Cooperative Research Centre

About: Cooperative Research Centre is a based out in . It is known for research contribution in the topics: Population & Sea ice. The organization has 7633 authors who have published 8607 publications receiving 429721 citations.

KIT/KIT Ligand in Mammalian Oogenesis and Folliculogenesis: Roles in Rabbit and Murine Ovarian Follicle Activation and Oocyte Growth

Abstract: In rodent ovaries Kit ligand (KITL) and its receptor KIT have diverse roles, including the promotion of primordial follicle activation, oocyte growth, and follicle survival. Studies were undertaken to determine whether KITL and KIT carry out similar activities in rabbits. KitlandKitmRNA and protein were localized to oocytes and granulosa cells, respectively, in the rabbit ovary. Ovarian cortical explants from juvenile rabbits and neonatal mouse ovaries were subsequently cultured with recombinant mouse KITL and/or KITL neutralizing antibody. Indices of follicle growth initiation were compared with controls and between treatment groups for each species. Recombinant mouse KITL had no stimulatory effect on primordial follicle recruitment in cultured rabbit ovarian explants. However, the mean diameter of oocytes from primordial, early primary, primary, and growing primary follicles increased significantly in recombinant mouse KITL-treated explants compared with untreated tissues. In contrast, recombinant mouse KITL promoted both primordial follicle activation and an increase in the diameter of oocytes from primordial and early primary follicles in the mouse, and these effects were inhibited by coculture with KITL-neutralizing antibody. Recombinant mouse KITL had no effect on follicle survival for either species. These data demonstrate that KITL promotes the growth of rabbit and mouse oocytes and stimulates primordial follicle activation in the mouse but not in the rabbit. We propose that the physiologic roles of KITL and KIT may differ between species, and this has important implications for the design of in vitro culture systems for folliculogenesis in mammals, including the human.

Growth and mortality in high and low light: trends among 15 shade-tolerant tropical rain forest tree species

Abstract: Summary 1Past work on tropical rain forest tree seedlings has been dominated by contrasts between strongly light-demanding and strongly shade-tolerant species. We examined patterns of growth and mortality among shade-tolerant tree seedlings in response to light, and investigated the morphological and physiological correlates of high seedling growth and survival rates across species. 2Seedlings of 15 tree species from Australian tropical lowland forest were grown for up to 1 year in neutral-density shadehouses at three light levels (10%, 0.8% and 0.2% full daylight). All species showed negligible mortality in the 10% and 0.8% shadehouses, but survival was significantly reduced in 0.2% daylight. 3Seedling survival rate in 0.2% daylight showed no significant relationship with either the dry mass of seed reserves (embryo plus endosperm), or relative growth rates in dry mass (RGRM) in 0.8% and 10% light. 4The RGRM values in 0.8% and 10% daylight were strongly positively correlated, and showed a strong negative correlation with the dry mass of seed reserves. Interspecific variation in low-light RGRM was driven by unit leaf rate (rate of accumulation of dry mass per unit area of leaf), whereas interspecific variation in high-light RGRM was most closely correlated with leaf area ratio (leaf area per total plant dry mass). 5Variation in seedling characters in response to light may have important implications for the coexistence of shade-tolerant tropical tree species.

Evaluating different bases for market segmentation: a comparison of geographic origin versus activity participation for generating tourist market segments

Abstract: While market segmentation has become a major approach to understanding the nature of tourists and their travel behaviour, there exists considerable debate over which bases and statistical approaches provide the best segmentation solutions. Morrison (1996) has offered eight criteria for evaluating the success or value of a segmentation result. This paper used these eight criteria to evaluate two different segmentation approaches used with the same survey sample. An a priori geographic segmentation of visitors to the Wet Tropics region of Australia was compared to an activity based a posteriori segmentation approach. There was evidence that the activity segmentation approach fulfilled the eight criteria more adequately than the geographic approach. It was further suggested that for large samples a multi-stage methodology might be a desirable approach for meeting all eight marketing segmentation effectiveness criteria.

Historical rainforest contractions, localized extinctions and patterns of vertebrate endemism in the rainforests of Australia's wet tropics

Abstract: The spatial patterns in the distributions of vertebrates in the rainforests of the wet tropics biogeographic region of north-eastern Australia were examined to form hypotheses on the processes that have shaped vertebrate assemblages and patterns of species richness and regional endemism. These rainforests occur in a relatively narrow and discontinuous strip along the coast of north-eastern Australia. We found that the number of regionally endemic species and the proportion of regional endemics present in each subregion are both strongly related to the geographic shape of subregional patches of rainforest, independent of rainforest area, within Australian tropical rainforests. Shape has a more significant influence on regional endemism than area, and area has a stronger influence on species richness. These patterns were congruent for all terrestrial vertebrate classes manuals, birds, reptiles and frogst, and for the four groups combined. Our results suggest that the combination of current rainforest area and shape are an index of the relative susceptibility of each area of rainforest to historical contractions, with the implication that historical habitat fluctuations, coupled with subsequent localized extinctions species sifting; have been extremely important processes in determining current patterns of endemism in Australia's wet tropical rainforests. This hypothesis is supported by the highly nested structure of the subregional distribution patterns.