Explaining the abundance of ants in lowland tropical rainforest canopies     

Davidson DW  Cook SC  Snelling RR  Chua TH 《Science (New York, N.Y.)》2003,300(5621):969-972

The extraordinary abundance of ants in tropical rainforest canopies has led to speculation that numerous arboreal ant taxa feed principally as "herbivores" of plant and insect exudates. Based on nitrogen (N) isotope ratios of plants, known herbivores, arthropod predators, and ants from Amazonia and Borneo, we find that many arboreal ant species obtain little N through predation and scavenging. Microsymbionts of ants and their hemipteran trophobionts might play key roles in the nutrition of taxa specializing on N-poor exudates. For plants, the combined costs of biotic defenses and herbivory by ants and tended Hemiptera are substantial, and forest losses to insect herbivores vastly exceed current estimates.  相似文献   

Modulation of acetaminophen-induced hepatotoxicity by the xenobiotic receptor CAR     

Zhang J  Huang W  Chua SS  Wei P  Moore DD 《Science (New York, N.Y.)》2002,298(5592):422-424

We have identified the xenobiotic receptor CAR (constitutive androstane receptor) as a key regulator of acetaminophen metabolism and hepatotoxicity. Known CAR activators as well as high doses of acetaminophen induced expression of three acetaminophen-metabolizing enzymes in wild-type but not in CAR null mice, and the CAR null mice were resistant to acetaminophen toxicity. Inhibition of CAR activity by administration of the inverse agonist ligand androstanol 1 hour after acetaminophen treatment blocked hepatotoxicity in wild type but not in CAR null mice. These results suggest an innovative therapeutic approach for treating the adverse effects of acetaminophen and potentially other hepatotoxic agents.  相似文献   

Anticancer Potential of Syzygium Species: a Review     

Chua  Lee Kee  Lim  Chooi Ling  Ling  Anna Pick Kiong  Chye  Soi Moi  Koh  Rhun Yian 《Plant foods for human nutrition (Dordrecht, Netherlands)》2019,74(1):18-27

Plant Foods for Human Nutrition - Cancer is a preventable and treatable disease, however, the incidence rates are on the rise. Classical treatment modalities for cancer include surgery,...  相似文献   

Molecular fingerprinting of Riemerella anatipestifer by repetitive sequence PCR.   总被引：6，自引：0，他引：6  

B Huang  S Subramaniam  K L Chua  J Kwang  H Loh  J Frey  H M Tan 《Veterinary microbiology》1999,67(3):213-219

Riemerella anatipestifer is a gram-negative rod-shaped bacterium associated with epizootic infections in poultry. A total of 35 R. anatipestifer isolates including the type strain ATCC11845T, reference and field strains for 18 different serotypes were characterized by repetitive sequence based-PCR (rep-PCR) with outwardly-directed primers based on the repetitive extragenic palindromic (REP) consensus sequence. This technique was applied by using either extracted genomic DNA or preparation of whole bacterial cells harvested directly from plate cultures. Rep-PCR discriminated the R. anatipestifer isolates into 19 electrophoretic types. DNA fingerprints obtained from rep-PCR of extracted genomic DNA or from preparations of whole cells yielded comparable patterns. Substantial variation was seen among the rep-PCR fingerprints of different serotypes. Moreover, different polymorphisms of the rep-PCR fingerprints were evident among epidemiologically unrelated isolates of the same serotype. These results suggest the presence of repetitive extragenic palindromic-like elements within the genome of R. anatipestifer that can be used in some isolates to discriminate between different strains belonging to the same serotype. Rep-PCR may serve as a useful molecular tool for subtyping R. anatipestifer isolates for epidemiologic investigations. The whole cell procedure offers the advantage of ease of performance requiring only small quantities of cells.  相似文献   

Ameliorative Effects of Melatonin against Hydrogen Peroxide‐Induced Oxidative Stress on Boar Sperm Characteristics and Subsequent In Vitro Embryo Development     

HY Jang  YH Kim  BW Kim  IC Park  HT Cheong  JT Kim  CK Park  HS Kong  HK Lee  BK Yang 《Reproduction in domestic animals》2010,45(6):943-950

Melatonin, the major secretory product of the pineal gland, scavenges a variety of reactive oxygen and nitrogen species in vivo and in vitro, indicating that melatonin is a potent function as an antioxidant. The objective of this study was to investigate the effect of melatonin in the presence or absence of hydrogen peroxide (H₂O₂) on sperm characteristics (motility, viability, survival rate, membrane integrity, lipid peroxidation (LPO) and mitochondria activity) and also to examine the developmental rates to the blastocysts stage of porcine oocytes fertilized in vitro with semen treated with or without melatonin (100 nm ) in the presence or absence of H₂O₂ (250 μm ). The sperm were treated with melatonin in the presence or absence of H₂O₂ for 3, 6, 9 and 12 h at 37°C and then analysed for the sperm characteristics. The porcine embryos were produced by in vitro maturation and in vitro fertilization (IVM/IVF) using semen treated with or without melatonin (100 nm ) in the presence or absence of H₂O₂ (250 μm ) for 6 h. The semen characteristics, including motility, viability, survival rate, membrane integrity and mitochondria activity, were higher in the groups that were treated with melatonin in comparison to other groups, irrespective of incubation periods. Malondialdehyde levels in control, melatonin and melatonin + H₂O₂ groups were lower than H₂O₂ only group. A positive correlation was shown among motility, viability, survival rate and membrane integrity, but a negative correlation was observed between LPO and the other evaluation methods. The developmental rates to blastocysts of IVM/IVF porcine oocytes fertilized by semen treated with melatonin were significantly increased compared with any other groups, with the cell number of blastocysts shown to have a similar trend to the developmental rates. These results demonstrate that melatonin can improve the semen characteristics during in vitro storage and support the developmental ability of IVM/IVF embryos in pigs.  相似文献   

Purification, cloning, and identification of two thaumatin-like protein isoforms in jelly fig (Ficus awkeotsang) Achenes     

Chua AC  Chou WM  Chyan CL  Tzen JT 《Journal of agricultural and food chemistry》2007,55(18):7602-7608

Jelly curd used for a popular summer drink in Taiwan is prepared by extracting the pericarpial portion of jelly fig (Ficus awkeotsang Makino) achenes. The two most abundant proteins found in jelly curd have been identified as a pectin methylesterase and a chitinase. A method was developed to purify the next abundant protein by 40% ammonium sulfate precipitation and flowing through Mono Q chromatography. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses, the purified protein migrated as a polypeptide of 20 kDa in the absence of beta-mercaptoethanol but split into a minor polypeptide of 20 kDa and a major polypeptide of 27 kDa in the presence of this reducing agent. Two cDNA fragments encoding precursor polypeptides of two putative thaumatin-like protein isoforms were obtained by polymerase chain reaction cloning and subsequently overexpressed in Escherichia coli to generate recombinant proteins for antibody preparations. Immunological detection and mass spectrometric analyses indicated that the two split polypeptides were thaumatin-like protein isoforms encoded by the two cloned cDNA fragments.  相似文献   

桑天牛成虫行为及雄虫辐射不育的研究     

彭镇华  王善武  崔应时 《安徽农业大学学报》1994,(Z1)

观察了桑天牛成虫行为,初步研究了６０Ｃｏγ射线对雄虫的辐射效应。研究结果表明：雄虫占６０％,飞翔能力强寿命长,雌雄虫需在构、桑树上进行补充营养,交尾均不止１次,雌虫产卵量大;６０Ｃｏγ射线对雄虫取食、活力、寿命、交尾及孵化幼虫,均有明显影响,雄虫不育剂量的上限为１６３．２Ｇγ。  相似文献   

Organ-specific and light-induced expression of plant genes     

Fluhr R  Kuhlemeier C  Nagy F  Chua NH 《Science (New York, N.Y.)》1986,232(4754):1106-1112

  相似文献   

Assessment of Genetic Variability in the Coding Sequence of Melatonin Receptor Gene (MTNR1A) in Tropical Arid Sheep Breeds of India          下载免费PDF全文

VK Saxena  BK Jha  AS Meena  HK Narula  D Kumar  SMK Naqvi 《Reproduction in domestic animals》2015,50(3):517-521

Seasonal behaviour in sheep, which varies in tropical and temperate environmental conditions, is a matter of study, because it can provide a clue to address the problem of seasonality in sheep. Melatonin receptor is the membrane‐bound G‐coupled receptor, sensing the message of photoperiodic cues thorough melatonin. Restriction fragment length polymorphism (RFLP) studies were carried out to assess the variability of gene at G612A and C606T SNPs in MTNR1A gene, which have been studied to be markers for out‐of‐season breeding. Allelic frequency distribution corresponded to higher frequency of GG and CC genotype, in tropical arid sheep breed in comparison with temperate region sheep breed. PCR amplification of MTNR1A gene of 30 animals was performed and single nucleotide polymorphisms (SNPs) identification was carried out using Lasergene software. Seven SNPs/mutations were identified, but most of them were synonymous, except the one G706A, leading to substitution of valine by isoleucine. Polyphen‐2 analysis of G706A mutation revealed that it is a benign mutation. Two important SNPs C426T and G555A, which were identified in temperate sheep breeds, could not be traced in Magra and Marwari breeds of sheep. Thus, the Magra and Marwari breeds of tropical, arid region demonstrated the presence of both polymorphic SNPs markers G612A and C606T, associated with out‐of‐season breeding. GG and CC genotypes were having a higher prevalence in the studied population.  相似文献   

Species determination of Malaysian Bactrocera pests using PCR‐RFLP analyses (Diptera: Tephritidae)     

Tock H Chua  Yi Vern Chong  Saw Hoon Lim 《Pest management science》2010,66(4):379-384

BACKGROUND: Identification of Bactrocera carambolae Drew and Hancock, B. papayae Drew and Hancock, B. tau Walker, B. latifrons Hendel, B. cucurbitae Coquillett, B. umbrosa Fabricius and B. caudata Fabricius would pose a problem if only a body part or an immature stage were available. Analysis of polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) of cytochrome oxidase I (COI) gene using primers COIR, COIF, UEA7 and UEA10 and restriction enzymes (MseI, RsaI and Alu1) was carried out. The banding profiles in the electrophoresis gel were analysed. RESULTS: The COI gene in six Bactrocera spp. was successfully amplified by COIR and COIF, as well as UEA7 and UEA10, while B. caudata was amplified successfully only by UEA primers. Using COI amplified PCR products and restriction enzymes, distinct banding profiles for B. tau, B. latifrons, B. cucurbitae and B. umbrosa were observed, but not for B. carambolae and B. papayae. However, using UEA7, UEA10 and RsaI, B. caudata could be identified, while B. carambolae and B. papayae might possibly be separated from one another. It was also shown that adult body parts or immature life stages of B. carambolae, B. papayae, B. latifrons and B. cucurbitae produced the same banding profiles as the adults. CONCLUSION: PCR‐RFLP analyses are able to identify positively five Bactrocera species, while B. papayae and B. carambolae might possibly be separated from one another, even if immature life stages or adult body parts are used. Copyright © 2009 Society of Chemical Industry  相似文献