The GC-IGF1 axis-mediated testicular dysplasia caused by prenatal caffeine exposure.

Prenatal caffeine exposure (PCE) can induce testicular developmental toxicity. Here, we aimed to explore the underlying mechanism of this process in reference to its intrauterine origin. Pregnant rats were intragastrically administrated caffeine (30 and 120 mg/kg/day) from gestational days 9 to 20. The results showed that the male fetuses exposed to high dose of caffeine (120 mg/kg/day) had a decreased bodyweight and inhibited testosterone synthetic function. Meanwhile, their serum corticosterone concentration was elevated and their testicular insulin-like growth factor 1 (Igf1) expression was decreased. Moreover, the histone 3 lysine 14 acetylation (H3K14ac) level in the Igf1 promoter region was reduced. Low-dose (30 mg/kg/day) caffeine exposure, however, increased steroidogenic enzymes expression in male fetuses. After birth, the serum corticosterone concentration gradually decreased in the PCE (120 mg/kg/day) offspring rats, whereas the expression and H3K14ac level of Igf1 gradually increased, with obvious catch-up growth and testicular development compensation. Intriguingly, when we subjected the offspring to 2 weeks of chronic stress to elevate the serum corticosterone concentration, the expression of Igf1 and testosterone synthesis were inhibited again in the PCE (120 mg/kg/day) group, accompanied by a decrease in the H3K14ac level in the Igf1 promoter region. In vitro, corticosterone (rather than caffeine) was proved to inhibit testosterone production in Leydig cells by altering the H3K14ac level and the expression of Igf1. These observations suggested that PCE-induced testicular developmental toxicity is related to the negative regulation of corticosterone on H3K14ac levels and the expression of Igf1.

Critical developmental stages for the efficiency of somatic cell nuclear transfer in zebrafish.

Somatic cell nuclear transfer (SCNT) has been performed extensively in fish since the 1960s with a generally low efficiency of approximately 1%. Little is known about somatic nuclear reprogramming in fish. Here, we utilized the zebrafish as a model to study reprogramming events of nuclei from tail, liver and kidney cells by SCNT. We produced a total of 4,796 reconstituted embryos and obtained a high survival rate of 58.9-67.4% initially at the 8-cell stage. The survival rate exhibited two steps of dramatic decrease, leading to 8.7-13.9% at the dome stage and to 1.5-2.96% by the shield stage. Concurrently, we observed that SCNT embryos displayed apparently delayed development also at the two stages, namely the dome stage (1:30 ± 0:40) and the shield stage (2:50 ± 0:50), indicating that the dome and shield stage are critical for the SCNT efficiency. Interestingly, we also revealed that an apparent alteration in klf4 and mycb expression occurred at the dome stage in SCNT embryos from all the three donor cell sources. Taken together, these results suggest that the dome stage is critical for the SCNT efficiency, and that alternated gene expression appears to be common to SCNT embryos independently of the donor cell types, suggesting that balanced mycb and klf4 expression at this stage is important for proper reprogramming of somatic nuclei in zebrafish SCNT embryos. Although the significant alteration in klf4 and mycb expression was not identified at the shield stage between ZD and SCNT embryos, the importance of reprogramming processes at the shield stage should not be underestimated in zebrafish SCNT embryos.

[The growth promoting activity of two different kinds of reconstructed terminators in transgenic common carp].

The transgenic promoter directly affects the activity of transgenic gene. Choice of terminator has been proved to affect the activity of transgenic gene. Since the relevant theoretical research is rare, using the terminator of transgenic gene or the promoter gene to construct the transgenic vector has not come to the conclusion. In order to construct a better transgenic vector to nurture "all fish" growth hormone transgenic fish which has a rapid growth character, two different transgenic vectors were constructed separately by the terminator of beta-actin gene and the terminator of growth hormone gene. After micro-injection, we obtained the P0 generation of "all fish" transgenic fish farming groups. Comparing the activities of the two different transgenic vectors, the weight distribution of the breeding groups from growth hormone gene terminator transgenic vector felt into a normal distribution; however, the weight distribution of the breeding groups originated from beta-actin gene terminator exhibited a non-normal mode and in a rightist trend. The average weight of GH (Growth hormone) gene terminator transgenic groups was significantly higher than that of the beta-actin gene terminator transgenic groups. Interestingly, a fast-growth transgenic carp was found from a mixed farming group, which was positive for the growth hormone gene terminator. This result showed that "all fish" GH gene transgenic carp could grow fast, and the transgenic gene could inherit from generation to generation. Our results suggest that the growth hormone gene terminator transgenic vector has stronger growth-promoting activity than the beta-actin gene terminator transgenic vector.

[Polymorphism in intron 2 of crucian carp GH I gene].

High length and nucleotide polymorphisms in intron2 of GH I gene were detected in 162 individuals,which were from seven wild crucian carp colonies, two goldfish colonies and one Fangzheng crucian carp colony. Using denaturating polyareylamide gel electrophoresis (DPAGE) and single-strand conformation polymorphism (SSCP), seven length variants and 15 haplotypes were identified in these fishes. The length types and haplotypes diversity was 4.32% and 9.26%, respectively. Sequence analysis of the 15 haplotypes indicated the following results: (1) The size of intron2 varied from 243 to 263 bp. In the 15 haplotypes,the average percentages of the four bases (A,T,G and C) were 34.13%, 37.36%, 15.13% and 13.38%, respectively; the frequency of G + C(28.51%) was much lower than that of A + T (71.49%). The GT/AG domain was found in exon-intron junctions,which was the 5' and 3' splice donor and acceptor sites in higher eukaryotic gene introns. The similarity sequence of GTAAGTA was located on the junction between exon2 and intron2. And there existed a richer pyrimidine region (TTTGCCTTTTGTTATC) near the 3' end of intron2. (2) The seven length variants (A, B, C, D, E, F and G) were determined to be 189, 196, 204, 205, 206, 207 and 209 bp, respectively. The polymorphism resulted from the variable repeat number of T (N = 0, 8, 9, 10, 11 and 13) and the difference in one or two motifs deletions of TGAAAAC, TT and GAGTG. (3) Compared the sequences of the 15 haplotypes, 17 substitution sites were observed, of which two were of transversion sites and 15 were of transition sites. Obviously, the transition mutations (88.24%) were more frequent than transversion mutations (11.76%). Analysis of the distributions of the length types, haplotypes and composite genotypes suggested that genetic diversity was varied in different colonies. In the goldfish colonies, only one length type (A), two haplotypes (A1 and A2) and one composite genotype (A1A2) were observed. Two length types (C and D), four haplotypes (C1, C2, D2 and D5) and one composite genotype (C1C2D2D5) presented in the Fangzheng crucian carp colonies. The highest level of genetic diversity was exhibited in the seven wild crucian carp colonies: seven length types (A, B, C, D, E, F and G), 14 haplotypes (A1, A2, A3, B, C1, C2, D1, D2, D3, D4, E1, E2, F and G) and 14 composite genotypes (A1A2A3, A1A2A3B, A1C1C2D1D2D3, A1C1C2D2, A1C1C2D2D3, A1C1C2D3E2, BC1C2D2, BC1C2D3D4, C1C2D2, C1C2D2D3, C1C2D3D4, C1C2D3D4F, C1C2D4, D2E1G) were shared by the seven wild colonies. The numbers of observed length types, haplotypes and genotypes within the wild colonies ranged from 3 to 6, 6 to 10 and 2 to 6, respectively. Whether the length and nucleotide polymorphisms in the intron2 of crucian carp GH I gene were associated with gene expression and gene regulation remained unsolved and required further investigations.