No description available.

No description available.

No description available.

京都大学 / 新制・課程博士 / 博士(生命科学) / 甲第25516号 / 生博第532号 / 新制||生||70(附属図書館) / 京都大学大学院生命科学研究科統合生命科学専攻 / (主査)教授 鈴木 淳, 教授 北島 智也, 教授 見学 美根子 / 学位規則第4条第1項該当 / Doctor of Philosophy in Life Sciences / Kyoto University / DFAM

Quaternary ammonium compounds (QACs) are antimicrobial disinfectants commonly used in commercial and household settings. While these compounds have been used for decades, reproductive toxicity has not been thoroughly evaluated. Extensive use of QACs results in ubiquitous human exposure to potentially toxic compounds. Reproductive toxicity of two common QACs, alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC), was investigated to determine gender-specific toxicity with an emphasis on male reproductive function. Breeding pairs of mice exposed for six months to ADBAC+DDAC exhibited decreases in fertility and fecundity, with fewer pregnancies and decreased numbers of pups over a six month period. Females proceeded through significantly fewer estrus cycles, and both ovulation and implantation rates were reduced. Males exhibited declines in both sperm concentration and motility. Male reproductive toxicity was further assessed in a series of in-vitro and in-vivo experiments. ADBAC+DDAC were cytotoxic to testicular Sertoli cells in culture at concentrations greater than or equal to 0.0005%. Changes in blood-testis-barrier integrity (BTB) were observed at 0.01% ADBAC+DDAC using a two-compartment culture system that measures transepithelial electrical resistance (TER). Sertoli cell cytotoxicity correlated with decreased TER at ADBAC+DDAC concentrations above 0.001%. In-vitro fertilization capacity of epididymal sperm was reduced in males given a 10-day rest period following ADBAC+DDAC exposure. Multigenerational changes in sperm parameters and in mRNA expression of enzymes involved with epigenetic modifications were evaluated across three generations. Sperm concentration and motility were reduced in F0 males exposed directly to ADBAC+DDAC. In F1 males, sperm concentration was increased and motility decreased, while there was no change in the F2 progeny. Genes involved in epigenetic modifications were altered in the exposed F0, with upregulation of two histone acetyltransferases (Hat1 and Kat2b) and downregulation of one lysine-specific demethylase (Kdm6b). F1 and F2 generations were not different from controls except for downregulation of the methyltransferase Dnmt1 in F1 progeny. The reproductive toxicity of ADBAC+DDAC identified in these studies, particularly to the male, compels further investigation into the potential effects that these compounds may have on human reproduction. / Ph. D.

Master of Science

Thesis (M.Sc.). / Written for the Dept. of Animal Science. Title from title page of PDF (viewed 2009/07/07). Includes bibliographical references.

Esta investigação tem a finalidade estudar experimentalmente os efeitos do ultra-som pulsado de baixa intensidade sobre a espermatogênese de ratos pré-púberes e adultos. Foram utilizados 40 ratos machos da raça Wistar, sendo 20 pré-púberes e 20 adultos, os quais tiveram os testículos estimulados por 15 minutos durante 10 dias consecutivos. Cada grupo experimental constou de 10 animais pré-púberes ou adultos, estimulados com o ultra-som pulsado de baixa intensidade ou não estimulados. Administrou-se Colchicina, 6 horas antes do sacrifício dos animais com a finalidade de bloquear a divisão das células em metáfase para facilitar a avaliação do ciclo espermatogenético. Mediante morfometria estimou-se as áreas dos túbulos seminíferos e fez-se a avaliação dos estadios do ciclo espermatogenético quando foi constatado um aumento significativo das áreas dos túbulos seminíferos dos animais estimulados. O ciclo espermatogenético de ratos pré-púberes e adultos foi avaliado mediante contagens de associações celulares do ciclo nos estadios VII e VIII e XIV, correspondentes ao fim e início de cada ciclo. Houve aumento temporal do ciclo espermatogenético por apresentar maior número de associações com características dos estadios VIII significando acentuada maturidade de espermatozóides nos ratos pré-púberes estimulados. Os testículos dos animais adultos estimulados apresentaram aumento de peso em relação aos dos controles, exibindo uma diferença significativa. Nossos resultados são compatíveis com a hipótese de que o ultra-som pulsado de baixa intensidade estimula o aumento do peso dos testículos dos ratos adultos e das áreas dos túbulos seminíferos, bem como acelerando o ciclo espermatogenético em ratos pré-púberes. / This is an experimental study of the effects of low intensity pulsed ultrasound on the spermatogenesis of prepubertal and adult male rats. Forty male Wistar rats - twenty prepubertal and twenty adults -, whose testicles were stimulated for fifteen minutes for ten consecutive days were studied. Each experimental group was composed of ten prepubertal or adult animals, stimulated with low intensity pulsed ultrasound or not. Six hours before killing, the rats were given Colchicine to block the division of metaphasic cells, in order to facilitate the assessment of the spermatogenetic cycle. The area of the seminiferous tubule was done estimated by morphometry and the stages of spermatogenetic cycle were assessed, showing a significant increase of the areas of the seminiferous tubules of the stimulated animals. The spermiogenesis of prepubertal and adult rats was assessed through counts of cell associations in the stages VII and VIII and XIV, corresponding to the end and beginning of each cycle. There was a temporal increase in the spermatogenetic cycle due to a higher number of the associations with stage VIII characteristics, which means accentuated sperm cell maturity of the stimulated prepubertal rats. The testicles of the stimulated animals were weight increase regarding the of the control animals, showing a significant difference. Our results are compatible with the hypothesis that the low intensity pulsed ultrasound stimulates the increase of the testicle weight, the rats adults, and the area of the seminiferous tubules as well as accelerating the spermatogenetic cycle in rats prepubertal.

Further studies of Stk31 in spermatogenesis in vivo would allow the identification of the asymmetry machinery of GSCs and the signaling mechanism underlying cell fate determination. Further studies of STK31 in cancer stem cells would allow the development of new diagnostic and therapeutic approaches. / In the first part of the experiment, the expression and cellular localization of STK31 were investigated. RT-PCR results showed that STK31 was reactivated in 47 -- 86% of multiple cancers. Immunofluorescent study and GFP tagging experiment showed that STK31 was localized in the cytoplasm and formed aggregated granules that divide asymmetrically during mitosis. Further study by co-staining with E-cadherin demonstrated that the mouse homolog, Stk31, was expressed in the transition state between undifferentiated and differentiated spermatogonia. These data suggest the possible involvement of STK31 in mouse spermatogonia and cancer development. / In the second part of the experiment, the function of Stk31 in mouse spermatogonia was investigated- A GSC culture on an STO feeder layer was established. Studies on growing properties, expression of molecular markers and germ cell transplantation showed that GSC culture maintained spermatogonial stem cell activity. Retinoic acid was then used to induce differentiation of GSC. The differentiation status was confirmed by monitoring the expression of molecular markers. RT-PCR and immunofluorescent study showed that the expression of Stk31 was induced in RA-induced differentiation and Stk31 proteins were asymmetrically distributed during GSC division. Overexpression of Stk31 in GSCs using retroviral transduction induced the differentiation phenotypes. These data indicate the involvement of Stk31 in mouse spermatogonia cell fate determination. / In the third part of the experiment, the function of STK31 in human colon cancer was investigated. A stable STK31 knock-down Caco2 cells were established by stably transfecting two miR RNAi designs with different efficiency into Caco2 cells. Flow cytometry analysis showed that knock-down of STK31 resulted in G1 phase arrest. Cell counts and MTS assays suggested that knock-down of STK31 decreased cell proliferation in confluent cultures. Knock-down of STK31 also enhanced cell attachment to several ECM proteins and decreases cell migration as suggested by attachment assays and migration assays. Moreover, knock-down of STK31 enhanced enterocytic differentiation and inhibited tumorigenicity both in vitro and in vivo as indicated by colony formation assays and xenograft assays. Date obtained from whole genome microarray studies indicate that STK31 regulates these "stemness" properties through altering the expression of key players in various pathways including KIT, SMAD1 and Cyclin D2. These results suggest the involvement of STK31 in colon cancer as a regulator of "sternness". / Spermatogenesis is a complicated process involving mitosis, meiosis and post-meiotic differentiation. Due to the lack of in vitro models, genes that are involved in mammalian spermatogenesis are largely unknown. Spermatogenesis and tumorigenesis share important biological similarities. This co-relation can be signified by a special group of genes called cancer/testis (CT) antigens, which are only expressed in the testes and cancer. Although cancer biology has been extensively studied for decades, promising therapeutic methods are not available for every type of cancer. Recent discovery of cancer stem cells and functional genomics studies have shed light on the development of new diagnostic and therapeutic approaches. This thesis describes the expression, cellular localization and function of a novel CT gene, STK31, in spermatogonia and cancer development. / Fok, Kin Lam Ellis. / "December 2009." / Adviser: H.C. Chan. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 143-169). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Thesis (Ph. D.)--University of Missouri--Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 107-112). Also available on the Internet.