RESUMO
The fruit fly Drosophila melanogaster is a model for understanding how hosts and their microbial partners interact as the host adapts to wild environments. These interactions are readily interrogated because of the low taxonomic and numeric complexity of the flies' bacterial communities. Previous work has established that host genotype, the environment, diet, and interspecies microbial interactions can all influence host fitness and microbiota composition, but the specific processes and characters mediating these processes are incompletely understood. Here, we compared the variation in microbiota composition between wild-derived fly populations when flies could choose between the microorganisms in their diets and when flies were reared under environmental perturbation (different humidities). We also compared the colonization of the resident and transient microorganisms. We show that the ability to choose between microorganisms in the diet and the environmental condition of the flies can influence the relative abundance of the microbiota. There were also key differences in the abundances of the resident and transient microbiota. However, the microbiota only differed between populations when the flies were reared at humidities at or above 50% relative humidity. We also show that elevated humidity determined the penetrance of a gradient in host genetic selection on the microbiota that is associated with the latitude the flies were collected from. Finally, we show that the treatment-dependent variation in microbiota composition is associated with variation in host stress survival. Together, these findings emphasize that host genetic selection on the microbiota composition of a model animal host can be patterned with the source geography, and that such variation has the potential to influence their survival in the wild. Importance: The fruit fly Drosophila melanogaster is a model for understanding how hosts and their microbial partners interact as hosts adapt in wild environments. Our understanding of what causes geographic variation in the fruit fly microbiota remains incomplete. Previous work has shown that the D. melanogaster microbiota has relatively low numerical and taxonomic complexity. Variation in the fly microbiota composition can be attributed to environmental characters and host genetic variation, and variation in microbiota composition can be patterned with the source location of the flies. In this work we explored three possible causes of patterned variation in microbiota composition. We show that host feeding choices, the host niche colonized by the bacteria, and a single environmental character can all contribute to variation in microbiota composition. We also show that penetrance of latitudinally-patterned host genetic selection is only observed at elevated humidities. Together, these results identify several factors that influence microbiota composition in wild fly genotypes and emphasize the interplay between environmental and host genetic factors in determining the microbiota composition of these model hosts.
RESUMO
BACKGROUND: On-site evaluation of fine-needle aspiration (FNA) specimens by a pathologist is essential to obtain adequate samples and provide a preliminary diagnosis. Distance from the laboratory can make this difficult. The authors present their experience with on-site evaluation using telecytopathology. METHODS: Dynamic images of cytology smears were captured and processed with a Nikon digital camera system for microscopy and transmitted via Ethernet. A pathologist accessed the real-time images on a computer and interpreted them while communicating with on-site operators over the telephone. Sample adequacy and accuracy of preliminary diagnosis were compared with those obtained by regular on-site evaluation. RESULTS: A total of 429 telecytopathology cases and 363 conventional on-site cases were compared. Specimens were mainly from the pancreas, gastrointestinal tract, liver, and lymph nodes. Adequacy rate was 94.0% for telecytopathology and 97.7% for conventional cases. Preliminary diagnoses of unsatisfactory, adequate (defer), negative/benign, atypical, neoplasm, suspicious, and positive for malignancy were 6.3%, 13.5%, 14.9%, 17.9%, 7.2%, 8.6%, and 31.5% for telecytopathology and 3.9%, 30.6%, 21.5%, 9.6%, 5.0%, 5.2%, and 24.2% for conventional cases. Preliminary and final diagnoses were discrepant in 7 (1.8%) of 371 telecytopathology cases, and in 8 (3.1%) of 252 conventional cases. Difficulty was encountered in some cases in distinguishing pancreatic endocrine neoplasm from lymphoid proliferations, and low grade pancreatic tumors from chronic pancreatitis via telecytopathology. CONCLUSIONS: On-site evaluation of FNA specimens via telecytopathology assures sample adequacy and accurate preliminary diagnosis compared with the conventional method. It allows pathologists to use their time more efficiently and makes on-site evaluations at remote locations possible.
