A functional and morphological approach to evaluate the vertical migration of estuarine intertidal nematodes during a tidal cycle

We tested herein the hypothesis that exposure time significantly contributes to the vertical distribution profile of nematodes during a tidal cycle as a function of distinct feeding and locomotion behaviors, conditioned by body morphology. We showed that the vertical distribution profile of the slender with filiform tail, numerically dominant Terschellingia longicaudata is in fact significantly correlated with sediment changes induced by tidal variation. Conversely, none of the other nematode species showed unequivocal evidence of vertical migration. Horizontal spatial heterogeneity also influenced the vertical distribution of nematode associations, probably as a response to varying temperature and desiccation levels at the sediment surface. The resulting vertical profiles for individual or species groups are a trade-off among locomotory and feeding strategies and concordant morphological adaptations.     

The role of calcium on protein secretion of the albumen gland in Helisoma duryi (Gastropoda)

Abstract. The albumen gland of the freshwater pulmonate snail Helisoma duryi produces and secretes the perivitelline fluid, which coats fertilized eggs and provides nutrients to the developing embryos. It is known that perivitelline fluid secretion is stimulated by dopamine through the activation of a dopamine D₁‐like receptor, which in turn stimulates cAMP production leading to the secretion of perivitelline fluid. This paper examines the glandular release of perivitelline fluid and provides evidence for the role of Ca²⁺ in the regulated secretion of perivitelline fluid based on protein secretion experiments and inositol 1,4,5‐trisphosphate assays. Dopamine‐stimulated protein secretion by the albumen gland is reduced in Ca²⁺‐free medium or in the presence of plasma membrane Ca²⁺ channel blockers, although the Ca²⁺ channel subtype involved is unclear. In addition, dopamine‐stimulated protein secretion does not directly involve phospholipase C‐generated signaling pathways and Ca²⁺ release from intracellular stores. Sarcoplasmic/endoplasmic reticulum Ca²⁺‐ATPase inhibitors had little effect on protein secretion when applied alone; however, they potentiated dopamine‐stimulated protein secretion. Dantrolene, an inhibitor of ryanodine receptors, 8‐(N,N‐diethylamino)‐octyl‐3,4,5‐trimethoxybenzoate hydrochloride, a nonspecific inhibitor of intracellular Ca²⁺ channels, and 2‐aminoethyldiphenylborate, an inhibitor of inositol 1,4,5‐trisphosphate receptors, did not suppress protein secretion, suggesting Ca²⁺ release from internal stores does not directly regulate protein secretion. Thus, the influx of Ca²⁺ from the extracellular space appears to be the major pathway mediating protein secretion by the albumen gland. The results are discussed with respect to the role of Ca²⁺ in controlling exocytosis of proteins from the albumen gland secretory cells.     

Commentary regarding: “Activity determination of FAD‐dependent glucose dehydrogenase immobilized in PEDOT: PSS‐PVA composite films for biosensor applications”

In the light of continuous improvement and optimization, recent experiments that the authors conducted give new insights into the applied evaluation method of Riegel et al. [1]: Thorough investigations of the previous results regarding the usage of the Lowry Assay showed discrepancies in the determination of the released amount of protein in the analysis solution. The accurate quantification of this parameter is crucial as it directly influences the calculation of the residual enzymatic activity. In concrete terms, this finding has a major impact on the presented and discussed results in the article “Activity determination of FAD‐dependent glucose dehydrogenase immobilized in PEDOT: PSS‐PVA composite films for biosensor applications” [1]. Thus, this commentary addresses the new insights concerning the applied evaluation method, explains necessary revisions and discusses new conclusions derived from the adjusted evaluation method.     

Comparative analysis of qualitative anatomical characters of <Emphasis Type="Italic">Trifolium</Emphasis> L. (Fabaceae) and their taxonomic implications: preliminary results

A comparative anatomical study of 20 Trifolium species was carried out using light and scanning electron microscopy in order to investigate the structure of their vegetative and reproductive organs and to evaluate the taxonomic significance of qualitative characters for distinguishing between the taxa. Characters were coded and analysed by multiple correspondence analysis. The combination of selected qualitative anatomical characters of the petiole, stipules, stem, peduncle and calyx (not previously studied in detail) were significant in delimiting sections of the genus Trifolium, but not for identification of species. The characters that contributed most to the separation of sections were peduncle cross-section shape, the presence of trichomes on the calyx tubes and the presence of trichomes and crystals in the stipules.     

Anatomical characteristics and antioxidant properties of Euphorbia nicaeensis ssp. glareosa

Anatomical analyses found that leaves of Euphorbia nicaeensis ssp. glareosa are isolateral, amphistomatous, with two layers of palisade cells on the adaxial and one on the abaxial side. Laticifers are present by vascular bundles, in palisade and spongy tissue. Stem laticifers are located in the pericyclic ring, adjacent to the phloem, in cylinder parenchyma and medullar rays. The structure of pleiochasium and dichasium peduncle is similar to the stem structure. Plants from typical steppe habitat show more xeromorphic features. Phytochemical screening of extracts showed presence of catecholes, flavonoids, tannins, saponins, free quinone derivatives and absence of anthocyanins, leucoanthocyanins, alkaloids, steroid compounds and essential oils. Our results showed that the examined taxon was partially susceptible to the action of reactive oxygen species, such as O₂·⁻ and ·OH. The higher quantities of ROS thus provoked an antioxidative response from the plant, both in an enzymatic and non-enzymatic manner. Stable anatomical structure, presence and distribution of laticifers and effective antioxidant properties when exposed to ROS, make Euphorbia nicaeensis subsp. glareosa potentially interesting for further pharmaceutical and phytochemical examinations.