Homoeologous chromosome pairing: frequency differences in inbred and intraspecific hybrid polyploid ferns

The homosporous fern Ceratopteris thalictroides (Parkeriaceae) has evolved a polyploid genetic system that serves to store and release genetic variability in spite of self-fertilization and Mendelian homozygosity. This is demonstrated by the segregation of a gametophyte mutant within two inbred tetraploid lines and in their intraspecific hybrid. The segregation behavior can be explained by a model involving a duplicated locus and regular homoeologous chromosome pairing. Homoeologous pairing occurs at low levels in the inbred lines and at a high level in the hybrid, indicating intraspecific differences in chromosome pairing affinities.     

浙江蕨类植物的数量统计分析

在具有典型的中亚热带植被特征的浙江植物区系中,蕨类植物资源极为丰富,计49科,116属和542种(含变种、变型).其水平和垂直分布随地形和海拔高度不同而呈现较大差异,生态类型和区系成分也较为复杂,各科、属的种数差异较大.蕨类植物在浙江植物区系组成中占较大比重.     

蕨类植物繁殖研究进展

蕨类植物在种质和次生代谢产物方面具有多样性,在遗传研究、医疗保健、观赏植物、指示植物等方面有很好的开发潜力。总结了近年来蕨类植物的繁殖技术和研究进展情况,并对其组织培养的前景进行了展望,以期更好地开发和利用我国蕨类植物资源。     

关于杨树多倍体育种的几点认识

诸多杨树多倍体实例表明,基于有性多倍化的多倍体育种,可以通过一轮次的育种过程实现杨树多目标性状综合改良,获得生长快、纤维长、木素低、纤维含量高以及抗逆性强等性状表现突出的杨树品种。在具体杨树多倍体育种工作中,掌握配子或合子染色体加倍有效处理时期的即时判别方法,有助于提高杨树多倍体育种效率和效果;而多倍体品种表现优劣与其杂合性密切相关,通过杂交亲本选配以及适宜的配子染色体加倍途径选择等,可以增进多倍体的杂合性,在利用基因剂量效应带来的倍性优势同时,充分利用异源配子结合产生的杂种优势,最大限度地发挥杨树多倍体育种的技术潜力。     

青黑杨杂种三倍体花粉母细胞减数分裂染色体行为及其花粉变异研究

目的本研究通过分析青黑杨杂种三倍体的花粉母细胞减数分裂特征和配子变异规律,为进一步利用三倍体种质作为中介材料进行杨树染色体工程育种奠定基础。方法本研究以雌配子染色体加倍来源的‘哲引3号杨’ × ‘北京杨’杂种三倍体WT-21及杂种二倍体WD-2雄株为材料,基于醋酸洋红染色压片观察,比较分析了两者花粉母细胞减数分裂染色体行为及花粉形态变异。结果（1）无论是三倍体杂种WT-21还是二倍体杂种WD-2,其花粉母细胞减数分裂染色体行为均非常丰富,存在高频率的染色体提前分离、落后染色体、微核等异常现象,反映了亲本基因组间较强的异质性。（2）WT-21和WD-2花粉母细胞减数第二次分裂过程均存在平行纺锤体、融合纺锤体、三极纺锤体等异常定向,而且在WT-21中还发生胞质提前分裂,共同导致减数分裂产物中二分体、三分体等的产生。（3）三倍体WT-21的花粉空瘪率达44.55%,高于二倍体WD-2;WT-21饱满花粉的直径显著大于WD-2,从花粉直径分布可推测出WT-21能产生少量未减数花粉;WT-21的花粉生活力为（1.08 ± 0.44）%,显著低于二倍体WD-2（28.67% ± 2.04%）。结论由于倍性效应和杂合性的双重影响,青黑杨杂种三倍体的花粉母细胞减数分裂存在复杂的染色体行为,并对配子发育造成影响;利用三倍体的花粉进行授粉,可能获得非整倍体和四倍体后代,为杨树染色体操作奠定基础。      

Stomatal size in fossil plants: evidence for polyploidy in majority of angiosperms

Three published estimates of the frequency of polyploidy in angiosperms (30 to 35 percent, 47 percent, and 70 to 80 percent) were tested by estimating the genome size of extinct woody angiosperms with the use of fossil guard cell size as a proxy for cellular DNA content. The inferred chromosome numbers of these extinct species suggest that seven to nine is the primitive haploid chromosome number of angiosperms and that most angiosperms (approximately 70 percent) have polyploidy in their history.     

四川省蕨类植物资源的分布及其开发利用前景

介绍了四川省的蕨类植物资源及分布,并阐述其在药用、食用、观赏园艺以及植物修复等方面的开发利用前景。     

Ogura雄性不育甘蓝型油菜×白菜、芜菁杂种F1及其回交后代染色体减数分裂行为分析

 以甘蓝型油菜（Brassica napus L.，AACC，2n＝38）Ogura CMS材料与白菜 （B. campestris ssp. chinensis Makino, AA，2n＝20） 品种新选1号、矮脚黄和芜菁 （B. campestris ssp. rapifera Sinsk , AA，2n＝20）品种耐病98-1进行杂交、回交。F1花粉母细胞减数分裂染色体构型为10Ⅱ+9Ⅰ。BC1生长势强的群体中，新选1号和耐病98-1染色体构型多为10Ⅱ+9Ⅰ，矮脚黄的染色体构型以10Ⅱ和10Ⅱ+7Ⅰ占优势；BC1生长势弱的群体中，新选1号和耐病98-1染色体构型多为10Ⅱ+7Ⅰ，矮脚黄的染色体构型多为10Ⅱ+1Ⅰ。BC2生长势强的群体中，新选1号的染色体构型多为10Ⅱ+1Ⅰ，矮脚黄多为10Ⅱ；BC2生长势弱的群体中，新选1号和矮脚黄多为10Ⅱ，耐病98-1多为10Ⅱ+6Ⅰ、10Ⅱ+5Ⅰ。BC3根尖染色体观察新选1号、矮脚黄染色体数达到100%，耐病98-1中染色体数为20的细胞达到78.12%。同时对BC1代不同染色体数在减数分裂Ⅰ的分离规律进行了研究。结果表明，AACC染色体组物种与AA染色体组物种杂交经少数几代回交即可获得后代性状相对稳定的不育系。     

中国观赏蕨类植物的种类、繁殖方法及在园林中的应用

综述了中国观赏蕨类植物的种类、地域分布、生态习性、繁殖方法以及在园林中的应用.针对观赏蕨类植物在保护利用中存在的问题,提出了开发与利用的5点建议,并对蕨类植物的应用前景进行了展望.     

An in vitro system for adhesion and fusion of maize gametes

The development of in vitro fertilization systems in flowering plants is important for understanding and controlling the mechanisms of fertilization. Here a method is described in which isolated maize gametes fuse. In a medium containing 5 mM calcium chloride, sperm and egg cells adhere for several minutes and then fuse within 10 seconds. The method is specific to male-female gamete pairs and results in 80 percent fusion, whereas fusions with other combinations of gametic and mesophyllic cells are less frequent. Eggs fertilized in vitro do not fuse with additional male gametes, which suggests that a block to polyspermy exists.     

三元杂种[A_2A_2G_1G_1]×[A_2×(AD)_1]的形态及核型分析

在对亚比棉异源四倍体[A2A2G1G1]研究的基础上,对亲本[A2×(AD)1]和三元杂种[A2A2G1G1]×[A2×(AD)1]进行了形态学和核型分析。形态学分析表明:在23个性状当中,有26.1%的性状趋向于母本,有13.1%的性状趋向于父本,21.7%的性状为与父母本相同的性状,13.1%的性状表现为中间性状,26.0%的性状表现为超亲性状。核型分析表明:异源多倍体[A2×(AD)1]体细胞染色体数目为2n=4x=52,核型公式为2n=4x=52=50(2SAT)+2sm属1B型;三元杂种[A2A2G1G1]×[A2×(AD)1]体细胞染色体数目为2n=4x=52,核型公式为2n=4x=52=40m(4SAT)+12sm(2SAT)属2A型。     

A human Y-linked DNA polymorphism and its potential for estimating genetic and evolutionary distance

A human DNA sequence (p12f2), derived from a partial Y-chromosome genomic library and showing homology with the X and Y chromosomes and with an undetermined number of autosomes, detected two Y-specific restriction fragment length variants on male DNA that had been digested with Taq I and Eco RI. These variants may have been generated through a deletion-insertion mechanism and their pattern of holoandric transmission indicates that they represent a two-allele Y-linked polymorphism (RFLP). By means of DNA from patients with inborn deletions in chromosome Y, this polymorphic DNA site was mapped to the interval Yq11.1-Yq11.22. The frequency of the rarest allele was about 35 percent in Algerian and Sardinian human males, whereas it was only 4 percent among Northern Europeans. The p12f2 probe also detected Y-specific DNA fragments in the gorilla and chimpanzee. In view of the monosomy of the Y chromosome in mammalian species, Y-linked RFLP's may prove to be more useful than autosomal or X-linked markers in estimating genetic distances within and between species.     

Molecular genetics of human color vision: the genes encoding blue, green, and red pigments

Human color vision is based on three light-sensitive pigments. The isolation and sequencing of genomic and complementary DNA clones that encode the apoproteins of these three pigments are described. The deduced amino acid sequences show 41 +/- 1 percent identity with rhodopsin. The red and green pigments show 96 percent mutual identity but only 43 percent identity with the blue pigment. Green pigment genes vary in number among color-normal individuals and, together with a single red pigment gene, are proposed to reside in a head-to-tail tandem array within the X chromosome.     

生姜脱菌及离体快繁研究

用生姜茎尖0.5mm以内的分生组织离体培养,可100%脱菌。以加3.0mg/LBA和0.6mg/LNAA的MS培养基为佳,其繁殖效率高达79/120天,生姜茎尖再生植株的形态和染色体无异常现象,遗传性稳定。     

Linkage of lactate dehydrogenase B and C loci in pigeons

Synthesis of lactate dehydrogenase in somatic and gametic tissues of certain avian and mammalian species is controlled by alleles at three loci, A, B, and C. We report breeding experiments with pigeons that conclusively demonstrate linkage between the B and C structural loci in this species. The most probable recombination fraction is zero, and contiguity is not excluded. The upper 95 percent probability limit is 4.5 percent. This tight linkage of two loci that produce closely similar polypeptides suggests that the loci acquired their separate identities through a duplication event. Further-more, the existence of recognizable B- and C-type polypeptides in both the bird and the mammal suggests that the event and the resulting linkage preceded the separation of these fauna. If so, then the linkage has persisted for a very long time.     

不同倍性泥鳅杂交后代染色体数目组成的研究

以泥鳅 Misgurnus anguillicaudatus 为研究对象,通过染色体计数法,对二倍体泥鳅与天然四倍体泥鳅正交(2n×4n)、反交(4n×2n)杂交后代的早期胚胎、6月龄及12月龄阶段的染色体数目进行了统计分析.结果表明:早期胚胎正、反杂交后代的染色体数目为67～81、67～82,在良好的中期分裂相(100、100个)中,染色体数目为75的整三倍体众数百分比最高(22％,20％),此外还有大量染色体数目＜75的亚三倍体(37％,51％)和染色体数目＞75的超三倍体(41％,29％);6月龄正、反杂交后代的染色体数目为68～79、66～80,在良好的中期分裂相(58、63个)中,整三倍体(3n=75)众数百分比最高(26％,41％),此外还有大量亚三倍体(34％,49％)和超三倍体(40％,10％);12月龄正、反杂交后代的染色体数目为68～82、69 ～83,在良好的中期分裂相(71、50个)中,三倍体(3n=75)众数百分比最高(28％,54％),此外还有大量亚三倍体(48％,20％)和超三倍体(24％,26％).研究表明,二倍体泥鳅与天然四倍体泥鳅正、反杂交后代均出现大量能存活的非整三倍体个体,并随养殖时间的延长,非整三倍体率呈下降趋势.     

Multiple Genotypes in Individuals of Claytonia virginica

Supernumerary chromosomes are common among plants of Claytonia virginica found in a weedy population near the southwestern edge of its distribution. Roots, stems, and microsporocytes vary in chromosome number within the same plant in 68 percent of the population studied.     

Trout leukocytes: growth in oxygenated cultures

A reproducible method of culturing leukocytes from rainbow trout (Salmo gairdneri) has been found. Using an atmosphere of 100 percent oxygen, we stimulated peripheral blood leukocytes to divide at 19 degrees C. Cultured cells were used for a karyological study; they had a modal chromosome number of 60 and a constant arm number of 104, a value previously reported for other tissues in these fish.     

Electrophoretic Evidence for Genetic Diploidy in the Bracken Fern (Pteridium aquilinum)

Analysis of isozyme variability demonstrates that bracken fern (Pteridium aquilinum) has a diploid genetic system and expresses solely disomic inheritance patterns. Electrophoretic data indicate that genetically variable progeny are produced in natural populations after intergametophytic mating rather than by a process involving recombination between duplicated unlinked loci. Although some enzymes are encoded by more than one locus, this has resulted from subcellular compartmentalization of isozymes, and there is no evidence of extensive gene duplication resulting from polyploidy. The conclusions reached in this report differ from those which propose polyploidy as an adaptive mechanism for maintaining genetic variability in Pteridium and other homosporous pteridophytes.