Identification of mobile and fixed antigens on the plasma membrane of rat spermatozoa using monoclonal antibodies

We have used monoclonal antibodies to study the mobility and distribution of three different antigens on the cell surface of rat spermatozoa. We classified two of the antigens (designated 2B1 and 2D6) as 'mobile', since when detected by indirect immunofluorescence they were situated over the entire sperm flagellum and were susceptible to antibody-induced patching. Patching was critically dependent upon antibody concentrations and was much reduced at 4 degrees C. Patching of the 2B1 antigen was not induced by the 2B1 monoclonal antibody alone. Thus, 2B1 antibody labelled directly with fluorescein bound with a uniform distribution over the sperm flagellum, but this uniform fluorescence was made patchy on subsequent incubation in an unlabelled second antibody layer of anti-mouse IgG anti-serum. By 'Western blotting', the 2B1 antigen was found to be located to a 40 kD molecular weight polypeptide. The remaining 'fixed' antigen (designated 1B6) was not susceptible to antibody-induced patching, and was restricted to a discrete domain on the post-acrosomal region of the sperm surface. We discuss the relationship between mobility of sperm surface antigens and their segregation to discrete domains on the plasma membrane.     

The metabolism of α-tocopherol by plants

An enzyme system which metabolizes α-tocopherol has been identified in homogenates of etiolated pea shoots. Enzyme activity is considerably increased by the presence of 20% ethanol in the incubation mixture. The enzyme has an absolute requirement for phospholipid. The reaction utilizes molecular oxygen and it is proposed that the enzyme be called α-tocopherol oxidase.     

Analysis and distribution of tocopherols and quinones in the pea plant

A procedure is described and evaluated for the analysis of ubiquinone, plastoquinone, tocopherols and vitamin K₁ in Pisum sativum L. Vitamin K₁ appears to be absent from the roots of this plant. While the pea seed contains only γ-tocopherol, the root and shoot contain only α-tocopherol. During the greening of etiolated tissue, plastoquinone and vitamin K₁ levels increase markedly while ubiquinone and α-tocopherol levels are unaffected. On homogenization or damage to tissue, considerable losses of α-tocopherol occur in the pea plant.     

Mapping of a mouse homolog of a Heterochromatin protein gene to the X Chromosome

Modifiers of position-effect-variegation inDrosophila are thought to encode proteins that are either structural components of heterochromatin or enzymes that modify these components. We have recently shown that a sequence motif found in oneDrosophila modifier gene, Heterochromatin protein 1 (HP1), is conserved in a wide variety of animal and plant species (Singh et al. 1991). Using this motif, termed chromo box, we have cloned a mouse candidate modifier gene,M31, that also shows considerable sequence homology toDrosophila HP1. Here we report evidence of at least four independently segregating loci in the mouse homologous to theM31 cDNA. One of these loci—Cbx-rsl—maps to the X Chromosome (Chr), 1 cM proximal toAmg and outside the X-inactivation center region.     

Association of physical activity intensity and bout length with mortality: An observational study of 79,503 UK Biobank participants

BackgroundSpending more time active (and less sedentary) is associated with health benefits such as improved cardiovascular health and lower risk of all-cause mortality. It is unclear whether these associations differ depending on whether time spent sedentary or in moderate-vigorous physical activity (MVPA) is accumulated in long or short bouts. In this study, we used a novel method that accounts for substitution (i.e., more time in MVPA means less time sleeping, in light activity or sedentary) to examine whether length of sedentary and MVPA bouts associates with all-cause mortality.Methods and findingsWe used data on 79,503 adult participants from the population-based UK Biobank cohort, which recruited participants between 2006 and 2010 (mean age at accelerometer wear 62.1 years [SD = 7.9], 54.5% women; mean length of follow-up 5.1 years [SD = 0.73]). We derived (1) the total time participants spent in activity categories—sleep, sedentary, light activity, and MVPA—on average per day; (2) time spent in sedentary bouts of short (1 to 15 minutes), medium (16 to 40 minutes), and long (41+ minutes) duration; and (3) MVPA bouts of very short (1 to 9 minutes), short (10 to 15 minutes), medium (16 to 40 minutes), and long (41+ minutes) duration. We used Cox proportion hazards regression to estimate the association of spending 10 minutes more average daily time in one activity or bout length category, coupled with 10 minutes less time in another, with all-cause mortality. Those spending more time in MVPA had lower mortality risk, irrespective of whether this replaced time spent sleeping, sedentary, or in light activity, and these associations were of similar magnitude (e.g., hazard ratio [HR] 0.96 [95% CI: 0.94, 0.97; P < 0.001] per 10 minutes more MVPA, coupled with 10 minutes less light activity per day). Those spending more time sedentary had higher mortality risk if this replaced light activity (HR 1.02 [95% CI: 1.01, 1.02; P < 0.001] per 10 minutes more sedentary time, with 10 minutes less light activity per day) and an even higher risk if this replaced MVPA (HR 1.06 [95% CI: 1.05, 1.08; P < 0.001] per 10 minutes more sedentary time, with 10 minutes less MVPA per day). We found little evidence that mortality risk differed depending on the length of sedentary or MVPA bouts. Key limitations of our study are potential residual confounding, the limited length of follow-up, and use of a select sample of the United Kingdom population.ConclusionsWe have shown that time spent in MVPA was associated with lower mortality, irrespective of whether it replaced time spent sleeping, sedentary, or in light activity. Time spent sedentary was associated with higher mortality risk, particularly if it replaced MVPA. This emphasises the specific importance of MVPA. Our findings suggest that the impact of MVPA does not differ depending on whether it is obtained from several short bouts or fewer longer bouts, supporting the recent removal of the requirement that MVPA should be accumulated in bouts of 10 minutes or more from the UK and the United States policy. Further studies are needed to investigate causality and explore health outcomes beyond mortality.

Louise Millard and co-workers study associations between bouts of moderate-to-vigorous physical activity and mortality.     

A scientific and animal welfare assessment of the OECD Health Effects Test Guidelines for the safety testing of chemicals under the European Union REACH system

We have assessed each of the OECD Health Effects Test Guidelines (TGs) that were included in an annex to the Internet consultation issued by the European Commission relating to the Registration, Evaluation and Authorisation of Chemicals (REACH) legislation for the testing of new and existing chemical substances. Each guideline has been analysed with respect to its design and its scientific and animal welfare implications, the extent to which it makes use of modern techniques, and its suitability to be used in the REACH system for the testing of large numbers of chemicals. The scientific basis of the test and its justification are considered, as well as the numbers of animals required, and the potential adverse effects on them. The prospects and possibilities for applying the Three Rs (reduction, refinement and replacement) to each of the TGs are also discussed. We have proposed an overall testing strategy for how these TGs and other methods could best be deployed for chemicals testing, should it be necessary to fill data gaps. Certain TGs have been omitted from the strategy, when we have considered them to be unnecessary for chemicals testing. A series of recommendations has been made for improving the TGs with regard to both their scientific content and ways in which they could be better designed in relation to optimising the use of the animals concerned, and minimising adverse welfare consequences to them. Our investigations show that there is an urgent need to update the TGs to reflect modern techniques and methods, and to use current approaches for applying refinement strategies to improve the scientific and animal welfare aspects of the procedures used. Improvements can and should be made in all aspects of toxicity testing, from sample preparation, and animal housing, care and feeding, to dose formulation, test material administration, and the histopathological and clinical analysis of tissue samples. Opportunities for streamlining individual assays are very limited, but testing could be made more efficient by: a) only undertaking studies that provide relevant data; b) making greater use of screens and preliminary testing; c) applying some tests simultaneously to the same animals; d) using one sex; and e) eliminating redundant tests. In conclusion, it is clear that, as they stand, the OECD Health Effects TGs are unsuitable for use in the European Union REACH system, for which potentially very large numbers of laboratory animals will be needed for the testing of a very large number of chemicals.     

Evolutionary shifts of vertebrate structures and Hox expression up and down the axial series of segments: a consideration of possible mechanisms

The term 'transposition' describes how, during vertebrate evolution, anatomical structures have shifted up or down the axial series of segments. For example, the neck/thorax junction and the position of the forelimb in the chicken have shifted posteriorly, relative to mouse, by a distance of seven somites or vertebrae. By examining the expression boundaries of some chick Hox genes not previously described, we provide new evidence that axial shifts in anatomical structures correspond with shifts in Hox expression domains. These shifts occur both in mesodermal components (somites, vertebrae, and lateral plate mesoderm) and neural components (spinal ganglia). We discuss morphogen gradient, timing, spreading, and growth models for the setting of Hoxexpression boundaries, and consider how evolutionary shifts in boundary positions might have been effected in terms of these models.