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1.
Recent studies in fruit flies have imposed dietary restriction (DR) by diluting yeast and have reported increased lifespan as the yeast-to-sugar ratio decreased. In this study, the effects of DR on the lifespan of Bactrocera dorsalis were investigated using constant-feeding diets with different yeast:sugar ratios and an intermittent-feeding diet in which flies ate every sixth day. Antioxidant enzyme activities and the malondialdehyde concentration were also measured in virgin females under constant-feeding DR protocols to investigate their relationships with lifespan. The results showed that B. dorsalis lifespan was significantly extended by DR, and carbohydrate-enriched diet may be important for lifespan-extension. Female flies lived significantly longer than males at all dietary levels under both feeding regimes, indicating no interaction between diet and sex in determining lifespan. Antioxidant enzyme activities increased with the amount of yeast increased in the diets (0–4.76%) between starvation and DR treatments, indicating that the antioxidants may have influences in determining lifespan in B. dorsalis under starvation and DR treatments. However, antioxidants cannot keep up with increased oxidative damage induced by the high yeast diet (25%). These results revealed that the extension of lifespan by DR is evolutionarily conserved in B. dorsalis and that yeast:sugar ratios significantly modulate lifespan in this species.  相似文献   

2.
The harpacticoid copepodTisbe holothuriae was collected from Saronicos Gulf (Greece) and reared under constant laboratory conditions. In order to study the effects of food on the population dynamics, seven diets were tested: the seaweedUlva; five artificial compound feeds: the liquid Fryfood® (Waterlife), a powder ofMytilus, yeast, soya andSpirulina, respectively; and a mixed diet consisting ofUlva and Fryfood. The life cycle parameters (mortality, sex ratio, generation time, offspring production) were measured, and the demographic variables [mean generation time (T), net reproductive rate (Ro), and intrinsic rate of natural increase (rm)] were determined. As to their efficiency regarding population dynamics, the diets ranked as follows: (1)Ulva+Fryfood, (2),Ulva, (3) Fryfood, (4)Mytilus, (5) soya, (6) yeast, and (7)Spirulina. In this order they cause a progressive increase of both larval mortality and generation time, a progressive decrease of sex ratio, number of offspring per egg sac, number of egg sacs per female and, consequently, of Ro and rm. The observed differences between diets were most pronounced with respect to offspring production. Of the compound diets, those containing animal extracts were more efficient than those containing vegetable materials.Ulva plays an important role in the nutrition ofT. holothuriae, favouring offspring production as well as larval survival, development and pigmentation.Ulva in combination with Fryfood led to a greater copepodid survival and offspring production. This mixed diet proved to be the most favourable for rearing the Greek population oft. holothuriae, resulting in an efficient intrinsic rate of natural increase (rm=0.304) of the population.  相似文献   

3.
DHA is an important omega-3 PUFA that confers neurodevelopmental benefits. Sufficient omega-3 PUFA intake has been associated with improved mood-associated measures in adult humans and rodents, but it is unknown whether DHA specifically influences these benefits. Furthermore, the extent to which development and puberty interact with the maternal diet and the offspring diet to affect mood-related behaviors in adolescence is poorly understood. We sought to address these questions by 1) feeding pregnant rats with diets sufficient or deficient in DHA during gestation and lactation; 2) weaning their male offspring to diets that were sufficient or deficient in DHA; and 3) assessing depression-related behaviors (forced swim test), plasma biomarkers [brain-derived neurotrophic factor (BDNF), serotonin, and melatonin], and brain biomarkers (BDNF) in the offspring before and after puberty. No dietary effects were detected when the offspring were evaluated before puberty. In contrast, after puberty depressive-like behavior and its associated biomarkers were worse in DHA-deficient offspring compared with animals with sufficient levels of DHA. The findings reported here suggest that maintaining sufficient DHA levels throughout development (both pre- and postweaning) may increase resiliency to emotional stressors and decrease susceptibility to mood disorders that commonly arise during adolescence.  相似文献   

4.
The effect of aqueous extract from R. rosea root on lifespan and the activity of antioxidant enzymes in budding yeast Saccharomyces cerevisiae have been studied. The supplementation of the growth medium with R. rosea extract decreased survival of exponentially growing S. cerevisiae cells under H2O2-induced oxidative stress, but increased viability and reproduction success of yeast cells in stationary phase. The extract did not significantly affect catalase activity and decreased SOD activity in chronologically aged yeast population. These results suggest that R. rosea acts as a stressor for S. cerevisiae cells, what sensitizes yeast cells to oxidative stress at exponential phase, but induces adaptation in stationary phase cells demonstrating the positive effect on yeast survival without activation of major antioxidant enzymes.  相似文献   

5.
Silent Information Regulator 2 (Sir2), a conserved NAD+-dependent histone deacetylase, has been implicated as one of the key factors in regulating stress response and longevity. Here, we report that the role of Sir2 in oxidative stress resistance and chronological lifespan is dependent on growth phase in yeast. In exponential phase, sir2Δ cells were more resistant to H2O2 stress and had a longer chronological lifespan than wild type. By contrast, in post-diauxic phase, sir2Δ cells were less resistant to H2O2 stress and had a shorter chronological lifespan than wild type cells. Similarly, the expression of antioxidant genes, which are essential to cope with oxidative stress, was regulated by Sir2 in a growth phasedependent manner. Collectively, our findings highlight the importance of the metabolic state of the cell in determining whether Sir2 can protect against or accelerate cellular aging of yeast.  相似文献   

6.
Organic polyanions act as complexants of prion protein in soil   总被引:1,自引:0,他引:1  
The persistence of prions, the causative agents of transmissible spongiform encephalopathies, in soil constitutes an environmental concern and substantial challenge. Experiments and theoretical modeling indicate that a particular class of natural polyanions diffused in soils and waters, generally referred to as humic substances (HSs), can participate in the adsorption of prions in soil in a non-specific way, mostly driven by electrostatic interactions and hydrogen bond networks among humic acid molecules and exposed polar protein residues. Adsorption of HSs on clay surface strongly raises the adsorption capacity vs proteins suggesting new experiments in order to verify if this raises or lowers the prion infectivity.  相似文献   

7.
Queensland fruit fly, Bactrocera tryoni (“Q‐fly”), is Australia’s most economically important insect pest of horticultural and commercial crops especially in the eastern regions. The sterile insect technique (SIT) has been adopted as an environmentally benign and sustainable approach for management of Q‐fly outbreaks. High‐performance larval diets are required to produce the millions of flies needed each week for SIT. Yeast products contribute amino acids (protein) to fruit fly larval diets, as well as carbohydrate, fat and micronutrients, but there can be substantial variation in the nutritional composition and suitability of yeast products for use in larval diets. Gel larval diets have recently been developed for large‐scale rearing of Q‐fly for SIT, and composition of these diets requires optimization for both performance and cost, including choice of yeast products. We assessed performance of Q‐flies reared on gel larval diets that contained debittered brewer’s yeast (Lallemand LBI2240), hydrolysed yeast (Lallemand FNILS65), inactivated brewer’s yeast (Lallemand LBI2250) and inactivated torula yeast (Lallemand 2160‐50), including blends. Q‐flies performed poorly when reared on diets containing only or mostly hydrolysed yeast in terms of pupal number, pupal weight and percentage of fliers. Performance was also poor on diets containing high proportions of torula yeast. Overall, debittered brewer’s yeast is recommended as the best option for Q‐fly gel larval diet, as it is cheap, readily available, and produces flies with good performance in quality control assays. Inactivated brewer’s yeast produced flies of comparable quality with only a modest increase in cost and would also serve as an effective alternative.  相似文献   

8.
Catalase (EC 1.11.1.6) is an important antioxidant enzyme that protects aerobic organisms against oxidative damage by degrading hydrogen peroxide to oxygen and water. Catalase mRNAs have been cloned from many species and employed as useful biomarkers of oxidative stress. In the present study, we cloned the cDNA from the catalase gene in Daphnia magna, analyzed its catalytic properties, and investigated mRNA expression patterns after the exposure to known oxidative stressors. The catalase proximal heme-ligand signature sequence, FDRERISERVVHAKGSGA, and the proximal active site signature, RLFSYTDTH, are highly conserved. The variation of catalase mRNA expression in D. magna was quantified by real-time PCR, and the results indicated that catalase expression was up-regulated after exposure to UV-B light or cadmium (Cd). The activity of catalase enzyme also showed a similar increasing pattern when exposed to these model stressors. The full-length catalase cDNA of D. magna was cloned using mixed primers by the method of 3′ and 5′ rapid amplification of cDNA ends PCR. The cDNA sequence consists of 1515 nucleotides, encoding 504 amino acids. Sequence comparison showed that the deduced amino acid sequence of D. magna shared 73%, 72%, 71% and 70% identity with that of Chlamys farreri, Fenneropenaeus chinensis, Litopenaeus vannamei and Anopheles gambiae, respectively. This study shows that the catalase mRNA from D. magna could be successfully employed as a biomarker of oxidative stress, which is a common mode of toxicity for many water contaminants.  相似文献   

9.
This study addresses how humic substance (HS) chemical composition and photoreactivity affect bacterial growth, respiration, and growth efficiency (BGE) in lake water. Aqueous solutions of HSs from diverse aquatic environments representing different dissolved organic matter sources (autochthonous and allochthonous) were exposed to artificial solar UV radiation. These solutions were added to lake water passed through a 0.7-μm-pore-size filter (containing grazer-free lake bacteria) followed by dark incubation for 5, 43, and 65 h. For the 5-h incubation, several irradiated HSs inhibited bacterial carbon production (BCP) and this inhibition was highly correlated with H2O2 photoproduction. The H2O2 decayed in the dark, and after 43 h, nearly all irradiated HSs enhanced BCP (average 39% increase relative to nonirradiated controls, standard error = 7.5%, n = 16). UV exposure of HSs also increased bacterial respiration (by ~18%, standard error = 5%, n = 4), but less than BCP, resulting in an average increase in BGE of 32% (standard error = 10%, n = 4). Photoenhancement of BCP did not correlate to HS bulk properties (i.e., elemental and chemical composition). However, when the photoenhancement of BCP was normalized to absorbance, several trends with HS origin and extraction method emerged. Absorbance-normalized hydrophilic acid and humic acid samples showed greater enhancement of BCP than hydrophobic acid and fulvic acid samples. Furthermore, absorbance-normalized autochthonous samples showed ~10-fold greater enhancement of BCP than allochthonous-dominated samples, indicating that the former are more efficient photoproducers of biological substrates.  相似文献   

10.
An experiment is conducted to investigate the effects of selenium (Se) source and level on growth performance, tissue Se concentrations, antioxidation, and immune functions of heat-stressed broilers from 22 to 42?days of age. A total of 210 22-day-old Arbor Acres commercial male chicks were assigned by body weight to one of seven treatments with six replicates of five birds each in a completely randomized design involving a 3?×?2 factorial arrangement plus one Se-unsupplemented basal diet control (containing 0.027?mg of Se/kg). The three Se sources were sodium selenite (Na2SeO3), Se yeast, and AMMS Se (Se protein), and the two supplemental Se levels were 0.15 or 0.30?mg Se/kg. All birds were reared under heat-stressed condition (33?±?1?°C during 0900?C1700?hours and 27?±?1?°C during 1900?C0700?hours with a relative humidity of 60?C80?%). The results showed that heat-stressed chicks fed Se-supplemented diets had higher (P?<?0.10) average daily feed intake, Se concentrations in liver and breast muscle, liver glutathione peroxidase (GSH-Px) activity, serum antibody titers against H5N1(Re-4 strain), H5N1(Re-5 strain) and lower (P?<?0.01) mortality compared with the control. Chicks fed the diets supplemented with 0.30?mg/kg of Se had higher (P?<?0.05) Se concentrations in liver and breast muscle, liver GSH-Px activity, and serum antibody titer against H5N1 (Re-4 strain) than those fed the diets supplemented with 0.15?mg/kg of Se. Broilers fed the diets supplemented with Se yeast had higher (P?<?0.001) Se concentrations in liver and breast muscle than those fed the diets supplemented with Na2SeO3 or AMMS Se. However, broilers fed the diets supplemented with AMMS Se had higher (P?<?0.05) serum antibody titers against H5N1 (Re-4 strain) and H5N1 (Re-5 strain) than those fed the diets supplemented with Na2SeO3. These results indicated that Se yeast was more effective than Na2SeO3 or AMMS Se in increasing tissue Se retention; however, AMMS Se was more effective than Na2SeO3 or Se yeast in improving immune functions of heat-stressed broilers.  相似文献   

11.
Reduced protein levels in nursery diets have been associated with a lower risk of postweaning diarrhea, but the interaction with CP levels in maternal diet on the performance of the offspring remains unclear. The objective of this study was to determine the effect of protein content in sow gestation and piglet nursery diets on the performance of the piglets until slaughter. This was studied in a 2 × 2 factorial trial (35 sows, 209 piglets), with higher or lower (H or L) dietary CP in sow diets (168 vs 122 g CP/kg) during late gestation. A standard lactation feed was provided for all sows (160 g CP/kg). For both sow treatments, half of the litters received a higher or lower CP in the piglet nursery diet (210 vs 166 g CP/kg). This resulted in four possible treatment combinations: HH, HL, LH and LL, with sow treatment as first and piglet treatment as second letter. For each phase, all diets were iso-energetic and had a similar level of essential amino acids. Ps*p is the p-value for the interaction effect between sow and piglet treatment. In the nursery phase (3.5–9 weeks of age), a tendency toward interaction between piglet and sow treatments with feed efficiency (Ps*p = 0.08) was observed with HH having the highest gain:feed ratio (G:F) (0.74 ± 0.01), LH the lowest (0.70 ± 0.01) and the other two groups intermediate. In the growing-finishing phase, an interaction was observed between the piglet and sow diets with decreased G:F for LH (Ps*p = 0.04) and a tendency toward interaction with increased daily feed intake for LH (Ps*p = 0.07). The sow diet showed a tendency toward a long-lasting effect on the dressing percentage and meat thickness of the offspring, which was higher for the progeny of H sows (Ps < 0.01 and Ps = 0.02, respectively). At 23 weeks, serum urea concentrations tended to be lower for the HH and LL groups (Ps*p = 0.07). Fecal consistency scores were higher at day 10–day 14 after weaning for piglets from L sows (Ps = 0.03 and Ps < 0.01, respectively). At day 7 after weaning, fecal consistency score was higher for piglets fed the higher protein diet (Pp < 0.01). At 8 weeks of age, the apparent total tract digestibility of CP (ATTDCP) interacted between piglet and sow diet (Ps*p = 0.02), with HH showing the highest digestibility values. In conclusion, the protein levels in sow late-gestation and piglet nursery diets interacted with feed efficiency, ATTDCP and serum urea concentrations in the nursery phase.  相似文献   

12.
Oak acorn contains high levels of tannins which have capacity to form complexes with proteins and consequently reduce their availability and as a result it could reduce colostrum quality and immunoglobulin (Ig) synthesis. Thus, the aim of this experiment was to investigate the effects of dietary oak (Quercus persica) acorn (OA) level during the last 60 days of pregnancy on colostrum composition and plasma metabolites and IgG level of goats and their kids. In all, 24 multiparous pregnant goats (41.7±2.3 kg BW) were assigned into one of the three experimental diets consisted of control diet (without OA) and diets containing 20% (OA20) or 40% (OA40) OA on dry matter basis. Goats fed OA40 had lower BW change compared with other groups (P⩽0.05). Kids birth weight was not affected by experimental diets (P>0.05). Goats fed OA containing diets had lower plasma glucose, triglyceride and Fe concentrations compared with those fed the control diet (P<0.01). Plasma IgG (P<0.01) and urea (P<0.05) concentrations were lower in goats fed OA40 compared with others. Animals fed OA containing diets had higher plasma alanine aminotransferase than those fed the control diet (P<0.05). Goats fed OA40 produced colostrum with lower fat (P⩽0.05) and lactose (P<0.01) contents compared with other animals. Goats fed OA containing diets had lower colostrum IgG level than those fed the control diet (P⩽0.05). Kids plasma total protein concentration was not affected by experimental diets (P>0.05), whereas kids born from goats fed OA containing diets had lower plasma IgG level compared with the control diet (P<0.01). It is concluded that feeding OA during the last 60 days of pregnancy decreased colostrum quality which may have adverse effect on kid’s survival.  相似文献   

13.
Yeast is frequently used as a probiotic in aquaculture with the potential to substitute for antibiotics. In this study, the involvement and extent to which the viability of yeast cells and thus the secretory metabolites released from the yeast contribute to effects of baker’s yeast was investigated in Nile tilapia. No yeast, live yeast or heat-inactivated baker’s yeast were added to basal diets high in fishmeal and low in soybean (diet A) or low in fishmeal and high in soybean (diet B), which were fed to fish for 8 weeks. Growth, feed utilization, gut microvilli morphology, and expressions of hsp70 and inflammation-related cytokines in the intestine and head kidney were assessed. Intestinal microbiota was investigated using 16S rRNA gene pyrosequencing. Gut alkaline phosphatase (AKP) activity was measured after challenging the fish with Aeromonas hydrophila. Results showed that live yeast significantly improved FBW and WG (P < 0.05), and tended to improve FCR (P = 0.06) of fish compared to the control (no yeast). No significant differences were observed between inactivated yeast and control. Live yeast improved gut microvilli length (P < 0.001) and density (P < 0.05) while inactivated yeast did not. The hsp70 expression level in both the intestine and head kidney of fish was significantly reduced by live yeast (P < 0.05) but not inactivated yeast. Live yeast but not inactivated yeast reduced intestinal expression of tnfα (P < 0.05), tgfβ (P < 0.05 under diet A) and il1β (P = 0.08). Intestinal Lactococcus spp. numbers were enriched by both live and inactivated yeast. Lastly, both live and inactivated yeast reduced the gut AKP activity compared to the control (P < 0.001), indicating protection of the host against infection by A. hydrophila. In conclusion, secretory metabolites did not play major roles in the growth promotion and disease protection effects of yeast. Nevertheless, secretory metabolites were the major contributing factor towards improved gut microvilli morphology, relieved stress status, and reduced intestinal inflammation of Nile tilapia fed diets supplemented with baker’s yeast.  相似文献   

14.
Insect lifespan is often closely linked to diet, and diet manipulations have been central to studies of ageing. Recent research has found that lifespan for some flies is maximised on a very low yeast diet, but once all yeast is removed, lifespan drops precipitously. Although effects of yeast availability on lifespan are commonly interpreted in terms of protein, yeast is a complex mix of nutrients and provides a rich source of vitamins, minerals and sterols. Elucidating which components of yeast are involved in this lifespan drop provides insights into more specific nutritional requirements and also provides a test for the commonplace interpretation of yeast in terms of protein. To this end, we fed Queensland fruit flies (Bactrocera tryoni) one of eight experimental diets that differed in the nutrient group(s) found in yeast that were added to sucrose: none, vitamins, minerals, amino acids, cholesterol, vitamin+mineral+cholesterol (VMC), vitamin+mineral+cholesterol+amino acids (VMCA), and yeast. We measured survival rates and egg production in single sex and mixed sex cages, as well as nutrient intake of individual flies. We found that the addition of minerals increased lifespan of both male and female flies housed in single sex cages by decreasing baseline mortality. The addition of just amino acids decreased lifespan in female flies; however, when combined with other nutrient groups found in yeast, amino acids increased lifespan by decreasing both baseline mortality and age-specific mortality. Flies on the yeast and VMCA diets were the only ones to show significant egg production. We conclude that the drop in lifespan observed when all yeast is removed is explained by missing micronutrients (vitamins, minerals and cholesterol) as well as the absence of protein in females, whereas minerals alone can explain the pattern for males. These results indicate a need for caution when interpreting effects of dietary yeast as effects of protein.  相似文献   

15.
In this study, we examined the effects of two phytoplankton species, Chlorella vulgaris and Stephanodiscus hantzschii, on growth of the zooplankton Daphnia magna. Our experimental approach utilized stable isotopes to determine the contribution of food algae to offspring characteristics and to the size of adult D. magna individuals. When equal amounts of food algae were provided (in terms of carbon content), the size of individuals, adult zooplankton, and their offspring increased significantly following the provision of S. hantzschii, but not after the provision of C. vulgaris or of a combination of the two species. Offspring size was unaffected when C. vulgaris or a mixture of the two algal species was delivered, whereas providing only S. hantzschii increased the production of larger-sized offspring. Stable isotope analysis revealed significant assimilation of diatom-derived materials that was important for the growth of D. magna populations. Our results confirm the applicability of stable isotope approaches for clarifying the contribution of different food algae and elucidate the importance of food quality for growth of D. magna individuals and populations. Furthermore, we expect that stable isotope analysis will help to further precisely examine the contribution of prey to predators or grazers in controlled experiments.  相似文献   

16.
Organisms are exposed to multiple biotic and abiotic environmental stressors, which can influence the dynamics of individual populations and communities. Populations may also genetically adapt to both natural (e.g. disease) and anthropogenic (e.g. chemical pollution) stress. In the present study, we studied fitness consequences of exposure to both a parasite (i.e. biotic) and a pesticide (i.e. abiotic) for the water flea Daphnia. In addition, we investigated whether these fitness consequences change through time as a population evolves. Thus, we exposed Daphnia magna clones, hatched from dormant eggs isolated from different time layers of a natural dormant egg bank, to the parasite Pasteuria ramosa and the insecticide diazinon in a multifactorial experiment. While our experimental treatments for unknown reasons failed to induce disease symptoms in the Daphnia, we did observe a reduced survival of D. magna when simultaneously exposed to both the parasite and the pesticide. No increased mortality upon exposure to individual stressors was observed. We did not observe an evolutionary change in fitness response of the Daphnia clones hatched from different time horizons upon exposure to stressors.  相似文献   

17.
18.
Maternal age is generally known to be negatively correlated with the lifespan of offspring in several animal models including yeast, rotifers, flies, and possibly in humans. However, several reports have shown positive effects of parental age on offspring lifespan. Thus, there was a need to investigate further the inconsistent results on the effect of parental age on lifespan. In this study, the effects of parental age on offspring fitness and lifespan were examined by using Drosophila melanogaster. The lifespan of offspring from old parents was significantly increased compared with that of the young counterparts in the Canton‐S (CS) strain but not in other D. melanogaster strains, such as Oregon‐R (OR) and w1118. To find out why the lifespan is increased in the offspring from old parents in CS flies, fitness components that could modulate lifespan were examined in CS flies. Egg weight and body weight were reduced by parental aging and the offspring of old fathers or old mothers developed faster than that of the young. In addition, the offspring of old parents had increased resistance to oxidative and heat shock stresses. However, reproductive capacity, mating preference, and food intake were unaffected by parental aging. These results indicate that parental aging in CS strain D. melanogaster has beneficial effects on the lifespan and fitness of offspring. The presence of strain‐specific manner effects suggests that genetic background might be a significant factor in the parental age effect.  相似文献   

19.
20.
《Biological Control》2013,64(3):237-245
We examined the effects of a supplemental diet mixture (SDM) and its individual ingredients (sucrose, yeasts, and toasted soy flour) on the survivorship, growth, and development of a cursorial spider, Hibana futilis Banks (Anyphaenidae). Some treatments included limited numbers of Helicoverpa zea eggs, a favored prey. This approach highlighted the relative nutritional contributions of the supplemental diet ingredients, especially under conditions of prey limitation, and showed whether these spiders could be reared on minimal prey augmented with supplemental diet. Spiders fed either 5 or 15 eggs became prey-limited during their first and second molts, respectively. When deprived of prey but provisioned with either sucrose or SDM, spiders persisted as first instar nymphs for weeks, but while sucrose-fed nymphs never molted, those fed SDM typically molted 2–3 times. When SDM was added to the diet, spiders that had fed on as few as 50 eggs could reproduce successfully. Binary mixtures of sucrose plus either baker’s yeast (Saccharomyces cerevisiae Meyen ex E.C. Hansen) or toasted soy flour were more effective in promoting growth and development in prey-limited spiders than any of the three ingredients of SDM alone. Active baker’s yeast was more effective than dried powdered brewer’s yeast at supporting development. These results suggest two possibilities for managing cursorial spiders: (1) Supplemental diet mixtures could be applied as a food spray to promote their conservation in crops; and, (2) A mass rearing diet could be made from a minimal amount of prey plus two or three inexpensive, supplemental diet ingredients.  相似文献   

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