Drosophila as a model for the Anopheles Malpighian tubule

The insect Malpighian tubule is involved in osmoregulation, detoxification and immune function, physiological processes which are essential for insect development and survival. As the Malpighian tubules contain many ion channels and transporters, they could be an effective tissue for targeting with novel pesticides to control populations of Diptera. Many of the insecticide compounds used to control insect pest species are no longer suited to their task, and so new means of control must be found. The malarial mosquito, Anopheles gambiae, spreads the Plasmodium parasite which is responsible for over one million deaths each year, and is one of the species on which many current insecticides are no longer effective. Anopheles is notoriously difficult to study due to a lack of natural mutation stocks and transgenic capabilities, as well as the difficulties involved with maintaining a colony. The fruit-fly Drosophila melanogaster is a useful model organism for Anopheles, and previous studies suggest that the mechanisms of Malpighian tubule function are well conserved between the two species. Following microarray investigations to identify genes which were highly enriched in both the Anopheles and Drosophila Malpighian tubules, four homologous genepairs were selected, AGAP097752 and CG15406, AGAP012251 and Picot, AGAP009005 and ZnT35C, and AGAP002587 and CG8028. Analysis of the Anopheles Malpighian tubule microarray data-set showed ion channels and transporters to be highly expressed in the tubules, although similarly to Drosophila, very few of the renal up-regulated genes have been characterised. The gene-pairs chosen were all novel, but putatively predicted to be involved in sugar transport, phosphate transport, zinc transport and monocarboxylate transport respectively. These are functions which are likely to be essential, but so far remain unstudied in the insect renal system. The gene-pairs were chosen with two main purposes; to determine how closely expression of the genes was conserved between Anopheles and Drosophila, and also to determine which of the genes were essential, and could therefore be effective insecticide targets. The homologous gene-pair AGAP007752 and CG15406 have well-conserved expression in the Malpighian tubules, suggesting that they are functionally important genes. This was shown in Drosophila, where knockdown of CG15406 4 expression was lethal to the fly. A direct role in tubule fluid secretion was not found, and experiments to determine the sugars transported by CG15406 were inconclusive, possibly due to an abundance of highly-expressed sugar transporters in the tubules. The inorganic phosphate co-transporters AGAP012251 and Picot also show conservation of expression in the Malpighian tubules, and are likely to be involved in the transport of inorganic phosphate into the tubules for incorporation into metallo-organic concretions. In the Anopheles tubules the concretions are found in the main segment, in the Drosophila tubules they are located in the distal initial and transitional segments, where AGAP012251 and Picot are expressed. Picot is essential for Drosophila development through to adulthood, and for survival as an adult, although the transporter does not appear to be directly involved in fluid secretion. Expression of neither AGAP012251 nor Picot is confined to the tubules. The putative zinc transporters AGAP009005 and ZnT35C show a highly conserved expression pattern, and appear to be involved in the secretion of excess zinc from the Malpighian tubules. ZnT35C is essential early-on in Drosophila development, and for survival in the adult fly. Similarly to Picot and CG15406, there is no direct role for ZnT35C in fluid secretion from the tubules under normal zinc conditions. The putative monocarboxylate transporters AGAP002587 and CG8028 are not as well conserved, as AGAP002587 is highly upregulated in the tubules of female mosquitoes both before and after a bloodfeed, whereas CG8028 has no sex-specific up-regulation. CG8028 is not essential for Drosophila development or survival, and plays no discernable role in fluid secretion. The data collected during this investigation suggests that in general there is a high level of conservation of expression between homologous transport genes in the Anopheles and Drosophila Malpighian tubules. The three gene-pairs which show the greatest conservation of expression are also essential for development and survival in Drosophila. This suggests that cross-species studies are an effective way of finding essential and important genes. The data collected also suggests that Drosophila is a reliable model for Anopheles, and could be used as a high-throughput system of finding genes which could be effective insecticide targets in Diptera

Allele length of the DMPK CTG repeat is a predictor of progressive myotonic dystrophy type 1 phenotypes

Myotonic dystrophy type 1 (DM1) is an autosomal dominant inherited disorder caused by expansion of a germline and somatically unstable CTG repeat in the DMPK gene. Previously, CTG repeat length at birth has been correlated to patient age at symptom onset. Attempts to correlate CTG repeat length with progressive DM1 phenotypes, such as muscle power, have proven difficult. To better correlate genotype with progressive phenotypes, we have measured CTG repeat tract length and screened for interrupting variant repeats in 192 study participants from a well-characterized Canadian cohort. We have assessed genotype–phenotype correlations with nine progressive measures of skeletal muscle power and respiratory function. We have built statistical models that include confounding factors such as sex, age, height and weight to further explain variation in muscle power. Our analysis reveals a strong correlation between DM1 genotype and respiratory function and skeletal muscle power, as part of a complex model that includes additional modulators such as sex, age, height, weight and the presence or absence of interrupting variant repeats. Distal skeletal muscle measurements, such as hand pinch and grip strength, show the strongest correlation with disease genotype. Detailed analysis of CTG repeat length, and incorporation of confounding factors, greatly improves the predictive ability of these models. They reveal a greater genetic influence on individual progressive phenotypes than on age at symptom onset and for clinical trials will help optimize stratification and explain patient variability. They will also help practitioners prioritize assessment of the muscular power measurements that correlate best with disease severity

gene DNA methylation levels are associated with muscular and respiratory profiles in DM1

Objective: To assess the effects of dystrophia myotonica protein kinase (DMPK) DNA methylation (DNAme) epivariation on muscular and respiratory profiles in patients with myotonic dystrophy type 1 (DM1). Methods: Phenotypes were assessed with standardized measures. Pyrosequencing of bisulfite-treated DNA was used to quantify DNAme levels in blood from 90 patients with DM1 (adult form). Modal CTG repeat length was assessed using small-pool PCR. The presence of Acil-sensitive variant repeats was also tested. Results: DNAme levels upstream of the CTG expansion (exon and intron 11) were correlated with modal CTG repeat length (rs = −0.224, p = 0.040; rs = −0.317, p = 0.003; and rs = −0.241, p = 0.027), whereas correlations were observed with epivariations downstream of the CTG repeats (rs = 0.227; p = 0.037). The presence of a variant repeat was associated with higher DNAme levels at multiple CpG sites (up to 10% higher; p = 0.001). Stepwise multiple linear regression modeling showed that DNAme contributed significantly and independently to explain phenotypic variability in ankle dorsiflexor (3 CpGs: p = 0.001, 0.013, and 0.001), grip (p = 0.089), and pinch (p = 0.028) strengths and in forced vital capacity (2 CpGs: p = 0.002 and 0.021) and maximal inspiratory pressure (p = 0.012). Conclusions: In addition to the CTG repeat length, DMPK epivariations independently explain phenotypic variability in DM1 and could thus improve prognostic accuracy for patients

A DM1 family with interruptions associated with atypical symptoms and late onset but not with a milder phenotype

Carriage of interruptions in CTG repeats of the myotonic dystrophy protein kinase gene has been associated with a broad spectrum of myotonic dystrophy type 1 (DM1) phenotypes, mostly mild. However, the data available on interrupted DM1 patients and their phenotype are scarce. We studied 49 Spanish DM1 patients, whose clinical phenotype was evaluated in depth. Blood DNA was obtained and analyzed through triplet‐primed polymerase chain reaction (PCR), long PCR‐Southern blot, small pool PCR, AciI digestion, and sequencing. Five patients of our registry (10%), belonging to the same family, carried CCG interruptions at the 3’ end of the CTG expansion. Some of them presented atypical traits such as a very late onset of symptoms (>50 years) and a severe axial and proximal weakness requiring walking assistance. They also showed classic DM1 symptoms including cardiac and respiratory dysfunction, which were severe in some of them. Sizes and interrupted allele patterns were determined, and we found a contraction and an expansion in two intergenerational transmissions. Our study contributes to the observation that DM1 patients carrying interruptions present with atypical clinical features that can make DM1 diagnosis difficult, with a later than expected age of onset and a previously unreported aging‐related severe disease manifestation

FlyAtlas 2 in 2022: enhancements to the Drosophila melanogaster expression atlas

No abstract available

The <i>D. melanogaster</i> capa-1 neuropeptide activates renal NF-kB signaling

The capa peptide family exists in a very wide range of insects including species of medical, veterinary and agricultural importance. Capa peptides act via a cognate G-protein coupled receptor (capaR) and have a diuretic action on the Malpighian tubules of Dipteran and Lepidopteran species. Capa signaling is critical for fluid homeostasis and has been associated with desiccation tolerance in the fly, Drosophila melanogaster. The mode of capa signaling is highly complex, affecting calcium, nitric oxide and cyclic GMP pathways. Such complex physiological regulation by cell signaling pathways may occur ultimately for optimal organismal stress tolerance to multiple stressors. Here we show that D. melanogaster capa-1 (Drome-capa-1) acts via the Nuclear Factor kappa B (NF-kB) stress signaling network. Human PCR gene arrays of capaR-transfected Human Embryonic Kidney (HEK) 293 cells showed that Drome-capa-1 increases expression of NF-kB, NF-kB regulated genes including IL8, TNF and PTGS2, and NF-kB pathway-associated transcription factors i.e. EGR1, FOS, cJUN. Furthermore, desiccated HEK293 cells show increased EGR1, EGR3 and PTGS2 – but not IL8, expression. CapaR-transfected NF-kB reporter cells showed that Drome-capa-1 increased NF-kB promoter activity via increased calcium. In Malpighian tubules, both Drome-capa-1 stimulation and desiccation result in increased gene expression of the D. melanogaster NF-kB orthologue, Relish; as well as EGR-like stripe and klumpfuss. Drome-capa-1 also induces Relish translocation in tubule principal cells. Targeted knockdown of Relish in only tubule principal cells reduces desiccation stress tolerance of adult flies. Together, these data suggest that Drome-capa-1 acts in desiccation stress tolerance, by activating NF-kB signaling

Entwicklung einer Scheibenbremse aus Kohlefaserverbundwerkstoff fuer R/S-Hochgeschwindigkeitszuege Abschlussbericht

Available from TIB Hannover: F97B990+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Two-person bargaining between threat and fair solution

SIGLETIB: RN 5363 (145)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

DNA methylation at the DMPK gene locus is associated with cognitive functions in myotonic dystrophy type 1

Aim: Myotonic dystrophy type 1 (DM1) is caused by an unstable trinucleotide (CTG) expansion at the DMPK gene locus. Cognitive dysfunctions are often observed in the condition. We investigated the association between DMPK blood DNA methylation (DNAm) and cognitive functions in DM1, considering expansion length and variant repeats (VRs). Method: Data were obtained from 115 adult-onset DM1 patients. Molecular analyses consisted of pyrosequencing, small pool PCR and Southern blot hybridization. Cognitive functions were assessed by validated neuropsychological tests. Results: For patients without VRs (n = 103), blood DNAm at baseline independently contributed to predict cognitive functions 9 years later. Patients with VRs (n = 12) had different DNAm and cognitive profiles. Conclusion: DNAm allows to better understand DM1-related cognitive dysfunction etiology

Periodic solutions of the Stefan problem with hysteresis-type boundary conditions

We consider the Stefan problem with Dirichlet boundary conditions depending on a hysteresis functional where the free boundary is involved. We show existence of a positive value T and existence of a T-periodic solution of the problem, provided the Stefan number is sufficiently small and the hysteresis functional is described by the elementary rectangular hysteresis loop. If in addition the Preisach hysteresis operator is Lipschitz-continuous we prove that every periodic solution must be stationary. (orig.)Available from TIB Hannover: RO 7722(399) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman