Additive and non-additive genetic variance in juvenile Sitka spruce (Picea sitchensis Bong. Carr).

Many quantitative genetic models assume that all genetic variation is additive because of a lack of data with sufficient structure and quality to determine the relative contribution of additive and non-additive variation. Here the fractions of additive (fa) and non-additive (fd) genetic variation were estimated in Sitka spruce for height, bud burst and pilodyn penetration depth. Approximately 1500 offspring were produced in each of three sib families and clonally replicated across three geographically diverse sites. Genotypes from 1525 offspring from all three families were obtained by RADseq, followed by imputation using 1630 loci segregating in all families and mapped using the newly developed linkage map of Sitka spruce. The analyses employed a new approach for estimating fa and fd, which combined all available genotypic and phenotypic data with spatial modelling for each trait and site. The consensus estimate for fa increased with age for height from 0.58 at 2 years to 0.75 at 11 years, with only small overlap in 95% support intervals (I95). The estimated fa for bud burst was 0.83 (I95=[0.78, 0.90]) and 0.84 (I95=[0.77, 0.92]) for pilodyn depth. Overall, there was no evidence of family heterogeneity for height or bud burst, or site heterogeneity for pilodyn depth, and no evidence of inbreeding depression associated with genomic homozygosity, expected if dominance variance was the major component of non-additive variance. The results offer no support for the development of sublines for crossing within the species. The models give new opportunities to assess more accurately the scale of non-additive variation. Supplementary Information: The online version contains supplementary material available at 10.1007/s11295-023-01627-5.

Neutron sub-micrometre tomography from scattering data.

Neutrons are valuable probes for various material samples across many areas of research. Neutron imaging typically has a spatial resolution of larger than 20 µm, whereas neutron scattering is sensitive to smaller features but does not provide a real-space image of the sample. A computed-tomography technique is demonstrated that uses neutron-scattering data to generate an image of a periodic sample with a spatial resolution of ∼300 nm. The achieved resolution is over an order of magnitude smaller than the resolution of other forms of neutron tomography. This method consists of measuring neutron diffraction using a double-crystal diffractometer as a function of sample rotation and then using a phase-retrieval algorithm followed by tomographic reconstruction to generate a map of the sample's scattering-length density. Topological features found in the reconstructions are confirmed with scanning electron micrographs. This technique should be applicable to any sample that generates clear neutron-diffraction patterns, including nanofabricated samples, biological membranes and magnetic materials, such as skyrmion lattices.

Oestrogen and bone density: a comparison of tamoxifen and hypo-oestrogenaemia.

The effect of the anti-oestrogen tamoxifen on bone density in post-menopausal women with stage II breast cancer (n = 35) was compared with two untreated hypo-oestrogenaemic groups (premature ovarian failure, n = 20; prolactinoma, n = 19) and a group of women with prolactinomas and normal oestrogen levels (n = 12). Bone densities were normal in the euoestrogenaemic groups, but significantly reduced in both hypo-oestrogenaemic groups. Repeat measurements were available for 31 of the 35 tamoxifen-treated subjects after an interval of 33.9 +/- 14.7 months. The anti-oestrogen action of tamoxifen was not associated with accelerated bone loss of the spine or hip, an outcome that was clearly demonstrable in hypo-oestrogenaemic disorders.

Sleep apnea in acromegaly.

In patients with acromegaly obstruction of the upper airway may develop due to enlargement of the tongue and thickening of the tissues of the larynx. The sleep apnea syndrome may develop in patients with upper airway obstruction from other causes. We studied a somnolent patient with acromegaly in whom we documented the sleep apnea syndrome. Endoscopy, while the patient was sleeping, revealed that periodic obstruction during sleep occurred because the large tongue bulged into the pharynx and obliterated the pharyngeal airway. Tracheostomy was followed by the disappearance of the somnolence. The upper airway obstruction in acromegaly may result in severe hypoxemia and disruption of normal sleep.