Nuclear preservation in the cartilage of the Jehol dinosaur Caudipteryx

Previous findings on dinosaur cartilage material from the Late Cretaceous of Montana suggested that cartilage is a vertebrate tissue with unique characteristics that favor nuclear preservation. Here, we analyze additional dinosaur cartilage in Caudipteryx (STM4-3) from the Early Cretaceous Jehol biota of Northeast China. The cartilage fragment is highly diagenetically altered when observed in ground-sections but shows exquisite preservation after demineralization. It reveals transparent, alumino-silicified chondrocytes and brown, ironized chondrocytes. The histochemical stain Hematoxylin and Eosin (that stains the nucleus and cytoplasm in extant cells) was applied to both the demineralized cartilage of Caudipteryx and that of a chicken. The two specimens reacted identically, and one dinosaur chondrocyte revealed a nucleus with fossilized threads of chromatin. This is the second example of fossilized chromatin threads in a vertebrate material. These data show that some of the original nuclear biochemistry is preserved in this dinosaur cartilage material and further support the hypothesis that cartilage is very prone to nuclear fossilization and a perfect candidate to further understand DNA preservation in deep time.

Comparison of 12 DNA extraction kits for vertebrate samples

Comparison of 12 DNA extraction kits for vertebrate samples Martincová, I. Aghová, T. Abstract Obtaining high quality DNA extractions is a crucial step for molecular biology research projects. At present, numerous protocols are available for vertebrate tissue extractions. In the present study we compared eleven column–based protocols and one HotSHOT protocol using similar conditions (i.e., type of sample, weight of starting material). We evaluated time of extraction, quality and quantity of DNA yield, and price of extraction for a single sample. Based on our analysis, the most successful kits for producing DNA with the highest concentration and purity are the JetQuick® Genomic DNA Purification Kit (Genomed) and the NucleoSpin® Tissue (Macherey–Nagel). Nevertheless, it is highly recommended to test various extraction kits with specific samples to find the optimal kit in all aspects of time, quality and cost for a particular project.

Blood cells of adult Drosophila do not expand, but control survival after bacterial infection by induction of Drosocin around their reservoir at the respiratory epithelia

SummaryDrosophila melanogaster has been an excellent model for innate immunity, but the role and regulation of adult blood cells and organismal immunity have remained incompletely understood. Here we address these questions in a comprehensive investigation of the blood cell system in adult Drosophila. As a central finding, we reveal the largest reservoir of blood cells (hemocytes) at the respiratory epithelia (tracheal air sacs) and fat body of the thorax and head. We show that most hemocytes of adult Drosophila are phagocytic macrophages (plasmatocytes), derived by more than 60% from the embryonic lineage that parallels vertebrate tissue macrophages. Surprisingly, in contrast to hemocytes at the larval stage, we find no capacity of the adult blood cell system to expand. Instead, we demonstrate its central role in relaying an innate immune response to tissues surrounding the blood cell reservoir: Hemocytes, through Imd signaling and the Jak/Stat pathway ligand Upd3, act as sentinels of bacterial infection that induce expression of the antimicrobial peptide gene Drosocin in the respiratory epithelia and colocalizing domains of the fat body. We demonstrate that endogenous Drosocin expression in these tissues promotes animal survival after bacterial infection. Our work identifies the first molecular step in a new relay of organismal immunity, establishing adult Drosophila as model to dissect mechanisms of inter-organ immunity.