Amidine derived inhibitors of acid-sensing ion channel-3 (ASIC3)

A series of indole amidines modified at the 2-position of the indole ring were evaluated as inhibitors of Acid-Sensing Ion Channel-3 (ASIC3), a novel target for the treatment of chronic pain.     

Amiloride derived inhibitors of acid-sensing ion channel-3 (ASIC3)

A series of amiloride derivatives modified at the 5-position of the pyrazine ring were evaluated as inhibitors of acid-sensing ion channel-3 (ASIC3), a novel target for the treatment of chronic pain.     

Behavioural Tests Reveal Severe Visual Deficits in the Strictly Subterranean African Mole‐Rats (Bathyergidae) but Efficient Vision in the Fossorial Rodent Coruro (Spalacopus cyanus,Octodontidae)

Vision has long been considered purposeless in the dark underground ecotope. However, recent anatomical studies revealed an unexpected diversity of ocular and retinal features and various degrees of development of the visual system in mammals with predominantly subterranean activity, and have suggested retention of basic visual capabilities even in some strictly subterranean mammals such as the African mole‐rats. Behavioural tests assessing image‐forming vision have not yet been conducted in subterranean mammals. Here, we investigated the visual capacities in three species of the African mole‐rats, namely the giant mole‐rat Fukomys mechowii, the Mashona mole‐rat Fukomys darlingi and the silvery mole‐rat Heliophobius argenteocinereus, in the fossorial coruro Spalacopus cyanus and the inbred C57L/J mouse. The behavioural assays performed in this study revealed severe visual deficits in all three species of mole‐rats. The absence of the visual placing reflex suggested impairment of either image‐forming vision or visuomotor integration. The random choice between the shallow and the deep side of a visual cliff clearly demonstrated inability of mole‐rats to perceive depth. The nesting assay did not yield conclusive evidence regarding the capacity for visually guided spatial orientation in the only tested species, the giant mole‐rat. In contrast, both the coruro and the mouse exhibited a clear placing reaction and preferred the shallow side of the visual cliff, implying functional image‐forming vision. Thus, the behavioural data gathered in this study show that vision is seriously compromised in the strictly subterranean, congenitally microphthalmic African mole‐rats but efficient (i.e. comparable to that of surface‐dwelling rodents) in a species with regular surface activity, the coruro.     

GD2 ganglioside-binding antibody 14G2a and specific aurora A kinase inhibitor MK-5108 induce autophagy in IMR-32 neuroblastoma cells

The process of autophagy and its role in survival of human neuroblastoma cell cultures was studied upon addition of an anti-GD2 ganglioside (GD2) 14G2a mouse monoclonal antibody (14G2a mAb) and an aurora A kinase specific inhibitor, MK-5108. It was recently shown that combination of these agents significantly potentiates cytotoxicity against IMR-32 and CHP-134 neuroblastoma cells in vitro, as compared to the inhibitor used alone. In this study we gained mechanistic insights on autophagy in the observed cytotoxic effects exerted by both agents using cytotoxicity assays, RT-qPCR, immunoblotting, and autophagy detection methods. Enhancement of the autophagy process in the 14G2a mAb- and MK-5108-treated IMR-32 cells was documented by assessing autophagic flux. Application of a lysosomotropic agent—chloroquine (CQ) affected the 14G2a mAb- and MK-5108-stimulated autophagic flux. It is our conclusion that the 14G2a mAb (40 μg/ml) and MK-5108 inhibitor (0.1 μM) induce autophagy in IMR-32 cells. Moreover, the combinatorial treatment of IMR-32 cells with the 14G2a mAb and CQ significantly potentiates cytotoxic effect, as compared to CQ used alone. Most importantly, we showed that interfering with autophagy at its early and late step augments the 14G2a mAb-induced apoptosis, therefore we can conclude that inhibition of autophagy is the primary mechanism of the CQ-mediated sensitization to the 14G2a mAb-induced apoptosis. Although, there was no virtual stimulation of autophagy in the 14G2a mAb-treated CHP-134 neuroblastoma cells, we were able to show that PHLDA1 protein positively regulates autophagy and this process exists in a mutually exclusive manner with apoptosis in PHLDA1-silenced CHP-134 cells.     

Synthesis and physicochemical studies of amyloidogenic hexapeptides derived from human cystatin C

Human cystatin C (hCC) is a low molecular mass protein that belongs to the cystatin superfamily. It is an inhibitor of extracellular cysteine proteinases, present in all human body fluids. At physiological conditions, hCC is a monomer, but it has a tendency to dimerization. Naturally occurring hCC mutant, with leucine in position 68 substituted by glutamine (L68Q), is directly involved in the formation of amyloid deposits, independently of other proteins. This process is the primary cause of hereditary cerebral amyloid angiopathy, observed mainly in the Icelandic population. Oligomerization and fibrillization processes of hCC are not explained equally well, but it is proposed that domain swapping is involved in both of them. Research carried out on the fibrillization process led to new hypothesis about the existence of a steric zipper motif in amyloidogenic proteins. In the hCC sequence, there are 2 fragments which may play the role of a steric zipper: the loop L1 region and the C‐terminal fragment. In this work, we focused on the first of these. Nine hexapeptides covering studied hCC fragment were synthesized, and their fibrillogenic potential was assessed using an array of biophysical methods. The obtained results showed that the studied hCC fragment has strong profibrillogenic propensities because it contains 2 fragments fulfilling the requirements for an effective steric zipper located next to each other, forming 1 super‐steric zipper motif. This hCC fragment might therefore be responsible for the enhanced amyloidogenic properties of dimeric or partially unfolded hCC.     

Activity of beavers as an ecological factor that affects the benthos of small rivers - a case study in the Żylica River (Poland)

The Eurasian beaver (Castor fiber) has a greater impact on local ecosystems than other herbivores, and the affected area exceeds the range of its presence. Its activity may change or create new habitats by modifying the availability of the biotic and abiotic resources available not only to beavers, but also to other groups of animals. Our aim was to study how beaver activity affects the benthos composition in a small river and in a beaver pond. The way in which beavers function in the case of small rivers has received little attention. The study showed a lower density of benthos above the dam (beaver pond - 1467 ind./m²) compared to the river (3147 ind./m²). Below the dam, the diversity of Trichoptera and Coleoptera was greater, while Diptera were more abundant in the beaver pond. Betidae were a constant component in the benthos assemblages and were most abundant in the beaver pond. Collectors-gatherers and predators were the most numerous in the beaver pond. Decreasing percentages of collectors-gatherers were observed with an increased abundance of collectors-filterers and shredders in the river. All of the ratio values except the P/T FFG (Predators to total of all other groups) were lower in the beaver pond compared to the river. The % EPT (Ephemeroptera Plecoptera and Trichoptera) was also greater in the beaver pond. Small differences in the physicochemical properties of the water and organic matter content in the bottom sediments were found both above and below the beaver dam.     

Development of the plerocercoid I of Ophiotaenia europaea in reptiles

The existence of a two-host life-cycle in ophiotaeniid proteocephalideans was tested experimentally using Ophiotaenia europaea as a model. Three species of reptiles, Natrix natrix, Natrix tessellata and Lacerta viridis, were fed with experimentally infected copepods containing a large number of infective plerocercoids I. A few plerocercoids, most of which were dead, corresponding morphologically to the plerocercoid II developmental stage of O. europaea, were found encysted in the intestinal wall of N. natrix (8 days p.i.), N. tessellata (5 and 150 days p.i.) and L. viridis (40 days p.i.), while no plerocercoids or adult worms were recovered from their intestines. The results indicate that the infective plerocercoid I of O. europaea cannot undergo further development when ingested directly by the final host (a reptile), and that environmental temperature stimuli cannot initiate a reverse plerocercoid migration to the gut followed by strobilization.     

Cleistogamy and phylogenetic position of Viola uliginosa (Violaceae) re‐examined

Viola uliginosa is an endangered species throughout its range in Central Europe. Based on an unusual combination of morphological characters, including a reported lack of cleistogamous (CL) flowers, it was previously placed in the monotypic subsection Repentes, section Viola. Available individual phylogenetic analyses identify V. uliginosa as a lineage deeply embedded in section Viola, but hitherto its exact position was unknown. Here we confirm the occurrence of cleistogamy in V. uliginosa. Unlike other species of section Viola, V. uliginosa produced both chasmogamous and CL flowers at the same time, not at different times of the year (seasonal cleistogamy). The two flower types differed conspicuously in morphology and microstructure, especially in size and shape of the pistil and stamens as confirmed by scanning electron microscopy. Secondly, we resolved the phylogenetic position of V. uliginosa as a lineage deeply embedded in subsection Rostratae by means of a multigene multispecies coalescent analysis using *BEAST. In this analysis, V. mirabilis and V. uliginosa were successive sisters to the rest of subsection Rostratae and, because allopolyploids exist between V. mirabilis and the last one, subsection Rostratae needs to comprise all these taxa to be monophyletic. The evolution of key morphological traits is briefly discussed.