Adult females of a predatory fish, the blackfin icefish, Chaenocephalus aceratus examined at the South Shetland Islands and South Orkney Islands were by several orders of magnitude more infected with Acanthocephala than the males and immature females. Such phenomenon has not been observed in the neritic zone at South Georgia. Cystacanths of Corynosoma hamanni and Corynosoma pseudohamanni were the dominant parasites in Admiralty Bay, whereas Corynosoma bullosum was the dominant in the open sea off the South Shetland Islands and South Georgia, and in the sub-coastal waters off the South Orkney Islands. However, the dominance of C. bullosum was observed in several hosts in Admiralty Bay and the co-dominance of C. bullosum, C. hamanni, and C. pseudohamanni in one mature female in the neritic zone at the South Shetland Islands. Probably, these fish previously lived in the open sea. Cystacanths of Corynosoma arctocephali and Corynosoma shackletoni occurred in the fish in Admiralty Bay and off South Georgia. The former parasite was present also off the South Orkney Islands. One cystacanth of Andracantha baylisi was found off South Georgia. Two echinorhynchids, Aspersentis megarhynchus and Metacanthocephalus dalmori, occurred in the alimentary tracts of the fish caught in Admiralty Bay and one specimen of Echinorhynchus petrotschenkoi off the South Shetland Islands. The highest infection, amounting to 816 acanthocephalans, was found in a mature female in Admiralty Bay. One cystacanth of C. hamanni occurred in a single immature fish caught in the sub-coastal area off Deception Island.

This study investigated leaf mesophyll cells of Caryophyllaceae plants growing in polar regions – Cerastium alpinum and Silene involucrata from the Hornsund region of Spitsbergen island (Svalbard Archipelago, Arctic), and Colobanthus quitensis from the Admiralty Bay region on King George Island (South Shetland Islands, West Antarctic). Ultra− structural changes were analyzed in mesophyll protoplasts of plants growing in natural Arctic and Antarctic habitats and plants grown in a greenhouse, including plants exposed to short−term cold stress under se mi−controlled conditions. Cell organelles of plants growing in natural polar habitats and greenhouse−grown plants were characterized by significant morphological plasticity. Chloroplasts of plants studied in this work formed variously shaped protrusions and invaginations that visibly increased the contact area between adjacent cell compartments and reduced the distance between organelles. S. involucrata plants grown under greenhouse conditions, tested by us in this wor k, were characterized by highly dynamic cell nuclei with single or multiple invaginations of the nuclear membrane and the presence of channels and cisternae filled with cytoplasm and organelles. Crystalline inclusion proteins were observed in the cell nuclei of C. quitensis between nuclear membranes and in the direct proximity of heterochromatin. Our study revealed significant conformational dynamics of organelles, manifested by variations in the optical density of matrices, membranes and envelopes, in particular in C. quitensis , which could suggest that the analyzed Caryophyllaceae taxa are well adapted to severe climate and changing conditions in polar regions.

The aim of this work was to study the polyphenolic composition of Deschampsia antarctica È. Desv. plants grown at natural conditions on different locations on the Galindez Island, Argentine Islands, the maritime Antarctic. The plants were collected during the summer season of the 26th Ukrainian Antarctic Expedition (2020–2022). The extracts of 21 plants were obtained and the composition of the extracts was analyzed by means of high-performance liquid chromatography and matrix-assisted laser desorption/ionization mass spectrometry. The antioxidant properties of the extracts were characterized using the DPPH (2,2-diphenyl-1-picrylhydrazyl) test. The extracts were found to contain large amount of polyphenolic compounds, with flavonoids and phenolic acids, as well as their derivatives, being the most common classes of the phenols. Using the HPLC data the content of various phenols in the plants was systematic studied. It has been found that in all plants the most abundant phenols are flavonoids/flavonoid derivatives (on average about 75% of total mass of phenols). Among the flavonoids, luteolin derivatives predominate (86–94% of the total mass of flavonoids), and, among luteolin derivatives, the main compounds are orientin, orientin 2"- O-β-arabinopyranoside and isoswertiajaponin 2"- O-β-arabinopyranoside (67–83% of the total mass of luteolin derivatives). It has been also found that all the extracts possess the high activity in inhibition of DPPH radicals and that the antioxidant activity of the extracts correlates with total content of phenols in the samples. Thus, Deschampsia antarctica É. Desv. plants are a valuable source of natural phenolic antioxidants, and the most common antioxidants in the extracts are orientin, orientin 2"- O-β-arabinopyranoside and isoswertiajaponin 2"- O-β-arabinopyranoside.