Stenotrophomonas maltophilia as a part of normal oral bacterial flora in captive snakes and its susceptibility to antibiotics

Only little is known about normal oral bacterial flora in captive snakes containing Stenotrophomonas maltophilia. This microbe has been reported as a causative agent of numerous infections in reptiles. Therefore, the goal of the study was to detect its presence in the mouths of a significant number of healthy captive snakes and determining its susceptibility to antibiotics at 30 and 37 degrees C. The isolates were obtained in 1999-2005 from mouth swabs of 115 snakes of 12 genera and 22 species-most often Elaphe guttata (24 individuals; 20.9%). Susceptibility to 24 antibiotics was tested by the microdilution method. The microbe was demonstrated in 34 (29.6%) individuals. Overall, 47 strains of S. maltophilia were acquired. Evaluation using PFGE profiles and antibiograms resulted in confirmation of one strain of S. maltophilia in 23 (20.0%) individuals, two strains in nine (7.8%) and three in two (1.8%) snakes. All tested antibiotics were more effective at 37 degrees C, with the partial exception of cotrimoxazole and cefoperazone/sulbactam. At a temperature of 37 degrees C, the lowest frequency of resistance to levofloxacin (no resistant strains), cotrimoxazole and ofloxacin (97.9% of susceptible strains) was recorded. At 30 degrees C, the most active agents were cotrimoxazole (97.9% of susceptible strains), levofloxacin (91.5%) and ofloxacin (85.1%). In conclusion, S. maltophilia is present in the mouths of about one third of healthy captive snakes, showing good susceptibility to cotrimoxazole, some fluoroquinolones and aminoglycosides. The antibiotics (particularly aminoglycosides) are more effective at 37 degrees C.     

Above parr: Lowland river habitat characteristics associated with higher juvenile Atlantic salmon (Salmo salar) and brown trout (S. trutta) densities

Understanding juvenile salmonid habitat requirements is critical for their effective management, but little is known about these requirements in lowland rivers, which include important but unique salmonid habitats. We compared the relative influence of in-stream Ranunculus cover, water depth, prey abundance, distance upstream and two previously unexplored factors (water velocity heterogeneity and site colonisation potential) on summer densities of juvenile Atlantic salmon and brown trout. We applied electrofishing, habitat surveys and macroinvertebrate kick sampling, and calculated the site colonisation potential from salmon redd surveys across 18–22 sites in a lowland river in 2015–2017. Due to a recruitment crash in 2016, models including and excluding this unusual year were explored. Excluding 2016 data, juvenile salmon densities showed a positive association with Ranunculus cover and numbers of nearby upstream redds, and a negative association with distance upstream from the tidal limit. Trout densities were positively associated with velocity heterogeneity, indicating a potential indirect influence of Ranunculus mediated by water velocity. When including 2016, year had the largest effect on densities of both species, highlighting the impact of the recruitment failure. These findings uncover interspecific differences in the habitat requirements of juvenile salmonids in lowland rivers. Velocity heterogeneity and site colonisation potential had high explanatory power, highlighting that they should be considered in future studies of habitat use. These findings demonstrate that temporal replication and recruitment dynamics are important considerations when exploring species–habitat associations. We discuss potential management implications and argue that Ranunculus cover could be an important management tool in conservation of lowland salmonids.     

The systemic effects of juvenoids on the red firebug Pyrrhocoris apterus and on the pea aphid Acyrthosiphon pisum with data on life table response

BACKGROUND: A series of juvenoid alcohols and their glycosidic derivatives (juvenogens), synthesized at the Institute of Organic Chemistry and Biochemistry in Prague, commercially used juvenoids and the natural derivatives of juvabione were evaluated for their systemic juvenilizing effect on the red firebug, Pyrrhocoris apterus L., and on the pea aphid, Acyrthosiphon pisum Harris. A life table response experiment was designed, and demographic characteristics were computed for a cohort of A. pisum following chronic exposure to a range of concentrations of the selected trans-isomer of carbamate juvenoid 8 applied via the broad bean (Vicia faba L.) root system. RESULTS: Using the ratio of topical and per os activities, promising effects were found in two alkyl beta-D-glucopyranosides (3 and 9) and the trans-isomer of carbamate juvenoid 8 in tests on P. apterus. In A. pisum, the highest systemic activity was found in tests with the trans-isomer of carbamate juvenoid 8. The longevity, the number of offspring per female and the number of offspring per reproducing female significantly decreased with concentrations of 0.05 mg mL(-1) and higher. While the net reproductive rate R(0) and the intrinsic rate of natural increase r(m) displayed similar trends, the generation time G varied slightly between 11.6 and 12.8 days. CONCLUSION: Expected systemic activity of glycosidic juvenogens in P. apterus was not confirmed by exposure of the pea aphid on broad bean treated with aqueous solutions of the compounds. Nevertheless, the carbamate juvenoid alcohol 8 displayed a considerable juvenilizing effect on A. pisum in screening tests. Furthermore, this compound indicated a sublethal effect as the realized fecundity U(x) decreased disproportionately to the age-specific survival L(x) with increased concentration. The population parameters are compared with the data in similar demographic studies and are discussed together with the possibilities of using the compounds of this structural type in practice.     

The biological and chemical variability of yacon

This paper focuses on the biological and chemical variability of four yacon (Smallanthus sonchifolius) accessions cultivated under field conditions. Significant variations in tuber shape, weight, content of oligofructans, as well as in leaf isozymes, phenolics, and relative DNA contents were found. Accessions 6 and 88 were the most productive (up to 3.01 and 3.74 kg/plant); accession 48 was the most balanced from the yield aspect in three vegetative periods. A significantly higher content of beta-(2-->1) oligofructans was noted in accessions 48 and 88 as compared to 6 and 60. No difference in sucrose, glucose, and fructose level was observed. Only accession 6 exhibited separate acid phosphatase and esterase isoforms. Accessions 6 and 60 had the highest content of phenolics, and accession 88 had the lowest relative DNA content. Large yacon intraspecific variation may be useful in future detailed research as a good background for breeding, growing, and utilization in industrial processing.     

Determination of total content of phenolic compounds and their antioxidant activity in vegetables--evaluation of spectrophotometric methods

This research studies in detail the contents of phenolic compounds determined by the Folin-Ciocalteu reagent and the antioxidant activities determined by the TEAC (Trolox equivalent antioxidant capacity), DPPH (using diphenyl-p-picrylhydrazyl radical), and FRAP (ferric reducing antioxidant power) methods, and their correlations for used standards with these methods (catechine, gallic acid, caffeic acid, ferulic acid, Trolox, ascorbic acid, and ferrous sulfate) and extracts from several species of commonly consumed vegetables were studied in detail. The comparison of absolute values of absorption coefficients for used standards and for individual methods allows one to choose optimal common standards for methods to be compared. The procedures applied for the same sets of the extracts using identical calibration procedures and common standards allowed better comparison of the results obtained by the TEAC, DPPH, and FRAP methods. The values of content of phenolic substances and total antioxidant activity of the sets of samples correlate very well for all used methods. The very high values of antioxidant activity were found in intensely colored vegetables (red cabbage, red onion, etc.), and the values were very low in watery vegetables such as potato, marrow, and cucumber.     

Evolution of the molecular machines for protein import into mitochondria

In creating mitochondria some 2 billion years ago, the first eukaryotes needed to establish protein import machinery in the membranes of what was a bacterial endosymbiont. Some of the preexisting protein translocation apparatus of the endosymbiont appears to have been commandeered, including molecular chaperones, the signal peptidase, and some components of the protein-targeting machinery. However, the protein translocases that drive protein import into mitochondria have no obvious counterparts in bacteria, making it likely that these machines were created de novo. The presence of similar translocase subunits in all eukaryotic genomes sequenced to date suggests that all eukaryotes can be considered descendants of a single ancestor species that carried an ancestral "protomitochondria."     

PIN proteins perform a rate-limiting function in cellular auxin efflux

Intercellular flow of the phytohormone auxin underpins multiple developmental processes in plants. Plant-specific pin-formed (PIN) proteins and several phosphoglycoprotein (PGP) transporters are crucial factors in auxin transport-related development, yet the molecular function of PINs remains unknown. Here, we show that PINs mediate auxin efflux from mammalian and yeast cells without needing additional plant-specific factors. Conditional gain-of-function alleles and quantitative measurements of auxin accumulation in Arabidopsis and tobacco cultured cells revealed that the action of PINs in auxin efflux is distinct from PGP, rate-limiting, specific to auxins, and sensitive to auxin transport inhibitors. This suggests a direct involvement of PINs in catalyzing cellular auxin efflux.     

The colonization of decaying logs by vascular plants and the consequences of fallen logs for herb layer diversity in a lowland alluvial forest

The presence of coarse woody debris in forests is an important naturalness criterion as well as a biodiversity indicator. Decaying logs provide habitat for many organisms including vascular plants. The aims of this study are to describe the colonization of decaying logs by vascular plants in a lowland alluvial forest and to assess the impact of fallen logs on the biodiversity of the herb layer. We investigated 493 logs in the Ranšpurk National Nature Reserve in southern Moravia. For each log, we recorded species of vascular plants rooting on its surface. Decaying logs were characterized by their dimensions, woody species and decay class. Vascular plants rooted on 279 surveyed logs. Decaying logs were colonized by 79 species of vascular plants. Terrain relief was found to be a significant factor for colonizing species. Our study did not find any significant spatial pattern of colonized logs with regard to the distribution of vascular plants, intensity of colonization or the ecological demands of colonizers. The colonization of lying logs by vascular plants was significantly influenced by the species of logs, their surface area and decay class. Species composition of vascular plants on decaying logs and that on mineral soil were significantly different. Demonstrably higher frequencies of Dryopteris carthusiana and Impatiens parviflora were found on decaying logs. The presence of decaying logs and the microsites they create is important for total forest biodiversity including the diversity of vascular plants. We recommend increasing the proportion of decaying logs even in commercial forests.

     

Pineal vasotocin: release into cat cerebrospinal fluid by melanocyte-stimulating hormone release-inhibiting factor

The intracarotid injection of both synthetic melanocyte-stimulating hormone release-inhibiting factor (MIF) and purified MIF prepared from bovine hypothalami induces arginine vasotocin release into cerebrospinal fluid of cats and significantly decreases the pineal arginine vasotocin content at 5 minutes after the injection. The present results demonstrate an extrapituitary endocrine effect of synthetic and purified bovine MIF.     

Selective inhibition of a regulatory subunit of protein phosphatase 1 restores proteostasis

Many biological processes are regulated through the selective dephosphorylation of proteins. Protein serine-threonine phosphatases are assembled from catalytic subunits bound to diverse regulatory subunits that provide substrate specificity and subcellular localization. We describe a small molecule, guanabenz, that bound to a regulatory subunit of protein phosphatase 1, PPP1R15A/GADD34, selectively disrupting the stress-induced dephosphorylation of the α subunit of translation initiation factor 2 (eIF2α). Without affecting the related PPP1R15B-phosphatase complex and constitutive protein synthesis, guanabenz prolonged eIF2α phosphorylation in human stressed cells, adjusting the protein production rates to levels manageable by available chaperones. This favored protein folding and thereby rescued cells from protein misfolding stress. Thus, regulatory subunits of phosphatases are drug targets, a property used here to restore proteostasis in stressed cells.