Biology subjects

Lepori, F.

Publications and source records attributed to Lepori, F..

2 recordsLinked to original sources

bioRxiv2025

Microbial nitrogen removal versus recycling in the redox transition zone of a meromictic lake and its coupling to sulfur

Organotrophic denitrification is an important nitrogen (N) removal process in lakes, but alternative N reduction processes such as lithotrophic sulfur (S)-oxidizing denitrification may be greatly underappreciated. We studied the redox transition zone (RTZ) in the meromictic water column of the North Basin of Lake Lugano (Switzerland) to characterize N transformation pathways coupled to the S and carbon (C) cycles. Incubations with 15N-labeled and unlabeled nitrate showed low denitrification rates and a general limitation of organic electron donors. The most accessible fractions of exported primary production biomass may have been largely consumed in the oxic water column during sedimentation, and did not reach the RTZ at [~]100 m. Conversely, sulfide (H2S) and methane (CH4), major end products of anaerobic degradation of the more recalcitrant organic matter fractions in the sediment, represent a continuous source of energy to the RTZ, fostering the establishment of a community of S- and CH4-dependent nitrate reducers, dominated by Sulfuritalea and Candidatus Methylomirabilis over several years of observation. Anoxic incubation experiments with H2S amendments revealed a strong stimulation of dissimilatory nitrate reduction to ammonium (DNRA), but not denitrification. High relative abundances of the archaeal ammonia oxidizer Candidatus Nitrosopumilus and bacterial nitrifiers indicate intense nitrate regeneration by nitrification in the upper RTZ. The potential interaction between nitrification and S-driven DNRA is unclear. However, their importance in close proximity suggests that, at least under conditions of carbon limitation, N recycling between the nitrate and ammonium pools, predominates over N removal via complete denitrification in the Lake Lugano North Basin.

microbiology↗

bioRxiv2024

Does Precision Grip Research Extend to Unconstrained, Multidigit Grasping?

Most daily tasks require using our hands. Whether taking a sip from a glass or throwing a ball, we effortlessly select appropriate grasps. Yet, despite many possible hand configurations, most grasping research has focused on the finger-and-thumb precision grip. We thus questioned whether findings on precision grip hold under unconstrained grasping conditions. To test this, we compared how participants grasped 3D objects made of brass and wood, with both precision grip and unconstrained grasps. When unconstrained, participants rarely selected precision grips, favoring multi-digit grasps. Nevertheless, in both conditions, participants shifted grasps towards the objects center of mass and, when grasp factors conflicted, the variability in their selections increased, indicating greater uncertainty about the optimal strategy. Further, despite favoring multidigit grasps, participants consistently placed the thumb and index finger on the same positions on the objects, suggesting that in multidigit grasps, the additional fingers primarily provided support. Our findings thus reveal that object material affects unconstrained grasping similarly to precision grip and imply that previous precision grip research may extend to unconstrained, multidigit conditions. NEW & NOTEWORTHYMost grasping research focuses on two-digit precision grips, yet humans have more than two fingers. Here, we test whether previous precision grip findings apply to unconstrained grasping. We find that participants often use more than two digits when free to choose but consistently place thumb and index finger similarly on objects regardless of the number of fingers used. Our results thus highlight how the large body of precision grip literature can extend to multidigit grasping.

neuroscience↗