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Fulltext Deriving freshwater quality criteria for iron, lead, nickel, and zinc for protection of aquatic life in Malaysia

Shuhaimi-Othman M, Nadzifah Y, Nur-Amalina R, Umirah NS

ScientificWorldJournal, 2012;2012:861576.
PMID: 22919358 DOI: 10.1100/2012/861576

Freshwater quality criteria for iron (Fe), lead (Pb), nickel (Ni), and zinc (Zn) were developed with particular reference to aquatic biota in Malaysia, and based on USEPA's guidelines. Acute toxicity tests were performed on eight different freshwater domestic species in Malaysia which were Macrobrachium lanchesteri (prawn), two fish: Poecilia reticulata and Rasbora sumatrana, Melanoides tuberculata (snail), Stenocypris major (ostracod), Chironomus javanus (midge larvae), Nais elinguis (annelid), and Duttaphrynus melanostictus (tadpole) to determine 96 h LC(50) values for Fe, Pb, Ni, and Zn. The final acute value (FAV) for Fe, Pb, Ni, and Zn were 74.5, 17.0, 165, and 304.9 μg L(-1), respectively. Using an estimated acute-to-chronic ratio (ACR) of 8.3, the value for final chronic value (FCV) was derived. Based on FAV and FCV, a criterion maximum concentration (CMC) and a criterion continuous concentration (CCC) for Fe, Pb, Ni, and Zn that are 37.2, 8.5, 82.5, and 152.4 μg L(-1) and 9.0, 2.0, 19.9, and 36.7 μg L(-1), respectively, were derived. The results of this study provide useful data for deriving national or local water quality criteria for Fe, Pb, Ni, and Zn based on aquatic biota in Malaysia. Based on LC(50) values, this study indicated that N. elinguis, M. lanchesteri, N. elinguis, and R. sumatrana were the most sensitive to Fe, Pb, Ni, and Zn, respectively.

Matched MeSH terms: Fresh Water
Detection and genetic profiling of infectious hypodermal and haematopoietic necrosis virus (IHHNV) infections in wild berried freshwater prawn, Macrobrachium rosenbergii collected for hatchery production

Hazreen Nita MK, Kua BC, Bhassu S, Othman RY

Mol Biol Rep, 2012 Apr;39(4):3785-90.
PMID: 21755294 DOI: 10.1007/s11033-011-1155-x

Infectious hypodermal and haematopoietic necrosis virus (IHHNV) has been detected widely in penaeid culture facilities in Asia and the Americas. IHHNV infection on sub-adult and postlarvae of the giant freshwater prawn, Macrobrachium rosenbergii which had caused up to 80% mortalities was first reported in Southeast Taiwan in 2006. In Malaysia, although, there has been no report on IHHNV infections in M. rosenbergii, preliminary work suggests that there is an urgent need to setup a screening protocol for IHHNV for both wild and cultured populations. In this study, polymerase chain reaction based screening was carried out on 30 randomly sampled berried wild M. rosenbergii before and after spawning. All samples did not showed any sign of IHHNV infection. However, the results showed that 20% of the samples were IHHNV positive. Sequence analysis of the amplified band using NCBI-BLAST showed that the putative IHHNV sequence had 98% nucleotide sequence (388 bp) identity with the IHHNV isolate AC-05-005 non-structural protein 1 gene and seven other IHHNV strains in the data bank further affirming the suggestion on the presence of IHHNV in wild freshwater prawn populations in Malaysia.

Matched MeSH terms: Fresh Water*
Detection and molecular characterization of Giardia isolated from recreational lake water in Malaysia

Lim YA, Ramasame SD, Mahdy MA, Sulaiman WY, Smith HV

Parasitol Res, 2009 Dec;106(1):289-91.
PMID: 19705155 DOI: 10.1007/s00436-009-1602-y

Nine 50-l surface water samples from a Malaysian recreational lake were examined microscopically using an immunomagnetisable separation-immunofluorescent method. No Cryptosporidium oocysts were detected, but 77.8% of samples contained low numbers of Giardia cysts (range, 0.17-1.1 cysts/l), which were genetically characterised by SSU rRNA gene sequencing. Genotype analyses indicated the presence of Giardia duodenalis assemblage A suggesting potential risk to public health. The present study represents the first contribution to our knowledge of G. duodenalis assemblages in Malaysian recreational water.

Matched MeSH terms: Fresh Water/parasitology*
Determination of diffusion coefficients and activation energy of selected organic liquids using reversed-flow gas chromatographic technique

Khalisanni Khalid, Rashid Atta Khan, Sharifuddin Mohd. Zain

Sains Malaysiana, 2012;41:1109-1116.

Evaporation of vaporize organic liquid has ecological consequences when the compounds are introduced into both freshwater and marine environments through industrial effluents, or introduced directly into the air from industrial unit processes such as bioreactors and cooling towers. In such cases, a rapid and simple method are needed to measure physicochemical properties of the organic liquids. The Reversed-Flow Gas Chromatography (RF-GC) sampling technique is an easy, fast and accurate procedure. It was used to measure the diffusion coefficients of vapors from liquid into a carrier gas and at the same time to determine the rate coefficients for the evaporation of the respective liquid. The mathematical expression describing the elution curves of the samples peaks was derived and used to calculate the respective parameters for the selected liquid pollutants selected such as methanol, ethanol, 1-propanol, 1-butanol, n-pentane, n-hexane, n-heptane and n-hexadecane, evaporating into the carrier gas of nitrogen. The values of diffusion coefficients found were compared
with those calculated theoretically or reported in the literature. The values of evaporation rate were used to determine the activation energy of respective samples using Arrhenius equation. An interesting finding of this work is by using an alternative mathematical analysis based on equilibrium at the liquid-gas interphase, the comparison leads to profound
agreement between theoretical values of diffusion coefficients and experimental evidence.

Matched MeSH terms: Fresh Water
Determination of hexaconazole in field samples of an oil palm plantation

Muhamad H, Zainol M, Sahid I, Abu Seman I

Drug Test Anal, 2012 Aug;4 Suppl 1:112-7.
PMID: 22851367 DOI: 10.1002/dta.1351

In oil palm plantations, the fungicide hexaconazole is used to control Ganoderma infection that threatens to destroy or compromisethe palm. The application of hexaconazole is usually through soil drenching, trunk injection, or a combination of these two methods. It is therefore important to have a method to determine the residual amount of hexaconazole in the field such as in samples of water, soil, and leaf to monitor the use and fate of the fungicide in oil palm plantations. This study on the behaviour of hexaconazole in oil palm agro-environment was carried out at the UKM-MPOB Research Station, Bangi Lama, Selangor. Three experimental plots in this estate with 7-year-old Dura x Pisifera (DxP) palms were selected for the field trial. One plot was sprayed with hexaconazole at the manufacturer's recommended dosage, one at double the recommended dosage, and the third plot was untreated control. Hexaconazole residues in the soil, leaf, and water were determined before and after fungicide treatment. Soil samples were randomly collected from three locations at different depths (0-50 cm) and soil collected fromthe same depth were bulked together. Soil, water, and palm leaf were collected at -1 (day before treatment), 0 (day of treatment), 1, 3, 7, 14, 21, 70, 90, and 120 days after treatment. Hexaconazole was detected in soil and oil palm leaf, but was not detected in water from the nearby stream.

Matched MeSH terms: Fresh Water/analysis*
Determination of radioactive elements and heavy metals in sediments and soil from domestic water sources in northern peninsular Malaysia

Muhammad BG, Jaafar MS, Abdul Rahman A, Ingawa FA

Environ Monit Assess, 2012 Aug;184(8):5043-9.
PMID: 21901308 DOI: 10.1007/s10661-011-2320-3

Soil serves as a major reservoir for contaminants as it posseses an ability to bind various chemicals together. To safeguard the members of the public from an unwanted exposure, studies were conducted on the sediments and soil from water bodies that form the major sources of domestic water supply in northern peninsular Malaysia for their trace element concentration levels. Neutron Activation Analysis, using Nigeria Research Reactor-1 (NIRR-1) located at the Centre for Energy Research and Training, Zaria, Nigeria was employed as the analytical tool. The elements identified in major quantities include Na, K, and Fe while As, Br, Cr, U, Th, Eu, Cs, Co, La, Sm, Yb, Sc, Zn, Rb, Ba, Lu, Hf, Ta, and Sb were also identified in trace quantities. Gamma spectroscopy was also employed to analyze some soil samples from the same area. The results indicated safe levels in terms of the radium equivalent activity, external hazard index as well as the mean external exposure dose rates from the soil. The overall screening of the domestic water sources with relatively high heavy metals concentration values in sediments and high activity concentration values in soil is strongly recommended as their accumulation overtime as a consequence of leaching into the water may be of health concern to the members of the public.

Matched MeSH terms: Fresh Water/chemistry
Dickeya undicola sp. nov., a novel species for pectinolytic isolates from surface waters in Europe and Asia

Oulghazi S, Pédron J, Cigna J, Lau YY, Moumni M, Van Gijsegem F, et al.

Int J Syst Evol Microbiol, 2019 Aug;69(8):2440-2444.
PMID: 31166160 DOI: 10.1099/ijsem.0.003497

Strains 2B12T, FVG1-MFV-O17 and FVG10-MFV-A16 were isolated from fresh water samples collected in Asia and Europe. The nucleotide sequences of the gapA barcodes revealed that all three strains belonged to the same cluster within the genus Dickeya. Using 13 housekeeping genes (fusA, rpoD, rpoS, glyA, purA, groEL, gapA, rplB, leuS, recA, gyrB, infB and secY), multilocus sequence analysis confirmed the existence of a new clade. When the genome sequences of these three isolates and other Dickeya species were compared, the in silico DNA-DNA hybridization and average nucleotide identity values were found to be no more than 45.50 and 91.22 %, respectively. The closest relative species was Dickeya fangzhongdai. Genome comparisons also highlighted genetic traits differentiating the new strains from D. fangzhongdai strains DSM 101947T (=CFBP 8607T) and B16. Phenotypical tests were performed to distinguish the three strains from D. fangzhongdai and other Dickeya species. The name Dickeya undicola sp. nov. is proposed with strain 2B12T (=CFBP 8650T=LMG 30903T) as the type strain.

Matched MeSH terms: Fresh Water/microbiology*
Diel osmorespiration rhythms of juvenile marble goby (Oxyeleotris marmorata)

Lim LS, Tan SY, Tuzan AD, Kawamura G, Mustafa S, Rahmah S, et al.

Fish Physiol Biochem, 2020 Aug;46(4):1621-1629.
PMID: 32430644 DOI: 10.1007/s10695-020-00817-5

Oxyeleotris marmorata is an ambush predator. It is known for slow growth rate and high market demand. Farming of O. marmorata still remains a challenge. In order to establish a proper feeding practice to stimulate growth, knowledge of its metabolic processes and cost should be examined. Therefore, this study was designed to investigate the diel osmorespiration rhythms of O. marmorata in response to feeding challenge by using an osmorespirometry assay. The results have shown that oxygen consumption rate of the fed fish was approximately 3 times higher than that of the unfed fish in early evening to support specific dynamic action. Digestion and ingestion processes were likely to be completed within 18-20 h in parallel with the ammonia excretion noticeable in early morning. Under resting metabolism, metabolic oxygen consumption was influenced by diel phase, but no effect was noted in ammonia excretion. As a nocturnal species, O. marmorata exhibited standard aerobic metabolic mode under dark phase followed by light phase, with high oxygen consumption rate found in either fed or unfed fish. It can be confirmed that both the diel phase and feeding have a significant interactive impact on oxygen consumption rate, whereas ammonia metabolism is impacted by feeding state. High metabolic rate of O. marmorata supports the nocturnal foraging activity in this fish. This finding suggested that feeding of O. marmorata should be performed during nighttime and water renewal should be conducted during daytime.

Matched MeSH terms: Fresh Water
Differentiation and adaptive radiation of amphibious gobies (Gobiidae: Oxudercinae) in semi-terrestrial habitats

Polgar G, Sacchetti A, Galli P

J Fish Biol, 2010 Nov;77(7):1645-64.
PMID: 21078024 DOI: 10.1111/j.1095-8649.2010.02807.x

During several surveys made in the region of the lower Fly River and delta, Papua New Guinea, nine species of oxudercine gobies (Gobiidae: Oxudercinae) were recorded: Boleophthalmus caeruleomaculatus, Oxuderces wirzi, Periophthalmodon freycineti, Periophthalmus darwini, Periophthalmus novaeguineaensis, Periophthalmus takita, Periophthalmus weberi, Scartelaos histophorus and Zappa confluentus. An exploratory multivariate analysis of their habitat conditions discriminated five guilds, differentially distributed in habitats with different quantities of environmental water and three guilds corresponding to different levels of salinity. A partial correspondence between phylogenetic and ecological categories suggested the presence of parallel adaptive radiations within different genera. In particular, the species found in the most terrestrial habitats (P. weberi) was also found in the widest range of conditions, suggesting that colonization of extreme semi-terrestrial and freshwater habitats by this species was facilitated by eurytypy. It is proposed that these findings provide insight into convergent adaptations for the vertebrate eco-evolutionary transition from sea to land.

Matched MeSH terms: Fresh Water
Distribution and behaviour of nitrogen compounds in the surface water of the Sungai Terengganu estuary, southern waters of South China sea, Malaysia

Suhaimi Suratman, Azyyati Abdul Aziz, Norhayati Mohd Tahir, Lee HL

Sains Malaysiana, 2018;47:651-659.

A study was carried out to determine the distribution and behaviour of nitrogen (N) compounds (nitrite, nitrate, ammonia,
dissolved and particulate organic nitrogen) in Sungai Terengganu estuary (TRE). Surface water samples were collected
during ebb neap and spring tides for the longitudinal survey along the salinity gradient. The results indicated that all N
compounds behave non-conservatively with addition during both tidal cycles, except for nitrate which exhibited removal
behaviour during spring tide. In general, higher concentration of N compounds was observed during spring tide compared
to neap tide. It is suggested that during spring tide, stronger water turbulence resulted in resuspension of nutrients in
bottom sediment and lead to the increase in N compounds concentrations in the surface water. The diurnal survey for the
freshwater station showed that the concentrations of N compounds follow the ebb and flood variations, whereas for the
coastal station the reverse trend was observed. Comparisons with a previous study under similar tidal conditions show
there was an increase in nitrite and ammonia concentrations in TRE, which was probably due to increase in discharge
from the rapid development activities around this area. In addition, the presence of a breakwater at the lower part of
the estuary may also contribute to the high nutrient content in the estuary due to restricted outflow of nutrients to the
coastal area. Overall, the results from this study highlighted the importance of monitoring the N compounds for future
protection of the estuary.

Matched MeSH terms: Fresh Water
Distribution and health risk assessment of trace metals in freshwater tilapia from three different aquaculture sites in Jelebu Region (Malaysia)

Low KH, Zain SM, Abas MR, Md Salleh K, Teo YY

Food Chem, 2015 Jun 15;177:390-6.
PMID: 25660902 DOI: 10.1016/j.foodchem.2015.01.059

The trace metal concentrations in edible muscle of red tilapia (Oreochromis spp.) sampled from a former tin mining pool, concrete tank and earthen pond in Jelebu were analysed with microwave assisted digestion-inductively coupled plasma-mass spectrometry. Results were compared with established legal limits and the daily ingestion exposures simulated using the Monte Carlo algorithm for potential health risks. Among the metals investigated, arsenic was found to be the key contaminant, which may have arisen from the use of formulated feeding pellets. Although the risks of toxicity associated with consumption of red tilapia from the sites investigated were found to be within the tolerable range, the preliminary probabilistic estimation of As cancer risk shows that the 95th percentile risk level surpassed the benchmark level of 10(-5). In general, the probabilistic health risks associated with ingestion of red tilapia can be ranked as follows: former tin mining pool > concrete tank > earthen pond.

Matched MeSH terms: Fresh Water
Distribution and normalization of some metals in surface sediments from South Caspian Sea

Sohrabi T, Ismail A, Nabavi MB

Bull Environ Contam Toxicol, 2010 Nov;85(5):502-8.
PMID: 20957347 DOI: 10.1007/s00128-010-0112-z

Surface sediments along the south of Caspian Sea were collected to evaluate the contamination of heavy metals. The result ranged (μg/g, Fe% dw): Pb(13.06-33.48); Ni(18.01-69.63); Cd(0.62-1.5); Zn(30.11-87.88); Cu(5.86-26.37) and Fe(1.8-4%) respectively. Cadmium showed higher EF when compared to other sites. Geoaccumulation Index value for Cd in most stations was classified as moderately contaminated and moderately to strongly contaminated, as well as the average of I(geo) of Cd (1.77 ± 0.35) suggested that surface sediments of Caspian coast were moderately polluted by this metal. The result of the Pearson correlation showed that there were significant positive associations between Ni, Cd and Zn (r = 0.44-0.76; p < 0.01).

Matched MeSH terms: Fresh Water/chemistry*
Fulltext Distribution and prevalence of chloramphenicol-resistance gene in Escherichia coli isolated from aquaculture and other environment

Ng, K.H., Samuel, L., Kathleen, M.M., Leong, S.S., Felecia, C.

International Food Research Journal, 2014;21(4):1321-1325.
MyJurnal

In Malaysia, the aquaculture industry, particularly the production of freshwater aquaculture fish, is growing rapidly. Nevertheless, the illegal use of banned antimicrobial agents such as chloramphenicol in aquaculture has become a major concern in relation to the safety of consumers and also the development of drug-resistant strains in bacteria. Driven by those factors, the main intention of this study was to determine the prevalence and types of chloramphenicol resistance genes in E. coli isolated from aquaculture and other environmental waters. The respective chloramphenicol-resistance genes in the isolates were detected by multiplex PCR with four sense primers C-1, C-2, C-3, C-4 and one antisense primer C-R for targeting cat I, cat II, cat III and cat IV genes, respectively. Out of 27 E. coli isolated, 19 were resistant to chloramphenicol. Cat I, cat II, cat III and cat IV genes were detected in 19, 13, 10, and 6 of the E. coli isolates, respectively. The results of this study revealed that chloramphenicol-resistance E. coli is present in aquaculture and environmental waters, in the study area. This finding suggested that although banned, there could be illegal usage of chloramphenicol antibiotic in local aquaculture. The bacteria in aquaculture may have spread to other environmental water through disposal of aquaculture waste water to other environments.

Matched MeSH terms: Fresh Water
Distribution of linear alkylbenzenes (LABs) in riverine and coastal environments in South and Southeast Asia

Isobe KO, Zakaria MP, Chiem NH, Minh le Y, Prudente M, Boonyatumanond R, et al.

Water Res, 2004 May;38(9):2448-58.
PMID: 15142807

This paper reports the result of sewage pollution monitoring conducted in South and Southeast Asia during 1998-2003 using linear alkylbenzenes (LABs) as molecular tracers of sewage contamination. Eighty-nine water samples collected from Malaysia, Vietnam, and Japan (Tokyo), and 161 surface sediment samples collected from Tokyo, Thailand, Malaysia, Philippines, Vietnam, Cambodia, Indonesia, and India were analyzed for alkylbenzenes. The concentration range of SigmaLABs in river water particles in Southeast Asia (<0.005-0.913 microg/L) was comparable to or higher than those found in Tokyo (<0.005-0.638 microg/L). I/E ratios (a ratio of internal to external isomers of LABs) in tropical Asian waters were close to the value of LABs in raw sewage ( approximately 1) and much lower than those in secondary effluents (3-5). This suggests that untreated or inadequately treated sewage is discharged into the water. SigmaLABs concentrations in sediments from South and Southeast Asia ranged from <0.002-42.6 microg/g-dry with the highest concentration occurring at several populous cities. Low I/E ratios of the sediments with high SigmaLABs concentrations suggest a heavy load of untreated sewage. Clearly in view of the current data and evidence of the implications of sewage pollution, this paper highlights the necessity of the continuation of water treatment system improvement in tropical Asia.

Matched MeSH terms: Fresh Water/chemistry
Fulltext Divergent effects of climate change on future groundwater availability in key mid-latitude aquifers

Wu WY, Lo MH, Wada Y, Famiglietti JS, Reager JT, Yeh PJ, et al.

Nat Commun, 2020 07 24;11(1):3710.
PMID: 32709871 DOI: 10.1038/s41467-020-17581-y

Groundwater provides critical freshwater supply, particularly in dry regions where surface water availability is limited. Climate change impacts on GWS (groundwater storage) could affect the sustainability of freshwater resources. Here, we used a fully-coupled climate model to investigate GWS changes over seven critical aquifers identified as significantly distressed by satellite observations. We assessed the potential climate-driven impacts on GWS changes throughout the 21st century under the business-as-usual scenario (RCP8.5). Results show that the climate-driven impacts on GWS changes do not necessarily reflect the long-term trend in precipitation; instead, the trend may result from enhancement of evapotranspiration, and reduction in snowmelt, which collectively lead to divergent responses of GWS changes across different aquifers. Finally, we compare the climate-driven and anthropogenic pumping impacts. The reduction in GWS is mainly due to the combined impacts of over-pumping and climate effects; however, the contribution of pumping could easily far exceed the natural replenishment.

Matched MeSH terms: Fresh Water
Diversity and distribution of stream fishes of Pulau Langkawi, Malaysia

Izzati Adilah Azmir, Abdullah Samat

Sains Malaysiana, 2010;39.

Fishes from five streams in Gunung Machinchang and six streams in Gunung Raya areas of Pulau Langkawi were surveyed with the aim to investigate their diversity and distribution. Fish samples were collected from 23rd to 29th November 2007. Samplings took place along the 50 m reach of each of the site using an electrofisher and scoop nets. A total of 619 individuals of fish comprising 27 species and 14 families were recorded. Sixty-six percent from the taxa listed were of the cyprinids and Puntius binotatus was the most abundant species. Carassius auratus auratus was recorded for the first time in Pulau Langkawi. Streams of the Gunung Machinchang area were dominated by secondary freshwater fish species, but in the Gunung Raya area the streams were dominated by primary freshwater fish species. The highest diversity of fish was recorded for Sg. Kubang Badak with Simpson Index Ds = 0.838 and the lowest was for Sg. Perangin with Ds = 0.450. The highest evenness index of fish species was detected for Sg. Temurun with Es = 0.684 and the lowest was for Sg. Perangin with Es = 0.299. Species overlapping between streams of the two areas was 9.6%.

Matched MeSH terms: Fresh Water
Diversity, extinction risk and conservation of Malaysian fishes

Chong VC, Lee PK, Lau CM

J Fish Biol, 2010 Jun;76(9):2009-66.
PMID: 20557654 DOI: 10.1111/j.1095-8649.2010.02685.x

A total of 1951 species of freshwater and marine fishes belonging to 704 genera and 186 families are recorded in Malaysia. Almost half (48%) are currently threatened to some degree, while nearly one third (27%) mostly from the marine and coral habitats require urgent scientific studies to evaluate their status. Freshwater habitats encompass the highest percentage of threatened fish species (87%) followed by estuarine habitats (66%). Of the 32 species of highly threatened (HT) species, 16 are freshwater and 16 are largely marine-euryhaline species. Fish extinctions in Malaysia are confined to two freshwater species, but both freshwater and marine species are being increasingly threatened by largely habitat loss or modification (76%), overfishing (27%) and by-catch (23%). The most important threat to freshwater fishes is habitat modification and overfishing, while 35 species are threatened due to their endemism. Brackish-water, euryhaline and marine fishes are threatened mainly by overfishing, by-catch and habitat modification. Sedimentation (pollution) additionally threatens coral-reef fishes. The study provides recommendations to governments, fish managers, scientists and stakeholders to address the increasing and unabated extinction risks faced by the Malaysian fish fauna.

Matched MeSH terms: Fresh Water
Drowning

Sarvesvaran R

Malays J Pathol, 1992 Dec;14(2):77-83.
PMID: 1304628

A body recovered from the water does not necessarily imply that death was due to drowning. The diagnosis of drowning is discussed together with the significance of the "diatom" and biochemical tests.

Matched MeSH terms: Fresh Water
Fulltext Dynamics of the Water Circulations in the Southern South China Sea and Its Seasonal Transports

Daryabor F, Ooi SH, Samah AA, Akbari A

PLoS One, 2016;11(7):e0158415.
PMID: 27410682 DOI: 10.1371/journal.pone.0158415

A three-dimensional Regional Ocean Modeling System is used to study the seasonal water circulations and transports of the Southern South China Sea. The simulated seasonal water circulations and estimated transports show consistency with observations, e.g., satellite altimeter data set and re-analysis data of the Simple Ocean Data Assimilation. It is found that the seasonal water circulations are mainly driven by the monsoonal wind stress and influenced by the water outflow/inflow and associated currents of the entire South China Sea. The intrusion of the strong current along the East Coast of Peninsular Malaysia and the eddies at different depths in all seasons are due to the conservation of the potential vorticity as the depth increases. Results show that the water circulation patterns in the northern part of the East Coast of Peninsular Malaysia are generally dominated by the geostrophic currents while those in the southern areas are due solely to the wind stress because of negligible Coriolis force there. This study clearly shows that individual surface freshwater flux (evaporation minus precipitation) controls the sea salinity balance in the Southern South China Sea thermohaline circulations. Analysis of climatological data from a high resolution Regional Ocean Modeling System reveals that the complex bathymetry is important not only for water exchange through the Southern South China Sea but also in regulating various transports across the main passages in the Southern South China Sea, namely the Sunda Shelf and the Strait of Malacca. Apart from the above, in comparision with the dynamics of the Sunda Shelf, the Strait of Malacca reflects an equally significant role in the annual transports into the Andaman Sea.

Matched MeSH terms: Fresh Water
Fulltext Dystrophin gene expression and intracellular calcium changes in the giant freshwater prawn, Macrobrachium rosenbergii, in response to white spot symptom disease infection

Noor AF, Soo TCC, Ghani FM, Goh ZH, Khoo LT, Bhassu S

Heliyon, 2017 Dec;3(12):e00446.
PMID: 29322096 DOI: 10.1016/j.heliyon.2017.e00446

Background: Dystrophin, an essential protein functional in the maintenance of muscle structural integrity is known to be responsible for muscle deterioration during white spot syndrome virus (WSSV) infection among prawn species. Previous studies have shown the upregulation of dystrophin protein in Macrobrachium rosenbergii (the giant freshwater prawn) upon white spot syndrome virus (WSSV) infection. The literature has also suggested the important role of calcium ion alterations in causing such muscle diseases. Thus, the interest of this study lies within the linkage between dystrophin functioning, intracellular calcium and white spot syndrome virus (WSSV) infection condition.
Methods: In this study, the dystrophin gene from M. rosenbergii (MrDys) was first characterised followed by the characterization of dystrophin gene from a closely related shrimp species, Penaeus monodon (PmDys). Dystrophin sequences from different phyla were then used for evolutionary comparison through BLAST analysis, conserved domain analysis and phylogenetic analysis. The changes in mRNA expression levels of dystrophin and the alteration of intracellular calcium concentrations in WSSV infected muscle cells were then studied.
Results: A 1246 base pair long dystrophin sequence was identified in the giant freshwater prawn, Macrobrachium rosenbergii (MrDys) followed by 1082 base pair long dystrophin sequence in P. monodon (PmDys). Four conserved domains were identified from the thirteen dystrophin sequences compared which were classified into 5 different phyla. From the phylogenetic analysis, aside from PmDys, the characterised MrDys was shown to be most similar to the invertebrate phylum of Nematoda. In addition, an initial down-regulation of dystrophin gene expression followed by eventual up-regulation, together with an increase in intracellular calcium concentration [Ca2+]
i
were shown upon WSSV experimental infection.
Discussion: Both the functionality of the dystrophin protein and the intracellular calcium concentration were affected by WSSV infection which resulted in progressive muscle degeneration. An increased understanding of the role of dystrophin-calcium in MrDys and the interactions between these two components is necessary to prevent or reduce occurrences of muscle degeneration caused by WSSV infection, thereby reducing economic losses in the prawn farming industry from such disease.

Matched MeSH terms: Fresh Water

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