Successful Cultivation of Albino Mauremys mutica for the First Time

Zhenming REN, Keming REN, Shaoming REN, Bingjing LIU, Yue ZHAO

1. Shanyueguigu Turtle Farm, Foshan 528000, China; 2. Gannan Medical University, Ganzhou 341000, China；3. Bureau of Industry and Information Technology of Zhanggong District, Ganzhou 341000, China

Abstract Artificial albino Mauremys mutica was bred by a wild female albino M. mutica (P). F1 progeny was bred by mating between albino female turtle (P) and common male turtle, and F2 progeny was bred by mating between mature F1 male turtle with albino female turtle (P). After 7-8 years of cultivation, the artificial albino M. mutica was successfully produced from the F3 progeny bred in 2007, which was the first artificial breeding of the albino M. mutica. Through the cultivation of 18 batches of 5 generations (F5), the emergence rate of albino M. mutica reached more than 85%, and it could reach 100% in some cases. A stable albino M. mutica gene was produced for the first time.

Key words Mauremys mutica, Albino, First artificial cultivation

1 Introduction

Mauremysmuticais a genus in the Geoemydidae family[1-3], having two different subspecies, namely, M.m. mutica and M.m.kami. The first is widely distributed in southern China and northern Vietnam, while the latter is distributed in the Bachongshan Islands in the west of the Ryukyu Islands[4-6].M.muticais not only a famous and high-quality aquatic product in China, but also a traditional Chinese medicine. It is one of the 12 terrapin medicines recorded in theCompendiumofMateriaMedica, and has been widely bred. As of 2007, the number ofM.muticaraised in China reached nearly 10 million[7]. Albinism is that the melanocytes in life lack tyrosinase and cannot turn tyrosine into melanin, the skin is white or light red, the iris and choroid do not contain pigment, so the iris is red and transparent[8-9]. Albino individuals are rare in nature[10], but after artificial breeding, a small number of albino individuals can be cultivated[11-12]. The artificial cultivation of albinoM.muticahas not been reported. A mature female albinoM.mutica(P) was acquired by Shanyueguigu Turtle Farm in 2000. After 7-8 years of cultivation for three generations, the artificial albinoM.muticawas successfully bred for the first time in 2007. After more than five generations of cultivation, the emergence rate of albinoM.muticareached more than 85%, and it could reach 100% in some cases.

2 Materials and methods

2.1 Materials

2.1.1Sources. AlbinoM.mutica(P) was purchased from Qingping Market in Guangzhou in September 2 000 (female, about 10 years old, with a carapace length of 21.8 cm, a plastron length of 19.8 cm and a body weight of 1 347 g). The maleM.muticawas a common individual, and one with a very light color was selected from Shanyueguigu Turtle Farm (9 years old, with a carapace length of 24.9 cm, a plastron length of 21.3 cm and a body weight of 1 204 g).

2.1.2Feeding environment. The breeding pond, located in Foshan City, Guangdong Province, is a rectangular white PVC pool with an area of 1 m×2 m, including a water area of 1.5 m2and a sand pool of 0.5 m2. The land area was built above the water surface (the upper part is land, and the lower part is hole), covering an area of 0.5 m2. The source was tap water, the water level was 30 cm, the water was light green, floating with water lettuce, and the transparency was about 30 cm.

2.2 Methods

2.2.1Biological observation and feeding. The albinoM.mutica(P) was milky white and the shell joint was pink and white. The top of the head, the front of the tail, fingernails and the scales on limbs were milky yellow. The cheeks, tails and the ventral sides of the limbs were white. The eyeball and iris were blood red and transparent. The albinoM.mutica(P) had strong aquatic property and often lived in the water during the day. On sunny days, the time spent in the sun on land was less than that of ordinary individuals. When the weather was hot, it hid in the hole to prevent sunstroke, with less activity. When the temperature was high from the end of April to the end of September every year, the activity and food intake were relatively high, and it was fed with fresh fish meat, diet pellet, as well as grapes, papaya and other fruits. The optimum ambient water temperature was 25-30 ℃ and it was fed every 2 to 3 days. The turtle basically stopped eating at about 20 ℃, gradually went into hibernation at about 15 ℃, and fell into deep hibernation at about 10 ℃. At the end of March of the following year, the turtle gradually woke up when the water temperature was about 15 ℃. At this time, the turtle only crawled and did not eat. It doesn’t eat until the water temperature rose to about 20 ℃ in April.

3 Results and analysis

3.1 F1 progeny cultivationThe albino female turtle (P) was mixed with a lighter male turtle in the breeding pond, and the mating phenomenon occurred at the end of April to October. The albino female turtle (P) laid 6 eggs, 5 of which were fertilized on April 24, 2001; laid 5 eggs on May 12, all fertilized; laid 6 eggs, 5 of which were fertilized on June 21. The albino female turtle (P) laid 6 eggs, 5 fertilized on April 20, 2002; laid 5 eggs, all fertilized on May 9; laid 7 eggs, 5 fertilized on May 30; laid 5 eggs, all fertilized on June 17. On April 22, 2003, 7 albino female turtles (P) laid 7 eggs, 6 fertilized; laid 5 eggs, all fertilized on May 5; laid 7 eggs, 5 fertilized on May 29. The fertilized eggs were placed in parallel in vermiculite at intervals of 2 cm each. The humidity of the incubation medium was kept at about 9%, the air humidity 80%-90%, the temperature 28-30 ℃, and the incubation period 55-60 days. The egg was white, long oval, with a major diameter of 41.2 to 44.3 mm, a minor diameter of 31.2 to 36.4 mm and a weight of 12 to 16.3 g. There were 13 baby turtles (3 males and 10 females) in 2001; 17 baby turtles (5 males and 12 females) in 2002; 14 baby turtles (4 males and 10 females) in 2003. The baby turtle weighed 711 g. However, no albino individuals were obtained from 2001 to 2003.

3.2 F2 progeny cultivationIn August 2003, the albino female turtle (P) was mixed with the lightest of the three F1 male turtles, and the original common male turtle was abandoned. The albino female turtle (P) laid 6 eggs, 3 fertilized on April 10, 2004; laid 5 eggs, 3 fertilized on May 13; laid 6 eggs, 2 fertilized on June 2. On April 16, 2005, albino female turtles (P) laid 4 eggs, 3 fertilized; laid 5 eggs, 4 fertilized on May 7; laid 5 eggs, 4 fertilized on May 31; laid 5 eggs, 4 fertilized on June 16. On April 12, 2006, 7 albino female turtles laid 7 eggs, 6 fertilized; laid 6 eggs, all fertilized on May 6; laid 6 eggs, all fertilized on June 23, 2006. The fertilized eggs were hatched according to the steps in Section3.1. 8 baby turtles with 3 males and 5 females were obtained in 2004; 14 baby turtles with 5 males and 9 females were obtained in 2005; 17 baby turtles with 5 males and 12 females were obtained in 2006. Albino individuals were not obtained from 2004 to 2006.

3.3 F3 progeny cultivationIn August 2006, the albino female turtle (P) was mixed with the lightest of the three F2 males bred in 2004, and the original F1 male turtle was abandoned. The albino female turtle (P) laid 7 eggs, 3 fertilized on April 5, 2007; laid 5 eggs, 3 fertilized on April 28; laid 4 eggs, 3 fertilized on May 22; laid 6 eggs, 4 fertilized on June 18, 2007. The albino female turtle (P) laid 6 eggs, 5 fertilized on April 8, 2008; laid 5 eggs, 4 fertilized on May 1; laid 4 eggs, 3 fertilized on May 22; laid 5 eggs, 3 fertilized on June 17. The albino female turtle (P) laid 6 eggs, all fertilized on April 6, 2009; laid 7 eggs, all fertilized on April 21; laid 7 eggs, 6 fertilized on May 16. The fertilized eggs were hatched according to the steps in Section3.1. 13 baby turtles were obtained in 2007, 3 males and 10 females, including 3 albino baby turtles, 1 male and 2 females; 14 albino baby turtles were obtained in 2008, 3 males and 11 females, including 4 albino baby turtles, 1 male and 3 females; 18 albino baby turtles were obtained in 2009, 5 males and 13 females, including 4 albino baby turtles, 2 males and 2 females. By the end of 2007, albino individuals were finally obtained from F3 progeny, and the albinism rate of baby turtles was 21.4% to 28.8% (Fig.1).

3.4 F4 progeny cultivation

3.4.1P×F3 to cultivate F4 progeny. In August 2010, the albino female turtle (P) was mixed with one of the two F3 albino male turtles bred in 2007, and the original F2 male turtles were abandoned. From April to June 2011, albino female turtle (P) laid a total of 21 eggs (4 times), 12 fertilized, and produced 11 baby turtles, including 6 albino baby turtles (2 males and 4 females). From April to June 2012, albino female turtle (P) laid a total of 23 eggs (4 times), 18 fertilized, and produced 17 baby turtles, including 9 albino baby turtles (3 males and 6 females). From April to June in 2013, albino female turtle (P) laid a total of 22 eggs (4 times), 19 fertilized, and produced 17 baby turtles, including 8 albino baby turtles (2 males and 6 females).

3.4.2F3×F3 to cultivate F4 progeny. The F3 albino baby turtles obtained in 2007, 2008 and 2009 were raised in three different breeding ponds to cultivate F4 progeny. The number of eggs and hatching rate are shown in Table 1. It can be seen from the table that F4 progeny was able to produce albino individuals stably. The albinism rate of F4 progeny cultivated by F3×F3 was 47.1%-54.5%, and the albinism rate of F4 progeny cultivated by P×F3 was 48.4%-63.9%. Thus it can be seen that the number of albino genes of artificially bred F3 progeny was similar to that of parent P.

Table 1 F4 progeny cultivation

3.5 F5 progeny cultivation

3.5.1F4 generation in the same brood to cultivate F5 generation. 1 male and 2 females in the same brood were selected from F4 progeny bred by F3 progeny in 2007 and F4 progeny bred by F3 progeny in 2008, three groups were derived from each with a total of six groups. The individuals of the same brood were put into six feeding ponds to cultivate F5 progeny, respectively. The number of eggs laid and the production rate of baby turtles are shown in Table 2.

Table 2 F5 progeny cultivation

3.5.2F4 generation in different brood to cultivate F5 generation. 3 males and 6 females were selected from F4 progeny bred by F3 progeny in 2007 and F4 progeny bred by F3 progeny in 2008, respectively. The male turtles of F4 progeny bred by F3 progeny in 2007 and the female turtles of F4 progeny bred by F3 progeny in 2008 were mixed. The male turtles of F4 progeny bred by F3 progeny in 2008 and the female turtles of F4 progeny bred by F3 progeny in 2007 were mixed and put into six breeding ponds to cultivate F5 progeny of different brood (Fig.1). The number of eggs and the production rate of baby turtles are shown in Table 2. It can be seen from Table 2 that the number of eggs laid and fertilization rate of individuals in the same brood was similar to those in different brood, but there was a great difference in the production rate of albino baby turtles. The production rate of albino baby turtles by individuals in the same brood in 2017 and 2018 was between 80.0% and 95.8%, the average albinism rate was more than 85%, and the albinism rate was 100% in some brood. The production rate of albino baby turtles by individuals in different brood was significantly low. In 2017 and 2018, the albinism rate was between 61.5% and 86.9%, which was significantly lower than that of individuals in the same brood, and the albinism rate fluctuated greatly.

Fig.1 One-year old F3 generation albino turtles

Fig.2 Shelling of F5 generation albino turtles

4 Discussion and conclusion

4.1 Discussion

4.1.1The higher the progeny, the higher the albinism rate. If there is a lack of tyrosinase or loss of tyrosinase activity in vertebrates, melanin cannot be synthesized, resulting in albinism. Autosomal recessive genetic diseases, environment-induced gene mutations or inbreeding may lead to the emergence of albino individuals[13-14]. Therefore, it is very rare to obtain albino provenances. We cultivated the albino population based on the albino individuals obtained in 2000 as provenances. In the process of cultivation, it was found that the higher the progeny, the higher the albinism rate. No albino individuals were found in F1 and F2 progeny, and the albinism rate of F3 progeny was 21.4%-28.8%, respectively. The albinism rate of F4 progeny cultivated by F3×F3 was 47.1%-54.5%. The albinism rate of F4 progeny cultivated by P×F3 was 48.4%-63.9%. The albinism rate of F5 progeny cultivated by F4×F4 was 61.5%-95.8%, the average albinism rate was more than 85%, and the albinism rate was 100% in some brood. From F1 to F5, the albinism rate increased step by step, and from F3 progeny, the albinism rate increased by 20%-30% for each additional generation.

4.1.2Higher albinism rate in the progeny cultivated by parents with closer relationship. Inbreeding may lead to the emergence of albino individuals[13-14]. Taking F5 as an example, there was a great difference in albinism rate between F4 individuals in the same brood and F4 individuals in different brood. The albinism rate of F5 progeny cultivated by F4 individuals in the same brood was between 80.0% and 95.8%, the average albinism rate was more than 85%, and the albinism rate in some brood was 100%. The albinism rate of F5 progeny cultivated by F4 individuals in different brood was significantly low, and the albinism rate was between 61.5% and 86.9%, which was significantly lower than that of F4 individuals in the same brood, and the albinism rate fluctuated greatly. By analogy, the albinism rate of the progeny of the albino individuals with close relation was higher than that of the albino individuals with distant relation.

4.1.3Comparison between albino individuals and ordinary individuals. The maturation time, growth rate, brood number, number of eggs, egg-laying time, heat/mating period, fertilization rate and hatching rate of albino individuals were the same as those of ordinary individuals, and there was no significant difference between albino individuals and ordinary individuals. Generally speaking, 2-3-year-old male turtles had the ability to reproduce, but the fertilization rate was low, and 4-year-old females could lay eggs. For ordinary individuals, the annual number of eggs laid by F1-F5 progeny was between 20 and 28; for 5-year-old female turtles, the annual number of eggs laid by F1-F5 progeny was about 32. The fertilization rate of both female and male turtles was related to the age of their parents. Overall, the fertilization rate of 2-3-year-old male turtles mating with fully mature females over 7 years old was about 30%. If mating with 4-year-old mature female turtles, the fertilization rate was very low, or even there were no fertilized eggs. Similarly, if 4-year-old mature female turtles mated with more than 6-year-old mature male turtles, the fertilization rate was also about 30%. If mating with 2-3-year-old male turtles, there were no fertilized eggs. It can be seen that both ordinary and F1-F5 individuals of male turtles had the ability to reproduce at the age of 2 and 3, and were fully mature at the age of more than 6; female turtles could lay eggs at the age of 4 and were fully mature at the age of more than 7. In normal cultivation, fully mature male and female individuals should be used as parents as far as possible. If the conditions are limited, the old male turtles can mate with the young female turtles or the old female turtles can mate with the young male turtles to get a small quantity of progeny; if the weak young male turtles mate with the young female turtles, we generally cannot get the baby turtles. Albino individuals also go ashore to bask in the sun like ordinary individuals, but the time is less than that of ordinary individuals. This may be related to the lack of melanin in albino individuals and their inability to resist a large number of ultraviolet rays for a long time.

4.2 ConclusionIn recent years, there has been a strong international interest in albino mutant amphibians and reptiles, but for turtles, it is mainly reflected in the breeding ofTrachemysscriptaelegans. Now more than ten varieties of mutantTrachemysscriptaeleganshave been bred abroad. However, theTrachemysscriptaelegansis an alien species and has invaded the ecological environment system of our country. In this paper, it is the first time to cultivate the albino native species—M.mutica, which is beneficial to protecting the ecological environment of our country[15-16]. At the same time, it can also help to open up new aquatic products, form local brands, earn foreign exchange, promote the transformation of local industrialization in rural areas, and drive rural young people to return.