New tyrosinase inhibitory sesquiterpenes from Chloranthus henryi

Chemical investigation of the leaves and stems of Chloranthus henryi resulted in the isolation and characterization of two new eudesmane-type sesquiterpenes, and two new germacrane-type sesquiterpenes, together with two known compounds. The inhibitory activities against tyrosinase of all isolates were also evaluated.     

Globin-coupled sensors and protoglobins share a common signaling mechanism

The globin-coupled sensors (GCSs) and protoglobins (Pgbs) form one lineage of the globin superfamily. The GCSs are multidomain sensory proteins involved in aerotaxis or gene regulation, while the Pgbs are single-domain globins of yet unknown function. We postulate that the GCSs and Pgbs share a common signaling mechanism to modulate diverse physiological functions. To elucidate the signaling properties of individual globin domains, we constructed and expressed chimeric receptors in Escherichia coli. We demonstrate that all the chimeric receptors reversibly bind oxygen in vitro and trigger aerotactic responses in vivo. Thus, oxygen binding to the globin domains of diverse GCSs and Pgbs form a common signaling state that can trigger aerotactic responses.     

Differential regulation of human ALAS1 mRNA and protein levels by heme and cobalt protoporphyrin

5-Aminolevulinic acid synthase 1 (ALAS1) is the first and rate-controlling enzyme of heme biosynthesis. This study was to determine the effects of heme and selected nonheme metalloporphyrins on human ALAS1 gene expression in hepatocytes. We found that, upon heme and cobalt protoporphyrin (CoPP) treatments, ALAS1 mRNA levels were down-regulated significantly by ca. 50% or more. Measurement of mRNA in the presence of actinomycin D showed that these down-regulations were due to the decreases in mRNA half-lives. Furthermore, the levels of mitochondrial mature ALAS1 protein were down-regulated by 60-70%, but those of the cytosolic precursor protein were up-regulated by 2-5-fold. Measurement of protein in the presence of cycloheximide (CHX) suggests that elevation of the precursor form is due to the increase in protein half-lives. These results provide novel insights into the mechanisms of heme repressional effects on ALAS1 and provide a rationale for further investigation of CoPP as a therapeutic agent for acute porphyric syndromes.     

Wildlife trade,consumption and conservation awareness in southwest China

Commercial trade in wildlife is the major cause of species endangerment and a main threat to animal welfare in China and its neighboring countries. Driven by consumptive use for food and traditional medicine, the large volume of both legal and illegal trade in wildlife has caused great destruction to ecosystems and pushed many species to the brink of extinction. Data gathered from trading hubs at ports, boundary markets, city markets and stores, indicates the large amount of wildlife traded in the region of Guangxi, Yunnan and Qinghai provinces, a direct result of the numerous wildlife markets available. In a survey distributed in various trading places, while about half of the respondents agreed that wildlife should be protected, 60% of them had consumed wildlife at some point in the last 2 years. The results also indicated that law and regulation on wildlife trade control is insufficient. Wildlife trade controls are very limited because of bias on the utilization of wildlife as a natural resource to be exploited by the government agencies. The survey also shows that the current situation of wildlife consumption in key cities in China is serious, especially the consumption for food. The main consumption groups in China are male and young people with high education levels and good incomes. The key in public awareness publicity and education is to give them more information on the negative impacts of wildlife consumption and knowledge of protection.     

Electrochemical behaviors of amino acids at multiwall carbon nanotubes and Cu2O modified carbon paste electrode

A carbon paste electrode modified with multiwall carbon nanotubes and copper(I) oxide (MWCNT-Cu₂O CPME) was fabricated, and the electrochemical behaviors of 19 kinds of natural amino acids at this modified electrode were studied. The experimental results showed that the various kinds of amino acids without any derivatization displayed obvious oxidation current responses at the modified electrode. It was also found that the current response values of amino acids were dependent mainly on pH values of buffer solutions. The phenomenon could be explained by the fact that the amino acids suffered complexation or electrocatalytic oxidation processes under different pH values. Six kinds of amino acids (arginine, tryptophan, histidine, threonine, serine, and tyrosine), which performed high-oxidation current responses in alkaline buffers, were selected to be detected simultaneously by capillary zone electrophoresis coupled with amperometric detection (CZE-AD). These amino acids could be perfectly separated within 20 min, and their detection limits were as low as 10⁻⁷ or 10⁻⁸ mol L⁻¹ magnitude (signal/noise ratio = 3). The above results demonstrated that MWCNT-Cu₂O CPME could be successfully employed as an electrochemical sensor for amino acids with some advantages of convenient preparation, high sensitivity, and good repeatability.     

Ammonia removal from prawn aquaculture water using immobilized nitrifying bacteria

Intensive prawn aquaculture in tropical regions is associated with high concentrations of total ammoniacal nitrogen (TAN) as a result of high rates of prawn excretion and feed loading. Excessive TAN can adversely effect productivity and result in adverse impacts on coastal waters. Cultures of indigenous nitrifying bacteria were enriched from intensive prawn aquaculture pond water using continuous and batch enrichment techniques. Cultures were capable of TAN removal over a wide range of initial TAN concentrations - up to 200 mg/l. Cultures were immobilized onto porous clay pellets to enhance cell density and applied to culture medium and TAN-augmented pond water under aerobic conditions to determine TAN removal proficiency. Immobilized cultures were able to achieve a high TAN removal proficiency in pond water--even at a low density of 0.1 pellet per liter. A concentration of less than 0.5 mg TAN/l could be maintained under a fed-batch condition of 3.2 mg TAN/l per day, after an initial 2-day lag phase. A simplified and effective culture enrichment process was developed for culture immobilization onto pellets using TAN-augmented pond water. Overall, pellet immobilization of indigenous nitrifying bacteria represents a potentially effective TAN control system for prawn aquaculture in low-cost, but intensive tropical prawn farms.     

T型钙通道α1G亚单位在细胞增殖中的功能研究

Increases of functional T-type calcium channel (T-channel) expression have been associated with cellular proliferation although evidence for this remains controversial. In the present study, we have used a variety of cellular, molecular and electrophysiological techniques to test the hypothesis that T-type channels play a causal role in the signaling pathway leading to proliferation. The results showed that stable over-expression of alpha1G T-channel subunit in HEK-293 cells conferred a significant growth advantage. Thus, cell population doubling time was reduced to 13.7 +/- 0.3 h in alpha1G transfectants, compared to control cultures (22.1 +/- 1.1 h) and flow cytometry analysis showed that this was due to a reduction in the number of alpha1G transfectants residing in the G0/G1 phases of the cell cycle compared to controls. The selective T-type calcium channel blocker, mibefradil, induced a dose-dependent inhibition of proliferation in alpha1G tansfectants. Furthermore, the Western blotting results proved that the level of protein expression of CDK2, cyclin A and cyclin E was high in alpha1G transfectants compared to control cultures. Our results demonstrate that the T-type calcium channel provides a significant growth advantage to HEK-293 cells that might occur via effects on the G1/S cell cycle mechanism.     

油菜花丝枯萎机理的探讨

油菜（Brassica napus L.)花丝的输水系统由螺纹以及少量的环纹导管和管胞组成,它们随花丝的伸长而被拉长直至拉断。统计结果显示, 花开放后,大量的导管和管胞被拉断。输水组织的断裂终止了连续水柱的形成,使水分运输的重要动力－蒸腾拉力和内聚力不能发挥作用,引起了花丝组织的供水足,在蒸腾失水不断加剧的外部因素的相互作用下,最终导致了花丝的枯萎。     

Integration of the feline radiation hybrid and linkage maps

The recent development of genome mapping resources for the domestic cat provides a unique opportunity to study comparative medicine in this companion animal which can inform and benefit both veterinary and human biomedical concerns. We describe here the integration and order comparison of the feline radiation hybrid (RH) map with the feline interspecies backcross (ISB) genetic linkage map, constructed by a backcross of F₁ hybrids between domestic cat (Felis catus) and the Asian leopard cat (Prionailurus bengalensis). Of 253 microsatellite loci mapped in the ISB, 176 equivalently spaced markers were ordered among a framework of 424 Type I coding markers in the RH map. The integration of the RH and ISB maps resolves the orientation of multiple linkage groups and singleton loci from the ISB genetic map. This integrated map provides the foundation for gene mapping assessments in the domestic cat and in related species of the Felidae family. Received: 10 July 2000 / Accepted: 01 February 2001     

Identification of an 85-kb DNA fragment containing pms1, a locus for photoperiod-sensitive genic male sterility in rice

Photoperiod-sensitive genic male-sterile rice has a number of desirable characteristics for hybrid rice production. Previous studies identified pms1, located on chromosome 7, as a major locus for photoperiod-sensitive genic male sterility. The objective of this study was to localize the pms1 locus to a specific DNA fragment by genetic and physical mapping. Using 240 highly sterile individuals and a random sample of 599 individuals from an F2 population of over 5000 individuals from a cross between Minghui 63 and 32001S, we localized the pms1 locus by molecular marker analysis to a genetic interval of about 4 cM, 0.25 cM from RG477 on one side and 3.8 cM from R1807 on the other side. A contig map composed of seven BAC clones spanning approximate 500 kb in length was constructed for the pms1 region by screening a BAC library of Minghui 63 DNA using RFLP markers and chromosomal walking. Analysis of recombination events in the pms1 region among the highly sterile individuals reduced the length of the contig map to three BAC clones. Sequencing of one BAC clone, 2109, identified two SSR markers located 85 kb apart in the clone that flanked the pms1 locus on both sides, as indicated by the distribution of recombination events. We thus concluded that the pms1 locus was located on the fragment bounded by the two SSR markers.