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The rice root-knot nematode Meloidogyne graminicola is increasingly widely distributed in China and has had a severe incidence in Hunan Province. It is thus necessary to investigate its population dynamics in paddy fields. This study was conducted to ascertain the effect of direct-seeded rice agroecosystems on the population dynamics of M. graminicola and root gall development in rice. The results indicated that the population density of M. graminicola in soil was markedly influenced by the agroecosystem, rainfall and temperature. The population density of M. graminicola J2, and eggs in the soil and root galls, were significantly larger in the dry aerobic rice agroecosystem and in the rain-fed upland agroecosystem than in the lowland double-rice cropping sequence agroecosystem. As it can affect soil moisture rainfall was the key factor affecting the density of nematodes in both the rain-fed upland agroecosystem and the dry aerobic rice agroecosystem. Field flooding was still an effective way to reduce the population density of M. graminicola. In addition, we observed that M. graminicola can lay eggs outside rice roots under laboratory conditions. Therefore, we propose a hypothesis that M. graminicola lays egg masses within roots when the soil moisture is high, but lays eggs outside when the soil moisture is suitable. By clarifying the population dynamics of M. graminicola in different types of direct-seeded rice agroecosystems, this study is conducive to controlling rice root-knot nematodes.

To study the pose state and coordinate transformation of different tool positions by establishing the interpolation equations,and obtain the mathematical model between the coordinate systems,and verify the validity according to the simulation results. Based on the five-axis CNC machine tool,the interpolation equations are established,and the interpolation models of different machining directions are analyzed; using the homogeneous matrix transformation method and the numerical assignment inverse algorithm,combined with the classical DH method in robotics,the mathematical model between the coordinate systems is established,and the pose state of the machine tool holder is realized,and the coordinate values of each axis motion are obtained.And kinematics equations; spatial trajectory planning and kinematics simulation using MATALB and ADAMS. Through simulation analysis,the results show that the pose and stability of the dynamic tool holder during the machining process meet the requirements of the previous design,and the overall motion performance of the machine tool is good. Conclusion: The tool is moving in accordance with the trajectory law of the design,which verifies the validity and rationality of the method.

The meiotic entry of undifferentiated germ cells is sexually specific and strictly regulated by the testicular or ovarian environment. Germline stem cells with a set of abnormal sex chromosomes and associated autosomes undergo defective meiotic processes and are eventually eliminated by yet to be defined post‐transcriptional modifications. Herein, we report the role of gsdf, a member of BMP/TGFβ family uniquely found in teleost, in the regulation of meiotic entry in medaka (Oryzias latipes) via analyses of gametogenesis in gsdf‐deficient XX and XY gonads in comparison with their wild‐type siblings. Several differentially expressed genes, including the FKB506‐binding protein 7 (fkbp7), were significantly upregulated in pubertal gsdf‐deficient gonads. The increase in alternative pre‐mRNA isoforms of meiotic synaptonemal complex gene sycp3 was visualized using Integrative Genomics Viewer and confirmed by real‐time qPCR. Nevertheless, immunofluorescence analysis showed that Sycp3 protein products reduced significantly in gsdf‐deficient XY oocytes. Transmission electron microscope observations showed that normal synchronous cysts were replaced by asynchronous cysts in gsdf‐deficient testis. Breeding experiments showed that the sex ratio deviation of gsdf−/− XY gametes in a non‐Mendelian manner might be due to the non‐segregation of XY chromosomes. Taken together, our results suggest that gsdf plays a role in the proper execution of cytoplasmic and nuclear events through receptor Smad phosphorylation and Sycp3 dephosphorylation to coordinate medaka gametogenesis, including sex‐specific mitotic divisions and meiotic recombination. [ABSTRACT FROM AUTHOR]