69 research outputs found
Transcriptome profiling of ontogeny in the acridid grasshopper Chorthippus biguttulus
Acridid grasshoppers (Orthoptera:Acrididae) are widely used model organisms
for developmental, evolutionary, and neurobiological research. Although there
has been recent influx of orthopteran transcriptomic resources, many use
pooled ontogenetic stages obscuring information about changes in gene
expression during development. Here we developed a de novo transcriptome
spanning 7 stages in the life cycle of the acridid grasshopper Chorthippus
biguttulus. Samples from different stages encompassing embryonic development
through adults were used for transcriptomic profiling, revealing patterns of
differential gene expression that highlight processes in the different life
stages. These patterns were validated with semi-quantitative RT-PCR. Embryonic
development showed a strongly differentiated expression pattern compared to
all of the other stages and genes upregulated in this stage were involved in
signaling, cellular differentiation, and organ development. Our study is one
of the first to examine gene expression during post-embryonic development in a
hemimetabolous insect and we found that only the fourth and fifth instars had
clusters of genes upregulated during these stages. These genes are involved in
various processes ranging from synthesis of biogenic amines to chitin binding.
These observations indicate that post-embryonic ontogeny is not a continuous
process and that some instars are differentiated. Finally, genes upregulated
in the imago were generally involved in aging and immunity. Our study
highlights the importance of looking at ontogeny as a whole and indicates
promising directions for future research in orthopteran development
Toxic but Drank: Gustatory Aversive Compounds Induce Post-ingestional Malaise in Harnessed Honeybees
BACKGROUND: Deterrent substances produced by plants are relevant due to their potential toxicity. The fact that most of these substances have an unpalatable taste for humans and other mammals contrasts with the fact that honeybees do not reject them in the range of concentrations in which these compounds are present in flower nectars. Here we asked whether honeybees detect and ingest deterrent substances and whether these substances are really toxic to them. RESULTS: We show that pairing aversive substances with an odor retards learning of this odor when it is subsequently paired with sucrose. Harnessed honeybees in the laboratory ingest without reluctance a considerable volume (20 µl) of various aversive substances, even if some of them induce significant post-ingestional mortality. These substances do not seem, therefore, to be unpalatable to harnessed bees but induce a malaise-like state that in some cases results in death. Consistently with this finding, bees learning that one odor is associated with sugar, and experiencing in a subsequent phase that the sugar was paired with 20 µl of an aversive substance (devaluation phase), respond less than control bees to the odor and the sugar. Such stimulus devaluation can be accounted for by the malaise-like state induced by the aversive substances. CONCLUSION: Our results indicate that substances that taste bitter to humans as well as concentrated saline solutions base their aversive effect on the physiological consequences that their ingestion generates in harnessed bees rather than on an unpalatable taste. This conclusion is only valid for harnessed bees in the laboratory as freely-moving bees might react differently to aversive compounds could actively reject aversive substances. Our results open a new possibility to study conditioned taste aversion based on post-ingestional malaise and thus broaden the spectrum of aversive learning protocols available in honeybees
Integrated Operational Taxonomic Units (IOTUs) in Echolocating Bats: A Bridge between Molecular and Traditional Taxonomy
Background: Nowadays, molecular techniques are widespread tools for the identification of biological entities. However,
until very few years ago, their application to taxonomy provoked intense debates between traditional and molecular
taxonomists. To prevent every kind of disagreement, it is essential to standardize taxonomic definitions. Along these lines,
we introduced the concept of Integrated Operational Taxonomic Unit (IOTU). IOTUs come from the concept of Operational
Taxonomic Unit (OTU) and paralleled the Molecular Operational Taxonomic Unit (MOTU). The latter is largely used as
a standard in many molecular-based works (even if not always explicitly formalized). However, while MOTUs are assigned
solely on molecular variation criteria, IOTUs are identified from patterns of molecular variation that are supported by at least
one more taxonomic characteristic.
Methodology/Principal Findings: We tested the use of IOTUs on the widest DNA barcoding dataset of Italian echolocating
bats species ever assembled (i.e. 31 species, 209 samples). We identified 31 molecular entities, 26 of which corresponded to
the morphologically assigned species, two MOTUs and three IOTUs. Interestingly, we found three IOTUs in Myotis nattereri,
one of which is a newly described lineage found only in central and southern Italy. In addition, we found a level of molecular
variability within four vespertilionid species deserving further analyses. According to our scheme two of them (i.e.
M. bechsteinii and Plecotus auritus) should be ranked as unconfirmed candidate species (UCS).
Conclusions/Significance: From a systematic point of view, IOTUs are more informative than the general concept of OTUs
and the more recent MOTUs. According to information content, IOTUs are closer to species, although it is important to
underline that IOTUs are not species. Overall, the use of a more precise panel of taxonomic entities increases the clarity in
the systematic field and has the potential to fill the gaps between modern and traditional taxonomy
Die Verbreitung einiger Fledermausarten in Griechenland
Volume: 41Start Page: 9End Page: 2
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