Dual thermal ecotypes coexist within a nearly genetically identical population of the unicellular marine cyanobacterium Synechococcus.

The extent and ecological significance of intraspecific functional diversity within marine microbial populations is still poorly understood, and it remains unclear if such strain-level microdiversity will affect fitness and persistence in a rapidly changing ocean environment. In this study, we cultured 11 sympatric strains of the ubiquitous marine picocyanobacterium Synechococcus isolated from a Narragansett Bay (RI) phytoplankton community thermal selection experiment. Thermal performance curves revealed selection at cool and warm temperatures had subdivided the initial population into thermotypes with pronounced differences in maximum growth temperatures. Curiously, the genomes of all 11 isolates were almost identical (average nucleotide identities of >99.99%, with >99% of the genome aligning) and no differences in gene content or single nucleotide variants were associated with either cool or warm temperature phenotypes. Despite a very high level of genomic similarity, sequenced epigenomes for two strains showed differences in methylation on genes associated with photosynthesis. These corresponded to measured differences in photophysiology, suggesting a potential pathway for future mechanistic research into thermal microdiversity. Our study demonstrates that present-day marine microbial populations can harbor cryptic but environmentally relevant thermotypes which may increase their resilience to future rising temperatures.

Following the Astrobiology Roadmap: Origins, Habitability and Future Exploration.

Astrobiology asks three fundamental questions as outlined by the NASA Astrobiology Roadmap: 1. How did Life begin and evolve?; Is there Life elsewhere in the Universe?; and, What is the future of Life on Earth? As we gain perspective on how Life on Earth arose and adapted to its many niches, we too gain insight into how a planet achieves habitability. Here on Earth, microbial Life has evolved to exist in a wide range of habitats from aquatic systems to deserts, the human body, and the International Space Station (ISS). Landers, rovers, and orbiter missions support the search for signatures of Life beyond Earth, by generating data on surface and subsurface conditions of other worlds. These have provided evidence for water activity, supporting the potential for extinct or extant Life. To investigate the putative ecologies of these systems, we study extreme environments on Earth. Several locations on our planet provide analog settings to those we have detected or expect to find on neighboring and distant worlds. Whereas, the field of space biology uses the ISS and low gravity analogs to gain insight on how transplanted Earth-evolved organisms will respond to extraterrestrial environments. Modern genomics allows us to chronicle the genetic makeup of such organisms and provides an understanding of how Life adapts to various extreme environments.

Adaptations of endolithic communities to abrupt environmental changes in a hyper-arid desert.

The adaptation mechanisms of microbial communities to natural perturbations remain unexplored, particularly in extreme environments. The extremophilic communities of halite (NaCl) nodules from the hyper-arid core of the Atacama Desert are self-sustained and represent a unique opportunity to study functional adaptations and community dynamics with changing environmental conditions. We transplanted halite nodules to different sites in the desert and investigated how their taxonomic, cellular, and biochemical changes correlated with water availability, using environmental data modeling and metagenomic analyses. Salt-in strategists, mainly represented by haloarchaea, significantly increased in relative abundance at sites characterized by extreme dryness, multiple wet/dry cycles, and colder conditions. The functional analysis of metagenome-assembled genomes (MAGs) revealed site-specific enrichments in archaeal MAGs encoding for the uptake of various compatible solutes and for glycerol utilization. These findings suggest that opportunistic salt-in strategists took over the halite communities at the driest sites. They most likely benefited from compounds newly released in the environment by the death of microorganisms least adapted to the new conditions. The observed changes were consistent with the need to maximize cellular bioenergetics when confronted with lower water availability and higher salinity, providing valuable information on microbial community adaptations and resilience to climate change.

A pilot, prospective evaluation of a novel alternative for maintenance therapy of breast cancer-associated lymphedema [ISRCTN76522412].

BACKGROUND: Prospective investigations of complete decongestive lymphatic physiotherapy (CDPT), including manual lymphatic drainage (MLD), have validated the efficacy of these interventions for the initial reduction of edema and long-term maintenance of limb volume in lymphedema. However, CDPT demands substantial time and effort from patients to maintain these benefits; the treatments are not always well-accepted, and patients may suffer from a deterioration in quality-of-life or a time-dependent loss of initial treatment benefits. A new device designed for home use by the patient, the Flexitouch, has been developed to mechanically simulate MLD. We have undertaken a prospective, randomized, crossover study of the efficacy of the Flexitouch, when compared to massage, in the self-administered maintenance therapy of lymphedema. METHODS: A prospective, randomized, crossover study of maintenance therapy was performed in 10 patients with unilateral breast cancer-associated lymphedema of the arm. Each observation phase included self-administered treatment with the Flexitouch or massage, 1 hour daily for 14 days, respectively, followed by crossover to the alternate treatment phase. Each treatment phase was preceded by a 1 week treatment washout, with use of garment only. The sequence of treatment was randomly assigned. The potential impact of treatment modality on quality of life was assessed with serial administration of the SF-36. RESULTS: Statistical analysis disclosed that the order of treatment had no outcome influence, permitting 10 comparisons within each treatment group. Post-treatment arm volume reduced significantly after the Flexitouch, but not after self-administered massage. The patients' mean weight decreased significantly with Flexitouch use, but not with massage. The Flexitouch device was apparently well-tolerated and accepted by patients. Serial SF-36 administration showed no deterioration in physical or psychosocial scores compared to baseline measurements; there were no statistical differences in scores when the two treatment modalities were compared. CONCLUSION: This short-term prospective evaluation of the Flexitouch suggests that the device may provide better maintenance edema control than self-adiminstered massage in breast cancer-associated lymphedema. The apparent ease of use and reliability of response to the device suggest that further broad-scale testing is warranted.

An experimental model for the study of lymphedema and its response to therapeutic lymphangiogenesis.

BACKGROUND: Evaluation of the efficacy of molecular treatment strategies for lymphatic vascular insufficiency requires a suitable preclinical animal model. Ideally, the model should closely replicate the untreated human disease in its pathogenesis and pathological expression. OBJECTIVE: We have undertaken a study of the time course of the development and resolution of acquired, experimental lymphedema and of its responses to vascular endothelial growth factor (VEGF)-C lymphangiogenesis in the mouse tail model. STUDY DESIGN: We provoked post-surgical lymphedema in the mouse tail model and assessed the effects of exogenously administered human recombinant VEGF-C. Quantitative assessment of immune traffic function was performed through sequential in vivo bioluminescent imaging. RESULTS: In untreated lymphedema, tail edema was sustained until day 21. Exogenous administration of human recombinant VEGF-C produced a significant decrease in volume. Untreated lymphedema in the mouse tail model was characterized by the presence of dilated cutaneous lymphatics, marked acute inflammatory changes, and hypercellularity; VEGF-C produced a substantial reversion to the normal pattern, with notable regression in the size and number of cutaneous lymphatic vessels that express lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1). In vivo imaging confirmed the presence of an impairment of immune traffic in lymphedema that was ameliorated after VEGF-C administration. CONCLUSION: The post-surgical murine tail model of lymphedema closely simulates attributes of human lymphedema and provides the requisite sensitivity to detect therapeutically induced functional and structural alterations. It can, therefore, be used as an investigative platform to assess mechanisms of disease and its responses to candidate therapies, such as therapeutic lymphangiogenesis.

Validation of a new technique for the quantitation of edema in the experimental setting.

BACKGROUND: An inherent limitation to the study of in vivo animal models of lymphedema is the potential inaccuracy or unreliability of existing methods for the quantification of edema volume as a surrogate functional measure of lymphatic transport capacity. Circumference-based techniques have been proposed and validated as a suitable alternative to volume displacement measurements in human clinical studies; accordingly, we have elaborated a new application of this approach that can be applied to small animal studies. METHODS: Acute postsurgical lymphedema was created experimentally in the murine tail. Both normal and lymphedematous murine tails were examined. Tail volume was quantitated both by water displacement and by a digital photographic technique. In selected mice, after sacrificed on postsurgical day 7, a 6 cm segment was resected from the midportion of the tail and cauterized to create a closed space. Known incremental volumes of saline (20-100 microL) were injected for subsequent digital photographic volumetry. RESULTS: The coefficients of variation for volume assessment by water displacement and by digital imaging were 0.08+/-0.09 and 0.01+/-0.009, respectively. The two techniques were poorly correlated: while serial water displacement analysis yielded highly variable measurements within the same tail, concurrent digital imaging of the tail circumference was quite reproducible. Furthermore, after parenteral injection of known incremental volumes of saline, the correlation between the injectate volumes and the digitally measured increases in volume was high, both in the normal and the lymphedematous tail. CONCLUSION: In the murine tail, when compared to water displacement volumetry, digital photography yields highly reproducible data. We can conclude that the lack of correlation between the two methods, with the relatively flat slope of the linear regression relationship, reflects inherent inaccuracies of the water displacement method.

Olfactory deficits in an alpha-synuclein fly model of Parkinson's disease.

Parkinson's disease (PD) is the most common motor neurodegenerative disorder. Olfactory dysfunction is a prevalent feature of PD. It often precedes motor symptoms by several years and is used in assisting PD diagnosis. However, the cellular and molecular bases of olfactory dysfunction in PD are not known. The fruit fly Drosophila melanogaster, expressing human alpha-synuclein protein or its mutant, A30P, captures several hallmarks of PD and has been successfully used to model PD in numerous studies. First, we report olfactory deficits in fly expressing A30P (A30P), showing deficits in two out of three olfactory modalities, tested--olfactory acuity and odor discrimination. The remaining third modality is odor identification/naming. Second, oxidative stress is an important environmental risk factor of PD. We show that oxidative stress exacerbated the two affected olfactory modalities in younger A30P flies. Third, different olfactory receptor neurons are activated differentially by different odors in flies. In a separate experiment, we show that the odor discrimination deficit in A30P flies is general and not restricted to a specific class of chemical structure. Lastly, by restricting A30P expression to dopamine, serotonin or olfactory receptor neurons, we show that A30P expression in dopamine neurons is necessary for development of both acuity and discrimination deficits, while serotonin and olfactory receptor neurons appeared not involved. Our data demonstrate olfactory deficits in a synuclein fly PD model for exploring olfactory pathology and physiology, and for monitoring PD progression and treatment.