Thermal excitation of Trivelpiece-Gould modes in a pure electron plasma

Thermally excited plasma modes are observed in trapped, near-thermal-equilibrium pure electron plasmas over a temperature range of 0.05<T<5 eV. The measured thermal emission spectra together with a separate measurement of the wave absorption coefficient uniquely determines the temperature. Alternately, kinetic theory including the antenna geometry and the measured mode damping (i.e. spectral width) gives the plasma impedance, obviating the reflection measurement. This non-destructive temperature diagnostic agrees well with standard diagnostics, and may be useful for expensive species such as anti-matter

A Comparative Analysis of the Morphology and Evolution of Permanent Sperm Depletion in Spiders

Once thought to be energetically cheap and easy to produce, empirical work has shown that sperm is a costly and limited resource for males. In some spider species, there is behavioral evidence that sperm are permanently depleted after a single mating. This extreme degree of mating investment appears to co-occur with other reproductive strategies common to spiders, e.g. genital mutilation and sexual cannibalism. Here we corroborate that sperm depletion in the golden orb-web spider Nephila clavipes is permanent by uncovering its mechanistic basis using light and electron microscopy. In addition, we use a phylogeny-based statistical analysis to test the evolutionary relationships between permanent sperm depletion (PSD) and other reproductive strategies in spiders. Male testes do not produce sperm during adulthood, which is unusual in spiders. Instead, spermatogenesis is nearly synchronous and ends before the maturation molt. Testis size decreases as males approach their maturation molt and reaches its lowest point after sperm is transferred into the male copulatory organs (pedipalps). As a consequence, the amount of sperm available to males for mating is limited to the sperm contained in the pedipalps, and once it is used, males lose their ability to fertilize eggs. Our data suggest that PSD has evolved independently at least three times within web-building spiders and is significantly correlated with the evolution of other mating strategies that limit males to monogamy, including genital mutilation and sexual cannibalism. We conclude that PSD may be an energy-saving adaptation in species where males are limited to monogamy. This could be particularly important in web-building spiders where extreme sexual size dimorphism results in large, sedentary females and small, searching males who rarely feed as adults and are vulnerable to starvation. Future work will explore possible energetic benefits and the evolutionary lability of PSD relative to other mate-limiting reproductive behaviors

Mate choice for genetic quality when environments vary: suggestions for empirical progress

Mate choice for good-genes remains one of the most controversial evolutionary processes ever proposed. This is partly because strong directional choice should theoretically deplete the genetic variation that explains the evolution of this type of female mating preferences (the so-called lek paradox). Moreover, good-genes benefits are generally assumed to be too small to outweigh opposing direct selection on females. Here, we review recent progress in the study of mate choice for genetic quality, focussing particularly on the potential for genotype by environment interactions (GEIs) to rescue additive genetic variation for quality, and thereby resolve the lek paradox. We raise five questions that we think will stimulate empirical progress in this field, and suggest directions for research in each area: 1) How is condition-dependence affected by environmental variation? 2) How important are GEIs for maintaining additive genetic variance in condition? 3) How much do GEIs reduce the signalling value of male condition? 4) How does GEI affect the multivariate version of the lek paradox? 5) Have mating biases for high-condition males evolved because of indirect benefits

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly

Variation in Tetragnathid spermathecal structures and sperm competition with descriptions of natural history

The study of variation in arachnid genitalic structures has contributed to the fields of systematics and sexual selection. Simon (1892--1903) in his Histoire Naturelle des Araignees first divided the ecribellate higher spiders into two groups, the Haplogynae and Entelegynae, using reproductive morphology. Spider genitalia have been used as a taxonomic tool for distinguishing between taxa because of their species-specific morphological variation. Variation in spider genitalic morphology has inspired evolutionary biologists to test mechanisms of sexual selection by which the variation could evolve, ranging from Fisherian run-away selection, chase-away selection, and sperm competition. The Tetragnathidae are particularly interesting for a comparison between haplogyne and entelegyne reproductive morphologies. Within this entelegyne family, a reversal to haplogyny has occurred. Fifteen representative members of this family and four outgroup taxa were examined with scanning and transmission electron microscopy in order to describe the fine structure of spermathecae, including the distribution and density of spermathecal gland pores. While the function(s) of the glandular secretion are unknown, the distribution and density of spermathecal gland pores is discussed with regard to possible functions of the glandular secretion. The potential influence of spermathecal gland secretions on mating behavior and sperm competition is considered. Sperm release patterns have been examined in entelegynes, but previously were not available for haplogynes. The relationship between copulation duration and sperm release was determined in Tetragnatha versicolor, the first examination of sperm release patterns in any haplogyne spider. In this species, copulation duration is not proportional to sperm release. To examine the relative influence of spermathecal morphology and numerical sperm competition on paternity, sperm release and paternity was assessed in the entelegyne Nephila clavipes and the haplogyne Tetragnatha versicolor. The data clearly support differential sperm release between males as the cause of previously reported first-male advantage in Nephila clavipes and the mixed paternity found for N. clavipes and Tetragnatha versicolor in this study. The natural history, mating behavior, and sperm release were determined for a previously unstudied tetragnathid species, Glenognatha emertoni . This is the second examination of haplogyne sperm release behavior as well as the first description of an unusual escape behavior

Fibrin fragment E potentiates TGF-beta-induced myofibroblast activation and recruitment

Fibrin is an essential constituent of the coagulation cascade, and the formation of hemostatic fibrin clots is central to wound healing. Fibrin clots are over time degraded into fibrin degradation products as the injured tissue is replaced by granulation tissue. Our goal was to study the role of the fibrin degradation product fragment E (FnE) in fibroblast activation and migration. We present evidence that FnE is a chemoattractant for fibroblasts and that FnE can potentiate TGF-beta-induced myofibroblast formation. FnE forms a stable complex with alpha(v)beta(3) integrin, and the integrin beta(3) subunit is required both for FnE-induced fibroblast migration and for potentiation of TGF-beta-induced myofibroblast formation. Finally, subcutaneous infusion of FnE in mice results in a fibrotic response in the hypodermis. These results support a model where FnE released from clots in wounded tissue promote wound healing and fibrosis by both recruitment and activation of fibroblasts. Fibrin fragment E could thus represent a therapeutic target for treatment of pathological fibrosis