Effect of ecotype and Enteromorpha polysaccharide supplementation on the growth performance of indigenous chickens in Northwest Ethiopia.

The study was conducted to compare the growth performance of indigenous chickens and evaluate the effect of Enteromorpha prolifera (EP) supplementation on the growth of chickens. A total of 180 indigenous chicken ecotypes (Sinan, Dembecha, North Achefer, and Jawi) were used in the study. Chicken ecotype and sex had a highly significant (p < 0.001) effect on body weight and average daily gain (ADG). The highest final body weight (1811.5 ± 16.6 g) and ADG at twenty weeks of age (12.76 ± 0.12 g) were recorded for the Jawi ecotype, followed by the North Achefer. A significantly higher body weight and ADG in male chickens than female chickens were observed. The EP supplemented (EP +) chickens showed a significantly (P < 0.05) higher body weight and ADG than the non-supplemented (EP-) chickens. The interaction effect of ecotype and feed type was not statistically significant on body weight in the starter and grower phases, except at week 9. In the first four weeks, the highest (100%) and lowest (91.7%) survivability rates were recorded for the Sinan ecotype and the Jawi ecotype, respectively. In general, the Jawi and North Achefer ecotypes had better growth performance, and the Sinan ecotype relatively showed better survivability. EP supplementation could improve the growth performance of chickens.

The causal link between nitrogen structure and physiological processes of Ulva prolifera as the causative species of green tides.

Harmful algal blooms (HABs) increase with eutrophication depending on the nutrient structure (availability and ratios), but an unequivocal causal link between these factors is rarely established. Here, we provide support for the causal link between the nitrogen structure and physiological processes of Ulva prolifera as the causative species of Yellow Sea green tides (YSGTs) using in situ and laboratory experiments. The results showed that the components of nitrogen nutrients in seawater exhibited significant spatiotemporal variation. The concentration of NO3--N showed a notable decreasing trend from south to north. Sufficient dissolved inorganic nitrogen (DIN) induced increases in thalli nitrate reductase (NR) and glutamine synthetase (GS) activities. This could accelerate thalli uptake of nitrogen nutrients. The glutamate dehydrogenase (GDH) activity was significantly upregulated with the increasing proportion of dissolved organic nitrogen (DON) in seawater. The change in nitrogen structure regulated the activity of NR during the long-distance floating migration of the YSGTs. And the activity of NR could modulate the nitric oxide (NO) content in the thalli. NO was used as a signal molecule to enhance the antioxidant defense system of thalli. The efficient antioxidant system in the thalli could reduce oxidative stress and effectively maintain high photosynthetic activity. The findings deepen our understanding of the relationship between nitrogen structures and key biological processes in macroalgae. This study also suggest that NO can enhance key biological processes in U. prolifera under varying nitrogen structures.

A comparison of the biofouling potential of field-collected and laboratory-cultured Ulva.

The marine algae Ulva spp. are commonly used as model biofouling organisms. As biofouling studies are primarily conducted using field-collected specimens, factors including species identity, seasonal availability, and physiological status can hinder the replicability of the results. To address these limitations, a protocol was developed for the on-demand laboratory culture and release of Ulva zoospores. The biofouling potential of laboratory-cultured and field-collected Ulva blades was compared using a waterjet. No significant differences were found between field and laboratory-cultured samples in either spore adhesion (before waterjet) or the proportion of spores retained after waterjet exposure. However, there was significant variability within each session type in pre- and post-waterjet exposures, indicating that spore adhesion and retention levels vary significantly among trial runs. In addition, all our laboratory cultures were Ulva Clade C (LPP complex). In contrast, our field samples contained a mix of Ulva Clade C, U. compressa clade I, and U. flexuosa Clade D. This protocol for on-demand production of Ulva spores can improve biofouling research approaches, enables comparison of results across laboratories and regions, and accelerate the development of anti-biofouling strategies.

Nitrogen isotope variability of macroalgae from a small fishing village, Staithes Harbour, Yorkshire, UK.

Macroalgal nitrogen isotope analysis (δ15N) is a reliable method for the identification of nitrogen pollutant sources. Understanding δ15N geospatial variation within small bays and/or harbour environments can help identify point sources of nitrogen pollution. This study sampled over 300 Fucus vesiculosus and Ulva sp. specimens in September 2022 and May 2023 from Staithes Harbour, North Yorkshire, England. δ15N values for Staithes Beck were elevated when compared to sites in Staithes Harbour and the North Sea: this is attributed to sewage effluent and/or agricultural manure. Few sites within Staithes Harbour were significantly different from one another in terms of δ15N, suggesting a relatively homogenous nitrogen isotope record of the harbour. Simple harbour environments like Staithes may be relatively well mixed, and thus, sampling one harbour site may be enough to represent the entire harbour. Of course, more complex harbours may require more sample locations to ascertain point sources and mixing in the harbour.

Study on adsorption behavior of humic acid on aluminum in Enteromorpha prolifera.

High level of aluminum content in Enteromorpha prolifera posed a growing threat to both its growth and human health. This study focused on exploring the factors, impacts, and process of removing aluminum from Enteromorpha prolifera using humic acid. The results showed that under experimental conditions of 0.0330 g·L-1 humic acid concentration, pH 3.80, 34 °C, and a duration of 40 min, the removal rate was up to 80.18%. The levels of major flavor components, proteins, and amino acids in Enteromorpha prolifera increased significantly after treatment, while polysaccharides and trace elements like calcium and magnesium decreased significantly. Infrared spectroscopy demonstrated that the main functional groups involved in binding with Al3+ during humic acid adsorption were hydroxyl, carboxyl, phenol, and other oxygen-containing groups. The adsorption process of Al3+ by humic acid was a spontaneous phenomenon divided into three key stages: fast adsorption, slow adsorption, and adsorption equilibrium, which resulted from both physical and chemical adsorption effects. This study provided a safe and efficient method in algae metal removal.

How plastic litter sunk by biofouling recovers buoyancy - The role of benthic predation.

Estimates suggest that the amount of plastic litter discarded in the ocean is several times greater than what remains floating at the sea surface, raising questions about the fate of this marine debris. Fouling-induced sinking of plastic litter is one of the proposed mechanisms responsible for this mass difference. While some of this 'missing' plastic mass may be explained by the effects of fouling, it has also been hypothesized that sinking litter may return to the surface after benthic organisms consume the biofouling. However, this hypothesis has never been tested. The present study evaluated the structure and biomass of the fouling community in response to benthic predation in both summer and winter seasons. Floating PVC plates were installed during winter and summer in central Chile (36°S) until the growing biofouling community caused them to sink. Plates were then moved to the seabed, where they were exposed to benthic predation, while control plates were maintained in a mesh cage impeding predator access. In summer, all plates recovered their buoyancy, while in the winter only 60 % recovered buoyancy. All caged control samples remained on the bottom in both seasons. The community structure differed both in the treatments and across the seasons, with plates that recovered buoyancy initially being dominated by Ulva sp. and Ciona robusta. Conversely, plates that did not refloat were mainly covered by species resistant to predation such as Pyura chilensis, Austromegabalanus psittacus, and Balanus laevis. Thus, fouling community structure influences how predation facilitates buoyancy recovery, because not all epibionts can be consumed by predators. While previous studies had shown how fouling organisms cause sinking of floating litter, this is the first study to provide experimental evidence that predation can reverse this process and allow litter to resurface and become again available as dispersal vectors for native and invasive species.

Assessment of the antibacterial and antioxidant activities of seaweed-derived extracts.

In swine farming, animals develop diseases that require the use of antibiotics. In-feed antibiotics as growth promoters have been banned due to the increasing concern of antimicrobial resistance. Seaweeds offer bioactive molecules with antibacterial and antioxidant properties. The aim was to estimate the in vitro properties of seaweed extracts: Ascophyllum nodosum (AN), Palmaria palmata (PP), Ulva lactuca (UL), and 1:1 mixes (ANPP, ANUL, PPUL). Escherichia coli strains were used to test for growth inhibitory activity, and chemical-based assays were performed for antioxidant properties. The treatments were 2 (with/without Escherichia coli) × 2 (F4 + and F18 +) × 5 doses (0, 1.44, 2.87, 5.75, 11.50, and 23.0 mg/mL). Bacteria were supplemented with seaweed extracts, and growth was monitored. The antioxidant activity was assessed with 6 doses (0, 1, 50, 100, 200, 500, and 600 mg/mL) × 6 compounds using two chemical assays. Data were evaluated through SAS. The results showed that AN and UL significantly inhibited (p < 0.05) the growth of F4 + and F18 +. PP and mixes did not display an inhibition of the bacteria growth. AN, PP, UL extracts, and mixes exhibited antioxidant activities, with AN showing the strongest dose-response. Thus, AN and UL seaweed extracts reveal promising antibacterial and antioxidant effects and may be candidates for in-feed additives.

Anti-coccidial efficacy of Enteromorpha prolifera polysaccharide in indigenous chickens of Northwest Ethiopia.

BACKGROUND: A variety of bioactive compounds isolated from various botanical sources have been found to have therapeutic and immunotherapeutic effects on chicken coccidiosis. AIM: This study aimed to evaluate the anti-coccidial potential of Enteromorpha prolifera polysaccharide (EP) in indigenous chickens in Northwest Ethiopia. MATERIALS AND METHODS: A total of 78 male indigenous chickens were used for this study. The study had two treatment groups: (1) the EP non-supplemented group (those fed on diets without EP and Eimeria oocyst inoculated) and (2) the EP group (those receiving diets supplemented with 400 mg EP/kg diet and Eimeria oocyst inoculated). Each treatment group had five replications. Following fourteen days of EP supplementation, 1.5 × 104 oocysts of mixed Eimeria species were inoculated into individual birds. RESULTS: EP-supplemented chicken showed significantly lower (p < 0.05) oocyst counts compared to non-supplemented ones on 9 and 11 days post-challenge. In addition, chickens in the EP-supplemented group showed less severe lesion scores, with an average score of 1.33. Chickens that received EP showed a maximum of 27.27% protection against lesions. In contrast, the non-supplemented chickens had a lower percentage of protection (19.83%). The maximum anti-coccidial index value (146.98) was obtained from EP-supplemented chickens. Chickens in the EP-supplemented group exhibited a significantly higher (p < 0.05) weight gain. CONCLUSION: Overall, the inclusion of EP in chickens' diets shows promise as a potential anti-coccidial strategy. However, additional research is required to explore the mechanisms by which EP in chickens' diet could involve in increasing the protection ability of chickens against coccidiosis.

Preparation and Vasodilation Mechanism of Angiotensin-I-Converting Enzyme Inhibitory Peptide from Ulva prolifera Protein.

Ulva prolifera, a type of green algae that can be consumed, was utilized in the production of an angiotensin-I converting enzyme (ACE) inhibitory peptide. The protein from the algae was isolated and subsequently hydrolyzed using a neutral protease. The resulting hydrolysate underwent several processes including Sephadex-G100 filtration chromatography, ultrafiltration, HPLC-Q-TOF-MS analysis, ADMET screening, UV spectrum detection test, molecular docking, and molecular dynamic simulation. Then, the ACE inhibitory peptide named KAF (IC50, 0.63 ± 0.26 µM) was identified. The effectiveness of this peptide in inhibiting ACE can be primarily attributed to two conventional hydrogen bonds. Additionally, it could activate endothelial nitric oxide synthase (eNOS) activity to promote the generation of nitric oxide (NO). Additionally, KAF primarily increased the intracellular calcium (Ca2+) level by acting on L-type Ca2+ channel (LTCC) and the ryanodine receptor (RyR) in the endoplasmic reticulum, and completed the activation of eNOS under the mediation of protein kinase B (Akt) signaling pathway. Our study has confirmed that KAF has the potential to be processed into pharmaceutical candidate functions on vasoconstriction.

Light Spectra, a Promising Tool to Modulate Ulva lacinulata Productivity and Composition.

Light quality is a key factor affecting algal growth and biomass composition, particularly pigments such as carotenoids, known for their antioxidant properties. Light-emitting diodes (LEDs) are becoming a cost-effective solution for indoor seaweed production when compared to fluorescent bulbs, allowing full control of the light spectra. However, knowledge of its effects on Ulva biomass production is still scarce. In this study, we investigated the effects of LEDs on the phenotype of an Ulva lacinulata strain, collected on the Northern Portuguese coast. Effects of white (W), green (G), red (R), and blue (B) LEDs were evaluated for growth (fresh weight and area), photosynthetic activity, sporulation, and content of pigments and antioxidant compounds. The results showed that there were no significant differences in terms of fresh weight accumulation and reduced sporulation among the tested LEDs, while W light induced the highest expansion rate. Under G, U. lacinulata attained a quicker photoacclimation, and the highest content of pigments and total antioxidant activity; but with R and W, antioxidant compounds against the specific radicals O2•- and •NO were produced in a higher content when compared to other LEDs. Altogether, this study demonstrated that it is possible to modulate the bioactive properties of U. lacinulata by using W, R, and G light, opening the path to the production of biomass tailored for specific nutraceutical applications.

Mechanism of up-regulated H2O2 BPA-derived production and production of (poly)phenols by two seaweeds of the genus Ulva.

The present study provides information on the effects of BPA on ROS production-related phenomena in the chlorophytes Ulva rigida and U. intestinalis, and on the mechanism they establish against BPA toxicity, at environmentally relevant concentrations (0.1-3 µg L-1). Up-regulated H2O2 generation seems to be a key factor causing oxidative damage. Interspecific differences, in terms of the mechanism and the temporal response to BPA toxicity were observed. BPA effects on U. rigida were more intense and appeared earlier (on 1D at 0.1 µg L-1) compared to U. intestinalis and mostly after 7D (LOEC: 0.3 µg L-1, Terminal time, Tt: 7D). In U. rigida, on 1-5D, the 'mosaic' type effect patterns ('models' 3A/3B) with 'unaffected' and 'affected' areas (dark content, positive H2DCF-DA staining signal/H2O2 production and chlorophyll autofluorescence signal loss) indicated a time-dependent manner. After 7D, only U. rigida cells with dark content formed aggregates, showing positive H2O2 production ('model' 4) or in some cells oxidative damages triggering retrograde signaling in the neighboring 'unaffected' areas ('model' 5). H2O2 overproduction (CTCF ratio) in U. rigida, on 1D at the lowest concentration and after 7D at 0.3-1/3 µg L-1, respectively, seems to stimulate (poly)phenolic production, in a dose- and time-dependent manner. U. intestinalis did not display severe BPA impact (i.e., 'models' 4, 5) at any exposures, although at a later time indicated a lower LOEC (0.1 µg L-1, Tt: 9D) than that in U. rigida. In U. intestinalis, H2O2 production does not appear to stimulate high (poly)phenolic amounts.

Hydrothermal extraction of ulvans from Ulva spp. in a biorefinery approach.

A simple cascade process based on the hydrothermal fractionation of Ulva spp. biomass was proposed. Considering the overall extraction yields (50 %), ulvan recovery (23 %), and ulvan composition, structural, mechanical and cytotoxic properties, the selected optimal final heating temperature was 160 °C. Ethanol precipitation provided the highest ulvan recovery yields but choline chloride precipitated ulvans showed stronger mechanical properties, G´ moduli 1.5·104 Pa and 3·104 Pa for ethanol and for choline chloride, respectively. Both products were safe on NCTC 929 mouse fibroblasts and after a cooling stage, formed films without requiring any additives. From the ulvan-free liquid fraction, one product with 43 % (wt, d.b.) phenolics and moderate antiradical properties and a byproduct containing nutrients and minerals were separated. The methane potential of the corresponding residual solids was influenced by the hydrothermal heating temperature and was doubled compared to than for the untreated seaweed biomass (60 mL/g VS). This scheme could be also applied to the wet algal biomass, in a chemical free alternative to provide ready to use ulvan biopolymers, bioactives, nutrients, salts and biogas, conforming a biorefinery approach.

Effects of Enteromorpha prolifera sulfated polysaccharide and aluminium ion addition on the multifunctional property of conductive hydrogel for wearable strain sensing.

Although introducing Enteromorpha prolifera sulfated polysaccharide (SPEP) enhances the mechanical properties of hydrogels significantly, little is known about the effects of polysaccharide and ion addition on morphological and physicochemical properties of conductive hydrogel. Therefore, the Poly (acrylic acid)/SPEPn/Al3+m (PAA/SPEPn/Al3+m) hydrogels with different SPEP and Al3+ addition were synthesized by simple one-pot method. The porosity, tensile strength, and swelling ration increased, while compressive strength, elongation at break, self-healing, self-adhesion properties increased first and then decreased as SPEP addition increased from 0 % to 3.80 %. The Al3+ addition increased from 0.08 % to 0.30 %, both tensile and compressive strength increased first and then decreased, while elongation at break kept increasing. Unexpectedly, both increasing SPEP and Al3+ addition reduced the electrical conductivity, while SPEP increased the gauge factor of hydrogel. The hydrogel exhibited optimal comprehensive properties when SPEP and Al3+ addition were 2.31 % and 0.24 %, respectively. The PAA/SPEP2.31%/Al3+0.24% hydrogel showed high tensile strength (107.60 kPa), elongation at break (2426.67 %), strain self-healing rate (81.87 %), adhesion strength (21.61 kPa), and conductivity (3.60 S/m). Overall, the properties of PAA/SPEPn/Al3+m hydrogels can be regulated through tailoring SPEP and Al3+ addition, which can be used as on-demand strategy to improve the performance of PAA/SPEPn/Al3+m hydrogels for each application.

Differential effects of petroleum hydrocarbons on the growing development and physiological characteristics of Ulva species.

To compare the different effects of petroleum hydrocarbons on intertidal Ulva macroalgae, three dominant Ulva species (U. prolifera, U. linza, and U. lactuca) were exposed to two water-accommodated fractions (WAFs) of 0# diesel oil and crude oil at three concentration levels. The results indicated that two WAFs had significant concentration effects on the physiological characteristics of Ulva, the toxicity of 0# diesel oil was greater than crude oil, and crude oil had hormesis effect. Exposure of high WAFs concentrations, the growth, pigment, carbohydrate, and protein contents of Ulva were inhibited, while the antioxidant system was activated. In addition, the integrated biomarker response (IBR) indicated that U. prolifera had higher resistance to WAFs than U. linza and U. lactuca. Considering that U. prolifera is the main species of green tide in the Yellow Sea (YS) of China, the comparative effects of WAFs on different development stages of U. prolifera were also explored. The results showed that spore was the most sensitive to WAFs, while adult thalli was the most tolerant. The increased resistance of U. prolifera thalli and the hormesis effect triggered by crude oil may influence the outbreak scale of green tides. This study provides a new perspective for understanding the formation of green tides in the YS.

Minerals and trace element compositions of some seaweeds from the Marchica lagoon, North-East Mediterranean coast of Morocco.

The objective of the present study was to evaluate the mineral and heavy metals composition of different seaweeds growing in Marchica lagoon. To this end, green seaweeds, red seaweeds, and brown seaweeds were collected from three different stations in the Marchica lagoon. The highest concentration of Ca was measured in Centroceras clavulatum (17.12 ± 0.60), K in Caulerpa prolifera (15.17 ± 0.20), Na in Gracilaria dura (4.16 ± 0.03) and Hypnea musciformis (4.09 ± 0.03), Mg in Ulva rigida (2.80 ± 0.06), and the highest concentration of P was registered in Ulva intestinalis (3658 ± 14). Centroceras clavulatum and Gracilaria dura had the highest Al, Fe, and Sr levels. Cystoseira compressa had the highest As (53.8 mg/kg) and Rb (43 mg/kg). These findings suggest that seaweeds collected from Marchica lagoon could be used as potential sources of minerals and trace elements in seaweed-based products for human and animal nutrition alike.

Why did the world's largest green tides occur exclusively in the southern Yellow Sea?

The world's largest green tide, caused by the nuisance green algae Ulva prolifera, has occurred in the southern Yellow Sea for 16 consecutive years. It is puzzling why the extensive floating green tide occurs exclusively in the southern Yellow Sea, rather than other waters. We speculate that the transition of U. prolifera from a sessile state to a surface-floating one is the underlying cause of the floating green tide. Here we founded that the floating of U. prolifera was attributed to detachment from substrata and appropriate desiccation. The convergence of unreasonable green algae disposal, geographical features and farming patterns of Porphyra (economic red algae) in Subei Shoal contributed to mass production of floating U. prolifera, resulting in the exclusive occurrence of the floating green tides. Inducing the natural inactivation of green algae to prevent the floating of U. prolifera may effectively mitigate the extensive Ulva bloom at zero cost.

The Synergistic Inhibitory Effect of Combination Drug Treatment of Enteromorpha Prolifera Polysaccaharide and Doxorubicin Hydrochloride on A549 Cell.

BACKGROUND: As a common drug for tumor therapy, doxorubicin hydrochloride (DOX) is not yet widely used as a clinical solution. This is due to its toxicity and potential drug resistance. OBJECTIVE: This study investigated the inhibitory effect of enteromorpha prolifera polysaccaharide (EPP) combined with doxorubicin hydrochloride (DOX) on A549 cells, which fall into the cell line of human non-small cell lung cancer (NSCLC). It also explained the attenuated and synergistic effect of enteromorpha acid polysaccharide along with its synergistic effect on DOX. METHODS: To evaluate the proliferation inhibitory effect of EPP, DOX and both combined, we monitored cell growth curve and morphology using the real-time cell function analysis and imaging system-xCELLigence RTCA eSight system (eSight system). Flow cytometry was used to monitor cell apoptosis rate and cell cycle distribution. Mitochondrial function was tested by the energy metabolism analysis system. RESULTS: EPP could work with DOX to inhibit the proliferation of A549 cells. Growth curve showed that when 0.4 mg/mL of EPP was mixed with 0.2 µg/mL of DOX for 24 h, the mixure liquid had a significant inhibitory effect on the proliferation of A549 cells (p < 0.0001). The cells had lower cell adhesiveness, shrinking cell membrane, cytoplasmic aggregation, and hyperchromatic nuclei. According to the flow cytometry results, the combined drug of EPP and DOX could significantly increase the apoptosis rate of A549 cells (p < 0.0001), and block the cell cycle in the G1-S phase. Based on the results of the real-time energy metabolism, we found that the combined drug could significantly reduce A549 cells' ATP production rate and inhibit their mitochondrial respiratory function. CONCLUSIONS: The combination of EPP and DOX can block cell cycle, inhibit cell mitochondrial function, promote cell apoptosis, and enhance the killing ability of DOX on tumor cells. This study supports the antitumor activity of enterococcus acid polysaccharide and provides insights on reducing doxorubicin toxicity and drug resistance. It holds great significance for applying traditional Chinese natural medicine in clinical disease treatment.

Diversity of endophytic bacteria with antimicrobial potential isolated from marine macroalgae from Yacila and Cangrejos beaches, Piura-Peru.

Endophytic bacteria found in marine macroalgae have been studied for their potential antimicrobial activity, consequently, they could serve as a valuable source of bioactive compounds to control pathogenic bacteria, yeasts, and fungi. Algae endophytic bacteria were isolated from Caulerpa sp., Ulva sp., Ahnfeltiopsis sp., and Chondracantus chamissoi from Yacila and Cangrejo Beaches (Piura, Peru). Antimicrobial assays against pathogenic bacteria were evaluated using cross-culture, over-plate, and volatile organic compound tests. Afterward, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of selected crude extracts were determined, also ITS molecular analysis, antifungal activity, and PCR of iturin, fengycin, and surfactin genes were performed for bacteria strains exhibiting better activity. Forty-six algae endophytic bacteria were isolated from algae. Ten strains inhibited gram-positive pathogenic bacteria (Enterococcus faecalis, Staphylococcus epidermidis, S. aureus, and Listeria monocytogenes), and 12 inhibited gram-negative bacteria (Escherichia coli and Salmonella enteric sv typhimurium). Bacteria with better activity belong to Bacillus sp., Kluyvera ascorbata, Pantoea agglomerans, Leclercia adecarboxylata, and Enterobacter sp., which only four showed antifungal activities against Candida albicans, C. tropicalis, Colletotrichium sp., Fusarium sp., Fusarium oxysporum, and Alternaria sp. Furthermore, K. ascorbata YAFE21 and Bacillus sp. YCFE4 exhibited iturin and fengycin genes. The results indicate that the algae endophytic bacteria found in this study, particularly K. ascorbata YAFE21, Bacillus sp. YCFR6, L. adecarboxylata CUFE2, Bacillus sp. YUFE8, Enterobacter sp. YAFL1, and P. agglomerans YAFL6, could be investigated as potential producers of antimicrobial compounds due to their broad activity against various microorganisms.

Zinc oxide-Ulva lactuca nanocomposite is a robust dietary immunostimulant in the red swamp crayfish (Procambarus clarkii).

Aquaculture industry suffers significant limitations such as low resistance to diseases and expensive feed. This study investigated the antibacterial and immunostimulatory activities of ZnO-Ulva lactuca nanocomposite (ZnO-Ul NC) in the Procambarus clarkii. Zinc oxide nanoparticles (ZnO NPs) and ZnO-Ul NC were synthetized and characterized by electron microscopies as well as Fourier transform infrared spectroscopy. ZnO NPs and ZnO-Ul NC inhibited the growth of the isolated species Citrobacter freundii and Enterobacter hormaechei. For immunostimulatory evaluation, six crayfish groups (control, U. lactuca, ZnO L, ZnO H, ZnO-Ul L, and ZnO-Ul H) were fed on commercial diet, Ulva lactuca powder, and low or high dose of ZnO NPs or ZnO-Ul NCs, respectively for 90 days. The highest levels of total hemocyte count, granular cells%, phenoloxidase (PO) activity in hemolymph, and NO, superoxide dismutase (SOD), and GSH in hepatopancreas were all reported in the ZnO-Ul groups. The expression of proPO, SOD, and lysozyme exhibited the highest upregulation in the ZnO-Ul H group. Taken together, dietary ZnO-Ul NC significantly improved the non-specific immunity and antioxidant milieu of the crayfish at the genomic and proteomic levels. ZnO-Ul NC is cost effective, easily synthesized, and a promising immunostimulant for Procambarus clarkii that could be used in the aquaculture.

Regulation of seawater dissolved carbon pools by environmental changes in Ulva prolifera originating sites: A new perspective on the contribution of U. prolifera to the seawater carbon sink function.

The Ulva prolifera bloom is considered one of the most serious ecological disasters in the Yellow Sea in the past decade, forming a carbon sink in its source area within a short period but becoming a carbon source at its destination. To explore the effects of different environmental changes on seawater dissolved carbon pools faced by living U. prolifera in its originating area, U. prolifera were cultured in three sets with different light intensity (54, 108, and 162 µmol m-2 s-1), temperature (12, 20, and 28 °C) and nitrate concentration gradients (25, 50, and 100 µmol L-1). The results showed that moderate light (108 µmol m-2 s-1), temperature (20 °C), and continuous addition of exogenous nitrate significantly enhanced the absorption of dissolved inorganic carbon (DIC) in seawater by U. prolifera and most promoted its growth. Under the most suitable environment, the changes in the seawater carbonate system were mainly dominated by biological production and denitrification, with less influence from aerobic respiration. Facing different environmental changes, U. prolifera continuously changed its carbon fixation mode according to tissue δ13C results, with the changes in the concentrations of various components of DIC in seawater, especially the fluctuation of HCO3- and CO2 concentrations. Enhanced light intensity of 108 µmol m-2 s-1 could shift the carbon fixation pathway of U. prolifera towards the C4 pathway compared to temperature and nitrate stimulation. Environmental conditions at the origin determined the amount of dissolved carbon fixed by U. prolifera. Therefore, more attention should be paid to the changes in marine environmental conditions at the origin of U. prolifera, providing a basis for scientific management of U. prolifera.