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51.
52.
Genetic diversity and its relationship to hybrid performance in maize as revealed by RFLP and AFLP markers 总被引:50,自引:0,他引:50
P. Ajmone Marsan P. Castiglioni F. Fusari M. Kuiper M. Motto 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(2):219-227
The challenge to maize breeders is to identify inbred lines that produce highly heterotic hybrids. In the present study we
surveyed genetic divergence among 13 inbred lines of maize using DNA markers and assessed the relationship between genetic
distance and hybrid performance in a diallel set of crosses between them. The parental lines were assayed for DNA polymorphism
using 135 restriction fragment length polymorphisms (RFLPs) and 209 amplified-fragment polymorphisms (AFLPs). Considerable
variation among inbreds was detected with RFLP and AFLP markers. Moreover AFLPs detect polymorphisms more efficiently in comparison
to RFLPs, due to the larger number of loci assayed in a single PCR reaction. Genetic distances (GDs), calculated from RFLP
and AFLP data, were greater among lines belonging to different heterotic groups compared to those calculated from lines of
the same heterotic group. Cluster analysis based on GDs revealed associations among lines which agree with expectations based
on pedigree information. The GD values of the 78 F1 crosses were partioned into general (GGD) and specific (SGD) components. Correlations of GD with F1 performance for grain yield were positive but too small to be of predictive value. The correlations of SGDs, particularly
those based on AFLP data, with specific combining-ability effects for yield may have a practical utility in predicting hybrid
performance.
Received: 15 August 1997 / Accepted: 19 September 1997 相似文献
53.
AFLP技术运用于小麦种子超干燥保存遗传完整性的初探 总被引:4,自引:0,他引:4
小麦种子被干燥和超干燥至9.0%,8.0%,7.0%,6.0%,5.0%,4.0%后,密封包装于江西南昌常温保存。保存五年后,发芽结果表明,小麦种子于亚热带地区常温保存,必须先经过干燥密封包装。种子最适含水量介于7.0%~9.0%之间。不同品种阃有差异。种子经发芽生长至三叶一心期,取幼苗(茎与叶),用AFLP分子技术对其单株及20株的混合样品进行遗传稳定性鉴定。结果表明,每对引物的AFLP图谱谱带丰富,不同引物的清晰带有26至52条,不同品种间差异带在3至6条。同一品种不同的含水量之间AFLP图谱谱带整齐划一,未见明显差异。同一含水量不同混合样品或单株样品间也未见差异,表明小麦种子经干燥、超干燥后于亚热带地区(江西南昌)常温保存五年后。在AFLP分子水平上未见遗传变异。同时本研究也为贮藏种子的遗传完整性研究提供了一个新的思路。 相似文献
54.
55.
A. M. Chèvre F. Eber A. Baranger G. Hureau P. Barret H. Picault M. Renard 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(1-2):90-98
Gene flow from glufosinate-resistant transgenic oilseed rape to wild radish was studied over two backcross generations. Under field conditions,?seed production from oilseed rape-wild radish F1 hybrids due to pollination by wild radish was always low: on average 0.12 and 0.78 seeds per 100 flowers and per plant, respectively. The cytogenetics of the resulting «BC1» plants can be explained in the main by three different genomic constitutions: either ACRrRr, 2n=37, ACRr, 2n=28 (the same chromosome number as the mother plant), or by the amphidiploid AACCRrRr, 2n=56. The probability of gene exchange through chromosome pairing was high only in plants with 2n=28 or 37 chromosomes. Due to the viability of unreduced or partially reduced female gametes, most of the «BC1» plants (81.9%) were Basta resistant whereas the analysis of oilseed rape specific loci indicated that their transmission varied with the locus. In spite of low male fertility (8.7%), an improvement of the female fertility over the F1 hybrids was observed with an average production of 1.4 and 11 seeds per 100 flowers and per plant, respectively. At the following «BC2» generation, the bar gene transmission (57.2% of Basta-resistant plants) decreased as did the chromosome number, with a majority of plants having between 24 and 27 chromosomes, with 10.5% similar to wild radish (2n=18). The lower the chromosome number, the better the fertility of the «BC2» plants. On average, 7.9 and 229.3 seeds per 100 flowers and per plant were produced. Gene-flow assessment is discussed based on these data. 相似文献
56.
The computer program structure for assigning individuals to populations: easy to use but easier to misuse 下载免费PDF全文
Jinliang Wang 《Molecular ecology resources》2017,17(5):981-990
The computer program Structure implements a Bayesian method, based on a population genetics model, to assign individuals to their source populations using genetic marker data. It is widely applied in the fields of ecology, evolutionary biology, human genetics and conservation biology for detecting hidden genetic structures, inferring the most likely number of populations (K), assigning individuals to source populations and estimating admixture and migration rates. Recently, several simulation studies repeatedly concluded that the program yields erroneous inferences when samples from different populations are highly unbalanced in size. Analysing both simulated and empirical data sets, this study confirms that Structure indeed yields poor individual assignments to source populations and gives frequently incorrect estimates of K when sampling is unbalanced. However, this poor performance is mainly caused by the adoption of the default ancestry prior, which assumes all source populations contribute equally to the pooled sample of individuals. When the alternative ancestry prior, which allows for unequal representations of the source populations by the sample, is adopted, accurate individual assignments could be obtained even if sampling is highly unbalanced. The alternative prior also improves the inference of K by two estimators, albeit the improvement is not as much as that in individual assignments to populations. For the difficult case of many populations and unbalanced sampling, a rarely used parameter combination of the alternative ancestry prior, an initial ALPHA value much smaller than the default and the uncorrelated allele frequency model is required for Structure to yield accurate inferences. I conclude that Structure is easy to use but is easier to misuse because of its complicated genetic model and many parameter (prior) options which may not be obvious to choose, and suggest using multiple plausible models (parameters) and K estimators in conducting comparative and exploratory Structure analysis. 相似文献
57.
摘要 目的:探讨高压氧联合高频重复经颅磁刺激(rTMS)对重型颅脑损伤后意识障碍(DOC)患者促醒作用、神经电生理和脑损伤标志物的影响。方法:选取2021年6月~2023年6月期间安徽中医药大学附属六安医院收治的的80例重型颅脑损伤后DOC患者。根据随机数字表法分为对照组(n=40,高压氧治疗)和观察组(n=40,高压氧联合高频rTMS治疗)。对比两组疗效、促醒作用、神经电生理和脑损伤标志物水平变化情况。结果:观察组的临床总有效率高于对照组(P<0.05)。两组治疗4周后修订的昏迷恢复量表(CRS-R)、格拉斯哥昏迷量表(GCS)评分升高,观察组高于对照组(P<0.05)。两组治疗4周后脑干听觉诱发电位(BAFP)、四肢体感诱发电位(SEP)、脑电图(EEG)分级有所改善,观察组改善效果优于对照组(P<0.05)。两组治疗4周后髓鞘碱蛋白(MBP)、神经元特异性烯醇化酶(NSE)、S100β蛋白下降,观察组低于对照组(P<0.05)。结论:高压氧联合高频rTMS治疗可有效促醒重型颅脑损伤后DOC患者,还可改善神经电生理活动,减轻脑损伤程度。 相似文献
58.
The appropriateness of the Amplified Fragment Length Polymorphism (AFLP) technique for investigating Chondrus crispus Stackhouse populations in the Maritime Provinces of Canada was assessed. The AFLP procedure was first subjected to reproducibility
testing and three shortcomings were noted: 1) failure to reproduce band intensity between replicate runs for the same individual
and primer pair; 2) failure of some bands to replicate; 3) lack of reproducibility for complete replicate runs for some individuals
and primer pairs. In the last-mentioned case, the lack of reproducibility resulted in characteristic electropherograms indicative
of weak reactions. These weak runs can be attributed to poor restriction digest/ligation reactions and/or substandard PCR,
these failures ultimately resulting from low and inconsistent DNA quality. We recommend that reproducibility testing should
be completed routinely in studies using the AFLP technique. In the current work, only fragments and individuals that gave
reproducible results were used in subsequent analyses. The AFLP method resulted in highly variable markers within and between
the populations of C. crispus included in this investigation, which prevented successful resolution of population structure. This situation could result
from a lack of suitability for AFLP markers in population genetic studies, and/or too extensive genetic variation for C. crispus populations to be discerned by the AFLP technique. These two possible explanations are discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
59.
Molecular tools were used to evaluate the hybrid status of a specimen with intermediate colour pattern between Halichoeres bivittatus and Halichoeres garnoti from Belize. Phylogenetic analyses of the two species, eight Halichoeres species from new and old world lineages and two outgroups showed that the study species are closely related and that H. garnoti is the maternal contributor to the putative hybrid specimen, based on partial mitochondrial COI data. Direct sequencing of
Intron 1 of the nuclear ribosomal protein S7 identified H. bivittatus as sister to H. garnoti with the putative hybrid specimen in an intermediate position, due to heterozygosity at nucleotides alternatively fixed in
the two putative parent species. This is consistent with the hybrid status of the specimen, with parental contributions from
both H. garnoti and H. bivittatus. These results, combined with no evidence of introgression between the two parent species (based on the mtDNA and the single
investigated nuclear marker) and the biogeography and ecology of these species suggests that this is a rare event with minimal
evolutionary implications. 相似文献
60.
Sertoli cells play a key role in spermatogenesis by supporting the germ cells throughout differentiation. The isolation of Sertoli cells is essential to study their functions. However, the close contact of Sertoli cells with other testicular cell types and the high proliferation of contaminating cells are obstacles to obtain pure primary cultures. Current rodent Sertoli cell isolation protocols result in enriched, rather than pure Sertoli cells. Therefore, novel approaches are necessary to improve the purity of Sertoli cell primary cultures. The goal of this study is to obtain pure mouse Sertoli cells using lineage tracing and fluorescence‐activated cell sorting (FACS). We bred the Amh‐Cre mouse line with tdTomato line to generate mice constitutively expressing red fluorescence specifically in Sertoli cells. Primary cultures of Sertoli cells isolated from prepubertal mice showed that 79% of cells expressed tdTomato, as evaluated by fluorescence microscopy and flow cytometry; however, nearly all adherent cells were positive for vimentin. Most of the tomato‐negative cells expressed α‐smooth muscle actin (α‐SMA), a peritubular myoid cell marker, but double‐negative populations were also present. These findings suggest that vimentin lacks Sertoli cell‐specificity and that α‐SMA is not adequate to identify all of the contaminating cells. Upon FACS sorting; however, virtually 100% of the cells were tdTomato positive, expressed vimentin, but not α‐SMA. Prepubertal mice yielded a higher number of Sertoli cells compared to adults, but both could be adequately sorted. In conclusion, our study shows that lineage tracing and sorting is an efficient strategy for acquiring pure populations of murine Sertoli cells. 相似文献