Can eggs in a cavity be a female secondary sexual signal? Male nest visits and modelling of egg visual discrimination in blue tits

Eggshell colouration is thought to function as a female-specific secondary sexual trait. While tests of this idea are rapidly accumulating in cavity-nesting birds, some fundamental underlying assumptions remain rarely investigated: namely, can males see eggshell coloration and perceive colour differences between the eggs of different females? We tested these two key assumptions in a natural population of blue tits (Cyanistes caeruleus). Using transponders, we tracked male nest visits and found that all males visited their nest-boxes while eggs were present and often visually accessible. Interestingly, some males also visited neighbouring nests. We then tested whether birds could detect eggshell coloration using models of avian colour vision; models were performed with and without limitations on visual performance owing to dim light. Both models found that differences in eggshell brightness were often easier to discriminate than differences in colour; there was more contrast in white eggshell background between clutches than within and its contrast against nest background was repeatable within clutches, suggesting these features could act as signals. Yet, the detectability of these contrasts depended entirely on model assumptions of visual limitations. Consequently, we need a better understanding of underlying visual mechanisms in dim-light environments and behavioural discrimination experiments before confirming the signalling potential of eggshell coloration.     

Partial Resistance of Carrot to Alternaria dauci Correlates with In Vitro Cultured Carrot Cell Resistance to Fungal Exudates

Although different mechanisms have been proposed in the recent years, plant pathogen partial resistance is still poorly understood. Components of the chemical warfare, including the production of plant defense compounds and plant resistance to pathogen-produced toxins, are likely to play a role. Toxins are indeed recognized as important determinants of pathogenicity in necrotrophic fungi. Partial resistance based on quantitative resistance loci and linked to a pathogen-produced toxin has never been fully described. We tested this hypothesis using the Alternaria dauci – carrot pathosystem. Alternaria dauci, causing carrot leaf blight, is a necrotrophic fungus known to produce zinniol, a compound described as a non-host selective toxin. Embryogenic cellular cultures from carrot genotypes varying in resistance against A. dauci were confronted with zinniol at different concentrations or to fungal exudates (raw, organic or aqueous extracts). The plant response was analyzed through the measurement of cytoplasmic esterase activity, as a marker of cell viability, and the differentiation of somatic embryos in cellular cultures. A differential response to toxicity was demonstrated between susceptible and partially resistant genotypes, with a good correlation noted between the resistance to the fungus at the whole plant level and resistance at the cellular level to fungal exudates from raw and organic extracts. No toxic reaction of embryogenic cultures was observed after treatment with the aqueous extract or zinniol used at physiological concentration. Moreover, we did not detect zinniol in toxic fungal extracts by UHPLC analysis. These results suggest that strong phytotoxic compounds are present in the organic extract and remain to be characterized. Our results clearly show that carrot tolerance to A. dauci toxins is one component of its partial resistance.     

Ecotourism disturbance to wildfowl in protected areas: historical, empirical and experimental approaches in the Camargue, Southern France

Ecotourism is becoming very popular, especially in protected areas where wildlife concentrate and is easier to observe, but the consequences of associated disturbance have seldom be quantified other than in the short-term, making the sustainability of this activity untested. We combined a historical, an empirical and an experimental approach to assess the long-, medium- and short-term consequences of disturbance to wintering wildfowl (Anatidae) in a wetland of international importance in the Camargue, Southern France. In the short-term, disturbance made teal (Anas crecca) move away temporarily from observation blinds without leaving the waterbody. Wildfowl fed more after disturbance, disrupting their normal resting activities. In the medium-term, waterbodies with more tourists did not host fewer birds: conversely the most heavily disturbed one hosted the highest wildfowl density. In the long term, wildfowl numbers were not related with the number of visitors. When practiced with appropriate guiding of people, and where appropriate facilities are provided to limit human disturbance as done here, ecotourism may not affect wintering wildfowl other than reversibly in the very short term. The legitimate demand of the public for access, even in fragile protected areas, may therefore be sustainable under some conditions.     

Genetic variation and drought response in two Populus × euramericana genotypes through 2-DE proteomic analysis of leaves from field and glasshouse cultivated plants

Genotype and water deficit effects on leaf 2-DE protein profiles of two Populus deltoides × Populus nigra, cv. ‘Agathe_F’ and ‘Cima’, were analysed over a short-term period of 18 days in glasshouse using 4-month-old rooted cuttings and over a long-lasting period of 86 days in open field using 4-year-old rooted cuttings. Leaf proteomes were analyzed using two-dimensional gel electrophoresis, and proteins were identified after database searching from MS peptide spectra.A reliable genotype effect was observed in the leaf proteome over experiment locations, water regimes and sampling dates. Quantitative differences between genotypes were found. Most of them corresponded to proteins matching isoforms or post-translational modification variants. However, ‘Cima’ displayed the highest abundance of antioxidant enzymes.In response to water deficit, about 10% of the reproducible spots significantly varied regardless of the experiment location, among which about 25% also displayed genotype-dependent variations. As a whole, while ‘Cima’ differed from ‘Agathe_F’ by increased abundance of enzymes involved in photorespiration and in oxidative stress, ‘Agathe_F’ was mainly differentiated by increased abundance of enzymes involved in photosynthesis.     

Histone phosphorylation: how to proceed

Among all posttranslational modifications that occur on histone tails, phosphorylation is the one that establishes a direct link between chromatin remodeling and intracellular signaling pathways. Specific, conserved serine residues are present on the N-terminal tails of each histone. These are phosphoacceptor sites for a number of kinases, whose identification is essential to decipher the transduction routes leading to various physiological responses. In the case of histone H3, phosphorylation at the Ser10 residue may lead to either activated gene expression or chromatin condensation during mitosis. In addition, phosphorylation at specific sites may be coupled to other distinct modifications, such as acetylation and methylation, generating the so-called "histone code" which postulates that well defined combinatorial modifications at histone tails correspond to specific physiological responses. Here we describe a number of experimental methodologies that are essential for the study of histone phosphorylation. While chromatin immunoprecipitation is useful in recognizing gene targets, the in-gel kinase assay is a first, essential step in establishing the identity of the kinase(s) that operates in response to a specific signaling pathway. The subsequent use of in vitro kinase assays is helpful in validating the implication of a candidate kinase. These powerful approaches are important as identification of the signaling transduction routes leading to chromatin remodeling is critical to an understanding of all cellular processes.     

Laparoscopic appendectomy to remove a metallic foreign body in a wild Bornean orangutan (Pongo pygmaeus) undergoing rehabilitation

A laparoscopic appendectomy was performed in a wild orangutan (Pongo pygmaeus) undergoing rehabilitation, for a metal nail found on radiographs, using 3‐mm instrumentation. Post‐operative healing was rapid and uneventful, with return to the forest within 10 days. This is the first report of minimally invasive surgery in a wild orangutan.     

Segmental duplications arise from Pol32-dependent repair of broken forks through two alternative replication-based mechanisms

The propensity of segmental duplications (SDs) to promote genomic instability is of increasing interest since their involvement in numerous human genomic diseases and cancers was revealed. However, the mechanism(s) responsible for their appearance remain mostly speculative. Here, we show that in budding yeast, replication accidents, which are most likely transformed into broken forks, play a causal role in the formation of SDs. The Pol32 subunit of the major replicative polymerase Poldelta is required for all SD formation, demonstrating that SDs result from untimely DNA synthesis rather than from unequal crossing-over. Although Pol32 is known to be required for classical (Rad52-dependant) break-induced replication, only half of the SDs can be attributed to this mechanism. The remaining SDs are generated through a Rad52-independent mechanism of template switching between microsatellites or microhomologous sequences. This new mechanism, named microhomology/microsatellite-induced replication (MMIR), differs from all known DNA double-strand break repair pathways, as MMIR-mediated duplications still occur in the combined absence of homologous recombination, microhomology-mediated, and nonhomologous end joining machineries. The interplay between these two replication-based pathways explains important features of higher eukaryotic genomes, such as the strong, but not strict, association between SDs and transposable elements, as well as the frequent formation of oncogenic fusion genes generating protein innovations at SD junctions.