Search Results (8)

The mechanism controlling sex allocation in the pea aphid, Acyrthosiphon pisum (Harris), remains a crucial yet unresolved issue in the field of evolutionary ecology. This study aims to assess the influence of the presence of both self and non-self clones, along with juvenile hormone III (JH III) titer, on the sex allocation of aphid offspring. To this end, red and green clones were utilized as experimental subjects, and the agar method was employed. Initially, three distinct experimental treatments were established using sexuparae, and the daily offspring count and sex allocation in each treatment zone were recorded. Subsequently, an additional experimental condition involving mixed-clone treatments was introduced. This procedure entailed the transfer of a single sexupara and 20 oviparous females from either the red (1G + 20Rov) or green clone (1G + 20Gov) onto a leaf on agar medium. Simultaneously, a control setup with a new sexupara (1G) was established. Three days following sexupara production, a dose of 0, 25, or 50 ng of JH III was applied to the aphids’ abdomens. Subsequently, the titers of JH III in the sexuparae across each treatment group were quantified, and the extent of sex allocation was tallied. The findings demonstrated pronounced disparities in sex allocation among the various treatments and, notably, a substantial increase in the total offspring and oviparous number in the mixed-clone treatment group. The effects of mixed-clone treatment on the sex allocation patterns of the sexupara progeny could be determined by the application of exogenous JH III, indicating that JH may mediate the effects of mixed-clone treatment on sex allocation. Consequently, it can be concluded that A. pisum sexuparae possess the capability to modulate their sex allocation in response to the nature of adjacent competitor clones, thereby demonstrating a variety of sex allocation patterns. Throughout this process, JH III plays a pivotal role. Full article

The establishment of plant architecture requires coordination of distinct processes including shoot branching and apical dominance (AD). AD involves the bud apical shoot, mainly through indole-3-acetic acid (IAA) synthetized by the cells of the meristem and young leaves. The rootward flow generates an auxin gradient in the stem and buds, regulating lateral bud (LB) outgrowth. Phytochromes and AD are involved in the shade-avoidance syndrome in woody plants. However, the underlying mechanisms remain poorly understood. The aim of this study was to evaluate the sensitivity of cherry rootstocks to light, mediated by the photoreceptor phytochrome, and its effect on the role of auxin in driving branching by AD. Pharmacological treatments using transport inhibitors and a competitor of IAA were applied to transgenic lines of Colt cherry rootstock, which showed different sensitivities to light because of the ectopic expression of a rice phyA gene. Results showed different physiological behaviours among the transgenic lines and between themselves and the Colt-wt line. Exogenous IBA inhibited Colt-wt LB outgrowth, and this inhibition was less intense in transgenic lines. The IAA-inhibitors and IAA-competitor promoted branching. In in vitro phyA-transgenic plantlets, the ectopic gene induced greater branching and a higher number of buds developed in new shoots. This work confirms a positive action of phytochrome on lateral branching in cherry rootstock, playing a role in the regulation of AD. Moreover, we suggest that the confined in vitro system might now be used as a phenotyping screening to test the plasticity of the response, highlighting the behaviour of modified genotypes due to an ectopic insertion event by simple and rapid procedures. Full article

Microalga Chlorella (Chromochloris) zofingiensis has been gaining increasing attention of investigators as a potential competitor to Haematococcus pluvialis for astaxanthin and other xanthophylls production. Phytohormones, including abscisic acid (ABA), at concentrations relevant to that in hydroponic wastewater, have proven themselves as strong inductors of microalgae biomass productivity and biosynthesis of valuable molecules. The main goal of this research was to evaluate the influence of phytohormone ABA on the physiology of C. zofingiensis in a non-aseptic batch experiment. Exogenous ABA stimulated C. zofingiensis cell division, biomass production, as well as chlorophyll, carotenoid, and lipid biosynthesis. The relationship between exogenous ABA concentration and the magnitude of the observed effects was non-linear, with the exception of cell growth and biomass production. Fatty acid accumulation and composition depended on the concentration of ABA tested. Exogenous ABA induced spectacular changes in the major components of the culture microbiome of C. zofingiensis. Thus, the abundance of the representatives of the genus Rhodococcus increased drastically with an increase in ABA concentration, whereas the abundance of the representatives of Reyranella and Bradyrhizobium genera declined. The possibilities of exogenous ABA applications for the enhancing of the biomass, carotenoid, and fatty acid productivity of the C. zofingiensis cultures are discussed. Full article

To compare the effectiveness of various bioactive agents reversibly acting within a cell on a target intracellular macromolecule, it is necessary to assess effective cytoplasmic concentrations of the delivered bioactive agents. In this work, based on a simple equilibrium model and the cellular thermal shift assay (CETSA), an approach is proposed to assess effective concentrations of both a delivered bioactive agent and a target protein. This approach was tested by evaluating the average concentrations of nuclear factor erythroid 2-related factor 2 (Nrf2) and Kelch-like ECH-associated-protein 1 (Keap1) proteins in the cytoplasm for five different cell lines (Hepa1, MEF, RAW264.7, 3LL, and AML12) and comparing the results with known literature data. The proposed approach makes it possible to analyze both binary interactions and ternary competition systems; thus, it can have a wide application for the analysis of protein–protein or molecule–protein interactions in the cell. The concentrations of Nrf2 and Keap1 in the cell can be useful not only in analyzing the conditions for the activation of the Nrf2 system, but also for comparing the effectiveness of various drug delivery systems, where the delivered molecule is able to interact with Keap1. Full article

The selling price is one of the essential variables in decision making for fishers regarding the catching of a fishing resource. In the case of the Pacific Mexican lobster fishery, the price uncertainty at the beginning of the season translates into the suboptimal utilization of this resource. This work aims to predict the export price of Mexican red lobster (Panulirus) in a fishing season using demand-related market variables including price, main competitors, main buyers, and product quantities exported/imported in the market. We used the monthly export price from 2006 to 2018 for the main importer, China. As a method for price forecasting, artificial neural networks (ANNs), with and without exogenous variables (NARX, NAR), were used as an autoregressive model, while the same information was analyzed with an ARIMAX model for comparative purposes. It was found that ANNs are a useful tool that yielded better predictive power when forecasting Mexican lobster export prices compared to ARIMAX models. The predictive power was evaluated by comparing the mean square errors (MSE) of 15 models. The MSE of ANNs (73.07) was lower than that of the four ARIMAX models (88.1). It is concluded that neural networks are a valuable tool for accurately predicting prices relative to real values, an aspect of great interest for application in fishery resource management. Full article

External organic nitrogen (N) inputs can contrastingly affect the transformation and availability of N in forest soils, which is an important potential N resource and is possibly vulnerable to soil properties. Little is known about the transformation and availability of external small molecule organic N in forest soils and the underlying microbial mechanisms. Soil samples from Changbai Mountain at different altitudes (from 750 m to 2200 m) that ranged widely in soil properties were incubated with ¹³C, ¹⁵N-labeled glycine. The fate of ¹⁵N-glycine and the incorporation of ¹³C into different phospholipid fatty acids (PLFAs) were measured at the same time. The addition of glycine promoted gross N mineralization and microbial N immobilization significantly. Mineralization of glycine N accounted for 6.2–22.5% of the added glycine and can be explicable in the light of a readily mineralizable substrate by soil microorganisms. Assimilation of glycine N into microbial biomass by the mineralization-immobilization-turnover (MIT) route accounted for 24.7–52.1% of the added label and was most mightily affected by the soil C/N ratio. We also found that the direct utilization of glycine is important to fulfill microorganism growth under the lack of available carbon (C) at upper elevations. The labeled glycine was rapidly incorporated into the PLFAs and was primarily assimilated by bacteria, indicating that different groups of the microbial community were answerable to external organic N. G+ bacteria were the main competitors for the exogenous glycine. Increased intact incorporation of glycine into microbial biomass and the concentration of PLFAs in general, particularly in G+ bacteria, suggest a diversified arrangement to response changes in substrate availability. Full article

Infection by holoparasitic plants typically causes decreases in host mass, thought to be primarily as a result of resource abstraction. Inverse relationships have been noted between the number of Orobanche spp. parasites infecting a host and their mass, suggesting that the parasites compete for a shared resource pool, assumed to be recently fixed carbon (C). In clover, nitrogen (N) fixation requires a high proportion of daily photosynthate and represents a potential competitor for recently fixed C. We grew Trifolium pratense, either singly or parasitised by Orobanche minor, under high or low light levels, and with or without exogenous N supply. Low light and N deficiency led to decreased host biomass, while the damage caused by parasitism was proportionate to host mass. Parasitism caused reductions in host leaf mass, area, photosynthetic rates and shoot N concentration, but did not affect starch accumulation. Parasite mass as a proportion of system biomass was significantly higher when attached to plants grown at high light, which was attributed to higher photoassimilate supply, while the N supply had no effect. While both N limitation and parasitism caused reductions in host growth, little evidence of competition for C between N fixation and the parasites was noted. Full article

A functional ARMA-GARCH model for predicting the value-at-risk of the EURUSD exchange rate is introduced. The model implements the yield curve differentials between EUR and the US as exogenous factors. Functional principal component analysis allows us to use the information of basically the whole yield curve in a parsimonious way for exchange rate risk prediction. The data analyzed in our empirical study consist of the EURUSD exchange rate and the EUR- and US-yield curves from 15 August 2005–30 September 2016. As a benchmark, we take an ARMA-GARCH and an ARMAX-GARCHX with the 2y-yield difference as the exogenous variable and compare the forecasting performance via likelihood ratio tests. However, while our model performs better in one situation, it does not seem to improve the performance in other setups compared to its competitors. Full article