From the ancient Romans, through the Middle Ages, to the late of the nineteenth century, the Aristotelian doctrine of spontaneous generation was one of the most basic laws. Even the invention of the microscope and investigations of Leeuwenhoek and Hook did not disprove the Aritostelian doctrine. Finally, in the eighteenth century, the spontaneous generation doctrine was laid by Louis Pasteur. Moreover, in the first decade of the eighteenth century, nucleus was observed in plant and animal tissues, and Virchow and other scientists presented the view that cells are formed via scission of preexisting cells. In the first decade of the twentieth century, Ross Harrison developed the first techniques of cell culture in vitro, and Burrows and Carrel improved Harrison's cell cultures. In mid-twentieth century, the basic principles for plant and animal cell cultures in vitro were developed, and human diploid cell lines were established. On the basis of knowledge about the cell cycle and gene expression regulation, the first therapeutic proteins were produced using mammalian cell cultures. The end of twentieth century and early twenty-first century brought the progress in 3-D cell culture technology and created the possibility of the tissue engineering and the regenerative medicine development.

Hexagonal boron nitride is often referred to as white graphene. This is a 2D layered material, with a structure similar to graphene. It has gained many applications in cosmetics, dental cements, ceramics etc. Hexagonal boron nitride is also used in medicine, as a drug carrier similar as graphene or graphene oxide. Here we report that this material can be exfoliated in two steps: chemical treatment (via modified Hummers method) followed by the sonication treatment. Afterwards, the surface of the obtained material can be efficiently functionalized with gold nanoparticles. The mitochondrial activity was not affected in L929 and MCF-7 cell line cultures during 24-h incubation, whereas longer incubation (for 48, and 72 h) with this nanocomposite affected the cellular metabolism. Lysosome functionality, analyzed using the NR uptake assay, was also reduced in both cell lines. Interestingly, the rate of MCF-7 cell proliferation was reduced when exposed to h-BN loaded with gold nanoparticles. It is believed that h-BN nanocomposite with gold nanoparticles is an attractive material for cancer drug delivery and photodynamic therapy in cancer killing.

To induce the water solubility of hexagonal boron nitride (h-BN), we exfoliated and functionalized bulk h-BN with hydroxyl groups (h-BN-OH-n). Short-term studies showed that h-BN-OH-n induced low cytotoxicity in different models: insect haemocytes (in vivo), human erythrocytes and mouse fibroblasts (in vitro). We also demonstrated that Alexa Fluor 647-h-BN-OH-n administered topically to the insects passed through the cuticle barrier and was phagocytosed by haemocytes. Nanoflakes did not affect the haemocyte cell membrane and did not interfere with the phagocytosis of latex beads. Long-term immunoassays showed that h-BN-OH-n, despite not inducing haemocytotoxicity, impaired nodulation, the most important cellular immune response in insects. The haemocytes exposed to h-BN-OH-n and then to bacteria differed in morphology and adhesiveness from the haemocytes exposed only to bacteria and exhibited the same morphology and adhesiveness as the control haemocytes. The h-BN-OH-n-induced decrease in nodulation can therefore result from the reduced ability of haemocytes to recognize bacteria, migrate to them or form microaggregates around them, which can lead to dysfunction of the immune system during pathogen infection. Long-term in vivo studies with animal models are still necessary to unambiguously confirm that h-BN is biocompatible and useful for application as a platform for drug delivery or for bioimaging.

The study was aimed at investigating the effect of the Fe 3 O 4 hybrid deposited on graphene oxide (GO-Fe 3 O 4 ) on the relative viability and DNA integrity. The properties of the GO-Fe 3 O 4 hybrid were analyzed using a transmission electron microscopy (TEM), X-ray diffraction technique (XRD) and thermal gravimetric method (TGA), while the effi ciency of graphene oxide covalent functionalization with iron oxide nanospheres was determined by Fourier transform infrared spectroscopy (FT-IR). L929 and MCF-7 cell lines were selected to analyze the biocompatibility of GO-Fe 3 O 4 nanoparticles. The hybrid was tested using WST-1 and LDH leakage assays. DNA integrity was analyzed by agarose gel electrophoresis and micronucleus assay was performed to examine chromosomal damage in the exposed cell lines. The tested GO-Fe 3 O 4 hybrid did not signifi cantly reduce cell metabolism of L929 cells. GO-Fe 3 O 4 hybrid particles only slightly affected the integrity of cell membranes. DNA integrity and micronucleus assays did not indicate genotoxicity of the hybrid.

The LDHA/HaeIII polymorphism (g.2582481G>A) in pigeons is associated with physiological predispositions for rapid return and endurance, which are one of the most desired racing performance traits. Thus, the aim of the study was to analyse the association between the g.2582481G>A polymorphism with the relative expression level of LDHA in the group of young homing pigeons. The results demonstrated differences, but not significant in the relative LDHA expression level in the group of pigeons carrying different LDHA genotype. The highest expression of LDHA gene in pigeons carrying LDHA AG genotype was reported. Moreover, the differences in the average relative quantity of the LDHA gene were different in relation to gender, with a slightly higher expression level of the LDHA gene in females. In conclusion, the highest expression level of LDHA gene in homing pigeons with genotype AG may explain the better racing performance of LDHA AG pigeons reported in previous studies.