Hormonal correlates of breeding behavior and pouch color in the Magnificent Frigatebird, Fregata magnificens.

It is well known that testosterone (T) influences the expression of the behavior and many sexual traits during reproduction in vertebrates. However, patterns of circulating concentrations of T vary tremendously across free-living populations. Here the profiles of plasma T levels in the Magnificent Frigatebird, Fregata magnificens, are presented during the courtship, incubation and chick rearing stages of breeding. In addition, the predicted interrelationship of T and the expression of a sexually selected trait, the red gular pouch of males is investigated. Plasma levels of corticosterone (Cort) are reported in relation to the demands of breeding conditions in colonies. Blood samples were obtained from 26 males and 32 females in the 1993-1994 breeding season and 41 courting males in 1997. Pouch color and size were also estimated in these males. As expected, T levels changed across the breeding stages: birds showed high levels of T during courtship and much lower circulating levels during incubation and chick rearing. Consistent with the expected effect of T, individual pouch color and size correlated with circulating levels of this hormone. In this highly dimorphic species no correlation was found between T and body condition or tail asymmetry. Cort, in contrast, did not change across the three reproductive stages.

Comparative study of different cocoa (Theobroma cacao L.) clones in terms of their phytoprostanes and phytofurans contents.

Cocoa has been widely discussed as a bioactive food rich in sensory stimulation and health benefits. However, no information has been provided concerning phytoprostanes (PhytoPs) and phytofurans (PhytoFs) in cocoa. These compounds are of interest because they play a role in the regulation of immune function. The present study included 31 cocoa clones. The PhytoPs and PhytoFs were quantified by UHPLC-QqQ-MS/MS. The total PhytoPs and PhytoFs contents ranged from 221.46 to 1589.83 ng g-1 and from 1.18 to 13.13 ng g-1, respectively. The profiles of the PhytoPs and PhytoFs identified in the cocoa beans showed significant differences among the clones analysed. The results indicate that dry fermented cocoa beans are rich in PhytoPs and PhytoFs, which may represent an additional benefit of the consumption of foods derived from cocoa.

Morphology and ornamentation in male magnificent frigatebirds: variation with age class and mating status.

Male magnificent frigatebird (Fregata magnificens) ornamentation includes bright iridescent plumage and a red inflatable gular pouch. These signals are displayed during courtship, along with a drumming sound produced through specialized beak clackings resonating in the gular pouch. The extent of white in the plumage identifies three age classes of nonjuvenile male. Here we investigate how morphological and secondary sexual traits correlate with age class and mating status. Even though several age class-related differences in morphology and visual appearance can be identified, the only features that significantly predict mating success are acoustic components of courtship display. Specifically, males that mate drum at lower fundamental frequencies--that is, they have larger gular pouches--and have a quicker and more constant drumming cadence than unsuccessful males. The fundamental frequency decreases with age class, reflecting an increase in gular pouch size. This implies that females prefer older or possibly more experienced or viable males. Drumming cadence speed and stability might reflect male stamina. Apart from the acoustic differences with mating status, there is a nonsignificant tendency for back-feather iridescence to be of shorter reflectance wavelength spectra in mated than in unmated males, which, when combined with acoustic variables, improves prediction of age class and mating status.

[Acceptability of a test for antibodies against HIV in a group of pregnant women in Yucatan, Mexico]. / Aceptabilidad para la detección de anticuerpos contra el VIH en un grupo de mujeres embarazadas de Yucatán, México.

OBJECTIVE: To evaluate the acceptability of a test for antibodies against HIV (Ab-HIV) in a group of pregnant women in Yucatan, Mexico. PATIENTS AND METHODS: A clinical and epidemiological study was carried out on 310 pregnant women at different health centers in Yucatan Mexico, from January 2000 to March 2001. A questionnaire was applied to determine information in relation to HIV infection and acceptability of the test. Prior counselling was given to all those who accepted being tested. RESULTS: The median age was 24 (range 14 to 42). A 64.5% had a basic education, 91.6% were homemakers; 38% of the sexual partners worked away from home; 15% said they had more than one sexual partner; 31% had leukorrhea at the time of testing and 69% at some time in the past. Ninety percent of the women accepted being tested for HIV and all of them showed negative results. CONCLUSION: The acceptability of the test was similar to that reported in the international literature. The cost benefits of such a test must be considered, but always within the values of prevailing normative and respect of human rights of women. Despite zero prevalence, we found factors favourable for HIV infection.

Effects of rapid global warming at the Paleocene-Eocene boundary on neotropical vegetation.

Temperatures in tropical regions are estimated to have increased by 3° to 5°C, compared with Late Paleocene values, during the Paleocene-Eocene Thermal Maximum (PETM, 56.3 million years ago) event. We investigated the tropical forest response to this rapid warming by evaluating the palynological record of three stratigraphic sections in eastern Colombia and western Venezuela. We observed a rapid and distinct increase in plant diversity and origination rates, with a set of new taxa, mostly angiosperms, added to the existing stock of low-diversity Paleocene flora. There is no evidence for enhanced aridity in the northern Neotropics. The tropical rainforest was able to persist under elevated temperatures and high levels of atmospheric carbon dioxide, in contrast to speculations that tropical ecosystems were severely compromised by heat stress.

Corticosterone metabolites in blue tit and pied flycatcher droppings: effects of brood size, ectoparasites and temperature.

The hypothalamic-pituitary-adrenal (HPA) axis of birds induces the secretion of corticosterone (CORT) as a response to different ecological variables. In this study we tested experimentally if manipulations of brood size or ectoparasitism led to subsequent differences in the concentration of excreted CORT metabolites of adult and nestling blue tits (Cyanistes caeruleus). No significant effect of the manipulation of brood size was detected in adults or nestlings. No significant effect of ectoparasitism was detected in males or nestlings, although females from uninfested nests showed lower concentrations of excreted CORT metabolites. In addition, we analysed if weather conditions had an influence on the concentration of excreted CORT metabolites of blue tits and pied flycatchers (Ficedula hypoleuca) breeding in the same forest. We detected no effect of weather conditions on adults, but nestlings of both species showed a negative correlation between their excreted CORT metabolites and the average mean temperatures they were subjected to during their growth. This effect was not found in blue tits in a colder year, suggesting that the sensitivity of the HPA axis to ambient temperature may be subjected to interannual variation. Moreover, we found a positive effect of the maximum temperature on the day of sampling on the concentration of CORT metabolites of blue tit nestlings in one of the years. These results suggest that weather conditions may act as environmental stressors to which the HPA axis of blue tit and pied flycatcher nestlings may be sensitive.

Testosterone levels and gular pouch coloration in courting magnificent frigatebird (Fregata magnificens): variation with age-class, visited status and blood parasite infection.

Male magnificent frigatebirds (Fregata magnificens) possess a seasonally expressed skin ornament, namely the red and inflatable gular pouch, and are, therefore, a convenient model for the study of some theories related to the evolution of possible testosterone-dependent sexual skin coloration. Here we report the findings of a study performed over four consecutive mating seasons in the Mexican national park Isla Isabel. We investigated differences in testosterone level and gular pouch coloration in courting males in relation to the categories: age-class, visited status and blood parasite infection. Gular pouch color saturation increased with age-class. Investigated frigatebirds were infected only with Haemoproteus iwa (Haemosporida, Haemoproteidae), with an overall prevalence infection of 15.5%. Prevalence of the infection increased with birds' age-class. Testosterone levels were significantly higher in infected males, who also had lighter colored gular pouches. In non-infected males, those visited by a female had higher testosterone levels than non-visited males. Gular pouch lightness and redness were negatively correlated but only redness in non-visited non-infected males was positively correlated with testosterone levels. Gular pouch saturation in visited and infected males was positively correlated with body mass, which also increased with age-class. Mated males had lower testosterone levels and lighter, less red and saturated gular pouch coloration than courting males. In summary, we found that coloration of the male skin ornament could reflect age-class (saturation), parasite infection (lightness) and mated status (all), together with indications of condition and testosterone dependency of ornament expression.

Effects of parental effort on blood stress protein HSP60 and immunoglobulins in female blue tits: a brood size manipulation experiment.

1. Physiological stress in animals may impose a limit for investment in current reproduction in the wild. A brood manipulation experiment was conducted in a population of blue tits Cyanistes caeruleus to study the effect of parental effort on changes in two types of proteins related with stress: the blood stress protein HSP60 and the plasma immunoglobulins. 2. Levels of HSP60 were reduced across the experiment for females attending reduced broods, and females attending enlarged broods experienced a reduction of immunoglobulin levels. Moreover, the overall changes in the levels of both proteins were positively related. 3. By controlling for the change in immunoglobulin levels we found an increase in HSP60 for females in the enlarged treatment, presumably to offset deleterious effects derived from increased effort. 4. Maternal effort was able to partially compensate for the effect of treatment as nestlings did not differ in mass and levels of immunoglobulins and HSP60 among treatments. 5. Physiological stress as reflected in stress and immunoglobulin proteins may limit maternal effort in breeding blue tits.