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Penambahbaikan protein, lipid and asid lemak dalam mesocyclops leuckarti (claus, 1857) untuk peningkatan pertumbuhan dan kehidupan larva pangasius nasutus (bleeker, 1863)
Get PDFKAJIAN PENGARUH PERUBAHAN IKLIM TERHADAP PENGALIR ATASAN DAN CIRI ANGIN DI SEPANJANG PANTAI TIMUR SEMENANJUNG MALAYSIA DI BAWAH SENARIO PELEPASAN MASA HADAPAN RCP4.5 DAN RCP8.5 MENGGUNAKAN SIMULASI PELBAGAI MODEL CORDEX ASIA TENGGARA
No full textCost-benefit analysis of ballast water treatment for three major port clusters in China: evaluation of different scenario strategies
No full textThe expansion of maritime trade has led to the introduction of invasive species into aquatic ecosystems through ballast water discharge. China, being a major player in global trade and manufacturing, has experienced negative impacts on its coastal ecosystems and marine biodiversity
Influence of Salinity on the Survival Rate of Fertilized Chum Salmon (Oncorhynchus keta) Eggs
No full textChum salmon (Oncorhynchus keta) exhibit a remarkable ability to adapt to changes in salinity
during their life cycle. However, the fertilized egg stages are sensitive to salinity, affecting ontogeny
and hatching. This study investigated the effect of salinity (0, 1, 3, and 5 PSU) on the survival of two
developmental stages (<1 day after fertilization and <1 day after the eyed-egg stage) of fertilized
eggs. Based on the experimental results, we assessed the spawning ground environment using the
in situ salinity data of the Namdae River from 1997 to 2002, where the largest number of salmon in
Korea migrate to spawn. Survival of the <1-day-old fertilized eggs decreased sharply at 3 PSU or
more, and all eggs died at 5 PSU. Hatching of the eyed-egg stage occurred under all environmental
conditions. After 2010, the salinity of the layer of water in contact with the sediment in the lower
reaches of the river increased (>6.9 PSU) with the frequency of high waves. Overall, the function of
the lower river in spawning and hatching is weakening. This study enhances our understanding of
the effects of climate change, including increased wave activity, on salmon spawning grounds
Molecular characterization, spatiotemporal expression patterns of fatty acid elongase (elovl8) gene, and its transcription changes in response to different diet stimuli in yellow catfish (Pelteobagrus fulvidraco)
No full textElongase of very long-chain fatty acid 8 (Elovl8) is a new member identified in the
Elovl family that is involved in the synthesis of highly unsaturated fatty acids
(HUFAs). However, the evolutionary and physiological roles of this enzyme are
still largely unknown. In the present study, the elovl8 gene was identified and
characterized from yellow catfish Pelteobagrus fulvidraco, and then its
evolutionary and molecular characteristics as well as transcriptional changes in
response to various nutritional status were determined. Results showed that the
open reading frame (ORF) of elovl8 was 795 bp in length, encoding a protein of
264 amino acids. Multiple sequences alignment showed that the yellow catfish
Elovl8 was highly conserved with other homologs in teleosts, sharing similar
structural characteristics (including six conserved transmembrane a-helical
domains, four conserved elongase motifs, and three highly conserved cysteine
residues). Meanwhile, comparisons of genetic synteny confirmed that the elovl8
gene identified from the yellow catfish was the homolog of elovl8b in other
teleosts, and thus, the elovl8a gene was lost in the genome of the yellow catfish.
Gene structure analysis revealed that the elovl8b gene contained eight exons and
seven introns, which was highly conserved in teleosts, implying the functional
conservation among various fish species. Tissue distribution analysis detected byreal-time quantitative PCR (RT-qPCR) showed that the elovl8 gene was
extensively expressed in all detected tissues except eyes, with high expression
levels in the intestine and liver. Temporal expression analysis revealed that the
expression level of elovl8 was stably expressed in the early 12 h after fertilization,
and then dramatically decreased at 24, 48, 72, and 96 h after fertilization,
implying that elovl8 is required for HUFA biosynthesis in the early
development stages. Functional experiments showed that the expression of
the elovl8 gene was stimulated after feeding with egg yolk but was not obviously
affected after feeding with halogenated worms, indicating that diets full of
HUFAs can inhibit the expression of elovl8 in yellow catfish. Our findings will
help us to better understand the evolutionary and functional characteristics of
elovl8 in teleosts, and lay a solid basis for investigating the regulation mechanism
of HUFA biosynthesis
Ascorbate?glutathione cycle involving in response of Bangia fuscopurpurea (Bangiales, Rhodophyta) to hyposalinity
No full textBangia fuscopurpurea is a widespread intertidal seaweed that is commercially
cultured in China. This seaweed is frequently exposed to hyposalinity stress, but
little is known about the adaptation mechanisms. Ascorbate?glutathione (AsA?GSH)
cycle plays important roles in many organisms under a variety of abiotic stress,
including hyposaline stress. In this study, we investigated the response of key
metabolites and enzymes involved in the AsA?GSH cycle of B. fuscopurpurea
under hyposalinity, with the addition of exogenous GSH and Lbuthioninesulfoximine
(BSO). The quantification of BfAPX gene expression was assessed
across varied treatment regimens. And the putative interaction proteins of BfAPX
were screened by yeast two hybrid system. It was found that under hyposalinity (15
and/or 0 psu), the content of reduced glutathione (GSH), total glutathione (GSH+
oxidized glutathione, GSSG) and cysteine, the ratio of GSH/GSSG and ascorbic acid
(AsA)/ dehydroascorbic acid (DHA), and the activity of ascorbic acid peroxidase (APX)
and monodehydroascorbate reductase (MDHAR) was significantly up-regulated.
The hyposality-promoted GSH/GSSG was weakened while the glutathione
reductase (GR) activity was promoted by adding exogenous GSH and BSO. The
hyposality-promoted AsA/DHA ratio was strengthened by exogenous GSH but
weakened by BSO. The dehydroascorbate reductase (DHAR) activity had no
significant changes either with or without exogenous GSH under all salinities,
while DHAR activity together with DHA content was enhanced by BSO. The
expression of APX gene markedly increased under hyposalinity+BSO treatment.
Putative interacting proteins of APX, including glutamate dehydrogenase 1a and
fructose diphosphate aldolase, were identified through screening. The results
indicated that the AsA?GSH cycle was involved in response of B. fuscopurpurea to
hyposalinity by means of increasing GSH/GSSG ratio (through promoting GSH
biosynthesis pathway and GSH regeneration from GSSG by GR catalyzation) and
AsA/DHA ratio (promoting AsA regeneration through MDHAR). These findings would
contribute to improve the aquaculture of this promising economic species and
unveil how intertidal seaweeds address the global climate challenge
A study of the feeding characteristics of a small and medium-sized copepod species (Sinocalanus tenellus) using genetic analysis techniques: seasonal comparison of potential/eaten food sources focused on phytoplankton
No full textIn aquatic ecosystem, the food web structure based on composition and
abundance of prey species influences the feeding characteristics of predators,
resulting in changes to the structure and function of the entire food web.
Zooplankton mainly feed on phytoplankton, but the method of analyzing the
feed source through visual and microscopic identification of gut contents has
limitations in applicable species and the low resolution of the analysis results. In
this study, potential vs. eaten food sources of Sinocalanus tenellus, a small and
medium-sized copepod species dominant in brackish waters, were analyzed
based on phytoplankton operational taxonomic units detected from the habitat?s
raw water and treated whole bodies of S. tenellus. The alpha diversity and
dominant/subdominant species of each potential and eaten food source were
identified, and they were compared across seasons. At the same time, the
feeding selectivity index (Ei) was calculated by identifying overlapping species
in the potential vs. eaten food source pool. As a result, it was confirmed that not
all surrounding potential food sources are fed on by S. tenellus, and that its diet
can vary depending on the presence/absence of preferred prey. Metabarcoding
techniques is considered to be an effective way to identify fluctuations in major
food sources of zooplankton at the genus or species level. If uncertainties such
as incomplete species identification as identified from the results of this study are
improved through improving of analysis methods such as application of speciesspecific
primers in the future, it will be useful for securing information on the
feeding characteristics of small to medium-sized zooplankton
Assessment of growth and mortality parameters and exploitation rate to monitor the population status of wild catfish, Pangasius nasutus (Bleeker, 1863) in Pahang River, Malaysia
No full textPangasius nasutus is one of the popular freshwater fish species in Pahang River,
Malaysia because of its economic value, however, the high exploitation rate, occurrence of invasive
alien species in the same ecosystem, and habitat modification threatened its population sustainability.
This study aimed to enhance the existing information database of a species that has limited data
availability and to monitor its population status. The monthly samplings were conducted from the
upstream to the downstream of the Pahang River for 12 consecutive months from May 2021 to April
2022. The FiSAT II software was used to analyse population parameters from the length frequency
data. The results revealed the asymptotic length (L?) = 661.50 mm, growth coefficient (K) = 0.18
year-1, growth performance index (??) = 4.90, the maximum age (Tmax) = 16.67, total mortality (Z)
= 0.61 year-1, natural mortality (M) = 0.25 year-1, fishing mortality (F) = 0.36 year-1 and exploitation
rate (E) = 0.59 year-1. The results also showed that P. nasutus exhibits a slow growth rate, rendering
it more susceptible to overfishing. This study also indicated that the current level of exploitation of
P. nasutus population in the Pahang River appears to be appropriate. However, it is recommended
that a precautionary strategy be adopted to mitigate the risk of overexploitation
