Differential protective impact of peptide vaccine formulae targeting the lung- and liver-stage of challenge Schistosoma mansoni infection in mice.

The study aimed to elicit protective immune responses against murine schistosomiasis mansoni at the parasite lung- and liver stage. Two peptides showing amino acid sequence similarity to gut cysteine peptidases, which induce strong memory immune effectors in the liver, were combined with a peptide based on S. mansoni thioredoxin peroxidase (TPX), a prominent lung-stage schistosomula excretory-secretory product, and alum as adjuvant. Only one of the 2 cysteine peptidases-based peptides in a multiple antigenic peptide construct (MAP-3 and MAP-4) appeared to adjuvant protective immune responses induced by the TPX peptide in a MAP form. Production of TPX MAP-specific IgG1 serum antibodies, and increase in lung interleukin-1 (IL-1), uric acid, and reactive oxygen species (ROS) content were associated with significant (P < 0.05) 50 % reduction in recovery of lung-stage larvae. Increase in lung triglycerides and cholesterol levels appeared to provide the surviving worms with nutrients necessary for a stout double lipid bilayer barrier at the parasite-host interface. Surviving worms-released products elicited memory responses to the MAP-3 immunogen, including production of specific IgG1 antibodies and increase in liver IL-33 and ROS. Reduction in challenge worm burden recorded 45 days post infection did not exceed 48 % associated with no differences in parasite egg counts in the host liver and small intestine compared to unimmunized adjuvant control mice. Alum adjuvant assisted the second peptide, MAP-4, in production of IgG1, IgG2a, IgG2b and IgA specific antibodies and increase in liver ROS, but with no protective potential, raising doubt about the necessity of adjuvant addition. Accordingly, different vaccine formulas containing TPX MAP and 1, 2 or 3 cysteine peptidases-derived peptides with or without alum were used to immunize parallel groups of mice. Compared to unimmunized control mice, significant (P < 0.05 to < 0.005) 22 to 54 % reduction in worm burden was recorded in the different groups associated with insignificant changes in parasite egg output. The results together indicated that a schistosomiasis vaccine able to entirely prevent disease and halt its transmission still remains elusive.

Consequences of artificial light at night on behavior, reproduction, and development of Lymnaea stagnalis.

Light is an important zeitgeber that regulates many behavioral and physiological processes in animals. These processes may become disturbed due to the changes in natural patterns of light and dark via the introduction of artificial light at night (ALAN). The present study was designed to determine the effect of possible consequences of ALAN on reproduction, hatching success, developmental success, growth rate, feeding rate, mortality rate, and locomotor activity of the simultaneous hermaphrodite pond snail Lymnaea stagnalis. Snails were exposed to different light intensities at night that simulate actual ALAN measurements from the snail's night environment. The data revealed that exposure to ALAN at a low level significantly affected the cumulative number of laid eggs. At the same time, snails exposed to ALAN laid smaller eggs than those laid under normal light-dark cycles. Additionally, high light-intensity of ALAN delayed development and hatching of eggs of L. stagnalis while it showed no effect on hatching percentage. Furthermore, ALAN increased both the feeding and growth rates but did not lead to mortality. The results also show that snails exposed to dark conditions at night travel longer distances and do so faster than those exposed to ALAN. In light of these findings, it is clear that ALAN may have an influence on snails and their abundance in an environment, possibly disturbing ecological stability.

Slowly seeing the light: an integrative review on ecological light pollution as a potential threat for mollusks.

Seasonal changes in the natural light condition play a pivotal role in the regulation of many biological processes in organisms. Disruption of this natural condition via the growing loss of darkness as a result of anthropogenic light pollution has been linked to species-wide shifts in behavioral and physiological traits. This review starts with a brief overview of the definition of light pollution and the most recent insights into the perception of light. We then go on to review the evidence for some adverse effects of ecological light pollution on different groups of animals and will focus on mollusks. Taken together, the available evidence suggests a critical role for light pollution as a recent, growing threat to the regulation of various biological processes in these animals, with the potential to disrupt ecosystem stability. The latter indicates that ecological light pollution is an environmental threat that needs to be taken seriously and requires further research attention.

Effect of photoperiod and light intensity on learning ability and memory formation of the pond snail Lymnaea stagnalis.

Natural light is regarded as a key regulator of biological systems and typically serves as a Zeitgeber for biological rhythms. As a natural abiotic factor, it is recognized to regulate multiple behavioral and physiological processes in animals. Disruption of the natural light regime due to light pollution may result in significant effects on animal learning and memory development. Here, we investigated whether sensitivity to various photoperiods or light intensities had an impact on intermediate-term memory (ITM) and long-term memory (LTM) formation in the pond snail Lymnaea stagnalis. We also investigated the change in the gene expression level of molluscan insulin-related peptide II (MIP II) is response to the given light treatments. The results show that the best light condition for proper LTM formation is exposure to a short day (8 h light) and low light intensity (1 and 10 lx). Moreover, the more extreme light conditions (16 h and 24 h light) prevent the formation of both ITM and LTM. We found no change in MIP II expression in any of the light treatments, which may indicate that MIP II is not directly involved in the operant conditioning used here, even though it is known to be involved in learning. The finding that snails did not learn in complete darkness indicates that light is a necessary factor for proper learning and memory formation. Furthermore, dim light enhances both ITM and LTM formation, which suggests that there is an optimum since both no light and too bright light prevented learning and memory. Our findings suggest that the upsurge of artificial day length and/or night light intensity may also negatively impact memory consolidation in the wild.

Metals bioaccumulation in two edible bivalves and health risk assessment.

Our aim was to quantify the bioaccumulation of 13 metals in two edible bivalves (Ruditapes decussatus and Paphia undulata) in Lake Timsah, Egypt. A potential human health risk assessment was conducted to evaluate the hazards from bivalve consumption. Fe, Al, Zn, and Sr had the highest concentrations in the bivalve samples. The levels of Cd were much lower than the maximum permissible level, while Pb concentrations in the two bivalves were nearly two times the permissible level. The extent of bioaccumulation factor was site- and species-specific. For low and high bivalve-consuming groups, the estimated daily intake of Pb and Cd ranged from 0.01 to 0.76 µg/kg/day. For low and high bivalve-consuming groups, hazard quotients (HQs) for metals were found to be less than 1 for both bivalve species, except for Co in the high-consuming group. In conclusion, even though there was no apparent risk to bivalve consumers from being exposed to single metals, there is a risk from being exposed to the 13 studied metals together, especially for high bivalve-consuming groups such as fishermen.

Screening of marine extracts for schistosomicidal activity in vitro. Isolation of the triterpene glycosides echinosides A and B with potential activity from the Sea Cucumbers Actinopyga echinites and Holothuria polii.

CONTEXT: Praziquantel (PZQ) is the drug available for the treatment of schistosomiasis. The reported reduced cure rates, the failure of treatment after PZQ administration in patients and the existence of resistant parasite strains, reinforce the need to rapidly discover new effective molecules against Schistosoma parasite. OBJECTIVE: To screen the methanol extracts of 79 marine organisms for their schistosomicidal activities against Schistosoma mansoni adult worms in vitro and perform bio-assay directed chromatography for the most active extracts to isolate the active compounds. MATERIALS AND METHODS: Screening of the marine organisms and bio-assay directed chromatography of the most active extracts together with identification of the active isolates using 1D and 2D NMR analysis, were investigated. RESULTS: RESULTS indicated that the isolates echinosides A and B from the sea cucumbers Actinopyga echinites Jaeger and Holothuria polii Delle Chiaie (Holothuriidae) were highly active. Their LC(50) values were equal to 0.19 µg/ml and 0.27 µg/ml, respectively. Detailed (1)HNMR data for echinosides A and B are reported here for the first time. DISCUSSION AND CONCLUSION: These findings demonstrate that the isolated echinosides possess potential in vitro schistosomicidal activity against S. mansoni adult worms. Therefore, echinosides are promising as lead compounds for the development of new schistosomicidal agents.