590 Tiere (Zoologie)
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Forensic entomology
(2017)
For many members of the forensic community, insects still have an exotic status. This may be one reason why forensic entomology, the analysis of insect evidence for forensic and legal purposes, has not yet achieved the significance it deserves in forensic sciences. The present special issue may help to change that. ...
After initial formation, the heart tube grows by addition of second heart field progenitor cells to its poles. The transcription factor Isl1 is expressed in the entire second heart field in mouse, and Isl1-deficient mouse embryos show defects in arterial and venous pole development. The expression of Isl1 is conserved in zebrafish cardiac progenitors; however, Isl1 is required for cardiomyocyte differentiation only at the venous pole. Here we show that Isl1 homologues are expressed in specific patterns in the developing zebrafish heart and play distinct roles during cardiac morphogenesis. In zebrafish, isl2a mutants show defects in cardiac looping, whereas isl2b is required for arterial pole development. Moreover, Isl2b controls the expression of key cardiac transcription factors including mef2ca, mef2cb, hand2 and tbx20. The specific roles of individual Islet family members in the development of distinct regions of the zebrafish heart renders this system particularly well-suited for dissecting Islet-dependent gene regulatory networks controlling the behavior and function of second heart field progenitors in distinct steps of cardiac development.
Species identification of adult African blowflies (Diptera: Calliphoridae) of forensic importance
(2017)
Necrophagous blowflies can provide an excellent source of evidence for forensic entomologists and are also relevant to problems in public health, medicine, and animal health. However, access to useful information about these blowflies is constrained by the need to correctly identify the flies, and the poor availability of reliable, accessible identification tools is a serious obstacle to the development of forensic entomology in the majority of African countries. In response to this need, a high-quality key to the adults of all species of forensically relevant blowflies of Africa has been prepared, drawing on high-quality entomological materials and modern focus-stacking photomicroscopy. This new key can be easily applied by investigators inexperienced in the taxonomy of blowflies and is made available through a highly accessible online platform. Problematic diagnostic characters used in previous keys are discussed.
Background: Correct species identification of blow flies is a crucial step for understanding their biology, which can be used not only for designing fly control programs, but also to determine the minimum time since death. Identification techniques are usually based on morphological and molecular characters. However, the use of classical morphology requires experienced entomologists for correct identification; while molecular techniques rely on a sound laboratory expertise and remain ambiguous for certain taxa. Landmark-based geometric morphometric analysis of insect wings has been extensively applied in species identification. However, few wing morphometric analyses of blow fly species have been published.
Methods: We applied a landmark-based geometric morphometric analysis of wings for species identification of 12 medically and forensically important blow fly species of Thailand. Nineteen landmarks of each right wing of 372 specimens were digitised. Variation in wing size and wing shape was analysed and evaluated for allometric effects. The latter confirmed the influence of size on the shape differences between species and sexes. Wing shape variation among genera and species were analysed using canonical variates analysis followed by a cross-validation test.
Results: Wing size was not suitable for species discrimination, whereas wing shape can be a useful tool to separate taxa on both, genus and species level depending on the analysed taxa. It appeared to be highly reliable, especially for classifying Chrysomya species, but less robust for a species discrimination in the genera Lucilia and Hemipyrellia. Allometry did not affect species separation but had an impact on sexual shape dimorphism.
Conclusions: A landmark-based geometric morphometric analysis of wings is a useful additional method for species discrimination. It is a simple, reliable and inexpensive method, but it can be time-consuming locating the landmarks for a large scale study and requires non-damaged wings for analysis.