Intertwined Biosynthesis of Skyrin and Rugulosin A Underlies the Formation of Cage-Structured Bisanthraquinones.

Skyrin and rugulosin A are bioactive bisanthraquinones found in many fungi, with the former suggested as a precursor of hypericin (a diversely bioactive phytochemical) and the latter characterized by its distinct cage-like structure. However, their biosynthetic pathways remain mysterious, although they have been characterized for over six decades. Here, we present the rug gene cluster that governs simultaneously the biosynthesis of skyrin and rugulosin A in Talaromyces sp. YE3016, a fungal endophyte residing in Aconitum carmichaeli. A combination of genome sequencing, gene inactivation, heterologous expression, and biotransformation tests allowed the identification of the gene function, biosynthetic precursor, and enzymatic sets involved in their molecular architecture constructions. In particular, skyrin was demonstrated to form from the 5,5'-dimerization of emodin radicals catalyzed by RugG, a cytochrome P450 monooxygenase evidenced to be potentially applicable for the (chemo)enzymatic synthesis of dimeric polyphenols. The fungal aldo-keto reductase RugH was shown to be capable of hijacking the closest skyrin precursor (CSP) immediately after the emodin radical coupling, catalyzing the ketone reduction of CSP to inactivate its tautomerization into skyrin and thus allowing for the spontaneous intramolecular Michael addition to cyclize the ketone-reduced form of CSP into rugulosin A, a representative of diverse cage-structured bisanthraquinones. Collectively, the work updates our understanding of bisanthraquinone biosynthesis and paves the way for synthetic biology accesses to skyrin, rugulosin A, and their siblings.

[An experimental study on cardiopulmonary resuscitation by cardiac massage under diaphragmatic muscle for rabbit with cardiac arrest].

OBJECTIVE: To compare the hemodynamic effect of standard-cardiopulmonary resuscitation (S-CPR) and of CPR by cardiac massage under the diaphragmatic muscle (D-CPR), and to evaluate the feasibility of D-CPR. METHODS: Twenty healthy New Zealand rabbits were randomly divided into two groups: one group receiving S-CPR (n=10) and the other group receiving D-CPR (n=10). Cardiac arrest was induced by asphyxiation at the end expiration for 8 minutes. After the hemodynamic situation was stable for 5 minutes before asphyxiation, the readings of ascending aorta systolic pressure (AOS) and diastolic pressure (AOD), transcutaneous oxygen saturation (SpO(2)), right atrial systolic pressure (RASP), right atrial diastolic pressure (RADP), and electrocardiogram were recorded consecutively to the end of the experiment . The mean arterial pressure (MAP) of ascending aorta and coronary perfusion pressure (CPP) were calculated. The rate of restoration of spontaneous circulation (ROSC) and the survival rate in a short duration of 6 hours were observed. RESULTS: Five rabbits in S-CPR group and 8 in D-CPR group were successfully resuscitated and obtained ROSC (50%, 80%, P=20.05). Six hours survival rate was 40% in S-CRP group and 50% in D-CPR group. The comparisons between the two groups on AOS, AOD, MAP and CPP respectively showed that at 1 minute and 5 minutes during resuscitation the respective variables were higher in the D-CPR group than that in the S-CPR group (all P<0.05). Compared to the hemodynamics before asphyxiation, the MAP and CPP in the D-CPR group increased 54.1% and 33.4% of basic value at 1 minute, and they were 60.0% and 41.8% at 5 minutes, while the AOS and AOD in the S-CPR group only increased by an average of 37.3% and 16.5% at 1 minute, and they were 38.5% and 17.1% at 5 minutes, respectively. After ROSC, the hemodynamic variations of the D-CPR rabbits were more stable than those of S-CPR rabbits. CONCLUSION: D-CPR can provide higher arterial pressure, cardiac output, rate of ROSC and survival rate in a short period than S-CPR can induce, so that D-CPR is superior to S-CPR.