Pusat Pengajian Sains Kajihayat - Tesis

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Biomass Production Of Aureispira Sp. Ccb-qb1 And Its Application As A Novel Bioflocculant
(2022-05)
Rahman, Nur Hasyimah Abdul
Bioflocculants are important to remove pollutants, especially organic particles and heavy metals from wastewater. Previous study showed that Aureispira sp. CCB-QB1 demonstrated cell aggregation when calcium ions are available. This suggested that these bacterial cells are capable to adsorb the waste materials and have a great chance to be a novel bioflocculant. Therefore, in this research, the methods for cultivation of Aureispira sp. CCB-QB1 inside a bioreactor was studied. Then, the biosorption activity of the dead cells toward heavy metals (Fe3+ and Cu2+) was tested. The QB1 dead cells were prepared by treating the living cells using 0.5 % of formaldehyde. The dead cells were discovered to show robust flocculating activity toward kaolin (initial concentration 0.2 %) in the presence of 7 mM CaCl2. For cultivation inside flasks, 5 ml of the dead cell suspension showed overall of 96 % of flocculating activity after shaken using both 150 and 200 rpm agitation speeds. Besides, both tryptone and peptone were found to highly supported the growth of QB1 cells. The presence of peptone in the cell culture also helps in the aggregation of the QB1 cells. For cultivation inside a bioreactor, QB1 culture conditions were optimized using Response Surface Methodology (RSM). The optimized conditions were 3.39 % of sea salt concentration, 0.9 % of peptone concentration, and 29 h of incubation period. Additionally
Characterisation And Pathogenicity Of Fungi Causing Sooty Blotch And Flyspeck (Sbfs) Disease Of Mango (Mangifera Indica L.) In Peninsular Malaysia
(2024-09)
Tham, Khai Xin
The sooty blotch and flyspeck (SBFS) disease complex, caused by multiple fungal species, leads to black smudges and clusters of black spots on various fruits, including mango, impacting their marketability as fresh fruit. Although not previously reported in Malaysia, field visits in 2018 found similar SBFS disease symptoms on mango in various orchards in Perak. Therefore, this research aimed to: 1. Isolate and identify SBFS fungi on mango collected from Perak, Pahang, and Perlis based on morphological and molecular approaches; 2. Assess the phylogenetic relationship among the SBFS fungal isolates; 3. Determine the pathogenicity of the SBFS fungi isolated from mango. A total of 87 mango fruit showing SBFS disease symptoms were collected, and the number of SBFS colonies on each mango (CPM) and the percentage area of SBFS infection were determined. Subsequently, 2106 mango peel samples were obtained and subjected to isolation. Morphological characterization resulted in the identification of 33 pure cultures belonging to SBFS fungal genera, such as Zasmidum, Peltaster, Exophiala, Pseudocercospora, and Ochroconis. The DNA sequencing of the internal transcribed spacer (ITS) and large subunit (LSU) confirmed 18 representative isolates as distinct species, including Z. citrigriseum, Z. aporosae, Peltaster-like species, ‘Pseudopeltaster’, E. bergeri, E. spinifera, Pseudocercospora species, and O. cordanae. Phylogenetic analyses using maximum parsimony (MP) and maximum likelihood (ML) approaches indicated that the SBFS fungal complex on mango was related to both known SBFS members globally and non-SBFS taxa.
Development Of Broodstock Maturation Feed With Supplementation Of Arachidonic Acid (Ara, 20:4n-6) And Docosahexaenoic Acid (Dha, 22:6n-3) For Female Giant Freshwater Prawn, Macrobrachium Rosenbergii
(2023-08)
Ibrahim, Saadiah
The giant freshwater prawn (GFP), Macrobrachium rosenbergii (de Man, 1879), is one of the important commodities in Malaysia's aquaculture industry. The main challenge in Macrobrachium farming is the supply of high-quality seeds, which has become an increasingly critical issue. To address this problem, a study was conducted to investigate the effects of feeding maturation diets containing arachidonic acid (ARA, 20:4n-6) and docosahexaenoic acid (DHA, 22:6n-3) at optimal levels on the maturation and breeding performance of female M. rosenbergii. The research aimed to evaluate the impact of maturation diets enriched with ARA and DHA on the maturation of female GFP, including assessments of gonad development, egg quality, larval quantity, and oocyte size. The analysis also included the examination of fatty acid content in the shrimp's body. The study employed different formulations of maturation diets with varying ARA and DHA levels, comparing them with a control diet. Parameters studied in the female GFP given the experimental diets included reproductive effort, egg quality, larval yield, gonad and hepatopancreas histology, and fatty acid content in the study samples. Three feeding trial experiments were conducted to develop the maturation diets for female M. rosenbergii. The first experiment examined the effects of different diet forms and moisture content on the reproductive performance of female M. rosenbergii. The second experiment aimed to determine the optimal dietary ARA level for enhanced reproductive performance of female GFP
Efficacy And Autodissemination Of Aedestech Mosquito Home System (Amhs) On Aedes Mosquitoes In Laboratory And Small-scale Field Study
(2024-09)
Universiti Sains Malaysia
Ovitrap deployment stands as a viable strategy for Aedes mosquito control. This study evaluated the efficacy of an autodissemination ovitrap called AedesTech Mosquito Home System (AMHS), which incorporates pyriproxyfen. This study encompassed laboratory trials and a small-scale field study. The objective of the field study was to comprehensively assess the impact of AMHS on Aedes, non-target insects, and dengue infection rates in mosquitoes. Within the laboratory trials, these investigations unfolded across two species of mosquitoes: Aedes albopictus and Aedes aegypti. Three distinct facets were explored in the laboratory trials: the influence of an attractant on the oviposition, the effect of trap positioning on oviposition, and the selection of oviposition sites. The field study conducted in Asoka Apartment, Pulau Pinang, unfolded in three successive periods: baseline study, effectiveness study, and autodissemination study. Concurrently, the accuracy of the AedesTech Mobile App (ATA) was scrutinized. The laboratory results indicated the Mosquito Home Aqua (MHAQ) solution with attractant consistently attracted Ae. aegypti effectively (Welch's ANOVA, F(2,68.66)=5.22,p=0.01). However, its efficacy with Ae. albopictus was suboptimal compared to other treatments (Two-way ANOVA, F=0.16,df=2,p>0.05), highlighting the need for considering additional attractants. Notably, the placement of AMHS exhibited no discernible impact on its attractiveness for both mosquito species (T-test,p>0.05), underscoring the flexibility in trap deployment.
Efficacy Of Rodenticides In Controlling Major Rat Species Of Oil Palm, Rattus Tiomanicus (Miller) In Sungkai, Perak
(2022-06)
Noh, Ariff Ateed Bin Mohd
The efficacy of different types of rodenticides in controlling major rat species of oil palm, Rattus tiomanicus (Miller) was carried out in a comparative study among six types of rodenticide baits selected from first-generation anticoagulants: coumatetralyl, chlorophacinone and warfarin, second-generation anticoagulants: brodifacoum and flocoumafen, and non-anticoagulant rodenticide cholecalciferol. The study of the efficacy of selected rodenticide baits was conducted in both laboratory and field assessments. In the laboratory study, no-choice feeding study showed that flocoumafen bait was the most effective in this study compared to other treatments by recording complete mortality against R. tiomanicus. Warfarin bait recorded the lowest efficacy result in this study against R. tiomanicus by only recording 46.07% mortality. Choice feeding study results showed that flocoumafen bait recorded the highest mortality compared to other treatments at 55% while the least efficacy was recorded by warfarin at only 10% mortality. In addition, flocoumafen bait recorded highest bait acceptance at 30.50% and the most palatable bait at 1:2 compared to other treatment baits. In this evaluation, warfarin was the least effective (8.98%) and the least palatable bait (1:7) of the rats compared to other treatment baits. All treatment baits managed to control oil palm fresh rat damages below the threshold level (5%) except warfarin bait. The final result showed that fresh rat damages in treated areas dropped below the threshold level compared to the damages recorded earlier in pre-treatment. Warfarin bait recorded the least effective result, which was above the threshold level compared to other treatment baits.
Fabrication Of 3d Double-network Cnc/alg/pegda Printed Constructs Seeded With C2c12 Myoblasts For Bioprinting Applications
(2023-09)
Asohan, Anusha Wei
3D bioprinting offers a promising alternative for articular cartilage repair and regeneration using a layer-by-layer predetermined movement from a computer aided (CAD) software. In this project, a bioink for bioprinting applications was formulated using cellulose nanocrystals (CNCs), alginate (Alg), and poly(ethylene glycol) diacrylate (PEGDA). Firstly, different formulations of CNC/Alg/PEGDA were formulated using a double network crosslinking approach where the hydrogel was first ionically crosslinked with Ca2+ ions and subsequently photo-crosslinked under UV irradiation at 365nm post-extrusion. The rheological properties, swelling behaviour, and mechanical properties of the formulations were assessed to determine the optimal formulation for bioprinting. Then, the printability of the selected CNC/Alg/PEGDA formulation was evaluated using an extrusion based bioprinter. Next, the biocompatibility of the selected CNC/Alg/PEGDA formulation was determined using C2C12 myoblasts. The cells were seeded into the hydrogel, followed by the bioprinting process. The viability of cells was assessed using Live/Dead assay for a period of 14 to 16 days. The internal structure and porosity of the bioprinted construct with and without cells was analysed using scanning electron microscopy (SEM). Based on the preliminary results, Formulation 8 (F8) with the concentration of 4% CNC, 4% Alg and 40% PEGDA demonstrated shear-thinning behaviour with power-law inde
Factors Influencing Academic External Engagement, Global Mindedness And Internationalisation Satisfaction Among Academics In Malaysian Research Universities
(2024-09)
Muthu, Kalanithi
The internationalisation of higher education is a crucial driver of national economic growth and global competitiveness. Malaysian research universities are increasingly focusing on enhancing their international profile and academic engagement. This study investigates the factors influencing academic external engagement, global mindedness, and internationalisation satisfaction among academics in Malaysian public research universities. Specifically, it examines the impact of perceived institutional support, technology integration, and talent management on global mindedness, and how these relationships are mediated by global mindedness and moderated by academic external engagement. Using Smart PLS to evaluate the hypotheses, the study found that perceived institutional support, technology integration, and talent management positively influence global mindedness among academics. Additionally, global mindedness significantly enhances internationalisation satisfaction. However, the study revealed that while academic external engagement strengthens the relationship between technology integration and global mindedness, it does not significantly moderate the relationships between institutional support or talent management and global mindedness.
Genome-wide Identification And Functional Characterisation Of Β-1,3-glucanase Genes During Biotic And Abiotic Stresses In Hevea Brasiliensis
(2024-08)
Lui, Xin Jie
Natural rubber (NR) is one of the most widely used industrial raw materials while Hevea brasiliensis is the most exclusive species to produce high-quality NR commercially. However, the cultivation of H. brasiliensis faces numerous challenges which can negatively impact the production of natural rubber, such as the specific growth environment requirement of H. brasiliensis and its high susceptibility to fungal infections. Hence, the studies on disease-resistance related genes as well as breeding new disease-resistant varieties are crucial to maintain the role of H. brasiliensis as the promising source of natural rubber. β-1,3-glucanases (GLUs) are pathogenesis-related proteins that belong to the family of PR-2 proteins and can be abundantly found in H. brasiliensis. Besides their significance in physiological and developmental processes, they are vital in defending against microbial pathogen invasion with direct fungicidal effects. A few nucleotide sequences encoding GLUs have been identified from H. brasiliensis with their overexpression in response to a few fungal pathogens. However, the main challenges for utilising GLUs in the crop improvement include the lack of curated and characterised GLU gene sequences and understanding regarding the respective gene expression under different physiological conditions. In the current study, GLU sequences deposited in various databases were obtained, manually curated, analysed the gene features and the gene expression analysis under various conditions: different stages of leaves, abiotic and biotic stress.
Insecticide Resistance And Its Underlying Mechanisms, And Product Evaluations Against Tropical Bed Bugs, Cimex Hemipterus (Fabricius) (Hemiptera: Cimicidae)
(2022-07)
Leong, Xin Yeng
Chemical control remains as the principal mean of bed bug control in Malaysia despite insecticide resistance of bed bugs being widely documented. To date, there are fewer studies reported on insecticide resistance of C.x hemipterus as compared to C. lectularius . This study aims to investigate insecticide resistance status and its underlying mechanisms in eight field C. hemipterus strains collected in Malaysia and Australia. A C. lectularius (Monheim) susceptible strain was used as reference as no susceptible C. hemipterus strains were found. The C. hemipterus strains were evaluated for their resistance levels using commercialized residual liquid formulations, permethrin-impregnated (ActiveGuard) mattress liner, and technical grade insecticides. Insecticide classes investigated include pyrethroids (deltamethrin, lambda-cyhalothrin, beta-cyfluthrin, d-tetramethrin, cyphenothrin, d-phenothrin), neonicotinoids (thiamethoxam, imidacloprid), organophosphates (fenitrothion, chlorpyrifos), pyrrole (chlorfenapyr), and organochlorine (DDT). The parameters evaluated include developmental stages, exposure period, and mortality observation time. Results detected pyrethroid, neonicotinoid, organophosphate, and pyrrole resistance in adults of all C. hemipterus strains, exhibiting low to extremely high resistance levels. First instars demonstrated substantially lower resistance status than adults. Insecticide resistance was detected at egg stage.
Integrative Taxonomy Of The Genus Barbodes (Cyprinidae) In Peninsular Malaysia With A Focus On The B. Binotatus Species Complex And B. Lateristriga Morphotypes
(2023-09)
Sobri, Noor Zahidah Ahmad
This study focused on the fish genus Barbodes Bleeker, 1859 in Peninsular Malaysia, where four species have been often reported in the literatures, B. binotatus, B. banksi, B. lateristriga and B. dunckeri. Preliminary observations on the Barbodes fishes in Peninsular Malaysia had found variation in body pattern. These variations can not only be seen interspecifically but also be seen intraspecifically, which complicates the taxonomic designation of the species in this region. This is particularly true for two groups of species which are referred to as the (1) “B. binotatus species complex”, which includes three valid species: B. binotatus, B. banksi and B. rhombeus, and (2) “B. lateristriga morphotypes”. This study aims to resolve the taxonomic status of B. binotatus species complex and B. lateristriga morphotypes by morphology and molecular approach and provide a comprehensive species list of genus Barbodes in Peninsular Malaysia. Morphology studies of 106 specimens from different localities indicated three types of Barbodes species found in Peninsular Malaysia: B. binotatus, B. rhombeus and B. banksi referred to their size of black spot at the dorsal-fin base. All of these specimens also compared with the true B. binotatus from Java, holotype of B. rhombeus from Thailand and the true B. banksi from Sarawak respectively. Based on the analysis of morphometric using one-way ANOVA and post-hoc Tukey test, there are 27 characters of morphometric measurements showed significant difference (p<0.05) among the B. binotatus species complex. Investigation on this species complex by PCA and DFA analysis revealed the characters of snout length (SnL), prenostril length (PreNosL), caudal peduncle length (CPL), anal-fin depressed length (ADepL), anal-fin height (AHi) and dorsal-fin height (DHi) as important characters in separation of them.
Mealworms And Crickets As Protein Sources In Complete Rations Formulated With Kenaf, Yeast And Cereal Grains For Ruminants In Malaysia
(2024-08)
Yusoff, Husna Fasihah Mohd
Mealworm (Tenebrio molitor) and field cricket (Gryllus assimilis) as a protein source were evaluated for the production of high quality ruminant feed in Malaysia. Nutrient evaluations were also conducted on fibre source, namely kenaf. Whereas molasses, corn and wheat grains were energy sources. Nutrients evaluation in ruminant feed production should not only focused on protein alone but also included metabolizable energy, crude fibre and crude lipid. The feedstuff evaluated in this study suggested that they are potentially high in protein and energy. Both mealworms and crickets were found to contain high amounts of protein, while corn and wheat contained high energy with moderate crude protein contents. While kenaf showed high potential as fibre source for ruminants. This study also evaluated the use of dried malt extract, molasses and sugar in substrates fermentation for yeast production. In this study, multiple energy sources were utilised which contributed to the lowering of feed costs while enhancing the feed formulation. The novelty in this research was the insects used to replace soybean meal as a protein source in ruminant feed formulation. Insects have been widely included as a protein source in poultry industry. However, information on the use of insects as protein source in the ruminants is still limited. Hence, in order to determine the nutritional value of feed ingredients, several feed analysis were also carried out in each ingredients. Proximate analysis on feed ingredients were conducted and reported in chapters 3 to 7.
Micropropagation Of Fig (Ficus Carica) Cv.japanese Btm 6
(2024-09)
Lee, Yong Jun
Ficus carica L., commonly known as the fig tree and belonging to the Moraceae family, is cultivated in subtropical and Mediterranean regions worldwide. This fruit-bearing tree is rich in natural fibre, minerals, and vitamins. However, conventional propagation methods, such as grafting, hardwood cutting, and air layering, are inefficient for establishing viable plant stocks in Malaysia. The primary factor to this inefficiency is the suboptimal rooting efficiency associated with these conventional propagation techniques. However, experiments have shown that vermicast can enhance root induction, improving the survival rate of plantlets in these methods. Therefore, vermicast can be as an option to help with root induction."Vermicast, a byproduct of organic matter decomposition by earthworms, is known for its advantageous impact on plant growth in agriculture. This study aims to establish methods for the micropropagation of Ficus carica cv. Japanese BTM 6 and to evaluate the regeneration effects of vermicast solution on in vitro shoot cultures. Sterile nodal segment explants were subjected to treatments involving various types and concentrations of organic additives, including potato, banana, and coconut water. The induced shoots were further treated with different combinations and concentrations of cytokinins (meta-topolin, BAP, 2ip, zeatin, and TDZ) and auxins (IAA, IBA, NAA) to promote shoot multiplication. Additionally, the induced shoots were assessed for their response to varying concentrations of vermicast solution (ranging from 5% to 30%) in terms of in vitro shoot and root regeneration. Plantlets with roots were acclimatized with different potting mix and vermicast as the acclimazation media with and without vermicast solution during watering.
Proteomic And Biochemical Analysis Of Detoxification Enzyme In Musca Domestica L. (Diptera: Muscidae) And Its Response Upon Prolonged Exposure Of Insecticide
(2024-02)
Manoharan, Kalaavathi
This study provides the proteomic and biochemical information of the detoxification enzymes namely acetylcholinesterase (AChE), α-esterase (α-est), β- esterase (β-est), glutathione s-transferase (GST) and cytochrome P450 (Cyt P450) in susceptible (adult, larvae and pupae) and poultry strains (larvae) Musca domestica. Upon whole protein analysis, number of proteins discovered in larvae was highest (441), followed by adults (181) and pupae (115) which concluded specific proteins are necessary for the proper progression of each developmental phase. Meanwhile, the enzyme activities as well as the protein content of the susceptible strain were found to have significantly varied enzymatic activity across the developmental stages (p<0.05). Thirthy four distinct peptides of the targeted detoxification enzyme were discovered at various developmental stages of the susceptible strain. Functional analysis of the targeted peptides of the susceptible strains exposed that in addition to their functions in detoxification, the multifunctional enzymes were also found to be developmental-related proteins that responsible in various biological process, molecular functions and KEGG pathways to complete metamorphosis. Overall, it has been observed that at the larvae stage, the targeted developmental related detoxification peptides were more expressed and were the most enriched in terms of biological process, molecular function and KEGG
Rhamnolipid As Antifungal Agent Against Pyricularia Oryzae And Rhizoctonia Solani Causing Blast And Sheath Blight Diseases Of Paddy
(2024-09)
Shukri, Izah Adlina Mohamad
Pyricularia oryzae and Rhizoctonia solani are fungi causing blast and sheath blight diseases of paddy (Oryza sativa) in Malaysia. The use of disease resistant rice varieties and fungicides to control both diseases might increase the fungal resistance and the discharge of chemicals into watercourses. This research evaluates the antifungal activity of rhamnolipid, a biosurfactant produced by Pseudomonas aeruginosa USM-AR2 which is more sustainable than chemical fungicides. Seven isolates of Pyricularia sp. and eight isolates of Rhizoctonia sp. from thirty isolates were successfully obtained from blast and sheath blight symptoms in a paddy field in Alor Setar, Kedah, Malaysia. Pathogenicity test confirmed that all Pyricularia sp. and Rhizoctonia sp. isolates were pathogenic by showing a typical blast as an orange brown edge diamond-shaped and sheath blight as an irregular water-soaked. Morphological characterisation and molecular identification of one representative isolate from each group confirmed the identity as P. oryzae USM-PD1 and R. solani USM-PD2. Moreover, antifungal evaluation of rhamnolipid against both fungi demonstrated retarded mycelia with lysis and lesion, as well as slow growth on plates. The highest percentage inhibition of diameter growth (PIDG) for P. oryzae USM-PD1 was achieved at 2000 ppm (48.30 ± 1.18%). Meanwhile, PIDG and percentage inhibition of sclerotia (PISC) number of R. solani USM-PD2 were obtained at 10 000 ppm (60.00 ± 2.35%) and 800 ppm (100%), respectively.
Species Composition And Productivity Of Mosquitoes In Relation To Physicochemical Conditions, Teneral Reserves, Insecticide Susceptibility And Community Knowledge On Mosquito Borne Diseases In Niger,nigeria
(2022-06)
Kura, Ibrahim Shehu
Species compositions in mosquito larval abundance and productivity were assessed in three selected breeding habitats namely, gutters, swamps, and large water bodies located in Bosso, Katcha, Lapai, and Shiroro local government areas (LGAs) of Niger State, Nigeria. The experimental field design that involved opened and closed cage studies were employed, mosquitoes were sampled by dipping and agitation techniques. A total of seven species namely, Aedes aegypti, Ae. dorsalis, Anopheles gambiae, An. coustani, Culex quinquefasciatus, Cx. nigripalpus, and Cx. salinarius were morphologically identified. The findings revealed, large water bodies as the most productive habitats with the varying number of all the species encountered that aggregated at a high quantity followed by gutters and least was the swamps. The rainy season (June -August) was the peak of abundance and productions of all the stages of mosquitoes studied in the seasons, while November was the least (dry season).
Study On Flies Diversity And Effect Of Biotic And Abiotic Factors On Houseflies At Different Farming Systems
(2024-08)
Ballakrishnan, Navanithakumar
A study on the effect of the rearing system and the manure settling floor on the abundance of Musca domestica (fly) was conducted in Kinta district, Perak, Malaysia. The objectives of this study were to determine the diversity of Diptera species in 14 commercial poultry farms with close house and open house systems; the effect of biotic and abiotic factors and wind speed on the abundance of flies in fields with soil and concrete floor types; differences in the housefly index related to relative humidity, the thickness of manure deposited on the floor of the house, the natural manure moisture content, and wet manure were studied on six broiler farms. Knowledge, attitude, and practices (KAP) survey was also carried out to assess the current housefly management and prevention measures in practice. A total of 7,993 flies captured belonged to nine families namely, Muscidae, Calliphoridae, Sacrophagidae, Ulidiidae, Phoridae, Stratiomyidae, Sciaridae, Fannidae and Syrphidae. The Musca domestica was the predominant fly species (p= 0.047) and it represented 74.01% (open house) and 68.26% (closed house) while Megaselia scalaris was the second most abundant species constitutes (21.66% in open house and 30.58% in closed house farming system). In earthen manure settling floor, mean housefly index was 7.67 ± 0.23 heads/30 seconds, p= 0.000 ; bird’s age (12.29 ± 0.48 days, p= 0.057); temperature (29.14 ± 0.07 ℃, p= 0.000); ammonia (0.85 ± 0.04 ppm, p= 0.028); hydrogen sulfide (0.04 ± 0.00 ppm, p= 0.004); wind speed (0.98 ± 0.03 m/s, p= 0.457); relative humidity (56.79 ± 0.27%, p= 0.264); general manure moisture (45.53 ± 1.09%, p= 0.107); wet spot moisture (70.46 ± 1.62%, p= 0.707) and thickness of manure settled (26.13 ± 0.94 mm, p= 0.000).
The Effects Of Photoperiods And Light Emitting Diodes (Leds) On Cell Suspension And Hairy Root Cultures Of Eurycoma Longifolia Jack
(2024-09)
Sani, Sale
In recent years, the issue of earnings management has garnered significant attention from researchers and academics due to its consequences on the quality of financial reports and its impact on investors' decision-making. This study aims to provide evidence on the influence of COVID-19, CEO characteristics, and ownership concentration on two forms of earnings management (EM), namely accruals-based earnings management (AEM) and real earnings management (REM) in Jordan. Additionally, the study explores the role of ownership concentration (family and foreign ownership) as a moderating variable in the relationship between CEO characteristics and earnings management. The study sample included all service and industrial companies listed on the Amman Stock Exchange (ASE) after the update of the Jordanian Corporate Governance Code (JCGC) 2017, covering the period from 2017 to 2021. The theoretical basis for understanding this relationship draws upon the agency, upper-echelons theories and the entrenchment and alignment effects. The hypotheses were tested using the feasible generalized least squares (FGLS) method to address heteroskedasticity and autocorrelation issues, as it provides a suitable approach for controlling these problems in the analysis. The results reveal a negative relationship between COVID-19, CEO tenure, and AEM practices in Jordanian companies. A negative relationship exists between CEO non-duality, CEO age, and REM practices. However, the study uncovers a positive relationship between CEO gender, CEO experience, CEO age, and AEM.
The Use Of Polyhydroxyalkanoate Synthase (Phacbp-M-Cpf4) And Newly Identified Enoyl-Coa Hydratase (Phajss) For The Production Of Poly[(R)-3-Hydroxybutyrate-Co-(R)-3-Hydroxyhexanoate]
(2020-12)
Tan, Hua Tiang
Most industrial plastics are produced using non-renewable resources such as petroleum. Hence, polymer production processes based on renewable resources must be developed to reduce the carbon footprints left by human activities. Polyhydroxyalkanoates (PHAs) are intracellular biopolyesters synthesized by numerous microorganisms as carbon storage under culture conditions of limiting essential nutrients but with excess carbon source. Besides, PHA is biodegradable. Among the various types of PHA, poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] [P(3HB-co-3HHx)] has a high potential to serve as a commercial bioplastic due to it having the most identical properties to petroleum-based plastics. PHA synthase of Chromobacterium sp. USM2 (PhaCCs) and PHA synthase isolated from mangrove metagenome (PhaCBP-M-CPF4) have been reported to be able to produce P(3HB-co-3HHx). In this study, PhaCCs and PhaCBP-M-CPF4 as well as enoyl-CoA hydratase of Streptomyces sp. strain CFMR 7 (PhaJSs) were characterized. Thus, five different genotypes of Cupriavidus necator transformants harboring phaCBP-M-CPF4 gene and three different genotypes of C. necator transformants harboring phaCCs gene were developed to evaluate the incorporation efficiency of 3-hydroxyhexanoate (3HHx) monomers. The amount of 3HHx monomer incorporated in the PHA synthesized by these C. necator transformants were examined using palm oil as the sole carbon source. PhaCBP-M-CPF4 enabled the incorporation of higher 3HHx monomer than PhaCCs (up to 18 mol% 3HHx). Besides, the molecular weight (Mw) of P(3HB-co-3HHx) produced by transformants harboring phaCBP-M-CPF4 could reach up to 1.8 × 106 Da, which was six times higher than the P(3HB-co-3HHx) produced by transformants harboring phaCCs. Enoyl-CoA hydratase is crucial for 3HHx accumulation during the production of P(3HB-co-3HHx). This enzyme channels the pathway for supplying (R)-3-hydroxyacyl-CoA monomer units, especially (R)-3-hydroxyhexanoyl-CoA from fatty acid β-oxidation. In this study, phaJSs was identified from the rubber degrading Gram-positive non-PHA producing bacterium, Streptomyces sp. strain CFMR 7. Co-expression of this enoyl-CoA hydratase gene with the chosen PhaC above, phaCBP-M-CPF4, in C. necator PHB¯4, significantly increased 3HHx composition without decreasing the PHA content. This transformant could produce P(3HB-co-3HHx) with 18 mol% of 3HHx and has a Mw of nearly one million Da revealing that both PhaCBP-M-CPF4 and PhaJSs could potentially be used for industrial applications.
Unveiling Limestone Orchid Hotspots In The Karst Hills Of Northern Peninsular Malaysia
(2024-09)
Bakar, Shahrul Nizam Abu
A significant knowledge gap remains regarding the diversity of orchids in the limestone hills of northern Peninsular Malaysia, especially in Kedah and Perak. Addressing this knowledge gap requires thorough comprehensive assessments and proper documentations of orchid diversity and endemism in this unique karst habitat. To fulfill this, 10 field assessments have been carried out between Mac 2021 to November 2022 to five selected limestone hills in Kedah and Perak state boundary, aimed to assess the diversity of limestone orchids and their species richness, evaluating the threats facing by the orchids and their natural habitat, determining areas with high diversity hotspots, and proposing new conservation status for the rare and endangered orchid species with restricted distribution and small population size. A total of 134 orchid species represented in 68 genera have been recorded from Gunung Batu Putih, Gunung Pong, Gunung Baling, Gunung Pulai and Gunung Fakir Terbang. From the five limestone hills, Gunung Batu Putih was known to have the most richest and diverse orchid species with a total of 105 species from 58 genera (H’ = 4.504 and D = 0.9875), followed by Gunung Pong with 103 species from 57 genera (H’ = 4.471 and D = 0.9867), Gunung Baling with 93 species from 50 genera (H’ = 4.366 and D = 0.9853), Gunung Pulai with 90 species from 49 genera (H’ = 4.296 and D = 0.9838) and lastly Gunung Fakir Terbang with 67 species from 29 genera (H’ = 3.88 and D = 0.9756). From the account, 36 species are recognized as new records to Kedah and three species as new records to Peninsular Malaysia, namely Anoectochilus sanguineus P.T.Ong & P.O’Byrne, Bulbophyllum meson J.J.Verm., Schuit. & de Vogel and Luisia brachystachys (Lindl.) Blume. Three species endemic to Peninsular Malaysia were gathered in this study which are Anoectochilus sanguineus, Cheirostylis goldschmidtiana Schltr. and Phalaenopsis appendiculata Carr. This study has also revealed the relationships between the diversity of orchids and the influences of certain environmental factors. Only soil pH and relative humidity (RH) were found to be positively correlated with orchid’s species richness. The analysis on species distribution data has shown that Gunung Batu Putih to have the highest number of hotspot areas followed by Gunung Pong, Gunung Baling, Gunung Pulai and Gunung Fakir Terbang. New conservation status have been proposed to the selected rare and endangered orchids, which four species were proposed as Critically Endangered (CR) (Aerides krabiensis, Anoectochilus albolineatus, Goodyera hispida and Phalaenopsis appendiculata), and four as Endangered (EN) (Anoectochilus sanguineus, Cheirostylis goldschmidtiana, Paphiopedilum niveum and Spathoglottis hardingiana).
Whole Genome Sequencing For Establishment Of Phylogenetic Position And Discovery Of Miniaturization And Lipid Metabolism Genes In Paedocypris
(2022-05)
Sam, Ka Kei
Paedocypris is the world’s smallest vertebrate with a total length of ≤ 20 mm restricted to acidic freshwater peat swamp environments. The anatomy of Paedocypris is highly modified with developmental truncated characters. The unique miniature phenotypes make the Paedocypris a good model fish to study development and evolution. Three Paedocypris species have been described, including P. micromegethes from Sarawak and another two species, P. progenetica and P. carbunculus from Indonesia. Thus far, Paedocypris has no chromosome-scale genome, with only a draft genome with scaffold N50 ~59-61 kb. In this study, a high-quality chromosome level genome assembly for the P. micromegethes was generated with improved scaffold N50 of 29.8 Mb using a combination of Illumina, PacBio and Hi-C sequencing technologies. Meanwhile, the draft genome for the P. carbunculus was improved with N50 scaffold length of 125 Kb. This study revealed that the small and compact genome sizes of miniature Paedocypris are characterized by a low repeat content, short introns, and a lack of recent genome duplications. Additionally, this study discovered gene loss from the improved genome assemblies, such as fgf8b, mtmr14, scpp3a, scpp3b, scpp6, scpp7 scpp8, gsp37, spp2, and tbx22. Phylogenetic analysis to resolve the contentious taxonomy position of miniaturized cyprinids using mitochondrial 13 protein-coding genes (PCGs) and two ribosomal RNA genes (rRNAs) showed improved supportive values for the sister-group relationship for Paedocypris and Sundadanio to the Danionidae family.

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