Sympatric song variant in mountain chickadees Poecile gambeli does not reduce aggression from black-capped chickadees Poecile atricapillus

When habitats overlap and species compete for resources, negative interactions frequently occur. Character displacement in the form of behavioural, social or morphological divergences between closely related species can act to reduce negative interactions and often arise in regions of geographic overlap. Mountain chickadees  Poecile gambeli have an altered song structure in regions of geographic overlap with the behaviourally dominant black capped chickadee Poecile atricapillus. Similar to European and Asian tits, altered song in mountain chickadees  may decrease aggression from black-capped chickadees. To test this hypothesis, we conducted a playback study in Prince George, BC, Canada, to examine how black-capped chickadees responded to the songs of mountain chickadees recorded in regions where the two species were either sympatric or allopatric. We used principal  component analysis (PCA) to collapse behavioural response variables into a single ‘approach’ variable and a single ‘vocalisation’ variable. We then used mixed-model analysis to determine whether there was a difference in approach or vocalisation response to the two types of mountain chickadee songs (allopatric  songs and variant sympatric songs). Black-capped chickadees responded with equal intensity to both types of mountain chickadee songs, suggesting that the variant mountain chickadee songs from regions of sympatry with black-capped chickadees do not reduce heterospecific aggression. To our knowledge, this is the only instance of a character shift unassociated with reduced aggression in the family Paridae and raises interesting questions about the selective pressures leading to the evolution of this song divergence

Life history traits in selfing versus outcrossing annuals: exploring the 'time-limitation' hypothesis for the fitness benefit of self-pollination

BACKGROUND: Most self-pollinating plants are annuals. According to the 'time-limitation' hypothesis, this association between selfing and the annual life cycle has evolved as a consequence of strong r-selection, involving severe time-limitation for completing the life cycle. Under this model, selection from frequent density-independent mortality in ephemeral habitats minimizes time to flower maturation, with selfing as a trade-off, and / or selection minimizes the time between flower maturation and ovule fertilization, in which case selfing has a direct fitness benefit. Predictions arising from this hypothesis were evaluated using phylogenetically-independent contrasts of several life history traits in predominantly selfing versus outcrossing annuals from a data base of 118 species distributed across 14 families. Data for life history traits specifically related to maturation and pollination times were obtained by monitoring the start and completion of different stages of reproductive development in a greenhouse study of selfing and outcrossing annuals from an unbiased sample of 25 species involving five pair-wise family comparisons and four pair-wise genus comparisons. RESULTS: Selfing annuals in general had significantly shorter plant heights, smaller flowers, shorter bud development times, shorter flower longevity and smaller seed sizes compared with their outcrossing annual relatives. Age at first flower did not differ significantly between selfing and outcrossing annuals. CONCLUSIONS: This is the first multi-species study to report these general life-history differences between selfers and outcrossers among annuals exclusively. The results are all explained more parsimoniously by selection associated with time-limitation than by selection associated with pollinator/mate limitation. The shorter bud development time reported here for selfing annuals is predicted explicitly by the time-limitation hypothesis for the fitness benefit of selfing (and not by the alternative 'reproductive assurance' hypothesis associated with pollinator/mate limitation). Support for the time-limitation hypothesis is also evident from published surveys: whereas selfers and outcrossers are about equally represented among annual species as a whole, selfers occur in much higher frequencies among the annual species found in two of the most severely time-limited habitats where flowering plants grow – deserts and cultivated habitats

Glycerol extends lifespan of Brachionus manjavacas (Rotifera) and protects against stressors

AbstractDiet has profound effects on animal longevity and manipulation of nutrient sensing pathways is one of the primary interventions capable of lifespan extension. This often is done through caloric restriction (CR) and a variety of CR mimics have been identified that produce life extending effects without adhering to the rigorous CR dietary regimen. Glycerol is a dietary supplement capable mimicking CR by shifting metabolism away from glycolysis and towards oxidative phosphorylation. Glycerol supplementation has a number of beneficial effects, including lifespan extension, improved stress resistance, and enhanced locomotory and mitochondria activity in older age classes. Using rotifers as a model, we show that supplements of 150–300mM glycerol produced 40–50% extension of mean lifespan. This effect was produced by raising glycerol concentration only three times higher than its baseline concentration in rotifer tissues. Glycerol supplementation decreased rotifer reliance on glycolysis and reduced the pro-aging effects of glucose. Glycerol also acted as a chemical chaperone, mitigating damage by protein aggregation. Glycerol treatment improved rotifer swimming performance in older age classes and maintained more mitochondrial activity. Glycerol treatment provided increased resistance to starvation, heat, oxidation, and osmotic stress, but not UV stress. When glycerol was co-administered with the hexokinase inhibitor 2-deoxyglucose, the lifespan extending effect of glycerol was enhanced. Co-administration of glycerol with inhibitors like 2-deoxyglucose can lower their efficacious doses, thereby reducing their toxic side effects

A world wide web based informational reference source for ocular diseases using bacterial conjunctivitis as a template

Introduction: The project consists of a World Wide Web (WWW) site that can be accessed by . all interested individuals knowledgeable in WWW operating protocol. The design is of an informational reference source to aid the practicing clinician and the optometric student in gathering cross-referenced information regarding a particular ocular disease. This project did not develop the entire reference base for all ocular disease conditions, but rather developed a generic template using bacterial conjunctivitis as an example. Using the established protocol, additional ocular disease conditions will be added in the future to complete the site. Methods: Microsoft Frontpage 97 was used to create a World Wide Web (WWW) site consisting of six separate but interrelated pages. The six main sections of the ocular disease web site include; pathology and disease conditions, diagnostic techniques, differential diagnosis, causative agents, pharmacology, and references. Information on each topic section was derived from multiple reference sources including current text books, journal articles and class notes. Each page has detailed text information, full color images of the various conditions, as well as helpful visual information to reinforce text information. Crossed reference links were built to allow the user to easily access related information contained in the other topic pages. Even though this project is self contained, it has built-in links to various optometric and related medical information sites. Results: The project was presented to local practitioners where it received positive praise. The web site was uploaded to the Pacific University College of Optometry home page. Testing and evaluation of the performance is currently being conducted. Discussion: Use of the World Wide Web as a source of information IS still in its infancy. The potential for practitioners of Optometry to access this vast wealth information in a rapid and efficient manner is just beginning to be realized The strength of this format is the ability to access all related information contained in any other page by simply clicking a button

Variation in Morphology vs Conservation of a Mitochondrial Gene in Montastraea cavernosa (Cnidaria, Scleractinia)

Skeletal morphology of many scleractinian corals may be influenced by environmental factors and may thus result in substantial intraspecific phenotypic plasticity and, possibly, in overlapping morphologies between species. Environmentally induced variation can also mask phenotypic variation that is genetically based. Morphological analyses and DNA sequence analyses were performed on Montastraea cavernosa from the Flower Garden Banks, Texas, and from the Florida Keys in order to assess variation within and between geographic regions. Skeletal characters, including corallite diameter, columella width, theca thickness, nearest-neighbor distance, length of first septa cycle, and width of first septa cycle, varied within colonies, among colonies, and between the Flower Garden Banks and the Florida Keys. Morphological variation may be controlled by environmental and genetic influences at different levels. If phenotype is under genetic control, it is not influenced by the mitochondrial cytochrome oxidase subunit I gene, because analysis of a 708 base pair fragment revealed identical sequences of M. cavernosa from these geographic regions. This high level of nucleotide sequence similarity may result from functional constraints, efficient DNA repair mechanisms, or other processes. This gene was not found to exhibit any variation in association with that observed in the morphology, and we suggest that it is an inappropriate genetic marker to use to assess intraspecific variation within this species and possibly other scleractinian species as well. Analysis via other molecular techniques will be necessary in order to assess the factors that influence morphological variation and that distinguish populations within this species

Riparian Meadow Response to Modern Conservation Grazing Management.

Riparian meadows occupy a small proportion of the public lands in the western United States but they provide numerous ecosystem services, including the production of high-quality forage for livestock grazing. Modern conservation management strategies (e.g., reductions in livestock stocking rates and adoption of new riparian grazing standards) have been implemented to better balance riparian conservation and livestock production objectives on publicly managed lands. We examined potential relationships between long-term changes in plant community, livestock grazing pressure and environmental conditions at two spatial scales in meadows grazed under conservation management strategies. Changes in plant community were not associated with either livestock stocking rate or precipitation at the grazing allotment (i.e., administrative) scale. Alternatively, both grazing pressure and precipitation had significant, albeit modest, associations with changes in plant community at the meadow (i.e., ecological site) scale. These results suggest that reductions in stocking rate have improved the balance between riparian conservation and livestock production goals. However, associations between elevation, site wetness, precipitation, and changes in plant community suggest that changing climate conditions (e.g., reduced snowpack and changes in timing of snowmelt) could trigger shifts in plant communities, potentially impacting both conservation and agricultural services (e.g., livestock and forage production). Therefore, adaptive, site-specific management strategies are required to meet grazing pressure limits and safeguard ecosystem services within individual meadows, especially under more variable climate conditions

Uric Acid as a Potential Peripheral Biomarker for Disease Features in Huntington's Patients.

Oxidative stress has long been implicated in the pathophysiology and progression of Huntington's disease (HD). Uric acid (UA) is a naturally occurring antioxidant that is present in the brain and periphery. Growing evidence has implicated UA as a molecular biomarker for several neurodegenerative diseases, most notably Parkinson's disease (PD). In this study, we investigated UA levels in clinical samples from HD patients and normal controls (NCs) and assessed potential relationships between UA levels and disease and clinical data. UA levels were measured in plasma (n = 107) and saliva (n = 178) samples from premanifest (pre-HD) and manifest HD patients and control subjects. Gender effects of UA levels were observed in both biofluids, with male patients showing higher UA levels compared to female patients. Comparisons of UA levels across diagnostic groups, separated by gender, revealed that both plasma and salivary UA levels were significantly lower in female pre-HD and manifest HD patients compared to NCs. Salivary levels of UA were also significantly lower in male manifest HD patients versus controls, but not in plasma. Correlations of peripheral UA levels to clinical data also showed differences according to gender. In male HD patients, both plasma and salivary UA levels were significantly negatively correlated with total functional capacity (TFC), while positive correlations were observed with total motor score (TMS). Female HD patients showed a significant positive correlation between plasma UA levels and TMS, while salivary UA levels from female patients were significantly correlated to disease burden. Finally, in a separate cohort, we show that UA levels are decreased in postmortem prefrontal cortical samples (n = 20) from HD subjects compared to matched controls. These findings suggest that decreased levels of UA in the brains of HD patients can be reflected in peripheral fluids, with salivary measures of UA particularly offering significant promise as a potentially relevant, non-invasive biomarker of disease symptoms and burden. Our findings further highlight the impact of sexual dimorphism in HD pathophysiology

Size and Distribution of Resting Eggs in a Natural Population of the Rotifer Brachionus plicatilis

Resting eggs of the rotifer Brachionus plicatilis were collected from the sediments of a brackish-water pond near Tampa, Florida. These core samples were examined for resting egg density and size. Resting egg density decreased exponentially from the surface down to 7 cm in the sediments at all stations, with depth in the sediments accounting for 42.3% of the total variance. The maximum resting egg density recorded was 194 RE/cm3 with no significant differences in density among stations. Resting eggs were found to be significantly larger in the top 2 cm of sediment than resting eggs from deeper in the sediments. These data are discussed with regard to other work on resting egg densities in natural populations. Hypotheses are offered to explain the observed decrease in resting egg size with depth in sediments