Digit ratios (2D:4D), secondary sexual characters and cell-mediated immunity in house sparrows <Emphasis Type="Italic">Passer domesticus</Emphasis>

Homeobox genes regulate development of digits, and it has been suggested that the ratio of length of second to length of fourth digit reflects such genetic effects in a sex-specific manner. We show that digit ratios in the sexually dichromatic house sparrow Passer domesticus differ between sexes, with males having higher ratios than females, and that individuals produce consistent ratios on the two feet. If Homeobox or other genes had pleiotropic effects on development of digits, behavior, and physiology of males and females, we would expect secondary sexual characters and immunity to be related to digit ratio in a sex-specific manner. The size of the visible part of the black badge in February (a secondary sexual character), but not total badge size, was positively correlated with digit ratios, suggesting that males with more male-like digit ratios had larger visible badges. Because of sex-specific effects of development on secondary sexual characters and immunity, we predicted sex-specific differences in immune response to be related to digit ratio. House sparrows with large digit ratios had weaker T cell-mediated immune response than individuals with small digit ratios, particularly in females, implying that females with more male-like digit ratios had weak immune responses. These findings are consistent with the hypothesis that early development, as reflected by digit ratios, and genetics affect the expression of adult characters that are supposedly strongly contributing to fitness.     

Fitness costs of an immune response in the house martin (<Emphasis Type="Italic">Delichon urbica</Emphasis>)

Immune responses constitute a major way for hosts to defend themselves against parasites. Because hosts do not habitually produce strong responses all the time, immune responses might be costly to produce or maintain. We tested experimentally if the production of a response to a challenge with a novel antigen resulted in a cost in terms of fitness using the highly colonial house martin Delichon urbica as a model system. We injected adult breeding birds during laying of the first clutch with either Newcastle disease virus (NDV) or a control injection, and the clutch was subsequently removed to induce relaying. NDV stimulates the non-specific immune system, causing production of antibodies during a period of more than 2 weeks. Accordingly, we found an increase in leukocyte counts in experimental birds compared to controls. Experimental treatment reduced the frequency of re-laying, caused a delay in timing of relaying and a reduction in brood size. Quality of nestlings in terms of body size, body mass and T-cell-mediated immune response did not differ significantly between treatments. Overall, seasonal reproductive success differed significantly between treatments, showing that the production of an immune response by adult birds is costly in terms of future fecundity.     

Studies on the adsorption and kinetics of photodegradation of a model compound for heterogeneous photocatalysis onto TiO(2)

An investigation was made on the adsorption and kinetics of photodegradation of potassium hydrogenphthalate in an aqueous suspension of TiO(2). Two models, Langmuir and Freundlich, were used to describe the adsorption process and the model proposed by Langmuir-Hinshelwood (L-H) was employed to describe the kinetics of the photodecomposition reactions of hydrogenphthalate. The results of the adsorptions were fitted to the models proposed by Langmuir and Freundlich. Adsorption was found to be a function of the temperature, with adsorption capacity increasing from 2.4 to 4.5 mg/g when the temperature rose from 20 to 30 degrees C. The kinetic model indicates that the rate constant, k, of the first order reaction, is high in the 10.0 to 100 mg/l interval, which is coherent with the low value of the adsorption constant, K. The results fitted to the L-H model led to an equation that, within the range of concentrations studied here, theoretically allows one to evaluate the photodegradation rate.     

Measurement of carbon storage in landfills from the biogenic carbon content of excavated waste samples

Landfills are an anaerobic ecosystem and represent the major disposal alternative for municipal solid waste (MSW) in the U.S. While some fraction of the biogenic carbon, primarily cellulose (Cel) and hemicellulose (H), is converted to carbon dioxide and methane, lignin (L) is essentially recalcitrant. The biogenic carbon that is not mineralized is stored within the landfill. This carbon storage represents a significant component of a landfill carbon balance. The fraction of biogenic carbon that is not reactive in the landfill environment and therefore stored was derived for samples of excavated waste by measurement of the total organic carbon, its biogenic fraction, and the remaining methane potential. The average biogenic carbon content of the excavated samples was 64.6 ± 18.0% (average ± standard deviation), while the average carbon storage factor was 0.09 ± 0.06 g biogenic-C stored per g dry sample or 0.66 ± 0.16 g biogenic-C stored per g biogenic C_.     

Variation in sperm morphometry and sperm competition among barn swallow (Hirundo rustica) populations

Spermatozoa vary greatly in size and shape among species across the animal kingdom. Postcopulatory sexual selection is thought to be the major evolutionary force driving this diversity. In contrast, less is known about how sperm size varies among populations of the same species. Here, we investigate geographic variation in sperm size in barn swallows Hirundo rustica, a socially monogamous passerine with a wide Holarctic breeding distribution. We included samples from seven populations and three subspecies: five populations of ssp. rustica in Europe (Czech, Italy, Norway, Spain, and Ukraine), one population of ssp. transitiva in Israel, and one population of ssp. erythrogaster in Canada. All sperm traits (head length, midpiece length, tail length, and total length) varied significantly among populations. The variation among the European rustica populations was much lower than the differences among subspecies, indicating that sperm traits reflect phylogenetic distance. We also performed a test of the relationship between the coefficient of between-male variation in total sperm length and extrapair paternity levels across different populations within a species. Recent studies have found a strong negative relationship between sperm size variation and extrapair paternity among species. Here, we show a similar negative relationship among six barn swallow populations, which suggests that the variance in male sperm length in a population is shaped by the strength of stabilizing postcopulatory sexual selection.     

Geographic patterns of natal dispersal in barn swallows <Emphasis Type="Italic">Hirundo rustica</Emphasis> from Denmark and Spain

Dispersal is an important factor that determines the degree of gene flow and, hence, the degree of differentiation among populations. Using two long-term datasets on natal philopatry and short-distance dispersal in barn swallows Hirundo rustica from Denmark and Spain, we evaluated the fitness costs and benefits and test a number of predictions about the functional significance of dispersal. The proportion of philopatric individuals was more than six times larger in Spain than in Denmark, with a higher rate of philopatry in males than in females. Dispersal propensity decreased in both populations during the course of the study. Males from the more philopatric Spanish population lived longer when philopatric rather than dispersing while that was not the case for either sex of the less philopatric Danish population. There were large differences in dispersal propensity among cohorts and breeding sites, suggesting that sites differed in their suitability as sites for immigrants. We found no evidence consistent with the mate competition hypothesis suggesting that males in better condition or with larger condition-dependent secondary sexual characters were more likely to be philopatric. These findings suggest that there is a high degree of intraspecific variation in dispersal propensity between populations, probably relating to local differences in costs and benefits of philopatry and dispersal.     

Female house martins (Delichon urbica) reduce egg androgen deposition in response to a challenge of their immune system

Female birds deposit in the yolks of eggs substantial amounts of androgens, such as testosterone and androstenedione. These androgens have been shown to speed up nestling development, induce a fast development of ornaments and increase dominance in adults. Experiments in several species have reported that females invest greater amounts of androgens in the eggs fathered by attractive males, suggesting that yolk androgen is a costly investment for either the offspring or the mother. There is some evidence that nestling immunocompetence may be partially suppressed by high levels of yolk androgens, but it is not known whether this is also the case for females. We tested this hypothesis in the house martin by inducing an immune challenge through an injection of sheep red blood cells, a standard challenge of the humoral immune system. Experimental birds laid eggs with lower amounts of yolk androstenedione than controls, and there was a similar non-significant trend for testosterone. Furthermore, the probability of laying a replacement clutch was higher for birds that had laid a first clutch with relatively high levels of yolk testosterone. These results suggest that yolk androgen deposition is limited by immune costs in the female, and that only females in good condition may afford to invest high levels of androgen in eggs in this species.     

Biodegradable Polyesters and Polyamides From Difunctionalized Lauric and Coconut Fatty Acids

In this work, a major fatty acid from coconut oil was used as starting material in preparing biodegradable polymers. Thus, polyesters and polyamides from varying proportions of monomers, hydroxy- and amino- derivatives of lauric acid were synthesized. Initially, the derivatives were prepared by regioselective chlorination of lauric acid, in the presence of ferrous ions in strong acid medium. Subsequent hydroxylation and amination procedures yielded the hydroxy- and amino- derivatives of lauric acid. These monomers were polymerized in a reaction tube by simple polycondensation method at 220–230 °C for 6–8 h without catalyst. Molecular weight determination using –COOH by end group titration and gel permeation chromatography (GPC) gave an average molar mass of 3,000–5,000 g mol⁻¹ with n = 15–25 monomer units. Thermal properties such as glass transition (T_g) and decomposition (T_d) temperatures were obtained using differential scanning calorimetry (DSC). The same processes of synthesis and determinations above were applied to coconut fatty acids, derived from saponification of coconut oil, and resulted to very similar conclusions. A quick biodegradation assay against fungus Aspergillus niger UPCC 4219 showed that the polymers prepared are more biodegradable than conventional plastics such as polypropylene, poly(ethyleneterepthalate) and poly(tetrafluoroethylene) but not as biodegradable as cellulosic (newsprint) paper.     

Seasonal variation in the relationship between cellular immune response and badge size in male house sparrows (Passer domesticus)

The immunocompetence handicap hypothesis postulates that secondary sexual traits are honest signals of male quality because steroid hormones (such as corticosteroids and sex steroids), which are supposed to favor the development of secondary sexual traits, may also have immunosuppressive effects. Certain secondary sexual traits are not only used as mate choice signals but also play a role as badges of status. In the house sparrow (Passer domesticus), males have a bib of black feathers which is used both as a signal of social status in male-male interactions and by females when choosing a mate. We investigated the relationships between bib size and cellular immune response in male house sparrows during and outside the reproductive season. Males with large badges were found to have lower levels of immunocompetence, as assessed using a T-cell-mediated immunity assay, during the reproductive season, as predicted by the immunocompetence handicap hypothesis. Conversely, in November, the correlation between badge size and cellular immune response was positive, possibly reflecting the better access to trophic resources of large-badged dominant males in winter flocks. Received: 24 September 1998 / Received in revised form: 2 February 1999 / Accepted: 14 February 1999