Expression dynamics of solute carrier family 15 member 4 (SLC15A4) and its potential regulatory role in ovarian development of the Indian white shrimp, Penaeus indicus

Oligopeptide/Histidine Transporter PHT1 and PHT2 - Function, Regulation, and Pathophysiological Implications Specifically in Immunoregulation

The oligopeptide/histidine transporters PHT1 and PHT2, two mammalian solute carrier family 15A proteins, mediate the transmembrane transport of histidine and some di/tripeptides via proton gradient. PHT1 and PHT2 are distributed in a variety of tissues but are preferentially expressed in immune cells and localize to the lysosome-related organelles. Studies have reported the relationships between PHT1/PHT2 and immune diseases. PHT1 and PHT2 participate in the regulation of lysosomal homeostasis and lysosome-associated signaling pathways through their transport and nontransport functions, playing important roles in inflammatory diseases. In this review, we summarize recent research on PHT1 and PHT2, aiming to provide reference for their further biological research and as targets for drug design.

Structure and function analyses of the Mmd2 gene in pacific white shrimp Litopenaeus vannamei

Monocyte to macrophage differentiation factor 2 gene (Mmd2) encodes a member of the progestin and adipoQ receptor (PAQR) family, and plays a key role in growth and development. Our previous studies had found Mmd2 (Monocyte to macrophage differentiation factor 2) is a new candidate gene for growth traits in Pacific white shrimp (Litopenaeus vannamei). For the purpose of understanding the underlying mechanism of LvMmd2 affecting the growth of shrimp, we analyzed the gene structure, phylogeny, expression profiles and RNA interference of this gene in L. vannamei. We found the LvMmd2 gene sequence was highly conserved in transmembrane regions, it was widely expressed in different tissues, with the highest expression level in the eye stalk. Knockdown LvMmd2 could significantly promote body length and body weight gain, suggesting it is a growth suppressor. Through transcriptome analysis we identified 422 differentially expressed genes (DEGs) between the dsMmd2 group and control group, among which 337 genes were upregulated in the dsMmd2 group, including numerous muscle-related genes and protein synthesis genes. Further bioinformatics analysis showed that growth, metabolism, and immune-related signal pathway had changed significantly. The above results greatly increase our understanding on the conservative structure and function of LvMmd2 gene, and provide potential application prospects in genetics and breeding.

Evidence from transcriptome analysis unravelled the roles of eyestalk in salinity adaptation in Pacific white shrimp (Litopenaeus vannamei)

Eyestalk is considered the main neuroendocrine organ in crustaceans. Eyestalk regulates reproduction, molting, and energy metabolism by secreting several neurohormones. However, the role of eyestalk in salinity adaptation in crustaceans remains unclear. To reveal the role of eyestalk in salinity adaptation in Litopenaeus vannamei, we performed RNA-seq to compare the transcriptomic response of the eyestalk under low salinity (salinity 3) with that of the control group (salinity 25) for 8 weeks. A total of 479 mRNAs, including 150 upregulated and 329 downregulated mRNAs, were differentially expressed between the two salinity groups. The majority of the differentially expressed genes (DEGs) were enriched in biological pathways related to osmoregulation, metabolism and energy production, and oxidative stress. The most important DEGs associated with osmoregulation were CA4, ATP1A, ATP2B, ABCB1, ABCC4, PhoA, PhoB, NOS1, ACE, ANPEP, and the V-type H⁺-ATPase E-subunit. The metabolism-related DEGs were divided into three main categories: carbohydrate and energy metabolism (i.e., G6PC, UGT), protein and amino acid metabolism (i.e., SLC15A1, AhcY, GFAT), and lipid and fatty acid metabolism (i.e., GPAT3_4, CYP2J). The key DEGs related to the oxidative stress response were UGT, NDUFB1, QCR7, QCR8, P5CDh, COX6B, and CES1. These results provide evidence for the existence of an eyestalk-salinity adaptation-stress endocrine axis in L. vannamei. These findings provide a better understanding of the molecular mechanism underlying salinity adaptation in L. vannamei.

Molecular Characterization and RNA Interference Analysis of SLC26A10 From Nilaparvata lugens (Stål)

SLC26A10 is a member of the SLC26 gene family, but its role in insects is still unclear. We cloned the SLC26A10 gene of Nilaparvata lugens (NlSLC26A10) and found NlSLC26A10 contained 11 transmembrane regions and a STAS domain. Expression pattern analysis showed NlSLC26A10 expression was more upregulated in adults than in nymphs, highest in the ovary. After injection of double-stranded RNA (dsRNA) of NlSLC26A10, the mRNA level of NlSLC26A10 significantly decreased and, consequently, the ovarian development of adult females was hindered; the amount and the hatchability of eggs and yeast-like symbionts in mature oocytes decreased. Further study showed that NlSLC26A10 might result in decreased juvenile hormone level and vitellogenin expression. These results indicate that NlSLC26A10 plays an essential role in the reproduction of N. lugens.