The Antibacterial Activity of Erythrocytes From Goose (Anser domesticus) Can Be Associated With Phagocytosis and Respiratory Burst Generation

In the lumen of blood vessels, there are large numbers of erythrocytes, which are approximately 95% of the total blood cells. Although the function of erythrocytes is to transport oxygen in the organism, recent studies have shown that mammalian and teleost erythrocytes are involved in the immune response against bacterial infections. However, the immune mechanisms used by avian erythrocytes are not yet clear. Here, we demonstrated that erythrocytes from goose have the ability to phagocytose as well as conduct antimicrobial activity. Firstly, we revealed the phagocytosis or adhesion activity of goose erythrocytes for latex beads 0.1-1.0 μm in diameter by fluorescence microscopy, and scanning and transmission electron microscopy. The low cytometry results also proved that goose erythrocytes had a wide range of phagocytic or adhesion activity for different bacteria. Followed, the low cytometry analysis data further explored that the goose erythrocytes contain the ability to produce reactive oxygen species (ROS) and inducible nitric oxide synthase (iNOS) in response to bacterial stimulation, and also up-regulated the expression of NOX family includes NOX1 and NOX5. Finally, we also found that goose erythrocytes showed a powerful antibacterial activity against all the three bacteria, meanwhile the stimulation of three kinds of bacteria up-regulated the expression of inflammatory factors, and increased the production of antioxidant enzymes to protect the cells from oxidative damage. Herein, our results demonstrate that goose Erythrocytes possess a certain phagocytic capacity and antioxidant system, and that the antimicrobial activity of erythrocytes can occurred through the production of unique respiratory burst against foreign pathogenic bacteria, which provides new clues to the interaction between bacteria and avian erythrocytes.

ARTIFACTS OF FORMED ELEMENTS AND PLASMA OF BIRD BLOOD, THEIR GENESIS AND DIAGNOSTIC SIGNIFICANCE

The work is devoted to the study of literature data (humane and veterinary medicine) and the practical analysis of artifacts formed elements and plasma in peripheral blood smears of birds in a model of broiler chickens Gallus gallus L. of early postnatal ontogenesis. The age of the studied clinically healthy chicks and young hens was: day 1, day 7, day 23 and day 42 (n = 40). We studied 158 (n = 158) high-resolution color micrographs of the fields of view, in blood smears stained according to Pappenheim. As a result, single artifacts of avian erythrocytes were identified: cytoplasmic vacuoles of various pattern character, scalloped «bitten» edges of cells. Artifacts of blood plasma were found: pericellular and adhesioned on the cell surface of colored coagulated granularity. In some cases, this granularity imitated the toxic forms of granulocytes and agranulocytes in the peripheral blood of birds. It is necessary to distinguish artifacts of cells and plasma in peripheral blood smears from adaptive changes and symptoms of infectious, invasive and non-infectious diseases.

Revisiting the question of nucleated versus enucleated erythrocytes in birds and mammals

Erythrocyte enucleation is thought to have evolved in mammals to support their energetic cost of high metabolic activities. However, birds face similar selection pressure yet possess nucleated erythrocytes. Current hypotheses on the mammalian erythrocyte enucleation claim that the absence of cell organelles allows erythrocytes to 1) pack more hemoglobin into the cells to increase oxygen carrying capacity and 2) decrease erythrocyte size for increased surface area-to-volume ratio, and improved ability to traverse small capillaries. In this article, we first empirically tested current hypotheses using both conventional and phylogenetically informed analysis comparing literature values of mean cell hemoglobin concentration (MCHC) and mean cell volume (MCV) between 181 avian and 194 mammalian species. We found no difference in MCHC levels between birds and mammals using both conventional and phylogenetically corrected analysis. MCV was higher in birds than mammals according to conventional analysis, but the difference was lost when we controlled for phylogeny. These results suggested that avian and mammalian erythrocytes may employ different strategies to solve a common problem. To further investigate existing hypotheses or develop new hypothesis, we need to understand the functions of various organelles in avian erythrocytes. Consequently, we covered potential physiological functions of various cell organelles in avian erythrocytes based on current knowledge, while making explicit comparisons to their mammalian counterparts. Finally, we proposed by taking an integrative and comparative approach, using tools from molecular biology to evolutionary biology, would allow us to better understand the fundamental physiological functions of various components of avian and mammalian erythrocytes.

Taurine is Covalently Incorporated into Alpha Tubulin

We use various methods of high resolution mass spectrometry to demonstrate that taurine is covalently attached to the carboxyl terminus of alpha Tubulin from avian erythrocytes. The alpha Tubulin terminal residue, a tyrosine, must already be removed before covalent addition of taurine, via a known cycle of de-tyrosination and re-tyrosination. Taurination appears to stop this cycle. Taurine is the most abundant free amino acid in the body but this is the first time that it has been shown to be covalently incorporated into any protein.

Taurine is Covalently Incorporated into Alpha Tubulin

We use various methods of high resolution mass spectrometry to demonstrate that taurine is covalently attached to the carboxyl terminus of alpha Tubulin from avian erythrocytes. The alpha Tubulin terminal residue, a tyrosine, must already be removed before covalent addition of taurine, via a known cycle of de-tyrosination and re-tyrosination. Taurination appears to stop this cycle. Taurine is the most abundant free amino acid in the body but this is the first time that it has been shown to be covalently incorporated into any protein.

Modelling and DNA topology of compact 2-start and 1-start chromatin fibres

We have investigated the structure of the most compact 30-nm chromatin fibres by modelling those with 2-start or 1-start crossed-linker organisations. Using an iterative procedure we obtained possible structural solutions for fibres of the highest possible compaction permitted by physical constraints, including the helical repeat of linker DNA. We find that this procedure predicts a quantized nucleosome repeat length (NRL) and that only fibres with longer NRLs (≥197 bp) can more likely adopt the 1-start organisation. The transition from 2-start to 1-start fibres is consistent with reported differing binding modes of the linker histone. We also calculate that in 1-start fibres the DNA constrains more torsion (as writhe) than 2-start fibres with the same NRL and that the maximum constraint obtained is in accord with previous experimental results. We posit that the coiling of the fibre is driven by overtwisting of linker DNA which, in the most compact forms - for example, in echinoderm sperm and avian erythrocytes - could adopt a helical repeat of ∼10 bp/turn. We argue that in vivo the total twist of linker DNA could be modulated by interaction with other abundant chromatin-associated proteins and by epigenetic modifications of the C-terminal tail of linker histones.