Leber disease
Material inheritance means a genetic phenomenon controlled by the nuclear outer chromosome. For example, Leber's Hereditary Neuropathy, LHON is a major hereditary disease that is mainly involved in the visual yellow belt fiber, leading to a maternal hereditary disease that is degenerative. Male patients in this disease are mostly, the age of onset can be from less than 10 to 70 years old, but often in the age of 20 ~ 30. At the same time or in the eyes, the disease is mainly manifested as acute or subacute vision reduction, with central vision defects and tight impairment. In 1988, Wallace et al. Found that LHON was associated with mutation DNA (Mitochendrial DNA, MTDNA), and the patient's phosphorylated complex I (NADH dehydrogenase) ND4 subunit No. 11778 site base is replaced with a, so that ND4 Subunion 340-bit highly conserved arginine becomes histidine, resulting in LHON. More than 40 MTDNA mutations associated with LHON have been found, where ND4 G11778A, ND1 G3460A, and ND6 T14484C are considered to be three recognized primary mutation sites associated with LHON. Since MTDNA is a maternal genetic, the Leber disease caused by MTDNA gene mutations also follows the post-maternal transmission law, ie, patients are related to the mother. Direct collers have not been seen in the descendants of male patients. However, it is not a matter of presence of female patients, and the age of incidence is inconsistent; even some female patients themselves are normal, but the disease can be passed to the next generation.
Features
1 Mother transfer her MTDNA to the son and daughter, but only daughters can pass their MTDNA to the next generation;
2 human cells There are usually thousands of MTDNA copies, in the cells coexisting in mutants and normal MTDNA, MTDNA has genetic cars during the replication and separation of cells, which can cause three genotypes in children: homozygous mutant MTDNA Hybrid MTDNA, mutant and normal MTDNA heterogeneous because MTDNA's genetic does not follow Mendel's law, which is randomly distributed into child cells; mitochondrial disease has a threshold, only when an abnormal mtna Turning the disease when the threshold is exceeded. MTDNA of female carrier's intracellular mutation did not reach a threshold or a nuclear affected by a certain extent, but still passed through the MTDNA mutant. MTDNA in women in patients also had heterozygous, and the children were collected more of mutant MTDNA, and less condition was lighter or no pathogenesis.
Study
Mitochondrial DNA is generally only genetically genetically generated by the mother, and is a great tool for exploring the genetic tool of the mother. A study released by scientists explained the mechanism of mitochondrial DNA with this feature.
The mitochondria is a place where cell energy is stored and supplied. The research team of West Village, Cornell University of Cornell, and the research team of Tokyo University, Japan, in the new phase of the National Academy of Sciences, "Journal of the National Academy of Sciences" said that the mitochondrial DNA of sperm is decomposed soon, causing the mitochondrial DNA only through the mother. Scientists have previously believed that it may be because the sperm is much smaller than the egg, the number of mitochondria is also very limited, resulting in the germal mitochondrial DNA from the parent to account for absolute advantages. The sperm mitochondrial DNA is susceptible to the influence of tension, in order to prevent the germplasm of the descendants without the influence of the neutral genetic genetics, sperm mitochondrial DNA is destroyed.
In this study, the researchers were observed after dyeing the sperminal mitochondrial DNA of Qingxi. Sperm enters the mature stage, and these mitochondrial DNAs have only one-fifth of the original number, while almost all after the fertilization. The researchers use special devices to re-observe the fine sperm, and found that the mitochondria of the sperm is intact, while the DNA in the mitochondria is decomposed to decompose after 1 hour after fertilization.
Maternal genetic is the main characteristics of cytoplasmic genetic, and cannot represent all of the content of cytoplasm. With the development and application of molecular biology technology, it provides people with a strong means of research and understanding of cytoplasmic genetic law, and scientists have tried the new laws and new phenomena of biological cytoplasmic DNA genetic, and the performance of cytoplasm For the mother's maternal genetic, the father's genetic and the parental genetic forms have greatly enriched and gradually improved the content of cytoplasmic genetic research.
Life is more affected by matrix, because some of the genetic variation in mitochondria will affect the life of the descendants, while the mitochondrial genome belongs to the maternal genetic.
Other genetic
Cellular genetic is generally characterized by genetic characteristics of matrix. Since the 1980s, with the development of DNA molecular biology technology, the DNA molecule labeling is applied to cytoplasmic genetic studies, and the variation of cytoplasmic genetic substances is studied from DNA molecules, so that people have a further understanding of cytoplasmic genetic phenomena. . According to research, mitochondrial DNA is generally characterized by human, other mammals, amphibians, fish and higher plants, including humans, other mammals, amphibians, fish and higher plants. However, it has also been found that the mice, mice, the moon, barley, and rye, the mid-bone mitochondrial DNA, such as the mouse, barley, and rye, the northern Chinese color, etc. The study of plant chloroplast DNA has found that in the quilt plant, most plants are manifestative as maternal genetic characteristics, and 20% of these species have a parental phenomenon, and plants such as cycosity, carrots are typical. Genetic characteristics. . Most of the bodies DNA of most naked plants is characterized by the genetic characteristics of the parent compared to the quilt plants.