Leaf gall polymorphism and molecular phylogeny of a new Bruggmanniella species (Diptera: Cecidomyiidae: Asphondyliini) associated with Litsea acuminata (Lauraceae) in Taiwan,with ecological comparisons and a species description

Two types of cecidomyiid leaf galls, cup‐shaped and umbrella‐shaped, occur on Litsea acuminata (Lauraceae) in Taiwan. Based on the concept of gall shapes as “extended phenotypes” of gall inducers, these two types could be induced by different gall midge species. However, galls with intermediate shapes between the two types were recently discovered, which implies that possible genetic exchanges occur between the gall inducers of both types. To clarify the taxonomic status of gall midges responsible for the two types of galls on L. acuminata, we undertook taxonomic, molecular phylogenetic and ecological studies. Our findings show that the two gall types are induced by the same Bruggmanniella species and the species is new to science. We describe the species forming this range of galls as Bruggmanniella litseae sp. n. , and compare their geographical distribution, galling position and morphometry. Based on our results, a possible evolutionary scenario of B. litseae sp. n. is discussed.     

强化类球红细菌辅因子NADPH再生以提高法尼醇的产量

法尼醇(Farnesol,FOH)是由焦磷酸异戊烯基(IPP)和焦磷酸二甲基烯丙基(DMAPP)合成的法尼酰基焦磷酸盐(FPP)去焦磷酸化作用生成的。在类球红细菌中IPP和DMAPP是由MEP途径生成,而完整的MEP途径需要消耗大量的辅因子NADPH,增加胞内NADPH的量有可能强化FOH的合成。文中从增加NADPH的生成和降低NADPH的消耗这两个策略出发,分别干扰了编码6-磷酸葡萄糖异构酶基因(pgi)和谷氨酸脱氢酶基因(gdhA)的表达,同时强化了磷酸戊糖途径中6-葡萄糖磷酸脱氢酶基因(zwf)和6-葡萄糖酸磷酸脱氢酶基因(gnd)的表达。实验结果表明,经改造的菌株NADPH含量显著增加,干扰菌株中菌株RSpgii的产量较高,为3.91 mg/g,在过表达的菌株中同时过表达zwf和gnd基因的重组菌株(RSzg)的FOH产量提高到了3.43 mg/g。为了获得FOH产量更高的菌株,以RSpgii为出发菌株,分别与zwf和gnd组合调控,获得的菌株RSzgpi的产量达到了最高量为4.48 mg/g,是出发菌株RS-GY2产率的2.24倍。     

黄土区土质与土石质塿土堆积体水力侵蚀过程差异

利用室内模拟降雨试验,研究了不同雨强及坡度条件下黄土区土质(不含砾石)与土石质(砾石质量分数30%)塿土堆积体的水动力学特征、侵蚀特征及侵蚀动力机制的差异。结果表明: 砾石存在改变了堆积体坡面的水动力学特性,与土质坡面相比,土石质坡面的流速、弗汝德数、单位径流功率和过水断面单位能分别减少1.7%～49.7%、6.7%～60.6%、2.0%～44.6%和1.0%～26.7%;曼宁糙率系数、径流剪切力分别增加6.2%～169.4%、5.7%～79.3%。2.0、2.5 mm·min^-1雨强下,土石质坡面侵蚀速率较土质坡面降低26.2%～89.9%,砾石的减沙效益显著。2种堆积体的侵蚀速率与水动力学参数间均可用线性函数拟合,与土质坡面相比,土石质坡面的可蚀性参数均降低,降幅为56.1%～73.3%;而临界水动力学参数中径流剪切力增加11.1%,径流功率、单位径流功率和过水断面单位能分别减少25.4%、64.0%和5.0%。砾石的存在一定程度上控制了工程堆积体坡面降雨侵蚀过程。     

软枣猕猴桃控制授粉对果实和种子的影响

为了研究软枣猕猴桃授粉规律,以11年生软枣猕猴桃紫果3号为试验材料,设置剪留花柱数量为0、2、5、8、11、14、17和23(全留对照组)共8个处理。人工授粉,收获后调查测定其单果重、坐果率、果型指数、果实可溶性固形物含量和果实内含种子数量。结果表明:随着授粉柱头数的增加,单果重等主要指标相应增加;当授粉柱头数增至为8时,其果型指数和果实可溶性固形物含量与对照全留柱头23相比差异不明显;当授粉柱头数增至为11时,其单果重、坐果率和果实内含种子数量与对照全留柱头23相比差异不明显。据此软枣猕猴桃充分授粉的数量级指标为11,当授粉柱头数小于11时,产量降低、品质下降;当授粉柱头大于11时,浪费花粉。生产上可利用猕猴桃精准充分授粉技术,节约使用花粉或减少果园雄株数量,以提高生产效率。     

白云山国家森林公园不同人为干扰强度的群落冠层结构和光照特征

为探究森林冠层结构与林下光照的变化规律及其相关性,在河南省白云山国家森林公园选取人工林、择伐林、皆伐林和老龄林建立四块面积为1 hm²（100 m×100 m）的固定监测样地,利用半球面影像技术获取冠层结构及林下光照数据。研究发现：1）随着人为干扰强度降低,冠层覆盖度与叶面积指数呈增加趋势,林下散射辐射与直接辐射呈减少趋势;2）择伐林冠层覆盖度与叶面积指数最大,平均叶倾角与透光比最小,林下光照（直接辐射、散射辐射）与冠层覆盖度和叶面积指数都呈显著负相关,林下散射辐射与冠层覆盖度和叶面积指数的负相关关系最强;3）处于不同干扰强度的群落由于冠层结构的差异,形成了不同群落内特定的光照环境。研究结果丰富了暖温带-亚热带生态过渡区森林冠层结构与林下光照动态变化研究资料,同时也为该区域森林的恢复与重建等提供科学的依据。     

Narrow H3K4me2 is required for chicken PGC formation

The development of primordial germ cells (PGCs) undergoes epigenetic modifications. The study of histone methylation in regulating PGCs is beneficial to understand the development and differentiation mechanism of germ stem cells. Notably, it provides a theoretical basis for directed induction and mass acquisition in vitro. However, little is known about the regulation of PGC formation by histone methylation. Here, we found the high enrichment of H3K4me2 in the blastoderm, genital ridges, and testis. Chromatin immunoprecipitation sequencing was performed and the results revealed that genomic H3K4me2 is dynamic in embryonic stem cells, PGCs, and spermatogonial stem cells. This trend was consistent with the H3K4me2 enrichment in the gene promoter region. Additionally, narrow region triggered PGC‐related genes (Bmp4, Wnt5a, and Tcf7l2) and signaling pathways (Wnt and transforming growth factor‐β). After knocking down histone methylase Mll2 in vitro and vivo, the level of H3K4me2 decreased, inhibiting Cvh and Blimp1 expression, then repressing the formation of PGCs. Taken together, our study revealed the whole genome map of H3K4me2 in the formation of PGCs, contributing to improve the epigenetic study in PGC formation and providing materials for bird gene editing and rescue of endangered birds.