Sperm motility is crucial to reproductive success in sexually reproducing organisms. Impaired sperm movement causes male infertility, which is increasing globally. Sperm are powered by a ...microtubule-based molecular machine—the axoneme—but it is unclear how axonemal microtubules are ornamented to support motility in diverse fertilization environments. Here, we present high-resolution structures of native axonemal doublet microtubules (DMTs) from sea urchin and bovine sperm, representing external and internal fertilizers. We identify >60 proteins decorating sperm DMTs; at least 15 are sperm associated and 16 are linked to infertility. By comparing DMTs across species and cell types, we define core microtubule inner proteins (MIPs) and analyze evolution of the tektin bundle. We identify conserved axonemal microtubule-associated proteins (MAPs) with unique tubulin-binding modes. Additionally, we identify a testis-specific serine/threonine kinase that links DMTs to outer dense fibers in mammalian sperm. Our study provides structural foundations for understanding sperm evolution, motility, and dysfunction at a molecular level.
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•Structures of native axonemal doublet microtubules from sea urchin and bovine sperm•Identification of >60 proteins decorating sperm doublet microtubules•Identification of microtubule-associated proteins with unique tubulin-binding modes•Analysis of the evolution and structural diversity of the tektin bundle
Cryo-EM analysis of native axonemal doublet microtubules from sea urchin and bovine sperm provides molecular insights into sperm evolution, motility, and dysfunction.
Mitochondria-cytoskeleton interactions modulate cellular physiology by regulating mitochondrial transport, positioning, and immobilization. However, there is very little structural information ...defining mitochondria-cytoskeleton interfaces in any cell type. Here, we use cryofocused ion beam milling-enabled cryoelectron tomography to image mammalian sperm, where mitochondria wrap around the flagellar cytoskeleton. We find that mitochondria are tethered to their neighbors through intermitochondrial linkers and are anchored to the cytoskeleton through ordered arrays on the outer mitochondrial membrane. We use subtomogram averaging to resolve in-cell structures of these arrays from three mammalian species, revealing they are conserved across species despite variations in mitochondrial dimensions and cristae organization. We find that the arrays consist of boat-shaped particles anchored on a network of membrane pores whose arrangement and dimensions are consistent with voltage-dependent anion channels. Proteomics and in-cell cross-linking mass spectrometry suggest that the conserved arrays are composed of glycerol kinase-like proteins. Ordered supramolecular assemblies may serve to stabilize similar contact sites in other cell types in which mitochondria need to be immobilized in specific subcellular environments, such as in muscles and neurons.
A hierarchical Bayesian model for extreme pesticide residues Kennedy, Marc C.; Roelofs, Victoria J.; Anderson, Clive W. ...
Food and chemical toxicology,
January 2011, 2011, 2011-Jan, 2011-01-00, 20110101, Letnik:
49, Številka:
1
Journal Article
Recenzirano
The number of residue measurements in an individual field trial, carried out to provide data for a pesticide registration for a particular crop, is generally too small to estimate upper tails of the ...residue distribution for that crop with any certainty. We present a new method, using extreme value theory, which pools information from various field trials, with different crop and pesticide combinations, to provide a common model for the upper tails of residue distributions generally. The method can be used to improve the estimation of high quantiles of a particular residue distribution. It provides a flexible alternative to the direct fitting of a distribution to each individual dataset, and does not require strong distributional assumptions. By using a hierarchical Bayesian model, our method also accounts for parameter uncertainty. The method is applied to a range of supervised trials containing residues on individual items (e.g. on individual apples), and the results illustrate the variation in tail properties amongst all commodities and pesticides.
The outputs could be used to select conservative high percentile residue levels as part of a deterministic risk assessment, taking account of the variability between crops and pesticides and also the uncertainty due to relatively small datasets.
Wetlands are the largest natural source of atmospheric methane, the second most important greenhouse gas. Methane flux to the atmosphere depends strongly on the climate; however, by far the largest ...part of the methane formed in wetland ecosystems is recycled and does not reach the atmosphere. The biogeochemical controls on the efficient oxidation of methane are still poorly understood. Here we show that submerged Sphagnum mosses, the dominant plants in some of these habitats, consume methane through symbiosis with partly endophytic methanotrophic bacteria, leading to highly effective in situ methane recycling. Molecular probes revealed the presence of the bacteria in the hyaline cells of the plant and on stem leaves. Incubation with 13C-methane showed rapid in situ oxidation by these bacteria to carbon dioxide, which was subsequently fixed by Sphagnum, as shown by incorporation of 13C-methane into plant sterols. In this way, methane acts as a significant (10-15%) carbon source for Sphagnum. The symbiosis explains both the efficient recycling of methane and the high organic carbon burial in these wetland ecosystems.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
CCAAT/enhancer-binding protein δ (C/EBPδ) is a transcription factor involved in growth arrest and differentiation, which has consequently been suggested to harbor tumor suppressive activities. ...However, C/EBPδ over-expression correlates with poor prognosis in glioblastoma and promotes genomic instability in cervical cancer, hinting at an oncogenic role of C/EBPδ in these contexts. Here, we explore the role of C/EBPδ in pancreatic cancer. We determined C/EBPδ expression in biopsies from pancreatic cancer patients using public gene-expression datasets and in-house tissue microarrays. We found that C/EBPδ is highly expressed in healthy pancreatic ductal cells but lost in pancreatic ductal adenocarcinoma. Furthermore, loss of C/EBPδ correlated with increased lymph node involvement and shorter overall survival in pancreatic ductal adenocarcinoma patients. In accordance with this, in vitro experiments showed reduced clonogenic capacity and proliferation of pancreatic ductal adenocarcinoma cells following C/EBPδ re-expression, concurrent with decreased sphere formation capacity in soft agar assays. We thus report a previously unrecognized but important tumor suppressor role of C/EBPδ in pancreatic ductal adenocarcinoma. This is of particular interest since only few tumor suppressors have been identified in the context of pancreatic cancer. Moreover, our findings suggest that restoration of C/EBPδ activity could hold therapeutic value in pancreatic ductal adenocarcinoma, although the latter claim needs to be substantiated in future studies.
Cloacal exstrophy is a complex and rare congenital malformation. Because of improvements in medicine, operative techniques, and perioperative management the survival rates are now approaching 100%. ...Currently, treatment is focused on improving quality of life. Since 1974, we encountered 20 patients with cloacal exstrophy in our hospital. The aim of this study is to evaluate our clinical experience and outcome during the last 39 years.
A retrospective study of the medical records was performed. We evaluated anatomical status, phenotype and genotype at birth, subsequent surgical treatment and current gastrointestinal, urinary, spinal, genital, and gender status and outcome.
The records of all 20 patients who were treated in our center were included in this study. Of the 20 patients, 18 were primary patients, 2 referred. Six patients died within the first year of life. Median age of the surviving 14 patients was 25 years (range, 4-39 years) at time of evaluation. At the last follow-up, 11 patients had an endileostomy or endcolostomy. Three patients had a pull-through; two of them were continent for feces. Two patients were continent for urine; one with a sinus urogenitalis and one after urethra reconstruction. Eleven patients are incontinent; six of them had an incontinent urinary deviation (Bricker deviation). Of the other five incontinent patients, two had a urethral reconstruction, one vesicovaginal anastomosis, one perineotomy, and one epispadias bladder. Urinary continence was unknown in one patient. Of the surviving patients, nine have 46 XY karyotype and five 46 XX karyotype. Initially, six XY patients underwent external genital reconstruction with reassignment to female gender; however, one died postoperatively. One declared to feel like a man at age of 15 years. Remaining four XY patients underwent male external genital reconstruction. All XX patients underwent vagina or vulva reconstruction, except for one who still has aplasia vaginae. All patients were born with varying types of spinal dysraphism.
Despite medical efforts and development in treatment and support, satisfaction in outcome of cloacal exstrophy remains a challenge. Although reconstruction may be very difficult, male genital reconstruction in 46 XY patients has been given preference for more than a decade. A specialized multidisciplinary team should provide lifelong colorectal, urological, sexual, and psychosocial support to these patients, taking into account their age and phase of life.
Minimally invasive distal pancreatectomy (MIDP) shortens time to functional recovery and improves 30-day quality of life (QoL), as compared with open distal pancreatectomy (ODP) for nonmalignant ...disease. The impact of MIDP on QoL, cosmetic satisfaction, and overall major complications beyond 1-year follow-up is currently unknown.
The Minimally Invasive Versus Open Distal Pancreatectomy (LEOPARD) trial randomized 108 patients to MIDP (laparoscopic or robotic) or ODP in 14 Dutch centers (April 2015 to March 2017). The primary outcome measure of this study was quality-adjusted life years (QALYs), as assessed with the EQ-5D. QoL was assessed using subscales of the EORTC QLQ-C30, PAN-26, and a body image questionnaire. The latter included a cosmetic satisfaction score (range 3–24), and a body image score (range 5–20). Differences between MIDP and ODP for QALYs, generic, and disease-specific QoL and body image were analyzed. Missing QoL data were imputed using multiple imputation.
In total, 84 patients were alive, with a median follow-up of 44 months; 62 of these patients (74%) completed the questionnaires (27 MIDP, 35 ODP). There was no significant difference in QALYs between the 2 groups (mean score 2.34 vs 2.46 years, p = 0.63), nor on the QoL subscales. Significant overall change in EQ-5D health utilities were found for both groups over time (p < 0.001). Patients in the MIDP group scored higher on cosmetic satisfaction (21 vs 14, p = 0.049). No differences between the 2 groups were observed for clinical outcomes such as major complications, readmissions, and incisional hernias.
More than 3 years after distal pancreatectomy, no improvement in QALYs and overall QoL was seen after MIDP, whereas cosmetic satisfaction was higher after MIDP as compared with ODP.
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Drosophila melanogaster cuticular pheromones consist of unsaturated hydrocarbons with at least one double bond in position 7: 7 tricosene (T) in males and 7,11 heptacosadiene (HD) in females. ...However, in many African populations like the Tai strain, females possess low levels of 7,11 HD and high levels of its positional isomer 5,9 HD. We have previously isolated a desaturase gene, desat1 , from the Canton-S strain (CS), a 7,11 HD-2-rich morph of D. melanogaste r. This desaturase is located in 87C, a locus that has been involved in the difference between 7,11 HD and 5,9 HD morphs. Therefore, we have searched for different desaturase isoforms in both strains. We first cloned desat1 in the Tai strain and report here functional expression of desat1 in CS and Tai. In both strains, the Desat1 enzymes have the same Δ9 specificity and preferentially use palmitate as a substrate, leading to the synthesis of ω7 fatty acids. Also found was a desaturase sequence, named desat2 , with a homologous catalytic domain and a markedly different N-terminal domain compared with desat1 . In CS genome, it lies 3.8 kb upstream of desat1 and is not transcribed in either sex. In the Tai strain, it is expressed only in females and acts preferentially on myristate, leading to the synthesis of ω5 fatty acids. We suggest, therefore, that desat2 might play a control role in the biosynthesis of 5,9 HD hydrocarbons in Tai females and could explain the dienic hydrocarbon polymorphism in D. melanogaster. acyl-Coa desaturase pheromone biosynthesis
Drosophila melanogaster cuticular pheromones consist of unsaturated hydrocarbons with at least one double bond in position 7:7 tricosene (T) in males and 7,11 heptacosadiene (HD) in females. However, ...in many African populations like the Tai strain, females possess low levels of 7,11 HD and high levels of its positional isomer 5,9 HD. We have previously isolated a desaturase gene, desat1, from the Canton-S strain (CS), a 7,11 HD-2-rich morph of D. melanogaster. This desaturase is located in 87C, a locus that has been involved in the difference between 7,11 HD and 5,9 HD morphs. Therefore, we have searched for different desaturase isoforms in both strains. We first cloned desat1 in the Tai strain and report here functional expression of desat1 in CS and Tai. In both strains, the Desat1 enzymes have the same Δ 9 specificity and preferentially use palmitate as a substrate, leading to the synthesis of ω 7 fatty acids. Also found was a desaturase sequence, named desat2, with a homologous catalytic domain and a markedly different N-terminal domain compared with desat1. In CS genome, it lies 3.8 kb upstream of desat1 and is not transcribed in either sex. In the Tai strain, it is expressed only in females and acts preferentially on myristate, leading to the synthesis of ω 5 fatty acids. We suggest, therefore, that desat2 might play a control role in the biosynthesis of 5,9 HD hydrocarbons in Tai females and could explain the dienic hydrocarbon polymorphism in D. melanogaster.
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