Find the food first: An omnivorous sensory morphotype predates biomechanical specialization for plant based diets in phyllostomid bats

The role of mechanical morphologies in the exploitation of novel niche space is well characterized; however, the role of sensory structures in unlocking new niches is less clear. Here, we investigate the relationship between the evolution of sensory structures and diet during the radiation of noctilionoid bats. With a broad range of foraging ecologies and a well-supported phylogeny, noctilionoids constitute an ideal group for studying this relationship. We used diffusible iodine-based contrast enhanced computed tomography scans of 44 noctilionoid species to analyze relationships between the relative volumes of three sensory structures (olfactory bulbs, orbits, and cochleae) and diet. We found a positive relationship between frugivory and both olfactory and orbit size. However, we also found a negative relationship between nectarivory and cochlea size. Ancestral state estimates suggest that larger orbits and olfactory bulbs were present in the common ancestor of family Phyllostomidae, but not in other noctilionoid. This constellation of traits indicates a shift toward omnivory at the base of Phyllostomidae, predating their radiation into an exceptionally broad range of dietary niches. This is consistent with a scenario in which changes in sensory systems associated with foraging and feeding set the stage for subsequent morphological modification and diversification.

Testing hypotheses of marsupial brain size variation using phylogenetic multiple imputations and a Bayesian comparative framework

Considerable controversy exists about which hypotheses and variables best explain mammalian brain size variation. We use a new, high-coverage dataset of marsupial brain and body sizes, and the first phylogenetically imputed full datasets of 16 predictor variables, to model the prevalent hypotheses explaining brain size evolution using phylogenetically corrected Bayesian generalized linear mixed-effects modelling. Despite this comprehensive analysis, litter size emerges as the only significant predictor. Marsupials differ from the more frequently studied placentals in displaying a much lower diversity of reproductive traits, which are known to interact extensively with many behavioural and ecological predictors of brain size. Our results therefore suggest that studies of relative brain size evolution in placental mammals may require targeted co-analysis or adjustment of reproductive parameters like litter size, weaning age or gestation length. This supports suggestions that significant associations between behavioural or ecological variables with relative brain size may be due to a confounding influence of the extensive reproductive diversity of placental mammals.

Assessing Soft-Tissue Shrinkage Estimates in Museum Specimens Imaged With Diffusible Iodine-Based Contrast-Enhanced Computed Tomography (diceCT)

The increased accessibility of soft-tissue data through diffusible iodine-based contrast-enhanced computed tomography (diceCT) enables comparative biologists to increase the taxonomic breadth of their studies with museum specimens. However, it is still unclear how soft-tissue measurements from preserved specimens reflect values from freshly collected specimens and whether diceCT preparation may affect these measurements. Here, we document and evaluate the accuracy of diceCT in museum specimens based on the soft-tissue reconstructions of brains and eyes of five bats. Based on proxies, both brains and eyes were roughly 60% of the estimated original sizes when first imaged. However, these structures did not further shrink significantly over a 4-week staining interval, and 1 week in 2.5% iodine-based solution yielded sufficient contrast for differentiating among soft-tissues. Compared to six "fresh" bat specimens imaged shortly after field collection (not fixed in ethanol), the museum specimens had significantly lower relative volumes of the eyes and brains. Variation in field preparation techniques and conditions, and long-term storage in ethanol may be the primary causes of shrinkage in museum specimens rather than diceCT staining methodology. Identifying reliable tissue-specific correction factors to adjust for the shrinkage now documented in museum specimens requires future work with larger samples.

Timing the developmental origins of mammalian limb diversity

Mammals have highly diverse limbs that have contributed to their occupation of almost every niche. Researchers have long been investigating the development of these diverse limbs, with the goals of identifying developmental processes and potential biases that shape mammalian limb diversity. To date, researchers have used techniques ranging from the genomic to the anatomic to investigate the developmental processes shaping the limb morphology of mammals from five orders (Marsupialia, Chiroptera, Rodentia, Cetartiodactyla, and Perissodactyla). Results of these studies suggest that the differential expression of genes controlling diverse cellular processes underlies mammalian limb diversity. Results also suggest that the earliest development of the limb tends to be conserved among mammalian species, while later limb development tends to be more variable. This research has established the mammalian limb as a model system for evolutionary developmental biology, and set the stage for more in-depth, cross-disciplinary research into the genetic controls, tissue-level cellular behaviors, and selective pressures that have driven the developmental evolution of mammalian limbs. Ideally, these studies will be performed in a diverse suite of mammalian species within a comparative, phylogenetic framework.

The role of emotion in workplace incivility

Purpose

– The purpose of this paper is to examine leader-member exchange (LMX) and perceived organizational support (POS) as moderators of the relationship between psychological contract violation and workplace incivility.

Design/methodology/approach

– An online survey was administered to employed adults.

Findings

– The association between violation and incivility was more pronounced when levels of LMX and POS were higher.

Research limitations/implications

– The correlation design limits the ability to draw causal inferences. Affect models, including but not limited to affect infusion model (AIM), offer a useful framework for enhancing understanding of incivility and other forms of counterproductive work behaviors.

Practical implications

– The study has contributed to knowledge about contract violation’s implications for work behaviors, such as incivility. Managers sensitive to the dynamics of contract breach may prevent feelings of violation by communicating clearly and often about expectations, resources, and procedures.

Social implications

– Organizational and societal leaders may be well served by knowledge about preventing people’s intense responses to perceived violation by appropriately responding to perceived breach.

Originality/value

– The study draws upon AIM as a novel approach to understanding conditions under which negative emotions are most likely to relate to workplace incivility. Moreover, the roles of social exchange variables LMX and POS have heretofore been unexplored as moderators of the violation-incivility relationship.

Impacts of reduced sulfur components on active and resting ammonia oxidizers

While there has been significant research on the nature and extent of the impact of inhibitory reduced sulfur with respect to anaerobic (e.g., methanogenic and sulfidogenic) microbial systems, only limited study has yet been conducted on the comparable effects of soluble sulfides which might occur within aerobic wastewater treatment systems. Admittedly, aerobic reactors would not normally be considered conducive to the presence of reduced sulfur constituents, but there do appear to be a number of processing scenarios under which related impacts could develop, particularly for sensitive reactions like nitrification. Indeed, the following scenarios might well involve elevated levels of reduced sulfur within an aerobic reactor environment: (1) mixed liquor recycle back through sulfide-generating anaerobic zones (e.g., in conjunction with biological nutrient removal processes, etc.), (2) high-level side-stream sulfide recycle via sludge digestion, etc., back to aerobic reactors, and (3) high-level influent sulfide inputs to wastewater treatment facilities via specific industrial, septage, etc., streams. The objective of this study was, therefore, to determine the subsequent metabolic impact of soluble sulfide under aerated and unaerated conditions, focusing in particular on ammonia-oxidizing bacteria due to their critical first-step role with nitrification. The obtained results indicated that, under catabolically active conditions, cultures of ammonia oxidizers were extremely sensitive to the presence of sulfide. At total soluble sulfide concentrations of 0.25 mg l(-1) S, active ammonia oxidation was completely inhibited. However, immediately following the removal of this soluble sulfide presence, ammonia oxidation started to recover; and it continued to improve over the next 24 h. Similar sulfide impact tests conducted with inactive ammonia oxidizers exposed during anaerobic conditions, albeit at higher dosage levels, also revealed that their subsequent aerobic activity would correspondingly be retarded. These results indicated that, after sulfide exposure under unaerated conditions, subsequent aerobic oxidative activity rates rapidly decreased as the soluble sulfide exposure was increased from 0.5 gm l(-1) S to 5 mg l(-1) S and that further reductions in this activity progressively developed as the concentration was increased to 200 mg l(-1) S. The recovery following unaerated exposure to sulfide was significantly higher at pH 7, as compared with pH 8, and although the specific nature of this variation was not established, a hypothetical explanation appeared warranted.

Bilateral orchiectomy with or without flutamide for metastatic prostate cancer

BACKGROUND

Combined androgen blockade for the treatment of metastatic prostate cancer consists of an antiandrogen drug plus castration. In a previous trial, we found that adding the antiandrogen flutamide to leuprolide acetate (a synthetic gonadotropin-releasing hormone that results in medical ablation of testicular function) significantly improved survival as compared with that achieved with placebo plus leuprolide acetate. In the current trial, we compared flutamide plus bilateral orchiectomy with placebo plus orchiectomy.

METHODS

We randomly assigned patients who had never received antiandrogen therapy and who had distant metastases from adenocarcinoma of the prostate to treatment with bilateral orchiectomy and either flutamide or placebo. Patients were stratified according to the extent of disease and according to performance status.

RESULTS

Of the 1387 patients who were enrolled in the trial, 700 were randomly assigned to the flutamide group and 687 to the placebo group. Overall, the incidence of toxic effects was minimal; the only notable differences between the groups were the greater rates of diarrhea and anemia with flutamide. There was no significant difference between the two groups in overall survival (P=0.14). The estimated risk of death (hazard ratio) for flutamide as compared with placebo was 0.91 (90 percent confidence interval, 0.81 to 1.01). Flutamide was not associated with enhanced benefit in patients with minimal disease.

CONCLUSIONS

The addition of flutamide to bilateral orchiectomy does not result in a clinically meaningful improvement in survival among patients with metastatic prostate cancer.

Bronchoalveolar lavage: radiographic manifestations

Bronchoalveolar lavage (BAL) is a safe and well-tolerated procedure in which the lower respiratory tract is sampled through infusion and subsequent aspiration of sterile saline solution. To determine the radiographic changes consequent to this procedure, 25 patients undergoing fiberoptic bronchoscopy and BAL were evaluated prospectively. After lavage, anteroposterior radiographs were obtained immediately and after 30, 90, and 240 minutes, and 24 hours. The degree and site of opacification on the radiographs was graded on a 4+ subjective scale. Sixty-nine lobes were lavaged, but owing to overlap on the radiographs, 52 projected areas were evaluable for radiographic changes. Forty-seven areas of consolidation were identified on the radiographs obtained immediately after lavage. Consolidation was homogeneous and always corresponded to a projected site of lavage. There was a positive correlation between initial opacity on the radiograph and the volume of retained fluid (rs = .60, P less than .001). Consolidation cleared gradually over 24 hours. No patient had clinical pneumonitis. These benign, self-limited radiographic changes are common after BAL and may simulate pulmonary edema, aspiration, or hemorrhage.