Strongyloidiasis associated with amebiasis and giardiaisis in an immunocompetent boy presented with acute abdomen

Strongyloides stercoralis (SS) is an intestinal nematode that is mainly endemic in tropical and subtropical regions and sporadic in temperate zones. SS infection frequently occurs in people who have hematologic malignancies, HIV infection and in individuals undergoing immunosuppressive therapy. In this study, we report a 12- year-old immunocompetent boy who was admitted to our hospital with acute abdomen. Laboratory evaluation showed strongyloidiasis, amebiasis and giardiasis. Clinical and laboratory findings immediately improved with albendazole therapy. Therefore, when diarrhea with signs of acute abdomen is observed, stool examinations should be done for enteroparasitosis. This approach will prevent misdiagnosis as acute abdomen. Complete clinical improvement is possible by medical therapy without surgical intervention.     

Ecological genetics of abdominal pigmentation in Drosophila falleni: a pleiotropic link to nematode parasitism

Drosophila falleni belongs to the quinaria species group, whose species vary considerably in patterns of wing and abdominal pigmentation. Drosophila falleni itself exhibits substantial variation among wild flies in abdominal spotting patterns. A selection experiment revealed that natural populations of D. falleni harbor high levels of genetic variation for spot number: in 10 generations of selection modal spot number within populations declined from 18 (the modal number in wild-caught females) to as low as zero. Rearing flies at different temperatures shows that some of the variation among wild flies is likely to reflect variation in the environmental conditions under which they developed. Fitness assays did not reveal any cost of reduced spot number with respect to development time, adult survival, or female fecundity. However, spotless flies were almost twice as susceptible to infection by the nematode parasite Howardula aoronymphium. Thus, selection exerted by nematode parasites may influence pigmentation patterns and other, genetically correlated traits in natural populations D. falleni.     

温度对蟋蟀若虫生长发育的影响

澳洲黑蟋蟀Teleogryllus commodusWalker若虫在22℃下,有9个龄期,在28℃下,只有8个龄期。若虫在22℃和28℃的平均历期分别是159d和79d,并且若虫胸部和腹部相对于头部的生长速率在低温条件下均小于高温条件下的若虫。     

Evidence for rapid downward fecundity selection in an ectoparasite (Philornis downsi) with earlier host mortality in Darwin’s finches

Fecundity selection is a critical component of fitness and a major driver of adaptive evolution. Trade‐offs between parasite mortality and host resources are likely to impose a selection pressure on parasite fecundity, but this is little studied in natural systems. The ‘fecundity advantage hypothesis’ predicts female‐biased sexual size dimorphism whereby larger females produce more offspring. Parasitic insects are useful for exploring the interplay between host resource availability and parasite fecundity, because female body size is a reliable proxy for fecundity in insects. Here we explore temporal changes in body size in the myiasis‐causing parasite Philornis downsi (Diptera: Muscidae) on the Galápagos Islands under conditions of earlier in‐nest host mortality. We aim to investigate the effects of decreasing host resources on parasite body size and fecundity. Across a 12‐year period, we observed a mean of c. 17% P. downsi mortality in host nests with 55 ± 6.2% host mortality and a trend of c. 66% higher host mortality throughout the study period. Using specimens from 116 Darwin's finch nests (Passeriformes: Thraupidae) and 114 traps, we found that over time, P. downsi pupae mass decreased by c. 32%, and male (c. 6%) and female adult size (c. 11%) decreased. Notably, females had c. 26% smaller abdomens in later years, and female abdomen size was correlated with number of eggs. Our findings imply natural selection for faster P. downsi pupation and consequently smaller body size and lower parasite fecundity in this newly evolving host–parasite system.     

Temporal patterns of genetic and phenotypic variation in the epidemiologically important drone fly, Eristalis tenax

Eristalis tenax L. (Diptera: Syrphidae) is commonly known as the drone fly (adult) or rat‐tailed maggot (immature). Both adults and immature stages are identified as potential mechanical vectors of mycobacterial pathogens, and early‐stage maggots cause accidental myiasis. We compared four samples from Mount Fru?ka Gora, Serbia, with the aim of obtaining insights into the temporal variations and sexual dimorphism in the species. This integrative approach was based on allozyme loci, morphometric wing parameters (shape and size) and abdominal colour patterns. Consistent sexual dimorphism was observed, indicating that male specimens had lighter abdomens and smaller and narrower wings than females. The distribution of genetic diversity at polymorphic loci indicated genetic divergence among collection dates. Landmark‐based geometric morphometrics revealed, contrary to the lack of divergence in wing size, significant wing shape variation throughout the year. In addition, temporal changes in the frequencies of the abdominal patterns observed are likely to relate to the biology of the species and ecological factors in the locality. Hence, the present study expands our knowledge of the genetic diversity and phenotypic plasticity of E. tenax. The quantification of such variability represents a step towards the evaluation of the adaptive potential of this species of medical and epidemiological importance.     

How do workers of the primitively eusocial wasp Ropalidia marginata detect the presence of their queens?

Queens in primitively eusocial insect societies are morphologically indistinguishable from their workers, and occupy the highest position in the dominance hierarchy. Such queens are believed to use aggression to maintain worker activity and reproductive monopoly in the colony. However, in the primitively eusocial wasp Ropalidia marginata, the queen is a strikingly docile individual, who interacts rarely with her workers. If the queen is experimentally removed, one of the workers becomes extremely aggressive within minutes, and eventually becomes the new queen of the colony. We designate her as the potential queen. Experimental evidence suggests that the queen probably uses a non-volatile pheromone to signal her presence to her workers. Here we attempt to identify the mechanism by which the queen transmits information about her presence to the workers. We designate the time taken for the potential queen to realize the absence of the queen as the realization time and model the realization time as a function of the decay time of the queen's signal and the average signal age. We find that the realization time obtained from the model, considering only direct interactions (193.5 min) is too large compared to the experimentally observed value of 30 min. Hence we consider the possibility of signal transfer through relay. Using the Dijkstra's algorithm, we first establish the effectiveness of relay in such a system and then use experimental data to fit the model. We find that the realization time obtained from the model, considering relay (237.1 min) is also too large compared to the experimentally observed value of 30 min. We thus conclude that physical interactions, both direct and indirect (relay), are not sufficient to transfer the queen's signal in R. marginata. Finally, we discuss the possibility that the queen applies her pheromone on the nest material from where the workers can perceive it without having to physically interact with the queen.     

Protein tyrosine phosphatase 69D is a substrate of protein O-mannosyltransferases 1-2 that is required for the wiring of sensory axons in Drosophila

Mutations in protein O-mannosyltransferases (POMTs) result in severe brain defects and congenital muscular dystrophies characterized by abnormal glycosylation of α-dystroglycan (α-Dg). However, neurological phenotypes of POMT mutants are not well understood, and the functional substrates of POMTs other than α-Dg remain unknown. Using a Drosophila model, here we reveal that Dg alone cannot account for the phenotypes of POMT mutants, and identify Protein tyrosine phosphatase 69D (PTP69D) as a gene interacting with POMTs in producing the abdomen rotation phenotype. Using RNAi-mediated knockdown, mutant alleles, and a dominant-negative form of PTP69D, we reveal that PTP69D is required for the wiring of larval sensory axons. We also found that PTP69D and POMT genes interact in this process, and that their interactions lead to complex synergistic or antagonistic effects on axon wiring phenotypes, depending on the mode of genetic manipulation. Using glycoproteomic approaches, we further characterized the glycosylation of the PTP69D transgenic construct expressed in genetic strains with different levels of POMT activity. We found that the PTP69D construct carries many O-linked mannose modifications when expressed in Drosophila with wild-type or ectopically upregulated expression of POMTs. These modifications were absent in POMT mutants, suggesting that PTP69D is a substrate of POMT-mediated O-mannosylation. Taken together, our results indicate that PTP69D is a novel functional substrate of POMTs that is required for axon connectivity. This mechanism of POMT-mediated regulation of receptor-type protein tyrosine phosphatase functions could potentially be conserved in mammals and may shed new light on the etiology of neurological defects in muscular dystrophies.     

新型口服超顺磁性磁共振对比剂-NK50的体外试验研究

目的:研究一种由纳米磁性原料研制成功的口服磁共振胃肠对比剂-NK50,为磁共振造影提供一种新型材料。方法:按照新药研究的方法,进行了毒理、代谢、动力学、动物体内磁共振成像试验,并对其进行了效果分析。结果:家兔服用NK-50前后,血清铁无明显变化,MRI胃肠道显示率由5～15%提高到80～100%。结论:这种对比剂易于接受,安全性好,成像浓度范围宽,性能稳定,成本低,有优良超顺磁的性阴性对比效果和临床应用前景。