Biology subjects

Yang, C. S.

Publications and source records attributed to Yang, C. S..

4 recordsLinked to original sources

bioRxiv2023

Chemoproteomics reveals the epoxidase enzyme for the biosynthesis of camptothecin precursor strictosamide epoxide

Camptothecin and its derivatives are the third largest anticancer drugs in the world market, mainly used to treat malignant tumors such as lung, colon and cervical cancer. Camptothecin was firstly discovered in Camptotheca acuminate and extracted mainly from C. acuminate and Nothapodytes nimmoniana for medicine production (Sadre et al. 2016). However, the overharvesting of C. acuminate and N. nimmoniana has greatly reduced their populations in nature, which are currently listed as the second protected plants in China and India. It is estimated there would be 20 million new cancer cases in 2025 all over the world, meeting the growing demand for camptothecin and other anti-cancer drugs has become a daunting challenge (Seca et al. 2018). In this study we tried to elucidate the unknown biosynthetic pathway from strictosamide 1 to strictosamide epoxide 2 by unearthing the candidate enzymes from the proteome of plant Ophiorrhiza pumila using the chemoproteomic strategy.

plant biology↗

bioRxiv2022

Control becomes habitual early on when learning a novel motor skill

When people perform the same task repeatedly, their behavior becomes habitual, or inflexible to changes in the goals or structure of a task. While habits have been hypothesized to be a key aspect of motor skill acquisition, there has been little empirical work investigating the relationship between skills and habits. To better understand this relationship, we examined whether and when peoples behavior would become habitual as they learned a challenging new motor skill. After up to ten days of practice, we altered the structure of the task to assess whether participants would flexibly adjust their behavior or habitually persist in performing the task the way they originally learned. We found that participants behavior became habitual early in practice--after only two days--at which point they were still relatively unskilled. These data demonstrate that motor skills become habitual after relatively little training, but can nevertheless further improve with practice.

neuroscience↗

bioRxiv2021

De novo motor learning of a bimanual control task over multiple days of practice

Although much research on motor learning has focused on how we adapt our movements to maintain performance in the face of imposed perturbations, in many cases we must learn new skills from scratch, or de novo. In comparison to adaptation, relatively little is known about de novo learning. In part, this is because learning a new skill can involve many challenges, including learning to recognize new patterns of sensory input and generate new patterns of motor output. However, even with familiar sensory cues and well-practiced movements, the problem of quickly selecting the appropriate actions in response to the current state is challenging. Here, we devised a bimanual hand-to-cursor mapping which isolates this control problem. We find that participants initially struggled to control the cursor under this bimanual mapping, despite explicit knowledge of the mapping. Performance improved steadily over multiple days of practice, however. Participants exhibited no aftereffects when reverting to a veridical cursor, confirming that participants learned the new task de novo, rather than through adaptation. Corrective responses to mid-movement perturbations of the target were initially weak, but with practice, participants gradually became able to respond rapidly and robustly to these perturbations. After four days of practice, participants behavior under the bimanual mapping almost matched performance with a veridically mapped cursor. However, there remained a small but persistent difference in performance level. Our findings illustrate the dynamics and limitations of learning a novel controller and introduce a promising paradigm for tractably investigating this aspect of motor skill learning.

neuroscience↗

bioRxiv2020

De novo learning versus adaptation of continuous control in a manual tracking task

How do people learn to perform tasks that require continuous adjustments of motor output, like riding a bicycle? People rely heavily on cognitive strategies when learning discrete movement tasks, but such time-consuming strategies are infeasible in continuous control tasks that demand rapid responses to ongoing sensory feedback. To understand how people can learn to perform such tasks without the benefit of cognitive strategies, we imposed a rotation/mirror reversal of visual feedback while participants performed a continuous tracking task. We analyzed behavior using a system identification approach which revealed two qualitatively different components of learning: adaptation of a baseline controller and formation of a new, task-specific continuous controller. These components exhibited different signatures in the frequency domain and were differentially engaged under the rotation/mirror reversal. Our results demonstrate that people can rapidly build a new continuous controller de novo and can simultaneously deploy this process with adaptation of an existing controller.

neuroscience↗