Body condition and feather molt of a migratory shorebird during the non‐breeding season

Migratory shorebirds have some of the highest fat loads among birds, especially species which migrate long distances. The upland sandpiper Bartramia longicauda makes long‐distance migrations twice a year, but variation in body condition or timing of feather molt during the non‐breeding season has not been studied. Molt is an important part of the annual cycle of migratory birds because feather condition determines flight performance during migration, and long‐distance movements are energetically costly. However, variation in body condition during molt has been poorly studied. The objective of our field study was to examine the timing and patterns of feather molt of a long distance migratory shorebird during the non‐breeding season and test for relationships with body size, fat depots, mass, and sex. Field work was conducted at four ranches in the Northern Campos of Uruguay (Paysandú and Salto Departments). We captured and marked 62 sandpipers in a 2‐month period (Nov–Jan) during four non‐breeding seasons (2008–2012). Sex was determined by genetic analyses of blood samples taken at capture. Molt was measured in captured birds using rank scores based on published standards. Body mass and tarsus length measurements showed female‐biased sexual size dimorphism with males smaller than females. Size‐corrected body mass (body condition) showed a U‐shaped relationship with the day of the season, indicating that birds arrived at non‐breeding grounds in relatively good condition. Arriving in good body condition at non‐breeding grounds is probably important because of the energetic demands due to physiological adjustments after migration and the costs of feather molt.     

Fracture Faces in the Cell Envelope of Escherichia coli

Freeze-fracturing of Escherichia coli cells in the presence of 30% (v/v) glycerol resulted in a double cleavage of the cell envelope exposing two convex and two concave fracture faces ([Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text]) with characteristic patterns. Complementary replicas revealed the relationship of the fracture faces to their corresponding fracture planes. The inner fracture plane splits the plasma membrane at one particular level. Apparently the outer fracture plane was located in the outer part of the wall, as it was separated by a layer ([Formula: see text]) from the fractured profile (CW1) presumably corresponding to the murein layer. The outer fracture plane did alternate toward the cell periphery, exposing complementary smooth areas ([Formula: see text] and [Formula: see text]). When cells were freeze-fractured in the absence of glycerol, the outer cell surface appeared as an etching face rather than a fracture face. A schematic representation of the relative location of the different fracture faces in the E. coli cell envelope is given.     

Moulting fast and time constraint for reproduction in the king penguin

King penguins (Aptenodytes patagonicus) replace their complete plumage during a 3- to 4-week moulting fast on shore. After moulting, birds forage at sea for 2-3 weeks to store energy reserves for reproduction. Using an automatic identification and weighing system coupled with visual observations, we investigated the trade-off between the moulting fast and the following breeding attempt, in terms of body condition and in relation to time constraints, in free-living king penguins. King penguins reached their lowest body mass of the yearly cycle at the end of the moulting fast; this was lower than that at the end of the incubation fasts and not different from the body mass at egg desertion. Later in the season, the duration of the moulting fast became shorter and old feather loss occurred earlier after arrival ashore. Postmoulting foraging trips were shorter, but at the expense of body condition at the beginning of courtship. These results are discussed in relation to the synchronisation of the breeding cycle with food availability and mate choice.     

Suicide inactivation of tyrosinase in its action on tetrahydropterines

Tetrahydrobiopterin (BH(4)), methyl-tetrahydropterin (MBH(4)) and dimethyl-tetrahydropterin (DMBH(4)) are oxidized by tyrosinase in a process during which the suicide inactivation of tyrosinase may occur. From the kinetic study of this process, [Formula: see text] (apparent maximum constant for the suicide inactivation), [Formula: see text] (Michaelis constant for the substrate) and r (number of turnovers that the enzyme makes before the inactivation) can be obtained. From the results obtained, it can be deduced that the velocity of the inactivation governed by ([Formula: see text]) and the potency of the same ([Formula: see text]) follow the order: BH(4) > MBH(4) > DMBH(4).     

Fat King Penguins Are Less Steady on Their Feet

Returning to the shore after a feeding sojourn at sea, king penguins often undertake a relatively long terrestrial journey to the breeding colony carrying a heavy, mostly frontal, accumulation of fat along with food in the stomach for chick-provisioning. There they must survive a fasting period of up to a month in duration, during which their complete reliance on endogenous energy stores results in a dramatic loss in body mass. Our aim was to determine if the king penguin’s walking gait changes with variations in body mass. We investigated this by walking king penguins on a treadmill while instrumented with an acceleration data logger. The stride frequency, dynamic body acceleration (DBA) and posture of fat (pre-fasting; 13.2 kg) and slim (post fasting; 11 kg) king penguins were assessed while they walked at the same speed (1.4km/h) on a treadmill. Paired statistical tests indicated no evidence for a difference in dynamic body acceleration or stride frequency between the two body masses however there was substantially less variability in both leaning angle and the leaning amplitude of the body when the birds were slimmer. Furthermore, there was some evidence that the slimmer birds exhibited a decrease in waddling amplitude. We suggest the increase in variability of both leaning angle and amplitude, as well as a possibly greater variability in the waddling amplitude, is likely to result from the frontal fat accumulation when the birds are heavier, which may move the centre of mass anteriorly, resulting in a less stable upright posture. This study is the first to use accelerometry to better understand the gait of a species within a specific ecological context: the considerable body mass change exhibited by king penguins.     

Individual Consistency and Phenotypic Plasticity in Rockhopper Penguins: Female but Not Male Body Mass Links Environmental Conditions to Reproductive Investment

In marine habitats, increasing ocean temperatures due to global climate change may distinctly reduce nutrient and consequently food availability for seabirds. Food availability is a known driver of body mass and reproductive investment in birds, but these traits may also depend on individual effects. Penguins show extreme intra-annual body mass variation and rely on accumulated body reserves for successful breeding. However, no study so far has tested individual consistency and phenotypic responses in body mass and reproductive investment in this taxon. Using a unique dataset on individually marked female and male southern rockhopper penguins (Eudyptes chrysocome chrysocome) across six years, we investigated 1) the individual consistency in body mass (measured at egg laying), body condition and reproductive investment across years, subsequently 2) identified the best-explanatory temperature-related environmental variables for female and male body mass, and 3) tested the effect of female and male body mass on reproductive investment. Body mass, body condition and reproductive investment were all highly repeatable. As body condition should control for the structural size of the birds, the similarly high repeatability estimates for body mass and body condition suggested that the consistent between-individual body mass differences were independent of structural size. This supported the use of body mass for the subsequent analyses. Body mass was higher under colder environmental conditions (positive Southern Annular Mode), but the overall phenotypic response appeared limited. Reproductive investment increased with female but not male body mass. While environmental effects on body mass in our study period were rather small, one can expect that ongoing global climate change will lead to a deterioration of food availability and we might therefore in the long-term expect a phenotypical decline in body mass and reproductive investment.     

Comparison of behaviour,body mass,haematocrit level,site fidelity and survival between infested and non-infested king penguin<Emphasis Type="Italic"> Aptenodytes patagonicus</Emphasis> by ticks<Emphasis Type="Italic"> Ixodes uriae</Emphasis>

The tick Ixodes uriae is widespread in subantarctic areas. This tick species parasitises a large number of seabird species and may affect their population dynamics. Adult king penguins are significant hosts for I. uriae in Crozet Archipelago. We compared the body mass, haematocrit level and behaviour during incubation according to tick infestation. Tick infestation had no effect on the body mass, haematocrit or behaviour of incubating penguins. Contrary to what might have been expected, birds breeding in the infested area did not show a lower fidelity to that area the next breeding season in comparison to birds breeding in the non-infested area. Survival was not different between the two groups over the following 32 months.     

Estimating the critical body mass of king penguins

King penguins (Aptenodytes patagonicus) can fast for over a month. However, they return to sea to forage before their body mass reaches a critical value (cMb), beyond which there is an increase in rate of mass loss and in protein catabolism, termed phase III of fasting. Thus when studying king penguins onshore, accurate estimation of their cMb and, in turn, the date at which that body mass would be reached, will be informative to behavioural and physiological data being collected. For penguins being studied during fasts in captivity, knowing cMb is particularly important because of the need to release the birds back into their colony while they are still in good nutritional condition. The present study investigates the validity of using measures of beak, flipper and foot length together to estimate cMb in king penguins and provides a simple and effective prediction equation for researchers. The three morphometric measurements, along with body mass just prior to going to sea after the moult fast (taken to represent cMb), were obtained for nine king penguins in a colony at the Crozet Archipelago. A multiple linear regression of the three morphometric measurements against cMb provided an R ² of 71.2%. Mean absolute percentage error of the estimate of cMb over the nine birds was 8.82 ± 1.20%. The described technique could probably be employed for estimating cMb in other long-fasting seabirds.     

Gene or environment? Species-specific control of stomatal density and length

Stomatal characteristics are used as proxies of paleo-environment. Only a few model species have been used to study the mechanisms of genetic and environmental effects on stomatal initiation. Variation among species has not been quantified. In this paper, results from an in situ reciprocal transplant experiment along an elevation gradient in the northeast Tibetan Plateau are reported, in which the relative effects of genetics (original altitude) and environment (transplant altitude) on stomatal density (SD) and length (SL) were quantified. In Thalictrum alpinum, only the environment significantly influenced SD, with the variance component ([Formula: see text]) of the environment found to be much greater than that of genetics ([Formula: see text]) ([Formula: see text]). In Kobresia humillis, only genetics significantly influenced SD and SL, with the genetics variance component found to be greater than that of the environment ([Formula: see text], for SD). These results suggest that the extent to which genetics and the environment determine stomatal initiation and development is species-specific. This needs to be considered when studying genetic or environmental controls of stomatal initiation, as well as when SD and SL are used as proxies for ancient climate factors (e.g., CO(2) concentration).     

Condition dependence of a multicomponent sexual display trait in Drosophila serrata

Theory predicts that costly sexual displays should evolve condition dependence if the marginal fitness gain from trait exaggeration is greater for high- than for low-condition individuals and that the strength of condition dependence should increase with the strength of directional selection. While there is substantial support for the first prediction, evidence for the latter is much weaker. We undertook a quantitative test of this prediction for a multivariate sexual display consisting of a suite of contact pheromones termed "cuticular hydrocarbons" (CHCs) in Drosophila serrata. We performed a dietary manipulation of condition (i.e., the pool of metabolic resources available for allocation to fitness-enhancing traits) within a half-sibling breeding design, thereby also providing insight into the genetic basis of condition dependence. As predicted, the linear combination of CHCs under the strongest sexual selection from female mate preferences was unusually condition dependent relative to other CHC combinations within the population ([Formula: see text]). A significant positive correlation also existed between the strengths of condition dependence and sexual selection among different CHC blends ([Formula: see text], [Formula: see text]). Finally, sires varied in their response to the dietary manipulation, demonstrating significant genetic variance in condition dependence. Our results are consistent with the evolution of heightened condition dependence of sexual displays in response to persistent sexual selection.     

Sex-specific genetic variances in life-history and morphological traits of the seed beetle Callosobruchus maculatus

Knowledge of heritability and genetic correlations are of central importance in the study of adaptive trait evolution and genetic constraints. We use a paternal half-sib-full-sib breeding design to investigate the genetic architecture of three life-history and morphological traits in the seed beetle, Callosobruchus maculatus. Heritability was significant for all traits under observation and genetic correlations between traits (r(A)) were low. Interestingly, we found substantial sex-specific genetic effects and low genetic correlations between sexes (r(MF)) in traits that are only moderately (weight at emergence) to slightly (longevity) sexually dimorphic. Furthermore, we found an increased sire ([Formula: see text]) compared to dam ([Formula: see text]) variance component within trait and sex. Our results highlight that the genetic architecture even of the same trait should not be assumed to be the same for males and females. Furthermore, it raises the issue of the presence of unnoticed environmental effects that may inflate estimates of heritability. Overall, our study stresses the fact that estimates of quantitative genetic parameters are not only population, time, environment, but also sex specific. Thus, extrapolation between sexes and studies should be treated with caution.     

Comparison of Color and Body Condition Between Early and Late Breeding King Penguins

Early breeding is associated with greater reproductive success in many species. In king penguins, Aptenodytes patagonicus , laying extends for 6 mo. Early breeders may fledge a single chick at best, but late breeders virtually never fledge a chick. For early and late breeders, we compared colored ornaments known to be important in mate choice: yellow–orange feathers of the breast and auricular areas, and an ultraviolet and yellow–orange beak spot. Our purpose was to discern differences between males and females in this highly sexually monomorphic species, as well as to discern whether colored ornaments are more important for the more successful early breeders (aspects of color were hue, chroma, and brightness). For this, we weighed and measured 130 penguins. Early males had greater reflectance of ultraviolet color from the beak spot than did early females and late breeders of both sexes, and the early males were heavier and in better condition than late breeding males or females. Late breeding females were the yellowest in breast hue, a trait that has been linked to immunocompetence. Within pairs, males and females were significantly correlated in body mass, but only early in the breeding season. We concluded that early in the breeding season when reproductive success was greatest, potential mates were not only more similar in body mass, but also that females may have chosen males that had brighter beak spots and were in better body condition.     

Association of peak aerobic power with capillary density but not oxidative potential in human vastus lateralis muscle

In this study, we have postulated that in healthy males, peak aerobic power ([Formula: see text]) would associate with muscle capillary density rather than oxidative potential, regardless of fibre type or subtype. To test this, active but untrained volunteers (n = 11) were separated into high (HI) and low (LO) groups based on [Formula: see text] obtained during a progressive cycle task to fatigue. The 26% higher (P?< 0.05) [Formula: see text] observed in HI (40.8?± 1.5?mL·kg(-1)·min(-1), mean?± SE) compared with LO ( 51.4?± 0.90?mL·kg(-1)·min(-1), mean?± SE) was not accompanied by differences in age (21.3?± 1.2 compared with 21.1?± 0.63?years, respectively) or body mass (72.4?± 4.6 compared with 71.6?± 1.9?kg, respectively). Tissue samples obtained from the vastus lateralis indicated greater (P?< 0.05) capillary counts per fibre (CC;?+24%) in HI compared with LO, regardless of fibre type (I, IIA, IIX, IIAX). Capillary density (CD) as measured in a field of defined area was also elevated (+22%; P?< 0.05), as was the number of capillaries per fibre (+22%; P?< 0.05). No differences were observed between the 2 groups in the distribution, area, and the CC/fibre area ratio in the different fibre types and subtypes. Similarly, there was no difference between the HI and LO groups in oxidative potential, as measured by succinic dehydrogenase activity in the different fibre types. It is concluded that the higher capillary density may contribute to improved vascular conductance and the elevated [Formula: see text] observed in the untrained participants.     

Body condition effects in American kestrels fed selenomethionine

Body composition was measured in male American kestrels (Falco sparverius) beginning after a 77-day exposure to 0, 6, or 12 ppm (dry wt.) selenium as seleno-L-methionine in their diet. Total body mass, lean body mass, and body fat were compared among groups to identify potential wasting effects of selenium, as had been reported for wild waterfowl from a selenium-contaminated site. On the last day of selenium treatment, selenium concentrations in the blood of kestrels was significantly negatively correlated with lean mass. Kestrels that had been exposed to 12 ppm selenium in the diet exhibited relatively higher lean mass (relative to total body mass) and lower normalized body fat than kestrels fed 0 or 6 ppm dietary selenium. These differences persisted throughout the 6 mo study period. The effect observed on body condition of kestrels at environmentally relevant exposure levels has implications for wild birds with respect to both overwinter survival and reproductive success.     

Is Penguin banding harmless?

Thousands of penguins are banded annually world-wide, even though little is known about the potential impact of these flipper bands. In this paper, the possible effect of banding on the survivorship, breeding frequency and other ecological factors on king penguins was investigated. The extended laying period (3–4 months) of the king penguin allows the observation of non-lethal effects that could influence the time of laying and thus the reproductive success. Three hundred and eighty-three breeding king penguins on the colony of “la Baie du Marin” on Possession Island, Crozet Archipelago were either single- or double-flipper banded. The results show that the returning birds were laying late the following breeding season, and that double-banded birds lay significantly later than single-banded birds. Furthermore, our data suggest a lower return rate for double-banded birds than for single-banded birds (45% as opposed to 76%). The low return rate of single-banded birds, when compared to an interannual survivorship estimated to be 96.5%, also raises questions concerning the potential impact of single banding. Received: 2 January 1998 / Accepted: 23 May 1998     

Exploiting magnetic resonance angiography imaging improves model estimation of BOLD signal

The change of BOLD signal relies heavily upon the resting blood volume fraction ([Formula: see text]) associated with regional vasculature. However, existing hemodynamic data assimilation studies pretermit such concern. They simply assign the value in a physiologically plausible range to get over ill-conditioning of the assimilation problem and fail to explore actual [Formula: see text]. Such performance might lead to unreliable model estimation. In this work, we present the first exploration of the influence of [Formula: see text] on fMRI data assimilation, where actual [Formula: see text] within a given cortical area was calibrated by an MR angiography experiment and then was augmented into the assimilation scheme. We have investigated the impact of [Formula: see text] on single-region data assimilation and multi-region data assimilation (dynamic cause modeling, DCM) in a classical flashing checkerboard experiment. Results show that the employment of an assumed [Formula: see text] in fMRI data assimilation is only suitable for fMRI signal reconstruction and activation detection grounded on this signal, and not suitable for estimation of unobserved states and effective connectivity study. We thereby argue that introducing physically realistic [Formula: see text] in the assimilation process may provide more reliable estimation of physiological information, which contributes to a better understanding of the underlying hemodynamic processes. Such an effort is valuable and should be well appreciated.     

Robustness and information propagation in attractors of random boolean networks

Attractors represent the long-term behaviors of Random Boolean Networks. We study how the amount of information propagated between the nodes when on an attractor, as quantified by the average pairwise mutual information ([Formula: see text]), relates to the robustness of the attractor to perturbations ([Formula: see text]). We find that the dynamical regime of the network affects the relationship between [Formula: see text] and [Formula: see text]. In the ordered and chaotic regimes, [Formula: see text] is anti-correlated with [Formula: see text], implying that attractors that are highly robust to perturbations have necessarily limited information propagation. Between order and chaos (for so-called "critical" networks) these quantities are uncorrelated. Finite size effects cause this behavior to be visible for a range of networks, from having a sensitivity of 1 to the point where [Formula: see text] is maximized. In this region, the two quantities are weakly correlated and attractors can be almost arbitrarily robust to perturbations without restricting the propagation of information in the network.     

Body condition changes of sand martins (Riparia riparia) during breeding, and a comparison with fledgling condition

The body condition of adult sand martins during the breeding season and a sample of fledglings was investigated by carcass analysis and by examination of live birds in the field. Fat scoring of live individuals was a reliable predictor of an individual's lipid content in most instances. Body mass changes during breeding were related to changes in the size of birds' lipid reserves, pectoral muscle mass, body water, and to development of the reproductive system. In both males and females, reserve lipid declined between the onset of breeding and nestling rearing. Pre-breeding males had significantly greater pectoral muscle masses than did nestling rearing females. The potential significance of protein in pectoral muscles as an energy reserve during breeding was small compared with lipid reserves. By comparing potential energy reserves in body lipid and protein with daily energy expenditure, it was calculated that neither incubating nor nestling rearing adults could survive a day of normal activity without feeding. The selective premium on adults optimizing their use of time and energy for self-maintenance behaviour during breeding is therefore likely to be great.     

Shear conditions in clavulanic acid production by Streptomyces clavuligerus in stirred tank and airlift bioreactors

In biochemical processes involving filamentous microorganisms, the high shear rate may damage suspended cells leading to viability loss and cell disruption. In this work, the influence of the shear conditions in clavulanic acid (CA) production by Streptomyces clavuligerus was evaluated in a 4-dm(3) conventional stirred tank (STB) and in 6-dm(3) concentric-tube airlift (ALB) bioreactors. Batch cultivations were performed in a STB at 600 and 800 rpm and 0.5 vvm (cultivations B1 and B2) and in ALB at 3.0 and 4.1 vvm (cultivations A1 and A2) to define two initial oxygen transfer conditions in both bioreactors. The average shear rate ([Formula: see text]) of the cultivations was estimated using correlations of recent literature based on experimental data of rheological properties of the broth (consistency index, K, and flow index, n) and operating conditions, impeller speed (N) for STB and superficial gas velocity in the riser (UGR) for ALB. In the same oxygen transfer condition, the [Formula: see text] values for ALB were higher than those obtained in STB. The maximum [Formula: see text] presented a strong correlation with a maximum consistency index (K (max)) of the broth. Close values of maximum CA production were obtained in cultivations A1 and A2 (454 and 442 mg L(-1)) with similar maximum [Formula: see text] values of 4,247 and 4,225 s(-1). In cultivations B1 and B2, the maximum CA production of 269 and 402 mg L(-1) were reached with a maximum [Formula: see text] of 904 and 1,786 s(-1). The results show that high values of average shear rate increase the CA production regardless of the oxygen transfer condition and bioreactor model.     

Spontaneous egg or chick abandonment in energy-depleted king penguins: a role for corticosterone and prolactin?

Various exogenous or endogenous factors may induce an emergency response in birds, redirecting current activity towards survival. In fasting, breeding penguins, the achievement of a critical energy depletion was suggested to induce egg abandonment and departure to sea for re-feeding. How such a behavioral shift is hormonally controlled remains unknown. The possible involvement of corticosterone and prolactin was examined by characterizing the nutritional and hormonal states of king penguins at egg abandonment. Further, we tested if these states differ according to whether an egg or a chick is abandoned, and according to the timing of breeding. In every case of abandonment, birds were in phase III fasting characterized by accelerated protein catabolism. However, body condition at egg abandonment was lower in early than in late breeders, suggesting that king penguins are willing to tolerate a larger energy depletion when their potential breeding success is high. At egg and chick abandonment, plasma corticosterone levels were, respectively, increased by 2- and 4-fold, whereas plasma prolactin levels were, respectively, depressed by 3- and 1.4-fold. The increase in plasma corticosterone and the decrease in plasma prolactin could be involved in the control of abandonment by, respectively, stimulating the drive to re-feed and diminishing the drive to incubate or brood. The smaller decrease in prolactin levels and the greater increase in corticosterone levels observed at chick vs egg abandonment suggest that, in addition to nutritionally-related stimuli, tactile or audible stimuli from the egg or chick could intervene in the endocrine control of abandonment.