The role of the specific, profilaggrin-containing keratohyalin granules in the developing epidermis of the fetal horse hoof

The adult equine hoof is subdivided into distinct segments with various keratinization modes. In the periople and bulbs of the heel, the epidermis forms a Stratum granulosum with basophilic keratohyalin granules during soft keratinization, whereas in the coronet, wall proper, sole, and frog, the epidermis undergoes hard keratinization by keratinizing and comifying without forming keratohyalin granules. The present study tests the hypothesis that the presence of specific (profilaggrin-containing) keratohyalin granules in the hoof epidermis is correlated with the water-binding capacity and mechanical properties of the hoof horn. To identify these specific profilaggrin-containing keratohyalin granules, tissue samples of fetal hooves were studied with histochemistry, immunohistochemistry, and transmission electron microscopy. In a fetal hoof, a Stratum granulosum is formed in all hoof segments in the wake of the establishment of a segment-specific papillary body, but at differing developmental stages, starting in the coronet, then in the wall proper, and later in the sole and frog, and disappearing again in the same sequence. In the terminal part of the wall proper (i.e., Zona alba), the Stratum granu/osum is retained at least until three days after birth. In the periople and bulbs of the heel, the Stratum granulosum appears last (and is retained in the adult) when the other segments have not yet completely lost theirs. The basophilic granules in the Stratum granulosum are specific profilaggrin-containing granules that were also described in the human skin. These observations are relevant for a better understanding of certain dyskeratotic processes in the hoof epidermis

Application of ion chromatography for the reliable quantification of ammonium in electrochemical ammonia synthesis experiments : a practical guide

Assessing novel electrocatalysts for the electrochemical ammonia synthesis (EAS) requires reliable quantitative trace analysis of electrochemically produced ammonia to infer activity and selectivity. This study concerns the development of an ion chromatography (IC) method for quantitative trace analysis of ammonium in 0.1 M sulfuric acid electrolyte, which is applied to EAS gas-diffusion electrode (GDE) experiments with commercial chromium nitride as electrocatalyst. The developed IC method is highly sensitive, versatile, and reliable, achieving a limit of quantification (LOQ) of 6 μg l-1 (6 ppbmol) ammonium. The impacts of the sample matrix, dilution, and neutralization, as well as contamination, on the quantitative analysis by IC are analyzed. Experimental constraints result in an effective LOQ including dilution of 60 μg l-1 for the determination of ammonium in 0.1 M sulfuric acid electrolyte, owing to necessary sample dilution. The practical guide presented herein is intended to be very relevant for the field of EAS as a guideline and applicable to a broad range of catalyst systems and ion chromatography devices.Deutsche ForschungsgemeinschaftFederal Ministry for Economic Affairs and Climate ActionProjekt DEA

Desenvolvimento do sistema tegumentar em bovinos com idades gestacionais estimadas de 20 a 140 dias

A pele representa parte importante do sistema tegumentar, pois desempenha funções como a proteção contra desidratação, lesões e infecções, além de apresentar alto poder de renovação. Histologicamente, a pele consiste de duas camadas funcionais, morfologicamente distintas, a epiderme e a derme. As glândulas mamárias, capsula ungueal e cornos também fazem parte deste sistema. Devido à escassez de dados na literatura sobre o desenvolvimento da pele e dos anexos de natureza córnea em bovinos, o objetivo deste trabalho foi descrever as características morfológicas do desenvolvimento do sistema tegumentar durante os períodos embrionário e fetal em bovinos. Os indivíduos foram divididos em três grupos: Grupo I -embriões de 20-26 dias (n=4); Grupo II -embriões 30-47 dias (n=6) e Grupo III -fetos de 74-140 dias (n=6). Durante o desenvolvimento da pele observou-se diferentes padrões morfológicos de acordo com as regiões analisadas, apresentando índice maior de diferenciação no intervalo entre 30-47 dias de gestação. O aparelho ungueal e a glândula mamária se desenvolvem mais tardiamente entre os dias 74-140 da gestação. Em resumo, estes resultados acerca do desenvolvimento do sistema tegumentar em bovinos, poderão auxiliar na interpretação e compreensão da formação dos órgãos que o constituem, assim como para a compreensão de alterações patológicas associadas à organogênese

Keratin and S100 calcium-binding proteins are major constituents of the bovine teat canal lining

The bovine teat canal provides the first-line of defence against pathogenic bacteria infecting the mammary gland, yet the protein composition and host-defence functionality of the teat canal lining (TCL) are not well characterised. In this study, TCL collected from six healthy lactating dairy cows was subjected to two-dimensional electrophoresis (2-DE) and mass spectrometry. The abundance and location of selected identified proteins were determined by western blotting and fluorescence immunohistochemistry. The variability of abundance among individual cows was also investigated. Two dominant clusters of proteins were detected in the TCL, comprising members of the keratin and S100 families of proteins. The S100 proteins were localised to the teat canal keratinocytes and were particularly predominant in the cornified outermost layer of the teat canal epithelium. Significant between-animal variation in the abundance of the S100 proteins in the TCL was demonstrated. Four of the six identified S100 proteins have been reported to have antimicrobial activity, suggesting that the TCL has additional functionality beyond being a physical barrier to invading microorganisms. These findings provide new insights into understanding host-defence of the teat canal and resistance of cows to mastitis

Strukturelle Faktoren mit Einfluss auf die Hornqualität und Prädilektionsstellen für Erkrankungen an der Fussungsfläche der Rinderklaue

The quality of the horn of the cattle hoof varies in the different segments of the ground surface adapted to weight bearing. Horn quality is influenced by the following main factors: the keratin proteins as the most important intracellular factor, the intercellular cementing substance as the intercellular factor, and the architecture of the cluster of horn cells, i.e. the arrangement of horn cells in tubular and intertubular horn. Differences in the structure and composition of these factors and their respective combination determine the different degrees of hardness of hoof horn, which are even palpable. In special places, as i.e. the white zone, the combination of all these above-mentioned factors determines sites of predilection for diseases of the cattle hoof like white line disease