Cost effective,robust, and reliable coupled separation techniques for the identification and quantification of phospholipids in complex biological matrices: Application to insects

The quantification of phospholipid classes and the determination of their molecular structures are crucial in physiological and medical studies. This paper's target analytes are cell membrane phospholipids, which play an important role in the seasonal acclimation processes of poikilothermic organisms. We introduce a set of simple and cost‐effective analytical methods that enable efficient characterization and quantification of particular phospholipid classes and the identification and relative distribution of the individual phospholipid species. The analytical approach involves solid‐phase extraction and high‐performance thin‐layer chromatography, which facilitate the separation of particular lipid classes. The obtained fractions are further transesterified to fatty acid methyl esters and subjected to gas chromatography coupled to flame ionization detection, which enables the determination of the position of double bonds. Phospholipid species separation is achieved by high‐performance liquid chromatography with mass spectrometry, which gives information about the headgroup moiety and attached fatty acids. The total content of each phospholipids class is assessed by phosphorus determination by UV spectrophotometry. The simultaneous analysis of phosphorus, fatty acid residues, and phospholipid species provides detailed information about phospholipid composition. Evaluation of these coupled methods was achieved by application to an insect model, Pyrrhocoris apterus. High correlation was observed between fatty acid compositions as determined by gas chromatography and high‐performance liquid chromatography analysis.     

Insect wings as retrospective/accidental/forensic dosimeters: An optically stimulated luminescence investigation

Estimation of the radiation released during nuclear accidents or radiological terrorist events is imperative for the prediction of health effects following such an exposure. In addition, in several cases there is a need to identify the prior presence of radioactive materials at buildings or sites (nuclear forensics). To this direction, several materials have been the research object of numerous studies the last decade in an attempt to identify potentially new retrospective/accidental/forensic dosimeters.However, the studies targeting biological materials are limited and their majority is mainly focused on the luminescence behavior of human biological material. Consequently, the use of such materials in retrospective dosimetry presumes the exposure of humans in the radiation field. The present work constitutes the first attempt to seek non-human biological materials, which can be found in nature in abundance or in/on other living organisms. To this end, the present work investigates the basic optically stimulated luminescence behavior of insect wings, which exhibit several advantages compared to other materials. Insects are ubiquitous, have a short life expectancy and exhibit a low decomposition rate after their death.Findings of the present study are encouraging towards the potential use of insects' wings at retrospective/accidental/forensic dosimetry, since they exhibit linear OSL response over a wide dose range and imperceptible loss of signal several days after their irradiation when they are kept in dark. On the other hand, the calculated lower detection limit is not low enough to allow their use as emergency dosimeters when individuals are exposed to non-lethal doses. In addition, wings exhibit strong optical fading when they are exposed to daylight and thus special care should be taken during the sampling procedure in order to use the wings as accidental/forensic dosimeters, by seeking (dead) insects in dark places, such as behind furniture, equipment or in air-shafts.Finally, a new single aliquot measurement protocol is also successfully tested on the wings for the dose estimation, while further work is in progress to validate it on other (heat-sensitive) materials as well.     

Sample preparation for the chromatographic determination of ecdysteroids using solid-phase extraction methods

The ecdysteroids are hormones widely distributed in insects and crustaceans, where they are involved in the regulation of moulting. Methods of sample preparation based on solid-phase extraction of the ecdysteroids from biological samples for subsequent chromatographic analysis are reviewed. Most methods use an initial partition of the sample (or extract) between water or aqueous methanol with a non-polar solvent to remove lipids. The aqueous portion is applied to a cartridge containing C₁₈-bonded silica gel. Removal of polar impurities is then effected, followed by recovery of the ecdysteroids from the cartridge and chromatographic analysis. Results are given for the use of phenylboronic acid (PBA) bonded to silica gel as a means of obtaining a much more specific method of extraction. The PBA phase was shown to have a high affinity for ecdysteroids containing a 20,22-cis-diol but not for compounds possessing only a 2,3-cis-diol.     

Preparation of small-scale samples from insect for chromatography

Techniques are available for the gas chromatography of very small samples of insect pheromones and defensive secretions by which the diluting and contaminating effects of solvents are avoided. Samples obtained in many ways can be sealed in fine glass capillaries, heated and crushed on-column to give quantitative high-resolution chromatograms. Reactions can be carried out in a micro-reactor and the reaction products obtained in a very small volume (5 μl) for chromatography without evaporation.     

Identification and synthesis of new bicyclic acetals from caddisflies (Trichoptera)

As shown by synthesis and enantioselective gas chromatography, males and females of the caddisfly species Potamophylax latipennis and Potamophylax cingulatus produce (1R,3S,5S,7S)-1-ethyl-3,5,7-trimethyl-2,8-dioxabicyclo[3.2.1]octane, while Glyphotaelius pellucidus produces 1,3-diethyl-4,6-dimethyl-2,7-dioxabicyclo[2.2.1]heptane, having either the (1S,3S,4R,6S) or (1R,3R,4S,6S)-configuration. As shown by electrophysiological investigations, the compounds are perceived by the antennae of both sexes.     

Differential vitellin polypeptide processing in insect embryos

This review focuses on the current status of knowledge regarding the process of vitellogenin (Vg) uptake and vitellin (Vt) storage in insect oocytes. We also consider the overall morphology of the yolk sac as an embryonic organ allowing for both temporal and spatial differentiation of yolk degradation to provide the primary food supply for the embryo. In this context we describe the evidence that demonstrates the occurrence of Vt polypeptide processing and how it may be affected by maternally derived proteases stored in the yolk granules and by the ubiquitin–proteasome system in the cytosol. The extent of Vt polypeptide processing induced by these proteases will be correlated with the structural modifications affecting yolk granules and vitellophages in developing insect embryos. To accomplish these goals the ultrastructural and cytochemical composition of yolk granules during vitellogenesis and embryogenesis will be reviewed. Last but not the least, our current understanding of the role played by acidification of yolk granules in the activation of maternally derived proteases will also be examined.     

昆虫中RNA介导的转座因子

在昆虫中编码反转录酶的转座因子分为二大类：含长末端重复(LTRs)和不含长末端重复的转座因子.LTRs反转录转座子是具有两侧长正向重复末端序列的片段,中间部分序列包括一个或一个以上的ORFs(开放性阅读框架),其编码转座因子复制和转座所必需的蛋白质;包括Gypsy-Ty3家族、Copia-Ty1家族和Pao因子等.不含长末端重复的转座因子有时称为反转座子,能编码反转录酶但缺乏整合酶;包括I、F、G、Jockey、Doc和Het-A等因子.本文简介了有关昆虫基因组中转座因子的主要家族及近年来的研究     

SORTING SYSTEMS BASED ON OPTICAL METHODS FOR DETECTING AND REMOVING SEEDS INFESTED INTERNALLY BY INSECTS OR FUNGI: A REVIEW*

Sorting systems based on optical methods have the potential to rapidly detect and physically remove seeds severely contaminated by fungi, or infested internally by insect larvae or pupae. Thus, the literature on sorting systems based on optical methods for detecting and sorting seeds with these attributes was reviewed. Sorting indices based on wavelengths useful for detecting these attributes were emphasized. Surface characteristics of seeds, like discoloration caused by fungi, are generally detectable in the visible range of the electromagnetic spectrum, whereas internal attributes are detectable in the near-infrared range. The spectral differences between sound and infested seeds are usually subtle, but full-spectrum and two-wavelength classification models have succeeded in detecting and classifying seeds based on these attributes. For high sorting accuracies, wavelength identification and proper selection of a sorting criterion are important. Color, chitin, ergosterol, or hydrolysis of triglycerides have been identified as indicators of seed fungal contamination whereas chitin, protein, phenolic compounds, or changes in starch have been useful indicators of internal insects in seeds.