两种邻域分布石鸡间的线粒体DNA渗透

采用聚合酶链式反应(PCR)和mtDNA细胞色素b基因314 bp核苷酸序列测定等方法,证明在大石鸡与山石鸡的异域种群之间存在广泛的差异.然而采自六盘山地区与山石鸡相邻分布的大石鸡种群的样本中却存在山石鸡的mtDNA基因型,这种基因型与其它大石鸡个体的基因型有4.4%核苷酸差异.在与山石鸡相邻分布的大石鸡种群中有25%的个体具有山石鸡的mtDNA基因型,而采自六盘山接触地带以西约200 km处兰州市郊的大石鸡标本中则没有发现这种基因型.此发现支持山石鸡和大石鸡之间存在或曾经有过杂交的假设.作者还提出了一种限制性内切酶分析方法,可以快速地检测这种mtDNA基因型.在此之前还没有过关于山石鸡和大石鸡之间基因流动的报道.     

渐渗杂交的研究进展及其理论实践意义

渐渗杂交(Introgressive hybridization)一词最早是由Anderson和Hubricht 在1938年通过植物杂交研究提出,指两物种的杂交后代与亲本之一或双亲反复回交,把某一亲本的性状带至另一亲本.本文阐述了渐渗杂交的定义发展,各物种渐渗杂交的研究进展以及相关研究方法的发展.相关研究文献主要讨论了这样一些问题:渐渗杂交形成机制的探讨;基因渗透程度;在进化上的重要意义;对生物多样性的影响以及对物种保护上的贡献;作物育种上的应用等.最后从进化、生物多样性、作物育种等角度讨论了渐渗杂交的理论实践意义,提出了一些关于渐渗杂交有待于进一步深入研究的建议.     

利用EST-SSR分子标记检测鹅掌楸种间渐渗杂交

引进物种常与本土近缘种间发生杂交而导致基因渐渗,进而影响本地种的遗传系统。鹅掌楸(Liriodendron chinense)为我国濒危树种之一,鹅掌楸种间杂交可配性高,近10年来随着北美鹅掌楸(L.tulipifera)的大量引种及杂交鹅掌楸的繁殖推广,鹅掌楸种间发生基因渐渗的可能性大大增加。本文以5个包含鹅掌楸、北美鹅掌楸、杂交鹅掌楸的人工混交林为实验群体,每个群体包含19–130个成年个体及60–117个自然更新小苗或半同胞子代,利用EST-SSR(simple sequence repeat based on expressed sequence tag)分子标记对各子代群体进行亲本分析,探究鹅掌楸种间自然交配方式以检测鹅掌楸种间渐渗杂交;同时,以亲子群体等位基因频率的回归系数作为渐渗系数,定量分析鹅掌楸属种间基因渐渗。结果表明:在研究的5个鹅掌楸混生群体中,均检测到种间渐渗杂交,且渐渗杂交的方向与效应大小在不同群体间有差异。研究还发现,各树种基因渐渗程度与其种群个体数有关,种群个体数越多,其渐渗能力越强。据此,我们还探讨了鹅掌楸种质资源保护策略。     

异源DNA导入水稻诱发活跃反转子Tos17发生可遗传DNA甲基化变异(英文)

用水稻(OryzasativaL.)内源反转座子Tos17为探针,经Southern杂交在5种含有野生稻(ZizanialatifoliaGriseb.)(菰)DNA片段的水稻渐渗杂交系中检测到了可遗传DNA甲基化变异。在分析的4种甲基化敏感限制性内切酶中,每种酶切都发生了亲本杂交片段的消失和新片段的出现。发生甲基化变异的位点包括对称和不对称的胞嘧啶碱基,也包括腺嘌呤碱基。序列分析表明,与水稻亲本比较,所研究的5种渐渗杂交系在Tos17的2个重要区域(5'-LTR和RT)均未发生序列变异。但甲基化敏感-序列特异性PCR分析证实,每种渐渗杂交系在这2个区域内均发生了广泛的DNA甲基化变异。而且,在2种渐渗杂交系中发现5'-LTR和RT区域的甲基化变异存在协同性。甲基化变异可稳定遗传给后代。因为已有的研究表明,在这5种渐渗杂交系中异源DNA导入均导致了Tos17的激活和转座,因此可以推测DNA甲基化在调控Tos17活性中可能具有一定作用。但反转座子激活和甲基化变异之间的确切关系尚有待进一步研究。     

异源DNA导入水稻诱发活跃反转子Tos17发生可遗传DNA甲基化变异

用水稻(Oryza sativa L.)内源反转座子Tos17为探针,经Southern杂交在5种含有野生稻(Zizania latifolia Griseb)(菰)DNA片段的水稻渐渗杂交系中检测到了可遗传DNA甲基化变异.在分析的4种甲基化敏感限制性内切酶中,每种酶切都发生了亲本杂交片段的消失和新片段的出现.发生甲基化变异的位点包括对称和不对称的胞嘧啶碱基,也包括腺嘌呤碱基.序列分析表明,与水稻亲本比较,所研究的5种渐渗杂交系在Tos17的2个重要区域(5'-LTR和RT)均未发生序列变异.但甲基化敏感-序列特异性PCR分析证实,每种渐渗杂交系在这2个区域内均发生了广泛的DNA甲基化变异.而且,在2种渐渗杂交系中发现5'-LTR和RT区域的甲基化变异存在协同性.甲基化变异可稳定遗传给后代.因为已有的研究表明,在这5种渐渗杂交系中异源DNA导入均导致了Tos17的激活和转座,因此可以推测DNA甲基化在调控Tos17活性中可能具有一定作用.但反转座子激活和甲基化变异之间的确切关系尚有待进一步研究.     

异源DNA导入水稻诱发活跃反转子Tosl7发生可遗传DNA甲基化变异

用水稻(Oryza sativa L.)内源反转座子Tosl7为探针,经Southern杂交在5种含有野生稻(Zizania latifolia Griseb．)(菰)DNA片段的水稻渐渗杂交系中检测到了可遗传DNA甲基化变异。在分析的4种甲基化敏感限制性内切酶中,每种酶切都发生了亲本杂交片段的消失和新片段的出现。发生甲基化变异的位点包括对称和不对称的胞嘧啶碱基,也包括腺嘌呤碱基。序列分析表明,与水稻亲本比较,所研究的5种渐渗杂交系在Tosl7的2个重要区域(5′—LTR和RT)均未发生序列变异。但甲基化敏感—序列特异性PCR分析证实,每种渐渗杂交系在这2个区域内均发生了广泛的DNA甲基化变异。而且,在2种渐渗杂交系中发现5′—LTR和RT区域的甲基化变异存在协同性。甲基化变异可稳定遗传给后代。因为已有的研究表明,在这5种渐渗杂交系中异源DNA导人均导致了Tosl7的激活和转座,因此可以推测DNA甲基化在调控Tosl7活性中可能具有一定作用。但反转座子激活和甲基化变异之间的确切关系尚有待进一步研究。     

山羊草(Aegilops)物种作母本与小麦远缘杂交的评价

研究了山羊草不同物种作母本,在不借助胚培等特殊措施的情况下与不含隐性可杂交基因的小麦推广品种杂交、回交及杂种自交情况,结果表明(1)山羊草物种作母本,小麦推广品种作父本进行杂交是一种很有效的方式;山羊草物种作母本容易与小麦进行杂交,但回交和自交较困难;回交与自交相比时,回交容易些;(2)同一物种的不同基因型材料在与小麦杂交、回交及杂种自交时存在大量变异;(3)杂交结实率与以后的回交或自交并不相关,但是杂种的回交和自交之间相关;(4)山羊草物种与小麦杂交、回交及其杂种自交的结实率与其染色体组构成并无明显相关.     

鸡PPAR基因单核苷酸多态与脂肪性状相关的研究

以AA肉鸡和 3个中国地方鸡品种 (石岐杂、北京油鸡、白耳鸡 )为实验材料 ,用 7对引物对PPAR α基因整个编码区用PCR SSCP方法进行了扫描 ,结果发现引物 4扩增片段上有一个C T的单碱基突变 ,使鸡群中表现出 3种基因型 (AA、AB、BB)。统计结果发现 3种基因型在各品种中的分布不一致 ,AA肉鸡同中国地方鸡品种差异很大 ,χ2 独立性检验差异极显著 (P <0 0 1)。将AA肉鸡 3种基因型同腹脂等屠体性状进行方差分析 ,结果表明BB基因型与其他 2种基因型相比有较高的腹脂重和腹脂率 ,同AA型比较差异显著 (P <0 0 5 )。因此推测PPAR α基因可能是影响鸡脂肪代谢的主效基因或与控制该性状的主效基因连锁 ,并且能够用于对鸡脂肪性状进行分子标记辅助选择。     

钙蛋白酶Ⅰ(CAPN1)基因多态性与鸡肉嫩度和屠体性状的相关研究

为了探讨CAPN1基因作为影响鸡肌肉嫩度候选基因的可能性, 寻找与鸡嫩度性状相关的分子标记, 对钙蛋白酶Ⅰ(CAPN1)基因的CDS区进行SNPs 检测, 分析不同基因型在5个优质肉鸡纯品系和3个配套系间分布规律。利用测序和单链构象多态(SSCP)的方法进行SNPs 检测和基因型的分析, 计算等位基因频率、各位点多态信息含量。结果发现2546位(位点A) 处发生点突变由C→T和3535位(位点B)处发生点突变由G→A。各位点的3 种基因型与肉鸡生产性状的最小二乘分析结果表明,各位点的各种基因型个体在肌纤维密度和部分屠体性状指标存在显著差异(P< 0.05)。初步推断CAPN1基因可能是影响鸡嫩度性状潜在的主效基因或与主效基因连锁, 并且这些位点具有成为分子标记的潜在可能。     

通过种质渗入法对控制种间性信息素通讯分化的性信息素基因进行QTL定位

Heliothisvirescens(Hv)和H.subflexa(Hs)性信息素组分在质和量上存在不同,作为理解鳞翅目蛾类种特异性性信息素通讯进化的第一步,Groot等对Hv和Hs2个近缘种进行了杂交和回交,并利用AFLP技术对控制性信息素混合物比例的基因进行了QTL定位。在回交群体1和2(BC1和BC2)里,22号染色体对3种乙酸脂性信息素化合物的产生有强烈的抑制作用,这些乙酸脂性信息素化合物在Hs性腺里存在而在Hv里不存在。在这里,他们描述了如何通过渐渗回交法把Hv22号染色体渗入Hs基因组的。在BC3里选择出带有Hv22号染色体且乙酸脂性信息素化合物比例<3%的雌蛾个…     

Mitochondrial DNA and microsatellite markers evidence a different pattern of hybridization in red-legged partridge (Alectoris rufa) populations from NW Italy

Genetic introgression with exotic genomes represents a major conservation concern for the red-legged partridge (Alectoris rufa, Phasianidae). In particular, massive releases of chukar partridges (Alectoris chukar) and/or red-legged × chukar partridge hybrids for hunting purposes have cast serious doubts on the Italian present-day occurrence of wild A. rufa populations not affected by introgressive hybridization. This study investigates the genetic structure of red-legged partridges populations in two ecologically different areas in Northern Italy. Analysis of maternal mitochondrial DNA and biparental microsatellite markers excluded the presence of hybridization in a typical agricultural habitat where hunting and release of reared birds are strictly banned. By contrast, signs of chukar introgression were detected in a perifluvial habitat unusual for the red-legged partridge in Italy. The present study documents the first red-legged partridge population with no genetic evidences of recent chukar introgression presently living in Italy. We recommend that urgent conservation actions are taken to preserve the genetic integrity of this population from the risk of hybridization with farm-reared birds and to support its long-term conservation.     

光对棉铃虫和烟青虫杂交的影响

【目的】力求建立一种准确鉴定室内棉铃虫Helicoverpa armigera(Hübner)、烟青虫H.assulta(Guenée)及其杂交种的分子技术,探讨棉铃虫和烟青虫杂交的可能。【方法】室内暗期设置0.5 lx黑光灯和白炽灯,测定不同配对模式下3日龄处女棉铃虫和烟青虫的杂交率;筛选可区分室内建立的棉铃虫、烟青虫及杂交种家族的微卫星位点;于架设有黑光灯的温室内释放棉铃虫和烟青虫混合种群,利用微卫星分子标记技术检测子代微卫星位点大小。【结果】两种蛾类在任何一种配对模式下均可杂交,混合种群处理杂交率为2.92%,且均为烟青虫雌蛾与棉铃虫雄蛾配对交配;黑光灯、白炽灯和黑暗条件下杂交率无显著性差异;筛选出的Har SSR1、Har SSR9和Har SSR10在两种蛾类上的等位基因片段大小不一样;两年温室实验共鉴定360头子代,混合种群中未检测到杂交后代。【结论】交配笼中棉铃虫和烟青虫能进行种间杂交,弱光不能提高二者杂交率;混合种群处理只发现一种杂交配对模式,说明了棉铃虫雄蛾的交配竞争能力更强;成功利用微卫星分子标记技术鉴定室内建立的棉铃虫、烟青虫及杂种家族,提供了一种简单准确的分子鉴定手段;两年温室实验未检测到杂交种,说明2种蛾类之间存在着交配前生殖隔离机制。     

Behavioral and morphological asymmetries in chukar Alectoris chukar copulation

Birds often exhibit greater reproductive tract development on the left side than right side. Behavioral evidence from the three species for which data has been published indicates that these species copulate more frequently on the left side of females than on the right side. Missing from the literature are studies that compare asymmetry in copulation behavior to asymmetry in reproductive tract morphology of the same individuals of both sexes within a single species. To better understand the potential for cryptic sexual selection to influence avian copulation, we measured asymmetries in chukar Alectoris chukar copulation using 24 male and 29 female chukar brought into captivity from the wild. Chukar copulated (n=37) more from the left side (n=30) of females than the right side (n=7). The left testis of males was consistently greater in size, mass and volume than the right testis. The left ovary and oviduct of females was consistently functional with no observable development of the right ovary or oviduct. Left-side bias in direction of copulation, larger left testes, and functional left vaginal openings may act in concert to deliver spermatozoa to the oviduct, promoting fertilization.     

Introgression of Alectoris chukar genes into a Spanish wild Alectoris rufa population

In order to detect introgression of other Alectoris genus species into wild populations of Spanish Alectoris rufa, we studied a sample of 93 red-legged partridges (supposed to be A. rufa) captured in the island of Majorca. A set of 31 chukar partridges (Alectoris chukar) from Cyprus and 33 red-legged partridges (A. rufa) from one Spanish farm were also studied to provide suitable populations for comparison. Factorial correspondence analysis on microsatellite genotypes supported a clear distinction of birds from Cyprus, whereas partridges from Majorca and the Spanish farm overlapped in a wide area. The existence of A. chukar mitochondrial DNA in 16 individuals from Majorca indicated introgression into their maternal lineage even if their phenotypes were not different from A. rufa. Bayesian inference based on microsatellite analysis indicated a noticeable degree of genetic proximity to A. chukar only for one of these hybrids.     

Fitness consequences of anthropogenic hybridization in wild red-legged partridge (Alectoris rufa, Phasianidae) populations

Hybridization is a widespread phenomenon, which plays crucial roles in the speciation of living beings. However, unnatural mixing of historically isolated taxa due to human-related activities has increased in recent decades, favouring levels of hybridization and introgression that can have important implications for conservation. The wild red-legged partridge (Alectoris rufa, Phasianidae) populations have recently declined and the releases of farm-reared partridges have become a widespread management strategy. The native range of the red-legged is limited to the south-west of Europe (from Italy to Portugal). This species does not breed in sympatry with the chukar partridge (A. chukar), whose range is Eurasian (from Turkey to China). However, red-legged partridges have often been hybridized with chukar partridges to increase the productivity of farmed birds, and game releases may have spread hybrid birds into the wild. In this study, we investigated the fitness (survival and breeding) differences between hybrid and “pure” red-legged partridges in a wild population located in central Spain. Incubation probability was similar in hybrids and “pure” partridges. Hybrid females laid larger clutches than “pure” ones, but hatching success did not differ between hybrid and “pure” partridges. Hybrid birds had lower survival rate than “pure” ones, mainly because of higher predation rates. Our results show that, despite lower survival, hybrid partridges breed in natural populations, so this could increase extinction risk of wild pure partridge populations, through releases of farmed hybrid birds. The consequences of continued releases could be of vital importance for the long term conservation of wild red-legged partridges.     

Widespread hybridization within mound‐building wood ants in Southern Finland results in cytonuclear mismatches and potential for sex‐specific hybrid breakdown

Hybridization and gene flow between diverging lineages are increasingly recognized as common evolutionary processes, and their consequences can vary from hybrid breakdown to adaptive introgression. We have previously found a population of wood ant hybrids between Formica aquilonia and F. polyctena that shows antagonistic effects of hybridization: females with introgressed alleles show hybrid vigour, whereas males with the same alleles show hybrid breakdown. Here, we investigate whether hybridization is a general phenomenon in this species pair and analyse 647 worker samples from 16 localities in Finland using microsatellite markers and a 1200‐bp mitochondrial sequence. Our results show that 27 sampled nests contained parental‐like gene pools (six putative F. polyctena and 21 putative F. aquilonia) and all remaining nests (69), from nine localities, contained hybrids of varying degrees. Patterns of genetic variation suggest these hybrids arise from several hybridization events or, instead, have backcrossed to the parental gene pools to varying extents. In contrast to expectations, the mitochondrial haplotypes of the parental species were not randomly distributed among the hybrids. Instead, nests that were closer to parental‐like F. aquilonia for nuclear markers preferentially had F. polyctena's mitochondria and vice versa. This systematic pattern suggests there may be underlying selection favouring cytonuclear mismatch and hybridization. We also found a new hybrid locality with strong genetic differences between the sexes similar to those predicted under antagonistic selection on male and female hybrids. Further studies are needed to determine the selective forces that act on male and female genomes in these newly discovered hybrids.     

The Application of Fluorescence In Situ Hybridization in Different Ploidy Levels Cross-Breeding of Lily

21 crossing were conducted between Asiatic Lily with different ploidy levels, the results showed that the interploidy hybridization between diploid and tetraploid lilies was not as successful as intraploidy hybridization. Regardless of male sterility, triploid lilies could be used as female parents in the hybridization which the progenies were aneuploidy. 3x×4x crosses could be cultured more successfully than 3x×2x crosses. 45S rDNA was mapped on the chromosomes of seven Lilium species and their progenies using fluorescence in situ hybridization (FISH). FISH revealed six to sixteen 45S rDNA gene loci, and normally the sites were not in pairs. The asymmetry indexes of LA (Longiflorum hybrids × Asiatic hybrids) hybrids was higher than Asiatic hybrids, the evolution degree was LA hybrids > Asiatic hybrids. 45S rDNA distributed variably on chromosome 1-10 and 12 among Asiatic hybrids. Chromosome 1 had invariable sites of 45S rDNA in all Asiatic hybrids, which could be considered as the characteristic of Asiatic hybrids. LA hybrid ‘Freya’ had two sites of 45S rDNA on one homologous chromosome 5, and also it could be found in the progenies. The karyotype and fluorescence in situ hybridization with 45S rDNA as probe were applied to identify the different genotypes of 9 hybrids. Typical chromosomes with parental signal sites could be observed in all the genotypes of hybrids, it was confirmed that all the hybrids were true.     

Masculinization mechanism of hybrids in bitterlings (Teleostei: Cyprinidae)

The sex ratio of bitterling hybrids (subfamily: Acheilognathinae) is often likely to be biased toward males. Artificial hybridization was carried out in 10 species of bitterlings (three genera) in order to elucidate the masculinization mechanism of hybrids. Tanakia himantegus never produced viable F1 hybrids with other species, while hybrids of most other species were viable. In terms of sex ratio and fertility, hybrids were clearly divided into two groups: congeneric Tanakia hybrids and others. Both male and female congeneric Tanakia hybrids were fertile. The sex ratio was nearly 1:1 in all groups of Tanakia hybrids. Except for the congeneric Tanakia hybrids, sterile males appeared predominantly in groups of hybrids in which females were very rare but remained fertile. Sterile intersexes were also observed in five hybrid groups: T. lanceolata (female) x Acheilognathus cyanostigma (male), Rhodeus uyekii (female) x T. lanceolata (male), A. rhombeus (female) x T. lanceolata (male), A. rhombeus (female) x T. limbata (male), and A. tabira tabira (female) x A. cyanostigma (male). In the development of male-predominant hybrids, although hybrid and control (parental species) hatching and survival rates do not differ, no females appeared in hybrids, contrary to the controls. Taking the female heterogametic sex-determining system (ZW) and the phylogenetic relationship of bitterlings into consideration, the masculinization mechanism of hybrids in bitterlings can be explained by the interaction of two sex chromosomes, derived from each parental species. The basic genetic sex in bitterlings is male (ZZ) and the derivative is female (ZW). When parental species are related, the sex phenotype of hybrids coincides with the genetic sex. However, when the parental species differ, the sex phenotype of the ZW genotype is reversed to become male by an abnormal interaction between the Z and W chromosomes. The rare appearance of females and intersexes in male-predominant hybrids might be due to complete or partial functional expression of the W chromosome.     

Genetic analysis of a wild-caught hybrid between non-sister Heliconius butterfly species

Interspecific hybridization occurs regularly in wild Heliconius butterflies, although hybrid individuals are usually very rare. However, hybridization generally occurs only between the most closely related species. We report a rare naturally occurring hybrid between non-sister species and carry out the first genetic analysis of such distant hybridization. Mitochondrial and nuclear genes indicate that the specimen is an F1 hybrid between a female Heliconius ethilla and a male Heliconius melpomene, originating from a group of 13 species estimated to have diverged over 2.5 Myr ago. The presence of such distant natural hybrids, together with evidence for backcrossing, suggests that gene flow across species boundaries can take place long after speciation. Adaptive genes such as those involved in wing coloration could thus be widely shared among members of this highly mimetic genus.