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Richard Zehner - One of the best experts on this subject based on the ideXlab platform.
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dating pupae of the blow fly calliphora vicina robineau desvoidy 1830 diptera calliphoridae for post mortem Interval estimation validation of molecular age markers
Genes, 2018Co-Authors: Barbara Karolina Zajac, Jens Amendt, Marcel A Verhoff, Richard ZehnerAbstract:Determining the age of juvenile blow flies is one of the key tasks of forensic entomology when providing evidence for the minimum post mortem Interval. While the age determination of blow fly larvae is well established using morphological parameters, the current study focuses on molecular methods for estimating the age of blow flies during the metamorphosis in the pupal stage, which lasts about half the total juvenile development. It has already been demonstrated in several studies that the intraspecific variance in expression of so far used genes in blow flies is often too high to assign a certain expression level to a distinct age, leading to an inaccurate prediction. To overcome this problem, we previously identified new markers, which show a very sharp age dependent expression course during pupal development of the forensically-important blow fly Calliphora vicina Robineau–Desvoidy 1830 (Diptera: Calliphoridae) by analyzing massive parallel sequencing (MPS) generated transcriptome data. We initially designed and validated two quantitative polymerase chain reaction (qPCR) assays for each of 15 defined pupal ages representing a daily progress during the total pupal development if grown at 17 °C. We also investigated whether the performance of these assays is affected by the ambient temperature, when rearing pupae of C. vicina at three different constant temperatures—namely 17 °C, 20 °C and 25 °C. A temperature dependency of the performance could not be observed, except for one marker. Hence, for each of the defined development landmarks, we can present gene expression profiles of one to two markers defining the mentioned progress in development.
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de novo transcriptome analysis and highly sensitive digital gene expression profiling of calliphora vicina diptera calliphoridae pupae using mace massive analysis of cdna ends
Forensic Science International-genetics, 2015Co-Authors: Barbara Karolina Zajac, Jens Amendt, R Horres, M A Verhoff, Richard ZehnerAbstract:Determining a Post-Mortem Interval using the weight or length of blow fly larvae to calculate the insect's age is well established. However, to date, there are only a handful studies dealing with age estimation of blow fly pupae, in which weight or length cannot be used as a relevant parameter. The analysis of genetic markers, which indicate a certain developmental stage, can extend the period for a successful Post-Mortem Interval determination. In order to break new ground in the field of age determination of forensic relevant blow flies, we performed a de novo transcriptome analysis of Calliphora vicina pupae at 15 different developmental stages. Obtained data serve as base to establish molecular age determination techniques. We used a new, deeper, and more cost-effective digital gene expression profiling method called MACE (Massive Analysis of cDNA Ends). We generated 15 libraries out of 15 developmental stages, with 3-8 million reads per library. In total, 53,539 distinct transcripts were detected, and 7548 were annotated to known insect genes. The analysis provides high-resolution gene expression profiles of all covered transcripts, which were used to identify differentially expressed genetic markers as candidates for a molecular age estimation of C. vicina pupae. Moreover, the analysis allows insights into gene activity of pupal development and the relationship between different genes interesting for insect development in general.
Jens Amendt - One of the best experts on this subject based on the ideXlab platform.
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dating pupae of the blow fly calliphora vicina robineau desvoidy 1830 diptera calliphoridae for post mortem Interval estimation validation of molecular age markers
Genes, 2018Co-Authors: Barbara Karolina Zajac, Jens Amendt, Marcel A Verhoff, Richard ZehnerAbstract:Determining the age of juvenile blow flies is one of the key tasks of forensic entomology when providing evidence for the minimum post mortem Interval. While the age determination of blow fly larvae is well established using morphological parameters, the current study focuses on molecular methods for estimating the age of blow flies during the metamorphosis in the pupal stage, which lasts about half the total juvenile development. It has already been demonstrated in several studies that the intraspecific variance in expression of so far used genes in blow flies is often too high to assign a certain expression level to a distinct age, leading to an inaccurate prediction. To overcome this problem, we previously identified new markers, which show a very sharp age dependent expression course during pupal development of the forensically-important blow fly Calliphora vicina Robineau–Desvoidy 1830 (Diptera: Calliphoridae) by analyzing massive parallel sequencing (MPS) generated transcriptome data. We initially designed and validated two quantitative polymerase chain reaction (qPCR) assays for each of 15 defined pupal ages representing a daily progress during the total pupal development if grown at 17 °C. We also investigated whether the performance of these assays is affected by the ambient temperature, when rearing pupae of C. vicina at three different constant temperatures—namely 17 °C, 20 °C and 25 °C. A temperature dependency of the performance could not be observed, except for one marker. Hence, for each of the defined development landmarks, we can present gene expression profiles of one to two markers defining the mentioned progress in development.
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de novo transcriptome analysis and highly sensitive digital gene expression profiling of calliphora vicina diptera calliphoridae pupae using mace massive analysis of cdna ends
Forensic Science International-genetics, 2015Co-Authors: Barbara Karolina Zajac, Jens Amendt, R Horres, M A Verhoff, Richard ZehnerAbstract:Determining a Post-Mortem Interval using the weight or length of blow fly larvae to calculate the insect's age is well established. However, to date, there are only a handful studies dealing with age estimation of blow fly pupae, in which weight or length cannot be used as a relevant parameter. The analysis of genetic markers, which indicate a certain developmental stage, can extend the period for a successful Post-Mortem Interval determination. In order to break new ground in the field of age determination of forensic relevant blow flies, we performed a de novo transcriptome analysis of Calliphora vicina pupae at 15 different developmental stages. Obtained data serve as base to establish molecular age determination techniques. We used a new, deeper, and more cost-effective digital gene expression profiling method called MACE (Massive Analysis of cDNA Ends). We generated 15 libraries out of 15 developmental stages, with 3-8 million reads per library. In total, 53,539 distinct transcripts were detected, and 7548 were annotated to known insect genes. The analysis provides high-resolution gene expression profiles of all covered transcripts, which were used to identify differentially expressed genetic markers as candidates for a molecular age estimation of C. vicina pupae. Moreover, the analysis allows insights into gene activity of pupal development and the relationship between different genes interesting for insect development in general.
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effect of different post feeding Intervals on the total time of development of the blowfly lucilia sericata diptera calliphoridae
Forensic Science International, 2012Co-Authors: Madeleine Mai, Jens AmendtAbstract:Abstract By estimating the age of the immature stages of flies developing on a corpse, forensic entomologists are able to establish the minimum Post-Mortem Interval. Blowflies, which are the first and most important colonizers, usually leave the cadaver at the end of the last larval stage searching for a pupation site. This period of development is referred as the post-feeding or wandering stage. The characteristics of the ground where the corpse was placed might be of notable importance for the post-feeding dispersal time: For pupariation the larvae prefer an environment protected from light and predators and may have a longer dispersal time in order to reach an appropriate pupation site. Hence, the dispersal time can vary and may influence the total time of development which may lead to an erroneous calculation of the Post-Mortem Interval. This study investigates the effect of various post-feeding time Intervals on the development of the blowfly Lucilia sericata at a temperature of 25 °C. As larvae reached the post-feeding stage a pupariation substrate was offered at 0 and after 12, 24 and 48 h. Only the larvae with a dispersal time of 24 h (total time of development 325.2 h; median) and 48 h (total time of development 347.7 h; median) showed a significantly longer total development time compared to the control group (total time of development 318.4 h; median). The mortality rate did not differ between groups; however the flies that emerged from the group with a dispersal of 48 h were significantly smaller indicating increased energy consumption during dispersal. The results of this study indicate that a prolonged post-feeding stage could increase the total developmental time of L. sericata which should be taken into consideration when interpreting entomological findings. The need for a serious examination of current rearing practices in forensic entomology laboratories is indicated because reference data sets for the time of development are usually produced by offering the post-feeding stage a substrate for pupariation immediately.
Barbara Karolina Zajac - One of the best experts on this subject based on the ideXlab platform.
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dating pupae of the blow fly calliphora vicina robineau desvoidy 1830 diptera calliphoridae for post mortem Interval estimation validation of molecular age markers
Genes, 2018Co-Authors: Barbara Karolina Zajac, Jens Amendt, Marcel A Verhoff, Richard ZehnerAbstract:Determining the age of juvenile blow flies is one of the key tasks of forensic entomology when providing evidence for the minimum post mortem Interval. While the age determination of blow fly larvae is well established using morphological parameters, the current study focuses on molecular methods for estimating the age of blow flies during the metamorphosis in the pupal stage, which lasts about half the total juvenile development. It has already been demonstrated in several studies that the intraspecific variance in expression of so far used genes in blow flies is often too high to assign a certain expression level to a distinct age, leading to an inaccurate prediction. To overcome this problem, we previously identified new markers, which show a very sharp age dependent expression course during pupal development of the forensically-important blow fly Calliphora vicina Robineau–Desvoidy 1830 (Diptera: Calliphoridae) by analyzing massive parallel sequencing (MPS) generated transcriptome data. We initially designed and validated two quantitative polymerase chain reaction (qPCR) assays for each of 15 defined pupal ages representing a daily progress during the total pupal development if grown at 17 °C. We also investigated whether the performance of these assays is affected by the ambient temperature, when rearing pupae of C. vicina at three different constant temperatures—namely 17 °C, 20 °C and 25 °C. A temperature dependency of the performance could not be observed, except for one marker. Hence, for each of the defined development landmarks, we can present gene expression profiles of one to two markers defining the mentioned progress in development.
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de novo transcriptome analysis and highly sensitive digital gene expression profiling of calliphora vicina diptera calliphoridae pupae using mace massive analysis of cdna ends
Forensic Science International-genetics, 2015Co-Authors: Barbara Karolina Zajac, Jens Amendt, R Horres, M A Verhoff, Richard ZehnerAbstract:Determining a Post-Mortem Interval using the weight or length of blow fly larvae to calculate the insect's age is well established. However, to date, there are only a handful studies dealing with age estimation of blow fly pupae, in which weight or length cannot be used as a relevant parameter. The analysis of genetic markers, which indicate a certain developmental stage, can extend the period for a successful Post-Mortem Interval determination. In order to break new ground in the field of age determination of forensic relevant blow flies, we performed a de novo transcriptome analysis of Calliphora vicina pupae at 15 different developmental stages. Obtained data serve as base to establish molecular age determination techniques. We used a new, deeper, and more cost-effective digital gene expression profiling method called MACE (Massive Analysis of cDNA Ends). We generated 15 libraries out of 15 developmental stages, with 3-8 million reads per library. In total, 53,539 distinct transcripts were detected, and 7548 were annotated to known insect genes. The analysis provides high-resolution gene expression profiles of all covered transcripts, which were used to identify differentially expressed genetic markers as candidates for a molecular age estimation of C. vicina pupae. Moreover, the analysis allows insights into gene activity of pupal development and the relationship between different genes interesting for insect development in general.
Sherah L Vanlaerhoven - One of the best experts on this subject based on the ideXlab platform.
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impact of comingled heterospecific assemblages on developmentally based estimates of the post mortem Interval a study with lucilia sericata meigen phormia regina meigen and calliphora vicina robineau desvoidy diptera calliphoridae
Insects, 2021Co-Authors: Krystal Rae Hans, Sherah L VanlaerhovenAbstract:Estimates of the minimum Post-Mortem Interval (mPMI) using the development rate of blow flies (Diptera: Calliphoridae) are common in modern forensic entomology casework. These estimates are based on single species developing in the absence of heterospecific interactions. Yet, in real-world situations, it is not uncommon to have 2 or more blow fly species developing on a body. Species interactions have the potential to change the acceptance of resources as suitable for oviposition, the timing of oviposition, growth rate, size and development time of immature stages, as well as impacting the survival of immature stages to reach adult. This study measured larval development and growth rate of the blow flies Lucilia sericata (Meigen, 1826), Phormia regina (Meigen, 1826) and Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) over five constant temperatures (15, 20, 25, 30, 35 °C), in the presence of conspecifics or two-species heterospecific assemblages. Temperature and species treatment interacted such that L. sericata larvae gained mass more rapidly when in the presence of P. regina at 20 and 30 °C, however only developed faster at first instar. At later stages, the presence of P. regina slowed development of L. sericata immatures. Development time of C. vicina immatures was not affected by the presence of P. regina, however larvae gained mass more slowly. Development time of P. regina immatures was faster in the presence of either L. sericata or C. vicina until third instar, at which point, the presence of L. sericata was neutral whereas C. vicina negatively impacted development time. Phormia regina larvae gained mass more rapidly in the presence of L. sericata at 20 °C but were negatively impacted at 25 °C by the presence of either L. sericata or C. vicina. The results of this study indicate that metrics such as development time or larval mass used for estimating mPMI with blow flies are impacted by the presence of comingled heterospecific blow fly assemblages. As the effects of heterospecific assemblages are not uniformly positive or negative between stages, temperatures or species combinations, more research into these effects is vital. Until then, caution should be used when estimating mPMI in cases with multiple blow fly species interacting on a body.
Bryan S. Turner - One of the best experts on this subject based on the ideXlab platform.
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post feeding larval behaviour in the blowfly calliphora vicina effects on post mortem Interval estimates
Forensic Science International, 2008Co-Authors: Sophie Arnott, Bryan S. TurnerAbstract:Using the rate of development of blowflies colonising a corpse, accumulated degree hours (ADH), or days (ADD), is an established method used by forensic entomologists to estimate the Post-Mortem Interval (PMI). Derived from laboratory experiments, their application to field situations needs care. This study examines the effect of the post-feeding larval dispersal time on the ADH and therefore the PMI estimate. Post-feeding dispersal in blowfly larvae is typically very short in the laboratory but may extend for hours or days in the field, whilst the larvae try to find a suitable pupariation site. Increases in total ADH (to adult eclosion), due to time spent dispersing, are not simply equal to the dispersal time. The pupal period is increased by approximately 2 times the length of the dispersal period. In practice, this can introduce over-estimation errors in the PMI estimate of between 1 and 2 days if the total ADH calculations do not consider the possibility of an extended larval dispersal period.
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the effects of larval crowding and food type on the size and development of the blowfly calliphora vomitoria
Forensic Science International, 2006Co-Authors: Sarah Ireland, Bryan S. TurnerAbstract:Abstract The use of entomological evidence in the estimation of the post mortem Interval (PMI) often depends on the size and developmental stage of blowfly larvae collected from a corpse. Therefore, factors which can have an effect on the larval size and growth rate can have implications for reliable PMI determinations. This study explores the competitive effects of larval overcrowding on Calliphora vomitoria reared on three different pig tissues – liver, brain and muscle. The competitive feeding environment within the more crowded larval cultures resulted in increased development rates and the production of undersized larvae and adults. Variation in the extent of these effects was observed on each of the three body tissues, highlighting the importance of documenting the positions from which entomological evidence is recovered from a corpse.