426 research outputs found
Clonal expansion of sequence type (ST-)5 and emergence of ST-7 in serogroup A meningococci, Africa.
One hundred four serogroup A meningococci in our collection, isolated in Africa from 1988 to 1999, were characterized by multilocus sequence typing (MLST). Our results and data from the Internet indicate that sequence type 5 (ST-5) strains were responsible for most of African outbreaks and sporadic cases during this period. In 1995, a new clone, characterized by ST-7 sequence, emerged and was responsible for severe outbreaks in Chad (1998) and Sudan (1999). MLST and epidemiologic data indicate that ST-5 and ST-7 represent two virulent clones. These two STs, which belong to subgroup III, differ only in the pgm locus: allele pgm3 is characteristic for ST-5 and allele pgm19 for ST-7. Subgroup III strains were responsible for two pandemics in the 1960s and 1980s. Our data show that the third subgroup III pandemic has now reached Africa
Lateralization (handedness) in Magellanic penguins
Lateralization, or asymmetry in form and/or function, is found in many animal species. Brain lateralization is considered adaptive for an individual, and often results in “handedness,” “footedness,” or a side preference, manifest in behavior and morphology. We tested for lateralization in several behaviors in a wild population of Magellanic penguins Spheniscus magellanicus breeding at Punta Tombo, Argentina. We found no preferred foot in the population (each penguin observed once) in stepping up onto an obstacle: 53% stepped up with the right foot, 47% with the left foot (n = 300, binomial test p = 0.27). We found mixed evidence for a dominant foot when a penguin extended a foot for thermoregulation, possibly depending on the ambient temperature (each penguin observed once). Penguins extended the right foot twice as often as the left foot (n = 121, p < 0.0005) in 2 years when we concentrated our effort during the heat of the day. In a third year when we observed penguins early and late in the day, there was no preference (n = 232, p = 0.59). Penguins use their flippers for swimming, including searching for and chasing prey. We found morphological evidence of a dominant flipper in individual adults: 60.5% of sternum keels curved one direction or the other (n = 76 sterna from carcasses), and 11% of penguins had more feather wear on one flipper than the other (n = 1217). Right-flippered and left-flippered penguins were equally likely in both samples (keels: p = 0.88, feather wear: p = 0.26), indicating individual but not population lateralization. In fights, aggressive penguins used their left eyes preferentially, consistent with the right side of the brain controlling aggression. Penguins that recently fought (each penguin observed once) were twice as likely to have blood only on the right side of the face (69%) as only on the left side (31%, n = 175, p < 0.001). The proportion of penguins with blood only on the right side increased with the amount of blood. In most fights, the more aggressive penguin used its left eye and attacked the other penguin’s right side. Lateralization depended on the behavior tested and, in thermoregulation, likely on the temperature. We found no lateralization or mixed results in the population of Magellanic penguins in three individual behaviors, stepping up, swimming, and thermoregulation. We found lateralization in the population in the social behavior fighting
Trading Efficiency of Fund Families: Impact on Fund Performance and Investment Behavior
Mutual funds are part of larger organizations, which make decisions with consequences for all their member funds. This study examines how the efficiency of trading desks operated by fund families affects the performance and trading of affiliated funds. We introduce a novel approach to measure the efficiency of trading desks, which allows for comparisons across families with different investable universes. By operating efficient trading desks, which reduce trading costs, fund families improve the performance of their funds significantly. Furthermore, the lower trading costs resulting from more efficient trading desks enable mutual funds to trade more and hold less liquid portfolios
Genome-wide association analysis of dementia and its clinical endophenotypes reveal novel loci associated with Alzheimer's disease and three causality networks: The GR@ACE project
INTRODUCTION: Large variability among Alzheimer's disease (AD) cases might impact genetic discoveries and complicate dissection of underlying biological pathways. METHODS: Genome Research at Fundacio ACE (GR@ACE) is a genome-wide study of dementia and its clinical endophenotypes, defined based on AD's clinical certainty and vascular burden. We assessed the impact of known AD loci across endophenotypes to generate loci categories. We incorporated gene coexpression data and conducted pathway analysis per category. Finally, to evaluate the effect of heterogeneity in genetic studies, GR@ACE series were meta-analyzed with additional genome-wide association study data sets. RESULTS: We classified known AD loci into three categories, which might reflect the disease clinical heterogeneity. Vascular processes were only detected as a causal mechanism in probable AD. The meta-analysis strategy revealed the ANKRD31-rs4704171 and NDUFAF6-rs10098778 and confirmed SCIMP-rs7225151 and CD33-rs3865444. DISCUSSION: The regulation of vasculature is a prominent causal component of probable AD. GR@ACE meta-analysis revealed novel AD genetic signals, strongly driven by the presence of clinical heterogeneity in the AD series
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