夜光藻有性繁殖研究进展

夜光藻是全球最主要的赤潮生物之一,也是我国近海常见的浮游甲藻。根据营养方式分为异养的红色夜光藻和混合营养的绿色夜光藻,前者广泛分布于温带和亚热带近岸水域,后者仅分布于热带西太平洋、阿拉伯海、阿曼湾和红海。夜光藻的生活史包括无性繁殖和有性繁殖过程。少部分营养细胞自发转变为配子母细胞,启动了有性繁殖。每个配子母细胞可形成大量配子,具有横沟、纵沟和2根鞭毛,形态与裸甲藻接近。配子两两融合形成合子,合子不经过休眠孢囊阶段直接发育成新的营养细胞。目前,对配子母细胞形成的调控机制、合子发育的影响因素的认识还存在分歧。研究发现,营养细胞经过一定次数的二分裂后都会转变为配子母细胞,而配子的存在能够中止此过程,使营养细胞继续进行二分裂。因此,有性繁殖可能通过产生新个体对种群增长做出贡献,还可能通过释放配子维持无性繁殖,进而促进种群增长。配子在相模湾水域全年都有分布,其丰度峰值与营养细胞丰度峰值同步或提前出现,配子的大量出现可能是赤潮形成的必要条件。对有性繁殖的研究佐证了夜光藻在甲藻的系统进化中处于较为古老的地位。此外,还简单介绍了研究夜光藻有性繁殖的主要方法,回顾了国内的夜光藻研究,并对相关研究进行了展望。     

天麻室内有性繁殖技术

天麻室内有性繁殖技术蔡义荣（安徽省金寨县双河职业高中２３７３８１）天麻（Ｇａｓｔ。ｄｉ４ｅｌａｔａＢｌｕｍｅ）属寄生性兰科植物,无根无绿叶,依靠分解吸收蜜环菌卜。。ｌｉａｎａｍｅｌｌｅａ（ＶａｈｌｅｘＦｒ）ＱｕｅｌＪ而生存。应用箭麻（即成熟的天麻块茎...     

玉蝉花繁殖生态学研究

通过野外调查、人工授粉和室内种子萌发实验等,对天目山玉蝉花（Iris ensata）种群繁殖生态特征进行了研究。结果显示：玉蝉花自然种群呈聚集型分布,种群更新主要依赖贡献率为0.756的无性繁殖。人工同瓣和异瓣自花授粉座果率分别为10%和20%,结实数分别为0和4±1（n=2）粒/果;同株和异株异花授粉座果率分别为80%和100%,结实数分别为59±7（n=8）和64±9（n=10）粒/果,自交主要来自同株异花授粉,而同株花异熟、雌雄异位和异向等可有效降低自交。自然套袋不结实,不存在无融合生殖。花粉/胚珠比1277±270（n=10）,辅证玉蝉花为兼性异花授粉、异花授粉植物。有效授粉昆虫为蜜蜂（Apismellifica）,访花频率为0.019次.花-1.h-1,单只蜜蜂回访同朵花的比率为3.5%。自然种群立地种子数估算值为368粒/m2,种子宿存,具非深度生理休眠,萌发需光,低温层积60d萌发率达94.9±0.7%。玉蝉花种群繁殖适应对策为k对策,具备自我维持机制,但现正受人为干扰。     

蓝睡莲有性繁殖栽培研究

蓝睡莲（延药睡莲）NymphaeastellataWilld．是一种具有园林水体绿化的重要观赏水生植物。根据我们调查、收集的结果看,现仅在海南省万宁县境内的丘陵湿地中发现有自然分布。中国植物志第二十七卷记载湖北有分布,但到目前为止,尚未有人报道发现实物;海南植物志记载海口市附     

蕨菜有性繁殖与无性繁殖技术

蕨菜有性繁殖与无性繁殖技术冯玉斌,何允波,赵占美,洪永刚（通化市园艺研究所１３４００１）蕨菜（ＰｔｈａｉｕｌｎａｑｕｆｆＩｎｕｍ）是凤尾蕨科的多年生草本植物。适应性强,分布极为广泛。近年来,我国对蕨菜进行大量出口。主要是由于其新鲜可口,营养价值高,含...     

野生有性繁殖物种首次证明可单性繁殖

通常都是2条蛇——一雌一雄——合作生下一窝蛇宝宝。然而最新的研究表明,美洲蝮蛇（Agkistrodon contortrix）及其有毒的表亲水蝮蛇（Agkistrodon piscivonus）却并非总是需要一个伴侣才能够创造下一代。这些毒蛇具有单．性繁殖的能力。     

藕莲有性繁殖栽培

根据莲(Nelumbo nucifera)生物学特性,既可用藕作种进行无性繁殖,也可用种子播种进行有性繁殖。藕莲在我国有数千年的栽培历史,但素以无性系栽培。尚未见到有性繁殖栽培的报道。作者自1980年起进行了有性繁殖栽培试验。1982-1984年先后在武汉市、河南省封丘县、进行大田小区栽培试验,并列入湖北省科委农林牧副渔综合基点县推广研究项目,在广济县试验推广,已获成功。     

风箱果有性繁殖研究

对风箱果（Physocarpus amurensis）适宜的采种时期、不同母树种子的成熟差异和幼苗的生长特征进行了研究。结果表明,风箱果种子的最适采种期在7月末,种子成熟后有休眠特性;方差分析表明,不同植株间种子的发芽率和千粒重都达到极显著水平（p<0.01）,并且发芽率与种子重量呈正相关,其相关程度最佳的为幂函数,确定系数是75.75%（p<0.01）;风箱果幼苗类型为子叶出土型,幼苗生物量对根的投资最大,其次是叶,茎的最少,在这3部分生物量投资中,对根和叶的投资比较稳定（其变异系数分别为6.8%和11.03%）,对茎的生物量投资具有较大的变异（其变异系数为21.81%）。基径是衡量风箱果幼苗空间大小的重要数量指标。风箱果构件生物量（根生物量、茎生物量、叶生物量及总生物量）各组分均随基径的增加,呈线性函数形式增长,这表明随着植株的空间扩展,各构件有着相同的物质生产与积累规律。     

松江鲈的生态学和繁殖生物学的研究进展

松江鲈(Trachidermus Fasciatus Heckel),别名四鳃鲈、老虎鱼、新娘鱼、媳妇鱼等,隶属于鲉形目(Scorpaeniformes),杜父鱼科(Cottidae),松江鲈鱼属(Trachidermus)。     

Gamete attachment process revealed in flowering plant fertilization

Sex-possessing organisms perform sexual reproduction, in which gametes from different sexes fuse to produce offspring. In most eukaryotes, one or both sex gametes are motile, and gametes actively approach each other to fuse. However, in flowering plants, the gametes of both sexes lack motility. Two sperm cells (male gametes) that are contained in a pollen grain are recessively delivered via pollen tube elongation. After the pollen tube bursts, sperm cells are released toward the egg and central cells (female gametes) within an ovule (Fig. 1). The precise mechanism of sperm cell movement after the pollen tube bursts remains unknown. Ultimately, one sperm cell fuses with the egg cell and the other one fuses with the central cell, producing an embryo and an endosperm, respectively. Fertilization in which 2 sets of gamete fusion events occur, called double fertilization, has been known for over 100 y. The fact that each morphologically identical sperm cell precisely recognizes its fusion partner strongly suggests that an accurate gamete interaction system(s) exists in flowering plants.Open in a separate windowFigure 1.Illustration of the fertilization process in flowering plants. First, each pollen tube accesses an ovule containing egg and central cells. Next, the 2 sperm cells face the female gametes in the ovule after the pollen tube bursts. Finally, each sperm cell simultaneously fuses with either egg or central cell.     

DURATIONS OF GAMETE MOTILITY AND CONJUGATION ABILITY OF ULVA COMPRESSA (ULVOPHYCEAE)1

The present study was designed to develop a technique for crossing and to gain insight into how sexual reproduction contributes to the maintenance of local populations of Ulva compressa L. To examine the durations of gamete motility and conjugation ability, freshly released gametes were incubated for various periods of time prior to mixing both mating types. The conjugation ability of the gametes gradually declined after being released from the thalli when the gametes were incubated without mixing with the opposite mating type. The ability to conjugate decreased by half after 6 h, although most of the gametes remained motile. The gametes released 4 h later had the same level of conjugation ability when mixed immediately after releasing. When the mature thalli were wrapped in a moist paper towel to prevent gametes from being released, the gametes were preservable for 7 h without a significant decrease in their conjugation ability. Conjugation occurred soon after mixing gametes of both mating types and reached a plateau after 30 s. However, conjugation rates did not exceed a rate of ～70%, even though freshly released gametes were used. Interestingly, a portion of the gametes newly conjugated 30 min after mixing both mating types, and conjugation rates reached a second plateau at ～90%. Gametes with delayed conjugation are provided some period of time that allows them to be transported away and increases their chances of mating with more distant populations, thus contributing to the maintenance of genetic variation.     

One Hundred and One Years of Chemotaxis. Pfeffer,Pheromones, and Fertilization

Chemotaxis of flagellated unicellular gametes was discovered by Wilhelm Pfeffer. In most known systems the lure is a metabolic waste product ritualized for sexual attraction. A special case are the female gametes of brown algae. They secrete polyunsaturated C-8 or C-11 hydrocarbons mostly with straight chain or unsubstituted tri-, penta- or heptacyclic structures. Their biogenetic origin stems from polyunsaturated fatty acids. The reactions leading to the different structures comprise lipoxygenase-type radical formations and dehydrogenating decarboxylations. — Most gametes produce a variety of such hydrocarbons; however, only one of them is the active principle. Biological activity is highly stereospecific; but frequently the bouquets contain lures for other species. Although cross-fertilization is excluded, they may be used to defend the habitat against overgrowth by other seaweeds. Besides chemoattractive action, some secretions also synchronize hatching of the spermatozoids. One of the compounds responsible is characterized by an epoxy substitution. — For most of the structures, stereospecific and versatile syntheses are available, which were used to investigate the binding site. This forms a template for the signal molecule with specifically situated polarizing groups that interact with the π-electrons of the double bonds. The message is transformed into changes of flagellar beat patterns which ensure meeting of the partners followed by fertilization.     

银杏传粉生物学研究进展

银杏(Ginkgo biloba L.)是最古老裸子植物之一,其传粉受精过程表现出许多特殊的原始性状和特征,在种子植物的系统演化上具有重要研究价值;同时,银杏种实经济价值高,但栽培上由于授粉受精不良而导致落花落果现象严重,因此了解银杏传粉生物学特性对于其种实的优质高产具有实际意义.本文从银杏雌雄株开花物候学、雌雄花形态结构特征、花粉和胚珠发育进程、花粉和胚珠生物学特性、传粉机制及花粉在胚珠内萌发生长进程等方面,对银杏传粉生物学相关研究进行综述,为银杏的系统演化、授粉受精和种实发育研究提供参考.