Just Accepted

Articles just accepted or in press have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).
RESEARCH PAPER
Identification, expression analysis, and functional characterization of ghrelin and its receptors in spotted sea bass (Lateolabrax maculatus)
Peng Yu, Yangyang Zhou, Xin Qi, Hongying Fan, Kaiqiang Zhang, Xiaoyan Zhang, Yun Li, Haishen Wen
, Available online  , doi: 10.1007/s42995-020-00055-x
Abstract(29) PDF Springerlink
Abstract:
Ghrelin (Ghrl), an appetite-inducing peptide hormone secreted by the stomach, is the endogenous ligand for the growth hormone secretagogue receptor (Ghs-r). In this study, we identified the preproghrelin gene and its receptors in spotted sea bass (Lateolabrax maculatus). The ghrl gene consisted of an open reading frame (ORF) of 324 nucleotides encoding 107 amino acids, and the premature protein contained a 20-amino-acid mature peptide. Through a syntenic analysis, we also validated the annotation of growth hormone secretagogue receptor 1a (ghs-r1a) and growth hormone secretagogue receptor 1a-like (ghs-r1a-like), which contained seven-transmembrane structures, in spotted sea bass. The ORF of ghs-r1a consisted of 1152 bp that encoded a 383-amino-acid protein, and ghs-r1a-like contained an ORF of 2631 bp and produced a protein with 876 amino acids. A phylogenetic analysis showed that spotted sea bass ghrl and its receptors clustered with those of other ishes and were more distantly related to those of other vertebrates. In situ hybridization revealed that ghrl was highly expressed in the stomach and localized in the mucosa and submucosa. The expression of these genes varied during short-term starvation in a time-dependent manner. In vitro studies showed that after incubation with Ghrl for 3 h enhanced the expression of motilin (mln), gastrin (gas) and cholecystokinin (cck), but this effect vanished after 6 h of incubation. In summary, Ghrl and its receptors might play important roles in the regulation of food intake in spotted sea bass.
Characterization of TEMPO-oxidized chitin nanofibers with various oxidation times and its application as an enzyme immobilization support
Rui Chen, Wen-Can Huang, Wei Wang, Xiangzhao Mao
, Available online  , doi: 10.1007/s42995-020-00054-y
Abstract(22) PDF Springerlink
Abstract:
Chitin nanofibers have recently received increased attention and are considered to be a promising material for a wide range of applications because of their excellent characteristics. In this study, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized chitin nanofibers (CNFs) with various oxidation times were prepared and characterized. CNFs with different oxidation times were then utilized for enzyme immobilization, using chymotrypsin as a model enzyme. The effects of oxidation time on enzyme immobilization were explored. Results showed characteristics of chitin nanofibers can be controlled by adjusting oxidation time. CNFs treated with TEMPO for 360 min showed the lowest crystallinity (79.13 ± 1.43%), the shortest length (241.70 ± 74.61 nm), the largest width (12.67 ± 3.43 nm), and the highest transmittance (73.01% at 800 nm). The activity of immobilized enzymes and enzyme loading showed good correlation to the carboxylate content of CNFs. The enzyme eiciency based on CNFs and the content of carboxylate groups peaked at the oxidization time of 60 min. When the additional amount of chymotrypsins (CTs) was 500 or 2000 mg/g carrier, the highest loading amount of CTs was 307.17 ± 4.08 or 726.82 ± 12.05 mg/g carrier, respectively.
REVIEW
Strategies for culturing active/dormant marine microbes
Da-Shuai Mu, Yang Ouyang, Guan-Jun Chen, Zong-Jun Du
, Available online  , doi: 10.1007/s42995-020-00053-z
Abstract(26) PDF Springerlink
Abstract:
Microorganisms are ubiquitous in the ocean environment and they play key roles in marine ecosystem function and service. However, many of their functions and phenotypes remain unknown because indigenous marine bacteria are mostly diicult to culture. Although many novel techniques have brought previously uncultured microbes into laboratory culture, there are still many most-wanted or key players that need to be cultured from marine environments. This review discusses possible reasons for ‘unculturable microbes’ and categorizes uncultured bacteria into three groups: dominant active bacteria, rare active bacteria, and dormant bacteria. This review also summarizes advances in cultivation techniques for culturing each group of unculturable bacteria. Simulating the natural environment is an effective strategy for isolating dominant active bacteria, whereas culturomics and enrichment culture methods are proposed for isolating rare active bacteria. For dormant bacteria, resuscitation culture is an appropriate strategy. Furthermore, the review provides a list of the most-wanted bacteria and proposes potential strategies for culturing these bacteria in marine environments. The review provides new insight into the development of strategies for the cultivation of speciic groups of uncultured bacteria and therefore paves the way for the detection of novel microbes and their functions in marine ecosystems.
Roles of dietary taurine in fish nutrition
W. W. H. A. Sampath, R. M. D. S. Rathnayake, Mengxi Yang, Wenbing Zhang, Kangsen Mai
, Available online  , doi: 10.1007/s42995-020-00051-1
Abstract(88) PDF Springerlink
Abstract:
Taurine is a conditionally essential amino acid in fish nutrition.The present study addressed the practical application of examining published data on fish nutrition over the past 20 years,emphasizing the topic of taurine by using computational tools and their applications.According to the published articles,an increased linear growth of research occurred,with Japanese flounder being the most examined fish species.Dietary taurine supplementation has several beneficial effects in fish nutrition, such as survival,growth,feed utilization,protein and energy retention,intermediate metabolism,anti-oxidation,anti-stress, disease resistance,muscle texture and reproductive performance.Also,there are negative effects in some species.Dietary taurine exerted effects on several gene expressions and enzyme activities;these are important in taurine metabolism in fish. These genes and enzymes included taurine transporter (TauT),cysteine dioxygenase (CDO),cysteamine dioxygenase (ADO), cysteine sulfonate decarboxylase (CSD) and pretrypsinogen (Ptry).Plant protein-based diets with taurine supplementation are recommended because of the absence of taurine in plant protein.
Optimal amounts of coconut oil in diets improve the growth, antioxidant capacity and lipid metabolism of large yellow croaker (Larimichthys crocea)
Tao Ding, Ning Xu, Yongtao Liu, Xueshan Li, Xiaojun Xiang, Dan Xu, Chuanwei Yao, Qiangde Liu, Zhaoyang Yin, Kangsen Mai, Qinghui Ai
, Available online  , doi: 10.1007/s42995-020-00045-z
Abstract(84) PDF Springerlink
Abstract:
The purpose of this study was to investigate the efect of diferent dietary coconut oil (CO) levels on growth, antioxidant capacity and lipid metabolism of juvenile large yellow croaker (Larimichthys crocea). Five iso-nitrogen (45% crude protein) and iso-lipid (13% crude lipid) experimental diets were prepared by replacing 0% (the control), 25%, 50%, 75% and 100% ish oil with coconut oil. The results showed that dietary CO had no signiicant efect on survival rate (SR, P > 0.05). However, the speciic growth rate was increased signiicantly when compared with the control group when ish were fed the diet with 50% CO (P < 0.05). The saturated fatty acids were increased signiicantly with increasing dietary CO in the liver and muscle, whereas the content of n-3 PUFA was decreased signiicantly (P < 0.05). The highest activities of glutathione peroxidase and superoxide dismutase in the liver were recorded in ish-fed diet with 50% CO; conversely, the content of malondialdehyde was signiicantly decreased (P < 0.05). The mRNA expression of peroxisome proliferator-activated receptor α, carnitine palmitoyl transferase 1 and acyl-CoA oxidase reached the highest levels in ish-fed diet with 50% CO. To some extent, this indicated that the rapid oxidation reaction of fatty acids to provide energy may be the reason for the rapid growth of large yellow croaker. In conclusion, ish-fed diet with 50% CO increased the growth rate and antioxidant capacity. Therefore, the timal replacement level of CO to FO in the diet should be 50%