NHR-23, a conserved member of the nuclear receptor family of transcription factors, is required for normal development in Caenorhabditis elegans where it plays a critical role in growth and molting. In a search for NHR-23 dependent genes, we performed whole genome comparative expression microarrays on both control and nhr-23 inhibited synchronized larvae. Genes that decreased in response to nhr-23 RNAi included several collagen genes. Unexpectedly, several hedgehog-related genes were also down-regulated after nhr-23 RNAi. A homozygous nhr-23 deletion allele was used to confirm the RNAi knockdown phenotypes and the changes in gene expression. Our results indicate that NHR-23 is a critical co-regulator of functionally linked genes involved in growth and molting and reveal evolutionary parallels among the ecdysozoa.

• MeSH
• Caenorhabditis elegans genetika   růst a vývoj   MeSH
• delece genu MeSH
• molekulární sekvence - údaje MeSH
• proteiny Caenorhabditis elegans genetika   fyziologie   MeSH
• proteiny hedgehog metabolismus   MeSH
• receptory cytoplazmatické a nukleární genetika   fyziologie   MeSH
• sekvence aminokyselin MeSH
• shazování tělního pokryvu genetika   MeSH
• transkripční faktory genetika   fyziologie   MeSH
• vývojová regulace genové exprese * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Intramural MeSH
• Názvy látek
• NHR-23 protein, C elegans MeSH Prohlížeč
• proteiny Caenorhabditis elegans MeSH
• proteiny hedgehog MeSH
• receptory cytoplazmatické a nukleární MeSH
• transkripční faktory MeSH

BACKGROUND, AIM AND SCOPE: Pollution-induced endocrine disruption in vertebrates and invertebrates is a worldwide environmental problem, but relatively little is known about effects of endocrine disrupting compounds (EDCs) in planktonic crustaceans (including Daphnia magna). Aims of the present study were to investigate acute 48 h toxicity and sub-chronic (4-6 days) and chronic (21 days) effects of selected EDCs in D. magna. We have investigated both traditional endpoints as well as other parameters such as sex determination, maturation, molting or embryogenesis in order to evaluate the sensitivity and possible use of these endpoints in ecological risk assessment. MATERIALS AND METHODS: We have studied effects of four model EDCs (vinclozolin, flutamide, ketoconazole and dicofol) on D. magna using (i) an acute 48 h immobilization assay, (ii) a sub-chronic, 4-6 day assay evaluating development and the sex ratio of neonates, and (iii) a chronic, 21 day assay studying number of neonates, sex of neonates, molting frequency, day of maturation and the growth of maternal organisms. RESULTS: Acute EC50 values in the 48 h immobilization test were as follows (mg/L): dicofol 0.2, ketoconazole 1.5, flutamide 2.7, vinclozolin >3. Short-term, 4-6 day assays with sublethal concentrations showed that the sex ratio in Daphnia was modulated by vinclozolin (decreased number of neonate males at 1 mg/L) and dicofol (increase in males at 0.1 mg/L). Flutamide (up to 1 mg/L) had no effect on the sex of neonates, but inhibited embryonic development at certain stages during chronic assay, resulting in abortions. Ketoconazole had no significant effects on the studied processes up to 1 mg/L. DISCUSSION: Sex ratio modulations by some chemicals (vinclozolin and dicofol) corresponded to the known action of these compounds in vertebrates (i.e. anti-androgenicity and anti-oestrogenicity, respectively). Our study revealed that some chemicals known to affect steroid-regulated processes in vertebrates can also affect sublethal endpoints (e.g. embryonic sex determination and/or reproduction) in invertebrates such as D. magna. CONCLUSIONS: A series of model vertebrate endocrine disrupters affected various sub-chronic and chronic parameters in D. magna including several endpoints that have not been previously studied in detail (such as sex determination in neonates, embryogenesis, molting and maturation). Evaluations of traditional reproduction parameters (obtained from the 21 day chronic assay). as well as the results from a rapid, 4-6 day, sub-chronic assay provide complementary information on non-lethal effects of suspected organic endocrine disrupters. RECOMMENDATIONS AND PERSPECTIVES: It seems that there are analogies between vertebrates and invertebrates in toxicity mechanisms and in vivo effects of endocrine disruptors. However, general physiological status of organisms may also indirectly affect endpoints that are traditionally considered 'hormone regulated' (especially at higher effective concentrations as observed in this study) and these factors should be carefully considered. Further research of D. magna physiology and comparative studies with various EDCs will help to understand mechanisms of action as well as ecological risks of EDCs in the environment.

• MeSH
• chemické látky znečišťující vodu toxicita   MeSH
• Daphnia účinky léků   fyziologie   MeSH
• dikofol toxicita   MeSH
• endokrinní disruptory toxicita   MeSH
• flutamid toxicita   MeSH
• ketokonazol toxicita   MeSH
• lokomoce účinky léků   MeSH
• novorozená zvířata MeSH
• oxazoly toxicita   MeSH
• pohlavní dospělost účinky léků   MeSH
• poměr pohlaví MeSH
• rozmnožování účinky léků   MeSH
• shazování tělního pokryvu účinky léků   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chemické látky znečišťující vodu MeSH
• dikofol MeSH
• endokrinní disruptory MeSH
• flutamid MeSH
• ketokonazol MeSH
• oxazoly MeSH
• vinclozolin MeSH Prohlížeč

Epigenetic mechanisms have not been characterized in ticks despite their importance as vectors of human and animal diseases worldwide. Our investigation identifies and functionally characterizes the orthologue of S-adenosylmethionine (SAM) binding methyltransferase enzyme, disruptor of telomeric silencing 1-like (DOT1L) in Ornithodoros moubata (OmDOT1L), a soft tick vector for the relapsing fever pathogen Borrelia duttonii and the African swine fever virus. The OmDOT1L tertiary structure was predicted and compared to the Homo sapiens DOT1L which had been co-crystalized with SGC0946, a DOT1L-specific inhibitor. The amino acid residues crucial for SAM and SGC0946 binding conserved in most DOT1L sequences available, are also conserved in OmDOT1L. Quantitative PCR of Omdot1l during O. moubata life stages showed that transcripts were significantly upregulated in first-stage nymphs. O. moubata larvae exposed to SGC0946 displayed high mortality during molting to first-stage nymphs. Furthermore, a significant decrease in weight was observed in second-stage nymphs fed on recombinant OmDOT1L-immunized rabbits. In contrast, artificial blood feeding supplemented with SGC0946 did not affect survival and reproductive performance of adult female ticks. We concluded that OmDOT1L plays an essential role in the regulation of larval molting and the feeding of O. moubata second-stage nymphs.

• Klíčová slova
• DOT1L, Ornithodoros moubata, histone methyltransferase,
• Publikační typ
• časopisecké články MeSH

Feather bacterial load affects key avian life-history traits such as plumage condition, innate immunity, and reproductive success. Investigating the interplay between life-history traits and feather microbial load is critical for understanding mechanisms of host-microbiome interactions. We hypothesize that spatiotemporal variation associated with migration and molting, body size affecting colonizable body surface area, and preening intensity could shape feather bacterial load. Integrating 16S rDNA-qPCR and flow cytometry, we examined total and viable bacterial loads in the feathers of 316 individuals of 24 Palearctic passerine species. We found that viable bacterial load in feathers was lower in larger species and higher in residents compared to migrants. In contrast, total bacterial load was not explained by any of the life-history traits but varied considerably among species, sampling sites, and years. By pinpointing main drivers of bacterial loads on avian body surfaces, we identify key mechanisms shaping host-microbiome interactions and open alternative research directions.

• Klíčová slova
• Evolutionary biology, Microbiology, Ornithology,
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Leishmaniasis is a group of neglected vector-borne diseases transmitted by phlebotomine sand flies. Leishmania parasites must overcome various defenses in the sand fly midgut, including the insects's immune response. Insect immunity is regulated by the ecdysone hormone, which binds to its nuclear receptor (EcR) and activates the transcription of genes involved in insect immunity. However, the role of ecdysone in sand fly immunity has never been studied. Phlebotomus perniciosus is a natural vector of Leishmania infantum; here, we manipulated its neuroendocrine system using azadirachtin (Aza), a natural compound known to affect ecdysone synthesis. METHODS: Phlebotomus perniciosus larvae and adult females were fed on food containing either Aza alone or Aza plus ecdysone, and the effects on mortality and ecdysis were evaluated. Genes related to ecdysone signaling and immunity were identified in P. perniciosus, and the expression of antimicrobial peptides (AMPs), EcR, the ecdysone-induced genes Eip74EF and Eip75B, and the transcription factor serpent were analyzed using quantitative polymerase chain reaction (PCR). RESULTS: Aza treatment inhibited molting of first-instar (L1) larvae to L2, with only 10% of larvae molting compared to 95% in the control group. Serpent and Eip74EF, attacin, defensin 1, and defensin 2 genes were downregulated by Aza treatment in larvae. Similarly, Aza-treated adult females also presented suppression of ecdysone signaling-related genes and the AMPs attacin and defensin 2. Notably, all gene repression caused by Aza was reversed by adding ecdysone concomitantly with Aza to the larval or female food, indicating that these genes are effective markers for ecdysone repression. CONCLUSIONS: These results highlight the critical role of ecdysone in regulating the development and immunity of P. perniciosus, which potentially could interfere with Leishmania infection.

• Klíčová slova
• Phlebotomus perniciosus, Antimicrobial peptides, Azadirachtin, Ecdysone,
• MeSH
• antimikrobiální peptidy genetika   farmakologie   MeSH
• ekdyson * MeSH
• hmyz - vektory účinky léků   genetika   parazitologie   imunologie   MeSH
• hmyzí proteiny genetika   metabolismus   MeSH
• larva * účinky léků   imunologie   genetika   MeSH
• limoniny * farmakologie   MeSH
• Phlebotomus * účinky léků   genetika   parazitologie   imunologie   MeSH
• shazování tělního pokryvu účinky léků   MeSH
• signální transdukce * účinky léků   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antimikrobiální peptidy MeSH
• azadirachtin MeSH Prohlížeč
• ekdyson * MeSH
• hmyzí proteiny MeSH
• limoniny * MeSH

CHR3 (nhr-23, NF1F4), the homologue of Drosophila DHR3 and mammalian ROR/RZR/RevErbA nuclear hormone receptors, is important for proper epidermal development and molting in the nematode Caenorhabditis elegans. Disruption of CHR3 (nhr-23) function leads to developmental changes, including incomplete molting and a short, fat (dumpy) phenotype. Here, we studied the role of CHR3 during larval development by using expression assays and RNA-mediated interference. We show that the levels of expression of CHR3 (nhr-23) cycle during larval development and reduction of CHR3 function during each intermolt period result in defects at all subsequent molts. Assaying candidate gene expression in populations of animals treated with CHR3 (nhr-23) RNA-mediated interference has identified dpy-7 as a potential gene acting downstream of CHR3. These results define CHR3 as a critical regulator of all C. elegans molts and begin to define the molecular pathway for its function.

• MeSH
• Caenorhabditis elegans růst a vývoj   fyziologie   MeSH
• DNA vazebné proteiny * MeSH
• hmyzí proteiny * MeSH
• larva MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• receptory peptidů bezobratlých genetika   fyziologie   MeSH
• shazování tělního pokryvu * MeSH
• teplota MeSH
• trans-aktivátory * MeSH
• vývojová regulace genové exprese * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• CHR3 protein, Choristoneura fumiferana MeSH Prohlížeč
• DNA vazebné proteiny * MeSH
• hmyzí proteiny * MeSH
• receptory peptidů bezobratlých MeSH
• trans-aktivátory * MeSH

In birds, concentrations of testosterone (T) and corticosterone (Cort) are closely connected with many morphological, behavioral, and other physiological traits, including reproduction, metabolism, immunity, and fitness. The direction of the effect of these hormones on above-mentioned traits, and the potential feedback between hormones are in general unclear; in addition, knowledge on how age and sex can affect T and Cort concentrations is still inconsistent. Our study used a novel method to analyze testosterone and corticosterone in feathers (Tf, Cortf) based on the precolumn chemical derivatization of hormones before liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Unlike previously used methods (RIA, EIA), our analytical procedure allows simultaneous analysis of both hormones from small amounts of feathers (4-25 mg) and, thus, overcomes the problem of insufficient detection limits. We applied this method to reveal associations between Tf and Cortf hormone concentrations and feather growth, age, and sex in feathers grown during the postbreeding (flanks) and prebreeding (tails) periods in barn swallows (Hirundo rustica). There was neither a correlation between prebreeding and postbreeding Tf, nor between prebreeding and postbreeding Cortf. Tail Cortf concentrations were negatively associated with tail feather growth rates. Feather hormone concentrations were correlated in the prebreeding period, negatively in males but positively in females. Both Cortf and Tf were higher in young birds compared to older ones, indicating either an age-related decrease in hormone concentrations within individuals, or the selective disappearance of individuals with high steroid concentrations. Males and females did not differ in Cortf, but Tf concentrations were higher in males than females, particularly during the prebreeding period. In this study, we provide an effective method for analyzing hormones in feathers in an ecological context, especially in situations when the total amount of feathers available for the analysis is limited.

• Klíčová slova
• barn swallow, feather corticosterone, feather testosterone, keratinous matrix, liquid chromatography–tandem mass spectrometry, ptilochronology, stress,
• Publikační typ
• časopisecké články MeSH

Four medial neurosecretory cells (MNC) and 4 lateral neurosecretory cells (LNC) in each brain hemisphere, and one pair of cells in each thoracic ganglion (TG) of Galleria larva react with antibodies against bombyxin and insulin. Material secreted from the MNC and LNC is released mainly in the corpora allata, and that from the TG through the ventral median nerves. Intrinsic secretory cells of the corpora cardiaca (CC) also contain bombyxin-like, but not insulin-like material. The immunoreactivities all disappear during molts and reappear with resumption of feeding. In the MNC and TG they reappear for less than a day, but in cells of the CC immunoreactivity reappears for the whole feeding period. Before pupation, the LNC become temporarily immunopositive towards the end of feeding period, and the MNC and TG during the wandering period, i.e. at the time of prothoracic gland stimulation. Immunoreactivity disappears during the pupal molt. In pupae it is present in the 4 pairs of MNC and 1-2 pairs of LNC 12-48 hr after ecdysis, and in cells of the CC from 12 hr after ecdysis until the end of the pupal instar. In adult, immunoreactivity is restricted to 2 pairs of the LNC and to CC cells.

• Publikační typ
• časopisecké články MeSH

Juvenile hormones (JHs) are sesquiterpenoids synthesized by the corpora allata (CA). They play critical roles during insect development and reproduction. The first JH was described in 1934 as a "metamorphosis inhibitory hormone" in Rhodnius prolixus by Sir Vincent B. Wigglesworth. Remarkably, in spite of the importance of R. prolixus as vectors of Chagas disease and model organisms in insect physiology, the original JH that Wigglesworth described for the kissing-bug R. prolixus remained unidentified. We employed liquid chromatography mass spectrometry to search for the JH homologs present in the hemolymph of fourth instar nymphs of R. prolixus. Wigglesworth's original JH is the JH III skipped bisepoxide (JHSB3), a homolog identified in other heteropteran species. Changes in the titer of JHSB3 were studied during the 10-day long molting cycle of 4th instar nymph, between a blood meal and the ecdysis to 5th instar. In addition we measured the changes of mRNA levels in the CA for the 13 enzymes of the JH biosynthetic pathway during the molting cycle of 4th instar. Almost 90 years after the first descriptions of the role of JH in insects, this study finally reveals that the specific JH homolog responsible for Wigglesworth's original observations is JHSB3.

• MeSH
• biologická proměna * MeSH
• corpora allata chemie   MeSH
• epoxidové sloučeniny chemie   MeSH
• hemolymfa chemie   MeSH
• kukla chemie   fyziologie   MeSH
• nymfa chemie   fyziologie   MeSH
• Rhodnius chemie   fyziologie   MeSH
• seskviterpeny chemie   MeSH
• shazování tělního pokryvu fyziologie   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• epoxidové sloučeniny MeSH
• juvenile hormone III MeSH Prohlížeč
• seskviterpeny MeSH

A unique cycle of female form alternation has been revealed in an experimental population of Orconectes limosus during a year-long observation. Significant cyclic changes observed in chelae length, width, and robustness, as well as in abdomen width, demonstrated a form alternation similar to that in conspecific males. Small females alternate between sexually active and sexually inactive forms with a short time interval between successive molts as well as different growth patterns of some body parts. Form alternation efficiently produces larger chelae, abdomen, and body dimensions, especially the molt to form I (sexually active). Larger females that undergo only a single annual molt do not alter between forms and are sexually active. They grow slowly and lose chelae robustness. The cycle of form alternation, consisting of two molts per year, may facilitate the effective utilization of resources to increase the size of body parts important to survival and reproduction.

• MeSH
• časové faktory MeSH
• pohlavní dimorfismus MeSH
• severní raci anatomie a histologie   růst a vývoj   fyziologie   MeSH
• shazování tělního pokryvu MeSH
• velikost těla MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH