광주기가 방사선에 의해 유발된 자주달개비 체세포돌연변이에 미치는 영향을 실험적으로 평가하였다. 포트에서 생육된 Tradescantia 4430 식물체에 코발트 선원으로부터 0.3, 0.5및 1.0Gy의 감마선을 조사하였으며 수술털 세포에 나타나는 분홍돌연변이를 분석하였다. 감마선 0.5 Gy를 기준선량으로 평가하였을 때 대조 실험군(CT)은 방사선 조사 후 6일 경과시부터 돌연변이율이 증가하기 시작하여 조사 후 10일째에 최고값에 도달하였다. 명기가 2

Drosophila의 actin 5C 유전자 promoter에 쥐의 DNA polymerase cDNA를 도입시킨 형질전환 초파리가 고감수성 환경성 변이원 검출계로 사용할 수 있는지를 조사하였다. 체세포 염색체 재조환과 체세포 염색체 돌연변이의 검출을 위해서는 geterozygous(mwh/+) 계통을 사용하였다. 염색체상의 결실이나 비분리 등에 의한 small mwh spot의 자연 발생적 빈도는 non-transgenic w 계통과 transgenic p[pol ]-130 계통에서 각각 0.351 및 0.606 정도였다. 체세포 염색체 재조환에 의한 large mwh spot의 자연 발생적 빈도의 경우는 transgenic p[pol ]-130 계통(0.063)이 non-transgenic w 계통(0.021)에 비해 약 3배 정도 높게 나타났다. IQ, Glu-P-1 및 TEXAFB1/TEX 등의 돌연변이원의 처리에 의한 경우, 두 종류의 mutant clone의 발생 빈도는 쥐의 DNA polymerase 가 도입된 transgenic p[pol ]-130 계통이 non-transgenic w 계통에 비하여 모두 약 2-3배 정도 높게 나타났다. 본 연구의 결과는 쥐의 DNA polymerase 가 최소한 체세포 염색체 돌연변이 유발이나 체세포 염색체 재조환의 생성 과정에 관여함을 의미하며, 형질전환 초파리 계통이 환경성 변이원 검출계로서 충분한 응용가능성이 있음을 보여 주었다.

Inactivation of the gene (DFR-A) coding for dihydroflavonol 4-reductase (DFR) involved in the anthocyanin biosynthesis pathway results in a yellow bulb color in onion (Allium cepa L.) and three inactive alleles have previously been identified in onion. Additionally, three active and six inactive DFR-A alleles were newly identified from extensive analyses of diverse onion germplasm. Presently, a yellow mutant containing a 171-bp deletion in the promoter region was identified and designated DFR-APD. Critically reduced transcription of this mutant allele and perfect co-segregation with color phenotypes in segregating populations were observed. Another yellow mutant (DFR-A5’DEL) containing a 518-bp deletion covering exons 1 and 2, which played important roles in DFR function, was identified. Meanwhile, both 2-bp and 4-bp insertions in the coding region leading to creation of pre-mature stop codons were also identified and designated DFR-AGT and DFR-A2AT, respectively. A 1-bp substitution mutation (DFR-AK48N) changing a positively charged lysine residue into a neutral asparagine was identified. This lysine residue, a NADPH binding site, was strictly conserved in other species. In addition, insertion of a leucine residue around substrate binding sites and catalytic triad was identified in several yellow accessions and was designated DFR-ATTA. Phylogenetic analysis of DFR-A alleles showed that all inactive alleles were independently derived from four different active alleles. In addition, the close relatedness and diversity of DFR-A mutants implied that all these mutations might have occurred after domestication of onions and had probably been maintained by artificial selection.

The reproductive activity in male mammals is well known to be regulated by the hypothalamus-pituitary-gonad axis. The hypothalamic neurons secreting gonadotropin releasing hormone (GnRH) govern the reproductive neuroendocrine system by integrating all the exogenous information impinging on themselves. The GnRH synthesized and released from the hypothalamus arrives at the anterior pituitary through the portal vessels, provoking the production of the gonadotropins(follicle-stimulating hormone (FSH) and luteinizing hormone (LH)) at the same time. The gonadotropins affect the gonads to promote spermatogenesis and to secret testosterone. Testosterone acts on the GnRH neurons by a feedback loop through the circulatory system, resulting in the balance of all the hormones by regulating reproductive activities. These hormones exert their effects by acting on their own receptors, which are included in the signal transduction pathways as well. Unexpected aberrants are arised during this course of action of each hormone. This review summarizes these abnormal phenomena, including various mutations of molecules and their actions related to the reproductive function.

eIF4E family is well known for recessive resistance gene of potyvirus in many crops. And Turnip mosaic virus (TuMV) is one of the major viruses in Brassicaceae crops which belong to the genus Potyvirus. To elucidate the key amino acids in the interaction between TuMV VPg and Brassica eIF(iso)4E, amino acids of eIF(iso)4E were mutated. Seven amino acids in cap binding pocket were chose for the candidate amino acid that may play a role in the interaction of TuMV VPg. We demonstrated that a single amino acid mutation in cap binding pocket of Brassica eIF(iso)4E can abolish the interaction with TuMV VPg. eIF(iso)4E which has a mutation at each W49, W95 and K150 positions impaired in its interaction with VPg prominently according to the yeast two hybrid analysis. Complementation of an eIF4E knockout yeast strain by mutated eIF(iso)4E proteins showed that all eIF(iso)4E mutants were able to complement eIF4E of yeast. To find out if these mutations affect the susceptibility of Chinese cabbage, transformant analysis was performed. eIF(iso)4E W95L, W95L/K150E and susceptible wild type were over-expressed in susceptible Chinese cabbage. According to the TuMV screening result of T1 and T2 transformants, over-expression of the eIF(iso)4E mutants showed resistance to four TuMV strains (CHN2, 3, 4 and 5). Our results support that the mutations in eIF(iso)4E may control the broad spectrum TuMV resistance.

The lutropin/choriogonadotropin receptor (LHR) is a member of the rhodopsin-like subfamily of G protein coupled receptor (GPCRs), that has been shown to mediate the internalization of its two naturally occurring agonist, lutropin and choriogonadotropin (CG). The clustered agonist-receptor complex is internalized by a dynamin-dependent pathway and traverses the endosomal compartment without agonist dissociation Dissociation of the agonist-receptor complex occurs in the lysosomes, where both the agonist and receptor are degrade. Recently, constitutively activating mutations of the receptor have been identified that are associated with familial male-precocious puberty (FMPP). A FMPP is a form of sexual precocious puberty in boys in which testosterone levels are elevated independent of changes in luteinizing hormone-releasing hormone and serum luteinizing hormone levels, We have now analyzed two naturally occurring, constitutively active mutants of the human LHR. These mutations were introduced into the rat LHR (rLHR) and are designated L435R and D556Y. Cells expressing rLHR-D556Y bind human choriogonadotropin (hCG) with normal affinity, exhibit a 25-fold increase in basal cAMP and respond to hCG with a normal increase in cAMP accumulation. Cells expressing rLHR-L435R also bind hCG with normal affinity, exhibit a 47-fold increase in basal cAMP, and do not respond to hCG with a further increase in cAMP accumulation. This mutation enhances the internalization of the free and agonist-occupied receptors ~2- and ~17- fold, respectively We conclude that the state of activation of the rLHR can modulate its basal and/or agonist-stimulated internalization. Since the internalization of hCG is involved in the termination of hCG actions, we suggest that the lack of responsiveness detected in cells expressing rLHR-L435R is due to the fast rate of internalization of the bound hCG. The finding that membranes expressing rLHR-L435R respond to hCG with an increase in adenylyl cyclase activity supports this suggestion. Autonomous Leydig cell activity in FMPP is caused by a constitutively activating LH/CGR.

In order to analyze the sex-linked lethal mutagenic effects of ethyl methanesulfonate (EMS) in Drosophila melanogaster, the mutagenicities from the attached-X and Basc method have been detected. The indexes of relative lethal mutations at 2.0 and 4.0mM EMS treated group using the attached-X method were about 1.5 and 2.4 times than that of 1.0mM treated group, respectively. EMS had more pronounced effect in the sperm and spermatid stages in the induction of X-linked lethal mutations during the spermatogenesis. And, in the induction of X-linked recessive lethal mutations from the Basc method, the mutation frequency of 4.0mM EMS treated group as compared with 2.0mM was more than three fold. Two assay systems used in this study can support mutually according to experimental purposes, and the area of its application can be considerably wide.