Biology subjects

Bustos, C.

Publications and source records attributed to Bustos, C..

3 recordsLinked to original sources

bioRxiv2024

Formate from THF-C1 metabolism induces the AOX1 promoter in formate dehydrogenase-deficient Pichia pastoris

In Pichia pastoris (Komagataella phaffii), formate is a recognized alternative inducer to methanol for expression systems based on the AOX1 promoter (pAOX1). By disrupting the formate dehydrogenase encoding FDH1 gene, we converted such a system into a self-induced one, as adding any inducer in the culture medium is no longer requested for pAOX1 induction. In cells, formate is generated from serine through the THF-C1 metabolism, and it cannot be converted into carbon dioxide in an fdh1{Delta} strain. Under non-repressive culture conditions, such as on sorbitol, the intracellular formate generated from the THF-C1 metabolism is sufficient to induce pAOX1 and initiate protein synthesis. This was evidenced for two model proteins, namely intracellular eGFP and secreted CalB lipase from C. antarctica. Similar protein productivities were obtained for an fdh1{Delta} strain on sorbitol and a non-disrupted strain on sorbitol-methanol. Considering a P. pastoris fdh1{Delta} strain as a workhorse for recombinant protein synthesis paves the way for the further development of methanol-free processes in P. pastoris.

microbiology↗

bioRxiv2024

Neural correlates in the time course of inferences: costs and benefits for less-skilled readers at university level.

Inferences are an indicator of a greater reading comprehension, as they imply a combination of implicit and explicit information that usually combines a textual representation with background knowledge of the reader. The aim of this study is to explore the costs and benefits of the time course of inferences in university students with reading comprehension difficulties at 3 stages during a narration. The method used was the event-related potential (ERP) technique in order to register the brain activity of 63 teaching program students while they read familiar, less-familiar and neutral stories. Results show a slow negativity potential component with greater negativity in words coming from familiar contexts when compared to less familiar and neutral ones in the first locus; an N400 component and a Post-N400 component in the second locus, reflecting greater negativity in familiar contexts when compared to less-familiar ones; and, lastly, through the use of a lexical decision task, FN400 and N400 components were found in the third locus, especially for pseudowords. These results are interpreted as a preferably bottom-up processing, which is characterized by lexical access difficulties in less-skilled readers.

neuroscience↗

bioRxiv2023

Ivermectin resistance in dung beetles exposed for multiple generations

Ivermectin is an antiparasitic drug commonly used in cattle, that is excreted in dung, causing lethal and sub-lethal effects on coprophagous non-target fauna. Given that cattle parasites generate resistance to ivermectin, farmers have increased the used doses, with a consequent threat to wild fauna. The dung beetle species Euoniticellus intermedius provides ecosystem services by burying dung in cattle pastures, however it is highly threatened by ivermectin. Here we experimentally tested whether E. intermedius generates resistance against ivermectin after being exposed for several generations to a sublethal dose. We generated two laboratory lines where beetles were exposed to either ivermectin-treated or ivermectin-free dung for 18 generations. We compared reproductive success (total brood balls, emerged beetles, proportion emerged and days to emergence) of beetles from both lines across generations. Additionally, for each line, we carried-out toxicity experiments with increasing ivermectin concentrations to determine if sensitivity to ivermectin was reduced after some generations of exposure (i. e. if beetles acquired ivermectin resistance by means of transgenerational effects). Our results show that dung beetles do not generate resistance to ivermectin after 18 generations of continuous exposure and quantitative genetic analyses show low genetic variation in response to ivermectin across generations. Together, these results indicate low potential for adaptation to the contaminant in the short term. Although we cannot exclude that adaptation could occur in the long term, our results and comparative evidence in other insects indicate that dung beetles, and probably other species, are at risk of extinction in ivermectin-contaminated pastures unless they are pre-adapted to tolerate high ivermectin concentrations.

ecology↗