Doklady Biological Sciences

A new honey badger, Mellivora indosinica sp. nov., is described on the base of an isolated lower carnassial tooth from the Middle Pleistocene deposits of the Tham Hai cave in Northeast Vietnam (Lang Son Province). Judging by tooth measurements, the new species is larger than all known Mellivorini, including the medium-sized Recent Mellivora capensis, but much smaller than the Neogene giant Eomellivorini. This is the only representative of Mellivorinae in Southeast Asia and evidence for the presence of honey badgers in the Pleistocene Stegodon–Ailuropoda fauna.

Cranial materials of the large hyena Pachycrocuta brevirostris (Gervais, 1850) from the Early Pleistocene (~1.8–1.6 Ma) locality in the Taurida cave (Crimea) belong to individuals of different individual ages, from juvenile to senile. The relative facial length of the "short-faced hyena" P. brevirostris has been shown to be greater than that of the extant spotted hyena Crocuta crocuta (Erxleben, 1777). As P. brevirostris matured, the facial and frontal regions increased significantly in height, and the dorsal profile line of the skull elevated noticeably. New material on P. brevirostris is of great importance for studying the geographical variability and evolution of this widespread species of carnivorous mammals of the Early Pleistocene.

Effective approaches for selecting nuclei in which a gene of interest is in an active state are necessary for studying spatial organization and gene expression regulation. In this work, a novel two-component genetic system was created for the parasegment-specific labeling of nuclei in which the regulatory domain iab-5, which stimulates the homeotic gene Abd-B, is active. The system is based on the integration of a transgene expressing the yeast GAL4 activator under the control of the minimal hsp70 gene promoter into the iab-5 domain, near the early embryonic enhancer. As a result, the iab-5 enhancer induces specific expression of GAL4, which strongly amplifies the expression of the mScarlet fluorescent protein, allowing for the efficient selection of labeled nuclei in which the iab-5 domain is activated. This approach can be used for the selection of target nuclei in which any regulatory element or gene of interest is in an active or repressed state.

Aliphatic aldehydes are involved in many important biological processes, but detection of them at low concentrations requires expensive laboratory equipment and labor-intensive analytical methods. Typically, chromatographic and chromatograph mass spectrometric methods are used for this purpose. Therefore, developing a simple method for detecting aldehydes at low concentrations is a pressing scientific and technical challenge. We have demonstrated that a bacterial bioluminescent system can be effectively used for the semiquantitative determination of biogenic aldehydes in vitro at nanomolar concentrations. Furthermore, this system holds promise for detecting biogenic aldehydes in vivo.

The lipid envelope of the influenza A virus contains two major types of protein spikes formed by the transmembrane hemagglutinin trimers (HA; m.w.80 kDa) and neuraminidase tetramers (NA; m.w.55 kDa), in quantities of 500 and 120, respectively. The third transmembrane protein M2 (m.w. 14 kDa) forms tetramers of ion channels in quantities of about 10-20 per virion. Modeling of the molecular structure using the AlphaFold software tool showed a novel model for a heterocomplex of HA0-M2 proteins, in which the M2 tetramer located inside the HA0 trimer like a “matryoshka doll”. Similar models of the HA0-M2 heterocomplex were obtained for the A/Aichi/2/68 (H3N2) and A/WSN/33 (H1N1) viruses. The resulting HA0-M2 heterocomplex possessed a high structural complementarity of the macromolecular interfaces (ipTM = 0.65), had no structural clashes of atoms in the molecular interfaces (clash score = 0.0), and exhibited stable and reliable intermolecular topology with a high ranking score of 0.79. The constructed model allows to explain the phenomenon of blocking the function of M2 ion channels by the rigid conformation of the uncleaved HA0 protein and, in contrast, the activation of M2 channels after (i) specific point proteolysis of HA0 into HA1 (55 kDa) and HA2 (25 kDa) subunits and (ii) exposure to acidic pH of 4.0-5.5, leading to the disclosure of the 3D structure of the HA1/2 molecule and the opening of the M2 channel.