Displaying publications 1 - 20 of 522 in total

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  1. van der Werf GR, Dempewolf J, Trigg SN, Randerson JT, Kasibhatla PS, Giglio L, et al.
    Proc. Natl. Acad. Sci. U.S.A., 2008 Dec 23;105(51):20350-5.
    PMID: 19075224 DOI: 10.1073/pnas.0803375105
    Drainage of peatlands and deforestation have led to large-scale fires in equatorial Asia, affecting regional air quality and global concentrations of greenhouse gases. Here we used several sources of satellite data with biogeochemical and atmospheric modeling to better understand and constrain fire emissions from Indonesia, Malaysia, and Papua New Guinea during 2000-2006. We found that average fire emissions from this region [128 +/- 51 (1sigma) Tg carbon (C) year(-1), T = 10(12)] were comparable to fossil fuel emissions. In Borneo, carbon emissions from fires were highly variable, fluxes during the moderate 2006 El Niño more than 30 times greater than those during the 2000 La Niña (and with a 2000-2006 mean of 74 +/- 33 Tg C yr(-1)). Higher rates of forest loss and larger areas of peatland becoming vulnerable to fire in drought years caused a strong nonlinear relation between drought and fire emissions in southern Borneo. Fire emissions from Sumatra showed a positive linear trend, increasing at a rate of 8 Tg C year(-2) (approximately doubling during 2000-2006). These results highlight the importance of including deforestation in future climate agreements. They also imply that land manager responses to expected shifts in tropical precipitation may critically determine the strength of climate-carbon cycle feedbacks during the 21st century.
    Matched MeSH terms: Ecosystem
  2. van der Ent A, Mak R, de Jonge MD, Harris HH
    Sci Rep, 2018 06 26;8(1):9683.
    PMID: 29946061 DOI: 10.1038/s41598-018-26891-7
    Hyperaccumulation is generally highly specific for a single element, for example nickel (Ni). The recently-discovered hyperaccumulator Glochidion cf. sericeum (Phyllanthaceae) from Malaysia is unusual in that it simultaneously accumulates nickel and cobalt (Co) with up to 1500 μg g-1 foliar of both elements. We set out to determine whether distribution and associated ligands for Ni and Co complexation differ in this species. We postulated that Co hyperaccumulation coincides with Ni hyperaccumulation operating on similar physiological pathways. However, the ostensibly lower tolerance for Co at the cellular level results in the exudation of Co on the leaf surface in the form of lesions. The formation of such lesions is akin to phytotoxicity responses described for manganese (Mn). Hence, in contrast to Ni, which is stored principally inside the foliar epidermal cells, the accumulation response to Co consists of an extracellular mechanism. The chemical speciation of Ni and Co, in terms of the coordinating ligands involved and principal oxidation state, is similar and associated with carboxylic acids (citrate for Ni and tartrate or malate for Co) and the hydrated metal ion. Some oxidation to Co3+, presumably on the surface of leaves after exudation, was observed.
    Matched MeSH terms: Ecosystem
  3. da Silva LG, Kawanishi K, Henschel P, Kittle A, Sanei A, Reebin A, et al.
    PLoS ONE, 2017;12(4):e0170378.
    PMID: 28379961 DOI: 10.1371/journal.pone.0170378
    The geographic distribution and habitat association of most mammalian polymorphic phenotypes are still poorly known, hampering assessments of their adaptive significance. Even in the case of the black panther, an iconic melanistic variant of the leopard (Panthera pardus), no map exists describing its distribution. We constructed a large database of verified records sampled across the species' range, and used it to map the geographic occurrence of melanism. We then estimated the potential distribution of melanistic and non-melanistic leopards using niche-modeling algorithms. The overall frequency of melanism was ca. 11%, with a significantly non-random spatial distribution. Distinct habitat types presented significantly different frequencies of melanism, which increased in Asian moist forests and approached zero across most open/dry biomes. Niche modeling indicated that the potential distributions of the two phenotypes were distinct, with significant differences in habitat suitability and rejection of niche equivalency between them. We conclude that melanism in leopards is strongly affected by natural selection, likely driven by efficacy of camouflage and/or thermoregulation in different habitats, along with an effect of moisture that goes beyond its influence on vegetation type. Our results support classical hypotheses of adaptive coloration in animals (e.g. Gloger's rule), and open up new avenues for in-depth evolutionary analyses of melanism in mammals.
    Matched MeSH terms: Ecosystem
  4. Zvonareva S, Kantor Y
    Zootaxa, 2016 Sep 12;4162(3):401-37.
    PMID: 27615983 DOI: 10.11646/zootaxa.4162.3.1
    Gastropod molluscs are one of the most important components of mangrove ecosystem. Mangroves in Central Vietnam have a rather limited distribution due to peculiarities of the coastline morphology and presently their fauna remains understudied. Extensive surveys were conducted in both natural vegetation and artificial mangrove plantations in several localities in Nha Trang Bay from 2005 to 2015. In total 65 species of gastropod molluscs were found alive, 17 of which can be considered as predominantly mangrove-associated. An illustrated guide is provided, with short synonymies and data on ecology and distribution. The recorded molluscan diversity is compared with published data on mangrove gastropods in different regions of the Indo-Pacific. Total species number and the proportion of mangrove-associated species are similar to studied faunas in Hong Kong, Malaysia and Thailand, but the diversity is much lower than that of the mangal fauna of the Philippines.
    Matched MeSH terms: Ecosystem
  5. Zulkafli Abdul Rashid, Mohammad Noor Azmai Amal
    Sains Malaysiana, 2018;47:1941-1951.
    This study assesses the influence of water quality on fish occurrences in Sungai Pahang, Maran District, Pahang, Malaysia. Water quality and fish samplings were conducted at seven sampling sites in the district for 13 consecutive months. We used canonical correspondence analyses (CCA) to determine the influence of water quality on monthly fish species occurrences. The ranges of water quality parameters were quite high considering the measurements were made during rainy and dry seasons throughout the year. A total of 2,075 individual fish was captured which comprised of 22 different families and 65 species. Family Cyprinidae recorded the highest number of fish species of the area (27 species; 41.5%), followed by Bagridae (five species; 7.69%) and Pangasiidae (five species; 7.69%). Three fish species categorized as endangered, including Balantiocheilos melanopterus, Probarbus jullieni and Pangasianodon hypophthalmus were also collected. The collected fish species were divided into three groups (A to C), which was clearly separated in the CCA ordination diagram. The most important water quality variables for the fish occurrences in this river were pH, followed by temperature, conductivity, alkalinity and phosphate. Data analysis indicates that the occurrence of fishes were influenced by a combination of water quality parameters, but not associated with sampling month. The results present a new data from a study of fish assemblage and their habitat condition which may be important in fisheries activity and fish conservation of the river in the future.
    Matched MeSH terms: Ecosystem
  6. Zulfa, A.W., Norizah, K.
    MyJurnal
    The mangrove forest ecosystem acts as a shield against the destructive tidal waves, preventing the coastal areas and other properties nearby from severe damages; this protective function certainly deserves attention from researchers to undertake further investigation and exploration. Mangrove forest provides different goods and services. The unique environmental factors affecting the growth of mangrove forest are as follows: distance from the sea or the estuary bank, frequency and duration of tidal inundation, salinity, and composition of the soil. These crucial factors may under certain circumstances turn into obstacles in accessing and managing the mangrove forest. One effective method to circumvent this shortcoming is by using remotely sensed imagery data, which offers a more accurate way of measuring the ecosystem and a more efficient tool of managing the mangrove forest. This paper attempts to review and discuss the usage of remotely sensed imagery data in mangrove forest management, and how they will improve the accuracy and precision in measuring the mangrove forest ecosystem. All types of measurements related to the mangrove forest ecosystem, such as detection of land cover changes, species distribution mapping and disaster observation should take advantage of the advanced technology; for example, adopting the digital image processing algorithm coupled with high-resolution image available nowadays. Thus, remote sensing is a highly efficient, low-cost and time-saving technique for mangrove forest measurement. The application of this technique will further add value to the mangrove forest and enhance its in-situ conservation and protection programmes in combating the effects of the rising sea level due to climate change.
    Matched MeSH terms: Ecosystem
  7. Zhang JX, Maddison WP
    Zootaxa, 2014;3852(2):252-72.
    PMID: 25284396 DOI: 10.11646/zootaxa.3852.2.5
    Six new species of marpissoid jumping spiders from Sarawak, Borneo, are described in the new genus Tisaniba Zhang & Maddison. They are the type species, T. mulu Zhang & Maddison sp. nov., as well as the species T. bijibijan Zhang & Maddison sp. nov., T. dik Zhang & Maddison sp. nov., T. kubah Zhang & Maddison sp. nov., T. selan Zhang & Maddison sp. nov., and T. selasi Zhang & Maddison sp. nov. The spiders are small and brown to black, living in leaf litter in the tropical forest. Phylogenetic analyses based on 28s and 16sND1 genes indicate that they are a distinctive group within the marpissoids. Diagnostic illustrations and photographs of living spiders are provided for all species.
    Matched MeSH terms: Ecosystem
  8. Zaleha K, Nasiratul_shahida MN, Siang HY, Kamaruzzaman BY
    Sains Malaysiana, 2016;45:1019-1024.
    Meiobenthos in Bidong Archipelago in coastal water of the South China Sea is hypothesised to have a certain trend of
    distribution particularly in the island ecosystem where it is usually having different type of sea bottom. Nonetheless, since
    it is located in a tropical area, the trend at the sub-tidal could be less obvious due to absent of clear season. Meiobenthic
    sampling was carried out in Karah Island, an island in Bidong Archipelago, from the intertidal, towards the sub-tidal
    zone covering the coral and non-coral area to see the trend in the density and composition. A transparent hand core
    was used to collect benthos samples. Nematoda and harpacticoid copepods dominated the intertidal and sub-tidal zone
    respectively. Harpacticoid copepods were higher in density in the non-coral sediment than the coral area. This could be
    due to the high content of silt and clay in the coral area (2.98% of silt and clay). The 2-dimension MDS analysis on the
    density data indicated the highest degree of scattering and an over-lapping condition for those intertidal and sub-tidal
    samples respectively. ANOSIM result showed that the degree of similarity was lower at the intertidal (70%) than the subtidal
    (reaching 90%) in the first sampling before both became no significant different in the second sampling. It could
    indicate the stable condition in the subtidal than the intertidal ecosystem. The comparatively low density of meiobenthos
    could indicate their response towards the environmental condition in the area which will only be confirmed by long term
    ecological study.
    Matched MeSH terms: Ecosystem
  9. Zakri, A.H.
    ASM Science Journal, 2009;3(2):200-202.
    MyJurnal
    Recent studies by the United Nations University - Institute of Advanced Studies (UNU-IAS) demonstrate that bioprospecting is taking place in Antarctica and the Southern Ocean and that related commercial applications were being marketed. The bioprospectors’ interest in Antarctica stems from two reasons. First, the lack of knowledge surrounding Antarctic biota provides opportunities to discover novel organisms of potential use to biotechnology. Second, Antarctica’s environmental extremes, such as cold temperatures, extreme aridity and salinity present conditions in which biota have evolved unique characteristics for survival (UNU-IAS 2003). Thus bioprospecting opportunities include, inter alia, the discovery of novel bioactives in species found in cold and dry lithic habitat, novel pigments found in hyper-saline lakes and antifreezes in sea-lakes (Cheng & Cheng 1999).
    Matched MeSH terms: Ecosystem
  10. Zakaria MH, Amin SM, Rahman MA, Arshad A, Christianus A, Siraj SS
    Pak. J. Biol. Sci., 2012 Jul 01;15(13):604-9.
    PMID: 24218929
    The freshwater fish, Probarbus jullieni (Sauvage), locally referred to as "Temoleh", is a high-valued freshwater fish in Malaysia and has both cultural and conservational significance. It is widely distributed in the North-east Asian countries such as Thailand, Cambodia, Vietnam and Malaysia. During the recent past, the natural stocks of P. jullieni have been decreased severely due to habitat degradation and man-induced hazards in aquatic ecosystem. Despite the vast research that has been conducted on various carp species, little attention has been given to P. jullieni. This study reviewed the published information on the status, distribution, reproduction and biodiversity of this commercially important fish species. The findings would greatly be helpful towards the species conservation and aquaculture development of the highly endangered P. jullieni.
    Matched MeSH terms: Ecosystem
  11. Zakaria L, Yee TL, Zakaria M, Salleh B
    Trop Life Sci Res, 2011 May;22(1):71-80.
    PMID: 24575210 MyJurnal
    A total of 82 isolates of microfungi were isolated from 6 sandy soil samples collected from Teluk Aling beach, Pulau Pinang. The soil microfungi were isolated by using direct isolation, debris isolation and soil dilution techniques. Based on morphological characteristics, seven genera of microfungi were identified namely, Fusarium (42%), Aspergillus (24%), Trichoderma (13%), Curvularia (9%), Colletotrichum (6%), Helminthosporium (4%) and Penicillium (2%). The most common species isolated was Fusarium solani followed by Fusarium semitecum, Aspergillus niger, Trichoderma viride, Curvularia clavata, Curvularia lunata, Helminthosporium velutinum, Colletotrichum sp. and Penicillium chrysogenum. From the present study, it appears that the sandy beach contains a microfungi reservoir comprising of a variety of genera which contributes significantly to the ecological functioning of a marine ecosystem.
    Matched MeSH terms: Ecosystem
  12. Zaidi Che Cob, Aziz Arshad, Japar Sidik Bujang, Mazlan Abd Ghaffar
    Sains Malaysiana, 2014;43:503-511.
    The abundance of marine benthic organisms often exhibits distinct distributional patterns, which is generally governed by many physical and biological factors specific to the habitat. In this study, the spatial and temporal variations in abundance of the dog conch, Strombus canarium Linnaeus 1758, a commercially important marine gastropod, was investigated. Assessment of conch abundance at Merambong seagrass bed, Malaysia, was conducted using a transect belt method. Sampling stations were randomly selected and environmental parameters associated with the habitat were recorded. The species showed distinct spatial distributional pattern. Conch densities were significantly higher in sheltered areas, mainly in mixed seagrass bed dominated by Halophila spp. and with high sediment organic content. The densities were relatively very low in areas dominated by the tape seagrass, Enhalus acoroides. The species studied also showed distinct temporal variation in abundance. The abundance value was seasonally varied with highest density recorded during the wet monsoon season (p<0.05). The densities were otherwise very low during the dry season, except for a slight peak in July. Since the conch is a very important fishery species within the Johor Straits and regulations on their harvesting is still lacking, this information would be very important for their sustainable management.
    Matched MeSH terms: Ecosystem
  13. Yunus AJ, Nakagoshi N, Salleh KO
    J Environ Sci (China), 2003 Mar;15(2):249-62.
    PMID: 12765268
    This study investigate the relationships between geomorphometric properties and the minimum low flow discharge of undisturbed drainage basins in the Taman Bukit Cahaya Seri Alam Forest Reserve, Peninsular Malaysia. The drainage basins selected were third-order basins so as to facilitate a common base for sampling and performing an unbiased statistical analyses. Three levels of relationships were observed in the study. Significant relationships existed between the geomorphometric properties as shown by the correlation network analysis; secondly, individual geomorphometric properties were observed to influence minimum flow discharge; and finally, the multiple regression model set up showed that minimum flow discharge (Q min) was dependent of basin area (AU), stream length (LS), maximum relief (Hmax), average relief (HAV) and stream frequency (SF). These findings further enforced other studies of this nature that drainage basins were dynamic and functional entities whose operations were governed by complex interrelationships occurring within the basins. Changes to any of the geomorphometric properties would influence their role as basin regulators thus influencing a change in basin response. In the case of the basin's minimum low flow, a change in any of the properties considered in the regression model influenced the "time to peak" of flow. A shorter time period would mean higher discharge, which is generally considered the prerequisite to flooding. This research also conclude that the role of geomorphometric properties to control the water supply within the stream through out the year even though during the drought and less precipitations months. Drainage basins are sensitive entities and any deteriorations involve will generate reciprocals and response to the water supply as well as the habitat within the areas.
    Matched MeSH terms: Ecosystem*
  14. Yonge CM
    Biol. Bull., 1968 Oct;135(2):378-405.
    PMID: 28368764 DOI: 10.2307/1539789
    1. Study of the structure and mode of life of Malleus regula provides the basis for consideration of the "hammer" species, M. malleus and M. albus.
    2. M. regula occurs byssally attached, vertically disposed on rocky substrates associated with mud and is widely distributed in the tropical Indo-Pacific.
    3. The distal two-thirds of the elongated shell is exclusively prismatic. By means of special pallial retractors the mantle lobes can be withdrawn within the nacreous region.
    4. The massive opisthodetic ligament has a short secondary extension of fusion layer.
    5. A promyal chamber on the right side proximal to the adductor increases water flow into the exhalant chamber.
    6. The long filibranch ctenidia provide a vertically extended food-collecting surface.
    7. The foot is concerned with planting of the massive byssus which emerges through a notch in the right valve but on the under ( i.e., dorsal) surface. There is also a unique and very long accessory foot, ventrally grooved, everywhere ciliated and in constant writhing activity due to blood pressure and intrinsic muscle. Moving freely throughout the lower mantle cavity it can only be concerned with cleansing.
    8. Pseudofaeces are ejected from the distal tip of the mantle cavity.
    9. M. malleus, the black hammer shell, occurs vertically embedded in coarse sand or sandy gravel. Byssus threads are attached to fragments within the substrate. The great anterior and posterior elongations of the hinge line (also exclusively prismatic) are separated by the byssal notch (now affecting both valves).
    10. Shells are usually excessively irregular due to the great exposure to damage and the almost unlimited powers of rapid repair by the three pallial extensions.
    11. M. albus, the white hammer shell, is stouter and inhabits muddy sand. During growth it loses the byssus with reduction of the foot and byssal retractors and closure of the byssal notch. The accessory foot is not affected. The animal becomes anchored in the substrate exclusively by the anterior and posterior extensions of the shell.
    12. Description of the typically rounded Isognomon ephippium leads to that of the elongated I. isognomon which occupies precisely the same habitat as M. regula.
    13. It lacks the pallial retractors, promyal chamber and accessory foot of Malleus, the nacreous region is more extended distally and the ligament is multivincular (the formation of which is discussed), producing some posterior, but never any anterior, extension of the hinge line.
    14. A remarkably dense mixed bed of M. regula and I. isognomon in Darvel Bay, Sabah (Borneo), is described. Different spawning periods, by preventing competition during settlement, may account for this complete intermixing of sympatric species, which, however, are generalized herbivores where numbers are not limited by food supply.
    15. From a basic epifaunal habit (Pteria, Isognomon, M. regula), members of the Pteriacea have become adapted for infaunal life within sponges (Vulsella, Crenatula) or within soft substrates ( M. malleus, M. alba and the Pinnidae).
    16. There is final discussion about elongation in monomyarians, i.e., in the genus Malleus and in I. isognomon.
    Matched MeSH terms: Ecosystem
  15. Yin ZW, Li LZ
    Zootaxa, 2014;3850:1-83.
    PMID: 25112427 DOI: 10.11646/zootaxa.3850.1.1
    The Oriental pselaphine genus Horniella Raffray, 1905 (tribe Tyrini: subtribe Somatipionina) is redefined and revised. Twenty-five new species are described: H. centralis Yin & Li, sp. n., H. confragosa Yin & Li, sp. n., H. dao Yin & Li, sp. n., H. hongkongensis Yin & Li, sp. n., H. nakhi Yin & Li, sp. n., H. schuelkei Yin & Li, sp. n., H. sichuanica Yin & Li, sp. n., H. simplaria Yin & Li, sp. n., and H. tianmuensis Yin & Li, sp. n. from China, H. himalayica Yin & Li, sp. n. from Nepal and North India, H. asymmetrica Yin & Li, sp. n., H. burckhardti Yin & Li, sp. n., H. intricata Yin & Li, sp. n., H. kaengkrachan Yin & Li, sp. n., H. khaosabap Yin & Li, sp. n., H. loebli Yin & Li, sp. n., H. phuphaman Yin & Li, sp. n., H. prolixo Yin & Li, sp. n., and H. schwendingeri Yin & Li, sp. n. from Thailand, H. philippina Yin & Li, sp. n. from the Philippines, H. awana Yin & Li, sp. n., H. gigas Yin & Li, sp. n., H. pilosa Yin & Li, sp. n., and H. smetanai Yin & Li, sp. n. from Malaysia, and H. cibodas Yin & Li, sp. n. from Indonesia. The two previously described species, H. hirtella Raffray, 1901 (type species) from Sri Lanka and H. falcis Yin & Li, 2010 from China are redescribed, and a lectotype is designated for H. hirtella. Illustrations of habitus and important diagnostic features, an identification key, and distributional maps for all species are provided. Eleven unidentified species represented only by females are left unnamed. Illustrations of the habitus and the genital complex, and label data of these species are given to facilitate future study. All available data indicates that species of Horniella typically inhabit leaf litter of various kinds of forests, and can be most efficiently collected by sifting and use of Winkler-Moczarski extractors. 
    Matched MeSH terms: Ecosystem
  16. Yeong KC, Takizawa H, Liew TS
    PeerJ, 2018;6:e5811.
    PMID: 30386703 DOI: 10.7717/peerj.5811
    Sabah is a province of Malaysia located on the northern part of the island of Borneo. Most of the leaf beetle fauna studies from this region conducted over the past 15 years have focussed on the mainland habitats while the leaf beetle fauna from island habitats (ca. 500 islands) have largely been overlooked. This study looks into the leaf beetle fauna of 13 small satellite islands off the west coast of Sabah. All specimens were first sorted into morpho-species operational taxonomic unit (OTU) before being identified to species rank where possible based on morphological characters and species names assigned when the specimens fitted the description of species in the literature. We collected 75 OTUs from 35 genera and five subfamilies according to morphology, 12 of which were identifiable to species level. In addition, the DNA barcode for each OTU was cross checked with records in GenBank and Barcoding of Life Data system (BOLD) to verify their identity. The number of species recorded was reduced from 12 species and 63 OTUs (total 75 OTUs) to 12 species and 56 OTUs (total 68 OTUs) after removal of the colour polymorphic species based on DNA barcode analyses. Pulau Gaya has the highest species richness and Pulau Sulug has the lowest species richness. A total of 64 Barcode Index Numbers consisting of 101 DNA barcodes were obtained from the 12 leaf beetle species and 48 OTUs. Based on the DNA barcode analyses, it was possible to confirm several polymorphic OTUs and cryptic species. The mean intraspecific and interspecific genetic divergence were determined as 0.77% and 16.11%, respectively. DNA barcodes of this study show a low similarity with records in GenBank and BOLD, highlighting the lack of representation and the urgency of studying leaf beetles from this region. The study provides the first documentation of leaf beetle fauna from island habitats of Sabah and the first DNA barcoding data for leaf beetles from this part of the world, with the next steps being larger scale sampling over a wider geographical scale for a better understanding of tropical arthropod diversity.
    Matched MeSH terms: Ecosystem
  17. Yeang HY
    New Phytol., 2007;175(2):283-9.
    PMID: 17587376
    How tropical trees flower synchronously near the equator in the absence of significant day length variation or other meteorological cues has long been a puzzle. The rubber tree (Hevea brasiliensis) is used as a model to investigate this phenomenon. The annual cycle of solar radiation intensity is shown to correspond closely with the flowering of the rubber tree planted near the equator and in the subtropics. Unlike in temperate regions, where incoming solar radiation (insolation) is dependent on both day length and radiation intensity, insolation at the equator is due entirely to the latter. Insolation at the upper atmosphere peaks twice a year during the spring and autumn equinoxes, but the actual solar radiation that reaches the ground is attenuated to varying extents in different localities. The rubber tree shows one or two flowering seasons a year (with major and minor seasons in the latter) in accordance with the solar radiation intensity received. High solar radiation intensity, and in particular bright sunshine (as distinct from prolonged diffuse radiation), induces synchronous anthesis and blooming in Hevea around the time of the equinoxes. The same mechanism may be operational in other tropical tree species.
    Matched MeSH terms: Ecosystem
  18. Yazid SNE, Thanggavelu H, Mahror N, Selamat J, Samsudin NIP
    Int. J. Food Microbiol., 2018 Oct 03;282:57-65.
    PMID: 29913332 DOI: 10.1016/j.ijfoodmicro.2018.06.007
    In studying the ecophysiology of fungal phytopathogens, several stages are involved (in vitro, greenhouse, in planta). Most in vitro studies extensively utilise the general growth media such as Potato Dextrose Agar and Malt Extract Agar. Although the crop components in these media serve as excellent carbon sources and yield luxuriant growth, they are not naturally contaminated with Aspergillus flavus and thus might result in under- or overestimation of its actual toxigenic potentials. Empirical data on the formulation of semi-synthetic growth medium mimicking the natural crop commonly contaminated by A. flavus for the ecophysiological studies in vitro are scarce. The present work was aimed at investigating the ecophysiology of A. flavus on commercial growth media (PDA, MEA); formulating maize- and peanut-based semi-synthetic growth media using two methods of raw material preparation (milling, hot water extraction) at different concentrations (1, 3, 5, 7, 9% w/v), and comparing the ecophysiological parameters between commercial and formulated growth media. Growth rates were obtained by computing the hyphal expansion data into y = mx + c equation. AFB1 was quantified using high performance liquid chromatography with fluorescence detector. Formulated media were found to yield significantly higher growth rates when compared to commercial media. However, commercial media yielded significantly higher AFB1 when compared to all formulated media. Between the two formulations, milling yielded significantly higher growth rates and AFB1 when compared to hot water extraction. Although in vitro data cannot directly extrapolate in planta performance, results obtained in the present work can be used to gauge the actual toxigenic potential of A. flavus in maize and peanut agro-ecosystems.
    Matched MeSH terms: Ecosystem
  19. Yap C, Noorhaidah A
    Sains Malaysiana, 2011;40:1075-1085.
    In this paper we investigated the concentrations of Pb in seven different soft tissues (foot, cephalic tentacles, mantle muscle, gill, digestive caecum and remaining soft tissues) of 17 geographical populations of Telescopium telescopium collected from the intertidal area of Peninsular Malaysia. Two points can be presented based on the present study. First, as expected, different concentrations of Pb were found in the different soft tissues, indicating different mechanisms of bioaccumulation and regulations of Pb in these different tissues. By comparing the Pb concentrations in the similar tissues, spatial variation of Pb was found in the different sampling sites although there is no consistent pattern of Pb contamination in these sampling sites. Second, based on the correlation coefficients and multiple linear stepwise regression analysis between Pb concentrations in the different soft tissues and Pb concentrations in geochemical factions in the surface sediments, it is found that gill and digestive caecum can truly reflect Pb contamination and Pb bioavailabilities in the tropical intertidal mudflats. To our knowledge, this is the most comprehensive study on Pb in the different soft tissues of T. telescopium, in relation to the habitat sediments of the snails.
    Matched MeSH terms: Ecosystem
  20. Yamada T, Yamada Y, Okuda T, Fletcher C
    Oecologia, 2013 Jul;172(3):713-24.
    PMID: 23183820 DOI: 10.1007/s00442-012-2529-z
    Differences in the density of conspecific tree individuals in response to environmental gradients are well documented for many tree species, but how such density differences are generated and maintained is poorly understood. We examined the segregation of six dipterocarp species among three soil types in the Pasoh tropical forest, Malaysia. We examined how individual performance and population dynamics changed across the soil types using 10-year demographic data to compare tree performance across soil types, and constructed population matrix models to analyze the population dynamics. Species showed only minor changes in mortality and juvenile growth across soil types, although recruitment differed greatly. Clear, interspecific demographic trade-offs between growth and mortality were found in all soil types. The relative trade-offs by a species did not differ substantially among the soil types. Population sizes were projected to remain stable in all soil types for all species with one exception. Our life-table response experiment demonstrated that the population dynamics of a species differed only subtly among soil types. Therefore, species with strong density differences across soil types do not necessarily differ greatly in their population dynamics across the soil types. In contrast, interspecific differences in population dynamics were large. The trade-off between mortality and growth led to a negative correlation between the contributions of mortality and growth to variations in the population growth rate (λ) and thus reduced their net contributions. Recruitment had little impact on the variation in λ. The combination of these factors resulted in little variation in λ among species.
    Matched MeSH terms: Ecosystem*
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