油菜素内酯对陆地棉体细胞胚胎发生的影响

0.01ppmBR能使陆地棉Coker201,312两品种分化产生胚性愈伤组织,并有效地保持该种愈伤组织的生活力和胚胎发生能力。0.01ppmBR 0.5 ppmIAA促进Coker201,312两品种体细胞胚胎发生,0.01ppmBR 0.05ppm 2,4—D能诱导所有供试品种产生疏松黄绿色愈伤组织,2,4—D用量逐步降低或除去后,一些品种便分化产生胚性愈伤组织或体细胞胚状体。     

玉米胚性愈伤组织的长期继代及其染色体分析

对５种基因型幼胚诱导的愈伤组织继代培养表明,玉米胚性愈伤组织的长期继代受基因型,培养基成分,激素,培养条件的影响。适时继代,逐代筛选对胚性保持起重要作用。适当降低培养温度（１２±２℃）有利于愈伤组织的保存和胚性保持,可以减少愈伤组织长期继代所需的物质和工作量。长期继代培养的胚性愈伤组织,胚状体发生能力和植株再生率无显著变化,但正常苗的再生频率显著下降。观察愈伤组织细胞染色体发现：（１）基因型对不同倍性细胞的比例有明显影响。（２）随着继代时间的延长,二倍体细胞下降,四倍体和非二倍体细胞增多。（３）愈伤组织中出现多种染色体结构变异,这些结构变异有可能导致非整倍体细胞的形成。     

柑桔胚珠培养中形态发生的扫描电镜观察

在附加５００ｍｇ／Ｌ酷蛋白水解物的ＭＴ培养基上,７－８周龄的Ｐｅｎｇ柑胚珠可同时产生球形胚状体和胚性愈伤组织。在继代培养中,愈伤组织的形态发生可通过体细胞胚胎发生或发生两条途径同时进行。对正常体细胞胚胎发生。异常体细胞胚胎发生,次生胚胎发生及发生的过程和形态特征进行了系统的扫描电镜观察,并提出了在扫描电镜下鉴别双子叶植物胚状体和不定芽的形态依据。     

影响水稻幼穗培养体细胞胚胎发生因素的研究

用水稻幼穗为外植体进行组织培养,研究了影响其体细胞胚胎发生的有关因素,建立了高频率体细胞胚胎发生的培养程序。结果表明不同基因型之间体细胞胚胎发生率的差异达到61．2％;生长素2,4－D对诱导水稻体细胞胚起重要的调控作用,细胞分裂素BA有一定的协同促进作用。干燥处理可提高愈伤组织体细胞胚胎发生率,愈伤组织含水量在60％～80％范围的培养效果较好;外源DNA溶液浸泡发育早期的心状体细胞胚．其进一步发育时异常胚的频率显著增加．成苗率降低。     

棉花体细胞培养中畸形胚的初步形态学观察

棉花体细胞培养中畸形胚的初步形态学观察黄振英,黄建成,黎春玉（陕西师范大学生物系,西安７１００６２）陆地棉（Ｇｏｓｓｙｐｉｕｍｈｉｒｓｕｔｕｍ）的体细胞组织培养,能够通过产生愈伤组织,继而分化出再生植株。在短期培养中,正常胚状体占很大比例,但随着培养...     

高粱体胚发生的组织细胞学观察

以Sb33高粱非胚性、胚性愈伤组织和体胚为材料,用传统石蜡切片法对各组织材料进行组织化学染色,对高粱胚性与非胚性愈伤组织以及体胚进行组织细胞学观察。结果表明：高粱非胚性愈伤组织无淀粉粒积累,高粱胚性愈伤组织淀粉粒积累较多,而与胚性愈伤组织相比,高粱体胚淀粉粒积累更多,这说明淀粉粒的积累与高粱体细胞的胚胎发生密切相关。此外,高粱可通过鱼雷胚基部产生球形胚的方式实现体胚的增殖,高粱离体再生途径以体细胞胚发生为主,并同时存在少量器官发生途径。在高粱体细胞胚胎发生中,外起源和内起源同时存在。本研究为高粱体细胞胚胎发生提供细胞学理论基础。     

高粱不同类型胚性和非胚性愈伤组织的生理生化差异

植物体细胞胚胎发生过程中伴随着复杂的生理生化变化,为进一步揭示胚性愈伤组织的再生潜力,该研究以高粱Sb19未成熟胚诱导产生的两种胚性愈伤组织和一种非胚性愈伤组织为材料,通过测定各愈伤组织中可溶性蛋白、游离脯氨酸和可溶性糖的含量,采用方差分析法对高粱体细胞胚胎发生过程中不同类型愈伤组织的生理生化指标进行了差异比较研究。结果表明:(1)高粱两种胚性愈伤组织中可溶性蛋白、游离脯氨酸和可溶性糖的含量均显著高于非胚性愈伤组织,表明胚性愈伤组织中的代谢活性高于非胚性愈伤组织,能够为体细胞胚胎发生提供更多的物质能量基础。(2)两种类型胚性愈伤组织之间生理生化差异显著,其中,Ⅱ型胚性愈伤组织中可溶性蛋白和游离脯氨酸含量均显著高于Ⅰ型胚性愈伤组织,相反,Ⅱ型胚性愈伤组织中可溶性糖含量显著低于Ⅰ型胚性愈伤组织,这种生理生化差异在一定程度上影响了后期的分化。该研究结果为愈伤组织的胚胎发生能力与生化代谢的关系提供理论依据。     

几种植物体细胞胚胎发生标记蛋白的研究

利用ＳＤＳ一聚丙烯酰胺凝胶电泳对西洋参（ＰａｎａｘｑｕｌｎｇｕｅｆｏｌｉｕｓＬ．）、香雪兰（Ｆｒｅｅｓｎｉｒｅ－ｆｒａＫｌａｔｔ．）、光棘豆（ＯｘｙｔｒｏｐｏｌｅｐｔｏｐｈｙｌｌａＬ．）和草木气（Ｍｅｄｌ’ｃａｇｏｓｕａａｖｅｏｌｅｎｓＬ．）４种植物的胚性、非胚性愈伤组织及胚状体的可溶性蛋白组成进行了分析。结果表明,在这几种植物的胚性愈伤组织中均存在非胚性愈伤组织中没有的特异蛋白质。在西洋参和光棘豆中,这些胚性蛋白质在胚状体中也能检测到。另外,在香雪兰和光棘豆的非胚性愈伤组织中还发现了胚性愈伤组织中没有的蛋白质成分。特异性的胚性蛋白质可以作为分子标记来鉴别潜在的胚性培养物,跟踪胚胎发育,并为进一步探讨体细胞胚胎发生的基因调控和分子机制提供基础。     

籼稻体细胞胚胎发生的组织学及细胞学研究

以成熟种子为外植体,在离体培养中研究了体细胞胚胎发生,组织学研究表明,愈伤组织是由成熟种子盾片的表皮吸收细胞首先发生的,随后从愈伤组织分化出胚状体。象水稻合子胚的结构一样,体细胞胚状体主要由盾片,胚芽稍及胚根组成,在胚状体内可以观察到不同发育时期的原胚,包括大量的单一的胚性细胞、二细胞、四细胞及分化程度不同的原胚以及一些畸形胚状体,从本实验可以初步认为由籼稻体细胞培养而获得的胚状体在结构上也有象合子胚一样的基本结构,并且是单细胞起源的。     

青扦胚性细胞悬浮培养中影响体细胞胚发生因素的研究

试验以青扦（Ｐｉｃｅａｗｉｌｓｏｎｉ）的胚性愈伤组织为材料,以改良５９基本成分附加２４－Ｄ１ｍｇ／Ｌ及ＫＴ１ｍｇ／Ｌ为培养介质,比较了液体悬浮与半固体二种培养方式对胚性愈伤组织增殖和体细胞发生的影响,研究了液体悬浮培养过程中影响体细胞胚发生的因素。结果表明：液体悬浮培养好于半固体培养,它的胚性愈伤组织的生长率为２６８％,是半固体培养的１２４倍;体细胞胚的分化率为９３％,是半固体培养的２２倍;悬浮培养较佳的培养条件为：初始细胞密度为２％（鲜重）,蔗糖浓度为２０ｇ／Ｌ,摇床转速为１００ｒ／ｍｉｎ,ｐＨ为５８。经过两个月悬浮培养,将培养物转至１／２改良５９附加ＡＢＡ１ｍｇ／Ｌ的分化培养基上,３个月后每ｇ培养物上可获得２８５个正常的子叶期体细胞胚。     

Leaf waxes in Coincya Rouy (Brassicaceae)

A total of 55 populations belonging to the genus Coincya Rouy (Brassicaceae) from the Iberian Peninsula were examined for their leaf wax composition. The total wax content and the relative proportions of the five main lipid fractions, hydrocarbons, esters, ketones, free alcohols and free sterols were determined. It was observed that there was a positive correlation between chemical composition and environmental adaptation, and also with certain morphological characterS. Changes relate to low temperatures or to high relative humidity, and there is a positive correlation between chemical composition and leaf glaucosity.     

Diurnal variation of phytoplankton in Loch Lomond

A study of diurnal variation over a 48 hour period was undertaken in July 1973 to ascertain the extent and timing of some major chemical, physical and biological variables in Loch Lomond. The phytoplankton population was dominated by the diatom Tabellaria fenestrata, with a maximum abundance between 04.00 and 06.00 h in surface waters on both days. A distinct diurnal variation in cell numbers was also recorded. Chlorophyll a values also showed a regular pattern of variation with a single peak between 10.00 and 14.00 h each day. Some chemical changes appeared to be a direct consequence of phytoplankton multiplication. Nitrate-nitrogen showed a decrease in concentration coinciding with the period of cell multiplication, whereas dissolved silica concentrations only fell on the completion of this process. Other common diatoms displayed less distinct patterns of variation although Fragilaria crotonensis attained its maximum abundance in surface waters. Considerable variation was recorded in the number of organisms and chlorophyll a levels at 25 cm intervals in the upper metre of the water column, with large variations in standing-crop and chemical parameters in the space of one hour. Diurnal oscillations in the position of the thermocline were recorded, with the thermal discontinuity being at its greatest depth in the early hours of the morning. The hypolimnion and thermocline regions clearly acted as a source of nutrient supply to the epilimnion. From this investigation it is apparent that for the proper understanding of diurnal variation a 24 hour study alone is insufficient and may give rise to misleading results.Department of Botany, University of GlasgowDepartment of Botany, University of Glasgow     

Inter‐ and intraspecific variation in mycotoxin tolerance: A study of four Drosophila species

Many mycophagous Drosophila species have adapted to tolerate high concentrations of mycotoxins, an ability not reported in any other eukaryotes. Although an association between mycophagy and mycotoxin tolerance has been established in many Drosophila species, the genetic mechanisms of the tolerance are unknown. This study presents the inter‐ and intraspecific variation in the mycotoxin tolerance trait. We studied the mycotoxin tolerance in four Drosophila species from four separate clades within the immigrans‐tripunctata radiation from two distinct locations. The effect of mycotoxin treatment on 20 isofemale lines per species was studied using seven gross phenotypes: survival to pupation, survival to eclosion, development time to pupation and eclosion, thorax length, fecundity, and longevity. We observed interspecific variation among four species, with D. falleni being the most tolerant, followed by D. recens, D. neotestacea, and D. tripunctata, in that order. The results also revealed geographical variation and intraspecific genetic variation in mycotoxin tolerance. This report provides the foundation for further delineating the genetic mechanisms of the mycotoxin tolerance trait.     

Skeletal biological distance studies in American physical anthropology: recent trends

Biological distance analysis, the dominant type of skeletal biological research during the 19th century, has become less visible in recent years. Although the proportion of American Journal of Physical Anthropology articles and published abstracts focusing on biodistance has remained fairly constant over the three decades between 1955 and 1985, the proportion of biodistance contributions relative to other skeletal biology studies has decreased. Emphasis in skeletal biology has shifted from the analysis of biological variation to investigations of health and diet, and within biodistance studies methodological issues have assumed prominence over purely analytical approaches. This paper investigates trends in biological distance analysis through a survey of articles and meetings abstracts published in the American Journal of Physical Anthropology from 1955 to 1985. The survey provides the historical context for five symposium papers on skeletal biological distance presented at the 1986 meeting of the American Association of Physical Anthropologists.     

Functional characterization of powdery mildew resistance gene MlIW172, a new Pm60 allele and its allelic variation in wild emmer wheat

Wild emmer wheat (Triticum dicoccoides, WEW) is an immediate progenitor of both the cultivated tetraploid and hexaploid wheats and it harbors rich genetic diversity against powdery mildew caused by Blumeria graminis f. sp. tritici (Bgt). A powdery mildew resistance gene MlIW172 originated from WEW accession IW172 (G-797-M) is fine mapped in a 0.048 centimorgan (cM) genetic interval on 7AL, corresponding to a genomic region spanning 233 kb, 1 Mb and 800 kb in Chinese Spring, WEW Zavitan, and T. urartu G1812, respectively. MlIW172 encodes a typical NLR protein NLR^IW172 and physically locates in an NBS-LRR gene cluster. NLR^IW172 is subsequently identified as a new allele of Pm60, and its function is validated by EMS mutagenesis and transgenic complementation. Haplotype analysis of the Pm60 alleles reveals diversifications in sequence variation in the locus and presence and absence variations (PAV) in WEW populations. Four common single nucleotide variations (SNV) are detected between the Pm60 alleles from WEW and T. urartu, indicative of speciation divergence between the two different wheat progenitors. The newly identified Pm60 alleles and haplotypes in WEW are anticipated to be valuable for breeding powdery mildew resistance wheat cultivars via marker-assisted selection.     

Skull osteology and osteological phylogeny of the Western whip snake Hierophis viridiflavus (Squamata,Colubridae)

The skull osteology of Hierophis viridiflavus is here described and figured in detail on the basis of 18 specimens. The sample includes specimens from the ranges of both H. viridiflavus viridiflavus and H. viridiflavus carbonarius as well as specimens not identified at sub-specific level. The main characters that define H. viridiflavus in comparison to the parapatric congeneric species Hierophis gemonensis are wide maxillary diastema, basioccipital crest well distinct in three lobes and basioccipital process well marked. The foramina of the otoccipital and prootic, and the basioccipital process of the basioccipital are among the most ontogenetically variable characters, as indicated by two juvenile specimens included in the sample. A specimen-level phylogenetic analysis including H. gemonensis and other outgroups (overall 6 species, 26 specimens, 64 skull characters) recovered all H. viridiflavus specimens in one clade, indicating the presence of a clear phylogenetic signal in the applied characters. However, the resolution within the H. viridiflavus clade is poor the monophyly of H. viridiflavus carbonarius was retrieved, but not that of Hierophis v. viridiflavus. Probably due to the relatively high variability, the skull morphology does not support the recently proposed specific status of the two subspecies.     

A hybrid zone between Chorthippus parallelus parallelus and Chorthippus parallelus erythropus (Orthoptera: Acrididae): morphological and electrophoretic characters

Two subspecies of the grasshopper Chorthippus parullelus have distributions that abut in the Pyrenees. We have studied morphological and electrophoretic variation in II populations near Mont Louis, Pyrénées-Orientales, France. The two subspecies differ in several morphological characters and at one enzyme locus, esterase-2, and in this area they hybridize forming a cline in morphology less than 5 km wide. Examination of museum specimens suggests that this hybrid zone extends for most of the length of the Pyrenees, possibly breaking down in the extreme west. As the two subspecies are known to differ in mating behaviour this hybrid zone is well suited to the study of reinforcement.     

The variances of the distributions of the combinations of the sexes within mammalian litters: Notes to mark the centenary of the problem

It is 100 years since Gini noted that in some samples of litters of mice and rabbits, the variances of the distributions of the combinations of the sexes are sub-binomial. In other words, in contrast with binomial expectation, there are too many litters in which the sexes are equally balanced, and there are too few unisexual litters. In the intervening years, this finding has been replicated in a number of further species, but no explanation has become established. Potential explanations are reviewed here, and it is suggested that the most likely cause is that, at the time of formation of the zygotes, p, the probability that a zygote will be male, varies from one zygote to another within litters, thus constituting an example of Poisson variation. And it is a standard result in probability theory that such variation causes sub-binomial variance.     

浙江古田山自然保护区常绿阔叶林种子雨的时空变异

木本植物种子产量的时间和空间变化格局对植物更新以及群落组成和结构有着重要影响, 是种子雨研究的一个重要方面。2006年6月在古田山亚热带常绿阔叶林24 hm²样地布置了130个面积为0.5 m²的种子雨收集器, 每周收集一次。利用4年的种子雨数据, 研究了种子雨的时间和空间变异。主要结果如下: (1)共收集到124227粒成熟种子, 属于29科51属63种, 每月降水量与平均每月种子数、物种数均呈显著负相关; (2)种子产量在每年干季(秋季)有明显的高峰, 有10个物种在湿季扩散种子, 不同物种结实物候起始和终止时间有差异; (3)基于4年的种子雨数据, 几乎所有物种的种子雨均存在很大的年际变异, 收集到的所有物种的种子产量年际变异系数的中位数为1.72; (4)种子雨在不同收集器之间有很大的变异, 变异系数的中位数为8.06; 几乎所有物种的空间变异都远远大于时间变异, 这可能是由于母树的稀有性、种子传播距离的差异, 以及地形等因素造成。通过与巴拿马Barro Colorado Island 50 hm ²样地108个物种种子产量的年际变异系数相比较, 古田山种子雨数据支持了高纬度地区种子产量变异高于低纬度地区的假说。