Assessment of T lymphocyte responses induced by parasite antigens

Recently developed procedures for the isolation and continuous growth in vitro of T lymphocytes can be used to extend our knowledge of cellular immune responses elicited by parasitic infections. These procedures are adaptable to the study of both the inductive and effector phases of T cell responses. The inductive phase of T cell responses is measured by assessing the level of blastogenesis induced in antigen-primed lymphocyte populations by parasite antigens. The development of limiting dilution analyses and procedures for the repeated in vitro restimulation of such cells have allowed for the quantitation of blastogenic responses, and for the isolation of antigen-reactive T cells. The effector phase of T cell responses is assessed by assays that detect either, cytolytic activity of the antigen-responsive cells, the secretion of lymphokines by the responding cells, or specific or non-specific T cell mediated immunosuppression.     

CpG-oligodeoxynucleotides enhance porcine immunity to Toxoplasma gondii

Protection against a challenge infection with Toxoplasma gondii VEG strain oocysts was examined in pigs after vaccination with T. gondii RH strain tachyzoites with or without a porcine specific synthetic oligodeoxynucleotides (ODN) containing immunostimulatory CpG motifs. Six groups of pigs were immunized with incomplete Freund's adjuvant (IFA) and either vehicle, tachyzoites alone or in combination with three different doses of CpG ODN or with CpG ODN alone. Protection from challenge was significantly (P < 0.05) improved in pigs vaccinated using CpG ODN as an adjuvant with tachyzoites compared to all other groups. The CpG ODN tachyzoite-immunized pigs also had higher serum parasite specific IgG antibody, no clinical signs of disease, and 52% had no demonstrable tissue cysts after the challenge infection. These data indicate that CpG ODN is a potential safe and effective adjuvant for the T. gondii RH strain vaccine in pigs.     

澧阳平原末次冰期-早全新世气候环境演变研究

通过对澧阳平原野外考察、典型剖面YC自然沉积剖面的系统采样、室内地球化学元素Li、Rb、Sr、Ba和Li/Ba、Rb/Sr比值的分析,以及沉积物年代样品的OSL和AMS14C年代测定,探讨了长江中游地区澧阳平原末次冰期-早全新世的气候环境变化过程。结果表明,MIS3阶段晚期(31.80~23.80 ka BP)暖湿期记录明显,对应的沉积物含大量黑色铁锰膜和铁锰结核,地球化学元素Li含量、Rb含量、Rb/Sr比值、Li/Ba比值出现峰值,而Sr含量、Ba含量出现低谷,表明此时期冬季风减弱,夏季风增强,降水量增大,温度上升,风化作用显著增强。澧阳平原YC剖面很好的记录了56.00~6.96 ka BP的气候环境演变过程,大致经历了冷干期(56.00~31.80 ka BP)、相对暖湿期(31.80~23.80 ka BP)、冷湿期(23.80~10.60 ka BP)、暖湿期(10.60~6.96 ka BP)4个气候变化阶段。     

Carcinogenicity of acrylamide: a computational study

This paper reports a series of ab initio, density functional theory (DFT), and semiempirical molecular orbital (MO) calculations concerning the reaction between the ultimate carcinogen of acrylamide and guanine. Acrylamide--a product of the Maillard reaction--is present in a variety of fried and oven-cooked food. After intake, it is epoxidized by cytochrome P450 2E1 to yield the ultimate carcinogen--glycidamide. Effects of solvation were considered using the Langevin dipoles (LD) model of Florian and Warshel and the solvent reaction field (SCRF) model of Tomasi and co-workers. In silico activation free energies are in very good agreement with the experimental value of 22.8 kcal/mol. This agreement presents strong evidence in favor of the validity of the proposed S N2 reaction mechanism and points to the applicability of quantum chemical methods to studies of reactions associated with carcinogenesis. In addition, insignificant stereoselectivity of the studied reaction was predicted. Finally, the competing reaction of glycidamide with adenine was simulated, and the experimentally observed regioselectivity was successfully reproduced.     

Mechanizsed microsite preparation and direct seeding of Pinus sylvestris in boreal forests — a way to create desired spacing at low cost

The main objective of this study was to examine the cost, flexibility, and appropriate scale of mechanized microsite preparation (MP), in combination with mechanical direct seeding of Pinus sylvestris L. with orchard seed. This technique was tested at four boreal forest sites in Northern Sweden. Orchard and stand seeds were sown with and without MP. The use of orchard seed increased seedling establishment by 41% and the use of MP increased seedling establishment by 47%, respectively, after two years. The best substrates for sowing when using MP were OA_h-, E- and BC-horizon, in ranked order. The use of orchard seed compared to stand seed increased mean seedling height by 25% after four years. These trials suggest that to obtain a density of 5,000 stems ha^-1 four years after seeding, 61,000 viable stand seeds or 41,000 orchard seeds ha^-1 should be sown if MP is not used. If MP is used, seeding rate could be reduced by about 32%. By using MP, and by further improving scarification technique so that all scarified area is thin OA_h-horizon, we predict that only 32,000 stand seeds or 22,000 orchard seeds ha^-1, i.e., half the dosage, should be needed. Under these optimal conditions, it would be necessary to sow about six and four germinable stand and orchard seeds, respectively, to ensure one seedling after four years. Furthermore, regeneration cost would be less than a third that of planting.     

长沙冷季型草坪草引种试验

为了给长沙地区草坪建植和草种选用提供栽培依据,3年来对高羊茅、草地早熟禾、粗茎早熟禾、翦股颖、多年生黑麦草5个冷季型草坪草的42个品种进行了引种栽培试验,筛选出绿色期长、抗逆性好、适合长沙气候的冷季型草坪草品种有高山、浪潮、优异、华盛顿、公园、兰肯、猎狗5号、交战2号、L5、侵略者、百都11个。     

Dereplication and Chemotaxonomical Studies of Marine Algae of the Ochrophyta and Rhodophyta Phyla

Dereplication and chemotaxonomic studies of six marine algae of the Ochrophyta and one of the Rhodophyta phyla resulted in the detection of 22 separate compounds. All 16 secondary metabolites, including four new compounds (16–19), could be rapidly dereplicated using HPLC-NMR and HPLC-MS methodologies in conjunction with the MarinLit database. This study highlights the advantages of using NMR data (acquired via HPLC-NMR) for database searching and for the overall dereplication of natural products.     

Production and isolation of azaspiracid-1 and -2 from Azadinium spinosum culture in pilot scale photobioreactors

Azaspiracid (AZA) poisoning has been reported following consumption of contaminated shellfish, and is of human health concern. Hence, it is important to have sustainable amounts of the causative toxins available for toxicological studies and for instrument calibration in monitoring programs, without having to rely on natural toxin events. Continuous pilot scale culturing was carried out to evaluate the feasibility of AZA production using Azadinium spinosum cultures. Algae were harvested using tangential flow filtration or continuous centrifugation. AZAs were extracted using solid phase extraction (SPE) procedures, and subsequently purified. When coupling two stirred photobioreactors in series, cell concentrations reached 190,000 and 210,000 cell · mL(-1) at steady state in bioreactors 1 and 2, respectively. The AZA cell quota decreased as the dilution rate increased from 0.15 to 0.3 day(-1), with optimum toxin production at 0.25 day(-1). After optimization, SPE procedures allowed for the recovery of 79 ± 9% of AZAs. The preparative isolation procedure previously developed for shellfish was optimized for algal extracts, such that only four steps were necessary to obtain purified AZA1 and -2. A purification efficiency of more than 70% was achieved, and isolation from 1200 L of culture yielded 9.3 mg of AZA1 and 2.2 mg of AZA2 of >95% purity. This work demonstrated the feasibility of sustainably producing AZA1 and -2 from A. spinosum cultures.