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Regulatory T cell (Treg) suppression of conventional T cells is a central mechanism that ensures immune system homeostasis. The exact time point of Treg emergence is still disputed. Furthermore, the time of Treg-mediated suppression mechanisms’ emergence has not been identified. It is not yet known whether Treg suppression mechanisms diverged from a single pathway or converged from several sources. We investigated the evolutionary history of Treg suppression pathways using various phylogenetic analysis tools. To ensure the conservation of function for investigated proteins, we augmented our study using nonhomology-based methods to predict protein functions among various investigated species and mined the literature for experimental evidence of functional convergence. Our results indicate that a minority of Treg suppressor mechanisms could be homologs of ancient conserved pathways. For example, CD73, an enzymatic pathway known to play an essential role in invertebrates, is highly conserved between invertebrates and vertebrates, with no evidence of positive selection (w = 0.48, p-value < 0.00001). Our findings indicate that Tregs utilize homologs of proteins that diverged in early vertebrates. However, our findings do not exclude the possibility of a more evolutionary pattern following the duplication degeneration–complementation (DDC) model. Ancestral sequence reconstruction showed that Treg suppression mechanism proteins do not belong to one family; rather, their emergence seems to follow a convergent evolutionary pattern.

Authors' contribution Wkład autorów: A. Study design/planning zaplanowanie badań B. Data collection/entry zebranie danych C. Data analysis/statistics dane-analiza i statystyki D. Data interpretation interpretacja danych E. Preparation of manuscript przygotowanie artykułu F. Literature analysis/search wyszukiwanie i analiza literatury G. Funds collection zebranie funduszy Summary Lyme disease, as one of tick-borne diseases, has been a current epidemiological problem in Poland and in the world for several years. The proportion of borreliosis infections caused by B. burgdorferi spirochaetes is increasing. Difficulties diagnosing this disease with conventional methods have led to growing molecular biology research aimed at developing improved diagnostic tools. Molecular biology methods include all techniques that allow the detection and analysis of nucleic acids. Among them there are methods based on PCR reaction, molecular typing methods (MLST), new generation sequencing (NGS). The current development of this field gives great research opportunities. With regard to B. burgdorferi spirochaete, molecular biology is used to: confirm Lyme borreliosis, identify and type Borreliella spirochaetes, detect them in tick vectors or intermediate hosts, as well as to identify co-infections between different Borreliella species and other tick-borne pathogens. They are meant to significantly improve diagnostic analyzes. This paper reviews the current methods used for the detection and identification of B. burgdorferi. Molecular mechanisms for the survival of spirochaetes in the host, infection vectors and clinical picture of Lyme disease were also discussed.

Teodorowicz, Marcin Weiner. This is an Open Access journal, all articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License (http://creativecommons.org/licenses/by-ncsa/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.

In a healthy physiological state, the mucous membrane of the oral cavity creates a suitable environment for the colonization of Candida spp. yeasts. The aim of the study was to analyze the nanomechanical properties of C. albicans cells derived from the oral cavity of healthy people in a biofilm produced in laboratory conditions. Candida spp. were sampled from the oral cavity of healthy individuals. The process of biofilm formation was analyzed using classic microscopic observation enriched with SEM (scanning electron microscope) and the nanomechanical properties of the cells were assessed with the use of the atomic force microscopy technique (AFM). From all isolated strains in the samples collected of the oral cavity healthy people was detected 79% C. albicans. Other isolated species belonged to the group „non-albicans”. The observations of C. albicans carried out in 24-h cultures revealed a tendency of the cells to form a biofilm structure with multilayer cell systems. The diameter of C. albicans cells in this structure was 5.75 µm, and the length of the pseudohyphae was 17.08 µm. The presence of an extracellular substance surrounding the C. albicans cells was detected. The mean value of the adhesion force determined for C. albicans cells was 4.01 nN. Areas with increased hardness (Force Modulation Mode signal; FMM signal) were found mainly in the zones of cells in contact with the glass substrate. The analysis of Candida cells in liquid samples gives satisfactory results, as it prevents unfavorable changes in the cell surface and thus provides more reliable results. The quality of the biofilm is probably related to the nanomechanical properties of C. albicans cells and may consequently contribute to the stability of the biofilm structures and their susceptibility or resistance to antifungal drugs. The presence of Candida spp. especially in companion animals (dogs, cats) poses a risk of their transmission to the human organism. For this reason, it is advisable to undertake additional research to analyze the ability of zoonotic-origin Candida spp. to form biofilms with comparison of the biofilm-formation capacity of species isolated from humans.