β-Glucans are a heterogeneous group of glucose polymers with a common structure comprising a main chain of β-(1,3) and/or β-(1,4)-glucopyranosyl units, along with side chains with various branches ...and lengths. β-Glucans initiate immune responses via immune cells, which become activated by the binding of the polymer to specific receptors. However, β-glucans from different sources also differ in their structure, conformation, physical properties, binding affinity to receptors, and thus biological functions. The mechanisms behind this are not fully understood. This mini-review provides a comprehensive and up-to-date commentary on the relationship between β-glucans' structure and function in relation to their use for immunomodulation.
The invertebrate's innate immune system was reported to show some form of adaptive features, termed trained immunity. However, the memory characteristics of innate immune system and the mechanisms ...behind such phenomena remain unclear. Using the invertebrate model Artemia, we verified the possibility or impossibility of trained immunity, examining the presence or absence of enduring memory against homologous and heterologous antigens (Vibrio spp.) during a transgenerational study. We also determined the mechanisms behind such phenomenon. Our results showed the occurrence of memory and partial discrimination in Artemia's immune system, as manifested by increased resistance, for three successive generations, of the progenies of Vibrio-exposed ancestors towards a homologous bacterial strain, rather than to a heterologous strain. This increased resistance phenotype was associated with elevated levels of hsp70 and hmgb1 signaling molecules and alteration in the expression of key innate immunity-related genes. Our results also showed stochastic pattern in the acetylation and methylation levels of H4 and H3K4me3 histones, respectively, in the progenies whose ancestors were challenged. Overall results suggest that innate immune responses in invertebrates have the capacity to be trained, and epigenetic reprogramming of (selected) innate immune effectors is likely to have central place in the mechanisms leading to trained immunity.
Goldfish (Carassius auratus) juveniles were exposed to virgin polyvinyl chloride microplastics (PVC-MPs) in triplicate at 0, 0.1 or 0.5 mg/L for four days. Afterwards, the histopathology of the ...gills, liver and intestines were examined, along with various antioxidant enzymes and indicators of oxidative damage (malondialdehyde (MDA) and hydrogen peroxide (H2O2)), in the brain, liver and gills. In addition, we also studied the expression of hepatic insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein 1 (IGFBP-1) and growth hormone (GH) receptor, while cortisol receptor (CR) and cytochrome P450 1A (CYP1A) gene expression were assayed in both the liver and gills. Histological analysis revealed PVC-MPs in the intestines at 0.1 and 0.5 mg/L, along with substantially shorter villi. The gills appeared undamaged by PVC-MPs exposure and had limited or no effect to antioxidant activity, Na+/K+-ATPase and H+-ATPase activity or plasma ion levels, but there was a prominent upsurge of the detoxification enzymes glutatione S-transferase (GST) activity and CYP1A expression. Livers showed inflammation and some occurrences of hemorrhaging and necrosis at 0.5 mg/L. While the brain showed some evidence of oxidative damage, the liver was the most susceptible to oxidative damage, based on increased MDA, H2O2 and various antioxidant enzymes. Hepatic expression of IGFBP-1 and GH receptor were significantly downregulated at 0.5 mg/L while CR was upregulated. Results indicate that exposure to environmentally relevant PVC-MP can cause oxidative damage in the brain and liver, adverse histomorphological changes to the intestine and liver and alter the gene expression in goldfish.
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•Virgin microplastics (MPs) at 0.5 mg/L induced oxidative damage to brain and liver.•Anti-oxidative response was differentially modulated in brain, liver and gills.•Histology revealed MPs in intestines at 0.1 and 0.5 mg/L, with substantially shortened villi.•0.5 mg/L MPs reduced growth regulating genes receptors and binding proteins expression.•PVC-MPs had no effect on gills Na+/K+-ATPase and H+-ATPase activities, and ions status.
Vibrio campbellii
is one of the major bacterial pathogens for animals reared in aquaculture, affecting both vertebrates and invertebrates, and causes significant economic losses. It is now evident ...that the expressions of virulence factors in this pathogen are regulated by the density of the bacterial population. This type of regulation, termed quorum sensing (QS), is mediated by extracellular signal molecules called autoinducers. In this study, the impact of sodium ascorbate (NaAs) on the virulence of
V. campbellii
was investigated under both
in vitro
and
in vivo
conditions, to develop a natural anti-infective strategy to contain
V. campbellii
infection in aquacultured animals. Results showed that NaAs significantly decreased swimming motility, biofilm production, and the production of virulence enzymes, such as lipase, caseinase, phospholipase, and hemolysin in
V. campbellii
. Consistent with this, pretreatment of
V. campbellii
with NaAs before inoculation into the rearing water resulted in significantly increased survival of gnotobiotic brine shrimp larvae, when compared to larvae challenged with untreated
V. campbellii
. Furthermore, NaAs could interfere with QS-regulated bioluminescence in
V. campbellii
, suggesting the QS-inhibitory activity largely determines the protective effect of NaAs toward the brine shrimp. In essence, due to the potent anti-virulence effects observed in
in vitro
studies and the clinical brine shrimp-
V. campbellii
infection model, NaAs constitute a promising novel strategy for the control of
V. campbellii
infections in aquaculture.
The halophilic aquatic bacterium,
, is an important aquatic pathogen, also capable of causing acute hepatopancreatic necrosis disease (AHPND) in shrimp resulting in significant economic losses. ...Therefore, there is an urgent need to develop anti-infective strategies to control AHPND. The gnotobiotic
model is used to establish whether a phenolic compound phloroglucinol is effective against the AHPND strain
MO904. We found that pretreatment with phloroglucinol, at an optimum concentration (30 µM), protects axenic brine shrimp larvae against
infection and induced heat shock protein 70 (Hsp70) production (twofolds or more) as compared with the control. We further demonstrated that the
-protective effect of phloroglucinol was caused by its prooxidant effect and is linked to the induction of Hsp70. In addition, RNA interference confirms that phloroglucinol-induced Hsp70 mediates the survival of brine shrimp larvae against
infection. The study was validated in xenic
model and in a
system. Pretreatment of xenic brine shrimp larvae (30 µM) and
larvae (5 µM) with phloroglucinol increases the survival of xenic brine shrimp and
larvae against subsequent
challenge. Taken together, our study provides substantial evidence that the prooxidant activity of phloroglucinol induces Hsp70 production protecting brine shrimp,
, and freshwater shrimp,
, against the AHPND
strain MO904. Probably, phloroglucinol treatment might become part of a holistic strategy to control AHPND in shrimp.
A 120-day feeding trial was conducted in a pilot field setting to study the nutraceutical properties of ginger powder (GP), focusing on the growth performance and health status of Indian major carp
L
....
rohita
reared under a semi-intensive culture system.
L. rohita
fingerlings (average weight: 20.5 g) were divided into five groups and fed a diet with no GP supplementation (control), or a diet supplemented with GP at 5 g (GP5), 10 g (GP10), 15 g (GP15), and 20 g (GP20) per kg of feed. The study was carried out in outdoor tanks (20 m
2
) following a complete randomized design with three replicates for each experimental group. Dietary supplementation of GP at 15 g·kg
−1
(GP15) of feed caused a significant increase in the growth performances of the fish. Results also showed that feeding of GP15 diet led to a significant improvement in the health status of fish as indicated by a marked change in the tested haematological indices (i.e., higher RBC, WBC, Hb, and Ht values), oxidative status (increased SOD and decreased LPO levels), biochemical parameters (increased HDL, decreased cholesterol, and triglycerides levels), and activities of the liver enzymes (decreased AST and ALT). Overall results suggested that dietary supplementation of GP could positively influence the growth and health status of
L. rohita
fingerlings, and hence could be an important natural nutraceutical for sustainable farming of carp.
In this study, we evaluated the effect of probiotic bacteria
supplemented at different inclusion levels in a control diet basal diet containing 0.5% fructooligosaccharide (FOS) on the growth ...performance, feed conversion ratio, immune response, and the disease resistance of whiteleg shrimp
juveniles against
. A control diet with 0.5% FOS but without
supplementation (Control) was prepared. In addition, three other test diets were also formulated: control diet supplemented with
at (i) 1 × 10
cfu g
diet (P1), (ii) 1 × 10
cfu g
diet (P2), or (iii) 1 × 10
cfu g
diet (P3). After a 60-day feeding trial, the experimental shrimps were challenged with
The results showed that dietary supplementation of
significantly improved the growth performance and immune responses of
juveniles. The juveniles that were fed with a P2 or P3 diet recorded the maximum increase in the final body weight, final length, weight gain, and survival rate. The total hemocyte counts, phenoloxidase, and lysozyme activity of shrimp fed with either of these two diets were significantly enhanced. The results also showed that juveniles fed with a P2 or P3 diet exhibited significantly lower mortality when challenged with
. Overall results suggested that a combination of
at the inclusion level of 1 × 10
cfu g
diet (P2) and 0.5% FOS could be considered as a potential synbiotic formulation for improving the growth, health, and robustness of
.
In this study, we tested the compatibility of two extracts from the plant Jerusalem artichokes and button mushrooms with two different
Lactobacillus
probiotics (
Lactobacillus acidophilus
; La and
...Lactobacillus delbrueckii
subsp.
Bulgaricus
; Lb) to develop a synbiotic formulation to improve the growth, survival, and reproductive performances of farmed fishes. Initially, we employed
in vitro
approach to monitor the growth of the probiotic lactobacilli in the presence of the different doses of the plant-based prebiotics, with the aim of selecting interesting combination(s) for further verification under
in vivo
conditions using zebrafish as a model. Results from the
in vitro
screening assay in the broth showed that both the probiotic species showed a preference for 50% mushroom extract as a source of prebiotic. A synbiotic formulation, developed with the selected combination of
L. acidophilus
,
L. bulgaricus
, and 50% mushroom extract, showed a positive influence on the growth and reproductive performances of the zebrafish. Our findings also imply that the improvement in the reproductive indices was associated with the upregulation of a
cyp19a
gene. Overall results suggest that a combination of
L. acidophilus
,
L. bulgaricus
, and mushroom extract can be considered as a potential synbiotic for the successful production of aquaculture species.
•HSP70 and HMGB1 proteins are molecular chaperones for protein and DNA, respectively.•In presence of stressors, these proteins are involved in generating immune responses.•HSP70 and HMGB1 were ...elevated sequentially in Artemia in response to mild heat stress.•These alterations were associated with improved survival of Vibrio-challenged Artemia.
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