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  • 1
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    FISON | Lagos, Nigeria
    In:  http://aquaticcommons.org/id/eprint/23226 | 19325 | 2018-03-18 14:51:17 | 23226 | Fisheries Society of Nigeria
    Publication Date: 2021-07-13
    Description: The proximate composition and amino acids assay of smoked Clarias gariepinus and Oreochromis niloticus were determined using standard procedures. The mean proximate composition of Oreochromis niloticus are 8.9% moisture, 16.00% lipids, 5.6% ash, 44.5% crude protein, 0.42% crude fiber and 24.9% NFE while Clarias gariepinus has 8.19% moisture, 15.55% lipids, 4.725 ash, 40.46% crude protein, 0.50% crude fiber and 30.58% NFE. There is therefore a nutrient variation between the 2 species of fish Oreochromis niloticus has higher crude protein, lipids, moisture and ash content than Clarias gariepinus.The amino acids profile shows that both fishes have 17 amino acids. Apart from Tryptophan, the following essential amino acids Histidine, Methionine, Threonine, Isoleucine, Leucine, Lysine, Valine and Phenylalanine are present in both fish. Oreochromis niloticus however has higher quantities of the essential amino acids except for Histidine than Clarias gariepinus
    Description: Includes:- 2 tables.;2 figs.;7 refs.
    Keywords: Chemistry ; Fisheries ; Clarias gariepinus ; Oreochromis niloticus ; Nigeria ; Kainji L. ; freshwater environment ; Amino acids ; Ash content ; Lipids ; Organic compounds ; Moisture ; Proteins
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  • 2
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    FISON | Akure (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23338 | 19325 | 2018-04-07 17:17:18 | 23338 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: The evaluation of Cr. Cu, Mn, Fe, Ni, Zn,As and Pb concentrations in Clarias gariepinus and Oreochromis niloticus from Lake Geriyo Yola,Adamawa, Nigeria using X - ray fluorescence (XRF) technique is discussed. The analytical samples are irradiated with high energy electrons of 109Cd to produce fluorescent X-rays was produced which passes to the Silicon-lithium detector through Mo target as a source of monochromatic X-rays. The spectrum of energy generated on the detector was processed by a Multi- Channel Analyzer to obtain analytical data. The intensity of the fluorescent X-rays on the detector is proportional to the concentration of the individual element of interest in the sample. This method can identify up to 30 or more elements at the same time. The results showed varying levels of heavy metals in the fishes. The concentrations of Cr, Mn, Cu, and Ni in the fishes were much higher than WHO and PEPA maximum permissible limits, while the concentrations of Zn and Pb were lower than the standards. The results suggest that the lake is polluted with Cr, Mn, Cu and Ni and the consumption of fishes of the lake is life threatening to man.
    Description: Includes:- 1table.;11 refs.
    Keywords: Ecology ; Chemistry ; Pollution ; Clarias gariepinus ; Oreochromis niloticus ; Nigeria ; Geriyo L. ; freshwater environment ; Heavy metals ; Fish ; X-ray fluorescence analysis ; Pollution ; Pollution effects
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    Format: 69-71
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  • 3
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23422 | 19325 | 2018-04-25 19:24:46 | 23422 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: Tilapia guineensis eggs were spawned and hatched in different salinities (17, 12, 7, 5, 2 and 0) ppt. The study was conducted in eight replicates. The aim of the investigation was to ascertain disparity in hatching size of Tilapia guineensis attributable to salinity. Immediately hatching was observed, body weight of five hatchlings in each replicate was individually weighed in milligramme. The individual total length of the five hatchlings was also measured in millimeter. The height of the yolk sac larva was determined with micro-metre screw gauge graduated in millimeter from the top of the yolk sac to the dorsal region of the larva. Data obtained were used to calculate yolk sac volume. Significant differences (P〈0.01) were observed in body weight and total length of larvae hatched in different salinities. The heaviest and longest larvae were hatched in 12 ppt saline water. The yolk sac volume of larvae hatched in lower salinities were significantly higher (P〈0.01) than the yolk sac volume of larvae hatched in higher salinities. The smallest yolk sac volume was recorded in 12ppt saline water. Our findings show that salinity could be manipulated for economic production of heavier seeds of Tilapia.
    Description: Includes:- 5 tables.;6 refs.
    Keywords: Aquaculture ; Chemistry ; Tilapia guineensis ; Nigeria ; brackishwater environment ; Salinity effects ; Larvae
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  • 4
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24590 | 19325 | 2018-05-20 16:05:58 | 24590 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: The water analysis of five selected ponds in Ado-Ekiti in Ekiti State, was carried out to determine their suitability for fish culture. Pa rameters analyzed were: Temperature, Turbidity, Carbon (IV) oxide, Alkalinity, Hardness, pH and Dissolved oxygen. Values for temperature ranged between 20.0~'C and 29.0~'C, Turbidity values were between 46.0-50.2cm, Carbon (IV) oxide: 11.5-12.2mg/litre; alkalinity: 100-120mg/liter; hardness: 110-200mg/litre; pH: 6.8-7.8 and dissolved oxygen: 5.8-6.8mg/liter. The values obtained were found to be within acceptable range for fish production.
    Description: Includes: 10 references.
    Keywords: Aquaculture ; Chemistry ; Nigeria ; Physico-chemical parameter ; Fish pond ; Ado-Ekiti ; Fish production ; freshwater environment ; automation
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  • 5
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    FISON | Minna (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24067 | 19325 | 2018-05-10 10:15:21 | 24067 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: This study focused on the assessment of Terminalia suparba (bark, leave and root) based diet to improve the ovulation of Clarias gariepinus brood stocks. Ten female and ten male brood stocks were obtained from a reputable fishfarm in Ogun State, Nigeria and were fed with the diets for four weeks before the breeding exercise. The latency period observed in treatments 1 to 4 was 4hours 30minutes while the ovulation period in treatment 5 was 8 hours. There was no significant different (P〉0.05) among the means. The brood stocks in Treatment 2 (Root) has the highest fecundity count (2001) while those in Treatment 5 (control) has the least fecundity count (1496). The phytochemical analysis of the plant materials showed the presence of Alkaloids, Tannin, Phenol, Glycoside, Flavonoids, Steroids, Phlobatannin, Saponin, Anthraquinones. The physical and chemical parameters of water observed showed that dissolved oxygen value ranges from 3.28 -4.60, pH 6.5 - 8.5, temperature 28.0 - 28.8 and conductivity 8.9 - 9.20. It is therefore concluded that the inclusion of Terminalia suparba in the feed of Clarias gariepinus broodstock will not only improve ovulation but also reduce the latency period.
    Description: Includes: 5 tables;Also includes: 11 refs.
    Keywords: Aquaculture ; Chemistry ; Ecology ; Clarias gariepinus ; Nigeria ; broodstocks ; Terminalia specie ; Latency ; fecundity ; Clarias gariepinus ; freshwater environment ; Artificial feeding ; Feeding experiments ; Fecundity ; Brood stocks ; Sublimation heat ; Ovulation ; Physicochemical properties ; Fish culture
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  • 6
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24618 | 19325 | 2018-05-22 06:12:36 | 24618 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: One of the priority research projects of the Nigerian Institute for Oceanography and Marine Research (NIOMR) is broodstock development and mass propagation of silver catfish, Chrysichthys nigrodigitatus of which the broodstock is naturally abundant in New Gala River. Selected physical characteristics and water physico-chemical parameters of the upper reach of the New Calabar River at Aluu were investigated. The highest depth value of 9.20 m was recorded in the middle of the river. The width of the river measured during spring high tide and low tide were 174 m and 110 m respectively. The cross-sectional area and average flow velocity of the river were 797.13 m2 and 0.374 m/s respectively. The discharge of the river was computed as 298.13m3/s. The river water was acidic most of the period (Hydrogen ion concentration, pH: 5.12 to 7.43), with low total alkalinity values (4.00 to 12.00 mgCaCO3/L) and low total hardness values (11.5 to 51.2 mgCaCO3/L) which indicate that the river water is black and soft. There was significant (p~,0.05) seasonal variation in temperature (23.1 to 31.7~'C\}, Secchi transparency (9.30 to 19.00 cm), total hardness (11.5 to 51.2 mgCaCO3/L), dissolved oxygen (5.20 to 7.50 mg/L) and dissolved oxygen deficit (0.02 to 2.95mg/L). These results are useful for several stake holders who use the river as a sink for trade wastes, as source of water for fish farming, as source of broodstocks of Chrysichthys nigrodigitatus, as raw water for water treatment plants, and as means of transportation of industrial materials.
    Description: Includes: 16 references.
    Keywords: Chemistry ; Fisheries ; Limnology ; Chrysichthys nigrodigitatus ; Nigeria ; New Calabar River ; New calabar River ; Physical characteristics and physico-chemical features ; Seasonal variation ; freshwater environment ; automation
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    Format: 206-210
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  • 7
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24619 | 19325 | 2018-05-22 06:14:16 | 24619 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Eight month physicochemical study of Dadin Kowa Dam was carried out forthnightly from July, 2011 to february 2012. Air temperature ranged from 18.25~'C ~c 28~'C ~c 0.50 to 28~'C ~c 2.16. Water tmperature ranged from 18.75~'C ~c 2.21. Transparency ranged from 11.00cm ~c 1.83 to 29.63 cm ~c ~c 2.14. Conductivity ranged from 13.00~Ks/cm ~c 13.33 to 41.38~Ks/cm ~c 5.54. Hydrogen ion (pH) ranged from 6.69 ~c 1.03 to 8.39 ~c 1.17. Dissolved oxygen ranged from 6.39mg/l ~c 1.03 to 10.14mg/l ~c 1.17. Total alkalinity ranged from o.69mg/l ~c 0.38 1.34mb/l ~c 0.02. Total ammonia ranged from 0.20mg/l ~c 0.027 to 0.83mg/l ~c 0.05. There were various levels of correlation between these parameters. There was no significant difference between both sites and months (p〉0.05) of all the parameters except total nitrogen which show a significant difference between the sites (p〈0.05) and transparency also shows a significance between the months (p〈0.05). All physicochemical parameters were almost within the tolerable limits for supporting aquatic life.
    Description: Includes: 27 references.
    Keywords: Fisheries ; Chemistry ; Nigeria ; Dadin Kowa Dam ; Physico-chemical parameters ; Fish production ; Dadin Kowa Dam ; freshwater environment ; automation
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    Format: 211-213
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  • 8
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    FISON | Akure (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23326 | 19325 | 2018-04-06 16:03:20 | 23326 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: This study looked into the physicochemical and bacteriological investigation of fish and water in Aiba Reservoir. Water and fish samples collected were studied to assess their bacteriological and physicochemical characteristics and their suitability for domestic purposes. Structural questionnaires were administered to the fishermen around the reservoir and experiments were carried out in the laboratory to analyze the samples. The results showed that the total viable bacteria count was high(1.02 x 105 cfu/ml) while few Staphylococcus aureus and E. coli occurred insignificantly. The population of S. aureus and E. coli in the fish gills, liver and tissue were insignificant. The results obtained from the physicochemical analysis of the water samples showed that the reservoir has optimum water temperature of 29degreesC ~c 0.25, a pH of 7.70 ~c 0.20, dissolved Oxygen level of 7.20mgO2/1 ~c 0.20 and total hardness of 45.00 mg/ICaC03 ~c 1.05. The microbial load in the fish sample is higher than that in the water sample. Further strict hygienic measures and surveillance is recommended so as to improve the water quality and to avoid deleterious effects on the health of the Iwo inhabitants and its neighboring communities who also benefit from the reservoir.
    Description: Includes:- 2 figs.;11 refs.
    Keywords: Chemistry ; Fisheries ; Nigeria ; Aiba Reservoir ; freshwater environment ; Physicochemical properties ; Bacteriology ; Water quality ; Water ; Bacterial counters
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  • 9
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    FISON | Akure (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23410 | 19325 | 2018-04-12 09:04:25 | 23410 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: Comparative primary production in Little Stream Farms, near Uyo was investigated in relation to physico-chemical parameters of the adjacent perennial stream and the fish ponds. Except for temperature, which showed the same values for both stations, physico-chemical variables generally showed significant difference (P〈O.05) between the pond water and the adjacent stream. Values of silicates, Turbidity (NTU), Secchi Disc Transparency and Total Suspended Solids (TSS) exhibited significantly variable trends (P〈O.05), especially in the stream water, in response to the commercial sand dredging activities upstream from the fann location. Lowest value of stream transparency (O.1M) recorded was during the peak of the sand dredging, whereas the stream water showed absolute transparency in the absence of the dredging. The water quality parameters also exhibited a general trend of significant seasonal variation (P〈O.05). Five phytoplankton families: Bacillariophyceae, Chlorophyceae, Cyanobacteria, Euglenophyceae and Dinophyceae occurred in the ponds, while three families, Bacillariophyceae, Chlorophyceae and Cyanobacteria occurred in the stream. Bacillariophyceae showed the highest relative abundance in both stations A and B.
    Description: Includes:- 1 table.;3 figs.;11 refs.
    Keywords: Aquaculture ; Chemistry ; Ecology ; Nigeria ; Akwa Ibom State ; freshwater environment ; Physicochemical properties ; Freshwater ecology ; Water quality ; Phytoplankton ; Suspended particulate matter
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  • 10
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    FISON | Akure (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23404 | 19325 | 2018-04-12 08:55:07 | 23404 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: The physico-chemical parameters of Lake Alau were monitored for four months to assess the water quality. Parameters such as temperature, transparency, conductivity, dissolved oxygen, biochemical oxygen demand, Ca, P, etc were studied in five stations (A, B, C, D and E). Water samples were collected monthly from 8:00 to l2:00noon, for four months (July - October 2008, wet season) and analysed. The physico-chemical parameters were within the ranges of unpolluted water bodies. Variation occurs in almost all the months of the study. Significant difference (P〈0.05) occurred in pH, transparency and Ca among the stations, and insignificant difference (P〉0.05) in temperature, conductivity, dissolved oxygen, biochemical oxygen demand, Mg and P. These variations may be due to effects of fertilizer application, herbicides and insecticides in irrigated farms around the Lake.
    Description: Includes:- 2 tables.;24 refs.
    Keywords: Chemistry ; Limnology ; Nigeria ; Alau L. ; freshwater environment ; Physicochemical properties ; Water quality ; Temperature ; Turbidity ; Transparency ; Dissolved oxygen
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    Format: 149-152
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  • 11
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24638 | 19325 | 2018-05-24 09:36:38 | 24638 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Study of some Physico-chemical parameters and fish species composition of Doma Darn was carried out between the month of August 2012. Fishing communities along the dam were selected at sampling stations and collection of fish species. The values of physico-parameters obtained for stations were in the range of 28.10-92 m for depth, 27.70-28.48~'for temperature, 7.03-7.64 for PH, 7.23-7.64mg/l for dissolved oxygen (DO), 30.08-31.75 ntu for turbidity, 94.64-105.17mg/l for alkalinity and 79.17-80.58mg/l for total hardness. The result indicated that there was significant difference (p〈0.5)for depth, temperature turbidity and alkalinity, while there was no significant difference (p〈0.05) for DO, pH and water hardness among the stations. The result of these parameters among the duration shows that there was significant different (p〈0.05) in all the parameters except pH. The study revealed that there were twenty-five (25) fish species belonging to 12 families in the dam. The family Cichlidae and Mochokidae and Bagridae which has three each, While the family, Polypteridae, Channidae, Centropomidae, flepsetidae and Protopteridae has the lowest number of one (1) each. The overall result revealed that the Phvsico-chemical parameters were mostly influenced by duration and not much by stations; and parametersoaram measured were within the recommended water quality requirement for growth and survival of aquatic organisms.
    Description: Includes: 10 references.
    Keywords: Chemistry ; Fisheries ; Nigeria ; Doma Dam ; Doma Dam ; Fishing community ; Physico-chemical parameter ; Fish species ; freshwater environment ; automation
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    Format: 295-297
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 49-53 
    ISSN: 1476-5535
    Keywords: l-Phenylacetyl carbinol ; Saccharomyces cerevisiae ; Yeast ; Benzaldehyde ; Biotransformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The rate of production ofl-phenylacetyl carbinol bySaccharomyces cerevisiae in reaction mixtures containing benzaldehyde with sucrose or pyruvate as cosubstrate was investigated in short 1 h incubations. The effect of yeast dose rate, sucrose and benzaldehyde concentration and pH on the rate of reaction was determined. Maximum biotransformation rates were obtained with concentrations of benzaldehyde, sucrose and yeast of 6 g, 40 g and 60 g/l, respectively. Negligible biotransformation rates were observed at a concentration of 8 g/l benzaldehyde. The reaction had a pH optimum of 4.0–4.5. Rates of bioconversion of benzaldehyde and selected substituted aromatic aldehydes using both sucrose and sodium pyruvate as cosubstrate were compared. The rate of aromatic alcohol production was much higher when sucrose was used rather than pyruvate.o-Tolualdehyde and 1-chlorobenzaldehyde were poor substrates for aromatic carbinol formation although the latter produced significant aromatic alcohol in sucrose-containing media. Yields of 2.74 and 3.80 g/l phenylacetyl carbinol were produced from sucrose and pyruvate, respectively, in a 1 h reaction period.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 81-84 
    ISSN: 1476-5535
    Keywords: Ethanol fermentation ; Wheat starch ; Saccharomyces cerevisiae ; immobilization ; Continuous dynamic immobilized biocatalyst bioreactor ; Biocatalyst bioreactor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A simple and efficient method of conversion of wheat starch B to ethanol was investigated. Employing a two-stage enzymatic saccharification process, 95% of the wheat starch was converted to fermentable sugars in 40 h. From 140 g/l total sugars in the feed solution, 63.6 g/l ethanol was produced continuously with a residence time of 3.3 h in a continuous dynamic immobilized biocatalyst bioreactor by immobilized cells ofSaccharomyces cerevisiae. The advantages and the application of this bioreactor to continuous alcoholic fermentation of industrial substrates are presented.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nutrition 22 (1983), S. 205-212 
    ISSN: 1436-6215
    Keywords: Schwermetallwirkung ; Malatdehydrogenase ; Glutamatdehydrogenase ; Glycerinaldehyd-3-phosphatdehydrogenase ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The difference between cadmium, zinc, lead, and mercury in regard of their effects on the activity of the enzymes tested is very slight. Concentrations higher than 10−5 M reduce significantly the activity of the enzymes, and concentrations of approximately 10−3 M inhibit it completely. An increase of the activity cannot be detected. The addition of combinations of cadmium, zinc, and lead results in a summing up of the toxic effects, whereas the interaction between mercury and the other three heavy metals shows a cumulative effect, which is appointed nearly completely by the heavy metal more toxic. The findings suggest that under in-vitro conditions there exists a direct interaction between the heavy metals and the enzymes.
    Notes: Zusammenfassung Die vier Schwermetalle Cadmium, Zink, Blei und Quecksilber unterscheiden sich in ihrer Wirkung auf die Aktivität der untersuchten Enzyme nur sehr wenig. Konzentrationen über 10−5 M vermindern die Enzymaktivität signifikant, und Konzentrationen von etwa 10−3 M unterbinden sie völlig. Eine Steigerung der Enzymaktivität läßt sich nicht feststellen. Die Zugabe von Cadmium-, Zink- und Bleikombinationen führt zu einer Addition der toxischen Effekte, während bei der Interaktion zwischen Quecksilber und den anderen drei Schwermetallen die Gesamtwirkung fast ausschließlich durch das stärker hemmende Schwermetall allein bestimmt wird. Die erhaltenen Ergebnisse lassen vermuten, daß es unter Invitro-Bedingungen zu einer direkten Wechselwirkung zwischen den Schwermetallen und den Enzymen kommt.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 91 (1999), S. 403-412 
    ISSN: 1570-7458
    Keywords: aphid ; Diuraphis noxia ; Triticum aestivum ; endosymbiont ; insect-plant interactions ; phloem ; amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The feeding behavior of Diuraphis noxia Mordvilko (Homoptera: Aphididae) on susceptible hosts causes both ultrastructural and tissue level damage which may affect phloem composition. Genetic evidence suggests that endosymbiotic bacteria in most aphids overproduce limiting amino acids to benefit hosts but that D. noxia depends less on endosymbionts for these nutrients, possibly due to an enriched diet. To determine whether D. noxia feeding damage results in higher concentrations of essential amino acids, stylet exudates were analyzed from wheat (Triticum aestivum) damaged to different degrees. Comparison of samples from undamaged and damaged susceptible wheat revealed changes in amino acid composition and an increase in levels of essential amino acids, indicating a nutritionally enhanced ingesta. The changes in stylet exudates paralleled changes in leaf exudates, indicating that the effects are systemic. Feeding damage is not observed on a resistant wheat host, var. Halt, and leaf exudates from infested Halt did not show changes in amino acid composition. Mean relative growth of nymphs was significantly lower on Halt than on susceptible Arapahoe, indicating that Halt is a less suitable host. Both varieties show similar amino acid levels in non-infested samples, suggesting that D. noxia infestation does not enhance the phloem environment in Halt. This study provides evidence that aphid feeding can generate a nutritionally enhanced phloem diet.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 58 (1991), S. 69-74 
    ISSN: 1570-7458
    Keywords: Rhopalosiphum padi ; antixenosis ; plant resistance ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Antixenose gegenüberRhopalosiphum padi (L.) in den drei Weizensorten Timmo, Moghan 2 und Ommid, von denen die zwei letzteren Sorten aus dem Iran stammen, wurde unter Verwendung des systemischen Insektizids Pirimicarb gemessen. Jeweils zwei Pflanzen aus verschiedenen Sorten wurden als Paar verwendet (in allen Kombinationen der drei Sorten), pro Paar ein Topf mit Pirimicarb gegossen, und zwanzig Blattlaüse über Blattflächen von beiden Sorten gekäfigt. Ähnliche Versuche wurden auch ohne Insektizid ausgeführt. Beide Methoden zeigten deutliche Antixenose von Moghan 2 und Ommid in Vergleich mit Timmo. Die Insektizidmethode zeigte auch eine Bevorzugung von Moghan 2 gegenüber Ommid, ein Resultat, das mit der schon bekannten relativen Antibiose dieser zwei Sorten übereinstimmte, während sich ohne Insektizid kein solcher Unterschied erwies. Die statistische Analyse solcher Versuche mit einem Insektizid, die eine Modifikation der Berechnung des erwarteten Werts mit dem χ2 Test enthält, ist beschrieben.
    Notes: Abstract Antixenosis in three wheat varieties (Timmo, Moghan 2 and Ommid) toRhopalosiphum padi (L.) was measured by pairing plants of any two varieties with one plant of each pair treated with a soil drench of the systemic insecticide pirimicarb. Aphids were then allowed access to equivalent leaf areas from the two plants in a leaf cage. The results were compared with similar choice experiments without insecticide. By either technique, the two Iranian varieties (Moghan 2 and Ommid) showed antixenosis in comparison with Timmo. The statistical analysis of the data, using a heterogeneity χ2 test, is described.
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  • 17
    ISSN: 1570-7458
    Keywords: LepidopteraEphestia kuehniella ; α-amylase ; Triticum aestivum ; endosperm ; α-amylase inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Crude α-amylase preparations from seven Lepidoptera pests were susceptible to inhibition by salt-soluble proteins of bread wheat (Triticum aestivum L.) endosperm. Protein fractions that corresponded to tetrameric, dimeric, and monomeric wheat α-amylase inhibitors, were decreasingly effective against the insect α-amylase activity. To further confirm these results, purified inhibitors were tested against an α-amylase preparation fromEphestia kuehniella (Zeller). This preparation showed decreased activity when increasing amounts of an heterotetrameric inhibitor (reconstituted from its isolated subunits WTAI-CM2, -CM3 and -CM16) were assayed. Activity was only partially inhibited by homodimeric (WDAI-1, synonym 0.53; WDAI-2, synonym 0.19) and monomeric (WMAI-1, synonym 0.28) inhibitors.
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  • 18
    ISSN: 1570-7458
    Keywords: sieve element ; salivation ; aphid ; plant resistance ; wheat ; Sitobion fragariae ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extended sieve element salivation (E1 waveform in the electrical penetration graph) is a characteristic activity during early sieve element punctures, particularly in resistant plants. In order to explore a chemically-mediated mechanism of resistance associated with sieve element salivation, we compared the pattern of feeding behaviour of the aphid, Sitobion fragariae (Walker), on two cultivars of the wheat Triticum aestivum L., with different concentrations of hydroxamic acids (Hx). During 24 h of electronic monitoring, aphids dedicated over 50% of the total time to phloem ingestion from the sieve elements. Total time allocated to E1 in the experiment, time to first E1 within the experiment, time allocated to E1 before a sustained phloem ingestion (E2) and the contribution of sieve element salivation to the phloem phase (E1/[E1+E2]) were significantly higher in the high-Hx cultivar. The increased salivation in plants with higher contents of Hx suggests the existence, at least in this system, of a chemically-mediated sieve element constraint.
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  • 19
    ISSN: 1572-8773
    Keywords: iron ; siderophores ; transport ; Saccharomyces cerevisiae ; fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Transport proteins of microorganisms may either belong to the ATP-binding cassette (ABC) superfamily or to the major facilitator (MFS)-superfamily. MFS transporters are single-polypeptide membrane transporters that transport small molecules via uniport, symport or antiport mechanisms in response to a chemiosmotic gradient. Although Saccharomyces cerevisiae is a non-siderophore producer, various bacterial and fungal siderophores can be utilized as an iron source. From yeast genome sequencing data six genes of the unknown major facilitator (UMF) family were known of which YEL065w Sce was recently identified as a transporter for the bacterial siderophore ferrioxamine B (Sit1p). The present investigation shows that another UMF gene, YHL047c Sce, encodes a transporter for the fungal siderophore triacetylfusarinine C. The gene YHL047c Sce (designated TAF1) was disrupted using the kanMX disruption module in a fet3 background (strain DEY 1394 Δfet3), possessing a defect in the high affinity ferrous iron transport. Growth promotion assays and transport experiments with 55Fe-labelled triacetylfusarinine C showed a complete loss of iron utilization and uptake in the disrupted strain, indicating that TAF1 is the gene for the fungal triacetylfusarinine transport in Saccharomyces cerevisiae and possibly in other siderophore producing fungi.
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  • 20
    ISSN: 1572-8773
    Keywords: major facilitator superfamily ; iron transport ; siderophores ; enterobactin ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract While in fungi iron transport via hydroxamate siderophores has been amply proven, iron transport via enterobactin is largely unknown. Enterobactin is a catecholate-type siderophore produced by several enterobacterial genera grown in severe iron deprivation. By using the KanMX disruption module in vector pUG6 in a fet3Δ background of Saccharomyces cerevisiae we were able to disrupt the gene YOL158c Sce of the major facilitator super family (MFS) which has been previously described as a gene encoding a membrane transporter of unknown function. Contrary to the parental strain, the disruptant was unable to utilize ferric enterobactin in growth promotion tests and in transport assays using 55Fe-enterobactin. All other siderophore transport properties remained unaffected. The results are evidence that in S. cerevisiae the YOL158c Sce gene of the major facilitator super family, now designated ENB1, encodes a transporter protein (Enb1p), which specifically recognizes and transports enterobactin.
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  • 21
    ISSN: 1572-8773
    Keywords: Manganese ; Electron spin resonance ; Superoxide dismutase ; Saccharomyces cerevisiae ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Manganese accumulation was studied by room-temperature electron spin resonance (ESR) spectroscopy inSaccharomyces cerevisiae grown in the presence of increasing amounts of MnSO4. Mn2+ retention was nearly linear in intact cells for fractions related to both low-molecular-mass and macromolecular complexes (‘free’ and ‘bound’ Mn2+, respectively). A deviation from linearity was observed in cell extracts between the control value and 0.1 mM Mn2+, indicating more efficient accumulation at low Mn2+ concentrations. The difference in slopes between the two straight lines describing Mn2+ retention at concentrations lower and higher than 0.1 mM, respectively, was quite large for the free Mn2+ fraction. Furthermore it was unaffected by subsequent dialyses of the extracts, showing stable retention in the form of low-molecular-mass complexes. In contrast, the slope of the line describing retention of ‘bound’ Mn2+ at concentrations higher than 0.1 mM became less steep after subsequent dialyses of the cell extracts. This result indicates that the macromolecule-bound Mn2+ was essentially associated with particulate structures. In contrast to Cu2+, Mn2+ had no effect on the major enzyme activities involved in oxygen metabolism except for a slight increase of cyanide-resistant Mn-superoxide dismutase activity, due to dialyzable Mn2+ complexes.
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  • 22
    ISSN: 1572-8773
    Keywords: catalase ; copper resistance ; pH-dependent growth ; Saccharomyces cerevisiae ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A strain of Saccharomyces cerevisiae has been adapted to increasing concentrations of copper at two different pH values. The growth curve at pH 5.5 is characterized by a time generation increasing with the amount of added copper. A significant decrease of cell volume as compared with the control is also observed. At pH 3 the cells grow faster than at pH 5.5 and resist higher copper concentrations (3.8 against 1.2 mm). Experimental evidence indicates that, after copper treatment, the metal is not bound to the cell wall, but is localized intracellularly. A significant precipitation of copper salts in the medium was observed only at pH 5.5. Increased levels of superoxide dismutase (SOD) activity were observed in copper-treated cells and which persisted after 20 subsequent inocula in a medium without added metal. On the contrary, catalase activity was not stimulated by copper treatment and, hence, not correlated with SOD levels. The mechanism of copper resistance, therefore, probably involves a persistent induction of SOD, but not of catalase, and it is strongly pH-dependent.
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  • 23
    ISSN: 1572-8773
    Keywords: EPR ; Saccharomyces cerevisiae ; uptake ; vanadate ; vanadyl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Vanadium uptake by whole cells and isolated cell walls of the yeast Saccharomyces cerevisiae was studied. When orthovanadate was added to wild-type S. cerevisiae cells growing in rich medium, growth was inhibited as a function of the VO4 3- concentration and the growth was completely arrested at a concentration of 20 mM of VO4 3- in YEPD. Electron paramagnetic resonance (EPR) spectroscopy was used to obtain structural and dynamic information about the cell-associated paramagnetic vanadyl ion. The presence of EPR signals indicated that vanadate was reduced by whole cells to the vanadyl ion. On the contrary, no EPR signals were detected after interaction of vanadate with isolated cell walls. A ‘mobile’ and an ‘immobile’ species associated in cells with small chelates and with macromolecular sites, respectively, were identified. The value of rotational correlation time τ r indicated the relative motional freedom at the macromolecular site. A strongly ‘immobilized’ vanadyl species bound to polar sites mainly through coulombic attractions was detected after interaction of VO2+ ions with isolated cell walls.
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  • 24
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    Entomologia experimentalis et applicata 59 (1991), S. 79-85 
    ISSN: 1570-7458
    Keywords: Wheat ; Triticum aestivum ; cereals ; Rhopalosiphum padi ; Aphididae ; barley yellow dwarf virus ; hydroxamic acids ; DIMBOA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), a hydroxamic acid (Hx) occurring in wheat, was shown to deter feeding by the aphid Rhopalosiphum padi (L.), and to reduce BYDV transmission to the plant. Dual choice tests with wheat leaves showed the preferential settlement of aphids on leaves with lower levels of DIMBOA. Electric monitoring of aphid feeding behaviour showed that in seedlings with higher DIMBOA levels fewer aphids reached the phloem and they needed longer times to contact a phloem vessel than in those with lower levels. When aphids carrying BYDV were allowed to feed on wheat cultivars with different DIMBOA levels, fewer plants were infected with BYDV in the higher DIMBOA cultivars than in the lower ones. Preliminary field experiments showed a tendency for wheat cultivars with higher Hx levels to be more tolerant to infection by BYDV than lower Hx level ones.
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  • 25
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    Cellular and molecular life sciences 40 (1984), S. 1159-1161 
    ISSN: 1420-9071
    Keywords: Saccharomyces cerevisiae ; 5-trifluoromethyl-6-àzauracil ; yeast cell cultures ; cell division ; inhibition of
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cell division, as studied in asynchronous cultures of yeast cells, is sensitive to 5-trifluoromethyl-6-azauracil (F3CAzU). Under defined conditions (10 mmoles l−1 F3CAzU) this compound blocks immediately and completely the process of cell division. Using synchronized cells, the time-point at which division process of yeast cell can be inhibited by F3CAzU has been determined. The inhibitor effect of this compound is completely reversed by thymine, thymidine and uracil.
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  • 26
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    Cellular and molecular life sciences 43 (1987), S. 886-888 
    ISSN: 1420-9071
    Keywords: Saccharomyces cerevisiae ; trichothecenes ; mycotoxins ; vitamins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Several trichothecene mycotoxins were shown to inhibit the growth ofSaccharomyces cerevisiae. This effect was most pronounced with the macrocyclic trichothecenes, especially verrucarin A. Much less growth inhibition was observed with T-2 toxin. Verrucarol, diacetoxyscirpenol, acetyl T-2 toxin, HT-2 toxin, T-2 tetraol and neosolaniol were inactive at a concentration of 75 μg of toxin per disc. Incubation ofS. cerevisiae with verrucarin A together with vitamins resulted in a decrease in toxicity. Pyridoxine-HCl, Ca-pantothenate, thiamine-HCl and α-tocopheryl acetate were amongst the most potent of the vitamins tested which reversed growth inhibition, overcoming the inhibitory potential of the toxins.
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  • 27
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    Cellular and molecular life sciences 43 (1987), S. 888-890 
    ISSN: 1420-9071
    Keywords: Thiaminase ; thiamine ; thiamine antagonist ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary It was found that cell-free extracts ofSaccharomyces cerevisiae contain thiaminase II which hydrolyzes thiamine and thiamine analogs. The possible involvement of this enzyme and thiamine-synthesizing enzymes in thiamine production from thiamine antagonists is discussed.
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  • 28
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    Cellular and molecular life sciences 52 (1996), S. 1130-1135 
    ISSN: 1420-9071
    Keywords: Saccharomyces cerevisiae ; mitochondria ; mRNA-specific translational activation ; synthetic genes ; gene regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mitochondrial gene expression in yeast,Saccharomyces cerevisiae, depends on translational activation of individual mRNAs by distinct proteins encoded in the nucleus. These nuclearly coded mRNA-specific translational activators are bound to the inner membrane and function to mediate the interaction between mRNAs and mitochondrial ribosomes. This complex system, found to date only in organelles, appears to be an adaptation for targeting the synthesis of mitochondrially coded integral membrane proteins to the membrane. In addition, mRNA-specific translational activation is a rate-limiting step used to modulate expression of at least one mitochondrial gene in response to environmental conditions. Direct study of mitochondrial gene regulation and the targeting of mitochondrially coded proteins in vivo will now be possible using synthetic genes inserted into mtDNA that encode soluble reporter/passenger proteins.
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  • 29
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    Cellular and molecular life sciences 48 (1992), S. 1162-1164 
    ISSN: 1420-9071
    Keywords: Polygodial ; warburganal ; antifungal activity ; Candida albicans ; Saccharomyces cerevisiae ; Pityrosporum ovale ; enhancing effect ; antioxidants ; vitamin C ; BHA ; anethole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The antifungal activity of two drimane sesquiterpene dialdehydes, polygodial (1) and warburganal (2), alone and in combination with several other substances, was examined against three fungi,Candida albicans, Saccharomyces cerevisiae andPityrosporum ovale employing a broth dilution method. Anethole significantly synergized the activity of the two sesquiterpenoids againstC. albicans andS. cerevisiae however, it had only an, additive effect againstP. ovale. By contrast, two antioxidants, ascorbic acid (vitamin C) and BHA (butylated hydroxyanisole), noticeably enhanced the activity of the sesquiterpenoids againstP. ovale, but had no, effect againstC. albicans andS. cerevisiae.
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  • 30
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    Cellular and molecular life sciences 52 (1996), S. 1033-1041 
    ISSN: 1420-9071
    Keywords: Ubiquitin ; yeast ; Saccharomyces cerevisiae ; Dictyostelium discoideum ; cytoskeleton ; mutants ; endocytosis ; actin ; myosin ; calmodulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Endocytosis is a general term that is used to describe the internalization of external and plasma membrane molecules into the cell interior. In fact, several different mechanisms exist for the internalization step of this process. In this review we emphasize the work on the actin-dependent pathways, in particular in the yeastSaccharomyces cerevisiae, because several components of the molecular machinery are identified. In this yeast, the analysis of endocytosis in various mutants reveals a requirement for actin, calmodulin, a type I myosin, as well as a number of other proteins that affect actin dynamics. Some of these proteins have homology to proteins in animal cells that are believed to be involved in endocytosis. In addition, the demonstration that ubiquitination of some cell surface molecules is required for their efficient internalization is described. We compare the actin, myosin and ubiquitin requirements for endocytosis with recent results found studying these processes usingDictyostelium discoideum and animal cells.
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  • 31
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    Cellular and molecular life sciences 52 (1996), S. 1111-1116 
    ISSN: 1420-9071
    Keywords: Mitochondria ; mitochondrial inheritance ; cytoskeleton ; Saccharomyces cerevisiae ; Schizosaccharomyces pombe ; membrane proteins ; organelle movement ; mitochondrial morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mechanisms mediating the inheritance of mitochondria are poorly understood, but recent studies with the yeastsSaccharomyces cerevisiae andSchizosaccharomyces pombe have begun to identify components that facilitate this essential process. These components have been identified through the analysis of conditional yeast mutants that display aberrant mitochondrial distribution at restrictive conditions. The analysis of these mutants has uncovered several novel proteins that are localized either to cytoskeletal structures or to the mitochondria themselves. Many mitochondrial inheritance mutants also show altered mitochondrial morphology and defects in maintenance of the mitochondrial genome. Although some inheritance components and mechanisms appear to function specifically in certain types of cells, other conserved proteins are likely to mediate mitochondrial behavior in all eukaryotic cells.
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  • 32
    ISSN: 1420-9071
    Keywords: Saccharomyces cerevisiae ; mitochondrial ribosomes ; peptidyl transferase ; Varl ribosomal protein ; gene relocation ; posttranscriptional rRNA modification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mitochondria posses their own ribosomes responsible for the synthesis of a small number of proteins encoded by the mitochondrial genome. In yeast,Saccharomyces cerevisiae, the two ribosomal RNAs and a single ribosomal protein, Varl, are products of mitochondrial genes, and the remaining approximately 80 ribosomal proteins are encoded in the nucleus. The mitochondrial translation system is dispensable in yeast, providing an excellent experimental model for the molecular genetic analysis of the fundamental properties of ribosomes in general as well as adaptations required for the specialized role of ribosomes in mitochondria. Recent studies of the peptidyl transferase center, one of the most highly conserved functional centers of the ribosome, and the Varl protein, an unusual yet essential protein in the small ribosomal subunit, have provided new insight into conserved and divergent features of the mitochondrial ribosome.
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  • 33
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    BioMetals 12 (1999), S. 289-294 
    ISSN: 1572-8773
    Keywords: accumulation ; gold ; proton efflux ; Saccharomyces cerevisiae ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract This paper examines the effects of ionic gold on Saccharomyces cerevisiae, as determined by long-term (growth in gold-containing media) and short-term interactions (H+ efflux activity). An increasing gold concentration inhibited growth and at 〈0.2 mM Au, growth was not observed. Transmission electron microscopy revealed no differences in ultrastructure but fine electron dense particles were observed in unstained preparations from gold-containing medium. After glucose addition (to 10mM) to starved suspensions of S. cerevisiae, glucose-dependent reduction of external pH occurred as the cells extruded protons. In the presence of increasing gold concentrations, the lag time before proton extrusion did not change but the rate and duration decreased significantly with a marked influence on proton efflux rate being observed at ≤ 10 μM. Extension of preincubation time of yeast cells in gold-containing medium resulted in a decreasing proton efflux rate and colloidal phase formation in the cell suspensions, the time between gold addition and the beginning of colloidal phase formation depending on the gold concentration used. Both Ca and Mg enhanced the inhibitory effect of gold on the yeast cells with Ca showing a stronger inhibitory effect than Mg.
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  • 34
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    Journal of industrial microbiology and biotechnology 7 (1991), S. 131-135 
    ISSN: 1476-5535
    Keywords: Saccharomyces cerevisiae ; Jerusalem artichoke ; High-fructose syrup ; Ethanol ; Immobilized yeast cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The results from this study showed that Jerusalem artichoke juice can be used for the production of very enriched fructose syrup by selective conversion of glucose to ethanol in a continuous process using immobilized cells ofSaccharomyces cerevisiae ATCC 36859. The product contained up to 99% of the total carbohydrates as fructose compared to 76% in the feed. Using Jerusalem artichoke juice supplemented with some glucose a product was obtained with 7.5% w/v ethanol which made ethanol recovery economically favourable. It was found that some fructose was consumed in these continuous processes; the glucose/fructose conversion rate ratio was regulated by the glucose concentration in the product stream.
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  • 35
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    Journal of industrial microbiology and biotechnology 7 (1991), S. 181-189 
    ISSN: 1476-5535
    Keywords: Saccharomyces cerevisiae ; Torulaspora delbrueckii ; Aroma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Thirty-three fermentations of Pedro Ximénez grapes, collected in three degrees of ripeness, were carried out by inoculation with three types of inoculum: pure cultures ofSaccharomyces cerevisiae races and ofTorulaspora delbrueckii, indigenous yeasts, and mixed cultures of indigenous yeasts enriched with the pure cultures. By means of variance analysis 21 compounds were determined whose final concentrations in the wines significantly depended on the musts, the inocula or both. Eleven products that depended significantly on the inocula were subjected to a discriminant analysis in which most of the pure cultures gathered in a discriminant space area different from that occupied by the indigenous yeasts. The centroids corresponding to most of the mixed cultures were shifted to the central area of the discriminant space, moved away from their corresponding pure cultures and approached the indigenous yeasts. The results show a high similarity between the fermentations carried out with mixed cultures with the addedS. cerevisiae races and those fermentations carried out with the indigenous yeasts, with regard to those compounds which were significantly dependent on the inocula.
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  • 36
    ISSN: 1432-1890
    Keywords: Key words Glomus mosseae ; Hydroponics ; Nitrate uptake ; Root respiration ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Oxygen and CO2 fluxes were measured in hydroponically grown mycorrhizal and non-mycorrhizal Triticum aestivum L. cv. Hano roots. The NO3 – uptake of the plants was used to estimate the amount of root respiration attributable to ion uptake. Plants were grown at 4 mM N and 10 μM P, where a total and viable mycorrhizal root colonisation of 48% and 18%, respectively, by Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe (BEG 107) was observed. The O2 consumption and NO3 – uptake rates were similar and the CO2 release was higher in mycorrhizal than in non-mycorrhizal wheat. This resulted in a significantly higher respiratory quotient (RQ, mol CO2 mol–1 O2) in mycorrhizal (1.27±0.13) than in non-mycorrhizal (0.79±0.05) wheat. As the biomass and N and P concentrations in mycorrhizal and non-mycorrhizal wheat were the same, the higher RQ resulted from the mycorrhizal colonisation and not differences in nutrition per se.
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  • 37
    ISSN: 1432-0789
    Keywords: Wheat ; Paddy straw compost ; N and P enrichment ; Rock phosphate ; Pyrite ; Triticum aestivum ; Nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A nutrient-rich compost from paddy straw was prepared using urea and Mussoorie rock phosphate for N and P enrichment respectively. Inorganic N was partly conserved in the compost by the addition of pyrite. Citric-acid-soluble P also increased with the addition of pyrite. Compost containing about 1.6% total N and 3.3% total P was found to be a good source of P for a wheat crop and also supplied a significant amount of N to the plants.
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  • 38
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    Biology and fertility of soils 9 (1990), S. 281-282 
    ISSN: 1432-0789
    Keywords: Surface sterilization ; Contaminants ; Sterile plant selection ; Axenic seedlings ; Triticum aestivum ; Trifolium pratense ; Trifolium repens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sterile seedlings are required for the investigation of interactions between microorganisms and plants. The present study was designed to develop a simple and reliable method for the selection of sterile seedlings by the use of liquid nutrient media, avoiding some of the disadvantages of solid media. The method of germinating surface-sterilized seedlings on solid water agar or nutrient media was compared with our method for sterility control in nutrient broth. Sterile plant selection in liquid media was the most sensitive method for detecting bacterial and fungal contaminants. Sterile plants grow with the same vigour as unsterilized plants and can be used for sterile plant experiments.
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  • 39
    ISSN: 1432-0789
    Keywords: 15N-labelled fertilizer ; Added N interaction Fertilizer N uptake ; Soil N uptake ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of 15N-labelled ammonium nitrate, urea and ammonium sulphate on yield and uptake of labelled and unlabelled N by wheat (Triticum aestivum L. cv. Mexi-Pak-65) were studied in a field experiment. The dry matter and N yields were significantly increased with fertilizer N application compared to those from unfertilized soil. The wheat crop used 64.0–74.8%, 61.5–64.7% and 61.7–63.4% of the N from ammonium nitrate, urea and ammonium sulphate, respectively. The fertilizer N uptake showed that ammonium nitrate was a more available source of N for wheat than urea and ammonium sulphate. The effective use of fertilizer N (ratio of fertilizer N in grain to fertilizer N in whole plant) was statistically similar for the three N fertilizers. The application of fertilizer N increased the uptake of unlabelled soil N by wheat, a result attributed to a positive added N interaction, which varied with the method of application of fertilizer N. Ammonium nitrate, urea and ammonium sulphate gave 59.3%, 42.8% and 26.3% more added N interaction, respectively, when applied by the broadcast/worked-in method than with band placement. A highly significant correlation between soil N and grain yield, dry matter and added N interaction showed that soil N was more important than fertilizer N in wheat production. A values were not significantly correlated with added N interaction (r=0.719). The observed added N interaction may have been the result of pool substitution, whereby added labelled fertilizer N stood proxy for unlabelled soil N.
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  • 40
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    Biology and fertility of soils 3 (1987), S. 199-204 
    ISSN: 1432-0789
    Keywords: Phosphatases ; Rhizosphere ; Organic phosphorus ; Allium cepa ; Brassica oleracea ; Triticum aestivum ; Trifolium alexandrinum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The distribution of phosphatase activity and of phosphate fractions of the soil in the proximity of roots was studied in order to evaluate the significance of phosphatases in P nutrition of various plants (Brassica oleracea, Allium cepa, Triticum aestivum, Trifolium alexandrinum). A considerable increase in both acid and alkaline phosphatase activity in all the four soil-root interfaces was observed. Maximum distances from the root surface at which activity increases were observed ranged from 2.0 mm to 3.1 mm for acid phosphatase and from 1.2 mm to 1.6 mm for alkaline phosphatase. The increase in phosphatase activity depended upon plant age, plant species and soil type. A significant correlation was noticed between the depletion of organic P and phosphatase activity in the rhizosphere soil of wheat (r = 0.99**) and clover (r = 0.97**). The maximum organic P depletion was 65% in clover and 86% in wheat, which was observed within a distance from the root of 0.8 mm in clover and 1.5 mm in wheat. Both the phosphatases in combination appear to be responsible for the depletion of organic P.
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  • 41
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    Biology and fertility of soils 23 (1996), S. 327-331 
    ISSN: 1432-0789
    Keywords: CO2 emission ; Field method ; Soil respiration ; Triticum aestivum ; Soil moisture ; Carbon reservoirs ; Greenhouse effect ; Grey forest soil ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of the rate of CO2 evolution from soil in fallow and croplant under spring wheat (Triticum aestivum L.) was studied in a crop rotation in grey forest soil of the Baikal forest-steppe during the growing season and in different years. It was shown that the regional characteristics of soils and hydrothermal conditions in different years affect the rate of CO2 evolution in agroecosystems. The seasonal dynamics of CO2 is characterized by insignificant changes in the autumn to spring period and enhanced emission in hot and dry summers. CO2 evolution is assumed to increase due to enhanced mineralization and partial diffusion from the carbonate horizon at the depth of the seasonal frost. During the growing season the dynamics of CO2 evolution depends on the soil moisture regime. There was a strong correlation between the rate of CO2 emission and soil moisture in the particularly dry year of 1993 (η=0.86) and a moderate correlation in the other years (η=0.38–0.54). The effect of the previous crop and fertilizer application on the rate of CO2 emission was insignificant. In a continuous fallow the total carbon release into the atmosphere varied throughout the years studied from 558 to 1880 kg ha-1. Humus losses varied from 0.9% to 3.1%.
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  • 42
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    Biology and fertility of soils 5 (1987), S. 76-82 
    ISSN: 1432-0789
    Keywords: Biomass accumulation ; Decomposition ; Litter ; Soil organic matter ; Soil respiration ; 14C deposition ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In a field experiment with 14C-labeled winter wheat conducted in the north-central region of the United States, crop-accumulated carbon (grain excluded) returned to the soil was found to be 542 g m−2 year−1. Almost half of the carbon from the underground compartment was released in the form of CO2 during the first 3 months after harvest due to very favorable conditions for biological activity. After 18 months, no less than 80% of the carbon from the plant residues was mineralized. About 16% of straw carbon and 24% of root carbon was transferred into soil organic matter. The annual rate of soil organic matter decomposition was approximated as 1.7%.
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  • 43
    ISSN: 1432-0789
    Keywords: Triticum aestivum ; T. turgidum ; Nitrogen fixation ; Field inoculation ; Acetylene reduction assay (ARA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Eight commercial Israeli spring wheat cultivars (six Triticum aestivum and two T. turgidum) grown with 40 and 120 kg N/ha were tested for responses to inoculation with Azospirillum brasilense. At the low level of N fertilization (40 kg/ha), five cultivars showed significant increases in plant dry weight measured at the milky ripe stage; however, by maturation only the cultivar “Miriam” showed a significant increase in grain yield. Two cultivars, which had shown a positive inoculation effect at the earlier stages, had a significant decrease in grain yield. No significant effect of inoculation was found at the high N level. To confirm those results, four wheat (T. aestivum) cultivars were tested separately over 4 years in 4 different locations under varying N levels. Only Miriam showed a consistently positive effect of Azospirillum inoculation on grain yield. Inoculation increased the number of roots per plant on Miriam compared with uninoculated plants. This effect was found at all N levels. Nutrient (N, P and K) accumulation and number of fertile tillers per unit area were also enhanced by Azospirillum, but these parameters were greatly affected by the level of applied N. It is suggested that the positive response of the spring wheat cultivar “Miriam” to Azospirillum inoculation is due to its capacity to escape water stresses at the end of the growth season.
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  • 44
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    Biology and fertility of soils 23 (1996), S. 327-331 
    ISSN: 1432-0789
    Keywords: Key words CO2 emission ; Field method ; Soil respiration ; Triticum aestivum ; Soil moisture ; Carbon reservoirs ; Greenhouse effect ; Grey forest soil ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of the rate of CO2 evolution from soil in fallow and cropland under spring wheat (Triticum aestivum L.) was studied in a crop rotation in grey forest soil of the Baikal forest-steppe during the growing season and in different years. It was shown that the regional characteristics of soils and hydrothermal conditions in different years affect the rate of CO2 evolution in agroecosystems. The seasonal dynamics of CO2 is characterized by insignificant changes in the autumn to spring period and enhanced emission in hot and dry summers. CO2 evolution is assumed to increase due to enhanced mineralization and partial diffusion from the carbonate horizon at the depth of the seasonal frost. During the growing season the dynamics of CO2 evolution depends on the soil moisture regime. There was a strong correlation between the rate of CO2 emission and soil moisture in the particularly dry year of 1993 (η=0.86) and a moderate correlation in the other years (η=0.38–0.54). The effect of the previous crop and fertilizer application on the rate of CO2 emission was insignificant. In a continuous fallow the total carbon release into the atmosphere varied throughout the years studied from 558 to 1880 kg ha–1. Humus losses varied from 0.9% to 3.1%.
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  • 45
    ISSN: 1432-0789
    Keywords: Key words Phosphate-solubilizing microorganisms ; Mussoorie rock phosphate ; Vesicular-arbuscular mycorrhizae ; Triticum aestivum ; Nutrient-deficient soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The effect of inoculating wheat (Triticum aestivum L.) with the PO4 3–-solubilizing microorganisms (PSM) Bacillus circulans and Cladosporium herbarum and the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus sp. 88 with or without Mussoorie rock phosphate (MRP) amendment in a nutrient-deficient natural sandy soil was studied. In the sandy soil of low fertility root colonization by VAM fungi was low. Inoculation with Glomus sp. 88 improved root colonization. At maturity, grain and straw yields as well as N and P uptake improved significantly following inoculation with PSM or the VAM fungus. These increases were higher on combined inoculation of PSM and the VAM fungus with MRP amendment. In general, a larger population of PSM was maintained in the rhizosphere of wheat in treatments with VAM fungal inoculation and MRP amendment. The results suggest that combined inoculation with PSM and a VAM fungus along with MRP amendment can improve crop yields in nutrient-deficient soils.
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  • 46
    ISSN: 1432-0789
    Keywords: Azospirillum brasilense ; Triticum aestivum ; Inoculation ; N and dry matter yield ; N percentages in plant parts ; Associative N2 fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wheat plants (Triticum aestivum) grown in pots and in the field under the Mediterranean climate of the south of France were inoculated with a strain of Azospirillum brasilense. Comparisons with non-inoculated plants grown under the same conditions showed significant responses to inoculation with an increase in the number of fertile tillers, shoot and root dry weight, and root to shoot biomass ratio. The roots of inoculated plants attracted relatively more assimilates than those of the control plants until a late stage of growth (heading stage) but the rhizosphere respiration expressed per unit of root growth was not increased by inoculation. Nitrogen yield, both total and in grains, was also enhanced; however, N percentages of all aerial parts of the plants grown in pots were always statistically lower after inoculation than in the control. At maturity, the N % in seeds was 1.81 and 2.45, respectively. The possible mechanisms of this effect of inoculation under the experimental conditions of this study are discussed.
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  • 47
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    Biology and fertility of soils 23 (1996), S. 273-281 
    ISSN: 1432-0789
    Keywords: Wheat ; Triticum aestivum ; Rhizosphere ; Soil microflora ; Gram-negative bacteria ; API 20 NE ; Flavobacterium spp ; Cytophaga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We identified 161 Gram-negative bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into seven groups based on major morphological and physiological properties. Taxonomic allocation of the groups was verified by guanine+cytosine contents of DNA. Except for one group, which may be assumed to include bacteria belonging to the genera Flavobacterium and Cytophaga, the various groups were taxonomically united. The distribution of the groups changed with soil improvement. Pseudomonads predominated in unimproved soil, but Flavobacterium and Cytophaga spp. were predominant in the most improved soil. As all the strains were non-fermentative by Hugh and Leifson's test, API 20NE identification was applied. However, many strains were misidentified by this system, especially in the Flavobacterium and Cytophaga spp. group. For ecological studies, the strains were classified to species level by the API 20 NE system and by the results of a combination of guanine+cytosine (mol%) and isoprenoid quinone data. The pattern of distribution of the bacteria on the root surface of wheat varied at species level within one genus depending on soil conditions.
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  • 48
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    Biology and fertility of soils 7 (1988), S. 67-70 
    ISSN: 1432-0789
    Keywords: Root activity ; Soil C mineralization ; 14C-labelled plant material ; Decomposition stages ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two different soils were amended with 14C-labelled plant material and incubated under controlled laboratory conditions for 2 years. Half the samples were cropped with wheat (Triticum aestivum) 10 times in succession. At flowering, the wheat was harvested and the roots removed from the soil, and a new crop was started. Thus, the soil was continuously occupied by predominantly active root systems. The remaining samples were maintained without plants under the same conditions. The aim of the experiment was to study the effects of active roots on C-mineralization rates during different stages of decomposition and during long-term incubation. During the first 200 days, corresponding to the active decomposition stages, the roots weakly reduced 14C mineralization. With a lower level of decomposition, when more than 60% of the initial 14C was mineralized and when the available nutrients were markedly exhausted by plant uptake, the roots stimulated 14C mineralization.[/ p]
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  • 49
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    Biology and fertility of soils 7 (1988), S. 71-78 
    ISSN: 1432-0789
    Keywords: Root activity ; Rhizosphere ; C metabolism ; Microbial biomass ; Microbial activity ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two different soils were amended with 14C-labelled plant material and incubated under controlled laboratory conditions for 2 years. Half the samples were cropped with wheat (Triticum aestivum) 10 times in succession. At flowering, the wheat was harvested and the old roots removed from the soil, so that the soil was continuously occupied by predominantly active root systems. The remaining samples were maintained without plants under the same conditions. During the initial stages of high microbial activity, due to decomposition of the labile compounds, the size of the total microbial biomass was comparable for both treatments, and the metabolic quotient (qCO2-C = mg CO2-C·mg−1 Biomass C·h−1) was increased by the plants. During the subsequent low-activity decomposition stages, after the labile compounds had been progressively mineralized, the biomass was multiplied by a factor of 2–4 in the presence of plants compared to the bare soils. Nevertheless, qCO2-C tended to reach similar low values with both treatments. The 14C-labelled biomass was reduced by the presence of roots and qCO2-14C was increased. The significance of these results obtained from a model experiment is discussed in terms of (1) the variation in the substrate originating from the roots and controlled by the plant physiology, (2) nutrient availability for plants and microorganisms, (3) soil biotic capacities and (4) increased microbial turnover rates induced by the roots.
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  • 50
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    Biology and fertility of soils 4 (1987), S. 37-40 
    ISSN: 1432-0789
    Keywords: Azospirillum brasilense ; Azospirillum amazonense ; rate reductase ; Inoculation ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Three field experiments with wheat were conducted in 1983, 1984, and 1985 in Terra Roxa soil in Paraná, the major Brazilian wheat-growing region, to study inoculation effects of various strains of Azospirillum brasilense and A. amazonense. In all three experiments inoculation with A. brasilense Sp 245 isolated from surface-sterilized wheat roots in Paraná produced the highest plant dry weights and highest N% in plant tops and grain. Grain yield increases with this strain were up to 31 % but were not significant. The application of 60 or 100 kg N ha−1 to the controls increased N accumulation and produced yields less than inoculation with this strain. Another A. brasilense strain from surface-sterilized wheat roots (Sp 107st) also produced increased N assimilation at the lower N fertilizer level but reduced dry weights at the high N level, while strain Sp 7 + Cd reduced dry weights and N% in the straw at both N levels. The A. amazonense strain isolated from washed roots and a nitrate reductase negative mutant of strain Sp 245 were ineffective. Strains Sp 245 and Sp 107st showed the best establishment within roots while strain Cd established only in the soil.
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  • 51
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    Biology and fertility of soils 4 (1987), S. 41-46 
    ISSN: 1432-0789
    Keywords: Competition ; Migration ; Colonization potential ; Replica printing ; Triticum aestivum ; Pseudomonas fluorescens ; Bacillus subtilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Colonization patterns of Pseudomonas fluorescens and Bacillus subtilis on roots of wheat seedlings growing on water agar were studied qualitatively by replica printing and quantitatively by the plate count method. The results indicated a stronger colonization potential for P. fluorescens (up to 107 cfu/cm root) than for B. subtilis (up to 105 cfu/cm root). Although the numbers of both species were lower when inoculated together, the observed colonization patterns on the roots were comparable to those found with single inoculations. For none of these bacteria was active migration along the root surface in any direction observed, indicating that distal positions are reached mainly by a passive displacement on the root tip and elongating cells. Ecological implications of the observed phenomena are discussed.
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  • 52
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    Biology and fertility of soils 5 (1987), S. 31-35 
    ISSN: 1432-0789
    Keywords: Gaeumannomyces graminis ; VegVetative growth ; Pathogenicity ; Herbicides ; Diquat+paraquat ; Glyphosate ; Dicamba ; Trifluralin ; Chlorsulfuron ; Chlorthal dimethyl ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of Spray Seed (diquat + paraquat), Roundup (glyphosate), Banvel-D (dicamba), Treflan (trifluralin), Glean (chlorsulfuron) and Dacthal (chlorthal dimethyl) at concentrations of 0–500 ppm product on the vegetative growth, vigour and pathogenicity of Gaeumannomyces graminis var. tritici (Ggt) on wheat were examined. All herbicides with the exception of dicamba and chlorsulfuron inhibited fungal growth on potato dextrose agar (PDA) at concentrations 10–500-fold of rates recommended for use in the field. The vegetative growth of the pathogen growing out of straw colonized on PDA supplemented with 100 ppm diquat + paraquat or glyphosate was reduced by 47.4% and 42.4%, respectively. When portions of these colonies were subcultured onto unamended PDA, their growth and the pathogenicity of straw pieces colonized by these subcultures were found to be unaltered. Straw colonized by Ggt on agar amended with concentrations of diquat + paraquat or at all concentrations of glyphosate produced less root disease in wheat seedlings in comparison to those colonized on unamended agar. It is proposed that the reduced pathogenicity of inocula prepared on agar amended with these two herbicides is due to poor colonization by the pathogen of straw on these media, and that a similar effect on saprophytic colonization in the field could lead to a reduction in the field inocula of the pathogen.
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  • 53
    ISSN: 1432-0789
    Keywords: Biopores ; Root growth ; Transpiration ; Simulations ; Mechanical impedance ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The use of vertical biopores by wheat (Triticum aestivum) seminal roots for easy access to the subsoil and the consequences for plant water supply and yield has been investigated by computer simulation. Parameters included were: biopore density and diameter, depth of cultivation and strength of the subsoil — all under a wide range of seasonal weather conditions. The model predicts that biopores add significantly to root penetration at depth, even at a density of 0.1% v/v of small, vertical pores, while 1.5% to 2.0% v/v can ensure maximum root penetration. When the growing season is shorter a larger number of biopores is needed to ensure timely root penetration to depth. With shallow tillage, biopores occur closer to the soil surface, and their importance is increased. Deeper root penetration invariably gives greater water uptake and transpiration, but may have a negative effect on grain yield, especially under the driest climatic conditions. An increase in early water use may result in less soil water being available during the grain-filling period. The effect of biopores on plant transpiration varies from year to year, depending on the amount of rain and its distribution in time, and on the amount of soil water stored at time of sowing.
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  • 54
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    Calcified tissue international 10 (1972), S. 82-90 
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Precipitation ; Kinetics ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La cinétique de la formation et de la transformation des précipités de phosphate de calcium, obtenus en mélangeant de volumes égaux de solutions à 6×10−3 M de calcium total et/ou phosphate total est étudiée à 25°C. Les solutions de phosphate sont préajustées à un pH de 7.4. Les changements de pH et de turbidité des solutions sont suivis simultanément en fonction du temps. Les précipités sont isolés à des intervalles de temps variables et caractérisés par diverses méthodes physico-chimiques. Initialement un précipité avec un rapport molaire Ca/P de 1.5, amorphe aux rayons X et en diffraction électronique, est formé. Le spectre IR indique la présence de PO 4 3− et de HPO 4 2− . Après une période métastable, on observe la précipitation d'un matériel cristallin dans ou sur la phase amorphe. Vingt quatre heures après préparation de l'échantillon les précipités présentent surtout les caractères du phosphate octocalcique.
    Abstract: Zusammenfassung Die Kinetik der Bildung und Transformation von Calciumphosphat-Niederschlägen wurde bei 25°C untersucht. Es wurden dazu gleiche Volumen von Lösungen gemischt, bei einer Konzentration von 6×10−3M totales Calcium und/oder totales Phosphat. Die Phosphatlösungen wurden zuerst auf pH 7,4 eingestellt. Veränderungen des pH und Trübung der Lösungen wurden gleichzeitig als eine Funktion der Zeit aufgezeichnet. Niederschläge wurden in verschiedenen Zeitintervallen isoliert und mit verschiedenen physiko-chemischen Methoden charakterisiert. Am Anfang wurde ein Niederschlag mit einem molaren Ca/P-Verhältnis von 1,5, im Röntgenbild und in der Elektronendiffraktion amorph, gebildet. Infrarotspektren deuteten die Anwesenheit von PO 4 3− - und HPO 4 2− -Ionen an. Nach einer metastabilen Periode erfolgte ein Niederschlag aus kristallinem Material innerhalb oder auf der amorphen Substanz. 24 Std nach der Herstellung der Proben zeigten die Niederschläge in der Hauptsache die Charakteristiken von Octocalciumphosphat.
    Notes: Abstract The kinetics of the formation and transformation of calcium phosphate precipitates obtained by mixing equal volumes of solutions, 6×10−3 M in total calcium and/or total phosphate was investigated at 25°. The phosphate solutions were preadjusted to pH 7.4. Changes of the pH and turbidity of the solutions were followed simultaneously as a function of time. Precipitates were isolated at various time intervals and characterized by different physicochemical methods. Initially a precipitate with a molar Ca/P ratio of 1.5, amorphous to X-ray and electron diffraction was formed. IR spectra indicated the presence of PO 4 3− and HPO 4 2− ions. After a period of metastability, precipitation of a crystalline material within or upon the amorphous matter occurred. Twenty four hours after sample preparation the precipitates showed mainly the characteristics of octacalcium phosphate.
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    Calcified tissue international 16 (1974), S. 145-152 
    ISSN: 1432-0827
    Keywords: EHDP ; Bone ; Chemistry ; Serum ; Rabbits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) on bone and serum chemistry were investigated in adult rabbits. EHDP was administered by subcutaneous injection at doses of 0.25, 2.5 and 10 mg/kg body weight/day for of 28 days. Blood samples were obtained weekly from each rabbit and serum levels of total calcium, ionized calcium, inorganic phosphate and alkaline phosphatase were determined. At the end of the treatment period all rabbits were sacrificed and the tibiae removed for chemical analysis and histological evaluation. The effect of EHDP administration on serum chemistry was both dose- and time-related. The highest of the three doses, 10 mg/kg/day, resulted in a time-related decrease in total serum calcium. This dose also caused a rapid but transient reduction in serum ionized calcium. The effect of EHDP on serum inorganic phosphate was biphasic. Administration of 2.5 mg/kg/day resulted in a time-related elevation in this parameter, whereas the 10 mg/kg/day dose resulted in a time-related hypophosphatemic response. There were no significant drug-related changes in tibial fat-free dry weight, ash weight, total calcium or total phosphorus values. However, administration of 2.5 and 10 mg/kg/day EHDP resulted in increased osteoid tissue as measured histologically. These results are compared with data from other EHDP studies, and discussed in relation to the maturity and growth-state of the experimental animals.
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    Calcified tissue international 23 (1977), S. 13-17 
    ISSN: 1432-0827
    Keywords: Dental calculus ; Glycopeptide ; Chemistry
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    Topics: Biology , Medicine , Physics
    Notes: Summary A method is described for the isolation and purification of a sulphated glycopeptide from human supragingival calculus. The compound was isolated after using EDTA treatment, 2 M CaCl2 extraction, proteolytic digestion, ethanol precipitation, and finally purified by DEAE cellulose chromatography. It migrated as a single component on cellulose acetate electrophoresis, and chemical and infrared spectral analysis showed the presence of covalently attached sulphate groups. The sulphated glycopeptide was distinguished from being a sulphated glycosaminoglycan.
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    Current genetics 12 (1987), S. 577-582 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Cell cycle ; Cyclic AMP ; G0 protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When the cyr1-1 cells of Saccharomyces cerevisiae, which require cyclic AMP (cAMP) for growth, were starved for cAMP, cell division was arrested at the G1 state of the mitotic cell cycle and the cells entered the resting state (G0) also observed in wild-type cells transferred to sulfur-free medium. The level of cAMP in wild-type cells decreased rapidly when the cells were starved for sulfur and subsequently increased following its addition. The cyr1-1 cells starved for cAMP preferentially synthesized nine G0 proteins. The synthesis of these G0 proteins in the sulfur-starved cells was repressed by the addition of cAMP. The RAS2 val19 or bcy1 cells, which produced an elevated level of cAMP or cAMP-independent protein kinase, did not synthesize the G0 proteins under the sulfur-starved condition. The results suggest that cAMP plays a role in the transition between the proliferating state and G0 state.
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  • 58
    ISSN: 1432-0983
    Keywords: 2-oxoglutarate dehydrogenase ; Saccharomyces cerevisiae ; rad52-mediated chromosome loss
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    Topics: Biology
    Notes: Summary Ogd1 mutants of Saccharomyces cerevisiae are deficient in mitochondrial 2-oxoglutarate dehydrogenase activity; they cannot grow on glycerol and produce an increased amount of organic acids during growth on glucose as substrate. Using gamma ray-induced rad52-mediated chromosome loss the ogd1 mutation can be assigned to chromosome IX. Tetrad analysis of crosses between ogd1 and other markers on chromosome IX revealed that the OGD1 gene maps on the left arm of this chromosome 1.9 cM from his5.
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  • 59
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Orotate phosphoribosyl transferase ; Nucleotide sequence-5-phosphoribosyl 1-pyrophosphate (5PRPP)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Orotate phosphoribosyl transferase (OPRTase) catalyses the transformation of orotate to OMP in the pyrimidine pathway. In the yeast Saccharomyces cerevisiae, the URA5 gene is known to encode this enzyme activity. In this paper we present the cloning and sequencing of a yeast gene, named URA10, encoding a second OPRTase enzyme. Comparison of the predicted amino acid sequences between URA5 and URA10 genes shows more than 75% similarity. These sequences have also been compared to those of Escherichia coli, Podospora anserina, Sordaria macrospora and Dictyostelium discoideum. Remarkable similarities in the primary structure of these proteins have been found. Gene disruption experiments revealed that URA10 gene expression is responsible for the leaky phenotype of a ura5 mutant. Assays of OPRTase activity in extracts from ura5 and ura10 mutants indicate that the URA10 product contributes only 20% of the total activity found in wild type cells.
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  • 60
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Site specific recombination ; 2 μ DNA plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The purpose of this work is to identify and quantitate in vivo 2 μ plasmid FLP-independent recombination in yeast, using a nonselective assay system for rapid detection of phenotypic expression of the recombination events. A tester plasmid was constructed such that in vivo recombination between 2 μ direct repeat sequences produces the resolution of the plasmid into two circular DNA molecules. This recombinational event is detected as a phenotypic shift from red to white colonies, due to the mitotic loss of the plasmid portion containing the yeast ADE8 gene in a recipient ade1 ade2 ade8 genetic background. In the absence of the 2 μ FLP recombinase and/or its target DNA sequence, recombination is not abolished but rather continues at a high frequency of about 17%. This suggests that the FLP-independent events are mediated by the chromosomally-encoded general homologous recombination system. We therefore conclude that the totality of 2 μ DNA recombination events occurring in FLP+ cells is the contribution of both FLP-mediated and FLP-independent events.
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  • 61
    ISSN: 1432-0983
    Keywords: Schizosaccharomyces pombe ; Saccharomyces cerevisiae ; Argininosuccinate lyase ; Gene cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A gene bank of Sau3A partially restricted Schizosaccharomyces pombe DNA in YEp13 was used to transform an arg4 mutant of Saccharomyces cerevisiae. One colony was recovered which contained the YEp13 plasmid bearing a large insert complementing the argininosuccinate lyase (ASL) mutation. As shown by restriction mapping and subcloning experiments, the DNA sequence required for complementation is localized on a 2 kb BamHI-BamHI fragment. The plasmid complemented several S. cerevisiae arg4 mutants of independent origin and a S. pombe arg7 mutant lacking ASL. Low but significant ASL activities were detected in crude extracts of these transformants. No complementation of the E. coli argH mutant was observed. Southern blot hybridizations showed that the insert originates from the S. pombe genome. No cross-hybridization was found between this sequence and S. cerevisiae DNA. It can be concluded that the cloned DNA fragment bears the S. pombe ARG7 gene coding for ASL.
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  • 62
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    Current genetics 14 (1988), S. 413-418 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Chromosome length polymorphisms ; FIGE ; OFAGE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Although Saccharomyces cerevisiae strains generally have similar chromosomal band patterns as revealed by pulsed field gel electrophoresis, individual bands often move slightly differently from one strain to the other. Surveying strains from our stock collection, we found that nearly all the bands of a certain pair of strains differed in their mobility. Some of these chromosome length polymorphisms segregated in a 2:2 ratio, indicating that they resulted from single structural alterations (i.e. additions or deletions). One of these was mapped on the right arm of chromosome 1. Others did not segrate in a simple 2:2 ratio. That is, there were progenies which had bands not present in either parent. We suggest that these new bands are the products of recombination between homologous chromosomes having two or more structural alterations.
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  • 63
    ISSN: 1432-0983
    Keywords: Secale cereale ; Triticum aestivum ; Ribosomal RNA genes ; Mitochondrial DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mitochondrial 18S and 5S ribosomal RNA (rRNA) genes of rye, plus a total of about 90 kilobase pairs of flanking DNA, have been cloned and maps of restriction enzyme cleavage sites have been constructed. Like their homologs from hexaploid wheat, the rye genes are closely linked and are part of a three-copy family of recombining repeats (the “18S/5S repeat”). The rye repeat probably also contains a mitochondrial tRNAfMet gene, which the wheat repeat is known to carry. However, despite the overall organizational similarity between the wheat and rye 18S/5S repeats in the immediate vicinity of their coding regions, extensive rearrangement of flanking sequences has taken place during evolutionary divergence of the two species. Our data provide additional support for an emerging picture of plant mitochondrial genomes as evolving much more rapidly in structure than in sequence.
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  • 64
    ISSN: 1432-0983
    Keywords: ARS ; Saccharomyces cerevisiae ; Schizosaccharomyces pombe ; Tetrahymena thermophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have isolated several Tetrahymena thermophila chromosomal DNA fragments which function as autonomously replicating sequences (ARS) in the heterologous Saccharomyces cerevisiae and Schizosaccharomyces pombe selection systems. The Tetrahymena ARS sequences were first isolated in S. cerevisiae and were derived from non-ribosomal micro- and macronuclear DNA. Sequence analysis of the ARS elements identified either perfect or close matches with the 11 by S. cerevisiae ARS core consensus sequence. Subcloning studies of two Tetrahymena ARS elements defined functional regions ranging in size from 50 to 300 bp. Testing of the ARS elements in S. pombe revealed that most of the T. thermophila inserts confer ARS function in both yeasts, at least in the sense of promoting a high transformation frequency to plasmids which contain them. However, the actual sequences responsible for ARS activity were not always identical in the two yeasts.
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  • 65
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Ribosomal protein genes ; CYH2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A diploid strain of the yeast Saccharomyces cerevisiae has been constructed that has one copy of the ribosomal protein gene CYH2 completely deleted and replaced with the TRP1 gene using the method of Rothstein (1983). There are only small differences in growth rate and no detectable difference in steady state level of CYH2 mRNA between the diploid that is heterozygous for the CYH2 deletion and the parent diploid with two normal copies of this gene. This suggests that the diploid must partially compensate for the loss of one CYH2 gene. Tetrad dissection shows that haploid spores lacking the CYH2 gene cannot germinate. The lethality of this deletion can be rescued by a CYH2 cDNA on a low copy vector. Haploids which lack the genomic copy of the CYH2 gene, but contain a plasmid copy of the CYH2 cDNA are able to grow normally. These CYH2 deleted yeast haploids should be useful to analyze mutationally altered CYH2 genes and genes homologous to CYH2 from other organisms without interference from a genomic copy.
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  • 66
    ISSN: 1432-0983
    Keywords: Yeast ; Gene regulation ; Saccharomyces cerevisiae ; PDCI promoter
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    Notes: Summary A 870 by promoter fragment of the PDC1 gene that includes the carbon source dependent regulatory regions was investigated using 5′ and 3′ promoter deletions. The results indicate that glucose and ethanol regulation of PDC1 transcription are independently controlled by distinct cis-acting regions. The consensus sequence AAATCGATA may play a role in this regulation, while the sequence (ATCA)AACCT may be important in transcription initiation.
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  • 67
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mutants ; Farnesyl diphosphate synthetase ; Ergosterol
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    Topics: Biology
    Notes: Summary Two yeast mutant strains auxotrophic for ergosterol and blocked in farnesyl diphosphate synthetase (EC 2.5.1.1) were isolated. Genetic analysis has shown that these mutant strains carry additional mutations in the ergosterol pathway besides erg20-1 and erg20-2 which affect FPP synthetase. The novel feature of these mutants is their ability to excrete prenyl alcohols (farnesol and geraniol). As geraniol is toxic for yeast cells, the above leaky mutations in FPP synthetase have to be associated with others in the sterol pathway, in order to slow down geraniol synthesis.
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  • 68
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Vector ; Glyphosate resistance ; Transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The E. coli aroA gene was inserted between yeast promoter and terminator sequences in different shuttle expression plasmids and found to confer enhanced EPSP synthase activity as well as resistance to glyphosate toxicity. Subsequently, a transformation system using these newly constructed vectors in yeast was characterized. The efficiency of the glyphosate resistance marker for transformation and selection with plasmid pHR6/20-1 in S. cerevisiae laboratory strain SHY2 was found to be relatively high when compared with selection for LEU2 prototrophy. The fate of the recombinant plasmid pHR6/20-1 in the transformants, the preservation of the aroA E. coli DNA fragment in yeast, mitotic stability, EPSP synthase activity, and growth on glyphosate-containing medium have been investigated. As this plasmid also allows direct selection for glyphosate resistant transformants on rich media, the glyphosate resistance marker was used for transforming both S. cerevisiae laboratory strain SHY2 and brewer's yeast strains S. cerevisiae var. “uvarum” BHS5 and BHS2. In all cases, the vector pHR6/20-1 was maintained as an autonomously replicating plasmid. The resistance marker is, therefore, suitable for transforming genetically unlabeled S. cerevisiae laboratory, wild, and industrial yeast strains.
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  • 69
    ISSN: 1432-0983
    Keywords: Glucose oxidase ; Aspergillus ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report the cloning of the Aspergillus niger glucose oxidase gene and its use to elevate glucose oxidase productivity in A. niger by increasing the gene dosage. In addition, the gene has been introduced into A. nidulans where it provides the novel capacity to produce glucose oxidase. A plasmid, in which DNA encoding the mature form of glucose oxidase was preceded by a Saccharomyces cerevisiae secretion signal, effected high-level production of extracellular glucose oxidase in this yeast.
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  • 70
    ISSN: 1432-0983
    Keywords: Schizosaccharomyces pombe ; Saccharomyces cerevisiae ; Argininosuccinate lyase ; Sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The complete nucleotide sequence of the ARG7 gene, coding for argininosuccinate lyase (EC 4.3.2.1), in the fission yeast (Schizosaccharomyces pombe) has been determined. It consists of an open reading frame of 461 codons. The deduced protein has a molecular weight of 51 200 Da. The gene is devoid of introns which is confirmed by the fact that it is expressed in Escherichia coli after spontaneous insertion of a bacterial sequence probably bearing a prokaryotic promoter. A perfect “TATA” box is found at-72 and the major transcription initiation site in Saccharomyces cerevisiae is located at-11 as shown by primer extension experiments. Comparison of the S. pombe lyase with related proteins from other organisms reveals an important degree of conservation except in the carboxyterminal part of the polypeptide. Additionally, a deletion removing 66 amino acids of the carboxy terminus yields an enzyme exhibiting some biological activity. A unique 1500 b transcript was found in S. cerevisiae when the intact gene was present, but the deleted version of the gene gave rise to at least three transcripts of 1800, 2800 and 3900 b.
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  • 71
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Chromosome V ; Ty elements ; tRNA genes ; Transposition hot-spots ; Yeast polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ty4 is a novel transposable element in the yeast, Saccharomyces cerevisiae, which is present in only a few copies in the genome (Stucka et al. 1989). In strain C836 one of the three copies (Ty4-90) is contained in cosmid clone c90, where it resides on chromosome V. Analysis of this region reveals a “hot-spot” of transposition: in addition to Ty4-90, the locus contains a complete Ty3 element and seven singular delta, sigma and tau elements. Three tRNA genes (for His, Lys, and Ile) are located in this region, and these are closely associated with one or the other of the elements, a phenomenon commonly observed in yeast. A comparison of c90 with corresponding regions from other strains shows that the locus is highly polymorphic and that this polymorphism is explicitly associated with Ty transposition and recombination events.
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  • 72
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Pyrimidine salvage pathway ; Semi-dominant mutants ; FUR1 ; Uracil phosphoribosyl transferase ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Saccharomyces cerevisiae, the protein encoded by the FUR1 gene is absolutely required for the expression of uracil phosphoribosyl transferase activity. The occurrence of semi-dominant mutations for 5-fluorouracil-(5FU)-resistance at this locus led us to clone and sequence the semi-dominant fur 1–5 allele. A single point mutation, resulting in the substitution of arginine 134 for serine, is responsible for this mutant phenotype. The fur 1–5 allele is transcribed and expressed at the same level as the wild-type allele. But, in contrast with the wild-type, the UPR Tase activity of the fur 1–5 mutant strain is stimulated in vitro by UTP and does not, therefore, correspond to a loss of feedback of UPR Tase activity. We found that uracil, as a free base, induces a significative increase in transcription and UPR Tase activity in a wild-type strain as well as in uracil-overproducing mutants which principally explains the high efficiency of the pyrimidine salvage pathway in S. cerevisiae.
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  • 73
    ISSN: 1432-0983
    Keywords: Gene cloning ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have carried out experiments aimed at explaining the observed variations in transformation frequencies when Saccharomyces cerevisiae or Saccharomyces carlbergensis are transformed with chimeric plasmids that contain one of 4 possible EcoRI fragments of the yeast 2-μm circle. These plasmids fall into 2 classes when used to transform 2 different yeast his3 auxotrophs, one (strain LL20) harbours indigenous 2-μm circle, and the other (strain YF233) is devoid of this plasmid. Hybrid plasmids containing either the 2.4 mega-dalton (mD) R-form EcoRI fragment (pYF88) or the l.4 mD L-form EcoRI fragment (pYF177) of 2-μm circle transform either of the two hosts at a high frequency (50,000 colonies per Mg in LL20 and 10,000 colonies per μg in YF233). Hybrid plasmids containing the 1.5 mD R-form EcoRI fragment (pYF87) or the 2.5 mD L-form EcoRI fragment (pYF178) of the 2-μm circle transform LL20 at a reduced frequency (6,000–16,000 colonies per μg) and YF233 at extremely low frequencies (1–5 colonies per μg). All plasmids retrieved from strain YF233 that had been transformed with pYF88 or pYF177 were identical to the original transforming plasmid. Of the plasmids retrieved from strain LL20 that had been transformed with pYF87 and pYF178, approximately half had acquired an extra copy of the 2-μm circle. Of the plasmids retrieved from strain LL20 that had been transformed with pYF88 and pYF177, an average of only approximately 13% had acquired an extra copy of 2-μm circle. Taken together, these observations indicate that the transformation of yeast by a plasmid lacking the ability to replicate (pYF87 and pYF1780) occurs by the recombinational acquisition of 1 copy of the host 2-μm circle, which serves to supply the incoming plasmid with missing essential sequences. A comparison of 2-μm circle DNA fragments carried by pYF88 and pYF177 indicates that the region of 2-μm circle required for high frequency transformation is a 1.2 mD segment that is common to the 2.4 mD R-form and 1.4 ml) L-form EcoRI fragments. This region extends from the EcoRI cut site adjacent to the PstI site, through to the end of the inverted repeat. However, the inverted repeat sequence alone is not sufficient to bestow high frequency transformation of yeast.
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  • 74
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    Current genetics 18 (1990), S. 401-403 
    ISSN: 1432-0983
    Keywords: Baking yeast ; Saccharomyces cerevisiae ; Dough leavening ; Benomyl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To investigate the leavening ability of yeast in dough, chromosome loss was induced by benomyl treatment in YOY1037, a diploid between a baking strain and a laboratory strain, and its effect on the leavening ability was studied. When benomyl-treated cells were spread on plates with a dye indicator for ploidy, about 20% of the visible colonies were stained dark blue or dark purple; the rest stained pale blue, similar to the diploid YOY1037. Strains showing the MATα phenotype, and non-galactose fermenting strains, apparently having lost particular chromosomes, were observed only in those with darkcoloured colonies. Strains with dark-coloured colonies showed a wider range of leavening ability than did those with pale-coloured colonies.
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  • 75
    ISSN: 1432-0983
    Keywords: Xylitol dehydrogenase gene ; Pichia stipitis ; Saccharomyces cerevisiae ; Xylose utilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A P. stipitis cDNA library in λgt11 was screened using antisera against P. stipitis xylose reductase and xylitol dehydrogenase, respectively. The resulting cDNA clones served as probes for screening a P. stipitis genomic library. The genomic XYL2 gene was isolated and the nucleotide sequence of the 1089 bp structural gene, and of adjacent non-coding regions, was determined. The XYL2 open-reading frame codes for a protein of 363 amino acids with a predicted molecular mass of 38.5 kDa. The XYL2 gene is actively expressed in S. cerevisiae transformants. S. cerevisiae cells transformed with a plasmid, pRD1, containing both the xylose reductase gene (XYL1) and the xylitol dehydrogenase gene (XYL2), were able to grow on xylose as a sole carbon source. In contrast to aerobic glucose metabolism, S. cerevisiae XYL1-XYL2 transformants utilize xylose almost entirely oxidatively.
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  • 76
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Centromere flanking sequences ; tRNA modification enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transcriptional analysis of the region flanking the left boundary of the centromere of chromosome VI revealed the presence of a gene immediately adjacent to CEN6. The transcription of the gene is directed toward the centromere, and nucleotide sequence analysis showed that the coding region terminates only 50 bp away from CEN6. Our results extend to chromosome VI the observation that centromere-flanking regions of S. cerevisiae are transcriptionally active. Disruption of the coding region of the gene showed that its product, whilst not essential for cell viability, is important for normal cell growth. The gene has been termed DEG1 (DEpressed Growth rate). Comparison of the deduced amino acid sequence of DEG1 with a protein sequence databank revealed homology with the enzyme tRNA pseudouridine synthase I of E. coli.
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  • 77
    ISSN: 1432-0975
    Keywords: Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry.
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  • 78
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    Current genetics 1 (1979), S. 63-74 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Translation ; Coordinate regulation ; Electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The products of protein synthesis from exponential phase cultures of Saccharomyces cerevisiae grown at 23 °C or at 36 °C appear to be essentially identical. However, yeast cells respond to a shift in culture temperature from 23 °C to 36 °C with the rapid de novo synthesis of a polypeptide species of molecular weight 100,000. Within 60–90 min after the shift this polypeptide represents approximately 2.5% of the total cellular protein, a 5–10 fold increase over the preshift level. The level of this polypeptide then decreases with continued growth of the cells at 36 °C. Analyses by SDS-polyacrylamide gel electrophoresis of polypeptides obtained from cells pulse labeled with [35S]methionine demonstrate that following a temperature shift from 23 °C to 36 °C the synthetic rate of the 100,000 molecular weight polypeptide (as well as a number of other polypeptide species) increases to a level at least 10 fold higher than that observed prior to the shift. A concomittant decrease is observed in the synthesis of a large number of polypeptide species which were actively synthesized before the shift. Maximum changes in synthetic rates are observed 20–30 min after the shift and preshift synthetic patterns are regained within 60–90 min. Synthetic changes of the same magnitude and time course can be produced by short (20–30 min) exposures to 36 °C implicating a heat shock response. Several of the transiently induced polypeptides, including the 100,000 molecular weight species, show an affinity for DNA as determined by DNA-cellulose chromatography.
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  • 79
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    Current genetics 10 (1986), S. 943-945 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; α-factor ; Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When Mat a cells are treated with α-factor prior to being protoplasted and fused, the frequency of karyogamy is higher than in unarrested controls.
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  • 80
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    Current genetics 10 (1985), S. 179-185 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Resistance ; Mercury ; Tyrosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary From a cross of two strains ofSaccharomyces cerevisiae, both of which had the same (wild type or normal) level of resistance to inorganic mercury, segregants having three distinguishable resistance levels, normal, sensitive and semi-sensitive, were obtained. Genetic analyses of the parents and the progeny indicated that the levels of inorganic mercury sensitivity were determined by three distinct loci,HGS1, HGS2 andMSM1. The recessive allele of theHGS1 locus,hgsl-1, and the codominant allele of theHGS2 locus,HGS2-1, were necessary for the sensitive phenotypes, and alleles in theMSM1 locus,MSMI-1 andmsml-2, were responsible for the different sensitivity levels. In short, the strains of genotypeshgs1-1 HGS2-1 msml-2 andhgsl-1 HGS2-1 MSMI-1 were sensitive and semi-sensitive, respectively, while the strains of all other genotypes were normal. Although thehgs1-1 allele was identified as thearo7-1 mutation which confers deficiency of tyrosine and phenylalanine, mutations such asaro1B (deficiency of tyrosine, phenylalanine and tryptophan) andtyr1 (deficiency of tyrosine) had similar effects asaro7-1 on inorganic mercury sensitivity. From these results we conclude that theHGS2-1 allele causes inorganic mercury sensitivity when the cells are defective in the tyrosine biosynthesis. In fact, addition of tyrosine to the growth medium containing inorganic mercury resulted in increase of colony forming ability of the sensitive strains.
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  • 81
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    Current genetics 10 (1986), S. 665-670 
    ISSN: 1432-0983
    Keywords: Multiple drug resistance ; Genetic mapping ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the yeast Saccharomyces cerevisiae, two nuclear pleiotropic drug resistance mutations pdr3-1 (former designation muc PR) and pdr3-2 (former designation DRI9/T7) have been selected as resistant to mucidin and as resistant to chloramphenicol plus cycloheximide, respectively. The pdr3 mutations were found not to affect the plasma membrane ATPase activity measured in a crude membrane fraction. Meiotic mapping using strains with standard genetic markers revealed that mutation pdr3-1 is centromere linked on the left arm of chromosome II at a distance of 5.9 ± 3.3 cM from its centromere and 11.6 ± 3.1 cM from the marker pet9. The centromere linked pdr3-2 mutation exhibited also genetic linkage to pet9 with a map distance of 9.8 ± 3.2 cM. These results indicate that pdr3-1 and pdr3-2 are alleles of the same pleiotropic drug resistance locus PDR3 which is involved in the control of the plasma membrane permeability in yeast.
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  • 82
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    Current genetics 10 (1986), S. 657-664 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Amino acid biosynthesis ; General control ; GCD-genes ; GCN-genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mutant strains, resistant against the amino acid analogues 5-methyltryptophan, 5-fluorotryptophan and canavanine were isolated, starting with a trp2 leaky auxotrophic strain. Of 10 such strains, only four turned out to be of the “general control derepressed” (gcd) mutant type. Three other isolates were shown to be defective in the general amino acid permease system, while the remaining three strains displayed low spore viability and were not further investigated. Complementation tests amongst the four new gcd-mutant strains, including strain RH558 gcd2-1 isolated earlier, yielded five complementation groups: GCD2, GCD3, GCD4, GCD5, and GCD6. All mutant strains showed a dual phenotype, which was not separable by wild type backcrosses: “constitutive derepression” and “slow growth”. Epistatis of all gcd mutations over gcn1-1, gcn2-1 and gcn3-1 was found with respect to both phenotypes, except for gcd5-1, which was lethal in these combinations. On the other hand gcn4-101 was found to be epistatic over all gcd mutations, but only with respect to the “constitutive derepression” phenotype, and not to “slow growth”; again the combination with gcd5-1 was lethal. Mutation gcd2-1 was mapped on chromosome VII, 50 cM from leu1 and 22 cM from ade6. A new model is discussed, in which GCD-genes are involved in the amino acid uptake into the vacuoles.
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  • 83
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Inducible repair ; Plasmid transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Many reports show that resistance of Saccharomyces cerevisiae to a large UV dose can be enhanced by pre-induction with a smaller one given some hours before. This work tests if such increased cell survival is associated with increased DNA repair on UV damaged plasmid transformed into yeast. There was no change in transformation efficiency of UV-damaged plasmid DNA under conditions where RAD cell survival increased 5-fold, and where rad1-1 and rad6-1 survival increased 2-fold. It is concluded that DNA repair activity involving the RAD6 and RAD3 pathways is either not inducible or is unable to work on plasmid DNA. It is suggested that the enhancement of cellular survival detected may be based on changes in cell-cycle behaviour which permit cells generally proficient in repair a greater chance to recover.
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  • 84
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; 2 μ plasmids ; Plasmid free segregants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The maximum specific growth rates (μmax) of 2 μ-plasmid-free ([cir°]) segregants of three haploid and one diploid strain of Saccharomyces cerevisiae have been determined and compared with the μmax of their 2 μ-plasmid-containing ([cir +]) progenitors. Two classes of [cir°] strains have been examined: those induced by transformation with a 2 μ-based recombinant plasmid according to the method of Dobson et al. (1980) and those isolated as spontaneous [cir°] segregants from glucose-limited continuous cultures. The μmax of the spontaneous [cir°] segregants was not found to differ significantly from that of their [cir +] parents. In all cases, however, the induced [cir°] strains had a μmax which was significantly less than that of their [cir +] counterparts. This effect was particularly marked in the case of the diploid strain where a 34% reduction in μmax was observed. The implications of these results are discussed in terms of the effect of the transformation process on host yeast cells.
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  • 85
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Minor tRNAs ; Codon usage ; Transposable elements ; Delta ; Tau
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During characterization of the whole tRNA(Glu) family from the yeast, Saccharomyces cerevisiae, we isolated one cosmid clone bearing a tRNA(Glu) gene copy that is deviant from the major tRNA(Glu3) gene members in only five positions. This divergent tRNA(Glu) is a minor species and is represented by a single gene copy. One of the nucleotide exchanges concerns the anticodon which is modified from T-T-C in the tRNA(Glu3) gene to C-T-C which implies that this tRNA serves the codon triplet G-A-G. Two other minor yeast tRNA species have been reported which appear to be particularly designed for the translation of those codons that have a G in its third (Wobble) position. The low abundance of such minor tRNA species correlates positively to the low occurrence of most of the N-N-G codons in yeast. Furthermore, the GAGtRNA(Glu) locus represents another case of the general phenomenon in which the majority of the tRNA genes in yeast are associated with one or several transposable elements forming complex patterns. In this particular case, divergent segments of delta and tau are present in the 5′ flanking region of the tRNA gene and arranged in a novel configuration. The sequence data lend support to the view that tau is not an evolutionary young element as was earlier anticipated.
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  • 86
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    Current genetics 16 (1989), S. 315-321 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Antisuppressor ; ADE3 ; Translation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mutations in a known yeast gene, ADE3, were shown to act as an antisuppressor, reducing the efficiency of the omnipotent suppressor, sup45-2. The ADE3 locus encodes the trifunctional enzyme C1-tetrahydrofolate synthase, which is required for the biosynthesis of purines, thymidylate, methionine, histidine, pantothenic acid and formylmethionyl-tRNAfmet. The role of this enzyme in translational fidelity had not previously been suspected.
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  • 87
    ISSN: 1432-0983
    Keywords: Yeast ; Saccharomyces cerevisiae ; Nonsense suppression ; Omnipotent suppressors ; Gene mapping
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Ten dominant omnipotent suppressors of Saccharomyces cerevisiae, which were previously shown to be different from SUP46, have been examined. Nine are mapped in a region between lys5 and cyh2 on the left arm of chromosome VII. These suppressors, like SUP46, manifest sensitivity to increased temperature and the antibiotics paromomycin and hygromycin B. In addition, they have an identical action spectrum. These results strongly suggest that they are allelic to each other and they are designated SUP138. The tenth is mapped to a position between his1 and arg6 on the right arm of chromosome V. This suppressor, named SUP139, does not manifest temperature sensitivity nor antibiotic sensitivity. SUP139 and SUP138, which are clearly distinguished by means of action spectrum, act on much fewer nonsense mutations than SUP46. It is now clear that dominant omnipotent suppressors arising at a single locus are homogeneous and that their efficiency is locus-dependent. The order of efficiency is SUP46〉SUP138〉SUP139.
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  • 88
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    Current genetics 13 (1988), S. 21-23 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Transformation ; Plasmid ; Colony ; Polyethylene glycol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A rapid and simple yeast transformation procedure has been developed using colonies on agar plates. Saccharomyces cerevisiae SHY3 cells were picked up from colonies on YPD plates grown freshly or stored at 4 °C and incubated with M13RK9-T DNA at 30 °C for 1–2 h in a solution of Li+, Ca2+, Mg2+, triacetin and polyethylene glycol. About 3,500 transformants were obtained per µg of double stranded M13RK9-T DNA. Unlike the existing spheroplast techniques, single stranded M13RK9-T DNA transformed intact cells below one-hundredth frequency of the duplex form.
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  • 89
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Plant mitochondrial DNA ; Ribosomal genes ; Sequence rearrangements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequence of the wheat mitochondrial 26S ribosomal RNA gene and flanking regions was determined and compared with mitochondrial 26S rRNA genes from maize and Oenothera. All three genes exhibit a high degree of homology except within two variable regions. When the plant mitochondrial 26S rRNA genes are compared with Escherichia coli 23S rRNA and chloroplast 23S and 4.5S rRNA genes, a third variable region is apparent close to the 3′ end of the gene. The 5′ and 3′ ends of the wheat mitochondrial gene were determined by S1 nuclease mapping. Computer analysis of the wheat mitochondrial gene revealed several small sequences present either in the 5′ region of the 26S rRNA gene or in the 18S rRNA gene.
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  • 90
    ISSN: 1432-0983
    Keywords: Aspergillus terreus clonotheque ; Saccharomyces cerevisiae ; Homologous integration ; 2 μ circledirected chromosome destabilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A genome clonotheque consisting of 25- to 40-kb Sau3A1 fragments of Aspergillus terreus DNA was constructed in the episomal cosmid vector pES33 containing the yeastARG4 gene. From the 475 transformants of cir° yeast strain ESH-0, 23 stable Arg + transformants were independently selected. Genetic and Southern analysis of these stable transformants showed that 39% arose as a result of recombination between cloned A. terreus DNA sequences and yeast chromosome XII. The recombination events most likely occurred in the regions of homology within the rDNA clusters of A. terreus and Saccharomyces cerevisiae.
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  • 91
    ISSN: 1432-0983
    Keywords: Yeast ; Repair ; Complementation ; Saccharomyces cerevisiae ; Schizosaccharomyces pombe ; Gene cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two Saccharomyces cerevisiae genes necessary for excision repair of UV damage in DNA, RAD1 and RAD2, were introduced individually, on a yeast shuttle vector, into seven Schizosaccharomyces pombe mutants — rads1, 2, 5, 13, 15,16 and 17. The presence of the cloned RAD1 gene did not affect survival of any of the S. pombe mutants. The RAD2 gene increased survival of S. pombe rad13 to near the wild-type level after UV irradiation and had no effect on any of the other mutants tested. S. pombe rad13 mutants are somewhat defective in removal of pyrimidine dimers so complementation by the S. cerevisiae RAD2 gene suggests that the genes may code for equivalent proteins in the two yeasts.
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  • 92
    ISSN: 1432-0983
    Keywords: DNA transformation ; Saccharomyces cerevisiae ; Site-specific recombination ; 2μ DNA plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The 2μ DNA plasmid of the yeast Saccharomyces cerevisiae does not confer any known selectable phenotype to the host cell carrying it. Selection of cells transformed with purified 2μ DNA therefore cannot be achieved, and the intracellular presence of 2μ can only be assessed by molecular analysis of the DNA complement. In addition, 2μ alone does not replicate in bacterial hosts, thus rendering its amplification by conventional methods impossible. We have isolated a shuttle plasmid, pBH-2L, generated by in vivo sites-pecific recombination between the endogenous 2μ DNA plasmid and pRL, a pBR322 derivative containing the yeast LEU2 gene and one 2μ repeat sequence associated with the origin of replication. This new shuttle plasmid has the property, when transformed into yeast, of undergoing site-specific recombinational resolution between its two direct repeat sequences. This releases 2μ plasmid and pRL as individual molecules. The latter can undergo progressive mitotic loss during growth in nonselective medium, ultimately leaving leucine auxotrophic transformants that contain only 2μ DNA plasmid. This system can be utilized to introduce 2μ DNA alone into cells lacking it, thereby providing a novel means to study the biology and the molecular genetics of the plasmid and its potential practical applications as a vector.
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  • 93
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    Current genetics 15 (1989), S. 113-120 
    ISSN: 1432-0983
    Keywords: Calmodulin mutant ; Nuclear division ; Chromosome stability ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The coding region of a yeast calmodulin gene was fused to a galactose-inducible GAL1 promoter, and a conditional-lethal mutant of Saccharomyces cerevisiae, in which the expression of calmodulin was regulated by galactose, was constructed. The mutant grew normally in galactose medium, but in glucose medium, in which the promoter was repressed, it ceased growing after 12–15 h. The growth arrest was associated with a decrease in intracellular calmodulin levels: after 12h, no intracellular calmodulin protein was detectable. Analysis of the terminal phenotype showed that when the cell stopped growing, it had a bud, a nucleus after S-phase and a short mitotic spindle. Thus, the defect was mainly in nuclear division. Bud growth was partially inhibited in these cells: 27% of the cells stopped growing with a small bud. Furthermore, calmodulin-deficient cells showed elevated rates of chromosome loss, possibly as the result of a defect in the precise segregation of chromosomes.
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  • 94
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    Current genetics 15 (1989), S. 235-237 
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mitochondrial DNA ; Method of extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A rapid method for the extraction of yeast mitochondrial DNA (mtDNA) is described. In comparison with previous methods, it simplifies several steps, does not require either the isolation of mitochondria or phenol treatment and is less time consuming. This protocol gives a high yield of pure mtDNA (50–120 μg from a 100-ml culture), which can be directly used in various molecular applications: restriction enzyme digestion, electrophoresis, blotting, labeling, cloning and sequencing.
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  • 95
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mutagen hyperresistance ; Southern, Northern analysis ; Gene transplacement ; Transposon mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genes SNQ and SFA confer hyperresistance to 4-NQO and FA when present on a multi-copy plasmid in yeast. Both are non-essential genes since transplacement of SNQ by a disrupted snq-0::LEU2 yielded stable and viable haploid integrants. Southern analysis revealed that SNQ and SFA are single-loci genes, and OFAGE analysis showed that they are located on chromosome XIII and IV, respectively. Northern blot analysis of SNQ and SFA revealed poly(A)+ RNA transcripts of 2 kb and 1.7 kb, respectively. Nuclease S 1 mapping showed SNQ to have a coding region of 1.6 kb and SFA, one of 1.3 kb. The 5′ coding regions were determined for both genes, while the 3′ end could only be determined for gene SNQ. Both genes do not appear to contain introns. The SFA locus was also mapped by transposon mutagenesis. Tn10-LUK integrants disrupted the SFA gene function at sites that were determined by subcloning to lie within the SFA transcription unit.
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  • 96
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; SKI3 ; SKI5 ; M1 dsRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have identified a mutant strain of the yeast Saccharomyces cerevisiae which overproduces killer toxin. This strain contains a single mutation which fails to complement defects in both the SKI3 and SKI5 genes, while a cloned copy of this gene complements both the ski3 and ski5 defects. The level of secreted toxin from a cDNA based plasmid is not increased in a ski3 strain, showing that the overproduction phenotype is dependent upon an increased level of M1 dsRNA.
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  • 97
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Psoralen photoaddition ; Interstrand cross-link ; Repair deficiency ; Genotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two different UVA irradiation systems were initially biologically calibrated with two haploid yeast strains proficient and deficient, respectively, in nucleotide excision repair. The number of DNA lesions introduced into the cell's genome by the photoactivated bifunctional furocoumarin 8-MOP was then calculated by means of the applied UVA exposure doses. At LD37 the repair-proficient wild type had about 14 ICL and 34 furan-side monoadducts in its DNA, while doubly blocked repair mutant rad3-12 pso1-1 had 2 ICL and 3 monoadducts. Locus-specific reversion of lys1-1 followed two-hit kinetics in the repair-proficient wild type and one-hit kinetics in an excision-deficient rad2-20 mutant, as would be expected if ICL was the main type of mutagenic lesion in the wild type and monoadducts the main mutagenic lesion type in the excision-deficient strain. Quantitative comparison of 8-MOP + UVA-induced ICL with those induced by bifunctional mustard revealed the former to have a much higher genotoxicity.
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  • 98
    ISSN: 1432-0983
    Keywords: Mutagen hyper-resistance ; Nitrogen mustard ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A screening of haploid yeast strains for enhanced resistance to nitrogen mustard (HN2) yielded a recessive mutant allele, hnm1, that conferred hyper-resistance (HYR) to HN2. Diploids, homo- or heterozygous for the HNM1 locus, exhibit normal wild-type like resistance while homozygosity for hnm1 leads to the phenotype HYR to HN2. The hnm1 mutation could be found in yeast strains proficient or deficient in different DNA repair systems. In these mostly HN2-sensitive haploid repair-deficient mutants, hnm1 acted as a partial suppressor of HN2 sensitivity. All isolated recessive mutations conferring hyper-resistance belonged to a single complementations group. The HYR to HN2 phenotype was maximally expressed in growing cells and was associated with reduced mutability by HN2. HNM1 most probably controls uptake of HN2 which would be impaired in the hnm1 mutants.
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  • 99
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; G418 resistance ; Gene cartridges ; Heterologous Gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Coding sequence cartridges for aminoglycoside phosphotransferase (APT) were isolated from bacterial transposon Tn903. When incorporated into a heterologous gene construction utilising the PGK1 promoter and terminator, the heterologous APT gene provided a G418-resistance determinant that functioned efficiently as a dominant marker for yeast in both multiple- and single-copy. Transformant colonies on selective medium appeared rapidly, within 36–48 h, and growth rate of the transformed cells was normal. A simple and highly sensitive radiolabelling assay for APT enzyme activity was developed for use with crude cell protein extracts. Enzyme activity units were equated to the amount of APT protein present in the cells, and the APT protein was shown to be stable in yeast. Heterologous APT expression was 130-fold reduced compared with homologous PGK1. This resulted from an estimated two-fold decrease in mRNA level and a 65-fold decrease in translation efficiency. The latter was unaffected by AUG sequence context change, but corresponded with a high frequency of minor codons in the APT-coding sequence. APT can be used as a semi-quantitative reporter of gene expression, whose useful features are in vivo detection via the G418-resistance phenotype and powerful cell-free assay.
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  • 100
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    Current genetics 2 (1980), S. 115-120 
    ISSN: 1432-0983
    Keywords: Galactose fermentation ; Saccharomyces cerevisiae ; Regulatory mutant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A novel type of regulatory mutation for galactose metabolism in Saccharomyces cerevisiae is described. The mutation named gal11 was recessive, non-allelic to GAL4, GAL80, GAL2, or GAL3, and unlinked to the gene cluster of GAL1, GAL10, and GAL7. It caused a ‘coordinate’ reduction of galactokinase, galactose-1-P uridylyl transferase, and UDP-glucose 4-epimerase by a factor of more than 5, rendering the mutant cells galactose-nonfermenting. The effect of the mutation was manifested not only in cells grown on galactose but also in cells constitutively synthesizing the galactose-metabolizing enzymes.
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