Wall lizards combine chemical and visual cues of ambush snake predators to avoid overestimating risk inside refuges

The threat sensitivity hypothesis assumes that multiple cues from a predator should contribute in an additive way to determine the degree of risk-sensitive behaviour. The ability to use multiple cues in assessing the current level of predation risk should be especially important to prey exposed to multiple predators. Wall lizards, Podarcis muralis, respond to predatory attacks from birds or mammals by hiding inside rock crevices, where they may encounter another predator, the smooth snake, Coronella austriaca. We investigated in the laboratory whether chemical cues may be important to wall lizards for detection of snakes. The greater tongue-flick rate and shorter latency to first tongue-flick in response to predator scents indicated that lizards were able to detect the snakes' chemical cues. We also investigated the use of different predatory cues by lizards when detecting the presence of snakes within refuges. We simulated successive predator attacks and compared the propensity of lizards to enter the refuge and time spent within it for predator-free refuges, refuges containing either only visual or chemical cues of a snake, or a combination of these. The antipredatory response of lizards was greater when they were exposed to both visual and chemical cues than when only one cue was presented, supporting the threat sensitivity hypothesis. This ability may improve the accuracy of assessments of the current level of predation risk inside the refuge. It could be especially important in allowing lizards to cope with threats posed by two types of predators requiring conflicting prey defences.     

Boar spermatozoa encapsulated in barium alginate membranes: a microdensitometric evaluation of some enzymatic activities during storage at 18 degrees C

The customary dilution of boar semen for subsequent artificial insemination (AI) procedures damages the cell membrane of spermatozoa, resulting in a loss of enzymes and other cytoplasmic contents and acrosomal reactions. We encapsulated non-diluted boar semen in barium alginate membranes to optimize AI procedures and to improve the functional integrity of spermatozoal membranes during storage. The percentage of non-reacted acrosomes (NRA) and measurements of enzyme leakage (cytochrome c oxidase (COX), lactate dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase (G6PDH)) were used as indices of the functional status of diluted, unencapsulated and encapsulated spermatozoa, stored for 72 h at 18 degrees C. Enzymatic activity was assessed in situ by microdensitometry, and non-reacted acrosomes were microscopically determined by staining. The percentage of acrosome integrity and the intracellular enzymatic activities during storage were different for unencapsulated and encapsulated semen. Semen dilution caused a rapid decline in enzymatic activities and concomitant acrosomal reactions. Encapsulated spermatozoa had significantly higher acrosome integrity (77% versus 55%; P < 0.01 after 72 h) and an overall higher in situ enzymatic activity. For cytochrome c oxidase and lactate dehydrogenase the greatest differences between encapsulated and unencapsulated spermatozoa were present after 72 h whereas for glucose-6-phosphate dehydrogenase significant differences were found within 24h of storage. The encapsulation process maintains a better preservation environment for boar spermatozoa and could be a promising, innovative technique to improve storage of these cells.     

Cleavage of syndecan-4 by ADAMTS1 provokes defects in adhesion

Syndecan-4 is a membrane-bound heparan sulfate proteoglycan that participates in cell-cell and cell-matrix interactions and modulates adhesion and migration of many cell types. Through its extracellular domain, syndecan-4 cooperates with adhesion molecules and binds matrix components relevant for cell migration. Importantly, syndecan-4 is a substrate of extracellular proteases, however the biological significance of this cleavage has not been elucidated. Here, we show that the secreted metalloprotease ADAMTS1, involved in angiogenesis and inflammatory processes, cleaves the ectodomain of syndecan-4. We further showed that this cleavage results in altered distribution of cytoskeleton components, functional loss of adhesion, and gain of migratory capacities. Using syndecan-4 null cells, we observed that ADAMTS1 proteolytic action mimics the outcome of genetic deletion of this proteoglycan with regards to focal adhesion. Our findings suggest that the shedding of syndecan-4 by ADAMTS1 disrupts cell adhesion and promotes cell migration.     

Comparison of the metabolic activities of four wild-type <Emphasis Type="Italic">Clostridium perfringens</Emphasis> strains with their gatifloxacin-selected resistant mutants

The production of short-chain fatty acids, reductive enzymes, and hydrolytic enzymes by four gatifloxacin-selected, fluoroquinolone-resistant, mutant strains of C. perfringens, with stable mutations either in DNA gyrase or in both DNA gyrase and topoisomerase IV, was compared with that produced by the wild-type parent strains to investigate the effect of mutations associated with the selection of gatifloxacin resistance on bacterial metabolic activities. The mutants differed from their respective wild-type parent strains in the enzymatic activities of azoreductase, nitroreductase, and β-glucosidase and in the ratio of butyric acid to acetic acid production. Microarray analysis of one wild type and the corresponding mutant revealed different levels of mRNA expression for the enzymes involved in short-chain fatty acid (SCFA) synthesis and for β-glucosidase and oxidoreductases. In addition to mutations in the target genes, selection of resistance to gatifloxacin resulted in strain-specific physiological changes in the resistant mutants of C. perfringens that affected their metabolic activities.     

Culturable Microbial Diversity and the Impact of Tourism in Kartchner Caverns,Arizona

Kartchner Caverns in Benson, AZ, was opened for tourism in 1999 after a careful development protocol that was designed to maintain predevelopment conditions. As a part of an ongoing effort to determine the impact of humans on this limestone cave, samples were collected from cave rock surfaces along the cave trail traveled daily by tour groups (200,000 visitors year^–1) and compared to samples taken from areas designated as having medium (30–40 visitors year^–1) and low (2–3 visitors year^–1) levels of human exposure. Samples were also taken from fiberglass moldings installed during cave development. Culturable bacteria were recovered from these samples and 90 unique isolates were identified by using 16S rRNA polymerase chain reaction and sequencing. Diversity generally decreased as human impact increased leading to the isolation of 32, 27, and 22 strains from the low, medium, and high impact areas, respectively. The degree of human impact was also reflected in the phylogeny of the isolates recovered. Although most isolates fell into one of three phyla: Actinobacteria, Firmicutes, or Proteobacteria, the Proteobacteria were most abundant along the cave trail (77% of the isolates), while Firmicutes predominated in the low (66%) and medium (52%) impact areas. Although the abundance of Proteobacteria along the cave trail seems to include microbes of environmental rather than of anthropogenic origin, it is likely that their presence is a consequence of increased organic matter availability due to lint and other organics brought in by cave visitors. Monitoring of the cave is still in progress to determine whether these bacterial community changes may impact the future development of cave formations.     

Oral Candida colonization in patients with chronic periodontitis. Is there any relationship?

Background

Candida can be implicated in the pathology of chronic periodontitis.

Effects of climate change and horticultural use on the spread of naturalized alien garden plants in Europe

Climate warming is supposed to enlarge the area climatically suitable to the naturalization of alien garden plants in temperate regions. However, the effects of a changing climate on the spread of naturalized ornamentals have not been evaluated by spatially and temporarily explicit range modelling at larger scales so far. Here, we assess how climate change and the frequency of cultivation interactively determine the spread of 15 ornamental plants over the 21st century in Europe. We coupled species distribution modelling with simulations of demography and dispersal to predict range dynamics of these species in annual steps across a 250 × 250 m raster of the study area. Models were run under four scenarios of climate warming and six levels of cultivation intensity. Cultivation frequency was implemented as size of the area used for planting a species. Although the area climatically suitable to the 15 species increases, on average, the area predicted to be occupied by them in 2090 shrinks under two of the three climate change scenarios. This contradiction obviously arises from dispersal limitations that were pronounced although we assumed that cultivation is spatially adapting to the changing climate. Cultivation frequency had a much stronger effect on species spread than climate change, and this effect was non‐linear. The area occupied increased sharply from low to moderate levels of cultivation intensity, but levelled off afterwards. Our simulations suggest that climate warming will not necessarily foster the spread of alien garden plants in Europe over the next decades. However, climatically suitable areas do increase and hence an invasion debt is likely accumulating. Restricting cultivation of species can be effective in preventing species spread, irrespective of how the climate develops. However, for being successful, they depend on high levels of compliance to keep propagule pressure at a low level.     

Rescue of Fructose-Induced Metabolic Syndrome by Antibiotics or Faecal Transplantation in a Rat Model of Obesity

A fructose-rich diet can induce metabolic syndrome, a combination of health disorders that increases the risk of diabetes and cardiovascular diseases. Diet is also known to alter the microbial composition of the gut, although it is not clear whether such alteration contributes to the development of metabolic syndrome. The aim of this work was to assess the possible link between the gut microbiota and the development of diet-induced metabolic syndrome in a rat model of obesity. Rats were fed either a standard or high-fructose diet. Groups of fructose-fed rats were treated with either antibiotics or faecal samples from control rats by oral gavage. Body composition, plasma metabolic parameters and markers of tissue oxidative stress were measured in all groups. A 16S DNA-sequencing approach was used to evaluate the bacterial composition of the gut of animals under different diets. The fructose-rich diet induced markers of metabolic syndrome, inflammation and oxidative stress, that were all significantly reduced when the animals were treated with antibiotic or faecal samples. The number of members of two bacterial genera, Coprococcus and Ruminococcus, was increased by the fructose-rich diet and reduced by both antibiotic and faecal treatments, pointing to a correlation between their abundance and the development of the metabolic syndrome. Our data indicate that in rats fed a fructose-rich diet the development of metabolic syndrome is directly correlated with variations of the gut content of specific bacterial taxa.