Current Articles

Review
Minireview: The role of viruses in marine photosynthetic bioflms
Andrew McMinn, Yantao Liang, Min Wang
2020, 2(3): 203-208. doi: 10.1007/s42995-020-00042-2
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Abstract:
Microphytobenthos and sea ice algae comprise globally significant photosynthetic biofilms. While their microalgal and bacterial constituents are well characterized,there is very little information on their viral communities or on the virus-bacteria and virus-algae interactions within them. While high levels of interaction might be expected because of the high density of cells,infection rates,particularly of microalgae,have been found to be low. It remains unclear whether this is a result of environment characteristics,developed resistance or because of the small number of studies.
Vibrio harveyi: a serious pathogen of fish and invertebrates in mariculture
XiaoHua Zhang, Xinxin He, Brian Austin
2020, 2(3): 231-245. doi: 10.1007/s42995-020-00037-z
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Abstract:
Vibrio harveyi, which belongs to family Vibrionaceae of class Gammaproteobacteria, includes the species V. carchariae and V. trachuri as its junior synonyms. The organism is a well-recognized and serious bacterial pathogen of marine fish and invertebrates, including penaeid shrimp, in aquaculture. Diseased fish may exhibit a range of lesions, including eye lesions/blindness, gastro-enteritis, muscle necrosis, skin ulcers, and tail rot disease. In shrimp, V. harveyi is regarded as the etiological agent of luminous vibriosis in which affected animals glow in the dark. There is a second condition of shrimp known as Bolitas negricans where the digestive tract is filled with spheres of sloughed-off tissue. It is recognized that the pathogenicity mechanisms of V. harveyi may be different in fish and penaeid shrimp. In shrimp, the pathogenicity mechanisms involved the endotoxin lipopolysaccharide, and extracellular proteases, and interaction with bacteriophages. In fish, the pathogenicity mechanisms involved extracellular hemolysin (encoded by duplicate hemolysin genes), which was identified as a phospholipase B and could inactivate fish cells by apoptosis, via the caspase activation pathway. V. harveyi may enter the so-called viable but nonculturable (VBNC) state, and resuscitation of the VBNC cells may be an important reason for vibriosis outbreaks in aquaculture. Disease control measures center on dietary supplements (including probiotics), nonspecific immunostimulants, and vaccines and to a lesser extent antibiotics and other antimicrobial compounds.
Impacts of ocean acidifcation under multiple stressors on typical organisms and ecological processes
Kunshan Gao, Guang Gao, Youji Wang, Sam Dupont
2020, 2(3): 279-291. doi: 10.1007/s42995-020-00048-w
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Abstract:
The oceans are taking up over one million tons of fossil CO2 per hour, resulting in increased pCO2 and declining pH, leading to ocean acidification (OA). At the same time, accumulation of CO2 and other greenhouse gases is causing ocean warming, which enhances stratification with thinned upper mixed layers, exposing planktonic organisms to increasing levels of daytime integrated UV radiation. Ocean warming also reduces dissolved oxygen in seawater, resulting in ocean deoxygenation. All these ocean global changes are impacting marine ecosystems and effects are well documented for each individual driver (pH, oxygen, temperature, UV). However, combined effects are still poorly understood, strongly limiting our ability to project impacts at regional or local levels. Different regions are often exposed (and often adapted) to contrastingly different physical and chemical environmental conditions and organisms, and ecosystems from different parts of the world will be exposed to unique combinations of stressors in the future. Understanding the modulating role of adaptation, species niche and stressorso interaction is key. This review, being a non-exhaustively explored one, aims to provide an overview on understandings of ecophysiological effects of OA and its combination with covarying drivers, mainly warming, deoxygenation and solar UV radiation. We propose a testable hypothetical model as well as future research perspectives.
Colonization features of marine biofilm-dwelling protozoa in Chinese coastal waters of the Yellow Sea
Mohammad Nurul Azim Sikder, Henglong Xu, Alan Warren
2020, 2(3): 292-301. doi: 10.1007/s42995-020-00040-4
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Abstract:
Colonization features of biofilm-dwelling protozoa, especially ciliates, are routinely used as a useful tool for marine bioassessment. In this review, we summarize some of these features to develop an optimal sampling strategy for using biofilm-dwelling protozoa as bioindicators of marine water quality. We focus on the utility of: (1) diversity indices to analyze the colonization features of biofilm-dwelling protozoa for monitoring marine water quality; (2) MacArthur-Wilson and logistic equation models to determine spatio-temporal variations in colonization dynamics; and (3) homogeneity in taxonomic breadth of biofilm-dwelling protozoa during the process of colonization. The main findings are that: (1) the colonization dynamics of biofilm-dwelling protozoa are similar at depths of 1-5 m in spring and autumn; (2) temporal variability was well fitted to the MacArthur-Wilson and logistic models (P < 0.05); and (3) species composition reached an equilibrium after a colonization period of 10-14 days in spring and autumn, but this took less time in the summer and more time in the winter. Ellipse-plotting tests demonstrated spatial variability in homogeneity in taxonomic structure of the ciliate communities at different depths in the water column, with high levels at 1 m and 2 m and lower levels at 3.5 m and 5 m. Thus, the findings of this review suggest that the colonization dynamics of biofilm-dwelling protozoa may be influenced by different depths and seasons in coastal waters and 1-2 m in spring and autumn may be optimal sampling strategy for bioassessment on large spatial/temporal scales in marine ecosystems.
Research Paper
Redescription of five tintinnine ciliates (Alveolata: Ciliophora: Oligotrichea) from coastal waters of Qingdao, China
Yang Bai, Rui Wang, Wen Song, Suzuki Toshikazu, Xiaozhong Hu
2020, 2(3): 209-221. doi: 10.1007/s42995-020-00034-2
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Abstract:
Tintinnine ciliates are widely distributed around the world and are characterized by the possession of a lorica that is highly diverse in structure and morphology. In the present study, five tintinnines, namely Tintinnopsis cf. radix, T. everta Kofoid and Campbell, 1929, T. mulctrella Kofoid and Campbell, 1929, Eutintinnus inflatus Marshall, 1969, and Favella ehrenbergii (Claparède and Lachmann, 1858) Jörgensen, 1924, were collected from coastal waters of Qingdao, China. Three are newly recorded from China, i.e., T. everta, T. mulctrella, and E. inflatus. The morphology of the lorica and cell proper of all five species are described and compared with original and subsequent descriptions. The morphology in vivo of the lorica and cell proper of all five species are described and compared with original and subsequent descriptions. In addition, the ciliary patterns of F. ehrenbergii and T. cf. radix are revealed based on protargol-stained specimens.
cDNA cloning of four Hsp genes from Agarophyton vermiculophyllum and transcription analysis in different phases
Xiaohui Pan, Weifang Zhu, Di Xu, Hongyan Yang, Xiaofei Cao, Zhenghong Sui
2020, 2(3): 222-230. doi: 10.1007/s42995-020-00049-9
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Abstract:
Agarophyton vermiculophyllum is an agarophytic red alga originating from Northeast Asia that successfully spread to Europe and North America in the last 20 years. In this study, three hsp70 genes (hsp70-1, hsp70-2, and hsp70-3) and one hsp90 gene were cloned, and real-time reverse transcription polymerase chain reaction (RT-qPCR) was used to measure their transcriptional levels in three kinds of thalli (tetrasporophytes, and male/female gametophytes) belonging to diploid or haploid phases in the life cycle of A. vermiculophyllum. The results show that the three Hsp70s in A. vermiculophyllum clustered into three different groups, and the locations of the putative Hsp70-1, Hsp70-2, and Hsp70-3 were in the cytoplasm, endoplasmic reticulum and chloroplast, respectively, according to their sequences. Beside on the same research, the putative Hsp90 was supposed to have a cytoplasmic location. The RT-qPCR results show that the three hsp70 genes were highly upregulated in gametophytes as compared to tetrasporophytes but the transcriptional level of hsp90 did not show such a significant increase. The chloroplast hsp70-3 exhibited the highest upregulation and the transcriptional level increased more than 570 fold in female gametophytes, and 17 fold in male gametophytes, compared with tetrasporophytes. Therefore, cpHsp70-3 might act more like a chaperon molecule involved in haploid development under natural condition, while Hsp70-1 and Hsp70-2 were more active in stress resistance.
Radiographic and tomographic description of marlin sucker Remora osteochir, Pisces: Echeneidae—preliminary data of one specimen
André Luiz Veiga Conrado, Renata Stecca Iunes, Carlos Eduardo Malavasi Bruno, Aline Tiemi Shiraishi Rocha, José Roberto Machado Cunha da Silva
2020, 2(3): 246-251. doi: 10.1007/s42995-020-00036-0
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Abstract:
Remoras are commensal fish of various marine species, such as sharks, swordfishes, turtles, dolphins, manta rays and whales. One specimen of marlin sucker Remora osteochir was evaluated using computed tomography for skeletal digital reconstruction, digital radiology for general evaluation and bone counting, and the double contrast technique to distinguish coelomic organs. In radiographic images, it was possible to observe otoliths in the center of the neurocranium, to count 27 vertebrae, nine pairs of ribs, and to detect the presence of the hipural and epural bones near of the caudal fin. In double contrast images, it was possible to visualize the swim bladder, gills, heart, liver, stomach and intestines. From the tomographic images and reconstructions, it was possible to identify the intercalar bones of the cephalic disc; the spine with vertebral bodies composed of neural arches and ventral ribs; and the pectoral girdle formed by posttemporal, cleithrum and scapulocoracoid bones. It was concluded that digital radiology and computed tomography were able to describe anatomical structures of marlin sucker R. osteochir without the need for dissection.
Glutathione S-transferase genes in scallops and their diverse expression patterns after exposure to PST-producing dinofagellates
Jiarun Lou, Jie Cheng, Xiaogang Xun, Xu Li, Moli Li, Xiangchao Zhang, Tingting Li, Zhenmin Bao, Xiaoli Hu
2020, 2(3): 252-261. doi: 10.1007/s42995-020-00050-2
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Abstract:
The glutathione S-transferases (GSTs) are a superfamily of enzymes that function in cellular protection against toxic substances and oxidative stress. Bivalves could accumulate high concentration of paralytic shellfish toxins (PSTs) from harmful algae. To understand the possible involvement of GSTs in protecting bivalves during PST accumulation and metabolism,the GST genes were systemically analyzed in two cultured scallops,Azumapecten farreri and Mizuhopecten yessoensis,which were reported for PST deposition during harmful algae bloom. A total of 35 and 37 GSTs were identified in A. farreri (AfGSTs) and M. yessoensis (MyGSTs) genome,respectively,and the expansion of the sigma class from the cytosolic subfamily was observed. In both scallop species,sigma class GSTs showed higher expression than other members. The high GSTs expression was detected mainly during/after larvae stages and in the two most toxic organs,hepatopancreas and kidney. After ingesting PST-producing dinoflagellates,all the regulated AfGSTs in the hepatopancreas were from the sigma class,but with opposite regulation pattern between Alexandrium catenella and A. minutum exposure. In scallop kidneys,where PSTs transformed into higher toxicity,more AfGSTs were regulated than in the hepatopancreas,and most of them were from the sigma class,with similar regulation pattern between A. catenella and A. minutum exposure. In M. yessoensis exposed to A. catenella,MyGST-σ2 was the only up-regulated MyGST in both hepatopancreas and kidney. Our results suggested the possible diverse function of scallop GSTs and the importance of sigma class in the defense against PSTs,which would contribute to the adaptive evolution of scallops in marine environments.
p-Terphenyl alcohols from a marine sponge-derived fungus, Aspergillus candidus OUCMDZ-1051
Dongyang Wang, Peng Qu, Jiayu Zhou, Yi Wang, Liping Wang, Weiming Zhu
2020, 2(3): 262-267. doi: 10.1007/s42995-020-00039-x
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Abstract:
In order to discover structurally new and bioactive compounds from marine life,we studied the secondary metabolites of the marine-derived fungi associated with a marine sponge (XS-3) from the Xisha islands. As a result,4-O-methylcandidusin A (1),a new p-terphenyl alcohol,along with nine known analogs (2-10),were isolated and identified from the marine sponge-derived fungus Aspergillus candidus OUCMDZ-1051. The structures of these compounds were determined by analyzing spectroscopic data,especially 1D and 2D NMR. The new compound 1 selectively inhibited the growth of the MDA-MB-468,BT474 and A431 human cancer cell lines with the IC50 values of 1.84,6.05 and 0.98 μmol/L,respectively. Compound 1 also displayed a selective antimicrobial activity against Escherichia coli with an MIC value of 27.3 μmol/L. The results indicated 4-O-methylcandidusin A (1) as a potential lead in the new drug discovery for triple negative breast cancer,invasive ductal breast cancer and epidermoid cancer. The antimicrobial metabolites also evidenced a clue for chemical defense of sponges by their associated microorganisms.
Successive digestion of tilapia collagen by serine proteinase and proline specifc endopeptidase to produce novel angiotensin I-converting enzyme inhibitory peptides
Xin Hua, Lechang Sun, Chan Zhong, Qiang Wu, Panpan Xiao, Asami Yoshida, Guangming Liu, Minjie Cao
2020, 2(3): 268-278. doi: 10.1007/s42995-020-00038-y
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Abstract:
Serine proteinase, purified from the hepatopancreas of Pacific white shrimp (Litopenaeus vannamei), was used to hydrolyze acid solubilized collagen (ASC) isolated from Nile tilapia (Oreochromis sp.) skin to produce angiotensin I-converting enzyme (ACE) inhibitory peptides (ACEIPs). A series of column chromatography assays were used to separate the ACEIPs. A peptide, NPARTCR, was isolated as it exhibited high ACE inhibition potential. Further digestion of this peptide by a proline specific endopeptidase (PSEP), produced a pentapeptide ARTCR with ACE inhibitory activity (IC50) of 77.0 μmol/L. Both NPARTCR and ARTCR inhibited ACE in a non-competitive manner. An in vivo study in rats demonstrated that ARTCR has ACE inhibitory activity via lowering systolic blood pressure in spontaneously hypertensive rats (SHRs). These results suggest that processing by-products from shrimp and tilapia are ideal raw materials for the production of serine proteinase and collagen, respectively. Serine proteinase and collagen are both ideal raw materials that can be used to derive ACE inhibitory active peptides against hypertension.
Heterologous expression and cell membrane localization of dinoflagellate opsins (rhodopsin proteins) in mammalian cells
Minglei Ma, Xinguo Shi, Senjie Lin
2020, 2(3): 302-308. doi: 10.1007/s42995-020-00043-1
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Abstract:
Rhodopsins are now found in all domains of life,and are classified into two large groups: type II,found in animals and type I found in microbes including Bacteria,Archaea,and Eukarya. While type II rhodopsin functions in many photodependent signaling processes including vision,type I among others contains rhodopsins that function as a light-driven proton pump to convert light into ATP as in proteobacteria (named proteorhodopsin). Proteorhodopsin homologs have been documented in dinoflagellates,but their subcellular localizations and functions are still poorly understood. Even though sequence analyses suggest that it is a membrane protein,experimental evidence that dinoflagellate rhodopsins are localized on the plasma membrane or endomembranes is still lacking. As no robust dinoflagellate gene transformation tool was available,we used HEK 293T cells to construct a mammalian expression system for two dinoflagellate rhodopsin genes. The success of expressing these genes in the system shows that this mammalian cell type is suitable for expressing dinoflagellate genes. Immunofluorescence of the expressed protein locates these dinoflagellate rhodopsins on the cell membrane. This result indicates that the protein codons and membrane targeting signal of the dinoflagellate genes are compatible with the mammalian cells,and the proteins' subcellular localization is consistent with proton pump rhodopsins.