Role of IP3R in LH-EGFR-induced mouse oocyte meiotic resumption

AIM: To explore the effect of inositol 1, 4, 5-trisposphate receptor (IP₃R) in luteinizing hormone-epidermal growth factor receptor (LH-EGFR)-induced oocyte meiotic resumption. METHODS: Models of mouse cumulus-oocyte complexs (COCs) culture and follicle culture in vitro were generated to study the effects of 2-aminoethyl diphenyl borate (2-APB) and heparin (IP₃R specific inhibitors) on LH/EGF-induced oocyte meiotic resumption and EGF-induced cumulus cell expansion. Real-time PCR was used to detect the mRNA expression of cumulus expansion-related factors. The changes of the intracellular calcium level were monitored using Fluo 3-AM, and the cGMP level was measured by ELISA. RESULTS: The inhibitors of IP₃R, 2-APB and heparin, dramatically reversed EGF-induced oocyte maturation (P<0.05) and decreased cGMP levels in COCs (P<0.05). In addition, 2-APB and heparin reversed EGF-induced cumulus expansion, and significantly inhibited EGF-induced cumulus expansion-related factor expression (P<0.05). The activation of IP₃R increased intracellular calcium level, and the study found that 2-APB and heparin dramatically reversed EGF-induced elevation of calcium level in cumulus cells (P<0.05). Follicular culture in vitro showed that 2-APB and heparin significantly reversed the LH-induced oocyte maturation (P<0.05). CONCLUSION: LH-EGFR signaling pathway increases calcium level in cumulus cells through IP₃R, resulting in meiotic resumption.     

花前氮亏缺对水稻叶片氮代谢酶活性的影响

以籼型杂交稻中浙优1号和籼粳型杂交稻甬优12为材料,试验分析了花前不同时期氮亏缺处理对水稻叶片氮代谢酶活性的影响。结果表明,花前氮亏缺导致植株上3叶氮浓度、NR、GS、GOGAT、GOT和GPT酶活性大幅下降,GDH活性显著增长,且各叶位对花前氮亏缺敏感度总体上表现为剑叶倒2叶倒3叶;破口期亏氮对籼型杂交稻中浙优1号上3叶氮同化酶活性的影响远小于减数分裂期处理,与之相比,籼粳杂交稻甬优12对破口期亏氮胁迫仍较敏感,表明中浙优1号植株氮代谢酶的亏氮敏感性由减数分裂期至破口期逐步下降,对土壤速效氮的需求同步降低,甬优12则对土壤供氮存在更高需求。     

杉木花粉母细胞减数分裂的细胞学特性及异常现象的观察

用2种荧光染料(CMA、DAPI)对3个杉木无性系花粉母细胞减数分裂的染色体进行荧光染色,发现在减数分裂的花粉母细胞的各个时期,染色质或染色体上有CMA荧光亮点出现,而无DAPI荧光亮点.在杉木花粉母细胞减数分裂过程中观察到一些异常细胞学行为,即单价体和多价体、染色体桥、滞后染色体、不均等分离、微核等异常现象. 对杉木花粉的生活力差异与杉木小孢子形成过程中减数分裂异常现象之间的关系进行了讨论.     

生殖细胞早期发生与减数分裂启动调节机制的研究进展

卵巢性生殖疾病发生的主要原因之一是卵子发生过程中减数分裂发生或染色体分离异常。为了更好地进行这些生殖疾病的诊断和治疗,需要充分地了解个体发育的生物学过程中及关键时间点。鉴于此,本文主要阐述了哺乳动物生殖细胞早期发生和减数分裂启动的生理过程,介绍生殖细胞的出现、迁移、性别分化和减数分裂的整个过程。深入了解卵母细胞发生过程将为利用体外发育来源的卵母细胞治疗卵巢性生殖疾病,克服女性不孕、卵巢早衰等重大疾病提供一定的理论支持。     

四种栽培棉合成的四元杂种F1细胞遗传学研究

用(亚洲棉×草棉)F1进行染色体加倍,再与(陆地棉×海岛棉)F1进行杂交,产生亚洲棉、草棉、陆地棉和海岛棉四元杂种.对四种栽培棉的四元杂种F1花粉母细胞减数分裂各时期染色体行为观察结果表明,四元杂种F1的减数分裂异常,染色体丢失现象普遍,部分染色体不能联会配对,以单价体的形式存在,并出现三价体、四价体、五价体等多价体,在减数分裂的末期形成大量的不正常多分孢子,导致四元杂种F1高度不育.然而,四元杂种F1减数分裂中大多染色体仍能配对,形成环状或棒状二价体,并有较多的三价体、四价体、五价体等多价体,表明四种栽培棉种之间的亲缘关系相对较近,可以通过遗传重组产生综合四个栽培棉种性状的新种质.     

Cytogenetic analyses of sugarcane relatives (Andropogoneae: Saccharinae)

Summary Meiosis was studied in 31 wild Saccharum relatives, including Erianthus (8 clones), Miscanthus (5 clones), Narenga prophyrocoma (1 clone), S. robustum (3 clones), and S. spontaneum (14 clones). Chromosome number for 18 clones confirmed published counts or was typical of the particular species. Chromosome number for seven clones (Djatiroto 2n=58, Molokai 5099 2n=80, SES 84/58 2n=58, SES 114 2n=64, SES 260 2n=64, Taiwan 100 2n=112, and US 57-11-2 2n=60) differed from published counts (2n=112, 86-100, 64, 60, 60, 96, and 30, respectively). Counts were obtained for the first time for six clones (Local escape 2n=96, Nepal 2n=72, NG 77-77 2n=108–112, NG 77-199 2n=166, US 57-60-2 2n=20, and US 68-1-4 2n=38). Bivalent chromosome pairing predominated in all clones. Meiotic irregularity (numeric aberrations, univalents, multivalents, and telophase II micronuclei) tended to be associated with taxonomic grouping and level of polyploidy. Clones in Erianthus, Miscanthus, and Narenga were apparent euploids (2n=20–60) and tended to have fewer meiotic irregularities than Saccharum clones. Differences in level of meiotic stability among taxonomic groups may reflect error in chromosome association and synapsis associated with high chromosome number.     

Interspecific hybridization between Coffea arabica L. and tetraploid C. canephora P. Ex Fr. II. Meiosis in F1 hybrids and back crosses to C. Arabica

Summary Melosis was studied in Coffea arabica, in induced tetraploid C. canephora, in their F₁ hybrid (arabusta hybrid) and in backcross generations of the hybrid with C. arabica as recurrent parent. Irregularities were observed, consisting of univalents (especially in the arabusta hybrid), multivalents (especially in tetraploid C. canephora) and uneven distribution of chromosomes at first anaphase. Chromosome distribution was improved by backcrossing. Meiotic irregularities wer negatively correlated with pollen fertility.     

Metaphase-I analysis of a Triticum aestivum x T. monococcum hybrid by the C-banding technique

Summary The meiotic pairing behaviour at metaphase I of a Triticum aestivum×Triticum monococcum hybrid has been studied by means of the C-banding technique to ascertain the homology between the chromosomes in the A genome of the two species. The technique allowed the A and B genome chromosomes and the 2D, 3D and 5D chromosomes to be identified. Differences in the level of chromosome pairing in the A genome were noted. The T. monococcum 4A chromosome did not pair with any of the T. aestivum chromosomes in any of the metaphase I cells analysed. Two reciprocal translocations between the 2B and 2D chromosomes on one side and the 2A and 3D on the other side have been identified. The usefulness of the C-banding technique in the study of chromosome homology among species related to wheat is discussed.     

Meiosis and pollen grain viability in Helianthus mollis,Helianthus salicifolius,Helianthus maximiliani and their F1 hybrids with cultivated sunflower

Three diploid perennial sunflower species are useful for variety improvement: Helianthus mollis, because of sessile leaves, H. salicifolius, because of a high oil concentration, and H. maximiliani, a potential source of resistance to Sclerotinia sclerotiorum. The crossability of these species to cultivated sunflower was examined.Hybrids were obtained from eight combinations, with 3–15 F₁ plants per combination. The F₁'s exhibited the dominant phenotype of the wild species. Pollen viability varied between 32.1 and 69.9%. Meiosis was irregular in the F₁ hybrids. At diakinesis, bivalents (62.7–97.9% of meiocytes), univalents (0–31.23%), and multivalents (3.84–7.68%) were detected. At anaphase I, chromosome bridges were detected in 6.77 to 11.44% of meiocytes. Fast chromosomes in metaphase I, and lagging chromosomes in anaphase I and telophase II were evidenced in a high percentage of meiocytes.     

Genomic Relationships of Triticum sharonense with Other S-Genome Diploid Triticum Species

Triticum sharonense was hybridized with autotetra-ploid T. speltoides, T. longissimum and T. bicorne. Meiotic analysis of these hybrids showed that T. sharonense is almost equally related to both T. speltoidcs and T. longissimum, while it is comparatively distant from T. bicorne. Therefore, this study does not support treating T. sharonense as a subspeies or variety of T. lottgissimum.