153 research outputs found

    Brain aromatase activity and plasma testosterone levels are elevated in aggressive male mice during early ontogeny

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    Testosterone (T) and estradiol (E(2)) are involved in intraspecific aggressive behavior. Both steroids exert their effects on behavior via the hypothalamus and the amygdala (Am) of the central nervous system (CNS). In these brain areas T is converted to E(2), by the enzyme aromatase. Both the levels of brain aromatase activity (AA) and the effects of T and E(2) on aggressive behavior in adulthood depend on steroidal organization of the CNS during ontogeny. In this study we measured plasma T and in vitro brain AA of male fetuses and neonates derived from two strains of wild house mice, which had been genetically selected for aggression, based upon attack latency. There were no differences in preoptic area (POA) AA levels between selection lines on either embryonic day (E) 17 or 18, or the day after birth (day 1). In the non-aggressive long attack latency (LAL) males the POA AA increases with age, i.e. was higher on E18 than on E17, which is correlated with brain weight (BrW). This was in contrast to aggressive short attack latency (SAL) fetuses, which only showed a slight, but not significant difference between embryonic days or, a correlation with BrW. Neonatally, the POA AA of LAL males tended to decrease in contrast to SAL males. However, SAL neonates had a higher AA in the amygdala (Am) than LAL neonates, whereas no differences exist in the anterior hypothalamus. Thus, a differential brain AA distribution exists in SAL and LAL pups. At day 1 SAL: males show higher AA in the Am than in the hypothalamus (POA + AH), whereas in the LAL strain the AA did not differ between these brain areas. In the LAL males plasma T levels decreased from E17 to day 1, whereas the SAL neonates (day 1) exhibited higher circulating T concentrations than LAL neonates. These results suggest a T-independent aromatase induction prenatally in both selection lines, whereas neonatally the higher plasma T level in the SAL line coincides with higher AA levels:in the Am. Accordingly, a differential pattern of E(2) formation exists in the brains of the two selection lines during ontogeny. The variation in circulating T and maximal brain E(2) formation around birth might result in a differential organization of adult CNS sensitivity to sex steroids and accordingly differences in aggressive behavior.</p

    Fate of Escherichia coli O145 present naturally in bovine slurry applied to vegetables before harvest, after washing and simulated wholesale and retail distribution

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    Aims: To determine the fate of E. coli on vegetables that were processed through commercial wash treatments and stored under simulated retail conditions at 4oC or wholesale at fluctuating ambient temperatures (0-25oC, dependent on season). Methods and Results: Bovine slurry that was naturally contaminated with Escherichia coli O145 was applied without dilution or diluted 1/10 using borehole water to growing potatoes, leeks or carrots. Manure was applied one week prior to harvest to simulate a near-harvest contamination event by manure deposition or an application of contaminated water to simulate a flooding event or irrigation from a contaminated water source. At harvest, crops were contaminated at up to two log cfu/g. Washing transferred E. coli into the water of a flotation tank used for potato washing and did not completely remove all traces of contamination from the crop. Manure contaminated potatoes were observed to contain 0.72 cfu E. coli O145/g after processing and retail storage. Manure-contaminated leeks harboured 0.73 – 1.55 cfu E. coli O145/g after washing and storage. There was no cross contamination when leeks were spray-washed. Washing in an abrasive drum resulted in less than perfect decontamination for manure-contaminated carrots. There were five post-distribution isolations from carrots irrigated with contaminated water 24h prior to harvest. Conclusions: Standard commercial washing and distribution conditions may be insufficient to reliably control human pathogenic E. coli on fresh produce. Significance and Impact: Previous speculation that the cause of a UK foodborne disease outbreak was soil from imperfectly cleaned vegetables is plausible

    A quantitative approach towards a better understanding of the dynamics of Salmonella spp. in a pork slaughter-line.

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    Pork contributes significantly to the public health disease burden caused by Salmonella infections. During the slaughter process pig carcasses can become contaminated with Salmonella. Contamination at the slaughter-line is initiated by pigs carrying Salmonella on their skin or in their faeces. Another contamination route could be resident flora present on the slaughter equipment. To unravel the contribution of these two potential sources of Salmonella a quantitative study was conducted. Process equipment (belly openers and carcass splitters), faeces and carcasses (skin and cutting surfaces) along the slaughter-line were sampled at 11 sampling days spanning a period of 4 months. Most samples taken directly after killing were positive for Salmonella. On 96.6% of the skin samples Salmonella was identified, whereas a lower number of animals tested positive in their rectum (62.5%). The prevalence of Salmonella clearly declined on the carcasses at the re-work station, either on the cut section or on the skin of the carcass or both (35.9%). Throughout the sampling period of the slaughter-line the total number of Salmonella per animal was almost 2log lower at the re-work station in comparison to directly after slaughter. Seven different serovars were identified during the study with S. Derby (41%) and S. Typhimurium (29%) as the most prominent types. A recurring S. Rissen contamination of one of the carcass splitters indicated the presence of an endemic 'house flora' in the slaughterhouse studied. On many instances several serotypes per individual sample were found. The enumeration of Salmonella and the genotyping data gave unique insight in the dynamics of transmission of this pathogen in a slaughter-line. The data of the presented study support the hypothesis that resident flora on slaughter equipment was a relevant source for contamination of pork

    Allaeochelys libyca, a new carettochelyine turtle from the middle miocene (Langhian) of Libya

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    Fossil carettochelyine turtles are well known from the Paleogene of Europe (Allaeochelys), North America and Asia (Anosteira); however, the previously known Neogene fossil record is highly fragmentary and was therefore unsuitable for taxonomic analysis. In this work, we present a new carettochelyine taxon, Allaeochelys libyca, from the Middle Miocene (Langhian) of Gebel Zelten (Libya) based on an incomplete skull and disarticulated postcranial elements. The new taxon is diagnosed relative to the extant Carettochelys insculpta based on the placement of the foramen posterius canalis carotici interni close to the fenestra postotica, the horizontal orientation of the tubercula basioccipitalis, the substantial contribution of the opisthotic to the base of the tubercula basioccipitalis, the presence of a triangular pterygoid fossa, the arrangement of the mandibular condyles along a plane and the presence of an extremely well-developed fossa at the base of the processus mandibularis. A phylogenetic analysis of pancarettochelyids confirms the monophyly of Carettochelyidae and Carettochelyinae but resulted in a paraphyletic taxon, Allaeochelys. For the sake of nomenclatural stability, we provisionally retain the genus Allaeochelys as paraphyletic relative to the extant Carettochelys insculpta

    Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the Ultraviolet Anomaly in NGC 5548 with X-Ray Spectroscopy

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    During the Space Telescope and Optical Reverberation Mapping Project observations of NGC 5548, the continuum and emission-line variability became decorrelated during the second half of the six-month-long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as part of the campaign. The Swift spectra show that excess flux (relative to a power-law continuum) in the soft X-ray band appears before the start of the anomalous emission-line behavior, peaks during the period of the anomaly, and then declines. This is a model-independent result suggesting that the soft excess is related to the anomaly. We divide the Swift data into on- and off-anomaly spectra to characterize the soft excess via spectral fitting. The cause of the spectral differences is likely due to a change in the intrinsic spectrum rather than to variable obscuration or partial covering. The Chandra spectra have lower signal-to-noise ratios, but are consistent with the Swift data. Our preferred model of the soft excess is emission from an optically thick, warm Comptonizing corona, the effective optical depth of which increases during the anomaly. This model simultaneously explains all three observations: the UV emission-line flux decrease, the soft-excess increase, and the emission-line anomaly

    Parsec-scale polarization of the jet in quasar 4C71.07

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    SIGLEAvailable from British Library Document Supply Centre-DSC:DXN026780 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

    Aromatase Activity in the Preoptic Area Differs Between Aggressive and Nonaggressive Male House Mice

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    Treatment with testosterone (T) or estradiol (E2) facilitates intraspecific aggressive behavior in adult rodents. Brain aromatization of T to E2 appears to be involved in facilitation of fighting behavior. In the present study we measure the in vitro brain aromatase activity (AA) in the preoptic area (POA), amygdaloid nuclei (Am), ventromedial hypothalamus (VMH), and parietal cortex (CTX) from two strains of adult male house mice, which were genetically selected for territorial aggression, based upon their attack latencies (short attack latency: SAL; long attack latency: LAL). The results reveal a higher AA in the POA of nonaggressive LAL males, as compared to aggressive SAL animals. The POA AA is, thus, inversely correlated with aggressiveness. The AA levels in both the VMH and Am do not differ significantly between strains. Furthermore, a differential brain area-specific AA distribution exists: POA > VMH AA in LAL, whereas POA < VMH in SAL. In both selection lines, the Am exhibits the highest levels of AA, as compared to the other investigated areas. Kinetic studies revealed that the aromatase Km is similar in both strains. The results indicate that the strain difference in AA is specific to the POA, but is not necessarily positivefy correlated with circulating plasma T levels. Other factors, in addition to androgen, are probably involved in the regulation of POA aromatase. We suggest that a higher neural androgen receptor sensitivity exists in the POA of nonaggressive LAL males, resulting in higher adult POA AA, despite lower concentrations of circulating T.
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