爪蟾(Xenopus laevis)的四倍体及其子一代

在爪蟾受精卵第一次有丝分裂中期进行静液压处理,抑制细胞质分裂从而得到四倍体。实验中获得三只存活了三年以上的四倍体雌性爪蟾。其中一只雌性与二倍体雄性爪蟾作人工催青得到受精卵。现已产卵三批,发育的胚胎400余,经检查子代染色体为三倍体。     

八倍体小黑麦单倍性胚性细胞无性系的建立

取异源八倍体小黑麦“h739”的植株和花粉植株护颖分化期的幼穗,培养在附加2mg/l2,4-D 的 MS 培养基上,接种后20天形成愈伤组织。诱导频率达98.3%。转分化培养,植株再生率为95.2%。选出了 HC-2、HC-3、HC-4、HC-5和 HC-0 5个无性繁殖系,这些系经892天的长期继代培养,植株再生率仍保持在90%以上。HC-2、HC-3经细胞学观察表明,大部分细胞为单倍体(2n=28)。组织学和电镜观察表明 HC-3系是由不同发育阶段的胚状体组成。     

APPLICABILITY OF THE HYPERGEOMETRIC PHENOTYPIC MODEL TO HAPLOID AND DIPLOID POPULATIONS

We show that the phenotypic hypergeometric model of a quantitative trait can exactly describe both haploid and diploid populations. The condition necessary for this is equiprobability of genotypes within each phenotype. This requires equal allele frequencies across the loci, which may be the case when the population is under disruptive selection.     

二倍体和四倍体泥鳅染色体组型比较

根据陈景星1 的论述,分布于中国境内的泥鳅属(Misgurnus) 的鱼类共有三种:北方泥鳅 (M.bipartitus) 、黑龙江泥鳅(M.mohoity) 和泥鳅(M.anguillicaudatus) 。       

CHEMO-DEMES OF DIPLOID AND TETRAPLOID THELESPERMA SIMPLICIFOLIUM (HELIANTHEAE,COREOPSIDINEAE)

Selected secondary biochemical constituents (mainly flavanoids) contained in methanol leaf extracts of 11 taxa in the genus Thelesperma were analyzed via two-dimensional paper chromatography. With but one exception all produce an essentially identical array of these compounds. Since this common or “generic” biochemical profile is present regardless of the morphological, ecological, and cytological differences among and within the various species, it is impossible to make accurate specific identifications on the basis of chromatographic data alone. Recently, however, morphologically identical, but allopatric, diploid and tetraploid races of T. simplicifolium were discovered which differ radically in respect to these secondary biochemical components. Their infraspecific biochemical differences are so absolute that it is possible to predict accurately the ploidy level and geographic source of any given individual from its chromatographic profile. The evolutionary implications of these biochemical differences are also discussed briefly.     

ADAPTATION OF DIPLOID AND TETRAPLOID CHAMERION ANGUSTIFOLIUM TO ELEVATION BUT NOT LOCAL ENVIRONMENT

Polyploid organisms often have different geographic ranges than their diploid relatives. However, it is unclear whether this divergence is maintained by adaptation or results from historical differences in colonization. Here, we conducted a reciprocal transplant experiment with diploid and autotetraploid Chamerion angustifolium to test for adaptation at the ploidy and population level. In the Rocky Mountains, pure diploid populations occur at high elevations and pure autotetraploid populations occur at low elevations with mixed ploidy populations between. We planted 3134 seedlings in 2004 and 3890 juveniles (bolting) in 2005 among nine plots, three in each of the diploid, mixed ploidy, and tetraploid zones, and monitored survival until 2008. For both seedlings and juvenile plants, elevation significantly influenced survival. The juvenile plants also showed a significant ploidy by elevation interaction, indicating that diploids and tetraploids survived best at their native elevations. In contrast, we found no evidence of local adaptation to plot within elevation. This suggests that the current distribution of diploids and tetraploids across elevations is the result of adaptation and that genome duplication may have facilitated the invasion of lower elevation habitats by limiting the movement of maladapted alleles from diploid populations at higher elevations.     

PATTERNS OF ALLOZYME VARIATION IN DIPLOID AND TETRAPLOID CENTAUREA JACEA AT DIFFERENT SPATIAL SCALES

Abstract.— The extent and spatial patterns of genetic variation at allozyme markers were investigated within and between diploid and autotetraploid knapweeds (Centaurea jacea L. sensu lato, Asteraceae) at contrasted geographic scales: (1) among populations sampled from a diploid‐tetraploid contact zone in the northeastern part of the Belgian Ardennes, and (2) within mixed populations from that zone where diploids and tetraploids coexist. Our data were also compared with a published dataset by Sommer (1990) describing allozyme variation in separate diploid and tetraploid knapweeds populations collected throughout Europe. Genetic diversity was higher in tetraploids. In the Belgian Ardennes and within the mixed populations, both cytotypes had similar levels of spatial genetic structure, they were genetically differentiated, and their distributions of allele frequencies were not spatially correlated. In contrast, at the European scale, diploids and tetraploids did not show differentiated gene pools and presented a strong correlation between their patterns of spatial genetic variation. Numerical simulations showed that the striking difference in patterns observed at small and large geographic scales could be accounted for by a combination of (1) isolation by distance within cytotypes; and (2) partial reproductive barriers between cytotypes and/or recurrent formation of tetraploids. We suggest that this may explain the difficulty of the taxonomic treatment of knapweeds and of polyploid complexes in general.     

PLOIDY AND EVOLUTION BY SEXUAL SELECTION: A COMPARISON OF HAPLOID AND DIPLOID FEMALE CHOICE MODELS NEAR FIXATION EQUILIBRIA

We compare the stability properties of haploid and diploid models of Fisherian sexual selection (with male contribution limited to sperm) by examining both models at equilibria for which a male trait is fixed or absent. Haploid and diploid two locus diallelic models share the property that the stability of such fixation equilibria is determined by the relationship between the harmonic mean of relative preference values for the common male trait, weighted by the frequency of the preferences, and the relative viability associated with the common male trait. When diploid females with heterozygotic-based preferences express preference strengths intermediate between homozygote-based preferences, then boundary equilibria of haploid and diploid models share many stability properties. However, even with intermediate heterozygote preferences, haploid and diploid models do differ: (1) for a particular frequency of the preference allele, both fixation boundaries can be stable for the diploid model, and (2) with over- or underdominance at the preference locus (a possibility precluded in the haploid model), a fixation boundary in the diploid model may show two switches in its stability state for increasing frequencies of one of the preference alleles. These differences are due not just to the impossibility of dominance in haploid models, but also to the larger number of diploid genotypes.     

GENETIC VARIABILITY WITHIN A POPULATION AND BETWEEN DIPLOID/HAPLOID TISSUE OF MACROCYSTIS PYRIFERA (PHAEOPHYCEAE)1

Multi-locus DNA fingerprints using an M13 probe were obtained for eight individuals of giant kelp Macrocystis pyrifera (L.) C. Ag. collected from Monterey Bay, California. For each individual, DNA was extracted from a diploid blade and from ca. 10⁹ haploid spores that were released from four to Jive sporophylls. Viable or swimming spores from one individual were pooled and referred to as a spore group. A total of 34 bands (4–19 kb) was detected in DNA fingerprints from the eight blades and eight spore groups, with individual blade or spore groups exhibiting 7–18 bands (mean = 12.6). One band (4.5 kb) was present in all 16 samples. Eight bands were detected in 11–14 of the 16 samples. Similarity indices were calculated for all pairwise comparisons of fingerprint bands among all possible combinations of blades and spore groups. Mean similarity indices for the eight blades (0.51, SE = 0.032) and spore groups (0.56, SE = 0.031) were significantly lower than for the eight comparisons of the blade and spore groups from a single individual (0.86, SE = 0.052). The data indicate that DNA fingerprints can be used to measure genetic variation within populations of M. pyrifera because variation of DNA fingerprints associated with meiotic products (spores) of a given individual is small relative to variation observed among individuals within the population. Additionally, fingerprint variation between diploid vegetative tissue and haploid meiotic products may be a measure of genetic change due to recombination or DNA turnover mechanisms.     

PLANT POLYPLOIDY AND POLLINATION: FLORAL TRAITS AND INSECT VISITS TO DIPLOID AND TETRAPLOID HEUCHERA GROSSULARIIFOLIA

In many polyploid species, polyploids often have different suites of floral traits and different flowering times than their diploid progenitor species. We hypothesized that such differences in floral traits in polyploids may subsequently affect their interactions with pollinating and other insect visitors. We measured floral morphology and flowering phenology in 14 populations of diploid and autotetraploid Heuchera grossulariifolia Rydb. (Saxifragaceae), determined if repeated evolution of independent polyploid lineages resulted in differentiation in floral morphology among those lineages, and ascertained if there was a consistent pattern of differentiation among genetically similar diploid and autotetraploid populations. In addition, we evaluated the differences in suites of floral visitors within a natural community where diploids and autotetraploids occur sympatrically. Overall, flowers of autotetraploid plants were larger and shaped differently than those of diploids, had a different flowering phenology than that of diploids, and attracted different suites of floral visitors. In comparison with flowers of diploids, tetraploid floral morphology varied widely from pronounced differences between cytotypes in some populations to similar flower shapes and sizes between ploidal levels in other populations. Observations of floral visitors to diploids and autotetraploids in a natural sympatric population demonstrated that the cytotypes had different suites of floral visitors and six of the 15 common visitors preferentially visited one ploidy more frequently. Moreover, we also found that floral morphology differed among independent autotetraploid origins, but there was no consistent pattern of differentiation between genetically similar diploid and autotetraploid populations. Hence, the results suggest that the process of polyploidization creates the potential for attraction of different suites of floral visitors. Multiple origins of polyploidy also presents the opportunity for new or different plant-insect interactions among independent polyploid lineages. These differences in turn may affect patterns of gene flow between diploids and polyploids and also among plants of independent polyploid origin. Polyploidy, therefore, may result in a geographic mosaic of interspecific interactions across a species' range, contributing to diversification in both plant and insect groups.     

金鱼etv2基因的克隆及在雌核发育单倍体和自交二倍体胚胎中的差异表达

为研究鱼类雌核发育单倍体循环系统发育异常的原因,从金鱼(Carassius auratus)中克隆了血管发生主调控基因etv2(Ets variant 2)的全长cDNA序列,并比较分析了该基因在雌核发育单倍体和自交二倍体中的表达。金鱼etv2 cDNA全长1531 bp,其开放阅读框为1116 bp,编码371个氨基酸。序列对比分析表明,金鱼ETV2蛋白的C端含有ETS(E26 transformation-specific)转录因子家族所共有的ETS DNA结合结构域,该结构域氨基酸序列与其他脊椎动物ETV2的同源性超过60%。RT-PCR和荧光实时定量PCR分析结果表明, etv2在自交二倍体金鱼成体的肝脏、心脏、肌肉、肾脏、精巢、脑和脾脏等多种器官组织中表达,但在卵巢和成熟卵子中不表达;在金鱼胚胎发育过程中, etv2从尾芽期开始表达,在体节形成后, etv2表达水平随胚胎发育而升高,在20体节期达到峰值,随后其表达水平降低。整胚原位杂交显示etv2特异性表达于自交二倍体金鱼胚胎的侧板中胚层、成血管细胞以及血管内皮细胞。在14体节期和20体节期,雌核发育单倍体胚胎中etv2在躯...     

DEVELOPMENT OF FLOWER FORM IN AN ALLOTETRAPLOID CLARKIA AND ITS PARENTAL DIPLOID SPECIES

The allotetraploid Clarkia delicata possesses a floral phenotype and breeding system intermediate to its diploid progenitors. Three patterns were observed in a comparative study of anther, sepal, and petal development using allometry and scanning electron micrographs. In Pattern 1 (e.g., anther), all three species are similar at inception and in subsequent development. Anthers of the allotetraploid mature at a size intermediate to both diploids. In Pattern 2 (e.g., sepal and petal limb), diploids exhibit divergent developmental patterns, and the allotetraploid develops similarly to one diploid. In Pattern 3 (e.g., petal size and shape), diploids exhibit divergent developmental patterns, and the allotetraploid is variously intermediate to both. In petal size (length vs. width), the diploid developmental pathways are parallel, and the allotetraploid is intermediate at all points of development. In petal shape (limb length above widest point/length below widest point vs. petal width), diploid developmental pathways intersect, and the allotetraploid is similar to one diploid at inception and the other in subsequent development.