An enemy of your enemy is your friend: Impact of predators on aggregation behavior of gammarids

Predation pressure may affect many aspects of prey behavior, including forming groups and changes in social interactions. We studied the aggregation behavior of competing gammarids Dikerogammarus villosus and Pontogammarus robustoides (Amphipoda, Crustacea) to check whether they modify their preferences for conspecifics or heterospecifics in response to predator (the racer goby Babka gymnotrachelus) kairomones in the presence or absence of stone shelters (alternative protection source). Both species exhibited preferences toward shelters occupied by conspecifics over empty shelters and conspecifics apart from shelters, suggesting that their aggregation depends not only on habitat heterogeneity, but also on their social interactions. Moreover, gammarids in the presence of shelters (safer conditions) preferred conspecifics over heterospecifics, but predator kairomones made them form aggregations irrespective of species. In the predator presence, P. robustoides increased its aggregation level only in the sheltered conditions, whereas D. villosus exhibited this response only in the absence of shelters, suggesting that this behavior can protect it against predators. Therefore, we tested the antipredator effectiveness of D. villosus aggregations by exposing them to fish predation. Gobies foraged most effectively on immobile single gammarids compared to moving and aggregated individuals. Fish also avoided aggregated prey, confirming the protective character of aggregations. We have demonstrated that the predator presence increases aggregation level of prey gammarids and affects their social behavior by reducing antagonistic interactions and avoidance between competing species. This is likely to affect their distribution and functioning in the wild, where predator pressure is a standard situation.     

Design of a resilient ring for middle ear’s chamber stapes prosthesis

Abstract

This paper presents the process of designing a new elastic element replacing a membrane in the chamber stapes prosthesis (ChSP). The results of the study are volume displacement characteristics obtained for the prosthesis and physiological stapes. Simulation tests on a 3D CAD model have confirmed that a properly designed ring can stimulate perilymph with the same or greater efficacy as the physiological stapes footplate placed on the elastic annular ligament. The ChSP with a new elastic element creates a good chance of improving hearing in patients suffering from otosclerosis.     

Structural study of GCDFP-15/gp17 in disease versus physiological conditions using a proteomic approach

Gross cystic disease fluid protein (GCDFP-15), also known as prolactin-inducible protein (PIP), is a specific breast tumor marker. GCDFP-15/PIP is also identified as gp17 and/or seminal actin-binding protein (SABP) from seminal vesicles and as extraparotid glycoprotein (EP-GP) from salivary glands. It is an aspartyl proteinase able to specifically cleave fibronectin (FN), suggesting a possible involvement in mammary tumor progression and fertilization. Other functions were attributed to this protein(s) on the basis of its ability to interact with an array of molecules such as CD4, actin, and fibrinogen. We investigated the structure of the protein(s) under disease versus physiological conditions by RP-HPLC chromatography, ProteinChip technology, and QStar MS/MS mass spectrometry. The proteins behaved differently when examined by RP-HPLC chromatography and surface-enhanced laser desorption ionization time-of-flight (SELDI-TOF) mass spectrometry, suggesting different conformations and/or tissue-specific posttranslational modifications of the proteins, although their primary structure was identical by MS/MS analysis. Both showed a single N-glycosylation site. A different N-linked glycosylation pattern was observed in pathological GCDFP-15/PIP as compared with physiological gp17/SABP protein by coupling enzymatic digestion and ProteinChip technology. Furthermore, taking advantage of ProteinChip technology, we analyzed the interaction of both proteins with CD4 and FN. We observed that the physiological form was mainly involved in the binding to CD4. Moreover, we defined the specific FN binding-domain of this protein. These data suggested that, depending on its conformational state, the protein could differently bind to its various binding molecules and change its function(s) in the microenviroments where it is expressed.     

Study of the first hours of microvinification by the use of osmotic stress-response genes as probes

When yeast cells are inoculated into grape must for vinification they find stress conditions because of osmolarity, which is due to very high sugar concentration, and pH lower than 4. In this work an analysis of the expression of three osmotic stress induced genes (GPD1, HSP12 and HSP104) under microvinification conditions is shown as a way to probe those stress situations and the regulatory mechanisms that control them. The results indicate that during the first hours of microvinification there is an increase in the GPDI mRNA levels with a maximum about one hour after inoculation, and a decrease in the amount of HSP12 and HSP104 mRNAs, although with differences between them. The RNA steady-state levels of all the genes considered, and in some cases the microvinification progress are significantly affected by the composition of the must (pH, nature of the osmotic agent and carbon source). These results point out the importance of the control of these parameters and the yeast molecular response during the first hours of vinification for an accurate winemaking process.     

A study of variation in the pollen spectra of honeys sampled from the Baixa Limia‐Serra do Xurés Nature Reserve in north‐west Spain

The pollen content of eleven honey samples from ten different apiaries in the Baixa Limia – Serra do Xurés Nature Reserve and other honey commercialised by the cooperative as “Mel do Xurés” (north‐west Spain) was subjected to quantitative and qualitative melissopalynological analysis. The quantitative analysis found that ten samples belonged to Maurizio's Class III and one to Class IV. According to the qualitative analysis, four samples were classified as unifloral honey with Erica, four samples as multifloral honey with Erica pollen as the principal component and three samples as multifloral honey with Cytisus‐type pollen and Erica as the principal component pollen. The pollen spectra differ between the diverse honeys analysed, with a common denominator being Erica and Cytisus‐type pollen being abundant in all. For the rest of the samples, the pollen spectra were mainly the same, but with different relative percentages among secondary elements. Thus, either as a secondary or an important element, 91% of the honeys contained Quercus, 82% Castanea sativa Miller, 45% Rubus, 36% Cistus and 27% Lithodora prostrate (Loisel) Griseb,. In particular, we record for the first time the presence of Ribes and Ilex aquifolium L. pollen in Spanish honeys as an important minor or minor pollen component.     

Influence of slime production and adhesion of Candida sp. on biofilm formation

The increase of fungal infections in recent years is connected with the progress in medicine. The vast usage of biomaterials is an inseparable element of contemporary medicine but it also leads to development of infections. Yeast-like fungi Candida albicans are still the main pathogen of candidiasis. The ability to slime production and adhesion to polystyrene of Candida sp. on different surfaces can cause to form biofilm on surfaces of biomaterials used in production of catheters, drains and prosthesis. The aim of the study was to evaluate the influence of slime production and adhesion to polystyrene, of Candida sp. on biofilm formation on different biomaterials. 50 strains of Candida sp. were examined. They isolated from ill to Clinics of Anesthesiology and Intensive Therapy University Hospital No 1 of dr. A. Jurasza in Bydgoszcz. The ability to slime production was evaluated by Christensen method in modification Davenport and Branchini methods. The adhesion to polystyrene was evaluated by Richards et el method. The ability to produce biofilm biomaterials by the studied fungi was measured after 72 hours of incubation at 37 degrees C on different biomaterials. Yeast-like fungi Candida sp. fabricating slime and adhesion forming frequently biofilm on surface researched of biomaterials. Influence of chosen biological specificity ascertain on the ability to produce biofilm on surfaces of siliconized latex and polyvinylchloride.     

Adapt or die—Response of large herbivores to environmental changes in Europe during the Holocene

Climate warming and human landscape transformation during the Holocene resulted in environmental changes for wild animals. The last remnants of the European Pleistocene megafauna that survived into the Holocene were particularly vulnerable to changes in habitat. To track the response of habitat use and foraging of large herbivores to natural and anthropogenic changes in environmental conditions during the Holocene, we investigated carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotope composition in bone collagen of moose (Alces alces), European bison (Bison bonasus) and aurochs (Bos primigenius) in Central and Eastern Europe. We found strong variations in isotope compositions in the studied species throughout the Holocene and diverse responses to changing environmental conditions. All three species showed significant changes in their δ¹³C values reflecting a shift of foraging habitats from more open in the Early and pre‐Neolithic Holocene to more forest during the Neolithic and Late Holocene. This shift was strongest in European bison, suggesting higher plasticity, more limited in moose, and the least in aurochs. Significant increases of δ¹⁵N values in European bison and moose are evidence of a diet change towards more grazing, but may also reflect increased nitrogen in soils following deglaciation and global temperature increases. Among the factors explaining the observed isotope variations were time (age of samples), longitude and elevation in European bison, and time, longitude and forest cover in aurochs. None of the analysed factors explained isotope variations in moose. Our results demonstrate the strong influence of natural (forest expansion) and anthropogenic (deforestation and human pressure) changes on the foraging ecology of large herbivores, with forests playing a major role as a refugial habitat since the Neolithic, particularly for European bison and aurochs. We propose that high flexibility in foraging strategy was the key for survival of large herbivores in the changing environmental conditions of the Holocene.     

Synthetic biology and metabolic engineering of actinomycetes for natural product discovery

Actinomycetes are one of the most valuable sources of natural products with industrial and medicinal importance. After more than half a century of exploitation, it has become increasingly challenging to find novel natural products with useful properties as the same known compounds are often repeatedly re-discovered when using traditional approaches. Modern genome mining approaches have led to the discovery of new biosynthetic gene clusters, thus indicating that actinomycetes still harbor a huge unexploited potential to produce novel natural products. In recent years, innovative synthetic biology and metabolic engineering tools have greatly accelerated the discovery of new natural products and the engineering of actinomycetes. In the first part of this review, we outline the successful application of metabolic engineering to optimize natural product production, focusing on the use of multi-omics data, genome-scale metabolic models, rational approaches to balance precursor pools, and the engineering of regulatory genes and regulatory elements. In the second part, we summarize the recent advances of synthetic biology for actinomycetal metabolic engineering including cluster assembly, cloning and expression, CRISPR/Cas9 technologies, and chassis strain development for natural product overproduction and discovery. Finally, we describe new advances in reprogramming biosynthetic pathways through polyketide synthase and non-ribosomal peptide synthetase engineering. These new developments are expected to revitalize discovery and development of new natural products with medicinal and other industrial applications.     

Reproductive and competitive interactions among gametophytes of the allotetraploid fern Dryopteris corleyi and its two diploid parents

Background and Aims

Several models predict that the establishment of polyploids within diploid populations is enhanced by non-random mating (i.e. selfing and assortative mating) of cytotypes and by a higher relative fitness of polyploids. This report assesses the role that antheridiogens (i.e. maleness-inducing pheromones) and intercytotype differences in growth rate have on polyploid performance.

Methods

Three buckler-fern species were studied: the allotetraploid Dryopteris corleyi and its diploid parents, D. aemula and D. oreades. In one experiment, gametophytes of these species were cultured under rich growth conditions to compare the timing of gametangia production. The substrata on which these gametophytes had grown were used as antheridiogen sources in a second experiment. The three species were combined as source and target of antheridiogen (i.e. nine species pairs). Timing of antheridia production and gametophyte size were determined after those antheridiogen treatments.

Key Results

Under rich growth conditions the allotetraploid produced archegonia earlier than those of diploid parents. Female gametophytes of the three species produced antheridiogens that inhibited growth and favoured maleness both within and among species. Gametophyte size was similar in the three species but antheridia formed earlier in the allotetraploid.

Conclusions

Unisexuality, promoted by non-specific antheridiogens, enhances random mating both within and among species. The resulting hybridization can favour the reproductive exclusion of the allopolyploid in sites where it is outnumbered by diploids. However, the earlier production of gametangia in the allotetraploid favours assortative mating and may thus counterbalance reproductive exclusion.Key words: Allopolyploidy, antheridiogen, assortative mating, Dryopteris aemula, Dryopteris corleyi, Dryopteris oreades, gametophytes, gender expression, minority cytotype exclusion