• Development and Reproduction
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• v.16 no.1
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• pp.59-67
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• 2012

Previously, we found that $Zap70$ (Zeta-chain-associated protein kinase) expressed in the mouse oocytes and played significant role in completion of meiosis specifically at MI-MII (metaphase I-II) transition. Microinjection of $Zap70$ dsRNA into the cytoplasm of germinal vesicle oocyte resulted in MI arrest, and exhibited abnormalities in their spindles and chromosome configurations. The purpose of this study was to determine the mechanisms of action of $Zap70$ in oocyte maturation by evaluating downstream signal networking after $Zap70$ RNAi (RNA interference). The probe hybridization and data analysis were used by Affymetrix Gene Chip Mouse Genome 430 2.0 array and GenPlex 3.0 (ISTECH, Korea) software, respectively. Total 1,152 genes were up (n=366) and down (n=786) regulated after $Zap70$ RNAi. Among those genes changed, we confirmed the expressional changes of the genes involved in the regulation of actin cytoskeleton and MAPK (mitogen-activated protein kinase) signaling pathway, since the phenotypes of $Zap70$ RNAi in oocytes were found in the changes in the chromosome separation and spindle structures. We confirmed the changes in gene expression in the actin skeletal system as well as in the MAPK signaling pathway, and concluded that these changes are main cause of the aberrant chromosome arrangement and abnormal spindles after $Zap70$ RNAi.

• Development and Reproduction
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• v.13 no.3
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• pp.145-153
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• 2009

Previously, we obtained the list of genes differentially expressed between GV and MII oocytes. Out of the list, we focused on functional analysis of Zap70 in the present study, because it has been known to be expressed only in immune cells. This is the first report about the expression and its function of Zap70 in the oocytes. Synthetic 475 bp Zap70 dsRNA was microinjected into the GV oocytes, and the oocytes were cultured in vitro. In addition to maturation rates, meiotic spindle and chromosome rearrangements, and changes in expression levels of transcripts of three kinases, Erk1/2, JNK, and p38, were determined. Zap70 is highly expressed in immature GV oocytes, and gradually decreased as oocyte matured. When dsRNA of Zap70 was injected into the GV oocytes, Zap70 mRNA specifically and completely decreased by 2 hr and its protein expression also decreased significantly. Absence of Zap70 resulted in maturation inhibition at meiosis I (57%) with abnormalities in meiotic spindle formation and chromosome rearrangement. Concurrently, mRNA expression of Erk2, JNK, and p38, were affected by Zap70 RNAi. Therefore, we concluded that Zap70 is involved in MI-MII transition by affecting expression of MAP kinases.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.3
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• pp.344-353
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• 2018

Objective: cAMP and mature promoting factor (MPF) play critical roles during the maturation of mammalian oocytes. The aim of this study was to produce the offspring from denuded oocytes (DOs) in mice by regulating cAMP and MPF. Methods: In this study, we used DOs at the germinal vesicle (GV) stage in mice and regulated levels of cAMP and MPF in DOs by adding Forskolin and PD166285 during in vitro maturation without follicle stimulating hormone and luteinizing hormone, respectively. Results: Combined use of $50{\mu}M$ Forskolin for 3 h and $2.5{\mu}M$ PD166285 for additional 21 h enhanced the developmental competence of DOs, maturation rate of DOs was $76.71%{\pm}4.11%$, blastocyst rate was $18.33%{\pm}4.44%$ after parthenogenetic activation (PA). The DOs could successfully be fertilized with sperm in vitro, cleavage rate was $17.02%{\pm}5.82%$ and blastocyst rate was $5.65%{\pm}3.10%$. Besides, 2-cell in vitro fertilization embryos from DOs produced 4 normal live offspring (4/34). Conclusion: The results confirmed that the combination of Forskolin and PD166285 can induce DOs to complete meiosis process and produce normal offspring.

• Animal cells and systems
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• v.10 no.4
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• pp.227-231
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• 2006

Micro-deletions at specific loci of the Y chromosome have been observed frequently in male infertility patients, suggesting that genes in these regions are involved in male germ cell development. DAZ is a representative male infertility gene at the AZFc locus of the Y chromosome. Since DAZ contains an RNA binding motif along with so-called a DAZ domain, it was proposed to participate in RNA metabolism during spermatogenesis. A mouse gene homologous to the human DAZ gene has been cloned and named Dazl (DAZlike). Dazl is autosomal and expressed in the testis and also at a low level in the ovary. Male mice homozygous for the Dazl null allele have small testes with a few spermatogonia and almost complete absence of germ cells beyond the spermatogonial stage, suggesting the requirement of Dazl for entry or progression through meiosis. However, its exact cellular functions have not been understood yet. In order to investigate cellular functions of Dazl, we decided to isolate candidate interacting protein genes of the mouse Dazl, using yeast two-hybrid screening. A number of candidate Dazlinteracting proteins have been isolated, such as Bprp, Acf, Hgs, Murr1, Nbak3 and Ranbp9, but dynein light chain 1 (Dlc1) was most predominant. A strong interaction of Dazl with Dlc1 suggests that Dazl might function as an mRNA adaptor to the dynein motor complex.

• Korean Journal of Plant Resources
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• v.18 no.2
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• pp.302-308
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• 2005

This study was carried out to obtain the basic informations on the characteristics of gametophytes formation and embryo developement in Dicentra spectabilis. Microspore mother cells developed from archesporial cells, start meiosis when flower bud length reaches around 1 mm, formed tetrahedral type tetrad. The 4 microspores were separated. They were developed to male gametophytes, respectively. Megaspore mother cells were observed when flower bud length was $4{\sim}5\;mm$. The developemental type of megaspore was polygonum and embryo sac was amphitropous. Three large and distinctive antipodals did not degenerated and remained after embryo sac was developed. When the male and female gametophytes was fully developed, the length of stamen and style was very similar or stamen was shorter about 0.5 mm than that of style. This result indicates that self-fertilization can be occurred in this species. After fertilization, developing zygotic embryos showed various stages of development from globular to cotyledonary embryos, and zygotic embryo in seed scattering time seemed to have an early cotyledonary stage.

• Journal of Life Science
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• v.13 no.6
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• pp.958-969
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• 2003

The human Y chromosome is strictly paternally inherited and does not X-Y crossing over during male meiosis in most of its length. Although this region came to be known as the non-recombining region Y (NRY), it was renamed as male-specific region Y (MSY) due to abundant recombination. The MSY is a mosaic of heterochromatic sequences and three classes of euchromatic sequences: X-transposed, X-degenerated and ampliconic. The X-transposed sequences exhibit 99% identity to the X chromosomal sequences. The X-degenerate sequences are remnants of ancient autosomes from which the modem X and Y chromosomes evolved. Eight palindromes of the ampliconic comprise one-quarter of the euchromatic DNA of the male-specific region of the human Y chromosome. They contain many testis-specific genes and typically exhibit 99.97% intra-palindromic (arm-to-arm) sequence identity. The arms of these palindromes must have subsequently engaged in gene conversion, driving the pair arms to evolve it concert. Averages of approximately 600 nucleotides per newborn male have undergone Y-Y gene conversion, which has had an important role in the evolution of multi-copy testis gene families in the MSY.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.6
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• pp.443-448
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• 2001

This study was carried out to obtain the basic informations on the characteristics of gametophytes formation and microspore germination in Astragalus membranaceus Bunge. Pollen mother cells passed through meiosis when the flower bud length reaches around 3.5 mm, thus creating the tetrad when it is 4.0 mm long. Pollen attains full growth when the bud is about 10.0 mm long and the anther is found to dehisce when the length of tate bud reach around 12.0 mm. Embryo sac develops at a similar speed as pollen did and it attains its full growth when the bud is about 10-12 mm long. After being stored at 4$^{\circ}C$ or -4$^{\circ}C$, the pollen maintained its germination ability to almost full extent by the 30th day after store. However, the germination rate at room temperature (23~28$^{\circ}C$) decreased below 3％ by the 3rd day of storage and so did the germination speed.

• Korean Journal of Plant Resources
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• v.28 no.2
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• pp.235-242
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• 2015

Morphology and characteristics of floral organ in highbush blueberry cultivars were studied to select suitable cultivars of highbush blueberry for domestic cultivation. The stamen consists an anther and a tape-like hairy filament with well-developed trichomes. When the anther was opened, the wall of anther was not dehiscent, and pollen grains were discharged into two tubes. Pollen was mature tetrad type without being separated after meiosis (Late March). The number of pollen granules per anther was 400~1,300, the germination rate was higher in the cultivars having many pollen grains. Pistil was composed of five carpels and a shipper without separate part. The number of ovules per ovary was 39~67, therefore, the coefficient of ranged from 11.6 to 31.0%. The seed pod formation by combination of ‘Bluejay’ and ‘Sharpblue’ was higher in the cross-pollination than in the self-pollination.

• Development and Reproduction
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• v.24 no.4
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• pp.297-306
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• 2020

Repetitive changes in the intracellular calcium concentration ([Ca²⁺]i) triggers egg activation, including cortical granule exocytosis, resumption of second meiosis, block to polyspermy, and initiating embryonic development. [Ca²⁺]i oscillations that continue for several hours, are required for the early events of egg activation and possibly connected to further development to the blastocyst stage. The sources of Ca²⁺ ion elevation during [Ca²⁺]i oscillations are Ca²⁺ release from endoplasmic reticulum through inositol 1,4,5 tri-phosphate receptor and Ca²⁺ ion influx through Ca²⁺ channel on the plasma membrane. Ca²⁺ channels have been characterized into voltage-dependent Ca²⁺ channels (VDCCs), ligand-gated Ca²⁺ channel, and leak-channel. VDCCs expressed on muscle cell or neuron is specified into L, T, N, P, Q, and R type VDCs by their activation threshold or their sensitivity to peptide toxins isolated from cone snails and spiders. The present study was aimed to investigate the localization pattern of N and P/Q type voltage-dependent calcium channels in mouse eggs and the role in fertilization. [Ca²⁺]i oscillation was observed in a Ca²⁺ contained medium with sperm factor or adenophostin A injection but disappeared in Ca²⁺ free medium. Ca²⁺ influx was decreased by Lat A. N-VDCC specific inhibitor, ω-Conotoxin CVIIA induced abnormal [Ca²⁺]i oscillation profiles in SrCl₂ treatment. N or P/Q type VDC were distributed on the plasma membrane in cortical cluster form, not in the cytoplasm. Ca²⁺ influx is essential for [Ca²⁺]i oscillation during mammalian fertilization. This Ca²⁺ influx might be controlled through the N or P/Q type VDCCs. Abnormal VDCCs expression of eggs could be tested in fertilization failure or low fertilization eggs in subfertility women.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.213-224
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• 2019

There is an increasing frequency in the occurrence of abnormal weather phenomena such as sharp increases and decreases in temperature. Under these weather conditions, the heading time of rice changes unexpectedly, which poses problems in agriculture. Therefore, we investigated the effect of temperature on the heading response at different growth stages in rice. During the period from transplanting to heading, the plants were subjected to different temperature treatments, each for a 9-day period, to observe the heading response. For the heading date analysis, "heading date" was defined as the number of days from transplanting to the appearance of the first spikelet. We found that the influence of temperature increased in the order of rooting stage, followed by meiosis, early tillering, spikelet differentiation, and panicle initiation stage in all ecological types and cultivars. In particular, unlike the results reported previously, the effect of temperature on heading during the photo-sensitive period was very small. Meanwhile, the influence of temperature on vegetative growth response at different growth stages was not consistent with heading response. These results can be used as basic data for predicting the variation in heading date owing to temperature variation at each growth stage. In addition, we propose that the concept of day length should be included in determining the influence of temperature on the photo-sensitive period.