Do great tits (Parus major) starve to reproduce?

To test whether nest abandonment is associated with parental health state, reproductive parameters and parental condition indices were examined in relation to brood desertion in great tits. Before desertion, pairs that abandoned their broods in the second half of the nestling period had significantly higher nestling mortality as well as lower average weight of nestlings and entire broods. Independently of brood size, female great tits that deserted their broods on average weighed 1 g (>5%) more than non-deserters. Comparison of metabolic profiles revealed that deserting females were in better nutritional condition (inclined to fat deposition) than non-deserters, which showed symptoms of postresorptive catabolic state, as indicated by a lower level of plasma triglycerides, very low density lipoproteins, and a higher level of free fatty acids and β-hydroxy-butyrate. These results suggest that desertion can be regarded as a reproductive restraint and that non-deserting females invested at least some of their maintenance resources on brood rearing. We found no evidence that desertion or non-desertion was associated with age- or disease-related differences in residual reproductive values. Male condition was not related to brood abandonment, suggesting that desertions were primarily initiated by females. Received: 16 November 1998 / Accepted: 1 February 1999     

The glycine arginine‐rich domain of the RNA‐binding protein nucleolin regulates its subcellular localization

Nucleolin is a multifunctional RNA Binding Protein (RBP) with diverse subcellular localizations, including the nucleolus in all eukaryotic cells, the plasma membrane in tumor cells, and the axon in neurons. Here we show that the glycine arginine rich (GAR) domain of nucleolin drives subcellular localization via protein‐protein interactions with a kinesin light chain. In addition, GAR sequences mediate plasma membrane interactions of nucleolin. Both these modalities are in addition to the already reported involvement of the GAR domain in liquid‐liquid phase separation in the nucleolus. Nucleolin transport to axons requires the GAR domain, and heterozygous GAR deletion mice reveal reduced axonal localization of nucleolin cargo mRNAs and enhanced sensory neuron growth. Thus, the GAR domain governs axonal transport of a growth controlling RNA‐RBP complex in neurons, and is a versatile localization determinant for different subcellular compartments. Localization determination by GAR domains may explain why GAR mutants in diverse RBPs are associated with neurodegenerative disease.     

Health impact of blood parasites in breeding great tits

Hypotheses of hemoparasite-mediated sexual selection and reproductive costs rely on the assumption that avian blood parasite infections are harmful to their hosts. To test the validity of this assumption, we examined the health impact of Haemoproteus blood parasites on their great tit (Parus major) host. We hypothesised that if blood parasites impose any serious health impact on their avian hosts, then infected individuals must differ from uninfected ones in respect to hemato-serological general health and immune parameters. A 3-year study of two great tit populations, breeding in contrasting (urban and rural) habitats in south-east Estonia, revealed that Haemoproteus blood parasites affected the health state of their avian hosts. Infected individuals had elevated lymphocyte hemoconcentration and plasma gamma-globulin levels, indicating that both cell-mediated and humoral immune response mechanisms are involved in host defence. The effect of parasites on cell-mediated immunity was both age- and sex-specific, as infection status affected peripheral blood lymphocyte counts only in males, and among these, the magnitude of response was greater in old individuals than yearlings. Heterophile hemoconcentration and plasma albumin levels were not affected by infection status, suggesting that blood stages of Haemoproteus infection do not cause a severe inflammatory response. Parasitism was not related to hematocrit values, indicating that Haemoproteus infection does not cause anemia. In two years, infected individuals were heavier than uninfected ones in the urban but not in the rural study area. This suggests, that under certain circumstances (possibly related to reproductive tactics), breeding great tits may avoid losing body mass in order to save resources for an anti-parasite immune response. Received: 16 February 1998 / Accepted: 22 May 1998     

Expression of immunity and general condition in the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae), in relation to origin and gender

In immunoecological studies, experimental effects usually explain a relatively small proportion of total variation observed in immune parameters, while the large amount of variation remains unexplained. It is crucial to be aware of such natural variation of immune parameters, which may overshadow the effects of the experiment. We examined factors responsible for variation in cellular immunity (estimated as hemocyte concentration) and general condition (estimated as fresh weight) in the Colorado potato beetle, Leptinotarsa decemlineata, originating from two neighboring potato fields, in a common garden experiment. Progeny of beetles collected from the “New” field, where potato was cultured for the first year, had significantly higher hemocyte concentration and fresh weight compared to individuals originating from the “Old” field, where potato had been cultured for several years. Furthermore, hemocyte concentration varied with respect to gender only in beetles originating from the New field, where males had a higher hemocyte concentration than females. No such sex differences were found in beetles originating from the Old field, suggesting that immune traits and general condition of insects originating from geographically close locations/populations may express different sources of variation. Therefore, generalization of immunity–life‐history trade‐offs based on one population/location should be treated with caution.     

QSAR study of mosquito repellents using Codessa Pro

Protection times provided by 31 synthetic repellents against Aedes aegypti mosquitoes were correlated with the chemical structures of these repellents using Codessa Pro software. Two statistically significant quantitative models with R2 values of ca. 0.80 are presented and discussed.     

Formation of melanin-based wing patterns is influenced by condition and immune challenge in Pieris brassicae

According to life‐history theory, trade‐offs emerge because organisms possess a limited amount of resources that they have to allocate between different bodily functions. Here, we tested whether there is a trade‐off between melanin‐based immune response and dark melanized wing patterning in the large white butterfly, Pieris brassicae L. (Lepidoptera: Pieridae), by activating the immune system of pupae and measuring the wing pigmentation of freshly emerged adults. In contrast to expectations, we did not find any negative associations between immune challenge and wing patterning. Furthermore, implanted and punctured male pupae tended to have larger and darker forewing tips as adults compared to controls. Both in females and males, different wing spots were affected by condition‐reflecting traits (e.g., pupal mass, brood), which suggest that formation of wing patterns may be a condition‐dependent process and/or heritable.     

Bioaugmentation in a newly established LECA-based horizontal flow soil filter reduces the adaptation period and enhances denitrification

The possibility of enhancing the denitrification of a newly established LECA-based horizontal subsurface flow (HSSF) soil filter receiving pretreated wastewater from a vertical flow filter was studied. The pilot-scale experiment offers evidence regarding the survival and reproduction of introduced microbes taken from an LECA-based HSSF constructed wetland (CW) that has similar internal conditions, after bioaugmentation into newly established LECA-based HSSF CW mesocosms. Bioaugmentation resulted in a trend towards higher and more stable denitrification in the supplemented mesocosms during the nearly half-year study period.