Nonelectroactive clostridium obtains extracellular electron transfer-capability after forming chimera with Geobacter.

Extracellular electron transfer (EET) of microorganisms is a major driver of the microbial growth and metabolism, including reactions involved in the cycling of C, N, and Fe in anaerobic environments such as soils and sediments. Understanding the mechanisms of EET, as well as knowing which organisms are EET-capable (or can become so) is fundamental to electromicrobiology and geomicrobiology. In general, Gram-positive bacteria very seldomly perform EET due to their thick non-conductive cell wall. Here, we report that a Gram-positive Clostridium intestinale (C.i) attained EET-capability for ethanol metabolism only after forming chimera with electroactive Geobacter sulfurreducens (G.s). Mechanism analyses demonstrated that the EET was possible after the cell fusion of the two species was achieved. Under these conditions, the ethanol metabolism pathway of C.i was integrated by the EET pathway of G.s, by which achieved the oxidation of ethanol for the subsequent reduction of extracellular electron acceptors in the coculture. Our study displays a new approach to perform EET for Gram-positive bacteria via recruiting the EET pathway of an electroactive bacterium, which suggests a previously unanticipated prevalence of EET in the microbial world. These findings also provide new perspectives to understand the energetic coupling between bacterial species and the ecology of interspecies mutualisms.

[Treatment option for unexplained primary infertility following failed intrauterine insemination].

OBJECTIVE: To determine an optimal insemination technique for unexplained infertility patients undergoing IVF or ICSI following failed intrauterine insemination (IUI). METHODS: Sixty-five cycles of 61 patients with failed IUI were divided into four groups: Group A (37 cycles of IVF), Group B (19 cycles of ICSI), Group C (4 cycles of IVF and ICSI: half and half), Group D (5 cycles of ICSI after failed IVF). The conventional IVF cycles were defined as Group E (37 cycles), and the conventional ICSI cycles defined as Group F (24 cycles). The fertilization rate, completely failed fertilization rate, high quality embryo rate, clinical pregnancy rate and the implantation rate were compared among all the groups. RESULTS: There were statistically significant differences in the fertilization rate, completely failed fertilization rate between Groups A and E (55.4% vs 72.8%, P < 0.05; 21.6% vs 0%, P < 0.005), and Groups A and B (55.4% vs 68.4%, P < 0.05; 21.6% vs 0%, P < 0.01). In Group D, there was statistically significant difference in the fertilization rate between IVF cycles and ICSI cycles (12.2% vs 74.2%, P < 0.005). CONCLUSION: The present study demonstrates that there may be 20% of totally failed fertilization in IVF cycles with unexplained primary infertility following failed IUI, and ICSI treatment can increase fertilization rate and avoid complete fertilization failure.

[In vitro maturation, fertilization and embryo transfer of human immature oocyte].

OBJECTIVE: To try a new method for treating infertile women by in vitro maturation technique. METHODS: To set up in vitro maturation (IVM) program, including stimulating regimen, oocyte retrieval technique, and culture system of the immature oocytes with the medium consisted of essential supplements and human mature follicular fluid. IVM was performed in 30 infertile patients (35 cycles), (1) with polycystic ovary syndrome (POCS) (14/30), (2) ovary hyperstimulation syndrome (OHSS) in the previous stimulating cycles (6/30), and (3) retardation of the oocyte growth in conventional IVF cycles (10/30). RESULTS: Totally 203 oocytes were obtained, with a mean of 5.8 oocytes each cycle. First polar bodies were observed in 156 oocytes, maturation rate was 76.8%. There were 120 oocytes getting into pronucleus stage, normal fertilization rate was 76.9%. Embryo transfer was performed in 33 cycles. Eight pregnancies were established, pregnancy rate was 24%. Five patients have delivered 7 healthy babies. CONCLUSIONS: The result of our study indicated that IVM is one of the new assisted reproductive technologies for the infertile women with PCOS, poor response to stimulation and the history of OHSS. Human mature follicular fluid would be an ideal component in the maturation medium for oocyte maturation in vitro and provides a much simplified and practical method for clinical use.