Habitat-specific variation in gut microbial communities and pathogen prevalence in bumblebee queens (Bombus terrestris).

Gut microbial communities are critical for the health of many insect species. However, little is known about how gut microbial communities respond to anthropogenic changes and how such changes affect host-pathogen interactions. In this study, we used deep sequencing to investigate and compare the composition of gut microbial communities within the midgut and ileum (both bacteria and fungi) in Bombus terrestris queens collected from natural (forest) and urbanized habitats. Additionally, we investigated whether the variation in gut microbial communities under each habitat affected the prevalence of two important bumblebee pathogens that have recently been associated with Bombus declines (Crithidia bombi and Nosema bombi). Microbial community composition differed strongly among habitat types, both for fungi and bacteria. Fungi were almost exclusively associated with bumblebee queens from the forest habitats, and were not commonly detected in bumblebee queens from the urban sites. Further, gut bacterial communities of urban B. terrestris specimens were strongly dominated by bee-specific core bacteria like Snodgrassella (Betaproteobacteria) and Gilliamella (Gammaproteobacteria), whereas specimens from the forest sites contained a huge fraction of environmental bacteria. Pathogen infection was very low in urban populations and infection by Nosema was only observed in specimens collected from forest habitats. No significant relationship was found between pathogen prevalence and microbial gut diversity. However, there was a significant and negative relationship between prevalence of Nosema and relative abundance of the core resident Snodgrassella, supporting its role in pathogen defense. Overall, our results indicate that land-use change may lead to different microbial gut communities in bumblebees, which may have implications for bumblebee health, survival and overall fitness.

Agar composition affects in vitro screening of biocontrol activity of antagonistic microorganisms.

Agar-based screening assays are the method of choice when evaluating antagonistic potential of bacterial biocontrol-candidates against pathogens. We showed that when using the same medium, but different agar compositions, the activity of a bacterial antagonist against Agrobacterium was strongly affected. Consequently, results from in vitro screenings should be interpreted cautiously.

Efficacy of hydrogen peroxide treatment for control of hairy root disease caused by rhizogenic agrobacteria.

AIMS: Rhizogenic Agrobacterium strains are the causative agent of hairy root disease (HRD), an increasing problem in the hydroponic cultivation of tomato and cucumber in Europe. A previous study has demonstrated that different lineages of rhizogenic agrobacteria are able to form biofilms. Although hydrogen peroxide (H2 O2 ) is a frequently used biocide in hydroponic systems, until now its effectiveness to remove rhizogenic agrobacteria has not been unequivocally demonstrated. Therefore, the main objective of this study was to assess the efficacy of H2 O2 in controlling Agrobacterium-containing biofilms. METHODS AND RESULTS: Using lab-scale experiments, we found a huge variation between different rhizogenic Agrobacterium strains in EC50 values, ranging from 18·8 to 600 ppm H2 O2 , representing the lowest and highest concentration tested respectively. Using pilot-scale experiments in which different H2 O2 concentrations were tested, treatment with 25 ppm H2 O2 was found to be ineffective. In contrast, treatment with 50 ppm significantly affected a catalase-negative Agrobacterium population, while a catalase-positive population was only marginally affected. For the catalase-positive Agrobacterium population, a treatment of 100 ppm H2 O2 was required to be effective. Finally, H2 O2 treatment of HRD in two commercial greenhouses was monitored, and showed that the H2 O2 concentration decreased considerably towards the end of the irrigation circuits. Further, a clear correlation was found between the actual concentration of H2 O2 and the incidence of HRD. CONCLUSION: We showed that H2 O2 may be effective to reduce biofilm formation by rhizogenic bacteria. Nevertheless, it was clear from our results that the required H2 O2 concentration depends on the particular Agrobacterium strain(s) present in the greenhouse. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study that examined the effectiveness of H2 O2 to control HRD in hydroponic systems, and the effect of catalase activity on H2 O2 effectiveness. Our study has direct relevance for the highly intensive horticultural sector.

Functional knee axis based on isokinetic dynamometry data: Comparison of two methods, MRI validation, and effect on knee joint kinematics.

This paper compares geometry-based knee axes of rotation (transepicondylar axis and geometric center axis) and motion-based functional knee axes of rotation (fAoR). Two algorithms are evaluated to calculate fAoRs: Gamage and Lasenby's sphere fitting algorithm (GL) and Ehrig et al.'s axis transformation algorithm (SARA). Calculations are based on 3D motion data acquired during isokinetic dynamometry. AoRs are validated with the equivalent axis based on static MR-images. We quantified the difference in orientation between two knee axes of rotation as the angle between the projection of the axes in the transversal and frontal planes, and the difference in location as the distance between the intersection points of the axes with the sagittal plane. Maximum differences between fAoRs resulting from GL and SARA were 5.7° and 15.4mm, respectively. Maximum differences between fAoRs resulting from GL or SARA and the equivalent axis were 5.4°/11.5mm and 8.6°/12.8mm, respectively. Differences between geometry-based axes and EA are larger than differences between fAoR and EA both in orientation (maximum 10.6°).and location (maximum 20.8mm). Knee joint angle trajectories and the corresponding accelerations for the different knee axes of rotation were estimated using Kalman smoothing. For the joint angles, the maximum RMS difference with the MRI-based equivalent axis, which was used as a reference, was 3°. For the knee joint accelerations, the maximum RMS difference with the equivalent axis was 20°/s(2). Functional knee axes of rotation describe knee motion better than geometry-based axes. GL performs better than SARA for calculations based on experimental dynamometry.

Use of the palmaris brevis flap for preventing recurrent median nerve compression in mucolipidosis.

In a patient with severe, recurrent bilateral carpal tunnel syndrome secondary to mucolipidosis, the 'turnover' palmaris brevis flap was used in conjunction with internal neurolysis. The procedure was effective in alleviating symptoms of recurrent carpal tunnel compression in both hands.

Scanning electron microscopic study of thrombus formation in an end-to-side anastomosis of the rat carotid artery.

The healing of conventional microvascular end-to-side anastomoses has been reported in several studies. The authors studied thrombus formation under scanning electron microscopy (SEM) in an end-to-side anastomotic model in rat carotid arteries. Twenty anastomoses were carried out with 10-0 nylon interrupted sutures. Thrombus formation was evaluated 30 min after clamp release. The findings indicated that the first 30 min are the most critical time for thrombus formation. Thrombi underwent partial lysis or embolization after this time, and gross intraluminal thrombi did not recur. Thrombus formation was studied at four different sites in the end-to-side anastomoses. The sites of needle holes and sutures were primary locations for thrombocyte adhesions and aggregations in normal, vascular anastomoses.

Perineal repair of procidentia recti with a silastic sling.

Several operations have been proposed to correct complete rectal prolapse (1, 2, 3, 4). Perineal approaches in patients with rectal prolapse are recognized as less strenuous on the general health of the patient than abdominal methods of repair. This has led to the use of perineal procedures for elderly and debilitated patients. In our text we describe a perineal repair with a silastic sling. In general this technique is designed to treat the prolapse by narrowing of the anal outlet and suspension of the rectum.

Chronic anemia secondary to side-to-side distal small bowel anastomosis.

Occult intestinal bleeding was diagnosed in a patient who underwent a distal small bowel resection. The resection was required for small bowel obstruction. She developed iron deficiency anemia four years later. Clinically she presented with melena. Colonoscopy, gastroscopy were unsuccessful in making the diagnosis. But a 99 mass Technetium (99m Tc) Labeled Red Blood Cell (RBC) scintigraphy, established the bleeding site in the gastrointestinal tract. Laparotomy identified an ulcerative lesion at the surgical side-to-side anastomosis. Histology demonstrated focal ulceration with chronic inflammation but did not show crypt abscesses, or granulomata. Medical therapy, including iron and Histamine-antagonists were ineffective. She was treated with resection of the anastomosis. Gastrointestinal bleeding due to anastomotic ulceration appears to be a late complication of small bowel resection with side-to-side anastomosis.

A pseudotumoral edema of the urinary bladder secondary to an intramural impacted ureteral lithiasis.

A case of pseudotumor of the urinary bladder secondary to intramural lithiasis is reported. Computer tomography, cystoscopy of the mass and cytology suggested a malignant tumor. A transurethral biopsy from the tumor was therefore performed, but it showed tissue covered with normal transitional cell epithelium but no signs of malignancy. Pseudotumoral edema of the bladder is easily mistaken for a malignant neoplasm (1, 2, 3).