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Validation of otolith daily increment formation and early growth analysis of Japanese flounder (<em>Paralichthys olivaceus</em>)
Get PDFThe Japanese flounder is a vital economic species among East Asian released and cultured fish. Here, we sought to validate daily increment formation and analyze the early morphological development of sagittal otoliths and lapillus in Japanese flounder larvae and juveniles over 50 days. Our analysis focused on the otolith shapes, the number of daily rings present, and their length and width measurements. The results revealed that sagittal otoliths and lapillus formed before the fertilized eggs hatched. During the larval and juvenile stages, sagittae evolved gradually, transforming from nearly round to oval structures, eventually adopting arrow- or pear-shaped forms. Similarly, lapillus transformed from nearly round to mussel-shaped structures. The first daily ring became evident on the 5th-day post-hatching, demonstrating a daily periodicity during the larval phase. We observed a direct relationship between incubation days (D) and the number of daily otolith increments (n), expressed as D = n + 5. This deposition trend exhibited a daily periodicity for both sagittae and lapillus. We also noted exponential correlations between the length (Ls, μm) and width (Ws, μm) of the sagittae and the total length (TL, mm). Contrastingly, the lapillus measurements demonstrated linear correlations. Furthermore, a linear relationship emerged between the sagittae and lapillus lengths: Ll= 0.3028Ls+ 28.534 (R2= 0.9366). Additionally, we found a similar linear relationship between the sagittae and lapillus widths: Wl = 0.3791Ws+ 21.508 (R2= 0.9426). The formation pattern of daily increments in lapillus was notably more distinct than that in sagittae, making it highly suitable for age identification and group recognition. This study not only contributes to the field of fish ecology but also provides a foundational understanding for future research. It can assist in reconstructing early life histories and inferences about the spawning periods and grounds of stocked Japanese flounder
Transcriptome profiling of the gills to air exposure in mud crab <em>Scylla paramamosain</em>
Get PDFThe mud crab Scylla paramamosain is a valuable commercial mariculture crab worldwide. During the ebb tide or when transported to market, crabs suffer underlying air exposure stress. Gills tissue is the first tissue to cope with this stress. In this study, the transcriptome of S. paramamosain gills from the control group (CG) and experimental group (EG) were sequenced, assembled, and compared. A total of 7,425,620,293 bp and 6,741,616,977 bp clean data were found in EG and CG, respectively. A total of 38,507 unigenes (42.78%) were annotated successfully. 13,626 differentially expressed genes (DEGs) were up-regulated, and 6,502 DEGs were down-regulated. The DEGs related to immunity, apoptosis, metabolism, and ion exchange were detected. DEGs were enriched significantly into the KEGG pathways related to metabolism and immunity. These results proved that more material and energy were required, and immune defense was enhanced when the crab was under air exposure stress. The present study provides the first-gill transcriptomic analysis challenged with air exposure stress in S. paramamosain under air exposure stress, which will be useful to clarify the molecular mechanisms of air exposure adaptation
A First Look at Genetic Diversity of <em>Metapenaeus ensis</em> Populations in Tam Giang – Cau Hai Lagoon, Vietnam
Get PDFThis study investigates the genetic diversity and population structure of the greasyback shrimp, Metapenaeus ensis (De Haan, 1844), within the Tam Giang – Cau Hai lagoon, Vietnam, by analyzing mtCOI genes from 91 individuals collected across four populations in nine sampling locations. High genetic diversity was found, with 34 unique haplotypes and 38 genetic variations identified. Most genetic variation occurred within populations (AMOVA), suggesting high gene flow. Low and non-significant Fst values and close genetic distances confirmed minimal differentiation among populations. These findings provide the first insights into M. ensis population genetics in this lagoon, informing conservation and management efforts. Understanding genetic diversity is crucial for sustainable management and conservation of marine species. This research aids in understanding population resilience, potential impacts of overfishing, and may assist in developing sustainable harvest strategies of this economically important shrimp species
Effects of dietary β-sitosterol supplementation on growth performance, antioxidant ability, and disease resistance in largemouth bass <em>Micropterus salmoides</em>
Get PDFβ-sitosterol, as the most abundant phytosterol, has been shown to exert multiple biological roles in in vitro and in vivo animal studies. Largemouth bass (Micropterus salmoides) is an economical freshwater-farmed species widely cultivated in China due to its nutritious and delicious meat. This study investigated the effects of dietary β-sitosterol supplementation on largemouth bass farming. In the study, largemouth bass were fed with five levels of β-sitosterol (0, 20, 40, 80, and 160 mg/kg) supplementation in a commercial feed for four weeks. The growth performance, antioxidant ability, intestinal structure, immune-related gene expression, and resistance to pathogens such as Aeromonas hydrophila and largemouth bass virus (LMBRaV) were detected. The results revealed that β-sitosterol supplementation in feed increased the weight gain rate of largemouth bass, with 40 mg/kg supplementation displaying the best effect. The serum biochemical indices all showed an increase, including glucose and alkaline phosphatase. The intestinal villus length and muscularis propria thickness also increased, accompanied by elevated digestive enzyme activities, which promoted digestion and absorption of nutrients. Meanwhile, the levels of total cholesterol, aspartate aminotransferase, and alanine aminotransferase in serum decreased, indicating reduced liver damage. In addition, β-sitosterol supplementation effectively enhanced the antioxidant capacity of largemouth bass by decreasing malondialdehyde and elevating superoxide dismutase. Immune-related gene expression also changed. Pathogen infection tests revealed that β-sitosterol supplementation in feed had a certain protective effect against infection in largemouth bass, with the protection rate against A. hydrophila being higher than LMBRaV. The 40 mg/kg β-sitosterol supplementation group exhibited the best results. Collectively, the results revealed that the β-sitosterol can promote growth, improve enzyme activity, stimulate intestinal digestion, increase immune gene expression, and induce disease resistance in largemouth bass, with the optimal supplementation dosage being 40 mg/kg. β-sitosterol might be an excellent feed additive in aquaculture
Classifiers and Definiteness in Longdu (Min Chinese)
Get PDFThis study examines a pair of classifiers in Longdu which show overt definiteness marking. In Longdu, the classifier pair nɛɪː¹¹ and ɑ⁵⁵ gives rise to an indefinite and a definite interpretation respectively. This pair of classifiers is compatible with nouns that denote discrete entities (e.g., apples) or homogeneous substances (e.g., water). The resulting [CLF - N] phrase expresses an accumulation of entities or substances with an underspecified number or amount. I call them ‘fuzzy’ classifiers, referring to the lack of precise quantity specification. The explicit definiteness marking in this pair of ‘fuzzy’ classifiers provides a valuable glimpse into the definiteness of classifiers when embedded in different kinds of nominal phrases. I present data showing that the indefinite and definite fuzzy classifiers in Longdu have different properties with respect to the licensing of NP-ellipsis, reduplication, and modification. Only the indefinite fuzzy classifier can license NP-ellipsis and reduplicate, while only the definite fuzzy classifier can appear in a [bare modifier - CLF - N] phrase. I will present evidence which suggests that the presence of two kinds of classifiers with definiteness contrast can be a phenomenon that spans over other Chinese varieties. All Longdu data presented here were gathered in my own fieldwork
Mannan oligosaccharide improves antioxidant capacity, non-specific immunity and protection against <em>Vibrio</em> disease and Typhoon stress in <em>Trachinotus ovatus</em> juveniles
No full textThis study examined the impact of varying doses of mannan oligosaccharide (MOS) supplementation on antioxidant defense, non-specific immunity, resistance to typhoon stress, and resistance to disease in Trachinotus ovatus. Fish groups C, M1, M2, and M3 were fed 1%, 0.3%, 0.6%, and 1% MOS-supplemented feed, respectively. On the 28th and 56th day of the feeding trial, samples from all groups were taken to measure the antioxidant and non-specific immunity parameters and challenged with Vibrio harvey. On the 32nd day, a typhoon hit the experimental site, and the survival rates of all groups were calculated. Results showed that on the 28th day, groups M2 and M3 showed considerably higher levels of antioxidant abilities (T-AOC), and groups M1 and M2 showed significantly enhanced non-specific immunity (AKP, LZM, and TP) levels than those of group C (p T. ovatus juveniles
Bacteriophage applications in aquaculture
Get PDFAquaculture has grown tremendously due to the big demand for its products. However, diseases affecting aquaculture and economic losses are worldwide problems and it needs low cost, sustainable, highly efficient, specific and eco-friendly therapeutants. Due to the rising up antibiotic resistant-microorganism, bacteriophage therapy has reinvigorated to replace antibiotics in agriculture, medicine, food safety and the environment. Likewise, it also holds great promise to avoid, control and treat bacteria in aquaculture to decrease the mortality level of different aquatic animal diseases. The isolation and characterization of new phages and phage application therapy to eliminate bacterial fish and shellfish pathogens such as Vibrio, Aeromonas, Pseudomonas, Lactococcus, Yersinia, Flavobacterium, and Streptococcus was gradually reported in aquaculture literature. The present review summarizes large-scale reports in vitro or in vivo use of aquaphage studies and applications in fish diseases from the 1980s to 2022 and future directions
Treatment of leachate solid wastewater and protein-rich biomass production using <em>Ceratophyllum demersum</em> (Linnaeus, 1753)
Get PDFThe present study, conducted in 2018, aimed to treat landfill leachate using the Ceratophyllum demersum plant and convert the wastewater nutrients into protein-rich biomass. The experiment was carried out for 45 days in an enriched medium with ½ Hoagland nutrient solution. Regarding the experimental setups, C. demersum cultivation was performed in four different dilution ratios (100%, 75%, 50%, and 25%) in the landfill leachate. The changes in the chemical properties of the wastewater (pH, NO₄⁻-N, NO₂⁻-N, NO₃⁻-N, and o-PO₄³⁻) were measured. The values in the leachate and after treatment were measured as follows: NH₄⁺-N ranged from 18.03 to 476.2 mg/L, NO₃⁻-N ranged from 5.0 to 33.98 mg/L, NO₂⁻-N ranged from 1.49 to 7.06 mg/L, and PO₄³⁻-P ranged from 27.99 to 145.4 mg/L. The protein yield (CP prot) in the experimental groups at the end of the 45-day study was as follows: T1 = 20.90%, T2 = 36.68 %, T3 = 41.78%, T4 = 47.43% and T5c = 49.56%. These results demonstrate that aquatic plants can be utilized in wastewater treatment and as animal feed due to their high protein yield. In my research, a completely nature-friendly treatment technique was used to reduce water pollution without using any chemicals