两种地衣共生藻对铜和锌的耐受性及吸附特性研究

重金属污染生物修复中,藻类对重金属的吸附潜力引起诸多研究者的关注。为了探讨从地衣体分离培养的地衣共生藻对重金属Cu~(2+)、Zn~(2+)吸附特性及其耐受性的差异,以2种地衣共生藻为研究材料,采用Evan’s blue染色法、BCO和双硫腙分光光度法测定地衣共生藻细胞活率,培养液及藻体内的Cu~(2+)、Zn~(2+)含量。结果显示:不同浓度Cu~(2+)、Zn~(2+)胁迫下,2种地衣共生藻的细胞活力及重金属吸附特性有所差异,对Cu~(2+)胁迫的耐受性及吸附性为:P.EB;Zn~(2+)胁迫下,培养至9d时耐受为:P.E B,随着培养时间的延长P.E的细胞活力急剧下降并低于B,但吸附率还是处于P.E B;并且2种地衣共生藻对Zn~(2+)胁迫的耐性及吸附性明显高于Cu~(2+)。研究发现,来自菌藻共生的特殊生物-地卷属地衣的两种藻类比一些自由生长的藻类对铜和锌胁迫具有较高的耐受性及吸附性。     

粘盖牛肝菌不同菌株对Zn2+、Cd2+的吸附及其对油松Zn2+、Cd2+的耐受性

为了探讨同一菌根真菌不同菌株对重金属的耐受性,选用采集于内蒙古阴山山脉不同地区的粘盖牛肝菌(Suillus bovinus)的不同菌株进行研究。首先,在不同浓度Zn^2 、Cd^2 液体培养基中培养菌丝体,以了解各菌株菌丝体对重金属的耐受性及吸附能力,采用烘干法和原予吸收法分别测定菌丝体的生物量和菌丝体、培养液中Zn^2 、Cd^2 含量,结果表明：劈柴沟粘盖牛肝菌在Zn^2 、Cd^2 胁迫条件下,生物量、吸附能力约为其余各菌株的1．5～2倍。其次,为了探明油松(Pinus tabulaeformis)形成菌根后对Zn^2 、Cd^2 胁迫的耐受性及其耐受机理,采用一次性定量浇灌不同浓度Zn^2 、Cd^2 溶液的方法,测定了菌根化油松苗地上、地下生物量及Zn^2 、Cd^2 含量的分配,结果表明：菌根形成后能显著促进油松的生长及对Zn^2 、Cd^2 胁迫的耐受性,并且菌根能够帮助油松吸收基质中大量的Zn^2 、Cd^2 ,根中重金属的含量是茎叶中的2～3倍以上,非菌根苗在重金属浓度稍高(Zn^2 400mg／kg;Cd^2 40mg／kg)时就会死亡。经方差分析及多重比较证实,劈柴沟粘盖牛肝菌对Zn^2 、Cd^2 的耐受性及对油松的促生效果与其它各菌株存在显著的差异,这可能是它通过把吸收的Zn^2 、Cd^2 最大限度地输送到根中的同时,也输送到了茎叶中,使重金属在体内得到一定程度的稀释,使自身免受毒害。     

地卷属5株共生藻的分离鉴定及抗逆性分析

[目的]了解地卷属的5种地衣共生藻分离、鉴定,并对其响应干旱、重金属、盐和温度等非生物胁迫因子的抗逆特性进行研究。[方法]采用涂布法进行分离培养及其结合形态与分子学方法初步鉴定分类地位;并采用PEG模拟法和重金属检测法研究对共生藻耐受性。[结果](1)在绿皮地卷(Peltigera apthosa)、犬地卷(Peltigera canina)、平盘软地卷(Peltigera elisabethae)、地卷(Peltigera rufescens)和膜地卷(Peltigera membranacea)等5种地卷中分离培养了5株藻(编号为1、2-1、4-2、6和7号),均属于杆裂丝藻属(Stichococcus)。(2)PEG模拟法对共生藻耐干旱特性的研究结果表明,1号、2-1号、6号和7号共生藻的干旱耐受性可达到30%,其中1号共生藻、2-1号和6号共生藻的PEG耐受性达40%。共生藻对不同重金属离子的耐受性存在显著差异:对1.0 mmol/L浓度Cu~(2+)、Cd~(2+)和Fe~(2+)均有一定的耐受性藻株为1号、2-1号、6号和4-2号共生藻;对1.0 mmol/L Zn~(2+)具有耐受性的藻株为6号、7号和4-2号共生藻。其中6号藻株对Cu~(2+)和Fe~(2+)的耐受性可高达1.5 mmol/L,7号藻株也对Cu~(2+)耐受性达到1.5 mmol/L',6号藻株对不同重金属的耐受性显著高于其它藻株。5株共生藻中,4-2号和7号藻对0.3 mol/L氯化钠具有一定的耐受性,1号和6号共生藻对Na Cl的耐受性最为强,可达到0.4 mol/L。其中(6号、7号、2-1号)在35℃条件下也能生长,所有藻株均显示敏感性。[结论]对干旱、重金属、盐和温度等非生物胁迫抗逆特性最高的藻株为地卷中分离的6号藻株。研究结果证实了地卷属地衣中包含了具有较强的生存力和耐干旱、重金属和盐胁迫适应能力的藻类品种。     

转基因衣藻对重金属的抗性及对镉离子的富集

目的：研究了转基因衣藻对不同重金属离子的抗性和对Cd^2＋的富集行为。方法：将MT-like基因在莱茵衣藻细胞中的表达后通过摇瓶实验测试其对重金属离子的抗性和富集能力。结果：转基因衣藻对Pb^2＋、Zn^2＋和Cd^2＋三种重金属离子的抗性得到明显增强,其中以对Zn^2＋的抗性增强最为显著。转基因藻对Cd^2＋的富集能力经MT-like蛋白表达后较野生藻细胞有较大增加,最大达到144．48μmol／g,为野生藻的8．3倍。结论：转基因衣藻对重金属离子的抗性和对Cd^2＋的富集能力较野生衣藻有较大提高。     

Agromyces sp.CS16去除水体中重金属镉、镍、铜、锌离子的研究北大核心

【目的】本研究从深圳福田红树林表层土壤中分离出一株潜在放线菌新种Agromyces sp.CS16,研究其对水体中重金属的去除能力以及特征,并初步探究其在去除水体重金属中的实际应用,为利用微生物修复水体重金属污染提供技术支持。【方法】测定菌株CS16对Cd^(2+)、Ni^(2+)、Cu^(2+)、Zn^(2+)的去除能力;测定CS16对Cd^(2+)、Ni^(2+)、Cu^(2+)、Zn^(2+)在胞外吸附和胞内吸收的占比;通过全基因组测序分析CS16基因组中与重金属耐受相关的基因;采用海藻酸钠和聚乙烯醇将CS16包埋,并测定包埋后CS16对重金属的去除能力。【结果】放线菌Agromyces sp.CS16在Cd^(2+)浓度为10μg/mL时对其的去除量最大,为32.95 mg/g,此时对溶液中Cd^(2+)的去除率也最高,达到83.71%;菌株CS16在Ni^(2+)浓度为75μg/mL时去除量最大,为25.09 mg/g,在Ni^(2+)浓度为25μg/mL时去除率最高,为70.27%;CS16在Cu^(2+)浓度为150μg/mL时去除量最大,为30.69 mg/g,在Cu^(2+)浓度为30μg/m L时去除率最高,为80.11%;CS16在Zn^(2+)浓度为125μg/mL时去除量最大,为39.29 mg/g,在Zn^(2+)浓度为25μg/mL时去除率最高,为88.91%。菌株CS16全基因组预测总共有3744个基因,其中有37个基因推测与Cd^(2+)、Ni^(2+)、Cu^(2+)、Zn^(2+)的抗性相关。CS16主要通过将重金属吸附在细胞外表面来去除水体中的重金属,在被海藻酸钠(sodium alginate,SA)与聚乙烯醇(polyvinyl alcohol,PVA)材料包埋后,CS16对Cd^(2+)的去除能力下降,但对Ni^(2+)、Cu^(2+)、Zn^(2+)的去除能力显著提高。【结论】放线菌Agromyces sp.CS16是一株分离自红树林表层沉积物的新菌,本研究测定了CS16对Cd^(2+)、Ni^(2+)、Cu^(2+)、Zn^(2+)的去除能力,从细胞层面和基因层面初步探索了其对Cd^(2+)、Ni^(2+)、Cu^(2+)、Zn^(2+)的去除机理,并成功用海藻酸钠和聚乙烯醇将其包埋,为探究微生物去除水体重金属离子的机制和之后应用CS16修复水体重金属污染提供了理论基础。     

铜离子胁迫对两种地衣细胞结构的影响

采用光学显微镜徒手切片技术和透射电子显微镜超薄切片制备技术,以两种叶状地衣即中国树花(Ramalina sinensis)和地卷(Peltigera rufescens)为实验材料,研究了不同浓度CuSO4(0、1、2、3、4mmol/L)处理24h后地衣体细胞的存活率以及Cu2+胁迫对细胞超微结构的影响。结果显示:(1)光学显微镜下可初步确定,Cu2+浓度越大中国树花共生藻细胞存活率越小,而同样处理条件下地卷共生藻细胞的存活率则基本保持不变。(2)低浓度Cu2+(1mmol/L)对中国树花细胞结构基本无影响,细胞壁、细胞膜及细胞内的线粒体、叶绿体完整;随着Cu2+浓度增加,当处理Cu2+浓度为2mmol/L时,细胞壁无损,但细胞膜开始破坏形成小空泡,线粒体嵴变凌乱,叶绿体也出现皱缩,类囊体膨胀,基粒排列紊乱;当Cu2+处理浓度大于2mmol/L时,共生藻的细胞膜和细胞器出现不同程度的损伤;当Cu2+浓度为3mmol/L时,细胞壁变薄,细胞膜形成的空泡变大,细胞内部结构变松散,蛋白核消失,叶绿体与细胞质混在一起,基粒片层扭曲,分布混乱,线粒体变形;当Cu2+浓度达4mmol/L时,细胞结构完全受到破坏。(3)不同浓度Cu2+处理对地卷共生藻细胞结构无明显的影响,在所有处理条件下地卷共生藻细胞壁、细胞膜都完整,且大多数共生藻细胞处于分裂状态。研究认为,中国树花对Cu2+胁迫较敏感,Cu2+耐受在1~2mmol/L之间,Cu2+浓度与中国树花细胞结构的损伤程度存在着明显的剂量效应关系,Cu2+浓度越高,其属于共球藻的真核共生藻细胞受损程度越大;地卷对Cu2+胁迫具有一定的耐性,Cu2+胁迫下地卷属于蓝藻的原核共生藻细胞仍能繁殖分裂产生子代细胞。     

重金属镉和铅胁迫对海洋微藻的毒性效应研究

设置不同浓度的重金属Cd2+(0、0.2、0.4、0.6、0.8和1 mg•L-1)和Pb2+(0、0.1、0.2、0. 4、0.8和1.6 mg•L-1)胁迫处理, 检测米氏凯伦藻(Karenia mikimotoi)的生长生理情况, 分析重金属胁迫对海洋微藻生长的毒性效应, 探讨超氧化物歧化酶(SOD)和过氧化氢酶(CAT)等对重金属胁迫的缓解作用。研究结果发现, 重金属Cd2+和Pb2+对米氏凯伦藻具有较强的毒性, 随着重金属浓度的提高, 细胞生长受到毒害作用增强; 而米氏凯伦藻对重金属Cd2+和Pb2+胁迫具有一定的适应性。重金属Cd2+和Pb2+胁迫导致米氏凯伦藻细胞的叶绿素a、叶绿素b含量下降(1.6 mg•L-1 Pb2+胁迫除外), 类胡萝卜素含量提高, 最大光能转化效率(Fv/Fm)下降, 表明重金属胁迫抑制藻的光合作用, 影响藻的生长繁殖。丙二醛(MDA)随着重金属Cd2+和Pb2+浓度提高而升高, 说明重金属引起藻细胞膜透性增加, 藻细胞遭受破坏。SOD活性整体呈现先升高后下降(或与对照持平)的趋势, 提示海洋微藻的抗氧化酶系统在低浓度重金属胁迫下产生应激性反应, 酶活性增强; 而CAT活性上升, 也对藻细胞起到保护作用, 推测两者共同反应, 以缓解藻体遭受的重金属毒害作用。结果可为了解重金属胁迫对海洋微藻的毒性效应提供参考。     

重金属诱导拟南芥原生质体DNA损伤的单细胞凝胶电泳检测

以拟南芥原生质体为实验体系,研究不同浓度的3种重金属离子对拟南芥原生质体的毒性和DNA损伤的差异。结果表明,用1-5mmol·L^-1的Zn^2＋、Cd^2＋和Cu^2＋分别处理的拟南芥原生质体,2小时内活力逐渐下降,并表现出明显的浓度依赖性：与相同浓度的Cd^2＋和Cu^2＋相比,Zn^2＋对拟南芥原生质体活力的影响程度较小,表现出较低的毒性。单细胞凝胶电泳检测发现,用0．1-0．8mmol·L^-1的Zn^2＋、Cd^2＋和Cu^2＋分别处理拟南芥原生质体30分钟,以OTM值表示的原生质体DNA损伤量随重金属离子浓度的增加而递增：相同浓度（0．5mmol·L^-1）的3种重金属离子相比,Zn^2＋对原生质体的遗传毒性明显低于Cu^2＋和Cd^2＋。综合原生质体活力和DNA损伤的单细胞凝胶电泳检测结果,发现ZnO^2＋对拟南芥原生质体的遗传毒性较低,而CdO^2＋和Cu^2＋的遗传毒性较高。本研究建立的拟南芥原生质体实验体系,结合运用单细胞凝胶电泳技术,能够快速、灵敏地检测重金属对植物细胞的遗传毒性。     

三种地卷响应Cu~(2+)胁迫的差异分析

基于谷胱甘肽(Glutathione,GSH)含量变化和铜吸附性分析地卷、平盘软地卷和犬地卷响应Cu~(2+)胁迫的差异,以了解谷胱甘肽在低等生物地衣抗重金属胁迫中的作用。分光光度法和火焰原子吸收方法分别测定地衣体的GSH与细胞内、外的铜含量。结果显示,低浓度Cu~(2+)胁迫下,3种地卷GSH均呈上升趋势,4 mmol/L时达最高;5-8 mmol/L时,地卷和犬地卷的GSH逐步下降较明显,但仍显著高于对照组,而平盘软地卷GSH在3-5 mmol/L Cu~(2+)范围差异不显著,Cu~(2+)5 mmol/L时才出现较明显的下降(P0.05)。4 mmol/L Cu~(2+)处理时间不同时,犬地卷的GSH变化与处理时间正相关,而地卷和平盘软地卷的GSH出现波动式变化(6 h增加,12 h下降,18-24 h上升)。3种地卷胞外铜与Cu~(2+)浓度和处理时间呈正相关并显著高于胞内铜(P0.01),而胞内富集的铜与地衣GSH变化相对应呈高-低-高的变化趋势。菌藻共生的特殊生物-地卷类似于高等植物可诱导合成GSH缓解胁迫产生的伤害,3种地卷的铜耐受性差异与其铜吸附性和GSH合成能力密切相关。     

TUNEL法检测Cu~(2+)胁迫诱导的中国树花共生藻细胞的死亡

为了探讨铜离子胁迫对中国树花共生藻细胞毒害作用的机制及细胞死亡的原因,通过徒手切片,采用两种TUNEL检测法(Promega和Roche试剂盒)对2mmol/L和4mmol/L Cu~(2+)胁迫24h的中国树花地衣体共生藻细胞凋亡情况进行观察。结果表明:(1)伊文思蓝染色法检测结果显示,中国树花共生藻细胞活力在2和4mmol/L Cu~(2+)胁迫下显著降低,其细胞的死亡率随着Cu~(2+)浓度的提高和处理时间的延长而明显增加;(2)在2和4mmol/L Cu~(2+)胁迫条件下,中国树花共生藻细胞的TUNEL阳性细胞率在Promega试剂盒中检测结果分别为50.30%和31.21%,而在Roche试剂盒中共生藻细胞TUNEL阳性标记核分别为53.17%和36.88%,两种TUNEL检测法结果类似。(3)与伊文思蓝染色法检测的Cu~(2+)胁迫中国树花共生藻细胞活力相比,发现较低浓度的Cu~(2+)(2mmol/L)胁迫对地衣共生藻细胞的毒害作用可诱导启动细胞凋亡程序,而较高浓度的Cu~(2+)(4mmol/L)胁迫对地衣共生藻产生较严重的毒害则导致大部分细胞的坏死,只有极少数细胞出现细胞凋亡。(4)两种试剂盒均可用于较低浓度Cu~(2+)胁迫引起的地衣体共生藻细胞凋亡的检测;直接将徒手切片材料用于TUNEL细胞凋亡原位检测中也得到了较理想的结果,避免了制备石蜡切片的繁琐步骤,缩短实验时间,简化了实验流程。     

Seasonal study of the fungal biota of the fur of dogs

During a one year period, 944 dogs from the Municipal kennel of Barcelona were examined to detect animals with suspected dermatophytosis. Only a few animals (1.8%) presented skin lesions but none of them had dermatophytosis. A representative number of dogs without visible skin lesions (n=172), selected at random, were used to carry out a seasonal study of the mycobiota of their fur. Fifteen isolates belonging to the genera Microsporum and Trichophyton were isolated from 14 of the 172 (8.1%) dogs without lesions. The identity of these fungi was Microsporum gypseum (6/15), Trichophyton terrestre (4/15), M. canis (2/15), M. cookei (2/15) and Trichophyton ajelloi (1/15) (one strain each of M. gypseum and T. ajelloi were isolated from one dog). Species of Penicillium (% prevalence=89.5%), Alternaria (86.6%), Cladosporium (84.9%), Aspergillus (77.3%), Scopulariopsis (65.7%) and Chrysosporium (64.5%) were the most prevalent. No significant differences in the fungal biota were observed with respect to age, gender, hair length or between mixed and pure breed dogs. A large number of isolates, including species belonging to the genera Beauveria, Chrysosporium, Malbranchea and Scopulariopsis, that macroscopically and/or microscopically resemble dermatophytes and may be mistaken for them, produced a red color change in Dermatophyte Test Medium. No significant seasonal difference was detected among the isolates belonging to the the most frequently encountered genera, with the exception of Scopulariopsis (higher in summer and autumn) and Chrysosporium (higher in summer). Species from other genera, with lower occurrence also presented significant differences in their seasonal distribution. Arthrinium, Aureobasidium, Chaetomium and Phoma spp. presented maximum prevalence peaks in spring, Fusarium, Paecilomyces, Phoma and Rhizopus spp. in summer and Geotrichum and Mucor spp. in autumn. The Microsporum and Trichophyton species were more frequently isolated in summer.     

Spatial distribution of brood-bearing females of limnetic species of Cladocera

In this study, the spatial distribution of brood-bearing females of five species of limnetic cladocerans (Daphnia cucullata, D. longispina, Bosmina coregoni, B. longirostris, Diaphanosoma brachyurum) in the deep mesotrophic lake in relation to the predation pressure of planktivorous fish (roach Rutilus rutilus, perch Perca fluviatilis, catfish Ictalurus nebulosus, white fish Coregonus albula, bleak Alburnus alburnus), and planktonic invertebrates (cyclopoids Mesocyclops leuckartii, Thermocyclops oithonoides, T. crassus, and cladoceran Leptodora kindtii) as well as some environmental variables was estimated. Most cladocerans showed apparent differences in horizontal distribution (ANOVA F = 0.2–0.45, P < 0.05) in the littoral zone and lack of such differences in the pelagic zone (F = 0.07–0.13, P > 0.05). Vertical distribution of most species, in turn, showed a clear pattern in the pelagic zone (F = 0.31–0.39, P < 0.05) and less regularities in the littoral zone (F = 0.15–029, P > 0.05). The differences in spatial distribution of non-predated and predated species suggest that predation pressure, but not predatory type, was an important factor structuring their distribution. Other factors that affected their distribution were conductivity, dissolved oxygen, TOC and macrophyte biomass; however, most of those variables better explained the distribution of brood-bearing cladocerans in the vertical than horizontal aspect.     

Effects of different batches of iodine on properties of I-hFSH and characteristics of radioligand-receptor assays

Radioiodination of highly purified human follicle-stimulating hormone (hFSH) (4000 IU/mg) was performed every other week for 23 weeks using 2 mCi carrier free Na ¹²⁵I (Amersham Corp., 15 mCi/μg I₂) in the presence of lactoperoxidase. Incorporation of ¹²⁵I into hFSH was determined by the method of [7.]Biochem. J. 89, 114). Hormone binding was studied in vitro under steady-state conditions (16 h, 20°C) using different calf testis membrane preparations having similar receptor characteristics. Each ¹²⁵I-hFSH preparation was characterized for maximum bindability, specific activity of bindable radioligand as determined by self-displacement analysis, and by determination of K_a and R_t. Incorporation of ¹²⁵I into FSH was relatively constant over the large number of experiments (62.4 ± 6.4 μCi/μg; n = 23). By comparison, however, specific radioactivity of the receptor bindable fraction of ¹²⁵I-hFSH was related to the lot of ¹²⁵I utilized, and was significantly (P ≤ 0.01) lower and more variable (28.7 ± 10.5 μCi/μg). Maximum bindability of ¹²⁵I-hFSH was not correlated to specific activity (r = 0.06) but was negatively correlated to hFSH ¹²⁵I incorporation (r = −0.47; P ≤ 0.05). These observations demonstrate the need to assess the quality of each batch of radioligand before undertaking radioligand-receptor assays and suggest that differences in Na¹²⁵I lots affect specific radioactivity of the radioligand and its receptor binding characteristics.     

Estimation of genome sizes of hyperthermophiles

Genomes of various hyperthermophilic and extremely thermophilic prokaryotes were analyzed with respect to size, physical organization, and 16S rDNA copy number. Our results show that all the genomes are circular, and they are in the size range of 1.6–1.8 Mb for Pyrodictium abyssi, Methanococcus igneus, Pyrobaculum aerophilum, Archaeoglobus fulgidus, Archaeoglobus lithotrophicus, and Archaeoglobus profundus (the two bacteria Fervidobacterium islandicum and Thermosipho africanus possess genomes of 1.5-Mb size). A systematic study of all validly described species of the order Sulfolobales revealed the existence of two classes of genome size for these archaea, correlating with phylogenetic analyses. The Metallosphaera–Acidianus group, plus Sulfolobus metallicus, have genomes of ca. 1.9 Mb; the other members of the order Sulfolobales group possess genomes >2.7 Mb. The special case of Stygiolobus azoricus is discussed. Received: August 10, 1997 / Accepted: January 1, 1998     

Effect of temperature on the duration of larval and pupal stages of two species of sciomyzid flies, predators of the snail Lymnaea truncatula

The duration of larval and pupal stages of two species of predatory flies was investigated at five constant temperatures. Ilione albiseta (Scopoli): Mean duration of first and second instars was shortest at 23°C and there was 100% survival of first instar larvae at all temperatures. Mean third instar larval duration decreased from 104 days at 17°C to 27.5 days at 26°C. Total percentage larval survival was greatest at 17°C and least at 26°C. Mean pupal duration decreased as temperature increased and this occurred also under outdoor conditions. Pherbellia cinerella (Fallén): As temperature increased mean larval duration decreased but the percentage of larvae pupating also decreased (100% at 14°C, 33.3% at 26°C). There was a trend for shorter mean pupal durations at higher temperatures.

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Résumé L'action de la température a été examinée à 14, 17, 20, 23 et 26°C. Les 2 espèces sont prédatrices de L. truncatula, vecteur de la douve du foie en Irlande, où elle provoque à l'àgriculture une perte évaluée à 10 millions de livres par an. Les données recuellies en conditions contrôlées du laboratoire doivent permettre de définir les conditions optimales pour l'élevage continu de ces espèces. Ceci est indispensable pour évaluer, dans la nature leurs potentialités pour la lutte biologique. Ilione albiseta: C'est à 23°C que le développement des larves de premier et second stades sont les plus brefs; la survie du premier stade est totale à toutes les températures constantes examinées. La durée moyenne du 3ème stade décroît de 104 jours à 17°C jusqu'à 27,5 jours à 26°C. Le taux de survie total est plus élevé à 17°C qu'à 26°C. La durée moyenne de la nymphose diminue quand la température croît, et ceci se produit aussi à la température ambiante extérieure. On réduit de moitié la durée du développement de l'éclosion de l'oeuf à l'apparition de l'adulte, entre la nature et le laboratoire, en utilisant respectivement: 23°, 17° et 26°C pour les premier et second stades, le troisième stade, la nymphé. Cela devrait aider à multiplier la souche pour la lutte biologique. Pherbellia cinerella: Avec élévation de la température la durée du développement larvaire diminue, mais aussi le nombre de larves parvenant à la pupaison (100% à 14° et 33,3% à 26°C). La nymphose tendait à être plus brève aux températures les plus élevées.

     

Stimulation by interferon of induction of differentiation of human promyelocytic leukemia cells

F₁-ATPase was isolated from yeast $\text{S.}\text{cerevisiae}$. The constituent subunits 1 and 2 were purified by gel permeation chromatography, and their amino acid compositions determined. Both subunits have a similar composition except for $\text{1}\text{2}$ cystine, methionine, leucine, histidine, and tryptophan. When F₁ is treated for three hours with 5′-p-[³H]fluorosulfonylbenzoyl adenosine in dimethylsulfoxide, 90% of the activity is lost. Disc gel electrophoresis of the modified complex showed that over 90% of the label was associated with subunit 2. A labelled peptide from a $\text{S.}\text{aureus}$ digest of subunit 2 was isolated and sequenced. It had the following amino acid sequence: His-Try¹-Asp-Val-Ala-Ser-Lys-Val-Gln-Glu, whereby Tyr¹ is the modified amino acid residue. This sequence shows homology to other sequences obtained from maize, beef heart, and $\text{E.}\text{coli}$ F₁-ATPases.     

Cytogenetics of Brazilian species of Bromeliaceae

This paper presents the mitotic chromosome numbers of 18 species of Bromeliaceae. The diploid number 2n = 50 was observed in Aechmea comata, A. caudata, A. correia‐araujoi, A. recurvata, A. marauensis, A. bicolor, A. pineliana, Hohenbergia catingae, H. blanchetti, Alcantarea imperialis, Al. nahoumi, Neoregelia tenebrosa, Nidularium lyman‐smithii, N. scheremetiewii, N. innocentii var. innocentii, and N. innocentii × Neoregelia johannis hybrid, whereas 2n = 34 was observed in Cryptanthus maritimus and C. warren‐loosei. All of the determinations presented in this study are previously unpublished, except A. comata and H. catingae. These results confirm x = 25 as the basic number for the family and x = 17 as a secondary basic number probably generated by decreasing dysploidy. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 189–193.     

Peculiarities of Selectivity of Three Subtypes of Low-Threshold T-Type Calcium Channels

Despite the progress in studies of the properties and functions of low-threshold calcium channels (LTCCs) [1], the mechanisms of their selectivity and permeability remain unstudied in detail. We performed a comparative analysis of the selectivity of three cloned pore-forming LTCC subunits (α1G, α1H, and α1I) functionally expressed in Xenopus oocytes with respect to bivalent alkaline-earth metal cations (Ba²⁺, Ca²⁺, and Sr²⁺. The relative conductivities (G) of these channels were determined according to the amplitudes of macroscopic currents (I) and potentials of zero currents (E). The currents were recorded after preliminary intracellular injection of a fast calcium buffer, BAPTA, in order to suppress the endogenous calcium-dependent chloride conductivity. Channels formed by α1G subunits demonstrated the following ratios of the amplitudes of macroscopic currents and potentials of zero current: I _Ca:I _Ba:I _Sr = 1.00:0.75:1.12 and E _Ca ≈ E _Ba ≈ E _Sr. For channels that were formed by α1H and α1I subunits, these ratios were as follows: I _Ca:I _Ba:I _Sr = 1.00:1.20:1.17, E _Ca ≈ E _Ba ≈ E _Sr and I _Ca:I _Ba:I _Sr = 1.00:1.48: 1.45, E _Ca ≈ E _Ba ≈ E _Sr respectively. The different macroscopic conductivities and similar potentials of zero current typical of α1G and α1I channels indicate that, probably, various bivalent cations can in a differential manner influence the stochastic parameters of functioning of these channels. At the same time, channels formed by α1H subunits are characterized by more positive potentials of zero current for Ca²⁺. It seems possible that the selectivity of the above channels is determined by mechanisms that mediate the selectivity of most high-threshold calcium channels (more affine binding of Ca²⁺ inside the pore). Neirofiziologiya/Neurophysiology, Vol. 37, No. 4, pp. 319–329, July–August, 2005.     

Influence of method of presentation on results of plant-host preference tests with two species of grasshopper

Leaf material of two Piper spp. (Piperaceae) was presented to two different generalist herbivores (Orthoptera: Acrididae) to determine whether method of leaf presentation in preference trials affects choice. For the grasshopper Leptomerinthoprora brevipennis, the method of presentation had no effect on preference ranking: more of Piper sancti-felicis was eaten than of P. arieianum, regardless of whether leaf material was presented as leaf disks, whole leaves supplemented with water, or whole leaves without water. In contrast, preference of the grasshopper Abracis flavolineata depended on presentation method. In that case, whole leaves of P. scancti-felicis supplemented with water were preferred over the same of P. arieianum, while dry weight consumption of leaf disks of P. arieianum was greater than that for disks of P. sancti-felicis. When presented with leaves not supplemented with water, A. flavolineata showed no significant preference for one plant species over another.

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Résumé Des feuilles provenant de deux espèces de Piper (Piperacae) ont été proposées à deux Orthoptères, Acrididae, herbivores généralistes, pour déterminer si la méthode de présentation des feuilles modifiait le choix. Pour Leptomerinthoprora brevipennis, la méthode de présentation est sans influence sur l'ordre de préférence; la consommation de Piper sancti-felicis est toujours supérieure à celle de P. arieianum, quelque soit le mode de présentation: disques de feuilles, feuilles entières humidifiées, ou feuilles entières sans addition d'eau. A l'opposé, l'ordre de préférence de Abracis flavolineata dépend du type de présentation; les feuilles entières humidifiées de P. sancti-felicis sont préférées à celles de P. arieianum proposées de la même façon, tandis que la consommation de disques secs de P. arieianum est plus importante que celle des disques secs de P. sancti-felicis. En présence de feuilles entières humidifiées, A. flavolineata ne manifeste aucune préférence.

     

Pollen analysis of honeys from the northwest of Argentina: Province of Jujuy

The palynological characterisation of 157 honey samples from three northwest regions of Argentina (Prepuna, Yungas and Chaco) are presented to determine their botanical origin and species associations to be able to define their geographic origin. Samples were harvested during 2003–2011 and processed by means of melissopalynological conventional techniques. One-hundred and nine pollen types were identified. Representative pollen types with a frequency of occurrence greater than 50% in descending order of importance are: Salix humboldtiana, Allophylus edulis, Baccharis, Solanaceae, Eucalyptus, Schinus, Brassicaceae, Papilionoideae, Celtis, Scutia/Condalia-type and Parapiptadenia excelsa. The most important monofloral honeys are from the following: Salix humboldtiana, Scutia/Condalia-type, Allophylus edulis, Baccharis, Blepharocalyx salicifolius, Gleditsia amorphoides, Myrtaceae, Sicyos, Ziziphus mistol, Schinopsis-type, Agonandra excelsa, Anadenathera colubrina, Mimosa, all of them native species, and among introduced species are Eucalyptus, Citrus and Tithonia. Three apicultural zones and their corresponding pollen association indicators were determined: Zone I, Prepuna: Arquita trichocarpa, Prosopis ferox, Schinus areira, Baccharis, Buddleja and Mutisieae; Zone II, Yungas: Myrtaceae, Parapiptadenia excelsa, Baccharis, Salix humboldtiana, Allophylus edulis, Scutia/Condalia-type and Zanthoxylum coco; Zone III, transitional area Yungas-Chaco: Prosopis, Salix humboldtiana, Schinus, Anadenanthera colubrina and Allophylus edulis.