Efficient rooting for establishment of papaya plantlets by micropropagation

A low cost micropropagation protocol to produce high quality root systems which are easy and economical to acclimatize is essential for large-scale micropropagation of papaya (Carica papaya L.). In this study, individual shoots (>0.5 cm) with 2_∼3 leaves from in vitro papaya multiple shoots were cultured on MS agar medium containing 2.5 μM IBA under dark conditions for 1 week for root induction. They were then transferred to agar or vermiculite media, containing half strength MS medium, under aerated or non-aerated conditions, for root development. Rooting percentage of shoots cultured for 2 weeks in aerated vermiculite was 94.5%, compared with 90.0% in non-aerated vermiculite, 71.1% in aerated agar, and 62.2% in non-aerated agar. Shoots with roots were acclimated in vermiculite under 100% RH for 1 week and then under ambient conditions for 2 weeks in a temperature-controlled growth chamber (28 °C). The survival rates of the plantlets were 94.5% from aerated vermiculite, 87.8% from non-aerated vermiculite, 42.2% from aerated agar, and 35.6% from non-aerated agar. Thus, root induction in low-concentration IBA agar medium followed by root development in vermiculite containing half strength MS medium under aerated conditions results in efficient rooting of in vitro papaya shoots. This revised version was published online in June 2006 with corrections to the Cover Date.     

Indole-3-carbinol Suppresses Tumor-Induced Angiogenesis by Inhibiting Tube Formation and Inducing Apoptosis

Indole-3-carbinol (I3C) has been reported to exert anticancer activity in vivo. However, its anticancer mechanism has not been fully elucidated. In this study, we demonstrate that I3C suppressed tumor-induced angiogenesis and tube formation of endothelial cells. I3C also induced apoptosis in endothelial cells by activating the caspase cascade. We propose that I3C exerts its anticancer effect through the induction of endothelial apoptosis.     

Is the adhesive material secreted by sea urchin tube feet species‐specific?

Sea urchin adoral tube feet are highly specialized organs that have evolved to provide efficient attachment to the substratum. They consist of a disk and a stem that together form a functional unit. Tube foot disk tenacity (adhesive force per unit area) and stem mechanical properties (e.g., stiffness) vary between species but are apparently not correlated with sea urchin taxa or habitats. Moreover, ultrastructural studies of sea urchin disk epidermis pointed out differences in the internal organization of the adhesive secretory granules among species. This prompted us to look for interspecific variability in the composition of echinoid adhesive secretions, which could explain the observed variability in adhesive granule ultrastructure and disk tenacity. Antisera raised against the footprint material of Sphaerechinus granularis (S. granularis) were first used to locate the origin of adhesive footprint constituents in tube feet by taking advantage of the polyclonal character of the generated antibodies. Immunohistochemical assays showed that the antibodies specifically labeled the adhesive secretory cells of the disk epidermis in the tube feet of S. granularis. The antibodies were then used on tube foot histological sections from seven other sea urchin species to shed some light on the variability of their adhesive substances by looking for antibody cross‐reactivity. Surprisingly, no labeling was observed in any of the species tested. These results indicate that unlike the adhesive secretions of asteroids, those of echinoids do not share common epitopes on their constituents and thus would be “species‐specific.” In sea urchins, variations in the composition of adhesive secretions could therefore explain interspecific differences in disk tenacity and in adhesive granule ultrastructure. J. Morphol., 2011. © 2011 Wiley Periodicals, Inc.     

A role for LORELEI,a putative glycosylphosphatidylinositol‐anchored protein,in Arabidopsis thaliana double fertilization and early seed development

In plants, double fertilization requires successful sperm cell delivery into the female gametophyte followed by migration, recognition and fusion of the two sperm cells with two female gametes. We isolated a null allele (lre‐5) of LORELEI, which encodes a putative glycosylphosphatidylinositol (GPI)‐anchored protein implicated in reception of the pollen tube by the female gametophyte. Although most lre‐5 female gametophytes do not allow pollen tube reception, in those that do, early seed development is delayed. A fraction of lre‐5/lre‐5 seeds underwent abortion due to defect(s) in the female gametophyte. The aborted seeds contained endosperm but no zygote/embryo, reminiscent of autonomous endosperm development in the pollen tube reception mutants scylla and sirene. However, unpollinated lre‐5/lre‐5 ovules did not initiate autonomous endosperm development and endosperm development in aborted seeds began after central cell fertilization. Thus, the egg cell probably remained unfertilized in aborted lre‐5/lre‐5 seeds. The lre‐5/lre‐5 ovules that remain undeveloped due to defective pollen tube reception did not induce synergid degeneration and repulsion of supernumerary pollen tubes. In ovules, LORELEI is expressed during pollen tube reception, double fertilization and early seed development. Null mutants of LORELEI‐like‐GPI‐anchored protein 1 (LLG1), the closest relative of LORELEI among three Arabidopsis LLG genes, are fully fertile and did not enhance reproductive defects in lre‐5/lre‐5 pistils, suggesting that LLG1 function is not redundant with that of LORELEI in the female gametophyte. Our results show that, besides pollen tube reception, LORELEI also functions during double fertilization and early seed development.     

Differences in pollen viability in relation to different deceptive pollination strategies in Mediterranean orchids

Background and Aims

To date, current research involving pollen viability has been evaluated in a relatively low number of orchid species. In the present study, we focused on five related Mediterranean orchid genera (Anacamptis, Orchis, Dactylorhiza, Ophrys and Serapias) that are characterized by different types of deceptive pollination.

Methods

The in vitro germination ability of increasingly aged pollinaria of eight food-, seven sexually and two shelter-deceptive species was evaluated. Pollination experiments on two food-, one sexually and one shelter-deceptive species were also performed and the percentage of embryonate seeds derived from the increasingly aged pollinaria was checked.

Key Results

All of the examined species showed long-term viabilities (=50 % pollen tube growth) that ranged from 8 to 35 d. Species with the same deceptive pollination strategies exhibited the same pollen viability trends. Interestingly, pollen viabilities of species groups with different deception types have shown significant differences, with sexually and shelter- deceptive species exhibiting a shorter life span than food-deceptive species.

Conclusions

This study confirms the prolonged germination and fertilization capacities of orchid pollinaria, and to our knowledge is the first report demonstrating a clear relationship between pollen viability and pollination system. It is proposed that this relationship is attributed to the different types of reproductive barriers, pre- or post-zygotic, that characterixe Ophrys and Serapias and the food-deceptive species, respectively.     

人类辅助生殖技术研究的里程碑——2010年诺贝尔生理学或医学奖解读

试管婴儿技术是现代医学治疗不育症的人类辅助生殖技术之一．试管婴儿技术的发展,打破了人类繁衍的自然方式和过程,是生殖医学领域的一场革命,对生命医学的发展产生了重大影响．为此,在试管婴儿技术研究中做出开创性贡献的英国科学家罗伯特·爱德华兹,荣获2010年诺贝尔生理学或医学奖．     

DUF784基因在花粉管导向中的功能分析

花粉管导向是高等植物完成双受精过程的重要环节,是受多重信号调控的复杂过程.最近的研究揭示,配子体阶段花粉管导向的诱导信号分子是一类具多态性的富含半胱氨酸的防卫素类似蛋白,如来自玉米的ZmEA1和蓝猪耳草中的LUREs在吸引花粉管进入珠孔起重要作用.但是拟南芥及其它植物中此类信号未知.转录组学分析表明,一组DUF784基因可能在花粉管导向中起到重要作用.通过RNAi技术降低一组DUF784基因的表达,分析发现在RNAi转基因植株中,出现胚珠败育现象,花粉管导向出现异常,一部分花粉管不能进入珠孔.另外,用MYB98基因的启动子携带1个DUF基因的编码区,然后转化ccg突变体,发现ccg转基因株系中胚胎败育率下降,即DUF基因能部分互补ccg突变体的表型;从这两方面证实了DUF784基因在花粉管定向导入过程中的作用.     

Regional neural tube closure defined by the Grainy head-like transcription factors

Primary neurulation in mammals has been defined by distinct anatomical closure sites, at the hindbrain/cervical spine (closure 1), forebrain/midbrain boundary (closure 2), and rostral end of the forebrain (closure 3). Zones of neurulation have also been characterized by morphologic differences in neural fold elevation, with non-neural ectoderm-induced formation of paired dorso-lateral hinge points (DLHP) essential for neural tube closure in the cranial and lower spinal cord regions, and notochord-induced bending at the median hinge point (MHP) sufficient for closure in the upper spinal region. Here we identify a unifying molecular basis for these observations based on the function of the non-neural ectoderm-specific Grainy head-like genes in mice. Using a gene-targeting approach we show that deletion of Grhl2 results in failed closure 3, with mutants exhibiting a split-face malformation and exencephaly, associated with failure of neuro-epithelial folding at the DLHP. Loss of Grhl3 alone defines a distinct lower spinal closure defect, also with defective DLHP formation. The two genes contribute equally to closure 2, where only Grhl gene dosage is limiting. Combined deletion of Grhl2 and Grhl3 induces severe rostral and caudal neural tube defects, but DLHP-independent closure 1 proceeds normally in the upper spinal region. These findings provide a molecular basis for non-neural ectoderm mediated formation of the DLHP that is critical for complete neuraxis closure.