Consumer-driven nutrient release to the water by a small omnivorous fish enhanced ramet production but reduced the growth rate of the submerged macrophyte Vallisneria denseserrulata (Makino) Makino

Small fish are highly associated with submerged macrophytes but may potentially hamper their growth due to nutrient excretion that stimulate growth of phytoplankton and periphyton growth. We conducted a mesocosm experiment to elucidate the effects of the small omnivore Chinese bitterling Acheilognathus macropterus on the growth of phytoplankton, periphyton and the submerged macrophyte Vallisneria denseserrulata. The treatments were fishless as well as low (LF) and high (HF) fish density. We found that the concentrations of nutrients and the phytoplankton biomass increased substantially in both fish treatments, leading to a significantly higher light attenuation compared with the control. Moreover, bitterling substantially enhanced the biomass of periphyton on plant leaves. Consequently, the relative growth rate (RGR) of V. denseserrulata was significantly suppressed in HF, while RGR in the LF treatment did not differ significantly from the controls. However, the bitterling also stimulated the ramet production of V. denseserrulata, significantly. Our results indicate that Chinese bitterling reduce the RGR of V. denseserrulata under high fish density condition. Therefore, the density of Chinese bitterling should be kept low in order to reduce the negative effects of the fish on the RGR of submerged macrophytes (e.g. V. denseserrulata), when restoring lakes by plant transplantation.

     

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.     

2018年河南省肠道病毒环境监测结果分析

通过对2018年河南省环境污水中肠道病毒(Enterovirus,EV)的持续监测,了解河南省环境污水中脊灰病毒(PV)和非脊灰肠道病毒(NPEV)的血清型分布及流行情况.选取了河南省东、西、南、北、中部的五个城市,对每个城市有10万～30万人共同使用的下水管网的地区进行污水采样,每两个月采集1次,每次采集两份污水样品,采集持续1年,对污水样品进行浓缩,将浓缩液接种至RD细胞、L20B细胞和HEp-2细胞进行病毒分离.对病毒分离物进行VP1区核苷酸序列测定分析,采用最大似然法构建系统进化树对EV进行分子定型,并进行核苷酸相似性分析.共采集污水样品60份,分离到EV阳性毒株16株(26.67％),分别为8株CVB5、3株E7、3株E11、1株CVB5+E11混合株;1株PVIII;环境监测标本与急性弛缓性麻痹(Acute flaccid paralysis,AFP)病例标本,在济源市和周口市分离到的CVB5比例有一致性,郑州市和济源市分离到的E7比例有一致性;污水标本中阳性毒株的检出时间要早于AFP病例标本中同种毒株型别的检出时间1～3个月.来源于AFP病例监测和环境监测的CVB5之间的核苷酸相似性为94.7％～99.6％,来源于AFP病例监测和环境监测的E7之间的核苷酸相似性为92.5％～100.0％.来源于AFP病例监测和环境监测的CVB5属于同一个基因型,E7也是同一个基因型,甚至是同一个病毒传播链.河南省2018年建立了环境监测方法,是AFP病例监测的有益的补充,也可对人类肠道病毒病流行或暴发进行预测和预警.     

广西麻鸡FOXL2基因的克隆、序列分析及在高低产蛋量卵巢中的表达

为了研究鸡FOXL2基因的结构和功能,本研究克隆了广西麻鸡FOXL2基因编码区序列,分析了其突变位点及与其他物种的同源性和进化距离,以及在高产组和低产组母鸡卵巢组织中的表达水平.结果 表明:广西麻鸡FOXL2基因的编码区长度为918 bp,共编码305个氨基酸,存在一处错义突变和两处同义突变.通过物种间的同源性分析显示,广西麻鸡FOXL2基因与原鸡(Gallus gallus)、雉鸡(Phasianus colchicus)、绿头鸭(Anas platyrhynchos)、野鸽(Columba livia)、人(Homo sapiens)、小鼠(Mus musculus)的同源性分别为99.7％、98.8％、95.1％、92.0％、75.7％、75.5％.通过种间进化树分析表明,广西麻鸡与原鸡(Gallus gallus)的亲缘关系最近,与小鼠(Mus musculus)的亲缘关系最远.FOXL2在高低产蛋量鸡卵巢中的表达水平结果显示:FOXL2基因在高产蛋组中的表达量显著高于低产蛋组中的表达量(P＜0.05).该研究结果提示鸡FOXL2的序列相对较保守,对卵巢功能的维持和提高产蛋量具有功能性作用.     

引入新型异戊二烯醇利用途径促进解脂耶氏酵母中β-胡萝卜素的合成*

目的:微生物体内异戊二烯类化合物的前体物异戊烯焦磷酸酯的天然合成路径受到严格的代谢调控,因此限制了异戊二烯类化合物的高效生物合成,而新型异戊二烯醇利用途径独立于生物体内源性代谢路径,通过在微生物中引入IUP能够进行异戊烯焦磷酸酯的大量合成,从而促进异戊二烯类化合物的大量合成。方法:在油脂酵母解脂耶氏酵母中引入IUP,强化异戊烯焦磷酸酯生物合成,促进β-胡萝卜素的高效积累。结果:通过生物信息学的方法预测IUP中两个关键蛋白酿酒酵母来源的胆碱激酶ScCK和拟南芥来源的异戊烯磷酸激酶AtIPK,均为酸性亲水性蛋白,无跨膜区和信号肽,二者都具有疏松不稳定的结构特征,显著富集于磷酸类物质的合成通路中。在解脂耶氏酵母中利用同源重组技术引入外源β-胡萝卜素合成关键基因carRP和carB,强化甲羟戊酸途径的关键基因thmgR和ggs1,使工程菌株中积累2.68 mg/L β-胡萝卜素。通过Cre-loxP系统回收基因组上的ura标签,再将IUP进一步整合到工程菌株染色体上。当培养基中含有20 mM异戊二烯醇作为底物、碳氮比为4/3且发酵96 h后,重组解脂耶氏酵母中β-胡萝卜素的产量提高到410.2 mg/L,较原始工程菌的产量提高了近200倍。结论:IUP能够促进解脂耶氏酵母中β-胡萝卜素的高效积累,为利用IUP开展β-胡萝卜素和其他异戊二烯类化合物的高效生物合成提供新思路。     

An inducible constitutive expression system in Bombyx mori mediated by phiC31 integrase

Inducible gene-expression systems play important roles in gene functional assays in the post-genome era. Streptomyces phage-derived phiC31 integrase, which mediates an irreversible site-specific cassette exchange between the phage attachment site (attP) and the bacterial attachment site (attB), provides a promising option for the construction of a controllable gene-expression system. Here, we report a phiC31 integrase-mediated promoter flip system (FLIP) for the inducible expression of target genes in silkworm (Bombyx mori). First, we constructed a FLIP reporter system, in which a BmAct4 promoter with enhanced translational efficiency was flanked by the attB and attP sites in a head-to-head orientation and further linked in a reverse orientation to a DsRed reporter gene. The coexpression of a C-terminal modified phiC31-NLS integrase carrying a simian virus 40 (SV40) nuclear localization signal (NLS) effectively flipped the BmAct4 promoter through an attB/attP exchange, thereby activating the downstream expression of DsRed in a silkworm embryo-derived cell line, BmE. Subsequently, the FLIP system, together with a system continuously expressing the phiC31-NLS integrase, was used to construct binary transgenic silkworm lines. Hybridization between FLIP and phiC31-NLS transgenic silkworm lines resulted in the successful flipping of the BmAct4 promoter, with an approximately 39% heritable transformation efficiency in silkworm offspring, leading to the constitutive and high-level expression of DsRed in silkworms, which accounted for approximately 0.81% of the silkworm pupal weight. Our successful development of the FLIP system offers an effective alternative for manipulating gene expression in silkworms and other lepidopteran species.     

Autophagy in plants: Physiological roles and post‐translational regulation

In eukaryotes, autophagy helps maintain cellular homeostasis by degrading and recycling cytoplasmic materials via a tightly regulated pathway.Over the past few decades, significant progress has been made towards understanding the physiological functions and molecular regulation of autophagy in plant cells. Increasing evidence indicates that autophagy is essential for plant responses to several developmental and environmental cues, functioning in diverse processes such as senescence, male fertility, root meristem maintenance, responses to nutrient starvation,and biotic and abiotic stress. Recent studies have demonstrated that, similar to nonplant systems,the modulation of core proteins in the plant autophagy machinery by posttranslational modifications such as phosphorylation, ubiquitination,lipidation, S-sulfhydration, S-nitrosylation, and acetylation is widely involved in the initiation and progression of autophagy. Here, we provide an overview of the physiological roles and posttranslational regulation of autophagy in plants.