Laura Barrios

How natural infection by Nosema ceranae causes honeybee colony collapse.

In recent years, honeybees (Apis mellifera) have been strangely disappearing from their hives, and strong colonies have suddenly become weak and died. The precise aetiology underlying the disappearance of the bees remains a mystery. However, during the same period, Nosema ceranae, a microsporidium of the Asian bee Apis cerana, seems to have colonized A. mellifera, and its now frequently detected all over the world in both healthy and weak honeybee colonies. For first time, we show that natural N. ceranae infection can cause the sudden collapse of bee colonies, establishing a direct correlation between N. ceranae infection and the death of honeybee colonies under field conditions. Signs of colony weakness were not evident until the queen could no longer replace the loss of the infected bees. The long asymptomatic incubation period can explain the absence of evident symptoms prior to colony collapse. Furthermore, our results demonstrate that healthy colonies near to an infected one can also become infected, and that N. ceranae infection can be controlled with a specific antibiotic, fumagillin. Moreover, the administration of 120 mg of fumagillin has proven to eliminate the infection, but it cannot avoid reinfection after 6 months. We provide Kochs postulates between N. ceranae infection and a syndrome with a long incubation period involving continuous death of adult bees, non-stop brood rearing by the bees and colony loss in winter or early spring despite the presence of sufficient remaining pollen and honey.

Effect of Temperature on the Biotic Potential of Honeybee Microsporidia

ABSTRACT The biological cycle of Nosema spp. in honeybees depends on temperature. When expressed as total spore counts per day after infection, the biotic potentials of Nosema apis and N. ceranae at 33°C were similar, but a higher proportion of immature stages of N. ceranae than of N. apis were seen. At 25 and 37°C, the biotic potential of N. ceranae was higher than that of N. apis. The better adaptation of N. ceranae to complete its endogenous cycle at different temperatures clearly supports the observation of the different epidemiological patterns.

Comparison of the energetic stress associated with experimental Nosema ceranae and Nosema apis infection of honeybees (Apis mellifera)

Nosema ceranae is a relatively new and widespread parasite of the western honeybee Apis mellifera that provokes a new form of nosemosis. In comparison to Nosema apis, which has been infecting the honeybee for much longer, N. ceranae seems to have co-evolved less with this host, causing a more virulent disease. Given that N. apis and N. ceranae are obligate intracellular microsporidian parasites, needing host energy to reproduce, energetic stress may be an important factor contributing to the increased virulence observed. Through feeding experiments on caged bees, we show that both mortality and sugar syrup consumption were higher in N. ceranae-infected bees than in N. apis-infected and control bees. The mortality and sugar syrup consumption are also higher in N. apis-infected bees than in controls, but are less than in N. ceranae-infected bees. With both microsporidia, mortality and sugar syrup consumption increased in function of the increasing spore counts administered for infection. The differences in energetic requirements between both Nosema spp. confirm that their metabolic patterns are not the same, which may depend critically on host–parasite interactions and, ultimately, on host pathology. The repercussions of this increased energetic stress may even explain the changes in host behavior due to starvation, lack of thermoregulatory capacity, or higher rates of trophallaxis, which might enhance transmission and bee death.

Nosema spp. infection and its negative effects on honey bees (Apis mellifera iberiensis) at the colony level

Nosemosis caused by the microsporidia Nosema apis and Nosema ceranae are among the most common pathologies affecting adult honey bees. N. apis infection has been associated with a reduced lifespan of infected bees and increased winter mortality, and its negative impact on colony strength and productivity has been described in several studies. By contrast, when the effects of nosemosis type C, caused by N. ceranae infection, have been analysed at the colony level, these studies have largely focused on collapse as a response to infection without addressing the potential sub-clinical effects on colony strength and productivity. Given the spread and prevalence of N. ceranae worldwide, we set out here to characterize the sub-clinical and clinical signs of N. ceranae infection on colony strength and productivity. We evaluated the evolution of 50 honey bee colonies naturally infected by Nosema (mainly N. ceranae) over a one year period. Under our experimental conditions, N. ceranae infection was highly pathogenic for honey bee colonies, producing significant reductions in colony size, brood rearing and honey production. These deleterious effects at the colony level may affect beekeeping profitability and have serious consequences on pollination. Further research is necessary to identify possible treatments or beekeeping techniques that will limit the rapid spread of this dangerous emerging disease.

1H HR-MAS and genomic analysis of human tumor biopsies discriminate between high and low grade astrocytomas

We investigate the profile of choline metabolites and the expression of the genes of the Kennedy pathway in biopsies of human gliomas (n = 23) using 1H High Resolution Magic Angle Spinning (HR‐MAS, 11.7 Tesla, 277 K, 4000 Hz) and individual genetic assays. 1H HR‐MAS spectra allowed the resolution and relative quantification by the LCModel of the resonances from choline (Cho), phosphocholine (PC) and glycerophosphorylcholine (GPC), the three main components of the combined tCho peak observed in gliomas by in vivo 1H NMR spectroscopy. All glioma biopsies depicted a prominent tCho peak. However, the relative contributions of Cho, PC, and GPC to tCho were different for low and high grade gliomas. Whereas GPC is the main component in low grade gliomas, the high grade gliomas show a dominant contribution of PC. This circumstance allowed the discrimination of high and low grade gliomas by 1H HR‐MAS, a result that could not be obtained using the tCho/Cr ratio commonly used by in vivo 1H NMR spectroscopy. The expression of the genes involved in choline metabolism has been investigated in the same biopsies. High grade gliomas depict an upregulation of the β gene of choline kinase and phospholipase C, as well as a downregulation of the cytidyltransferase B gene, the balance of these being consistent with the accumulation of PC. In the low grade gliomas, phospholipase A1 and lysophospholypase are upregulated and phospholipase D is downregulated, supporting the accumulation of GPC. The present findings offer a promising procedure that will potentially help to accurately grade glioma tumors using 1H HR‐MAS, providing in addition the genetic background for the alterations of choline metabolism observed in high and low grade gliomas. Copyright

Intraventricular craniopharyngiomas: topographical classification and surgical approach selection based on an extensive overview

SummaryBackground. This retrospective study analyzes the clinical, neuroradiological, pathological and surgical characteristics of well-described intraventricular craniopharyngiomas with the aims of: (i) critically to review the criteria used to affirm the diagnosis of an intraventricular location (ii) defining more accurately this topographical diagnosis preoperatively, and (iii) to investigate factors influencing the surgical outcome.Method. Clinical, neuroradiological, pathological and surgical objective data of 104 well-described intraventricular craniopharyngiomas (IVC) reported in the literature, in addition to a new case, were analyzed. On the basis of the proofs provided for third ventricle intactness, a new topographical classification for IVC was developed, distinguishing between: (i) strict IVC, with a proved third ventricle floor integrity and (ii) non-strict IVC, without any reliable proof confirming the intactness of the third ventricle floor. Following this classification, clinical features, pathology and surgical outcome for strictly and non-strictly IVC were compared.Findings. For 105 IVC compiled, 36 belonged to the strictly group and 69 to the non-strictly group. Two pathological features were associated with the non-strictly IVC group: a preferentially adamantinomatous pattern (p=0.106) and wider and tighter adherences to third ventricle margins (p=0.01). The non-strict topography was also associated with a worse postoperative outcome (p=0.046). There was a significant relationship between the surgical approach and the final outcome (p=0.05), being the translamina terminalis approach associated with the best outcome.Conclusions. Two different topographies might be considered among IVC: strict and non-strict intraventricular location. Non-strictly IVC have wider and tighter adhesions to third ventricle boundaries and this subtype is associated with a worse outcome.

Comparison of a static and a dynamic in vitro model to estimate the bioaccessibility of As, Cd, Pb and Hg from food reference materials Fucus sp. (IAEA-140/TM) and Lobster hepatopancreas (TORT-2)

Bioaccessibility, the fraction of an element solubilized during gastrointestinal digestion and available for absorption, is a factor that should be considered when evaluating the health risk of contaminants from food. Static and dynamic models that mimic human physiological conditions have been used to evaluate bioaccessibility. This preliminary study compares the bioaccessibility of arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) in two food certified reference materials (CRMs) (seaweed: Fucus sp., IAEA-140/TM; Lobster hepatopancreas: TORT-2), using two in vitro gastrointestinal digestion methods: a static method (SM) and a dynamic multicompartment method (TIM-1). There are significant differences (p<0.05) between the bioaccessible values of As, Cd, Pb and Hg obtained by SM and TIM-1 in the two CRMs. The specific form in which the elements studied are present in the CRM may help to explain the bioaccessibility values obtained.

Displacement of mammillary bodies by craniopharyngiomas involving the third ventricle: surgical-MRI correlation and use in topographical diagnosis

OBJECT Accurate diagnosis of the topographical relationships of craniopharyngiomas (CPs) involving the third ventricle and/or hypothalamus remains a challenging issue that critically influences the prediction of risks associated with their radical surgical removal. This study evaluates the diagnostic accuracy of MRI to define the precise topographical relationships between intraventricular CPs, the third ventricle, and the hypothalamus. METHODS An extensive retrospective review of well-described CPs reported in the MRI era between 1990 and 2009 yielded 875 lesions largely or wholly involving the third ventricle. Craniopharyngiomas with midsagittal and coronal preoperative and postoperative MRI studies, in addition to detailed descriptions of clinical and surgical findings, were selected from this database (n = 130). The position of the CP and the morphological distortions caused by the tumor on the sella turcica, suprasellar cistern, optic chiasm, pituitary stalk, and third ventricle floor, including the infundibulum, tuber cinereum, and mammillary bodies (MBs), were analyzed on both preoperative and postoperative MRI studies. These changes were correlated with the definitive CP topography and type of third ventricle involvement by the lesion, as confirmed surgically. RESULTS The mammillary body angle (MBA) is the angle formed by the intersection of a plane tangential to the base of the MBs and a plane parallel to the floor of the fourth ventricle in midsagittal MRI studies. Measurement of the MBA represented a reliable neuroradiological sign that could be used to discriminate the type of intraventricular involvement by the CP in 83% of cases in this series (n = 109). An acute MBA (< 60°) was indicative of a primary tuberal-intraventricular topography, whereas an obtuse MBA (> 90°) denoted a primary suprasellar CP position, causing either an invagination of the third ventricle (pseudointraventricular lesion) or its invasion (secondarily intraventricular lesion; p < 0.01). A multivariate model including a combination of 5 variables (the MBA, position of the hypothalamus, presence of hydrocephalus, psychiatric symptoms, and patient age) allowed an accurate definition of the CP topography preoperatively in 74%-90% of lesions, depending on the specific type of relationship between the tumor and third ventricle. CONCLUSIONS The type of mammillary body displacement caused by CPs represents a valuable clue for ascertaining the topographical relationships between these lesions and the third ventricle on preoperative MRI studies. The MBA provides a useful sign to preoperatively differentiate a primary intraventricular CP originating at the infundibulotuberal area from a primary suprasellar CP, which either invaginated or secondarily invaded the third ventricle.

Optic chiasm distortions caused by craniopharyngiomas: clinical and magnetic resonance imaging correlation and influence on visual outcome.

OBJECTIVE To evaluate the anatomic distortions of the optic chiasm caused by craniopharyngiomas (CPs) and their influence on preoperative and postoperative visual status. METHODS We conducted a retrospective investigation of 150 CPs including preoperative and postoperative magnetic resonance imaging (MRI) studies and the preoperative visual status and visual outcome after surgery. Morphologic distortions of the optic chiasm were analyzed on midsagittal MRI and correlated with preoperative vision, visual outcome, and features and topography of the CP. RESULTS Vision loss before operation was present in 68.7% of the patients. The type of chiasm distortion caused by the CP was the major predictive factor of preoperative visual impairment (P < 0.001). There were 6 patterns of chiasm distortion identified: nondistorted or normal (11.3%), compressed downward (18%), compressed forward (23.3%), stretched forward (18%), stretched upward (16.7%), and stretched backward (4.7%). Reduced vision was present in >80% of compressed forward and stretched chiasms. Overall, the mechanical stretching deformation of the chiasm caused a more severe visual deficit than its compression. Postoperative chiasm morphology was the major predictive factor for visual outcome (P < 0.001). There were 6 different chiasm morphologies identified after surgery: normal (52.7%), thinned (9.4%), thickened (16.7%), displaced forward (6%), displaced upward (4%), and displaced backward (2.7%). Thinned and displaced upward chiasms were associated with the highest rate of no visual improvement. A multivariate model including preoperative and postoperative chiasm distortions predicted the visual outcome in 91.3% of patients. CONCLUSIONS The type of chiasm distortion represents a valuable neuroradiologic finding to ascertain the preoperative and postoperative visual status.

Influence of mercury bioaccessibility on exposure assessment associated with consumption of cooked predatory fish in Spain

BACKGROUND Predatory fish tend to accumulate high levels of mercury (Hg). Food safety assessment of these fish has been carried out on the raw product. However, the evaluation of the risk from Hg concentrations in raw fish might be modified if cooking and bioaccessibility (the contaminant fraction that solubilises from its matrix during gastrointestinal digestion and becomes available for intestinal absorption) were taken into account. Data on Hg bioaccessibility in raw predatory fish sold in Spain are scarce and no research on Hg bioaccessibility in cooked fish is available. The aim of the present study was to evaluate Hg bioaccessibility in various kinds of cooked predatory fish sold in Spain to estimate their health risk. RESULTS Both Hg and bioaccessible Hg concentrations were analysed in raw and cooked fish (swordfish, tope shark, bonito and tuna). There were no changes in Hg concentrations during cooking. However, Hg bioaccessibility decreased significantly after cooking (42 ± 26% in raw fish and 26 ± 16% in cooked fish), thus reducing in swordfish and tope shark the Hg concentration to which the human organism would be exposed. CONCLUSION In future, cooking and bioaccessibility should be considered in risk assessment of Hg concentrations in predatory fish.