Marine Life Science & Technology最新文献

Nervous necrosis virus (NNV) is the etiological agent of viral encephalopathy and retinopathy in many fish species, including European sea bass (Dicentrachus labrax) and is of great economic losses to fish farmers. To solve this problem in fish production, antimicrobial peptides (AMPs) have been identified as potential candidates for NNV treatment in aquaculture. Hepcidin (Hamp) is one of the most promising AMPs. Thus, we aimed to evaluate the therapeutic application of Hamp synthetic peptide after NNV challenge. Hamp was able to significantly increase survival rates and ameliorate clinical signs of the disease, though the viral levels, determined by viral replication and immunolocalization, were not affected. Synthetic Hamp increased the immunoglobulin M (IgM) and AMP protein levels in serum and some tissues respect to the levels found in NNV-infected fish. However, Hamp peptide decreased the NNV-induced bactericidal activity. At the gene level, Hamp exerted anti-inflammatory properties, reducing the pro-inflammatory response orchestrated by NNV, probably preventing neuronal damage. Apart from this, Hamp up-regulated the expression of adhesion molecules that facilitated the recruitment of immune cells, namely T helper and B cells, probably to orchestrate the adaptive response. To conclude, Hamp immunomodulatory properties and therapeutic application against NNV are very promising for its use in aquaculture.

Supplementary information: The online version contains supplementary material available at 10.1007/s42995-024-00262-w.

Free trans-4-hydroxy-L-proline (T4LHyp), a non-proteinogenic amino acid, is mainly released from the degradation of collagen, hydroxyproline-rich glycoproteins, and some peptide antibiotics in nature. Although it has been known that some terrestrial bacteria utilize T4LHyp as carbon and nitrogen source via a T4LHyp gene cluster, which and how marine microorganisms catabolize T4LHyp still remains unclear. Here, five T4LHyp-utilizing marine bacterial strains, Halomonas sp. 5021, Salinicola sp. 4072, Alteromonas sp. 6022, Alteromonas sp. 5112 and Alteromonas sp. 30521, were isolated from hydrothermal vent sediment samples collected from the southwest Indian Ocean. While Halomonas sp. 5021 can utilize T4LHyp as both a nitrogen and carbon source, the other four strains can utilize T4LHyp as only a nitrogen source. Then, the T4LHyp catabolic mechanisms of Halomonas sp. 5021 and Salinicola sp. 4072, as a representative of the four strains, were further investigated by genomic, transcriptional, and biochemical analyses. Halomonas sp. 5021 adopts an intact T4LHyp gene cluster containing four enzymes to catabolize T4LHyp into NH₃ and α-ketoglutarate to provide nitrogen and carbon sources for its growth. Compared to Halomonas sp. 5021, Salinicola sp. 4072 lacks an α-KGSA dehydrogenase gene in the T4LHyp gene cluster and can only catabolize T4LHyp into NH₃ and α-ketoglutarate semialdehyde to provide a nitrogen source for its growth. Bioinformatic investigation showed that the 5021-like and 4072-like T4LHyp gene clusters are predominantly found in bacteria from Pseudomonadota, which are widely distributed in multiple marine habitats. Thus, Pseudomonadota bacteria are likely the dominant group to drive the recycling and mineralization of T4LHyp in the ocean.

Supplementary information: The online version contains supplementary material available at 10.1007/s42995-024-00272-8.

Zeaxanthin, an oxygenated carotenoid derivative with potent antioxidative properties, is produced by many organism taxa. Flavobacteriaceae are widely distributed in marine environments; however, the zeaxanthin biosynthesis property in this family remains incompletely explored. Here, we characterized zeaxanthin production by marine Flavobacteriaceae strains and elucidated underlying molecular mechanisms. Eight Flavobacteriaceae strains were isolated from the phycosphere of various dinoflagellates. Analyses of the zeaxanthin production in these strains revealed yields ranging from 5 to 3289 µg/g of dry cell weight. Genomic and molecular biology analyses revealed the biosynthesized zeaxanthin through the mevalonate (MVA) pathway diverging from the 2-C-methyl-d-erythritol-4-phosphate (MEP) pathway commonly observed in most Gram-negative bacteria. Furthermore, comprehensive genome analyses of 322 culturable marine Flavobacteriale strains indicated that the majority of Flavobacteriaceae members possess the potential to synthesize zeaxanthin using precursors derived from the MVA pathway. These data provide insight into the zeaxanthin biosynthesis property in marine Flavobacteriaceae strains, highlighting their ecological and biotechnological relevance.

Supplementary information: The online version contains supplementary material available at 10.1007/s42995-024-00268-4.

Tiny unicellular cyanobacteria or picocyanobacteria (0.5-3 µm) are important due to their ecological significance. Chesapeake Bay is a temperate estuary that contains abundant and diverse picocyanobacteria. Studies of Chesapeake Bay picocyanobacteria in the past 20 years led to the finding of new members of subcluster 5.2 Synechococcus. They laid the foundation for revealing the ecophysiology, biogeography, genomics, and molecular evolution of picocyanobacterial in the Chesapeake Bay and other coastal estuaries. The Bay picocyanobacteria are known to better tolerate the changes in temperature, salinity, and heavy metals compared to their coastal and open-ocean counterparts. Many picocyanobacteria isolated from the Bay contain rich toxin-antitoxin (TA) genes, suggesting that the TA system may provide them with a genetic advance to cope with variable estuarine environments. Distinct winter and summer picocyanobacteria are present in the Bay, suggesting a dynamic seasonal shift of the picocyanobacterial community in the temperate estuary. While the Bay contains subcluster 5.2 Synechococcus, it also contains freshwater Synechococcus, Cyanobium, and marine Synechococcus due to river influx and the ocean's tidal influence. Some Chesapeake Bay picocyanobacterial clades were found in the Bering Sea and Chukchi Sea, showing a link between the Bay and polar picocyanobacteria. Genomic sequences of estuarine picocyanobacteria provide new insight into the taxonomy and evolution of freshwater, estuarine, and marine unicellular cyanobacteria. Estuaries connect freshwater and marine ecosystems. This overview attempts to extend what we learned from Chesapeake Bay picocyanobacteria to picocyanobacteria in freshwater and marine waters.

The interaction of riverine inputs and ocean current systems causes complex spatiotemporal variations in phytoplankton dynamics in marginal seas of the northwest Pacific Ocean, yet quantitative assessments of these variations and their causes remain limited. Here we evaluate phytoplankton biomass and community structure changes using lipid biomarkers, accompanying ocean circulation and nutrient variations in surface waters collected in spring and summer of 2017-2018 at 118 sites in the East China Sea off the Zhejiang coast. High biomass of diatoms, inferred from brassicasterol concentrations, shifted from the south in spring to the north in summer, while high dinoflagellate biomass, inferred from dinosterol concentrations, occurred mainly in the Changjiang (Yangtze) River plume and adjacent areas in both seasons. Seasonal variation in phytoplankton distribution was linked to the spatial extents of water masses such as the Changjiang Diluted Water (CDW) and the intrusion of the Kuroshio Subsurface Water (KSSW). A three end-member mixing model was applied to quantify water mass contributions. The results showed that an increase in the KSSW (from 0 to 40%) and a decrease in the CDW (from 100 to 20%) resulted in a significant (20%) increase in diatom proportions and a significant (20%) decrease in dinoflagellate proportions. Dinoflagellate proportions were highest in the CDW-dominated region, while diatoms and total phytoplankton biomass were higher in the CDW-KSSW mixing region and the KSSW-dominated region. This study highlights the dynamic response of the phytoplankton community to water mass changes in marginal seas that can aid coastal ecosystem management.

Supplementary information: The online version contains supplementary material available at 10.1007/s42995-024-00260-y.

Psammophillic ciliates are an integral part of the foodweb despite being underrepresented in terms of molecular phylogeny and modern taxonomy. To investigate the karyorelictean group, sampling was conducted in interstitial marine habitats in China for ciliates living between the sand grains, resulting in an examination of the families Cryptopharyngidae Jankowski, 1980 and Kentrophoridae Jankowski, 1980. Three species, i.e., Cryptopharynx setigerus Kahl, 1928, Kentrophoros fasciolatus (Sauerbrey, 1928) Foissner, 1995 and K. fistulosus (Fauré-Fremiet, 1950) Foissner, 1995, are clearly recognized as being cosmopolitan, while other species await further recording. Phylogenetic analyses were carried out based on updated data. These revealed that the families Cryptopharyngidae and Kentrophoridae are closely related, and most genera studied are monophyletic, although Cryptopharynx qingdaoensis n. sp. is located within the Kentrophoridae branch. Brief revisions of two genera, namely Cryptopharynx Kahl, 1928 and Kentrophoros Sauerbrey, 1928, are provided including keys to the identification of nine species belonging to the former and 12 species belonging to the latter. One new genus, Parakentrophoros n. gen., and one new species, Cryptopharynx qingdaoensis n. sp., are described and a new combination, Parakentrophoros canalis (Wright, 1982) n. comb., is established. Finally, it appears that the subapical oral apparatus undergoes a gradual degeneration process from Cryptopharyngidae to Kentrophoridae.

Scuticociliatia is one of the most species-rich subclasses in the phylum Ciliophora. The evolutionary relationships among Scuticociliatia groups have long been very unclear due to the homogeneity of morphology and insufficiency of molecular data. With morphological and multi-gene-based molecular data presented here, the evolutionary phylogeny of several Scuticociliatia taxa that were hitherto especially poorly defined is analyzed and discussed. The results indicate: (1) all scuticociliates cluster into two well supported and one poorly supported group, representing three order-level taxa; (2) with the support of both morphological and molecular data, a new family Homalogastridae fam. nov. is proposed in the order Philasterida; (3) Parauronema is formally transferred to Uronematidae and Potomacus is treated as incertae sedis in the order Philasterida, therefore Parauronematidae is proposed to be a junior synonym of Uronematidae; (4) the genus Madsenia and the species Parauronema longum and Pseudocyclidium longum are treated as incertae sedis, while the genus Protophyra should be maintained in the family Ancistridae. In addition, the putative secondary structure of internal transcribed spacer 2 (ITS2) of representative taxa from the three orders of Scuticociliatia are analyzed, and consensus structures and nucleotide composition in each order are exhibited.

Supplementary information: The online version contains supplementary material available at 10.1007/s42995-024-00264-8.

CO₂ concentration mechanisms (CCMs) are important in maintaining the high efficiency of photosynthesis of marine algae. Aquatic photoautotrophs have two types of CCMs: biophysical CCMs, based on the conversion of inorganic carbon, and biochemical CCMs, based on the formation of C₄ acid intermediates. However, the contribution of biophysical and biochemical CCMs to algal carbon fixation remains unclear. Here, we used ethoxyzolamide (EZ) inhibitors of carbonic anhydrase and 3-mercaptopicolinic acid (MPA) inhibitors for phosphoenolpyruvate carboxykinase to examine the importance of biophysical and biochemical CCMs in photosynthesis of the green macroalga Ulva prolifera. The culture experiments showed that the carbon fixation of the species declined when EZ inhibited the biophysical CCM, while the increase in cyclic electron flow around the photosystem I indicated a more active biochemical CCM, contributing to ~ 50% of total carbon fixation. The biophysical CCM was also reinforced when MPA inhibited the biochemical CCM. In a comparison, the biophysical CCM can compensate for almost 100% of total carbon fixation. The results indicate that biophysical CCMs dominate the process of carbon fixation of U. prolifera while biochemical CCM plays a supporting role. Our results provide evidence of a complementary coordination mechanism between the biophysical and biochemical CCMs that promotes the efficiency of photosynthesis of U. prolifera, an efficient mechanism to boost the alga's bloom.

Supplementary information: The online version contains supplementary material available at 10.1007/s42995-024-00265-7.

[This corrects the article DOI: 10.1007/s42995-024-00229-x.].

Kelps are pivotal to temperate coastal ecosystems, providing essential habitat and nutrients for diverse marine life, and significantly enhancing local biodiversity. The impacts of elevated CO₂ levels on kelps may induce far-reaching effects throughout the marine food web, with potential consequences for biodiversity and ecosystem functions. This study considers the kelp Macrocystis pyrifera and its symbiotic microorganisms as a holistic functional unit (holobiont) to examine their collective response to heightened CO₂ levels. Over a 4 month cultivation from the fertilization of M. pyrifera gametes to the development of juvenile sporophytes, our findings reveal that elevated CO₂ levels influence the structure of the M. pyrifera symbiotic microbiome, alter metabolic profiles, and reshape microbe-metabolite interactions using 16S rRNA amplicon sequencing and liquid chromatography coupled to mass spectrometry analysis. Notably, Dinoroseobacter, Sulfitobacter, Methylotenera, Hyphomonas, Milano-WF1B-44 and Methylophaga were selected as microbiome biomarkers, which showed significant increases in comparative abundance with elevated CO₂ levels. Stress-response molecules including fatty-acid metabolites, oxylipins, and hormone-like compounds such as methyl jasmonate and prostaglandin F2a emerged as critical metabolomic indicators. We propose that elevated CO₂ puts certain stress on the M. pyrifera holobiont, prompting the release of these stress-response molecules. Moreover, these molecules may aid the kelp's adaptation by modulating the microbial community structure, particularly influencing potential pathogenic bacteria, to cope with environmental change. These results will enrich the baseline data related to the chemical interactions between the microbiota and M. pyrifera and provide clues for predicting the resilience of kelps to future climate change.

Supplementary information: The online version contains supplementary material available at 10.1007/s42995-024-00259-5.