Starting at the end: telomeres and telomerase in arthropods

Telomere composition and structure have been studied in several arthropods allowing us to better understand the evolution of such an important portion of the eukaryotic chromosomes. Genes coding for telomerase reverse transcriptase (TERT) have been sequenced and studied in few arthropod species only,where they resulted highly transcribed also in somatic tissues suggesting a different TERT regulation in respect to vertebrates. Contrary to the strict conservation of telomeres,subtelomeric regions were more polymorphic and heterogeneous in composition and frequently contained retrotransposable elements that strongly influenced subtelomere evolution

Distribution and molecular composition of heterochromatin in the holocentric chromosomes of the aphid Rhopalosiphum padi (Hemiptera: Aphididae)

In order to study the structure of holocentric chromosomes in aphids, the localization and the composition of Rhopalosiphum padi heterochromatin and rDNA genes have been evaluated at cytogenetic and molecular level. In particular, heterochromatin resulted located on all the chromosomes both in intercalary and telomeric positions. Moreover, enzymatic digestion of R. padi genome put in evidence a DraI satellite DNA which has been isolated, cloned and sequenced. FISH experiments showed that this satellite DNA clusters in an intercalary C-positive band on the two X chromosomes

Nest box selection and reproduction of European Rollers in Central Italy: a 7-year study

Background: Changes and increased mechanisation of agricultural practices have influenced the biodiversity composition of farmland habitats and caused a decline of bird communities in many European countries. The removal of shrubs and large trees rich in natural cavities, has also led to a drastic decrease in nest site availability for cavity-nesting bird species. Nest-boxes are a common conservation tool used to improve nest-site availability, and have helped to reverse declines in many endangered bird populations. Nonetheless to maximize the results of such interventions it is crucial to know where nest-boxes should be sited. The objective of this study was to investigate the effectiveness of the nest-box program for the European Roller (Coracias garrulus) population of Lazio region (Central Italy). More specifically, we focused on what landscape features were preferred (or avoided) in the process of nest box selection and how they influenced population's breeding parameters. Particular attention was paid to identifying potential limitations and to provide management recommendations for future interventions. Methods: Using data from 70 nest boxes sited on power lines monitored over a 7-year period (representing 140 breeding attempts), we developed probability functions to evaluate if nest box location, in terms of distance from habitat resources and habitat composition and structure, had an effect on nest box occupancy and on the main reproductive parameters. Results: Nest boxes were more likely to be occupied if they were located near arable fields and in areas characterized by a higher amount of incoming solar radiation. Higher fledging success was associated with fallow fields and with a moderate/low habitat structural complexity. Higher breeding success was associated with solar radiation and with greater distance from urban areas. Conclusions: Our results highlight the importance of specific habitat variables in influencing nest occupancy, and show which drivers primarily affect species’ reproduction and persistence over time. Siting nest boxes in habitats where occupancy rate and fledging success is higher, such as in arable and fallow fields and on south-facing slopes where solar radiation is maximised, may help to extend the suitable habitat for rollers and facilitate its local expansion