Enhancing nosiheptide production in Streptomyces actuosus by heterologous expression of haemoprotein from Sinorhizobium meliloti.

UNLABELLED: Oxygen deficiency is a critical limiting factor for nosiheptide production in Streptomyces actuosus during fermentation. To alleviate oxygen limitation and enhance the yield of nosiheptide, haemoprotein from Sinorhizobium meliloti (SmHb) was overexpressed in S. actuosus with overexpression of haemoglobin from Vitreoscilla (VHb) as a positive control. The expression of SmHb and VHb in S. actuosus was confirmed by SDS-PAGE and CO-difference spectra analysis. The results showed that S. actuosus recombinant strain with SmHb expression had higher nosiheptide production (increased by 151%) than the wild strain (WT) under the low aeration conditions, which was similar with S. actuosus mutant strain with VHb expression. Furthermore, two copies of SmfHb gene were integrated in S. actuosus, which further increased the nosiheptide production by approx. 1·9-fold compared with original strain, and final nosiheptide yield was up to 2352 µg ml(-1) . These results suggested that engineering of SmHb expression could be used as an efficient method for constructing a high nosiheptide-accumulating strain. SIGNIFICANCE AND IMPACT OF THE STUDY: The significant improvement of nosiheptide production was found in recombinant strain with overexpressed sm gene. And further improvement was obtained in the two copies of sm overexpressing strain. These results suggested that engineering of SmHb expression could be used as an efficient method for constructing a high nosiheptide-accumulating strain.

Is the optimal intervention policy UC superior to the suboptimal policy MFPT over inferred probabilistic Boolean network models?

A salient problem in translational genomics is the use of gene regulatory networks to determine therapeutic intervention strategies. Theoretically, in a complete network, the optimal policy performs better than the suboptimal policy. However, this theory may not hold if we intervene in a system based on a control policy derived from imprecise inferred networks, especially in the small-sample scenario. In this paper, we compare the performance of the unconstrained (UC) policy with that of the mean-first-passage-time (MFPT) policy in terms of the quality of the determined control gene and the effectiveness of the policy. Our simulation results reveal that the quality of the control gene determined by the robust MFPT policy is better in the small-sample scenario, whereas the sensitive UC policy performs better in the large-sample scenario. Furthermore, given the same control gene, the MFPT policy is more efficient than the UC policy for the small-sample scenario. Owing to these two features, the MFPT policy performs better in the small-sample scenario and the UC policy performs better only in the large-sample scenario. Additionally, using a relatively complex model (gene number N is more than 1) is beneficial for the intervention process, especially for the sensitive UC policy.

Deliver protein across bio-barriers via hexa-histidine metal assemblies for therapy: a case in corneal neovascularization model.

Because of their high specificity and low side effects, protein drugs possess a substantial global market. However, the low bioavailability of protein is still a major obstacle to their expanded applications, which is expected to be answered with proper protein formulations. Taking corneal neovascularization (CNV) as an example, we demonstrated a co-assembled system of hexa-histidine and Ava (Avastin) with metal ions (HmA@Ava) could cross the cornea, the most important bio-barrier during the treatment of most diseases of the anterior segment in clinics. We found that the nanosized HmA@Ava efficiently encapsulated Ava with impressive loading capacity without destroying the bioactivity of Ava and assisted Ava penetration through the corneal barriers to effectively inhibit CNV development in an alkali burn rat model with sustained and pH-dependent Ava release. Our results suggested that the co-assembled strategy of protein and HmA is a proper formulation to protein drugs, with promising penetration ability to deliver protein across bio-barriers, which could open a path for topical administration of protein drugs for treatment of various ocular diseases and hold enormous potential for delivery of therapeutic proteins not only for ocular diseases but also for other diseases that require protein treatment.

Response inhibition of cigarette-related cues in male light smokers: behavioral evidence using a two-choice oddball paradigm.

Behavioral inhibitory control has been shown to play an important role in a variety of addictive behaviors. A number of studies involving the use of Go/NoGo and stop-signal paradigms have shown that smokers have reduced response inhibition for cigarette-related cues. However, it is not known whether male light smokers' response inhibition for cigarette-related cues is lower than that of non-smokers in the two-choice oddball paradigm. The objective of the current study was to provide further behavioral evidence of male light smokers' impaired response inhibition for cigarette-related cues, using the two-choice oddball paradigm. Sixty-two male students (31 smokers, 31 non-smokers), who were recruited via an advertisement, took part in this two-choice oddball experiment. Cigarette-related pictures (deviant stimuli) and pictures unrelated to cigarettes (standard stimuli) were used. Response inhibition for cigarette-related cues was measured by comparing accuracy (ACC) and reaction time (RT) for deviant and standard stimuli in the two groups of subjects. An analysis of variance (ANOVA) showed that in all the participants, ACC was significantly lower for deviant stimuli than for standard stimuli. For deviant stimuli, the RTs were significantly longer for male light smokers than for male non-smokers; however, there was no significant difference in RTs for standard stimuli. Compared to male non-smokers, male light smokers seem to have a reduced ability to inhibit responses to cigarette-related cues.

The absorption, distribution, metabolism and excretion of Riccardin D in rats.

The present study was designed to investigate the pharmacokinetics following oral and intravenous administration of Riccardin D, an anticancer drug candidate isolated from Chinese liverworts Dumortiera hirsute, in Wistar rats. An HPLC-MS/MS analytical method was developed and validated. The results demonstrated that Riccardin D's bioavailability was 13.4%, 11.4%, and 9.8% after oral administration at 20 mg/kg, 40 mg/kg, and 80 mg/kg, respectively. There was no significant difference in the elimination half-time of Riccardin D at these doses, suggesting that Riccardin D may have linear pharmacokinetic characteristics in rats. The metabolite of Riccardin D in rat was identified as the glucuronide of Riccardin D. Riccardin D showed a wide distribution in various tissues followed by a rapid elimination from most of the tissues tested. Riccardin D was found to distribute widely in the tissues 0.5 h after oral and intravenous administration. The tissue concentrations were markedly decreased 8 h and 6 h after oral and intravenous dosing, respectively. Both Riccardin D and its conjugated metabolite were detected in urine and bile samples while only Riccardin D was detected in feces. Taken together, the study provided valuable pharmacokinetic data for further drug development of Riccardin D.