The importance of hatching from resting eggs for population dynamics and genetic composition of Daphnia in a deep reservoir

1. Cyclical parthenogens, organisms switching between sexual and asexual mode of reproduction, are common in aquatic habitats. In permanent waterbodies with year‐round persistence of populations, the relevance of sexually produced resting eggs for population dynamics and structure is still largely unexplored. 2. The aim of this study was to investigate the importance of recruitment from resting eggs to Daphnia spp. in a deep dimictic reservoir with overwintering populations (Saidenbach Reservoir, Germany). We linked field studies on Daphnia population dynamics, hatching rates and diapausing egg abundances in the sediment with allozyme analysis of the genetic variability of both the pelagic population and hatchlings from resting eggs. 3. We found higher hatching rates at intermediate depths (10–18 m), although highest diapausing egg abundances were found in the deeper parts of the reservoir. From the extensive field data, we calculated a population budget for the main basin of the reservoir, which showed that hatched daphnids accounted for <1% of the total abundance and explained only a tiny fraction of population growth. 4. The genetic composition (MultiLocus Genotypes, MLG) of the pelagic population was relatively stable throughout the stratified period with up to five among 39 detected MLGs attaining frequencies >5% per date. From 11 MLGs differentiated among hatched daphnids, three were recovered in the pelagic population in perceptible, albeit low frequencies (1–4%). 5. We conclude that the contribution of hatched animals to the spring population dynamics is negligible in situations with an overwintering population present and will only become relevant if densities are extremely low. In this type of system, the significance of the resting egg bank is presumably mainly related to the maintenance of genetic diversity.     

Novel nanoimaging approach: Antibodious polymeric nanolabel for intracellular alpha‐fetoprotein targeted monitoring

This study describes preparation and use of novel labeled and antibodious polymeric nanolabels (anti‐alpha fetoprotein cross‐linked nanolabels) as an immunogenic and semisynthetic nanolabel with potential prognostic and therapeutic roles for hepatoma cancer. Specificity, uptake, and binding efficiencies of the nanolabel have been examined in a human hepatosarcoma cell line HepG2, a human colorectal cell line DLD‐1, and a mouse myoblast cell line C2. Labeling of the cells has been performed by treating live and fixed cells with varying concentrations of the nanolabels and then, the cells have been examined under a fluorescence microscope. In addition, all cell lines have also been labeled using FITC‐conjugated nanotrastuzumab to compare the results obtained with those of the binding of the FITC‐nanoanti‐alpha fetoprotein nanolabels. Results show that FITC‐conjugated anti‐alpha fetoprotein cross‐linked nanolabels have been taken up by both live and fixed cells and have efficiently and specifically labeled HepG2 cells at a quite low concentration. Taken all together, the results indicate that the novel targeted nanoimaging tools and technique demonstrated their ability to detect the distribution of the nanolabels as probes in hepatoma cells. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29: 472–479, 2013     

3-Pyridinylboronic Acid Ameliorates Rotenone-Induced Oxidative Stress Through Nrf2 Target Genes in Zebrafish Embryos

Neurochemical Research - Parkinson’s disease (PD) is one of the most common forms of neurodegenerative diseases and research on potential therapeutic agents for PD continues. Rotenone is a...     

Loss of Dictyostelium ATG9 results in a pleiotropic phenotype affecting growth,development, phagocytosis and clearance and replication of Legionella pneumophila

Infection of Dictyostelium discoideum with Legionella pneumophila resulted in a large number of differentially regulated genes among them three core autophagy genes, ATG8, ATG9 and ATG16. Macroautophagy contributes to many physiological and pathological processes and might also constitute an important mechanism in cell‐autonomous immunity. For further studies we selected the highly conserved ATG9. In colocalization studies with GFP‐tagged ATG9 and different organelle marker proteins we neither observed colocalization with mitochondria, the ER nor lysosomes. However, there was partial colocalization with the Golgi apparatus and many ATG9‐GFP‐containing vesicles localized along microtubules and accumulated around the microtubule organizing centre. ATG9‐deficient cells had pleiotropic defects. In addition to growth defects they displayed severe developmental defects, consistent with the known role of autophagy in Dictyostelium development. Unexpectedly, the ATG9 mutant also had a strong phagocytosis defect that was particularly apparent when infecting the cells with L. pneumophila. However, those Legionellae that entered the host could multiply better in mutant than in wild‐type cells, because of a less efficient clearance in the early and a more efficient replication in the late phase of infection. We conclude that ATG9 and hence macroautophagy has a protective role during pathogen infection.