Dietary antioxidants, lipid peroxidation and plumage colouration in nestling blue tits Cyanistes caeruleus

Carotenoid pigments are responsible for many of the red, yellow and orange plumage and integument traits seen in birds. One idea suggests that since carotenoids can act as antioxidants, carotenoid-mediated colouration may reveal an individual's ability to resist oxidative damage. In fact, there is currently very little information on the effects of most dietary-acquired antioxidants on oxidative stress in wild birds. Here, we assessed the impacts on oxidative damage, plasma antioxidants, growth and plumage colouration after supplementing nestling blue tits Cyanistes caeruleus with one of three diets; control, carotenoid treatment or α-tocopherol treatment. Oxidative damage was assessed by HPLC analysis of plasma levels of malondialdehyde (MDA), a by-product of lipid peroxidation. Contrary to predictions, we found no differences in oxidative damage, plumage colouration or growth rate between treatment groups. Although plasma lutein concentrations were significantly raised in carotenoid-fed chicks, α-tocopherol treatment had no effect on concentrations of plasma α-tocopherol compared with controls. Interestingly, we found that faster growing chicks had higher levels of oxidative damage than slower growing birds, independent of treatment, body mass and condition at fledging. Moreover, the chromatic signal of the chest plumage of birds was positively correlated with levels of MDA but not plasma antioxidant concentrations: more colourful nestlings had higher oxidative damage than less colourful individuals. Thus, increased carotenoid-mediated plumage does not reveal resistance to oxidative damage for nestling blue tits, but may indicate costs paid, in terms of oxidative damage. Our results indicate that the trade-offs between competing physiological systems for dietary antioxidants are likely to be complex in rapidly developing birds. Moreover, interpreting the biological relevance of different biomarkers of antioxidant status represents a challenge for evolutionary ecology.     

Aggressive behavior of the male parent predicts brood sex ratio in a songbird

Brood sex ratio is often affected by parental or environmental quality, presumably in an adaptive manner that is the sex that confers higher fitness benefits to the mother is overproduced. So far, studies on the role of parental quality have focused on parental morphology and attractiveness. However, another aspect, the partner’s behavioral characteristics, may also be expected to play a role in brood sex ratio adjustment. To test this hypothesis, we investigated whether the proportion of sons in the brood is predicted by the level of territorial aggression displayed by the father, in the collared flycatcher (Ficedula albicollis). The proportion of sons in the brood was higher in early broods and increased with paternal tarsus length. When controlling for breeding date and body size, we found a higher proportion of sons in the brood of less aggressive fathers. Male nestlings are more sensitive to the rearing environment, and the behavior of courting males may often be used by females to assess their future parental activity. Therefore, adjusting brood sex ratio to the level of male aggression could be adaptive. Our results indicate that the behavior of the partner could indeed be a significant determinant in brood sex ratio adjustment, which should not be overlooked in future studies.     

Growth conditions affect carotenoid-based plumage coloration of great tit nestlings

 Carotenoid-based integument colour in animals has been hypothesised to signal individual phenotypic quality because it reliably reflects either foraging efficiency or health status. We investigated whether carotenoid-derived yellow plumage coloration of fledgling great tits (Parus major) reflects their nestling history. Great tit fledglings reared in a poor year (1998) or in the urban habitat were less yellow than these reared in a good year (1999) or in the forest. The origin of nestlings also affected their coloration since nestlings from a city population did not improve their coloration when transferred to the forest. Brood size manipulation affected fledgling colour, but only in the rural population, where nestlings from reduced broods developed more yellow coloration than nestlings from increased and control broods. Effect of brood size manipulation on fledgling plumage colour was independent of the body mass, indicating that growth environment affects fledgling body mass and plumage colour by different pathways. Received: 20 March 2000 / Accepted in revised form: 4 September 2000     

Effects of early developmental conditions on innate immunity are only evident under favourable adult conditions in zebra finches

Long-term effects of unfavourable conditions during development can be expected to depend on the quality of the environment experienced by the same individuals during adulthood. Yet, in the majority of studies, long-term effects of early developmental conditions have been assessed under favourable adult conditions only. The immune system might be particularly vulnerable to early environmental conditions as its development, maintenance and use are thought to be energetically costly. Here, we studied the interactive effects of favourable and unfavourable conditions during nestling and adult stages on innate immunity (lysis and agglutination scores) of captive male and female zebra finches (Taeniopygia guttata). Nestling environmental conditions were manipulated by a brood size experiment, while a foraging cost treatment was imposed on the same individuals during adulthood. This combined treatment showed that innate immunity of adult zebra finches is affected by their early developmental conditions and varies between both sexes. Lysis scores, but not agglutination scores, were higher in individuals raised in small broods and in males. However, these effects were only present in birds that experienced low foraging costs. This study shows that the quality of the adult environment may shape the long-term consequences of early developmental conditions on innate immunity, as long-term effects of nestling environment were only evident under favourable adult conditions.     

Frugivory is associated with low measures of plasma oxidative stress and high antioxidant concentration in free-ranging bats

Oxidative stress—an imbalance between reactive pro- and neutralising antioxidants—damages cell structures and impairs fitness-relevant traits such as longevity and reproduction. Theory predicts that feeding on diets with high antioxidant content such as fruits should reduce oxidative stress; however, there is no support of this idea in free-ranging mammals. Bats cover a large variety of ecological niches, and therefore, we asked if measures of oxidative stress are lower in species with fruit diets. We measured reactive oxygen metabolites (ROM) representing total pro-oxidants produced and antioxidants in the plasma of 33 Neotropical bat species. Species with a fruit diet showed the lowest level of ROM and the highest concentration of antioxidants, followed by omnivorous and animalivorous species. Potentially, frugivorous species ingest more antioxidants with food and thus are able to neutralise more pro-oxidants than species not feeding on fruits, resulting in an overall lower level of oxidative stress. We therefore showed for the first time that measures of oxidative stress vary according to diets in free-ranging mammals.     

Condition-dependent expression of melanin-based coloration in the Eurasian kestrel

Melanin is the most common pigment in animal integuments and is responsible for some of the most striking ornaments. A central tenet of sexual selection theory states that melanin-based traits can signal absolute individual quality in any environment only if their expression is condition-dependent. Significant costs imposed by an ornament would ensure that only the highest quality individuals display the most exaggerated forms of the signal. Firm evidence that melanin-based traits can be condition-dependent is still rare in birds. In an experimental test of this central assumption, we report condition-dependent expression of a melanin-based trait in the Eurasian kestrel (Falco tinnunculus). We manipulated nestling body condition by reducing or increasing the number of nestlings soon after hatching. A few days before fledging, we measured the width of sub-terminal black bands on the tail feathers. Compared to nestlings from enlarged broods, individuals raised in reduced broods were in better condition and thereby developed larger sub-terminal bands. Furthermore, in 2?years, first-born nestlings also developed larger sub-terminal bands than their younger siblings that are in poorer condition. This demonstrates that expression of melanin-based traits can be condition-dependent.     

The effects of mating status and time since mating on female sex pheromone levels in the rice leaf bug,Trigonotylus caelestialium

Although mating status affects future mating opportunities, the biochemical changes that occur in response to mating are not well understood. This study investigated the effects of mating status on the quantities of sex pheromone components found in whole-body extracts and volatile emissions of females of the rice leaf bug, Trigonotylus caelestialium. When sampled at one of four time points within a 4-day postmating period, females that had copulated with a male had greater whole-body quantities of sex pheromone components than those of virgin females sampled at the same times. The quantities of sex pheromone components emitted by virgin females over a 24-h period were initially high but then steadily decreased, whereas 24-h emissions were persistently low among mated females when measured at three time points within the 4 days after mating. As a result, soon after mating, the mated females emitted less sex pheromones than virgin females, but there were no significant differences between mated and virgin females at the end of the experiment. Thus, postmating reduction in the rate of emission of sex pheromones could explain previously observed changes in female attractiveness to male T. caelestialium.     

Effects of bifenthrin on Daphnia magna during chronic toxicity test and the recovery test

IntroductionWiththedevelopmentandapplicationofnewpesticide ,insecticidehasgreatlyreducedtheharmofpesttocrops .Bifenthrinisaneffectivepyrethroidinsecticideandacaricideagainstawiderangeofinsectpests ,anditisverypoisonoustomammal,aquatic .Thisinsecticideiswi…     

The reproductive choices of eavesdropping female black-capped chickadees,<Emphasis Type="Italic"> Poecile atricapillus</Emphasis>

In animals where males engage in signalling interactions, females might evaluate male–male contests to inform their reproductive choices. We used interactive playback to engage territorial male black-capped chickadees (Poecile atricapillus) of known dominance status in countersinging contests with an aggressive or submissive opponent. Previous analysis of these data showed that high-ranking males who received aggressive playback were more likely to be cuckolded. Here we describe the particular reproductive decisions of females whose partners received aggressive versus submissive playback. The proportion of extra-pair young per brood was higher for females paired to high-ranking males that received aggressive playback compared to submissive playback, and similar to levels in broods of females paired to low-ranking males. We found no strong predictors of whether high-ranking subjects lost paternity following aggressive playback. Females usually preferred extra-pair sires with high dominance status. When females had extra-pair fertilizations with low-ranking males, females chose males who had received submissive playback. We conclude that females mated to aggressive-playback, high-ranking males pursued mixed mating strategies similar to those of females mated to low-ranking males. Our results support the idea that male performance in song contests may influence multiple aspects of female reproductive choices.     

A critical number of workers in a honeybee colony triggers investment in reproduction

Social insect colonies, like individual organisms, must decide as they develop how to allocate optimally their resources among survival, growth, and reproduction. Only when colonies reach a certain state do they switch from investing purely in survival and growth to investing also in reproduction. But how do worker bees within a colony detect that their colony has reached the state where it is adaptive to begin investing in reproduction? Previous work has shown that larger honeybee colonies invest more in reproduction (i.e., the production of drones and queens), however, the term ‘larger’ encompasses multiple colony parameters including number of adult workers, size of the nest, amount of brood, and size of the honey stores. These colony parameters were independently increased in this study to test which one(s) would increase a colony’s investment in reproduction via males. This was assayed by measuring the construction of drone comb, the special type of comb in which drones are reared. Only an increase in the number of workers stimulated construction of drone comb. Colonies with over 4,000 workers began building drone comb, independent of the other colony parameters. These results show that attaining a critical number of workers is the key parameter for honeybee colonies to start to shift resources towards reproduction. These findings are relevant to other social systems in which a group’s members must adjust their behavior as a function of the group’s size.     

Moorhens have an internal representation of their own eggs

How do birds recognize their own eggs? Do they have a stored template for their own egg characteristics, or do they use another mechanism? Intraspecific brood parasitism is considered to be an additional reproductive tactic where females can increase their own reproductive success. Because of the costs involved in rearing young that are not their own, it will pay females to detect and reject the eggs of a parasite, although it is not known how they do this. Here, we show experimentally that moorhens will cease laying in a nest when their first egg is replaced with another hen’s egg but not when it is replaced with their own egg taken from an earlier clutch. This provides good evidence that birds have an internal representation of their own eggs and use this in decisions about whether to reject foreign eggs.     

Oxidative stress related enzymes in response to chromium (Ⅵ) toxicity in Oxya chinensis ( Orthoptera : Acridoidae)

The toxic effects of Cr（Vl） on antioxidant enzymes of Oxya chinensis（Orthoptera： Acridoidae） were determined. Changes in the activities of the antioxidant enzymes superoxide dismutase（SOD）, catalase（CAT）, and guaiacol peroxidase（GPx） were measured in O. chinensis insects injected with Cr（VI）. Fifth-nymphs of O. chinensis insects were injected with Cr（VI） with different concentrations （0, 75, 150, 225, 300, 375, 450 mg/kg of body weight）. The results showed that Cr（VI） led to the change of SOD, CAT, and GPx activities at different concentrations, which revealed that： （1） The oxidative stress of SOD increased with the increase of Cr （VI） concentration. （2） With the increase of Cr （VI） concentrations, CAT activities for females increased at lower concentrations, but decreased at higher concentration range, which indicated that antioxidant system of O. chinensis was not influenced by the presence of Cr （VI）. A very similar response to Cr（VI） effect for males indicated that Cr（VI） concentrations were not high enough to damage O. chinensis in terms of CAT. （3） The GPx activity for females increased in all treatments, which revealed that the damage power of Cr（VI） was increased with the increase of Cr（Vi） concentrations in terms of GPx, but the effect was not so remarkable. There was not a consistent trend of GPx activities for males in all treatments of Cr（VI）. Cr（VI）-induced changes in antioxidant enzymes were different for SOD, CAT and GPx, of which the tendency was that activities generally changed with increase of concentrations of Cr（VI） suggesting SOD, CAT, and GPx could serve as indices of oxidative stress to some extent.     

重金属对秀丽隐杆线虫繁殖的影响

为了探究重金属单独及联合暴露对秀丽隐杆线虫(Caenorhabditis elegans)繁殖的影响及其作用机制,采用96孔板液相暴露试验,以环境相关浓度(0.1~50.0 μg/L)的Cd、Hg、Pb暴露同步化处理秀丽隐杆线虫,24 h后统计其怀卵数及阴门畸形率,以及连续记录72 h内子一代秀丽隐杆线虫的个体数,最后利用2×2析因设计方差分析阐明重金属的两两联合作用模式. 结果表明:与对照组相比,Cd、Hg、Pb单独及联合暴露对秀丽隐杆线虫的繁殖具有显著抑制作用,ρ(Cd)为50.0 μg/L、ρ(Hg)为10.0 μg/L、ρ(Pb)为50.0 μg/L暴露组秀丽隐杆线虫子一代数量分别降低了43.5%、33.8%、51.0%;Cd-Hg暴露组〔当ρ(Cd)、ρ(Hg)分别为50.0、10.0 μg/L时〕、Hg-Pb暴露组〔当ρ(Hg)、ρ(Pb)分别为10.0、50.0 μg/L时〕、Cd-Pb暴露组〔当ρ(Cd)、ρ(Pb)分别为50.0、50.0 μg/L时〕秀丽隐杆线虫子一代个体数分别降低了44.7%、61.0%、53.3%. 进一步研究发现,Cd、Hg、Pb单独及联合暴露会引起秀丽隐杆线虫子宫内受精卵数量降低以及产卵器阴门结构畸形率升高. 2×2析因设计方差分析结果发现,Cd、Hg、Pb两两联合暴露对秀丽隐杆线虫的繁殖表现为没有交互作用或者交互方式为拮抗. 研究显示,秀丽隐杆线虫子宫内怀卵数的降低是其子一代数量显著减少的主要原因,而阴门结构的损伤可能使产卵行为受损,从而进一步加剧重金属对秀丽隐杆线虫繁殖的抑制作用.      

邻苯二甲酸二丁酯(DBP)对蒙古裸腹溞的毒性及其跨代影响

邻苯二甲酸二丁酯（DBP）是一种环境内分泌干扰物,可以通过城市生活污水和工业废水排放等方式迁移进入水域生态系统,从而对食物链中各营养级生物造成潜在危害.为阐明DBP对经海水驯化的枝角类生物生长、发育及生殖的影响,本文研究了DBP对蒙古裸腹溞（Moina mongolica）的急性毒性和5个世代的跨代毒性效应.结果表明,DBP对蒙古裸腹溞24 h和48 h的半致死浓度分别为8.36 mg·L^-1和6.34 mg·L^-1,安全浓度为1.09 mg·L^-1.DBP浓度在0.2~1.00 mg·L^-1时,对蒙古裸腹溞存在跨代毒性效应.DBP处理组F3代溞的平均寿命、总生殖量、每窝生殖量、首窝生殖量和种群增长等指标与对照组相比出现下降,而且DBP处理组F4代溞的平均寿命、总生殖量和首窝生殖量与对照组相比同样出现下降.本研究结果可为DBP对枝角类毒性研究提供理论依据.     

Acute and chronic toxic effects of Pb2+ on polychaete Perinereis aibuhitensis：Morphological changes and responses of the antioxidant system

Perinereis aibuhitensis was used to assess adverse biological effects caused by acute and chronic Pb2＋exposure in artificial seawater under controlled laboratory conditions. In 96-hr acute toxicity experiments,the morphological changes showed a positive time/dose-dependent tendency,and the 96-hr LC50 value of Pb2＋was 686.41 mg/L. The responses of enzymatic and non-enzymatic antioxidants in tissues including catalase（CAT）,peroxidase（POD）,superoxide dismutase（SOD）,glutathione peroxidase（GSH-PX）,malondialdehyde（MDA） and the content of total soluble protein（TSP）,were investigated on days 1,4,7 and 10 after Pb2＋exposure under chronic toxicity testing. Results showed that the activation of the antioxidant system in P. aibuhitensis depended on the Pb2＋concentration and the duration of exposure time.Specifically,POD and SOD activities were induced on the first day of the exposure and decreased to the control level on day 10 after exposure. Therefore,these two indexes could be used to indicate oxidative stress associated with P. aibuhitensis exposure to Pb2＋.     

Brood comb as a humidity buffer in honeybee nests

Adverse environmental conditions can be evaded, tolerated or modified in order for an organism to survive. During their development, some insect larvae spin cocoons which, in addition to protecting their occupants against predators, modify microclimatic conditions, thus facilitating thermoregulation or reducing evaporative water loss. Silk cocoons are spun by honeybee (Apis mellifera) larvae and subsequently incorporated into the cell walls of the wax combs in which they develop. The accumulation of this hygroscopic silk in the thousands of cells used for brood rearing may significantly affect nest homeostasis by buffering humidity fluctuations. This study investigates the extent to which the comb may influence homeostasis by quantifying the hygroscopic capacity of the cocoons spun by honeybee larvae. When comb containing cocoons was placed at high humidity, it absorbed 11% of its own mass in water within 4 days. Newly drawn comb composed of hydrophobic wax and devoid of cocoons absorbed only 3% of its own mass. Therefore, the accumulation of cocoons in the comb may increase brood survivorship by maintaining a high and stable humidity in the cells.     

Pheromone-modulated behavioral suites influence colony growth in the honey bee (<Emphasis Type="Italic">Apis mellifera</Emphasis>)

The success of a species depends on its ability to assess its environment and to decide accordingly which behaviors are most appropriate. Many animal species, from bacteria to mammals, are able to communicate using interspecies chemicals called pheromones. In addition to exerting physiological effects on individuals, for social species, pheromones communicate group social structure. Communication of social structure is important to social insects for the allocation of its working members into coordinated suites of behaviors. We tested effects of long-term treatment with brood pheromone on suites of honey bee brood rearing and foraging behaviors. Pheromone-treated colonies reared significantly greater brood areas and more adults than controls, while amounts of stored pollen and honey remained statistically similar. Brood pheromone increased the number of pollen foragers and the pollen load weights they returned. It appeared that the pheromone-induced increase in pollen intake was directly canalized into more brood rearing. A two-way pheromone priming effect was observed, such that some workers from the same age cohorts showed an increased and extended capacity to rear larvae, while others were recruited at significantly younger ages into pollen-specific foraging. Brood pheromone affected suites of nursing and foraging behaviors allocating worker and pollen resources associated with an important fitness trait, colony growth.     

微塑料对大型溞摄食和抗氧化防御系统的影响

微塑料（Microplastics,MPs）作为一种新兴环境污染物,其环境效应已引起了广泛关注.为揭示不同粒径微塑料对淡水生物摄食和抗氧化防御系统的影响规律,以100 nm、5 μm、50 μm聚苯乙烯（Polystyrene,PS）微塑料为研究对象,以大型溞（Daphnia magna）为受试生物,研究微塑料在大型溞体内的积累量、停留量,以及对大型溞滤水率、摄食率以及抗氧化防御系统的影响.结果表明:3种粒径的微塑料均可被大型溞摄入,100 nm和5 μm的微塑料在大型溞体内的积累量和停留量均高于50 μm的微塑料,50 μm的微塑料主要黏附在胸肢处,而100 nm和5 μm的微塑料能在大型溞肠道中积累.暴露于3种粒径的微塑料后,大型溞的滤水率和摄食率较对照组分别降低了50.7%±9.5%和39.2%±10.7%.3种粒径的微塑料均能促进大型溞体内超氧化物歧化酶、过氧化氢酶活性的升高,并诱导丙二醛含量升高,导致大型溞氧化损伤.研究显示,微塑料损伤大型溞的食物过滤器,堵塞消化道,降低其滤水率、摄食率,造成大型溞氧化损伤,微塑料暴露对大型溞的摄食和抗氧化防御系统造成了不利影响.      

Oxidative stress related enzymes in response to chromium (Ⅵ) toxicity in Oxya chinensis ( Orthoptera : Acridoidae)

The toxic effects of Cr(Ⅵ) on antioxidant enzymes of Oxya chinensis(Orthoptera: Acridoidae) were determined. Changes in the activities of the antioxidant enzymes superoxide dismutase(SOD), catalase(CAT), and guaiacol peroxidase(GPx) were measured in O. chinensis insects injected with Cr(Ⅵ). Fifth-nymphs of O. chinensis insects were injected with Cr(Ⅵ) with different concentrations (0, 75, 150, 225, 300, 375, 450 mg/kg of body weight). The results showed that Cr(Ⅵ) led to the change of SOD, CAT, and GPx activities at different concentrations, which revealed that: (1) The oxidative stress of SOD increased with the increase of Cr (Ⅵ)concentration. (2) With the increase of Cr (Ⅵ) concentrations, CAT activities for females increased at lower concentrations, but decreased at higher concentration range, which indicated that antioxidant system of O. chinensis was not influenced by the presence of Cr (Ⅵ). A very similar response to Cr(Ⅵ) effect for males indicated that Cr(Ⅵ) concentrations were not high enough to damage O. chinensis in terms of CAT. (3) The GPx activity for females increased in all treatments, which revealed that the damage power of Cr(Ⅵ)was increased with the increase of Cr(Ⅵ) concentrations in terms of GPx, but the effect was not so remarkable. There was not a consistent trend of GPx activities for males in all treatments of Cr(Ⅵ). Cr(Ⅵ)-induced changes in antioxidant enzymes were different for SOD, CAT and GPx, of which the tendency was that activities generally changed with increase of concentrations of Cr(Ⅵ) suggesting SOD, CAT, and GPx could serve as indices of oxidative stress to some extent.