Sporogenesis in Eusporangiate Ferns: II. Polyplastidic Meiosis in Ophioglossum (Ophioglossales)

Ophioglossum petiolatum . Unlike Angiopteris (Marattiales), which is monoplastidic, Ophioglossum undergoes polyplastidic meiosis like members of the fern-seed plant clade. The meiotic spindle is distinctly multipolar in origin and is consolidated into a bipolar spindle that is variously twisted and curved to accommodate the large number of chromosomes. Although a phragmoplast forms after first meiosis, no wall is deposited. Instead, an organelle band consisting of intermingled plastids and mitochondria is formed in the equatorial region between the dyad domains. Following second meiosis, a complex of phragmoplasts forms among sister and non-sister nuclei. Cell plates are deposited first between sister nuclei and then in the region of the organelle band resulting in a tetrad of spores each with a equal allotment of organelles. Received 30 January 2001/ Accepted in revised form 24 April 2001     

Partial purification and insecticidal activity of toxic metabolites secreted by a Mucor hiemalis strain (SMU-21) against adults of Bactrocera oleae and Ceratitis capitata (Diptera: Tephritidae)

The secondary metabolites present in the methanol extract of a Mucor hiemalis strain (SMU-21) mycelia, cultured in liquid medium, were evaluated for toxicity to Bactrocera oleae (Gmelin) and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) adults. Feeding and contact bioassays revealed that the methanol fraction of the crude supernatant was strongly toxic to both species. Symptoms of toxicity developed quickly; lethargy occurred 1-2 h posttreatment, and mortality reached 82-97% after 24 h. Both feeding and contact bioassays showed that B. oleae was more susceptible than C. capitata. Concentrations producing 50% mortality (LC50) to B. oleae and C. capitata after 24 h in feeding bioassays were 0.52 and 1.28 mg/ 0.1 ml diet, respectively, but 34.8 and 64.0 microg/ cm2, respectively, after 4 h in contact bioassays. Solvent partition, precipitation, and chromatographic procedures were used to isolate the active principles from the crude supernatant. These resulted in the isolation of one high-pressure liquid chromatography fraction with insecticidal activity on B. oleae flies equal to the initial crude supernatant.     

Chemical stimuli from corn plants affect host selection and oviposition behavior of Sesamia nonagrioides (Lepidoptera: Noctuidae)

The role of chemical stimuli in host selection and oviposition of Sesamia nonagrioides (Lef) was studied in the laboratory using eight corn hybrids. Female oviposition preference was evaluated on plants of the eight hybrids, their extracts in pentane and methanol, and volatiles collected by steam distillation in ether. Results from two-choice bioassays indicate various degrees of female preference to the hybrids. Four hybrids received more eggs than control plants, whereas the remainder received fewer eggs. Relatively similar results were obtained when filter paper sticks baited with pentane and steam distillation extracts were evaluated. Methanol extracts from all eight hybrids received fewer eggs than the methanol controls. Results showed that pentane and steam distillation extracts contain chemicals that elicit female oviposition response, while methanol extracts may contain chemicals that deter or repel females to oviposition.     

Flux Analysis of Glucose Metabolism in Rhizopus oryzae for the Purpose of Increasing Lactate Yields

A flux analysis of glucose metabolism in the filamentous fungus Rhizopus oryzae was achieved using a specific radioactivity curve-matching program, TFLUX. Glycolytic and tricarboxylic acid cycle intermediates labeled through the addition of extracellular [U-14C]glucose were isolated and purified for specific radioactivity determinations. This information, together with pool sizes and the rates of glucose utilization and end product production, provided input for flux maps of the metabolic network under two different experimental conditions. Based upon the flux analysis of this system, a mutant of R. oryzae with higher lactate and lower ethanol yields than the parent was sought for and found.     

Plant diversity positively affects short‐term soil carbon storage in experimental grasslands

Increasing atmospheric CO₂ concentration and related climate change have stimulated much interest in the potential of soils to sequester carbon. In ‘The Jena Experiment’, a managed grassland experiment on a former agricultural field, we investigated the link between plant diversity and soil carbon storage. The biodiversity gradient ranged from one to 60 species belonging to four functional groups. Stratified soil samples were taken to 30 cm depth from 86 plots in 2002, 2004 and 2006, and organic carbon contents were determined. Soil organic carbon stocks in 0–30 cm decreased from 7.3 kg C m^?2 in 2002 to 6.9 kg C m^?2 in 2004, but had recovered to 7.8 kg C m^?2 by 2006. During the first 2 years, carbon storage was limited to the top 5 cm of soil while below 10 cm depth, carbon was lost probably as short‐term effect of the land use change. After 4 years, carbon stocks significantly increased within the top 20 cm. More importantly, carbon storage significantly increased with sown species richness (log‐transformed) in all depth segments and even carbon losses were significantly smaller with higher species richness. Although increasing species diversity increased root biomass production, statistical analyses revealed that species diversity per se was more important than biomass production for changes in soil carbon. Below 20 cm depth, the presence of one functional group, tall herbs, significantly reduced carbon losses in the beginning of the experiment. Our analysis indicates that plant species richness and certain plant functional traits accelerate the build‐up of new carbon pools within 4 years. Additionally, higher plant diversity mitigated soil carbon losses in deeper horizons. This suggests that higher biodiversity might lead to higher soil carbon sequestration in the long‐term and therefore the conservation of biodiversity might play a role in greenhouse gas mitigation.     

556例多发伤患者的急诊救治临床分析

目的探讨多发伤患者的救治策略。方法回顾分析我科2000年1月至2008年5月急诊抢救的556例多发伤患者的临床资料。结果 16例患者经抢救无效死亡,死亡率2.88%;其余患者均经紧急抢救及行必要实验室检查,病情稳定,好转率达97.12%。平均抢救时间为(1.37±1.05)h。结论强化多发伤的急诊科早期救治,树立创伤急救"黄金1 h"观念,是提高多发伤患者生存率及降低死亡率的关键。     

Sporogenesis in Eusporangiate Ferns: I. Monoplastidic Meiosis in Angiopteris (Marattiales)

Angiopteris (Marattiales) undergoes the more primitive form of monoplastidic meiosis, while other ferns have evolved the polyplastidic type typical of seed plants. In monoplastidic cell division, the single plastid divides and serves as site of the microtubule organizing center (MTOC) for spindle formation resulting in coordinated division of plastid, nucleus, and cytoplasm. In plants with polyplastidic cell division, the MTOC is diffuse and generally perinuclear. Monoplastidic cell division is seen as a plesiomorphic feature that was inherited from algal ancestors containing a single plastid and modified through evolution. Monoplastidic meiosis occurs in all groups of bryophytes (although in only a few hepatics), Isoetes, Selaginella, certain generic segregates of Lycopodium, and in members of the Marattiales. It is not known to occur in psilophytes, Equisetum, leptosporangiate ferns, or seed plants. Received 30 January 2001/ Accepted in revised form 24 April 2001     

Kairomonal effect of sex pheromone components of two lepidopteran olive pests on Trichogramma wasps

Egg parasitoids are known to use a wide range of chemicals, emitted by plants, host eggs or adults, for host selection. The effect of the sex pheromone components of the lepidopteran olive pests Prays oleae (Lepidoptera: Yponomeutidae) and Palpita unionalis (Lepidoptera: Pyralidae) was studied under laboratory conditions, on the foraging behaviour of the egg parasitoid Trichogramma oleae (Hymenoptera: Trichogrammatidae). The response of T. oleae wasps to ( Z )-7-tetradecenal and ( E )-11-hexadecenal, major sex pheromone components of P. oleae and P. unionalis respectively, depended on the dose of the pheromone used in a Y-tube olfactometer bioassay. ( E )-11-hexadecenal elicited maximum attraction (70%) at a dose of 1 μg, while a dose of 100 μg ( Z )-7-tetradecenal attracted 80% of the tested wasps. ( E )-11-hexadecenyl acetate, the second sex pheromone component of P. unionalis , and the binary blend of ( E )-11-hexadecenyl acetate: ( E )-11-hexadecenal (7:3) were not attractive at these doses. The results of this research are discussed in view that they may be considered as alternatives in the biological control of these pests.