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The genus Shewanella comprises a group of marine-dwelling species with worldwide distribution. Several species are regarded as causative agents of food spoilage and opportunistic pathogens of human diseases. In this study, a standard multilocus sequence analysis (MLSA) based on six protein-coding genes (gyrA, gyrB, infB, recN, rpoA, and topA) was established as a rapid and accurate identification tool in 59 Shewanella type strains. This method yielded sufficient resolving power in regard to enough informative sites, adequate sequence divergences, and distinct interspecies branches. The stability of phylogenetic topology was supported by high bootstrap values and concordance with different methods. The reliability of the MLSA scheme was further validated by identical phylogenies and high correlations of genomes. The MLSA approach provided a robust system to exhibit evolutionary relationships in the Shewanella genus. The split network tree proposed twelve distinct monophyletic clades with identical GϩC contents and high genetic similarities. A total of 86 tested strains were investigated to explore the population biology of the Shewanella genus in China. The most prevalent Shewanella species was Shewanella algae, followed by Shewanella xiamenensis, Shewanella chilikensis, Shewanella indica, Shewanella seohaensis, and Shewanella carassii. The strains frequently isolated from clinical and food samples highlighted the importance of increasing the surveillance of Shewanella species. Based on the combined genetic, genomic, and phenotypic analyses, Shewanella upenei should be considered a synonym of S. algae, and Shewanella pacifica should be reclassified as a synonym of Shewanella japonica. IMPORTANCE The MLSA scheme based on six housekeeping genes (HKGs) (gyrA, gyrB, infB, recN, rpoA, and topA) is well established as a reliable tool for taxonomic, evolutionary, and population diversity analyses of the genus Shewanella in this study. The standard MLSA method allows researchers to make rapid, economical, and precise identification of Shewanella strains. The robust phylogenetic network of MLSA provides profound insight into the evolutionary structure of the genus Shewanella. The population genetics of Shewanella species determined by the MLSA approach plays a pivotal role in clinical diagnosis and routine monitoring. Further stud-2019. Multilocus sequence analysis, a rapid and accurate tool for taxonomic classification, evolutionary relationship determination, and population biology studies of the genus Shewanella. Appl Environ Microbiol 85:e03126-18. https://doi. Downloaded fromies on remaining species and genomic analysis will enhance a more comprehensive understanding of the microbial systematics, phylogenetic relationships, and ecological status of the genus Shewanella.

22The genus Shewanella comprises a group of marine-dwelling species with worldwide 23 distribution. Several species are regarded as causative agents of food spoilage and 24 opportunistic pathogens of human diseases. In this study, a standard multilocus 25 sequence analysis (MLSA) based on six protein-coding genes (gyrA, gyrB, infB, recN, 26 rpoA and topA) was established as a rapid and accurate identification tool in fifty-nine 27 The nucleotide sequences of six HKGs are deposited in GenBank nucleotide sequence database under accession numbers of gyrA: MH090144-MH090185; gyrB: MH090186-MH090202; infB: MH090203-MH090244; recN: MH090245-MH090286; rpoA: MH090287-MH090328; and topA: MH090329-MH090370. 2 type Shewanella strains. This method yielded sufficient resolving power in regard to 28 enough informative sites, adequate sequence divergences and distinct interspecies 29 branches. The stability of phylogenetic topology was supported by high bootstrap 30 values and concordance with different methods. The reliability of the MLSA scheme 31 was further validated by identical phylogenies and high correlations of genomes. The 32 MLSA approach provided a robust system to exhibit evolutionary relationships in the 33 Shewanella genus. The split network tree proposed twelve distinct monophyletic 34 clades with identical G+C contents and high genetic similarities. Eighty-six tested 35 strains were investigated to explore the population biology of the Shewanella genus in 36 China. The most prevalent Shewanella species were Shewanella algae, Shewanella 37 xiamenensis, Shewanella chilikensis, Shewanella indica, Shewanella seohaensis and 38 Shewanella carassii. The strains frequently isolated from clinical and food samples 39 highlighted the importance of increasing the surveillance of Shewanella species. 40 Combined with the genetic, genomic and phenotypic analyses, Shewanella upenei 41 should be considered a synonym of S. algae, and Shewanella pacifica should be 42 reclassified as a synonym of Shewanella japonica. 43 IMPORTANCE 44 The MLSA scheme based on six HKGs (gyrA, gyrB, infB, recN, rpoA and topA) is 45 well established as a reliable tool for taxonomic, evolutionary and epidemiological 46 analyses of the genus Shewanella in this study. The standard MLSA method allows 47 48 The robust phylogenetic network of MLSA provides profound insight into the 49 evolutionary structure of the genus Shewanella. The population genetics of 50 Shewanella species determined by the MLSA approach plays a pivotal role in clinical 51 diagnosis and routine monitoring. Further studies on remaining species and genomic 52 analysis will enhance a more comprehensive understanding of the microbial 53 systematics, phylogenetic relationships and ecological status of the genus Shewanella.54

The unique body morphology and specialized life history traits make seahorses excellent flagship species for many issues in marine conservation and biological evolution. In this study, the complete mitochondrial genome of Hippocampus fuscus was determined. Phylogenetic analyses showed that H. fuscus had a close genetic relationship to Hippocampus reidi, which give us a new insight into the speciation and dispersal among seahorse genus. A total of 843 base pairs of cytochrome b (Cytb) gene and a 646 base pairs of cytochrome oxidase I (COI) gene were obtained from 36 H. fuscus and 26 H. reidi from three populations. Population genetic analysis revealed a relatively high genetic diversity across the populations of H. fuscus compared with H. reidi. Neighbour-joining (NJ) tree of COI and Cytb gene sequences showed that H. fuscus haplotypes formed one cluster. The result of median-joining network of haplotypes based on COI and Cytb indicated a lack of structure in populations of H. fuscus. This study addressed the information about the evolution history and genetic structure of an Arabian seahorse H. fuscus, which provides insight into the genetic conservation and sustainable management for this species.

The transfer, from soil to Chinese cabbage and spinach, of radioactive strontium-90 released as a result of accidents in nuclear power stations was studied using a stable isotope of strontium, namely nuclide strontium-88 (88Sr). The study led to an experimental model for assessing the hazard of radionuclide strontium-90 (90Sr) entering the food chain and for predicting the risk to food safety. Chinese cabbage and spinach were grown in pots in a greenhouse and irrigated with deionized water containing known quantities of strontium. Based on the strontium content of that water, the plants were divided into five groups (treatments) and strontium content of the soil, and 30-day-old plants were determined by inductively coupled plasma atomic emission spectroscopy instrument (ICP-AES). Data on the strontium content of soil and plants enabled the development of a model using MATLAB, a mathematical software package, which included curve fitting and problem solving using regression equations and differential equations. Although strontium curves for leaves, stems, and roots of Chinese cabbage were not exactly the same, all showed a non-linear increase when compared with the increase in the content of strontium in soil. Strontium curves for leaves, stems, and roots of spinach were very similar and showed an initial increase followed by a decrease. Strontium concentrations in both Chinese cabbage and spinach were initially related to the concentrations of sodium and sulfur, the next two relevant nuclides being calcium and magnesium. The relationship between calcium and strontium in Chinese cabbage was different from that in spinach. By using 88Sr to simulate the transfer of radionuclide 90Sr from soil to a crop, the relevant data required to deal with accidental release of strontium can be obtained using a fitting curve and regression equations, thereby providing some experimental basis for evaluating the potential hazards posed by such accidents to the food chain.

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