Activity In Different Organs Research Articles

Immunoreactivity for thymosin beta 4 and thymosin beta 10 in the adult rat oro-gastro-intestinal tract

Thymosin beta 4 (Tβ4) and thymosin beta 10 (Tβ10) are two members of the β-thymosin family, involved in multiple cellular activities in different organs in multiple animal species. Here we report the expression pattern of Tβ4 and Tβ10 in rat tissues, in the gut and in annexed glands. The two peptide were differently expressed: Tβ4 was absent in salivary glands whereas Tβ10 was expressed in parotid and in submandibular glands. Tβ4 was mildly expressed in the tongue and in the esophagus, where Tβ10 was absent. A similar expression was found in the stomach, ileum and colon mucosa. In pancreas Tβ4 reactivity was restricted to the Langerhans islet cells; Tβ4 was also detected in the exocrine cells. Both peptide were not expressed in liver cells. When the rat expression pattern in rat organs was compared to reactivity for Tβ4 and Tβ10 in humans, marked differences were found. Our data clearly indicate a species-specific expression of Tβ4 and Tβ10, characterized by the actual unpredictability of the expression of these peptides in different cells and tissues. The common high expression of Tβ4 in mast cells, both in humans and in rats, represents one of the few similarities between these two species.

Exogenous Nitric Oxide Enhances Root Activity, Decreases H2O2 Accumulation by Increasing Activities of CAT and GR in Root of Potato cv. Desiree under Water-stress

We studied water content, H₂O₂ content, antioxidant enzymes activities of different organs and root activity in potato cv. Desiree pretreated with NO under water-stress. It was found that the bound water content in root and root activity was significantly increased by treating NO before water-stress. Pretreatment with NO decreased the H₂O₂ content and raised activities of CAT and GR significantly in roots under water-stress. The results suggested that NO might enhance the resistance to water-stress in potato.

Alterations induced by imazamox on acetohydroxyacid synthase activity of common bean (Phaseolus vulgaris) depend on leaf position

Imazamox is a selective herbicide applied in a wide spectrum of crops which belongs to the imidazolinone family, which mode of action is related to the inhibition of acetohydroxyacid synthase activity. The effect of this herbicide on plant growth, amino acids balance as well as the rate of inhibition of acetohydroxyacid synthase activity in different organs of common bean was studied. Our results indicated that total plant dry weight was not significantly affected two and seven days after herbicide application. Acetohydroxyacid synthase activity decreased in young tissues in response to imazamox treatments, whereas in mature organs the herbicide reversed the natural decrease of activity linked to ripeness. In shoot apical meristem and fully expanded leaves isoleucine content increased, while valine and leucine decreased less than expected considering the decline of acetohydroxyacid synthase activity, at less in young tissues. The results suggest that the herbicide is transported primarily to the growing areas where exerts its action by inhibiting the acetohydroxyacid synthase. Results found here allow to progress in the knowledge about legumes responses to imazamox herbicide.

Important photosynthetic contribution from the non-foliar green organs in cotton at the late growth stage

Non-foliar green organs are recognized as important carbon sources after leaves. However, the contribution of each organ to total yield has not been comprehensively studied in relation to the time-course of changes in surface area and photosynthetic activity of different organs at different growth stages. We studied the contribution of leaves, main stem, bracts and capsule wall in cotton by measuring their time-course of surface area development, O(2) evolution capacity and photosynthetic enzyme activity. Because of the early senescence of leaves, non-foliar organs increased their surface area up to 38.2% of total at late growth stage. Bracts and capsule wall showed less ontogenetic decrease in O(2) evolution capacity per area and photosynthetic enzyme activity than leaves at the late growth stage. The total capacity for O(2) evolution of stalks and bolls (bracts plus capsule wall) was 12.7 and 23.7% (total ca. 36.4%), respectively, as estimated by multiplying their surface area by their O(2) evolution capacity per area. We also kept the bolls (from 15 days after anthesis) or main stem (at the early full bolling stage) in darkness for comparison with non-darkened controls. Darkening the bolls and main stem reduced the boll weight by 24.1 and 9%, respectively, and the seed weight by 35.9 and 16.3%, respectively. We conclude that non-foliar organs significantly contribute to the yield at the late growth stage.

Phenolic amounts, antioxidant and antimicrobial potential of Crithmum maritimum cultivated in Tunisian arid zones

Polyphenols are bioactive molecules exhibiting a lot of scientific attention due to their multiple biological activities. The present study aimed at assessing the phenolic content, antimicrobial and antioxidant activities of different organs (leaves, flowers, seeds and stems) of Crithmum maritimum L. cultivated in the south east of Tunisia (Medenine).

An experimental model to study the effects of a senna extract on the blood constituent labeling and biodistribution of a radiopharmaceutical in rats

ABSTRACT Cassia angustifolia Vahl (senna) is a natural product that contains sennosides, which are active components that affect the intestinal tract and induce diarrhea. Authors have shown that senna produces DNA (deoxyribonucleic acid) lesions in Escherichia coli cultures and can act as an antifungal agent. Natural drugs can alter the labeling of blood constituents with technetium-99m (99mTc) and can affect the biodistribution of radiopharmaceuticals. In this work, we have evaluated the influence of a senna extract on the radiolabeling of blood constituents and on the biodistribution of the radiopharmaceutical sodium pertechnetate (Na99mTcO4) in Wistar rats. Twelve animals were treated with senna extract for 7 days. Blood samples were withdrawn from the animals and the radiolabeling procedure was carried out. The senna extract did not modify the radiolabeling of the blood constituents. A biodistributional assay was performed by administering Na99mTcO4 and determining its activity in different organs and in blood. The senna extract altered the biodistribution of Na99mTcO4 in the thyroid, liver, pancreas, lungs and blood. These results are associated with properties of the chemical substances present in the aqueous senna extract. Although these assays were performed in animals, our findings suggest that caution should be exercised when nuclear medicine examinations using Na99mTcO4 are conducted in patients who are using senna extract.

Distribution and Dynamics of 99mTc-Pertechnetate Uptake in the Thyroid and Other Organs Assessed by Single-Photon Emission Computed Tomography in Living Mice

(99m)Tc pertechnetate is a well-known anion, used for clinical imaging of thyroid function. This gamma emitter is transported by the sodium iodide symporter but is not incorporated into thyroglobulin. Scintigraphy using (99m)Tc pertechnetate or (123)iodide represents a powerful tool for the study of sodium iodide symporter activity in different organs of living animal models. However, in many studies that have been performed in mice, the thyroid could not be distinguished from the salivary glands. In this work, we have evaluated the use of a clinically dedicated single-photon emission computed tomography (SPECT) camera for thyroid imaging and assessed what improvements are necessary for the development of this technique. SPECT of the mouse neck region, with pinhole collimation and geometric calibration, was used for the individual measurement of (99m)Tc pertechnetate uptake in the thyroid and the salivary glands. Uptake in the stomach was studied by planar whole-body imaging. Uptake kinetics and biodistribution studies were performed by sequential imaging. This work has shown that thyroid imaging in living mice can be performed with a SPECT camera originally built for clinical use. Our experiments indicate that (99m)Tc pertechnetate uptake is faster in the thyroid than in the salivary glands and the stomach. The decrease in (99m)Tc pertechnetate uptake after injection of iodide or perchlorate as competitive inhibitors was also studied. The resulting rate decreases were faster in the thyroid than in the salivary glands or the stomach. We have shown that a clinically dedicated SPECT camera can be used for thyroid imaging. In our experiments, SPECT imaging allowed the analysis of (99m)Tc pertechnetate accumulation in individual organs and revealed differences in uptake kinetics.

Patient-specific internal radionuclide dosimetry

The development of patient-specific treatment planning systems is of outmost importance in the development of radionuclide dosimetry, taking into account that quantitative three-dimensional nuclear medical imaging can be used in this regard. At present, the established method for dosimetry is based on the measurement of the biokinetics by serial gamma-camera scans, followed by calculations of the administered activity and the residence times, resulting in the radiation-absorbed doses of critical organs. However, the quantification of the activity in different organs from planar data is hampered by inaccurate attenuation and scatter correction as well as because of background and organ overlay. In contrast, dosimetry based on quantitative three-dimensional data can be more accurate and allows an individualized approach, provided that all effects that degrade the quantitative content of the images have been corrected for. In addition, inhomogeneous organ accumulation of the radionuclide can be detected and possibly taken into account. The aim of this work is to provide adequate information on internal emitter dosimetry and a state-of-the-art review of the current methodology and future trends.

Toxic Effect and Biochemical Study of Chlorfluazuron, Oxymatrine, and Spinosad on Honey Bees (Apis mellifera)

Under laboratory conditions, the comparative effects of two insect growth regulators, chlorfluazuron and oxymatrine, and spinosad as a biopesticide were examined on honey bee workers (Apis mellifera L.). Separate groups of bees were left for 24 h to feed on 50% sucrose solution containing different concentrations of the tested insecticides, and the lethal concentration that caused 50% mortality (LC(50)) was estimated. The inhibitory effects on acetylcholinesterase (AChE) and adenosine triphosphatase (ATPase) activities as biochemical indicators were determined in vivo after 24 h in head, thorax, and abdomen of surviving bees obtained after treatments with a view to explore the possible mode of action of these compounds. Results indicated that exposure to spinosad showed toxicity to honey bees with LC(50) value of 7.34 mg L(-1), followed by oxymatrine (LC(50) = 10.68 mg L(-1)), while chlorfluazuron was the least acutely toxic of the tested compounds (LC(50) = 2,526 mg L(-1)). Oxymatrine and spinosad at the same tested concentrations (2.5, 5, 10, and 20 mg L(-1)) significantly inhibited AChE activity in different organs of honey bee workers, and high inhibition percentage was obtained with the enzyme isolated from the thorax. However, chlorfluazuron at 400, 1,000, 2,000, and 4,000 mg L(-1) caused high inhibition of AChE activity isolated from the head (39.65% and 44.22% at 2,000 and 4,000 mg L(-1), respectively). In addition, the toxic effects of the tested compounds on activity of ATPase indicated that spinosad caused the highest inhibitory effect in different organs compared with oxymatrine at the same concentrations, and high inhibition was found with ATPase isolated from the head. The results also indicated that oxymatrine was the least active compound for inhibition of AChE and ATPase.

Effects of Soil Texture on Activities of SPS, SS, and Relationship with Starch Accumulation during Grain Filling in Wheat

A wheat (Triticum aestivum L.) cultivar, Yumai 49 was used in a pool experiment to investigate the activities of key enzymes involved in sucrose metabolism in leaf, sheath, stem, and grain during grain filling in clay-loam, mid-loam, and sand-loam soils. The changes of sucrose phosphate synthase (SPS) and sucrose synthase (SS) activities in different organs during grain filling in three types of soil showed a single-peak curve. In the sand-loam soil, SPS activities were the highest in different organs expect grains. In the mid-loam soil, the SPS activity in grains at the early filling stage and the SS activity at the medium-to-late filling stages were significantly higher than those in the clay-loam soil. The 1000-grain weight and starch content in the mid-loam soil and sand-loam soil were significantly highter than those in the clay-loam soil, but those were not significantly different between mid-loam soil and sand-loam soil. This showed that the mid-loam soil and sand-loam soil could affect the sucrose synthesis and degradation in Yumai 49. The sand-loam soil was available for sucrose synthesis in the vegetative organs of wheat, but the mid-loam soil was available for sucrose synthesis in grains of wheat. The SPS and SS activities all correlated significantly or very significantly with grain filling rate, amylopectin and starch accumulation rates in grains in the mid-loam soil and sand-loam soil, but the correlation between the enzymes activities, expect SPS activities in grains, and starch accumulation rate was not significant. It is more important for the sucrose synthesis catalyzed by SPS in the vegetative organs and the sucrose degradation catalyzed by SS in grains to accumulate the starch and amylopectin in grains of wheat in the mid-loam soil and sand-loam soil.

Regularory elements of the copia retrotransposon determine different levels of expression in different organs of males and females of Drosophila melanogaster

Using a model system in which the expression of the reporter gene lacZ is under the control of five deleted variants of the copia retrotransposon regulatory region, which includes the 5'-long terminal repeat (LTR) and the 5'-untranslated region (5'-UTR), their contribution to the control of retrotransposon activity in different organs of males and females of Drosophila melanogaster was analyzed. The whole regulatory region provides expression of the reporter gene at the embryonic stage, and in larvae and adult flies only in generative organs. The 5'-end of LTR harbors a positive regulator that determines expression of the retrotransposon in organs of all types. The 3'-end of LTR harbors a negative regulator, which is sex- and time-specific: it represses copia expression in generative organs of males at all stages of development, and only at the imaginal stage in somatic tissues, without any effect on the expression of the retrotransposon in females. 5'-UTR contains a negative regulator of copia expression: it decreases the expression in embryos and generative organs and blocks it in somatic tissues. It may be suggested that a complex set of regulatory elements was formed in the course of the evolution of the retrotransposon, which made it possible to maintain a certain level of its expression in different types of cells and tissues and at different stages of development and, thus, to limit the harm caused to the host and provide the possibility for the retrotransposon to exist in the host genome over many generations.

Detection of chitinolytic enzymes with different substrate specificity in tissues of intact sundew (Drosera rotundifolia L.)

The round-leaf sundew (Drosera rotundifolia L.) is a carnivorous plant expressing a wide range of chitinolytic enzymes playing role in many different processes. In this study the intact plants were analyzed for the presence of chitinase transcripts and chitinolytic activities in different organs. In situ hybridization with chitnase fragment as a probe has revealed the presence of chitinases in the mesophyll cells of leaves and vascular elements of stems of healthy, non-stressed plants. More pronounced expression was observed in cortex and stele cells of roots as well as in ovules and anthers of reproductive organs. Similarly, higher chitinase enzyme activity was typical for flowers and roots suggesting a more specific role of chitinases in these tissues. In addition to endochitinases of different substrate specificities, chitobiosidases contributed to overall chitinolytic activity of tissue extracts. The activity of chitobiosidases was again typical for flowers and roots, while their role in plant physiology remains to be elucidated.

Age-related decrease in cardiopulmonary adrenergic neuronal function in children as assessed by I-123 metaiodobenzylguanidine imaging

Radioiodinated metaiodobenzylguanidine (MIBG) imaging has been used to evaluate adrenergic nerve activity in different organs. Cardiac and pulmonary MIBG uptake is important in predicting the prognosis of certain cardiopulmonary diseases. It has been reported that cardiac MIBG uptake decreases with age and is significantly lower in the elderly. However, there has been no systemic study on age-related changes in cardiac and pulmonary MIBG uptake in children. This study was undertaken to determine the changes in MIBG uptake in the developing heart and lung in children and adolescents. MIBG scans of 44 children (16 female and 28 male; age range, 2 months to 19 years) without abnormal uptake were selected from a large pool of patients with whole-body MIBG imaging performed for evaluation of neuroblastoma. All of the selected subjects had a normal physiologic distribution of MIBG and no history of heart or lung diseases. The patients were divided into 4 groups by age: group 1, 0 to 24 months; group 2, 25 to 48 months; group 3, 49 to 72 months; and group 4, 73 months or greater. Cardiac and pulmonary MIBG uptake values (expressed as heart-to-mediastinum [H/M] ratio and lung-to-mediastinum [L/M] ratio, respectively) were determined and compared among the 4 groups. H/M and L/M ratios were noted to decrease with age. The mean H/M and L/M ratios were in group 1, 4.13 +/- 0.66 and 1.53 +/- 0.18, respectively; in group 2, 3.46 +/- 0.71 and 1.26 +/- 0.18, respectively; in group 3, 3.19 +/- 0.94 and 1.13 +/- 0.17, respectively; and in group 4, 2.84 +/- 0.48 and 1.14 +/- 0.14, respectively. There was a significant inverse correlation between H/M ratio and age (r = 0.711, P < .001) as well as between L/M ratio and age (r = 0.718, P < .001). Cardiac and pulmonary MIBG uptake is inversely related to age in children.

INTESTINAL ISCHEMIA-REPERFUSION-INDUCED ACUTE LUNG INJURY AND ONCOTIC CELL DEATH IN MULTIPLE ORGANS

Most acute respiratory distress syndrome studies have been focused on the lung injury. Little is known about other organs during the development of acute respiratory distress syndrome. Herein, we investigated the injury and cell death in multiple organs after intestinal ischemia-reperfusion (IIR) in C57BL/6 mice. Terminal transferase dUTP nick end labeling staining was used as a marker of cell death. Caspase 3 and cathepsin B activation as markers of caspase-dependent and caspase-independent apoptosis, respectively, and electron microscopy for ultimate characterization of cell death were used. In comparison with control and sham-operated mice, the IIR group showed interstitial inflammatory infiltrates in the lung and significant increases of lung injury parameters and plasma lactate dehydrogenase and aspartate aminotransferase levels. Terminal transferase dUTP nick end labeling-positive cells and immunostaining for hemeoxygenase 1, an enzyme induced by inflammatory stimuli, were increased in the lung, heart, and kidney, but not in the liver. The number of hemeoxygenase 1-positive cells positively and significantly correlated to the number of terminal transferase dUTP nick end labeling-positive cells. Cell death was not associated with caspase 3 or cathepsin B activation. Electron microscopy showed morphological features compatible with oncotic rather than apoptotic cell death or necrosis, including mitochondrial swelling and cytoplasm disorganization in pulmonary and renal epithelial cells, lung and cardiac endothelial cells, and myocytes. These results indicate that, although lung injury is the most significant manifestation after IIR, oncotic cell death occurs in the lung, heart, and kidney, which may be related to ischemia and inflammation.

Exciting News from the Messenger

“These chemical messengers, however, or hormones (from [the Greek word] I excite or arouse), as we might call them, have to be carried from the organ where they are produced to the organ which they affect by means of the blood stream and the continually recurring physiological needs of the organism must determine their repeated production and circulation throughout the body.” As part of his second Croonian lecture to the Royal College of Surgeons in 1905 entitled “The chemical control of the functions of the body”, Ernest Starling surprisingly introduces the term “hormones” to describe chemicals that can be set into action in the blood stream to elicit activity in different organs of the body. The selection of the term “hormone” by Starling is not entirely clear, but may have developed in conversations with William Hardy and the Greek poet scholar W. T. Vesey to use the Greek verb “ormao” for “arouse” or “excite”. Yet, despite the absence, or at least the minimal use of the term “hormone” in the scientific arena prior to this point, early work during the mid-nineteenth century, such as by Claude Bernard, depicted processes responsible for internal secretion of chemicals as described with the release of glucose from glycogen in the liver. During this period, other pioneers such as Arnold Adolphe Berthold spoke of the interaction and communication between the different organs in the body. As these concepts became more accepted, physicians later in the nineteenth century reported the use of extracts of animal thyroid, pancreas, and even adrenal glands to treat patients suspected of suffering from the loss of circulating chemicals. By the early twentieth century, Starling and William Bayliss demonstrated that the duodenum, when stimulated with acid through local application, could lead to pancreatic secretion. They furthered these results by illustrating that duodenal extracts injected into the blood stream in animals also resulted in pancreatic secretion. From these studies, Starling and Bayliss suggested that the agent released from the duodenum should be termed “secretin”. The Nobel Laureate Pavlov was initially impressed with these results that had suggested the presence of several mechanisms in the control of the digestive system, but later stood firm to promote his personal concepts that pancreatic secretion and the organs of the gut were controlled principally by innervation of the nervous system during his acceptance of the Nobel Peace Prize for his work in 1904. Politics aside, investigations since the work of early pioneers in endocrinology and the study of hormones have fostered the development of numerous fields that involve vascular biology, neuroscience, physiology, genetics, metabolomics, development, cancer, and molecular medicine. Clinically, the advances from these fields that rely upon the understanding of the chemistry of hormones have resulted in remarkable strides for treatment protocols that involve the care and management of diabetes, the replenishment of hormone deficiencies with recombinant proteins that eliminate potential toxicity from the use of animal or human sources, and the success of fertility treatments that utilize in vitro fertilization. Furthermore, our progressive knowledge of the cellular and molecular processes that involve hormones have alerted us to the intimate relationship we hold with the environment and its accumulation of synthetic chemicals that can ultimately be detrimental to the endocrine system of both animals and humans. This issue of Current Neurovascular Research highlights the complexity of hormones and the cellular pathways they govern that ultimately regulate clinical health and disease. Ahmadi et al. provides exciting evidence that administration of a bone marrow cell population containing multipotent stem cells is not only non-toxic in patients who have suffered myocardial infarction, but also may result in clinical cardiac improvement with potential myogenesis and angiogenesis. However, hormonal systems may not always be beneficial during illness as illustrated by Makikallio et al. In their paper, they examined the hypothalamus-pituitary-adrenal axis in patients suffering from ischemic stroke over time and report that elevated cortisol and natriuretic peptide levels may be detrimental to the eventual recovery from stroke, suggesting that targeting this hormone system may offer treatment for acute cerebral ischemia.....

Use of isotopes in the diagnosis of hematopoietic disorders

Isotopes of iron have been paramount in clinical tracer studies of hematopoiesis. Kinetics of disappearance from plasma, appearance in circulating erythrocytes, and localization in general areas of bone marrow, spleen, and liver were early revealed by gamma-/beta-emitting Fe-59 with note of characteristic differences of kind and degree of dysfunction among various anemias. Findings have helped in management (e.g., decisions about splenectomy). Positron/gamma-emitting Fe-52 (better for imaging) has provided more detail on marrow expansion and erythropoietic relocation. Other gamma-emitting tracers of hematopoiesis have been In-111 (linked to transferrin) and technetium 99m (Tc-99m) colloids (localizing to reticuloendothelial cells, which have close association with blood cell progenitors), but Fe-52 has proved to be more accurate for recognition of erythropoiesis. Occasional diverse heterotopic sites of hematopoiesis beyond spleen and liver in states of bone marrow disease have posed diagnostic challenges and also raised questions about migration and/or activation of stem cells. Studies of granulopoiesis utilize Tc-99m--labeled leukocytes or Tc99m-labeled antibodies to circulating and progenitor white cells. Iron-deficiency anemias due to malnutrition, malabsorption, blood loss, or special need are explored by dual study (oral vs intravenous) with radioactive (Fe-59, Fe-55) or stable (Fe-54, Fe-57) iron isotopes, which can guide dietary supplementation. Tests for B-12 deficiency in pernicious anemia or malabsorption with radioisotopes of cobalt (Co-57, Co-58) have been upgraded in sensitivity and scope. Rates of oxidation to expired carbon dioxide from particular carbon (radioactive C-14 or stable C-13)--labeled compounds can test B-12 or folic acid deficiencies or gastric infestation as causes of megaloblastic anemias.

Glutathione conjugates in the vacuole are degraded by γ‐glutamyl transpeptidase GGT3 in Arabidopsis

gamma-Glutamyl transpeptidase (GGT) is the enzyme responsible for breaking the gamma-glutamyl bond between Glu and Cys in glutathione (GSH). We are using this gene family to study GSH degradation in plants. There are four putative GGT genes in Arabidopsis, and one of them, GGT3 (At4g29210), is analyzed in this study. GGT3 is localized to the vacuole based on organelle-targeting programs, subcellular distribution of GFP fusion proteins during transient expression in onion (Allium cepa) epidermal tissues, and its ability to metabolize vacuolar substrates in Arabidopsis plants. While Northern blots and promoter:GUS expression patterns have suggested that GGT3 is transcribed at relatively high levels in all parts of the plant, a comparison of enzyme activities in different organs of wild-type and a ggt3 knockout mutant showed that GGT3 was a major contributor to total GGT activity in roots, but a relatively minor contributor in other tissues. Wild-type Arabidopsis plants treated with monobromobimane (mBB) form a fluorescent GSH-mBB conjugate that is moved into the vacuole and then metabolized to Cys-Gly-mBB and Cys-mBB in that order. The first step is catalyzed by GGT3, and GSH-mBB metabolism is completely blocked in the roots of ggt3 knockout plants. In ggt3 leaves, some GSH-mBB metabolism still proceeds using the apoplastic GGT1. This identifies GGT3 as catalyzing the obligate initial step in GSH conjugate metabolism, and suggests that it has an important role in protecting plants from some xenobiotic chemicals.

Diabetes modulates differentially creatine kinase‐specific activity responsiveness to estradiol‐17β and to raloxifene in rat organs

Diabetes mellitus increases the risk for CVD in women. While there is considerable evidence suggesting beneficial effects of estrogen on decreasing lipid peroxidation, atherosclerotic processes, and cardiovascular diseases, diabetes negates most estrogen protective effects as well as the skeletal protective effects of estrogens, which are not discernable in diabetic women. In the present study, we examined the in vivo effects of estradiol-17beta (E2), on creatine kinase (CK)-specific activity, in estrogen-responsive organs from healthy and diabetic rats. Healthy or diabetic (streptozotocin-induced) female rats were injected with either E2 (10-50 microg/rat) or raloxifene (Ral; 500-1,000 microg/rat). Twenty-four hours following the injection, animals were sacrificed; their organs removed and assayed for CK-specific activity. CK-specific activity in different organs [Left ventricle of heart (Lv), uterus (Ut), aorta (Ao), para uterine adipose tissue (Ad), epiphyseal cartilage (Ep), and diaphyseal bone (Di)] from healthy animals, was stimulated with increased doses of E2, with maximum at 20 microg/rat. Age-matched diabetic female rats exhibited a remarkable decreased response to E2 in all organs except Ut. In contrast, the response to Ral was not altered in diabetic rats. Similar results were observed in organs from ovariectomized female rats (Ovx), healthy or diabetic. These results support our previous in vitro findings, demonstrating that hyperglycemia decreases CK response to E2 but not to Ral in cultured human vascular and bone cells. In summary, diabetes mellitus decreases CK response to E2 but not that of Ral in skeletal and vascular tissues. The decreased response to E2 detected in organs derived from diabetic rats might be due to changes in nuclear and/or membrane estrogen receptors and/or other genomic and non-genomic pathways, as was shown in in vitro cellular models.

Constitutive arginine-dependent nitric oxide synthase activity in different organs of pea seedlings during plant development

Nitric oxide (NO) is an important signalling molecule in different animal and plant physiological processes. Little is known about its biological function in plants and on the enzymatic source or site of NO production during plant development. The endogenous NO production from L-arginine (NO synthase activity) was analyzed in leaves, stems and roots during plant development, using pea seedlings as a model. NOS activity was analyzed using a novel chemiluminescence-based assay which is more sensitive and specific than previous methods used in plant tissues. In parallel, NO accumulation was analyzed by confocal laser scanning microscopy using as fluorescent probes either DAF-2 DA or DAF-FM DA. A strong increase in NOS activity was detected in stems after 11 days growth, coinciding with the maximum stem elongation. The arginine-dependent NOS activity was constitutive and sensitive to aminoguanidine, a well-known irreversible inhibitor of animal NOS, and this NOS activity was differentially modulated depending on the plant organ and seedling developmental stage. In all tissues studied, NO was localized mainly in the vascular tissue (xylem) and epidermal cells and in root hairs. These loci of NO generation and accumulation suggest novel functions for NO in these cell types.

Phylogenetic relationship of potato CAT1 and CAT2 genes, their differential expression in non-photosynthetic organs and during leaf development, and their association with different cellular processes.

Plants contain multiple forms of catalase (CAT) and their specific functions remain uncertain. We cloned two potato cDNAs corresponding to CAT1 and CAT2 genes, analysed their phylogenetic relationship, and studied their expression and activity in different organs to gain clues to their functions. Phylogenetic trees and the alignment of CAT cDNA sequences provided evidence that CAT1 and CAT2 genes have high identity to catalases of other solanaceous species, but are not phylogenetically closely related to one another, which contradicts the phylogenetic closeness ascribed to these genes. Northern blot analyses revealed that expression of CAT genes is controlled by leaf developmental phase. CAT2 expression was higher in both very young and senescent leaves, whereas CAT1 mRNA accumulated mainly in mature leaf, where the lowest CAT2 expression occurred. CAT1 and CAT2 are also differentially expressed in root, sprout and petal. Expression and activity patterns are consistent with different physiological roles for CAT1 and CAT2 isoforms. CAT1 is considered to be associated with photorespiration whereas CAT2 would fulfill physiological roles unrelated to this process. CAT2 appears to be a multifunctional isoform, associated with glyoxysomal activity in leaf senescence, other processes in non-photosynthetic organs and defence, functions that in other solanaceous species are fulfilled by two different isoforms.