<p> Serotonin positive (5HT+) and tyrosine hydroxylase positive (TH+) cells were identified using fluorescent immunocytochemical methods and quantified in the gill epithelium of six species of fish. 5HT+ cells were located in the filament epithelium in contact with the basal lamina on the efferent side, and in the lamellar epithelium where they were occasionally exposed to the external milieu. Thus, these cells appear to represent two populations of neuroepithelial cells (NEC) as proposed in other studies. In trout, bass and killi fish, NECs were revealed exclusively in the primary epithelium. In tilapia, NECs were located exclusively in the secondary epithelium, whereas in perch and zebrafish they occurred in both epithelial layers. The two types of NECs varied in number both within and among the species. Seasonal comparisons of NECs in perch revealed a decrease in cell density in the filament between July and November, though there was no significant difference in the density of NECs in the lamellae. TH+ cells were identified in perch, zebrafish and killi fish. In zebrafish TH+ cells occurred in similar numbers to 5HT+ cells, and were generally present in similar locations. It is likely that in this case, many of the labelled cells were positive for both markers. In two of the species, perch and killi fish, the density and distribution was such that the TH+ cells and 5HT+ cells were unlikely to be the same. A quantitative comparison of total catecholamine (CA) stores, using high performance liquid chromatography (HPLC), revealed that gill tissues in general contained higher levels of epinephrine (EPI) than norepinephrine (NOR) and dopamine (DOP). Finally, attempts were made to determine whether NECs would survive in 2-4 day old cultures of dispersed gill cells from perch, using immunocytochemical labelling for 5HT. A few successful cases are presented.</p> / Thesis / Master of Science (MSc)

Seasonal dynamics of unicellular diazotrophs were investigated in the upstream Kuroshio and the northern South China Sea (SCS). Unicellular diazotrophs had been postulated as an important N2-fixing contributor for the phenomenon of N* in the SCS where abundances of filamentous Trichodesmium and Richelia were scarced. Samples were collected during four cruises between August 2008 and August 2009 in summer (CR1310 and CR910), winter (CR886), and late spring (CR899), respectively. Sampling stations located between 21¢XN-22¢XN and 116¢XE-122¢XE in the upstream Kuroshio off southeast Taiwan and covering the shelf and basin waters of the northern SCS. The abundance of the unicellular diazotrophs was determined using whole-cell immunocytochemical method in which antibody of nitrogenase was used as the probe. Cells containing nitrogenase can be visualized and counted after the antigen-antibody reaction under microscope. Unicellular diazotrophs were classified to four types according to their sizes and shapes. For diameters of those with 1-3 £gm and in coccoid shape are called 1-3 £gm C, diameters of 1-3 £gm and in rod shape are called 1-3 £gm R, diameters of >3-10 £gm and in coccoid shape are called >3 £gm C, and diameters of >3-10 £gm and in rod shape are called >3 £gm R. Surface abundance of the unicellular diazotrophs was highest in winter in both the Kuroshio and the SCS, followed by summer, and was least in late spring. Among four cell types, 1-3 £gm C usually was the most abundant group, followed by 1-3 £gm R and >3 £gm R, and was least for the group of >3 £gm C. The abundances between groups of 1-3 £gm C and 1-3 £gm R were positively correlated. Likewise, the abundances between >3 £gm C and >3 £gm R were positively correlated. However, the total abundance of small cells (1-3 £gm C+R) was not significantly related to the large cells (>3 £gm C+R). During summer and late spring, the abundance of unicellular diazotrophs in the SCS was 1.3-2 times of that in the Kuroshio. However, in winter the abundance in the Kuroshio was 1.2 times of that in the SCS. Surface water temperature was found negatively correlated to the abundance of 1-3 £gm C, >3 £gm C, >3 £gm R, and large cells (>3 £gm C+R), respectively. Significant correlations among surface water temperature and surface chlorophyll a, [NO2+NO3], SRP and N:P ratio implicated that the dynamics of cell abundances could be attributed to the correlated ecological variables of surface water temperature. The dynamics for the abundances of >3 £gm C, >3 £gm R, and large cells (>3 £gm C+R) were suggested to relate with the fluctuation of SRP concentration. Unicellular diazotrophs accounted for 60-90 % of total unicellular cells in terms of cell number. Vertical distributions of unicellular diazotrophs in the Kuroshio and the SCS were in similar trends, with maximum abundance in deep water during summer and late spring, and on surface water during winter.

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Thesis (Ph. D.)--Miami University, Dept. of Botany, 2008. / Title from second page of PDF document. Includes bibliographical references.