Alien lichens unintentionally transported to the “Arctowski” station (South Shetlands, Antarctica)

The recent climate changes combined with intensified human activity in Antarctica are promoting the synanthropization process and increasing the likelihood of alien species establishing in the native communities. Cargo items, expedition members’ equipment and food destined for the 32nd Polish Antarctic Expedition to the “Arctowski” station in the 2007/2008 season were inspected to determine their potential as vectors for alien lichen species. Within the cargo, packaging and foodstuffs scanned, a total of 45 lichen specimens (24 species) were identified. Most of them had been accidentally transported with various timbers. Cargo containers and fresh food were also found to harbour for single specimens. The majority of lichens detected are alien to the Antarctic biota and had never been observed in the region. This paper estimates the potential risk of these lichens establishing themselves in remote southern latitudes. The results emphasize the threat of accidental introduction of alien organisms into Antarctica and the need for taking every precaution to prevent the importation of non-native species to this unique environment.     

Seasonal fluctuations in microbial activity in Antarctic moss peat

The Signy Island terrestrial reference sites epitomize unpolluted maritime Antarctic tundra. The extreme transition from the harsh Antarctic winter to the milder summer facilitates studies of the effects of freeze-thaw cycles on microbial activity in moss peat. Seasonal monitoring of peat oxygen uptake showed a transient spring peak at c. 0^oC, attributed to microbial utilization of dissolved organic carbon (DOC). After a more gradual temperature-linked summer increase, autumnal freeze-thaw cycles stimulated a final pre-winter peak. The transient climaxes were associated with blooms of saccharolytic yeasts and microfungi. The bacterial population stabilized after a spring increase but then diversified as DOC became rate-limiting. Effects of pre-monitored spring freeze-thaw cycles on late-winter peat cores were simulated in a Gilson respirometer. In vitro perturbations demonstrated the regulatory effects of DOC availability, water content and temperature on peat respiration and microflora! composition. Comparative respirometry and loss in tensile strength of interred cotton strips showed a difference in decomposer activity beneath a relatively dry Polytrichum-Chorisodontium turf and a wet Cattiergon-Cephalozielta carpet. This was associated with water content and anaerobiosis. Cellulolysis accelerated during the growing season and increased with depth, despite anaerobic conditions. Estimates of annual bryophyte decomposition are presented for use in an Antarctic ecosystem model.     

Production of enzymes and antimicrobial compounds by halophilic Antarctic <Emphasis Type="Italic">Nocardioides</Emphasis> sp. grown on different carbon sources

This study demonstrated the potential of microbial isolates from Antarctic soils to produce hydrolytic enzymes by using specific substrates. The results revealed potential of the strains to produce a broad spectrum of hydrolytic enzymes. Strain A-1 isolated from soil samples in Casey Station, Wilkes Land, was identified as Nocardioides sp. on the basis of morphological, biochemical, physiological observations and also chemotaxonomy analysis. Enzymatic and antimicrobial activities of the cell-free supernatants were explored after growth of strain A-1 in mineral salts medium supplemented with different carbon sources. It was found that the carbon sources favored the production of a broad spectrum of enzymes as well as compounds with antimicrobial activity against Gram-positive and Gram-negative bacteria, especially Staphylococcus aureus and Xanthomonas oryzae. Preliminary analysis showed that the compounds with antimicrobial activity produced by the strain A-1 are mainly glycolipids and/or lipopeptides depending on the used carbon source. The results revealed a great potential of the Antarctic Nocardioides sp. strain A-1 for biotechnological, biopharmaceutical and biocontrol applications as a source of industrially important enzymes and antimicrobial/antifungal compounds.     

Distribution and characterization of recrystallization inhibitor activity in plant and lichen species from the UK and maritime Antarctic

Extracts from a range of evolutionarily diverse plant and lichen species from the UK and maritime Antarctic have been assayed for inhibition of ice recrystallization. Approximately 25% of overwintering UK species and all Antarctic species exhibited antifreeze activity when exposed to low temperature. Preliminary characterization of the active extracts has demonstrated that the molecules co-opted to antifreeze activity by different species are biochemically diverse.     

A photographic documentation of the development of Antarctic krill (Euphausia superba) from egg to early juvenile

Antarctic krill (Euphausia superba) is a key species in Antarctic marine ecosystems, as well as an important species in the Southern Ocean fishery. Here, we provide the first detailed photographic documentation of embryonic and larval development of Antarctic krill over a 5-month developmental period under controlled laboratory conditions. Developing embryos and larvae were photographed every 3 h and every 5 days, respectively. Our results indicated a developmental time of approximately 6 days for embryos and 138 days for larvae (0.5 °C). This study provided baseline biometry information for future investigations of Antarctic krill development under changing environmental conditions.     

Microbial diversity and function in Antarctic freshwater ecosystems

Freshwater lakes occur through much of Antarctica and are characterized by short food chains dominated by microbes. Comparatively few studies have been made of continental freshwater lakes until recently, with the main emphasis being on the less extreme maritime Antarctic lakes. The wide range of trophic status seen at the northern extremes of the maritime Antarctic reduces markedly further south, but a wide range of micro-organisms occur throughout the latitudinal range. Information on seasonal and spatial patterns of microbial activity for freshwater lakes demonstrate rapid changes in community composition at certain times of year despite constant low temperatures. Benthic communities of cyanobacteria and bacteria are a feature of most lakes and are involved in a wide range of geochemical cycling. There is a need for more detailed taxonomic information on most groups and considerable potential for molecular studies.     

Bacterium-bacterium inhibitory interactions among psychrotrophic bacteria isolated from Antarctic seawater (Terra Nova Bay, Ross Sea)

One hundred and forty bacteria isolated from Antarctic seawater samples were examined for their ability to inhibit the growth of indigenous isolates and their sensitivity to antibacterial activity expressed by one another. On the basis of 16S rRNA gene sequencing and analysis, bacterial isolates were assigned to five phylogenetically different taxa, Actinobacteria, alpha and gamma subclasses of Proteobacteria, Bacillaceae, and Bacteroidetes. Twenty-one isolates (15%), predominantly Actinobacteria, exhibited antagonistic properties against marine bacteria of Antarctic origin. Members of Bacteroidetes and Firmicutes did not show any inhibitory activity. Differences were observed among inhibition patterns of single isolates, suggesting that their activity was more likely strain-specific rather than dependent on phylogenetic affiliation. A novel analysis based on network theory confirmed these results, showing that the structure of this population is probably robust to perturbations, but also that it depends strongly on the most active strains. The determination of plasmid incidence in the bacterial strains investigated revealed that there was no correlation between their presence and the antagonistic activity. The data presented here provide evidence for the antagonistic interactions within bacterial strains inhabiting Antarctic seawater and suggest the potential exploitation of Antarctic bacteria as a novel source of antibiotics.     

A comparison of epiphytic diatom communities on <Emphasis Type="Italic">Plocamium cartilagineum</Emphasis> (Plocamiales,Florideophyceae) from two Antarctic areas

Our understanding of diatoms, one of the most important Antarctic primary producers, is based mostly on investigations of plankton, sea-ice, and sediment samples. Herein, we contribute to the limited research devoted to benthic Antarctic diatoms by presenting a study on epiphytic diatom communities sampled in two remote Antarctic regions: Admiralty Bay (maritime Antarctica, Antarctic Peninsula) and Terra Nova Bay (Ross Sea). Recent studies have demonstrated that the most critical factor for the local epiphytic diatom communities was the nature of the substrate. In order to eliminate this factor so we could evaluate other potential controls, we sampled epiphytic diatoms from only one substrate that is common to both regions: the macroalgae Plocamium cartilagineum (L.) Dixon. Thalli of P. cartilagineum and their associated microalgal community was collected in January 2011 (Admiralty Bay) and 2012 (Terra Nova Bay) from a water depth of 5–25 m. Dehydrated macroalgal pieces were placed on stubs and sputter-coated, which allowed observation of diatoms attached to the substrate in their original position using scanning electron microscopy. A total of 72 taxa were observed, of which 31 taxa were common to both regions. Cell abundance and diatom growth form dominance were significantly different in Admiralty Bay and Terra Nova Bay samples. Total diatom abundance was higher in Admiralty Bay samples, dominated by adnate diatoms (Cocconeis spp.), but the number of taxa found as well as the values of ecological indices were higher for samples from the Ross Sea, where motile forms were dominant (Navicula spp.). Our results suggest that Antarctic shallow-water benthic habitats may present a high degree of microniche heterogeneity and highlight the need of fine-scale analyses in microbial studies. We also suggest grazers as a factor that contributes greatly to the observed differences.     

Environmental and spatial drivers of beta diversity components of chironomid metacommunities in contrasting freshwater systems

Marine sponges are exposed to predation as well as to a wide array of potentially harmful microorganisms, and therefore they often possess chemical activity against putative predators and/or pathogens. Some crude extracts from sponges are effective in avoiding microbial colonization or potential infections, and in protecting them against predation. Here, the antibacterial activity of 18 sponge species of Antarctic shallow-waters was tested against four Antarctic and four human pathogenic bacteria. Moreover, all sponge extracts were tested for feeding repellence against the seastar Odontaster validus, one of the main predators living in those habitats. All the sponges showed antibacterial activity against at least one bacterial isolate, although not all of them were active against pathogenic bacteria. The antibacterial effect against sympatric bacteria was stronger than to pathogenic bacteria. In contrast, feeding deterrence was low, with similar activities in both hydrophilic and lipophilic extracts. Only four sponges (Myxilla lyssostyla, Phorbas areolatus, Polymastia invaginata and Iophon sp.), presented repellent chemical defenses. Therefore, we conclude that chemical defenses are widespread in Antarctic shallow-water sponges, and in fact, these sponges are better protected against bacteria than against the seastar predator. We conclude that Antarctic sponges represent a valuable source of biological active compounds with pharmacological and potential ecological relevance.     

Antarctic strict anaerobic microbiota from <Emphasis Type="Italic">Deschampsia antarctica</Emphasis> vascular plants rhizosphere reveals high ecology and biotechnology relevance

The Antarctic soil microbial community has a crucial role in the growth and stabilization of higher organisms, such as vascular plants. Analysis of the soil microbiota composition in that extreme environmental condition is crucial to understand the ecological importance and biotechnological potential. We evaluated the efficiency of isolation and abundance of strict anaerobes in the vascular plant Deschampsia antarctica rhizosphere collected in the Antarctic’s Admiralty Bay and associated biodiversity to metabolic perspective and enzymatic activity. Using anaerobic cultivation methods, we identified and isolated a range of microbial taxa whose abundance was associated with Plant Growth-Promoting Bacteria (PGPB) and presences were exclusively endemic to the Antarctic continent. Firmicutes was the most abundant phylum (73 %), with the genus Clostridium found as the most isolated taxa. Here, we describe two soil treatments (oxygen gradient and heat shock) and 27 physicochemical culture conditions were able to increase the diversity of anaerobic bacteria isolates. Heat shock treatment allowed to isolate a high percentage of new species (63.63 %), as well as isolation of species with high enzymatic activity (80.77 %), which would have potential industry application. Our findings contribute to the understanding of the role of anaerobic microbes regarding ecology, evolutionary, and biotechnological features essential to the Antarctic ecosystem.     

Cleaning up after human activity in Antarctica: legal obligations and remediation realities

National Antarctic Programmes do not have a strict legal obligation to remediate the Antarctic environment following human activity. The Protocol on Environmental Protection to the Antarctic Treaty (the “Madrid Protocol”) obliges parties to conduct environmental impact assessments to prevent adverse impacts on the polar environment and to “clean up” pollution from waste disposal sites. The obligations stemming from the Madrid Protocol are not clearly defined, and give potential scope for parties to neglect past sites of human activity on the continent. This scope is narrowed by the work of the Committee for Environmental Protection in implementing clear practical clean‐up guidelines for National Antarctic Programmes based on scientific‐based recommendations from the Antarctic Treaty Parties. Despite better modern practice, Parties are still faced with damage from past activities. Some of these sites are deemed to be “beyond help.” This article proposes that rather than abandoning waste disposal sites because of widely acknowledged difficulties, that National Antarctic Programmes prioritize research into restorative methodologies and techniques, while increasing cooperation with other parties to overcome the enormous logistical and economic costs of cleaning up pollution in Antarctica.     

Circadian Rhythm in Plasma Noradrenaline of Healthy Sleep-Deprived Subjects

Under normal sleep-wake conditions, noradrenaline (NA) secretions in supine subjects exhibit a weak circadian variation with a peak that occurs around noon; the sleep span is characterized by reduced NA secretion. Some investigators have reported that the circadian NA rhythm is completely obliterated during sleep deprivation. In our laboratory, plasma NA was assayed every hour for 24 h in nine healthy men 20-23 years of age. All men were deprived of sleep and were required to eat and walk around every hour to prevent sleep. However, subjects remained supine for 20 min before blood samples were collected to eliminate the effect of activity. Persistence of a slight decrease in the night concentration in several subjects, despite sleep deprivation, suggests that NA secretion may be influenced by a biological clock whose activity becomes visible when the influence of posture is removed.     

Physiological adaptations and activity recorded at a polar base

Physiological parameters and activity were recorded monthly on 19 men wintering at a polar base. A comparison was made between those in their first Antarctic winter (Group A, n = 13) and those in their second consecutive Antarctic winter (Group B, n = 6). Group A were more active (p less than 0.001) and spent more time outside (p less than 0.001) during the summer months than during the darker and colder winter period. Combined data showed no correlation between total activity and meteorological conditions, but a clear (p less than 0.001) negative correlation with time spent outside and wind speed. In the first part of the year group A became fitter (as shown by a lower heart rate at a VO2 1.51 min-1), increased basal oxygen uptake under standard conditions and put on body and fat mass. These changes were not demonstrated in group B living and working under identical conditions. Lean body mass of both groups rose throughout the year (A, p less than 0.001; B, p less than 0.05). These data suggested that the changes in physiological parameters in group A were in response to the life style and activity of a polar base, rather than to the Antarctic climate per se.     

Diving pattern and performance in the macaroni penguin Eudptes chrysolophus

The pattern and characteristics of diving in two female macaroni penguins Eudyptes chrysolophus was studied, during the brooding period, using continuous-recording time-depth recorders, for a total of I8 days (15 consecutive days) during which the depth, duration and timing of 4876 dives were recorded. Diving in the first 11 days was exclusively diurnal, averaging 244 dives on trips lasting 12 hours. Near the end of the brooding period trips were longer and included diving at night. About half of all trips (except those involving continuous night-time diving) was spent in diving and dive rate averaged 14–25 dives per hour (42 per hour at night). The duration of day time dives varied between trips, and averaged 1.4–1.7 min, with a subsequent surface interval of 0.5–0.9 min. Dive duration was significantly directly related to depth, the latter accounting for 53% of the variation. The average depths of daytime dives were 20–35 m (maximum depth 11 5 m). Dives at night were shorter (average duration 0.9 min) and much shallower (maximum 11 m); depth accounted for only 6% of the variation in duration. Estimates of potential prey capture rates (3–5 krill per dive; one krill every 17–20 s) are made. Daily weight changes in chicks were directly related to number of dives, but not to foraging trip duration nor time spent diving. Of the other species at the same site which live by diving to catch krill, gentoo penguins forage exclusively diurnally, making longer. deeper dives; Antarctic fur seals, which dive to similar depths as macaroni penguins, do so mainly at night.     

Chemical defenses of tunicates of the genus Aplidium from the Weddell Sea (Antarctica)

Predation and competition are important factors structuring Antarctic benthic communities and are expected to promote the production of chemical defenses. Tunicates are subject to little predation, and this is often attributed to chemical compounds, although their defensive activity has been poorly demonstrated against sympatric predators. In fact, these animals, particularly the genus Aplidium, are rich sources of bioactive metabolites. In this study, we report the natural products, distribution and ecological activity of two Aplidium ascidian species from the Weddell Sea (Antarctica). In our investigation, organic extracts obtained from external and internal tissues of specimens of A. falklandicum demonstrated to contain deterrent agents that caused repellency against the Antarctic omnivorous predator, the sea star Odontaster validus. Chemical analysis performed with Antarctic colonial ascidians Aplidium meridianum and Aplidium falklandicum allowed the purification of a group of known bioactive indole alkaloids, meridianins A-G. These isolated compounds proved to be responsible for the deterrent activity.     

Enzymes from psychrophilic organisms

Abstract: Psychrophilic organisms such as micro-organisms and other ectothermic species living in polar, deep- sea or any constantly low temperature environments, produce enzymes adapted to function at low temperature. These enzymes are characterized by a high catalytic efficiency at low and moderate temperatures but are rather thermolabile. Due to their high specific activity and their rapid inactivation at temperatures as low as 30°C, they offer, along with the producing micro-organisms, a great potential in biotechnology. The molecular basis of the adaptation of cold α-amylase, subtilisin, triose phosphate isomerase from Antarctic bacteria and of trypsin from fish living in North Atlantic and in Antarctic sea waters have been studied. The comparison of the 3D structures obtained either by protein modelling or by X-ray crystallography (North Atlantic trypsin) with those of their mesophilic counterparts indicates that the molecular changes tend to increase the flexibility of the structure by a weakening of the intramolecular interactions and by an increase of the interactions with the solvent. For each enzyme, the most appropriate strategy enabling it to accommodate the substrate at a low energy cost is selected. There is a price to pay in terms of thermosensibility because the selective pressure is essentially oriented towards the harmonization of the specific activity with ambient thermal conditions. However, as demonstrated by site-directed mutagenesis experiments carried out on the Antarctic subtilisin, the possibility remains to stabilize the structure of these enzymes without affecting their high catalytic efficiency.     

Germicide capacity of macrophages (MØ) in the Antarctic fish Notothenia coriiceps (Richardson, 1844) at 0°C

The germicide capability of the macrophage (MØ) of the Antarctic fish Notothenia coriiceps is demonstrated using fluorescence microscopy for the first time. The MØs were able to kill microorganisms by intracellular mechanism and this killing can be stimulated by oyster-derived glycogen. Although the phagocytosis index is lower than in temperate water fish species, this work demonstrates that non-specific defence mechanism plays an important role in the polar environment. There are some studies on inflammation in N. coriiceps [Silva et al. (1998) Polar Biol 20:206–212], parasite–host relation [Silva et al. (1999) Polar Biol 22:417–424] and phagocytosis [Silva et al. (2002) J Fish Biol 60:466–478]. These previous studies have shown that the MØ were able to identify biotic and abiotic factors. However, it can be of interest to study the activity of MØ in microorganism killing, and this work adds new insights of this fundamental process under Antarctic temperatures.     

Deschampsia antarctica: genetic and molecular-biological aspects of spreading in Antarctica

The genetical and molecular biological attributes of Deschampsia antarctica are considered in relation to its remarkable success in the colonization of the maritime Antarctic. However, none of the data from several published research studies provide convincing evidence that this species possess any obvious unique or specialised adaptations which might account for this success. While its occurrence appears to have spanned much of the Holocene, there is no evidence that there have ever been any other native vascular plant species in the maritime Antarctic. It is still unclear why no other taxa have succeeded in colonising this region. Further intensive studies of genetics and molecular biology of this species, and of other potential immigrants, may provide a better understanding of their enigmatic success in the maritime Antarctic.     

Agarolytic culturable bacteria associated with three antarctic subtidal macroalgae

Bacterial communities of Antarctic marine macroalgae remain largely underexplored in terms of diversity and biotechnological applications. In this study, three Antarctic subtidal macroalgae (Himantothallus grandifolius, Pantoneura plocamioides and Plocamium cartilagineum), two of them endemic of Antarctica, were investigated as a source for isolation of agar-degrading bacteria. A total of 21 epiphytic isolates showed agarolytic activity at low temperature on agar plates containing agar as the sole carbon source. 16S rRNA identification showed that the agar-degrading bacteria belonged to the genera Cellulophaga, Colwellia, Lacinutrix, Olleya, Paraglaciecola, Pseudoalteromonas and Winogradskyella. The agarase enzyme from a potential new species of the genus Olleya was selected for further purification. The enzyme was purified from the culture supernatant of Olleya sp. HG G5.3 by ammonium sulfate precipitation and ion-exchange chromatography. Molecular weight of the agarase was estimated to be 38 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The purified enzyme exhibited activity at 4 °C, retaining >?50% of its maximum activity at this temperature. This is the first study reporting the phylogeny of agar-degrading bacteria isolated from Antarctic subtidal macroalgae and the results suggest the huge potential of Antarctic algae-associated bacteria as a source of cold-active hydrolytic enzymes of biotechnological interest.