Doctoral Degrees (Medical Physiology)

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Browsing Doctoral Degrees (Medical Physiology) by Subject "Animal models in research"

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    The dietary ionic effects on sex ratios in animal models
    (Stellenbosch : Stellenbosch University, 2016-03) Linge, Augustine Peter Kavoo; Du Plessis, S. S.; Kimwele, C.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Medical Physiology.
    ENGLISH ABSTRACT: X-linked disorders are more expressed in male offspring and prevention of these hereditary diseases is the only recourse to date. Influencing conception towards female offspring can circumvent this problem; however sex ratio adjustment remains highly contentious. Treatment of genetic disorders through sex ratio adjustments has been examined and adopted as acceptable, easier, cheaper, safer and legal. Historically, society has been rife with allegations that diet does influence sex ratios though this has not been proven fully. The dietary chemical compositions have been claimed to act as modulators that affect the electrical charges or potential of the membranes of the oocytes and cause allosteric modification or electrotactism through a process referred to as galvanotropism and cause selective attraction towards either of the male gametes and subsequently influence the gender of the conceptus. This study was performed in an attempt to address the various questions, allegations and speculations that have been rife in many societies concerning interplay between diet, fertilization and sex ratios so as to verify the validity of these social claims by taking them to the laboratory for experimental verification. Swiss Webster mice study In a double-blind fashion, nine double groups were set up comprising of 144 families of Swiss (Webster) mice, each receiving different ionic formulations in their drinking water: 1) water and 2) glucose as controls; high serum concentrations of single elements of 3) sodium, 4) potassium, 5) calcium and 6) magnesium; combined double elements 7) sodium + potassium and 8) calcium + magnesium; and finally a cocktail of the four elements 9) sodium + potassium + calcium + magnesium. Tests included the perinatal mortality rate; the relationship between high chemical composition diet and serum levels; the effects of the study chemicals on weight gains of the study models; the effects of birth order on sex ratios and the effects of seasonal variations on sex ratios. There were 1528 deliveries with 13,040 (6,348 females and 6,692 males) pups at 8.5 pups on average per litter. a) Glucose, sodium, potassium and sodium + potassium supplementation influenced the sex ratios towards male progeny (p<0.001). Calcium (p<0.014), magnesium (p<0.008) and calcium + magnesium (p<0.001) supplementation influenced sex ratios towards the female progeny. The water (p>0.61) and cocktail solutions (p>0.0609) had no influence. b) The perinatal mortality rate was 32/1000 and was female biased among the magnesium (p<0.005) and combined calcium + magnesium (p<0.044) groups only. c) Normal serum levels were observed in the control groups (p>0.165), while significant elevated serum levels were observed among the experimental groups (p<0.0001). d) The total mean weight gains were 11.12g and 10.55g among the females and males respectively. The weight trends were used to track the general wellbeing of the animal models. e) The mean litter size was 8.5 per delivery in all the groups and generations, while no influence due to birth order were detected. f) Seasons affect the litter size, in particular the rainy season, but not the gender ratios (p>0.061). Cat fish study Parallel double blind studies looking at the dietary chemical ionic effects on the oocyte membrane electrical potential were done utilising a cat fish model (n=108). The study sought to find out effects of the following solutions on the oocyte electrical charges: 1) plain electrolyte solution, 2) glucose solution 3) sodium solution 4) potassium solution 5) calcium solution 6) magnesium solution 7) sodium + potassium solution 8) calcium + magnesium solution and the 9) cocktail solution of the four elements combined. The results revealed that oocytes retrieved from the two control groups had baseline oval polar attraction significantly more towards the positive than the negative pole (p<0.0003). There was however more significant oocyte polar attraction towards the positive electrode among the oocytes retrieved from the sodium, potassium and the combined sodium + potassium solutions (p<0.0001). Oocytes retrieved from calcium, magnesium and combined calcium + magnesium solutions had significant affinity towards the negative electrode and minimal affinity towards the positive pole (p<0.0001). Oocytes harvested from the solutions constituted with all the salts demonstrated dual attraction with more attraction to the positive electrode than the negative electrode but of no statistical significance (p>0.0530). These study findings do confirm the social allegations that a positive relationship does exist between dietary components and sex ratios. The chemicals acted as the dietary modulators that ultimately influenced the electrical cellular gametal charges and subsequently the resulting progeny. Our platform of comfort is unlike artificial sex ratio adjustment methods; the natural sex ratio adjustment methods that include the dietary method under scrutiny in this study are practiced always at the comfort of many people’s homes and are difficult to quantify or have legislation on. However, this study shows that their long term effects conform to the Fishers principle of evolution towards 1:1 sex ratios and therefore do not have significant social gender skewing on a long term basis. The study clearly explains the molecular basis upon which ions of single valency attracts the Y-bearing sperm leading to a male conceptus and how cations of double valency attracts the X-bearing sperm leading to a female conceptus despite being positively charged. The study further reaffirms the natural feminine supremacy by demonstrating that it is the ova and by extension the woman who determines the sex of the conceptus. The study ultimately confirms that the dietary ionic effects on sex ratios can be used for prevention of X-linked disorders.