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The Chinese mitten crab (Eriocheir sinensis) is a seasonally breeding species and its reproductive system comprises paired symmetrical structures: testes, vasa deferentia, seminal vesicles, accessory glands and ejaculatory ducts. Histological examination of the testis of mature males reveals regression of the gonads and inhibition of the process of spermatogenesis during December to April of the following year, the regeneration of the gonads during June to July and the occurrence of the highest level of spermatogenesis during August to October. Microscopic assessments and hematoxylin and eosin (H&E) staining were used to describe all spermatogenic stages (spermatogonia, primary and secondary spermatocytes, spermatids and spermatozoids). To observe the morphological changes during spermiogenesis, we successfully initiated primary cell culture using testis tissue of E. sinensis, which will lay a solid foundation for further work on the immortalization of crab cells. During the interaction between the sperm and oocyte, the fertilizing spermatozoon must undergo a series of terminal morphological changes, called the acrosome reaction (AR). This study also provides a detailed description of the structural alterations of the acrosome reaction of E. sinensis. The acrosome complex and cup-shaped nucleus are located at the anterior and posterior of the spermatozoon, respectively. Male germ cell development involves a tightly controlled sequence of differentiation switches. The purpose of this study is to increase our knowledge of the morphological alterations during spermatogenesis and the acrosome reaction, whose changes are a fundamental requirement for fertilization of E. sinensis.

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In this study, the mineral-weathering bacterium Pseudomonas azotoformans F77, which was isolated from the soil of a debris flow area, was evaluated for its weathering activity under direct contact with biotite or without contact. Then, biotite-weathering behaviors of strain F77, mutants that had been created by deleting the gcd and adh genes (which are involved in gluconic acid metabolism and pilus formation, respectively), and the double mutant F77ΔgcdΔadh were compared. The relative gene expression levels of F77 and its mutants F77Δgcd and F77Δadh were also analyzed in the presence of biotite. Direct contact with biotite increased Fe and Al release from the mineral in the presence of F77. All strains had similar abilities to release Fe and Al from the mineral except for F77Δgcd and F77Δadh. Mobilized Fe and Al concentrations were decreased by up to 72, 26, and 87% in the presence of F77Δgcd, F77Δadh, and F77ΔgcdΔadh, respectively, compared to levels observed in the presence of F77 during the mineral-weathering process. Gluconic acid production was decreased for F77Δgcd and F77ΔgcdΔadh, while decreased cell attachment on the mineral surface was observed for F77Δadh, compared to findings for F77. The F77 genes involved in pilus formation and gluconic acid metabolism showed increased expression levels in the presence of biotite. The results of this study showed important roles for the genes involved in gluconic acid metabolism and pilus formation in mineral weathering by F77 and demonstrated the distinctive effect of these genes on mineral weathering by F77. IMPORTANCE Bacteria play important roles in mineral weathering and soil formation, although the molecular mechanisms underlying the interactions between bacteria and silicate minerals are poorly understood. In this study, the interactions between biotite and the highly effective mineral-weathering bacterium P. azotoformans F77 were characterized. Our results showed that the genes involved in gluconic acid metabolism and pilus formation play important roles in mineral weathering by F77. The presence of biotite could promote the expression of these genes in F77, and a distinctive effect of these genes on mineral weathering by F77 was observed in this study. Our results provide new knowledge and promote better understanding regarding the interaction between silicate minerals and mineral-weathering bacteria, as well as the molecular mechanisms involved in these processes.

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Composition optimization, structural design, and introduction of external magnetic fields into the catalytic process can remarkably improve the oxygen evolution reaction (OER) performance of a catalyst. NiFe2O4@(Ni, Fe)S/P materials with a heterogeneous core–shell structure were prepared by the sulfide/phosphorus method based on spinel-structured NiFe2O4 nanomicrospheres. After the sulfide/phosphorus treatment, not only the intrinsic activity of the material and the active surface area were increased but also the charge transfer resistance was reduced due to the internal electric field. The overpotential of NiFe2O4@(Ni, Fe)P at 10 mA cm–2 (iR correction), Tafel slope, and charge transfer resistance were 261 mV, 42 mV dec–1, and 3.163 Ω, respectively. With an alternating magnetic field, the overpotential of NiFe2O4@(Ni, Fe)P at 10 mA cm–2 (without iR correction) declined by 45.5% from 323 mV (0 mT) to 176 mV (4.320 mT). Such enhancement of performance is primarily accounted for the enrichment of the reactive ion OH– on the electrode surface induced by the inductive electric potential derived from the Faraday induction effect of the AMF. This condition increased the electrode potential and thus the charge transfer rate on the one hand and weakened the diffusion of the active substance from the electrolyte to the electrode surface on the other hand. The OER process was dominantly controlled by the charge transfer process under low current conditions. A fast charge transfer rate boosted the OER performance of the catalyst. At high currents, diffusion exerted a significant effect on the OER process and low OH– diffusion rates would lead to a decrease in the OER performance of the catalyst.