There is no abstract available for this thesis.

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

No description available.

Sex-specific growth analyses were conducted for 32 nestling ospreys (Pandion haliaetus) in a migratory population in Nova Scotia, Canada and for 31 nestling ospreys in a sedentary population in Sonora, Mexico. Eight variables including weight, body components and plumage characteristics were measured to document the influence of sex on growth performance. Within populations, males differed significantly from females in having lower weight and body component asymptotes but did not differ in plumage characteristics or growth rates. There was no difference in growth performance between individuals in broods of various sizes or within broods as a result of hatching order asynchrony. Comparisons of geographic variation showed that sedentary ospreys in Mexico had significantly higher weight and tarsus asymptotes, reduced growth rates, longer nestling periods and later emergence of flight feathers than migratory ospreys. Individual nestlings were initially identified by sex from karyotypic analysis of fibroblast tissue collected from a sample of 31 nestlings in the field. The karyotype is presented and growth performance is discussed within the framework of evolutionary theory.

Precise sexing–97% to 99% accuracy–of adult chest plates is possible when highly predictive costal cartilage ossification patterns are combined with four simple metric determinations. More than 1100 chest plate roentgenograms were evaluated for ossification pattern, fourth rib width, corpus width, sternal length and sternal area in an adult decedent population. An elementary, empirically obtained algorithm using the patternings and measurements, along with simple derivations (sternal length and area indices) was developed and then applied in chest plate sexing. This technique is not only easy, rapid and inexpensive, but it also results in a permanent and easily stored record.

No description available.

Orientador: Vera Fernanda Martins Hossepian de Lima / Banca: Lindsay Unno Gimenes / Banca: Beatriz da Costa Aguiar Alves Reis / Resumo: Os procedimentos durante a sexagem pelo citômetro de fluxo garantem a acuidade de 85%, mas causam danos na viabilidade espermática que levam a baixa taxa de prenhez após os 90 dias. Os objetivos dessa Dissertação foram: 1) caracterizar a expressão gênica diferencial em transcriptoma de espermatozoides congelados pelo método convencional, sexados por centrifugação em gradiente de densidade ou sexados por citometria de fluxo; 2) comparar as taxas de clivagem e de blastocistos produzidos in vitro de bovinos utilizando sêmen convencional, sexado por citometria de fluxo ou por centrifugação em gradiente de densidade. Os grupos experimentais para sêmen e embriões foram: 1) grupo controle: sêmen convencional submetido ao gradiente de PercollTM 45/90% e respectivos embriões produzidos com esse sêmen; 2) grupo gradiente: centrifugação em gradiente de densidade e respectivos embriões produzidos com esse sêmen; 3) grupo citometria: sêmen sexado pelo citometro de fluxo, submetido ao mini gradiente de PercollTM 45/90% e respectivos embriões produzidos com esse sêmen. O RNA total foi extraído dos espermatozoides (20 x 10 6 células) obtendo-se 400 ng RNA/ 20 x 10 6 células/ animal, ou seja, 20 fg RNA por espermatozoide. Entretanto, não foi posível a construção da biblioteca de cDNA, provavelmente, devido ao alto grau de degradação do RNA. Os Complexos cumulus oócito (COCs) classificados como graus 1, foram aspirados de folículos antrais de 3 a 8 mm de diâmetro a partir de ovários de abatedouros e maturados durante 18 horas em estufa a 38,5°C, 100% de umidade e atmosfera de 5% de CO2 em ar. Os oócitos maturados serão colocados em contato com os espermatozoides previamente preparados para fecundação e incubados por 20 horas em 5% de CO2, na temperatura de 38,5°C. Os prováveis zigotos serão lavados por três vezes em meio SOF (meio sintético de fluido de oviduto) sem SFB e sem glicose e cultivados e transferidos... / Abstract: The procedures for sexing by flow cytometry guarantee the accuracy of 85%, but cause damage in sperm viability leading to lower pregnancy rate after 90 days of pregnancy. The objectives of this study were: 1) to characterize differential gene expression in transcriptome of spermatozoa frozen by conventional method, sexed by density gradient centrifugation, by flow cytometry. 2) Compare blastocyst and cleavageratesproduced in vitro by conventional semen sexed by flow cytometry and by density gradient centrifugation. The experimental groups for semen and embryos were: 1) control group: conventional semen subjected to PercollTM gradient of 45/90% and their embryos produced with this semen, 2) gradientgroup: centrifugation in density gradient and their embryos produced with this semen, 3) cytometry group: semen sexed by flow cytometer, subjected to PercollTMmini gradient 45/90% and their embryos produced with this semen. Total RNA was extracted from sperm (20 x 10 6 cells) and it was possible to extract 400 ngRNA/ 20x10 6 cells/animal or it means, 20 fg of RNA per spermatozoa. However cDNA libraries were not built, probably due a high RNA degradation. The cumulus oocyte complexes (COCs) were classified as grade 1, aspirated from antral follicles with 3-8 mm in diameter, ovariesfromslaughterhouse were used and matured for 18 hours in an incubator at 38.5°C, 100% humidity and atmosphere of 5% of CO2 in air. The matured oocytes are going to be placed in contact with the prepared spermatozoa for fertilization and incubated for 20 hours in 5% CO2 at a temperature of 38.5 °C. Presumptive zygotes are going to be washed three times in SOF (half synthetic oviduct fluid) without FBS and without glucose, cultivated and transferred to plates with four wells containing 500 ul of the same medium used for washing zygotes after fertilization. Embryonic development was evaluated 7-8 days after fertilization. The cleavage and blastocysts rates were ... / Mestre

Abstract Birth of offspring of a pre-determined sex using flow cytometrically sorted fresh spermatozoa was first achieved in rabbits by Johnson et al. (1989). Since then offspring have been produced using sex-sorted spermatozoa from several different species (reviewed by Johnson, 2000). Initially, efficiency of the sex-sorting technology was poor with only low numbers of spermatozoa sorted per hour. Thus, the offspring derived from flow cytometrically sorted spermatozoa were produced with the use of artificial reproductive technologies (ART) such as in vitro fertilisation (IVF) and culture (IVC), intracytoplasmic sperm injection (ICSI) and deep artificial insemination (AI) which facilitated low dose insemination of potentially compromised spermatozoa. More recently, the development of high-speed sorters (Johnson and Welch, 1999) has facilitated the production of offspring using conventional AI techniques with low dose inseminates (Seidel et al., 1999) and successful cryopreservation of sorted spermatozoa (Schenk et al., 1999; Johnson et al., 2000; Lindsey et al., 2002; Schenk and DeGrofft, 2003). Increased efficiency of sorting bull spermatozoa has evolved through significant instrumentation and biological developments which have enabled the commercialization of the sperm sexing technology in the dairy industry, although conception rates in cows after low dose AI with sexed frozen-thawed spermatozoa are still lower than after standard frozen semen AI (Seidel et al., 1999). Subsequently, over 20 000 calves of pre-determined sex have been produced from commercially available sex-sorted frozen-thawed bull spermatozoa (Seidel, 2003). However, similar developments have not been made in the sheep industry and were examined in this thesis. In this study, successful cryopreservation of sex-sorted ram spermatozoa and production of offspring of the pre-determined sex (X: 94.4 %; Y: 100 %) was achieved after low dose (2-4 x 106 total) insemination using conventional laparoscopic intrauterine (IU) AI. However, the overall pregnancy rate for ewes inseminated with sex-sorted frozen-thawed spermatozoa was low (25 %) compared to ewes inseminated with a commercial dose (140 x 106 total) of non-sorted frozen-thawed spermatozoa (54 %). Cryopreservation has been found to not only reduce the proportion of motile spermatozoa, but cause the remaining spermatozoa to undergo changes that advance membrane maturation thereby shortening their lifespan, especially after in vivo fertilisation (Gillan and Maxwell, 1999). It was found that sorting prior to cryopreservation accelerated the maturation of sperm membranes and after co-incubation with oviducal cells in vitro, sorted frozen-thawed spermatozoa were released more rapidly than non-sorted (control) frozen-thawed spermatozoa. The potentially reduced lifespan of sorted frozen-thawed spermatozoa, and practical constraints on the number of spermatozoa that can be sorted for an insemination dose, makes insemination close to the site of fertilisation and time of ovulation critical for successful fertilisation. After treatment of ewes with GnRH to increase the precision of insemination in respect to the time of ovulation, there was no difference in pregnancy rate between ewes inseminated before, during or after the assumed time of ovulation. Furthermore, there was no difference in pregnancy rate after IU AI with similar doses of sorted frozen-thawed and non-sorted frozen-thawed spermatozoa in GnRH-treated ewes. The minimum dose of sorted frozen-thawed spermatozoa required for commercially acceptable pregnancy rates determined after IU AI was high (20 x 106 motile). Consequently, alternative methods for efficiently producing large numbers of offspring of a pre-determined sex using flow cytometrically sorted ram spermatozoa were investigated. Ram spermatozoa can be stored for short periods of time in a chilled state (liquid storage) or for an indefinite period of time in a frozen state (frozen storage; Salamon and Maxwell, 2000). The fixed location of the sperm sorter requires the need for transport of semen from the point of collection to the site of sorting and processing, but also from the sperm sorter site to the recipient females under artificial conditions. In this study, ram spermatozoa liquid stored for 24 h prior to sorting were efficiently sorted, frozen, thawed and after in vitro fertilisation and culture produced a high proportion of grade 1 blastocysts. Similarly, spermatozoa stored at reduced temperatures after sorting maintained high sperm quality for up to 6 days. Furthermore, frozen-thawed spermatozoa from rams and some non-human primates were successfully prepared for sorting and efficiently sorted producing spermatozoa with high quality in vitro parameters. The quality of frozen-thawed ram spermatozoa after sorting was such that successful re-cryopreservation after sorting was possible. Low numbers of frozen-thawed sorted and re-frozen and thawed spermatozoa were optimal for IVF and a high proportion of grade 1 in vitro embryos of a pre-determined sex were produced. These embryos were either transferred immediately or vitrified prior to transfer, extending the application of the sperm sexing technology further. The birth of lambs of pre-determined sex after transfer of both fresh and vitrified embryos derived from frozen-thawed sorted spermatozoa was achieved. The findings in this thesis suggest that sorted frozen-thawed ram spermatozoa may have more advanced membrane maturation state than non-sorted frozen-thawed spermatozoa, resulting in a decreased fertilizing lifespan in the female reproductive tract. Despite this, the use of sexed ram spermatozoa in a number of physiological states (fresh, liquid, frozen) with several different ARTs is possible in producing significant numbers of offspring of a pre-determined sex. Improved efficiency in both sperm sexing and associated reproductive technologies is required for commercialization to be achieved in the sheep industry.

published_or_final_version / abstract / toc / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

Production of all-male tilapia for aquaculture is assuming an increasingly important role. An important pre-requisite to repeated obtainment of monosex tilapia is a clear understanding of the mechanisms underlying sex differentiation. Histological observations on gonadal morphorgonesis and sex differentiation provided basic data for hormonal sex manipulation in four commercially important species. Results indicate that gonadal morphogenesis starts at different times ranging from eight days after hatching in 0. mossambicus to 17 days in 0. niloticus. Sex differentiation followed a similar pattern, and ranged from 22 days in O. mossambicus to 36 days in 0. niloticus. The effects of subjecting fish to different rearing temperatures was assessed. No significant influence was found on sex ratio of treated fish. Observations on offspring sex ratio in intraspecific breeding and interspecific hybridization demonstrated that significant differences between batches are a common occurrance and their regularity cannot be adequately explained on the basis of sex chromosome theory alone. Treating fish with synthetic androgen (17 alpha methyltestosterone) and synthetic oestrogen, (17 alpha ethenylestradiol) resulted in species specific and dosage dependant differences in sex ratios. Results also revealed significant differences in sex ratios of different batches of fish subjected to the same treatment, thus demonstrating that success rate in sex inversion varies not only between species and between stocks, but in sib groups as well. Results of intraspecific and interspecific breeding suggest that sex determination in tilapia is under the influence of multiple factors. Results of hormone treatments indicate variations in inversion rate at batch level, thus demonstrating presence of individual differences in lability. On the basis of results from these four experiments, it is hypothesized that sex in tilapia is influenced by multiple genes and the fishes' propencity to change sex varies in individual fish. Progeny testing oestrogen sex inversed fish indicates that on the basis of the chromosome theory of sex determination, S. galileaus and O. niloticus are female homogametic, while O, macrochir is female heterogametic. The implications of the results obtained in this study for production of all-male tilapia are briefly discussed.