Physiological Effects Of Dietary Organic Selenium On Silkworm,bombys Mori

Selenium(Se)is an essential trace element for humans and animals.It has various functions such as anti-oxidation,anti-tumor,anti-aging,improving immunity,etc.However,the existence of selenium has different effects of toxic and physiological on the body,and organic selenium has low toxicity and high bioavailability.It is great significance to study the physiological effects of organic selenium on the organism by using silkworm as a model creature.In this paper,different doses of organic selenium were used to feed silkworms to detect the characteristics of the organic selenium metabolism of silkworms,to study their effects on growth and development,oxidative stress and silk protein secretion,and to analyze the performance of selenium-enriched silk fibers.The main results of the study are as follows:1.After feeding with organic selenium,the main tissues and organs of the silkworm can produce an enrichment effect,the silkworm pupa can also enrich selenium,and selenium is also present in the cocoon silk.Organic selenium was used to feed silkworm in three different doses:4 mg/L,40 mg/L,400 mg/L.The test results showed that the silkworm fat body,silk gland,and digestive tube can be enriched with selenium;The enrichment effect of selenium can also be detected in silkworm pupa.The results of cocoon silk detection indicate that selenium can bind to the secreted silk protein.2.The effect on the growth and development of the silkworm feeding with organic selenium.The 5th instar silkworm continued to feed organic selenium at a concentration of 4 mg/L to the upper cluster.The results showed that compared with the control,there was no difference in the development time,body weight growth rate,mature silkworm body weight,cocoon formation rate,and pupa weight of the silkworm,suggesting that there was no adverse effect on the normal growth and development of the fifth instar larvae of silkworm;Feeding organic selenium at a concentration of 400 mg/L has a certain effect on the growth and development of the fifth-instar larvae of"(Jingsong×Haoyue)F1" male larvae and the silkworm named "Guangshi No.1" bred with artificial feed.It is speculated that when the concentration of organic selenium reaches a certain threshold,it can affect the growth and development of silkworm.3.The effect on silk protein synthesis of silkworm feeding with organicselenium.Feeding with organic selenium has no adverse effect on the amount of exocrine silk protein of the silkworm larvae of the large-scaled silkworm;Feeding with organic selenium at a concentration of 400 mg/L significantly reduces the amount of exocrine silk protein of "(Jingsong×Haoyue)F1" male silkworm.At the same time,it also reduced the amount of exocrine silk protein of the male and female of silkworms named "Guangshi No.1".Treatment of feeding with organic selenium will inhibit the expression of Bmfib-H and Bmfib-L,silk fibroin related genes;Treatment of feeding with organic selenium at a concentration of 4 mg/L will enhance the expression of Bmp25,while the concentration of 40 mg/L and 400 mg/L will inhibit the expression of Bmp25.Treatment of feeding with organic selenium can inhibit the expression of Bmser-l and Bmser-3 in silk gland tissues,and also enhance the expression of Bmser-2.Therefore,feeding with organic selenium at a concentration of 4 mg/L has no adverse effect on silkworm silk protein secretion,but the effect of feeding with organic selenium at a concentration of 400 mg/L on silk protein secretion is different.The effect of feeding with organic selenium on the silk fibroin gene in the silk gland tissue of silkworm has a dose effect.4.The effect on silk fiber performance by feeding with organic selenium.Silkworm cocoons obtained by the treatment of feeding with organic selenium showed significant selenium enrichment,and the conversion efficiency of selenium in silkworm cocoons was highest in the group of feeding with organic secretion at a concentration of 4 mg/L.The amino acid composition and thermal stability of the silk protein obtained by the treatment of feeding with organic selenium were not significantly different from those of the normal silk protein.The experiment proved that the selenium-rich silk protein played an important role in maintaining normal cell homeostasis of L929 mouse fibroblasts.It indicates that the selenium-enriched silk protein obtained by the treatment of feeding with organic selenium may have wider biomedical applications.5.The effect on the oxidative stress of the silkworm feeding with organic selenium.The experimental results found that feeding with organic selenium will increase the survival rate of silkworm under high temperature stress.The redox index test showed that the expression of CAT in the larval fat body from the organic selenium-fed group fed at room temperature was significantly higher than that of the control group,and the expression of Mn-SOD and CuZn-SOD decreased significantly;The expression levels of oxidative stress-related genes in the midgut were also significantly higher than those in the control group.Under high temperature stress,the expression of Tpx in the fat body from the organic selenium-fed group was significantly lower than that of the control group,and the expression of CAT had no significant change compared with the control group;Compared with the control group,there was no the significantly changed in the expression of Tpx in the midgut of the treatment group.The expression of CAT in the midgut of the treatment group was significantly lower than that of the control group.It can be seen that feeding with organic selenium can increase the resistance of silkworms on high temperature by inducing the changes of the level of oxidative stress in silkworms,and there are differences in the response of the genes related to oxidative stress in different tissues.