Papers by Heinrich Dircksen
List of prepropeptides. List of prepropeptides (precursor sequences) from 24 non-pterygote hexapo... more List of prepropeptides. List of prepropeptides (precursor sequences) from 24 non-pterygote hexapod species (Protura, Diplura, Collembola, Archaeognatha, Zygentoma), 2 crustacean species and 3 myriapod species; these data are deduced from transcriptome sequence assemblies obtained from the 1KITE project. The majority of prepropeptides contain neuropeptides with known receptors in insects; receptors are not known for the products of the elevenin, efl-amide, and orcokinin genes. In addition, currently available and critically revised sequences from the well-studied water flea Daphnia pulex (Branchiopoda) and fruit fly Drosophila melanogaster (Diptera) are listed. The genomes of these species were repeatedly screened for neuropeptide genes. Predicted signal peptides (highlighted in grey), amidation signals (bold), cleavage signals (italics, bold), splice variants (a, b), and supposed bioactive mature peptides (underscored) are indicated. Incomplete sequences are indicated with “…”. In some cases, sequences were reconstructed through the fusion of different database entries, or by including sequences from 3'-UTR regions encoding putative coding exons of a different splice form (see ITP). For a few Thermobia sequences, PCR and RACE experiments were conducted (Derst C, Blaser M, Predel R; unpublished results) to obtain full-length sequences; this information is given subsequent to accession or JGI numbers. (DOC 1182 kb)
Assignment of precursor sequences listed in Additional file 1 (only sequences not released in NCB... more Assignment of precursor sequences listed in Additional file 1 (only sequences not released in NCBI yet). The original sequences from assembly version 1 will be available upon request. (XLS 62 kb)
Social Science Research Network, 2022
Cell and Tissue Research, Jul 1, 1991
By use of an antiserum against the crustacean cardioactive peptide (CCAP) several types of bilate... more By use of an antiserum against the crustacean cardioactive peptide (CCAP) several types of bilaterally symmetrical neurons have been mapped quantitatively in the ventral nerve cord and in the brain of the meal beetle, Tenebrio molitor. The general architecture of these neurons was reconstructed from peroxidase-antiperoxidase-labelled whole-mount preparations. From the subesophageal to the seventh abdominal ganglia two types of neurons
Cell and Tissue Research, Feb 1, 1995
... superior median protocerebrum. The contralateral axonal projections through commissure AC IV ... more ... superior median protocerebrum. The contralateral axonal projections through commissure AC IV are easily recog-nized in whole-mounts and sections (Figs. 6a, b, 7a ... central body (Fig. 10a, c, e, f). cPlo-Neurons. The cPl0-neurons ...
Journal of comparative neurology, Dec 15, 2021
The primary olfactory centers of metazoans as diverse as arthropods and mammals consist of an arr... more The primary olfactory centers of metazoans as diverse as arthropods and mammals consist of an array of fields of dense synaptic neuropil, the olfactory glomeruli. However, the neurochemical structure of crustacean olfactory glomeruli is largely understudied when compared to the insects. We analyzed the glomerular architecture in selected species of hermit crabs using immunohistochemistry against presynaptic proteins, the neuropeptides orcokinin, RFamide and allatostatin, and the biogenic amine serotonin. Our study reveals an unexpected level of structural complexity, unmatched by what is found in the insect olfactory glomeruli. Peptidergic and aminergic interneurons provide the structural basis for a regionalization of the crustacean glomeruli into longitudinal and concentric compartments. Our data suggest that local olfactory interneurons take a central computational role in modulating the information transfer from olfactory sensory neurons to projection neurons within the glomeruli. Furthermore, we found yet unknown neuronal elements mediating lateral inhibitory interactions across the glomerular array that may play a central role in modulating the transfer of sensory input to the output neurons through presynaptic inhibition. Our study is another step in understanding the function of crustacean olfactory glomeruli as highly complex units of local olfactory processing.
Frontiers in Physiology, Sep 15, 2022
Editorial on the Research Topic Crustacean reproductive physiology and its applications Crustacea... more Editorial on the Research Topic Crustacean reproductive physiology and its applications Crustacea constitute an important taxonomic group in aquatic ecosystems and form an important sector of aquaculture industry. Novelties in studies on crustacean reproductive physiology help shedding new lights on deeper understanding of the mechanisms of sex determination and differentiation of crustaceans. The application of established and innovative techniques based on such knowledge will contribute significantly to progress in the crustacean aquaculture industry. The objective of this Special Issue was to provide a forum for researchers to report upon their cutting-edge research in Crustacean Reproductive Physiology and its Applications. This Research Topic comprises ten original research articles. In particular, in this Special Issue, the roles of several neuropeptides in regulating crustacean reproduction have been reported for several decapod crustacean species of importance for aquaculture. In the giant freshwater prawn Macrobrachium rosenbergii, Ao et al. revealed that recombinant neuroparsins NP1 and NP2 stimulate expression of the vitellogenin (Vg) gene, and silencing of NP1 and NP2 genes suppresses Vg, Vg receptor, and CyclinB gene expressions. In the mud crab Scylla olivacea, double strand RNA technology (dsRNA) was used to inhibit transcription of vitellogenesis-inhibiting hormone (VIH), i.e. dsRNA-VIH accelerates ovarian maturation by increasing hemolymph vitellogenin concentration and the gonadosomatic index (Duangprom et al.). In the swimming crab Portunus trituberculatus, Tu et al. confirmed via in vitro experiments that the expressions of Vg, VgR, cyclinB, and Cdc2 in ovary explants is induced by synthetic corazonin, but reduced by corazonin receptor dsRNA. Tu et al. also suggested that the corazonin/corazonin receptor signaling system stimulates the biosynthesis of ecdysteroids. It is known that crustacean female sex hormone (CFSH) plays a pivotal role in the development of secondary sex characteristics in dioecious species. The roles of CFSH were reported for the first time in female reproductive
Zoological Science, Feb 15, 1994
ABSTRACT Actions of neuropeptides can be assayed more conveniently at peripheral targets than in ... more ABSTRACT Actions of neuropeptides can be assayed more conveniently at peripheral targets than in the central nervous system. To draw attention to possible peripheral targets for studies of peptide action, this review focuses on neuropeptides in the neurosecretory and efferent systems of the thoracic and abdominal ganglia of insects, with special emphasis on blowflies (Calliphoridae), under the following headings: organization of insect neurosecretory systems; neuropeptides demonstrated in the thoracic and abdominal ganglia; general organization of thoracic abdominal neurosecretory systems and neurohaemal organs and release sites; neuropeptides in the neurohaemal area in the dorsal neural sheath of the blowfly thoracic-abdominal ganglion; peptides in the neurohaemal area in the pericardial septum of the blowfly; varicose axons in the neural sheath of peripheral nerves; neuropeptides in efferent neurons to the blowfly hindgut; and larval neurohaemal organs and peripheral release sites in blowflies.
Toxins, Dec 8, 2018
The non-proteinogenic amino acid beta-methyl-amino-L-alanine (BMAA) is a neurotoxin produced by c... more The non-proteinogenic amino acid beta-methyl-amino-L-alanine (BMAA) is a neurotoxin produced by cyanobacteria. BMAA accumulation in the brain of animals via biomagnification along the food web can contribute to the development of neurodegenerative diseases such as Amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC), the latter being associated with a loss of dopaminergic neurons. Daphnia magna is an important microcrustacean zooplankton species that plays a key role in aquatic food webs, and BMAA-producing cyanobacteria often form part of their diet. Here, we tested the effects of BMAA on putative neurodegeneration of newly identified specific dopaminergic neurons in the optic ganglia/brain complex of D. magna using quantitative tyrosine-hydroxylase immunohistochemistry and fluorescence cytometry. The dopaminergic system was analysed in fed and starved isogenic D. magna adults incubated under different BMAA concentrations over 4 days. Increased BMAA concentration showed significant decrease in the stainability of dopaminergic neurons of D. magna, with fed animals showing a more extreme loss. Furthermore, higher BMAA concentrations tended to increase offspring mortality during incubation. These results are indicative of ingested BMAA causing neurodegeneration of dopaminergic neurons in D. magna and adversely affecting reproduction. This may imply similar effects of BMAA on known human neurodegenerative diseases involving dopaminergic neurons.
The Journal of Experimental Biology, Oct 1, 2006
BMC Evolutionary Biology, Feb 29, 2016
Background: Neuropeptides are key players in information transfer and act as important regulators... more Background: Neuropeptides are key players in information transfer and act as important regulators of development, growth, metabolism, and reproduction within multi-cellular animal organisms (Metazoa). These short protein-like substances show a high degree of structural variability and are recognized as the most diverse group of messenger molecules. We used transcriptome sequences from the 1KITE (1K Insect Transcriptome Evolution) project to search for neuropeptide coding sequences in 24 species from the non-pterygote hexapod lineages Protura (coneheads), Collembola (springtails), Diplura (two-pronged bristletails), Archaeognatha (jumping bristletails), and Zygentoma (silverfish and firebrats), which are often referred to as "basal" hexapods. Phylogenetically, Protura, Collembola, Diplura, and Archaeognatha are currently placed between Remipedia and Pterygota (winged insects); Zygentoma is the sistergroup of Pterygota. The Remipedia are assumed to be among the closest relatives of all hexapods and belong to the crustaceans. Results: We identified neuropeptide precursor sequences within whole-body transcriptome data from these five hexapod groups and complemented this dataset with homologous sequences from three crustaceans (including Daphnia pulex), three myriapods, and the fruit fly Drosophila melanogaster. Our results indicate that the reported loss of several neuropeptide genes in a number of winged insects, particularly holometabolous insects, is a trend that has occurred within Pterygota. The neuropeptide precursor sequences of the non-pterygote hexapods show numerous amino acid substitutions, gene duplications, variants following alternative splicing, and numbers of paracopies. Nevertheless, most of these features fall within the range of variation known from pterygote insects. However, the capa/pyrokinin genes of non-pterygote hexapods provide an interesting example of rapid evolution, including duplication of a neuropeptide gene encoding different ligands. Conclusions: Our findings delineate a basic pattern of neuropeptide sequences that existed before lineage-specific developments occurred during the evolution of pterygote insects.
The Journal of Experimental Biology, 2019
Whether the character of developmental plasticity is adaptive or non-adaptive has often been a ma... more Whether the character of developmental plasticity is adaptive or non-adaptive has often been a matter of controversy. Although thermal developmental plasticity has been studied in Drosophila for several traits, it is not entirely clear how it affects reproductive fitness. We, therefore, investigated how developmental temperature affects reproductive performance (early fecundity and egg-to-adult viability) of wild-caught Drosophila melanogaster. We tested competing hypotheses on the character of developmental thermal plasticity using a full-factorial design with three developmental and adulthood temperatures within the natural thermal range of this species. To account for potential intraspecific differences, we examined flies from tropical (India) and temperate (Slovakia) climate zones. Our results show that flies from both populations raised at an intermediate developmental temperature (25°C) have comparable or higher early fecundity and fertility at all tested adulthood temperatures, while lower (17°C) or higher developmental temperatures (29°C) did not entail any advantage under the tested thermal regimes. Importantly, the superior thermal performance of flies raised at 25°C is apparent even after taking two traits positively associated with reproductive output into account: body size and ovariole number. Thus, in D. melanogaster, development at a given temperature does not necessarily provide any advantage in this thermal environment in terms of reproductive fitness. Our findings strongly support the optimal developmental temperature hypothesis, which states that in different thermal environments, the highest fitness is achieved when an organism is raised at its optimal developmental temperature.
PLOS Genetics, Aug 23, 2018
Animals need to continuously adjust their water metabolism to the internal and external condition... more Animals need to continuously adjust their water metabolism to the internal and external conditions. Homeostasis of body fluids thus requires tight regulation of water intake and excretion, and a balance between ingestion of water and solid food. Here, we investigated how these processes are coordinated in Drosophila melanogaster. We identified the first thirstpromoting and anti-diuretic hormone of Drosophila, encoded by the gene Ion transport peptide (ITP). This endocrine regulator belongs to the CHH (crustacean hyperglycemic hormone) family of peptide hormones. Using genetic gain-and loss-of-function experiments, we show that ITP signaling acts analogous to the human vasopressin and renin-angiotensin systems; expression of ITP is elevated by dehydration of the fly, and the peptide increases thirst while repressing excretion, promoting thus conservation of water resources. ITP responds to both osmotic and desiccation stress, and dysregulation of ITP signaling compromises the fly's ability to cope with these stressors. In addition to the regulation of thirst and excretion, ITP also suppresses food intake. Altogether, our work identifies ITP as an important endocrine regulator of thirst and excretion, which integrates water homeostasis with feeding of Drosophila.
Biochemical Journal, May 8, 2001
About 24 intrinsic neurosecretory neurons within the pericardial organs (POs) of the crab Carcinu... more About 24 intrinsic neurosecretory neurons within the pericardial organs (POs) of the crab Carcinus maenas produce a novel crustacean hyperglycaemic hormone (CHH)-like peptide (PO-CHH) and two CHH-precursor-related peptides (PO-CPRP I and II) as identified immunochemically and by peptide chemistry. Edman sequencing and MS revealed PO-CHH as a 73 amino acid peptide (8630 Da) with a free C-terminus. PO-CHH and sinus gland CHH (SG-CHH) share an identical N-terminal sequence, positions 1-40, but the remaining sequence, positions 41-73 or 41-72, differs considerably. PO-CHH may have different precursors, as cDNA cloning of PO-derived mRNAs has revealed several similar forms, one exactly encoding the peptide. All PO-CHH cDNAs contain a nucleotide stretch coding for the SG-CHH%"-(' sequence in the 3h-untranslated region (UTR). Cloning of crab testis genomic DNA revealed at least four CHH genes, the structure of which suggest that PO-CHH and SG-CHH arise Abbreviations used : CHH, crustacean hyperglycaemic hormone ; CPRP, CHH-precursor-related peptide ; MALDI-TOF MS, matrix-assisted laser desorption ionization-time-of-flight MS ; MT, medulla terminalis ; TFA, trifluoroacetic acid ; SG, sinus gland ; ITP, ion-transport peptide ; PO, pericardial organ ; Spe-, S-pyridylethylated ; EP-AspN, endoproteinase AspN ; CID, collision-induced dissociation ; RACE, rapid amplification of cDNA ends ; RT-PCR, reverse transcriptase PCR ; MIH, moult-inhibiting hormone ; RP-HPLC, reversed-phase HPLC ; UTR, untranslated region. 1 To whom correspondence should be addressed (e-mail Dircksen!uni-bonn.de). by alternative splicing of precursors and possibly post-transcriptional modification of PO-CHH. The genes encode four exons, separated by three variable introns, encoding part of a signal peptide (exon I), the remaining signal peptide residues, a CPRP, the PO-CHH"-%!\SG-CHH"-%! sequences (exon II), the remaining PO-CHH residues (exon III) and the remaining SG-CHH residues and a 3h-UTR (exon IV). Precursor and gene structures are more closely related to those encoding related insect ion-transport peptides than to penaeid shrimp CHH genes. PO-CHH neither exhibits hyperglycaemic activity in i o, nor does it inhibit Y-organ ecdysteroid synthesis in itro. From the morphology of the neurons it seems likely that novel functions remain to be discovered.
Nahrungsaufnahme beim Pantoffeltier Paramecium caudatum. Versuche zur Phagocytose und Cyclose III.
Journal of Crustacean Biology, Sep 1, 2017
Predators may be exposed to different prey types simultaneously, and so may select certain prey t... more Predators may be exposed to different prey types simultaneously, and so may select certain prey types over others. We examined prey selection, predation rate, and foraging behaviour of the swimming crab Portunus trituberculatus (Miers, 1876) provided with three types of clams, the Manila Ruditapes philippinarum (Adams & Reeve, 1850), bloody Scapharca subcrenata (Lischke, 1896), and hard Meretrix meretrix (Linnaeus, 1758) clams in laboratory experiments. When provided will all three possible prey simultaneously, crabs exhibited higher preference for R. philippinarum over S. subcrenata and M. meretrix (Chesson's selectivity index; P = 0.003). In the single-prey experiments, predation rates were significantly higher on R. philippinarum and S. subcrenata than on M. meretrix (P = 0.002). Video analysis revealed that prey type significantly affected both the proportion of time crabs spent on searching, and the probability of consumption upon capture. The proportion of time crabs spent on handling (P = 0.171), the encounter rate (P = 0.918), and the probability of capture upon encounter (P = 0.456), however, were not significantly affected by prey types. Handling time per prey was not significantly different among clam species. For the crab, prey profitability (energy intake per unit handling time) of R. philippinarum was similar to that of S. subcrenata, in both cases being significantly higher than that of M. meretrix (P ﹤ 0.001). The relative frequencies of changing from searching to handling were significantly higher for M. meretrix than for R. philippinarum and S. subcrenata (P = 0.007). These results suggest that the probability of consumption upon capture explained the observed selection by crabs. Furthermore, prey profitability, shell strength, and shell width, are important elements to affect prey selection of the crab.
BMC Evolutionary Biology, 2020
Background The adaptive significance of phenotypic changes elicited by environmental conditions e... more Background The adaptive significance of phenotypic changes elicited by environmental conditions experienced early in life has long attracted attention in evolutionary biology. In this study, we used Drosophila melanogaster to test whether the developmental diet produces phenotypes better adapted to cope with similar nutritional conditions later in life. To discriminate among competing hypotheses on the underlying nature of developmental plasticity, we employed a full factorial design with several developmental and adult diets. Specifically, we examined the effects of early- and late-life diets (by varying their yeast and sugar contents) on reproductive fitness and on the amount of energy reserves (fat and glycogen) in two wild-caught populations. Results We found that individuals that had developed on either low-yeast or high-sugar diet showed decreased reproductive performance regardless of their adult nutritional environment. The lower reproductive fitness might be caused by small...
Cell and Tissue Research, 2020
Terrestrial hermit crabs of the genusCoenobitadisplay strong behavioral responses to volatile odo... more Terrestrial hermit crabs of the genusCoenobitadisplay strong behavioral responses to volatile odors and are attracted by chemical cues of various potential food sources. Several aspects of their sense of aerial olfaction have been explored in recent years including behavioral aspects and structure of their peripheral and central olfactory pathway. Here, we use classical histological methods and immunohistochemistry against the neuropeptides orcokinin and allatostatin as well as synaptic proteins and serotonin to provide insights into the functional organization of their primary olfactory centers in the brain, the paired olfactory lobes. Our results show that orcokinin is present in the axons of olfactory sensory neurons, which target the olfactory lobe. Orcokinin is also present in a population of local olfactory interneurons, which may relay lateral inhibition across the array of olfactory glomeruli within the lobes. Extensive lateral connections of the glomeruli were also visualiz...
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Papers by Heinrich Dircksen