氯霉素降解菌Pseudoxanthomonas mexicana CC18的筛选、鉴定和降解特性

为挖掘降解氯霉素的微生物菌种资源,从处理氯霉素废水的生物接触氧化反应器内活性污泥中分离筛选得到1株氯霉素降解菌CC18,通过形态观察、生理生化特征、16S rRNA基因序列分析,鉴定菌株CC18归属于墨西哥假黄单胞菌(Pseudoxanthomonas mexicana)。菌株CC18降解氯霉素的最佳条件:接种量4%、pH值为7、培养温度28℃,24 h后其对20 mg/L氯霉素的降解率为22.9%。响应面试验结果表明,当接种量为3.6%,pH值为7.6,温度为30℃时,24 h后菌株CC18对20 mg/L氯霉素的降解率为30.6%。研究发现,墨西哥假黄单胞菌具有降解氯霉素的能力,不仅丰富了氯霉素降解菌库,也为环境中氯霉素污染的微生物强化处理提供了理论基础。

玉米草(Zea Mexicana)与海藻寡糖联合修复石油烃污染土壤的研究

采用玉米草及海藻寡糖联合修复技术研究了石油污染土壤的修复效果,对修复过程中酶活性变化进行了测定,并采用变性梯度凝胶电泳(DGGE)技术测定了土壤中微生物群落的变化。结果表明,种植玉米草可以有效提高土壤中石油烃的降解,与对照相比石油烃降解率增加了11%;加入不同浓度海藻寡糖进一步增加了石油烃的降解效果,降解率最高达到28.6%。种植植物及加入海藻寡糖可以有效提高多酚氧化酶、脱氢酶及尿酶的活性。PCR-DGGE结果表明植物种植及海藻寡糖的加入增加了土壤中微生物数量,其微生物群落结构与未种植植物及修复前土壤相比发生了较大的变化。

大刍草(Zea mexicana schard)×自交系K169选系的核型和SSR分析

本研究以玉米自交系K169及其与大刍草(Zea mexicana schard)远缘杂交而成的5个选系为研究材料,对它们进行核型和SSR分析,以期从细胞学和分子水平的角度为玉米远缘杂交育种提供理论依据。结果表明,5个远缘选系和轮回亲本K169体细胞染色体数目均为2n=20,但在核型结构上却存在较大差异,其中自交系K169和远缘选系1191在第6染色体的短臂上有随体,1183和1189在第8染色体的短臂上有随体,1193和1195未发现带随体的染色体;选系1183、1193和1195的染色体长度比(最长/最短)与K169之间存在较大差异;选系1183和1195的核型类型与K169不一致。96对SSR引物在5个选系和轮回亲本K169中共检测出27个多态性位点,位点多态信息量(PIC)的平均值为0.724;基因型多样性(H′)的平均值为1.400,它们之间的遗传相似系数平均值为0.5791。综合分析表明,这些选系与其轮回亲本K169之间存在真实的遗传差异,是一批新的玉米种质资源。

Isolation and identification of antibacterial components in seed extracts of Argemone mexicana L.(Papaveraceae)

Objective:The column chromatographic fractions of chloroform(CH1,CH2,CH3) seed extracts of Argemone mexicana(A.mexicana) were screened for antibacterial activity and phytochemical analysis.Methods:CH3 fraction was isolated and identified by column chromatography,thin layer chromatography,spectral data analysis and phytochemical screening were used for analysis. Results:CH3 fraction was significantly active at 4 to 64 mg/mL against Staphylococcus aureus, Escherichia coli,Klebsiella pneumoniae and Pseudomonas aeruginosa with minimum inhibitory concentration of 1.5625 to 3.125 mg/mL.The active fraction(CH3) revealed presence of alkaloid with retention factor value of 0.44.The active antibacterial agent in the most potent fraction (CH3) was isolated and identified as N-demethyloxysanguinarine by thin layer chromatography (TLC) and phytochemical screening.The CH1 and CH2 fractions did not show inhibitory activity. Conclusions:The results support the ethnomedicinal use of seeds of A.mexicana for treatment of bacterial diseases.

Effects of Different Nitrogen Application Strategies on Yield and Forage Nutritive Quality of Zea mexicana

A pool experiment was carried out to study the effects of different nitrogen applicationstrategies (rates and stages of nitrogen application) on yield and forage nutritivequality of Zea mexicana cultivated in summer, 2002. In the whole growing stage, its stemwas clipped three times at the height of 25cm when it was 110cm high (H1, H2 and H3 standfor the first, second and third harvest stage, respectively). Six indexes includingcrude protein (CP), ether extract (EE), nitrogen free extract (NFE), acid detergentfiber (ADF), crude ash (CA), and general energy (GE) were employed to evaluate the foragenutritive value. The results showed that the content of CP and EE increased but thecontent of CA and ADF decreased under the two nitrogen rates (High-rate N, 600kgha-1;Mid-rate N, 300kgha-1). The fresh and dry harvest biomass of the whole plants on H1 andthose of the leaves on H2 were also improved. But the stalks on H2 and the whole plantson H3 were affected mainly by dressing nitrogen fertilizer. The yield of CP and EE, CA,NFE, and GE was mainly affected by nitrogen rates. The ADF yield increased was due to theincrement of the fresh and dry harvest biomass. Nitrogen applied as base fertilizer forsummer Zea mexicana can be harvested a higher biomass and improve the forage nutritivequality.

Effect of Euchsaena mexicana Schrad Diets on Nutrient Digestibility and Nitrogen Metabolism for Wulong Goose

One trial was conducted to study nutrition digestibility of Euchsaena mexicana Schrad (EMC) diets for Wulong Goose. Thirty-two geese of 9 months old were selected and divided into four groups randomly, with eight geese in each group. Four groups were fed with the isocaloric and isonitrogenous diets of different EMC contents (12, 19, 25 and 31%), respectively. The results showed that, as dietary EMC increased, dry matter (DM) digestibility was decreased significantly, meanwhile the digestibility of crude fiber (CF), neutral detergent fiber (NDF) and acid detergent fiber (ADF) increased significantly (P<0.05). The ratio of apparent essential amino acid (EAA) digestibility (except Leu) among the four groups had significant difference (P<0.01). the content of NH3-N in feces dropped (P>0.05). There were no significant differences in net protein utilization (NPU), N apparent digestibility, N deposition and Ca apparent digestibility in different groups (P> 0.05). The apparent digestibility of P in different groups elevated, while there was significant difference between group D and A (P<0.01), and there was significant difference between group D and B (P<0.05).

不同选育方法对“玉米×大刍草”远缘杂交(Z.mays×Z.mexicana)后代育种效果的研究

用玉米综合种“G—1”与一墨西哥一年生大刍草进行种间杂交,后代采用连续自交、1—3代回交结合自交的选育方法,进行选系。对不同选育方法的育种效果作了分析。结果表明,无论采用连续自交或不同次数回交后自交选系,都能获得较好的选系。但回交比自交具有较快的稳定速度。在回交选育方法中,不同回交次数从总体而言无明显差异,但不同回交亲本对后代选系的影响是显著的;而且,不同回交亲本显示具有不尽相同的适宜回交次数。

Depressant effects of Agastache mexicana methanol extract and one of major metabolites tilianin

Objective:To determine the depressant-like effects and the possible mechanism of action of tilianin isolated from active methanol extract of Agastache mexicana(A.mexicana).Also,to establish the pharmacophoric requirements of tilianin,as a possible ligand of GABA_A/BZD receptor,by the alignment of diazepam.CGS-9896 and diindole,using a previously described pharmacophoric model.Methods:Tilianin(30 to 300 mg/kg.ip.and 300 mg/kg,pa.) and methanol crude extract(10 to 300 mg/kg,ip.and 300 mg/kg po.) from A.mexicana were evaluated for potential sedative and anxiolytic-like response drugs by using open-field,hole-board,cylinder of exploration,plus-maze and sodium pentobarbital-induced hypnosis mice methods.Results:Methanol extract and tilianin showed anxiolytic-like activity from a dosage of 30 mg/kg,ip.or 300 mg/kg,po.and were less potent than diazepam 0.1 mg/kg.a reference anxiolytic drug used.Moreover,depressant activity of both potentiates sodium pentobarbital(SP)-induced sleeping time.The anxiolytic-like effect of 30 mg/kg ip.observed for the extract and tilianin,by using the plus-maze model,was partially prevented in the presence of flumazenil(a GABA_A/BZD antagonist,5 mg/kg ip.) but not in the presence of WAY100635(a selective 5-HT_(1A) receptor antagonist,0.32 mg/kg.ip.).Pharmacophoric modeling alignments of three agonist of GABA_A/BZD allow identify seven chemical features.Tilianin contains six of the seven features previously determined.Conclusions:Results indicate that tilianin is one of the bioactive metabolites in the anxiolytic-like activity of 4.mexicana.reinforcing its central nervous system uses,where GABA_A/BZD,but not 5-HT_(1A),receptors are partially involved.

Argemone mexicana extract alleviates gastrointestinal disorders by stimulating muscarinic receptors and blocking voltage-gated L-type calcium channels

Objective:To investigate the pharmacological potential of Argemone mexicana in treating constipation and emesis by using in vitro and in vivo models.Methods:The spasmogenic and spasmolytic effects were evaluated on isolated rabbit jejunum fragments loaded in a tissue organ bath.The response was recorded with an isotonic transducer attached with Power Lab Data Acquisition System.The laxative and antiemetic activities were assessed in BALB-c mice and poultry chicks challenged with carbamylcholine and copper sulphate stimulated emesis,respectively.Results:The total phenolic and total flavonoids contents of the extract were(267.75±5.77)mg GAE/g and(73.86±6.01)mg QE/g,respectively.Argemone mexicana extract exerted spasmogenic effect on isolated rabbit jejunum segments with an EC_(50)value of 0.016 mg/m L,which was blocked by atropine(0.3μM).Argemone mexicana extract exerted spasmolytic effect in atropine treated jejunum fragments with an EC_(50)value of 2.185 mg/mL.Furthermore,Argemone mexicana extract relaxed potassium(80 mM)-induced contractions(EC_(50):9.07 mg/mL),similar to a standard drug verapamil.The calcium channel blocker activity was confirmed by a rightward shift of concentration-response curve of calcium in the presence of Argemone mexicana extract(1-5 mg/mL)and verapamil(0.1-1μM).In addition,the extract increased the distance travelled by a charcoal in the gastrointestinal tract and exhibited antiemetic effect on copper sulphate induced emesis in chicks.Conclusions:Argemone mexicana shows cholinergic agonist and calcium channel blocker activities,as well as antiemetic effect.It may be used as a potential agent for treating gastrointestinal disorders.

Distribution of Malpighia mexicana in Mexico and its implications for Barranca del Río Santiago

Wild plants represent relatively unexplored resource of high economic potential,especially as an alternative to developing new crops and,even more relevant,for improving existing crops and contributing to nutrition and health.The wild species M alpighia mexicana(manzanita)has a wide tradition of food,medicinal and ornamental use in Mexico.It is part of the American-origin group of tropical shrubs that produce edible red fruits,such as A cerola,which is considered the most important natural source of vitamin C in the world.Given the role played by M.mexicana in Mexico,and particularly in Barranca del Río Santiago(Santiago River Canyon),we modelled its potential distribution in both geographical areas.We used species'records from databases,local herbaria and records collected by the authors as well as climatic variables representing long term average,variability and extreme conditions of temperature and precipitation.To fit the models we used the modelling algorithm Maxent and selected an adequate configuration by testing a range of model complexity settings.The results indicate a clear species preference for warm-dry tropical forest,most extensively in the Balsas river depression and the central valleys of Oaxaca.The probability of the species presence in the western region was also high,although the probability was also high for smaller surface areas,such as the region of Santiago river canyons,which are covered by warm-dry tropical forests.

Atypical Cutaneous Leishmaniasis by Leishmania Mexicana: A Case Report with Dermoscopic, Histopathological and Molecular Study

Cutaneous leishmaniasis is a neglected tropical skin endemic disease, with worldwide distribution. By 2020 in the Americas, Mexico was in 12th place with 11 states reporting new cases. Molecular biology with different targets for diagnosis and species identification has been used for decades, also dermoscopy, a non-invasive diagnostic tool has shown its usefulness. We present the first case of cutaneous leishmaniasis in non-endemic place (Guerrero, Mexico) identifying Leishmania mexicana with molecular biology, and treated with itraconazole.

Preliminary Phenotypic and SNP-Based Molecular Characterization of Maize (<i>Zea mays</i>L.)-Mexicana (<i>Zea mays</i>SSP. <i>Mexicana</i>) Introgression Lines under Inbred Background of 48-2

Wild relatives possess potential genetic diversity for maize (Zea mays L.) improvement. Characterization of maize-mexicana introgression lines (ILs) is of great value to diversify the genetic base and improve the maize germplasm. Four maize-mexicana IL generations, i.e. BC1, BC2, BC3, and RIL, were constructed under the elite inbred background of 48-2, elite inbred line that is widely used in maize breeding in Southwestern China, and were phenotyped in different years and genotyped with 56110 SNPs. The results indicated that 48-2 had higher phenotypic performances than all the characterized ILs on most of the agronomic traits. Compared with other ILs, BC2 individuals exhibited more similar performance to 48-2 on most traits and possessed the highest kernel ratio (66.5%). Population structure and principal component analysis indicated that BC3 individuals gathered closer to 48-2 and exhibited the lowest mexicana-introgression frequency (0.50%), while BC2 (29.06%) and RIL (18.52%) showed higher introgression frequency. The high level of genetic diversity observed in the maize-mexicana ILs demonstrated that Z. mays ssp. mexicana can serve as a potential source for the enrichment of maize germplasm.

菲降解菌的分离鉴定及其在污染土壤生物修复中的应用

采用室内培养方法,从吴江市郊长期被多环芳烃污染的土壤中富集到以菲为唯一碳源和能源的菲降解复合微生物菌群,复合菌群在7d内对无机盐液体中菲(含量100mg·L-1)的降解率达到99%。从复合菌群中分离纯化获得两株菲高效降解菌B1和L2,经过菌体形态特征、生理生化特征和16SrDNA序列分析,鉴定菌株B1为百日咳博行特氏菌(Bordetella petrii),菌株L2为墨西哥假黄单胞菌(Pseudoxanthomonas mexicana)。这两株菌在菲含量为100mg·L-1的无机盐培养液中,7d内对菲(含量100mg·L-1)的降解率大约为80%,9d内的降解率可达到99%。将复合菌群和菲污染土壤混合,在光照培养箱中进行培养修复。结果表明,修复88d后,接种复合菌群的低污染浓度(8.22mg·kg-1)处理和高污染浓度(39.65mg·kg-1)处理的菲去除率分别达到95.74%和98.06%。

不同海拔高度黄梅衣属地衣松萝酸含量的测定

采集河北省蔚县小五台山和平山县驼梁两地不同海拔高度黄梅衣属淡腹黄梅(Xanthoparmellia mexicana),并采用HPLC分析样品中的松萝酸含量,同时分析了不同检测波长对检测结果的差异。结果表明,各海拔高度样品中的松萝酸含量差异较大,但海拔高度与样品中松萝酸含量变化无相关性。该结果可为研究海拔高度对黄梅衣属地衣松萝酸含量的影响提供参考。

盖裂木属两种植物花粉形态观察

利用光学显微镜、扫描电镜和透射电镜观察了盖裂木属两种Talauma gloriensis和T.mexicana的花粉形态。花粉粒具远极单萌发沟,椭圆球形,外壁较光滑或略粗糙且具小穴状雕纹。在透射电镜下,花粉外壁可分为覆盖层、柱状层和基层,外壁-2明显,且厚度不均匀。在远极面萌发沟区域,外壁逐渐减薄,最后覆盖层和柱状层消失,仅残留基层。T.gloriensis的柱状层内部空间较小,多由颗粒组成,而T.mexicana柱状层中有发育较好的小柱,与覆盖层和基层连接。

氮肥用量、时期对墨西哥玉米产量及饲用营养品质的影响

采用池栽方法研究了氮肥用量、时期对一年生夏播墨西哥玉米(Zea mexicana)产量和饲用营养品质的影响,并运用概略养分分析法来评价其饲用营养价值。结果表明,夏播墨西哥玉米生长季内刈割 3 茬,叶片对产量与品质的形成贡献最大;在中氮(300 kg·ha-1)和高氮(600 kg·ha-1)2 种水平下,氮肥用量对第 1 茬草产量的影响大,底肥肥效仅持续作用到第 2 茬的叶片;第 2 茬的茎鞘及第 3 茬的整个收获部分都表现追肥效应。增施氮肥提高了粗蛋白(CP)、粗脂肪(EE)的含量,降低了粗灰分(CA)、酸性洗涤纤维(ADF)的含量,氮肥水平对粗蛋白、粗脂肪、粗灰分、无氮浸出物(NFE)及总能量(GE)的产量影响程度大于施肥时期,随着刈割茬次的增加,底肥肥效降低而追肥肥效增加;酸性洗涤纤维的产量随氮肥用量的增加而增加是由于干物质产量提高的幅度大于含量降低的幅度。在较高氮肥水平下,底肥一次施入有利于提高产量及其饲用营养品质。

施氮对墨西哥玉米植株硝态氮累积及产量的影响

采用微区试验,研究了2个施氮水平(中氮,300 kg/hm2;高氮,600 kg/hm2)下2种施肥方式(一次基施和平均3次分施)对墨西哥玉米(Euchlaena mexicana)植株硝态氮(NO3--N)累积及产量的影响。结果表明,墨西哥玉米叶片中NO3--N含量以新生叶较高,全展叶较低,老叶居中;茎鞘和根系的NO3--N含量在不同收获期表现为第一收获期低于叶片,第二期仅比新生叶低,第三期则高于叶片。随着收获次数增加,NO3--N含量在叶片中呈降低趋势,在茎鞘和根系中先降后升。高氮水平和分次施肥是造成同一类型叶片NO3--N累积的主要原因;高氮分次施肥处理(N2-3)第二期收获的新生叶NO3--N含量最高,为92.66μg/g,这一数值尚未达动物摄食的潜在致毒剂量。氮素用量增加,其生产效率降低,但高氮(600 kg/hm2)一次性基施处理的干物质产量和粗蛋白质产量均显著高于其他处理。综上所述,较高的氮肥用量一次性基施能够实现墨西哥玉米的高产且不会影响其产品安全性。

留茬高度与刈割时期对墨西哥玉米再生性能的影响

采用大田小区栽培试验,研究了留茬高度和刈割时期对墨西哥玉米(Zeamexicana)再生性能(包括再生草产量和饲用营养品质)的影响。刈割时期的确定以植株高度为准,运用概略养分分析法评价饲用品质并引入再生系数(RGC)的概念判定其再生性能。结果表明,株高95cm时刈割,留茬30cm的再生草产量和总能量最高,分别为11.60kg·m-2(鲜草重)和278kJ·m-2,显著高于留茬20cm(CK)与10cm处理;留茬30cm再生草的粗蛋白和无氮浸出物含量较高,粗灰分和酸性洗涤纤维含量较低。留茬20cm,不同时期刈割,株高130cm与95cm(CK)的再生产量、总能量差异不显著,但明显高于株高60cm处理;但再生草饲用品质以株高60cm时刈割最佳。比较发现,RGC接近2.5时墨西哥玉米再生性能最好,对应的刈割方式(留茬30cm,株高95cm)可实现其优质高产。

添加墨西哥玉米干草粉对五龙鹅日粮消化利用及氮代谢的影响

选9月龄健康五龙鹅32只,随机分为4组,每组8只。每组的日粮中添加不同比例的墨西哥玉米(EMC)干草粉(分别占日粮配方的12%、19%、25%、31%),调整各组日粮等能等蛋白。采用全收粪法进行消化代谢试验,检测饲料和粪便中的多种营养成分,确定消化率。结果表明,在代谢能(ME)与粗蛋白(CP)摄入量一致的情况下,随着EMC干草粉添加水平(在12.0%～31.0%范围内)的升高,干物质(DM)消化率逐渐降低;粗纤维(CF)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)消化率升高;必需氨基酸(EAA)(除亮氨酸外)C、D组与A、B组相比消化率有显著性下降(P<0.05);粪中NH3-N浓度逐渐降低;净蛋白利用率(NPU) 、氮表观沉积率及沉积量组间差异不显著(P>0.05);钙表观消化率组间差异不显著(P>0.05);磷的表观消化率升高,D组与A组差异极显著(P<0.01),与B组差异显著(P<0.05)。