Imaging motor imagery: methodological issues related to expertise

Mental imagery (MI) is the mental rehearsal of movements without overt execution. Brain imaging techniques have made it possible to identify the brain regions that are activated during MI and, for voluntary motor tasks involving hand and finger movements, to make direct comparison with those areas activated during actual movement. However, the fact that brain activation differs for different types of imagery (visual or kinetic) and depends on the skill level of the individual (e.g., novice or elite athlete) raises a number of important methodological issues for the design of brain imaging protocols to study MI. These include instructing the subject concerning the type of imagery to use, objective measurement of skill level, the design of motor tasks sufficiently difficult to produce a range of skill levels, the effect of different environments on skill level (including the imaging device), and so on. It is suggested that MI is more about the neurobiology of the development of motor skills that have already been learned, but not perfected, than it is about learning motor skills de novo.     

Owl dusk chorus is related to the quality of individuals and nest‐sites

Dawn and dusk choruses represent one of the most investigated topics in avian vocal behaviour, but their underlying basis remains unclear. As with the dawn chorus in passerines, dusk chorus in owls seems to support the mate and rival assessment hypothesis and happens during the most constraining period, as individuals have not yet fed and, under the handicap principle, dusk chorus is likely to reveal inter‐individual differences in competitive ability, body condition and/or habitat quality. Here, a study of vocal displays at dusk of 14 Eurasian Eagle Owls Bubo bubo revealed a temporal succession in the order in which males began their vocalizations. The vocalization order appeared to be related to both the quality of the nesting territory (based upon mean number of fledged young and proportion of rats in the diet) and the male's individual quality, as revealed by haematocrit values and the brightness of the white throat patch.     

Hybridization between closely related songbirds is related to human habitat disturbance

Human habitat disturbances can promote hybridization between closely related, but typically reproductively isolated, species. We explored whether human habitat disturbances are related to hybridization between two closely related songbirds, black-capped and mountain chickadees, using both genomic and citizen science data sets. First, we genotyped 409 individuals from across both species' ranges using reduced-representation genome sequencing and compared measures of genetic admixture to a composite measure of human landscape disturbance. Then, using eBird observations, we compared human landscape disturbance values for sites where phenotypically diagnosed hybrids were observed to locations where either parental species was observed to determine whether hybrid chickadees are reported in more disturbed areas. We found that hybridization between black-capped and mountain chickadees positively correlates with human habitat disturbances. From genomic data, we found that (1) hybrid index (HI) significantly increased with habitat disturbance, (2) more hybrids were sampled in disturbed habitats, (3) mean HIs were higher in disturbed habitats versus wild habitats, and (4) hybrids were detected in habitats with significantly higher disturbance values than parentals. Using eBird data, we found that both hybrid and black-capped chickadees were significantly more disturbance-associated than mountain chickadees. Surprisingly, we found that nearly every black-capped chickadee we sampled contained some proportion of hybrid ancestry, while we detected very few mountain chickadee backcrosses. Our results highlight that hybridization between black-capped and mountain chickadees is widespread, but initial hybridization is rare (few F1s were detected). We conclude that human habitat disturbances can erode pre-zygotic reproductive barriers between chickadees and that post-zygotic isolation is incomplete. Understanding what becomes of recently hybridizing species following large-scale habitat disturbances is a new, but pressing, consideration for successfully preserving genetic biodiversity in a rapidly changing world.     

Regulation of the HPA axis is related to song complexity and measures of phenotypic quality in song sparrows

Regulation of the hypothalamic-pituitary-adrenal (HPA) axis is a key component of the vertebrate stress response. Prior studies have found that variation in HPA responses were correlated to measures of fitness and physiological condition. In addition, sexually-selected traits have also been found to correlate to measures of condition. The proximate mechanisms responsible for such covariation between sexually selected traits and measures of quality are unclear, but could involve variation in HPA regulation. We investigated whether HPA activity is related to song complexity, body size/condition and leukocyte profiles in wild male song sparrows (Melospiza melodia). We characterized three aspects of HPA activity: 1) response to restraint stress; 2) negative feedback, assessed by the ability of exogenous dexamethasone to suppress corticosterone levels; and 3) adrenal sensitivity to exogenous adrenocorticotropic hormone (ACTH). Birds with lower responses to restraint stress had more complex song and more heterophils and higher heterophil to lymphocyte (H:L) ratios. Birds with more effective negative feedback were larger and had fewer heterophils and lower H:L ratios, suggesting lower levels of physiological stress or infection. We observed no relationship between adrenal sensitivity to exogenous ACTH and any of the factors. These findings illustrate important relationships between HPA activity, song complexity, and morphological and physiological traits. Song complexity may thus provide receivers with information about the ability of the singer to cope with stressors.     

Indirect comparisons: a review of reporting and methodological quality

Background

The indirect comparison of two interventions can be valuable in many situations. However, the quality of an indirect comparison will depend on several factors including the chosen methodology and validity of underlying assumptions. Published indirect comparisons are increasingly more common in the medical literature, but as yet, there are no published recommendations of how they should be reported. Our aim is to systematically review the quality of published indirect comparisons to add to existing empirical data suggesting that improvements can be made when reporting and applying indirect comparisons.

Methodology/Findings

Reviews applying statistical methods to indirectly compare the clinical effectiveness of two interventions using randomised controlled trials were eligible. We searched (1966–2008) Database of Abstracts and Reviews of Effects, The Cochrane library, and Medline. Full review publications were assessed for eligibility. Specific criteria to assess quality were developed and applied. Forty-three reviews were included. Adequate methodology was used to calculate the indirect comparison in 41 reviews. Nineteen reviews assessed the similarity assumption using sensitivity analysis, subgroup analysis, or meta-regression. Eleven reviews compared trial-level characteristics. Twenty-four reviews assessed statistical homogeneity. Twelve reviews investigated causes of heterogeneity. Seventeen reviews included direct and indirect evidence for the same comparison; six reviews assessed consistency. One review combined both evidence types. Twenty-five reviews urged caution in interpretation of results, and 24 reviews indicated when results were from indirect evidence by stating this term with the result.

Conclusions

This review shows that the underlying assumptions are not routinely explored or reported when undertaking indirect comparisons. We recommend, therefore, that the quality of indirect comparisons should be improved, in particular, by assessing assumptions and reporting the assessment methods applied. We propose that the quality criteria applied in this article may provide a basis to help review authors carry out indirect comparisons and to aid appropriate interpretation.     

Pollen hemagglutinating activity is not related to lectin

We purified a hemagglutinating substance from pollen extracts to electrophoretic homogeneity. The hemagglutinating activity of this substance was inhibited by positively charged substances but not by the monosaccharides known as inhibitors of the lectin activity. The hemagglutinating substance appeared to be negatively charged in the pH conditions of the hemagglutinating assay, suggesting that hemagglutination was due to an electrostatic interaction with positively charged components of the erythrocytes. Preliminary chemical analysis suggests that the hemagglutinating substance is a proteoglycan.     

Willingness to share research data is related to the strength of the evidence and the quality of reporting of statistical results

Background

The widespread reluctance to share published research data is often hypothesized to be due to the authors'' fear that reanalysis may expose errors in their work or may produce conclusions that contradict their own. However, these hypotheses have not previously been studied systematically.

Methods and Findings

We related the reluctance to share research data for reanalysis to 1148 statistically significant results reported in 49 papers published in two major psychology journals. We found the reluctance to share data to be associated with weaker evidence (against the null hypothesis of no effect) and a higher prevalence of apparent errors in the reporting of statistical results. The unwillingness to share data was particularly clear when reporting errors had a bearing on statistical significance.

Conclusions

Our findings on the basis of psychological papers suggest that statistical results are particularly hard to verify when reanalysis is more likely to lead to contrasting conclusions. This highlights the importance of establishing mandatory data archiving policies.     

Decreased expression of heat shock protein A4L in spermatozoa is positively related to poor human sperm quality

Heat shock protein A4L (HSPA4L), which is highly expressed in the testis, is correlated with male fertility. However, the relationship between HSPA4L expression and sperm quality remains unknown. In the present study, a systematic characterization of HSPA4L expression on spermatozoa was performed. HSPA4L is highly expressed in the human testis, characterized by abundant localization in testicular spermatocytes and round spermatids. Compared with the testis from young adults (aged 27–36 years old), downregulated expression of HSPA4L in the testis from elderly adults (aged 78–82 years old) was observed. Immunofluorescence quantification demonstrated the localization of HSPA4L in the middle piece of sperm. Compared with mature spermatozoa, a similar lower intensity and localization percentage of HSPA4L in immature and asthenozoospermic spermatozoa were observed, and the consistently decreased expression of HSPA4L in immature and asthenozoospermic spermatozoa was validated by western blot analysis. Functional analysis revealed a correlation between HSPA4L and sperm motility by Spearman correlation analysis and its involvement in sperm–oocyte penetration by the human sperm–hamster egg penetration test. The current study demonstrates that HSPA4L is a promising marker for the assessment of sperm quality and provides clues for exploring biomarkers for the molecular diagnosis and treatment of male infertility.     

The R-type pyocin of Pseudomonas aeruginosa is related to P2 phage, and the F-type is related to lambda phage

Pseudomonas aeruginosa produces three types of bacteriocins: R-, F- and S-type pyocins. The S-type pyocin is a colicin-like protein, whereas the R-type pyocin resembles a contractile but non-flexible tail structure of bacteriophage, and the F-type a flexible but non-contractile one. As genetically related phages exist for each type, these pyocins have been thought to be variations of defective phage. In the present study, the nucleotide sequence of R2 pyocin genes, along with those for F2 pyocin, which are located downstream of the R2 gene cluster on the chromosome of P. aeruginosa PAO1, was analysed in order to elucidate the relationship between the pyocins and bacteriophages. The results clearly demonstrated that the R-type pyocin is derived from a common ancestral origin with P2 phage and the F-type from lambda phage. This notion was supported by identification of a lysis gene cassette similar to those for bacteriophages. The gene organization of the R2 and F2 pyocin gene cluster, however, suggested that both pyocins are not simple defective phages, but are phage tails that have been evolutionarily specialized as bacteriocins. A systematic polymerase chain reaction (PCR) analysis of P. aeruginosa strains that produce various subtypes of R and F pyocins revealed that the genes for every subtype are located between trpE and trpG in the same or very similar gene organization as for R2 and F2 pyocins, but with alterations in genes that determine the receptor specificity.     

Molecular analysis of a sulphate-reducing consortium used to treat metal-containing effluents

A sulphate-reducing consortium used in a bioprocess to remove toxic metals from solution as insoluble sulphides, was characterised using molecular (PCR-based) and traditional culturing techniques. After prolonged cultivation under anoxic biofilm-forming conditions, the mixed culture contained a low diversity of sulphate-reducing bacteria, dominated by one strain closely related to Desulfomicrobium norvegicum, identified by three independent PCR-based analyses. The genetic targets used were the 16S rRNA gene, the 16S-23S rRNA gene intergenic spacer region and the disulfite reductase (dsr) gene, which is conserved amongst all known sulphate-reducing bacteria. This organism was also isolated by conventional anaerobic techniques, confirming its presence in the mixed culture. A surprising diversity of other non-sulphate-reducing facultative and obligate anaerobes were detected, supporting a model of the symbiotic/commensal nature of carbon and energy fluxes in such a mixed culture while suggesting the physiological capacity for a wide range of biotransformations by this stable microbial consortium.