TOXICOKINETICS OF POLYCYCLIC AROMATIC HYDROCARBONS FROM CONTAMINATED SEDIMENT BY THE AMPHIBIAN LARVAE (PLEURODELES WALTL)

The molecular phototransformation mechanism of nitroarenes, genotoxic and ubiquitous pollutants in the atmosphere, is still under debate. With increasing exposure to radiation 1,6- and 1,8-dinitropyrene (DNP) in acetonitrile showed a decrease in their characteristic absorption bands (396 and 411 nm, respectively) in the presence of O ₂ , N ₂ and H ₂ O, and an increase in the 220–390 nm region and above 450 nm, indicating their photodegradation and transformation. The resulting photoproducts were highly fluorescent, presenting a broad emission band around 520–540 nm. Oxygen reactive species did not seem to be produced in the principal photodegradation pathways, since photodegradation rates were similar to those in anaerobic samples. In the presence of O ₂ or N ₂ 1,6-DNP photodegraded 4 times faster than 1,8-DNP, while in the presence of water is 1.5 times faster. Two chromatographic fractions were separated, and identified as pyrenediones using authentic samples and reported spectral data for hydroxy-nitropyrenes. Other chromatographic fractions are still to be identified. The properties of the identified products suggested that these were formed through a nitro-nitrite rearrangement.     

Description of the immatures of workers of the ant Linepithema micans forel (Hymenoptera: Formicidae)

Linepithema micans Forel is a poorly studied species that is now considered a pest in vineyards in South Brazil. Larval characters have been used in a few phylogenetic studies, and their importance greatly depends in the amount of available information on different species. This study presents a complete panorama on the external morphology of the immatures of L. micans based on observations by light and scanning electron microscopy. The number of larval instars was estimated as three based on the frequency distribution of head widths of 965 larvae. Larvae of L. micans were similar to other Linepithema Mayr in the general format of body and mandibles, presenting a dorsal abdominal protuberance, nine pairs of spiracle, and unbranched hairs. On the other hand, L. micans was unique for having shorter hairs, predominantly denticulate, intraspecific variation in the number of antennal sensilla and in the types of sensilla on the labial palps were reported. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.     

Zebrafish larvae as a model for the evaluation of inorganic arsenic and tributyltin bioconcentration

The European REACH legislation establishes the need to study the toxicity, persistence and bioaccumulation of those chemicals with an exceeding production of 100 tons and/or chemicals considered PBTs substances (Persistence, Bioaccumulation and Toxicity). Currently, the OECD technical guideline 305 is the most used protocol to determine bioconcentration factors of contaminants in aquatic environments. However, this procedure implies high cost and amount of adult fishes. Zebrafish (Danio Rerio) has been selected since this animal model has several advantageous features over other vertebrates, mainly fast embryonic development and easy growth. The analytical methodology here developed has been applied to calculate the bioconcentration factors (BCFs) of two contaminants: inorganic arsenic and tributyltin (measured as arsenic and tin). The method is based on the use of an ultrasonic probe assisted extraction for accelerating the sample treatment followed by detection using graphite furnace atomic absorption spectrometry with Zeeman correction (ZGFAAS). Results obtained for the BCFs values are in good agreement with previously reported data on freshwater aquatic organisms. In the case of arsenic, after exposing larvae to concentrations of 5 and 50 μg L⁻¹, very low BCFs were observed (between 2.2 and 9.5); while for tributyltin, the BCFs observed were within the range 840-1280 after exposure to concentrations of 0.2 and 2.0 μg L⁻¹, respectively. This study shows the use of zebrafish larvae together with the proposed analytical approach as a promising alternative to the OECD 305 test to evaluate the BCFs of classical and emergent contaminants.     

湿度对截头堆砂白蚁Cryptotermes domesticus （Haviland）补充型形成及繁殖的影响

本文主要论述截头堆砂白蚁在恒温27±1℃，相对湿度60％、75％、80％、90％条件下形成补充型及繁殖能力的试验结果。试验结果表明，温度适宜，湿度不适宜亦会影响该种白蚁补充型的形成及繁殖发展。该种白蚁的适宜湿度是75％－90％之间，最适宜湿度80％－90％。80％和90％这两组湿度的试验群体均能形成补充型，补充型均有繁殖功能，子代发育正常。     

Species‐specific fish larvae drift in anthropogenically constructed riparian zones on the Vienna impoundment of the River Danube,Austria: Species occurrence,frequencies, and seasonal patterns based on DNA barcoding

As a result of river regulations over several centuries, followed by restoration measures in recent decades, most of the River Danube shoreline is man‐made, primarily riprap, but some reconstructed gravel banks and riparian side arms. We investigated the effects of these different structures on fish larval dispersal over a 20‐km stretch in Vienna via the use of drift nets. The habitats examined were created 18 years ago when the impoundment of the Danube hydropower station Vienna/Freudenau was constructed. About 15,000 fish larvae were trapped, and a subsample was determined to species level by DNA barcoding. In total, 26 different species were detected, including 10 species that are endangered or in danger of extinction. When species composition was considered, cyprinids become dominant at sites downstream of gravel bars, whereas in riprap sections, the majority of the larvae consist of invasive Gobiidae. Side arm habitats provide spawning and nursery grounds for additional species. Furthermore, clear species‐related seasonal patterns were observed with peak densities and multiple spawning periods of some species being recorded. The largest peak of Percidae occurred in the first half of May, followed by Cyprinidae at the end of May and Gobiidae in mid‐June.     

2,6-Dichlorophenol in the tickRhipicephalus appendiculatus Neumann

Certain olfactory cells of maleRhipicephalus appendiculatus Neumann are known to be stimulated by 2,6-dichlorophenol.R. appendiculatus has been reexamined for the presence of 2,6-dichlorophenol, and it has been detected in both male and female adults. Unfed females contain 12 ng/ tick, declining to 2 ng/tick after six days of feeding, while unfed males contain 2 ng/tick, falling to 0 after feeding. Larval tick extracts which are also known to stimulate 2,6-dichlorophenol-sensitive cells were examined and found to contain this phenol, whereasR. appendiculatus eggs did not contain this compound.     

响应面法优化家蝇幼虫中抗氧化成分的提取工艺

以家蝇幼虫为原料,以1,1-二苯基苦基苯肼（DPPH）自由基清除率为指标,采用响应面法对其抗氧化成分的提取工艺进行优化．在单因素试验的基础上,采用全因子试验的方法,分别对提取条件中的甲醇体积分数、温度、时间三因素进行研究;通过二次回归方程解得出最佳配比为甲醇体积分数为36％,提取时间为4．8h,提取温度为18℃。经试验表明,在此条件下提取液对1,1-二苯基苦基苯肼（DPPH）自由基清除率为81．9％,与理论值接近．     

一株芽孢杆菌对河蟹蚤状一期幼体益生作用的初步研究

通过单株细菌感染河蟹蚤状幼体的方法获得一株对河蟹蚤状一期幼体有益生作用的菌株No.7,与对照组相比提高河蟹一期幼体的成活率13%,5d时与对照组相比变态率增加31%,该菌株有望成为河蟹幼体的益生菌株.对菌株No.7进行形态观察和16SrDNA序列分析,初步鉴定为芽孢杆菌属(Bacillus sp.).     

温湿度对截头堆砂白蚁Cryptotermes domestious(Haviland)生存与发展的关系

温湿度对截头堆砂白蚁生存与繁殖发展有密切关系，在相对湿度80％条件下，温度低于18℃和高于33℃，不利于该种群的存活与发展；在恒温27±1℃条件下，相对湿度低于75％就会影响其生存繁殖。