GROWTH RESPONSES OF FIVE NON TOXIC ALEXANDRIUM SPECIES (DINOPHYCEAE) TO TEMPERATURE AND SALINITY

Growth response of five clonal cultures of Alexandrium obtained from tropical and temperate waters were examined. Experiments were carried out in eighteen variable temperature-salinity conditions (temperatures of 15 °C, 20°C, and 25°C; salinities between 5 to 30 psu) under constant illumination of 150 ± 10.0 Amol m-2 s-' at 15:9 light:dark photo-cycle. Our results showed optimum growth of all Alexandrium species at 20 - 25°C. The salinity range for optimum growth however varied among the species. Growth rates of A. eine, A. insuetum, and A. fraterculus (0.28 — 0.37 day') were higher than those of A. leei and A. pseudogoniaulax under the same culture conditions (0.14 —0.22 day-'). The three temperate species showed positive growth at suboptimum temperature, 15°C, but the tropical species did not grow and died off. Salinity tolerance of the five species in decreasing order was A. pseudogoniaulax > A. leei > A. insuetum > A. affine > A. fraterculus. Results of the present study showed vast variations in salinity tolerance among the Alexandrium species regardless the geographical origins. Adaptation of the temperate species at higher temperature indicated that the species might proliferate in warm tropical waters.

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Variable Temperature Measurement on Operating Pentacene-Based OTFT

MRS Proceedings ◽

10.1557/proc-1091-aa07-91 ◽

2008 ◽

Vol 1091 ◽

Cited By ~ 2

Author(s):

Hung-Keng Chen ◽

Po-Tsun Liu ◽

Ting-Chang Chang ◽

S.-L. Shy

Keyword(s):

Conduction Mechanism ◽

Variable Temperature ◽

Electrical Measurement ◽

Isokinetic Temperature ◽

Trap States ◽

Band Tail ◽

Thermally Activated ◽

Multiple Trapping ◽

Higher Temperature ◽

Release Model

AbstractVariable temperature electrical measurement is well-established and used for determining the conduction mechanism in semiconductors. There is a Meyer¡VNeldel relationship between the activation energy and the prefactor with a Meyer¡VNeldel energy of 30.03 meV, which corresponds well with the isokinetic temperature of about 350 K. Therefore, the multiple trapping and release model is properly used to explain the thermally activated phenomenon. By the method, an exponential distribution of traps is assumed to be a better representation of trap states in band tail. Samples with higher temperature during measurement are observed to show better mobility, higher on-current and lower resistance, which agree well with the multiple trapping and release model proposed to explain the conduction mechanism in pentacene-based OTFTs.

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Extracellular α-Galactosidase from Trichoderma sp. (WF-3): Optimization of Enzyme Production and Biochemical Characterization

Biotechnology Research International ◽

10.1155/2015/860343 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

Aishwarya Singh Chauhan ◽

Arunesh Kumar ◽

Nikhat J. Siddiqi ◽

B. Sharma

Keyword(s):

Enzyme Activity ◽

Enzyme Assay ◽

Biochemical Characterization ◽

Catalytic Efficiency ◽

Culture Conditions ◽

Significant Loss ◽

Trichoderma Sp ◽

Rate Of Reaction ◽

Higher Temperature ◽

Substrate Concentrations

Trichoderma spp. have been reported earlier for their excellent capacity of secreting extracellular α-galactosidase. This communication focuses on the optimization of culture conditions for optimal production of enzyme and its characterization. The evaluation of the effects of different enzyme assay parameters such as stability, pH, temperature, substrate concentrations, and incubation time on enzyme activity has been made. The most suitable buffer for enzyme assay was found to be citrate phosphate buffer (50 mM, pH 6.0) for optimal enzyme activity. This enzyme was fairly stable at higher temperature as it exhibited 72% activity at 60°C. The enzyme when incubated at room temperature up to two hours did not show any significant loss in activity. It followed Michaelis-Menten curve and showed direct relationship with varying substrate concentrations. Higher substrate concentration was not inhibitory to enzyme activity. The apparent Michaelis-Menten constant (Km), maximum rate of reaction (Vmax), Kcat, and catalytic efficiency values for this enzyme were calculated from the Lineweaver-Burk double reciprocal plot and were found to be 0.5 mM, 10 mM/s, 1.30 U mg−1, and 2.33 U mg−1 mM−1, respectively. This information would be helpful in understanding the biophysical and biochemical characteristics of extracellular α-galactosidase from other microbial sources.

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Intraspecific variation in thermal tolerance differs between tropical and temperate fishes

Scientific Reports ◽

10.1038/s41598-021-00695-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

J. J. H. Nati ◽

M. B. S. Svendsen ◽

S. Marras ◽

S. S. Killen ◽

J. F. Steffensen ◽

...

Keyword(s):

Climate Change ◽

Global Warming ◽

Intraspecific Variation ◽

Fish Species ◽

Thermal Tolerance ◽

Evolutionary History ◽

Ecological Impacts ◽

Temperate Species ◽

Tropical Species ◽

Upper Thermal Tolerance

AbstractHow ectothermic animals will cope with global warming is a critical determinant of the ecological impacts of climate change. There has been extensive study of upper thermal tolerance limits among fish species but how intraspecific variation in tolerance may be affected by habitat characteristics and evolutionary history has not been considered. Intraspecific variation is a primary determinant of species vulnerability to climate change, with implications for global patterns of impacts of ongoing warming. Using published critical thermal maximum (CTmax) data on 203 fish species, we found that intraspecific variation in upper thermal tolerance varies according to a species’ latitude and evolutionary history. Overall, tropical species show a lower intraspecific variation in thermal tolerance than temperate species. Notably, freshwater tropical species have a lower variation in tolerance than freshwater temperate species, which implies increased vulnerability to impacts of thermal stress. The extent of variation in CTmax among fish species has a strong phylogenetic signal, which may indicate a constraint on evolvability to rising temperatures in tropical fishes. That is, in addition to living closer to their upper thermal limits, tropical species may have higher sensitivity and lower adaptability to global warming compared to temperate counterparts. This is evidence that freshwater tropical fish communities, worldwide, are especially vulnerable to ongoing climate change.

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Salinity optima for vegetative growth and sexual reproduction of the diatom Toxarium undulatum

Marine Biological Journal ◽

10.21072/mbj.2020.05.1.03 ◽

2020 ◽

Vol 5 (1) ◽

pp. 20-28

Author(s):

N. A. Davidovich ◽

O. I. Davidovich

Keyword(s):

Sexual Reproduction ◽

Black Sea ◽

Salinity Tolerance ◽

Vegetative Growth ◽

Sea Water ◽

The Black Sea ◽

Crimean Peninsula ◽

Wide Range ◽

Clonal Cultures ◽

Oceanic Species

Distribution of diatom algae is limited by their tolerance to environmental factors. Although a genus Toxarium has been evolving for more than 100 million years, it is represented by only two species. Toxarium undulatum is widely spread in tropical and subtropical seas, and it can be also found in the Black Sea, the salinity of which is twice lower than the oceanic one. Ecological and psychological characteristics research of this species is of great interest in terms of its relationship to salinity. T. undulatum clonal cultures were sampled in the Donuzlav Lake connected to the Black Sea (southwest of the Crimean Peninsula) and on Gran Canaria coast (Canary Islands archipelago). Experiments on the salinity tolerance limits showed, that the Black Sea clones were viable in a range of at least 30 ‰ (12 to 42 ‰). The same wide range of salinity tolerance with slightly higher values was observed among oceanic clones of this species. Optima of vegetative growth and sexual reproduction were determined. Optima of the Black Sea clones appeared to be 27.8 and 27.2 ‰, respectively, which was significantly higher than salinity observed in population habitat. Similar higher optima of vegetative growth and sexual reproduction, compared with those salinity values, at which natural population developed, were observed for a number of other Black Sea diatoms, which proved their oceanic (Mediterranean) origin. It was concluded that T. undulatum, along with other species, began to populate the Black Sea basin about seven thousand years ago after Mediterranean Sea water started to flow into the freshened Novoevksinsky Sea-Lake through the Bosporus Strait. However, the evolution rate did not allow bringing physiological and ecological characteristics of the species studied into full agreement with environmental conditions. Oceanic origin is evidently seen in its physiological reactions to salinity. Possibility of speciation due to settlement of the Black Sea with oceanic species is discussed.

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Common precursors for neural and mesectodermal derivatives in the cephalic neural crest

Development ◽

10.1242/dev.112.1.301 ◽

1991 ◽

Vol 112 (1) ◽

pp. 301-305 ◽

Cited By ~ 9

Author(s):

A. Baroffio ◽

E. Dupin ◽

N.M. Le Douarin

Keyword(s):

Neural Crest ◽

Cell Types ◽

Culture Conditions ◽

Pigment Cells ◽

Stem Cell Population ◽

Multipotent Cells ◽

Clonal Cultures ◽

Vertebrate Embryos ◽

Derivatives Of

The cephalic neural crest (NC) of vertebrate embryos yields a variety of cell types belonging to the neuronal, glial, melanocytic and mesectodermal lineages. Using clonal cultures of quail migrating cephalic NC cells, we demonstrated that neurons and glial cells of the peripheral nervous system can originate from the same progenitors as cartilage, one of the mesectodermal derivatives of the NC. Moreover, we obtained evidence that the migrating cephalic NC contains a few highly multipotent precursors that are common to neurons, glia, cartilage and pigment cells and which we interprete as representative of a stem cell population. In contrast, other NC cells, although provided with identical culture conditions, give rise to clones composed of only one or some of these cell types. These cells thus appear restricted in their developmental potentialities compared to multipotent cells. It is therefore proposed that, in vivo, the active proliferation of pluripotent NC cells during the migration process generates distinct subpopulations of cells that become progressively committed to different developmental fates.

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FLK-2/FLT-3 ligand regulates the growth of early myeloid progenitors isolated from human fetal liver

Blood ◽

10.1182/blood.v85.4.963.bloodjournal854963 ◽

1995 ◽

Vol 85 (4) ◽

pp. 963-972 ◽

Cited By ~ 78

Author(s):

MO Muench ◽

MG Roncarolo ◽

S Menon ◽

Y Xu ◽

R Kastelein ◽

...

Keyword(s):

Fetal Liver ◽

Culture Conditions ◽

Proliferative Potential ◽

Growth And Survival ◽

Human Fetal Liver ◽

Gm Csf ◽

Clonal Cultures ◽

Macrophage Colony Stimulating Factor ◽

Low Levels ◽

Macrophage Colony

The effects of the recently identified FLK-2/FLT-3 ligand (FL) on the growth of purified human fetal liver progenitors were investigated under serum-deprived culture conditions. FL alone was found to stimulate modest proliferation in short-term cultures of CD34++ CD38+ lineage (Lin)- light-density fetal liver (LDFL) cells and the more primitive CD34++ CD38- Lin- LDFL cells. However, the low levels of growth induced by FL were insufficient for colony formation in clonal cultures. Synergism between FL and either granulocyte-macrophage colony- stimulating factor (GM-CSF), interleukin-3 (IL-3) or KIT ligand (KL) was observed in promoting the growth of high-proliferative potential (HPP) colony-forming cells (CF) and/or low-proliferative potential (LPP)-CFC in cultures of CD34++ CD38+ Lin- and CD34++ CD38- Lin- LDFL- cells. FL, alone or in combination with other cytokines, was not found to affect the growth of CD34+ Lin- LDFL cells, the most mature subpopulation of fetal liver progenitors investigated. The growth of the most primitive subset of progenitors studied, CD34++ CD38- Lin- LDFL cells, required the interactions of at least two cytokines, because only very low levels of growth were observed in response to either FL, GM-CSF, IL-3 or KL alone. However, the results of delayed cytokine-addition experiments suggested that individually these cytokines did promote the survival of this early population of progenitors. Although two-factor combinations of FL, KL, and GM-CSF were observed to promote the growth of early progenitors in a synergistic manner, neither of these factors was found to make fetal liver progenitors more responsive to suboptimal concentrations of a second cytokine. Only myeloid cells were recovered from liquid cultures of CD34++ CD38- Lin- LDFL cells grown in the presence of combinations of FL, KL, and GM-CSF. These results indicate that FL is part of a network of growth factors that regulate the growth and survival of early hematopoietic progenitors.

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Energy and protein values of four forages, including a comparison between tropical and temperate species

Australian Journal of Experimental Agriculture ◽

10.1071/ea9880729 ◽

1988 ◽

Vol 28 (6) ◽

pp. 729 ◽

Cited By ~ 11

Author(s):

DE Margan ◽

NM Graham ◽

DJ Minson ◽

TW Searle

Keyword(s):

Chemical Composition ◽

Cell Walls ◽

Crude Protein ◽

Temperate Species ◽

Tropical Species ◽

Similar Chemical ◽

Metabolisable Energy ◽

Tropical Forages ◽

Carbon Balances ◽

Energy Maintenance

Artificially dried grass of 2 tropical species (Setaria spacelata and Digitaria decurnbens) from which most of the stem had been removed, and a temperate grass (Loliurn perenne) grown under the same subtropical conditions, were compared for energy and protein value. Data for a temperate clover hay (Trifolium resupinatum) that was tested concurrently are included because they provide useful contrasts. Each was evaluated by measuring energy, nitrogen (N) and carbon balances in 4 adult sheep at 2 levels of intake (ad libitum and near energy maintenance) and during fasting. The 3 grasses had similar leaf content (76-83%) and the clover much less (60%). The tropical forages had similar chemical composition but they contained less crude protein (10%) than the ryegrass (L. perenne) (1 5%) and more cell wall constituents (63-66% v. 58%). The clover had the most crude protein (19%) and the least cell walls (38%); it also was highest in carbohydrates, pectin and heat of combustion. Voluntary intakes of the setaria, pangola (D. decumbens) and ryegrass were similar and 20-30% lower than the intake of clover. Digestibilities of dry matter (DM), organic matter (OM) and energy were similar for the grasses and 8 percentage units lower than for the clover whereas digestibility of crude protein differed between the tropical and temperate species, the latter having digestibilities 12-15 units greater. Digestibility of cell walls did not vary. The metabolisable energy (ME) values of the grasses at maintenance were 8.3-8.5 MJ/kg DM while that of clover was 10.1; at maximum intakes, corresponding ME values were 7.9 and 10.0 MJ/kg DM. Net availability of ME for gain was 0.42 for the tropical grasses and the persian clover and 0.36 for the ryegrass. By contrast, the tropical forages supported higher gains of N relative to N supply than did the temperate forages because urinary N loss was not affected by intake of the tropicals; these differences in N gain were drastically reduced when gain was expressed in relation to ME. These results do not support the contention that forages of tropical species have a lower energy value per kg than temperate forages of similar composition. Indeed, the tropical species tested here appear to have had an ideal balance of energy and protein insofar as efficiency of use of digestible N was close to 100% and their energy values were commensurate with their chemical composition.

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Effect of sowing time on the establishment and early production of tropical and temperate pasture mixtures under irrigation in south-eastern Queensland

Australian Journal of Experimental Agriculture ◽

10.1071/ea9810410 ◽

1981 ◽

Vol 21 (111) ◽

pp. 410

Author(s):

KF Lowe ◽

TM Bowdler ◽

JC Mulder

Keyword(s):

Dry Matter ◽

Temperate Species ◽

Considerable Proportion ◽

Tropical Species ◽

Sowing Time ◽

South Eastern ◽

Early Production ◽

Grass Establishment ◽

Second Year ◽

Tropical Grass

The most effective time to sow irrigated perennial pastures containing tropical and temperate species was investigated over three years at Gatton, south-eastern Queensland. Three mixtures were sown each month between September and June and in split sowings where the tropical species were sown in September or March, and the temperate species in May. Autumn sowings produced the most seedlings of sown species 40 d after sowing. Of the autumn months, May was the most suitable, with an establishment of 181 plants/m2 and a weed population of only 19 plants/m2. Tropical grass establishment was less than 8 plants/m2 from all sowing times. A considerable proportion of tropical grass sown in autumn appeared in spring. Split sowings were not as effective as autumn sowings and favoured the tropical species, which were sown first. Dry matter yield of sown species in the establishment year varied from 0.9 t/ha for February sowings to 12.0 t/ha for April sowings; weed yields varied from 5.8 t/ha for September sowings to 0.8 t/ha for May sowings. Tropical grass contribution was greatest from the split sowing in which the tropical species were sown in September. Temperate species yields were highest from May sowings. In the second year yields of temperate species declined substantially, mainly because of poor persistence of ryegrass. Although tropical grass yields increased in all treatments, this increase was not sufficient in the autumn sowings to compensate for the low ryegrass yields.

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