Inhibition of ethylene production in sunflower cell suspensions by a novel oxime ether derivative

During the incubation of undifferentiated cell suspensions of sunflower (Helianthus annuus L. cv. Spanners Allzweck) ethylene production was effectively inhibited by the novel oxime ether derivative LAB 181 508, [[(Isopropyliden)-amino]-oxy]-acetic acid-2-(methoxyl)-2-oxoethylester (PACME). The compound was most active during the first 6 days of incubation exhibiting a value of 50% inhibition at 9.5×10^?6 mol×L^?1. The pattern of changes in the internal 1-aminocyclopropanecarboxylic acid (ACC) and N-malonyl-ACC (MACC) levels paralleled the influence on ethylene formation. While the addition of ACC fully restored ethylene production, applied S-adenosyl-L-methionine (SAM) was not effective. Experiments with [¹⁴C]indole-3-acetic acid (IAA) revealed that LAB 181 508 did not affect auxin uptake into suspension cells of sunflower. The results suggest that LAB 181 508 reduces ethylene formation by inhibiting the conversion of SAM to ACC in the biosynthetic pathway. In comparison to the structurally related inhibitor of ACC synthase, aminoethoxyvinylglycine (AVG), LAB 181 508 reduced growth and viability of the suspension cells only slightly. Low phytotoxicity of LAB 181 508 combined with a less complicated chemical synthesis might offer interesting aspects for physiological research and horticultural and agricultural practice.     

Image analysis of p53 and cyclin D1 expression in premalignant lesions of the oral mucosa

OBJECTIVE: The expression of p53 and cyclin D1 proteins was analyzed by image analysis in oral premalignant lesions and normal oral mucosa. STUDY DESIGN: Punch biopsies from the normal oral mucosa were obtained from 20 normal donors and 41 patients with oral dysplastic leukoplakias. After controlled formaldehyde fixation and paraffin embedding, immunohistochemistry was used to detect cyclin D1 and p53. Image analysis was performed using stain intensity levels established by determining color thresholds (nuclear score) in the basal and parabasal layers. RESULTS: Analysis of sections showed a similar pattern: only two normal donors had a few intensely positive p53 cells in the basal layer of the floor of the mouth and the tongue epithelia. Similarly, only three donors had intensely positive cyclin D1 cells in the normal epithelia of the same sites. Most cells fell in the range of negative or marginal stain (lower quartiles or terciles of nuclear score). These data on normal mucosa were compared with low grade oral leukoplakias (LGD) with mild to moderate dysplasia and with high grade leukoplakias (HGD) with severe dysplasia. Both markers were differentially expressed in precursor lesions versus normal epithelia. Statistical analysis of our data shows that the intensity of the immunohistochemical stain, as reflected in the nuclear scores of p53, is a reliable parameter that can differentiate between LGD and HGD of the oral mucosa. This was especially true when higher nuclear scores were compared. In contrast, low nuclear scores are more effective in differentiating normal epithelia from dysplastic epithelia. Although cyclin D1 immunohistochemistry does not stain as intensely as p53 stain, similar conclusions can be derived from those data. CONCLUSION: Image analysis of these two markers proved useful in distinguishing normal oral epithelia from low grade and high grade leukoplakias. With further developments in this field it is hoped that image analysis procedures could be used in different types of studies in which variations of protein expression in tissue sections could have prognostic implications or could be useful to determine subtle effects of curative or preventive treatment.     

Storage,mobilization and interrelations of starch,sugars, protein and fat in the ray storage tissue of poplar trees

The seasonal pattern in starch, various sugars, protein, and fat, and their interrelationship, has been followed in 3-year-old branch wood of poplar trees (Populus x canadensis Moench robusta) under natural site conditions. The deposition of starch, protein and fat proceeds at different times. Starch accumulates from May until October, fat mainly during the summer months, and protein when the leaves are yellowing in September and October. The maximum concentrations in the branch wood were 15–18 g starch, 6–9 g protein, 4–8 g fat, 10–15 g sucrose, and up to 30 g total sugars per milligram dry weight (DW). During starch deposition periods no increased sucrose level is found in the tissue. The maximum daily starch deposition rate was 0.2–0.4 g starch/day/mg DW of wood. During starch hydrolysis in late autumn and winter, a dramatic increase in sucrose and its galactosides is measured (up to 15–27 g/mg DW in total). In early spring, before budbreak, the concentrations of these sugars diminishes sharply. In contrast to this clear-cut starch-to-sugar conversion in autumn no significant starch-to-fat conversion is detected. An elevated content of free glycerol, however, is found in winter. In spring, starch and storage protein are mobilized completely, or almost completely, in poplar twig wood. A noteworthy pool of maltose is found transiently during autumn (up to 8 g/mg DW) and again in spring. The results demonstrate that the individual storage materials, e.g. starch, protein, and fat, are accumulated fairly independently in the wood storage parenchyma. Tissue sugar levels, in contrast, appear to be closely related to the seasonal variations in starch content, on the one hand, and to the acclimation and deacclimation of the cells, on the other. The interrelations of the storage materials and sugars are discussed.     

The ontogeny of human laughter

Human adult laughter is characterized by vocal bursts produced predominantly during exhalation, yet apes laugh while exhaling and inhaling. The current study investigated our hypothesis that laughter of human infants changes from laughter similar to that of apes to increasingly resemble that of human adults over early development. We further hypothesized that the more laughter is produced on the exhale, the more positively it is perceived. To test these predictions, novice (n = 102) and expert (phonetician, n = 15) listeners judged the extent to which human infant laughter (n = 44) was produced during inhalation or exhalation, and the extent to which they found the laughs pleasant and contagious. Support was found for both hypotheses, which were further confirmed in two pre-registered replication studies. Likely through social learning and the anatomical development of the vocal production system, infants'' initial ape-like laughter transforms into laughter similar to that of adult humans over the course of ontogeny.     

PopART-IBM,a highly efficient stochastic individual-based simulation model of generalised HIV epidemics developed in the context of the HPTN 071 (PopART) trial

Mathematical models are powerful tools in HIV epidemiology, producing quantitative projections of key indicators such as HIV incidence and prevalence. In order to improve the accuracy of predictions, such models need to incorporate a number of behavioural and biological heterogeneities, especially those related to the sexual network within which HIV transmission occurs. An individual-based model, which explicitly models sexual partnerships, is thus often the most natural type of model to choose. In this paper we present PopART-IBM, a computationally efficient individual-based model capable of simulating 50 years of an HIV epidemic in a large, high-prevalence community in under a minute. We show how the model calibrates within a Bayesian inference framework to detailed age- and sex-stratified data from multiple sources on HIV prevalence, awareness of HIV status, ART status, and viral suppression for an HPTN 071 (PopART) study community in Zambia, and present future projections of HIV prevalence and incidence for this community in the absence of trial intervention.