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Temperature is a limiting factor in the growth of aquatic organisms and can directly affect many chemical and biological processes, including metabolic enzyme activity, aerobic respiration, and signal transduction. In this study, physiological, transcriptomic, and metabolomic analyses were performed to characterize the response of Litopenaeus vannamei to cold stress. We subjected L. vannamei to gradually decreasing temperatures (24 °C, 20 °C, 18 °C, 14 °C, and 12 °C) and studied the changes in the hepatopancreas. The results showed that extreme cold stress (12 °C) caused structural damage to the hepatopancreas of L. vannamei. However, shrimp exhibited response mechanisms to enhance cold tolerance, through regulating changes in key genes and metabolites in amino acid, lipid metabolism, and carbohydrate metabolism, including (a) increased level of methylation in cells to enhance cold tolerance; (b) increased content of critical amino acids, such as proline, alanine, glutamic acid and taurine, to ameliorate energy metabolism, protect cells from cold-induced osmotic imbalance, and promote ion transport and DNA repair; (c) accumulation of unsaturated fatty acids to improve cell membrane fluidity; and (d) regulation of the metabolic pattern shift to rely on anaerobic metabolism with a gradual decrease in aerobic metabolism and enhance glycolysis to produce enough ATP to maintain energy metabolic balance. When the temperature dropped further, cold stress impaired antioxidant and immune defense responses in shrimp. This study provides an integrated analysis of the physiology, transcriptome, and metabolome of L. vannamei in response to cold stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

The activity of a gene newly integrated into a chromosome depends on the genomic context of the integration site. This "position effect" has been widely reported, although the other side of the coin, that is, how integration affects the local chromosomal environment, has remained largely unexplored, as have the mechanism and phenotypic consequences of this "externality" of the position effect. Here, we examined the transcriptome profiles of approximately 250 Saccharomyces cerevisiae strains, each with GFP integrated into a different locus of the wild-type strain. We found that in genomic regions enriched in essential genes, GFP expression tended to be lower, and the genes near the integration site tended to show greater expression reduction. Further joint analysis with public genome-wide histone modification profiles indicated that this effect was associated with H3K4me2. More importantly, we found that changes in the expression of neighboring genes, but not GFP expression, significantly altered the cellular growth rate. As a result, genomic loci that showed high GFP expression immediately after integration were associated with growth disadvantages caused by elevated expression of neighboring genes, ultimately leading to a low total yield of GFP in the long run. Our results were consistent with competition for transcriptional resources among neighboring genes and revealed a previously unappreciated facet of position effects. This study highlights the impact of position effects on the fate of exogenous gene integration and has significant implications for biological engineering and the pathology of viral integration into the host genome., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

Temperature is an important factor in the physiological processes of aquatic organisms and can seriously affect several chemical and biological processes in their bodies, including respiratory metabolism, antioxidant capacity, immune capacity, and signal transduction. In this study, physiological, transcriptomic, and metabolomic analyses were used to investigate the response of Penaeus vannamei to cold stress. The results indicated that cold stress disrupted nucleotide metabolism and inhibited gluconeogenesis. However, shrimp exhibited response mechanisms in order to enhance cold tolerance, regulating changes in key genes and metabolites in amino acid and lipid metabolism to increase energy supply and protect cell membrane stability. In addition, the response included regulating Ca2+ pumps and ion channels to maintain intracellular ion homeostasis and osmotic balance. When the temperature dropped further, oxidative damage occurred due to overwhelming of the antioxidant defense system, and immune function was inhibited. This research provides some references regarding the molecular mechanisms involved in responding to cold stress and potential strategies to improve cold tolerance in P. vannamei; these are important references for studying the cold stress response of shrimp. [ABSTRACT FROM AUTHOR]

• Transcriptome analysis of P. gravieri under salinity stress was firstly performed. • DEGs in hepatopancreas and gills of P. gravieri under different salinity stresses were firstly compared. • Transporters mainly played a role in the gills, but ABC transporters were more active in the hepatopancreas. • The response of P. gravieri to salinity change was different not only between the hepatopancreas and gills, but also between low and higher salinity. Salinity is an important factor in the aquatic environment, and its fluctuations always result in osmotic stress, which affects the survival, distribution, and physiological activities of crustaceans. Crustaceans counter them through osmoregulation, which consists of many mechanisms. Palaemon gravieri is an important economic species in Palaemonidae, widely distributed in the southern East China Sea and the China Yellow Sea, and has a good adaptability to salinity stress. Currently, there are only a few studies on the effects of salinity on P. graviera. Therefore, it is particularly important to study the molecular responses of P. gravieri to salinity fluctuations. In this study, P. gravieri was treated with salinities of 10, 25, and 40, and the hepatopancreas and gills of shrimp in the different salinity groups were sampled after 24 h. The samples were used for RNA extraction and transcriptome analysis. In total, 80,994 unigenes were obtained, of which 19,114 were annotated. The differences in gene expression between different tissues at the same salinity were more significant. Many metabolism-related genes were downregulated in the gills, such as beta-hexosaminidase subunit alpha (HEXA), 10-formyltetrahydrofolate dehydrogenase (ALDH1L1), and Alcohol dehydrogenase class-3 (ADH5). Scanning transmission electron microscope analysis showed that the expression levels of some stress-(but not salinity stress) related genes changed after stress (mostly upregulated), suggesting the existence of secondary stress. Gene set enrichment analysis (GSEA) focused on the expression of transporters in osmoregulation, and the results showed that they mainly played a role in the gills, but ATP-binding cassette (ABC) transporters were more active in the hepatopancreas. This study showed that the response of P. gravieri to salinity change was different not only between the hepatopancreas and gills, but also between low salinity and higher salinity, and the ion transport-related genes were mainly expressed in the gills. Overall, these results improve our understanding of salt tolerance mechanism in P. gravieri. [ABSTRACT FROM AUTHOR]

Temperature is an important variable factor in aquaculture which affects the health, survival, behavior, growth, and development of aquatic animals. Palaemon gravieri is one of the main economic shrimps in marine capture fisheries of the East China Sea and the South China Yellow Sea; however, it cannot tolerate high temperatures, thereby, resulting in unsuccessful large-scale farming. Thus far, there are few studies on the effects of acute high temperature on P. graviera. Therefore, it is especially important to study the effects of temperature fluctuations, especially acute high temperature, on P. gravieri. In this study, P. gravieri was treated with acute high-temperature stress, which gradually rose from 15 °C to 30 °C in 3 h, then remained at 30 °C for 12 h. The hepatopancreas of shrimps from five time points was collected once at 15 °C and thereafter, every 3 h after 30 °C. The samples of G0, G1, and G4 were selected for transcriptome analysis. A total of 18,308 unigenes were annotated, of which 7744 were differentially expressed. Most differentially expressed genes (DEGs) come from several physiological and biochemical processes, such as metabolism (GRHPR, ALDH5A1, GDH), immunity (HSP70, Rab5B, Rab10, CASP7), and stress-related process (UGT, GST, HSP60, HSP90). The results indicated that acute high temperature significantly reduced the metabolic capacity of shrimp but enhanced the immune capacity, which seemed to be an emergency metabolic compensation technique to resist stress. This study contributes to ongoing research on the physiological mechanism of P. gravieri response to acute high temperature. [Display omitted] • Transcriptome sequencing and analysis of P. gravieri was firstly performed. • DEGs of P. gravieri at different time points after high temperature stress were firstly compared. • The number of DEGs cumulative increased with prolonging the thermal treatment time. • The temporal expression patterns of DEGs were analyzed by STEM. • High temperature caused the inhibition of metabolism, while immune was enhanced. [ABSTRACT FROM AUTHOR]

• This analysis revealed 137 differentially expressed genes, with 84 up-regulated and 53 down-regulated genes. • The genes such as Invasin, AsnA, MCM8, MCM2 and MOT1 were down-regulated, while the genes such as RPL27a, RPS16 and Ksh1 were up-regulated. • The EHP spores could be germinated with H 2 O 2 germination solution for 20 minin vitro treatment. Enterocytozoon hepatopenaei (EHP), an obligate intracellular parasite classified as microsporidia, is an emerging pathogen with a significant impact on the global shrimp aquaculture industry. The understanding of how microsporidia germinate has been a key factor in exploring its infection process. However, the germination process of EHP was rarely reported. To gain insight into the germination process, we conducted a high-throughput sequencing analysis of purified EHP spores that had undergone in vitro germination treatment. This analysis revealed 137 differentially expressed genes, with 84 up-regulated and 53 down-regulated genes. While the functions of some of the genes remain unknown, this study provides important data on the transcriptomic changes before and after EHP germination, which can aid in further studies on the EHP infection mechanism. [ABSTRACT FROM AUTHOR]