Cloning and characterization of tyrosine decarboxylase (TDC) from Litopenaeus vannamei, and its roles in biogenic amines synthesis, immune regulation, and resistance to Vibrio alginolyticus by RNA interference

Investigation on 3D Printing of Shrimp Surimi Adding Three Edible Oils

Three-dimensional (3D) printing provides a new method for innovative processing of shrimp surimi. However, there still exists a problem of uneven discharge during the 3D printing of surimi. The effects of different amounts of lard oil (LO), soybean oil (SO), and olive oil (OO) (0%, 2%, 4%, and 6%, respectively) added to shrimp surimi on the 3D printability of surimi were evaluated. The findings showed that with the increase in the added oil, the rheological properties, texture properties, water-holding capacity (WHC), and water distribution of surimi with the same kind of oil were significantly improved; the printing accuracy first increased and then decreased; and the printing stability showed an increasing trend (p < 0.05). The surimi with 4% oil had the highest printing adaptability (accuracy and stability). Different kinds of oil have different degrees of impact on the physical properties of surimi, thereby improving 3D-printing adaptability. Among all kinds of oil, LO had the best printing adaptability. In addition, according to various indicators and principal component analysis, adding 4% LO to shrimp surimi gave the best 3D-printing adaptability. But from the aspects of 3D printing properties and nutrition, adding 4% SO was more in line with the nutritional needs of contemporary people.

Tyramine beta hydroxylase-mediated octopamine synthesis pathway in Litopenaeus vannamei under thermal, salinity, and Vibrio alginolyticus infection stress

Stress responses impact the immune systems, growth, and reproduction of aquatic organisms. Neuroendocrine regulation involving biogenic amines, including octopamine (OA), plays a pivotal role in maintaining physiological balance during stress. This study focuses on the synthesis pathway of OA, particularly the role of tyramine beta hydroxylase (TBH), in Litopenaeus vannamei under stress. TBH catalyzes the conversion of tyramine to OA, a process critical for physiological responses. The present study demonstrated LvTBH at the protein level under different stress conditions during acute (0.5, 1, 2 h) and chronic stress (24, 72, 168 h) periods. LvTBH increased in thoracic ganglia within 2 h under hyperthermal stress, accompanied by elevated OA levels. Conversely, LvTBH decreased in the brain and circumesophageal connective tissues during acute and chronic hypothermal stress. Additionally, LvTBH increased in the brain and circumesophageal connective tissues under acute infection stress, coinciding with elevated OA levels. These findings collectively contribute to a more intricate understanding of the neuroendocrine dynamics within L. vannamei under stress, underscoring the role of TBH in orchestrating responses crucial for adaptation.

Transcriptional and metabolomic investigation of the stress response in snow crab during simulated transport condition (Chionoecetes opilio)

The molecular mechanisms underlying the stress response are poorly described in crustaceans. This includes the snow crab (Chionoecetes opilio), a commercially important stenotherm species distributed throughout the northern hemisphere. A better understanding of the stress response in C. opilio is desperately needed for commercial and conservation purposes. The purpose of this study was to investigate the transcriptional and metabolomic response of C. opilio exposed to stressors. Crabs were randomly assigned to 24 or 72 h treatment groups where they were exposed to conditions simulating live transport (handling and air exposure). A control group was kept in cold (2 °C) and well‑oxygenated saltwater. The hepatopancreas of the crabs was sampled to perform RNA-sequencing and high-performance chemical isotope labeling metabolomics. Differential gene expression analyses showed that classic crustaceans' stress markers, such as crustacean hyperglycemic hormones and heat shock proteins, were overexpressed in response to stressors. Tyrosine decarboxylase was also up-regulated in stressed crabs, suggesting an implication of the catecholamines tyramine and octopamine in the stress response. Deregulated metabolites revealed that low oxygen was an important trigger in the stress response as intermediate metabolites of the tricarboxylic acid cycle (TCA) accumulated. Lactate, which accumulated unevenly between crabs could potentially be used to predict mortality. This study provides new information on how stressors affect crustaceans and provides a basis for the development of stress markers in C. opilio.

Tachykinin-related peptides modulate immune-gene expression in the mealworm beetle Tenebrio molitor L

Tachykinins (TKs) are a group of conserved neuropeptides. In insects, tachykinin-related peptides (TRPs) are important modulators of several functions such as nociception and lipid metabolism. Recently, it has become clear that TRPs also play a role in regulating the insect immune system. Here, we report a transcriptomic analysis of changes in the expression levels of immune-related genes in the storage pest Tenebrio molitor after treatment with Tenmo-TRP-7. We tested two concentrations (10^-8 and 10^-6 M) at two time points, 6 and 24 h post-injection. We found significant changes in the transcript levels of a wide spectrum of immune-related genes. Some changes were observed 6 h after the injection of Tenmo-TRP-7, especially in relation to its putative anti-apoptotic action. Interestingly, 24 h after the injection of 10^-8 M Tenmo-TRP-7, most changes were related to the regulation of the cellular response. Applying 10^-6 M Tenmo-TRP-7 resulted in the downregulation of genes associated with humoral responses. Injecting Tenmo-TRP-7 did not affect beetle survival but led to a reduction in haemolymph lysozyme-like antibacterial activity, consistent with the transcriptomic data. The results confirmed the immunomodulatory role of TRP and shed new light on the functional homology between TRPs and TKs.

Intestinal morphology and microflora to Vibrio alginolyticus in pacific white shrimp (Litopenaeus vannamei)

In recent years, the shrimp farming industry encountered significant economic losses induced by Vibrio alginolyticus. In this study, the influence of Vibrio alginolyticus on intestinal histomorphology and microbiome composition in Litopenaeus vannamei were studied. The results showed that the intestinal mucosal epithelial cells of Vibrio group (VA group) injected only with Vibrio alginolyticus showed large area exfoliation at 12 h, and the tissue morphology of intestine recovered at 48 h. Compared with the control group (CK group), the abundance of Proteobacteria was significantly higher (P < 0.05), while the abundance of Actinobacteria was significantly lower after infection with Vibrio alginolyticus. The abundance of Shewanella in intestinal microbiome of Litopenaeus vannamei was significantly higher at 12 h (P < 0.05), but the abundance of Candidatus_Bacilloplasma was significantly lower at 48 h after infection (P < 0.05). In VA group, the diversity of intestinal microbiome was significantly lower at 12 h, which could be caused by the proliferation of Candidatus_Bacilloplasma and Shewanella. All above findings suggested that the stability of the dynamic balance of microbiome in the intestine helped Litopenaeus vannamei to resist pathogen colonization.

Cloning and characterization of a key enzyme in octopaminergic pathway: Tyramine beta-hydroxylase from Litopenaeus vannamei, as expressed during Vibrio alginolytics infection and hypothermal stress

Tyramine beta-hydroxylase (TBH) is needed for the biosynthesis of the octopamine (OA) from tyramine (TA). Both OA and TA act as neurotransmitters, neurohormones, and neuromodulators in the invertebrate nervous system. In this study, TBH was identified in white shrimp, Litopenaeus vannamei, and further investigation on its potential function was conducted after inducing hypothermal stress and Vibrio alginolyticus infection. TBH of L. vannamei (LvTBH) was comprised 2178 nucleotide residues and contained an open reading frame encoding 408 amino acids, belonging to the Copper type II, ascorbate-dependent monooxygenases, was characterized by two Cu2_monooxygen domains and five glycosylation sites. LvTBH expression was especially abundant in muscle, and mainly in brain and thoracic ganglia of nervous system, eyestalk tissues, epithelium, and stomach, as determined by quantitative real-time PCR. The effects of hypothermal stress showed significant increases in LvTBH at 15, 30 and 60 min in brain and at 30 min in haemocyte, accompanied by an increase in OA level in haemolymph from 15 to 60 min. Significant increases in LvTBH occurred at 15, 30 and 60 min in haemocyte and at 60 min in brain tissue, and was proportional to the OA level of haemolymph under Vibrio alginolyticus infection from 30 to 60 min. Here, we demonstrated that LvTBH is functionally responsible for biogenic amine synthesis, suggesting that the increased release of OA in haemolymph for potential modulation of physiological and immunological responses is the consequence of the upregulated LvTBH gene expression in L. vannamei exposed to hypothermal stress and Vibrio alginolyticus infection.

Synbiotic combination of prebiotic, cacao pod husk pectin and probiotic, Lactobacillus plantarum, improve the immunocompetence and growth of Litopenaeus vannamei

To reach the sustainable development goals on waste recycling, cacao pod husk (CPH), produced as an agricultural waste byproduct during the cacao bean processing was applied to manufacture CPH pectin for developing the potential for diverse application in aquaculture, minimizing CPH impact to the environment and bringing benefits to the agriculture and aquaculture industries. In this study, CPH pectin (5 g/kg diet) and Lactobacillus plantarum (LP; 10¹⁰ cfu/kg diet) were separately introduced to the diets of Litopenaeus vannamei for a 56-day feeding trial, and two synbiotic combinations of CPH pectin and LP (CPH pectin at 5 g/kg diet + LP at 10⁷ cfu/kg diet or at 10¹⁰ cfu/kg diet) were also conducted. After the 56-day feeding trial, significantly elevated percent weight gain, percent length gains and feeding efficiency in L. vannamei were only observed in synbiotic combination of CPH pectin at 5 g/kg diet and LP at 10⁷ cfu/kg diet treatment, and the remainder of the treatments remained consistently similar to the control. Significantly increases in total haemocyte count, granular cells, phenoloxidase activity, and respiratory bursts were observed in L. vannamei fed with synbiotics at 7-28 days of feeding, accompanied by significant promotion of phagocytic activity and clearance efficiency in response to V. alginolyticus challenge during 56 days of feeding trial. Furthermore, at the end of the 56 days of feeding trial, shrimp receiving CPH pectin and/or LP treatments showed a significantly higher survival ratio against V. alginolyticus infection and hypothermal stress. It was therefore concluded that CPH pectin or LP was confirmed as an immunostimulant for L. vannamei to trigger immunocompetence through oral administration without negative effects within 56 days of feeding trial, and the synbiotic combination of CPH pectin and LP exhibited complementary and synergistic effects on growth performance and immunocompetence in L. vannamei.