Comparative Population Transcriptomics Provide New Insight into the Evolutionary History and Adaptive Potential of World Ocean Krill.

Genetic variation is instrumental for adaptation to changing environments but it is unclear how it is structured and contributes to adaptation in pelagic species lacking clear barriers to gene flow. Here, we applied comparative genomics to extensive transcriptome datasets from 20 krill species collected across the Atlantic, Indian, Pacific, and Southern Oceans. We compared genetic variation both within and between species to elucidate their evolutionary history and genomic bases of adaptation.

Light curves and colours of the ejecta from Dimorphos after the DART impact.

On 26 September 2022, the Double Asteroid Redirection Test (DART) spacecraft struck Dimorphos, a satellite of the asteroid 65803 Didymos. Because it is a binary system, it is possible to determine how much the orbit of the satellite changed, as part of a test of what is necessary to deflect an asteroid that might threaten Earth with an impact. In nominal cases, pre-impact predictions of the orbital period reduction ranged from roughly 8.

Structure-Based Functional Analysis of a Hormone Belonging to an Ecdysozoan Peptide Superfamily: Revelation of a Common Molecular Architecture and Residues Possibly for Receptor Interaction.

A neuropeptide (Sco-CHH-L), belonging to the crustacean hyperglycemic hormone (CHH) superfamily and preferentially expressed in the pericardial organs (POs) of the mud crab , was functionally and structurally studied. Its expression levels were significantly higher than the alternative splice form (Sco-CHH) in the POs, and increased significantly after the animals were subjected to a hypo-osmotic stress. Sco-CHH-L, but not Sco-CHH, significantly stimulated in vitro the Na, K-ATPase activity in the posterior (6th) gills.

Dinophyceae can use exudates as weapons against the parasite Amoebophrya sp. (Syndiniales).

Parasites in the genus Amoebophrya sp. infest dinoflagellate hosts in marine ecosystems and can be determining factors in the demise of blooms, including toxic red tides. These parasitic protists, however, rarely cause the total collapse of Dinophyceae blooms.

The Crustacean Hyperglycemic Hormone Superfamily: Progress Made in the Past Decade.

Early studies recognizing the importance of the decapod eyestalk in the endocrine regulation of crustacean physiology-molting, metabolism, reproduction, osmotic balance, etc.-helped found the field of crustacean endocrinology. Characterization of putative factors in the eyestalk using distinct functional bioassays ultimately led to the discovery of a group of structurally related and functionally diverse neuropeptides, crustacean hyperglycemic hormone (CHH), molt-inhibiting hormone (MIH), gonad-inhibiting hormone (GIH) or vitellogenesis-inhibiting hormone (VIH), and mandibular organ-inhibiting hormone (MOIH).

Antarctic krill (Euphausia superba) in a warming ocean: thermotolerance and deciphering Hsp70 responses.

The Antarctic krill, Euphausia superba, is a Southern Ocean endemic species of proven ecological importance to the region. In the context of predicted global warming, it is particularly important to understand how classic biomarkers of heat stress function in this species. In this respect, Hsp70s are acknowledged as good candidates.

Do transparent exopolymeric particles (TEP) affect the toxicity of nanoplastics on Chaetoceros neogracile?

The potential presence of nanoplastics (NP) in aquatic environments represents a growing concern regarding their possible effects on aquatic organisms. The objective of this study was to assess the impact of polystyrene (PS) amino-modified particles (50  nm PSNH) on the cellular and metabolic responses of the diatom Chaetoceros neogracile cultures at two essential phases of the growth cycle, i.e.

Bioactive Bromotyrosine-Derived Alkaloids from the Polynesian Sponge .

Herein, we describe the isolation and spectroscopic identification of eight new tetrabrominated tyrosine alkaloids ⁻ from the Polynesian sponge , along with known major compound psammaplysene D (), ,-dimethyldibromotyramine, 5-hydroxy xanthenuric acid, and xanthenuric acid. Cytotoxicity and acetylcholinesterase inhibition activities were evaluated for some of the isolated metabolites. They exhibited moderate antiproliferative activity against KB cancer cell lines, but psammaplysene D () displayed substantial cytotoxicity as well as acetylcholinesterase inhibition with IC values of 0.

Differential effects of silencing crustacean hyperglycemic hormone gene expression on the metabolic profiles of the muscle and hepatopancreas in the crayfish Procambarus clarkii.

In order to functionally characterize the metabolic roles of crustacean hyperglycemic hormone (CHH), gene expression of CHH in the crayfish (Procambarus clarkii) was knocked down by in vivo injection of CHH double-stranded RNA (dsRNA), followed by metabolomic analysis of 2 CHH target tissues (the muscle and hepatopancreas) using nuclear magnetic resonance spectroscopy. Compared to the levels in untreated and saline-injected (SAI) animals, levels of CHH transcript, but not those of molt-inhibiting hormone (a CHH-family peptide), in the eyestalk ganglia of CHH dsRNA-injected (DSI) animals were significantly decreased at 24, 48, and 72 hour post injection (hpi), with concomitant changes in levels of CHH peptide in the sinus gland (a neurohemal organ) and hemolymph. Green fluorescence protein (GFP) dsRNA failed to affect levels of CHH transcript in the eyestalk ganglia of GFP DSI animals.

Responses of the arcto-boreal krill species Thysanoessa inermis to variations in water temperature: coupling Hsp70 isoform expressions with metabolism.

Recent studies have indicated a metabolic temperature sensitivity in both the arcto-boreal krill species Thysanoessa inermis and Thysanoessa raschii that may determine these species' abundance and population persistence at lower latitudes (up to 40° N). T. inermis currently dominates the krill community in the Barents Sea and in the high Arctic Kongsfjord.

Metabolic effects of parasitization by the barnacle Polyascus plana (Cirripedia: Rhizocephala: Sacculinidae) on a grapsid host, Metopograpsus thukuhar.

Pathophysiological studies of rhizocephalan infections are rare. We describe differences in the levels of tissue and hemolymph metabolites between Polyascus plana-parasitized and unparasitized individuals of Metopograpsus thukuhar. Crabs were assigned to either a parasitized (carrying at least 1 externa, i.

Divergent ecological histories of two sister Antarctic krill species led to contrasted patterns of genetic diversity in their heat-shock protein (hsp70) arsenal.

The Arctic and the Antarctic Peninsula are currently experiencing some of the most rapid rates of ocean warming on the planet. This raises the question of how the initial adaptation to extreme cold temperatures was put in place and whether or not directional selection has led to the loss of genetic variation at key adaptive systems, and thus polar species' (re)adaptability to higher temperatures. In the Southern Ocean, krill represents the most abundant fauna and is a critical member at the base of the Antarctic food web.

Functional Assessment of Residues in the Amino- and Carboxyl-Termini of Crustacean Hyperglycemic Hormone (CHH) in the Mud Crab Scylla olivacea Using Point-Mutated Peptides.

To assess functional importance of the residues in the amino- and carboxyl-termini of crustacean hyperglycemic hormone in the mud crab Scylla olivacea (Sco-CHH), both wild-type and point-mutated CHH peptides were produced with an amidated C-terminal end. Spectral analyses of circular dichroism, chromatographic retention time, and mass spectrometric analysis of the recombinant peptides indicate that they were close in conformation to native CHH and were produced with the intended substitutions. The recombinant peptides were subsequently used for an in vivo hyperglycemic assay.

Diversification, evolution and sub-functionalization of 70kDa heat-shock proteins in two sister species of antarctic krill: differences in thermal habitats, responses and implications under climate change.

Background: A comparative thermal tolerance study was undertaken on two sister species of Euphausiids (Antarctic krills) Euphausia superba and Euphausia crystallorophias. Both are essential components of the Southern Ocean ecosystem, but occupy distinct environmental geographical locations with slightly different temperature regimes. They therefore provide a useful model system for the investigation of adaptations to thermal tolerance.

Biogenesis of D-amino acid containing peptides/proteins: where, when and how?

Peptides and proteins are chiral molecules with their structure determined by the composition and configuration of the amino acids constituting them. Natural amino acids (except glycine) display two chiral types (l- and d-enantiomers). For example, the presence of octopine, a derivative of l-arginine and d-alanine in octopus, or peptidyl poly-d-glutamic acid in a bacterial cell wall was demonstrated in the 1920s and 1930s, respectively.

Transcriptome and peptidome characterisation of the main neuropeptides and peptidic hormones of a euphausiid: the Ice Krill, Euphausia crystallorophias.

Background: The Ice krill, Euphausia crystallorophias is one of the species at the base of the Southern Ocean food chain. Given their significant contribution to the biomass of the Southern Ocean, it is vitally important to gain a better understanding of their physiology and, in particular, anticipate their responses to climate change effects in the warming seas around Antarctica.

Methodology/principal Findings: Illumina sequencing was used to produce a transcriptome of the ice krill.

Experimental strategies for the analysis of D-amino acid containing peptides in crustaceans: a review.

Detection of D-amino acids in natural peptides has been, and remains a challenging task, as peptidyl isomerization is a peculiar and subtle posttranslational modification that does not induce any change in primary sequence or in physicochemical properties of the molecule such as molecular mass or pI. Therefore, the presence of a D-amino acid residue in a peptide chain is generally transparent to classical methods of peptide analysis (electrophoresis, chromatography, mass spectrometry, molecular biology). In this article, we will review the various experimental strategies and analytical techniques, which have been used to characterize and to study D-amino acid containing peptides in crustaceans.

Antarctic krill 454 pyrosequencing reveals chaperone and stress transcriptome.

Background: The Antarctic krill Euphausia superba is a keystone species in the Antarctic food chain. Not only is it a significant grazer of phytoplankton, but it is also a major food item for charismatic megafauna such as whales and seals and an important Southern Ocean fisheries crop. Ecological data suggest that this species is being affected by climate change and this will have considerable consequences for the balance of the Southern Ocean ecosystem.

Molecular evolution of the crustacean hyperglycemic hormone family in ecdysozoans.

Background: Crustacean Hyperglycemic Hormone (CHH) family peptides are neurohormones known to regulate several important functions in decapod crustaceans such as ionic and energetic metabolism, molting and reproduction. The structural conservation of these peptides, together with the variety of functions they display, led us to investigate their evolutionary history. CHH family peptides exist in insects (Ion Transport Peptides) and may be present in all ecdysozoans as well.

Thermal biology of the deep-sea vent annelid Paralvinella grasslei: in vivo studies.

The annelid Paralvinella grasslei is a deep-sea vent endemic species that colonizes the wall of active chimneys. We report here the first data on its thermal biology based on in vivo experiments in pressurized aquaria. Our results demonstrate that P.

New insights into evolution of crustacean hyperglycaemic hormone in decapods--first characterization in Anomura.

The neuropeptides of the crustacean hyperglycaemic hormone (CHH) family are encoded by a multigene family and are involved in a wide spectrum of essential functions. In order to characterize CHH family peptides in one of the last groups of decapods not yet investigated, CHH was studied in two anomurans: the hermit crab Pagurus bernhardus and the squat lobster Galathea strigosa. Using RT-PCR and 3' and 5' RACE methods, a preproCHH cDNA was cloned from the major neuroendocrine organs (X-organs) of these two species.

Crustacean hyperglycemic and vitellogenesis-inhibiting hormones in the lobster Homarus gammarus.

Crustacean hyperglycemic hormone (CHH) and vitellogenesis-inhibiting hormone (VIH), produced by the X organ-sinus gland neurosecretory complex, belong to a peptide group referred to as the CHH family, which is widely distributed in arthropods. In this study, genetic variants and post-translationally modified isoforms of CHH and VIH were characterized in the European lobster Homarus gammarus. With the use of RP-HPLC and ELISA with specific antibodies that discriminate between stereoisomers of CHH and VIH, two groups of CHH-immunoreactive peaks were characterized from HPLC fractions of sinus gland extract (CHH A and CHH B); each group contained two variants (CHH and D-Phe3CHH).