Attachment to the substrate is an important phenomenon that determines the survival of many organisms. Most insects utilize wet adhesion to support attachment, which is characterized by fluids that are secreted into the interface between the tarsus and the substrates. Previous research has investigated the composition and function of tarsal secretions of different insect groups, showing that the secretions are likely viscous emulsions that contribute to attachment by generating capillary and viscous adhesion, leveling surface roughness and providing self-cleaning of the adhesive systems. Details of the structural organization of these secretions are, however, largely unknown. Here, we analyzed footprints originating from the arolium and euplantulae of the stick insect Medauroidea extradentata using cryo-scanning electron microscopy (cryo-SEM) and white light interferometry (WLI). The secretion was investigated with cryo-SEM, revealing four morphologically distinguishable components. The 3D WLI measurements of the droplet shapes and volumes over time revealed distinctly different evaporation rates for different types of droplets. Our results indicate that the subfunctionalization of the tarsal secretion is facilitated by morphologically distinct components, which are likely a result of different proportions of components within the emulsion. Understanding these components and their functions may aid in gaining insights for developing adaptive and multifunctional biomimetic adhesive systems.

The dye injection method has been applied to many species to analyze the xylem water transport pathway in trees. However, traditional dye injection methods introduced dye tracers from the surface of cut stems, including several annual rings. Furthermore, the traditional dye injection method did not evaluate radial water movement from the outermost annual rings to the inner annual rings. In this study, we assessed the difference in radial water movement visualized by an injected dye, between stem base cut and current-year root cut samples of Salix gracilistyla Miq., with current-year roots grown hydroponically. The results showed that the number of stained annual rings in the root cut samples was smaller than that in the stem cut samples, and the percentage of stained vessels in the root cut samples was significantly smaller than that in the stem base cut samples in the second and third annual rings. In the current-year root cut samples, water transport mainly occurred in the outermost rings from the current-year roots to leaves. In addition, the theoretical hydraulic conductivity of stained vessels in the stem cut samples was higher in the current-year root cut samples in the second and third annual rings. These findings indicate that the previously reported dye injection method using stem cut samples overestimated the water transport pathway in the inner part of the stems. Moreover, previous hydraulic conductivity measurement methods might not have considered the effects of radial resistance through the annual ring boundary, and they might have overestimated the hydraulic conductivity in the inner annual rings.

Foliar water uptake (FWU) has been documented in many species and is increasingly recognized as a non-trivial factor in plant-water relationships. However, it remains unknown whether FWU is a widespread phenomenon in Pinus species, and how it may relate to needle traits such as the form and structure of stomatal wax plugs. In this contribution, these questions were addressed by studying FWU in current-year and 1-year-old needles of seven Pinus species.
We monitored FWU gravimetrically and analysed the needle surface via cryo-scanning electron microscopy. Additionally, we considered the effect of artificial wax erosion by application of the surfactant Triton X-100, which is able to alter wax crystals.
The results show for all species that (1) FWU occurred, (2) FWU is higher in old needles compared to young needles and (3) there is substantial erosion of stomatal wax plugs in old needles. FWU was highest in Pinus canariensis, which has a thin stomatal wax plug. Surfactant treatment enhanced FWU.
The results of this study provide evidence for (1) widespread FWU in Pinus, (2) the influence of stomatal wax plugs on FWU and (3) age-related needle surface erosion.

CONCLUSIONS: The characteristics of sorghum anthers at 18 classified developmental stages provide an important reference for future studies on sorghum reproductive biology and abiotic stress tolerance of sorghum pollen. Sorghum (Sorghum bicolor L. Moench) is the fifth-most important cereal crop in the world. It has relatively high resilience to drought and high temperature stresses during vegetative growing stages comparing to other major cereal crops. However, like other cereal crops, the sensitivity of male organ to heat and drought can severely depress sorghum yield due to reduced fertility and pollination efficiency if the stress occurs at the reproductive stage. Identification of the most vulnerable stages and the genes and genetic networks that differentially regulate the abiotic stress responses during anther development are two critical prerequisites for targeted molecular trait selection and for enhanced environmentally resilient sorghum in breeding using a variety of genetic modification strategies. However, in sorghum, anther developmental stages have not been determined. The distinctive cellular characteristics associated with anther development have not been well examined. Lack of such critical information is a major obstacle in the studies of anther and pollen development in sorghum. In this study, we examined the morphological changes of sorghum anthers at cellular level during entire male organ development processes using a modified high-throughput imaging variable pressure scanning electron microscopy and traditional light microscopy methods. We divided sorghum anther development into 18 distinctive stages and provided detailed description of the morphological changes in sorghum anthers for each stage. The findings of this study will serve as an important reference for future studies focusing on sorghum physiology, reproductive biology, genetics, and genomics.

Foliar water uptake has recently been suggested as a possible mechanism for the restoration of hydraulically dysfunctional xylem vessels. In this paper we used a combination of ecophysiological measurements, X-ray microcomputed tomography and cryo-scanning electron microscopy during a drought treatment to fully evaluate this hypothesis.
Based on an assessment of these methods in beech (Fagus sylvatica L.) seedlings we were able to (1) confirm an increase in the amount of hydraulically redistributed water absorbed by leaves when the soil water potential decreased, and (2) locate this redistributed water in hydraulically active vessels in the stem. However, (3) no embolism repair was observed irrespective of the organ under investigation (i.e. stem, petiole or leaf) or the intensity of drought.
Our data provide evidence for a hydraulic pathway from the leaf surface to the stem xylem following a water potential gradient, but this pathway exists only in functional vessels and does not play a role in embolism repair for beech.

Cenopalpus wainsteini (Livshitz and Mitrofanov, Proceedings Nikitsky Botanic Garden 39:1-72, 1967), a mite species in the family Tenuipalpidae, was discovered on Pinus sylvestris Thumb. in Lima, Peru, and represents the first record of this species in the Americas. Previously, only Cenopalpus pulcher (Canestrini and Fanzago Acari Academia Cientifico Veneto 5:130-142, 1876) and C. officinalis (Papaioannou-Souliotis, Annals Institut Phytopathology Benaki 15:11-27, 1986) have been reported from the Nearctic and Neotropic regions. The current paper describes and illustrates the morphological characters of female, deutonymph, protonymph and includes the first description of the larval stage of the species. Species of C. wainsteini collected in Peru were compared with specimens collected in Italy, as well as with the original description by Livschitz and Mitrofanov of specimens from Ukraine and the re-description of the species by Arabuli and Kvavadze Int J Acarology 39(7): 538-541 (2013) based on specimens collected in Georgia. Furthermore, notes on Cenopalpus lineola (Canestrini and Fanzago 1876) are included since it is frequently associated with C. wainsteini. Severe damage symptoms caused by this flat mite on its host plants were observed and are discussed herein.

An emulsion, a type of soft matter, is complexed with at least two materials in the liquid state (e.g., water and oil). Emulsions are classified into two types: water-in-oil (W/O) and oil-in-water (O/W), depending on the strength of the emulsifier. The properties and behavior of emulsions are directly correlated with the size, number, localization, and structure of the dispersed phases in the continuous phase. Therefore, an understanding of the microstructure comprising liquid-state emulsions is essential for producing and evaluating these emulsions. Generally, it is impossible for conventional electron microscopy to examine liquid specimens, such as emulsion. Recent advances in cryo-scanning electron microscopy (cryo-SEM) could allow us to visualize the microstructure of the emulsions in a frozen state. Immersion freezing in slush nitrogen has often been used for preparing the frozen samples of soft matters. This preparation could generate ice crystals, and they would deform the microstructure of specimens. High-pressure freezing contributes to the inhibition of ice-crystal formation and is commonly used for preparing frozen biological samples with high moisture content. In this study, we compared the microstructures of immersion-frozen and high-pressure frozen emulsions (O/W and W/O types, respectively). The cryo-SEM observations suggested that high-pressure freezing is more suitable for preserving the microstructure of emulsions than immersion freezing.

•  Concentrations of phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca) were determined in situ in fully hydrated arbuscular mycorrhizas by cryo-analytical scanning electron microscopy. The field- and glasshouse-grown plants (subterranean and white clovers, field pea and leek) were colonized by indigenous mycorrhizal fungi. •  The [P] in intraradical hyphae was generally 60-170 mM, although up to 600 mM was recorded, and formed strong linear relationships with [K], up to 350 mM, and [Mg], up to 175 mM. Little Ca was detected. The turgid branches of young arbuscules contained 30-50 mM P, up to 100 mM K and little Mg. Collapsing arbuscule branches and clumped arbuscules had greatly elevated Ca (30-250 mM), but otherwise differed little from young arbuscule branches in elemental concentration. •  The [P] was low or undetectable in 86% of uncolonized cortical cell vacuoles, but was generally elevated in vacuoles surrounding an arbuscule and in the liquid surrounding hyphae in intercellular spaces. •  Our results suggest that both young arbuscules and intercellular hyphae are sites for P-transfer, that Mg2+ and K+ are probably balancing cations for P anions in hyphae, and that host cells may limit arbuscule lifespan through deposition of material rich in Ca.

Cellulose-based oil-in-water (O/W) emulsions were studied by diffusing wave spectroscopy (DWS) regarding the effect of the cellulose concentration and mixing rate on the average droplet size, microrheological features and stability. Furthermore, the microstructure of these emulsions was imaged by cryo-scanning electron microscopy (cryo-SEM). The micrographs showed that cellulose was effectively adsorbed at the oil-water interface, resembling a film-like shell that protected the oil droplets from coalescing. The non-adsorbed cellulose that was observed in the continuous aqueous medium, contributed to the enhancement of the viscosity of the medium, leading to an improvement in the stability of the overall system. Generally, the higher the cellulose concentration and mixing rate, the smaller the emulsion droplets formed, and the higher was their stability. The combination of both techniques, DWS and cryo-SEM, revealed a very appealing and robust methodology for the characterization and design of novel emulsion-based formulations.

This study introduces an original concept in the development of hydrogel materials for controlled release of charged organic compounds based on semi-interpenetrating polymer networks composed by an inert gel-forming polymer component and interpenetrating linear polyelectrolyte with specific binding affinity towards the carried active compound. As it is experimentally illustrated on the prototype hydrogels prepared from agarose interpenetrated by poly(styrene sulfonate) (PSS) and alginate (ALG), respectively, the main benefit brought by this concept is represented by the ability to tune the mechanical and transport performance of the material independently via manipulating the relative content of the two structural components. A unique analytical methodology is proposed to provide complex insight into composition-structure-performance relationships in the hydrogel material combining methods of analysis on the macroscopic scale, but also in the specific microcosms of the gel network. Rheological analysis has confirmed that the complex modulus of the gels can be adjusted in a wide range by the gelling component (agarose) with negligible effect of the interpenetrating component (PSS or ALG). On the other hand, the content of PSS as low as 0.01 wt.% of the gel resulted in a more than 10-fold decrease of diffusivity of model-charged organic solute (Rhodamine 6G).