Exposure to polystyrene nanoplastics reduces bacterial and fungal biomass in microfabricated soil models.

Nanoplastics have been proven to induce toxicity in diverse organisms, yet their effect on soil microbes like bacteria and fungi remains largely unexplored. In this paper, we used micro-engineered soil models to investigate the effect of polystyrene (PS) nanospheres on Pseudomonas putida and Coprinopsis cinerea. Specifically, we explored the effects of increasing concentrations of 60 nm carboxylated bovine serum albumin (BSA) coated nanospheres (0, 0.5, 2, and 10 mg/L) on these bacterial and fungal model organisms respectively, over time. We found that both microorganisms could disperse through the PS solution, but long-distance dispersal was reduced by high concentrations. Microbial biomass decreased in all treatments, in which bacteria showed a linear dose response with the strongest effect at 10 mg/L concentration, and fungi showed a non-linear response with the strongest effect at 2 mg/L concentration. At the highest nanoplastics concentration, the first colonizing fungal hyphae adsorbed most of the PS nanospheres present in their vicinity, in a process that we termed the 'vacuum cleaner effect'. As a result, the toxicity effect of the original treatment on subsequently growing fungal hyphae was reduced to a growth level indistinguishable from the control. We did not find evidence that nanoplastics are able to penetrate bacterial nor fungal cell walls. Overall, our findings provide evidence that nanoplastics can cause a direct negative effect on soil microbes and highlight the need for further studies that can explain how the microbial stress response might affect soil functions.

Microfluidic chips provide visual access to in situ soil ecology.

Microbes govern most soil functions, but investigation of these processes at the scale of their cells has been difficult to accomplish. Here we incubate microfabricated, transparent 'soil chips' with soil, or bury them directly in the field. Both soil microbes and minerals enter the chips, which enables us to investigate diverse community interdependences, such as inter-kingdom and food-web interactions, and feedbacks between microbes and the pore space microstructures. The presence of hyphae ('fungal highways') strongly and frequently increases the dispersal range and abundance of water-dwelling organisms such as bacteria and protists across air pockets. Physical forces such as water movements, but also organisms and especially fungi form new microhabitats by altering the pore space architecture and distribution of soil minerals in the chip. We show that soil chips hold a large potential for studying in-situ microbial interactions and soil functions, and to interconnect field microbial ecology with laboratory experiments.

Systemic canine histoplasmosis: A case report from Ecuador.

Histoplasmosis is a zoonotic systemic mycosis caused by Histoplasma capsulatum. We report a case of a female canine, 4 years old, presenting multifocal lymphadenitis and skin and gingival lesions, in Ecuador. Based on cytological, histopathological, histochemical analyses, fungal culture and DNA sequencing of the ITS region of the fungus, the diagnosis confirmed the presence of H. capsulatum as the agent of infection. The treatment plan included ketoconazole with a satisfactory outcome.

Cost-effectiveness of using small vertebrates as indicators of disturbance.

In species-rich tropical forests, effective biodiversity management demands measures of progress, yet budgetary limitations typically constrain capacity of decision makers to assess response of biological communities to habitat change. One approach is to identify ecological-disturbance indicator species (EDIS) whose monitoring is also monetarily cost-effective. These species can be identified by determining individual species' responses to disturbance across a gradient; however, such responses may be confounded by factors other than disturbance. For example, in mountain environments the effects of anthropogenic habitat alteration are commonly confounded by elevation. EDIS have been identified with the indicator value (IndVal) metric, but there are weaknesses in the application of this approach in complex montane systems. We surveyed birds, small mammals, bats, and leaf-litter lizards in differentially disturbed cloud forest of the Ecuadorian Andes. We then incorporated elevation in generalized linear (mixed) models (GL(M)M) to screen for EDIS in the data set. Finally, we used rarefaction of species accumulation data to compare relative monetary costs of identifying and monitoring EDIS at equal sampling effort, based on species richness. Our GL(M)M generated greater numbers of EDIS but fewer characteristic species relative to IndVal. In absolute terms birds were the most cost-effective of the 4 taxa surveyed. We found one low-cost bird EDIS. In terms of the number of indicators generated as a proportion of species richness, EDIS of small mammals were the most cost-effective. Our approach has the potential to be a useful tool for facilitating more sustainable management of Andean forest systems.

Evolutionary history of Andean Pholidobolus and Macropholidus (Squamata: Gymnophthalmidae) lizards.

Andean Pholidobolus and Macropholidus lizards contain seven and two species, respectively, as currently recognized. We analyze three mitochondrial loci (12S, 16S, ND4) using Bayesian methods to clarify the phylogenetic relationships between these genera based on a well-supported phylogenetic hypothesis. The phylogenetic tree obtained in this paper includes two main clades and shows that both Pholidobolus and Macropholidus are not monophyletic. A chronophylogenetic analysis indicates that the southernmost clade, occurring in the Huancabamba Depression, diversified earlier than the northern-Andes clade. Bayesian hypothesis tests reject previous phylogenetic hypotheses. We propose phylogenetic definitions for the main clades inferred herein.