Iron deficiency stress induced morphological and physiological changes in root tips of sunflower

Typical morphological and physiological changes were observed in iron deficient sunflower ( Helianthus annuus L. cv. Sobrid) roots. These changes, or so-called iron stress reactions, are exclusively confined to the root tips. Typical morphological changes included additional cell division in the rhizodermis layer and enhanced formation of root hairs, leading to an increase in root diameter ("swollen root tips"). These morphological changes were correlated with physiological changes such as increased release of protons, accumulation of phenols in the rhizodermis, and an increased ability of the roots to reduce iron-III compounds ("reducing capacity"). A marked increase in ability of the root tips to take up and translocate iron occurred simultaneously with these changes. There is good evidence that these morphological and physiological changes are reflections of an effective regulatory mechanism for enhanced mobilization of sparingly soluble iron-III compounds in the rhizosphere and for iron uptake by sunflower plants.     

Criteria for the evaluation of the functional importance of endogenous analogues of pharmacological regulators

Criteria for the evaluation of the functional importance of endogenous analogues of pharmacological drugs are proposed. These include opposite changes in their content in opposite pathophysiological or physiological states, accompanied by corresponding changes in the functional activity of enzymes sensitive to changes in their level, and the regulation of target enzymes by physiological concentrations of such endogenous compounds. The applicability of these criteria has been demonstrated using tribulin, the endogenous family of inhibitors of monoamine oxidases.     

Effects of environmental pollutants on the reproduction and welfare of ruminants

Anthropogenic pollutants comprise a wide range of synthetic organic compounds and heavy metals, which are dispersed throughout the environment, usually at low concentrations. Exposure of ruminants, as for all other animals, is unavoidable and while the levels of exposure to most chemicals are usually too low to induce any physiological effects, combinations of pollutants can act additively or synergistically to perturb multiple physiological systems at all ages but particularly in the developing foetus. In sheep, organs affected by pollutant exposure include the ovary, testis, hypothalamus and pituitary gland and bone. Reported effects of exposure include changes in organ weight and gross structure, histology and gene and protein expression but these changes are not reflected in changes in reproductive performance under the conditions tested. These results illustrate the complexity of the effects of endocrine disrupting compounds on the reproductive axis, which make it difficult to extrapolate between, or even within, species. Effects of pollutant exposure on the thyroid gland, immune, cardiovascular and obesogenic systems have not been shown explicitly, in ruminants, but work on other species suggests that these systems can also be perturbed. It is concluded that exposure to a mixture of anthropogenic pollutants has significant effects on a wide variety of physiological systems, including the reproductive system. Although this physiological insult has not yet been shown to lead to a reduction in ruminant gross performance, there are already reports indicating that anthropogenic pollutant exposure can compromise several physiological systems and may pose a significant threat to both reproductive performance and welfare in the longer term. At present, many potential mechanisms of action for individual chemicals have been identified but knowledge of factors affecting the rate of tissue exposure and of the effects of combinations of chemicals on physiological systems is poor. Nevertheless, both are vital for the identification of risks to animal productivity and welfare.     

Growth and physiological response of Arthrobacter protophormiae RKJ100 toward higher concentrations of o-nitrobenzoate and p-hydroxybenzoate

Bioremediation of sites that are heavily contaminated with pollutant chemicals is a challenge as most of the microorganisms cannot tolerate higher concentrations of toxic compounds. Only a few strains of the genus Pseudomonas have been studied for their tolerance toward the higher concentrations of aromatic pollutant compounds, a phenomenon that is accompanied by various physiological changes. In the present study we have characterized the growth response and physiological changes (adaptations) of a Gram-positive bacterium, Arthrobacter protophormiae RKJ100, toward the higher concentrations of two aromatic compounds, viz. o-nitrobenzoate (ONB) and p-hydroxybenzoate (PHB). Arthrobacter protophormiae RKJ100 could utilize 30 mM ONB and 50 mM PHB as sole sources of carbon and energy. It was capable of growth on higher concentrations of ONB (up to 200 mM) and PHB (up to 150 mM) when the cells were pre-exposed to lower concentrations of these compounds. The adaptive responses shown by the organism during growth on higher concentrations of these compounds were evident from significant changes in cellular fatty acid profiles. In addition, Bacterial Adhesion To Hydrocarbon (BATH) assay and scanning electron microscopy showed substantial increase in cell surface hydrophobicity and decrease in cell size of A. protophormiae RKJ100 when grown on ONB and PHB as compared to succinate-grown cells.     

Cardiac steroids induce changes in recycling of the plasma membrane in human NT2 cells

Cardiac steroids (CSs) are specific inhibitors of Na+, K(+)-ATPase activity. Although the presence of CS-like compounds in animal tissues has been established, their physiological role is not evident. In the present study, treatment of human NT2 cells with physiological concentrations (nanomolar) of CSs caused the accumulation of large vesicles adjacent to the nucleus. Experiments using N-(3-triethylammonium propyl)-4-(dibutilamino)styryl-pyrodinum dibromide, transferrin, low-density lipoprotein, and selected anti-transferrin receptor and Rab protein antibodies revealed that CSs induced changes in endocytosis-dependent membrane traffic. Our data indicate that the CS-induced accumulation of cytoplasmic membrane components is a result of inhibited recycling within the late endocytic pathway. Furthermore, our results support the notion that the CS-induced changes in membrane traffic is mediated by the Na+, K(+)-ATPase. These phenomena were apparent in NT2 cells at nanomolar concentrations of CSs and were observed also in other human cell lines, pointing to the generality of this phenomenon. Based on these observations, we propose that the endogenous CS-like compounds are physiological regulators of recycling of endocytosed membrane proteins and cargo.     

Social housing influences the composition of volatile compounds in the preputial glands of male rats

In rodents the preputial glands are one of the major sources of pheromones. These volatile chemosignaling compounds are known to elicit specific behavioral and physiological effects in their conspecifics. While social stress can alter both the behavior and hormonal status of rodents, little is known about its influence on the volatile constituents of the preputial glands. We have examined the composition of volatile compounds in the preputial glands of gonadally intact male rats housed for 70 days in either unisex triads (three/cage) or singly. The rank status of triad-housed rats was based on quantitative behavioral assessments taken during the initial 30 min of triad housing. Dominant rats had heavier preputial glands compared to subdominant and subordinate rats. Capillary gas chromatography-mass spectrometry identified 56 volatile preputial compounds, of these 17 did not differ between groups while 26 compounds were significantly higher in the single-housed compared to the triad-housed rats. Six additional volatile compounds were higher in the dominant compared to the other 3 groups, while another six compounds were higher in both the dominant and single-housed rats compared to the subdominant and subordinate rats. It can be concluded that both housing condition and social rank status have significant but different effects on the composition of volatile compounds found in preputial glands of male rats. The physiological and behavioral significance of these changes in preputial gland volatile compound composition in rats remain to be investigated.     

Study of the Early Events Leading to Cassava Root Postharvest Deterioration

Cassava (Manihot esculenta Crantz) roots, the fourth most important food crop of the world, is the major carbohydrate source for more than 600 million people in Africa, parts of Latin America, Oceania, and Asia. Besides being a rich source of starch (～80% of root), the root is also rich in vitamin C, some carotenoids, calcium, and potassium. Upon harvest, roots begin a process of physiological decay within 24–36 h called postharvest physiological deterioration or PPD. The early events leading to PPD are not known. Research to date concerning the study of PPD has mostly focused on the signaling events several hours after harvest. Upon examination of physiological and biochemical changes occurring 3 or 4 h after cassava root detachment, changes in the nature and type of volatile compounds emitted, secondary metabolites accumulated, and changes in the expression of key genes in reactive oxygen species (ROS) turnover were observed along with a correspondent increase in tissue cytoplasmic singlet oxygen presence using radical-specific fluorescent imaging of tissue samples. It is likely that these findings have significant implications to help us understand and assist in dissection of the early events leading to the postharvest deterioration of cassava root.     

Seasonal variation in the nutritional value of woody plants along a natural gradient in Eastern Africa

Several hypotheses relate a negative relationship between foliar concentration of phenolic compounds and nitrogen to physiological processes such as leaf development, seasonal variation in allocation priorities, nutrient, light and water related growth limitation, as well as herbivore attack. We sampled four common deciduous woody species of central Tanzania monthly during the growing season to assess changes in this relation and their nutritional value to ruminants. We found a negative relationship between leaf N and phenolic compounds within and among species and sites that weakens during the course of the growing season that was consistent for total phenolics, but not for condensed tannins. Leaf N concentration decreased throughout the season, its withdrawal being positively related with leaf N at first sampling date. Secondary compounds concentration showed no consistent seasonal trend. Concentrations of leaf N and phenolics were correlated with ¹³C discrimination in the two shrub species and with soil P in the two tree species. Digestibility was positively correlated with foliar N and negatively correlated with secondary compounds. We conclude that phenolic compounds may serve as reliable clues for selecting foliage rich in N at site and species level only during the first months of the growing season.     

Identification of Novel Inhibitors of Dietary Lipid Absorption Using Zebrafish

Pharmacological inhibition of dietary lipid absorption induces favorable changes in serum lipoprotein levels in patients that are at risk for cardiovascular disease and is considered an adjuvant or alternative treatment with HMG-CoA reductase inhibitors (statins). Here we demonstrate the feasibility of identifying novel inhibitors of intestinal lipid absorption using the zebrafish system. A pilot screen of an unbiased chemical library identified novel compounds that inhibited processing of fluorescent lipid analogues in live zebrafish larvae. Secondary assays identified those compounds suitable for testing in mammals and provided insight into mechanism of action, which for several compounds could be distinguished from ezetimibe, a drug used to inhibit cholesterol absorption in humans that broadly inhibited lipid absorption in zebrafish larvae. These findings support the utility of zebrafish screening assays to identify novel compounds that target complex physiological processes.     

Features of the intracellular repair of irradiated keratinocytes

By means of light and electron microscopy, intracellular reparation has been studied after a local x-ray radiation of the rat paws (7.74 X 10(-1) Ci/kg) using radioprotectors (mexamin, cysteamin, ionol) and other chemical compounds (including membranoprotective ones). Restoration of the intracellular structures after x-ray burns proceeds more slowly and more complexly than reparation of the epidermis as a tissue system. To the slowly repairing intracellular formations belong mitochondria and, especially, internal mitochondrial membrane, as well as intercellular contacts. Under radiation mitochondria increase their volume at the expense of their three-fold swelling. Preliminary treatment of the skin with some of the compounds mentioned above decreases or completely prevents these changes. By means of the membranoactive chemical compounds, as well as by means of the known radioprotectors it is possible essentially to normalize the process of intracellular reparation and physiological regeneration of the ultrastructures, and in some cases, to stimulate reparative processes in them.     

Inhibition of the k-stimulated ATPase of the plasmalemma of pinto bean leaves by ozone

Three varieties of Phaseolus vulgaris which differ in their sensitivity to ozone were examined for changes in some physiological and structural plasma membrane characteristics. Plasma membrane vesicles were prepared from control and ozone-treated (0.2 to 0.5 microliters per liter ozone for 5 hours) leaf tissue, and the (K⁺ + Mg²⁺)-ATPase activity determined and compared. No major changes were observed in the resistant varieties. The sensitive variety showed a severe inhibition of ATPase activity which was largely due to a decrease in the K⁺-stimulated component. This inhibition was completely reversed by the addition of sulfhydryl compounds.

Ozone-induced plasma membrane permeability changes may be effected by damage to membrane proteins, perhaps by oxidation of amino acid sulfhydryl groups to disulfide and sulfenic moieties.

     

The effect of growth temperature on the long-chain alkenes composition in the marine coccolithophorid Emiliania huxleyi

The hydrocarbon fraction of a pure culture of Emiliania huxleyi, composed of a mixture of C31, C33, C37 and C38 polyunsaturated n-alkenes, appeared strongly dependent on the growth temperature of the alga between 8 degrees C and 25 degrees C. The total hydrocarbon content increased linearly with decreasing temperatures. C37 and C38 alkenes (which accounted for more than 90% of the total hydrocarbons) showed distinct changes in distribution compared to C31 and C33 alkenes, suggesting different biological syntheses and/or functions for these two groups of compounds. C37 and C38 alkenes and C37 methyl ketones (alkenones) all showed a trend to lower proportions of the two diunsaturated isomers and to higher proportions of the corresponding trienes with decreasing temperature. Unlike the alkenone unsaturation ratio (U37k'), ratios based on the C37 and C38 alkadi- and trienes could be linearly related to the growth temperature of E. huxleyi only between 15 degrees C and 25 degrees C. The modifications in the distribution of alkenes induced by varying temperature appeared, however, to be twice as fast as the modifications undergone by the alkenones. Although structurally and biochemically related, the distinct evolutions of alkenes and alkenones in response to changes in growth temperature might indicate that these two classes of compounds play two distinct physiological functions. The non-systematic linearity of relationships to temperature of parameters based on alkenes distribution suggested that these compounds are of limited use as paleotemperature indicator in the marine environment in contrast with the alkenones.     

Physiological activities and the active constituents of potentially medicinal plants used by wild chimpanzees of the Mahale mountains,Tanzania

Potential medicinal plants for wild chimpanzees have been studied in order to discover their physiologically active compounds. Tests of the physiological activity of 3 plant species—Vernonia amygdalina, Aspilia mossambicensis, andFicus exasperata—indicate that they contain a variety of active compounds. From one species,V. amygdalina, an antitumor agent and 2 possible antitumor promoters are identified. Furthermore, steroid glucosides were isolated as the bitter substances. These structurally new compounds are expected to exhibit a number of significant physiological activities. The chemical investigation of possible medicinal plants used by chimpanzees should be helpful in recovering naturally occurring compounds of medicinal significance for human use.     

Condition-dependent chemosignals in reproductive behavior of lizards

This article is part of a Special Issue “Chemosignals and Reproduction”.Many lizards have diverse glands that produce chemosignals used in intraspecific communication and that can have reproductive consequences. For example, information in chemosignals of male lizards can be used in intrasexual competition to identify and assess the fighting potential or dominance status of rival males either indirectly through territorial scent-marks or during agonistic encounters. Moreover, females of several lizard species “prefer” to establish or spend more time on areas scent-marked by males with compounds signaling a better health or body condition or a higher genetic compatibility, which can have consequences for their mating success and inter-sexual selection processes. We review here recent studies that suggest that the information content of chemosignals of lizards may be reliable because several physiological and endocrine processes would regulate the proportions of chemical compounds available for gland secretions. Because chemosignals are produced by the organism or come from the diet, they should reflect physiological changes, such as different hormonal levels (e.g. testosterone or corticosterone) or different health states (e.g. parasitic infections, immune response), and reflect the quality of the diet of an individual. More importantly, some compounds that may function as chemosignals also have other important functions in the organism (e.g. as antioxidants or regulating the immune system), so there could be trade-offs between allocating these compounds to attending physiological needs or to produce costly sexual “chemical ornaments”. All these factors may contribute to maintain chemosignals as condition-dependent sexual signals, which can inform conspecifics on the characteristics and state of the sender and allow making behavioral decisions with reproductive consequences. To understand the evolution of chemical secretions of lizards as sexual signals and their relevance in reproduction, future studies should examine what information the signals are carrying, the physiological processes that can maintain the reliability of the message and how diverse behavioral responses to chemosignals may influence reproductive success.     

Profiles of toxic and non-toxic oligopeptides of Radiocystis fernandoii (Cyanobacteria) exposed to three different light intensities

Cyanobacteria produce a high variety of bioactive oligopeptides, which function, ecological, physiological roles and responses to environmental changes are still unclear. The influence of light intensity on the cell quota and the diversity of oligopeptides of two strains of the cyanobacterium Radiocystis fernandoii were experimentally tested. The peptides were quantified by HPLC and identified by a MALDI-TOF-TOF. Microcystins (MC) were generally more abundant in the treatment with low light. A compensatory mechanism was observed for the different variants of microcystin, whereby MC-RR responses were contrary to those observed for the other three variants and showed higher concentration in the treatment with intermediate light. Two microviridins were also produced at higher amounts at intermediate irradiance. For cyanopeptolins and a third microviridin no significant difference among treatments was found. The absence of a similar response for all peptides suggests that these compounds may have unique cellular functions, which better understanding could help explaining changes in toxicity. Finally, we observed that each chemical profile reflected in physiological differences between strains, strengthening the idea that chemotypes may act as distinct ecotypes in nature.     

Plant Polyamines in Reproductive Activity and Response to Abiotic Stress*

In this review we will focus on two areas in which the accumulated evidence for a critical physiological role of polyamines is becoming compelling, i.e. reproductive activity and response to abiotic stress. Regarding reproductive behavior, it seems clear that polyamines are members of the array of internal compounds required for flower initiation, normal floral organ morphogenesis, fruit growth and fruit ripening in particular plant species. Abiotic stresses such as osmotic stress can “turn on” arginine decarboxylase (ADC) genes, resulting in a rapid increase in their mRNA levels. Localization of ADC enzyme in the chloroplast suggests a role of PAs in the maintenance of photosynthetic activity during senescence responses induced by osmotic stress. We envisage that the use of transgenic plants and improved molecular probes will resolve in the near future the physiological significance of stress-induced changes in PA metabolism as well as the role of these compounds in reproductive activity.     

Cellular distribution, metabolism and regulation of the xanthine oxidoreductase enzyme system

Xanthine oxidase (EC 1.1.3.22) and xanthine dehydrogenase (EC 1.1.1. 204) are both members of the molybdenum hydroxylase flavoprotein family and represent different forms of the same gene product. The two enzyme forms and their reactions are often referred to as xanthine oxidoreductase (XOR) activity. Physiologically, XOR is known as the rate-limiting enzyme in purine catabolism but has also been shown to be able to metabolize a number of other physiological compounds. Recent studies have also demonstrated its ability to metabolize xenobiotics, including a number of anticancer compounds, to their active metabolites. During the past 10 years, evidence has mounted to support a role for XOR in the pathophysiology of inflammatory diseases and atherosclerosis as well as its previously determined role in ischemia-reperfusion injury. While significant progress has recently been made in our understanding of the physiological and biochemical nature of this enzyme system, considerable work still needs to be done. This paper will review some of the more recent work characterizing the interactions and the factors that influence the interactions of XOR with various physiological and xenobiotic compounds.     

The investigation of the antioxidative properties of the novel synthetic organoselenium compounds in some rat tissues

DMBA (7,12-dimethylbenz[a]anthracene) is a polycyclic aromatic hydrocarbon (PAH) known to cause tumors in rats. Selenium is an essential element with physiological non-enzymatic antioxidant properties. Because of the health problems induced by many environmental pollutants, many efforts have been undertaken in evaluating the relative antioxidant potential of selenium and synthetic organoselenium compounds. In this study, adult female Wistar rats were treated with DMBA and the novel organoselenium compounds (1-isopropyl-3-methylbenzimidazole-2-selenone [SeI] and 1,3-di-p-methoxybenzylpyrimidine-2-selenone [SeII]) in the determined doses. The protective effects of novel synthetic organoselenium compounds (SeI and SeII) against DMBA-induced changes in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) activities and total glutathione (GSH) and malone-dialdehyde (MDA) levels of rat heart and brain were investigated. It was determined that SeI and SeII fully or partially restored enzyme activity. It was also found that lipid peroxidation was also decreased in SeI and SeII treated groups. Consequently, it was determined that novel synthetic organoselenium compounds (SeI and SeII) provided protection of antioxidant activity, and protection against lipid peroxidation measured as MDA in SeI and SeII treated groups was provided by novel synthesized organoselenium compounds. The ability of the organoselenium compounds to prevent oxidative damage induced by DMBA in rats was rationalized.     

Constraints on adaptive mutations in the codling moth Cydia pomonella (L.): measuring fitness trade-offs and natural selection

Adaptive changes in populations encountering a new environment are often constrained by deleterious pleiotropic interactions with ancestral physiological functions. Evolutionary responses of populations can thus be limited by natural selection under fluctuating environmental conditions, if the adaptive mutations are associated with pleiotropic fitness costs. In this context, we have followed the evolution of the frequencies of insecticide-resistant mutants of Cydia pomonella when reintroduced into an untreated environment. The novel set of selective forces after removal of insecticide pressure led to the decline of the frequencies of resistant phenotypes over time, suggesting that the insecticide-adapted genetic variants were selected against the absence of insecticide (with a selective coefficient estimated at 0.11). The selective coefficients were also estimated for both the major cytochrome P450-dependent monooxygenase (MFO) and the minor glutathione S-transferase (GST) systems (0.17 and negligible, respectively), which have been previously shown to be involved in resistance. The involvement of metabolic systems acting both through xenobiotic detoxification and biosynthetic pathways of endogenous compounds may be central to explaining the deleterious physiological consequences resulting from pleiotropy of adaptive changes. The estimation of the magnitude of the fitness cost associated with insecticide resistance in C. pomonella suggests that resistance management strategies exclusively based on insecticide alternations would be unlikely to delay such a selection process.