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Selected AbstractsMovements of Murray cod (Maccullochella peelii peelii) in a large Australian lowland riverECOLOGY OF FRESHWATER FISH, Issue 4 2009J. D. Koehn Abstract,,, This study of Murray cod (Maccullochella peelii peelii) movements in a large lowland river in south-eastern Australia indicated that the species was not sedentary, but undertook complex movements that followed a seasonal pattern. While there were sedentary periods with limited home ranges and high site fidelity, Murray cod also under took larger movements for considerable portions of the year coinciding with its spawning schedule. This generally comprised movements (up to 130 km) from a home location in late winter and early spring to a new upstream position, followed by a rapid downstream migration typically back to the same river reach. Timing of movements was not synchronous amongst individuals and variation in the scale of movements was observed between individuals, fish size, original location and years. [source] Effect of spatial inhibition on saccade trajectory depends on location-based mechanismsJAPANESE PSYCHOLOGICAL RESEARCH, Issue 1 2009HIROYUKI SOGO Abstract:, Saccade trajectory often curves away from a previously attended, inhibited location. A recent study of curved saccades showed that an inhibitory effect prevents ineffective reexamination during serial visual search. The time course of this effect differs from that of a similar inhibitory effect, known as inhibition of return (IOR). In the present study, we examined whether this saccade-related inhibitory effect can operate in an object-based manner (similar to IOR). Using a spatial cueing paradigm, we demonstrated that if a cue is presented on a placeholder that is then shifted from its original location, the saccade trajectory curves away from the original (cued) location (Experiment 1), yet the IOR effect is observed on the cued placeholder (Experiment 2). The inhibitory mechanism that causes curved saccades appears to operate in a location-based manner, whereas the mechanism underlying IOR appears to operate in an object-based manner. We propose that these inhibitory mechanisms work in a complementary fashion to guide eye movements efficiently under conditions of a dynamic visual environment. [source] LIPID COMPOSITION OF CHLORARACHNIOPHYTES (CHLORARACHNIOPHYCEAE) FROM THE GENERA BIGELOWIELLA, GYMNOCHLORA, AND LOTHARELLA,JOURNAL OF PHYCOLOGY, Issue 2 2005Jeffrey D. Leblond The Chlorarachniophyceae are unicellular eukaryotic algae characterized by an amoeboid morphology that may be the result of secondary endosymbiosis of a green alga by a nonphotosynthetic amoeba or amoeboflagellate. Whereas much is known about the phylogeny of chlorarachniophytes, little is known about their physiology, particularly that of their lipids. In an initial effort to characterize the lipids of this algal class, four organisms from three genera were examined for their fatty acid and sterol composition. Fatty acids from lipid fractions containing chloroplast-associated glycolipids, storage triglycerides, and cytoplasmic membrane-associated polar lipids were characterized. Glycolipid-associated fatty acids were of limited composition, principally eicosapentaenoic acid [20:5(n-3)] and hexadecanoic acid (16:0). Triglyceride-associated fatty acids, although minor, were found to be similar in composition. The polar lipid fraction was dominated by lipids that did not contain phosphorus and had a more variable fatty acid composition with 16:0 and docosapentaenoic acid [22:5(n-3)] dominant along with a number of minor C18 and C20 fatty acids. Crinosterol and one of the epimeric pair poriferasterol/stigmasterol were the sole sterols. Several genes required for synthesis of these sterols were computationally identified in Bigelowiella natans Moestrup. One sterol biosynthesis gene showed the greatest similarity to SMT1 of the green alga, Chlamydomonas reinhardtii. However, homologues to other species, mostly green plant species, were also found. Further, the method used for identification suggested that the sequences were transferred to a genetic compartment other than the likely original location, the nucleomorph nucleus. [source] Genetic diversity of Forest and Savannah chicken populations of Ghana as estimated by microsatellite markersANIMAL SCIENCE JOURNAL, Issue 3 2010Richard OSEI-AMPONSAH ABSTRACT The characterization of indigenous animal genetic resources is a requisite step in providing needed information for the conservation of useful genotypes against future needs. Thus, in this study, 22 microsatellite markers were used to genotype 114 local chickens from the Forest (n = 59) and Savannah (n = 55) eco-zones of Ghana and the results compared to those of the ancestral red junglefowl (n = 15) and two European commercial chicken populations , a broiler (n = 25) and white leghorn (n = 25). A total of 171 alleles were observed, with an average of 7.8 alleles per locus. The local Ghanaian chickens showed higher diversity in terms of the observed number of alleles per locus (6.6) and observed heterozygosity (0.568) compared with the combined control populations (6.0 and 0.458, respectively). However, Wright's F -statistics revealed negligible genetic differentiation (FST) in local Ghanaian chicken populations. In addition, 65% of the Savannah chickens were inferred to be more likely from the Forest, suggesting a south-north dispersal of chickens from their probable original location in the Forest zone to the Savannah areas. It is concluded that the Forest and Savannah chickens of Ghana are a single, randomly mating unselected population, characterized by high genetic diversity and constitute a valuable resource for conservation and improvement. [source] Involvement of E-cadherin, ,-catenin, Cdc42 and CXCR4 in the progression and prognosis of cutaneous melanomaBRITISH JOURNAL OF DERMATOLOGY, Issue 6 2007M.G. Tucci Summary Background, A key event in cancer metastasis is the migration of tumour cells from their original location to a secondary site. The development of melanoma may be viewed as a consequence of the disruption of homeostatic mechanisms in the skin of the original site. Objectives, To investigate whether dysregulation of cell motility (Cdc42 expression), escaping the control of cell,cell and cell,matrix interactions (E-cadherin, ,-catenin expression), enhances melanoma progression, and whether chemokine receptors (CXCR4) mediate cell migration and activation during invasion and metastasis development. Methods, The immunohistochemical expression of Cdc42, E-cadherin, ,-catenin and CXCR4 was investigated in 30 patients with surgically treated nodular melanoma, 18 alive and disease free and 12 with a fatal outcome due to metastatic disease. Results, E-cadherin expression was significantly reduced (P < 0·05) and cytoplasmic ,-catenin was increased in the patients who had died compared with disease-free individuals, while membrane expression of ,-catenin was similar in the two groups. Patients with fatal outcome had increased Cdc42 (P < 0·01) and CXCR4 (P < 0·05). In this group a positive correlation was found between melanocytic Cdc42 expression and Breslow thickness (r = 0·598, P < 0·05) and between CXCR4 expression and Breslow thickness (r = 0·583, P < 0·05). Conclusions, Findings suggest that primary cutaneous melanoma with a high Breslow thickness is characterized by tumour cells with high motility and invasion ability, in line with the hypothesis that low E-cadherin levels and overexpression of Cdc42 and CXCR4 could be prognostic markers of poor outcome. [source] Comparative positions of kinetoplasts in Trypanosoma musculi and Trypanosoma lewisi during development in vitroCELL PROLIFERATION, Issue 5 2002M. Ashraf The development of Trypanosoma musculi and Trypanosoma lewisi were studied in vitro in the presence of adherent splenic cells. Both parasites developed only when attached by their flagellar tips to adherent splenic cells. During the proliferation of T. musculi, the kinetoplast migrated towards the nucleus, and once in the vicinity of the nucleus, the nuclear division was triggered. The kinetoplast of T. lewisi did not migrate towards the nucleus, but remained at its original location. The nucleus and kinetoplast divided at the same time in both parasites, and parasites started dividing from their flagellar ends and T. musculi and T. lewisi daughter cells were formed within 48 h. The unavailability of the adherent splenic cells in vitro led the parasites to transform into round/oval nonviable forms. [source] | ||||||||||