In most animals, oogenesis involves a syncytial “cyst” stage. Cysts are produced by incomplete mitotic divisions of gonial precursor cells, leaving the resulting cystocytes interconnected by cytoplasmic bridges. The bridges subsequently break down, liberating the developing gametes. In some animals (e.g. meroistic insects) cysts are “polarized”, such that certain cystocytes differentiate as supportive nurse cells, rather than oocytes. The variability of cysts in animal oogenesis contrasts with the relative universality of spermatogenic cysts, making the functional importance of cysts in oogenesis unclear. I have studied oogenesis in a polychaete worm, Ophryotrocha labronica (Annelida: Dorvilleidae). These worms produce polarized, two-celled oogenic cysts with one nurse cell and one oocyte. Such cysts resemble their better-characterized counterparts in meroistic insects. However, using a variety of light- and electron-microscopic techniques, I show here that the resemblance between O. labronica and meroistic insects is largely superficial. Rather, the roles of nurse cells and the mechanisms underlying cystocyte differentiation are quite distinct in both groups. Therefore, similarities between these polychaetes and insects are probably examples of convergent evolution rather than homology. These observations underscore the plasticity of oogenesis among animals. Mechanisms by which germ cells become distinct from somatic cells in animals are also a subject of considerable research activity. Two general modes of germ-cell specification have been described in animals: deterministic specification, which is typical of established model species (e.g., Drosophila melanogaster and Caenorhabditis elegans) and inductive specification, which, though it is the more-common mode among animals, has not been well studied. As an annelid worm, O. labronica likely specifies its germ cells inductively, and therefore has potential to serve as a model species for studies of inductive germ cell specification. Realizing this potential, however, will require the development of genetic resources for this species. I describe the beginnings of such work here: the isolation and characterization of a vasa/PL10-like gene whose expression is largely restricted to germ cells, the construction of a cDNA library, and the refinement of methods for in situ hybridization and immunostaining to visualize gene expression in whole worms.

Lic.-avh. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 2 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [93]-107).

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [76]-96).

Cryopreservation of fish germ cells has important applications in aquaculture, conservation of endangered species and human genomic studies. Although investigations on cryopreservation of fish sperm and embryos have been carried out extensively, cryopreservation of fish oocytes has not been studied systematically. The objective of the present study was to develop successful cryopreservation protocol for zebrafish oocytes at temperature of liquid nitrogen (-196°C), or if unachieved, to investigate the limiting factors associated with fish oocytes cryopreservation. In this study, the effects of cryoprotectants exposure and enzymatic treatments on oocytes survival were studied, and new viability tests for zebrafish oocytes were developed. The effects of controlled slow cooling with different cryoprotective agents, in different freezing media and at different cooling rates on cryosurvival of zebrafish (D. rerio) oocytes were investigated. Cryomicroscopic observations on zebrafish oocytes were also carried out. Three reliable vital tests -trypan blue (TB) staining, ATP assay, and in vitro maturation followed by germinal vesicle breakdown observation (GVBD) were found suitable for assessment of oocytes viability. Vitellogenesis (stage III) was found to be the optimal developmental stage for cryopreservation. Methanol was found to be the best CPA for zebrafish oocytes. Combination of 4M methanol and 0.2M glucose in potassium chloride (KCI) buffer was found to be the optimal cryoprotective solution. Controlled slow cooling at 0.3°C/min rate, combined with seeding at -12.5°C and plunge to liquid nitrogen (LN) at-40°C were found to be the optimal conditions for cryopreservation of stage III oocytes. However, even with the optimal protocol, TB-assessed viability, Le. the ratio of oocytes with intact plasma membrane after cooling to -196°C was 19.6±8%. Furthermore, GVBD experiments showed that none of the cryopreserved oocytes can be matured in vitro, and their ATP levels were decreased dramatically, indicating that successful cryopreservation of fish oocytes at liquid nitrogen temperature still remains elusive. Cryomicroscopic observations demonstrated, that the damages of oocytes are associated with intracellular ice formation (lIF). IIF occurred simultaneously with extracellular ice formation (ElF) in nearly 100% of the cases, and formation of lethal hexagonal type of ice was observed. This study was the first systematic attempt to cryopreserve fish oocytes at liquid nitrogen temperature. The results provided will undoubtedly assist successful protocol design for cryopreservation of fish oocytes in the future.

Orientadora: Elizabeth Romagosa / Banca: Sérgio Ricardo Batlouni / Banca: Rodolfo Nardez Sirol / Resumo: O trabalho foi conduzido com o objetivo de avaliar o efeito da temperatura de estocagem a curto prazo e da temperatura da água sobre os ovócitos e sêmen de jundiá, Rhamdia quelen. O experimento foi realizado em três etapas: (1) avaliar a qualidade dos ovócitos após estocagem e ativação em diferentes temperaturas; (2) padronizar a utilização de análise espermática computadorizada por meio de softwares livres; (3) avaliar os parâmetros espermáticos computadorizados após estocagem e ativação em diferentes temperaturas. Para a primeira, utilizou-se um delineamento experimental fatorial no tempo (5×3×3×3), com os tratamentos realizados em triplicata a cada 48h, na exposição de ovócitos nas temperaturas de 15; 25 e 35ºC e, ativados com água à 15; 25 e 35ºC cada, nos períodos de: 0; 45; 90; 135 e 180 minutos pós-coleta. A segunda etapa foi realizada através da captura de vídeos da movimentação espermática pelo software AMCAP, a uma taxa de 60 frames por segundo, processados no software VIRTUALDUB e analisados no software IMAGEJ por meio do aplicativo CASA. Os seguintes parâmetros foram analisados: taxa de motilidade espermática (MOT), velocidade curvilinear (VCL), velocidade média do deslocamento (VMD), velocidade em linha reta (VLR), linearidade (LIN), balanço (BAL) e freqüência de batimentos (FBAT). Os parâmetros espermáticos foram avaliados em um segundo de imagem nos tempos de 15, 25 e 35 segundos após a ativação espermática. Para a terceira etapa foi utilizado um delineamento experimental fatorial no tempo semelhante à primeira ,com 13 tempos de avaliação pós-coleta: 0; 2; 4; 6; 8; 10; 12; 16; 20; 24; 32; 40 e 48 horas. Os tratamentos foram realizados em triplicata e em protocolos sequenciais a cada 50 horas avaliando-se os parâmetros obtidos na segunda etapa. Estes foram submetidos às análises de correlação (Pearson) ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The study was conducted to evaluate the effect of temperature of storage in the short-term and the temperature of the water on the oocytes and sperm of jundiá, Rhamdia quelen. The experiment was conducted in three stages: (1) assess the quality of oocytes after storage and activation at different temperatures; (2) standardize the use of computerized sperm analysis by software free, (3) evaluate the computerized sperm parameters after storage and activation at different temperatures. For the first, was used a factorial experimental design in time (5×3×3×3), with treatments performed in triplicate every 48 hours, the exposure of oocytes at temperatures of 15, 25 and 35 C, and activated with water to 15, 25 and 35 C each, in the periods of: 0; 45; 90; 135 and 180 minutes post-collection. The second stage was performed by video capture of the movement of sperm through AMCAP software at a rate of 60 frames per second, processed and analyzed in VirtualDub software and ImageJ software using the CASA application. The following parameters were analyzed: rate of sperm motility (MOT), velocity curvilinear (VCL), velocity average path (VAP), velocity straight line (VSL), linearity (LIN), wobble (WOB), beating cross frequency (BCF). The sperm parameters were evaluated in a second image in the times of 15, 25 and 35 seconds after sperm activation. For the third step we used a factorial experimental design similar to the first in time, with 13 times of evaluation post-collection: 0; 2; 4; 6; 8; 10; 12; 16; 20; 24; 32; 40 and 48 hours. The treatments were performed in triplicate and sequencing protocols to be evaluated every 50 hours if the parameters obtained in the second stage. These were submitted to analysis of correlation (Pearson). The significant parameters (P<0.05) were summarized by the principals components analysis. For the first stage interaction (P<0.05) between time and temperature... (Complete abstract click electronic access below) / Mestre

Thesis (M. Sc. (Animal Production)) -- University of Limpopo, 2015 / The objectives of this study were: 1) To determine the effect of oocyte retrieval techniques (slicing and aspiration) on the quality and quantity of cattle oocytes, 2) To evaluate the effect of different concentrations of hormones on the maturational rate of cattle oocytes selected by brilliant cresyl blue staining, 3) To evaluate fertilization rate and cleavage/embryonic development of oocytes with or without cumulus cells, and 4) To compare the effect of fresh and frozen thawed semen on the fertilization rate of cattle oocytes. In Experiment 1: oocytes were recovered from abattoir derived ovaries using slicing and aspiration. The recovered oocytes were exposed for 90 minutes to 26μM of brilliant cresyl blue (BCB) stain and classified according to the colour of their cytoplasm: BCB+ (oocytes with blue cytoplasm) and BCB- (unstained oocytes). There was no difference (P>0.05) in the quality of oocytes recovered using slicing (60.7 %) or aspiration (53.7 %) techniques. In experiment 2: The BCB selected and the non-selected immature oocytes were randomly allocated into medium 199 + 10 % fetal bovine serum (FBS) maturation media. The media was supplemented with three different concentrations of hormones as treatments (T). The T1 (0.5 μg/ml of follicle stimulating hormone (FSH), 5mg/ml of luteinizing hormone (LH) and 2 μg/ml of estradiol (E2) as the control group. Then, T2 (1 μg/ml of FSH, 6 mg/ml of LH and 2.5 μg/ml of E2) and T3 (1.5 μg/ml of FSH, 7 mg/ml of LH and 4.5 μg/ml of E2). Maturation rate of oocytes was determined by the protrusion of the first polar bodies 24 hours following in vitro maturation. Treatment 2 yielded higher (P<0.05) maturation rate for both BCB+ (65.6 %) and without BCB (60.3 %) oocytes with T1 giving lower (P<0.05) maturation rate for BCB+ (22 %) and without BCB (16 %) oocytes. However, BCB- oocytes had lower (P<0.05) polar body extrusion (3.03 %, 8.1 % and 2.2 %) for T1, T2 and T3, respectively. In Experiment 3: one group of the presumptive zygotes was denuded of cumulus cells and the other group was cultured with cumulus cells. The presumptive zygotes were in vitro cultured in SOF-BSA and changed to SOF-FBS after 48 hours. High fertilization/cleavage rate was observed in oocytes cultured with cumulus cells (29.0 %) compared to the denuded oocytes (20.0 %) for 2-4 cells stage. Day 7 blastocysts were more (P<0.05) on oocytes cultured with cumulus cells (32 %) compared to denuded oocytes (13 %). In experiment 4: The matured oocytes were fertilized using fresh and frozen thawed semen. The oocytes fertilized with frozen thawed semen obtained a better number of 2-4 cell cleavage (23 %) when compared to fresh semen (19 %). Oocytes that were fertilized with frozen thawed semen also obtained higher morula (13 %) and blastocyst (8 %) compared to fresh semen with morula (3.4 %) and blastocyst (2 %). In conclusion, immature oocytes that were exposed to BCB+ and cultured in M199 supplemented with 10 % FBS, 0.5 μg/ml of FSH, 5 mg/ml of LH and 2 μg/ml of E2 had a higher (P<0.05) number of matured oocytes (extrusion of first polar body) compared to those that were not exposed to BCB (no BCB). Oocytes that were cultured with cumulus cells yielded a higher (P<0.05) number of cleaved embryos compared to the denuded oocytes. Slicing yielded a higher (P<0.05) number of oocytes, however the quality of oocytes recovered was similar compared to those recovered by the aspiration technique (P>0.05). Oocytes fertilized with frozen thawed semen yielded higher (P<0.05) number of 2-4 cell, morula and blastocyst when compared with oocytes that were fertilized using fresh semen. Keywords: ovaries, oocytes, slicing, aspiration, COCs, BCB, polar body and cattle

京都大学 / 新制・論文博士 / 博士(医学) / 乙第13537号 / 論医博第2277号 / 新制||医||1065(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 篠原 隆司, 教授 近藤 玄, 教授 齋藤 潤 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM