十二种沫蝉的染色体研究 (同翅目： 沫蝉总科)

观察了同翅目头喙亚目12种沫蝉雄性的染色体数目和减数分裂行为。通过对沫蝉总科现有核型资料的分析,认为沫蝉总科的核型特点是：①染色体较小,数目较多,总科内染色体数目变化范围较大,众数为2n=26（24+XO）;②染色体的易位现象极为普遍,因此可以推测,通过染色体的易位导致染色体数目增加是核型进化的主要机制;③减数分裂前期Ⅰ具有典型的花束期,但没有弥散期。因此从精子发生来看沫蝉总科与叶蝉总科、角蝉总科和蝉总科的关系更为密切,而与蜡蝉总科的关系较远。头喙亚目的亲缘关系可能是：蜡蝉总科+{蝉总科+［沫蝉总科+（叶蝉总科+角蝉总科）］}。     

卵圆周氏沫蝉——中国尖胸沫蝉科一新属新种(同翅目:沫蝉总科)

本文记述我国尖胸沫蝉科(Aphrophoridac)一新属周氏沫蝉属Choua及其新种卵圆周氏沫蝉Chouaovalis。新属新种标本采自我国云南及东京湾。本属与云南沫蝉属Yunnana China,1925外型比较相似,但据雄性外生殖器可以相区别。     

中国西北地区下侏罗统三工河组原沫蝉科(昆虫纲:半翅目)一新属种*

本文根据一枚产自中国新疆维吾尔自治区下侏罗统三工河组的昆虫化石标本建立1新属新种——秉氏巨沫蝉(Magnicercopis pingi Zhang, Chen et Zhang, gen. et sp. nov.), 归入已灭绝的半翅目原沫蝉科。本新属的衍征包括: MP脉3分支, 存在横脉im, MP脉分支处于CuA脉分支处的基侧。本文对新属种与中国侏罗纪的原沫蝉科类群, 尤其是Longucercopis xinjiangensis Zhang, Chen et Zhang, 2022进行了详细的翅脉对比: M. pingi盖翅长约为L. xinjiangensis的两倍、MP脉3分支(后者2分支)、MP脉首次分支处位于CuA脉分支处基侧(后者位于CuA脉分支处端侧)、M. pingi具横脉im (后者未见im脉)。这一发现不仅提高了对原沫蝉科多样性的认识, 也丰富了该科的翅脉信息。     

沫蝉总科Cercopoidea昆虫

沫蝉总科Cercopoidea隶属于昆虫纲Insecta半翅目Hemiptera头喙亚目Auchenorrhyncha，包括沫蝉科Cercopidae、尖胸沫蝉科Aphrophoridae、巢沫蝉科Machaerotidae及长盾沫蝉科Clastopteridae4个科，我国只有前3个科的种类。沫蝉总科目前全世界记录约3000种，广泛分布于世界各地，中国已知的种类300余种。沫蝉的若虫第七、八腹节具有发达的泡沫腺，能分泌胶质，与呼出的气体相混，形成泡沫状液体盖住身体以作保护，因而得名沫蝉。本期封面照片拍摄于安徽宣城。     

携带Paenibacillus polymyxa WLY78固氮基因簇(nif)的重组大肠杆菌Escherichia coli78-7转录组分析

[目的]来自Paenibacillus polymyxa WLY78的固氮基因簇（nifBHDKEfNXhesAnifV）可以转化入Escherichia coli中表达并使重组大肠杆菌合成有固氮活性的固氮酶。本文拟通过对重组大肠杆菌E.coli 78-7的转录组分析以提高其固氮能力。[方法]对固氮条件（无氧无NH₄⁺）和非固氮条件（空气和100 mmol/L NH₄⁺）培养的重组大肠杆菌E.coli 78-7进行转录组分析。[结果]nif基因在两种培养条件下显著表达,说明在重组大肠杆菌中可规避原菌中氧气和NH₄⁺对nif基因的负调控。对于固氮过程必需的非nif基因,如参与钼、硫、铁元素转运的mod、cys和feoAB,这些基因在两种培养条件下表达水平有差异。而参与铁硫簇合成的suf和isc基因簇在两条件下表达水平差异巨大。此外,参与氮代谢的基因在固氮条件下显著上调。[结论]重组大肠杆菌中与固氮相关的非nif基因在该菌的固氮过程中具有较大影响,本文对在异源宿主中调高固氮酶活性研究具有重要意义。     

半翅目沫蝉总科化石研究进展

回顾半翅目沫蝉总科化石研究简史,列出已发表的化石名录、地理分布及地质年代,共6科、117属、252种;概述了沫蝉总科的地质历史,总结了世界沫蝉总科化石的组成,提出该类群昆虫化石研究中存在的问题,并对今后的研究前景进行展望.     

中国歧脊沫蝉属二新种(同翅目:尖胸沫蝉科)

本文记述我国歧脊沫蝉属二新种:阿里山歧脊沫蝉,新种Jembrana arisanensis sp.nov.及西藏歧脊沫蝉,新种Jembrana tibetana sp.nov.前者采自我国台湾阿里山,以其雄性外生殖器结构(图1—3)区别于属内其它种;后者采自我国西藏波密结达,与产自西藏错那及亚东阿桑的近似种长茎歧脊沫蝉J.longipensis Liang以其体极小型,触角檐细长,头冠及前胸背板中纵隆脊浅灰白色等相区别。     

具独特后翅翅脉的泰国叉脉叶蝉属两新属（半翅目：叶蝉科：小叶蝉亚科）

分别基于波茎赤叉脉叶蝉Rakta sinuata sp. nov. 为模式种建立了赤叉脉叶蝉属Rakta gen. nov.,基于双突白叉脉叶蝉Albodikra bifida sp. nov. 为模式种建立了白叉脉叶蝉属Albodikra gen. nov.,进行了描记和绘图。虽然这两个属的后翅翅脉近似于小绿叶蝉族的特征,但此处将它们置于小叶蝉中的叉脉叶蝉族,并讨论了归族所依据的形态特征。     

赤斑黑沫蝉的发生与防治

<正> 赤斑黑沫蝉Callitettix versicolor Fabricius,属同翅目,沫蝉科,近年来是我县局部地区丘陵地带对水稻为害最重的一种新害虫。一般受害轻者减产5％左右,重者40％以上。由于国内对该虫的发生和防治研究报道极少,在我省乐山地区还尚无此虫记载。因此,作者从1982年起对该虫进行了初步观察和防治研究,现将     

歧脊沫蝉属二新种(同翅目:尖胸沫蝉科)

本文记述采自我国西藏、陕西的尖胸沫蝉科Aphrophoridae歧脊沫蝉属Jembrana二新种。模式标本保存于西北农业大学昆虫博物馆。长茎歧脊沫蝉Jembranalongipensis,新种(图1—3) 头顶褐黄色,长约前胸背板的1/3;前缘钝圆,唇基端横向极狭长。触角檐短且厚,褐黄色;额脊、唇基端沟缺无。颜面短宽,棕褐色,二侧横脊浅簿。喙伸出后足转节之外,除东端一点黑褐色外褐黄色。     

A cladistic analysis ofAnisopappus (Asteraceae: Inuleae)

A cladistic analysis of the genusAnisopappus (Asteraceae: Inuleae) has been undertaken. A hypothesis of species interrelationships in the genus is presented for the first time. The analysis also includedArctotis (Arctoteae), used as outgroup, and five additional genera from theInuleae: Geigeria, Calostephane, Asteriscus, Buphthalmum, Pulicaria, andInula. It is concluded thatAnisopappus is a monophyletic group situated at the base of the tribe, diagnosed by, e.g., their obtuse stylar sweeping-hairs. The species with acute sweeping-hairs were found to be derived within the genus. Problems concerning species delimitation, biogeography and character evolution in the genus are briefly discussed.     

Internal transcribed spacer sequence analyses indicate cytoevolutionary patterns within Brachycome Cass. (Asteraceae)

The sequences of the Internal Transcribed Spacer regions (ITS1 and ITS2) within the genes coding for cytoplasmic ribosomal (r) RNAs on the A chromosome complement of 34 members of the higher plant genus Brachycome (synonym Brachyscome) have been compared. The ITS1 sequence of species within the B. lineariloba complex contains a 56 bp tract that is absent from at least 12 Brachycome species but is present in other species within Brachycome as well as other Asteraceae. Phylogenetic data support the suggestion that the number of chromosomes reduced in several independent Brachycome lineages during speciation. Comparisons with the B chromosome ITS2 of B. dichromosomatica cytodeme A1 suggests an origin of the B chromosome at a time prior to the divergence of the four cytodemes of B. dichromosomatica.     

Contribution from nitrogen fixation (acetylene reduction) to the nitrogen budget of Lake Tohopekaliga (Florida)

Nitrogen fixation, as assayed by the acetylene reduction technique, provided 44% of the input of nitrogen to a lake in central Florida (Lake Tohopekaliga) during 1984. Ninety-four percent of the lake total fixation was found in the water column and associated with Anabaena spp. The lake-wide average nitrogen fixation rate of 5.7 g N/m²-yr amounted to a mass loading of 497 metric tons of nitrogen for the year, and is one of the highest nitrogen fixation rates reported.     

Diversity of Rhizobium-Phaseolus vulgaris symbiosis: overview and perspectives

Common bean (Phaseolus vulgaris) has become a cosmopolitan crop, but was originally domesticated in the Americas and has been grown in Latin America for several thousand years. Consequently an enormous diversity of bean nodulating bacteria have developed and in the centers of origin the predominant species in bean nodules is R. etli. In some areas of Latin America, inoculation, which normally promotes nodulation and nitrogen fixation is hampered by the prevalence of native strains. Many other species in addition to R. etli have been found in bean nodules in regions where bean has been introduced. Some of these species such as R. leguminosarum bv. phaseoli, R. gallicum bv. phaseoli and R. giardinii bv. phaseoli might have arisen by acquiring the phaseoli plasmid from R. etli. Others, like R. tropici, are well adapted to acid soils and high temperatures and are good inoculants for bean under these conditions. The large number of rhizobia species capable of nodulating bean supports that bean is a promiscuous host and a diversity of bean-rhizobia interactions exists. Large ranges of dinitrogen fixing capabilities have been documented among bean cultivars and commercial beans have the lowest values among legume crops. Knowledge on bean symbiosis is still incipient but could help to improve bean biological nitrogen fixation.     

The genusIschnea (Asteraceae,Senecioneae) in New Guinea

The endemic New Guinean genusIschnea F. Muell. (Asteraceae, Senecioneae, Blennospermatinae) is revised and four species are recognized. Characters of special interest are tubeless ray florets, male disc florets, and secretory spaces in leaves. A principal component analysis is made on theIschnea elachoglossa F. Muell. complex which shows great variation. One new species,I. capellana Swenson, from the Star Mountains, is described. A key, illustrations, and distribution maps to all species are supplied.     

Investigations into the evolutionary history of theAntennaria rosea (Asteraceae: Inuleae) polyploid complex

TheAntennaria rosea polyploid agamic complex is one of the most morphologically diverse and widespread complexes of N. AmericanAntennaria. The group is taxonomically confusing because of numerous agamospermous microspecies, having been recognized as distinct species. Morphometric analyses have demonstrated that the primary source of morphological variability in the complex derives from six sexually reproducing progenitors,A. aromatica, A. corymbosa, A. media, A. microphylla, A. racemona, andA. umbrinella. Additionally, two other sexually reproducing species,A. marginata andA. rosulata, may have contributed to the genetic complexity of theA. rosea complex. Cluster analysis indicates that four discrete morphological groups exist within theA. rosea complex. Each group could be the result of predominance of genes from different groups of sexual progenitors. AsA. rosea is of multiple hybrid origin, from among several sexual progenitors, it is advisable to recognizeA. rosea as a distinct species from its sexual progenitors.Investigations into the evolutionary history of the polyploid complexes inAntennaria (Asteraceae: Inuleae). 3. TheA. rosea complex.     

In situ nitrogen fixation associated with seagrasses in the Gulf of Elat (Red Sea)

In situ nitrogen fixation associated with the seagrass Halophila stipulacea, at the northern Gulf of Elat (Red Sea), is eight to ten times higher than that of nearby plant-free areas. A daily cycle of nitrogen fixation is evident, with rates during the day being seven times greater than during the night. Removal of seagrass leaves only from a patch within a seagrass bed gradually decreases nitrogen fixation activity, reaching the rates of plant-free areas after ten hours. A method devised for the in situ measurement of nitrogen fixation rates using belljars is described in detail. Nitrogen fixation rates in situ are higher than in the laboratory and lack the lag period typical to laboratory measurements. In laboratory experiments using intact plant samples, glucose enhances nitrogen fixation rates both in light and dark. Photosystem II inhibitor (3-3,4-dichloro-phenyl-1,1-dimethylurea) doubles nitrogen fixation rates in light. Both field and laboratory results indicate that light is essential for nitrogen fixation activity in the H. stipulacea bed possibly through its effect on cyanobacterial population that occupy the aerobic niches of the phyllosphere and on photosynthetic Rhodospirillacean bacteria that inhabit the anaerobic ones. Nitrogen fixation rates evident in H. stipulacea beds in situ account for a considerable portion of the biomass production by the seagrasses. The dependence of high nitrogenase activity by the diazotrophs on the presence of the seagrasses indicates the great importance of the seagrass community to the nitrogen cycle in its highly oligotrophic surroundings of the Gulf of Elat.     

Ammonium sensing in nitrogen fixing bacteria: Functions of theglnB andglnD gene products

A plentiful supply of fixed nitrogen as ammonium (or other compounds such as nitrate or amino acids) inhibits nitrogen fixation in free-living bacteria by preventing nitrogenase synthesis and/or activity. Ammonium and nitrate have variable effects on the ability ofRhizobiaceae (Rhizobium, Bradyrhizobium andAzorhizobium) species to nodulate legume hosts and on nitrogen fixation capacity in bacteroid cells contained in nodules or in plant-free bacterial cultures. In addition to effects on nitrogen fixation, excess ammonium can inhibit activity or expression of other pathways for utilization of nitrogenous compounds such as nitrate (through nitrate and nitrite reductase), or glutamine synthetase (GS) for assimilation of ammonium. This paper describes the roles of two key genesglnB andglnD, whose gene products sense levels of fixed nitrogen and initiate a cascade of reactions in response to nitrogen status. While work onEscherichia coli and other enteric bacteria provides the model system,glnB and, to a lesser extent,glnD have been studied in several nitrogen fixing bacteria. Such reports will be reviewed here. Recent results on the identity and function of theglnB andglnD gene products inAzotobacter vinelandii (a free-living soil diazotroph) and inRhizobium leguminosarum biovarviciae, hereinafter designatedR.l. viciae will be presented. New data suggests thatAzotobacter vinelandii probably contains aglnB-like gene and this organism may have twoglnD-like genes (one of which was recently identified and namednfrX). In addition, evidence for uridylylation of theglnB gene product (the PII protein) ofR. l. viciae in response to fixed nitrogen deficiency is presented. Also, aglnB mutant ofR. l. viciae has been isolated; its characteristics with respect to expression of nitrogen regulated genes is described.     

Variation in moss-associated nitrogen fixation in boreal forest stands

Traditionally it has been thought that most boreal forest communities lack a significant input of biologically fixed nitrogen. Recent discoveries of nitrogen fixation by cyanobacteria associated with mosses have resulted in a re-evaluation of this view. While it is recognized that rates of nitrogen fixation in mosses can be highly variable, there is little understanding as to why this occurs. I monitored nitrogen fixation, using acetylene reduction, in wet lowland and dry upland boreal forest communities, in central Canada, over a growing season. At the peak of nitrogen fixation in mid summer, Sphagnum capillifolium had an 11 times higher rate of fixation than Pleurozium schreberi. Variation in canopy openness and precipitation had no effect on rates of fixation over the growing season. In P. schreberi fixation rates did not vary between sites. Temperature had a positive effect on fixation rates in both S. capillifolium and P. schreberi, but the effect was 4 times more pronounced in S. capillifolium. Seasonal rates of nitrogen fixation were estimated at 193 mg N m⁻² for S. capillifolium and 23 mg N m⁻² for P. schreberi. With moderate increases in climate warming, predicted increases in nitrogen fixation in S. capillifolium are sufficient to raise its decomposition rate. Increased temperatures may therefore act synergistically to change boreal systems from a sink to a source of carbon.     

Methods for enhancing symbiotic nitrogen fixation

Biological nitrogen fixation of leguminous crops is becoming increasingly important in attempts to develop sustainable agricultural production. However, these crops are quite variable in their effectiveness in fixing nitrogen. By the use of the ¹⁵N isotope dilution method some species have been found to fix large proportions of their nitrogen, while others like common bean have been considered rather inefficient. Methods for increasing N₂ fixation are therefore of great importance in any legume work. Attempts to enhance nitrogen fixation of grain legumes has been mainly the domain of microbiologists who have selected rhizobial strains with superior effectiveness or competitive ability. Few projects have focused on the plant symbiont with the objective of improving N₂ fixation as done in the FAO/IAEA Co-ordinated Research Programme which is being reported in this volume. The objective of the present paper is to discuss some possibilities available for scientists interested in enhancing symbiotic nitrogen fixation in grain legumes. Examples will be presented on work performed using agronomic methods, as well as work on the plant and microbial symbionts. There are several methods available to scientists working on enhancement of N₂ fixation. No one approach is better than the others; rather work on the legume/Rhizobium symbiosis combining experience from various disciplines in inter-disciplinary research programmes should be pursued.