Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Stunting is widespread among brook trout Salvelinus fontinalis populations in high alpine lakes in the eastern Sierra Nevada, California. Due to their small size and poor condition, stunted brook trout are undesirable as sport fish. In the same area, a few lakes contain large brook trout. Population density was the primary difference between lakes with different sized fish. I hypothesized that in lakes with large fish the food ration per individual was sufficient and that in lakes with stunted fish the food ration was the limiting factor. I carried out removal experiments on eight brook trout populations to test the hypothesis (1) that fish size is inversely related to population density, and by that evaluate density reduction as a means of improving growth in stunted brook trout. I considered seven additional hypotheses regarding the relationships between brook trout population density and growth, fecundity, and recruitment: (2) growth response is proportional to density reduction; (3) growth response is inversely proportional to pre-reduction density; (4) growth responses of juvenile and senescent fish are less affected by density reductions than mature, reproductively active fish; (5) growth response to density reduction is inversely proportional to lake elevation; (6) fish size is proportional to angling pressure; (7) fecundity response is proportional to the reduction in population density; and (8) recruitment response is inversely related to density. I used gillnets to simultaneously remove part of the population and estimate population size through catch depletion methods that allow variable catchability. Catchability varied with lake size and with abundance, increasing as population abundance declined. Increased catchability can be explained by behavioral responses. I measured and aged 16000+ brook trout from 71 lakes, 9800+ from the eight experimental lakes. I validated annual structures on otoliths using a fluorochrome mark. For the experimental lakes, I back-calculated previous population sizes using estimates of number at age in 1989, catch at age in 1987-1988, and survival rates at age estimated from catch data collected in 1987-1989. I converted population estimates into density estimates of fish and biomass per lake surface area and volume. I tested hypothesis 1 by using survey data from 61 populations and by experimentally manipulating density in eight populations. The survey data suggested that size differences between populations of brook trout are a function of population density. Results from the eight removal experiments showed that fish size was inversely related to population density, though the increases in fish size were minor. The relationship between change in length and weight was roughly proportional to the change in density (hypothesis 2). Hypothesis 3 suggested differences in the severity of stunting in alpine lakes, and that the growth response of severely stunted populations would be more pronounced than the response of less stunted fish in lower density populations. The result was opposite; the growth response in lower density populations was greater than the response in higher density populations, suggesting that the growth response may have been proportional to the pre-reduction density. Hypothesis 4 suggested that the growth response for juvenile brook trout would be less than that for the pre-senescent adult population. The results refuted the juvenile portion of hypothesis 4: response for juveniles was greater than the response of the adults, perhaps because of greater recuperative abilities in young fish. The data supported the hypothesis that the growth response would be diminished in older fish. There was no relationship between elevation and growth response (hypothesis 5). Sport fishing had little effect on the growth of brook trout populations (hypothesis 6). Heavily fished populations were also stunted. Stunted brook trout had fecundities similar to non-stunted brook trout of the same size (hypothesis 7). Individual fecundity did increase in response to density reduction, but no more than would be expected from the increase in size. In several populations mean absolute fecundity decreased with age. Ovary weight was maintained by an apparent increase in mean egg size in older fish. The recruitment response varied between lakes (hypothesis 8). Recruitment did increase, likely in response to reduced cannibalism or competition, but I also found recruitment failure at the highest levels of density reduction. Strong cohorts were produced by increased juvenile survival rather than increased population fecundity, since population fecundity had decreased due to removal of most of the adult population. In one lake with almost no recruitment, densities remained low and fish weight doubled. For density reduction to be an effective means of increasing fish size, recruitment must be inhibited. / Science, Faculty of / Zoology, Department of / Graduate

Senescence, the progressive loss of growth potential culminating in death, is common among Kauaian strains of Neurospora intermedia. Senescence is initiated by the insertion of kalilo DNA into the mitochondrial DNA. Mitochondrial DNA molecules carrying the insert accumulate and death occurs when the insert is equimolar with the mitochondrial DNA. The inserted form of kalilo DNA is referred to as mtlS-kalDNA. Studies on the somatic transmission of mtlS-kalDNA in ascospore series have revealed that kalilo DNA is capable of assuming new locations within the mitochondrial DNA. It is proposed that these novel insertions originate from intramitochondrial movement and an autonomous form of kalilo DNA, mtFF-kalDNA, is predicted to be an intermediate in movement. Novel insertion of kalilo DNA appears to depend on the form of mtlS-kalDNA transmitted sexually. If a mutagenic insert is transmitted, senescence is initiated at the onset of vegetative growth of the ascospores and no novel insertions are detected. The lifespans of these ascospores are quite short, death occurring in 10 subcultures or less. Transmission of a nonmutagenic insert delays the onset of senescence until either a novel insertion or a rearrangement of the transmitted insert occurs. The lifespans of these ascospores usually exceed 10 subcultures and are variable. Information obtained from tetrad analysis has revealed that novel insertion of kalilo DNA may also be under the influence of the host genome. A senescent Kauaian strain was identified which shows some but not all characteristics of kalilo senescence. In this strain and its derivatives, the behaviour of mtlS-kalDNA is erratic and in, some cultures the characteristic mitochondrial biochemical deficiencies, normally accompanying kalilo senescence, are not observed. It is suspected that kalDNA is not responsible for senescence in this strain and its derivatives but rather some other unknown factor is affecting the normal growth patterns of these cultures. Kauaian strains were surveyed for the presence of dsRNA to determine whether kalDNA has a viral origin. Only one senescent strain contains detectable amounts of dsRNA which was not homologous with a kalDNA probe. The survey identified six nonKauaian strains which contain dsRNA and seven dsRNA species were delineated. Although the presence of dsRNA is not relevant to kalilo senescence, analysis of dsRNA in a genetically-well defined organism like Neurospora may give insight into the significance of dsRNA in fungi in general. / Medicine, Faculty of / Medical Genetics, Department of / Graduate

This study was designed to examine the hypothesis that the amount of amniotic fluid present during gestation is critical to normal lung growth and maturation. On day 16 of gestation the amniotic sacs of the right or left uterine horns of timed pregnant Sprague-Dawley rats were punctured with a 20 gauge needle. The fetuses of the opposite horn served as controls. On day 21 of gestation (one day prior to natural delivery) the fetuses were delivered by Cesarean section. An unbalanced, mixed model analysis of variance was performed on the data collected from each fetus. Probability values of less than 0.05 between control and experimental animals were considered significant. Amniotic sac puncture resulted in a significant loss of amniotic fluid as indicated by reduced amniotic fluid volume on day 21. Experimental body weight was significantly reduced indicating fetal growth retardation. Lung growth was also retarded as indicated by significantly reduced lung weight to body weight ratios and lung volume to body weight ratios following amniotic sac puncture. There was a reduction in the amount of fluid present within the experimental lungs. There appeared to be no significant effect on the structural units of the lung as indicated by no significant difference between control and experimental fetal lungs in terms of cell number, cell size, total protein to body weight ratio, maturation of type II cells, volume fraction of saccular air, saccular wall, conducting air and nonparenchyma, airspace size, saccular surface area to body weight ratio and surface to volume ratio. Thus, loss of amniotic fluid significantly affected lung growth, more than it affected overall body growth, without having an effect on lung maturation. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Genetic and non-genetic effects of maternal; size were investigated in four introduced populations of Cinnabar moth Tyria jacobaeae (L.) (Arctiidae). Offspring of different female moths were reared to the pupal stage under greenhouse conditions with an overabundance of food. Mean offspring-maternal size correlations were highest for second generation laboratory offspring using pupal weight as the size criterion, maximum egg weight was not related to female size, although average egg weight tended to decrease, and fecundity increase with female wing length. Egg weight was not related to final pupal weight. Egg weight decreased over the oviposition period, but pupae reared from later batches were not consistently of lower weight when compared with pupae reared from batches laid on tie first day of oviposition. Under a less favorable temperature regime, hatching, success was reduced in later batches. It was concluded that maternal effects (genetic and non-genetic) on offspring size are unimportant under normal field conditions in comparison to the effects exerted by larval crowding and food availability. However under very poor conditions, selective mortality may be imposed on later batches, or on the lighter eggs of large moths. / Science, Faculty of / Zoology, Department of / Graduate

Rainbow trout (Salmo gairdneri) from two wild stocks native to British Columbia, and a non-native domestic strain were reared under varying conditions to examine effects of growth rate and body size, genetic stock, and photoperiod on the incidence and timing of testis development. The ratio of gonad weight to body weight (Gonadosomatic index) was found to be useful for separating mature and immature male fish and for determining the onset of gonadal development. In Premier lake fish testis development began one year before the expected date of spawning. At this time, signs of maturation were evident primarily among males that reached a body weight of between ten and twenty grams, whereas most of the fish smaller than this "critical" size remained immature (i.e. no testis developmment). Apparently, this critical size must be reached by a certain time of the year. Thus, a time 'window' exists wherein fish achieving a certain size begin preparation for spawning the following year. Altering photoperiod regime during the time window had no effect on the incidence of sexual precociousness, but did delay spermatogenesis by an undetermined length of time. / Science, Faculty of / Zoology, Department of / Graduate

A deterministic simulation model is used to explore the relationship between juvenile pink, chum and coho salmon growth and size-related survival in the Fraser River estuary. Parameters most sensitive to change are identified and the results related to proposals for enhancement. These results suggest that increasing the initial size of enhancement pink and chum fry, relative to the size of wild fry, prior to seaward migration and releasing them early in the spring may increase their chances of survival. If increasing total (enhancement plus wild) fry density decreases fry growth rate, the presence of enhancement fry in the estuary could reduce the survival chances of wild fry. The decrease in wild stock survival may not be apparent from estimates of adult return for many years due to errors in measurement and to the effect on survival of environmental variability. The model can be used to suggest and evaluate enhancement proposals. Areas needing further research are also indicated. / Science, Faculty of / Zoology, Department of / Graduate

The purpose of this study was to substantiate previous claims that differential growth across the frontonasal suture occurs and if this differential growth pattern is caused by an increased mitotic rate of the nasal bone. Two six week old New Zealand White Rabbits were given calcein 20mg/kg IA, demeclocycline 20mg/kg IA, and BrdU 40mg/kg IA on Days 1, 11, and 14, respectively. The animals were euthanized using Ketamine 31.6mg/kg IM and Pentobarbital 100mg/kg IV. The frontonasal suture was removed from the rabbit and divided into hemisections. The right hemisection was histologically processed using standard calcified methods which were modified and used for smaller bone sections at the Comparative Orthopaedic Research Laboratory, School of Veterinary Medicine, University of Wisconsin. The left hemisection was reserved for BrdU staining at the Central Microscopy Research Facility, University of Iowa. The resultant slides were imaged and photographed using an Olympus BX-40 microscope and measured using ImageJ software (NIH). Means and standard deviations were calculated for interlabel distance and mineral apposition rate (MAR). All frontonasal suture sites demonstrated double fluorochrome labeling. Samples F2-2 and M2-1 demonstrated the predicted differential growth pattern. Samples F2-1 and M2-2 did not. No suture sites demonstrated positive staining for BrdU. Although the sample size was small (n=2), this may demononstrate a trend toward differential growth of the suture. Due to the small sample size, the labeling protocol used in this study provided limited quantitative data. Although two sections did not demonstrate more bone deposition or faster mineral apposition rate of the nasal bone, it is important to consider that these sections were of poorer quality when compared to the other sections. Higher quality sections with clear, measurable margins showed a difference between frontal and nasal bone growth in both morphology and mineral apposition rate.

Indiana University-Purdue University Indianapolis (IUPUI) / Bisphosphonates, effective inhibitors of bone resorption, are used in the treatment of postmenopausal osteoporosis. At present, the effects of bisphosphonate therapy on the maxilla have not been quantitatively studied. As part of the masticatory system, dentate alveolar bone is exposed to a unique pattern of loading. As such, data obtained from bisphosphonate studies of other bones may not be applicable to the cortical bone of the dentate maxilla. The objective of this study is to histomorphometrically quantify the effects of alendronate and risedronate therapy on alveolar bone of the dog maxilla (MX) and to determine if this site is affected differently than the cortical bone in the rib (R) from these same animals. Twenty-two female dogs were divided into three treatment groups of 1 mg/kg/day alendronate, 0.5 mg/kg/day risedronate, and a saline vehicle control. Fluorochrome labels were used to mark sites of bone formation. Maxillary and rib specimens from each dog were prepared for analysis of static and dynamic histomorphometric parameters. MX cortical bone surrounding the third premolar was further analyzed by side (buccal vs. lingual) and region (coronal vs. apical). Mineralizing surface (MS/BS) and bone formation rate (BFR) in the coronal maxilla of the control group is significantly (p < 0.05) higher than that of the bisphosphonate groups. In bisphosphonate treated animals, MS/BS, BFR, and activation frequency (AcF) were significantly (p < 0.05) higher in the R than in the MX. In all treatment groups, very little osteoid was detected, and no significant difference in the mineral apposition rate (MAR) was noted. These results indicate that: (1) bisphosphonate dosages used in this study effectively inhibited remodeling within the dog maxilla; (2) alveolar bone remodeling was decreased more than remodeling in rib cortical bone; (3) within the dentate maxilla, alveolar bone remodeling was decreased more in the coronal than in the apical region, and (4) none of the groups appears to show inhibition of mineralization.

by Ling Lin. / "November 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 149-168). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.