The Development of Gynoecium After Anthesis and Fertilization in Eleutherococcus brachypus (Araliaceae)

Eleutherococcus brachypus Harms. is a protandrous plant because the female gametophyte delays its maturation until the fifth day after anthesis and pollen shelling. On the fifth day after anthesis, about 57.69% of the embryo sacs matured and the rest degenerated or failed to develop. Fertilization began in the embryo sac on the fifth day. On the tenth day fertilization took place in 53.37 % of the total of embryo sacs. The stigma became receptible after 3 to 4 days of anthesis. It took 2 to 3 days from the germination of pollen grains on stigma to the fusion of male and female nuclei. The process of fertilization in E. brachypus is not different from most other angiosperms. It belonged to the type of premitotic syngamy. The observations and statistical analysis were made on the number feature of male and female nucleoli in the zygote. The result indicated that it took three days or so from the appearance of male nucleolus in the zygote to its fusion with the female nucleotus. Refering to the number of free nuclei of the endosperm, the fusion of male and female nucleoli in most of the zygotes occurred in the stage of 32 to 128 nuclei of the endosperm. Most zygotes con-tained a big nucleolus resulting from the fusion of male and female nucleolus and proceeding to mitosis. A few without fusion could also proceed to the mitotic stage. Features of multiple sperms entering the embryo sac or entering the egg cell and the degeneration of mature embryo sacs were observed as well. The sign of the termination of fertilization in angiosperms was discussed.     

受精前后烟草卵细胞内玉米素和三类酸性植物激素分布的免疫金电镜观察

用胶体免疫金电镜技术观察了受精前后烟草（Nicotianatabacumvarmacrophylla）卵细胞内玉米素（t－Z）、GA7与GA4、（＋）ABA与IAA分布的变化。受精前卵细胞内有大量t－Z,主要位于细胞核、内质网与线粒体上;与卵细胞相邻的助细胞合点端及中央细胞珠孔端亦有较多t-Z。受精后,合子与宿存助细胞t－z显著减少,正加厚的合子细胞壁中有t－Z分布。未受精卵细胞内GA7与GA4及（＋）ABA减少,IAA更少。合子内GA7与GA4及（＋）ABA略有增加,IAA仍然很少。初步讨论了上述植物激素与受精作用的关系。     

Natural revegetation on forest topsoil and subsoil along roadsides in boreal forest

Questions: Does natural revegetation from indigenous soil improve the restoration success of roadside areas? What are the effects of topsoil, subsoil and fertilization on natural revegetation? Location: Akershus county, SE Norway (10°25′ E, 59° 44′ N). Methods: We used a recently constructed road through a boreal coniferous forest for a three year (2000–2002), fully replicated revegetation experiment (six replications). Treatments were soil type (two levels; one topsoil and one subsoil type) and fertilization (two levels; NPK and unfertilized control). Ordination methods, constrained ordination methods as well as univariate statistical methods, such as Wilcoxon's signed‐rank test and correlation analysis, were used to assess the relative importance and significance of treatments on the plant species composition. Results: There was no fertilization effect on species composition. The species composition on both soil types was stabilised by the second year. The species dominating the topsoil were more in accordance with the indigenous vegetation than was the case on the subsoil. The significant difference in species composition among blocks, persisting for the entire study period, indicated that local factors are important determinants of the outcome of revegetation. Conclusions: Unfertilized topsoil provides a revegetation result in better accordance with the indigenous vegetation than does subsoil.     

Porcine sperm zona binding ability as an indicator of fertility

The escalated use of artificial insemination in swine has increased the importance of determining fertility of a semen sample before it is used. Multiple laboratory assays have been developed to assess fertilizing potential but they have yielded inconsistent results. This experiment sought to determine the relationship between in vitro competitive zona binding ability and in vivo fertility based on heterospermic inseminations and paternity testing. The zona pellucida binding ability and fertility of sperm from 15 boars was assessed by comparing sperm from one boar with sperm from other individual boars in a pairwise fashion using four ejaculates. The relationship of zona binding ability to the mean number of piglets sired per litter for each boar as well as historic fertility data (litter size and farrowing rate) was assessed. The in vitro competition assay consisted of labeling sperm from each boar of the pair with a different fluorophore and incubating an equal number of sperm from each boar in the same droplet with porcine oocytes. The competitive assay was highly effective in ranking boars by zona binding ability (R2=0.94). Paternity testing using microsatellite markers was used to determine the mean number of piglets sired per litter for each boar during heterospermic inseminations. The pairwise heterospermic insemination assay was effective in ranking boar fertility (R2=0.59). Using historical data from these boars, average litter size and farrowing rate were correlated (r=0.81, p<0.001). However, zona binding ability was not significantly correlated with historic farrowing rate data or historic average litter size. Boar sperm zona binding ability was also not correlated significantly with the mean number of piglets sired per litter following heterospermic insemination. But the number of piglets sired by each boar was related to a combination of zona binding ability, sperm motility, normal morphology, acrosomal integrity, and the presence of distal droplets (R2=0.70). These results suggest that zona binding ability is not an accurate predictor of fertilizing ability when used alone; however, when coupled with other sperm assessments, fertility may be predicted successfully.     

Pre-treatment of cattle semen or oocytes with purified milk osteopontin affects in vitro fertilization and embryo development

This study was designed to investigate the effects of pre-incubating cattle spermatozoa or matured oocytes with purified osteopontin (OPN) from cattle milk on fertilization in cattle and embryonic development in vitro. There were two different experiments, semen from six mature Holstein bulls (Bos Taurus) was frozen with different concentrations of OPN (0, 1, 10, 100 μg/mL). Matured cattle oocytes were also pre-treated with OPN (0, 10, 100 μg/mL). In both experiments, pre-treated oocytes or frozen semen, was processed for in vitro fertilization and embryo development. Significantly more oocytes were fertilized when using frozen semen with 10 μg/mL OPN (bull 2 = 85 ± 4% and bull 5 = 78 ± 4%) than without OPN (bull 2 = 75 ± 4% and bull 5 = 69 ± 4%). Those bulls also had increase in cleavage and embryo development (bull 2 = 85 ± 3%, 41 ± 1.9%; bull 5 = 76 ± 2%, 37 ± 1.8%) compared with control (bull 2 = 75 ± 3%, 30 ± 2%; bull 5 = 68 ± 2%, 29 ± 2%). Incubating matured oocytes in 10 μg/mL OPN (87 ± 3%) and 100 μg/mL OPN (88 ± 3%) significantly increased fertilization than control (73 ± 3%). OPN also improve cleavage, and embryo development in treatments with 10 μg/mL OPN (82.7 ± 1.3%; 31.7 ± 1.4%) and 100 μg/mL OPN (85.8 ± 1.3%; 33.8 ± 1.5%) when compared with control (74.1 ± 1.3%; 24.2 ± 1.2%). These data suggest that both, spermatozoa from some bulls and oocytes may associate with OPN, suggesting a facilitory role on in vitro fertilization and embryo development.     

Nitric oxide extends the oocyte temporal window for optimal fertilization

Deteriorating oocyte quality is a critical hurdle in the management of infertility, especially one associated with advancing age. In this study, we explore the role of nitric oxide (NO) on the sustenance of oocyte quality postovulation. Sibling oocytes from superovulated mice were subjected to intracytoplasmic sperm injection (ICSI) with cauda-epididymal spermatozoa following exposure to either the NO donor, S-nitroso-N-acetylpenicillamine (SNAP, 0.23 microM/min), an NO synthase (NOS) inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME, 1 mM), or an inhibitor of soluble guanylyl cyclase (sGC), 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ, 100 microM); while their sibling oocytes were subjected to ICSI either before (young) or after culture for the corresponding period of time (old). Outcomes of normal fertilization, cleavage, and development to the morula and blastocyst stages were compared. Embryos from each subgroup were also subjected to TUNEL assay for apoptosis. A significant deterioration in the ability of the oocytes to undergo normal fertilization and development to morula and blastocyst stages occurred among oocytes aged in culture medium compared to their sibling cohorts subjected to ICSI immediately after ovulation (P<0.05). This deterioration was prevented in oocytes exposed to SNAP. In contrast, exposure to L-NAME or ODQ resulted in a significant compromise in fertilization and development to the morula and blastocyst stages (P<0.05). Finally, apoptosis was noted in embryos derived from aged oocytes and those exposed to L-NAME or ODQ, but not in embryos derived from young oocytes or oocytes exposed to SNAP. Thus, NO is essential for sustenance of oocyte quality postovulation.     

Differential effects of nitrogen and phosphorus enrichment on growth of dwarf Avicennia marina mangroves

The effects of N and P enrichment were investigated on growth and physiological responses of dwarf Avicennia marina mangroves in a hypersaline (58 ± 8 psu) field site in Richards Bay, South Africa. It was hypothesized that at high salinities mangroves allocate more resources to roots than shoots, and that nutrient enrichment with N and P will shift resource allocation to shoots and enhance growth and productivity. In unvegetated areas of the dwarf zone, 1-year-old A. marina seedlings were planted in pots and enriched bimonthly with N, P, N + P, or remained unfertilized (control-C), and growth and morphology of plants were monitored for 2 years. Enrichment with N and N + P shifted resource allocation to shoots from 38% to 55%, and increased dry biomass accumulation by over 500%, compared to the control treatment. In the N and N + P treatments, plant height, number of leaves, leaf chlorophyll content and photosynthesis increased by over 50%, 330%, 30% and 30%, respectively, compared to the C and P treatments. Enrichment with N and N + P increased N concentrations in roots by over 60% (from 1.0 ± 0.1% to 1.6 ± 0.2% of dry mass) and in shoots by over 100% (from 1.3 ± 0.1% to 2.7 ± 02% of dry mass). Plants enriched with P alone were similar to those of the control. This study has demonstrated that dwarf A. marina in Richards Bay is N limited, and that N enrichment shifts resource allocation from roots to shoots and increases growth and productivity.     

黑鲷精子的超低温冻存及DNA损伤的SCGE检测

以0.5 mL的麦细管为冻存管和DMSO为抗冻剂进行超低温冷冻黑鲷精子,对冻精核DNA的损伤情况进行单细胞凝胶电泳（SCGE）检测,其结果表明,以Cortland溶液为稀释液,5%、10%、15%及20%DMSO为抗冻剂的超低温冻存的黑鲷精子活力、受精率与鲜精无显著差异。其中以10%DMSO为抗冻剂的冻存效果最佳,冻精的激活率、运动时间、寿命及受精率分别达（92.91±1.25）%、（39.90±2.70）min、（53.82±2.84）min及（89.35±1.99）%;而以25%及30%DMSO为抗冻剂时,冻精活力及受精率显著下降。SCGE检测结果显示,DMSO浓度为5%、10%、15%及20%时,黑鲷冻精与鲜精的彗星率及损伤系数差异不显著;DMSO浓度为25%及30%时,冻精与鲜精的彗星率及损伤系数差异显著;冻精的彗星率与抗冻剂DMSO浓度成正相关。黑鲷鲜精及冻精核的DNA损伤主要为轻度和中度损伤,重度损伤比例较低,完全损伤仅存在于25%及30%DMSO为抗冻剂的冻精中,且比例低。分析认为,较高浓度的DMSO是引起冻精核DNA损伤的主要原因。     

奥利亚罗非鱼与鳜杂交的受精细胞学及胚胎发育研究

通过对奥利亚罗非鱼(♀)和鳜(♂)杂交的受精细胞学观察发现:异源精子入卵后产生星光,并核化成雄性原核,与雌原核互相靠近,接触最终完全融合为一个合子核,合子核继续分裂。分析比较了奥利亚罗非鱼,鳜以及奥鳜杂种胚胎发育情况,发现杂种胚胎的发育速度在囊胚早期与母本奥利亚罗非鱼基本一致,到囊胚后期速度有所减慢,但与鳜胚胎发育速度相差很大。这表明奥利亚罗非鱼和鳜虽属不同科间的远缘杂交,但有正常的受精细胞学程序和常规的细胞分裂(卵裂)方式。     

施肥对潮棕壤钾收支及钾在作物体内分配的影响

通过15年的定位试验,研究了不同施肥制度下土壤K的收支及K在作物体内的分配.结果表明,施K肥处理的大豆籽实和秸秆中K浓度高于不施K肥处理;而施K肥处理的玉米籽实K浓度在各个处理间几乎没有变化.在不施K肥条件下,单一施用N肥或NP配施均可造成K的严重亏缺.保持农业系统养分循环再利用可以缓解K收支赤字,而配合适量K肥的施用可以实现作物高产,平衡土壤中K收支.