Evaluation of Azotobacter and Azospirillum as Biofertilizers in Aquaculture

Summary A preliminary comparative evaluation of the two commonly encountered free-living nitrogen fixers in the aquatic system, Azotobacter and Azospirillum was carried out in the laboratory for use as biofertilizers in aquaculture considering the importance of eco-friendly and econo-friendly productivity optimization of freshwater aquaculture. The ammonium–nitrogen levels in water media in Azotobacter treatment varied in the range 2.59–34.34 μg-N/l and was found to be significantly different from that of Azospirillum treatment (p < 0.05). The viable population of the respective nitrogen fixers as colony forming units (c.f.u.) in water media in charcoal-immobilized Azotobacter treatment ranged from 0.39 to 2.48 × 10³ c.f.u./ml and were significantly higher (p < 0.05) than the counterparts. The nitrogenase activity in the same treatment similarly remained higher, at 8.3–12.15 nmol of ethylene/ml water/h followed by the alginate-immobilized Azotobacter treatment which was at 7.2–11.40 nmol of ethylene/ml water/h compared to 5.8–7.8 and 4.65–4.83 in the respective Azospirillum-treated counterparts. Hence, better performance of Azotobacter sp. over Azospirillum sp., and of charcoal immobilization over alginate immobilization were observed.     

DoMicrocystis aeruginosa toxins accumulate in the food web: a laboratory study

The accumulation ofMicrocystis aeruginosa hepatotoxins (microcystin-LR) in the phantom midge larvaChaoborus was studied in a 16 d laboratory experiment. In the cyanobacteria treatment,Chaoborus larvae were fed withDaphnia pulex juveniles which had been feeding for two days on a mixture ofScenedesmus obtusiusculus and toxicMicrocystis aeruginosa. In the control treatment theChaoborus larvae were offeredD. pulex raised onScenedesmus only. An HPLC analysis failed to detect any cyanobacteria toxin in theChaoborus larvae, indicating that the toxin was metabolized or excreted byD. pulex andChaoborus. There was a statistically significant increase in mortality of larvae in the cyanobacteria treatment, but no difference between treatments in pupation success ofChaoborus was observed.     

Evaluating the Risk of Infection from the Presence of Giardia and Cryptosporidium in Drinking Water

Monte-Carlo simulations were performed in order to quantify the microbiological risk arising from the presence of Giardia and Cryptosporidium in drinking water. A two-year survey of 45 utilities located on a portion of the St. Lawrence River (Quebec, Canada) allowed us to collect the information required for this assessment: parasite occurrence data, treatment performances and daily unboiled water consumption. For a conventional treatment, the mean annual risk of infection with Cryptosporidium was found to be approximately eight times higher than with Giardia. The Monte-Carlo simulations confirm that the clarification process plays an important role in the reduction of the health risk associated with protozoan parasites. In fact, in the case of Cryptosporidium, the impact of chemical disinfectants (O₃ or Cl₂) appears to be minimal in the cold water treatment conditions prevailing in Quebec. According to the Monte-Carlo simulations, 45% (for conventional treatment+O₃) and 51% (for conventional treatment) of individuals are exposed to a risk of infection with Cryptosporidium higher than the proposed USEPA guideline (1 infection per 10[emsp4 ]000 individuals per year).     

爵床的甲醇提取物对小菜蛾的生物活性作用

为探明爵床(Justicia procumbens)甲醇提取物对小菜蛾的生物活性,采用室内生测法测定了爵床甲醇提取物对小菜蛾的触杀、拒食、胃毒、生长发育抑制和产卵忌避作用。结果表明,爵床甲醇提取物对小菜蛾幼虫具有较强的触杀、拒食、胃毒和生长发育抑制活性,对小菜蛾成虫具有较强的产卵忌避活性。在触杀试验中,药后1、2 d和3 d爵床甲醇提取物对小菜蛾3龄幼虫的致死中浓度(LC50)分别为5.17、4.05和3.06 mg/m L;在拒食试验中,药后1 d和2 d提取物对3龄幼虫的选择性拒食中浓度(AFC50)分别为2.64和3.13 mg/m L,药后1 d和2 d提取物对3龄幼虫的非选择性拒食中浓度(AFC50)分别为3.70、4.54 mg/m L;在胃毒试验中,药后4、5、6 d和7 d提取物对3龄幼虫的致死中浓度(LC50)分别为8.13、3.65、2.88、2.23 mg/m L;在生长发育抑制试验中,药后1 d和2 d提取物对3龄幼虫的抑制中浓度(IC50)分别为2.02、1.40 mg/m L;在产卵忌避试验中,药后1、2 d和3 d提取物对小菜蛾成虫的选择性产卵忌避中浓度(AOC50)分别为2.61、3.66、4.58 mg/m L,药后1、2和3 d提取物对小菜蛾成虫的非选择性产卵忌避中浓度(AOC50)分别为3.19、4.52、5.65 mg/m L。由此证实,爵床提取物对小菜蛾具有显著的毒杀活性,具有开发为新型高效、低毒植物源农药的潜在价值。     

Competitive effects of the invasive shrub,Lonicera maackii (Rupr.) Herder (Caprifoliaceae), on the growth and survival of native tree seedlings

Invasive plants are often associated with reduced cover of native plants, but rarely has competition between invasives and natives been assessed experimentally. The shrub Lonicera maackii, native to northeastern Asia, has invaded forests and old fields in numerous parts of eastern North America, and is associated with reduced tree seedling density in Ohio forests. A field experiment was conducted to test the effects of established L. maackii on the survival and growth of transplanted native tree species. The experiment examined above-ground competition (by removing L. maackii shoots) and below-ground competition (by trenching around transplanted seedlings). The effects of above-ground competition with L. maackii were generally more important than below-ground competition, though both were detected. Shoot treatment was the key determinant for the survival of all species except P. serotina, whereas trenching only enhanced survival for A. saccharum caged and P. serotina, and only in the shoot removal treatment. For the surviving seedlings, L. maackii shoot removal increased growth of A. saccharum seedlings protected with cages, but actually reduced the growth of unprotected Q. rubra and A. saccharum seedlings, indicating that L. maackii shoots confer some protection from deer browsing. Significant interactions between root and shoot treatment on Q. rubra growth parameters, specifically greatest growth in the shoot present & trenched treatment, is attributed to protection from deer browsing combined with release from below-ground competition. Despite this protective function of L. maackii shoots, the overall effect of this invasive shrub is increased mortality of native tree seedlings, suggesting it impacts the natural regeneration of secondary forests.     

盐胁迫对拟南芥AtPUB18基因的诱导表达及其启动子分析

用300mmol/L NaCl处理拟南芥幼苗,分别于处理后0、1、2、4、8、16、24、48h通过Northern Blot检测其AtPUB18基因的表达量。结果显示:拟南芥AtPUB18基因的表达量受高盐胁迫的诱导而升高,于处理后4h表达量达到最高,处理后16h表达量最低。采用PCR技术克隆AtPUB18的启动子,序列为1 974bp;序列分析发现启动子内含有大量与非生物胁迫相关的顺式作用元件,如HSE、LTR、MBS及ABRE;将启动子克隆到表达载体pCambia1300-221-GUS中,驱动报告基因GUS表达。组织化学染色结果表明,未经过高盐处理的幼苗中GUS基因表达水平很低;300mmol/L NaCl处理后GUS基因表达量显著升高。研究表明,AtPUB18的表达受高盐胁迫诱导,且AtPUB18基因的启动子是一个盐胁迫诱导型启动子。     

Saccharification of used paper with different cellulases

Various used paper materials have been exposed to the action of cellulases from Penicillium funiculosum, Trichoderma reesei, Trichoderma viride and Aspergillus niger. A 2 h incubation period showed cellulase from T. viride the most active except for office paper that was maximally degraded by A. niger cellulase. Cellulase mixtures increased saccharification while sequential treatment with cellulases from T. reesei and P. funiculosum increased biodegradation at values between 15% and 190%. The maximum increase of saccharification (190%) was obtained when T. reesei cellulase initiated the sequential treatment of newspaper relative to the sole action of P. funiculosum cellulase on this non-pretreated and pretreated material.     

Revision ofVerbesina sect.Pseudomontanoa (Asteraceae)

Verbesina sect.Pseudomontanoa is revised. The last treatment of the group byRobinson & Greenman (1899) recognized 5 species; the present treatment recognizes 12 species, 3 of which (V. breedlovei, V. cronquistii andV. olsenii) are described as new. A key to species, phyletic diagram and distribution maps are provided.     

棉花抗枯萎病相关转录因子基因的克隆与表达

以枯萎病菌诱导棉花基因表达谱中获得的差异表达bZIP作为探针,采用电子克隆结合RT-PCR方法从棉花抗枯萎病品种‘中棉所12’中克隆了1个TGA转录因子基因,命名为GhTGA2.2。序列分析表明,该基因的cDNA全长1 356bp,编码451个氨基酸,预测分子量为50.04kD,等电点为5.85,含有保守的bZIP结构域。系统进化树分析表明,GhTGA2.2属于bZIP亚家族的TGA转录因子,与拟南芥AtTGA2、烟草NtTGA2.2亲缘关系最近。qRT-PCR分析表明,经枯萎病菌诱导后,GhTGA2.2基因在抗病品种中呈上调表达,随处理后时间的推移,其相对表达量呈先升高后降低的趋势,并于处理后24h表达量达到最大;水杨酸诱导后1h,GhTGA2.2基因相对表达量迅速增加;茉莉酸和乙烯诱导后GhTGA2.2基因的相对表达量明显降低,呈下调表达。研究推测,GhTGA2.2基因可能通过水杨酸信号传导途径参与对枯萎病菌的防御反应。     

Persistence of <Emphasis Type="Italic">Paranosema</Emphasis> (<Emphasis Type="Italic">Nosema</Emphasis>) <Emphasis Type="Italic">locustae</Emphasis> (Microsporidia: Nosematidae) among grasshopper (Orthoptera: Acrididae) populations in the Inner Mongolia Rangeland,China

Paranosema (Nosema) locustae Canning has persisted in grasshopper populations in the Inner Mongolia Rangeland since spore treatment was applied in 1993. In the treatment year, a 58.32–71.43% reduction of grasshoppers was recorded and 59.26–80.36% of surviving grasshoppers of various species were infected. In the years following application, prevalence of P. locustae varied from 13.65% to 60.71%, demonstrating that P. locustae remains in grasshopper populations for many years. Infection prevalence was more than 60.00% for Dasyhippus barbipes (F.-W.), Bryodema luctuosum luctuosoma (Stoll) and Angaracris barabensis (Pall.) in 1993 but was very variable, ranging from 20.00% to 60.71% over the subsequent nine years. Disease prevalence was 43.72–60.71% in 1993 and 1994 for Oedaleus asiaticus B.-Bienko and Myrmeleotettix palpalis (Zub.) but gradually declined to approximately 20%, where it remained. Persistence of P. locustae in grasshopper populations may be important in keeping densities below economic thresholds for a number of years after application. Handling Editor: Helen Roy.     

土壤水分及其垂直分布对内蒙古草原冰草和冷蒿竞争的影响

内蒙古退化冷蒿草原围封恢复演替3-4年,植物群落更替出现半灌木冷蒿（Artemisia frigida）向禾草冰草（Agropyron cristatum）群落突然转变的现象,这对内蒙古草原植被恢复具有积极的作用,但目前关于冰草-冷蒿演替和竞争机制的研究鲜见报道。水分作为草原植被生长的主要限制因子,是影响群落演替的重要因素。气候干旱和过度放牧导致草原土壤水分垂直分布发生明显变化。由于冰草和冷蒿的根系分布深浅不同,土壤水分垂直变化可能会影响冰草-冷蒿的竞争。为探讨土壤水分及其垂直分布对冰草和冷蒿竞争的影响,本盆栽试验设置冰草、冷蒿单种以及混种处理,并进行不同土壤深度（0-30cm,30-60cm）的水分处理（上干下湿、上湿下干、上干下干）,结果表明：（1）与冷蒿相比,冰草受土壤水分变化影响显著,相对于上干下干处理,冰草在湿润（上干下湿或者上湿下干）处理的地上、地下生物量均显著增加,而冷蒿没有显著变化;（2）上干下湿和上湿下干处理间,冰草、冷蒿的地上、地下总生物量和根长差异均不显著;（3）不同水分处理,冰草和冷蒿的根系均可分布在30-60cm土壤中,且土壤30-60cm层冰草单种的根生物量和根长显著高于冷蒿单种;（4）相对竞争强度和竞争攻击力系数表明：湿润处理冰草的竞争力大于冷蒿;上干下干处理冷蒿的竞争力大于冰草。土壤水分变化引起冰草、冷蒿的明显竞争,上湿下干与上干下湿处理间冰草与冷蒿竞争力差异不显著。由于冰草和冷蒿均为多年生物种,冰草-冷蒿的竞争实验仍需在今后的研究中反复地验证。     

Porphyra nereocystis: A dual-daylength seaweed

Conchospores from the perennial conchocelis phase of the annual, epiphytic, marine red alga Porphyra nereocystis Anderson, which in nature lives on the large annual kelp Nereocystis luetkeana (Mertens) Postels et Ruprecht, are released in culture only in response to a short-day photoperiod treatment followed by a long-day treatment. Each treatment requires a minimum of three to four weeks and is enhanced by lower temperature during the second photoperiod treatment. To our knowledge P. nereocystis is the first known dualdaylength seaweed and requires a short-day-longday treatment for completion of its life cycle. This stringent environmental control of its reproduction appears to be an adaptation to coordinate conchospore production with the seasonal availability of its host kelp Nereocystis.Abbreviations LD long day - SD short day - SLD shortlong day     

Phylogenetic systematics of the monotypic genus Hayataella (Rubiaceae) endemic to Taiwan

Hayataella (Rubiaceae) is a monotypic genus endemic to Taiwan that comprises H. michelloides. In recent years, Hayataella was considered to be synonymous with Ophiorrhiza; however, no specific data have been reported, and the systematic treatment of Hayataella has been unclear. To elucidate the systematic treatment of Hayataella, molecular phylogenetic analyses based on ITS of nrDNA, atpB–rbcL, and trnK/matK of cpDNA were conducted with four Ophiorrhiza species. In the Bayesian and the most parsimonious trees, H. michelloides was included in the Ophiorrhiza clade. The monotypic status of Hayataella is, therefore, not considered appropriate, and the combination Ophiorrhiza michelloides (Masam.) H. S. Lo is supported.     

Quantification of<Emphasis Type="Italic">Bacillus</Emphasis> species in a wastewater treatment system by the molecular analyses

Bacillus species were observed and quantified by molecular approaches, using the 165 rDNA primers/probes, in a wastewater treatment plant designed for the purpose of stimulating the growth ofBacillus species. The plant has been operating as a test plant since 1997 in the city of Ina, Japan, with excellent treatment performance. Observations byin situ hybridization, usingBacillus-specific probes, indicated thatBacillus strains were inhabited in the plant and their numbers decreased during the treatment process. Similar results were obtained from a quantitative PCR analysis using aBacillus-specific primer set, and the amount of DNA originating from variousBacillus species was maximally 1.91% of the total DNA in the wastewater treatment tank. Clone library analysis using theBacillus-specific primers suggested that, while the population was noticeably increased, the phylogenetic diversity of the increasingBacillus species was very low.     

Biocontrol of the apple sawfly,Hoplocampa testudinea,with entomogenous nematodes

Four types of experiments were conducted to assess the pathogenicity of entomogenous nematodes against the apple sawfly,Hoplocampa testudinea Klug (Hymenoptera: Tenthredinidae). In Petri dish,Steinernema carpocapsae (Weiser) DD 136 strain,S. carpocapsae All strain,S. feltiae (Filipjev) andHeterorhabditis bacteriophora Poinar caused 100% larval mortality 72 h after the treatments. In semi-field conditions under dwarf apple trees, a single treatment with either 40 or 80S. carpocapsae All strain/cm² caused significant (>80%) larval mortality. No significant increase in mortality was obtained with a second application. In 1990, late treatment with 80S. carpocapsae All strain/cm² caused significant (39.1%) pupal mortality. In 50×50 cm quadrats under dwarf apple trees, treatment with 40 and 80S. carpocapsae All strain/cm² were done in spring 1989. In spring 1990, respectively 22 and 25 apple sawfly adults emerged from quadrats treated with 40 and 80S. carpocapsae All strain/cm², whereas 78 adults emerged from untreated quadrats. In a foliar application experiment, a single treatment withS. carpocapsae All strain significantly reduced the percent of fruit showing secondary damage. The possibility of using entomogenous nematodes as part of an integrated pest management in apple orchards is discussed, with particular reference to the integration of programs aimed at managing plum curculio,Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae) populations.      

Effects of the infection of toxigenic fungi and an antagonistic Streptomyces strain on wheat spikes

The objective of the present study was to determine the effect on infection of wheat spikes by toxigenic fungi (Aspergillus parasiticus NRRL 2999, Fusarium tricinctum NRRL 3299, Fusarium graminearum CEREMIC 136/92) and a strain of Streptomyces sp. that is antagonistic to the above-mentioned fungi. Wheat grains (variety GRANERO INTA) were sown in 8 pots containing natural soil and kept in a greenhouse chamber. In the period of the early anthesis the wheat spikes were inoculated with conidial suspensions of each of the fungi in the presence or absence of Streptomyces. Each pot was assigned a different treatment. After an incubation of 100 days and when the wheat plants had attained maturity, the spikes were separated and the following items were determined: (a) number of grains obtained with each treatment, (b) weight of the grains, (c) average weight of the grains/treatment, (d) average number and weight of the grains/spike, and (e) invasion of the caryopses by the microorganisms determined by the analysis of the caryopses in seriate histological sections.There was a significant decrease (p<0.01) in the average weight of the caryopses and in the weight and number of grains/spike in the presence F. graminearum. The wheat grains were invaded by of F. graminearum and A. parasiticus, an effect which was partially attenuated by the presence of antagonist Streptomyces sp. Nevertheless, the effect was not strong enough to prevent the degenerative consequences on the size and weight of the grains produced by F. graminearum.     

种间竞争对香蒲与芦苇生长的影响

为了探究种间竞争对香蒲（Typha domingensis）与芦苇（Phragmites australis）生长的影响,利用根系分隔盆栽试验研究了3种不同分隔方式条件下香蒲与芦苇的种间竞争特性,包括塑料膜分隔（根系完全分隔,无相互作用,无物质交换）、尼龙网分隔（根系部分分隔,无相互作用,有物质交换）和不分隔（根系完全相互作用,有物质交换）,分析了香蒲与芦苇根系形态和地上部生长的变化,探究香蒲与芦苇种间竞争的差异。结果发现（1）在尼龙网分隔和不分隔处理中芦苇具有明显的劣势。与塑料膜分隔处理相比,芦苇的总生物量、植株密度在尼龙网分隔和不分隔处理中分别减少了39.14%、49.41%和82.08%、79.22%,总根长、总根表面积、总根体积分别减少了40.53%、44.84%、62.52%和85.7%、82.45%、89.67%,且均具有极显著差异（P<0.01）;根系分隔方式也影响芦苇的株高、茎粗和叶片数,表现为不分隔 > 塑料膜分隔 > 尼龙网分隔。（2）与塑料膜分隔处理相比,香蒲总生物量在尼龙网分隔和不分隔中虽有增加,但差异不显著,植株密度和株高在尼龙网分隔和不分隔处理中都有增加且具有显著差异（P<0.05）,其总根长、总根表面积、总根体积在尼龙网分隔中分别增加了57.93%、26.5%、8.04%,但在不分隔处理中分别减少了11.57%、14.92%、11.39%（P<0.05）,虽然根系的相互作用对香蒲根系的生长具有促进作用,但植物种间根系相互作用越强,对两者的生长越不利。（3）在不同的分隔方式中,芦苇与香蒲间也存在明显变化。在不分隔处理中,香蒲的生物量和植株密度是芦苇的1.7倍和6.74倍,与塑料膜分隔处理相比增加了6倍,表明芦苇与香蒲根系的完全相互作用,显著削减了芦苇的繁殖生长,增加了香蒲的根系分蘖。（4）通过种间相互作用强度（RII值）分析也表明,尼龙网分隔和不分隔处理下芦苇表现为抑制作用（RII值为负值）,香蒲表现为促进作用（RII值为正值）。香蒲与芦苇互作对芦苇具有抑制作用,说明种间相互作用是能改变植物的适应性和植物群落的繁殖,同时也表明植物根系不仅在吸收土壤中的水和养分中起着关键作用,在种间关系中也起着重要作用。因此利用种间竞争控制植物生长,可以为保护生物多样性和生态系统的功能提供有效的技术支撑。     

The 2,4-D-induced wheat para-nodules are modified lateral roots with structure enhanced by rhizobial inoculation

Nodular outgrowths (para-nodules or p-nodules) on the roots of wheat (Triticum aestivum L.) cv. Miskle seedlings were induced by treatment with 0.3 and 0.6mg L^–1 2,4-dichlorophenoxyacetate (2,4-D). When co-inoculated with Rhizobium trifolii strain ATCC 14480, more p-nodules were formed at these levels and p-nodulation occured at 0.1 mg L^–1 indicating that inoculation enhances 2,4-D-induced p-nodulation. Similar to lateral roots, the p-nodules arose from the pericycle opposite the phloem tissues and were free from the cortical cells of the parental root at all stages of development. Structurally, the p-nodules exhibited tissue differentiation. They possessed a highly organized central vascular cylinder connected to that of the parent root, an endodermis, a cap, and an apical and lateral meristems. P-nodules formed by 2,4-D treatment alone were irregularly lobed due to uncoordinated activity of the apical meristem, while those in the combined 2,4-D and inoculation treatment were more globose. The results of the present study indicate that the 2,4-D-induced wheat p-nodules are modified lateral roots, the structure of which is enhanced by rhizobial inoculation.     

Agar quality of commercial agarophytes from different geographical origins: 1. Physical and rheological properties

Six economically important species ofGracilaria, from a number of commercial sources around the world, andGracilariopsis lemaneiformis, collected from two Japanese localities, were used as the sources of raw material for the evaluation of agar quality. Agar-agar was extracted by pretreatment with various concentratrions of NaOH (0%, 3%, 5%, 7%, 10%) incubated at 80 °C for 2 h. Agar yield, viscosity, dynamic gelling and melting temperature and gel texture were determined for 1.5% agar gels. The highest agar yield was obtained fromG. gracilis from Argentina (39.5%), while the lowest was from BrazilianG. gracilis (13.37%). Dynamic gelling temperature was highest in the agar fromG. gracilis from Turkey (59 °C) and lowest in the non-alkali treated agar isolated fromG. edulis from Indonesia (46 °C). Melting temperature ranged from 96 °C in the agars from the JapaneseGracilariopsis andG. chilensis from Chile to 69 °C in the non-alkali treated agar fromG. edulis from Indonesia. In general, all species produced an agar with high gel strength after treatment with 5% NaOH, except forG. chilensis and the twoGracilariopsis species, which produced an agar with high gel strength after treatment with 3, 7 and 10% NaOH. The highest gel strength (2056 ± 13.6 cm^–2) and hardest gel (261 ± 19.89 g mm^–2) were obtained fromG. lemaneiformis from Japan (Oita Prefecture) after treatment with 7 and 10% NaOH respectively. The lowest gel strength (351 ± 93 cm^–2) was obtained fromG. gracilis from Brazil after treatment with 3% NaOH. The softest gel (66.31 ± 9.63 g mm^–2) was isolated fromG. tenuistipitata from China, after treatment with 3% NaOH. The most flexible gel (11.62 ± 0.31 g mm^–2 × 10²) was obtained fromG. chilensis from Chile after treatment with 3% NaOH.Author for correspondence