Advancing Research for the Management of Long-Lived Species: A Case Study on the Greenland Shark

Long-lived species share life history traits such as slow growth, late maturity, and low fecundity, which lead to slow recovery rates and increase a population’s vulnerability to disturbance. The Greenland shark (Somniosus microcephalus) has recently been recognized as the world’s longest-lived vertebrate, but many questions regarding its biology, physiology, and ecology remain unanswered. Here we review how current and future research will fill knowledge gaps about the Greenland shark and provide an overall framework to guide research and management priorities for this species. Key advances include the potential for specialized aging techniques and demographic studies to shed light on the distribution and age-class structure of Greenland shark populations. Advances in population genetics and genomics will reveal key factors contributing to the Greenland shark’s extreme longevity, range and population size, and susceptibility to environmental change. New tagging technologies and improvements in experimental and analytical design will allow detailed monitoring of movement behaviors and interactions among Greenland sharks and other marine species, while shedding light on habitat use and susceptibility to fisheries interactions. Interdisciplinary approaches, such as the combined use of stable isotope analysis and high-tech data-logging devices (i.e., accelerometers and acoustic hydrophones) have the potential to improve knowledge of feeding strategies, predatory capabilities, and the trophic role of Greenland sharks. Measures of physiology, including estimation of metabolic rate, as well as heart rate and function, will advance our understanding of the causes and consequences of long lifespans. Determining the extent and effects of current threats (as well as potential mitigation measures) will assist the development of policies, recommendations, and actions relevant for the management of this potentially vulnerable species. Through an interdisciplinary lens, we propose innovative approaches to direct the future study of Greenland sharks and promote the consideration of longevity as an important factor in research on aquatic and terrestrial predators

Studies of ALN: An Empirical Assessment

This analysis of the research literature seeks to gain insight into the study of effectiveness of Asynchronous Learning Networks (ALN). A database of material gathered from the papers reporting the studies is described. The current picture of that data is highlighted and discussed. Additional papers are expected to be supportive of a need for better research techniques in the ALN community

Improved methods of analysis for betaines in Ascophyllum nodosum and its commercial seaweed extracts

Beneficial effects of seaweeds and their extracts on crop performance have been attributed to a variety of compounds, including the betaines which are quaternary ammonium betaines. Methods of analysis of betaines published thus far suffer from low sensitivity, lack of baseline separation of individual betaines and from interference from other sample constituents. A rapid cleanup protocol and a sensitive LC- MS/MS method of analysis were developed to afford baseline separation of four betaines in the brown alga Ascophyllum nodosum and its commercial seaweed extract. Using this method, the presence of glycine betaine, \u3b4-aminovaleric acid betaine, \u3b3-aminobutyric acid betaine and laminine in A. nodosum, and commercial extracts derived from A. nodosum, were confirmed and quantified. The major betaine present was \u3b3-aminobutyric acid betaine accounting for 0.008-0.014% of the dry weight of the seaweed and 0.014-0.027% of the dry weight of the commercial extracts. Seasonal variation in betaine content was observed. Differences in the total betaine content were observed between A. nodosum of the yellow (0.011-0.017% dry weight) and the olive green (0.017-0.021% dry weight) coloured morphologies.Peer reviewed: YesNRC publication: Ye

Ascophyllum nodosum extract mitigates salinity stress in Arabidopsis thaliana by modulating the expression of miRNA involved in stress tolerance and nutrient acquisition.

Ascophyllum nodosum extract (ANE) contains bioactive compounds that improve the growth of Arabidopsis in experimentally-induced saline conditions; however, the molecular mechanisms through which ANE elicits tolerance to salinity remain largely unexplored. Micro RNAs (miRNAs) are key regulators of gene expression, playing crucial roles in plant growth, development, and stress tolerance. Next generation sequencing of miRNAs from leaves of control Arabidopsis and from plants subjected to three treatments (ANE, NaCl and ANE+NaCl) was used to identify ANE-responsive miRNA in the absence and presence of saline conditions. Differential gene expression analysis revealed that ANE had a strong effect on miRNAs expression in both conditions. In the presence of salinity, ANE tended to reduce the up-regulation or the down-regulation trend induced caused by NaCl in miRNAs such as ath-miR396a-5p, ath-miR399, ath-miR2111b and ath-miR827. To further uncover the effects of ANE, the expression of several target genes of a number of ANE-responsive miRNAs was analyzed by qPCR. NaCl, but not ANE, down-regulated miR396a-5p, which negatively regulated the expression of AtGRF7 leading to a higher expression of AtDREB2a and AtRD29 in the presence of ANE+NaCl, as compared to ANE alone. ANE+NaCl initially reduced and then enhanced the expression of ath-miR169g-5p, while the expression of the target genes AtNFYA1 and ATNFYA2, known to be involved in the salinity tolerance mechanism, was increased as compared to ANE or to NaCl treatments. ANE and ANE+NaCl modified the expression of ath-miR399, ath-miR827, ath-miR2111b, and their target genes AtUBC24, AtWAK2, AtSYG1 and At3g27150, suggesting a role of ANE in phosphate homeostasis. In vivo and in vitro experiments confirmed the improved growth of Arabidopsis in presence of ANE, in saline conditions and in phosphate-deprived medium, further substantiating the influence of ANE on a variety of essential physiological processes in Arabidopsis including salinity tolerance and phosphate uptake

Transcriptional and metabolomic analysis of <it>Ascophyllum nodosum</it> mediated freezing tolerance in <it>Arabidopsis thaliana</it>

<p>Abstract</p> <p>Background</p> <p>We have previously shown that lipophilic components (LPC) of the brown seaweed <it>Ascophyllum nodosum</it> (ANE) improved freezing tolerance in <it>Arabidopsis thaliana</it>. However, the mechanism(s) of this induced freezing stress tolerance is largely unknown. Here, we investigated LPC induced changes in the transcriptome and metabolome of <it>A. thaliana</it> undergoing freezing stress.</p> <p>Results</p> <p>Gene expression studies revealed that the accumulation of proline was mediated by an increase in the expression of the proline synthesis genes <it>P5CS1</it> and <it>P5CS2</it> and a marginal reduction in the expression of the proline dehydrogenase (<it>ProDH</it>) gene. Moreover, LPC application significantly increased the concentration of total soluble sugars in the cytosol in response to freezing stress. Arabidopsis <it>sfr4</it> mutant plants, defective in the accumulation of free sugars, treated with LPC, exhibited freezing sensitivity similar to that of untreated controls. The ¹H NMR metabolite profile of LPC-treated Arabidopsis plants exposed to freezing stress revealed a spectrum dominated by chemical shifts (δ) representing soluble sugars, sugar alcohols, organic acids and lipophilic components like fatty acids, as compared to control plants. Additionally, 2D NMR spectra suggested an increase in the degree of unsaturation of fatty acids in LPC treated plants under freezing stress. These results were supported by global transcriptome analysis. Transcriptome analysis revealed that LPC treatment altered the expression of 1113 genes (5%) in comparison with untreated plants. A total of 463 genes (2%) were up regulated while 650 genes (3%) were down regulated.</p> <p>Conclusion</p> <p>Taken together, the results of the experiments presented in this paper provide evidence to support LPC mediated freezing tolerance enhancement through a combination of the priming of plants for the increased accumulation of osmoprotectants and alteration of cellular fatty acid composition.</p