Use of Vocal Fingerprinting for Specific Discrimination of Gray (Microcebus murinus) and Rufous Mouse Lemurs (Microcebus rufus)

Advertisement calls are often important noninvasive tools for discriminating cryptic species and for assessing specific diversity and speciation patterns in nature. We investigated the contribution of these calls to uncover specific diversity in nocturnal Malagasy lemurs. We compared sexual advertisement and predator advertisement calls of two mouse lemur species, western gray and eastern rufous mouse lemurs (Microcebus murinus and M. rufus, respectively) living in two contrasting habitats (dry deciduous vs. rain forest), and analyzed them statistically. Both species emitted several highly variable whistle calls in the context of predator-avoidance. Intrapopulation variation was high and overlapped interspecific variation. Sexual advertisement calls, given in the mating context, displayed a totally distinct, species-specific acoustic structure. Whereas gray mouse lemurs produced rapidly multifrequency modulated, long trill calls, rufous mouse lemurs gave slowly frequency-modulated short chirp calls. Our results suggest specific status for gray and rufous mouse lemurs and indicate the importance of predation and social needs in shaping vocal communication.     

Co-transplantation of human hematopoietic stem cells and human breast cancer cells in NSG mice: A novel approach to generate tumor cell specific human antibodies

Humanized tumor mice (HTM) were generated by the co-transplantation of human hematopoietic stem cells and human breast cancer cells overexpressing HER2 into neonatal NOD-scid IL2Rγ^null (NSG) mice. These mice are characterized by the development of a human immune system in combination with human breast cancer growth. Due to concurrent transplantation into newborn mice, transfer of MHC-mismatched tumor cells resulted in solid coexistence and immune cell activation (CD4⁺ T cells, natural killer cells, and myeloid cells), but without evidence for rejection. Histological staining of the spleen of HTM revealed co-localization of human antigen-presenting cells together with human T and B cells allowing MHC-dependent interaction, and thereby the generation of T cell-dependent antibody production. Here, we investigated the capability of these mice to generate human tumor-specific antibodies and correlated immunoglobulin titers with tumor outgrowth. We found detectable IgM and also IgG amounts in the serum of HTM, which apparently controlled tumor development when IgG serum concentrations were above 10 µg/ml. Western blot analyses revealed that the tumor-specific antibodies generated in HTM did not recognize HER2/neu antigens, but different, possibly relevant antigens for breast cancer therapy. In conclusion, HTM offer a novel approach to generate complete human monoclonal antibodies that do not require further genetic manipulation (e. g., humanization) for a potential application in humans. In addition, efficacy and safety of the generated antibodies can be tested in the same mouse model under human-like conditions. This might be of particular interest for cancer subtypes with no currently available antibody therapy.     

Glatiramer Acetate Increases Phagocytic Activity of Human Monocytes In Vitro and in Multiple Sclerosis Patients

Beside its effects on T cells, a direct influence on cells of the myelo-monocytic lineage by GA becomes evident. Recently, we demonstrated that GA drives microglia to adopt properties of type II antigen presenting cells (APC) and increases their phagocytic activity. In the present work, we focused on human blood monocytes in order to examine whether GA may increase phagocytic activity in vivo and to evaluate the molecular mechanisms explaining this new discovered mode of action. Peripheral blood mononuclear cells (PBMC) were obtained using a Biocoll-Isopaque gradient and monocytes were subsequently isolated by using CD14 MicroBeads. Phagocytic activity was determined by flow cytometric measurement of the ingestion of fluorescent beads. Flow cytometry was also used to assess monocytic differentiation and expression of phagocytic receptors. Monocytes of GA treated MS patients exhibited a significantly higher phagocytic activity than those of healthy controls or non-treated MS patients. In vitro, a significant phagocytic response was already detectable after 1 h of GA treatment at the concentrations of 62.5 and 125 µg/ml. A significant increase at all concentrations of GA was observed after 3 h and 24 h, respectively. Only monocytes co-expressing CD16, particularly CD14⁺⁺CD16⁺ cells, were observed to phagocytose. Treatment of monocytes with IL-10 and supernatants from GA-treated monocytes did not alter phagocytosis. We observed a decrease in CD11c expression by GA while no changes were found in the expression of CD11b, CD36, CD51/61, CD91, TIM-3, and CD206. In our blocking assays, treatment with anti-CD14, anti-CD16, anti-TIM3, anti-CD210, and particularly anti-CD36 antibodies led to a decrease in phagocytosis. Our results demonstrate a new mechanism of action of GA treatment that augments phagocytic activity of human monocytes in vivo and in vitro. This activity seems to arise from the CD14⁺⁺CD16⁺ monocyte subset.     

Combined behavioral and c-Fos studies elucidate the vital role of sodium for odor detection

Salt, known as taste quality, is generally neglected in olfaction, although the olfactory sensory neurons stretch into the salty nasal mucus covering the olfactory epithelium (OE). Using a psychophysical approach, we directly and functionally demonstrate in the awake rat for a variety of structurally diverse odorants that sodium is a critical factor for olfactory perception and sensitivity, both very important components of mammalian communication and sexual behavior. Bathing the olfactory mucus with an iso-osmotic sodium-free buffer solution results in severe deficits in odorant detection. However, sensitivity returns fully within a few hours, indicating continuous mucus production. In the presence of sodium in the mucus covering the OE, all odorants induce odorant-specific c-Fos expression in the olfactory bulb. Yet, if sodium is absent in the mucus, no c-Fos expression is induced as demonstrated for n-octanal. Our noninvasive approach to induce anosmia in mammals here presented--which is fully reversible within hours--opens new possibilities to study the functions of olfactory communication in awake animals.     

Representation of target-bound drugs by computed conformers: implications for conformational libraries

Background  

The increasing number of known protein structures provides valuable information about pharmaceutical targets. Drug binding sites are identifiable and suitable lead compounds can be proposed. The flexibility of ligands is a critical point for the selection of potential drugs. Since computed 3D structures of millions of compounds are available, the knowledge of their binding conformations would be a great benefit for the development of efficient screening methods.     

Tolerance of thermophilic and hyperthermophilic microorganisms to desiccation

We examined short- and long-term desiccation tolerance of 31 strains of thermophilic and hyperthermophilic Archaea and thermophilic phylogenetically deep-branching Bacteria. Seventeen organisms showed a significant high ability to withstand desiccation. The desiccation tolerance turned out to be species-specific and was influenced by several parameters such as storage temperature, pH, substrate or presence of oxygen. All organisms showed a higher survival rate at low storage temperatures (−20°C or below) than at room temperature. Anaerobic and microaerophilic strains are influenced negatively in their survival by the presence of oxygen during desiccation and storage. The desiccation tolerance of Sulfolobales strains is co-influenced by the pH and the substrate of the pre-culture. The distribution of desiccation tolerance in the phylogenetic tree of life is not domain specific. Surprisingly, there are dramatic differences in desiccation tolerance among organisms from the same order and even from closely related strains of the same genus. Our results show that tolerance of vegetative cells to desiccation is a common phenomenon of thermophilic and hyperthermophilic microorganisms although they originated from quite different non-arid habitats like boiling acidic springs or black smoker chimneys.     

Detergent-Like Activity and α-Helical Structure of Warnericin RK, an Anti-Legionella Peptide

Warnericin RK is the first antimicrobial peptide known to be active against Legionella pneumophila, a pathogen bacterium that is responsible for severe pneumonia. Strikingly, this peptide displays a very narrow range of antimicrobial activity, almost limited to the Legionella genus, and a hemolytic activity. A similar activity has been described for δ-lysin, a well-known hemolytic peptide of Staphylococci that has not been described as antimicrobial. In this study we aimed to understand the mode of action of warnericin RK and to explain its particular target specificity. We found that warnericin RK permeabilizes artificial membranes in a voltage-independent manner. Osmotic protection experiments on erythrocytes showed that warnericin RK does not form well-defined pores, suggesting a detergent-like mode of action, as previously described for δ-lysin at high concentrations. Warnericin RK also permeabilized Legionella cells, and these cells displayed a high sensitivity to detergents. Depending on the detergent used, Legionella was from 10- to 1000-fold more sensitive than the other bacteria tested. Finally, the structure of warnericin RK was investigated by means of circular dichroism and NMR spectroscopy. The peptide adopted an amphiphilic α-helical structure, consistent with the proposed mode of action. We conclude that the specificity of warnericin RK toward Legionella results from both the detergent-like mode of action of the peptide and the high sensitivity of these bacteria to detergents.     

Antibody-mediated growth inhibition of Plasmodium falciparum: relationship to age and protection from parasitemia in Kenyan children and adults

Background

Antibodies that impair Plasmodium falciparum merozoite invasion and intraerythrocytic development are one of several mechanisms that mediate naturally acquired immunity to malaria. Attempts to correlate anti-malaria antibodies with risk of infection and morbidity have yielded inconsistent results. Growth inhibition assays (GIA) offer a convenient method to quantify functional antibody activity against blood stage malaria.

Methods

A treatment-time-to-infection study was conducted over 12-weeks in a malaria holoendemic area of Kenya. Plasma collected from healthy individuals (98 children and 99 adults) before artemether-lumefantrine treatment was tested by GIA in three separate laboratories.

Results

Median GIA levels varied with P. falciparum line (D10, 8.8%; 3D7, 34.9%; FVO, 51.4% inhibition). The magnitude of growth inhibition decreased with age in all P. falciparum lines tested with the highest median levels among children <4 years compared to adults (e.g. 3D7, 45.4% vs. 30.0% respectively, p = 0.0003). Time-to-infection measured by weekly blood smears was significantly associated with level of GIA controlling for age. Upper quartile inhibition activity was associated with less risk of infection compared to individuals with lower levels (e.g. 3D7, hazard ratio = 1.535, 95% CI = 1.012–2.329; p = 0.0438). Various GIA methodologies had little effect on measured parasite growth inhibition.

Conclusion

Plasma antibody-mediated growth inhibition of blood stage P. falciparum decreases with age in residents of a malaria holoendemic area. Growth inhibition assay may be a useful surrogate of protection against infection when outcome is controlled for age.