Fueling Incubation: Differential Use of Body Stores in Arctic and Temperate-breeding Barnacle Geese (Branta leucopsis)

We compared the use of body stores in breeding Barnacle Geese (Branta leucopsis) in traditional Arctic colonies in the Barents Sea with that in recently established temperate-zone breeding colonies in the Baltic Sea and North Sea by studying female body-mass loss and use of fat and protein stores during incubation. Average daily body-mass loss was almost identical in the 2 temperate-breeding populations (17.0 g and 16.5 g in Baltic Sea and North Sea, respectively), whereas Arctic-breeding females lost significantly less (10.6 g day-1). Temperate-breeding females initiated incubation with body mass 125 g higher than that of Arctic breeders, but at the end of incubation, body mass was similar among the 3 populations, averaging 1,458 g. Body-mass loss during incubation amounted to 23% (North Sea), 22% (Baltic Sea), and 15% (Barents Sea). Fat mass, as measured by isotope dilution in a subsample of females, was consistently higher in North Sea than in Barents Sea birds, but both populations showed similar rates of fat-mass loss (9.4 g day-1, on average). By contrast, loss of fat-free mass (assumed to represent wet protein) amounted to 9.3 g day-1 in North Sea birds but only 1.5 g day-1 in Barents Sea birds. Energy content of 1 g utilized body mass was 21.1 kJ (North Sea) and 34.9 kJ (Barents Sea), which equates to 376 kJ day-1 and 415 kJ day-1 drawn from stored energy, respectively. We suggest that differences in nest-attendance and post-incubation demands are responsible for the differential use of body stores in temperate- and Arctic-breeding Barnacle Geese.

Macrophage-pathogen interactions in infectious diseases: new therapeutic insights from the zebrafish host model

Studying macrophage biology in the context of a whole living organism provides unique possibilities to understand the contribution of this extremely dynamic cell subset in the reaction to infections, and has revealed the relevance of cellular and molecular processes that are fundamental to the cell-mediated innate immune response. In particular, various recently established zebrafish infectious disease models are contributing substantially to our understanding of the mechanisms by which different pathogens interact with macrophages and evade host innate immunity. Transgenic zebrafish lines with fluorescently labeled macrophages and other leukocyte populations enable non-invasive imaging at the optically transparent early life stages. Furthermore, there is a continuously expanding availability of vital reporters for subcellular compartments and for probing activation of immune defense mechanisms. These are powerful tools to visualize the activity of phagocytic cells in real time and shed light on the intriguing paradoxical roles of these cells in both limiting infection and supporting the dissemination of intracellular pathogens. This Review will discuss how several bacterial and fungal infection models in zebrafish embryos have led to new insights into the dynamic molecular and cellular mechanisms at play when pathogens encounter host macrophages. We also describe how these insights are inspiring novel therapeutic strategies for infectious disease treatment

A quantitative in vivo assay for craniofacial developmental toxicity of histone deacetylases

Animal science

Infection of zebrafish embryos with intracellular bacterial pathogens

Zebrafish (Danio rerio) embryos are increasingly used as a model for studying the function of the vertebrate innate immune system in host-pathogen interactions (1). The major cell types of the innate immune system, macrophages and neutrophils, develop during the first days of embryogenesis prior to the maturation of lymphocytes that are required for adaptive immune responses. The ease of obtaining large numbers of embryos, their accessibility due to external development, the optical transparency of embryonic and larval stages, a wide range of genetic tools, extensive mutant resources and collections of transgenic reporter lines, all add to the versatility of the zebrafish model. Salmonella enterica serovar Typhimurium (S. typhimurium) and Mycobacterium marinum can reside intracellularly in macrophages and are frequently used to study host-pathogen interactions in zebrafish embryos. The infection processes of these two bacterial pathogens are interesting to compare because S. typhimurium infection is acute and lethal within one day, whereas M. marinum infection is chronic and can be imaged up to the larval stage (2, 3). The site of micro-injection of bacteria into the embryo (Figure 1) determines whether the infection will rapidly become systemic or will initially remain localized. A rapid systemic infection can be established by micro-injecting bacteria directly into the blood circulation via the caudal vein at the posterior blood island or via the Duct of Cuvier, a wide circulation channel on the yolk sac connecting the heart to the trunk vasculature. At 1 dpf, when embryos at this stage have phagocytically active macrophages but neutrophils have not yet matured, injecting into the blood island is preferred. For injections at 2-3 dpf, when embryos also have developed functional (myeloperoxidase-producing) neutrophils, the Duct of Cuvier is preferred as the injection site. To study directed migration of myeloid cells towards local infections, bacteria can be injected into the tail muscle, otic vesicle, or hindbrain ventricle (4-6). In addition, the notochord, a structure that appears to be normally inaccessible to myeloid cells, is highly susceptible to local infection (7). A useful alternative for high-throughput applications is the injection of bacteria into the yolk of embryos within the first hours after fertilization (8). Combining fluorescent bacteria and transgenic zebrafish lines with fluorescent macrophages or neutrophils creates ideal circumstances for multi-color imaging of host-pathogen interactions. This video article will describe detailed protocols for intravenous and local infection of zebrafish embryos with S. typhimurium or M. marinum bacteria and for subsequent fluorescence imaging of the interaction with cells of the innate immune system

New high-throughput technologies for drug screening in animal models of TB

Animal science

Phagocytosis of mycobacteria by zebrafish macrophages is dependent on the scavenger receptor Marco, a key control factor of pro-inflammatory signalling

Animal science

Common and specific downstream signaling targets controlled by Tlr2 and Tlr5 innate immune signaling in zebrafish

Animal science

Genomic annotation and expression analysis of the zebrafish Rho small GTPase family during development and bacterial infection

Microbial Biotechnolog

Selective sparing of goblet cells and paneth cells in the intestine of methotrexate-treated rats

Proliferation, differentiation, and cell death were studied in small intestinal and colonic epithelia of rats after treatment with methotrexate. Days 1-2 after treatment were characterized by decreased proliferation, increased apoptosis, and decreased numbers and depths of small intestinal crypts in a proximal-to-distal decreasing gradient along the small intestine. The remaining crypt epithelium appeared flattened, except for Paneth cells, in which lysozyme protein and mRNA expression was increased. Regeneration through increased proliferation during days 3-4 coincided with villus atrophy, showing decreased numbers of villus enterocytes and decreased expression of the enterocyte-specific genes sucrase-isomaltase and carbamoyl phosphate synthase I. Remarkably, goblet cells were spared at villus tips and remained functional, displaying Muc2 and trefoil factor 3 expression. On days 8-10, all parameters had returned to normal in the whole small intestine. No methotrexate-induced changes were seen in epithelial morphology, proliferation, apoptosis, Muc2, and TFF3 immunostaining in the colon. The observed small intestinal sparing of Paneth cells and goblet cells following exposure to methotrexate is likely to contribute to epithelial defense during increased vulnerability of the intestinal epithelium

Transcriptome profiling and functional analyses of the zebrafish embryonic innate immune response to Salmonella infection

Animal science