Synergids are metabolically dynamic cells of the egg apparatus and represent an important component of the female gametophyte. Besides directing the growth of the pollen tube towards the micropylar end of the embryo sac, these ephemeral structures make room for the pollen tube cytoplasm. The nature of chemotrophic substances that direct the growth of the pollen tube, the mechanism of degeneration of one of the synergids before fertilization and the molecular aspects of synergid morphogenesis have been studied in detail. Research carried out on model systems such as Arabidopsis, Brassica, Capsella, Triticum and Torenia has expanded our understanding of the molecular regulation of the pollen tube journey, its guidance and navigation in the pistil. Recently, the critical role of the central cell in fertilization and prevention of polytubey has also been thoroughly investigated. Interesting aspects that lead to degeneration of synergids, and the factors governing degeneration, including molecular aspects, have produced a paradigm shift in the understanding of these intriguing units. Sophisticated confocal microscopy, live cell imaging, and molecular tools have helped in furthering our knowledge of the functioning of synergids. Recent research using high throughput techniques has deciphered the role of various genes that regulate and govern the release of chemotropic substances, cell-to-cell interaction and synergid cell degeneration. Moreover, with the diversity displayed in form and function of organs in the angiosperms, and the switching of roles of the cells of egg apparatus, new insights have been provided into the involvement of synergids both pre- and post-fertilization. The present review provides a comprehensive account of synergids, their role in fertilization and the post fertilization events that have emerged using interdisciplinary approaches in recent years. We also discuss the variations observed in degeneration of synergids and the mechanisms that have been unraveled recently. Study of the dynamism exhibited by synergids reveals newer roles of these in fertilization. How synergids in angiosperm taxa where genetic transformation/alteration is carried out will respond to pollen stimuli is still unknown. Since environmental factors such as light and temperature have a significant impact on synergids and fertilization, it would be rewarding to study the role of chemo-attractants and other factors in elucidating the functional roles of synergids. Further research into developing adequate protocols for manipulating synergid functions is certainly required. This research has enormous potential in the advancement of basic science and has potential applications in agriculture, horticulture, and bioprospecting.
The aim of this study was to investigate the correlation between CDK1 protein and CDK1 mRNA during oocyte maturation in vivo in mouse. GV, GVBD, MI and MII oocytes were obtained from mice, respectively. Western blot validated that the CDK1 protein expression increased continuously and significantly with oocyte maturation in vivo (P<0.05). Real-time qRT-PCR showed that CDK1 mRNA expression was down-regulated significantly during transformation from GV to MI stages (P<0.05), and up-regulated significantly during transformation from MI to MII stages (P<0.05). The level of CDK1 mRNA peaked at MII stages. Spearman correlation analysis indicated that CDK1 protein expression was poor correlation with CDK1 mRNA expression during oocyte maturation in vivo (R=0.200). This finding suggested that the increase of CDK1 protein during oocyte maturation in vivo was not entirely caused by the change of transcription level. The results provide new food for thought for further research on the molecular mechanism of oocyte maturation in vivo.
It has long been held that the main difference between cranial and trunk neural crest (CNC and TNC, respectively) was the potential of CNC to originate mesenchymal cell types, especially skeletogenic. This is an age-old question that continues to challenge researchers, even today. Unfortunately, to date, no consensus has concluded the extent of TNC mesenchymal potential, nor has a systematic review been conducted to organize current knowledge about this fascinating question. However, the number of studies related to this question have expanded and deepened considerably in the last few years thanks to several new different species of vertebrates employed, the generation of transgenic animal strains, the combination of cell markers, and also the improvement of cell culture conditions through the use of different substrates and signaling molecules. Therefore, this review summarizes the literature showing that TNCCs can generate a broad range of mesenchymal cell types, including skeletogenic. This potential can be unveiled by certain favorable in vitro conditions, but it also seems to be expressed in some animal structures in vivo, to which TNCCs contribute. We also present several works that offer a contrary view and do not detect any mesenchymal/skeletogenic contribution of TNCCs in vivo. Perhaps, it is the controversy itself that makes this subject even more exciting.
Intraflagellar transport (IFT) is an essential condition for ciliogenesis. The primary cilia protrude like antennae and act as chemical or mechanical sensory organelles that coordinate specific receptor localization and signal transduction. IFT20 is the smallest molecule in IFT complex B, which is located in both the cilia and the Golgi complex. Recent studies have shown that IFT20 is a key molecule in multiple signaling pathways. Importantly, in the function of IFT20, signal transduction is not restricted to cilia, but is also involved in non-ciliary functions. Here we summarize current knowledge regarding IFT20-mediated signaling pathways and their relationship with cell development and tissue homeostasis, and analyse the cilia-dependent and cilia-independent mechanisms of IFT20 coordinated signaling pathways and potential crosstalk between the mechanisms. This review provides a comprehensive perspective on IFT20 coordinates signaling mechanisms in cell development and tissue homeostasis.
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