Microbial Composition and Functional Diversity Differ Across Urban Green Infrastructure Types.

Functional and biogeographical properties of soil microbial communities in urban ecosystems are poorly understood despite their role in metabolic processes underlying valuable ecosystem services. The worldwide emergence of engineered habitats in urban landscapes-green roofs, bioswales, and other types of soil-based green infrastructure-highlights the importance of understanding how environmental changes affect the community assembly processes that shape urban microbial diversity and function. In this study we investigated (1) whether engineered green roofs and bioswales in New York City had distinct microbial community composition and trait-associated diversity compared to non-engineered soils in parks and tree pits, and (2) if these patterns were consistent with divergent community assembly processes associated with engineered specifications of green infrastructure habitats not present in conventional, non-engineered green infrastructure; specifically, tree pit and park lawn soils. We found that green roofs and bioswales each had distinct bacterial and fungal communities, but that community composition and diversity were not significantly associated with geographic distance, suggesting that the processes structuring these differences are related to aspects of the habitats themselves. Bioswales, and to a lesser extent green roofs, also contained increased functional potential compared to conventional GI soils, based on the diversity and abundance of taxa associated with nitrogen cycling, biodegradation, decomposition, and traits positively associated with plant growth. We discuss these results in the context of community assembly theory, concluding that urban soil microbial community composition and diversity in engineered habitats are driven largely by environmental filtering, whereas stochastic processes are more important among non-engineered soils.

The effects of oxytocin and arginine vasopressin in vitro on epididymal contractility in the rat.

Oxytocin (OT) and arginine vasopressin (AVP) have been found to be present in the reproductive system of the mammalian male, but their function in this system is unclear. This study examined the effects of these two hormones on contractions of the rat caput epididymis, as well as the hormones' effects on epididymal diameter during contractions. The initial segments of caput epididymides were observed in vitro in a solution of modified Tyrode's solution, with a test solution containing a concentration of either OT or AVP being added after a 5-min period. The frequency and diameter of the epididymal contractions were measured before and after addition of each test solution. Also observed was the effect of magnesium concentrations on the ability of OT to induce changes in epididymal contractility. This study found that the frequency of epididymal contractions increase and that the diameter of the epididymal tubules decrease proportionally during contractions with the addition of either OT or AVP. Furthermore, we noted that Mg++ has an inverse correlation with the frequency of contractions of the caput epididymis both in the presence and absence of OT. These findings suggest that both OT and AVP may have a role in regulating epididymal contractility and thus, perhaps, sperm transport through that organ.