Honors Projects for Botany

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    Pythium Species Isolated From Taro (Colocasia Esculenta) In Hawaii
    (University of Hawaii at Manoa, 2014-01-15) Yamamoto, Brian ; Botany
    Isolates of papillate, proliferous Pythium sp. resembling Pythium helicoides Drechs, and P. carolinianum Matthews were cultured from soft rot corms of taro (Colocasia esculenta (L.) Schott) from the major islands of Hawaii. Temperature maximum for growth (43˚C) of these isolates also was comparable to those for P. helicoides and P. carolinianum. Due to a lack of the sexual stage of these isolates in diseased material or in culture, the fungus was placed with the imperfect fungus, P. carolinianum.
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    Environmental and Nutritional Factors Influencing Growth and Fructification of Pistillaria Micans
    (University of Hawaii at Manoa, 2014-01-15) Fukuki, Kate ; Friend, Douglas ; Botany
    Growth for Pistillaria micans was greatest at 25˚C while maximum and minimum temperatures for vegetative growth were about 30°and 10° respective1y. Under slightly anaerobic conditions, the optimum temperature was somewhere between 15˚C and 20˚C. Changing the photoperiod (continuous dark or alternating light/dark) after 8 days did not produce changes in growth. Relative humidity had little or no effect on growth or reproduction. Pistillaria micans was unable to tolerate acidic conditions and growth was favored neutral to alkaline conditions (pH 7.1-7.5). Light was inhibitory to fruit body production and a minimum of 48 hours in continuous darkness was required tor basidiocarp development. Fruit body production was specifically inhibited in the blue region (395 nm). When the blue light region was omitted, (as in red light, in NUV light, and in dark treatments), fruit body production was stimulated in the-near-ultraviolet region (313 nm). Growth occurred when dextrose, fructose, sucrose, galactose, soluble starch, cellulose was the sole carbon source. The best growth occurred when sucrose was the sole carbon source while growth on galactose was significantly poor. No growth occurred when ammonium sulfate or potassium nitrate was the sole nitrogen source, while growth was slight on asparagine and glycine. Casein hydrolysate, urea and peptone were good nitrogen sources. Vegetative growth occurred on the following media: rabbit food agar (RF), corn meal+malt and yeast extract (CMMY), corn meal, oat agar, Hau leaves in agar, V-8, corn meal+yeast extract + dextrose (CMYD), potato dextrose agar (PDA), Blakeslee's malt extract (ME(Bl.)), and Czapek agar. Growth on Difco malt extract was poor. Fruiting was good on RF, CMYD, PDA and Hau leaves and to a lesser extent on ME (Bl.), and CM. Pistillaria micans on PDA produced a few aborted basidiocarps while on ME (Bl.), they were more abundant. P. micans on Czapek agar produced synnemata instead of basidiocarps. Growth was stimulated when thiamine was added to the culture media. The combination of thiamine with biotin, pyridoxine or inositol increased vegetative growth.
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    Genetic Variation in Mycosphaerella Musicola Leach (Cercospora Musae Zimm.)
    (University of Hawaii at Manoa, 2014-01-15) Ferreira, Stephen ; Botany
    Although Cercospora leaf spot (Sigatoka disease) of bananas has been known for nearly half a century, little is known of the genetics and variability of the pathogen, Mycosphaerella musicola Leach (Cercospora musae Zimm.). Most of our present knowledge concerning the organism has been derived from field observations and inoculation studies. Simmonds (10) believed that flask-shaped bodies of closely interwoven layers of hyphae surrounding a central mass of loose, hyphal cells in field-collected Sigatoka lesions were immature spermagonia or ascocarps. A direct relationship between the Cercospora musae (imperfect) stage and spermagonia was found by Stahel (11). Leach (7) later found numerous mature ascocarps always associated with numerous spermagonia and few conidial fructifications in field-collected Sigatoka lesions. However, lesions which had numerous conidial fructifications had few spermagonia and perithecia.
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    Non-Stomatal Depression of Photosynthesis Caused by Water Stress on Scaevola Taccada Plants
    (University of Hawaii at Manoa, 2014-01-15) DeVirgilio, Mark ; Botany
    Plants of Scaevola taccada were grown in hydroponic solutions at different water potentials obtained by addition of either polyethylene glycol 1500 or sea water. The photosynthetic rates of detached leaves produced under treatment were obtained at high (525 u moles/m2 sec) and low (47.5 u moles/m2 sec) radiant flux densities. Photorespiration was reduced by the use of N2 gas and CO2 concentration of 400 ppm. A significant depression of photosynthesis was caused by the water stressing solutions under both the high and low intensity conditions. The depression under low light conditions varied linearly with respect to the osmotic potential of the hydroponic solution in the range of -2.0 to 0 M pascals and irrespectively of whether PEG or sea water was used to stress the plant.
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    Autoradiographic Analysis of the Relaxin Receptor in Human Fetal Membranes
    (University of Hawaii at Manoa, 2014-01-15) Cachola, Leinani ; Botany
    Relaxin is a polypeptide hormone best known for its role in pregnancy and parturition, it is synthesized as a single chain polypeptide precursor composed of a B chain, C peptide, and A chain. The C peptide is proteolytically cleaved from this precursor during processing to form the mature molecule. Presently two genes that code for human relaxin have been identified, and they are termed H1 and H2. The nucleotide sequence of the first human relaxin gene was obtained by using a porcine relaxin cDNA probe to screen a human genomic library and was called H1 (1). However, early studies failed to show relaxin H1 gene expression in tissues known to be sources of relaxin. These results suggested the presence of another human relaxin gene. Using a probe derived from the relaxin H1 to screen a cDNA library made from RNA isolated from the human corpus luteum of pregnancy, a second human relaxin gene was identified termed H2 (2). Subsequently, both genes were mapped on chromosome 9 (3).