Effects of COVID-19 Infection on Spermatogenesis, Oxidative Stress and Erectile Function.

Background: Our aim was to evaluate the effect of COVID-19 infection on male fertility and sexual function.

Methods: Thirty-one patients were investigated over a mean follow-up of 90 days (22-527) after a COVID-19 infection. Erectile dysfunction (ED), blood tests for sexual hormones, semen analysis including analysis of oxidative stress (OS), as well as COVID-19 antibody titer and the nasal COVID-19 PCR test were evaluated pre- and post-infection.

Long-Term Follow-Up after Testicular Torsion: Prospective Evaluation of Endocrine and Exocrine Testicular Function, Fertility, Oxidative Stress and Erectile Function.

Background: This study investigates endocrine and exocrine testicular function, oxidative stress (OS) in semen, and erectile function in patients who underwent surgery for suspected testicular torsion (TT). Methods: We evaluated 49 patients over a mean follow-up of 101 months: n = 25 patients treated with surgical exploration, n = 20 patients treated with detorsion, and n = 4 treated with orchiectomy. We performed semen analysis including Male infertility Oxidative System (MyOxSIS) analysis, physical examination, and evaluation of endocrine and erectile function.

Habitat isolation reduces intra- and interspecific biodiversity and stability.

Fragmentation is predicted to reduce biodiversity and stability by increasing habitat isolation and impeding dispersal among patches. These effects may manifest at both the interspecific and intraspecific levels, yet few studies have simultaneously explored dispersal effects across levels of organization. We used field mesocosm experiments to examine how habitat isolation (in the form of dispersal rate) alters inter- and intraspecific stability and diversity in local zooplankton communities.

Current water quality guidelines across North America and Europe do not protect lakes from salinization.

Human-induced salinization caused by the use of road deicing salts, agricultural practices, mining operations, and climate change is a major threat to the biodiversity and functioning of freshwater ecosystems. Yet, it is unclear if freshwater ecosystems are protected from salinization by current water quality guidelines. Leveraging an experimental network of land-based and in-lake mesocosms across North America and Europe, we tested how salinization-indicated as elevated chloride (Cl) concentration-will affect lake food webs and if two of the lowest Cl thresholds found globally are sufficient to protect these food webs.

LithoVue™ for renal stone therapy - a perfect fit for high volume academic centers; a retrospective evaluation of 108 cases.

Background: Over the last few years the number of flexible ureterorenoscopies, used for renal stone treatment, has risen steadily. This was associated with an increase in costs for maintenance and repair of the fragile ureterorenoscopes used. To overcome this problem single-use devices have been introduced to the market.

Eco-Evolutionary Dynamics in the Wild: Clonal Turnover and Stability in Populations.

There is increasing recognition of the importance of rapid adaptation in the dynamics of populations and communities. While the effects of rapid adaptation on the stability of populations have been shown in experimental systems, demonstration of their impacts in natural populations are rare. We examined the relationship between clonal dynamics and population stability of natural populations experiencing seasonal environmental variation.

Impacts of dispersal on rapid adaptation and dynamic stability of Daphnia in fluctuating environments.

Prior ecological research has shown that spatial processes can enhance the temporal stability of populations in fluctuating environments. Less explored is the effect of dispersal on rapid adaptation and its concomitant impact on population dynamics. For asexually reproducing populations, theory predicts that dispersal in fluctuating environments can facilitate asynchrony among clones and enhance stability by reducing temporal variability of total population abundance.

Synchronous dynamics of zooplankton competitors prevail in temperate lake ecosystems.

Although competing species are expected to exhibit compensatory dynamics (negative temporal covariation), empirical work has demonstrated that competitive communities often exhibit synchronous dynamics (positive temporal covariation). This has led to the suggestion that environmental forcing dominates species dynamics; however, synchronous and compensatory dynamics may appear at different length scales and/or at different times, making it challenging to identify their relative importance. We compiled 58 long-term datasets of zooplankton abundance in north-temperate and sub-tropical lakes and used wavelet analysis to quantify general patterns in the times and scales at which synchronous/compensatory dynamics dominated zooplankton communities in different regions and across the entire dataset.

Environmental noise, genetic diversity and the evolution of evolvability and robustness in model gene networks.

The ability of organisms to adapt and persist in the face of environmental change is accepted as a fundamental feature of natural systems. More contentious is whether the capacity of organisms to adapt (or "evolvability") can itself evolve and the mechanisms underlying such responses. Using model gene networks, I provide evidence that evolvability emerges more readily when populations experience positively autocorrelated environmental noise (red noise) compared to populations in stable or randomly varying (white noise) environments.

The stabilizing effects of genetic diversity on predator-prey dynamics.

Heterogeneity among prey in their susceptibility to predation is a potentially important stabilizer of predator-prey interactions, reducing the magnitude of population oscillations and enhancing total prey population abundance. When microevolutionary responses of prey populations occur at time scales comparable to population dynamics, adaptive responses in prey defense can, in theory, stabilize predator-prey dynamics and reduce top-down effects on prey abundance. While experiments have tested these predictions, less explored are the consequences of the evolution of prey phenotypes that can persist in both vulnerable and invulnerable classes.

Transient dynamics and the destabilizing effects of prey heterogeneity.

The presence of prey heterogeneity and weakly interacting prey species is frequently viewed as a stabilizer of predator-prey dynamics, countering the destabilizing effects of enrichment and reducing the amplitude of population cycles. However, prior model explorations have largely focused on long-term, dynamic attractors rather than transient dynamics. Recent theoretical work shows that the presence of prey that are defended from predation can have strongly divergent effects on dynamics depending on time scale: prey heterogeneity can counteract the destabilizing effects of enrichment on predator-prey dynamics at long time scales but strongly destabilize systems during transient phases by creating long periods of low predator/prey abundance and increasing extinction probability (an effect that is amplified with increasing enrichment).

Dispersal promotes compensatory dynamics and stability in forced metacommunities.

Understanding the factors that govern the stability of populations and communities has gained increasing importance as habitat fragmentation and environmental perturbations continue to escalate due to human activities. Dispersal is commonly viewed as essential to the maintenance of diversity in spatially subdivided communities, but few experiments have explored how dispersal interacts with the spatiotemporal components of environmental perturbations to determine community-level stability. We examined these processes using an experimental planktonic system composed of three competing species of zooplankton.

Periodically forced food-chain dynamics: model predictions and experimental validation.

Despite the recognition of the importance of seasonal forcing in nature, remarkably few studies have theoretically explored periodically forced community dynamics. Here we employ a novel approach called "successional state dynamics" (SSD) to model a seasonally forced predator-prey system. We first generated analytical predictions of the effects of altered seasonality on species persistence and the timing of community state transitions.

Resurrecting the ghost of competition past with dormant zooplankton eggs.

A common prediction of evolutionary theory is that the strength of interspecific competition should decline over time among sympatric populations of competing species. Here we provide experimental evidence of historical declines in competition effects among competing zooplankton populations. Using diapausing eggs, we resurrected clones of three species of zooplankton obtained from different periods of community assembly in a single lake.

Species richness and allometric scaling jointly determine biomass in model aquatic food webs.

1. Allometric theory makes specific predictions about how density, and consequently biomass, scale with organism size within trophic levels, across trophic levels and across food webs. 2.

Population and community resilience in multitrophic communities.

Diversity-stability relationships have long been a topic of controversy in ecology, but one whose importance has been re-highlighted by increasing large-scale threats to global biodiversity. The ability of a community to recover from a perturbation (or resilience) is a common measure of stability that has received a large amount of theoretical attention. Yet, general expectations regarding diversity-resilience relations remain elusive.

Context-dependent effects of Daphnia pulex on pond ecosystem function: observational and experimental evidence.

Large-bodied zooplankton of the genus Daphnia are thought to be keystone species in freshwater pelagic habitats, potentially able to exert strong grazing effects and enhance phosphorus limitation of algae. I examined the degree to which Daphnia pulex differ from small-bodied zooplankton in their effects on algal biomass, seston C:P and N:P, total nitrogen and total phosphorus. This was done with both survey data from natural ponds and an in situ experiment in which D.