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Electron microscopy determination of crystallographic polarity of aluminum nitride thin films

Kuwano N, Kaur J, Rahmah S

Micron, 2019 01;116:80-83.
PMID: 30321742 DOI: 10.1016/j.micron.2018.09.014

Aluminum nitride (AlN) crystallizes usually in the wurtzite structure (P63mc) and it has a crystallographic polarity. In this work, the polarity in AlN was characterized by using several methods of transmission electron microscopy (TEM) in order to examine their applicability. AlN was deposited by metalorganic vapor phase epitaxy (MOVPE), followed by annealing at 1550 °C. TEM samples were prepared by using a focused ion beam (FIB) mill. Observation was performed with microscopes of JEM-2100, JEM-ARM200 F and FEI Titan Cubed G2 at Kyushu University (Japan), and the following results were obtained. (1) Conventional TEM imaging: Under a diffraction condition with hkil = 0002, inversion domains or an inversion domain boundary (IDB) was observed. (2) Scanning TEM (STEM) High-Angle Annular Dark Field (HAADF) imaging: Even when atomic column images of Al and N are not resolved completely from each other, the polarity was determined from the shape of atomic column images. (3) Scanning moire fringe imaging: The moire fringe pattern indicated the position of IDB and determine the direction of polarity. (4) Convergent beam electron diffraction (CBED): CBED was applicable for determination of the polarity in AlN at the acceleration voltage of 120 kV. Hence the polarity, direction of polarity and inversion domain boundary was determined using advanced TEM methods.
Fulltext Effects of droplet-vitrification cryopreservation based on physiological and antioxidant enzyme activities of Brassidium shooting star orchid

Rahmah S, Ahmad Mubbarakh S, Soo Ping K, Subramaniam S

ScientificWorldJournal, 2015;2015:961793.
PMID: 25861687 DOI: 10.1155/2015/961793

Protocorm-like bodies (PLBs) of Brassidium Shooting Star orchid were successfully cryopreserved using droplet-vitrification method. Vitrification based cryopreservation protocol is comprised of preculture, osmoprotection, cryoprotection, cooling, rewarming, and growth recovery and each and every step contributes to the achievement of successful cryopreservation. In order to reveal the lethal and nonlethal damage produced by cryopreservation, histological observation, scanning electron microscopy (SEM), and biochemical analysis were carried out in both cryopreserved and noncryopreserved PLBs of Brassidium Shooting Star orchid comparing with the control PLBs stock culture. Histological and scanning electron microscopy analyses displayed structural changes in cryopreserved PLBs due to the impact of cryoinjury during exposure to liquid nitrogen. Total soluble protein significantly increased throughout the dehydration process and the highest value was achieved when PLBs were stored in liquid nitrogen. Ascorbate peroxidase (APX) and catalase (CAT) showed the highest enzyme activities in both dehydration and cryostorage treatments indicating that stress level of PLBs was high during these stages.
Use of hyperbaric oxygen therapy (HBOT) in chronic diabetic wound - A randomised trial

Nik Hisamuddin NAR, Wan Mohd Zahiruddin WN, Mohd Yazid B, Rahmah S

Med J Malaysia, 2019 Oct;74(5):418-424.
PMID: 31649219

INTRODUCTION: The purpose of this study was to investigate the effect of hyperbaric oxygen therapy (HBOT) towards diabetic foot ulcer (DFU) patients in addition to the standard wound care management.
METHODS: Fifty-eight diabetic patients with ulcers at Wagner Grade 2 and above involved in this study after presented at two study centres of tertiary teaching hospitals. The assigned patients received conventional wound care with additional HBOT given at 2.4 ATA for 90 minutes. Patients in the control group who received conventional wound care only were treated and observed for 30 days. The progress of wound healing was observed and measured at day 0, 10, 20 and 30 of study. The data collected were analysed using SPSS software (ver. 22) to study the association of HBOT towards healing of the diabetic foot ulcers.
RESULTS: Repeated Measures ANOVA analysis with Greenhouse-Geisser correction indicated that the means of wound size over time points (Day 0, 10, 20 and 30) among patients under HBOT group were statistically significantly different [F(1,61)=30.86, p<0.001)] compared to conventional therapy group. Multiple logistic regression analysis showed that HBOT group has nearly 44 times higher odds to achieve at least 30% wound size reduction within the study period (95%CI: 7.18, 268.97, p<0.001).
CONCLUSION: The results obtained in this study indicated that as an adjunctive therapy to conventional wound care, HBOT affected the rate of healing in diabetic foot ulcers significantly in terms of wound size reduction when compared to administering the conventional wound care alone.
Cryopreservation of Brassidium Shooting Star orchid using the PVS3 method supported with preliminary histological analysis

Mubbarakh SA, Rahmah S, Rahman ZA, Sah NN, Subramaniam S

Appl Biochem Biotechnol, 2014 Jan;172(2):1131-45.
PMID: 24146369 DOI: 10.1007/s12010-013-0597-0

Cryopreservation is an alternative, safe, and cost-effective method for long-term plant genetic resource conservation. This study was conducted to optimize the conditions for cryopreserving the protocorm-like bodies (PLBs) of Brassidium Shooting Star orchid with the PVS3 vitrification method. Five parameters were assessed in this study: PLB size, sucrose concentration, preculture duration, PVS3 duration, and unloading duration. The viability of the cryopreserved PLBs was determined using the triphenytetrazolium chloride assay and growth recovery assessments. The optimum condition for the cryopreservation of the PLBs of Brassidium Shooting Star orchid is based on the size range between 3 and 4 mm precultured with half-strength semi-solid MS media supplemented with 0.25 M sucrose for 24 h, followed by treatment with loading solution mixture of 2 M glycerol and 0.4 M sucrose supplemented with half-strength liquid MS media at 25 °C for 20 min. The PLBs were then dehydrated with PVS3 at 0 °C for 20 min prior to immersion in liquid nitrogen; finally, the PLBs were immersed with half-strength liquid MS media supplemented with 1.2 M sucrose for 30 min. Histological analyses displayed denser cytoplasm and voluminous nucleus in the cryopreserved PLBs of Brassidium Shooting Star orchid.
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.
Aquaculture wastewater-raised Azolla as partial alternative dietary protein for Pangasius catfish

Rahmah S, Nasrah U, Lim LS, Ishak SD, Rozaini MZH, Liew HJ

Environ Res, 2022 Jan 18;208:112718.
PMID: 35051427 DOI: 10.1016/j.envres.2022.112718

Azolla is a freshwater floating aquatic fern found in the tropical, subtropical and temperate regions with a high nitrogen-fixing rate from the result of symbiotic relationship with the blue-green cyanobacterium, Anabaena azollae. Azolla can effectively remediate aquaculture wastewater owing to its high production capacity and the ability to absorb nutrients and toxic compounds. The Azolla biomass generated as a by-product is currently underutilized and could potentially benefit the aquafeed industry in replacing the unfeasible and expensive fishmeal protein at a certain level. This study evaluates the incorporation of red tilapia wastewater-raised Azolla as a dietary protein for the growth performance, feed efficiency, survival, body indices, body composition and nutrient utilization of Pangasius catfish Pangasianodon hypophthalmus during a 90-days feeding experiment. Dried Azolla was incorporated into four isonitrogenous (30 g kg-1) and isolipidic (12 g kg-1) practical diets containing 0 g kg-1 (Control), 10 g kg-1 (A10), 20 g kg-1 (A20) and 30 g kg-1 (A30) fishmeal protein replacement. One hundred and twenty juveniles with an initial mean weight of 45 ± 15 g were distributed into 12 tanks representing four dietary treatments in triplicates. Results showed significant (p 0.05) effects were recorded for feed intake, survival, body indices and nutrient utilization amongst all dietary treatments. In conclusion, Azolla raised from red tilapia aquaculture wastewater can replace fishmeal protein up to 10 g kg-1 in the diet of Pangasius catfish juveniles having better growth, feed efficiency and nutrient utilization without affecting its survival, body indices and body composition.
Fulltext Polychaeta-mediated synthesis of gold nanoparticles: A potential antibacterial agent against Acute Hepatopancreatic Necrosis Disease (AHPND)-causing bacteria, Vibrio parahaemolyticus

Abu Hassan MS, Elias NA, Hassan M, Rahmah S, Wan Ismail WI, Harun NA

Heliyon, 2023 Nov;9(11):e21663.
PMID: 37954386 DOI: 10.1016/j.heliyon.2023.e21663

Gold nanoparticles (AuNPs) have emerged as a promising application in aquaculture. Their nano-sized dimensions, comparable to pathogens offer potential solutions for combating antibiotic resistance. In this study, AuNPs were synthesized by using polychaetes, Marphysa moribidii as the bio-reducing agent. Modifications were made to reduce agglomeration in green-synthesized AuNPs through ultrasonication. The antibacterial activities of AuNPs against V. parahaemolyticus were evaluated. The physicochemical characteristics of the green synthesized AuNPs were comprehensively investigated. The successful formation of AuNPs was confirmed by the appearance of a red ruby colour and the presence of surface Plasmon resonance (SPR) absorption peaks at 530 nm as observed from UV-vis spectroscopy. Scanning electron microscopy (SEM) revealed spherical-shaped AuNPs with some agglomerations. Transmission electron microscopy (TEM) showed particle size of AuNPs ranging from 10 nm to 60 nm, meanwhile dynamic light scattering (DLS) analysis indicated an average particle size of 24.36 nm. X-ray diffraction (XRD) analysis confirmed the high crystallinity of AuNPs, and no AuNPs were detected in the polychaetes extracts prior to synthesis. A brief ultrasonication significantly reduced the tendencies for AuNPs to coalesce. The green-synthesized AuNPs demonstrated a remarkable antibacterial efficacy against V. parahaemolyticus. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests revealed that a concentration of 0.3 g/ml of AuNPs effectively inhibited V. parahaemolyticus. These findings highlighted the potential of green-synthesized AuNPs as antibacterial agents for the prevention and management of AHPND in aquaculture.
Sweet orange peel waste as a feed additive in growth promoting and protective effect against Aeromonas hydrophila of juvenile bagrid catfish Mystus nemurus

See MS, Musa N, Liew HJ, Harun NO, Rahmah S

J Environ Manage, 2024 Feb;351:119677.
PMID: 38042084 DOI: 10.1016/j.jenvman.2023.119677

Sweet orange Citrus sinensis peel is a phytobiotic agricultural waste with bioactive compounds that have potential functional properties as a growth promoter and immune stimulator. This study aims to evaluate the dietary effects of sweet orange peel (SOP) as a feed additive on growth enhancement of juvenile bagrid catfish Mystus nemurus and their disease resistance ability against Aeromonas hydrophila infection. Four experimental diets were formulated to contain 0 (SOP0, control), 4 (SOP4), 8 (SOP8) and 12 g/kg (SOP12) SOP. After 90 d of the feeding experiment, improvement in weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio were observed in the fish fed with SOP4. While fish survival was not significantly affected, hepatosomatic and viscerosomatic indices were significantly higher in fish fed with SOP12. Muscle protein was higher in fish fed with SOP4, SOP8, and SOP12 than in control but muscle lipids showed an opposite trend. A 14-d post-challenge test against A. hydrophila revealed no significant effect on the fish survival. Nevertheless, fish fed SOP4 encountered delayed bacterial infection compared to other treatments and fish fed with SOP0 and SOP4 performed numerically better survival. Infected fish showed skin depigmentation, haemorrhagic signs at the abdomen and anus, internal bleeding, and stomach and intestine enlargement. In conclusion, SOP4 could be recommended as a growth promoter while slightly delaying A. hydrophila infection in M. nemurus.
Environmental changes affecting physiological responses and growth of hybrid grouper - The interactive impact of low pH and temperature

Thalib YA, Razali RS, Mohamad S, Zainuddin R', Rahmah S, Ghaffar MA, et al.

Environ Pollut, 2021 Feb 15;271:116375.
PMID: 33422747 DOI: 10.1016/j.envpol.2020.116375

Rising of temperature in conjunction with acidification due to the anthropogenic climates has tremendously affected all aquatic life. Small changes in the surrounding environment could lead to physiological constraint in the individual. Therefore, this study was designed to investigate the effects of warm water temperature (32 °C) and low pH (pH 6) on physiological responses and growth of hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) juveniles for 25 days. Growth performance was significantly affected under warm water temperature and low-pH conditions. Surprisingly, the positive effect on growth was observed under the interactive effects of warm water and low pH exposure. Hybrid grouper exposed to the interactive stressor of warm temperature and low pH exhibited higher living cost, where HSI content was greatly depleted to about 2.3-folds than in normal circumstances. Overall, challenge to warm temperature and low pH induced protein mobilization as an energy source followed by glycogen and lipid to support basal metabolic needs.
Impact of face mask microplastics pollution on the aquatic environment and aquaculture organisms

Jimoh JO, Rahmah S, Mazelan S, Jalilah M, Olasunkanmi JB, Lim LS, et al.

Environ Pollut, 2023 Jan 15;317:120769.
PMID: 36455766 DOI: 10.1016/j.envpol.2022.120769

Microplastic pollution in our environment, especially water bodies is an emerging threat to food security and human health. Inevitably, the outbreak of Covid-19 has necessitated the constant use of face masks made from polymers such as polypropylene, polyurethane, polyacrylonitrile, polystyrene, polycarbonate, polyethylene, or polyester which eventually will disintegrate into microplastic particles. They can be broken down into microplastics by the weathering action of UV radiation from the sun, heat, or ocean wave-current and precipitate in natural environments. The global adoption of face masks as a preventive measure to curb the spread of Covid-19 has made the safe management of wastes from it cumbersome. Microplastics gain access into aquaculture facilities through water sources and food including planktons. The negative impacts of microplastics on aquaculture cannot be overemphasized. The impacts includes low growth rates of animals, hindered reproductive functions, neurotoxicity, low feeding habit, oxidative stress, reduced metabolic rate, and increased mortality rate among aquatic organisms. With these, there is every tendency of microplastic pollution to negatively impact fish production through aquaculture if the menace is not curbed. It is therefore recommended that biodegradable materials rather than plastics to be considered in the production of face mask while recycle of already produced ones should be encouraged to reduce waste.
High environmental temperature and low pH stress alter the gill phenotypic plasticity of Hoven's carp Leptobarbus hoevenii

Mohamad S, Liew HJ, Zainuddin RA, Rahmah S, Waiho K, Ghaffar MA, et al.

J Fish Biol, 2021 Jul;99(1):206-218.
PMID: 33629400 DOI: 10.1111/jfb.14712

Climate warming and low pH environment are known to negatively impact all levels of aquatic organism from cellular to organism and population levels. For ammonotelic freshwater species, any abiotic factor fluctuation will cause disturbance to the fish, specifically at the gills which act as a multifunctional organ to support all biological processes. Therefore, this study was designed to investigate the effect of temperature (28 vs. 32°C) and pH (7.0 vs. 5.0) stress on the gill plasticity of Hoven's carp after 20 days of continuous exposure. The results demonstrated that high temperature and low pH caused severe changes on the primary and secondary lamellae as well as the cells within lamellae. An increasing trend of the proportion available for gas exchange was noticed at high temperature in both pH exposures, which resulted from a reduction of the primary lamellae width with elongated and thinner secondary lamellae compared to fishes at ambient temperature. Following exposure to high temperature and acidic pH, Hoven's carp experienced gill modifications including aneurysm, oedema, hypertrophy, curling of secondary lamellae, epithelial lifting, hyperplasia and lamellae fusion. These modifications are indicators of the coping mechanism of Hoven's carp to the changing environment in order to survive.
Fulltext Female tilapia, Oreochromis sp. mobilised energy differently for growth and reproduction according to living environment

Razali RS, Rahmah S, Shirly-Lim YL, Ghaffar MA, Mazelan S, Jalilah M, et al.

Sci Rep, 2024 Feb 05;14(1):2903.
PMID: 38316820 DOI: 10.1038/s41598-024-52864-0

This study was conducted to investigate the energy mobilisation preference and ionoregulation pattern of female tilapia, Oreochromis sp. living in different environments. Three different treatments of tilapia as physiology compromising model were compared; tilapia cultured in recirculating aquaculture system (RAS as Treatment I-RAS), tilapia cultured in open water cage (Treatment II-Cage) and tilapia transferred from cage and cultured in RAS (Treatment III-Compensation). Results revealed that tilapia from Treatment I and III mobilised lipid to support gonadogenesis, whilst Treatment II tilapia mobilised glycogen as primary energy for daily exercise activity and reserved protein for growth. The gills and kidney Na+/K+ ATPase (NKA) activities remained relatively stable to maintain homeostasis with a stable Na+ and K+ levels. As a remark, this study revealed that tilapia strategized their energy mobilisation preference in accessing glycogen as an easy energy to support exercise metabolism and protein somatogenesis in cage culture condition, while tilapia cultured in RAS mobilised lipid for gonadagenesis purposes.
Fulltext Hoven's carp Leptobarbus hoevenii strategized metabolism needs to cope with changing environment

Mohamad S, Rahmah S, Zainuddin RA, A Thallib Y, Razali RS, Jalilah M, et al.

Heliyon, 2024 Feb 29;10(4):e25559.
PMID: 38404778 DOI: 10.1016/j.heliyon.2024.e25559

Current water warming and freshwater acidification undoubtedly affect the life of aquatic animals especially ammonotelic teleost by altering their physiological responses. The effect of temperature (28 °C vs 32 °C) and pH (7 vs. 5) on the metabolic compromising strategies of Hoven's carp (Leptobarbus hoevenii) was investigated in this study. Fishes were conditioned to (i) 28 °C + pH 7 (N28°C); (ii) 32 °C + pH 7 (N32°C); (iii) 28 °C + pH 5 (L28°C) and (iv) 32 °C + pH 5 (L32°C) for 20 days followed by osmorespiration assay. Results showed that feeding performance of Hoven's carp was significantly depressed when exposed to low pH conditions (L28°C and L32°C). However, by exposed Hoven's carp to L32°C induced high metabolic oxygen intake and ammonia excretion to about 2x-folds higher compared to the control group. As for energy mobilization, Hoven's carp mobilized liver and muscle protein under L28°C condition. Whereas under high temperature in both pH, Hoven's carp had the tendency to reserve energy in both of liver and muscle. The findings of this study revealed that Hoven's carp is sensitive to lower water pH and high temperature, thereby they remodeled their physiological needs to cope with the environmental changes condition.

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