Speaking of the current milk, many people will blurt out "the milk is now prompted by hormones, taste nutrition will not work ... ...". The so-called "milk hormone" is actually a bovine growth hormone. In fact, it is currently not allowed in most countries. The United States approved its use in 1993, and it is still a country that runs counter to "international mainstream". Why do other countries need to be banned, and the United States wants to "take the big deal out of the world"? The role of "milk hormone" Growth hormone is a protein secreted in the animal's brain that is used to promote animal growth. The growth hormone of cattle is naturally called "bovine growth hormone", abbreviated bGH. Several decades ago, people discovered that injecting bGH into cows promoted milk production. However, this discovery did not make sense at the time. Because, at that time, bGH can only be extracted from the head of the dead cow, and its cost will greatly exceed the increased milk volume. In the 1980s, the development of biotechnology made it possible to use bGH. The gene that controls the synthesis of bGH is transferred to bacteria, and the same protein can be synthesized by culturing bacteria. The bovine somatotropin thus obtained is referred to as "recombinant bovine somatotropin", abbreviated as rbGH, and sometimes also referred to as rbST. Unlike the various legends about "milk hormones" in the society, rbGH does not allow milk cows to use plain milk for no reason. After milking a calf, cows will gradually increase their milk production, usually to 70 days Get to the max and then gradually fall. If the cow is injected with rbGH before reaching this maximum amount, the decline in milk production will be slow. In this way, dairy farmers can get more milk. On average, milk production can increase by more than 10% after the use of milk hormones. Is Milk hormone harmful to the human body? For most people, it is still concerned about whether the use of hormonal milk is harmful to health. This "possible harm" comes from two aspects, one is whether the hormone itself is harmful to health, and the other is whether the hormone used in the milk contains other harmful ingredients. "Milk hormones", whether natural bGH or "artificial" rbGH, are proteins. In general, after the protein is eaten, it is digested into amino acid fragments to be absorbed. But logically, we cannot rule out the possibility that the entire protein or large fragments will be absorbed. If this happens, there may be other effects on the human body that require long-term tests to determine if it is harmful. Otherwise, if it is broken down into a single amino acid, then just like other food proteins, it is not enough. In this case, it is not necessary to conduct more long-term experiments to verify its health effects. The U.S. Food and Drug Administration (FDA) required large doses of short-term animal experiments. In the 28 consecutive days, rats were fed a large dose of rbGH at a dose up to 100 times the injected dose of the cow. No abnormalities in the physiological parameters of the mice were observed. Therefore, the FDA believes that rbGH in foods will not be absorbed, so that it is not necessary to conduct long-term safety tests to make safe conclusions. However, Canadian food management authorities disagree with the FDA's conclusions. They believe that a study was omitted from the FDA's assessment. That study was part of a European study requiring rbGH safety. The experiment used different doses of rbGH to feed mice and detect antibody responses in mice. The results showed that rats weighing 0.5 mg per kilogram of body weight per day were not abnormal, but some of the rats in a dose of 5 mg had an antibody response, while those in a dose of 50 mg had more antibody responses. Canada believes that this means that rbGH can be absorbed, so the FDA's decision is not rigorous. The FDA re-evaluated whether rbGH could be absorbed, especially the results of this study. They believe that this study does not change the previous conclusions. Because the animal's antibody cells are spread throughout the body, antibodies produced by those antibody cells in the intestine can be transported to other parts of the body, so this result does not indicate that rbGH can be directly absorbed. However, such an explanation obviously only shows that the observed antibody is "not necessarily" produced by the absorbed rbGH, but this possibility cannot be denied. The FDA believes that there are two additional reasons why rbGH does not pose a safety concern: Even if antibodies are produced, their content is so low that they do not have any effect on the human body; the maximum amount of rbGH that the body can take from milk – such as A 10 kg child drinks 1.5 kg of milk with high concentration of rbGH every day, and its dose is only 0.0075 mg/kg body weight, which is far lower than the experiment will not lead to antibody reaction. "Safety dose" - 0.5 mg. The FDA's conclusion was supported by another study. In a paper published in 1988, if mice were given a dose of 0.15 mg/kg body weight of rbGH, body weight gain and blood rbGH antibodies were observed within 9 days. The addition of 40 mg/kg body weight of rbGH per day to food did not change. This can prove that rbGH in foods will not be absorbed directly, so it will not affect health. Is there any other harmful substance in the milk produced by "milk hormone"? Under modern analytical techniques, the composition of any food can be analyzed with considerable precision. Canada's analysis of milk reports that the use of rbGH increases the level of IGF-1 in milk. The full name of IGF-1 is "insulin-like growth factor I", which is a protein that has a wide range of physiological functions in the human body. Some epidemiological studies have shown that IGF-1 seems to have a relationship with prostate cancer and other cancers. If so, milk using rbGH presents potential health risks. The FDA believes that the relationship between IGF-1 and cancer is only a multi-factor correlation. So far there is no evidence that IGF-1 is the cause of cancer. In addition, the increase in IGF-1 caused by rbGH was small and less than the normal fluctuation of IGF-1 in milk. In other words, after a cow has used rbGH, the amount of IGF-1 in the milk produced will increase slightly, but the level after rise may still be lower than many cows that do not use rbGH. The body itself contains IGF-1. Regardless of whether or not you used rbGH, the obtained IGF-1 is insignificant compared to the body itself. In addition, after heating, digestion, and absorption, IGF-1 no longer has biological activity in the human body. In this issue, the FDA's conclusion is consistent with JECFA. JECFA is the Joint Expert Committee of Food Additives of the World Health Organization and the Food and Agriculture Organization of the United Nations. It is an international organization that is independent of commercial interests. To sum up, their attitude with the FDA is: RbGH does not have a substantial effect on IGF-1 in milk; IGF-1 in milk does not pose a health risk. In addition, JECFA's view of producing antibodies against rbGH in food is also consistent with the FDA. Is Milk hormone harmful to cows? There are still some doubts about whether the use of rbGH milk is harmful to health, but none of them are supported by biological theory or experimental results, and more are only some logical “possibilityâ€. The expert evaluation conclusion of Canada's food management department is also that "there is no evidence that the milk processed by rbGH will cause harm to human health," but they eventually rejected the use of rbGH. The reason is that the issue of animal welfare surfaced. The relevant professional committees in Canada and the European Union reviewed the effects of rbGH on the health of dairy cows and concluded that their use had caused damage to the health of cows. The most common damage is an increase in the incidence of mastitis, followed by adverse changes in the ability of the cow to produce, legs and feet. The cows that were injected with rbGH were not as healthy as the uninjected cows. The occurrence of mastitis may lead to an increase in the use of antibiotics. This in turn increases the likelihood that people will ingest antibiotics from milk, which will lead to new health risks. However, JECFA's assessment concludes that this “possibility†will not increase people’s health risk under the current regulations for the use of biosulfur in the milk industry. In fact, neither the EU nor Canada have raised any objection to the safety of milk using rbGH, but they believe that the use of rbGH has impaired the health of dairy cows. Therefore, it is mainly based on animal welfare considerations that rejected the use of rbGH. Milk labeling, not a word game In the United States, rbGH has been widely used since it was approved by the FDA. However, rbGH is exclusively produced by Monsanto. The reputation of the bio giant among consumers has not been very good. People's doubt about "hormone" products and the mistrust of producers are intertwined. American society has constantly criticized rbGH. Natural milk contains bovine growth hormone (bGH), and there is no technology that can distinguish it from synthetic "rbGH". At the same time, the use of rbGH does not pose security risks. According to FDA's practice, the use of rbGH does not require any labeling under such circumstances. In other words, the public will not be able to know if the purchased milk uses rbGH. Due to public misgivings, some milk producers have issued labels that are "non-hormone-containing" and have been banned by the FDA. Since cow's milk naturally contains hormones, "hormone-free" milk does not exist, and this label does not match the facts. One milk producer marked out "no rbGH". In essence, the fact expressed by such an annotation can be true. However, this mark was subject to the prosecution of Monsanto on the grounds that such an indication implies that "rbGH" is "problematic" and thus leads to misleading consumers. The case was eventually not heard in court, but ended in a settlement by both parties. As a result, the milk manufacturer stated in small print "without the label rbGH" that "the FDA has determined that there is no practical difference in the use or non-use of rbGH milk." The FDA recommends such an annotation, but it is not mandatory. From the observer's point of view, such an annotation reaches the greatest degree of compromise between both sides in favour of and against rbGH and conveys as objective information as possible. However, people who oppose rbGH still think this label is “incorrect†and FDA has also received many requests to ban rbGH.
PCR ( Polymerase Chain Reaction)
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It provides a way to make more copies of a portion of DNA.
We need to have PCR ingredients that include DNA portion, Buffer solution, Primer+DNA (tap polymerase), and Nucleotides during the preparation step.
In the step of PCR sequence, there are three steps in this section.
Step 1 Denaturation
The addition of heat is needed to separate the two strands of the DNA molecule.
Step 2 Annealing
Temperature, is going to be cool in this step, should allow the primers to bind to the specific segments.
Step 3 DNA Synthesis
To make more copies of the DNA.
Those three steps above keep repeating to make enough copies of the DNA fragments. It is the principle of how PCR machine works.
"Milk hormone" is not