Project description:Transcriptional profiling of different clam tissues (hemolymph and mantle) in response to QPX disease and temperautre Quahog Parasite Unknown (QPX) is a fatal protistan parasite that causes severe losses in the hard clam (Mercenaria mercenaria) fisheries along the northeastern coast of the US. Field and laboratory studies of QPX disease have demonstrated a major role for water temperature and M. mercenaria genetic origin in disease development. Infections are more likely to occur at cold temperatures, with clam stocks originating from southern states being more susceptible than clams from northern origin where disease is enzootic. Even though the influence of temperature on QPX infection have been examined in susceptible and resistant M. mercenaria at physiological and cellular scales, the underlying molecular mechanisms associated with host-pathogen interactions remain largely unknown. This study was carried out to explore the molecular changes in M. mercenaria in response to temperature and QPX infection on the transcriptomic level, and also to compare molecular responses between susceptible and resistant clam stocks. A M. mercenaria oligoarray (15K Agilent) platform was produced based on our previously generated transcriptomic data and was used to compare gene expression profiles in naive and QPX-infected susceptible (Florida stock) and resistant (Massachusetts) clams maintained at temperatures favoring disease development (13 °C) or clam healing (21 °C). In addition, transcriptomic changes reflecting focal (the site of infection, mantle) and systemic (circulating hemocytes) responses were also assessed using the oligoarray platform. Results revealed significant regulation of multiple biological pathways by temperature and QPX infection, mainly associated with immune recognition, microbial killing, protein synthesis, oxidative protection and metabolism. Alterations were widely systemic with most changes in gene expression revealed in hemocytes, highlighting the role of circulating hemocytes as the first line of defense against pathogenic stress. A large number of complement-related recognition molecules with fibrinogen or C1q domains were shown to be specially induced following QPX challenge, and the expression of these molecules was significantly higher in resistant clams as compared to susceptible ones. These highly variable immune proteins may be potent candidate molecular markers for future study of M. mercenaria resistance against QPX. Beyond the specific case of clam response to QPX, this study also provides insights into the primitive complement-like system in the hard clam. Three-condition interaction experiment (Temperature x clam/infection type x tissue type), 2 temperatures, 3 clam/infection types, 2 tissues, 3 biological replicates for each condition
Project description:Transcriptional profiling of different clam tissues (hemolymph and mantle) in response to QPX disease and temperautre Quahog Parasite Unknown (QPX) is a fatal protistan parasite that causes severe losses in the hard clam (Mercenaria mercenaria) fisheries along the northeastern coast of the US. Field and laboratory studies of QPX disease have demonstrated a major role for water temperature and M. mercenaria genetic origin in disease development. Infections are more likely to occur at cold temperatures, with clam stocks originating from southern states being more susceptible than clams from northern origin where disease is enzootic. Even though the influence of temperature on QPX infection have been examined in susceptible and resistant M. mercenaria at physiological and cellular scales, the underlying molecular mechanisms associated with host-pathogen interactions remain largely unknown. This study was carried out to explore the molecular changes in M. mercenaria in response to temperature and QPX infection on the transcriptomic level, and also to compare molecular responses between susceptible and resistant clam stocks. A M. mercenaria oligoarray (15K Agilent) platform was produced based on our previously generated transcriptomic data and was used to compare gene expression profiles in naive and QPX-infected susceptible (Florida stock) and resistant (Massachusetts) clams maintained at temperatures favoring disease development (13 °C) or clam healing (21 °C). In addition, transcriptomic changes reflecting focal (the site of infection, mantle) and systemic (circulating hemocytes) responses were also assessed using the oligoarray platform. Results revealed significant regulation of multiple biological pathways by temperature and QPX infection, mainly associated with immune recognition, microbial killing, protein synthesis, oxidative protection and metabolism. Alterations were widely systemic with most changes in gene expression revealed in hemocytes, highlighting the role of circulating hemocytes as the first line of defense against pathogenic stress. A large number of complement-related recognition molecules with fibrinogen or C1q domains were shown to be specially induced following QPX challenge, and the expression of these molecules was significantly higher in resistant clams as compared to susceptible ones. These highly variable immune proteins may be potent candidate molecular markers for future study of M. mercenaria resistance against QPX. Beyond the specific case of clam response to QPX, this study also provides insights into the primitive complement-like system in the hard clam.
Project description:This study aimed to establish a genome-wide association for heat tolerance using the newly developed 66K SNP array for Mercenaria mercenaria. Northern quahogs from three local farms were combined for a heat challenge by increasing temperature at 1°C per day from 24°C to 35°C (Phase I), maintaining at 35°C for two days before decreasing to 27°C within the next 24 hr, then to 24°C within 24 hr. Survival-time analysis showed different survivals among quahogs from these three farms during the heat challenge. Mortality during the temperature increase period (Phase I) was 38, 46, and 55%, and after the temperature decrease was 36, 30, and 29%. For the survivors, no changes were found in body weight before and after the heat shock challenges (p < 0.265). The PCA analyses of SNP frequencies indicated significant genetic differences associated with clam survival under heat stress across the different farms. The fastStructure analysis also revealed the proportions of different ancestral components within the clams, highlighting the genetic factors that may contribute to their varying survival rates under heat stress. The heritability of the heat tolerance traits was 0.680 ± 0.063. GWAS analysis indicated that one SNP exhibited a significant association with the time-to-death trait of northern quahogs and was in chromosome 7. More significant SNPs (p < 10-3.5) were inside genes that have been reported to function in heat tolerance such as serine/threonine-protein kinase 31 and carbohydrate sulfotransferase 11, and some genes found within 50K bp far from SNP sites have a relationship with heat tolerance such as toll-like receptors 4 and 6 (TLRs 4 and TLRs 6), uracil-DNA glycosylase, and a disintegrin and metalloproteinase with thrombospondin motifs gon-1 (ADAMTs). Overall, these findings highlight the power of high-throughput approaches for the identification of superior clam genotypes for further breeding.
Project description:Prochlorococcus is an obligate marine microorganism which are dominant autotroph in tropical and subtropical central oceans. However, what is the low salinity boundary and how Prochlorococcus would response to low salinity exposure is still unknown. In this study, we first tested the growing salinity range of two Prochlorococcus strains, NATL1A and MED4, and then compared the global transcriptome of their low salinity acclimated cells and cells growing in normal seawater salinity. We found that MED4 could be acclimated in the lowest salinity of 25% and NATL1A could be acclimated in the lowest salinity of 28%. Measurement of the effective quantum yield of PSII photochemistry (Fv/Fm) indicated that both strains were stressed when growing in salinity lower than 34%. The transcriptomic response of NATL1A and MED4 were approximately different, with much more genes having changed transcript abundance in NATL1A than in MED4. To cope with low salinity, NATL1A downregulated the transcript of most genes involved in translation, ribosomal structure and biogenesis, while MED4 upregulated those genes. Moreover, low salinity acclimated NATL1A cells suppressed ATP-producing genes and induced the expression of photosynthesis related genes, while low salinity acclimated MED4 upregulated ATP-producing genes and downregulated photosynthesis related genes. These results indicate that the response to low salinity stress of different Prochlorococcus strains could be distinct. The study provided the first glimpse into the growing salinity range of Prochlorococcus cells and their global gene expression changes due to low salinity stress.
Project description:Sea cucumber, Apostichopus japonicus is a very important species for aquaculture, and its behavior and physiology can respond to the initial change in salinity. It is important to understand the molecular responses of A. japonicus when exposed to ambient changes in salinity In this study, RNA-seq provided a general overview of the gene expression profiles of the intestine of A. japonicus exposed to high salinity (SD40), normal salinity (SD30) and low salinity (SD20) environment.
Project description:Most type 1 diabets (T1D) associated SNPs are located in non-coding regions, making it hard to understand their functional impact. We performed epigenomic profiling of two enhancer marks, H3K4me1 and H3K27ac, using primary TH1 and TREG cells from healthy and T1D subjects. By integrating enhancers predicted using these ChIP-Seq data, T1D associated SNPs and additional supporting data, we found and validated several novel risk SNPs for T1D.