Application of UV-cured resin as embedding/mounting media for practical, time-saving otolith specimen preparation

Abstract

19Otoliths are calcified structures located in the inner ears of fish, as in most vertebrates, 20 that are responsible primarily for the perception of gravity, balance and movement, and 21 secondarily of sound detection. Microstructural and chemical analyzes of the inner otolith 22 growth layers, called increments, constitute powerful tools to estimate fish age and 23 elucidate many life history and demographic traits of fish populations. Otolith analyzes 24 often require the production of a thin cross section that includes in the same plane of view 25 the otolith core and all microscopic layers formed from birth until the moment of collection 26 (otolith edge). Here we report on the usefulness of UV-cured resins that have become recently 27 popular among nail artists and hobbyists for otolith specimen preparation. We show that 28 single-component UV-cured resins can replace successfully and advantageously the 29 commonly used two-component Epoxy resins to obtain otolith cross sections suitable for 30 both microstructural examination and chemical analysis by electron probe microanalysis. 31 UV-cured resins provide on-demand, extremely rapid (minute-order) hardening and high 32 transparency, while providing similar adhesion and mechanical support for the otoliths 33 during processing and analysis as Epoxy resins. UV-cured resins may revolutionize 34 otolith specimen preparation practically-and time-wise, and may be particularly useful 35 in teaching and workshop situations in which time for otolith embedding is a constraint.36 37

Phenotypic/genotypic sex mismatches and temperature‐dependent sex determination in a wild population of an Old World atherinid, the cobaltcap silverside Hypoatherina tsurugae

“…A total of 56, 35, and 38 fish were chosen for the 2014, 2015, and 2016 year-classes, respectively, including both normal and phenotypic/ genotypic sex mismatches. The sagittal otoliths were extracted from the heads, cleaned in distilled water, dried, and mounted in otolith grinding orientation blocks using UV-cured resin (Tama-Koubou) (see details in Strüssmann, Miyoshi, & Mitsui, 2018). The otoliths were oriented in the blocks so as to allow grinding through the transversal plane and production of a thin cross-section including the otolith core that is already present at birth.…”

Preparation of ground sections using UV-curable acrylic adhesives

“…Micscape, www.microscopy-uk.org.uk/mag/ art97/locmount.html). A number of recent studies have shown good suitability of such media for pollen samples (Noetinger et al, 2017), wool, calcareous and siliceous microfossils (Phillips, 2020), fish otoliths (Strüssmann et al, 2018) etc. Introduction of these adhesives to industrial and household practice was enhanced by their relative safety along with fast and controlled curing (Bachmann & Cantor, 1999;Goss, 2002).…”

“…Introduction of these adhesives to industrial and household practice was enhanced by their relative safety along with fast and controlled curing (Bachmann & Cantor, 1999;Goss, 2002). Their additional microscopy-related advantages are absence of solvents and hardeners, low viscosity, no need for heating, satisfactory chemical inertness in cured state, including neutral pH and compatibility with dyes, high hardness and transparency, intentionally strong adhesion to glass (e.g., due to silane additives: Goss, 2002;Vitale et al, 2018), refractive index close to that of glass (Tennent & Townsend, 1984;Punge, 2009), absence of fluorescence and absence of significant deterioration with time (including crystallization, leakage and damaging by living organisms), traced during 35 years in some cases (Silverman, 1986;Neuhaus et al, 2017;Noetinger et al, 2017;Strüssmann et al, 2018;Phillips, 2020).…”

“…This encourages further research in the area. A number of works have shown the potential of non-specialized embedding media: acrylic adhesives with ultraviolet curing (Noetinger et al, 2017;Strüssmann et al, 2018;Phillips, 2020). Some of them are designed specifically for bonding glass.…”

Cyclododecane shaping, sublimation rate and residue analysis for the extraction of painting micro-samples from resin cross-sections

“…Their properties vary and must be adapted to the required analysis and sample type, which means the cross-section has limited use. The specific properties of resins cover hot/cold preparation, curing time and temperature 37 , 38 , transparency 39 , colour, fluorescence 40 , hardness, edge retention, and viscosity influencing the infiltration 36 . When in contact with the sample, the resin has an impact on it.…”