Editorial: Regulation of Pollen Tube Growth

In angiosperms, the pollen tube is a simple system composed of the vegetative cell and the two sperm cells which, nevertheless, accomplishes a very important process, essential for the life of flowering plants on Earth, i.e., sexual reproduction. In its simplicity, the pollen tube allowed plants to reproduce on land, even in the absence of water. Therefore, it is a very critical evolutionary factor. In the last 30 years, the pollen tube has been the object of study for many researchers around the world because of a number of reasons; apart from its biological importance, the pollen tube is a highly valuable cell model by which to analyze many aspects of plant cell biology (except for photosynthesis). The time course of cell wall deposition, the role of calcium ions in driving the apical growth of pollen tube, the action of signal transduction intermediates, the cell-cell communication, the mechanism of cell shape control by exocytosis/endocytosis are just some of the aspects on which it is possible to find articles in the scientific literature dealing with the pollen tube. Not to forget that the study of pollen tubes also has practical implications because the control of the reproductive process of plants also involves the study of genes, proteins and metabolites that promote or prevent the growth of pollen tubes. Therefore, controlling pollen tube growth can impact seed and fruit yields. Due to all these considerations, the Research Topic “Regulation of pollen tube growth” was meant to highlight some of the above aspects with updated considerations and special focus. These include contributions related to human health, pollen-pistil interaction, the growth of pollen tubes by exocytosis/endocytosis, and the rejection of the pollen tube in self-incompatibility processe

Editorial: Regulation of pollen tube growth, volume II

The pollen tube is an extension produced by the pollen grain when conditions are favorable; thus, the pollen tube is important in seed plant reproduction because it transports male gametes. However, it is also an excellent system for studying various plant cell processes that are common to sink organs or tissues (Kroeger and Geitmann, 2012). The pollen tube has been used to study a variety of processes, including vesicular transport, cytoskeletal organization, cell wall deposition, ion gradients, intracellular signaling. Since the pollen tube grows by contacting and signaling to pistil cells, it is also a model for studying cell-cell communication (Broz and Bedinger, 2021). Moreover, the pollen tube is involved in self-incompatibility (SI) processes that regulate reproduction and thus promote hybridization and genetic variability (Mandrone et al., 2019). SI is regulated by several factors, and in some cases, such as citrus, it is an important tool for producing seedless mandarins (Gentile et al., 2012). Pollen tube and pollen can also be targets of environmental stresses (Ledesma and Sugiyama, 2019), which can impair plant reproductive success, resulting in lower productivity of agronomically important plants and increasing allergenicity (pollinosis) (Armentia et al., 2019; Singh and Mathur, 2021)

Lubrication performance of an ammonium cation-based ionic liquid used as an additive in a polar oil.

This paper studies the tribological behavior of the ionic liquid methyltrioctylammonium bis(trifluoromethylsulfonyl)imide ([N 1888 ][NTf 2 ]) as additive at different concentrations (1.25, 2.50, 3.75 and 5.00 wt%) in a polar base oil (diester). A tribometer using a ball-on-disk reciprocating configuration under fully flooded lubrication was used at a frequency of 15 Hz, at three different loads (40, 80 and 120 N), stroke length of 4 mm, and duration of 45 min. Worn surface on the disk was studied by confocal microscopy, SEM and XPS. Main results showed similar coefficient of friction for all lubricant samples; but different wear results were found at different loads, probably related with the chemical states found for fluorine on the worn surface and the temperature-dependent adsorption-desorption processes

An equatorial ultra iron-poor star identified in BOSS

We report the discovery of SDSS J131326.89-001941.4, an ultra iron-poor red giant star ([Fe/H] ~ -4.3) with a very high carbon abundance ([C/Fe]~ +2.5). This object is the fifth star in this rare class, and the combination of a fairly low effective temperature (Teff ~ 5300 K), which enhances line absorption, with its brightness (g=16.9), makes it possible to measure the abundances of calcium, carbon and iron using a low-resolution spectrum from the Sloan Digital Sky Survey. We examine the carbon and iron abundance ratios in this star and other similar objects in the light of predicted yields from metal-free massive stars, and conclude that they are consistent. By way of comparison, stars with similarly low iron abundances but lower carbon-to-iron ratios deviate from the theoretical predictions.Comment: 6 pages, 4 figures, accepted for publication in A&

Strength, jumping, and change of direction speed asymmetries are not associated with athletic performance in elite academy soccer players

The aims of the present study were twofold: 1) to measure inter-limb asymmetries from a battery of fitness tests in youth soccer players and, 2) determine the association between asymmetry and measures of athletic performance. Sixteen elite youth soccer players (14.7 ± 0.2 years) performed a single leg Abalakov test (ABK), change of direction (COD) test over 10 m (5 + 5) and 20 m (10 + 10), and an iso-inertial power test. Subjects also performed 10 m, 20 m and 30 m sprints and a bilateral countermovement jump (CMJ), which were correlated with all ABK, COD and iso-inertial asymmetry scores. A one-way repeated measures ANOVA showed significant differences between inter-limb asymmetry scores across multiple tests (p 0.05) between the different inter-limb asymmetry scores, and between asymmetry scores and athletic performance. These findings show the test-specific nature of asymmetries in youth soccer players, with the iso-inertial power test being the most sensitive in detecting asymmetry. Moreover, the results obtained suggest that inherent asymmetry in young soccer players did not negatively impact their performance

Present and future ecological niche modeling of garter snake species from the Trans-Mexican Volcanic Belt

Articulo producto parcial de tesis doctoralLand use and climate change are affecting the abundance and distribution of species. The Trans-Mexican Volcanic Belt (TMVB) is a very diverse region due to geological history, geographic position, and climate. It is also one of the most disturbed regions in Mexico. Reptiles are particularly sensitive to environmental changes due to their low dispersal capacity and thermal ecology. In this study, we define the important environmental variables (considering climate, topography, and land use) and potential distribution (present and future) of the five Thamnophis species present in TMVB. To do so, we used the maximum entropy modeling software (MAXENT). First, we modeled to select the most important variables to explain the distribution of each species, then we modeled again using only the most important variables and projected these models to the future considering a middle-moderate climate change scenario (rcp45), and land use and vegetation variables for the year 2050 (generated according to land use changes that occurred between years 2002 and 2011). Arid vegetation had an important negative effect on habitat suitability for all species, and minimum temperature of the coldest month was important for four of the five species. Thamnophis cyrtopsis was the species with the lowest tolerance to minimum temperatures. The maximum temperature of the warmest month was important for T. scalaris and T. cyrtopsis. Low percentages of agriculture were positive for T. eques and T. melanogaster but, at higher values, agriculture had a negative effect on habitat suitability for both species. Elevation was the most important variable to explain T. eques and T. melanogaster potential distribution while distance to Abies forests was the most important variable for T. scalaris and T. scaliger. All species had a high proportion of their potential distribution in the TMVB. However, according to our models, all Thamnophis species will experience reductions in their potential distribution in this region. T. scalaris will suffer the biggest reduction because this species is limited by high temperatures and will not be able to shift its distribution upward, as it is already present in the highest elevations of the TMVB.Universidad Autónoma del Estado de México: 4047/2016SF. CONACY

Is the future universe singular: Dark Matter versus modified gravity?

The fundamental problem of the occurrence/removal of finite-time future singularity in the universe evolution for coupled dark energy (DE) is addressed. It is demonstrated the existence of the (instable or local minimum) de Sitter space solution which may cure the Type II or Type IV future singularity for DE coupled with DM as the result of tuning the initial conditions. In case of phantom DE, the corresponding coupling may help to resolve the coincidence problem but not the Big Rip (Type I) singularity issue. We show that modified gravity of special form or inhomogeneous DE fluid may offer the universal scenario to cure the Type I,II,III or IV future singularity of coupled (fluid or scalar) DE evolution.Comment: LaTeX 9 page

Lubrication Properties of the Ionic Liquid Dodecyl-3 Methylimidazolium bis(trifluoromethylsulfonyl)imide

© 2017, Springer Science+Business Media, LLC, part of Springer Nature. The ionic liquid (IL) dodecyl-3 methylimidazolium bis(trifluoromethylsulfonyl)imide was tested as neat lubricant and as additive (at 1 and 4 wt%) in a polar oil (diester). Tribological tests were performed using a reciprocating configuration for 90 min at 30 and 70 N, 10 Hz, 4 mm stroke length, and at room temperature and 100 °C. Wear volume and surface–IL interaction were determined by confocal microscopy, SEM, and XPS. The main findings were: Neat ionic liquid showed the best tribological behavior; the IL-containing mixtures had similar behavior than the base oil at the lower load; meanwhile, the mixture with 4 wt% of IL outperformed the antiwear behavior of the neat base oil at the higher load; surface–IL chemical interaction was found mainly at 100 °C

Airborne Pollen, Allergens, and Proteins: A Comparative Study of Three Sampling Methods

Nowadays, there is a wide range of different methods available for the monitoring of pollen and allergens, but their relative efficiency is sometimes unclear, as conventional pollen monitoring does not thoroughly describe pollen allergenicity. This study aims to evaluate airborne pollen, allergen, and protein levels, associating them with meteorological and chemical parameters. The sampling was performed in Bologna (Italy) during the grass flowering period, with three different devices: a Cyclone sampler (CS), a Dicothomous sampler (DS), and a Berner impactor (BI). Total proteins were extracted from aerosol samples, and grass allergens Phl p 1 and Phl p 5 were quantified by ELISA. Airborne Poaceae pollen concentrations were also evaluated, using a Hirst-type trap. Proteins and allergens collected by CS resulted about ten times higher than those collected by the other two instruments, possibly due to their different cut-offs, while DS and BI results appeared consistent only for the total proteins collected in the fine fraction (1.3 vs. 1.6 mu g/m(3)). Airborne proteins correlated neither with Poaceae pollen nor with its aeroallergens, while aeroallergens correlated with pollen only in the coarse particulate, indicating the presence of pollen-independent aeroallergens in the fine particulate, promoted by high wind speed