Tropical life sciences research最新文献

Pineapple, Ananas comosus (L.) Merr., is a highly nutritious, major tropical Amazonian fruit valued for its health properties. Josapine, a successfully commercialised Malaysian hybrid, bears sweet fruits and has a shorter gestation period as compared to other cultivars. The current study aims to evaluate the in vitro regeneration and shoot multiplication potential of Ananas comosus cv. Josapine using different types of explant sources and different concentrations of cytokinins. Pineapple crown and suckers were surface sterilised and cultured in MS medium supplemented with 6-Benzylaminopurine (BAP) at different concentrations (0.0 mg/L, 1.0 mg/L, 2.0 mg/L and 3.0 mg/L) for six weeks to evaluate the shoot regeneration efficiency of both explants used. In vitro induced shoots from crown and sucker explants were also cultured in different concentrations of BAP and kinetin (0.0 mg/L, 0.5 mg/L, 1.0 mg/L, 1.5 mg/L, 2.0 mg/L, 2.5 mg/L and 3.0 mg/L) for the induction of multiple shoots and roots. Results from the current study revealed that the highest percentage of shoot induction obtained from crown explants was 88.00% in the treatment of 2.0 mg/L BAP (3.50 ± 0.67 shoots per explant), whereas the treatment of 3.0 mg/L BAP resulted in the highest percentage of shoot induction (82.00%) from sucker explants. As for the response of in vitro shoots, the treatment of 2.0 mg/L BAP resulted in the highest number of shoots (6.85 ± 0.61 shoots per explant), whereas the highest number of roots (6.09 ± 0.46 roots per explant) was observed in MS media supplemented with 1.5 mg/L kinetin after 16 weeks of culture. This study demonstrates methods for in vitro shoot multiplication suitable for the micropropagation and commercialisation of the Josapine cultivar. This facilitates the mass production of disease-free, high-quality planting materials, leading to improved fruit quality and enhanced export potential of this pineapple cultivar.

Bio-based plasticisers have been developed as sustainable alternatives to phthalate-based plasticisers. However, limited information on their potential ecotoxicological effects on aquatic organisms could hinder their widespread adoption in the market. This study addresses this gap by providing ecotoxicological data on epoxidised methyl oleate (EMO), a potential bio-based plasticiser. This study evaluated the acute toxicity of EMO on five aquatic species (Moina macrocopa, Daphnia magna, Chlamydomonas reinhardtii, Chlorella vulgaris and Macrobrachium lanchesteri) to develop a species sensitivity distribution (SSD) curve for determining the predicted no-effect concentration (PNEC) of EMO for ecological risk assessment. Additionally, the biodegradation potential of EMO in aquatic environments was assessed using the OECD 301F Manometric Respiratory Test. These results indicate that EMO exhibits a concentration-dependent toxic effect on all tested species. The SSD curve, developed using a normal distribution and a Maximum Likelihood Estimation fit model, yielded 0.359 mg/L for hazardous concentration for 5% of species (HC05). This HC05 value suggests that EMO poses a minimal ecological risk, as it exceeded the water solubility limit (0.012 mg/L). Furthermore, EMO demonstrated favourable biodegradation potential under aerobic conditions. At a concentration of 30 mg/L, EMO achieved 60% biodegradation within four days of incubation, whereas at 100 mg/L, the same level of biodegradation was achieved by Day 11. These findings underscore the importance of assessing the environmental impact of bio-based plasticisers and highlight the EMO's potential as an eco-friendly alternative to less biodegradable, petroleum-based plasticisers.

Quantifying dietary composition is crucial for basic ecological research and to formulate conservation management. For predatory fishes, DNA-metabarcoding can yield more accurate estimates than conventional morphological-based analyses. In Southeast Asia, Malaysian mahseers are experiencing declines in the wild due to their commercial and aesthetic value. Current practice in artificial propagation for mahseer has yet to fulfil high market demand due to constraints in dietary formulations that affect fish fertility and optimal growth. Here we applied cytochrome oxidase I (COI) metabarcoding with one species of Malaysian mahseer, Tor tambra or 'kelah', to characterise their food assimilation and feeding habits from seven different locations of wild and farm origins. Prey DNA sequences were grouped into 54 taxonomic groups at the species level. The diet comprised four predominant classes: Insecta, Actinopterygii, Arachnida and Aconoidasida. Representative taxa from each class were detected in wild and farmed fish. However, less than a quarter of the total taxa overlapped between both fish origins. Non-metric multidimensional scaling (NMDS) indicated greater prey taxonomic diversity and composition in wild fish across different rivers compared to those in farmed fish (PERMANOVA, pseudo-F = 1.959, p < 0.05). Our findings suggest that prey availability from the surrounding play roles in determining the fish food composition and dietary overlap. Expanding dietary analyses could offer ways to optimise diet for cultured fish as one of strategies to reduce fishing pressure on wild populations.

Demand for water monitor lizards (Varanus salvator macromaculatus) from Sumatra and Kalimantan for the leather industry is the highest compared to varanid species from Java (V. s. bivittatus) or Sulawesi (V. s. ziegleri). No conclusive evidence on the age estimate of the individuals being harvested. The skeletochronology method was used to estimate harvested Sumatran water monitors' age and body growth using fibular bones. The mid-diaphysis fibula bone cross-sections of 81 individuals (39 females and 42 males) showed that the line of arrested growth (LAG) was not always clearly visible. Periosteal bones in individuals with SVLs of 39.0 cm-70.0 cm showed double and multiple LAGs and only a few individuals had apparent LAG. As the SVL increases, the double and multiple LAGs are not seen in individuals with more than 70 cm SVL. The estimated ages of harvested individuals of female V. s. macromaculatus with SVLs ranging from 40.1 cm-71.0 cm were 2-3 years old, whilst for males with SVLs ranging between 39.0 cm-96.0 cm, were 2-5 years old. A strong correlation between the SVL and fibular mid-diaphysis diameter was observed in both sexes. This indicates that the formation of LAGs occurs steadily every year, although LAGs are not always clearly visible in every individual, especially in young ones.

Schizophrenia is a psychiatric disorder that affects a person's ability to think, feel and behave clearly. The pathophysiology of the disease stems from the overexpression of dopamine neurotransmission and deficiency of glutamate activity at glutamate synapse in the brain. Considering the significant global burden of the disease, lack of complete efficacy using the current medications and variety of adverse effects associated with their use, and the huge opportunity created by Computer-Aided Drug Design, it is therefore important and possible to come up with drug leads that will have improved efficacy and reduced side effects. This research is thus aimed to design, evaluate the pharmacokinetic properties, and the in silico antischizophrenic activity of novel 1,3-disubstituted chalcones. Ten compounds were designed using ChemDraw Ultra 7.0 using similarity approach and their oral bioavailability was predicted using SwissADME, toxicity was predicted using PROTOX 3.0 and docking studies were carried out using AutoDock Vina through Chimera 1.11.2. The 10 designed compounds were predicted to have excellent oral bioavailability and lead-likeness properties, easy synthesisability and a relatively safer toxicity profile than the reference compound clozapine. The compounds were evaluated to have higher docking scores between -8.3 to -9.5 compared to clozapine with a docking score of -8.8 when docked against dopaminergic D2 receptor. In addition, the compounds have close binding scores (-6.0 to -6.6) compared to clozapine (-6.7) when docked against N-Methyl-D-aspartic Acid (NMDA) receptor, suggesting their use as potential antischizophrenic agents.

A comparative leaf anatomy study was carried out on 10 taxa of Globba L. (Zingiberaceae) in Peninsular Malaysia to ascertain their systematic significance, especially for species differentiation and identification. Methods used include leaf clearing, leaf sectioning using a sliding microtome and observation under a scanning electron microscope. Results showed that a combination of the following characters have taxonomic significance in Globba spp. Studied, i.e., outlines of leaf margin, midribs, petioles and their relative sizes; number of vascular bundles in arc I, II, III and IV in the midribs and petioles; absence or presence and type of trichomes; presence of fibre caps and girders in vascular bundles in the leaf lamina, as well as the presence of hypodermal layers below adaxial epidermis. Anatomical characteristics such as tufted trichomes in G. patens, papilose adaxial epidermal cells in G. variabilis var. pusilla, rounded margin in G. variabilis and an arc I vascular bundle present only in the midrib of G. variabilis var. pusilla can be used as diagnostic characters for each species. Globba variabilis var. pusilla which is closely related to G. variabilis can be distinguished by the papilose epidermal cells. This study proved that leaf epidermis anatomical characteristics could possibly be applied to the identification of some species in Globba with certainty.

Pumpkin is an important economic crop with high nutritional value. Different pumpkin varieties experience diverse growth problems due to soil salinity. This research studied the physiological and anatomical adaptations of the Kang Kog pumpkin cultivar to salinity stress. Pumpkin seedlings were grown under a hydroponic system using Hoagland's solution with NaCl concentrations of 0 mM, 25 mM, 50 mM, 75 mM and 100 mM for four weeks. Results showed that pumpkin leaf number, leaf width, leaf length, root number, root length, plant height, stem diameter, fresh weight and dry weight significantly decreased after exposure to high NaCl concentrations. Chlorophyll a and green intensity measured as SPAD units also significantly decreased, while chlorophyll fluorescence (Fv/Fm, Fv'/Fm') and chlorophyll b content of all treated groups were not significantly different when compared to the control group. Fibre strands and cuticles in all treatments were significantly thicker compared to the control group, while vessel diameters and vascular bundle sizes of the treated groups significantly decreased compared to the control group. Results showed that salinity stress did not impact chlorophyll b and chlorophyll fluorescence. Kang Kog pumpkins can adapt and grow in slightly saline environments. Our results provide important information for pumpkin breeding programs efforts that can be used in combining with other agronomic characters to improve tolerant cultivars under initial salinity stress tolerance.

Enzymes are functional proteins that accelerate chemical reactions and reduce the activation energy. Lacticaseibacillus paracasei, a lactic acid bacterium, is widely used as a probiotic supplement in the food industry. L. paracasei strain IN17 was isolated from Inasua, Indonesian fish fermentation products. It produces an extracellular protease that hydrolyses peptide bonds to produce peptides or amino acids. It is important to characterise bacteria that produce protease to know their activity and potency. This study aims to purify, characterise and detect the protease-encoding gene from L. paracasei. Isolates that have been identified were tested qualitatively by measuring the proteolytic index. The optimal production was known for two incubation treatments with static and dynamic conditions. The crude extract was precipitated with ammonium sulfate in the concentration range of 0%-80% (w/v). Enzyme activity characterisation was carried out based on optimum pH and temperature, the effect of cation metal, inhibitor and protease kinetics. The static condition had higher growth and protease-specific activity than the dynamic condition, which were 0.137 U/mg and 0.054 U/mg, respectively, at 18 h of production. Ammonium sulfate saturation at a concentration of 20% (w/v) resulted in a protease purity 7.36. The optimal activity of crude extract and precipitated protease were at pH 7 and 6, respectively. Both crude extract and precipitated protease have an optimal temperature at 30°C, activated by Mn cofactor and inhibited by EDTA with >50% inhibition percentage. This protease represents a metalloprotease. The gene encoding protease (prtP) was successfully amplified with ~685 bp visualised in an agarose gel 1% (w/v).

Light quality significantly influences plant growth and development by interacting with photoreceptors, leading to reversible and irreversible outcomes. This study provides novel insights into the species-specific effects of light-emitting diodes (LEDs) on the morphological characteristics and genetic stability of Eurycoma longifolia hairy root cultures (ELHRCs) under different light qualities. LED treatments included white (400 nm-700 nm), blue (440 nm), mint green (530 nm), red (660 nm) and a combination of blue with red (1:1) (440 nm + 660 nm) applied for 8, 10 and 12 weeks. Morphological changes and growth were assessed alongside genetic stability through direct amplification of minisatellite DNA regions (DAMD) and inter-simple sequence repeat (ISSR) markers analysis using 12 primers. The results showed genetic similarity of 90.6% after 8 weeks and 100% after 10 and 12 weeks (DAMD) and 100%, 98.2% and 90.3% after 8, 10 and 12 weeks, respectively (ISSR) under all LED treatments, confirming the genetic stability of the hairy roots. Additionally, the study demonstrated how spectral quality influences hairy roots growth and morphology. The high percentage of genetic similarity highlights LEDs as a promising tool for in vitro culture of ELHRCs. These findings represent the first comprehensive report on the combined effects of LED spectral quality on growth, morphological changes and genetic stability in ELHRCs.

The increasing prevalence of chronic diseases and oxidative stress-related conditions has led to a growing interest in natural products with potent antioxidant properties. High-throughput screening (HTS) assays offer a promising solution for the rapid evaluation of numerous samples. This study aims to establish a robust HTS assay using the 2-Diphenyl-1-Picrylhydrazyl (DPPH) method to identify natural products with significant antioxidant capabilities, ensuring their safety profiles through cytotoxicity screening and phytochemical profiling. An automated liquid handler with the usage of a 384-well assay plate was employed in optimising and validating the 2,2-diphenyl-1-picrylhydrazyl (DPPH)-HTS assay by calculating the metrics. The HTS metrics include Z-prime (Z') values of 0.72 and 0.63, signal to background (S/B) ratios of 3.54 and 9.02, and coefficient of variation percentages (%C/V) of 4.25 and 6.49 for each primary and secondary screenings, respectively. These values indicated that the HTS assay was excellent. By using optimised HTS-DPPH assay programme, a total of 363 plant extracts were screened and 58 (16%) were found to have potent antioxidant activity (a 'yes' score and EC₅₀ < 50 μg/mL). Out of these 363 extracts, only 80 plants were identified with herbarium and the screening results revealed that Tetracera scandens along with other 11 plants have potent antioxidant activities. T. scandens was the most potent and the methanol extract from its leaves recorded an EC₅₀ value of 13.041± 0.82 μg/mL. However, the aqueous extract of T. scandens leaves (TSLAE) was selected to allow any possibilities of using it for traditional herbal preparation. TSLAE presented an EC₅₀ value of 13.76 ± 4.50 μg/mL in the DPPH assay and was non-toxic towards normal cells with an IC₅₀ value of > 100 μg/mL. Secondary metabolites with promising antioxidant potentials were successfully identified using LC/MS and the library, which were mainly flavonoids (37.5%), phenolics (8.9%) and polyphenols (8.9%). HTS-DPPH is a robust and rapid technique for screening of antioxidative substances in plant extracts. The hit is non-toxic in vitro and rich in secondary metabolites that contribute to antioxidant activity.