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The energy cost of adaptive immune activation in endotherms is typically quantified from changes in resting metabolic rate following exposure to a novel antigen. An implicit assumption of this technique is that all variation in energy costs following antigenic challenge is due solely to adaptive immunity, while ignoring potential changes in the energy demands of ongoing bodily functions. We critically assess this assumption by measuring both basal metabolic rate (BMR) and exercise-induced maximal metabolic rate (MMR) in house sparrows before and after the primary and two subsequent vaccinations with either saline (sham) or two novel antigens (keyhole limpet haemocyanin and sheep red blood cells; KLH and SRBC, respectively). We also examined the effect of inducing male breeding levels of testosterone (T) on immune responses and their metabolic costs in both males and females. Although there was a moderate decrease in KLH antibody formation in T-treated birds, there was no effect of T on BMR, MMR or immunity to SRBC. There was no effect of vaccination on BMR but, surprisingly, all vaccinated birds maintained MMR better than sham-treated birds as the experiment progressed. Our findings caution against emphasizing energy costs or nutrient diversion as being responsible for reported fitness reductions following activation of adaptive immunity.

Life history theory suggests that species experiencing high extrinsic mortality rates allocate more resources toward reproduction relative to self-maintenance and reach maturity earlier ('fast pace of life') than those having greater life expectancy and reproducing at a lower rate ('slow pace of life'). Among birds, many studies have shown that tropical species have a slower pace of life than temperate-breeding species. The pace of life has been hypothesized to affect metabolism and, as predicted, tropical birds have lower basal metabolic rates (BMR) than temperate-breeding birds. However, many temperate-breeding Australian passerines belong to lineages that evolved in Australia and share 'slow' life-history traits that are typical of tropical birds. We obtained BMR from 30 of these 'old-endemics' and ten sympatric species of more recently arrived passerine lineages (derived from Afro-Asian origins or introduced by Europeans) with 'faster' life histories. The BMR of 'slow' temperate-breeding old-endemics was indistinguishable from that of new-arrivals and was not lower than the BMR of 'fast' temperate-breeding non-Australian passerines. Old-endemics had substantially smaller clutches and longer maximal life spans in the wild than new arrivals, but neither clutch size nor maximum life span was correlated with BMR. Our results suggest that low BMR in tropical birds is not functionally linked to their 'slow pace of life' and instead may be a consequence of differences in annual thermal conditions experienced by tropical versus temperate species.

Endemic Australian mammal species are exposed to pesticides used for locust control as they occupy the same habitat as the target insect. The authors examined the impact of an ultra-low volume formulation of the organophosphorous insecticide fenitrothion (O,O-dimethyl-O-[3-methyl-4-nitrophenol]-phosphorothioate) on a suite of physiological measures that affect the ability of animals to survive in free-living conditions: locomotory and thermogenic functions, metabolic performance, body mass, and hematocrit and hemoglobin levels. Plasma and brain cholinesterase activity in relation to time since exposure to pesticide were also determined. An orally applied dose of 90 mg kg(-1) fenitrothion reduced running endurance in the stripe-faced dunnart, Sminthopsis macroura, by 80% the day after exposure concomitantly with a reduction of approximately 50% in plasma and 45% in brain acetylcholinesterase activity. These adverse effects disappeared by 10 d postexposure. Maximal metabolic rates reached during running were unaffected by pesticide, as were body mass and hemoglobin and hematocrit levels. Maximal cold-induced metabolic rate (measured as peak 2 min metabolic rate attained during cold exposure), time taken to reach peak metabolic rate on cold exposure, cumulative total oxygen consumed during shivering thermogenesis, and body temperature before and after cold exposure were unaffected by fenitrothion. Dunnart rectal temperatures showed a reduction of up to 5 °C after exposure to fenitrothion but returned to pre-exposure levels by 10 d postdose. Such physiological compromises in otherwise asymptomatic animals demonstrate the importance of considering performance-based measures in pesticide risk assessments., (© 2015 SETAC.)

Attention is required during speech perception to focus processing resources on critical information. Previous research has shown that bilingualism modifies attentional processing in nonverbal domains. The current study used event-related potentials (ERPs) to determine whether bilingualism also modifies auditory attention during speech perception. We measured attention to word onsets in spoken English for monolinguals and Chinese-English bilinguals. Auditory probes were inserted at four times in a continuous narrative: concurrent with word onset, 100 ms before or after onset, and at random control times. Greater attention was indexed by an increase in the amplitude of the early negativity (N1). Among monolinguals, probes presented after word onsets elicited a larger N1 than control probes, replicating previous studies. For bilinguals, there was no N1 difference for probes at different times around word onsets, indicating less specificity in allocation of attention. These results suggest that bilingualism shapes attentional strategies during English speech comprehension.

This article is part of a Special Issue "SBN 2014". In most vertebrate species, glucocorticoid levels and stress sensitivity vary in relation to season and life-history stage. In birds, baseline corticosterone (CORT) and stress sensitivity are typically highest while breeding and decrease substantially during moult. Because elevated CORT adversely affects protein synthesis, moult-related CORT suppression is thought to be necessary for forming high-quality feathers. Surprisingly, some passerine species lack moult-related CORT suppression, but these are distinguished by having slow rates of moult and being opportunistic breeders. We examined baseline and stress-induced CORT levels in an opportunistically breeding Australian passerine, the white-plumed honeyeater (Lichenostomus penicillatus). Although this species has a slower moult rate than high-latitude breeders, it differs little from north-temperate passerines. Neither baseline nor stress-induced CORT levels varied with season (winter, spring or summer), sex or moult status in adult birds. While breeding tended to be highest in early spring through late summer, laparotomies revealed only limited reduction in testicular size in males the year round. In all but one sampling period, at least some females displayed follicular hierarchy. Breeding usually coincides with outbreaks of phytophagous insects, which can happen at any time of the year. This results in moult/breeding overlap when infestations occur in late spring or summer. The ability of this species to moult and breed at the same time while having breeding-levels of CORT demonstrates that CORT suppression is not a prerequisite for synthesis of high-quality feathers. An experimental design incorporating moulting and non-moulting phenotypes is suggested to test the functional significance of CORT suppression in other species., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The relative contribution of genetic and environmental factors in determining variation in life-history traits is of central interest to evolutionary biologists, but the physiological mechanisms underlying these traits are still poorly understood. Here we experimentally demonstrate opposing effects of nutritional stress on immune function, endocrine physiology, parental care, and reproduction between red and black head-color morphs of the Gouldian finch (Erythrura gouldiae). Although the body condition of black morphs was largely unaffected by diet manipulation, red birds were highly sensitive to dietary changes, exhibiting considerable within-individual changes in condition and immune function. Consequently, nutritionally stressed red birds delayed breeding, produced smaller broods, and reared fewer and lower-quality foster offspring than black morphs. Differences in offspring quality were largely due to morph-specific differences in parental effort: red morphs reduced parental provisioning, whereas black morphs adaptively elevated their provisioning effort to meet the increased nutritional demands of their foster brood. Nutritionally stressed genetic morphs also exhibited divergent glucocorticoid responses. Black morphs showed reduced corticosterone-binding globulin (CBG) concentrations and increased levels of free corticosterone, whereas red morphs exhibited reduced free corticosterone levels and elevated CBG concentrations. These opposing glucocorticoid responses highlight intrinsic differences in endocrine sensitivities and plasticity between genetic morphs, which may underlie the morph-specific differences in condition, behavior, and reproduction and thus ultimately contribute to the evolution and maintenance of color polymorphism.

Recent event-related potential (ERP) evidence demonstrates that adults employ temporally selective attention to preferentially process the initial portions of words in continuous speech. Doing so is an effective listening strategy since word-initial segments are highly informative. Although the development of this process remains unexplored, directing attention to word onsets may be important for speech processing in young children who would otherwise be overwhelmed by the rapidly changing acoustic signals that constitute speech. We examined the use of temporally selective attention in 3- to 5-year-old children listening to stories by comparing ERPs elicited by attention probes presented at four acoustically matched times relative to word onsets: concurrently with a word onset, 100 ms before, 100 ms after, and at random control times. By 80 ms, probes presented at and after word onsets elicited a larger negativity than probes presented before word onsets or at control times. The latency and distribution of this effect is similar to temporally and spatially selective attention effects measured in adults and, despite differences in polarity, spatially selective attention effects measured in children. These results indicate that, like adults, preschool aged children modulate temporally selective attention to preferentially process the initial portions of words in continuous speech., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Event-related potential (ERP) evidence indicates that listeners selectively attend to word onsets in continuous speech, but the reason for this preferential processing is unknown. The current study measured ERPs elicited by syllable onsets in an artificial language to test the hypothesis that listeners direct attention to word onsets because their identity is unpredictable. Both before and after recognition training, participants listened to a continuous stream of six nonsense words arranged in pairs, such that the second word in each pair was completely predictable. After training, first words in pairs elicited a larger negativity beginning around 100 ms after onset. This effect was not evident for the completely predictable second words in pairs. These results suggest that listeners are most likely to attend to the segments in speech that they are least able to predict., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Two studies were carried out to examine the impact of maternal fipronil exposure on embryonic and offspring development. In the first study, breeding female zebra finches were orally dosed with single sublethal levels of fipronil (1, 5, and 10 mg/kg body weight) to determine behavioural and developmental consequences on chicks following maternal pesticide exposure. Significant levels of fipronil and fipronil-sulfone residues were detected in eggs laid by females in all dosed groups, however, these were undetectable in eggs laid 13 days after treatment. The level of sulfone detected in eggs was consistently higher than that of the parent fipronil compound. Of the seven eggs laid in the treatment groups, only one (14%) chick hatched and this was from the lowest dose group. This chick was severely underdeveloped at 10 days of age in comparison to control chicks and fiproles were detected in brain, liver, and adipose tissues collected following euthanasia of this individual. In contrast, there was 100% hatchability of control group eggs and all chicks fledged nests on schedule. In the second study, domestic chicken eggs were injected with 5.5, 17.5, and 37.5 mg/kg egg weight of fipronil directly into the yolk sac on day 12 of incubation. Treatment did not affect hatching success, however, behavioural and developmental abnormalities were observed in hatchlings from the highest dose group. These chicks also demonstrated reduced feeding rates, as indicated by reduced body mass at 48 h period post hatch. Both fipronil and fipronil-sulfone residues were detected in brain and liver tissue of hatchlings at all pesticide dose levels tested.

The scarcity of information on the effects of pesticides on native Australian vertebrates constrains the development of biologically relevant risk assessments in Australia for the registration of pesticides. The concern that endemically old and unique Australian vertebrate fauna might display high sensitivity to pesticides used for locust control provoked examination of the acute oral toxicity of the organophosphorus pesticide fenitrothion for the fat-tailed dunnart, Sminthopsis crassicaudata (Gould 1844), and the stripe-faced dunnart, S. macroura (Gould 1845). By using the up-and-down method for determining acute oral toxicity, S. crassicaudata and S. macroura were found to have estimated median lethal doses (LD50s) of 129 mg/kg (95% confidence interval [CI] = 74.2-159.0) and 97 mg/kg (95% CI = 88.3-120.0), respectively. These values are 10 to 14 times lower than the reported LD50 values for a similar-sized eutherian mammal, Mus musculus (L. 1758; LD50 = 1,100-1,400 mg/kg) and lower than all other reported mammalian LD50 values. Such wide interspecific variation in sensitivity to fenitrothion may be a consequence of underlying differences in the metabolic pathway for fenitrothion detoxification in mammals and a possible explanation for the increased toxicity of fenitrothion to dunnarts, compared with other mammals, is proposed. The unexpectedly high sensitivity of these Australian marsupials to fenitrothion emphasises the importance of adequately evaluating the risks of pesticides to endemic Australian fauna., (Copyright © 2011 SETAC.)

Fipronil is a phenyl pyrazole insecticide registered for agricultural use in many countries. Avian exposure to fipronil occurs mainly by ingesting contaminated insects or seeds. There is little information regarding the toxicological effects of fipronil in avian species and even less research documenting avian behavioural responses to fipronil ingestion. We examined the effects of a single oral dose of fipronil in northern bobwhite quail, the most fipronil-sensitive species tested to date, in respect to signs of intoxication and the metabolic fate of fipronil. Fipronil-treated birds did not eat or drink following pesticide administration, and as a result lost a significant amount of body mass. Treated birds also appeared withdrawn and did not respond to disturbance within the first hour after treatment. Identifiable signs of fipronil toxicity were not observed until at least 2d after treatment. Chemical analyses indicated a difference between fipronil and fipronil-sulfone residue distribution and bioaccumulation, with significantly higher (30- to 1000-fold) tissue concentrations of the sulfone detected at all time points from 8 to 96 h post-dose in brain, liver and adipose tissues. Tissue sulfone concentrations increased significantly in fipronil-treated birds, peaking at 72 h post-dose. Body mass decreased at all time points in dosed birds. The coincidence of the particular intoxication symptoms with the time course of rise in brain sulfone levels after fipronil dosing gives insight into possible mechanisms of toxicity in this highly sensitive species., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Locusts and grasshoppers cause considerable economic damage to agriculture worldwide. The Australian Plague Locust Commission uses multiple pesticides to control locusts in eastern Australia. Avian exposure to agricultural pesticides is of conservation concern, especially in the case of rare and threatened species. The aim of this study was to evaluate the probability of pesticide exposure of native avian species during operational locust control based on knowledge of species occurrence in areas and times of application. Using presence-absence data provided by the Birds Australia Atlas for 1998 to 2002, we developed a series of generalized linear models to predict avian occurrences on a monthly basis in 0.5 degrees grid cells for 280 species over 2 million km2 in eastern Australia. We constructed species-specific models relating occupancy patterns to survey date and location, rainfall, and derived habitat preference. Model complexity depended on the number of observations available. Model output was the probability of occurrence for each species at times and locations of past locust control operations within the 5-year study period. Given the high spatiotemporal variability of locust control events, the variability in predicted bird species presence was high, with 108 of the total 280 species being included at least once in the top 20 predicted species for individual space-time events. The models were evaluated using field surveys collected between 2000 and 2005, at sites with and without locust outbreaks. Model strength varied among species. Some species were under- or over-predicted as times and locations of interest typically did not correspond to those in the prediction data set and certain species were likely attracted to locusts as a food source. Field surveys demonstrated the utility of the spatially explicit species lists derived from the models but also identified the presence of a number of previously unanticipated species. These results also emphasize the need for special consideration of rare and threatened species that are poorly predicted by presence-absence models. This modeling exercise was a useful a priori approach in species risk assessments to identify species present at times and locations of locust control applications, and to discover gaps in our knowledge and need for further focused data collection.

The effect of fenitrothion exposure on birds was examined by measuring aerobic metabolism, blood hemoglobin content, plasma cholinesterases, and body weight for up to 21 d postdose. Peak metabolic rate was measured in a flight chamber in three-dose groups of house sparrows (Passer domesticus; 100 mg/kg = high, 60 mg/kg = medium, 30 mg/kg = low) and one-dose groups of zebra finches (Taeniopygia guttata; 3 mg/kg) and king quails (Coturnix chinensis; 26 mg/kg). Aerobic metabolism was measured during 1 h of exposure to subfreezing thermal conditions in low-dose house sparrows and king quails (26 mg/kg). Fenitrothion had no effect on metabolic rate during cold exposure or on blood hemoglobin at any time. By contrast, aerobic performance during exercise in sparrows was reduced by 58% (high), 18% (medium), and 20% (low), respectively, 2 d postdose. House sparrows (high) had the longest recovery period for peak metabolic rate (21 d) and plasma cholinesterase activity (14 d). House sparrows (high) and treated king quails had significantly lower myoglobin at 48 h postdose, whereas myoglobin was invariant in zebra finches and house sparrows (medium and low). Cholinesterase was maximally inhibited at 6 h postdose, and had recovered within 24 h, in house sparrows (low), king quails, and zebra finches. Exercise peak metabolic rate in zebra finches and king quails was reduced by 23% at 2 d and 3 d, respectively, despite these birds being asymptomatic in both behavior and plasma cholinesterase activities.

Objective: We hypothesized that a dietary combination of soy with either a probiotic (yoghurt) or a prebiotic (resistant starch) would result in enhanced lipid-lowering effects compared with a control soy diet, possibly via improvements in isoflavone bioavailability., Subjects: Mildly hypercholesterolaemic subjects (men and post-menopausal women) older than 45 years were recruited via the local media. Thirty-six subjects commenced the study; five withdrew., Results: Soy+probiotic significantly decreased total cholesterol (4.7+/-2.0%; P=0.038) and soy+prebiotic significantly decreased total and low-density lipoprotein cholesterol (5.5+/-1.6%; P=0.003 and 7.3+/-2.2%; P=0.005, respectively). The bioavailabilities of daidzein, genistein or equol were not affected by probiotic or prebiotic consumption or associated with lipid changes., Conclusion: Dietary combination of soy with either a probiotic or a prebiotic resulted in significant lipid lowering, not related to isoflavone bioavailability.

Spatially selective attention allows for the preferential processing of relevant stimuli when more information than can be processed in detail is presented simultaneously at distinct locations. Temporally selective attention may serve a similar function during speech perception by allowing listeners to allocate attentional resources to time windows that contain highly relevant acoustic information. To test this hypothesis, event-related potentials were compared in response to attention probes presented in six conditions during a narrative: concurrently with word onsets, beginning 50 and 100 ms before and after word onsets, and at random control intervals. Times for probe presentation were selected such that the acoustic environments of the narrative were matched for all conditions. Linguistic attention probes presented at and immediately following word onsets elicited larger amplitude N1s than control probes over medial and anterior regions. These results indicate that native speakers selectively process sounds presented at specific times during normal speech perception.

Fipronil, a phenyl pyrazole pesticide, is aerially applied in eastern Australia to control locust outbreaks, usually as "Adonis 3UL Insecticide" (BASF), an ultra low (UL) volume formulation containing 0.3% active pesticide. We tested the toxicities of technical-grade fipronil, the Adonis 3UL formulation and its components in zebra finch, a native bird at risk of exposure in locust control regions. We estimated oral-dose LD50 by the Up-and-Down method. Under laboratory conditions, we identified unexpectedly high toxicities due exclusively to diacetone alcohol (DAA), a solvent making up 12.5% of the Adonis 3UL formulation. In contrast, finches were asymptomatic when exposed to 0.3% technical grade fipronil dissolved in a minimum amount of acetone. Depending upon the behaviour and persistence of DAA under field conditions, this formulation of Adonis 3UL may pose a far greater threat to the health of small birds and possibly other vertebrates than expected for fipronil alone.

We measured aerobic metabolism during cold exposure and exercise performance (run duration and oxygen consumption while running at 1 m s(-1)) in the fat-tailed dunnart Sminthopsis crassicaudata, a dasyurid marsupial, before and after ingestion of 30 mg kg(-1) of fenitrothion, an organophosphate (OP) pesticide. Running endurance of OP-exposed animals was less than half that of control animals over the first 3 days after dosing and 55% of control animal endurance on day 5 post-dose. Despite these declines, peak metabolic rate at this running speed (9.3 times basal metabolic rate; BMR) was unaffected by OP exposure. Peak metabolic rate (PMR) and cumulative oxygen consumption during a 1-h exposure to conditions equivalent to -20 degrees C did not differ between OP-treated and control dunnarts, with PMR averaging 11 times BMR. We conclude that fenitrothion-induced exercise fatigue is not due to limitations in oxygen or substrate delivery to muscle or in their uptake per se, but more likely relates to decreased ability to sustain high-frequency neuromuscular function. The persistence of locomotor impairment following OP exposure in otherwise asymptomatic animals emphasizes the importance of using performance-based measures when characterising sublethal effects of pesticide exposure in an ecological context.

We examined the effects of cage size and testosterone (T) levels on basal and peak metabolic rates (BMR and PMR, respectively) and on pectoral and leg muscle masses of male house sparrows (Passer domesticus). Birds were housed either in small birdcages or in flight aviaries for at least 2 weeks prior to the initial metabolic evaluations. They were then implanted with either empty or T-filled silastic capsules and remeasured 5-6 weeks later. Birds treated with single T implants achieved breeding levels (4-6 ng/mL) and one group given double implants reached 10 ng/mL. There was no effect of T on BMR or PMR in any group studied, but there was an effect of caging. Caged birds showed significant reductions in PMR over the course of captivity, whereas PMR in aviary-housed birds were indistinguishable from their free-living counterparts. Testosterone treatment significantly increased leg muscle mass in caged birds, but had no effect on muscle mass in aviary-housed sparrows. We conclude that testosterone has no direct effect on sparrow metabolic rate or muscle mass, but may interact with cage conditions to produce indirect changes to these variables.

Some of the most important information we encounter changes so rapidly that our perceptual systems cannot process all of it in detail. Spatially selective attention is critical for perception when more information than can be processed in detail is presented simultaneously at distinct locations. When presented with complex, rapidly changing information, listeners may need to selectively attend to specific times rather than to locations. We present evidence that listeners can direct selective attention to time points that differ by as little as 500 msec, and that doing so improves target detection, affects baseline neural activity preceding stimulus presentation, and modulates auditory evoked potentials at a perceptually early stage. These data demonstrate that attentional modulation of early perceptual processing is temporally precise and that listeners can flexibly allocate temporally selective attention over short intervals, making it a viable mechanism for preferentially processing the most relevant segments in rapidly changing streams.

Evolutionary theory suggests that alternative colour morphs (i.e. genetically controlled phenotypes) may derive similar fitness under frequency-dependent selection. Here we experimentally demonstrate opposing effects of frequency-dependent social environments on plasma hormone levels (testosterone and corticosterone) and immune function between red- and black-headed male morphs of the Gouldian finch (Erythrura gouldiae). Red-headed males are highly sensitive to changes in the social environment, especially towards the relative density of their own aggressive morph, exhibiting high stress responses and immunosuppression in socially competitive environments. In contrast, the non-aggressive black-headed males follow a more passive strategy that appears to buffer them against social stresses. The differential effect of hormones on aggressive behaviour and immune performance reinforces the contrasting behavioural strategies employed by these colour morphs, and highlights the importance of the social environment in determining the individual basis of behavioural and physiological responses.

Objective: Probiotics and prebiotics that affect gut microflora balance and its associated enzyme activity may contribute to interindividual variation in isoflavone absorption after soy intake, possibly enhancing isoflavone bioavailability. This study examined the effects of the consumption of bioactive yogurt (a probiotic) or resistant starch (a known prebiotic) in combination with high soy intake on soy isoflavone bioavailability., Methods: Using a crossover design, chronic soy consumption was compared with soy plus probiotic yogurt or resistant starch in older male and postmenopausal females (n = 31). Isoflavone bioavailability was assessed at the beginning and end of each 5-wk dietary period by sampling plasma and urine after a standardized soy meal., Results: Chronic soy intake did not significantly affect plasma or urinary isoflavones after the soy meal and there were no significant effects of probiotic or resistant starch treatment. However, there were trends for increased circulating plasma daidzein and genistein after the probiotic treatment and for increased plasma daidzein and genistein 24 h after soy intake with resistant starch treatment. Neither treatment induced or increased equol production, although there was a trend for increased plasma equol in "equol-positive" subjects (n = 12) after probiotic treatment., Conclusion: The weak or absence of effects of probiotic yogurt or resistant starch supplement to a chronic soy diet suggests that gut microflora were not modified in a manner that significantly affected isoflavone bioavailability or metabolism.

Cooperative breeding systems are characterized by nonbreeding helpers that assist breeders in offspring care. However, the benefits to offspring of being fed by parents and helpers in cooperatively breeding birds can be difficult to detect. We offer experimental evidence that helper effects can be obscured by an undocumented maternal tactic. In superb fairy-wrens (Malurus cyaneus), mothers breeding in the presence of helpers lay smaller eggs of lower nutritional content that produce lighter chicks, as compared with those laying eggs in the absence of helpers. Helpers compensate fully for such reductions in investment and allow mothers to benefit through increased survival to the next breeding season. We suggest that failure to consider maternal egg-investment strategies can lead to underestimation of the force of selection acting on helping in avian cooperative breeders.

Huge aggregations of flightless locust nymphs pose a serious threat to agriculture when they reach plague proportions but provide a very visible and nutritious resource for native birds. Locust outbreaks occur in spring and summer months in semiarid regions of Australia. Fenitrothion, an organophosphate pesticide, is sprayed aerially to control locust plagues. To evaluate fenitrothion exposure in birds attending locust outbreaks, we measured total plasma cholinesterase (ChE), butrylcholinesterase (BChE), and acetylcholinesterase (AChE) activities in four avian species captured pre- and postfenitrothion application and ChE reactivation in birds caught postspray only. Eleven of 21 plasma samples from four species had ChE activity below the diagnostic threshold (two standard deviations below the mean ChE activity of prespray samples). Granivorous zebra finches (Taeniopygia guttata) and insectivorous white-winged trillers (Lalage sueurii) had significantly lower mean plasma total ChE, BChE, and AChE activity postspray, while other insectivores, white-browed (Artamus superciliosus) and masked woodswallows (Artamus personatus), did not. Cholinesterase was reactivated in 19 of the 73 plasma samples and in one of three brain samples. We conclude that native bird species are exposed to fenitrothion during locust control operations. This exposure could have detrimental impacts, as both locust outbreaks and avian reproductive events are stimulated by heavy summer rainfall, leading to co-occurrence of locust control and avian breeding activities.

In classical eyeblink conditioning, non-specific emotional responses to the aversive shock unconditioned stimulus (US), which are presumed to coincide with the development of fear, occur early in conditioning and precede the emergence of eyeblink responses. This two-process learning model was examined by concurrently measuring fear and eyeblink conditioning in the freely moving rat. Freezing served as an index of fear in animals and was measured during the inter-trial intervals in the training context and during a tone conditioned stimulus (CS) presented in a novel context. Animals that received CS-US pairings exhibited elevated levels of fear to the context and CS early in training that decreased over sessions, while eyeblink conditioned responses (CRs) developed gradually during acquisition and decreased during extinction. Random CS-US presentations produced a similar pattern of fear responses to the context and CS as paired presentations despite low eyeblink CR percentages, indicating that fear responding was decreased independent of high levels of learned eyeblink responding. The results of paired training were consistent with two-process models of conditioning that postulate that early emotional responding facilitates subsequent motor learning, but measures from random control animals demonstrate that partial CS-US contingencies produce decrements in fear despite low levels of eyeblink CRs. These findings suggest a relationship between CS-US contingency and fear levels during eyeblink conditioning, and may serve to clarify further the role that fear conditioning plays in this simple paradigm.

Aim: To examine cardiovascular health benefits of foods containing a whole soybean extract., Methods: The study design was a randomized, placebo-controlled crossover trial of consuming soy-based milk and yoghurt (treatment) or equivalent dairy products (control) for 5 weeks each. Twenty-six mildly hypercholesterolaemic and/or hypertensive volunteers were recruited from the community as study volunteers, of which 23 completed. Main outcome measures included clinic and ambulatory blood pressure, arterial compliance, lipids, fatty acids and isoflavones in fasted blood and 24-hour urinary isoflavone excretion. Nutrient intakes were assessed initially and after each 5-week period. Multiple regression analyses were used to determine predictor variables in statistical models; order effects were tested by repeated measures ANOVA. Changes in Lp(a) were determined by Wilcoxon signed ranks tests; other differences between treatment and control were assessed by t tests., Results: Plasma and urinary isoflavones were markedly increased by whole soy supplementation but there were no overall differences in plasma lipids, blood pressure or arterial compliance between the soy and dairy diets. However, in 8 equol-positive subjects (equol detected in either plasma or urine), retrospective analysis revealed significant reductions in total cholesterol (8.5%), LDL cholesterol (10%), LDL:HDL ratio (13.5%), plasma triglycerides (21%) and lipoprotein(a) (11%) with the soy diet. These reductions were independent of changes in polyunsaturated fat and other macronutrient intakes., Conclusions: Regular consumption of whole soybean milk and yogurt products had no effect on plasma lipids, blood pressure or arterial compliance in at-risk subjects, despite substantially increasing isoflavone levels in blood and urine. Retrospective analysis suggests that improvement of plasma lipids may have been limited to equol-positive subjects., (Copyright 2004 S. Karger AG, Basel)

The breeding season is very brief for arctic-breeding passerines, and any interruptions of parental care by aggressive interactions over territory may reduce reproductive success. We tested both the "testosterone insensitivity" and "corticosterone insensitivity" hypotheses in the arctic-breeding Gambel's white-crowned sparrow, Zonotrichia leucophrys gambelii. Additionally, we tested whether simulated territorial intrusions (STIs), known to stimulate increases in luteinizing hormone (LH) and testosterone (T) in mid-latitude breeding Z. l. pugetensis, would also be effective in either the early or late phases of the brief breeding season of Z. l. gambelii. Plasma levels of T and LH were high early in the breeding season and declined as egg laying began. Exposure of free-living males to 10 min of STI significantly increased LH but not T secretion. Nonetheless, the pituitary-gonadal axis is sensitive as jugular injection of gonadotrophin-releasing hormone increased plasma T at 10 min relative to saline-challenged controls. T implants failed to increase territorial aggression following STI during incubation. These data are consistent with the T insensitivity hypothesis and contrast sharply with the response of the southerly breeding subspecies, Z. l. pugetensis, in which the territorial response to T administration is retained throughout its relatively long breeding season. However, corticosterone implants during the incubation period decreased territorial aggression during STI. This responsiveness to corticosterone is not consistent with the corticosterone insensitivity hypothesis of stress modulation. Z. l. gambelii retain sensitivity to corticosterone levels that may occur naturally in response to environmental perturbations resulting in suppression of territorial behavior., (Copyright 2002 Elsevier Science (USA))

We studied a population of rufous whistlers, Pachycephala rufiventris, throughout a single breeding season in central New South Wales, Australia. We evaluated the relation between plasma testosterone (T) and reproductive behaviors using both simulated territorial intrusions (STIs) and subcutaneous T implants. We compared circulating T values to aggression levels of males (using STI) during pair bond and territory establishment and again during incubation. Although plasma T levels were significantly lower in the latter period, male responsiveness to STI, in terms of proximity to decoy, call rate, and number of attacks on the decoy, was indistinguishable between the two breeding stages. T levels of males exposed to STI were not different from the levels of unexposed free-living males at the same breeding stage. The effect of exogenous T on parental behavior was examined by comparing duration of incubation bouts of males and their mates prior to and after T treatment. T males significantly reduced the amount of time they incubated following implantation, whereas Control males maintained their incubation effort. After cessation of breeding activities, T males displayed significantly higher call rates due to increased use of the primary intersexual advertisement call in this species. The reduction of incubation behavior following T implantation emphasises the functional significance of the rapid decline in T in free-living males during incubation. The results from both experiments suggest that intersexual advertisement, rather than territorial aggression, may be dependent on high T levels in this species., (Copyright 2001 Academic Press.)

We examined the effect of corticosterone on plasma levels of reproductive hormones (testosterone, dihydrotestosterone, and luteinizing hormone) and territorial defense behavior in male tree sparrows, Spizella arborea. Birds receiving Silastic implants filled with corticosterone (B) had significantly higher plasma levels of B than control birds, which received empty implants, and exhibited pectoral muscle wastage and a decrease in body mass. We evaluated the hormonal and agonistic responses of the two implanted groups of birds using a simulated territorial intrusion (STI) 2 to 4 days after they were implanted. Corticosterone-treated and control birds did not differ in their circulating levels of reproductive hormones or in their behavioral responses to STI (latency to respond to intrusion, number of songs, and closest approach to a decoy and tape recording). Unlike previous studies of north temperate passerines, high physiological levels of exogenous B had no effect either on circulating levels of reproductive hormones or on territorial behaviors associated with breeding. Nonetheless, untreated tree sparrows do mount a robust adrenocortical response, having a two- to fourfold increase in plasma B levels during a 1-h period of capture. Thus, adrenocortical responsiveness is maintained in these birds, but elevated levels of glucocorticoids do not suppress reproductive hormones or associated behaviors. We believe that this hormonal and behavioral refractoriness to glucocorticoids-or uncoupling of the stress response from the reproductive axis-may be advantageous for species having extreme temporal constraints on their breeding schedules., (Copyright 2000 Academic Press.)

We tested the effects of naturally relevant environmental temperatures on long day-induced reproductive development in male and female white-crowned sparrows, Zonotrichia leucophrys gambelii. Transfer from short days (8L 16D) to long days (20L 4D) resulted in rapid testicular development and partial ovarian development as has been reported many times previously. Exposure of experimental groups to low (5 degrees), moderate (20 degrees), and high (30 degrees) temperature during photostimulation had only subtle effects on plasma levels of follicle-stimulating hormone and luteinizing hormone over time and no effects on the size of testes, cloacal protuberance, ovaries, or brood patch at Day 30 of treatment. Long days resulted in the well known increase in body mass and fat score, indicative of preparations for migration. In females, treatment with low temperature resulted in a reduction in the premigratory increase in fat and body mass when transferred to long days. This was accompanied by an increase in plasma levels of corticosterone during the early stages of photostimulation at low temperature. Temperature regimes had no effects on fattening or body mass in males, despite an early increase in plasma corticosterone at low temperature. Circulating levels of thyroxine (T4) and triiodothyronine (T3) increased to varying degrees following photostimulation. Temperature treatment had no effect on plasma levels of thyroid hormones in males, but low temperature did inhibit thyroid hormone secretion (particularly T4) in females. Although reproductive development appears to be resistant to naturally relevant temperature extremes in both sexes, low environmental temperature impaired preparations for migration in females but not males. This effect may be mediated through glucocorticosteroids and not thyroid hormones. Reasons for the sexual dimorphism in this response are unknown, but may be related to sexual selection for males to arrive on the breeding grounds ahead of females regardless of local weather conditions.

The Lapland longspur, Calcarius lapponicus, times its breeding season so that chicks hatch coincident with the brief period of food abundance in the high arctic. This synchronization requires that all reproductive activities occur in over a much shorter period than at lower latitudes. Because of the known influence of stress hormones on delaying breeding in temperate-zone birds and the detrimental effects of such delays in the arctic, we expected the performance of the hypothalamic-pituitary-adrenal (HPA) axis of arctic-breeding birds to show less sensitivity to environmental stress than their mid-latitude counterparts. We found that adrenocortical responsiveness to the standardized stress of capture and handling, measured by taking five serial blood samples for corticosterone during the course of a 1-hr period, was similar to many temperate passerines and was also similar both between male and female longspurs and between the migratory and reproductive phases. However, the profile of plasma corticosterone during capture stress was significantly damped in longspurs sampled as they began their postnuptial molt. In addition, we had the opportunity to examine endocrine responses to a natural environmental stress in 1989 during a 3-day snowstorm which concealed available food resources. During this storm longspurs formed progressively larger flocks each day, with females abandoning incubation duties by the third day. Birds captured during the storm showed highly significant increases in both the rate of plasma corticosterone increase during capture and the peak postcapture level compared with birds sampled before the storm. This increased adrenal potential suggests increased activity of the HPA axis in response to severe conditions and is reminiscent of the response to fasting. Although the storm occurred during incubation, and reproductive hormone levels had begun to decline, we measured significant reductions in luteinizing hormone in both males and a subset of females captured during the storm.

We evaluated the adrenocortical response to acute stress in free-living Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii) using a standardized capture stress protocol in which five serial blood samples (70 microliters) were taken for measurement of plasma corticosterone (B) over the course of an hour of captivity (at 1, 5, 10, 30, and 60 min). In field-captured birds, male plasma B levels rose two to four times higher than those of females under capture stress during the breeding season, but were no different during winter (nonbreeding). We investigated the basis of this pattern by conducting dexamethasone (DEX) suppression tests on breeding and nonbreeding sparrows of both genders. This test involves pretreatment with subcutaneous DEX implants (a potent synthetic glucocorticoid) and challenge with intrajugular injections of either corticotropin (ACTH) or saline, followed by collection of a series of blood samples for evaluation of plasma B levels over a 2-hr period. ACTH injections in DEX-treated birds resulted in elevated B in both genders, with nonbreeding B profiles consistently lower than those of breeding birds. All DEX-treated, saline-injected birds, except breeding males, maintained low B levels for the entire 2-hr post-challenge period. This result indicates effective negative feedback by DEX on the hypothalamic-pituitary-adrenal axis, thus inhibiting endogenous B secretion. The apparent reduction in glucocorticoid feedback inhibition in breeding males may be related to an uncoupling of adrenal effects on reproductive behavior.

Resting metabolic rates of Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii) and pine siskins (Carduelis pinus) were evaluated at thermoneutral temperatures before and after administration of corticosterone (B) at physiological doses. There was no effect of B on basal metabolic rate of either species, but nocturnal metabolic rate varied significantly less over the 3-h period of measurement in B-treated sparrows and siskins than in control birds. These results, coupled with observations of caged birds, suggest that corticosterone has no direct effect on avian resting metabolism but does reduce the responsiveness of birds to external stimuli and thus promotes nocturnal restfulness.

Acetylcholinesterase (AChE) distribution in the dorsal lateral geniculate nucleus (LGd) of 3 polyprotodont and 3 diprotodont marsupials has been compared with the cytoarchitecture and, as appropriate, with retinal terminal bands (RTBs) as demonstrated by tracers injected into the vitreous body. In this series those polyprotodont marsupials showing only partial segregation of retinal input (Virginia opossum and Tasmanian devil), display the least cell laminar differentiation. In them AChE staining is mainly diffuse but stronger in areas of greatest retinal terminal overlap. Segregation of visual input increases progressively in the remaining polyprotodont (eastern quoll) and in the diprotodonts (Tasmanian bettong, Tasmanian potoroo and brush-tailed possum), culminating in the last-named, in which segregation is most complete. Related to this development varying numbers of cell laminae/sublaminae appear and retinal terminal laminae/sublaminae (bands) are revealed. AChE activity can be correlated with both specific cell laminae/sublaminae and retinal terminal laminae/sublaminae in these complex LGds. Greatest AChE staining in every case is related to laminae/RTBs located in the medial part of the lateral (alpha) segment of LGd. Cytoarchitecturally, the ventral lateral geniculate nucleus (LGv), unlike the heterogeneous LGd, is remarkably homogeneous in the series of animals studied and shows well-stained AChE patches relating to areas receiving significant retinal input.