饵料蛋白质水平对德国小蠊营养效应及氮代谢的影响

【目的】本研究旨在探究饵料蛋白质水平对德国小蠊Blattella germanica营养利用及氮代谢的影响,为蟑螂毒饵的研发提供新思路。【方法】采用标准重量分析法评估了取食4种不同蛋白质水平(5%, 25%, 45%和65%)饵料的德国小蠊雄成虫营养效率指数和氮利用率;利用分光光度法测定了取食不同蛋白水平饵料的德国小蠊雄成虫体内黄嘌呤氧化酶(xanthine oxidase, XOD)、谷草转氨酶(glutamic oxaloacetic transaminase, GOT)、谷丙转氨酶(glutamic pyruvic transaminase, GPT)活性及尿酸含量。【结果】取食65%蛋白质饵料组的德国小蠊雄成虫的相对取食量最高,而取食45%蛋白质饵料组的雄成虫食物利用率、食物转化率及相对生长率均显著高于取食5%和65%蛋白质饵料组的雄成虫。且德国小蠊雄成虫体内氮、粪便氮、氮消耗速率、氮排泄率、氮生成率、氮同化效率、黄嘌呤氧化酶活性和尿酸含量均随饵料蛋白质水平的提高而提高,但65%蛋白质饵料组氮利用率最低,45%蛋白质饵料组谷草转氨酶活性最高,25%和45%蛋白质饵料组谷丙转氨酶活性显著高于5%和65%蛋白质饵料组。【结论】适量蛋白质饵料有利于德国小蠊对食物及氮的利用,而高蛋白质含量条件下德国小蠊谷草转氨酶和谷丙转氨酶活性下降,说明高蛋白不利于德国小蠊利用食物,且增加其代谢负担。     

Nutritional quality of gorilla diets: consequences of age,sex, and season

We tested the effects of age, sex, and season on the nutritional strategies of a group of mountain gorillas (Gorilla beringei) in the Bwindi Impenetrable National Park, Uganda. Through observations of food intake of individual gorillas and nutritional analyses of dietary components over different seasons and environments, we estimated nutrient intake and evaluated diet adequacy. Our results suggest that the nutritional costs of reproduction and growth affect nutrient intake; growing juveniles and adult females ate more food and more protein per kilogram of metabolic body mass than did silverbacks. The diets of silverback males, adult females, and juveniles contained similar concentrations of protein, fiber, and sugar, indicating that adult females and juveniles did not select higher protein foods than silverbacks but rather consumed more dry matter to ingest more protein. Juveniles consumed more minerals (Ca, P, Mg, K, Fe, Zn, Mn, Mo) per kilogram of body mass than adult females and silverback males, and juveniles consumed diets with higher concentrations of phosphorous, iron, and zinc, indicating that the foods they ate contained higher concentrations of these minerals. Seasonally, the amount of food consumed on a dry weight basis did not vary, but with increased frugivory, dietary concentrations of protein and fiber decreased and those of water-soluble carbohydrates increased. Energy intake did not change over the year. With the exception of sodium, gorillas ate diets that exceeded human nutrient requirements. A better understanding of the relative importance of food quantity and quality for different age–sex classes provides insights into the ways in which gorillas may be limited by food resources when faced with environmental heterogeneity.     

Pollen as an alternative food for Harmonia axyridis

The current study examines the potential of the multicoloured Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) to use pollen as a food to sustain development and reproduction in the absence of insect prey. Three populations of H. axyridis were used in this study: a long-term laboratory population (since 1998) and a melanic and non-melanic population originating from field collected individuals in Belgium. The insects were allowed to develop and reproduce on frozen eggs of Ephestia kuehniella Zeller (Lepidoptera: Phycitidae), frozen moist bee pollen or an even mixture of the two. Females of the field population offered the mixed diet initiated oviposition sooner than those fed only E. kuehniella eggs, but other developmental and reproductive traits were similar on these diets. A diet of pollen alone allowed 35–48% of the larvae of the field population of H. axyridis to successfully reach adulthood. However, developmental time for these individuals was prolonged by 31–49% and adult body weight was reduced by 37–68%, compared to individuals offered the diets containing E. kuehniella eggs. When fed exclusively on pollen in their larval and adult life, about 40% of the adult females of either field population were able to produce a small number of viable eggs. The laboratory and field strains differed in their response to diet for a number of developmental and reproductive traits. The exploitation of pollen and other plant foods at times when insect prey is scarce, may offer a further competitive advantage to the non-indigenous coccinellid H. axyridis over native European predatory lady beetles that share the same niche and are less capable of using pollen as an alternative food.     

Fitness consequences for copepods feeding on a red tide dinoflagellate: deciphering the effects of nutritional value, toxicity, and feeding behavior

Phytoplankton exhibit a diversity of morphologies, nutritional values, and potential chemical defenses that could affect the feeding and fitness of zooplankton consumers. However, how phytoplankton traits shape plant–herbivore interactions in the marine plankton is not as well understood as for terrestrial or marine macrophytes and their grazers. The occurrence of blooms of marine dinoflagellates such as Karenia brevis suggests that, for uncertain reasons, grazers are unable to capitalize on, or control, this phytoplankton growth—making these systems appealing for testing mechanisms of grazing deterrence. Using the sympatric copepod Acartia tonsa, we conducted a mixed diet feeding experiment to test whether K. brevis is beneficial, toxic, nutritionally inadequate, or behaviorally rejected as food relative to the palatable and nutritionally adequate phytoplankter Rhodomonas lens. On diets rich in K. brevis, copepods experienced decreased survivorship and decreased egg production per female, but the percentage of eggs that hatched was unaffected. Although copepods showed a 6–17% preference for R. lens over K. brevis on some mixed diets, overall high ingestion rates eliminated the possibility that reduced copepod fitness was caused by copepods avoiding K. brevis, leaving nutritional inadequacy and toxicity as remaining hypotheses. Because egg production was dependent on the amount of R. lens consumed regardless of the amount of K. brevis eaten, there was no evidence that fitness costs were caused by K. brevis toxicity. Copepods limited to K. brevis ate 480% as much as those fed only R. lens, suggesting that copepods attempted to compensate for low food quality with increased quantity ingested. Our results indicate that K. brevis is a poor food for A. tonsa, probably due to nutritional inadequacy rather than toxicity, which could affect bloom dynamics in the Gulf of Mexico where these species co-occur.     

Digestive responses of two omnivorous rodents (<Emphasis Type="Italic">Peromyscus maniculatus</Emphasis> and <Emphasis Type="Italic">P. alstoni</Emphasis>) feeding on epigeous fungus (<Emphasis Type="Italic">Russula occidentalis</Emphasis>)

The sporocarps of hypogeous and epigeous fungi are important dietary items for forest dwelling rodents in temperate and tropical forests throughout the world. However, results of some pioneering works have demonstrated that fungi cannot be considered as nutritionally high-quality food items for some mycophagous small rodents. According to these studies, when mycophagous rodents feed on fungus, they showed a minimal digestibility, but whether this applies to most rodent species that include fungi in their diets is unknown. In this study, we experimentally evaluated body mass changes and feed preferences in captive deer (Peromyscus maniculatus) and volcano (P. alstoni) mice when fed on epigeous fungus (Russula occidentalis). In experiment 1, the animals were fed with fungus as the only feedstuff in comparison to regular rodent chow and oat. In experiment 2, the animals were fed with fungus in a free-choice arrangement together with equal amounts of rodent chow and oat. Both species lost ∼15% of their body mass within 4 days when fed on fungus alone, but gained 5–10% body mass during the same time period when ingesting oat and rodent chow, respectively, as the only feedstuff. However, in contrast, in the free-choice arrangement with all three feedstuffs, both species gained 20–30% body mass, and showed the highest feed preference for fungus followed by oat and rodent chow. In addition, apparent digestibility of energy and nitrogen were analyzed in both rodent species, which were 50–60% for fungus, whereas approximately 90–94% for rodent chow and oat. According to our results, animals need to supplement their diets with alternative high-quality food items in order to maintain and increase their body mass, suggesting that epigeous fungi are only of moderate nutritional value for small rodents. Futures studies should focus on exploring the importance of a mixture of fungal species in the diet of small mycophagous rodents.     

The effects of azadirachtin-treated diets on the feeding behaviour and fecundity of the peach-potato aphid,Myzus persicae

Adult apterousMyzus persicae, which had fed for 26 h on diet containing azadirachtin at concentrations of 25–100 ppm, produced nymphs at less than half the rate of aphids on control diets. After 50 h on azadirachtin-treated diets nymph production had virtually ceased. After this period, any nymphs produced by adults that had fed on azadirachtin-treated diets were born dead with undeveloped appendages. Honeydew production on azadirachtin-treated diets was unaffected during the first 26 h period but was approximately three times less than on control diets during the subsequent 24 h period.     

Maintenance of gynodioecy in Wurmbea biglandulosa (Colchicaceae): gender differences in seed production and progeny success

 In gynodioecious species, females contribute genes to future generations only through ovules, and to persist in populations they must have a compensatory advantage compared with hermaphrodites that reproduce via ovules and pollen. This compensation can result from greater fecundity and/or superior success of progeny from females. We examined differences in seed production and progeny success between females and hermaphrodites in the geophyte Wurmbea biglandulosa to explain the maintenance of females. Females produced more ovuliferous flowers and had more ovules per flower than did hermaphrodites but this did not necessarily result in greater fecundity, in part because seed production of females was pollen-limited. Over four years in one population, open-pollinated females produced 1.32 more seeds than open-pollinated hermaphrodites (range 1.09–1.63). In two other populations examined for one year only females produced 1.07 and 0.79 as many seeds as hermaphrodites. Seed production of open-pollinated females and hermaphrodites was only 55% and 73% that of cross-pollinated plants, respectively, indicating that both genders were pollen-limited but females more so than hermaphrodites. Open-pollinated seeds from females were 1.18–1.27 times more likely to germinate than seeds from hermaphrodites. No gender differences existed in seedling growth or survival. Hermaphrodites were self-compatible, but selfed seed set was only 80% that of crossed seed set. Crossed seed set of females and hermaphrodites did not differ. Assuming nuclear control of male sterility, relative female fitness is insufficient to maintain females at their current frequencies of 17%, and substantial female fitness advantages at later life-cycle stages are required. Received May 4, 2001 Accepted February 25, 2002     

Growth performance and body composition in response to dietary protein and lipid levels in Nile tilapia (Oreochromis niloticus Linnaeus, 1758) subjected to normal and temporally restricted feeding regimes

A factorial experiment was designed to examine the effect on compensatory growth (CG) of Nile tilapia Oreochromis niloticus fed diets containing different protein and lipid levels under normal and temporally restricted feeding regimes. Four diets were formulated to contain either 30% or 36% crude protein, and 5% or 11% crude lipid. Triplicate replicates of each treatment were assigned to 24 150‐L tanks (20 fish/tank density). Fish (mean initial weight ± SD = 8.79 ± 0.34 g) were then fed either the normal feeding regime (thrice daily to apparent satiation) or the restricted regime (1 day feed deprivation followed by 3 days of feeding to apparent satiation) over a 44‐days study period. Fish receiving a diet under the restricted regime achieved weight gains (WG) comparable to fish consuming the diet containing 30% protein and 5% lipids under the normal feeding regime. Fish maintained on the restricted feeding regime exhibited reduced feed intake (FI), WG, feed efficiency ratio (FE), protein efficiency rate (PER) and hepatosomatic index versus fish on the normal feeding regime, except WG in fish fed the diet with 30% protein and 5% lipids. However, the resultant FI (85%~94%) was higher than the excepted 75% intake when fish were subjected to the restricted regime. Feeding 11% lipid diets led to improved FI, WG, FE, and PER compared to feeding the 5% lipid diets. Increased FI, WG, and FE, but reduced PER were observed in fish fed with 36% protein versus fish fed 30% protein. Fish receiving the 36% protein diets had lower whole‐body moisture and ash contents, but elevated whole‐body protein and lipid contents compared to those receiving the 30% protein diets. Whole‐body moisture contents were lower, but whole‐body protein, lipid and ash contents were higher in fish fed 11% lipid diets than in fish fed 5% lipid diets. There was an increase in whole‐body moisture content, but a decrease in protein and lipid content in response to the restricted feeding regime. Ash content was not affected by the feeding regime. The present study shows that Nile tilapia fed diets subjected to a restricted feeding regime exhibited growth comparable to those fed the diet at 30% protein and 5% lipid levels under a normal feeding regime. This positive effect was more pronounced in diets at a high protein level or in a combination of high protein and lipid levels.     

Growth and survival of river catfish Mystus nemurus (Cuvier & Valenciennes) larvae fed isocaloric diets with different protein levels during weaning

The growth of river catfish Mystus nemurus (Cuvier & Valenciennes) larvae fed four isocaloric diets (4200 kcal kg^?1) with different protein levels during weaning was determined. Diets containing 45, 50, 55, and 60% protein were formulated by linear programming using amino acid profiles based on that of 2‐day‐old river catfish larvae. Artificial diets were fed to the larvae beginning at day 5 after being initially fed Artemia nauplii for 4 days. The larvae thrived solely on artificial diets from day 8 to day 16. On the other hand, the control larvae were fed Artemia nauplii from day 1 to day 16. Results of the feeding trial showed that growth and survival of M. nemurus larvae given the diet containing 60% protein were high and comparable to those of the larvae given only live food (control). Larvae fed the 55% protein diet had significantly lower growth and survival than the larvae on the control and 60% diets but significantly higher growth and survival rates than did larvae fed with 45 and 50% protein diets. Carcass moisture and total lipids after 16 days of feeding did not differ significantly (P > 0.05), but body protein increased with increasing dietary protein. Body protein of the control larvae was similar to that of larvae given the 60% protein diet.     

Parasitism of an insect Manduca sexta L. alters feeding behaviour and nutrient utilization to influence developmental success of a parasitoid

The effects of macronutrient balance on nutrient intake and utilization were examined in Manduca sexta larvae parasitized by Cotesia congregata. Insects fed an artificial diet having constant total macronutrient, but with varied ratios of protein and carbohydrate, with altered diet consumption in response to excesses and deficiencies of the individual macronutrients. Bivariate plots of protein and carbohydrate consumption for non-parasitized larvae demonstrated a curvilinear relationship between points of nutrient intake for the various diets, and the larvae grew best on carbohydrate-biased diets. The relationship was linear for parasitized larvae with the growth uniform across diets. On protein-biased diets, the larvae regulated the nitrogen content, containing similar amounts of nitrogen regardless of consumption. Efficiency of nitrogen conversion in non-parasitized larvae was greatest on carbohydrate-biased diets, while nitrogen conversion by parasitized larvae was greatest with intermediate nutrient ratios. Accounting for carbohydrate consumption, the lipid content decreased as dietary carbohydrate increased, but parasitized larvae contained significantly less lipid. The total biomass of parasites developing in individual host larvae was positively correlated with host protein consumption, but the individual parasites were similar in size. Parasitism influences host nutrient consumption in a manner that achieves uniform host growth under diverse nutritional regimes, thereby constraining blood nutrient concentrations within limits suitable for parasite growth and development.     

Influence of diet and photoperiod on development and reproduction of European populations of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)

The current study examines the effect of photoperiod (16:08 or 12:12 h L:D) and diet (eggs of Ephestia kuehniella Zeller (Lepidoptera: Phycitidae) or the pea aphid Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae)) on the development and reproduction of the multicoloured Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). A long-term laboratory population of H. axyridis (since 1998) and a melanic and non-melanic population originating from field collected individuals of H. axyridis in Belgium were used in this study. Long day conditions (16 h photoperiod) shortened development of the field populations with 2–3 days when compared with short day conditions (12 h photoperiod). Oviposition in the field populations was delayed by 1–3 months when reared at a 12 h photoperiod. Dissections indicated that the females were in reproductive diapause. As compared with live pea aphids, a diet consisting of E. kuehniella eggs yielded heavier adult body weights (up to 12%) and increased the number of egg laying days (by 45–169%) for both field populations at a 16 h photoperiod and lengthened adult life span (by 45–92%) under both light regimens. The morph types differed in their response to the foods offered in terms of developmental rate, pre-oviposition period and number of oviposition days. The laboratory and field strains responded differentially to regimens of food and photoperiod. The study indicated a greater nutritional plasticity of the non-melanic morphs which may offer them a competitive advantage that may in part explain the predominance of non-melanic morphs in newly colonized areas.     

Growth and protein synthesis of barramundi, Lates calcarifer, fed lupin as a partial protein replacement

Protein synthesis is an essential growth process in all animals. Little information is available on post-prandial protein synthesis and even less where different protein sources are compared. Protein synthesis was measured at 4 and 24 h after feeding juvenile barramundi in order to determine the effect of using lupin as a partial protein replacement for fish meal on the post-prandial protein metabolism. Juvenile barramundi (4.3 ±0.6 g) were held in a recirculation system (27 °C, salinity 10‰ and 24 h light) for 15 days. Fish were fed one of two isonitrogenous isoenergetic diets (40% crude protein, 16% lipid and 18.5 GE MJ kg^− 1). One diet was formulated with 100% fish meal as the protein source while the other had 45% of the protein replaced with lupin ingredients (lupin kernel meal (Lupinus angustifolius) and lupin protein concentrate). All fish were fed a ration of 6%·d^− 1 and feed intake was not significantly different between the two diets. Specific growth rate (SGR) and growth efficiency (in relation to protein (PPV) and energy (PEV)) were 6.5 ± 0.14%·d^− 1, 43.8 ± 2.72% and 38.31 ± 1.56%, respectively, and were not significantly different between the two diets. There was no significant difference in protein synthesis between the two diets at 4 and 24 h after feeding, however protein synthesis was significantly higher 4 h after feeding than at 24 h (p = 0.02). Neither growth performance nor protein metabolism was altered by replacing 45% of the protein with lupin protein and indicated this to be a suitable protein source for barramundi feeds.     

Beneficial effect of supplementing an artificial diet for Amblyseius swirskii with Hermetia illucens haemolymph

Artificial diets have been developed to sustain the mass rearing of a wide range of arthropod natural enemies, with varying success. In some cases, such diets can be optimized using insect‐derived materials, such as haemolymph. In this study, we examined the effect of supplementing haemolymph of the black soldier fly, Hermetia illucens, to a basic artificial diet for the phytoseiid mite Amblyseius swirskii. The survival, development and reproduction of the predatory mite were assessed when fed on artificial diets composed of honey, sucrose, tryptone, yeast extract and egg yolk, supplemented with 5%, 10%, or 20% of H. illucens pre‐pupal haemolymph. Developmental time from larva to adult was shorter for males and females offered artificial diets supplemented with 20% haemolymph vs. the basic diet. The oviposition rate and total fecundity of females reared on the basic diet were substantially lower than those of females supplied with the enriched diets. The intrinsic rate of increase was highest on the diet containing 20% haemolymph, followed by those containing 10% and 5% haemolymph. In a subsequent diet‐switching experiment, mites fed on the basic diet in their juvenile stages were switched upon adulthood to diet enriched with different concentrations of H. illucens haemolymph. The females that were fed with the enriched diets from the adult stage on had higher oviposition rates and fecundities than those maintained on the basic diet, but their reproductive parameters were not significantly affected by the concentration of the haemolymph in the artificial diet. In conclusion, supplementing artificial diets with black soldier fly haemolymph significantly improved their nutritional value for A. swirskii. Our findings indicate the potential of using H. illucens as a cheap source for haemolymph in artificial diets, as the fly can be cost‐effectively produced at a large scale on organic waste materials.     

Haemolymph amino acid and sugar levels in locusts fed nutritionally unbalanced diets

Aspects of pre- and post-ingestive compensation were investigated in locusts (Locusta migratoria) fed nutritionally unbalanced artificial diets containing 7% protein and 21% digestible carbohydrate (7:21) or 21% protein and 7% digestible carbohydrate (21:7). Feeding behaviour and haemolymph levels of amino acids and sugars were measured in locusts fed ad libitum on these diets. Locusts fed the high-protein diet had chronically elevated haemolymph levels of 15 out of 19 amino acids measured compared to locusts fed the low protein diet. However, haemolymph levels of lysine, alanine, aspartic acid and glutamic acid did not differ between diets, suggesting some specific regulatory mechanism for these amino acids. Haemolymph glucose and trehalose reflected levels of carbohydrate in the diets, being high in insects fed diet 7:21 relative to those given diet 21:7. These data are discussed in relation to the physiological and behavioural bases of nutritional homeostasis.Abbreviations AA amino acid(s) - PRO protein - CHO carbohydrate - PBS phosphate-buffered saline - MW molecular weight     

Low Tryptophan and Protein in the Diet During Development Increase the Susceptibility to Convulsions in Adult Rats

Tryptophan (TRY) is the precursor for serotonin (5-HT) synthesis. Common maize has low protein content with low concentration of TRY and lysine. A diet based on two strains of corn differing in their TRY content were given to adult female rats, prior mating, during pregnancy and lactation. Same diets were offered to their male offspring after weaning until reaching 60-days old. The pattern and severity of the convulsive phenomenon induced by monosodium glutamate (MSG) in a well established model of Status epilepticus were evaluated in comparison with data from animals of two control groups: (a) rats fed a hypoproteic (8% protein) diet, and (b) rats fed a normal Purina chow diet (23% protein). Significant increased susceptibility to convulsions was observed in both groups of rats fed the corn-based diets. However, the animals fed the common corn-based diet (8–9% protein; 0.058% TRY) showed a higher susceptibility to convulsions than what was registered in animals fed a Quality Protein Maize (QPM)-based diet (8–9% protein; 0.1% TRY). It is concluded that low TRY concentration in the diet during development, produces lower rate of brain 5-HT synthesis, affecting development and maturation of GABAergic inhibitory cortical interneurons, with alteration of cortical excitability, contributing in part, to the increased susceptibility to convulsions, as shown in the experiments here reported. Special issue article in honor of Dr. Ricardo Tapia.     

Feeding habits of juvenile slime flounder <Emphasis Type="Italic">Microstomus achne</Emphasis> in the coastal area of southern Hokkaido

A total of 45 juvenile [30.0–57.4 mm total length (TL)] slime flounder Microstomus achne were collected in the coastal area of southern Hokkaido from April to July in 2001 and April to June in 2002. Their diets were analyzed. Slime flounder juveniles of 30.0–39.9 mm TL fed predominantly on small crustaceans (gammarid amphipods, harpacticoids and cumaceans) and those of 40.0–57.4 mm TL on gammarid amphipods, cumaceans and polychaetes. The major prey items changed with growth from small crustaceans (e.g., harpacticoids) to polychaetes, although gammarid amphipods were the major prey items throughout the juvenile period (30.0–57.4 mm TL).     

Fitness Implications of Clonal Integration and Leaf Dynamics in a Stoloniferous Herb, Nelsonia canescens (Lam.) Spreng (Nelsoniaceae)

Very little has been published on the life-history significance of clonal plants inhabiting southern African savanna environments. This study investigated the fitness implications of clonal integration, resprouting behaviour and growth phenology in a stoloniferous herb, Nelsonia canescens (blue pussyleaf) at a savanna site in Zambia, central Africa. Census data on growth and survival were obtained regularly on permanently marked ramets over a 4-year period, from 2001 to 2005, and analyzed to assess how physiological integration and module demography contribute to fitness in Nelsonia. Above ground and below ground growth occurred during the dry and rainy seasons, respectively. Dry season growth was characterized by resprouting and production of stolons that bore small pubescent leaves with high mortality (30–80% month⁻¹). Deep roots and high leaf turnover appear to contribute to sustained growth during the dry season when topsoil moisture and nutrient availability are low. The interaction between maximum temperature and precipitation explained a significant proportion (59%, p<0.01) of the monthly variation in leaf size and increasing evapo-transpiration levels appeared to trigger the shift in leaf size from a large wet season type to a small dry season one. During the dry season Nelsonia resprouted from dormant buds buried at the time of root development in daughter ramets in the rainy season. Temporal integration significantly (p<0.05) enhanced survival of daughter ramets. However, daughter ramets with severed mother–daughter ramet inter-connectors experienced high initial mortality that was caused by both early stolon severing and drought stress during the root development phase. The majority of ramets lived for 5–10 months and 25% were still alive at the age of 3.5 years. The study showed that although the growth phenology of Nelsonia has serious ecological implications for accessing scarce resources during the dry season, the species utilizes a number of strategies to overcome resource limitations in a seasonally heterogenous environment. Co-ordinating editor: G. P. Cheplick     

Prenatal and postnatal protein restriction in the rat: effect on some parameters related to brain development, and prospects for rehabilitation.

Abstract— From the third day of pregnancy rats were fed a diet containing either 7% casein (experimental) or 24% casein (control). During lactation the control dams were fed the 24% casein diet and the experimental dams a 12% casein diet. From 25 to 50 days of age the experimental and control progeny were fed diets containing 7 and 24% casein, respectively. Between 50 and 120 days both groups were fed a diet containing 24% crude protein. Several indications of brain maturation in two brain areas were examined at various stages of development. In addition to retardation of brain growth, protein restriction led to myelin of an immature composition at 25 and 50 days of age. The immature composition was indicated by a low plasmalogen content at 25 days and by a high phospholipid and low galactolipid and plasmalogen contents at 50 days of age. The activity of the myelin marker enzyme, 2′3′-cyclic nucleotide 3′-phosphohydrolase (CNP), was significantly lower in the brains (excluding the cerebella) of malnourished rats at 21, 30 and 50 days. At all ages except at 50 days the activity of CNP in the cerebellum was higher in protein-deprived animals than in controls. The activity of glutamic acid decarboxylase (GAD) in the brains (excluding the cerebella) of protein-deprived rats was significantly lower at 21, 25 and 30 days but not at 50 and 65 days of age. As indicated by brain/body ratios, myelin composition and GAD activity, nutritional rehabilitation led to almost complete recovery of brain maturity, but the activity of CNP remained lower in the experimental group after rehabilitation.     

Dietary zinc mediates inflammation and protects against wasting and metabolic derangement caused by sustained cigarette smoke exposure in mice

In mouse asthma models, inflammation can be modulated by zinc (Zn). Given that appetite loss, muscle wasting and poor nutrition are features of chronic obstructive pulmonary disease (COPD) and that poor dietary Zn intake is in itself accompanied by growth retardation and appetite loss, we hypothesised that dietary Zn limitation would not only worsen airway inflammation but also exaggerate metabolic effects of cigarette smoke (CS) exposure in mice. Conversely, Zn supplementation would lessen inflammation. Mice were exposed to CS [2× 2RF, 3×/day; 15 min/cigarette] and fed diets containing 2, 20 or 140 mg/kg Zn ad libitum. Airway cells were collected by bronchoalveolar lavage (BAL). Plasma Zn was measured by fluorometric assay. Inflammatory, metabolic and Zn transport markers were measured by real-time RT-PCR. Mice fed low Zn diets had less plasma labile zinc (0–0.18 μM) than mice fed moderate (0.61–0.98 μM) or high (0.77–1.1 μM) Zn diets (SDs 0.1–0.4, n = 8–10). Smoke exposure increased plasma and BAL labile Zn (1.5–2.5 fold, P < 0.001), bronchoalveolar macrophages (2.0 fold, P < 0.0001) and MT-1 (1.5 fold), MIP-2 (2.3 fold) and MMP-12 (3.5 fold) mRNA. Zn supplementation reduced alveolar macrophage numbers by 62 and 52% in sham and smoke-exposed mice, respectively (Zn effect: P = 0.011). Gastrocnemius, soleus and tibialis anterior muscle mass were affected by both smoke and dietary Zn in the order of 3–7%. The 50–60% reduction in alveolar macrophages in Zn-supplemented mice supports our evolving hypothesis that Zn is an important anti-inflammatory mediator of airway inflammation. Restoring airway Zn levels through dietary supplementation may lessen the severity of lung inflammation when Zn intake is low.     

The effect of dietary protein and carbohydrate concentration on the biochemical composition and gametogenic condition of the sea urchin Lytechinus variegatus

Previously starved urchins, Lytechinus variegatus, (36.0 ± 0.8 (SE) mm test diameter) were held in replicated (3) 10-L aquaria with artificial seawater at 22 ± 2  °C and 32‰ salinity and fed three diet treatments. Urchins were fed diets containing 9 : 35, 20 : 23 or 31 : 12% dry protein: % dry carbohydrate (P : C) ad libitum for a 65-day period. Gonads from urchins fed the 9 : 35 P : C diet had similar organic, lower ash, and lower water content than urchins fed the 31 : 12 P : C protein diet. Water content varied with both diet and nutritional history; consequently, water content may have limited value as a predictor of gonad nutritional status. Protein and carbohydrate concentrations in the gonad were directly related to the dietary composition of these nutrients; gonad lipids did not vary with diet. Excess carbohydrates are frequently stored as fats in fish and mammals but this does not appear to be the case in L. variegatus. Test carbohydrate storage and gut protein storage also reflected dietary composition. Image analysis of ovaries indicated decreased nutritive phagocyte volume, increased germinal epithelium volume and larger oocyte diameters in urchins fed high protein, low carbohydrate diets. Analysis of testes also indicated decreased nutritive phagocyte volume and increased gamete volume with urchins fed high protein, low carbohydrate diets, but differences among treatments were less obvious than in ovaries. This study suggests that high protein, low carbohydrate diets promote gamete growth and development. In addition, the biochemical and gametic composition of gonads can be altered by manipulating dietary composition. This could affect the quality and value of sea urchin roe for human consumption.