosylated and acylated to produce chlorobactene glucoside laurate. The genes encoding the enzymes responsible for these modifications of chlorobactene, CT1987, and CT0967, have been identified by comparative genomics, and these genes were insertionally inactivated in C. tepidum to verify their predicted function. The gene encoding chlorobactene glucosyltransferase (CT1987) has been named cruC, and the gene encoding chlorobactene lauroyltransferase (CT0967) has been named cruD. Homologs of these genes are found in the genomes of all sequenced green sulfur bacteria and filamentous anoxygenic phototrophs as well as in the genomes of several nonphotosynthetic bacteria that produce similarly modified carotenoids. The other bacteria in which these genes are found are not closely related to green sulfur bacteria or to one another. This suggests that the ability to synthesize modified carotenoids has been a frequently transferred trait.

To be able to survive, marine macroalgae in shallow coastal waters need mechanisms for short-term acclimation to fast changes in their environment. Of major importance are mechanisms that regulate the efficiency of photosynthesis by protecting PS II from photo-oxidative damage. Carotenoids, xanthophyll cycles and non-photochemical quenching (NPQ) are central constituents of such protection mechanisms. Red algae as a group do not have a universal carotenoid composition. We screened ten red algal species and selected two species, originating from similar ecological conditions but with different carotenoid compositions, for use in irradiance-acclimation experiments. We selected the tropical intertidal species Gracilaria domingensis and Kappaphycus alvarezii with antheraxanthin and lutein as major xanthophylls, respectively. Simultaneous in vivo fluorescence and [O.sub.2] evolution experiments were performed at different irradiance levels, which allowed a direct comparison of overall photosynthetic performance with NPQ. Interconversions of xanthophylls (violaxanthin, zeaxanthin, [beta]-cryptoxanthin and one unidentified carotenoid) did occur in G. domingensis, but not in response to sudden exposure to light. Thus, NPQ was not correlated with any xanthophyll cycle during short-term acclimation to light. G. domingensis had five times higher weight-specific photosynthetic rates than K. alvarezii, which can be explained by the thicker thallus of K. alvarezii. Chlorophyll-specific gross photosynthetic rates were higher in K. alvarezii, but net rates were the same for both species. G. domingensis showed an immediate strong onset of NPQ upon exposure to irradiance, followed by down-regulation to the NPQ level required. In K. alvarezii NPQ increased slowly until the required NPQ level was reached. At high irradiance G. domingensis downregulated photosynthesis while K. alvarezii continued to produce [O.sub.2] even at 2,000 [micro]mol photons [m.sup.-2] [s.sup.-1] without NPQ increase. The strategy of K. alvarezii may provide short-term gains but with the risk of oxidative damage. The fast onset of NPQ in G. domingensis even at subsaturating irradiance as well as down-regulation of photosynthesis when NPQ is saturated might provide this species with a competitive advantage under conditions of changing irradiance in the field., Introduction Many marine macroalgae grow in shallow waters of coastal areas where environmental changes can occur fast. Especially intertidal algae are exposed to stress factors such as changes in irradiance, [...]

Lutein, a dihydroxycarotenoid, has antioxidant and immunomodulatory potential. Two 2 x 2 x 2 factorial designs examined effects of carotenoids during in ovo embryogenesis and, in the diet posthatch, on the systemic inflammatory response to lipopolysaccharide (LPS). In both trials, breeder hens were fed a carotenoidreplete (40 mg lutein/kg) or a carotenoid-deplete diet, eggs were collected, and chicks were hatched from carotenoiddeplete or carotenoid-replete eggs. Meat-type chicks (n = 160 and n = 144, respectively) were then fed diets containing 0 or 40 mg lutein/kg diet and either injected or not injected with LPS. LPS injection increased plasma haptoglobin and Zn (P < 0.01) and reduced plasma Fe and Cu (P < 0.01). Chicks hatched from carotenoid-deplete eggs had greater changes in plasma Fe and S post-LPS than chicks hatched from carotenoid-replete eggs (P < 0.05 for each). Compared with chicks fed 40 mg lutein/kg diet, chicks fed 0 mg lutein had greater body weight losses and higher plasma haptoglobin and relative thymus, bursa, and spleen weights post-LPS (P < 0.05). Data suggest that a lack of carotenoid exposure, either in ovo or posthatch, increases parameters of systemic inflammation. KEY WORDS: * carotenoid * lutein * egg yolk * inflammation

Carotenoids are biologically active pigments of crucial importance for the development of avian embryos and nestlings. Thus parental ability to provide nestlings with a carotenoid-rich diet may enhance offspring fitness. However, very little is known about the possible effects of carotenoid availability in the diet on growing nestlings in natural populations. We experimentally manipulated dietary intake of carotenoids by nestlings of two closely related passerine species, the great tit Parus major and the blue tit Parus caeruleus, and measured nestling antioxidants, body condition, immunity and plumage colour. There was no detectable increase in plasma carotenoids after treatment in carotenoid-fed nestlings of either species despite regular supply of dietary carotenoids. However, in carotenoid-fed blue tit nestlings, plasma vitamin E concentration increased with plasma carotenoid concentration, while that was not the case for control nestlings. In both species, there was no significant effect of carotenoid supply on immune function. Carotenoid supplementation enhanced yellow feather colour in great tit nestlings only. In both species a strong effect of carotenoid supply was found on body condition with an increase in body mass for small carotenoid-fed nestlings compared to similarly sized control nestlings. Dietary availability of carotenoids may thus have important fitness consequences for tits. We hypothesise that the difference in effect of dietary carotenoids on the two species is due to relatively larger clutch size and higher growth rates of blue tits compared to great tits, leading to blue tit nestlings being more in need of carotenoids for antioxidant function than great tit nestlings. Key words: antioxidants, early development, feather colour, fledgling body mass. immune function.

The influence of thermal treatment (frying of plantain) on the micronutrients ascorbic acid, potassium and carotenoids is evaluated. Cylinders (diameter 30 mm, thickness 10 mm) of plantain (Musa AAB 'barraganete') were fried at four thermal treatments (120-180[degrees]C and from 24 to 4 min) to obtain products with approximately the same water content ([approximately equal to] 0.8 [+ or -]0.02 kg/[kg.sup.1]) and fat content ([approximately equal to] 0.15 [+ or -]0.06 kg/kg). The thermal study used the cook value and the mean cook value as indicators of the effect of several different treatment temperatures and times on quality. Deep-fat frying had no significant effect on carotenoid contents at any frying conditions, and on potassium content, except at 120[degrees] C and 24 min (loss [less than or equal to] 11%). There was a significant, but not complete, loss ([less than or equal to] 45%) of ascorbic acid. The process with the greatest effect was low temperature and long time (120[degrees] C/24 min), as observed for potassium and ascorbic acid. These results are in agreement with other studies that demonstrated short thermal treatments at high temperatures protect food nutritional quality, as shown by the cook value and the mean cook value. In our work, deep-fat frying of plantain preserved most of the micronutrient contents that were evaluated. Keywords: Deep-fat frying, ascorbic acid, carotenoids, potassium, plantain

The vitamin A (VA) value of carotenoids from fruits and vegetables is affected by many factors. This study determined the VA value of [alpha]-carotene isolated from carrots compared with [beta]-carotene and retinyl acetate supplements fed to Mongolian gerbils (Meriones unguiculatus). Gerbils (n = 38) were fed a VA-free diet for 4 wk. At baseline, 6 gerbils were killed to determine liver VA. Gerbils were divided into 3 treatment groups (n = 9/group) and given 35, 35, or 17.5 nmol retinyl acetate, [alpha]-carotene or [beta]-carotene, respectively, in 2 divided doses 5 h apart each day. The remaining 5 gerbils received oil vehicle. Gerbils were killed after 3 wk of supplementation. Serum samples and livers were collected and analyzed for VA. Liver extracts were subsequently saponified to quantify [alpha]-retinol. Serum retinol concentrations did not differ among the groups. Liver retinyl palmitate concentrations were significantly higher in the retinyl acetate treatment group (0.198 [+ or -] 0.051 [micro]mol/g; P < 0.05) than in all other groups. The [alpha]- and [beta]-carotene treatments resulted in similar retinyl palmitate concentrations, i.e., 0.110 [+ or -] 0.026 and 0.109 [+ or -] 0.051 [micro]mol/g, respectively, which did not differ from the concentrations in gerbils killed at baseline (0.123 [+ or -] 0.024 [micro]mol/g). The oil group had significantly less retinyl palmitate (0.061 [+ or -] 0.029 [micro]mol/g; P < 0.05) than all other groups, [alpha]-Retinol was detected in livers of the [alpha]-carotene group (0.062 [+ or -] 0.013 [micro]mol/g). Thus, twice the amount of purified [alpha]-carotene maintained VA status as well as [beta]-carotene in VA-depleted gerbils. Conversion factors were ~5.5 [micro]g [alpha]-carotene or ~2.8 [micro]g [beta]-carotene to 1 [micro]g retinol. KEY WORDS: * [alpha]-retinol * carotenoids * conversion factors * Mongolian gerbils * retinol * vitamin A

Data suggest that intestinal carotenoid absorption is a facilitated process. The present study was conducted to determine whether carotenoids and cholesterol share common pathways (transporters) for their intestinal absorption. Differentiated Caco-2 cells on membranes were incubated (16 h) with a carotenoid (1 [micro]mol/L) with or without ezetimibe (EZ; Zetia[R], an inhibitor of cholesterol transport), and with or without antibodies against the receptors, cluster determinant 36 (CD36) and scavenger receptor class B, type I (SR-BI). Carotenoid transport in Caco-2 cells (cellular uptake + secretion) was decreased by EZ (10 mg/L) as follows: [beta]-carotene [approximately equal to] [alpha]-carotene (50% inhibition) [much greater than] [beta]-cryptoxanthin [approximately equal to] lycopene (20%) [much greter than] lutein:zeaxanthin (1:1) (7%). EZ reduced cholesterol transport by 31%, but not retinol transport. [beta]-Carotene transport was also inhibited by anti-SR-BI, but not by anti-CD36. The inhibitory effects of EZ and anti-SR-BI on/3-carotene transport were additive, indicating that they may have different targets. Finally, differentiated Caco-2 cells treated with EZ showed a significant decrease in mRNA expression for the surface receptors SR-BI, Niemann-Pick type C1 Like 1 protein (NPC1L1), and ATP-binding cassette transporter, subfamily A (ABCA1) and for the nuclear receptors retinoid acid receptor (RAR)[gamma], sterol-regulatory element binding proteins (SREBP)-1 and -2, and liver X receptor (LXR)[beta] as assessed by real-time PCR analysis. The data indicate that 1) EZ is an inhibitor of carotenoid transport, an effect that decreases with increasing polarity of the carotenoid molecule, 2) SR-BI is involved in carotenoid transport, and 3) EZ may act, not only by interacting physically with cholesterol transporters as previously suggested, but also by downregulating expression of these proteins. The cellular uptake and efflux of carotenoids, like that of cholesterol, likely involve more than one transporter. KEY WORDS: * carotenoids * intestinal absorption * ezetimibe * facifitated transport * Caco-2 cells

Antioxidants, particularly carotenoids and tocopherols, may protect against cardiovascular disease. The objective of this study was to determine whether dietary and adipose tissue carotenoids and tocopherols are associated with the risk of myocardial infarction (MI). Cases (n = 1456) of a first acute MI were identified and matched by age, sex, and residence to randomly selected population controls (n - 1456) living in Costa Rica. Carotenoids and tocopherols were measured in adipose tissue using HPLC. Dietary intake was assessed using a validated FFQ. Anthropometrical and lifestyle data were collected using an interviewer-administered questionnaire. Subjects were distributed into quintiles of intake or adipose tissue concentration of carotenoids or tocopherols. The lowest quintile was used as the referent in conditional logistic regression analyses. Adipose tissue [beta]-carotene showed a significant inverse relation with MI risk; the odds ratio (OR) comparing the highest to the lowest quintile was 0.70 (95% CI: 0.51-0.96, P for trend - 0.02). Intake of fruits and vegetables that are rich in [beta]-carotene was also inversely associated with the risk of MI (OR - 0.74; CI: 0.54-1.01, P for trend - 0.09). In contrast, lutein + zeaxanthin in adipose tissue (OR = 1.46; CI: 1.05-2.05, P for trend = 0.02) and diet (OR = 1.18; CI: 0.88-1.57, P for trend = 0.02) was positively associated with MI risk. MI risk was not associated with any of the other carotenoids or tocopherols in the diet or adipose tissue. Thus, the inverse association between/3-carotene and MI risk suggests that/3-carotene protects against MI or it is a marker of some protective factor in foods containing [beta]-carotene. The mechanism underlying the positive association between lutein + zeaxanthin and the risk of MI warrants investigation. KEY WORDS: * biomarkers * antioxidants * carotenoids * tocopherols * myocardial infarction * cardiovascular disease

Identification of a novel gene (CrtNb) involved in conversion of 4,4'-diapolycopene to 4,4'-diapolycopene aldehyde is reported. However, data from crtNb and expression of crtNb in Escherichia coli indicated that crtNb is a novel carotenoid oxidase catalyzing oxidation of the terminal methyl group(s) of 4,4'-diaponeurosporene and 4,4'-diapolycopene to the corresponding terminal aldehyde.

Carotenoids have been linked with protective roles against diseases associated with aging, including cancer, cardiovascular disease, cataracts, and age-related macular degeneration. With data from a semiquantitative, validated FFQ, we examined carotenoid intake of 340 Puerto Ricans, 98 Dominicans, and 146 non-Hispanic whites (>60 y old) in Massachusetts. Compared with non-Hispanic white men, Hispanic men reported a higher intake of lycopene and lower intakes of [alpha]-carotene, lutein + zeaxanthin, [beta]-carotene (from diet only), and total [beta]-carotene (diet and supplements) (P < 0.001). Hispanic women reported higher intakes of [beta]-cryptoxanthin and lycopene but lower intakes of lutein + zeaxanthin (P < 0.001) than non-Hispanic white women. The frequency of consumption of fruit and vegetables was higher among Hispanic women, relative to non-Hispanic white women (P < 0.05). Plasma concentrations of s-carotene and lycopene were higher in Hispanic than in non-Hispanic white men and women. For both ethnic groups, higher intakes of carotenoids were associated with higher plasma concentrations of the respective carotenoids, except for lycopene (Hispanics) and lutein + zeaxanthin (non-Hispanic whites). Food sources contributing most to total intakes differed among the groups. The major sources of [alpha]- and [beta]-carotene were carrots for non-Hispanic whites and winter squash for Hispanics. The major source of lycopene was cooked tomato products for Hispanics, and pasta dishes for non-Hispanic whites. Traditional foods such as beans and plantains were also important contributors of carotenoids for Hispanics. Because of the potential importance of carotenoids as protective factors against chronic diseases, more attention to food-related practices associated with carotenoid intake in differing population groups is warranted. KEY WORDS: * carotenoids * elderly * Hispanic * Puerto Rican * Dominican

The objective of this study was to determine whether vitamin supplementation during long-term (36 wk) ingestion of olestra supplemented with vitamin E could prevent decreases in vitamin E, vitamin A, and carotenoids. This was a 36-wk study of 37 healthy males randomly assigned to consume a control diet composed of 33% energy from fat, a similar diet in which one third of the energy from fat had been replaced with olestra, or a fat-reduced (25% of energy from fat) diet. Subjects also ingested a daily multivitamin (Centrum[TM]). Serum concentrations of [alpha]-tocopherol, retinol, [beta]-carotene, lycopene, and lutein + zeaxanthin were analyzed by HPLC. Subjects eating the olestra-containing diet had substantial decreases in serum [beta]-carotene, lycopene, and lutein + zeaxanthin, which occurred by 12 wk; these changes were found despite correcting for serum total cholesterol or BMI. Serum [beta]-carotene and lycopene concentrations were below the lower limit of the reference range ( KEY WORDS: * olestra * vitamin E * vitamin A * carotenoids * fat substitute

Researchers have mixed, matched, and mutated carotenoid biosynthetic enzymes and screened libraries of thee evolved pathways for the emergence of new carotenoid products. The strategies and specific methods that are employed to generate new carotenoid biosynthetic pathways in the laboratory are discussed.

Dietary lipids are hypothesized to be an important factor for carotenoid bioavailability. However, most carotenoid-rich fruits and vegetables are low in lipids. The objective of this study was to assess whether the addition of avocado fruit as a lipid source enhances carotenoid absorption in humans. Healthy subjects (n = 11/ study) were recruited for 2 crossover, postprandial studies. The effect of avocado addition (150 g) to salsa on lycopene and [beta]-carotene absorption was examined in Study 1, and the absorption of lutein, [alpha]-carotene, and [beta]-carotene from salad in Study 2. Furthermore, the effects of avocado dose (75 vs. 150 g containing 12 vs. 24 g lipid, respectively) and of lipid source (avocado fruit vs. avocado oil) on carotenoid absorption were examined in Study 2. Intact carotenoids were quantified in the plasma triacylglycerol-rich lipoprotein (TRL) fraction during the 9.5 h after consumption of the test meal and expressed as baseline-corrected area under the concentration-vs.-time curve (AUC). The addition of avocado to salsa enhanced lycopene and [beta]-carotene absorption (P < 0.003), resulting in 4.4 and 2.6 times the mean AUC after intake of avocado-free salsa, respectively. In Study 2, supplementing 150 g avocado or 24 g avocado oil to salad similarly enhanced [alpha]-carotene, [beta]-carotene, and lutein absorption (P < 0.01), resulting in 7.2, 15.3, and 5.1 times the mean AUC after intake of avocado-free salad, respectively (150 g avocado). Neither the avocado dose nor the lipid source affected carotenoid absorption. In conclusion, adding avocado fruit can significantly enhance carotenoid absorption from salad and salsa, which is attributed primarily to the lipids present in avocado. 2005. KEY WORDS: * carotenoids * avocados * postprandial absorption * triacyglycerol-rich lipoproteins * humans

We experimentally tested the hypothesis that accumulations of dietary compounds such as carotenoids or UV-absorbing mycosporine-like amino acids (MAAs) protect against natural levels of ultraviolet radiation (UVR). A calanoid copepod, Leptodiaptomus minutus, was collected from a relatively UV-transparent lake in Pennsylvania where levels of copepod MAAs and carotenoids vary during the year (MAAs high/carotenoids low in summer). Animals raised in the laboratory under different diet/UVR treatments accumulated MAAs from an MAA-producing dinoflagellate but not from a cryptomonad that lacks them. The acquisition efficiency increased under exposure to UVR-supplemented photosynthetically active radiation (PAR, 400-700 nm), yielding MAA concentrations up to 0.7% dry weight compared with only 0.3% under unsupplemented PAR. Proportions of individual MAAs differed between the animals and their diet. Shorter wavelength absorbing palythine and shinorine ([[lambda].sub.max] 320 and 334 nm, respectively) were disproportionately accumulated over usujirene and palythene ([[lambda].sub.max] ca. 359 nm). Carotenoids accumulated under UVR exposure (to 1% dry weight) when dietary MAAs were not available. Tolerance of ultraviolet-B (UV-B) radiation was assessed as L[E.sub.50]s (UV exposure giving 50% mortality after 5 d) following 12-h acute exposure to artificial UV-B radiation. L[E.sub.50]s increased 2.5-fold for UV-acclimated, MAA-rich animals, but only 1.5-fold for UV-acclimated, carotenoid-rich animals. Compared with carotenoids, MAAs offer this copepod a more effective photoprotection strategy, potentially as important as photorepair of DNA damage, to promote tolerance of natural levels of UV-B radiation.

Carotenoids are produced by a variety of organisms, but the mechanisms that regulate gene expression leading to carotenoid biosynthesis have been characterized for only a few organisms. In this study, we found that Streptomyces coelicolor A3(2), a gram-positive filamentous bacterium, produces carotenoids under blue light induction. The carotenoid fraction isolated from the cell extract contained multiple compounds, including isorenieratene and [beta]-carotene. The carotenoid biosynthesis gene cluster of S. coelicolor consists of two convergent operons, crtEIBV and crtYTU, as previously shown for Streptomyces griseus. The crtEIBV null mutant completely lost its ability to produce carotenoids. The crt gene cluster is flanked by a regulatory region that consists of two divergent operons, litRQ and litSAB. The lit (light-induced transcription) genes encode a MerR-type transcriptional regulator (LitR), a possible oxidoreductase (LitQ), an extracytoplasmic function sigma factor ([[sigma].sup.LitS]), a putative lipoprotein (LitA), and a putative anti-sigma factor (LitB). S1 protection assay revealed that the promoters preceding crtE (PcrtE), crtY (PcrtY), litR (PlitR), and litS (PlitS) are activated upon illumination. A litS mutant lost both the ability to produce carotenoids and the activities of PcrtE, PcrtY, and PlitS, which suggested that [[sigma].sup.LitS] directs light-induced transcription from these promoters. An RNA polymerase holocomplex containing purified [[sigma].sup.LitS] recombinant protein generated specific PcrtE and PcrtY transcripts in an in vitro runoff transcriptional assay. A litR mutant that had an insertion of the kanamycin resistance gene was defective both in the ability to produce carotenoids and in all of the light-dependent promoter activities. Overexpression of litS resulted in constitutive carotenoid production in both the wild type and the litR mutant. These results indicate that [[sigma].sup.LitS] acts as a light-induced sigma factor that directs transcription of the crt biosynthesis gene cluster, whose activity is controlled by an unknown LitR function. This is the first report to describe light-inducible gene expression in Streptomyces.

Of the many carotenoids circulating in human sera, only lutein and zeaxanthin are accumulated throughout the tissues of the eye. Within the eye, they reach their highest concentration in the central retina, where they are clinically referred to as the macula lutea. Lutein and zeaxanthin, more commonly referred to as macular pigments, may serve a variety of roles in the specialized vision of higher primates. This paper reviews recent studies investigating the influence of macular pigments on human visual performance. Such studies have offered insight into why lutein and zeaxanthin are uniquely concentrated in ocular tissues. Key words: carotenoid, lutein, macula, macular degeneration, zeaxanthin