Ants that Frequently Colonize Twigs in the Leaf Litter of Different Vegetation Habitats

Ants often colonize twigs in the leaf litter, but some species use this resource more frequently than others. We analyzed the composition of the community and the diameter of colonized twigs to test if any species had a size preference. Samples were collected in different vegetation habitats (urban parks, eucalyptus plantations and native forests). In each site, all twigs with an ant colony in six 16-m2 plots were collected and measured, and the ants occupying them were identified. For the analyses, we only included species recorded in 10 or more twigs; these species were considered “common inhabitants” of the twigs (approximately 19.7% of the fauna analyzed). Our results indicate that the community is richer and uses a larger number of twigs of different diameters in the native forest. In addition, some species colonized twigs of similar sizes in different vegetation habitats, suggesting possible selection by ants. 

Occurrence of Ants (Hymenoptera: Formicidae) in both Leaf Litter and Twigs in Atlantic Forest

Twigs in the litter derived from the fragmentation of tree branches form one microhabitat, where entire colonies of ants, both leaf litter and arboreal species, can be found. The objective was to survey ant species that are presente in both the leaf litter and twigs simultaneously. We describe the nest type, the social structure of the colonies and the trophic guild membership of these species. Samples were collected from 10 preserved fragments of Brazilian Atlantic forest. We used Berlese funnels to collect leaf litter ants and manual collection for twig ants. We recorded 80 ant species; 60 species were in leaf litter samples and 35 species were in twigs. Of the total species, only 15 (20%) occurred simultaneously in the leaf litter and in twigs. Of these species, Gnamptogenys striatula, Pheidole sarcina, P. sospes and Solenopsis sp. 2 were the most frequent among leaf litter dwellers, and Myrmelachista catharinae was the most common arboreal species. Most of these belonged to generalista and predator guilds, with “polydomous nests” and colonies monogynous

Confocal and multiphoton imaging of intracellular Ca²⁺

This chapter compares the imaging capabilities of a range of systems including multiphoton microscopy in regard to measurements of intracellular Ca<sup>2+</sup> within living cells. In particular, the excitation spectra of popular fluorescent Ca<sup>2+</sup> indicators are shown during 1P and 2P excitation. The strengths and limitations of the current indicators are discussed along with error analysis which highlights the value of matching the Ca<sup>2+</sup> affinity of the dye to a particular aspect of Ca<sup>2+</sup> signaling. Finally, the combined emission spectra of Ca<sup>2+</sup> and voltage sensitive dyes are compared to allow the choice of the optimum combination to allow simultaneous intracellular Ca<sup>2+</sup> and membrane voltage measurement

Fast fluorescence microscopy for imaging the dynamics of embryonic development

Live imaging has gained a pivotal role in developmental biology since it increasingly allows real-time observation of cell behavior in intact organisms. Microscopes that can capture the dynamics of ever-faster biological events, fluorescent markers optimal for in vivo imaging, and, finally, adapted reconstruction and analysis programs to complete data flow all contribute to this success. Focusing on temporal resolution, we discuss how fast imaging can be achieved with minimal prejudice to spatial resolution, photon count, or to reliably and automatically analyze images. In particular, we show how integrated approaches to imaging that combine bright fluorescent probes, fast microscopes, and custom post-processing techniques can address the kinetics of biological systems at multiple scales. Finally, we discuss remaining challenges and opportunities for further advances in this field

Impact of Sarcoplasmic Reticulum Calcium Release on Calcium Dynamics and Action Potential Morphology in Human Atrial Myocytes: A Computational Study

Electrophysiological studies of the human heart face the fundamental challenge that experimental data can be acquired only from patients with underlying heart disease. Regarding human atria, there exist sizable gaps in the understanding of the functional role of cellular Ca2+ dynamics, which differ crucially from that of ventricular cells, in the modulation of excitation-contraction coupling. Accordingly, the objective of this study was to develop a mathematical model of the human atrial myocyte that, in addition to the sarcolemmal (SL) ion currents, accounts for the heterogeneity of intracellular Ca2+ dynamics emerging from a structurally detailed sarcoplasmic reticulum (SR). Based on the simulation results, our model convincingly reproduces the principal characteristics of Ca2+ dynamics: 1) the biphasic increment during the upstroke of the Ca2+ transient resulting from the delay between the peripheral and central SR Ca2+ release, and 2) the relative contribution of SL Ca2+ current and SR Ca2+ release to the Ca2+ transient. In line with experimental findings, the model also replicates the strong impact of intracellular Ca2+ dynamics on the shape of the action potential. The simulation results suggest that the peripheral SR Ca2+ release sites define the interface between Ca2+ and AP, whereas the central release sites are important for the fire-diffuse-fire propagation of Ca2+ diffusion. Furthermore, our analysis predicts that the modulation of the action potential duration due to increasing heart rate is largely mediated by changes in the intracellular Na+ concentration. Finally, the results indicate that the SR Ca2+ release is a strong modulator of AP duration and, consequently, myocyte refractoriness/excitability. We conclude that the developed model is robust and reproduces many fundamental aspects of the tight coupling between SL ion currents and intracellular Ca2+ signaling. Thus, the model provides a useful framework for future studies of excitation-contraction coupling in human atrial myocytes

Laser‐Based Measurements in Cell Biology

In this chapter, we review the imaging techniques and methods of molecular interrogation made possible by integrating laser light sources with microscopy. We discuss the advantages of exciting fluorescence by laser illumination and review commonly used laser-based imaging techniques such as confocal, multiphoton, and total internal reflection microcopy. We also discuss emerging imaging modalities based on intrinsic properties of biological macromolecules such as second harmonic generation imaging and coherent anti-Raman resonance spectroscopy. Super resolution techniques are presented that exceed the theoretical diffraction-limited resolution of a microscope objective. This chapter also focuses on laser-based techniques that can report biophysical parameters of fluorescently labeled molecules within living cells. Photobleaching techniques, fluorescence lifetime imaging, and fluorescence correlation methods can measure kinetic rates, molecular diffusion, protein-protein interactions, and concentration of a fluorophore-bound molecule. This chapter provides an introduction to the field of laser-based microscopy enabling readers to determine how best to match their research questions to the current suite of techniques

Unidades ciclotomicas

Orientadores: Francisco Thaine Prada, Tenkasi M. ViswanathanDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Ciencia da ComputaçãoResumo: Não informado.Abstract: Not informed.MestradoMestre em Matemátic