What is interspecific hybridization examples
People breed different species of plants and animals to produce organisms with valuable properties. For example, mule – heterotic hybrid of a donkey and a horse and Nar – hybrid one-humped and two – humped camels have great stamina and strength. Hybrids of wild mountain sheep and fine-wool sheep give wool of high quality. However, all interspecific and intergeneric hybrids are usually sterile.
Why are interspecies hybrids are usually sterile
The cause of infertility distant hybrids is the difference of their chromosomes. Each chromosome is represented by only one homologue, resulting in the formation of homologous pairs (bivalents were) in meiosis becomes impossible. I.e. meiotic filter, occurs when distant hybridization, prevents the formation of normal germ cells in females and their sexual reproduction.
Chromosomes of different structure from inter-specific hybrids are not able to konjugierte. In the normal course of meiosis homologous pairs closer together, partially exchanged genes, and then reteplase and on the threads of the spindle disperse to different poles of the dividing cell. At the crossing of distant hybrids of the chromosome that do not have a pair, don't disperse to different poles, and randomly, arbitrarily fall into the forming gamete. These germ cells are usually not viable.
Polyploidy as a method of overcoming the sterility of interspecific hybrids
One of the main methods of overcoming the sterility of interspecific hybrids polyploidy. When using this method, the spindle deliberately destroy special substances (for example, poison colchicine), and the doubled chromosomes are due to remain in the same cell. Homologous chromosomes in multiple sets of the parent birds conjugial between that restores normal course of meiosis.
Polyploid hybrid of cabbage and radish – an example of successful overcoming of the sterility of distant hybrids
For the first time the sterility of distant hybrids overcome by polyploidy Russian geneticist G. D. Karpechenko in 1924, received ogrodowy a hybrid of radish and cabbage. Both contain a haploid set of chromosomes 9. The hybrid has 18 chromosomes (9 from the cabbage and radish 9) sterile, because the chromosomes in meiosis are not conjugium. In polyploid, amphidiploids, hybrid, of which 18 chromosomes of the cabbage and radish, the conjugation of the chromosomes of the cabbage with the cabbage, reechnyj – redenumi. This hybrid resembling a cabbage, and radish, successfully fruiting: pods is represented by two connected pods, one of which is similar in appearance to the cabbage and the other on radecky.
Advice 2: How to check infertility
Many couples dream of a child, or even several, but unfortunately, not all of them is impossible to conceive and give birth. Stress, unhealthy lifestyle, bad habits, different diseases can cause infertility. A couple is considered infertile if for a year or two she is unable to conceive a child, and they have regular sexual intercourse and not using protection. Infertility can be both female and male. To check you need to pass a full medical examination.
Cause of infertility in women can be migrated earlier inflammatory and infectious diseases, abortion, abdominal surgery in the pelvic area. Adhesions in the abdomen and the obstruction of the fallopian tubes are also the reason why a woman cannot conceive a child. To identify these problems, you need to undergo a gynecological examination and ultrasound examination of the pelvic organs, which can be detected in various inflammatory processes. Hysterosalpinography is assigned for determination of tubal patency and hysteroscopy will help to determine the presence of pathologies in the uterine cavity. To determine whether ovulation, prescribe hormonal evaluation at 2-4 day cycle and on day 21. Attention is drawn to the menstrual cycle if it is irregular, it may be the reason that you are not ovulating, i.e. the egg, ready for fertilization, is not Mature.Because infertility may be associated with endocrine diseases, in particular metabolic disorders, excess weight, it is recommended that the survey endocrinologist, who appoints analyzes on hormones, and if necessary the treatment. Also taken into account and, protect the woman, for example, the use of IUDs is quite often the cause of inflammatory processes in organs of small pelvis, which can negatively affect fertility.
The cause of infertility may not be in the woman and the man. Inadequate sperm motility, low sperm quality, infectious diseases, hydrocele, varicocele, Smoking, alcohol abuse, constant stress and other factors may reduce the ability of men to reproduce offspring. To identify male infertility should be examined by a urologist to be checked for the presence of infectious diseases, including sexually transmitted to do semen analysis, which will assess the quality and quantity of seminal fluid. To determine the cause of infertility in men a lot easier, so best to partner examined to exclude the possibility that the problem in it. If a man is healthy, then you should look for the causes of infertility in a woman.
It so happens that both the man and the woman are healthy, but pregnancy still does not occur. In this case you should be checked for physiological compatibility of the secretions of the cervix and sperm. Perhaps the women's field is so aggressive to semen men that the sperm cannot reach the egg and can't impregnate her.