4,380 research outputs found
Transgendered in Alaska: Navigating the Changing Legal Landscape for Change in Gender Petitions
Background: Detecting intracellular bacterial symbionts can be challenging when they persist at very low densities. Wolbachia, a widespread bacterial endosymbiont of invertebrates, is particularly challenging. Although it persists at high titers in many species, in others its densities are far below the detection limit of classic end-point Polymerase Chain Reaction (PCR). These low-titer infections can be reliably detected by combining PCR with DNA hybridization, but less elaborate strategies based on end-point PCR alone have proven less sensitive or less general. Results: We introduce a multicopy PCR target that allows fast and reliable detection of A-supergroup Wolbachia -even at low infection titers -with standard end-point PCR. The target is a multicopy motif (designated ARM: A-supergroup repeat motif) discovered in the genome of wMel (the Wolbachia in Drosophila melanogaster). ARM is found in at least seven other Wolbachia A-supergroup strains infecting various Drosophila, the wasp Muscidifurax and the tsetse fly Glossina. We demonstrate that end-point PCR targeting ARM can reliably detect both high-and low-titer Wolbachia infections in Drosophila, Glossina and interspecific hybrids. Conclusions: Simple end-point PCR of ARM facilitates detection of low-titer Wolbachia A-supergroup infections. Detecting these infections previously required more elaborate procedures. Our ARM target seems to be a general feature of Wolbachia A-supergroup genomes, unlike other multicopy markers such as insertion sequences (IS)
Silver-spoon upbringing improves early-life fitness but promotes reproductive ageing in a wild bird
Early-life conditions can have long-lasting effects and organisms that experience a poor start in life are often expected to age at a faster rate. Alternatively, individuals raised in high-quality environments can overinvest in early-reproduction resulting in rapid ageing. Here we use a long-term experimental manipulation of early-life conditions in a natural population of collared flycatchers (Ficedula albicollis), to show that females raised in a low-competition environment (artificially reduced broods) have higher early-life reproduction but lower late-life reproduction than females raised in high-competition environment (artificially increased broods). Reproductive success of high-competition females peaked in late-life, when low-competition females were already in steep reproductive decline and suffered from a higher mortality rate. Our results demonstrate that ‘silver-spoon’ natal conditions increase female early-life performance at the cost of faster reproductive ageing and increased late-life mortality. These findings demonstrate experimentally that natal environment shapes individual variation in reproductive and actuarial ageing in nature
Drosophila mitoferrin is essential for male fertility: evidence for a role of mitochondrial iron metabolism during spermatogenesis
<p>Abstract</p> <p>Background</p> <p>Mammals and <it>Drosophila melanogaster </it>share some striking similarities in spermatogenesis. Mitochondria in spermatids undergo dramatic morphological changes and syncytial spermatids are stripped from their cytoplasm and then individually wrapped by single membranes in an individualization process. In mammalian and fruit fly testis, components of the mitochondrial iron metabolism are expressed, but so far their function during spermatogenesis is unknown. Here we investigate the role of <it>Drosophila </it>mitoferrin (dmfrn), which is a mitochondrial carrier protein with an established role in the mitochondrial iron metabolism, during spermatogenesis.</p> <p>Results</p> <p>We found that P-element insertions into the 5'-untranslated region of the <it>dmfrn </it>gene cause recessive male sterility, which was rescued by a fluorescently tagged transgenic <it>dmfrn </it>genomic construct (<it>dmfrn<sup>venus</sup></it>). Testes of mutant homozygous <it>dmfrn<sup>SH115 </sup></it>flies were either small with unorganized content or contained some partially elongated spermatids, or testes were of normal size but lacked mature sperm. Testis squashes indicated that spermatid elongation was defective and electron micrographs showed mitochondrial defects in elongated spermatids and indicated failed individualization. Using a <it>LacZ </it>reporter and the <it>dmfrn<sup>venus </sup></it>transgene, we found that dmfrn expression in testes was highest in spermatids, coinciding with the stages that showed defects in the mutants. Dmfrn-venus protein accumulated in mitochondrial derivatives of spermatids, where it remained until most of it was stripped off during individualization and disposed of in waste bags. Male sterility in flies with the hypomorph alleles <it>dmfrn<sup>BG00456 </sup></it>and <it>dmfrn<sup>EY01302 </sup></it>over the deletion <it>Df(3R)ED6277 </it>was increased by dietary iron chelation and suppressed by iron supplementation of the food, while male sterility of <it>dmfrn<sup>SH115</sup>/Df(3R)ED6277 </it>flies was not affected by food iron levels.</p> <p>Conclusions</p> <p>In this work, we show that mutations in the <it>Drosophila </it>mitoferrin gene result in male sterility caused by developmental defects. From the sensitivity of the hypomorph mutants to low food iron levels we conclude that mitochondrial iron is essential for spermatogenesis. This is the first time that a link between the mitochondrial iron metabolism and spermatogenesis has been shown. Furthermore, due to the similar expression patterns of some mitochondrial iron metabolism genes in <it>Drosophila </it>and mammals, it is likely that our results are applicable for mammals as well.</p
LTE or non-LTE, that is the question
Strontium has proven itself to be one of the most important neutron-capture
elements in the study of metal-poor stars. Thanks to the strong absorption
lines of Sr, they can be detected even in the most metal-poor stars and also in
low-resolution spectra. However, we still cannot explain the large star-to-star
abundance scatter we derive for metal-poor stars. Here we contrast Galactic
chemical evolution (GCE) with improved abundances for SrI+II including updated
atomic data, to evaluate possible explanations for the large star-to-star
scatter at low metallicities. We derive abundances under both local
thermodynamic equilibrium (LTE) and non-LTE (NLTE) for stars spanning a large
interval of stellar parameters. Gravities and metallicities are also determined
in NLTE. We confirm that the ionisation equilibrium between SrI and SrII is
satisfied under NLTE but not LTE, where the difference between SrI and SrII is
on average ~0.3dex. We show that the NLTE corrections are of increasing
importance as the metallicity decreases. For the stars with [Fe/H]>-3 the SrI
NLTE correction is ~0.35/0.55dex in dwarfs/giants, while the Sr II NLTE
correction is +/-0.05dex. On the basis of the large NLTE corrections, SrI
should not be applied as a chemical tracer under LTE, while it is a good tracer
under NLTE. SrII is a good tracer under both LTE and NLTE (down to [Fe/H]\sim
-3), and LTE is a safe assumption for this majority species. However, the Sr
abundance from SrII lines is dependent on an accurate surface gravity
determination, which can be obtained from NLTE spectroscopy of Fe lines or from
parallax measurements. We could not explain the star-to-star scatter (which
remains under both LTE and NLTE) by the use of the GCE model, since the Sr
yields to date are too uncertain to draw firm conclusions. At least two
production sites seem necessary in order to account for this large scatter
(abridged).Comment: 14 pages, 12 figures and one online table (accepted by A&A
Complexity Measures from Interaction Structures
We evaluate new complexity measures on the symbolic dynamics of coupled tent
maps and cellular automata. These measures quantify complexity in terms of
-th order statistical dependencies that cannot be reduced to interactions
between units. We demonstrate that these measures are able to identify
complex dynamical regimes.Comment: 11 pages, figures improved, minor changes to the tex
On angular momentum of gravitational radiation
The quasigroup approach to the conservation laws (Phys. Rev. D56, R7498
(1997)) is completed by imposing new gauge conditions for asymptotic
symmetries. Noether charge associated with an arbitrary element of the
Poincar\'e quasialgebra is free from the supertranslational ambiquity and
identically vanishes in a flat spacetimeComment: Revtex4 styl
Superdiffusion of massive particles induced by multi-scale velocity fields
We study drag-induced diffusion of massive particles in scale-free velocity
fields, where superdiffusive behavior emerges due to the scale-free size
distribution of the vortices of the underlying velocity field. The results show
qualitative resemblance to what is observed in fluid systems, namely the
diffusive exponent for the mean square separation of pairs of particles and the
preferential concentration of the particles, both as a function of the response
time.Comment: 5 pages, 5 figures. Accepted for publication in EP
A Measurement of 'Walking-the-Wall' Dynamics: An Observational Study Using Accelerometry and Sensors to Quantify Risk Associated with Vertical Wall Impact Attenuation in Trampoline Parks.
This study illustrates the application of a tri-axial accelerometer and gyroscope sensor device on a trampolinist performing the walking-the-wall manoeuvre on a high-performance trampoline to determine the performer dynamic conditions. This research found that rigid vertical walls would allow the trampolinist to obtain greater control and retain spatial awareness at greater levels than what is achievable on non-rigid vertical walls. With a non-rigid padded wall, the reaction force from the wall can be considered a variable force that is not constrained, and would not always provide the feedback that the trampolinist needs to maintain the balance with each climb up the wall and fall from height. This research postulates that unattenuated vertical walls are safer than attenuated vertical walls for walking-the-wall manoeuvres within trampoline park facilities. This is because non-rigid walls would provide higher g-force reaction feedback from the wall, which would reduce the trampolinist's control and stability. This was verified by measuring g-force on a horizontal rigid surface versus a non-rigid surface, where the g-force feedback was 27% higher for the non-rigid surface. Control and stability are both critical while performing the complex walking-the-wall manoeuvre. The trampolinist experienced a very high peak g-force, with a maximum g-force of approximately 11.5 g at the bottom of the jump cycle. It was concluded that applying impact attenuation padding to vertical walls used for walking-the-wall and similar activities would increase the likelihood of injury; therefore, padding of these vertical surfaces is not recommended
Kin but less than kind:within-group male relatedness does not increase female fitness in seed beetles
Theory maintains within-group male relatedness can mediate sexual conflict by reducing male-male competition and collateral harm to females. We tested whether male relatedness can lessen female harm in the seed beetle Callosobruchus maculatus. Male relatedness did not influence female lifetime reproductive success or individual fitness across two different ecologically relevant scenarios of mating competition. However, male relatedness marginally improved female survival. Because male relatedness improved female survival in late life when C. maculatus females are no longer producing offspring, our results do not provide support for the role of within-group male relatedness in mediating sexual conflict. The fact that male relatedness improves the post-reproductive part of the female life cycle strongly suggests that the effect is non-adaptive. We discuss adaptive and non-adaptive mechanisms that could result in reduced female harm in this and previous studies, and suggest that cognitive error is a likely explanation
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