Unexpected photobleaching of Alexa 488 in a fixed bacterial sample during 2-photon excitation

A sample of fixed bacterial cells was examined by immunofluorescence microscopy using an Alexa 488 conjugated secondary antibody for visualization. Excitation using visible light confirmed the expected photostability of this fluorophore; however, when using 2-photon excitation, Alexa 488 was rapidly and substantially photobleached. The unexpected instability of Alexa 488 under certain conditions may have deleterious consequences if not anticipated and accommodated in experimental protocols.     

A cell-impermeable cyclosporine A derivative reduces pathology in a mouse model of allergic lung inflammation

Although the main regulators of leukocyte trafficking are chemokines, another family of chemotactic agents is cyclophilins. Intracellular cyclophilins function as peptidyl-prolyl cis-trans isomerases and are targets of the immunosuppressive drug cyclosporine A (CsA). Cyclophilins can also be secreted in response to stress factors, with elevated levels of extracellular cyclophilins detected in several inflammatory diseases. Extracellular cyclophilins are known to have potent chemotactic properties, suggesting that they might contribute to inflammatory responses by recruiting leukocytes into tissues. The objective of the present study was to determine the impact of blocking cyclophilin activity using a cell-impermeable derivative of CsA to specifically target extracellular pools of cyclophilins. In this study, we show that treatment with this compound in a mouse model of allergic lung inflammation demonstrates up to 80% reduction in inflammation, directly inhibits the recruitment of Ag-specific CD4(+) T cells, and works equally well when delivered at 100-fold lower doses directly to the airways. Our findings suggest that cell-impermeable analogs of CsA can effectively reduce inflammatory responses by targeting leukocyte recruitment mediated by extracellular cyclophilins. Specifically blocking the extracellular functions of cyclophilins may provide an approach for inhibiting the recruitment of one of the principal immune regulators of allergic lung inflammation, Ag-specific CD4(+) T cells, into inflamed airways and lungs.     

Molecular evidence places the swallow bug genus Oeciacus Stål within the bat and bed bug genus Cimex Linnaeus (Heteroptera: Cimicidae)

The genera Cimex Linnaeus and Oeciacus Stål (Heteroptera: Cimicidae) are common haematophagous ectoparasites of bats or birds in the Holarctic region. Both their phylogenetic relationship and the systematics of the entire family previously were based on data from morphology and host relationships. Relationships among nine species of the genus Cimex and three species of the genus Oeciacus were analysed here using two mitochondrial and three nuclear genes. Cimex was shown to be paraphyletic with respect to Oeciacus. Oeciacus is thus proposed as a synonym of Cimex. The characteristic phenotype of Oeciacus results from the specific host association with different species of swallows (Hirundinidae). The morphological characters that have been used as diagnostic for the genera were shown to be valid and can be further used for determination at species level. The present analyses recovered the four traditional morphologically defined species groups of the genus Cimex. However, their relationships were poorly resolved – only the C. hemipterus group showed a well‐supported relationship to the C. pipistrelli group. The molecular differentiation within the Palaearctic C. pipistrelli and the Nearctic C. pilosellus species groups correlates with their karyotype differentiation. Furthermore, the analyses suggest poly‐ or paraphyly of the former genus Oeciacus. Either way this indicates there is a large amount of host‐associated phenotypic convergence in either bat‐ or bird‐associated groups of species. The probability of host choice and subsequent switch in Cimicidae are discussed and possible scenarios of the evolution of host association in species of Cimex are suggested.