甘蓝型油菜与诸葛菜属间杂种无性系的变异研究

从形态及细胞学两方面对甘蓝型油菜与诸葛菜属间杂种无性系的变异进行了研究。经过长期继代培养后,杂种在形态上越来越偏向母本甘蓝型油菜,而表现出较少的父本诸葛菜性状,但表现出对等双分枝的新性状。经细胞学观察表明,杂种体内杂种细胞比例下降,而甘蓝型油菜细胞比例大幅度上升并远高于核质杂种细胞（具有油菜细胞质与诸葛菜细胞核）的比例,以至较多的甘蓝型油菜染色体组被遗传下去。在该杂种继代培养中还观察到杂种细胞内的染色体消除及体细胞配对现象。     

小麦及缺体小麦与黑麦杂种幼胚愈伤组织在长期继代中的染色体数量变异

对中国春及其６Ａ缺体与黑麦杂种幼胚愈伤组织在长期继代培养过程中愈伤组织的染色体数量进行了统计分析,结果表明：中国春×黑麦和６Ａ缺体×黑麦杂种幼胚愈伤组织在继代培养的前６０ｄ内细胞染色体数目分别稳定在２ｎ＝２８和２７;随着继代培养时间的延长,其染色体数量均发生变异主要表现为染色体数的减少;在第４２０ｄ至５４０ｄ培养期间两个组合愈伤组织丢失染色体的细胞比率明显增加,同时也发现了个别超出正常染色体数的细胞。第５４０ｄ后的愈伤组织染色体数量变异基本维持在这一水平。     

小麦及缺体小麦与黑麦杂种幼胚愈伤组织在长期继代中的染色体数…

对中国春及其６Ａ缺体与黑麦杂幼胚愈伤组织在长期继代培养过程中愈伤组织的染色体数量进行了统计分析,结果表明：中国春×黑麦和６Ａ缺体×黑麦杂种幼胚愈伤组织在继体培养的前６０ｄ内细胞染色体数目分别稳定在２ｎ＝２８和２７;随着继代培养时间的延长,其染色体数量均发生变异主要     

丁香属植物有性杂交试验的研究初报

１９８８－１９８９年在哈尔滨市第三苗圃进行了丁香属（Ｓｙｒｉｎｇａ Ｌ．）植物种间（内）杂交试验。结果表明：⑴不同杂交组合的亲和性差异很大,在试验的１８个杂交组合中有５个杂交组合得到了发育正常的杂种Ｆ１代种子,但结实率不同,其中以白丁香与洋丁香为亲本的杂交组合,无论是正交或反交,杂种Ｆ１代的结实率均达８６％以上,表现出较高的亲和力。而以重瓣洋丁香为母本,白丁香为父本和杂交组合,杂种Ｆ１代结实率仅有     

甘蓝型油菜与蓝花子远缘杂交及双二倍体的合成研究

甘蓝型油菜品种奥罗×蓝花子杂种Ｆ-１,平均配对构型为１２．１Ⅰ＋６．５３Ⅱ＋０．４１Ⅲ＋０．１８Ⅳ＋０．１８Ⅴ,Ａ、Ｃ染色体组与Ｒ染色体间存在配对,它们之间具有一定的同源性。在甘蓝型油菜与蓝花子的杂种Ｆ-１代中,存在一种染色体不配对的减数分裂类型。这一类型中有少量可形成平衡的不减数配子。提供了油菜与蓝花子远缘杂种回交结实的细胞学根据。在ＭＳ＋０．２ｍｇ／ＬＮＡＡ＋３ｍｇ／ＬＢＡ＋１ｇ／Ｌ秋水仙碱＋３０ｇ／Ｌ蔗糖＋８ｇ／Ｌ琼脂的培养基中,接种甘蓝型油菜奥罗与蓝花子的杂种Ｆ-１进行加倍处理,经快速繁殖后,获得大量的染色体数为２ｎ＝５６的双二倍体幼苗。上述双二倍体自交结实,在减数分裂中绝大多数细胞形成２８个二价体,个别形成２６个二价体和１个四价体。上述技术在油菜与蓝花子远缘杂交中首次解决了用常规方法不易获取远种杂种稳定双二倍体的难题。甘蓝型油菜品种Ａｌｔｅｘ×蓝花子杂种Ｆ-１代,长时间的快速繁殖后,出现了染色体丢失和加倍,有形成１９条染色体的配子回复到甘蓝型油菜染色体组成的趋势。在油菜远缘杂种中发现了类似于球茎大麦远缘杂种中染色体丢失的现象。     

普通小麦与簇毛麦属间杂种体细胞无性系的建立及双倍体的合成

通过将常规有性杂交,杂种幼胚愈伤组织培养,杂种试管苗无性繁殖,和杂种愈伤组织及试管苗的染色体加倍等环节相结合,由普通小麦x簇毛麦的极少数杂种幼胚在半年时间内获得了上万株杂种植株,并从中产生了数以千计的双倍体种子。经人工接种鉴定,这个双倍体对白粉病免疫,已被用做小麦抗白粉病育种的中间材料。与此同时,在实验室内还保存着相当数量的杂种愈伤组织和试管苗。前者已经过30余次继代,保存了近2年半的时间,仍具有良好的生长和分化能力;后者也已经历了20几次继代,保存了2年,仍可不断增殖。     

红江橙体胚发生及影响因素的研究

红江橙花后４周的幼果,直径约１ｃｍ左右,这时期的胚珠最适于胚性愈伤组织的诱导。以ＭＴ为基本培养基,加上适当浓度的ＩＡＡ、ＢＡ和ＭＥ可显著提高胚性愈伤组织诱导率。体胚发生,以ＭＴ＋ＩＡＡ０．１ｍｇ１－１＋ＢＡ（ＺＴ）１ｍｇ１－１培养基较好,能诱导产生正常体胚,且频率较高。胚性愈伤组织继代次数对体胚发生也有一定的影响,继代６次以内,胚性愈伤组织具有旺盛产生体胚能力;继代至第９次时,产生体胚的能力明显下降;至第１２代时,不能产生胚状体。成熟胚转换成小植株,以ＭＴ＋ＧＡ２ｍｇ１－１＋ＮＡＡ０．１ｍｇ１－１培养基成苗率最高。     

小麦与高冰草属间体细胞杂交获可育杂种植株

普通小麦（ＴｒｉｔｉｃｕｍａｅｓｔｉｖｕｍＬ．２ｎ＝４２）“济南１７７”与紫外线照射的高冰草（长穗偃麦草Ａｇｒｏｐｙｒｏｎｅｌｏｎｇａｔｕｍ,２ｎ＝７０）原生质体在ＰＥＧ诱导下融合,获杂种再生植株。取杂种子房诱导产生愈伤组织并再生植株,经染色体和同工酶鉴定,它们仍保留杂种性质。其中两株移栽成活并结实,杂种性质也经表型、染色体、同工酶和ＲＡＰＤ分析得到证明。在Ｆ０和Ｆ１代植株根尖细胞中,均发现高频率地存在着染色体断片;从Ｆ２代花粉母细胞减数分裂的染色体数目及行为发现,杂种细胞染色体数目主要分布在１８Ⅱ～２２Ⅱ,染色体断片发生配对及分离,表明它们是小染色体（ｍｉｎｉｃｈｒｏｍｏｓｏｍｅｓ）。Ｆ１及Ｆ２代植株比亲本小麦（“济南１７７”）秆茎粗硬、生长健壮,穗大粒大,已经产生具有优良性状的Ｆ２代穗系     

小麦—黑麦—中间偃麦草三属杂种F1及其花粉植株的细胞遗传学研究

２个小麦－黑麦－中间偃麦草三属杂种Ｆ１的减数分裂行为复杂,中期Ｉ染色体平均每细胞构型为１９．５３Ｉ＋１３．４７ＩＩ＋０．７０ＩＩＩ＋０．０６１Ⅴ和１９．９９Ｉ＋１３．４２ＩＩ＋０．６５ＩＩＩ和０．０４１Ⅴ＋０．０１Ⅴ,后期Ｉ染色体分配不平衡,单价体并不一定排列在赤道板上,产生各种类型的异常四分体。１８株花粉植株染色体组成类型多样,在２个花粉植株中分别观察到端体和等臂染色体。单倍体花粉植株中期Ｉ染色     

节节麦×普通小麦杂种的胚援救和胚愈伤组织再生植株

通过活体-离体胚培养和胚愈伤组织培养有效地克服了节节麦(Aegilops tauschii Cosson.)×小麦(Triticum aestivum L.)杂种幼胚的败育,产生了大量的杂种植株。采用活体-离体胚培技术,节节麦×小麦三个组合杂种幼胚的成苗率为55%,是前人所用传统胚培方法成功率的5—20倍。杂种幼胚在添加有2 mg/L 2,4-D的MS培养基上诱导为愈伤组织,经继代产生全能性愈伤组织,继而分化出再生植株。愈伤组织经继代保存150天仍不丧失分化能力。本文还对两种产生杂种的组织培养方法进行了比较研究。     

Suppression in vivo of human papillomavirus type 18 E6-E7 gene expression in nontumorigenic HeLa X fibroblast hybrid cells.

The E6 and E7 genes of the cancer-associated human papillomavirus (HPV) types 16 (HPV16) and 18 (HPV18) can induce cell immortalization in vitro in normal human keratinocytes. This, however, is not associated with tumorigenicity in vivo. On the other hand, tumorigenicity of HPV18-positive HeLa cervical carcinoma cells can be suppressed by fusion of HeLa cells with normal human keratinocytes or fibroblasts. We have addressed the question of whether suppression of tumorigenicity in HeLa x fibroblast hybrid cells might be due to a reduced ability of these cells to express the HPV18 E6-E7 genes in vivo. Nontumorigenic hybrid cells and tumorigenic hybrid segregants were transplanted as organotypical cultures or injected subcutaneously into immunocompromised mice and were analyzed for HPV18 E6-E7 gene expression by RNA-RNA in situ hybridization. The tumorigenic hybrid cells showed a continuous and invasive growth that was associated with high levels of HPV18 E6-E7 mRNAs at all time points examined. In contrast, the nontumorigenic hybrid cells stopped cell proliferation approximately 3 days after transplantation. At this time they expressed the E6-E7 genes at low levels, whereas at day 2 high expression levels were observed. However, the mRNA levels of the cytoskeletal genes beta-actin and vimentin remained high for at least 14 days, demonstrating that inhibition of growth and of HPV18 E6-E7 gene expression was not due to cell death. These results suggest that growth inhibition of the nontumorigenic HeLa x fibroblast hybrid cells in vivo might be caused by suppression of HPV18 E6-E7 gene expression and are compatible with the idea of an intracellular surveillance mechanism for HPV gene expression existing in nontumorigenic cells.     

Molecular cytogenetic identification and relationship of the artificial intergeneric hybrid between Dendranthema indica and Crossostephium chinense by GISH

Although most of the hybrid embryos aborted at an early developmental stage, a 2n = 27 true intergeneric hybrid between Dendranthema indica (L.) Des Moul (2n = 36) as ♀ and Crossostephium chinense (L.) Makino (2n = 18) as ♂ was produced following pollination and ovule rescue. The morphology of the resulting adult putative hybrid and the two parents differed significantly from one another in seven of the nine traits measured, the exceptions being leaf width and leaf length, for which the putative hybrid was indistinguishable from the maternal plant. Genomic in situ hybridization experiments were able to successfully distinguish the genomic origin of both mitotic and meiotic metaphase chromosomes in the hybrid. In addition, the 18 D. indica chromosomes were paired as bivalents at meiotic metaphase in the hybrid.     

Newcastle Disease Virus-Specific RNA: Polyacrylamide Gel Analysis of Single-Stranded RNA and Hybrid Duplexes

Newcastle disease virus-specific [(3)H]uridine-labeled 18S RNA was resolved by polyacrylamide gel electrophoresis into several components with molecular weights from 450,000 to 840,000. The analysis of 35 and 24S virus-specific RNA also revealed several components in each sedimentational class. The conversion of 18S RNA into double-stranded form by hybridization with an excess of unlabeled virion RNA improved the resolution in polyacrylamide gels and revealed at least six distinct components. The same six classes of hybrid duplexes were revealed when (32)P-labeled 50S virion RNA was hybridized with an excess of 18S RNA. The applicability of polyacrylamide gel electrophoresis of hybrid duplexes to the analysis of viral genome structure is discussed.     

向日葵rRNA基因克隆及其染色体定位研究

该研究以内葵杂3号三交种为材料,采用同源序列法克隆了5SrRNA和18SrRNA基因并进行了序列测定,测得片段长度分别为515bp和1808bp。以5SrRNA、18SrRNA和45SrRNA基因为探针,分别与内葵杂3号三交种染色体进行荧光原位杂交（FISH）分析。结果表明：45SrRNA和18SrRNA基因均得到3对杂交信号且位点分布相同,分别位于第3对和第10对染色体及第2对随体染色体的短臂末端;5SrRNA基因的信号位点共有2对,分布在第7对和第10对染色体短臂端部。     

Mobilization of closely related plasmids pUB110 and pBC16 by Bacillus plasmid pXO503 requires trans-acting open reading frame beta.

Genetic analysis of the closely related nonconjugative plasmids pUB110 and pBC16 has demonstrated that the open reading frame beta (ORF-beta) region in pUB110 and the corresponding homologous region in pBC16 are essential for mobilization of these plasmids by pLS20 or its derivatives. Deletions in this region or insertions that interrupted ORF-beta severely impaired or eliminated the mobilization of pUB110::pUC18 and pBC16::pUC18 hybrids. In contrast, a hybrid in which pUC18 was inserted into pBC16 at a point outside ORF-beta transferred at a frequency comparable to that of intact pUB110 or pBC16 (10(-4) transcipients per donor cell). The defect of most transfer-deficient (Mob-) hybrid plasmids could be complemented by an intact sister plasmid (i.e., pBC16 for pUB110::pUC18 Mob- hybrids). The inability to complement certain constructs suggested that the origin of transfer might be located in an area 5' to ORF-beta. Furthermore, cloning the region 5' to ORF-beta onto a nonmobilizable pC194::pUC18 construct resulted in a hybrid plasmid, pUCCoriTBC16, that could be mobilized with complementation. These results indicate that mobilization of pUB110 and pBC16 by conjugative helper plasmids requires ORF-beta in trans and at least one other region, including the RSA sequence, which presumably functions as an origin of transfer, in cis.     

AN INTERGENERIC HYBRID IN THE SAXIFRAGACEAE: EVIDENCE FROM RIBOSOMAL RNA GENES

The tandemly repeated multigene families encoding the 5S and 18S-25S ribosomal RNAs were studied at the restriction enzyme level in Tolmiea menziesii, Tellima grandiflora, and in a putative intergeneric hybrid. Using restriction endonucleases that cut once per repeat, the repeat lengths of the 5S and 18S-25S ribosomal genes were estimated. The 5S ribosomal gene repeat length is approximately 480 and 450 base pairs, respectively, in Tolmiea and Tellima. The repeat length of the 18S-25S ribosomal genes varied from 11–13 kb in Tolmiea, and was only about 9 kb in Tellima. The putative hybrid combined the repeat lengths of both Tolmiea and Tellima for both the 5S and the 18S-25S ribosomal genes. These data substantiate the occurrence of natural hybridization between Tolmiea and Tellima. For both the 5S and 18S-25S gene experiments, the hybrid appears to contain fewer repeats corresponding to Tolmiea than to Tellima.     

A hybrid Azotobacter vinelandii-Clostridium pasteurianum nitrogenase iron protein that has in vivo and in vitro catalytic activity

Site-directed mutagenesis and gene replacement procedures were used to construct a mutant strain of Azotobacter vinelandii which expresses a hybrid nitrogenase Fe protein. This hybrid Fe protein has its carboxyl-terminal 18 residues replaced with the 5 analogous residues from the Clostridium pasteurianum Fe protein sequence. The hybrid Fe protein is 13 amino acids smaller than the wild-type A. vinelandii Fe protein and has a net loss of 4 negatively charged residues, resulting in a change in size and charge. The strain which produces the hybrid Fe protein remained capable of diazotrophic growth, albeit at a reduced rate. Also, the purified hybrid Fe protein exhibited a maximum activity about one-half that of native Fe protein. These results demonstrate that the tight, inactive complex which is formed when A. vinelandii MoFe protein and C. pasteurianum Fe protein are mixed in heterologous reconstitution experiments cannot be accounted for only by differences in the A. vinelandii and C. pasteurianum Fe protein primary sequences located at their respective carboxyl termini.     

Intermolecular hybridization of 5S rRNA with 18S rRNA: identification of a 5'-terminally-located nucleotide sequence in mouse 5S rRNA which base-pairs with two specific complementary sequences in 18S rRNA.

Eukaryotic 5S rRNA hybridizes specifically with 18S rRNA in vitro to form a stable intermolecular RNA:RNA hybrid. We have used 5S rRNA/18S rRNA fragment hybridization studies coupled with ribonuclease digestion and primer extension/chain termination analysis of 5S rRNA:18S rRNA hybrids to more completely map those mouse 5S rRNA and 18S rRNA sequences responsible for duplex formation. Fragment hybridization analysis has defined a 5'-terminal region of 5S rRNA (nucleotides 6-27) which base-pairs with two independent sequences in 18S rRNA designated Regions 1 (nucleotides 1157-1180) and 2 (nucleotides 1324-1339). Ribonuclease digestion of isolated 5S rRNA:18S rRNA hybrids with both single-strand- and double-strand-specific nucleases supports the involvement of this 5'-terminal 5S rRNA sequence in 18S rRNA hybridization. Primer extension/chain termination analysis of isolated 5S rRNA:18S rRNA hybrids confirms the base-pairing of 5S rRNA to the designated Regions 1 and 2 of 18S rRNA. Using these results, 5S rRNA:18S rRNA intermolecular hybrid structures are proposed. Comparative sequence analysis revealed the conservation of these hybrid structures in higher eukaryotes and the same but smaller core hybrid structures in lower eukaryotes and prokaryotes. This suggests that the 5S rRNA:16S/18S rRNA hybrids have been conserved in evolution for ribosome function.