Inability of IL-2 and IL-10 to counteract B cell clonal deletion.

The B cell antigen receptor (BCR) delivers inhibitory signals in nascent B cells leading to the establishment of tolerance via clonal deletion or clonal anergy depending upon the type of antigen to which the B cells are exposed. In previous work, it has been demonstrated that activated Th2 cells, as well as some recombinant lymphokines, prevent the inhibition of growth and subsequent cell death induced through the BCR in model B cell lymphomas. Herein, we extend this work to another Th2 lymphokine, IL-10, that in contrast to IL-4 does not interfere with the deletion promoted by IgM crosslinking. The effect of individual lymphokines has also begun to be analyzed in a transgenic model of B cell clonal deletion. To this end, we have administered a recombinant vaccinia virus producing human IL-2 to mice expressing an autoreactive H-2Kk,b-specific transgenic IgMk and found that IL-2 does not abrogate B cell deletion in vivo.     

The effect of exhaustive exercise on expired pentane as a measure of in vivo lipid peroxidation in the rat

The concentrations of pentane and ethane in the expired breath of swimming rats were used to determine the possible occurrence of lipid peroxidation caused by strenuous exercise. Rats swum to exhaustion produced significantly more pentane but not ethane than did rats at rest. Rats fed a vitamin E-deficient diet produced slightly more pentane following exhaustive exercise than they did while at rest, but this increase was not statistically significant. Rats were also swum for prescribed lengths of time. Only rats that had swum for 20 or 40 min had significantly elevated concentrations of pentane in the breath. Rats swum for 10 or 30 min had elevated concentrations of pentane in the breath, but these increases were not statistically significant. These results suggest that lipid peroxidation is moderately increased following exhaustive exercise.     

Evolution of chromosomal abnormalities in sequential cytogenetic studies of ataxia telangiectasia

Summary Sequential cytogenetic studies of four patients with ataxia telangiectasia showed the progressive development of lymphocyte clones, each marked with a rearranged chromosome 14. Initial studies had shown random chromosomal breaks and rearrangements. Later studies in all patients showed nonrandom rearrangement of chromosome 14 with a breakpoint at 14q12 and with the distal segment translocated to either chromosome 14 or 7. The proportion of circulating lymphocytes carrying the marker tended to increase with time, accounting for the majority of the lymphocytes eventually in one case. The marked lymphocyte clones evolved further, as a result of loss of the small centric portions of the rearranged chromosome 14 (14pter14q12).Perhaps the abnormal clones in ataxia telangiectasia escape immunologic surveillance and flourish in an immunologically impaired environment. Subsequent to the loss of the centric portion of the rearranged chromosome 14, the cells may acquire additional capabilities that enhance malignant transformation.     

Evaluation of Nosema locustae (Microsporida) as a control agent of grasshopper populations in Saskatchewan

A quantitative study of the effect of a microsporidan, Nosema locustae, as a control agent against grasshopper populations in Saskatchewan, Canada, revealed that 50% of the populations of Melanoplus sanguinipes, M. packardii, and Camnula pellucida were infected between 4 and 5 weeks (400 to 424 degree-days) after application of the pathogen. Maxima of 95–100% infection were evident between 9 and 12 weeks (600–700 degree-days) after application. The percentage reduction in surviving populations of M. sanguinipes, i.e., those that did not die from natural causes, reached about 20% by the 4th week (400 degree-days) after inoculation, about 50% by the 9th week (600 + degree-days), and a maximum of about 60% by the 12th week (700 degree-days). An exponential relationship was obtained between percentage reduction and percentage infection in all three species. However, a similar percentage infection resulted in different percentage reduction in the populations. Results also revealed that the rate of reduction in populations reached its peak by about 40–80 degree-days before the maximum rate of infection was attained for each species. Egg production in the two Melanoplus species in treated plots was significantly lower (P < 0.05) than in the control plot.     

Effect of Polychlorinated Biphenyl Formulations on the Growth of Estuarine Bacteria

Polychlorinated biphenyl formulations inhibited the growth of certain estuarine bacteria. The sensitive strains, although exhibiting some similar physiological characteristics, contained both gram-positive and gram-negative bacteria.     

Efficacy of core stability training on upper extremity performance in collegiate athletes

Objective:To determine the efficacy of a five-week core stability training program for collegiate athletes on upper extremity performance measures.Methods:Seventy healthy collegiate athletes (age 21.6±1.7years; height 175±4.63 cm; body mass 65.31±5.63 kg) were randomly allocated to experimental (n=35) and control group (n=35). The experimental group has undergone a five-week core stabilisation protocol (three days /week) and regular training, whereas the control group maintained their regular training. The upper quarter Y balance test (UQ-YBT) and Functional throwing performance index (FTPI) were assessed pre and post-training.Results:The results of mixed ANOVA show that there was a significant interaction between time and group variables on YBT (p<0.001, η_p² =0.759) and FTPI (p<0.001, η_p² =0.411) after five weeks of core stability training. Statistically, significant improvement was shown in YBT (mean change=15.2, p<0.001) and FTPI (mean change=14.4, p<0.001) in the experimental group; however, there was no significant change observed in both outcomes in the control groups.Conclusion:After five weeks of core stabilisation training program, the measures of UQ-YBT and FTPI were improved, thus advocating the use of a core stabilisation training program among collegiate athletes to enhance their upper extremity performance.     

ER-stress-induced secretion of circulating glucose-regulated protein 78kDa (GRP78) ameliorates pulmonary artery smooth muscle cell remodelling

Pulmonary arterial hypertension (PAH) is driven by vascular remodelling due to inflammation and cellular stress, including endoplasmic reticulum stress (ER stress). The main ER-stress chaperone, glucose-regulated protein 78 kDa (GRP78), is known to have protective effects in inflammatory diseases through extracellular signalling. The aim of this study is to investigate its significance in PAH. Human pulmonary arterial smooth muscle cells (PASMC) were stimulated with compounds that induce ER stress, after which the secretion of GRP78 into the cell medium was analysed by western blot. We found that when ER stress was induced in PASMC, there was also a time-dependent secretion of GRP78. Next, naïve PASMC were treated with conditioned medium (CM) from the ER-stressed donor PASMC. Incubation with CM from ER-stressed PASMC reduced the viability, oxidative stress, and expression of inflammatory and ER-stress markers in target cells. These effects were abrogated when the donor cells were co-treated with Brefeldin A to inhibit active secretion of GRP78. Direct treatment of PASMC with recombinant GRP78 modulated the expression of key inflammatory markers. Additionally, we measured GRP78 plasma levels in 19 PAH patients (Nice Group I) and correlated the levels to risk stratification according to ESC guidelines. Here, elevated plasma levels of GRP78 were associated with a favourable risk stratification. In conclusion, GRP78 is secreted by PASMC under ER stress and exhibits protective effects from the hallmarks of PAH in vitro. Circulating GRP78 may serve as biomarker for risk adjudication of patients with PAH.Graphical abstractProposed mechanism of ER-stress-induced GRP78 secretion by PASMC. Extracellular GRP78 can be measured as a circulating biomarker and is correlated with favourable clinical characteristics. Conditioned medium from ER-stressed PASMC reduces extensive viability, ROS formation, inflammation, and ER stress in target cells. These effects can be abolished by blocking protein secretion in donor cells by using Brefeldin A. Supplementary InformationThe online version contains supplementary material available at 10.1007/s12192-022-01292-y.     

Reproductive efficiency and shade avoidance plasticity under simulated competition

Plant strategy and life‐history theories make different predictions about reproductive efficiency under competition. While strategy theory suggests under intense competition iteroparous perennial plants delay reproduction and semelparous annuals reproduce quickly, life‐history theory predicts both annual and perennial plants increase resource allocation to reproduction under intense competition. We tested (1) how simulated competition influences reproductive efficiency and competitive ability (CA) of different plant life histories and growth forms; (2) whether life history or growth form is associated with CA; (3) whether shade avoidance plasticity is connected to reproductive efficiency under simulated competition. We examined plastic responses of 11 herbaceous species representing different life histories and growth forms to simulated competition (spectral shade). We found that both annual and perennial plants invested more to reproduction under simulated competition in accordance with life‐history theory predictions. There was no significant difference between competitive abilities of different life histories, but across growth forms, erect species expressed greater CA (in terms of leaf number) than other growth forms. We also found that shade avoidance plasticity can increase the reproductive efficiency by capitalizing on the early life resource acquisition and conversion of these resources into reproduction. Therefore, we suggest that a reassessment of the interpretation of shade avoidance plasticity is necessary by revealing its role in reproduction, not only in competition of plants.     

Determinants of cyanobacterial species composition in the splash zone of two Croatian islands

Cyanobacterial communities of the splash zone of two Croatian islands, Veruda and Ugljan, were surveyed. At each island, we studied eight localities with different aspects. From all 336 samples, a total of 42 cyanobacterial species, one green alga, and one red alga were found. In both islands Hyella spp. and Gloeocapsopsis crepidinum dominated and Entophysalis deusta, Solentia spp., Kyrtuthrix dalmatica and Mastigocoleus testarum were found frequently. Multivariate statistical analysis of species composition shows that the vertical gradient is the strongest determinant of species composition and that there are statistically significant but not very pronounced differences in species composition between the two islands. Species composition among individual sites within islands differed slightly, and between localities decreased rather slowly with the distance of individual samples (i.e. the similarity distance decay was very slow), showing that even close samples can have quite different species composition. The species accumulation curves do not reach their asymptote, indicating that many samples are needed to reasonably cover the species richness of a site. This study highlights the importance of in-depth species counts and high density sampling along vertical gradients for satisfactory cyanobacterial community assessments in marine coastal splash zones.     

Iron transport in the genus Marinobacter

Marinobacter belong to the class of Gammaproteobacteria and these motile, halophilic or halotolerent bacteria are widely distributed throughout the world’s oceans having been isolated from a wide variety of marine environments. They have also been identified as members of the bacterial flora associated with other marine organisms. Here, using a combination of natural products chemistry and genomic analysis, we assess the nature of the siderophores produced by this genus and their potential relationship to phylogeny and lifestyle/ecological niche of this diverse group of organisms. Our analysis shows a wide level of diversity in siderophore based iron uptake systems among this genus with three general strategies: (1) production and utilization of native siderophores in addition to utilization of a variety of exogenous ones, (2) production and utilization of native siderophores only, (3) lack of siderophore production but utilization of exogenous ones. They all share the presence of at least one siderophore-independent iron uptake ABC transport systems of the FbpABC iron metal type and lack the ability for direct transport of ferrous iron. Siderophore production and utilization can be correlated with phylogeny and thus it forms a type of chemotaxonomic marker for this genus.