23Alternative microbial hosts have been engineered as biocatalysts for butanol biosynthesis. 24The butanol synthetic pathway of Clostridium acetobutylicum was first re-constructed in 25

Methamphetamine affects the hippocampus, a brain region crucial for learning and memory, as well as relapse to drug seeking. Rats self-administered methamphetamine for 1 h twice weekly (intermittent-short-I-ShA), 1 h daily (limited-short-ShA), or 6 h daily (extended-long-LgA) for 22 sessions. After 22 sessions, rats from each access group were withdrawn from self-administration and underwent spatial memory (Y-maze) and working memory (T-maze) tests followed by extinction and reinstatement to methamphetamine seeking or received one intraperitoneal injection of 5-bromo-2'-deoxyuridine (BrdU) to label progenitors in the hippocampal subgranular zone (SGZ) during the synthesis phase. Two-hour-old and 28-day-old surviving BrdU-immunoreactive cells were quantified. I-ShA rats performed better on the Y-maze and had a greater number of 2-h-old SGZ BrdU cells than nondrug controls. LgA rats, but not ShA rats, performed worse on the Y- and T-maze and had a fewer number of 2-h-old SGZ BrdU cells than nondrug and I-ShA rats, suggesting that new hippocampal progenitors, decreased by methamphetamine, were correlated with impairment in the acquisition of new spatial cues. Analyses of addiction-related behaviors after withdrawal and extinction training revealed methamphetamine-primed reinstatement of methamphetamine-seeking behavior in all three groups (I-ShA, ShA, and LgA), and this effect was enhanced in LgA rats compared with I-ShA and ShA rats. Protracted withdrawal from self-administration enhanced the survival of SGZ BrdU cells, and methamphetamine seeking during protracted withdrawal enhanced Fos expression in the dentate gyrus and medial prefrontal cortex in LgA rats to a greater extent than in ShA and I-ShA rats. These results indicate that changes in the levels of the proliferation and survival of hippocampal neural progenitors and neuronal activation of hippocampal granule cells predict the effects of methamphetamine self-administration (limited vs extended access) on cognitive performance and relapse to drug seeking and may contribute to the impairments that perpetuate the addiction cycle.

The functional reconstruction of acetoin and meso-2,3-butanediol (meso-2,3-BD) biosynthetic pathways in Escherichia coli have been explored systematically. Pathway construction involved the in vivo screening of prospective pathway isozymes of yeast and bacterial origin. After substantial engineering of the host background to increase pyruvate availability, E. coli YYC202(DE3) ldhA − ilvC − expressing ilvBN from E. coli and aldB from L. lactis (encoding acetolactate synthase and acetolactate decarboxylase activities, respectively) was able to produce up to 870 mg/L acetoin, with no coproduction of diacetyl observed. These strains were also found to produce small quantities of meso-2,3-BD, suggesting the existence of endogenous 2,3-BD dehydrogenase activity. Finally, the coexpression of bdh1 from S. cerevisiae, encoding 2,3-BD dehydrogenase, in this strain resulted in the production of up to 1120 mg/L meso-2,3-BD, with glucose a yield of 0.29 g/g. While disruption of the native lactate biosynthesis pathway increased pyruvate precursor availability to this strain, increased availability of NADH for acetoin reduction to meso-2,3-BD was found to be the most important consequence of ldhA deletion.

We investigated whether prior exposure to chronic wheel running (WR) alters maladaptive patterns of excessive and escalating methamphetamine intake under extended access conditions, and intravenous methamphetamine self-administration-induced neurotoxicity. Adult rats were given access to WR or no wheel (sedentary) in their home cage for 6 weeks. A set of WR rats were injected with 5-bromo-2′-deoxyuridine (BrdU) to determine WR-induced changes in proliferation (2-h old) and survival (28-day old) of hippocampal progenitors. Another set of WR rats were withdrawn (WRw) or continued (WRc) to have access to running wheels in their home cages during self-administration days. Following self-administration [6 h/day], rats were tested on the progressive ratio (PR) schedule. Following PR, BrdU was injected to determine levels of proliferating progenitors (2-h old). WRc rats self-administered significantly less methamphetamine than sedentary rats during acquisition and escalation sessions, and demonstrated reduced motivation for methamphetamine seeking. Methamphetamine reduced daily running activity of WRc rats compared with that of pre-methamphetamine days. WRw rats self-administered significantly more methamphetamine than sedentary rats during acquisition, an effect that was not observed during escalation and PR sessions. WR-induced beneficial effects on methamphetamine self-administration were not attributable to neuroplasticity effects in the hippocampus and medial prefrontal cortex, but were attributable to WR-induced inhibition of methamphetamine-induced increases in the number of neuronal nitric oxide synthase expressing neurons and apoptosis in the nucleus accumbens shell. Our results demonstrate that WR prevents methamphetamine-induced damage to forebrain neurons to provide a beneficial effect on drug-taking behavior. Importantly, WR-induced neuroprotective effects are transient and continued WR activity is necessary to prevent compulsive methamphetamine intake.