• ALGAE
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• v.35 no.4
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• pp.389-404
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• 2020

Red algal fertilization is unusual and offers a different model to the mechanism of intracellular transport of nuclei and polyspermy blocking. A female carpogonium (egg) undergoes plasmogamy with many spermatia (sperm) simultaneously at the receptive structure, trichogyne, which often contains numerous male nuclei. The pattern of selective transport of a male nucleus to the female nucleus, located in the cell body of the carpogonium, remain largely unknown. We tracked the movement of spermatial nuclei and cell organelles in the trichogyne after plasmogamy using time-lapse videography and fluorescent probes. The fertilization process of Bostrychia moritziana is composed of five distinctive stages: 1) gamete-gamete binding; 2) mitosis in the attached spermatia; 3) formation of a fertilization channel; 4) migration of spermatial nuclei into the trichogyne; and 5) cutting off of the trichogyne cytoplasm from the rest of the cell after karyogamy. Our results showed that actin microfilaments were involved in the above steps of fertilization, microtubules are involved only in spermatial mitosis. Time-lapse videography showed that the first ("primary") nucleus which entered to trichogyne moved quickly to the base of carpogonium and fused with the female nucleus. The transport of the primary male nucleus to the egg nucleus was complete before its second nucleus migrated into the trichogyne. Male nuclei from other spermatia stopped directional movement soon after the first one entered the carpogonial base and oscillated near where they entered trichogyne. The cytoplasm of the trichogyne was cut off at a narrow neck connecting the trichogyne and carpogonial base after gamete nuclear fusion but gamete binding and plasmogamy continued on the trichogyne. Spermatial organelles, including mitochondria, entered the trichogyne together with the nuclei but did not show any directional movement and remained close to where they entered. These results suggest that polyspermy blocking in B. moritziana is achieved by the selective and rapid transport of the first nucleus entered trichogyne and the rupture of the trichogyne after gamete karyogamy.

• ALGAE
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• v.23 no.3
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• pp.163-175
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• 2008

Phenolic compounds play a major role in the interaction of plants with their environment. They are thought to have been a feature of higher plants since early colonization of the land. Phenolics are crucial for many important aspects of plant life. They can play structural roles in different supporting or protective tissues, for example in cell walls, they can be involved in defence strategies, and signalling properties particularly in the interactions between plants and their environment. In brown algae, phenolic compounds are contained within membrane bound vesicles known as physodes, and their roles in algae are thought to be similar to those of higher plant phenolics. They can be stained using various histochemical stains, however, none of these stains are phenolic specific so care must be taken during interpretation of such results. Many, but not all phenolics are also autofluorescent under UV or violet light. Physodes are involved in cell wall construction, both in primary and secondary walls in brown algae. They bind together with other wall components to make a tough wall. They have also been found to play a role at fertilization, in blocking polyspermy in some species. Sperm are very quickly rendered immobile after phenolic release from newly fertilized zygotes seconds after fertilization. Phenolic compounds are thought to be important herbivore deterrents in some species due to their astringent nature. Phenolic compounds also offer effective UV protection in the early life stages and also the adults of many algal species. In the future, this factor may also make them an important player in the pharmaceutical and skincare industries.

• Applied Microscopy
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• v.41 no.2
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• pp.123-128
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• 2011

The micropyles on the prefertilized and artificial fertilized eggs of Epinephelus fasciatus were investigated using scanning electron microscope (SEM). The micropyles ($6.6{\pm}0.41\;{\mu}m$) of E. fasciatus eggs were found in the animal pole and theirs shape were observed as a flat crateriform of cylindrical shape. The micropylar vestibule arranged by 6~7 thickened spiral annuli on the ridge and contributed to differentiate and form fertilization cone for blocking to polyspermy by presenting swollen vestibule structure. As E. fasciatus eggs was pelagic, so chorionic surface was an uneven structures such as circular and fillar form nodules. Especially, various pores (0.15~0.55 ${\mu}m$, 230~270 pores) distributed at the only around micropyles, those pores radiately exhibited regular projection structures showing gill filament-shape. These ultrastructural characters of E. fasciatus eggs can be utilized in a taxonomical cue of grouper species.

• Journal of Embryo Transfer
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• v.19 no.3
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• pp.245-255
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• 2004

In recent years, an increasing number of studies on pig in vitro maturation(IVM) and in vitro fertilization(IVF) have been separated. the wide range of new technologies, including that in applied molecular genetics, has increased this interest. the production of viable porcine embryos in vitro is a prerequisites for the successful production of transgenic pigs to date. The efficiency of IVM/IVF techniques in the porcine is lower than that obtained in other species such as cattle and mouse. The several problems are generally thought to be the cause of poor results: the low rate of MPN formation derived from inadequate IVM of oocytes, the high incidence of polyspermy after IVF and cell blocking at 4 cell during embryos culture. For there reasons overcoming, many studies have been conducted to improve in vitro embryo-genic competence of oocytes. In the last several years, many maturation culture media have been evaluated and various exogenous factors such as hormones and grows factors have been tested to improve the efficiency of porcine in vitro system. In the study several antioxidants have been examined to improve in vitro fertilization and development of porcine oocytes. In this study, several antioxidants were examined to determine the effects on the development of oocytes to the cleavage, morula and blastocyst stage when added at the maturation(IVM) or in vitro fertilization(IVF) or in vitro culture(IVC) of porcine embryos. Porcine oocytes were matured, fertilized and embryos were cultured in defind conditioned medium in vitro with or without supplementation with the antioxidents of cysteine, catalase and glutathione. 1. Significant improvement of blastocyst rate (27.2％ versus 15.4％, p<0.05) were achieved when catalase(500U/$m\ell$) were added to TCM-199 medium and morula rate(72.0％ versus 53.9％, p<0.05) were significantly higher when glutathione(1.0mM/$m\ell$) were added to TCM-199 medium than those of control. 2. In mTBM medium for oocytes fertilization, the addition of cysteine, catalase and glutathione had no positive effect on embryonic development. glutathione had no positive effect on embryonic development. In conclusion, this study shows that addition of catalase, gluththione during IVM improved the rate of porcine embryo development.