Enigmatic adult overwintering in damselflies: coexistence as weaker intraguild competitors due to niche separation in time

Odonata, like most freshwater invertebrates, tend to overwinter in water due to the thermal properties of a water environment. Winter damselflies (genus Sympecma), however, hibernate as adults in terrestrial habitats. The strategy of adult overwintering combined with high mortality is associated with several unique adaptations to semiarid conditions, but winter damselflies maintain this unique life history throughout almost the entire Palaearctic. We assume that the unique strategy of adult overwintering in temperate zones is indirectly maintained by niche separation in time. We used phenological data from the Czech Republic to compare the seasonal phenology of Sympecma spp. with other coexisting odonate species. Seasonal population growth patterns between S. fusca and other coexisting species representing different life histories were compared using GLMMs and LME. The models showed negative non-linear dependence between the population growth of S. fusca and the estimated abundance of compared species. We found that the specific strategy of adult overwintering makes it possible to avoid seasonal maxima of competition and predation in adult and larval stages. Adults may benefit from free niches during spring while larvae may benefit from size advantage among intraguild competitors and optimal conditions for development.     

Development of peptides specifically modulating the activity of KLK2 and KLK3

The prostate produces several proteases, the most abundant ones being kallikrein-related peptidase 3 (KLK3, PSA) and KLK2 (hK2), which are potential targets for tumor imaging and treatment. KLK3 expression is lower in malignant than in normal prostatic epithelium and it is further reduced in poorly differentiated tumors, in which the expression of KLK2 is increased. KLK3 has been shown to inhibit angiogenesis, whereas KLK2 may mediate tumor growth and invasion by participating in proteolytic cascades. Thus, it may be possible to control prostate cancer growth by modulating the proteolytic activity of KLK3 and KLK2. We have developed peptides that very specifically stimulate the activity of KLK3 or inhibit that of KLK2. Using these peptides we have established peptide-based methods for the determination of enzymatically active KLK3. The first-generation peptides are unstable in vivo and are rapidly cleared from the circulation. Currently we are modifying the peptides to make them suitable for in vivo applications. We have been able to considerably improve the stability of KLK2-binding peptides by cyclization. In this review we summarize the possible roles of KLK3 and KLK2 in prostate cancer and then concentrate on the development of peptides that modulate the activity of these proteases.     

The in vitro effects of selected substances and nanomaterials against Diaporthe eres,Diplodia seriata and Eutypa lata

Grapevine trunk pathogens (GTPs) cause serious damage to grapevines and have significant economic impacts. There is no effective protection against grapevine trunk diseases. Newly designed AgSe nanoparticles (NPs) and CuSe NPs, single-element Ag NPs, Cu NPs, Se NPs and selected chemicals or chemical agents such as sodium arsenite, 8-hydroxyquinoline, silver nitrate, colloidal silver, Altron Silver fertilizer and silver thiosulfate complex (NH₄)₃/Ag(S₂O₃)₂ were tested in vitro against two serious GTPs Diaporthe eres, Eutypa lata and Diplodia seriata isolated from walnut. The most significant inhibition of fungal growth was observed for silver nitrate and AgSe NPs, which showed the highest level of half the maximum effective EC₅₀ concentration with the lowest concentrations. In the case of silver nitrate at a concentration of 1000 mg L⁻¹, 79% inhibition of mycelial growth was observed for the pathogen E. lata, 48% for D. seriata and 54% for D. eres. AgSe NPs, in which the concentration of silver is 2588 mg L⁻¹ and that of selenium is 902 mg L⁻¹, showed 68% inhibition of mycelial growth in the pathogen E. lata, 54% in D. seriata and 58% in D. eres.     

Proton extrusion and attendant transport phenomena in Candida utilis induced by ethanol

Summary Ion fluxes after ethanol addition to Candida utilis depend crucially on aeration (air versus oxygen). In O₂-aerated non-growing cells ethanol causes an H ⁺ / K ⁺ exchange and an extrusion of acetate and lactate accompanied mostly by K ⁺, and their subsequent reimportation together with H ⁺. Cells from continuous culture display generally stronger acidification and more marked K ⁺ movements than non-growing ones. Offprint requests to: A. Prell     

Skin tests with autologous cholesteryl hemisuccinate treated tumour cells in cancer patients

Summary Skin tests with autologous irradiated tumour cells were performed in 20 malignant melanoma, 7 breast and 6 ovarian cancer patients. In the majority of cases evident reaction was noted with cholesteryl hemisuccinate (CHS)-treated cells while the reaction with untreated cells was mostly negative.No correlation was found between this reactivity and the ability of patients to be sensitized to DNCB and to their reactivity to PPD. No correlation was found between reactivity to CHS-treated tumour cells and the stage and course of the disease.     

The role of quarternary structure in fluorescent protein stability

The stability of fluorescent proteins (FPs) is of great importance for their use as reporters in studies of gene expression, protein dynamics and localization in cell. A comparative analysis of conformational stability of fluorescent proteins, having different association state was done. The list of studied proteins includes EGFP (monomer of green fluorescent protein, GFP), zFP506 (tetramer GFP), mRFP1 and "dimer2" (monomer and dimmer of red fluorescent protein), DsRed1 (red tetramer). The character of fluorescence intensity changes induced by guanidine hydrochloride (GdnHCl) of these proteins differs significantly. Green tetramer zFP506 has been shown to be more stable than green monomer EGFP, red dimmer "dimer2" has been shown to be less stable than red tetramer DsRed1, while red monomer mRFP1 has been shown to be practically as stable as tetramer DsRedl. It is concluded that the quaternary structure, being an important stabilizing factor, does not represent the only circumstance dictating the dramatic variations between fluorescent proteins in their conformational stability.     

Diel changes in habitat use by dragonflies: Nocturnal roosting site selection by the threatened dragonfly Sympetrum depressiusculum (Odonata: Libellulidae)

Although it is well recognized that insects' habitat use and requirements may change during the season, very little attention has been devoted to diel habitat changes in most insects. In this study, we compared habitat utilization patterns of Sympetrum depressiusculum (Selys, 1841) adult dragonflies between daytime activities and nocturnal roosting. During daytime, we captured and marked adult individuals with fluorescent paint in different habitats. At night, we searched, using UV light, for marked individuals that remained on the habitats. We found that habitat selection for daytime activities and that for nocturnal roosting differed significantly. Adults clearly avoided ponds and their immediate surroundings for nocturnal roosting, whereas this habitat type was frequently utilized for daytime activities. We suggest that nocturnal avoidance of the riparian area is associated with lower temperatures, which adversely affect thermoregulation, and that selection of specific habitats for nocturnal roosting is closely associated with vegetation structure providing stability during windy nights and serving as a suitable shelter. Such habitat properties are found especially on fallow land, a habitat type whose representation in agricultural areas has been gradually decreasing in recent decades.