广椭牛齿兰，中国兰科一新记录种

报道了在海南热带雨林国家公园内发现的兰科牛齿兰属中国一新记录种：广椭牛齿兰[Appendicula ovalis(Schltr.) J.J.Sm. ex Mansf.]。该种原分布于马来半岛、苏门答腊岛、爪哇岛、婆罗洲、苏拉威西岛,在形态上与国内记录的4种牛齿兰属植物均有较大差别,如茎中部具分枝、叶广椭圆形、单个花序仅着生1朵花、且唇瓣扭转具粉紫色斑块等特征。对产自海南的该种形态和生境进行了详细描述,并提供高清解剖照片。凭证标本保存于海南大学林学院教学标本馆(HUFB)。     

光周期调节光敏感核不育水稻叶片抗环血酸过氧化物酶的活性

从第二次枝梗原基分化期开始用长日照(LD)或短日照(SD)处理光敏感核不育水稻农垦58S 和常规水稻农垦58。与 SD 处理比较,LD 处理明显抑制农垦58S 和农垦58的抗坏血酸过氧化物酶(AsAPOD)的活性,对农垦58S 的 AsA POD 活性的抑制效应较之农垦58的大。随着 AsAPOD 活性下降,抗坏血酸(AsA)和丙二醛(MDA)的含量逐渐增加,AsA POD 活性与 AsA 和MDA 含量之间呈负相关。LD 抑制 ASA POD 活性和抑制幼穗发育的时间有一定的一致性。推测在 LD 处理下 AsA POD 活性下降与幼穗发育受阻有某些内在的联系。     

林蛙受精卵的表面收缩波和卵裂起动收缩

林蛙受精卵表面的大豆凝集素结合位点没有侧向运动,联在结合位点上的标记物在卵表面位置的改变应该可以反映卵表面运动。本文利用近景摄影测量术和侧向摄影法观测卵表面标记点位置的变化,得到下面的结果:1.卵裂前30—40min,整个卵表面都向预定分裂沟中心移动,表示卵表面在收缩。卵裂前15min左右,沟中心附近的卵表面开始松弛,随之是离沟较远处的卵表面松弛,显示卵表面有一个从预定分裂沟中心向四周传播的收缩波(图2—5)。如果以相邻标记点之间的距离变化作图(图6),则出现两个波,一个是松弛波,一个是收缩波。本文对卵表面究竟出现一个波还是两个波的问题进行了讨论。2.分裂沟中心附近收缩时,高程逐渐下降,基部两侧逐渐加宽(图7和图8);卵松弛时,高程增加,基部收缩。所以卵高程的变化也是从预定分裂沟中心波浪形地向四周传播的。3.卵裂沟出现前3—5 min,预定分裂沟两端开始向沟中心收缩,这是卵裂起动收缩。以后收缩范围逐渐扩大,强度亦增加,但预定分裂沟两侧的卵表面没有向预定分裂沟两端移动。这一结果支持了赤道区收缩的假说。     

枯草杆菌核糖体蛋白质突变对碱性蛋白酶基因表达的影响

用枯草杆菌体外转录-翻译偶联系统检测13种19株枯草杆菌核糖体蛋白质突变对碱性蛋白酶基因表达的影响,发现10种13株核糖体蛋白质突变能影响碱性蛋白酶基因的表达。其中依赖链霉素突变核糖体几乎不能翻译碱性蛋白酶mRNA。依赖链霉素突变在翻译层次抑制碱性蛋白酶基因的表达,但对中性蛋白酶基因的表达没有影响。在碱性蛋白酶mRNA翻译起始区有一个复合二级结构,用体外突变方法破坏其中一个,翻译效率提高8.2倍。依赖链霉素突变和抗链霉素突变核糖体的高级结构不同,与碱性蛋白酶mRNA 5'端片段的亲合力也有差异。由于碱性蛋白酶mRNA翻译起始区的复合二级结构和低起始强度以及依赖链霉素突变核糖体高级结构的改变,使依赖链霉素突变核糖体不能翻译碱性蛋白酶mRNA。     

Differences between migrasome,a ‘new organelle’, and exosome

The migrasome is a new organelle discovered by Professor Yu Li in 2015. When cells migrate, the membranous organelles that appear at the end of the retraction fibres are migrasomes. With the migration of cells, the retraction fibres which connect migrasomes and cells finally break. The migrasomes detach from the cell and are released into the extracellular space or directly absorbed by the recipient cell. The cytoplasmic contents are first transported to the migrasome and then released from the cell through the migrasome. This release mechanism, which depends on cell migration, is named ‘migracytosis’. The main components of the migrasome are extracellular vesicles after they leave the cell, which are easy to remind people of the current hot topic of exosomes. Exosomes are extracellular vesicles wrapped by the lipid bimolecular layer. With extensive research, exosomes have solved many disease problems. This review summarizes the differences between migrasomes and exosomes in size, composition, property and function, extraction method and regulation mechanism for generation and release. At the same time, it also prospects for the current hotspot of migrasomes, hoping to provide literature support for further research on the generation and release mechanism of migrasomes and their clinical application in the future.     

DNA barcoding of Cymbidium by genome skimming: Call for next-generation nuclear barcodes

Cymbidium is an orchid genus that has undergone rapid radiation and has high ornamental, economic, ecological and cultural importance, but its classification based on morphology is controversial. The plastid genome (plastome), as an extension of plant standard DNA barcodes, has been widely used as a potential molecular marker for identifying recently diverged species or complicated plant groups. In this study, we newly generated 237 plastomes of 50 species (at least two individuals per species) by genome skimming, covering 71.4% of members of the genus Cymbidium. Sequence-based analyses (barcoding gaps and automatic barcode gap discovery) and tree-based analyses (maximum likelihood, Bayesian inference and multirate Poisson tree processes model) were conducted for species identification of Cymbidium. Our work provides a comprehensive DNA barcode reference library for Cymbidium species identification. The results show that compared with standard DNA barcodes (rbcL + matK) as well as the plastid trnH-psbA, the species identification rate of the plastome increased moderately from 58% to 68%. At the same time, we propose an optimized identification strategy for Cymbidium species. The plastome cannot completely resolve the species identification of Cymbidium, the main reasons being incomplete lineage sorting, artificial cultivation, natural hybridization and chloroplast capture. To further explore the potential use of nuclear data in identifying species, the Skmer method was adopted and the identification rate increased to 72%. It appears that nuclear genome data have a vital role in species identification and are expected to be used as next-generation nuclear barcodes.     

Stimulation of ethylene production by a cell wall component from mature green tomato fruit

Pectic (carbonate-soluble, covalently-bound pectin, CBP) material stimulated increased ethylene production when vacuum-infiltrated into whole, mature green tomato ( Lycopersicon esculentum Mill. cv. Rutgers) fruit. Activity was greatest if CBP was extracted from mature green tomatoes with jellied locules. CBP extracted from mature green tomatoes with immature seeds had no elicitor activity, while CBP from turning or red ripe tomatoes was only moderately active. Infiltration of CBP from normal mature green fruit into ripening inhibitor ( rin ) mutant tomato fruit stimulated ethylene production and attenuated red pigmentation in these fruits. Partial purification of the active material was accomplished using DEAE-Sephadex and BioGel P-100 chromatography. The most highly purified fraction is comprised of neutral carbohydrate (95%) with a relatively low content of amino acids (1%) and a uronic acid content of less than 5%. This material may be an endogenous trigger of ethylene production and ripening.     

FOUR NEW SPECIES OF COENOSIA MEIGEN (DIPTERA: MUSCIDAE) FROM YUNNAN, CHINA

Abstract  This paper describes four new species of Coenosia Meigen, 1826, namely C. angustifolia sp.nov., C. obscuriabdominis sp. nov., C. sparagmocerca sp. nov. and C. sponsa sp. nov. Type specimens are deposited in Institute of Entomology, Shenyang Normal University, Shenyang, China.