• 한국산림과학회지
• /
• 제45권1호
• /
• pp.51-61
• /
• 1979

교배(交配) 모수(母樹)인 P. alba화분(花粉) 모수(母樹)인 P. glandulosa 및 그의 잡종(雜種)인 ${\times}$P. albaglandulosa에 관(關)한 화분모세포(花粉母細胞)의 감수분열(減數分裂)에 있어 염색체행동(染色体行動)과 대합(對合) 현상(現象)에 관(關)해 조사(調査)하였다. 1. Metaphase II에서 Earyl separation chromosome을 갖는 핵판(核板)이 가장 적은 개체(個体)는 P. glandulosa로 11.0%며 ${\times}$P. albaglandulosa는 13.0%로 가장 높았다. 2. Metaph se II에서 ${\times}$P. albaglandulosa는 11.0%의 Early separation chromosome이 출현(出現)했으나 양친양친수(兩親兩親樹)와 차이(差異)는 없었다. 3. Anahase I에서 Lagging chromosome의 출현율(出現律)은 ${\times}$P. albaglandulosa가 다소(多少) 높아 11.6%로 나타났으며 chromosome bridge에서는 양친수(兩親樹)와 거의 차(差)가 없었다. 4. Anaphase II때 Lagging chromososome은 ${\times}$P. albaglandulosa에서 다소(多少) 높은 빈도(頻度)로 10.2%였으며 chromosome bridge P. glandulosa에서 가장 높은 빈도(頻度)로 출현(出現)하였다. 5. Abnormal pollen sporad는 ${\times}$P. albaglandulosa에서 가장 많이 출현(出現)하여 8.2%를 나타냈다. 이상(以上)의 결과(結果) P. alba, P. glandulosa 및 ${\times}$P. albaglandulosa는 화분모세포분열(花粉母細胞分裂)에 있어서 염색체분열접합(染色体分裂接合)이 정상적(正常的) 행동(行動)을 하고 있어 결국(結局) 정상(正常) 화분형식(花粉形式)을 행(行)하는 수종(樹種)이라 결론(結論)할 수 있다.

• 식물조직배양학회지
• /
• 제25권6호
• /
• pp.453-475
• /
• 1998

During the 100 years since the initial discovery of meiotic phenomenon many brilliant aspects have been elucidated, but further researches based on light microscopy alone as an experimental tool have been found to have some limits and shortcomings. By the use of electron microscopy and armed with the advanced knowledges on modern genetics and biochemistry it has been possible to applu molecular technology in gaining information on the detailed aspects of meiosis. As synapsis takes place, a three-layered proteinous structure called the synatonemal complex starts to form in the space between the homologous chromosomes. To be more precise, it begins to form along the paired chromosomes early in the prophase I of meiotic division. The mechanism that leads to precise point-by-point pairing between homologous chromocomes division. The mechamism that leads to precise point-by-point pairing between homologous chromosomes remains to be ascertained. Several items of information, however, suggest that chromsome alignment leading to synapsis may be mediated somehow by the nuclear membrane. Pachytene bivalents in eukaryotes are firmly attached to the inner niclear membrane at both termini. This attached begins with unpaired leptotene chromosomes that already have developed a lateral element. Once attached, the loptotene chromosomes begin to synapse. A number of different models have been proposed to account for genetic recombination via exchange between DNA strands following their breakage and subsequent reunion in new arrangement. One of the models accounting for molecular recombination leading to chromatid exchange and chiasma formation was first proposed in 1964 by Holliday, and 30 years later still a modified version of his model is favored. Nicks are made by endomuclease at corresponding sites on one strant of each DNA duplex in nonsister chromatid of a bivalent during prophase 1 of meiosis. The nicked strands loop-out and two strands reassociate into an exchanged arrangement, which is sealed by ligase. The remaining intact strand of each duplex is nicked at a site opposite the cross-over, and the exposed ends are digested by exonuclease action. Considerable progress has been made in recent years in the effort to define the molecular and organization features of the centromere region in the yeast chromosome. Centromere core region of the DNA duplex is flanked by 15 densely packed nucleosomes on ons side and by 3 packed nucleosomes on the other side, that is, 2000 bp on one side and 400 400 bp in the other side. All the telomeres of a given species share a common DNA sequence. Two ends of each chromosome are virtually identical. At the end of each chromosome there exist two kinds of DNA sequence" simple telpmeric sequences and telpmere-associated sequencies. Various studies of telomere replication, function, and behabior are now in progress, all greatly aided by molecular methods. During nuclear division in mitosis as well as in meiosis, the nucleili disappear by the time of metaphase and reappear during nuclear reorganizations in telophase. When telophase begins, small nucleoli form at the NOR of each nucleolar-organizing chromosome, enlarge, and fuse to form one or more large nucleoli. Nucleolus is a special structure attached top a specific nucleolar-organizing region located at a specific site of a particular chromosome. The nucleolus is a vertical factory for the synthesis of rRNAs and the assenbly of ribosome subunit precursors.sors.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
• /
• pp.171-174
• /
• 2003

In this paper, a Learning module for a reconfigurable neural network processor(ERNIE) was proposed for an On-chip learning. The existing reconfigurable neural network processor(ERNIE) has a much better performance than the software program but it doesn't support On-chip learning function. A learning module which is based on Back Propagation algorithm was designed for a help of this weak point. A pipeline structure let the learning module be able to update the weights rapidly and continuously. It was tested with five types of alphabet font to evaluate learning module. It compared with C programed neural network model on PC in calculation speed and correctness of recognition. As a result of this experiment, it can be found that the neural network processor(ERNIE) with learning module decrease the neural network training time efficiently at the same recognition rate compared with software computing based neural network model. This On-chip learning module showed that the reconfigurable neural network processor(ERNIE) could be a evolvable neural network processor which can fine the optimal configuration of network by itself.

• Asian-Australasian Journal of Animal Sciences
• /
• 제29권6호
• /
• pp.793-800
• /
• 2016

Most hinnies (female donkey${\times}$male horse) and mules (female horse${\times}$male donkey) are sterile with few reports of equine fertile hybrids. The main cause of this sterility is thought to be a meiotic block to spermatogenesis and oogenesis. This study compared the developmental features of the testes and a histological analyses of spermatogenesis in a male hinny with those of a normal, fertile stallion and Jack donkey. Hinny testes showed a thicker tunica albuginea, fewer blood vessels and more connective tissue in the testis parenchyma than those of the stallion and Jack donkey. Although the mean number of seminiferous tubules was significantly higher in stallion and hinny than Jack donkey (p<0.01), the mean proportion of seminiferous tubules was lower in the hinny (p<0.01) which resulted in a smaller diameter of seminiferous tubules. The mean number of spermatogonia and spermatocytes per unit area were significantly lower in hinny testis (p<0.01) and no spermatids or mature spermatozoa cells were found during immunofluorescent analyses. These results indicated that defects in seminiferous tubule development and structure occur in the testis of hinnies. Furthermore, most spermatogonia and spermatocytes cease development in synapsis during mid-meiosis of spermatocytes, which results in a block to spermatogenesis that prevents the formation of spermatids and matured spermatozoa during meiosis in male hinnies.