This review analyzes three studies carried out on Drosophila, which resulted in discoveries that would be impossible while using other subjects. Thanks to these discoveries, events accompanying the...

Evolutionary biologists have always been interested in the origin and evolution of new genes. The most obvious mechanisms of their formation are various types of chromosomal and intergenic rearrangements, suggesting the use of existing genes as the source material. The possibility of the origin of a fully functional gene from noncoding DNA, i.e., de novo, was not rejected but it was practically considered as impossible until recently. Nevertheless, in 1996, after analysis of the yeast Saccharomyces cerevisiae genome, the first experimental evidence of the possibility of de novo gene formation was obtained. Ten years later, genes that do not have homologs, presumably having originated de novo, were found in Drosophila. The relatively high probability of the occurrence of genes de novo, estimated in bioinformatics studies, raised the interest in this topic and made the search for genes of this type relevant. Recently, the number of works devoted to the problem of the emergence of de novo genes in different organisms, including humans, is constantly growing, demystifying this phenomenon. Nevertheless, there are still many questions that require theoretical and practical research. This review is devoted to the problem of finding and characterizing genes that have arisen de novo, as well as to the proposed mechanisms of their occurrence.

Xenobiotic-induced activation of human aryl hydrocarbon receptor target genes in Drosophila is mediated by the epigenetic chromatin modifiers Xenobiotic-induced activation of human aryl hydrocarbon receptor target genes in Drosophila is mediated by the epigenetic chromatin modifiers

Histone chaperones are a class of proteins that bind and transport histones, preventing their chaotic aggregation when forming nucleosomes. Histone chaperones of the NAP (Nucleosome Assembly Protein) family contain a highly conserved central NAP domain, which is necessary for histone binding and nucleosome assembly. They are an essential component in creating and maintaining the eukaryotic chromatin dynamics on which the transcription of many genes depends. The review considers the NAP family of proteins and its specific representatives: NAP1, NAP2, and CG5017/Hanabi. Since they are canonical histone transporters providing effective chromatin remodeling, NAP family proteins are involved in neuronal differentiation, spermatogenesis, and long-term memory formation, which indicates the importance of this family in ontogenesis.

A family of closely related genes, named the d4 family, has been previously identified in mammals. It comprises three genes encoding structurally related proteins. The hallmark of the family is D4 domain—a double-paired finger motif that consists of two tandemly arranged PHD finger domains. These genes are expressed in various tissues and at various developmental stages. Two of those, neuro-d4 and cer-d4, are strictly neurospecific and their expression is developmentally regulated. Another gene, ubi-d4/Requiem is ubiquitously expressed in all embryonic and adult tissues at the same levels. d4 family genes are evolutionary conserved. Human, mouse, rat, and chicken d4 genes have been cloned. The only d4-like gene was found in the genome of nematode C. elegans and hydra H. magnipapillata. The sole member of d4 family was identified also in the genome of D. melanogaster. However, d4 genes are not believed to be present in the genomes of prokaryotes and yeast. This review describes genomic organization and expression of d4 family genes in vertebrates.

Robertsonian (centric-fusion) translocation is the form of chromosomal translocation in which two long arms of acrocentric chromosomes are fused to form one metacentric. These translocations reduce the number of chromosomes while preserving existing genes and are considered to contribute to speciation. We asked whether hypomorphic mutations in genes that disrupt the formation of pericentromeric regions could lead to centric fusion. TBP-related factor 2 (Trf2) encodes an alternative general transcription factor. A decrease of TRF2 expression disrupts the structure of the pericentromeric regions and prevents their association into chromocenter. We revealed several centric fusions in two lines of Drosophila melanogaster with weak Trf2 alleles in genetic experiments. We performed an RNAi-mediated knock-down of Trf2 in Drosophila and S2 cells and demonstrated that Trf2 upregulates expression of D1—one of the major genes responsible for chromocenter formation and nuclear integrity in Drosophila. Our data, for the first time, indicate that Trf2 may be involved in transcription program responsible for structuring of pericentromeric regions and may contribute to new karyotypes formation in particular by promoting centric fusion. Insight into the molecular mechanisms of Trf2 function and its new targets in different tissues will contribute to our understanding of its phenomenon.