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At least 757 records · Page 42Linked to original sources
PubMed2002

Sit4 is required for proper modulation of the biological functions mediated by Pkc1 and the cell integrity pathway in Saccharomyces cerevisiae.

Maintenance of cellular integrity in Saccharomyces cerevisiae is carried out by the activation of the protein kinase C-mediated mitogen-activated protein kinase (PKC1-MAPK) pathway. Here we report that correct down-regulation of both basal and induced activity of the PKC1-MAPK pathway requires the SIT4 function. Sit4 is a protein phosphatase also required for a proper cell cycle progression. We present evidence demonstrating that the G(1) to S delay in the cell cycle, which occurs as a consequence of the absence of Sit4, is mediated by up-regulation of Pkc1 activity. Sit4 operates downstream of the plasma membrane sensors Mid2, Wsc1, and Wsc2 and upstream of Pkc1. Sit4 affects all known biological functions involving Pkc1, namely Mpk1 activity and cell wall integrity, actin cytoskeleton organization, and ribosomal gene transcription.

Acacia↗
PubMed2001

Evaluation of psychopharmacological effects of Clerodendrum phlomidis Linn. extract.

The methanolic extract of Clerodendrum phlomidis Linn. (MECP) leaves was evaluated for its psychopharmacological activities in several experimental models using Swiss albino mice and Wistar albino rats. The MECP was found to cause significant reduction in spontaneous activity, and decreases in exploratory behavioral profiles by the Y-maze and head dip test. It also showed reduction in muscle relaxant activity by rotarod, 30 degrees inclined screen and traction tests, as well as significantly potentiated the phenobarbitone sodium-induced sleeping time in the doses examined (200, 400 and 600 mg/kg body wt.). All the results were compared with respective controls for the evaluation of significance.

Acacia↗
PubMed2005

Morphological and secretory characterization of extrafloral nectaries in plants of coastal Veracruz, Mexico.

BACKGROUND AND AIMS: Morphological descriptions of the extrafloral nectaries (EFNs) of certain plant species are common in the literature, but they rarely relate morphology with histology, gland distribution and secretory attributes. In this study a morphological/secretory characterization of EFNs occurring on several plant species in a tropical coastal community is made and the implications of gland attributes discussed from a functional perspective. METHODS: The morphology and nectar secretion of the EFNs of 20 plant species are characterized through scanning electron microscopy, histochemical detection of reducing sugars (Fehling's reagent) and nectar volume/concentration estimates. KEY RESULTS: Sixty-five per cent of plant species in coastal communities had EFNs on vegetative structures and 35 % of species had glands on reproductive and vegetative organs. The Fabaceae is the plant family with the most species with EFNs and most diversity of gland morphologies. Four types of vascularized nectaries and four of glandular trichomes are described; sugar-secreting trichomes are characterized using Fehling's technique, and the first descriptions of unicellular and peltate trichomes functioning as EFNs are provided. Glands of ten plant species and six genera are described for the first time. Four plant species possess more than one morphological type of EFN. Eleven species have EFNs in more than one location or organ. More complex glands secrete more nectar, but are functionally homologous to the aggregations of numerous secretory trichomes on specific and valuable plant organs. CONCLUSION: Important diversity of EFN morphology was foundin the coastal plant community studied. Both vascularized and non-vascularized EFNs are observed in plants and, for the latter, previously non-existent morpho-secretory characterizations are provided with a methodological approach to study them. It is recommended that studies relating EFN attributes (i.e. morphology, distribution) with their differential visitation by insects (i.e. ants) and the cost of maintenance to the plants are carried out to understand the evolution of these glands.

Acacia↗
PubMed1976

Influence of certain dietary fibers on serum and tissue cholesterol levels in rats.

Pectin, carragheenan, agar gum arabic, cellulose and wheat bran were each fed to rats at a level of 5 to 7% to examine their effect on serum, liver and tissue cholesterol levels. Diets (casein-sucrose diet containing 10-15% soybean oil, or skim milk-wheat flour diet containing 10-15% soybean oil) supplemented with either 0, 0.2, or 0.5% cholesterol were used to test the possibly dietary interactions. Among the fibers tested, pectin displayed the most hypocholesterolemic effect. In some experiments, pectin lowered the level of cholesterol in the serum, liver, and aorta, but it elevated body cholesterol levels. Carragheenan was inconsistent in lowering serum cholesterol levels and tended to increase liver and carcass cholesterol levels. These results probably suggest that pectin and carragheenan can affect the distribution of cholesterol within the body. Gum arabic and agar did not lower serum cholesterol levels and in one case gum arabic elevated them. Furthermore, in some experiments they elevated liver body cholesterol levels. It appears that feeding of gum arabic and agar probably resulted in an expansion of the whole body cholesterol pool. Feeding of wheat bran or cellulose had no significant effect on either serum or liver cholesterol levels. The study indicates that the effect of dietary fiber is dependent on the composition of the diet. Furthermore, while some fibers such as pectin may exhibit a hypocholesterolemic effect in rats, other fibers such as gum arabic and agar may actually elevate serum or tissue cholesterol levels.

Acacia↗
PubMed1978

Effect of pectin, gum arabic and agar on cholesterol absorption, synthesis, and turnover in rats.

A series of five experiments was conducted to determine the effect of pectin, gum arabic and agar (5%) on cholesterol absorption, biosynthesis and turnover in rats. In the study of cholesterol absorption, a tracer dose of labeled cholesterol was included in the last meal. The rats were killed 12 hours later. The proportion of the labeled cholesterol recovered in the whole body was used as an estimation of the efficiency of absorption of dietary cholesterol. Cholesterol biosynthesis was estimated by determining the activity of labeled digitonin-precipitable sterols biosynthesized from labeled glucose which was included in a test meal. In turnover studies, rats were injected intravenously with labeled cholesterol using serum as a vehicle, and the activity of labeled cholesterol in tissues was determined after various time intervals. All three complex carbohydrates decreased cholesterol absorption and pectin had the greatest effect. Pectin and gum arabic increased cholesterol biosynthesis in rats fed a cholesterol-containing diet, but had no effect in a cholesterol-free diet. Pectin slightly increased the turnover of cholesterol, but gum arabic and agar had no effect. This work supports the hypothesis that pectin lowers cholesterol levels by interfering with cholesterol absorption and by increasing cholesterol turnover. The study also suggests that complex carbohydrates differ in their effects on cholesterol metabolism. The reason for these differences remains to be determined.

Absorption↗
PubMed2002

Growth rate and survivorship of drought: CO2 effects on the presumed tradeoff in seedlings of five woody legumes.

Traits that promote rapid growth and seedling recruitment when water is plentiful may become a liability when seedlings encounter drought. We tested the hypothesis that CO2 enrichment reinforces any tradeoff between growth rate and drought tolerance by exaggerating interspecific differences in maximum relative growth rate (RGR) and survivorship of drought among seedlings of five woody legumes. We studied invasive species of grasslands that differ in distribution along a rainfall gradient. Survivorship of drought at ambient CO2 concentration ([CO2]) was negatively related to RGR in well-watered seedlings in one of two experiments, but the relationship was weak because interspecific differences in RGR were small. Contrary to our hypothesis, there was no significant relationship among well-watered seedlings between RGR at ambient [CO2] and either the relative or absolute increase in RGR at elevated [CO2]. As predicted, however, CO2 enrichment reinforced interspecific differences in survivorship of seedlings exposed to similar rates of soil water depletion. Doubling [CO2] improved seedling survivorship of the most drought-tolerant species throughout the period of soil water depletion, but did not consistently affect survivorship of more drought-sensitive species. Midday xylem pressure potentials of drought-treated seedlings were less negative at elevated [CO2] than at ambient [CO2], but no other measured trait was consistently correlated with improved survivorship at high [CO2]. Carbon dioxide enrichment may not reinforce species differences in RGR, but could exaggerate interspecific differences in drought tolerance. To the extent that seedling persistence in grasslands correlates with drought survivorship, our results indicate a positive effect of CO2 enrichment on recruitment of woody legumes that are currently tolerant of drought.

Acacia↗
PubMed2002

Influence of natural temperature gradients on measurements of xylem sap flow with thermal dissipation probes. 2. Advantages and calibration of a noncontinuous heating system.

Natural temperature gradients in stems of trees growing in open stands give rise to errors when measuring sap flow by the continuous thermal dissipation method. Previously, we obtained evidence from field measurements that a noncontinuous thermal dissipation system can prevent these errors (Do and Rocheteau 2002). Cyclic heating (i.e., 45 minutes on and 15 minutes off; 45/15) allowed the derivation of an alternate signal, defined as the difference between the temperature signal at the end of the heating period and the temperature signal at the end of the cooling period. By analogy with the continuous system, we calculated an alternate flow index. Analysis in an artificial flow system confirmed that external temperature gradients have an additive effect on the continuous signal, whereas the alternate signal is unaffected by such gradients. The response of the alternate flow index to flow densities was similar for five combinations of heating and cooling times (45/15, 40/20, 30/30, 15/15 and 10/10 min). The relationship was markedly different from Granier's (1985) calibration because measurements in cyclic systems are made under non-steady-state temperature conditions. We recommend the 15/15 min cycle, which allows two sap flow measurements per hour. We compared flow density estimates obtained from field measurements with the continuous and cyclic systems over 192 days with 1-day lags between systems. Comparisons based on daily maximum values (between 0.5 and 2.5 l dm(-2) h(-1) for the cyclic system) confirmed that differences between the continuous and cyclic systems, which could be greater than 100%, were linked to the effect of temperature gradients on the continuous system. The results demonstrate that, in situations where significant natural temperature gradients (i.e., > 0.2 degrees C) are likely, the cyclic system improves the accuracy of sap flow measurements made with thermal dissipation probes.

Acacia↗
PubMed2004

A balanced psychology and a full life.

Psychology since World War II has been largely devoted to repairing weakness and understanding suffering. Towards that end, we have made considerable gains. We have a classification of mental illness that allows international collaboration, and through this collaboration we have developed effective psychotherapeutic or pharmacological treatments for 14 major mental disorders. However, while building a strong science and practice of treating mental illness, we largely forgot about everyday well-being. Is the absence of mental illness and suffering sufficient to let individuals and communities flourish? Were all disabling conditions to disappear, what would make life worth living? Those committed to a science of positive psychology can draw on the effective research methods developed to understand and treat mental illness. Results from a new randomized, placebo-controlled study demonstrate that people are happier and less depressed three months after completing exercises targeting positive emotion. The ultimate goal of positive psychology is to make people happier by understanding and building positive emotion, gratification and meaning. Towards this end, we must supplement what we know about treating illness and repairing damage with knowledge about nurturing well-being in individuals and communities.

Adaptation, Psychological↗
PubMed1990

The influence of selected tannin-containing plant species on the tenacity of pathogenic bacteria in an in-vitro rumen system. 1. Communication: the influence of selected plant species on the tenacity of Cl. perfringens.

The effect of plant species containing tannins on the tenacity of Cl. perfringens was elucidated. Trials were purchased in physiological saline solution and in a rumen-fluid-medium under anaerobic conditions. The results obtained show, that within minutes the tenacity of Cl. perfringens can be reduced by some of the tested plant material not only in physiological saline solution but also in a rumen-fluid-medium. The results indicate that the reaction of some vegetable tannins and Clostridium perfringens germs is a specific one and could be used in controlling diseases caused by Clostridium perfringens.

Acacia↗
PubMed1984

Particle size analysis of microcapsules.

To standardize the preparation of three-walled w/o/w microcapsules it was necessary to assess their particle size distribution, since they occur as both unicored and multicored types. The log-normal law, reported to be obeyed by many particulate systems, including microcapsules, was not applicable to the size data. A curve-fitting computer program using least squares minimization was used to assess the size distribution data. The models tested were the unimodal and bimodal log-normal distributions, the bimodal form being the most appropriate. Using the equations to the curves of best fit, the modal size and standard deviation of each population were estimated, and the relative percentages of unicored and multicored microcapsules could be deduced from an analysis of the bimodal curves in which they were represented as the sum of two constituent unimodal distributions.

Acacia↗