Behavioural Type Affects Space Use in a Wild Population of Crows (Corvus corone)

While personality‐dependent dispersal is well studied, local space use has received surprisingly little attention in this context, despite the multiple consequences on survival and fitness. Regarding the coping style of individuals, recent studies on personality‐dependent space use within a habitat indicate that ‘proactive’ individuals are wider ranging than ‘reactive’ ones. However, such studies are still scarce and cover limited taxonomic diversity, and thus, more research is needed to explore whether this pattern generalises across species. We examined the link between coping style and space use in a population of crows (Corvus corone) freely inhabiting the urban zoo of Vienna, Austria. We used a binary docility rating (struggle during handling vs. no struggle) and a tonic immobility test to quantify individual coping style. Individual space use was quantified as the number of different sites at which each crow was observed, and we controlled for different number of sightings per individual by creating a space use index. Only the binary docility rating showed repeatability over time, and significantly predicted space use. In contrast to previous studies, we found that reactive crows (no struggle during handling) showed wider ranging space use within the study site than proactive individuals (who struggled during handling). The discrepancy from previous results suggests that the relationship between behavioural type and space use may vary between species, potentially reflecting differences in socioecology.     

Algal Remodeling in a Ubiquitous Planktonic Photosymbiosis

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Influence of oligosaccharides on the viability and membrane properties of Lactobacillus reuteri TMW1.106 during freeze-drying

Freeze-drying is a process commonly used in starter culture preparation. To improve the survival rate of bacteria during the process, cryoprotectives are usually added before freezing. This study investigated the influence of the addition of sucrose, fructo-oligosaccharides (FOS), inulin and skim milk on the viability and membrane integrity of Lactobacillus reuteri TMW1.106 during freezing, freeze-drying and storage. The effect of drying adjuncts on survival was correlated to their interaction with bacterial membrane by determination of the parameters membrane fluidity and membrane lateral pressure. Sucrose, FOS and skim milk significantly enhanced survival of exponential-phase cells of L. reuteri during freeze-drying. Cellular viability during storage of exponential-phase cells remained highest for cells dried in the presence of skim milk and inulin. Membranes of these cells were completely permeabilized after freeze-drying. The application of FOS significantly improved survival of stationary phase cells of L. reuteri TMW1.106 after freeze-drying and storage. This increased viability of L. reuteri TMW1.106 in the presence of FOS correlated to improved membrane integrity. Fructo-oligosaccharides and fructans, but not gluco-oligosaccharides interacted with membrane vesicles prepared from L. reuteri TMW1.106 as indicated by increased membrane lateral pressure in the presence of FOS and fructans. Increased membrane integrity of stationary phase L. reuteri TMW1.106 was attributed to direct interactions between FOS and the membrane which leads to increased membrane fluidity and thus improved stability of the membrane during and rehydration.     

Cdc37p is involved in osmoadaptation and controls high osmolarity-induced cross-talk via the MAP kinase Kss1p

Cdc37p, the p50 homolog of Saccharomyces cerevisiae, is an Hsp90 cochaperone involved in the targeting of protein kinases to Hsp90. Here we report a role for Cdc37p in osmoadaptive signalling in this yeast. The osmosensitive phenotype that is displayed by the cdc37-34 mutant strain appears not to be the consequence of deficient signalling through the high osmolarity glycerol (HOG) MAP kinase pathway. Rather, Cdc37p appears to play a role in the filamentous growth (FG) pathway, which mediates adaptation to high osmolarity parallel to the HOG pathway. The osmosensitive phenotype of the cdc37-34 mutant strain is aggravated upon the deletion of the HOG gene. We report that the hyper-osmosensitive phenotype of the cdc37-34, hog1 mutant correlates to a reduced of activity of the FG pathway. We utilized this phenotype to isolate suppressor genes such as KSS1 that encodes a MAP kinase that functions in the FG pathway. We report that Kss1p interacts physically with Cdc37p. Like Kss1p, the second suppressor that we isolated, Dse1p, is involved in cell wall biogenesis or maintenance, suggesting that Cdc37p controls osmoadapation by regulating mitogen-activated protein kinase signalling aimed at adaptive changes in cell wall organization.     

Prediction of quaternary structure by analysis of hot spot residues in protein-protein interfaces: the case of anthranilate phosphoribosyltransferases

It is an important goal of computational biology to correctly predict the association state of a protein based on its amino acid sequence and the structures of known homologues. We have pursued this goal on the example of anthranilate phosphoribosyltransferase (AnPRT), an enzyme that is involved in the biosynthesis of the amino acid tryptophan. Firstly, known crystal structures of naturally occurring homodimeric AnPRTs were analyzed using the Protein Interfaces, Surfaces, and Assemblies (PISA) service of the European Bioinformatics Institute (EBI). This led to the identification of two hydrophobic “hot spot” amino acids in the protein-protein interface that were predicted to be essential for self-association. Next, in a comprehensive multiple sequence alignment (MSA), naturally occurring AnPRT variants with hydrophilic or charged amino acids in place of hydrophobic residues in the two hot spot positions were identified. Representative variants were characterized in terms of thermal stability, enzymatic activity, and quaternary structure. We found that AnPRT variants with charged residues in both hot spot positions exist exclusively as monomers in solution. Variants with hydrophilic amino acids in one hot spot position occur in both forms, monomer and dimer. The results of the present study provide a detailed characterization of the determinants of the AnPRT monomer-dimer equilibrium and show that analysis of hot spots in combination with MSAs can be a valuable tool in prediction of protein quaternary structures.     

A framework to evaluate whether to pool or separate behaviors in a multilayer network

A multilayer network approach combines different network layers,which are connected by interlayer edges,to create a single mathematical object.These networks can contain a variety of information types and represent different aspects of a system.However,the process for selecting which information to include is not always straightforward.Using data on 2 agonistic behaviors in a captive population of monk parakeets(Myiopsitta monachus),we developed a framework for investigating how pooling or splitting behaviors at the scale of dyadic relationships(between 2 individuals)affects individual-and group-level social properties.We designed 2 reference models to test whether randomizing the number of interactions across behavior types results in similar structural patterns as the observed data.Although the behaviors were correlated,the first reference model suggests that the 2 behaviors convey different information about some social properties and should therefore not be pooled.However,once we controlled for data sparsity,we found that the observed measures corresponded with those from the second reference model.Hence,our initial result may have been due to the unequal frequencies of each behavior.Overall,our findings support pooling the 2 behaviors.Awareness of how selected measurements can be affected by data properties is warranted,but nonetheless our framework disentangles these efforts and as a result can be used for myriad types of behaviors and questions.This framework will help researchers make informed and data-driven decisions about which behaviors to pool or separate,prior to using the data in subsequent multilayer network analyses.     

Monitoring the colonization of sugarcane and rice plants by the endophytic diazotrophic bacterium Gluconacetobacter diazotrophicus marked with gfp and gusA reporter genes

Aims: To evaluate the colonization process of sugarcane plantlets and hydroponically grown rice seedlings by Gluconacetobacter diazotrophicus strain PAL5 marked with the gusA and gfp reporter genes. Methods and Results: Sugarcane plantlets inoculated in vitro with PAL5 carrying the gfp::gusA plasmid pHRGFPGUS did not present green fluorescence, but β‐glucuronidase (GUS)‐stained bacteria could be observed inside sugarcane roots. To complement this existing inoculation methodology for micropropagated sugarcane with a more rapid colonization assay, we employed hydroponically grown gnotobiotic rice seedlings to study PAL5–plant interaction. PAL5 could be isolated from the root surface (10⁸ CFU g^?1) and from surface‐disinfected root and stem tissues (10⁴ CFU g^?1) of inoculated plants, suggesting that PAL5 colonized the internal plant tissues. Light microscopy confirmed the presence of bacteria inside the root tissue. After inoculation of rice plantlets with PAL5 marked with the gfp plasmid pHRGFPTC, bright green fluorescent bacteria could be seen colonizing the rice root surface, mainly at the sites of lateral root emergence, at root caps and on root hairs. Conclusion: The plasmids pHRGFPGUS and pHRGFPTC are valid tools to mark PAL5 and monitor the colonization of micropropagated sugarcane and hydroponic rice seedlings. Significance and Impact of the Study: These tools are of use to: (i) study PAL5 mutants affected in bacteria–plant interactions, (ii) monitor plant colonization in real time and (iii) distinguish PAL5 from other bacteria during the study of mixed inoculants.     

Co‐localized Crassostrea virginica and Crassostrea ariakensis Oysters differ in bioaccumulation,retention and depuration of microbial indicators and human enteropathogens

Aims: To evaluate the bioaccumulation, retention and depuration rates of nine pathogens and surrogates when two oyster species were co‐localized in tanks of seawater. Methods and Results: Crassostrea ariakensis (n = 52) and Crassostrea virginica (n = 52) were exposed to five virus types, two protozoan and two microsporidian species for 24 h. Oysters were then placed in depuration tanks, and subsets were removed and analysed for micro‐organisms at weekly intervals. The odds of C. ariakensis oysters harbouring mouse norovirus‐1 (MNV‐1), human norovirus (NoV) or haepatitis A virus (HAV) were significantly greater than the odds of C. virginica oysters harbouring the same viruses (MNV‐1 OR = 5·05, P = 0·03; NoV OR = 6·97, P = 0·01; HAV OR = 7·40, P < 0·001). Additionally, compared to C. virginica, C. ariakensis retained significantly higher numbers of transmissive stages of all protozoan and microsporidian species (P < 0·01). Crassostrea ariakensis oysters are also capable of retaining multiple human pathogens for at least 1 month. Conclusions: Crassostrea ariakensis oysters were statistically more likely to harbour enteropathogens and microbial indicators, compared to C. virginica. Individual C. ariakensis were also statistically more likely to retain multiple viruses, protozoa and microsporidia than C. virginica, highlighting the role the species may play in the transmission of multiple diseases. Significance and Impact of the Study: Nonnative Crassostrea ariakensis oysters are under review for their introduction into the Chesapeake Bay. The results of this study suggest that nonnative C. ariakensis oysters may present a serious public health threat to people consuming the oysters raw from contaminated sites.