Effects of temperature and tissue age on gel strength and composition of agar from Gracilaria tikvahiae (Rhodophyceae)

1984 ◽  
Vol 62 (8) ◽  
pp. 1665-1670 ◽  
Author(s):  
James S. Craigie ◽  
Zong C. Wen
Keyword(s):  
Gel Strength ◽  
Wild Type ◽  
Gracilaria Tikvahiae ◽  
Morphological Mutants ◽  
Wild Type Clone ◽  
Effects Of Temperature ◽  
Lateral Branches ◽  
Increasing Temperature ◽  
Strong Inverse Relationship ◽  
Galactose Content

Agars were prepared from a wild type and two morphological mutants of Gracilaria tikvahiae grown at 17, 22, and 27 °C, and from apical segments, main axis segments, and lateral branches of the wild type clone MP-2 grown at 17 and 27 °C. The yield of native agar was 9–11% from the young parts and 19–23% from the most mature parts of the MP-2 thallus. The gel strengths of alkali-modified agars showed a strong inverse relationship with increasing temperature of growth in each of the three clones examined. The modified agar produced from plants grown at high temperature contained more sulfate and less 3,6-anhydro-L-galactose than agars produced at lower temperatures. The increase in 4-O-methyl-L-galactose content of the agars as the growth temperature increased was especially marked. Dissection experiments on clone MP-2 showed that agar with the maximum gel strength and 3,6-anhydro-L-galactose content and the minimum sulfate and 4-O-methyl-L-galactose content was produced at low temperature by apical segments and young lateral branches. The poorest quality agar was prepared from mature segments of the thallus, especially those grown at high temperatures. Agars prepared from mature parts of the thallus were greatly enriched in 4-O-methyl-L-galactose, which reached 8.8% of the weight of the agar at 27 °C. Changes in 6-O-methyl-D-galactose were smaller, but this sugar was lowest in agar prepared from young tissues of plants grown at 17 °C.

Growth experiments on morphological mutants of Gracilaria tikvahiae (Rhodophyceae)

1983 ◽  
Vol 61 (6) ◽  
pp. 1654-1659 ◽  
Author(s):  
Mohsin U. Patwary ◽  
John P. van der Meer
Keyword(s):  
Growth Rate ◽  
High Density ◽  
Low Density ◽  
Wild Type ◽  
Gracilaria Tikvahiae ◽  
Morphological Mutants ◽  
Growth Experiments

The growth of morphological mutants of Gracilaria tikvahiae was compared with that of wild-type clones in tanks of flowing seawater in a greenhouse. At low density four mutants grew faster than a related wild type, and two, MP-40 and MP-44, grew faster than any of the wild clones tested. Of the mutants, MP-40 consistently had the fastest growth rate at low density. At high density MP-40 and MP-44 again grew faster than wild type; however, MP-44 had the faster growth rate and gave the higher yields. Both of these mutants removed nitrogen (NH4+) from seawater faster than the wild types and both proved to be much more epiphyte resistant, with MP-40 scoring highest for both of these characteristics.

Genetics of Gracilaria tikvahiae (Rhodophyceae). VIII. Phenotypic and genetic characterization of some selected morphological mutants

1982 ◽  
Vol 60 (12) ◽  
pp. 2556-2564 ◽  
Author(s):  
Mohsin U. Patwary ◽  
John P. van der Meer
Keyword(s):  
Wild Type ◽  
Initial Attempt ◽  
Gracilaria Tikvahiae ◽  
Induced Mutants ◽  
Morphological Mutants ◽  
Phenotypic And Genetic Characterization ◽  
Growth Habits ◽  
Selection Of ◽  
Better Than

Morphological mutants of the marine red alga Gracilaria tikvahiae have been isolated in an initial attempt to develop improved strains for mariculture by selection of plants with altered growth habits. Both spontaneous and ethylmethanesulphonate-induced mutants were collected for this study. The phenotypes of the mutants range from plants with extremely fine, highly branched fronds to plants with thick puffy fronds. Among 10 mutants selected for more detailed study, 9 have distinctly different phenotypes. Genetic results identify nine mutant cistrons corresponding to the nine phenotypes. All the phenotypes are transmitted as single, mostly recessive, Mendelian mutations, with possible linkage appearing in two combinations of mutants. Growth trials in culture indicate that at least some of the mutants grow better than a genetically related wild type. In general, plants with increased branching showed the greatest promise.

scholarly journals Survival and mutant production induced by mutagenic agents in Metarhizium anisopliae

1995 ◽  
Vol 52 (3) ◽  
pp. 548-554 ◽  
Author(s):  
V. Kava - Cordeiro ◽  
E.A. Luna - Alves - Lima ◽  
J.L. Azevedo
Keyword(s):  
Gamma Radiation ◽  
Ultraviolet Light ◽  
Metarhizium Anisopliae ◽  
Entomopathogenic Fungus ◽  
Nitrous Acid ◽  
Wild Strain ◽  
Wild Type ◽  
Survival Curves ◽  
Auxotrophic Mutants ◽  
Morphological Mutants

A wild strain of Metarhizium anisopliae, an entomopathogenic fungus, was submitted to three mutagenic agents: gamma radiation, ultraviolet light and nitrous acid. Survival curves were obtained and mutants were selected using different mutagenic doses which gave 1 to 5% survival. Morphological and auxotrophic mutants were isolated. Morphological mutants were grouped in a class with yellow conidia and other with pale vinaceous conidia as opposed to the green wild type conidia. Auxotrophic mutants had requirements for vitamin and aminoacid biosynthesis. More than 58% of the total auxotrophk mutants required proline/aipnine. Gamma radiation showed to be the most efficient mutagenic agent giving 0.2% of auxotrophk mutants followed by ultraviolet light (0.12%) and nitrous acid (0.06%).The conidial colour and auxotrophk mutants isolated until now from M. anisopliae were reviewed.

Survival of Endocronartium harknessii teliospores in a simulated airborne state

1989 ◽  
Vol 67 (3) ◽  
pp. 928-932 ◽  
Author(s):  
Kan-Fa Chang ◽  
P. V. Blenis
Keyword(s):  
Relative Humidity ◽  
Liquid Nitrogen ◽  
Long Distance ◽  
Spider Webs ◽  
Considerable Potential ◽  
Good Ability ◽  
Endocronartium Harknessii ◽  
Spore Longevity ◽  
Effects Of Temperature ◽  
Increasing Temperature

The effects of temperature and relative humidity (RH) on the survival of Endocronartium harknessii teliospores and the longevity of these spores out of doors during daylight hours were studied. In one experiment, fresh and liquid-nitrogen-stored spores of E. harknessii were impacted onto spider webs or plastic threads and incubated in darkness at temperatures of 6, 15, and 24 °C and RHs of 39 and 98%. Survival was measured after 1, 2, 4, 8, and 16 days. Spore longevity decreased with increasing temperature and was lower at 98 than at 39% RH. In a second experiment, spores were impacted onto spider webs and placed out of doors on clear days. Viability decreased linearly with time and averaged 33% after 12 h. The data suggest that E. harknessii has relatively good ability to survive in an airborne state and thus would have considerable potential for long distance spread.

Effects of Temperature on Leaf Expansion in Sunflower

1982 ◽  
Vol 9 (2) ◽  
pp. 209 ◽  
Author(s):  
HM Rawson ◽  
JH Hindmarsh
Keyword(s):  
Field Studies ◽  
Leaf Expansion ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Leaf Position ◽  
Leaf Emergence ◽  
Temperature Regimes ◽  
Effects Of Temperature ◽  
Increasing Temperature ◽  
Relative Change

Five commercial cultivars of sunflower were grown in cabinets at three temperature regimes, 32/22, 27/17 and 22/12°C, and with 15-h and 11-h photoperiods, and expansion of leaves 5-15 was followed. Leaves appeared faster with increasing temperature (0.022 leaves day-1 °C-1) and with increasing daylength. Areas of individual leaves increased linearly up the plant profile and, although final area per leaf (Amax) decreased with increasing temperature, the relative change was similar for each leaf position. Cultivars maintained their ranking for Amax across temperatures, and these rankings agreed with those in previous field studies. Within each temperature regime, both the expansion rate of leaves and the duration of expansion increased with leaf position. As temperature increased, leaves grew for shorter periods with a change of 1.04 days °C-1, but under the photon flux density used (500 �mol m-2 s-1, or about 25% full sunlight) expansion rates were greatest at the lowest temperature. Expansion rates were only one-third of those in field studies at comparable temperatures, but durations were similar. Cultivars that achieved the largest Amax did so via faster rates of expansion and not via longer durations: only one cultivar differed from the mean (20 days) duration of leaf expansion. All cultivars reached floral initiation progressively earlier with extension of photoperiod from 10 to 15 h, with the change for the most sensitive cultivars being 8 days and for the least sensitive 5 days. Rates of leaf emergence were linked with this sensitivity.

scholarly journals Mutation in neurospora crassa with leaf extract of citrus aurantifolia and their soluble protein content

1970 ◽  
Vol 19 (2) ◽  
pp. 151-155
Author(s):  
Apurba Lal Ray ◽  
Mahbuba Akhter Jahan ◽  
Tahsina Rahim
Keyword(s):  
Neurospora Crassa ◽  
Protein Content ◽  
Soluble Protein ◽  
Mycelial Growth ◽  
Leaf Extract ◽  
Mutagenic Effect ◽  
Wild Type ◽  
Soluble Protein Content ◽  
Citrus Aurantifolia ◽  
Morphological Mutants

Leaf extract of Citrus aurantifolia exhibited remarkable inhibitor effect on the radial mycelial growth of Neurospora crassa. The extract also showed mutagenic effect and atleast six morphological mutants of the fungus were detected including albino (al 243), vigorous (vg 117), fluffy (fl 220), colonial (cl 232), conidial band (con. band 171) and dirty (dir 83). The mutants were used for estimation of soluble protein in comparison with the wild type (Ema). The soluble protein content increased to some extent in case of the mutants con. band 171 (192.86 μg/ml), cl 232 (188.57 μg/ml) and vg 117 (186.43 μg/ml) as compared to the wild type (182.14 μg/ml). On the other hand, the soluble protein content was remarkably decreased in case of the mutant al 243 (94.28 μg/ml), which was about 50% less than the control. This indicates that the leaf extract not only effect colony morphology but possesses profound effect on growth and metabolism of the fungus. Key words: Neurospora crassa; Mutation; Leaf extract; Soluble protein DOI: http://dx.doi.org/10.3329/dujbs.v19i2.8958 DUJBS 2010; 19(2): 151-155

scholarly journals From Function to Shape: A Novel Role of a Formin in Morphogenesis of the Fungus Ashbya gossypii

2006 ◽  
Vol 17 (1) ◽  
pp. 130-145 ◽  
Author(s):  
Hans-Peter Schmitz ◽  
Andreas Kaufmann ◽  
Michael Köhli ◽  
Pierre Philippe Laissue ◽  
Peter Philippsen
Keyword(s):  
Giant Cells ◽  
Polar Growth ◽  
Ashbya Gossypii ◽  
Essential Factor ◽  
Wild Type ◽  
Actin Cable ◽  
Lateral Branches ◽  
Actin Cables ◽  
Two Hybrid

Morphogenesis of filamentous ascomycetes includes continuously elongating hyphae, frequently emerging lateral branches, and, under certain circumstances, symmetrically dividing hyphal tips. We identified the formin AgBni1p of the model fungus Ashbya gossypii as an essential factor in these processes. AgBni1p is an essential protein apparently lacking functional overlaps with the two additional A. gossypii formins that are nonessential. Agbni1 null mutants fail to develop hyphae and instead expand to potato-shaped giant cells, which lack actin cables and thus tip-directed transport of secretory vesicles. Consistent with the essential role in hyphal development, AgBni1p locates to tips, but not to septa. The presence of a diaphanous autoregulatory domain (DAD) indicates that the activation of AgBni1p depends on Rho-type GTPases. Deletion of this domain, which should render AgBni1p constitutively active, completely changes the branching pattern of young hyphae. New axes of polarity are no longer established subapically (lateral branching) but by symmetric divisions of hyphal tips (tip splitting). In wild-type hyphae, tip splitting is induced much later and only at much higher elongation speed. When GTP-locked Rho-type GTPases were tested, only the young hyphae with mutated AgCdc42p split at their tips, similar to the DAD deletion mutant. Two-hybrid experiments confirmed that AgBni1p interacts with GTP-bound AgCdc42p. These data suggest a pathway for transforming one axis into two new axes of polar growth, in which an increased activation of AgBni1p by a pulse of activated AgCdc42p stimulates additional actin cable formation and tip-directed vesicle transport, thus enlarging and ultimately splitting the polarity site.

scholarly journals Effects of WMA Additive on the Rheological Properties of Asphalt Binder and High Temperature Performance Grade

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Jiupeng Zhang ◽  
Guoqiang Liu ◽  
Li Xu ◽  
Jianzhong Pei
Keyword(s):  
Critical Temperature ◽  
Rheological Properties ◽  
Asphalt Binder ◽  
Aging Effect ◽  
Asphalt Binders ◽  
Short Term ◽  
Performance Grade ◽  
Temperature Performance ◽  
Effects Of Temperature ◽  
Increasing Temperature

Sasobit additives with different dosages were added into 70# and 90# virgin asphalt binders to prepare WMA binders. The rheological properties, includingG∗andδ, were measured by using DSR at the temperature ranging from 46°C to 70°C, and the effects of temperature, additive dosage and aging onG∗/sin⁡δ, critical temperature, and H-T PG were investigated. The results indicate that WMA additive improvesG∗but reducesδ, and the improvement on 70# virgin binder is more significant.G∗/sin⁡δexponentially decreases with the increasing temperature but linearly increases with the increasing additive dosage. Aging effect weakens the interaction between binder and additive but significantly increases the binder’s viscosity; that is whyG∗/sin⁡δis higher after short-term aging. In addition, the critical temperature increases with the increasing additive dosage, and the additive dosage should be more than 3% and 5% to improve H-T PG by one grade for 70# and 90# virgin binder, respectively.

Temperature effects on pH of mitochondria isolated from carp red muscle

1988 ◽  
Vol 254 (4) ◽  
pp. R611-R615 ◽  
Author(s):  
C. D. Moyes ◽  
L. T. Buck ◽  
P. W. Hochachka
Keyword(s):  
Intracellular Ph ◽  
Temperature Effects ◽  
Respiratory Control ◽  
Ph Gradient ◽  
Carp Cyprinus Carpio ◽  
Red Muscle ◽  
Effects Of Temperature ◽  
Increasing Temperature ◽  
Induced Changes

Mitochondria isolated from red muscle of carp (Cyprinus carpio) were used to investigate the effects of temperature and extramitochondrial pH (pHe) on the mitochondrial pH gradient and respiratory properties. Mitochondria from animals acclimated to 10 degrees C were isolated and incubated in KCl-based media with 0.2 mM lauroylcarnitine (C-12) as substrate. Maximal respiratory control ratios (RCR = state 3/state 4) were 16-18 between pH 6.7 and 7.4 at 10 degrees C; RCR values were 9-12 between pH 6.5 and 7.1 at 30 degrees C. Changes in RCR values were due primarily to changes in the state 3 rate (in the presence of ADP). Mitochondrial pH was determined by measuring 5,5-[2-14C]dimethyloxazolidine-2,4-dione distribution, using [14C]sucrose as an extramatrical marker. The pH gradient was inversely related to pHe. At any particular pHe, the mitochondrial pH gradient decreased with increasing temperature. However, if pHe was varied in the same manner that intracellular pH changes with temperature in vivo, the pH gradient was maintained constant at approximately 0.4 U at 10, 20, and 30 degrees C. These data suggest that carp red muscle mitochondria defend an appropriate mitochondrial pH gradient with temperature-induced changes in intracellular pH.

Sign in / Sign up

Export Citation Format

Share Document