Promoter elements involved in environmental and developmental control of potato proteinase inhibitor II expression

The proteinase inhibitor II (pin2) gene family exhibits two different modes of expression. It is, on the one hand, constitutively expressed in flowers of potato and tomato plants. and in potato tubers. On the other hand, its expression is induced in the plant foliage by mechanical wounding. To define cis-regulatory elements involved in pin2 promoter activity, deletion analysis of a potato pin2 promoter has been performed in stably and transiently transformed potato and tobacco plants. Two different elements, a quantitative enhancer and a regulatory element, are required for promoter activity. While functional promoter elements required for pin2 activity in tubers and wounded leaves could not be separated, its expression in flowers is mediated by different cis-acting sequences. Induction of pin2 expression in leaves by treatment with the plant growth regulators abscisic acid and jasmonic acid, and the general metabolite sucrose, depends on the presence of the regulatory element involved in expression in tubers and wounded leaves. Thus, pin2 expression in tubers and wounded leaves apparently results from the action of similar hormonal signals on closely linked promoter elements, while a different signal pathway leads to its constitutive expression in flowers.     

Association of glycosphingolipids with intermediate filaments of human umbilical vein endothelial cells

Our previous studies of glycosphingolipids (GSLs) of human umbilical vein endothelial cells (HUVECs) established that globoside and ganglioside GM3 are the most abundant GSLs of HUVECs. Both compounds are located intracellularly, as well as on the cell surface. In this study, we demonstrate that the intracellular globoside and GM3 antigens are associated with the vimentin intermediate filaments of the HUVEC cytoskeleton. Immunofluorescence staining of fixed, permeabilized HUVECs showed colocalization of globoside and GM3 with vimentin but not with tubulin or actin. Both GSLs remained associated with intermediate filaments after perinuclear collapse of the filaments induced by colcemid. Indirect evidence that the globoside epitope is present on a GSL is the loss of staining by anti-globoside after methanol fixation and the absence of anti-globoside reactivity with HUVEC proteins on immunoblots. Colocalization of anti-globoside and anti-vimentin was also demonstrated in cryosections of endothelial cells, which indicates that the observed association was not an artifact induced by exposure of cells to detergent or organic solvent. Association of globoside with intermediate filaments was confirmed by immunoelectron microscopy, which demonstrated the presence of antigen along intermediate filaments, as well as on the cell surface and on lipid vesicles. Interferon-gamma decreased the ratio of surface to filamentous globoside staining, but had the opposite effect on GM3 distribution. Less abundant HUVEC GSLs, including Gb3, nLc4, IV2FucnLc4, and IV3NeuAcnLc4, were not detected along filaments. This is the first report of the association of GSLs with intermediate filaments. We suggest that intermediate filaments may play a role in the transport of GSLs.     

Decreased E‐Cadherin in MCF7 Human Breast Cancer Cells Forming Multicellular Spheroids Exposed to Simulated Microgravity

MCF7 human breast cancer cells were cultured under normal gravity (1 g) and on a random positioning machine (RPM) preventing sedimentation. After 2 weeks, adherent 1 g‐control and adherent RPM cells (AD) as well as multicellular spheroids (MCS) were harvested. AD and MCS had been exposed to the RPM in the same culture flask. In a subsequent proteome analysis, the majority of the proteins detected showed similar label‐free quantification (LFQ) scores in each of the respective subpopulations, but in both AD or MCS cultures, proteins were also found whose LFQs deviated at least twofold from their counterparts in the 1 g‐control cells. They included the cell junction protein E‐cadherin, which was diminished in MCS cells, where proteins of the E‐cadherin autodegradation pathway were enhanced and c‐Src (proto‐oncogene tyrosine‐protein kinase c‐Src) was detected. Spheroid formation was prevented by inhibition of c‐Src but promoted by antibodies blocking E‐cadherin activity. An interaction analysis of the detected proteins that are involved in forming and regulating junctions or adhesion complexes and in E‐cadherin autodegradation indicated connections between the two protein groups. This suggests that the balance of proteins that up‐ or downregulate E‐cadherin mediates the tendency of MCF7 cells to form MCS during RPM exposure.     

Bayesian estimation and use of high-throughput remote sensing indices for quantitative genetic analyses of leaf growth

Key message

We develop Bayesian function-valued trait models that mathematically isolate genetic mechanisms underlying leaf growth trajectories by factoring out genotype-specific differences in photosynthesis. Remote sensing data can be used instead of leaf-level physiological measurements.

Abstract

Characterizing the genetic basis of traits that vary during ontogeny and affect plant performance is a major goal in evolutionary biology and agronomy. Describing genetic programs that specifically regulate morphological traits can be complicated by genotypic differences in physiological traits. We describe the growth trajectories of leaves using novel Bayesian function-valued trait (FVT) modeling approaches in Brassica rapa recombinant inbred lines raised in heterogeneous field settings. While frequentist approaches estimate parameter values by treating each experimental replicate discretely, Bayesian models can utilize information in the global dataset, potentially leading to more robust trait estimation. We illustrate this principle by estimating growth asymptotes in the face of missing data and comparing heritabilities of growth trajectory parameters estimated by Bayesian and frequentist approaches. Using pseudo-Bayes factors, we compare the performance of an initial Bayesian logistic growth model and a model that incorporates carbon assimilation (A _max) as a cofactor, thus statistically accounting for genotypic differences in carbon resources. We further evaluate two remotely sensed spectroradiometric indices, photochemical reflectance (pri2) and MERIS Terrestrial Chlorophyll Index (mtci) as covariates in lieu of A _max, because these two indices were genetically correlated with A _max across years and treatments yet allow much higher throughput compared to direct leaf-level gas-exchange measurements. For leaf lengths in uncrowded settings, including A _max improves model fit over the initial model. The mtci and pri2 indices also outperform direct A _max measurements. Of particular importance for evolutionary biologists and plant breeders, hierarchical Bayesian models estimating FVT parameters improve heritabilities compared to frequentist approaches.

     

A laboratory study of host use by the cuckoo catfish <Emphasis Type="Italic">Synodontis multipunctatus</Emphasis>

The only known non-avian vertebrate obligate brood parasite is the cuckoo catfish (Synodontis multipunctatus), a Lake Tanganyikan endemic. The cuckoo catfish parasitizes Tanganyikan mouthbrooding cichlids, and under captive conditions, will also parasitize cichlids from other Rift Valley lakes. Here we examine the frequency of parasitism by the cuckoo catfish of Ctenochromis horei from Lake Tanganyika and three species from Lake Malawi and the greater Lake Victorian system in a laboratory setting. C. horei was parasitized significantly less (17%) than the allopatric species Haplochromis latifasciatus, Haplochromis nubilus, and Metriaclima estherae (combined parasitism rate of 28%). The lower rates of parasitism in C. horei may be due to differences in the mating ritual, oviposition (e.g., long periods of pseudo-spawning before actual oviposition), and behavioral adaptations (e.g., increased aggression towards the cuckoo catfish). The number of catfish eggs per parasitized brood was similar between C. horei, H. latifasciatus, H. nubilus, and M. estherae. Our results are comparable to findings from the field for C. horei parasitism frequency and number of cuckoo catfish per brood. We also analyzed the parasitism rate of the albino morph of Metriaclima zebra, a domestic strain. Parasitism rates and number of catfish per brood were the highest in the albino morphotype suggesting that the higher levels of parasitism may be related to lower aggressive behavior, lower visual acuity, or captive influence. Cuckoo catfish and mouthbrooding cichlids provide a model system for testing brood parasitism in a laboratory setting.     

Endogenous arabitol and mannitol improve shelf life of encapsulated <Emphasis Type="Italic">Metarhizium brunneum</Emphasis>

Successful commercialization of microbial biocontrol agents, such as Metarhizium spp., is often constrained by poor drying survival and shelf life. Here, we hypothesized that culture age would influence endogenous arabitol, erythritol, mannitol and trehalose contents in M. brunneum mycelium and that elevated levels of these compounds would improve drying survival and shelf life of encapsulated mycelium coupled with enhanced fungal virulence against T. molitor larvae. We found that culture age significantly influenced endogenous arabitol and mannitol contents in mycelium with highest concentrations of 0.6?±?0.2 and 2.1?±?0.2 µg/mg after 72 h, respectively. Drying survival of encapsulated mycelium was independent of culture age and polyol content with 41.1?±?4.4 to 55.0?±?6.2%. Best shelf life was determined for biomass harvested after 72 h at all investigated storage temperatures with maximum values of 59.5?±?3.3% at 5 °C followed by 54.5?±?1.6% at 18 °C and 19.4?±?1.3% at 25 °C after 6 months. Finally, high fungal virulence against T. molitor larvae of 83.3?±?7.6 to 98.0?±?1.8% was maintained during storage of encapsulated mycelium for 12 months with larval mortalities being independent of culture age and polyol content. In conclusion, our findings indicate beneficial effects of endogenous polyols in improving shelf life of encapsulated mycelium and this may spur the successful development of microbial biocontrol agents in the future.     

Evaluating cognition and thermal physiology as components of the pace-of-life syndrome

The pace-of-life syndrome (POLS) suggests that behavioral traits are correlated and integrate within a fast–slow physiological continuum. At the fast extreme, individuals having higher metabolic rates are more active, exploratory, and bold with the opposite suite of traits characterizing those at the slow physiological extreme. A recent framework suggests that behavioral types may also differ consistently in their cognitive style. Accordingly, we propose that cognition could be further incorporated into the POLS framework comprised of behavioral and thermal physiological traits. Under this premise, fast behavioral types having high thermal traits are predicted to acquire a novel task faster but at the cost of accuracy while slow behavioral types with low thermal traits would be more attentive, responding to cues at a slower rate leading to higher accuracy and flexibility. This was tested by measuring physiological and behavioral traits in delicate skinks (Lampropholis delicata) and testing their learning ability. Correlations were detected between cognition and behavior but not thermal physiology. Contrary to our predictions, individual positioning along these axes opposed our predicted directions along the fast–slow continuum. Fast lizards preferring lower body temperatures expressed higher activity, exploration, sociality, and boldness levels, and learned the discrimination learning task at a slower rate but made the most errors. Additionally, modelling results indicated that neither thermal physiology, behavior, or their interaction influenced cognitive performance. Although the small number of animals completing the final stages of the learning assays limits the strength of these findings. Thus, we propose that future research involving a greater sample size and number of trials be conducted so as to enhance our understanding into how the integration of cognitive style, behavior, and physiology may influence individual fitness within natural populations.     

Selenium Utilization by GPX4 Is Required to Prevent Hydroperoxide-Induced Ferroptosis

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MacroH2A histone variants limit chromatin plasticity through two distinct mechanisms

MacroH2A histone variants suppress tumor progression and act as epigenetic barriers to induced pluripotency. How they impart their influence on chromatin plasticity is not well understood. Here, we analyze how the different domains of macroH2A proteins contribute to chromatin structure and dynamics. By solving the crystal structure of the macrodomain of human macroH2A2 at 1.7 Å, we find that its putative binding pocket exhibits marked structural differences compared with the macroH2A1.1 isoform, rendering macroH2A2 unable to bind ADP‐ribose. Quantitative binding assays show that this specificity is conserved among vertebrate macroH2A isoforms. We further find that macroH2A histones reduce the transient, PARP1‐dependent chromatin relaxation that occurs in living cells upon DNA damage through two distinct mechanisms. First, macroH2A1.1 mediates an isoform‐specific effect through its ability to suppress PARP1 activity. Second, the unstructured linker region exerts an additional repressive effect that is common to all macroH2A proteins. In the absence of DNA damage, the macroH2A linker is also sufficient for rescuing heterochromatin architecture in cells deficient for macroH2A.