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1.
Oecologia ; 197(2): 373-385, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34596750

RESUMEN

Microhabitats with distinct biotic and abiotic properties exist within landscapes, and this microhabitat variation can have dramatic impacts on the phenology and physiology of the organisms occupying them. The Antarctic midge Belgica antarctica inhabits diverse microhabitats along the Western Antarctic Peninsula that vary in macrophyte composition, hygric qualities, nutrient input, and thermal patterns. Here, we compare seasonal physiological changes in five populations of B. antarctica living in close proximity but in different microhabitats in the vicinity of Palmer Station, Antarctica. Thermal regimes among our sample locations differed in both mean temperature and thermal stability. Between the warmest and coldest sites, seasonal mean temperatures differed by 2.6˚C and degree day accumulations above freezing differed by a factor of 1.7. Larval metabolic and growth rates varied among the sites, and adult emergence occurred at different times. Distinct microhabitats also corresponded with differences in body composition, as lipid and carbohydrate content of larvae differed across sites. Further, seasonal changes in carbohydrate and protein content were dependent on site, indicating fine-scale variation in the biochemical composition of larvae as they prepare for winter. Together, these results demonstrate that variation in microhabitat properties influences the ontogeny, phenology, physiology, and biochemical makeup of midge populations living in close proximity. These results have implications for predicting responses of Antarctic ecosystems to environmental change.


Asunto(s)
Chironomidae , Ecosistema , Animales , Regiones Antárticas , Frío , Congelación
2.
Artículo en Inglés | MEDLINE | ID: mdl-34559624

RESUMEN

A yellow bacterial strain, designated LRZ-2T, was isolated from High Arctic tundra near the settlement Ny-Ålesund in the Svalbard Archipelago, Norway. The cells were Gram-stain-positive, aerobic and non-sporulating. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain LRZ-2T represented a novel member of the suborder Micrococcineae. Its nearest phylogenetic neighbours were the members of the genus Luteimicrobium, with 16S rRNA gene sequence similarity of 95.3-96.9 %. The average nucleotide identity and digital DNA-DNA hybridization values between the genomes of strain LRZ-2T and its closely related strains were 77.4-74.3 % and 21.4-19.6 %, respectively. The DNA G+C content was 72.4 mol%. The peptidoglycan type of the isolate was A4ß with an interpeptide bridge comprising l-ornithine and d-glutamic acid. The predominant menaquinone was MK-9 (H4) and the major fatty acids were anteiso-C15 : 0, C16 : 0, anteiso-C15 : 1 A, anteiso-C17 : 0 and iso-C15 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, phosphatidylinositol dimannoside, unidentified phosphoglycolipid, four unidentified phospholipids and two unidentified polar lipids. Strain LRZ-2T showed a 16S rRNA gene signature pattern consisting of nucleotides at positions 120 (A), 131-231 (C-G), 196 (C), 342-347 (C-G), 444-490 (A-U), 580-761 (C-G), 602-636 (C-G), 670-736 (A-U), 822-878 (G-C), 823-877 (G-C), 826-874 (C-G), 827 (U), 843 (C), 950-1231 (U-A), 1047-1210 (G-C), 1109 (C), 1145 (G), 1309-1328 (G-C), 1361 (G) and 1383 (C), which clearly distinguished it from all genera previously reported in the suborder Micrococcineae. On the basis of the phylogenetic, phenotypic and chemotaxonomic data, strain LRZ-2T is considered to represent a novel species of a new genus, for which the name Pengzhenrongella sicca gen. nov., sp. nov. is proposed. The type strain of Pengzhenrongella sicca is LRZ-2T (=CCTCC AB 2012163T=DSM 100332T).


Asunto(s)
Ácidos Grasos , Suelo , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , Ácidos Grasos/química , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Tundra , Vitamina K 2
3.
Nat Commun ; 12(1): 5483, 2021 09 16.
Artículo en Inglés | MEDLINE | ID: mdl-34531387

RESUMEN

Eukaryotic phytoplankton are responsible for at least 20% of annual global carbon fixation. Their diversity and activity are shaped by interactions with prokaryotes as part of complex microbiomes. Although differences in their local species diversity have been estimated, we still have a limited understanding of environmental conditions responsible for compositional differences between local species communities on a large scale from pole to pole. Here, we show, based on pole-to-pole phytoplankton metatranscriptomes and microbial rDNA sequencing, that environmental differences between polar and non-polar upper oceans most strongly impact the large-scale spatial pattern of biodiversity and gene activity in algal microbiomes. The geographic differentiation of co-occurring microbes in algal microbiomes can be well explained by the latitudinal temperature gradient and associated break points in their beta diversity, with an average breakpoint at 14 °C ± 4.3, separating cold and warm upper oceans. As global warming impacts upper ocean temperatures, we project that break points of beta diversity move markedly pole-wards. Hence, abrupt regime shifts in algal microbiomes could be caused by anthropogenic climate change.


Asunto(s)
Variación Genética , Microalgas/genética , Microbiota/genética , Fitoplancton/genética , Transcriptoma/genética , Regiones Antárticas , Regiones Árticas , Biodiversidad , Ciclo del Carbono , Cambio Climático , Ontología de Genes , Geografía , Calentamiento Global , Microalgas/clasificación , Microalgas/crecimiento & desarrollo , Océanos y Mares , Fitoplancton/clasificación , Fitoplancton/crecimiento & desarrollo , ARN Ribosómico 16S/genética , ARN Ribosómico 18S/genética , Análisis de Secuencia de ADN/métodos , Especificidad de la Especie , Temperatura
4.
Mar Environ Res ; 171: 105478, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34562790

RESUMEN

Situated in the sub-Antarctic region, Beagle Channel represents a unique marine ecosystem due to the connection between the Pacific and the Atlantic Oceans, and its proximity to the Antarctic Peninsula. Ushuaia city, the biggest settlement on the channel, exerts an increasing anthropogenic pressure by discharges of urban and industrial effluents. In the present work, we use Patagonotothen tessellata, one of the most abundant and widespread species in the channel, as a bioindicator species in order to evidence anthropic impact from Ushuaia Bay and surrounding areas. We first analyzed and characterized real time gene expression of androgen receptor, estrogen receptor and different forms of vitellogenin (VTG), under laboratory conditions. This was achieved by induction with estradiol of P. tessellata males. Then, the selected genes were used as biomarkers for an environmental biomonitoring study. Morphometric indices and circulating sex steroids (estradiol and testosterone) were also quantified in male fish collected from different sites. The qPCR analysis showed that vtgAb form is more inducible than vtgAa or vtgC forms after estrogen induction. The field survey revealed the up-regulation of vtgAb and the androgen receptor in fish from sites with higher anthropogenic influence. Sex steroids followed seasonal variations according to their reproductive cycle, with higher levels of estradiol and testosterone in winter and summer seasons. The use of biomarkers such as gene expression of VTG demonstrates that fish from Ushuaia Bay are likely to be exposed to endocrine disrupting compounds. To our knowledge, this research is the first attempt to assess the endocrine disruption associated to anthropic impact in a widespread fish of the Beagle Channel and contributes to a better understanding of the reproductive physiology of sub Antarctic ichthyofauna.


Asunto(s)
Disruptores Endocrinos , Perciformes , Contaminantes Químicos del Agua , Animales , Regiones Antárticas , Perros , Ecosistema , Disruptores Endocrinos/toxicidad , Peces , Masculino , Vitelogeninas/genética , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidad
5.
Chemosphere ; 282: 131082, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34470154

RESUMEN

For the first time an eco-friendly method involving microextraction by packed sorbent (MEPS) coupled to gas chromatography-mass spectrometry (GC-MS) was developed for the determination of the 16 US-EPA priority pollutant polycyclic aromatic hydrocarbons (PAHs) as indicators of anthropogenic contamination in snow samples collected in polar regions. MEPS was carried out by using C8 sorbent material packed in a barrel insert and needle (BIN) and integrated in the eVol® semi-automatic device. For optimization purposes a Face Centred Design and the multicriteria method of the desirability functions were performed to investigate the effect of some parameters affecting the MEPS extraction efficiency, i.e. the number of loading cycles and the number of elution cycles. The developed MEPS-GC-MS method proved to be suitable for PAHs analysis at ultra-trace level by extracting small sample volumes achieving detection limits for 16 PAHs in the 0.3-5 ng L-1 range, repeatability and intermediate precision below 11% and 15%, respectively, and good recovery rates in the 77.6 (±0.1)-120.8 (±0.1)% range for spiked blank snow samples. Enrichment factors in the 64 (±7)-129 (±18) range were calculated. Finally, the proposed method was successfully applied to the determination of PAHs in surface snow samples collected in 2020-2021 from four locations of Northern Victoria Land, Antarctica. Local emission sources such as ships and research stations were found to influence PAHs concentrations in the surface snow.


Asunto(s)
Hidrocarburos Policíclicos Aromáticos , Contaminantes Químicos del Agua , Regiones Antárticas , Cromatografía de Gases y Espectrometría de Masas , Límite de Detección , Hidrocarburos Policíclicos Aromáticos/análisis , Nieve , Microextracción en Fase Sólida , Contaminantes Químicos del Agua/análisis
7.
Sci Total Environ ; 799: 149380, 2021 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-34352464

RESUMEN

Surface sediments were collected from Prydz Bay, Antarctica to investigate the distribution patterns, origins, annual fluxes, and trends of organochlorine pesticides (OCPs) in the marginal sea of polar areas. The concentrations of OCPs ranged from 0.80 to 7.90 ng/g dry weight, with dichlorodiphenytrichloroethanes (DDTs) as the main components. Levels of hexachlorocyclohexanes (HCHs) and DDTs in sediment from Prydz Bay were comparable to the majority of marine sediment worldwide. The distributions of OCPs were characterized by a distinct "quasi-concentric circle" pattern, which has significantly positive relationship with total organic carbon (TOC) of sediment and controlled by the local hydrodynamic conditions and sources of organic matter. Source apportionment demonstrated that HCHs and chlordanes in Prydz Bay were mainly derived from the long range atmospheric transport (LRAT) of these compounds from off regions. However, current inputs of DDT-based compounds and lindane are suggested to exist either as a result of the LART from the neighbouring countries or re-emission from melting glacier. The annual sedimentary fluxes of OCPs were 0.007 to 7.12 pg/cm2/yr, about one to three orders of magnitude lower than some data from the Arctic areas. Based on a rough calculation of r-HCH, only 0.3-1.5% of the air-seawater net deposition would be buried in sediment, implying a long active lifetime of OCPs in Antarctica. We preliminarily indicate an increase of OCP contamination in Antarctic environment afterwards when considering the possible occurrence of "fresh" sources and low proportion of sedimentary sink.


Asunto(s)
Hidrocarburos Clorados , Plaguicidas , Contaminantes Químicos del Agua , Regiones Antárticas , Bahías , China , Monitoreo del Ambiente , Sedimentos Geológicos , Hidrocarburos Clorados/análisis , Plaguicidas/análisis , Contaminantes Químicos del Agua/análisis
8.
Arch Microbiol ; 203(9): 5519-5524, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34420074

RESUMEN

A Gram-staining-positive, heterotrophic, non-spore-forming, non-motile, short rod-shaped, strain G11-30T belonging to the genus Lacisediminihabitans was isolated from a swampland mud in Antarctica. The strain was identified using a polyphasic taxonomic approach. The strain grew well on R2A agar media and formed no aerial mycelia and no diffusible pigments on any media tested. The chemotaxonomic results showed 2, 4-diaminobutyric acid (DAB) is the diagnostic diamino acid of the peptidoglycan. MK-10 was the predominant respiratory menaquinone. The major phospholipids were phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), unidentified lipid (L) and unidentified glycolipid (GL). The major fatty acids were anteiso-C15:0 (64.5%) and iso-C15:0 (18.7%). A phylogenetic tree based on 16S rRNA gene sequences showed that strain G11-30T formed a lineage in the genus Lacisediminihabitans with the closest phylogenetic Lacisediminihabitans profunda CHu50b-6-2T and Glaciihabitans tibetensis MP203T (97.9%, 97.5% 16S rRNA gene sequence similarity). A phylogenomic tree based on genome sequence of G11-30T, conferred by Type Strain Genome Server (TYGS), separated it from L. profunda CHu50b-6-2T. Strain G11-30T has a complete genome size of 2.59 Mb, with a G + C content of 66.2 mol%. The digital DNA-DNA hybridization (dDDH) score between strain G11-30T and reference strains L. profunda CHu50b-6-2T and G. tibetensis MP203T were 20.1 and 20.3%, respectively. Concurrently, Average Nucleotide Identity (ANI) score between strain G11-30 T against. profunda CHu50b-6-2T and G. tibetensis MP203T were 76.2 and72.5%, respectively. Based on phenotypic, phylogenetic and genotypic data, a novel species, Lacisediminihabitans changchengi sp. nov. is proposed. The type strain is G11-30T (= CCTCC AA 2019080T = KCTC49359T).


Asunto(s)
Ácidos Grasos , Fosfolípidos , Actinobacteria , Regiones Antárticas , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Vitamina K 2
9.
Mar Environ Res ; 170: 105430, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34340030

RESUMEN

Benthic organisms of the Southern Ocean are particularly vulnerable to ocean acidification (OA), as they inhabit cold waters where calcite-aragonite saturation states are naturally low. OA most strongly affects animals with calcium carbonate skeletons or shells, such as corals and mollusks. We exposed the abundant cold-water coral Malacobelemnon daytoni from an Antarctic fjord to low pH seawater (LpH) (7.68 ± 0.17) to test its physiological responses to OA, at the level of gene expression (RT-PCR) and enzyme activity. Corals were exposed in short- (3 days) and long-term (54 days) experiments to two pCO2 conditions (ambient and elevated pCO2 equaling RCP 8.5, IPCC 2019, approximately 372.53 and 956.78 µatm, respectively). Of the eleven genes studied through RT-PCR, six were significantly upregulated compared with control in the short-term in the LpH condition, including the antioxidant enzyme superoxide dismutase (SOD), Heat Shock Protein 70 (HSP70), Toll-like receptor (TLR), galaxin and ferritin. After long-term exposure to low pH conditions, RT-PCR analysis showed seven genes were upregulated. These include the mannose-binding C-Lectin and HSP90. Also, the expression of TLR and galaxin, among others, continued to be upregulated after long-term exposure to LpH. Expression of carbonic anhydrase (CA), a key enzyme involved in calcification, was also significantly upregulated after long-term exposure. Our results indicated that, after two months, M. daytoni is not acclimatized to this experimental LpH condition. Gene expression profiles revealed molecular impacts that were not evident at the enzyme activity level. Consequently, understanding the molecular mechanisms behind the physiological processes in the response of a coral to LpH is critical to understanding the ability of polar species to cope with future environmental changes. Approaches integrating molecular tools into Antarctic ecological and/or conservation research make an essential contribution given the current ongoing OA processes.


Asunto(s)
Antozoos , Animales , Regiones Antárticas , Antozoos/genética , Dióxido de Carbono/toxicidad , Arrecifes de Coral , Concentración de Iones de Hidrógeno , Océanos y Mares , Agua de Mar
10.
J Environ Radioact ; 237: 106713, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34388521

RESUMEN

The present article introduces data on natural radioactivity (40K, 230,232Th, 234,238U) in the Antarctic marine and terrestrial environment. Various biota samples were analysed due to internal exposure to 40K, 230,232Th, 234,238U. Activity concentration of 40K was the highest in both marine and terrestrial samples. Mean values of 40K activity concentration are 1340 Bq/kg and 370 Bq/kg for the marine and terrestrial samples respectively. 234U/238U ratios analysis revealed that sea waters and sea spray are the main source of the uranium in the terrestrial samples. Average 230,232Th, 234,238U activity concentrations in the Antarctic biota do not exceed 6 Bq/kg. Weighted internal dose rates are relatively low; they range from approximately 0.1 to 0.6 µGy/h. Statistically significant differences in radionuclide accumulation were discovered between the mosses and lichens. It may point to various mechanisms of the nutrient absorption from the environment by these organisms.


Asunto(s)
Exposición a la Radiación , Monitoreo de Radiación , Contaminantes Radiactivos del Suelo , Uranio , Regiones Antárticas , Biota , Radioisótopos de Potasio/análisis , Radioisótopos/análisis , Contaminantes Radiactivos del Suelo/análisis , Torio/análisis , Uranio/análisis
11.
Environ Pollut ; 287: 117627, 2021 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-34426394

RESUMEN

Antarctic melt streams are important ecosystems that increasingly face contaminant pressures from anthropogenic sources. Metal contaminants are often reported in the limno-terrestrial environment but their speciation is not well characterised, making environmental risk assessments difficult. This paper characterises labile metal concentrations in five melt streams and three shallow lakes around the Casey and Wilkes research stations in East Antarctica using chemical extracts and field deployments of diffusive gradients in thin-film (DGT) samplers. An acute toxicity test with field-collected Ceratadon purpeus and taxonomic identification of diatoms in melt streams were used to infer environmental risk. Copper and zinc were the most labile metals in the melt streams. DGT-labile copper concentrations were up to 3 µg Cu L-1 in melt-stream waters but not labile below the sediment-water interface. DGT-labile zinc concentrations were consistent above and below the sediment-water interface at concentrations up to 14 µg Zn L-1 in four streams, but one stream showed evidence of zinc mineralisation in the sediment with a flux to overlying and pore waters attributed to the reductive dissolution of iron and manganese oxides. Other metals, such as chromium, nickel, and lead were acid-extractable from the sediments, but not labile in pore waters or overlying waters. All streams had unique compositions of freshwater diatoms, but one had particularly reduced diversity and richness, which correlated to metal contamination and sediment physico-chemical properties such as a finer particle size. In laboratory bioassays with field-collected samples of the Antarctic moss C. purpeus, there was no change in photosynthetic efficiency following 28-d exposure to 700, 900, 1060, or 530 µg L-1 of cadmium, copper, nickel, and zinc, respectively. This study shows that microorganisms such as diatoms may be at greater risk from contaminants than mosses, and highlights the importance of geochemical factors controlling metal lability.


Asunto(s)
Monitoreo del Ambiente , Contaminantes Químicos del Agua , Regiones Antárticas , Ecosistema , Sedimentos Geológicos , Lagos , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidad
12.
Molecules ; 26(15)2021 Jul 28.
Artículo en Inglés | MEDLINE | ID: mdl-34361720

RESUMEN

The metabolism of nitric oxide plays an increasingly interesting role in the physiological response of the human body to extreme environmental conditions, such as underwater, in an extremely cold climate, and at low oxygen concentrations. Field studies need the development of analytical methods to measure nitrite and nitrate in plasma and red blood cells with high requirements of accuracy, precision, and sensitivity. An optimized spectrophotometric Griess method for nitrite-nitrate affords sensitivity in the low millimolar range and precision within ±2 µM for both nitrite and nitrate, requiring 100 µL of scarcely available plasma sample or less than 50 µL of red blood cells. A scheduled time-efficient procedure affords measurement of as many as 80 blood samples, with combined nitrite and nitrate measurement in plasma and red blood cells. Performance and usefulness were tested in pilot studies that use blood fractions deriving from subjects who dwelt in an Antarctica scientific station and on breath-holding and scuba divers who performed training at sea and in a land-based deep pool facility. The method demonstrated adequate to measure low basal concentrations of nitrite and high production of nitrate as a consequence of water column pressure-triggered vasodilatation in deep-water divers.


Asunto(s)
Ensayos Analíticos de Alto Rendimiento , Hipoxia/sangre , Nitratos/sangre , Óxido Nítrico/sangre , Nitritos/sangre , Estrés Fisiológico , Regiones Antárticas , Frío , Buceo/fisiología , Eritrocitos/química , Humanos , Oxigenación Hiperbárica/métodos , Hipoxia/fisiopatología , Sensibilidad y Especificidad , Vasodilatación
13.
Chemistry ; 2021 Aug 24.
Artículo en Inglés | MEDLINE | ID: mdl-34428339

RESUMEN

Herein we report on the development and application of chemoenzymatic Dynamic Kinetic Asymmetric Transformation (DYKAT) of α-substituted ß-hydroxyketones (ß-HKs), using Candida antartica lipase B (CALB) as transesterification catalyst and a ruthenium complex as epimerization catalyst. An operationally simple protocol allows for an efficient preparation of highly enantiomerically enriched α-substituted ß-oxoacetates. The products were obtained in yields up to 95 % with good diastereomeric ratios.

14.
Nat Commun ; 12(1): 4948, 2021 08 16.
Artículo en Inglés | MEDLINE | ID: mdl-34400630

RESUMEN

Since the middle of the past century, the Western Antarctic Peninsula has warmed rapidly with a significant loss of sea ice but the impacts on plankton biodiversity and carbon cycling remain an open question. Here, using a 5-year dataset of eukaryotic plankton DNA metabarcoding, we assess changes in biodiversity and net community production in this region. Our results show that sea-ice extent is a dominant factor influencing eukaryotic plankton community composition, biodiversity, and net community production. Species richness and evenness decline with an increase in sea surface temperature (SST). In regions with low SST and shallow mixed layers, the community was dominated by a diverse assemblage of diatoms and dinoflagellates. Conversely, less diverse plankton assemblages were observed in waters with higher SST and/or deep mixed layers when sea ice extent was lower. A genetic programming machine-learning model explained up to 80% of the net community production variability at the Western Antarctic Peninsula. Among the biological explanatory variables, the sea-ice environment associated plankton assemblage is the best predictor of net community production. We conclude that eukaryotic plankton diversity and carbon cycling at the Western Antarctic Peninsula are strongly linked to sea-ice conditions.


Asunto(s)
Biodiversidad , Ciclo del Carbono , Cubierta de Hielo , Plancton/fisiología , Regiones Antárticas , Carbono/metabolismo , Diatomeas , Ecosistema , Eucariontes , Microbiota , Plancton/genética , Temperatura
15.
Sci Total Environ ; 790: 147879, 2021 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-34380283

RESUMEN

Marine phytoplankton can utilize different strategies to cope with ocean warming and freshening from glacial melting in polar regions, which are disproportionally impacted by global warming. In the present study, we investigated the individual and combined effects of a 4 °C increase in seawater temperature (T+) and a 4 psu decrease in salinity (S-) from ambient values on biomass, nutrient use, fatty acid composition and lipid damage biochemistry of natural phytoplankton assemblages from Potter Cove (25 de Mayo/King George Island, Antarctica). Experiments were conducted by exposing the assemblages to four treatments during a 7-day incubation period using microcosm located along shore from January 23 to 31, 2016. The N:P ratio decreased in all treatments from day 4 onwards, but especially under high temperature (T+). Lipid damage was mainly detected under S0T+ and S-T+ conditions, and it decreased when the production of the antioxidant α-tocopherol increased. This antioxidant protection resulted in a build-up of phytoplankton biomass, especially at T+. Under the combined effect of both stressors (S-T+), the concentration of ω3 fatty acids increased, potentially leading to higher-quality FA composition. These results, which were related to the dominance of sub-Antarctic species in phytoplankton assemblages, contribute to the understanding of the potential consequences of ocean warming and increase seawater freshening on the trophic webs of the Southern Ocean.


Asunto(s)
Metabolismo de los Lípidos , Fitoplancton , Regiones Antárticas , Océanos y Mares , Agua de Mar
16.
J Exp Biol ; 224(14)2021 07 15.
Artículo en Inglés | MEDLINE | ID: mdl-34297110

RESUMEN

Rapid hardening is a process that quickly improves an animal's performance following exposure to potentially damaging stress. In this study of the Antarctic midge, Belgica antarctica (Diptera, Chironomidae), we examined how rapid hardening in response to dehydration (RDH) or cold (RCH) improves male pre- and post-copulatory function when the insects are subsequently subjected to a damaging cold exposure. Neither RDH nor RCH improved survival in response to lethal cold stress, but male activity and mating success following sublethal cold exposure were enhanced. Egg viability decreased following direct exposure of the mating males to sublethal cold but improved following RCH and RDH. Sublethal cold exposure reduced the expression of four accessory gland proteins, while expression remained high in males exposed to RCH. Though rapid hardening may be cryptic in males, this study shows that it can be revealed by pre- and post-copulatory interactions with females.


Asunto(s)
Chironomidae , Aclimatación , Animales , Regiones Antárticas , Frío , Cortejo , Femenino , Fertilidad , Larva , Masculino
17.
Oecologia ; 197(2): 339-352, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34309704

RESUMEN

Sexual segregation, the differential space, habitat or resource use by males and females, can have profound implications for conservation, as one sex may be more vulnerable to environmental and anthropogenic stressors. The drivers of sexual segregation, such as sex differences in body size, breeding constraints, and social behaviour, have been well studied in adults but are poorly understood in immature animals. To determine whether sexual segregation occurs in juvenile Antarctic fur seals, Arctocephalus gazella, and investigate the underlying drivers, we deployed Global Location Sensors on 26 males and 19 females of 1-3 years of age at Bird Island, South Georgia. Sexual segregation occurred in foraging distribution, primarily in latitude, with females foraging closer to South Georgia and the Polar Front, and males foraging further south near the Antarctic Peninsula. This segregation was particularly evident in Feb-Apr and May-Nov, and males spent more time hauled out than females in May-Nov. Although juveniles have no immediate reproductive commitments, reproductive selection pressures are still likely to operate and drive sex differences in body size, risk-taking, and social roles. These factors, coupled with prey distribution, likely contributed to sexual segregation in juvenile Antarctic fur seals. Consequently, male and female juveniles may compete with different fisheries and respond differently to environmental change, highlighting the importance of considering sex and age groups in species conservation efforts.


Asunto(s)
Lobos Marinos , Animales , Regiones Antárticas , Ecosistema , Femenino , Islas , Masculino , Caracteres Sexuales
18.
Food Chem ; 365: 130500, 2021 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-34246152

RESUMEN

There is a growing interest in exploiting Antarctic fisheries for human consumption. However, information on how the nutritional qualities of these resources will respond to the predicted seawater warming in the region for the next century is poor. The present research investigates changes in various nutritional indices of dietary importance (e.g. the ratio polyunsaturated to saturated fatty acids, the atherogenicity index, the thrombogenicity index, the hypo-cholesterolemic to hyper-cholesterolemic index, the health-promoting index, the flesh lipid quality and the ratio omega-3 to omega-6 index) by determining the fatty acid composition in muscle of Trematomus bernacchii (an Antarctic fish species) in its natural habitat (-1.87 °C) and warmer temperatures (0.0, 1.0, 2.0 °C). Comparison of the estimated nutritional indices at -1.87 °C with those at warmer temperatures revealed that seawater warming caused changes in the nutritional indices in the range of -12%<Δ < 30%. The observed changes were not statistically significant and ascribed to biological variability. Therefore, the nutritional values of T. bernacchii muscle were preserved after increasing the temperature of its natural habitat by + 4 °C. The present research is the first report describing the nutritional quality indices for an Antarctic fish species and the consequences of seawater warming on the nutritional value of T. bernacchii.


Asunto(s)
Ácidos Grasos , Perciformes , Animales , Regiones Antárticas , Humanos , Evaluación Nutricional , Valor Nutritivo , Agua de Mar
19.
Environ Sci Process Impacts ; 23(9): 1316-1327, 2021 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-34318848

RESUMEN

To investigate mass size distributions of water-soluble ions in aerosols in the marine boundary layer (MBL) over the Southern Ocean, size-segregated (0.056-18 µm in aerodynamic diameter) aerosols were collected on the 28th Chinese National Antarctic Research Expedition (CHINARE) cruise from November 2011 to March 2012. Major water-soluble inorganic and organic species in aerosols were analyzed by ion chromatography (IC). Results showed that high loadings of aerosol mass were observed over the western sector of the Southern Ocean, attributed to the high mass loadings of Na+ and Cl- in the particles >1.0 µm in diameter and high mass loadings of non-sea-salt (nss) SO42- and methanesulfonate (MSA) in the particles <1.0 µm in diameter. Nss-SO42- and MSA accounted for ∼40% of the total mass in aerosols with particle size <0.56 µm over the eastern sector of the Southern Ocean, while it was elevated to more than 60% over the western sector of the Southern Ocean that could be linked with high marine productivity reflected by high chlorophyll-a occurrence in surface waters in that region. MSA/nss-SO42- ratios showed an increasing trend as latitude increased in the southern hemisphere with a dramatic increase south of 60 °S and the variation of MSA may shape the spatial distribution of the ratios. High MSA concentration and MSA/nss-SO42- ratios were observed in west Antarctica, especially in the supermicron particles. A bimodal mass size distribution of total Ca2+ with a small peak in the 0.18-0.32 µm size range was observed, suggesting different sea spray aerosol (SSA) production mechanisms. Nss-SO42-, MSA was mainly enriched in the particle size range of 0.18 µm to 0.56 µm. The concentrations of formate and oxalate were low and detected only in certain size particles, mainly in the range <0.56-1.8 µm. Further studies should be conducted over the remote Southern Ocean to reveal marine ecosystem-aerosol-climate interactions.


Asunto(s)
Contaminantes Atmosféricos , Aerosoles/análisis , Contaminantes Atmosféricos/análisis , Regiones Antárticas , Ecosistema , Monitoreo del Ambiente , Iones/análisis , Océanos y Mares , Agua
20.
New Phytol ; 232(2): 788-801, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34270800

RESUMEN

Composition and functioning of arctic soil fungal communities may alter rapidly due to the ongoing trends of warmer temperatures, shifts in nutrient availability, and shrub encroachment. In addition, the communities may also be intrinsically shaped by heavy grazing, which may locally induce an ecosystem change that couples with increased soil temperature and nutrients and where shrub encroachment is less likely to occur than in lightly grazed conditions. We tested how 4 yr of experimental warming and fertilization affected organic soil fungal communities in sites with decadal history of either heavy or light reindeer grazing using high-throughput sequencing of the internal transcribed spacer 2 ribosomal DNA region. Grazing history largely overrode the impacts of short-term warming and fertilization in determining the composition of fungal communities. The less diverse fungal communities under light grazing showed more pronounced responses to experimental treatments when compared with the communities under heavy grazing. Yet, ordination approaches revealed distinct treatment responses under both grazing intensities. If grazing shifts the fungal communities in Arctic ecosystems to a different and more diverse state, this shift may dictate ecosystem responses to further abiotic changes. This indicates that the intensity of grazing cannot be left out when predicting future changes in fungi-driven processes in the tundra.


Asunto(s)
Micobioma , Reno , Animales , Regiones Árticas , Ecosistema , Fertilización , Suelo , Microbiología del Suelo , Tundra
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