The filter feeder clam
Laternula elliptica
is a key species in the Antarctic ecosystem. As a stenothermal benthic species, it has a poor capacity for adaptation to small temperature variations. ...Despite their ecological importance and sensitivity to climate change, studies on their microbiomes are lacking. The goal of this study was to characterize the bacterial communities of
L. elliptica
and the tissues variability of this microbiome to provide an initial insight of host-microbiota interactions. We investigated the diversity and taxonomic composition of bacterial communities of
L. elliptica
from five regions of the body using high-throughput 16S rRNA gene sequencing. The results showed that the microbiome of
L. elliptica
tended to differ from that of the surrounding seawater samples. However, there were no significant differences in the microbial composition between the body sites, and only two OTUs were present in all samples, being considered core microbiome (genus
Moritella
and
Polaribacter
). No significant differences were detected in diversity indexes among tissues (mean 626.85 for observed OTUs, 628.89 Chao1, 5.42 Shannon, and 0.87 Simpson). Rarefaction analysis revealed that most tissues reached a plateau of OTU number according to sample increase, with the exception of Siphon samples.
Psychromonas
and
Psychrilyobacter
were particularly abundant in
L. elliptica
whereas Fluviicola dominated seawater and siphons. Typical polar bacteria were
Polaribacter
,
Shewanella
,
Colwellia
, and
Moritella
. We detected the prevalence of pathogenic bacterial sequences, particularly in the family
Arcobacteraceae
,
Pseudomonadaceae
, and
Mycoplasmataceae
. The prokaryotic diversity was similar among tissues, as well as their taxonomic composition, suggesting a homogeneity of the microbiome along
L. elliptica
body. The Antarctic clam population can be used to monitor the impact of human activity in areas near Antarctic stations that discharge wastewater.
The establishment of
(Mtb) long-term infection
depends on several factors, one of which is the availability of key nutrients such as iron (Fe). The relation between Fe deprivation inside and outside ...the granuloma, and the capacity of Mtb to accumulate lipids and persist in the absence of growth is not well understood. In this context, current knowledge of how Mtb modifies its lipid composition in response to growth arrest, depending on iron availability, is scarce. To shed light on these matters, in this work we compare genome-wide transcriptomic and lipidomic profiles of Mtb at exponential and stationary growth phases using cultures with glycerol as a carbon source, in the presence or absence of iron. As a result, we found that transcriptomic responses to growth arrest, considered as the transition from exponential to stationary phase, are iron dependent for as many as 714 genes (iron-growth interaction contrast, FDR <0.05), and that, in a majority of these genes, iron deprivation enhances the magnitude of the transcriptional responses to growth arrest in either direction. On the one hand, genes whose upregulation upon growth arrest is enhanced by iron deprivation were enriched in functional terms related to homeostasis of ion metals, and responses to several stressful cues considered cardinal features of the intracellular environment. On the other hand, genes showing negative responses to growth arrest that are stronger in iron-poor medium were enriched in energy production processes (TCA cycle, NADH dehydrogenation and cellular respiration), and key controllers of ribosomal activity shut-down, such as the T/A system
E6
F6. Despite of these findings, a main component of the cell envelope, lipid phthiocerol dimycocerosate (PDIM), was not detected in the stationary phase regardless of iron availability, suggesting that lipid changes during Mtb adaptation to non-dividing phenotypes appear to be iron-independent. Taken together, our results indicate that environmental iron levels act as a key modulator of the intensity of the transcriptional adaptations that take place in the bacterium upon its transition between dividing and dormant-like phenotypes
.
Relatively little is known about the effects of endogenous and exogenous steroid hormones on ecologically relevant behavioral and cognitive phenotypes in women, such as emotion recognition, despite ...the widespread use of steroid hormone-altering hormonal contraceptives (HCs). Though some previous studies have examined the effect of HC use, estradiol, progesterone, and testosterone on emotion recognition in women, they have been limited by cross-sectional designs, small sample sizes (total n < 100), and compromised statistical power to detect significant effects. Using data from two test sessions in a large sample of naturally cycling women (NC; n = 192) and women on HCs (n = 203), we found no group differences in emotion recognition; further, the lack of group differences in emotion recognition was not modulated by item difficulty or emotional valence. Among NC women who provided saliva samples across two sessions that were assayed for estradiol and progesterone concentrations, we found no compelling evidence across models that between-subject differences and within-subject fluctuations in these ovarian hormones predicted emotion recognition accuracy, with the exception that between-subjects estradiol negatively predicted emotion recognition for emotions of neutral valence (p = .042). Among HC women who provided saliva samples across two sessions that were assayed for testosterone, we found no compelling evidence that between-subjects differences and within-subject fluctuations in testosterone predicted emotion recognition accuracy. Overall, our analyses provide little support for the idea that circulating endogenous or exogenous ovarian hormones influence emotion recognition in women.
•Investigated how endogenous exogenous hormones affect emotion recognition (ER).•2 sessions from 193 naturally-cycling women and 203 on oral contraception•Oral contraceptive use did not modulate ER.•Individual differences in estradiol, progesterone, and testosterone did not predict ER.•Within-subject sex hormone changes across sessions did not predict ER.
Heat stress proteins are implicated in stabilizing and refolding denatured proteins in vertebrates and invertebrates. Members of the Hsp70 gene family comprise the cognate heat shock protein (Hsc70) ...and inducible heat shock protein (Hsp70). However, the cDNA sequence and the expression of Hsp70 in the Antarctic sea urchin are unknown.
We amplified and cloned a transcript sequence of 1991 bp from the Antarctic sea urchin Sterechinus neumayeri, experimentally exposed to heat stress (5 and 10 °C for 1, 24 and 48 h). RACE-PCR and qPCR were employed to determine Hsp70 gene expression, while western blot and ELISA methods were used to determine protein expression.
The sequence obtained from S. neumayeri showed high identity with Hsp70 members. Several Hsp70 family features were identified in the deduced amino acid sequence and they indicate that the isolated Hsp70 is related to the cognate heat shock protein type. The corresponding 70 kDa protein, called Sn-Hsp70, was immune detected in the coelomocytes and the digestive tract of S. neumayeri using a monospecific polyclonal antibody. We showed that S. neumayeri do not respond to acute heat stress by up-regulation of Sn-Hsp70 at transcript and protein level. Furthermore, the Sn-Hsp70 protein expression was not induced in the digestive tract.
Our results provide the first molecular evidence that Sn-Hsp70 is expressed constitutively and is non-induced by heat stress in S. neumayeri.
Although the cellular and molecular responses to exposure to relatively high temperatures (acute thermal stress or heat shock) have been studied previously, only sparse empirical evidence of how it ...affects cold-water species is available. As climate change becomes more pronounced in areas such as the Western Antarctic Peninsula, both long-term and occasional acute temperature rises will impact species found there, and it has become crucial to understand the capacity of these species to respond to such thermal stress. Here, we use the Antarctic sponge
sp. to investigate how sessile organisms (particularly Porifera) can adjust to acute short-term heat stress, by exposing this species to 3 and 5 °C for 4 h, corresponding to predicted temperatures under high-end 2080 IPCC-SRES scenarios. Assembling a de novo reference transcriptome (90,188 contigs, >93.7% metazoan BUSCO genes) we have begun to discern the molecular response employed by Isodictya to adjust to heat exposure. Our initial analyses suggest that TGF-β, ubiquitin and hedgehog cascades are involved, alongside other genes. However, the degree and type of response changed little from 3 to 5 °C in the time frame examined, suggesting that even moderate rises in temperature could cause stress at the limits of this organism's capacity. Given the importance of sponges to Antarctic ecosystems, our findings are vital for discerning the consequences of short-term increases in Antarctic ocean temperature on these and other species.
Chromitite bodies can be found within ophiolitic mantle sections in three locations in Colombia: Medellín, Planeta Rica, and La Guajira. These chromitites are typically massive pods that are often ...surrounded by lateritic soil in Medellín and Planeta Rica, or small discoidal bodies in La Guajira. Inclusions in chromite are preserved to varying degrees in the three localities: olivine and pargasite are partially preserved in Medellín and Planeta Rica, whereas inclusions in La Guajira chromitites are completely altered to chlorite. Compositionally, chromite from the chromitites is high-Al in Medellín (Cr#Cr/(Cr+Al) atomic ratio = 0.41-0.51) and Planeta Rica (Cr# = 0.49-0.57), and high-Cr in La Guajira (Cr# = 0.75-0.76), whereas TiO
2
contents are low in the three localities (0.12-0.43 wt%). Regarding trace elements composition, the chromitites are similar to others formed in supra-subduction zone settings; the chromite from the high-Al chromitites is similar to that in MORB/BABB, whereas chromite from the high-Cr chromitites has a strong boninitic affinity. Chromitites from Planeta Rica are richer in Ti, possibly due to the presence of nearby gabbroic bodies and impregnated peridotites. The alteration in chromite rims and silicate matrix is related to metamorphic processes. Bulk-rock platinum-group element (PGE) contents range from 30 to 487 ppb, and chondrite-normalized PGE patterns show the typical enrichment in IPGE relative to PPGE observed in most ophiolitic chromitites. The estimated melts in equilibrium with the different chromitites correspond to MORB-like melts for the Medellín and Planeta Rica chromitites and to boninites for La Guajira chromitites. However, the estimated TiO
2
content in the melt is too low for a typical MORB, indicating back-arc basin basalts and a back-arc setting for the formation of the Medellín and Planeta Rica chromitites during the Late Triassic and the Late Jurassic, respectively. La Guajira chromitites are interpreted to have formed in a fore-arc basin related to subduction-initiation during Cretaceous times.
Although the frequency and magnitude of sedimentation often varies across coastal landscapes creating patches with different mean sediment loads, duration of sedimentation and rates of sediment ...resuspension, few studies have documented the emergent effects of spatio-temporal variability in sedimentation. Here, we conducted two laboratory experiments to evaluate such effects on the establishment of Macrocystis pyrifera and Undaria pinnatifida spores. In the first experiment, spore establishment was significantly affected by sediment load (the effective dose required for a 40 % reduction in establishment ranged between 16 and 60 mg sediment l⁻¹) and sediment regime (relative sedimentation occurring before spore settlement, ~3 times more sediment was required for 20 % reduction in spore establishment when sedimentation occurred after spore settlement). The second experiment demonstrated that the effects of sediment depended on sediment load (spore establishment was 2–4 times greater when sediment load was 200 mg l⁻¹ relative to 400 mg l⁻¹), variability in sedimentation (spore establishment was 1.36 times greater with variable than fixed sediment loads), repeated pulses of sedimentation (pulsed sedimentation decreased spore establishment by 59–91 % relative to a single sedimentation event) and timing of sedimentation relative to spore settlement (sedimentation before spore settlement decreased establishment by 51–95 % relative to sedimentation after spore settlement). These results have important implications for ecologists and resource managers attempting to predict the consequences of sedimentation, suggesting that it is not only important to consider sediment load, but also fine-scale temporal variability in sedimentation relative to key life-history events of the impacted organisms.
El artículo tiene como objetivo evaluar el impacto de los programas de bienestar universitario en el rendimiento académico de estudiantes de una universidad pública en Colombia. Metodológicamente, se ...desarrolló como un estudio explicativo que tomó como muestra a los estudiantes desde el periodo 2014-I a 2018-II. Se analizaron 1.530 estudiantes, donde el 53% son mujeres y el 47% hombres, a los cuales se les aplicó un modelo econométrico múltiple de corte transversal sobre las variables de estudio. En los resultados, se encontró que existe una relación latente sobre el rendimiento académico, permanencia y graduación, en los beneficios de ayudantía, almuerzo y refrigerio, pero que se está explicando poco. Por lo tanto, se concluye sobre la necesidad de reajustar el proceso de selección de estudiantes beneficiarios y focalizar la población con mayor vulnerabilidad socioeconómica, así como hacer evaluaciones cualitativas de las variables.
The occurrence and impact of contaminants of emerging concerns (CECs) have been investigated in Antarctica much less than in other parts of the world. Although legacy anthropogenic pollutants can ...reach Antarctica via long-range transport, CECs mainly originate from local sources. Here, we investigated the ability of a freshwater crustacean, the Antarctic fairy shrimp Branchinecta gaini, to cope with nanoscale titanium dioxide (n-TiO2), a widely used pigment in consumer products (e.g. paintings), including those for personal care (e.g. sunscreens). An in vivo acute short-term exposure study (9 h, n-TiO2 concentration range 50–200 μg ml-1) was performed and the expression levels of several genes involved in stress response were evaluated. No effect on the expression of heat-shock protein chaperone genes was found, with the exception of Hsp70a, which was significantly upregulated at 200 μg ml-1 n-TiO2. Similarly, cytochrome P450 was upregulated at 100 and 200 μg ml-1 n-TiO2, while the expression levels of cathepsin L and of antioxidant genes such as superoxide dismutase and glutathione peroxidase were significantly reduced with increasing concentrations of n-TiO2. This study shows for the first time the responsiveness and sensitivity of an Antarctic freshwater crustacean to n-TiO2 exposure and supports its suitability as a biomonitor of CECs in Antarctica.
Purpose
This study aims to unify phenomena in academic and grey literature into a theory of marine spatial disappropriation based on geopolitical relationships. It is argued that conflict over marine ...space arises as a result of top-down sovereign control of marine resources, and that the recognition of marine tenure and greater inclusivity in marine development* decision-making would lessen conflict between users, such as artisanal fishermen and ecotourism businesses.
Design/methodology/approach
A preliminary literature review was conducted, followed by a research study at Cabo Pulmo National Park (CPNP) in Baja California Sur, Mexico.
Findings
The results demonstrate that though CPNP's tenure structure is unique and inclusivity is an element of its management, the degree to which it is practiced is not sufficient to eliminate the chance of eventual disappropriation and ensuing conflict.
Practical implications
The results of this assessment can be used to strengthen the argument in favour of developing stronger requirements for deliberative democratic decision-making in marine delineation, as well as bolder social performance standards in marine development industries.
Originality/value
Research on socio-environmental revolutions are not new, but the authors contest that they are not alone a sufficient condition for achieving reduced conflict long-term. Instead, the originality of this research lies in its exploration of the importance of customary and formal tenure over marine resources, and its suggestion that this on the whole reduces conflict between exclusive and competing interests. One popular alternative, as demonstrated in numerous cases around the globe, can often be the marginalization of small-scale ocean users through the forceful appropriation of ocean resources.
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