Poplar (Populus nigra L.) plants transformed with aBacillus thuringiensis toxin gene: insecticidal activity and genomic analysis

Insect-resistant poplar (Populus nigra L.) plants have been produced by infecting leaves withAgrobacterium tumefaciens strains carrying a binary vector containing different truncated forms of aBacillus thuringiensis (B.t.) toxin gene under a duplicated CaMV 35S promoter. Putative transgenic plants were propagated by cuttings at two experimental farms (in Beijing and Xinjiang, China). At 2–3 years after transformation, 17 of them were selected on the bases of insect-tolerance and good silvicultural traits, and evaluated for insect resistance, for the presence of theB.t. toxin DNA fragment (Southern blots and PCR) and for the expression of the transgene (western and northern blots). Somaclonal variation, as suggested by the appearance of permanent changes in the shape of the leaves, was also investigated with molecular tools (RFLP (restriction fragment length polymorphism), RAPD (random amplified polymorphic DNA) and microsatellite DNA).Bioassays withApochemia cineraius andLymantria dispar on the leaves of the selected clones showed different and, in some cases, high levels of insecticidal activity. The molecular analysis demonstrated integration and expression of the foreign gene. Somatic changes were correlated to extensive genomic changes and were quantified in dendrograms, in terms of genomic similarity. The analysis of control plants suggested that genomic changes were correlated to thein vitro culture step necessary forA. tumefaciens-mediated gene transfer, rather than to the integration of the foreign genes.Three transgenic clones (12, 153 and 192), selected for insect resistance, reduced morphological changes and promising silvicultural traits, are now under large-scale field evaluation in six different provinces in China.     

豆田刺吸类害虫、天敌自然种群消长规律及其群落结构的研究

在豆田群落中,常见的天敌昆虫及有益生物为12科13种,它们对寄主均有很强的选择性．小花蝽是大豆蚜的主要天敌,系优势种,其次是龟纹瓢虫．大青叶蝉的主要天敌是蜘蛛类,三突花蛛和草间小黑蛛为优势种．在长期不施用农药的环境下,天敌自然种群对控制害虫发生危害的作用明显．经数学分析,建立了12个数学模型,进一步揭示了两种刺吸类害虫与其天敌之间的关系;天敌种群消长、害虫种群消长与时间变动的关系．尤其通过对豆田群落生物的多样性、稳定性动态分析,表明豆田群落在8月9日至8月29日多样性指数和稳定性指数最大;同时亦表明豆田群落的多样性指数愈高,群落的稳定性愈强．     

In vitro peptidergic neurons from the adult locust pars intercerebralis: Morphological and immunocytological studies

Primary cell cultures were prepared from a major neurosecretory center of the adult locust brain, the pars intercerebralis, in order to characterize neurosecretory cells growingin vitro. Individual pars intercerebralis could be removed free of surrounding tissue and dissociated by mechanical treatment. Mature neurosecretory neurons of different sizes regenerate new neurites during the initial three daysin vitro in serum-free medium. They show a tendency to sprout one primary neurite from which fine processes develop. By means of electron microscopy, we observed the integrity of the cellular organelles, indicating that cultured neurons are healthy, and we were able to distinguish three types of neurosecretory neurons on the basis of the ultrastructural aspects of the neurosecretory material. These three types have the same ultrastructural characteristics asin situ neuroparsin, ovary maturing parsin and locust insulin related peptide neurons. Immunogold labelling at the electron microscopic level, using the two available specific antibodies, anti-neuroparsin and anti-ovary maturing parsin, confirms the morphological characterization of neuroparsin and ovary maturing parsin cells. These results show for the first time that cultured locust neurosecretory neurons behave like thosein vivo, in terms of their ultrastructure and immunocytochemistry. Moreover, the presence of recently-formed neurosecretory material both in the Golgi zone of the perikaryon and in the neuronal processes indicates that cultured neurons have functional capacity since they are able to synthesizede novo and to transport the neurosecretory material along the neurite. Thus our well-characterized culture system provides a suitable invitro model to investigate the secretory mechanism of locust neurosecretory neurons.     

组建昆虫系统生物学的目的性和可行性探索

通过作在昆虫生物学方面近五十年研究工作的体会．提出了组建昆虫系统生物学的目的性和可行性探索．拟以昆虫分类序列目、科、属、种为单元,将一些已知种类的有关生物学环节．一一列叙．编成《中国农林昆虫系统生物学手册》．再以目、科、属、种为主体,探求彼此间在生物学各环节间的共性和个性,分别加以比较、归纳和分析．作为这—分支学科的蘸本。     

Hypothesis on adaptive features of the compound eye of bees: Flower-specific specializations

Summary This note surveys the current knowledge of the existence of acute zones in insects' eyes in relation to beeflower interactions.We suggest some broad generalizations correlating the size, use, structure and presentation of flowers with the foraging behaviour, body size and eye design of bees.Special emphasis is given to the differences between small and large bees and the architecture of flowers that they use.     

Flight initiation byProstephanus truncatus in relation to time of day, temperature, relative humidity and starvation

Studies were carried out in the laboratory on the influences of time of day, temperature, relative humidity and starvation on flight initiation byProstephanus truncatus (Horn) (Coleoptera: Bostrichidae). Flight occurred throughout the 12 h photophase and at the beginning of the scotophase but peaked at 2–0 h before darkness. Temperature exerted a significant effect on flight. The frequency of flight take-off increased with temperature over the range 20–30°C but declined sharply at 35°C. Flight activity increased with starvation up to a maximum at 2 days after which it began to decline.     

Development of an immunoassay to detect insect contamination of microalgal products

While the insect fragment count is currently the primary test used for assessing insect contamination of food products, this technique is very problematical for assaying microalgal materials. An account is given of a new immunoassay technique,which is based on an enzyme-linked immunosorbent assay(ELISA) detection of insect myosin and which provides a rapid and convenient means of quantitatively determining the amount of insect contamination in algal product samples with a high degree of replicability. Up to 30 samples can be tested in duplicate in 2.5–3 h. Experiments were carried out with a variety of common contaminant insects of algal products, using various life stages, including Corixidae, Ephydridaeand Chironomidae using both Spirulina (Arthrospira) and Chlorella as typical algal materials. As little as one insect per 50 g sample can readily be detected, with excellent correlation (r² = 0.99) between the number of insects present and the color produced. A matrix analysis to determine the ruggedness of the immunoassay was carried out following the protocols of the AOAC International and established that minor departures in seven variables from the standard assay resulted in no substantial differences. The insect myosin assay offers a quantitative and reliable means for assessing insect contamination of algal materials and should be considered for adoption as a standard method for this type of product. This revised version was published online in August 2006 with corrections to the Cover Date.     

Distribution of SchistoFLRFamide-like immunoreactivity in the adult ventral nervous system of the locust,Schistocerca gregaria

SchistoFLRFamide (PDVDHVFLRF-NH₂) is one of the major endogenous neuropeptides of the FMRF-amide family found in the nervous system of the locust,Schistocerca gregaria. To gain insights into the potential physiological roles of this neuropeptide we have examined the distribution of SchistoFLRFamide-like immunoreactivity in the ventral nervous system of adult locusts by use of a newly developed N-terminally specific antibody. SchistoFLRFamide-like immunoreactivity in the ventral nerve cord is found in a subgroup of the neurones that are immunoreactive to an antiserum raised against bovine pancreatic polypeptide (BPP). In the suboesophageal ganglion three groups of cells stain, including one pair of large posterior ventral cells. These cells are the same size, in the same location in the ganglion and have the same branching pattern as a pair of BPP immunoreactive cells known to innervate the heart and retrocerebral glandular complex of the locust. In the thoracic and abdominal ganglia two and three sets of cells, respectively, stain with both the SchistoFLRFamide and BPP antisera. In the abdominal ganglia the immunoreactive cells project via the median nerves to the intensely immunoreactive neurohaemal organs.     

The effect of plant chemistry on the acceptability of caterpillar prey to the argentine antIridomyrmex humilils (Hymenoptera: Formicidae)

Experiments were performed to test the acceptability of two palatable, cryptic caterpillars, the tobacco hornworm,Manduca sexta, and the cabbage looper,Trichoplusia ni, reared on different diets, to the Argentine ant,Iridomyrmex humilis. Ants preferred larvae reared on artificial diet, groundcherry, or cowpea to tobacco-reared larvae. Ants also preferred larvae reared on artificial diet without nicotine to larvae reared on diet containing nicotine (5% dry wt). Experiments were also performed to test the response of ants to larval extracts and chemicals applied to the surface of palatable prey. Ants did not respond differently to larvae of the potato tuber moth,Phthorimaea operculella, treated with larval extracts or regurgitate from tobacco-reared larvae compared to artificialdiet-reared larvae, but ants were deterred byP. operculella larvae treated with nicotine compared to untreated larvae. The results of this study indicate that caterpillars can derive at least some degree of chemical protection from their food plant without sequestering and storing plant compounds and without the development of elaborate aposematic characteristics.     

Efficient membrane targeting of the chick nicotinic acetylcholine receptor α-subunit in stable insect cell lines

We have synthesised the -subunit of the chick nicotinic acetylcholine receptor (nAChR) in stable, continuous insect (Spodoptera frugiperda) cell lines. A cDNA was integrated randomly into the insect cell genome under control of a baculovius immediate early gene promoter. Transformed cells were obtained by co-transfection of the insect cells with pIEK1.nAChR, encoding the -subunit cDNA, and pIEK1.neo, encoding the neomycin resistance gene. G-418-resistant clones were selected and expanded into continuous cell lines synthesising the chick nAChR -subunit. Using fluorescence microscopy and ligand binding studies we were able to demonstrate efficient membrane targeting of the receptor subunit in the insect cell plasma membrane. Stable insect cell lines may thus have significant advantages over transient baculovirus vectors for the synthesis and characterisation of heterologous receptor proteins.Abbreviations AcNPV Autographa californica nuclear polyhedrosis virus - BTX -bungarotoxin - BSA bovine serum albumin - FITC Fluoroscein isothiocyanate - G418 geneticin-418 - hpi hours post-infection - ie-1 immediate early 1 gene - nAChR nicotinic acetylcholine receptor alpha subunit - Sf Spodoptera frugiperda - tPA tissue plasminogen activator