Displaying publications 81 - 97 of 97 in total

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  1. Tan WS, Chang CY, Yin WF, Chan KG
    Genome Announc, 2015;3(1).
    PMID: 25635007 DOI: 10.1128/genomeA.01509-14
    Pantoea stewartii is known to be the causative agent of Stewart's wilt, which usually affects sweet corn (Zea mays) with the corn flea beetle as the transmission vector. In this work, we present the whole-genome sequence of Pantoea stewartii strain M009, isolated from a Malaysian tropical rainforest waterfall.
    Matched MeSH terms: Rainforest
  2. Tan WS, Yin WF, Chan KG
    Genome Announc, 2015;3(1).
    PMID: 25555739 DOI: 10.1128/genomeA.01372-14
    Aeromonas hydrophila species can be found in warm climates and can survive in different environments. They possess the ability to communicate within their populations, which is known as quorum sensing. In this work, we present the draft genome sequence of A. hydrophila M013, a bacterium isolated from a Malaysian tropical rainforest waterfall.
    Matched MeSH terms: Rainforest
  3. Tan WS, Yunos NY, Tan PW, Mohamad NI, Adrian TG, Yin WF, et al.
    Sensors (Basel), 2014;14(6):10527-37.
    PMID: 24932870 DOI: 10.3390/s140610527
    One obvious requirement for concerted action by a bacterial population is for an individual to be aware of and respond to the other individuals of the same species in order to form a response in unison. The term "quorum sensing" (QS) was coined to describe bacterial communication that is able to stimulate expression of a series of genes when the concentration of the signaling molecules has reached a threshold level. Here we report the isolation from aquatic environment of a bacterium that was later identified as Enterobacter sp.. Chromobacterium violaceum CV026 and Escherichia coli [pSB401] were used for preliminary screening of N-acyl homoserine lactone (AHL) production. The Enterobacter sp. isolated was shown to produce two types of AHLs as confirmed by analysis using high resolution tandem mass spectrometry. To the best of our knowledge, this is the first documentation of an Enterobacter sp. that produced both 3-oxo-C6-HSL and 3-oxo-C8-HSL as QS signaling molecules.
    Matched MeSH terms: Rainforest*
  4. Tan, Soon Guan
    MyJurnal
    The world’s biodiversity is not distributed uniformly throughout the globe. Some areas such as the tropical rainforests, seas and coral reefs teem with the varieties of life whereas others such as some deserts and polar regions are almost devoid of them (Gaston, 2000). Malaysia, with her tropical jungles and seas, is rich with biodiversity. She is fortunate to have had eminent pioneers such as Ridley (1967), Corner (1972), Soepadmo (1972) and Whitmore (1983) to study her flora and Medway (1968) and Lim (1991) to study her fauna taxonomy. Other pioneers in Malaysian biology included Berry, Dhaliwal and Mohsin. These pioneers are then ably followed by workers such as Latiff, Kiew, Go, Khoo, Davidson, Saberi, Omar, Jambari, Idris, Zekri, Teo, Marziah, Tan, Mukherjee, Shapor, Yusoff, Azmi and many others studying the various subdisciplines of biology. In addition to the more obvious large plants and animals, microorganisms and aquatic organisms had not been neglected either. Workers such as Nawawi, Verghese, Ho and Faridah are known
    for their work on fungi while Fatimah, Phang, Japar and Anton had studied algae, seaweeds, diatoms and seagrasses. However, some of these workers have now either retired or are soon going to attain retirement age and the worrying part is that there are not many younger
    workers keen to pursue research in taxonomy and biosystematics, a prerequisite to further studies in ecology, genetics, biotechnology which in turn are prerequisites for rational conservation, management and sustainable utilization of our rich biological resources. With each passing day species are becoming extinct sometimes without us even knowing that they had ever existed. Even in a developed country such as the USA, one third of her plant and animal species are at risk of extinction (McCann, 2000). Hence, taxonomic and biosystematic studies of our plants, animals and microbes whether terrestrial or aquatic, freshwater and marine, should be priority areas. So should studies on their reproductive biology, life cycles, physiology, feeding habits, migration patterns, predators and their sensitivities to environmental changes.
    Matched MeSH terms: Rainforest
  5. Tan, Chin Xuan, Azrina Azlan
    MyJurnal
    Canarium odontophyllum Miq. fruit, popularly recognized as dabai fruit in Sarawak, is a
    seasonal fruit found in the tropical rainforest of East Malaysia. A dabai fruit can be divided into
    several anatomical parts, and different parts of the fruit have different valuable phytochemicals. Due
    to the lack of promotion, dabai fruit is viewed as nutritionally inferior fruit by the public. On the
    contrary, the fruit is rich in nutrients such as protein, fat, carbohydrates, sodium, calcium and iron.
    Many phytochemicals have been detected from different parts of dabai fruit, and these molecules have
    been linked to beneficial properties such as hypolipidemic, anti-atherosclerotic, anti-cholinesterase,
    antimicrobial and potentially anti-diabetic. The aim of this article is to review research studies on this
    fruit in order to provide adequate baseline information for commercial exploitation as well as for
    future studies.
    Matched MeSH terms: Rainforest
  6. Tang ACI, Stoy PC, Hirata R, Musin KK, Aeries EB, Wenceslaus J, et al.
    Sci Total Environ, 2019 Sep 15;683:166-174.
    PMID: 31132697 DOI: 10.1016/j.scitotenv.2019.05.217
    Tropical rainforests control the exchange of water and energy between the land surface and the atmosphere near the equator and thus play an important role in the global climate system. Measurements of latent (LE) and sensible heat exchange (H) have not been synthesized across global tropical rainforests to date, which can help place observations from individual tropical forests in a global context. We measured LE and H for four years in a tropical peat forest ecosystem in Sarawak, Malaysian Borneo using eddy covariance, and hypothesize that the study ecosystem will exhibit less seasonal variability in turbulent fluxes than other tropical ecosystems as soil water is not expected to be limiting in a tropical forested wetland. LE and H show little variability across seasons in the study ecosystem, with LE values on the order of 11 MJ m-2 day and H on the order of 3 MJ m-2 day-1. Annual evapotranspiration (ET) did not differ among years and averaged 1579 ± 47 mm year-1. LE exceeded characteristic values from other tropical rainforest ecosystems in the FLUXNET2015 database with the exception of GF-Guy near coastal French Guyana, which averaged 8-11 MJ m-2 day-1. The Bowen ratio (Bo) in tropical rainforests in the FLUXNET2015 database either exhibited little seasonal trend, one seasonal peak, or two peaks. Volumetric water content (VWC) and VPD explained a trivial amount of the variability of LE and Bo in some of the tropical rainforests including the study ecosystem, but were strong controls in others, suggesting differences in stomatal regulation and/or the partitioning between evaporation and transpiration. Results demonstrate important differences in the seasonal patterns in water and energy exchange across different tropical rainforest ecosystems that need to be understood to quantify how ongoing changes in tropical rainforest extent will impact the global climate system.
    Matched MeSH terms: Rainforest*
  7. Ten DCY, Jani R, Hashim NH, Saaban S, Abu Hashim AK, Abdullah MT
    Animals (Basel), 2021 Apr 06;11(4).
    PMID: 33917373 DOI: 10.3390/ani11041032
    The critically endangered Malayan tiger (Panthera tigris jacksoni), with an estimated population of less than 200 individuals left in isolated rainforest habitats in Malaysia, is in an intermediate population crash leading to extinction in the next decade. The population has decreased significantly by illegal poaching, environmental perturbation, roadkill, and being captured during human-wildlife conflicts. Forty-five or more individuals were extracted from the wild (four animals captured due to conflict, one death due to canine distemper, one roadkilled, and 39 poached) in the 12 years between 2008-2019. The Malayan tigers are the first wildlife species to test positive for COVID-19 and are subject to the Canine Distemper Virus. These anthropogenic disturbances (poaching and human-tiger conflict) and environmental perturbation (decreasing habitat coverage and quality) have long been identified as impending extinction factors. Roadkill and infectious diseases have emerged recently as new confounding factors threatening Malayan tiger extinction in the near future. Peninsular Malaysia has an existing Malayan tiger conservation management plan; however, to enhance the protection and conservation of Malayan tigers from potential extinction, the authority should reassess the existing legislation, regulation, and management plan and realign them to prevent further population decline, and to better enable preparedness and readiness for the ongoing pandemic and future threats.
    Matched MeSH terms: Rainforest
  8. Thüs H, Wolseley P, Carpenter D, Eggleton P, Reynolds G, Vairappan CS, et al.
    Microorganisms, 2021 Mar 05;9(3).
    PMID: 33807993 DOI: 10.3390/microorganisms9030541
    Many lowland rainforests in Southeast Asia are severely altered by selective logging and there is a need for rapid assessment methods to identify characteristic communities of old growth forests and to monitor restoration success in regenerating forests. We have studied the effect of logging on the diversity and composition of lichen communities on trunks of trees in lowland rainforests of northeast Borneo dominated by Dipterocarpaceae. Using data from field observations and vouchers collected from plots in disturbed and undisturbed forests, we compared a taxonomy-based and a taxon-free method. Vouchers were identified to genus or genus group and assigned to functional groups based on sets of functional traits. Both datasets allowed the detection of significant differences in lichen communities between disturbed and undisturbed forest plots. Bark type diversity and the proportion of large trees, particularly those belonging to the family Dipterocarpaceae, were the main drivers of lichen community structure. Our results confirm the usefulness of a functional groups approach for the rapid assessment of tropical lowland rainforests in Southeast Asia. A high proportion of Dipterocarpaceae trees is revealed as an essential element for the restoration of near natural lichen communities in lowland rainforests of Southeast Asia.
    Matched MeSH terms: Rainforest
  9. Tomimatsu H, Iio A, Adachi M, Saw LG, Fletcher C, Tang Y
    Tree Physiol, 2014 Sep;34(9):944-54.
    PMID: 25187569 DOI: 10.1093/treephys/tpu066
    Understory plants in tropical forests often experience a low-light environment combined with high CO2 concentration. We hypothesized that the high CO2 concentration may compensate for leaf carbon loss caused by the low light, through increasing light-use efficiency of both steady-state and dynamic photosynthetic properties. To test the hypothesis, we examined CO2 gas exchange in response to an artificial lightfleck in Dipterocarpus sublamellatus Foxw. seedlings under contrasting CO2 conditions: 350 and 700 μmol CO2 mol(-1) air in a tropical rain forest, Pasoh, Malaysia. Total photosynthetic carbon gain from the lightfleck was about double when subjected to the high CO2 when compared with the low CO2 concentration. The increase of light-use efficiency in dynamic photosynthesis contributed 7% of the increased carbon gain, most of which was due to reduction of photosynthetic induction to light increase under the high CO2. The light compensation point of photosynthesis decreased by 58% and the apparent quantum yield increased by 26% at the high CO2 compared with those at the low CO2. The study suggests that high CO2 increases photosynthetic light-use efficiency under both steady-state and fluctuating light conditions, which should be considered in assessing the leaf carbon gain of understory plants in low-light environments.
    Matched MeSH terms: Rainforest
  10. Valappil NKM, Viswanathan PM, Hamza V
    PMID: 32572749 DOI: 10.1007/s11356-020-09542-1
    A comprehensive study of the chemical composition of rainwater was carried out from October 2016 to September 2017 in the equatorial tropical rainforest region of northwestern Borneo. Monthly cumulative rainwater samples were collected from different locations in the Limbang River Basin (LRB) and were later categorized into seasonal samples representing northeast monsoon (NEM), southwest monsoon (SWM), and inter-monsoon (IM) periods. Physical parameters (pH, EC, TDS, DO, and turbidity), major ions (HCO3-, Cl-, Ca2+, Mg2+, Na+, and K+) and trace metals (Co, Ni, Cd, Fe, Mn, Pb, Zn, and Cu) were analyzed from collected rainwater samples. Rainwater is slightly alkaline with mean pH higher than 5.8. Chloride and bicarbonate are the most abundant ions, and the concentration of major ions in seasonal rainwater has shown slight variation which follows a descending order of HCO3-> Cl-> Na+ > Ca2+ > Mg2+ > K+ in NEM and Cl- > HCO3- > Na+ > Ca2+ > K+ > Mg2+ in SWM and Cl- > HCO3- > Na+ > Ca2+ > Mg2+ > K+ in IM period. Trace metals such as Fe and Ni have shown dominance in seasonal rainwater samples, and all the metals have shown variation in concentration in different seasons. Variation in chemical characteristic of seasonal rainwater samples identified through piper diagram indicates dominance of Ca2+-Mg2+-HCO3- and mixed Ca2+-Mg2+-Cl- facies during NEM, SWM, and IM periods. Statistical analysis of the results through two-way ANOVA and Pearson's correlation also indicates significant variation in physico-chemical characteristics. This suggests a variation in contributing sources during the monsoon seasons. Factor analysis confirmed the source variation by explaining the total variance of 79.80%, 90.72%, and 90.52% with three factor components in NEM, SWM, and IM rainwater samples with different loading of parameters. Enrichment factor analysis revealed a combined contribution of marine and crustal sources except K+ which was solely from crustal sources. Sample analysis of backward air mass trajectory supports all these findings by explaining seasonal variation in the source of pollutants reaching the study area. Overall, the results show that the chemical composition of seasonal rainwater samples in LRB was significantly influenced by natural as well as anthropogenic processes. These include (long-range and local) industrial activities, fossil fuel combustion, forest burning, transportation activities including road transport and shipping activities, and land-derived soil dust along with chemical constituents carried by seasonal wind.
    Matched MeSH terms: Rainforest
  11. Venkataraman VV, Yegian AK, Wallace IJ, Holowka NB, Tacey I, Gurven M, et al.
    Proc Biol Sci, 2018 11 07;285(1890).
    PMID: 30404871 DOI: 10.1098/rspb.2018.1492
    The convergent evolution of the human pygmy phenotype in tropical rainforests is widely assumed to reflect adaptation in response to the distinct ecological challenges of this habitat (e.g. high levels of heat and humidity, high pathogen load, low food availability, and dense forest structure), yet few precise adaptive benefits of this phenotype have been proposed. Here, we describe and test a biomechanical model of how the rainforest environment can alter gait kinematics such that short stature is advantageous in dense habitats. We hypothesized that environmental constraints on step length in rainforests alter walking mechanics such that taller individuals are expected to walk more slowly due to their inability to achieve preferred step lengths in the rainforest. We tested predictions from this model with experimental field data from two short-statured populations that regularly forage in the rainforest: the Batek of Peninsular Malaysia and the Tsimane of the Bolivian Amazon. In accordance with model expectations, we found stature-dependent constraints on step length in the rainforest and concomitant reductions in walking speed that are expected to compromise foraging efficiency. These results provide the first evidence that the human pygmy phenotype is beneficial in terms of locomotor performance and highlight the value of applying laboratory-derived biomechanical models to field settings for testing evolutionary hypotheses.
    Matched MeSH terms: Rainforest*
  12. Venkataraman VV, Kraft TS, Dominy NJ, Endicott KM
    Proc Natl Acad Sci U S A, 2017 03 21;114(12):3097-3102.
    PMID: 28265058 DOI: 10.1073/pnas.1617542114
    The residential mobility patterns of modern hunter-gatherers broadly reflect local resource availability, but the proximate ecological and social forces that determine the timing of camp movements are poorly known. We tested the hypothesis that the timing of such moves maximizes foraging efficiency as hunter-gatherers move across the landscape. The marginal value theorem predicts when a group should depart a camp and its associated foraging area and move to another based on declining marginal return rates. This influential model has yet to be directly applied in a population of hunter-gatherers, primarily because the shape of gain curves (cumulative resource acquisition through time) and travel times between patches have been difficult to estimate in ethnographic settings. We tested the predictions of the marginal value theorem in the context of hunter-gatherer residential mobility using historical foraging data from nomadic, socially egalitarian Batek hunter-gatherers (n = 93 d across 11 residential camps) living in the tropical rainforests of Peninsular Malaysia. We characterized the gain functions for all resources acquired by the Batek at daily timescales and examined how patterns of individual foraging related to the emergent property of residential movements. Patterns of camp residence times conformed well with the predictions of the marginal value theorem, indicating that communal perceptions of resource depletion are closely linked to collective movement decisions. Despite (and perhaps because of) a protracted process of deliberation and argument about when to depart camps, Batek residential mobility seems to maximize group-level foraging efficiency.
    Matched MeSH terms: Rainforest*
  13. Veryard R, Wu J, O'Brien MJ, Anthony R, Both S, Burslem DFRP, et al.
    Sci Adv, 2023 Sep 15;9(37):eadf0938.
    PMID: 37713486 DOI: 10.1126/sciadv.adf0938
    Experiments under controlled conditions have established that ecosystem functioning is generally positively related to levels of biodiversity, but it is unclear how widespread these effects are in real-world settings and whether they can be harnessed for ecosystem restoration. We used remote-sensing data from the first decade of a long-term, field-scale tropical restoration experiment initiated in 2002 to test how the diversity of planted trees affected recovery of a 500-ha area of selectively logged forest measured using multiple sources of satellite data. Replanting using species-rich mixtures of tree seedlings with higher phylogenetic and functional diversity accelerated restoration of remotely sensed estimates of aboveground biomass, canopy cover, and leaf area index. Our results are consistent with a positive relationship between biodiversity and ecosystem functioning in the lowland dipterocarp rainforests of SE Asia and demonstrate that using diverse mixtures of species can enhance their initial recovery after logging.
    Matched MeSH terms: Rainforest
  14. Weemstra M, Peay KG, Davies SJ, Mohamad M, Itoh A, Tan S, et al.
    New Phytol, 2020 10;228(1):253-268.
    PMID: 32436227 DOI: 10.1111/nph.16672
    Arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF) produce contrasting plant-soil feedbacks, but how these feedbacks are constrained by lithology is poorly understood. We investigated the hypothesis that lithological drivers of soil fertility filter plant resource economic strategies in ways that influence the relative fitness of trees with AMF or EMF symbioses in a Bornean rain forest containing species with both mycorrhizal strategies. Using forest inventory data on 1245 tree species, we found that although AMF-hosting trees had greater relative dominance on all soil types, with declining lithological soil fertility EMF-hosting trees became more dominant. Data on 13 leaf traits and wood density for a total of 150 species showed that variation was almost always associated with soil type, whereas for six leaf traits (structural properties; carbon, nitrogen, phosphorus ratios, nitrogen isotopes), variation was also associated with mycorrhizal strategy. EMF-hosting species had slower leaf economics than AMF-hosts, demonstrating the central role of mycorrhizal symbiosis in plant resource economies. At the global scale, climate has been shown to shape forest mycorrhizal composition, but here we show that in communities it depends on soil lithology, suggesting scale-dependent abiotic factors influence feedbacks underlying the relative fitness of different mycorrhizal strategies.
    Matched MeSH terms: Rainforest
  15. Yeo TC, Naming M, Manurung R
    Comb Chem High Throughput Screen, 2014 Mar;17(3):192-200.
    PMID: 24409959
    The Sarawak Biodiversity Centre (SBC) is a state government agency which regulates research and promotes the sustainable use of biodiversity. It has a program on documentation of traditional knowledge (TK) and is well-equipped with facilities for natural product research. SBC maintains a Natural Product Library (NPL) consisting of local plant and microbial extracts for bioprospecting. The NPL is a core discovery platform for screening of bioactive compounds by researchers through a formal agreement with clear benefit sharing obligations. SBC aims to develop partnerships with leading institutions and the industries to explore the benefits of biodiversity.
    Matched MeSH terms: Rainforest
  16. Yusah KM, Foster WA, Reynolds G, Fayle TM
    PeerJ, 2018;6:e4231.
    PMID: 29423344 DOI: 10.7717/peerj.4231
    Background: Competitive interactions in biological communities can be thought of as giving rise to "assembly rules" that dictate the species that are able to co-exist. Ant communities in tropical canopies often display a particular pattern, an "ant mosaic", in which competition between dominant ant species results in a patchwork of mutually exclusive territories. Although ant mosaics have been well-documented in plantation landscapes, their presence in pristine tropical forests remained contentious until recently. Here we assess presence of ant mosaics in a hitherto under-investigated forest stratum, the emergent trees of the high canopy in primary tropical rain forest, and explore how the strength of any ant mosaics is affected by spatial scale, time of day, and sampling method.

    Methods: To test whether these factors might impact the detection of ant mosaics in pristine habitats, we sampled ant communities from emergent trees, which rise above the highest canopy layers in lowland dipterocarp rain forests in North Borneo (38.8-60.2 m), using both baiting and insecticide fogging. Critically, we restricted sampling to only the canopy of each focal tree. For baiting, we carried out sampling during both the day and the night. We used null models of species co-occurrence to assess patterns of segregation at within-tree and between-tree scales.

    Results: The numerically dominant ant species on the emergent trees sampled formed a diverse community, with differences in the identity of dominant species between times of day and sampling methods. Between trees, we found patterns of ant species segregation consistent with the existence of ant mosaics using both methods. Within trees, fogged ants were segregated, while baited ants were segregated only at night.

    Discussion: We conclude that ant mosaics are present within the emergent trees of the high canopy of tropical rain forest in Malaysian Borneo, and that sampling technique, spatial scale, and time of day interact to determine observed patterns of segregation. Restricting sampling to only emergent trees reveals segregatory patterns not observed in ground-based studies, confirming previous observations of stronger segregation with increasing height in the canopy.

    Matched MeSH terms: Rainforest
  17. ZALIHA ZAINUDDIN, ZALEHA MOHAMED, HAROLD LOLING
    MyJurnal
    Tourism is associated with leisure and travelling, and is considered one of the fastest growing sectors that contribute significantly to the country’s economy, as well as bringing benefits directly to local communities. The Rural Tourism Master Plan was established in 2001, which defines rural tourism as an attraction that offers visitors the opportunity to experience Malaysia’s traditional culture and heritage away from urban areas. This study focuses on such tourism in the Gunung Mulu National Park, a famous natural park comprising underground caves, virgin rainforests and highlands. This research uses a quantitative approach with a random sampling technique because the procedure to select a unit for inclusion in a sample is much easier, quicker and cheaper. A questionnaire is distributed via Google Form to 500 local tourists who visited the park. The results of this research may be useful in marketing the Gunung Mulu National Park worldwide, besides fine-tuning programmes to attract tourists to the national park.
    Matched MeSH terms: Rainforest
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