Impact of sample preservation and manipulation on insect gut microbiome profiling : a test case with fruit flies (Diptera, Tephritidae)

High-throughput sequencing (HTS) techniques are of great value for the investigation of microbial communities, and have been extensively used to study the gut microbiome. While most studies focus on the human gut, many others have investigated insects. However, because of the rapid spread of HTS techniques, a lot of variation exists in the protocols for sample preparation. In the present study, we investigated the impact of two widely adopted sample-processing procedures preceding library preparation, i.e., preservation of insect tissue in 70% ethanol (EtOH) and sample dissection. We used the fruit fly Ceratitis capitata (Diptera: Tephritidae) as a model organism and set up two experiments, one comparing the effects of sample manipulation and preservation across life stages and the other across fruit samples from different sources. The results of this study showed no major effects of dissection on the outcome of HTS. However, EtOH preservation did have effects on the recovered gut microbiome, the main effect being a significant reduction of the dominant genus, Providencia, in EtOH-preserved samples. Less abundant bacterial groups were also affected resulting in altered microbial profiles obtained from samples preserved in 70% EtOH. These results have important implications for the planning of future studies and when comparing studies that used different sample preparation protocols

INTEGRATING SENSORY ANALYSIS AND HEDONIC EVALUATION FOR APPLE QUALITY ASSESSMENT

Apple cultivars were subjected to a consumer test in order to appreciate individual preferences and set up a protocol for a practical hedonic-sensory evaluation. Cultivars subjected to the test were "Golden Delicious,""Modi,""Pink Lady" and "Fuji" of two different origins. Apples had the sensory profile defined by a trained panel and were evaluated by 154 consumers. According to their preferences, consumer population could be divided in six clusters. Consumer preference responses clearly associated the two "Fuji" and showed "Modi" and "Pink Lady" to have appeal on the same consumers groups. Besides expressing hedonic judgment, consumers were requested to indicate the positive sensory attributes determining their choice. Consumers appreciated "Golden Delicious" and "Fuji" on the basis of sweetness and aroma, while preferences for "Pink Lady" and "Modi" were expressed by consumers appreciating crispness, juiciness and a certain degree of acidity. The involvement of consumers in defining attributes driving preferences provides details useful for weighing up the consistency between consumers' response and sensory panel profile

Ultrasonographic Study of Gallbladder Wall Thickness and Emptying in Cirrhotic Patients without Gallstones

Background and Aim. Gallbladder wall thickening and impaired contractility are currently reported in cirrhotic patients and often related to portal hypertension and hepatic failure. The purpose of this work was to evaluate, by ultrasonographic method, gallbladder wall thickness and gallbladder emptying after a standard meal in normal subjects and in patients with compensated liver cirrhosis without gallstones. Methods. Twenty-three patients with Child-Pugh class A liver cirrhosis and twenty healthy controls were studied. Gallbladder wall thickness (GWT), gallbladder fasting volume (FV), residual volume (RV), and maximum percentage of emptying (%E) were calculated. Measurements of mean portal velocity, portal vein flow, and serum albumin were performed too. Statistical analysis was assessed by Student's “t test” for unpaired data. Results. GWT was 0.60 ± 0.22 cm in cirrhotic patients and 0.21 ± 0.06 cm in controls (P < .0001). FV and RV were, respectively, 37.8 ± 3.7 cm3 and 21.8 ± 3 cm3 in cirrhotic patients, 21.9 ± 4.2 cm3 and 4.6 ± 2.2 cm3 in healthy volunteers (P < .0001). %E was smaller in cirrhotics (42.6 ± 7.8) as compared to controls (80.3 ± 7.2; P < .0001). Conclusions. In patients with compensated liver cirrhosis without gallstones gallbladder wall thickness is increased whereas its contractility is reduced. These early structural and functional alterations could play a role in gallstone formation in more advanced stages of the disease

A review of the current knowledge on Zeugodacus cucurbitae (Coquillett) (Diptera, Tephritidae) in Africa, with a list of species included in Zeugodacus

This paper reviews all available information regarding the occurrence and biology of the melon fly, Zeugodacus cucurbitae (Coquillett), in the Afrotropical Region, including data on invasion history, distribution patterns, population genetics, host range, and interspecific competition. Although limited intraspecific variability has been observed within the region regarding the above mentioned aspects, there seems to be no indication that Z. cucurbitae represents a species complex. A checklist of all of the species included in Zeugodacus as recently proposed by Virgilio et al. (2015) is provided. (Résumé d'auteur

Population structure and cryptic genetic variation in the mango fruit fly, Ceratitis cosyra (Diptera, Tephritidae)

The fruit fly Ceratitis cosyra is an important agricultural pest negatively affecting the mango crop production throughout Africa and also feeding on a variety of other wild and cultivated hosts. The occurrence of deeply divergent haplotypes, as well as extensive morphological variability, previously suggested possible cryptic speciation within C. cosyra. Here we provide the first large-scale characterisation of the population structure of C. cosyra with the main objective of verifying cryptic genetic variation. A total of 348 specimens from 13 populations were genotyped at 16 polymorphic microsatellite loci. Hardy-Weinberg equilibrium (HWE) deviations were observed in 40.4% of locus-population combinations and suggested the occurrence of genetic substructuring within populations. Discriminant Analysis of Principal Components (DAPC) showed genetic divergence between the vast majority of vouchers from Burundi and Tanzania (plus a few outliers from other African countries) and all other specimens sampled. Individual Bayesian assignments confirmed the existence of two main genotypic groups also occurring in sympatry. These data provided further support to the hypothesis that C. cosyra might include cryptic species. However, additional integrative taxonomy, possibly combining morphological, ecological and physiological approaches, is required to provide the necessary experimental support to this model. (Résumé d'auteur

Using next-generation sequencing to improve DNA barcoding: lessons from a small-scale study of wild bee species (Hymenoptera, Halictidae)

International audienceAbstractThe parallel sequencing of targeted amplicons is a scalable application of next-generation sequencing (NGS) that can advantageously replace Sanger sequencing in certain DNA barcoding studies. It can be used to sequence different PCR products simultaneously, including co-amplified products. Here, we explore this approach by simultaneously sequencing five markers (including the DNA barcode and a diagnostic marker of Wolbachia) in 12 species of Halictidae that were previously DNA barcoded using Sanger sequencing. Consensus sequences were obtained from fresh bees with success rates of 74–100% depending on the DNA fragment. They improved the phylogeny of the group, detected Wolbachia infections (in 8/21 specimens) and characterised haplotype variants. Sequencing cost per marker and per specimen (11.43 €) was estimated to decrease (< 5.00 €) in studies aiming for a higher throughput. We provide guidelines for selecting NGS or Sanger sequencing depending on the goals of future studies