Maternal Expression Relaxes Constraint on Innovation of the Anterior Determinant, bicoid

The origin of evolutionary novelty is believed to involve both positive selection and relaxed developmental constraint. In flies, the redesign of anterior patterning during embryogenesis is a major developmental innovation and the rapidly evolving Hox gene, bicoid (bcd), plays a critical role. We report evidence for relaxation of selective constraint acting on bicoid as a result of its maternal pattern of gene expression. Evolutionary theory predicts 2-fold greater sequence diversity for maternal effect genes than for zygotically expressed genes, because natural selection is only half as effective acting on autosomal genes expressed in one sex as it is on genes expressed in both sexes. We sample an individual from ten populations of Drosophila melanogaster and nine populations of D. simulans for polymorphism in the tandem gene duplicates bcd, which is maternally expressed, and zerknüllt (zen), which is zygotically expressed. In both species, we find the ratio of bcd to zen nucleotide diversity to be two or more in the coding regions but one in the noncoding regions, providing the first quantitative support for the theoretical prediction of relaxed selective constraint on maternal-effect genes resulting from sex-limited expression. Our results suggest that the accelerated rate of evolution observed for bcd is owing, at least partly, to variation generated by relaxed selective constraint

Computerised tomography indices of raised intracranial pressure and traumatic brain injury severity in a New Zealand sample

After traumatic brain injury (TBI) complex cellular and biochemical processes occur¹ including changes in blood flow and oxygenation of the brain; cerebral swelling; and raised intracranial pressure (ICP).² This can dramatically worsen the damage³ and contributes to mortality

Reading Instruction for Children who use AAC: Considerations in the Pursuit of Generalizable Results

Our purpose was to review evidence-based literacy instruction for children with severe speech impairment (SSI) who communicate with AAC. This review focuses on three issues important to researchers in this area: participant heterogeneity, assessment and instruction, and research design. We found 8 articles that reported attempts to teach phonological awareness and individual-word reading to a total of 26 children with SSI who used AAC. We evaluated these studies based on reporting of participant characteristics, assessment and instruction modifications, and the strength of research designs. We conclude by highlighting the need for standard assessments that can be used across studies, discussing strategies for facilitating metaanalyses, and suggesting the creation of an online database for researchers to share results on literacy instruction for this population

Inertial wave turbulence driven by elliptical instability

The combination of elliptical deformation of streamlines and vorticity can lead to the destabilisation of any rotating flow via the elliptical instability. Such a mechanism has been invoked as a possible source of turbulence in planetary cores subject to tidal deformations. The saturation of the elliptical instability has been shown to generate turbulence composed of non-linearly interacting waves and strong columnar vortices with varying respective amplitudes, depending on the control parameters and geometry. In this paper, we present a suite of numerical simulations to investigate the saturation and the transition from vortex-dominated to wave-dominated regimes. This is achieved by simulating the growth and saturation of the elliptical instability in an idealised triply periodic domain, adding a frictional damping to the geostrophic component only, to mimic its interaction with boundaries. We reproduce several experimental observations within one idealised local model and complement them by reaching more extreme flow parameters. In particular, a wave-dominated regime that exhibits many signatures of inertial wave turbulence is characterised for the first time. This regime is expected in planetary interiors

Performance of Hamamatsu 64-anode photomultipliers for use with wavelength--shifting optical fibres

Hamamatsu R5900-00-M64 and R7600-00-M64 photomultiplier tubes will be used with wavelength--shifting optical fibres to read out scintillator strips in the MINOS near detector. We report on measurements of the gain, efficiency, linearity, crosstalk, and dark noise of 232 of these PMTs, of which 219 met MINOS requirements.Comment: 15 pages, 12 figures. Accepted by Nucl. Inst. Meth.

Why does early childhood deprivation increase the risk for depression and anxiety in adulthood? A developmental cascade model

Abstract Background: Using data from the English & Romanian Adoptees (ERA) study we recently reported that early time-lmited exposure to severe institutional deprivation is associated with early onset and persistent neurodevelopmental problems and later onset emotional problems. Here we examine possible reasons for the late emergence of emotional problems in this cohort. Our main focus is on testing a developmental cascade mediated via the functional impact of early-appearing neurodevelopmental problems on late adolescent functioning. We also explore a second putative pathway via sensitization to stress. Methods: The ERA study includes 165 Romanian individuals who spent their early lives in grossly depriving institutions and were subsequently adopted into UK families, along with 52 UK adoptees with no history of deprivation. Age six years symptoms of neurodevelopmental problems and age 15 anxiety/depression symptoms were assessed via parental reports. Young adult symptoms of depression and anxiety were assessed by both parent and self-reports; young adults also completed measures of stress reactivity , exposure to adverse life events and functioning in work and interpersonal relationships. Results: The path between early institutional deprivation and adult emotional problems was mediated via the impact of early neurodevelopmental problems on unemployment and poor friendship functioning during the transition to adulthood. The findings with regard to early deprivation, later life stress reactivity and emotional problems were inconclusive. Conclusions: Our analysis suggests that the risk for adult depression and anxiety following extreme institutional deprivation is explained through the effects of early neurodevelopmental problems on later social and vocational functioning. Future research should more fully examine the role of stress susceptibility in this model

Productivity of Osprey, Pandion haliaetus, Nesting on Natural and Artificial Structures in the Kawartha Lakes, Ontario, 1991-2001

Ospreys (Pandion haliaetus) declined throughout the Great Lakes basin during the 1950s to 1970s due to usage of organochlorine pesticides. Following the banning of DDT in 1972, artificial elevated nest structures were erected in the Kawartha Lakes region of south-central Ontario to aid in their recovery. As the population grew, large stumps of flooded trees, < 1 m above the surface of the water became important nesting sites, despite their propensity to flood in turbulent weather conditions. We compared the productivity of Ospreys among nest substrates and longevity of the nests in this area from 1991 to 2001. Of 260 individual nesting attempts made over the 11 years, 57% used man-made structures, primarily either quadrupod nesting platforms or utility poles. Of nests on natural substrates, stump nests accounted for 37% of total nesting attempts; elevated tree nests were relatively uncommon (6%). Productivity of stump nests was significantly greater than that of artificial or tree nests (1.48 versus 1.16 and 0.73 chicks produced per occupied nest, respectively). Nevertheless, survivorship of stump nests was less than that of platform nests after 3 years of age, as high water levels, storms or winter ice activity destroyed some of these low nests between breeding seasons. Ospreys were able to attain greater productivity in these stump nests than on man-made nesting substrates