Determination of Homalodisca coagulata (Hemiptera: Cicadellidae) egg ages suitable for oviposition by Gonatocerus ashmeadi, Gonatocerus triguttatus, and Gonatocerus fasciatus (Hymenoptera: Mymaridae)

Homalodisca coagulata (Say) (Hemiptera: Cicadellidae) eggs 1–10 days of age were exposed to Gonatocerus ashmeadi Girault, Gonatocerus triguttatus Girault, and Gonatocerus fasciatus Girault (all Hymenoptera: Mymaridae) in no choice laboratory trials to investigate egg age utilization and to determine which egg ages are vulnerable to attack by these three parasitoids. The H. coagulata egg ages that were most suitable for oviposition by G. ashmeadi, G. triguttatus, and G. fasciatus were eggs 3, 4, and 2 days of age, respectively. Egg ages least suitable for parasitoid development were 6–10 days for G. ashmeadi (resulting in <50% parasitism), 1–2 and 7–10 days for G. triguttatus (resulting in <25% parasitism), and 3–10 days for G. fasciatus (resulting in <11% parasitism). Pooling parasitism data across all egg ages showed that parasitism by G. ashmeadi was 12.9 and 28.5% higher compared with G. triguttatus and G. fasciatus, respectively, and G. triguttatus resulted in 15.6% higher percentage parasitism compared with G. fasciatus. Egg age had a significant effect on the percentage of female G. ashmeadi offspring produced, but this was not significant for G. triguttatus, and low G. fasciatus parasitism prevented statistical analyses for comparisons. Results from tests where females were offered a choice for oviposition between eggs 1, 3, and 5 days of age demonstrated that G. ashmeadi and G. triguttatus showed no significant oviposition preference, while percentage parasitism by G. fasciatus was 29.4 and 7.4% higher when females were presented eggs 1 and 3 days of age, respectively, compared with eggs 5 days of age. Choice tests indicated that an overlap in egg age suitability for oviposition exists between G. ashmeadi, G. triguttatus, and G. fasciatus, and that interspecific competition for eggs 1, 2, and 3 days of age may occur in the field environment.     

Detecting Karenia brevis blooms and algal resuspension in the western Gulf of Mexico with satellite ocean color imagery

Blooms of the toxic dinoflagellate, Karenia brevis, have had detrimental impacts on the coastal Gulf of Mexico for decades. Detection of Karenia brevis blooms uses an ecological approach based on anomalies derived from ocean color imagery. The same anomaly product used in Florida produces frequent false positives on the Texas coast. These failures occurred during wind-driven resuspension events. During these events resuspension of benthic algae significantly increases chlorophyll concentrations in the water, resulting in confusion with normal water column phytoplankton, such as Karenia. A method was developed to separate the resuspended chlorophyll from the water column chlorophyll, decreasing the false positives used with the detection method.     

Electrophysical characteristics of Azospirillum brasilense Sp245 during interaction with antibodies to various cell surface epitopes

This work was undertaken to examine the electrooptical characteristics of cells of Azospirillum brasilense Sp245 during their interaction with antibodies developed to various cell surface epitopes. We used the dependences of the cell suspension optical density changes induced by electroorientation on the orienting field frequency (740, 1000, 1450, 2000, and 2800kHz). Cell interactions with homologous strain-specific antibodies to the A. brasilense Sp245 O antigen and with homologous antibodies to whole bacterial cells brought about considerable changes in the electrooptical properties of the bacterial suspension. When genus-specific antibodies to the flagellin of the Azospirillum sheathed flagellum and antibodies to the serologically distinct O antigen of A. brasilense Sp7 were included in the A. brasilense Sp245 suspension, the changes caused in the electrooptical signal were slight and had values close to those for the above changes. These findings agree well with the immunochemical characteristics of the Azospirillum O antigens and with the data on the topographical distribution of the Azospirillum major cell surface antigens. The obtained results can serve as a basis for the development of a rapid test for the intraspecies detection of microorganisms.     

A thermostable cysteine protease precursor from a tropical plant contains an unusual C-terminal propeptide: cDNA cloning, sequence comparison and molecular modeling studies

We report here the cloning and characterization of the entire cDNA of a papain-like cysteine protease from a tropical flowering plant. The 1098-bp ORF of the cDNA codify a protease precursor having a signal peptide of 19 amino acids, a cathepsin-L like N-terminal proregion of 114 amino acids, a mature enzyme part of 208 amino acids and a C-terminal proregion of 24 amino acids. The derived amino acid sequence of the mature part tallies with the thermostable cysteine protease Ervatamin-C--as was aimed at. The C-terminal proregion of the protease has altogether a different sequence pattern not observed in other members of the family and it contains a negatively charged helical zone. The three-dimensional model of the precursor, based on the homology modeling and X-ray structure, shows that the extended peptide stretch region of the N-terminal propeptide, covering the interdomain cleft, contains protruding side chains of positively charged residues. This study also indicates that the negatively charged zone of C-terminal propeptide may interact with the positively charged zone of the N-terminal propeptide in a cooperative manner in the maturation process of this enzyme.     

Reactive oxygen species in regulation of fungal development

Reactive oxygen species (ROS) are formed by fungi in the course of metabolic activity. ROS production increases in fungi due to various stress agents such as starvation, light, mechanical damage, and interactions with some other living organisms. Regulation of ROS level appears to be very important during development of the fungal organism. ROS sources in fungal cells, their sensors, and ROS signal transduction pathways are discussed in this review. Antioxidant defense systems in different classes of fungi are characterized in detail. Particular emphasis is placed on ROS functions in interactions of phytopathogenic fungi with plant cells.     

Macroinfauna community structure and biochemical composition of sedimentary organic matter along a gradient of wave exposure in sandy beaches (NW Spain)

Six sandy beaches on the North West coast of Spain, exposed to different wave action, were sampled in order to study the macroinfauna community and the biopolymeric fraction (proteins, lipids and carbohydrates) of sedimentary organic matter. According to McLachlan’s rating system (1980), three of them were classified as sheltered and the other three as exposed beaches. Sampling was carried out during August 2004 at three tidal levels: high, medium and low. Macroinfauna community and organic matter concentrations were found to be significantly different when sheltered and exposed beaches were compared. Macroinfauna diversity (H′), abundances and biomass became increasingly enriched along a gradient from exposed to sheltered beaches. Macroinfauna mean abundance was found higher in sheltered (ranked from 1535 ± 358 to 15062 ± 5771 ind m⁻²) than in exposed beaches (from 150 ± 41 to 5518 ± 1986 ind m⁻²). Macroinfauna biomass ranged from 3.2 to 14.7 g m⁻² and species richness from 25 to 27 in sheltered localities; while in exposed beaches, biomass ranged from 0.2 to 2.3 g m⁻² and the number of species from 5 to 14. The biopolymeric carbon concentration (BPC) was significantly higher in sheltered (from 84.7 ± 44.7 to 163.3 ± 34.8) than in exposed (from 30.3 ± 7.5 to 78.7 ± 12.3) beaches. The low hydrodynamic conditions of sheltered beaches favoured the settlement of organic rich fine sediments, being supported by the higher protein to carbohydrate ratio found in the exposed (from 23.5 ± 0.9 to 32.7 ± 4.4), rather than in the sheltered localities (from 6.2 ± 0.7 to 13.6). Mean macroinfauna abundances were higher at medium and low tidal levels in both sheltered and exposed beaches. Crustacea was found to be the main group inhabiting the upper part of both types of beaches, dominating all tidal levels of exposed sandy beaches. Mollusca and Polychaeta groups were dominant in sheltered beaches at the medium and lower levels. There was a significant negative relationship between the BPC and the beach face slope; thus, BPC decreased as the intertidal slope increased. It seems that exposed sandy beaches are mainly physically controlled, whereas hospitable sheltered beaches let other factors, such as biochemical compounds, enrich the benthic fauna scenery. Electronic Supplementary Material  Supplementary material is available in the online version of this article at and is accessible for authorized users Handling editors: K. Martens     

城市扩张与耕地保护耦合对陆地生态系统碳储量的影响——以湖北省为例

城市扩张对生态系统的影响可以分为城市扩张对生态用地的直接挤占以及为补充城市扩张占用的耕地对生态用地二次挤占两个连锁的过程。以往的研究大多只关注城市扩张对生态系统的直接影响,忽略了城市扩张与耕地保护耦合的间接影响。针对这一问题,采用GIS空间分析方法和InVEST模型定量评估了2000年至2015年湖北省城市扩张与耕地保护耦合对陆地生态系统碳储量的影响。结果显示:(1)城市扩张与耕地保护耦合导致湖北省陆地生态系统碳储量减少40.90 Tg;(2)由城市扩张与耕地保护耦合导致的陆地生态系统碳储量的减少量中,耕地保护传导作用间接导致的占比31%。结果表明,城市扩张与耕地保护的耦合是导致生态系统碳储量减少的主要原因之一。忽视城市扩张通过耕地保护的传导作用对生态系统碳储量的间接影响,会导致城市扩张对陆地生态系统碳储量的影响被严重低估。     

西南岩溶地区石漠化综合治理研究

我国西南岩溶地区石漠化是人地矛盾作用下生态系统退化的过程或结果,石漠化不仅带来水土流失加剧、旱涝灾害频发、生物多样性降低等生态问题,还会带来贫困落后等一系列社会问题。20世纪80年代开始进行的石漠化治理工作已经成为我国西南岩溶地区生态文明建设的重要举措与必由之路,通过近40年来的石漠化治理使得我国西南岩溶地区石漠化问题恶化的趋势开始得到扭转。面向生态文明新时期的建设目标,石漠化脆弱区仍存在人地矛盾难以全面消除、治理成果可持续性亟待提升等问题,石漠化防治需要从多年来石漠化治理研究与实践探索积累中汲取有益于促进人地和谐、提升生态系统可持续性的治理经验与做法。因此,本文以石漠化治理典型区域调研资料与文献资料为数据基础,从石漠化治理目标、技术、措施和模式四个层面梳理石漠化治理经验与做法,归纳总结出石漠化综合治理四点配置原则:(1)以治理目标与预期周期为导向,确立石漠化治理采取的措施;(2)针对解决的关键生态退化问题,结合区域特征遴选石漠化治理技术;(3)针对石漠化退化阶段的差异,确定石漠化治理途径措施;(4)结合石漠化综合治理模式的共性特征,以小流域为基本单元,因地制宜的选择与构建石漠化综合治理模式。以期通过对实践经验的总结为石漠化治理过程中选择具备区位适宜性和机理明晰性的生态技术提供参考。