The Effect of Light Regime on Source–Sink Relations in the Shade-Enduring Ajuga reptans Plant

A quantitative approach to the evaluation of source–sink relations in Ajuga reptans plants grown under the forest canopy (shade plants) and on an open plot (sun plants) was worked out in terms of growth characteristics, CO₂ exchange, and carbon balance. Shade plants developed leaves with the relative and specific areas twice exceeding those of sun plants. Sun plants assimilated more carbon, using a significant part of it for the development of numerous runners. During a day, shade and sun plants produced 0.03 and 0.67 g of substrate, respectively. At the same time, forest (shade) plants spent 48% of assimilates for the respiration, in comparison with plants from the open plot that spent almost 70% of assimilates for respiration as they were greater in size. It was concluded, that light controls source–sink relations, which is a way of realization of the life strategy and a coordination mechanism of functional integrity of the plant organism. Light not only controls photosynthesis (source activity) but morphophysiological characteristics of plants with their hierarchical structure of sinks too.     

Source–Sink Relations in the Organs and Tissues of Silver Birch during Different Scenarios of Xylogenesis

Russian Journal of Plant Physiology - Source–sink relations in the “leaf–stem–root” system at the time of cambial growth were studied in two forms of silver birch:...     

Effects of Light Spectral Quality on Morphogenesis and Source–Sink Relations in Radish Plants

The accumulation of dry matter and the content of major phytohormones in the aboveground and underground plant parts, as well as light curves and the diurnal course of photosynthesis in the leaves were studied in radish (Raphanus sativusL.) plants of different ages that were grown under red (RL) or blue (BL) light. As seen from the rapid increase in plant biomass, the development of storage organs (hypocotyl or tap root) started on the 14th day after the emergence of seedling of the BL plants and on the 21st day for the RL plants. Conversely, RL stimulated biomass accumulation in the aboveground parts (petioles and stems) already in the early stages of plant development. Light spectral quality only slightly affected the activity and the diurnal course of photosynthesis. The GA content was ten times higher in the aboveground parts of the RL plants than those of the BL plants. The hypocotyl of the BL plants contained much higher amounts of cytokinins and IAA than that of the RL plants. The specific responses of the source–sink relations to the light quality were related to the distribution of various phytohormones between the aboveground and underground parts of the plants: RL increased the content of gibberellins (GA) in the aboveground parts of plants, thus increasing their sink activity, whereas BL stimulated the synthesis of cytokinins and IAA in the hypocotyl and enhanced its development. Light quality-specific morphogenetic responses were reversed when plants were treated with exogenous GA or paclobutrazol, an inhibitor of GA synthesis. The treatment of the BL plants with exogenous GA stimulated petiole and hypocotyl elongation and induced stem formation. The treatment of the BL plants with paclobutrazol led to shortened petioles, the flattening of the storage organ, and the disappearance of the stem.     

Source–Sink Relationships in Potato Plants

Russian Journal of Plant Physiology - Using the method of labeled atoms, we investigated the operation of the source–sink system in potato plants grown at the northern border of the...     

The Role of the Sympathoadrenomedullary System in the Formation of Pilot’s Adaptation to Flight Loads

The objective of this study was to evaluate the functions of the sympathoadrenomedullary system and the related psychophysiological reactions of pilots, depending on flying hours on a highly maneuverable aircraft. The study involved 78 volunteer pilots (41 high-maneuverability pilots and 37 bomber and transport aviation pilots). A set of methods was chosen with the possibility of their use according to the principle of comprehensive evaluation of the body functional state under flight loads taken into account. Our results indicate that highly maneuverable aircraft piloting induces a significant activation of the sympathoadrenomedullary system in pilots, compared to bombing and transport aircrafts. This is particularly common to young pilots with the total flying time of less than 1000 h. It has been recorded that changes in adaptation to the effect of flight factors on the body develop with age and flight experience.     

The tree-ring chronology of Scots pine (Pinus sylvestris L.) from the Nesvizh castle XVI–XIX cc. in central Belarus

This article presents for the first time Scots pine tree-ring chronology created from historical timber (XVII–XIX cc.) from central Belarus. The chronology includes 59 tree-ring series which were collected from the different wood structures in the Nesvizh castle. This samples show different stages of the castle renovations. The chronology presented in this paper embraces 222 years covering the period between 1608 and 1829.     

Have We Neglected the Role of Fetal Endothelium in Transplacental Transport?

Maternal‐to‐fetal transfer of nutrient and other substances occurs across the placental barrier (PB) which is made up of endothelial cells (EC) on the fetal side and the syncytiotrophoblast (STB) on the maternal side. Numerous studies were conducted to explore the transport characteristics across the STB layer, which is also considered as the major resistance for maternal‐to‐fetal exchange of materials. In contrast the layer of EC has received very little attention if at all. A recently developed viable co‐culture model of the PB revealed significant resistance of the EC layer for maternal‐to‐fetal transfer of glucose. This argues for a major contribution of the EC to overall transplacental transfer of nutrients. Accordingly, it is recommended to fill the void of knowledge and expand our understanding on the role of the feto‐placental endothelium for transplacental transport characteristics.     

Development of needle retention in Scots pine (Pinus sylvestris) in 1957–1991 in northern and southern Finland

The needle trace method was used to study retrospectively the long-term latitudinal variation in needle retention in Scots pine (Pinus sylvestris L.) in Finland. The mean annual summer needle retention (ANR) along the main stem varied from 3.4 to 6.0 needle sets during the period 1957–1991. The lowest values were observed in southern and the highest in northern Finland. The length of the growing season, expressed as the thermal sum (threshold value +5 °C), was negatively correlated with the mean ANR (r=-0.96). The geographical needle retention pattern (NRP) for the period 1957–1991 showed a clearly increasing trend from 1957 to 1969 (southern Finland) and to 1975 (northern Finland); thereafter, the NRP tended to decrease close to its minimum value recorded in 1991. The general level of the NRP was approximately 5.0 needle sets in northern Finland and 3.5–4.0 needle sets in southern Finland. The NRP, with its 6–12 year cycle for southern Finland, was clearly periodical. Differences in the NRP among the ten stands in southern Finland were small, whereas the said periodicity was missing and the differences were high among the stands in northern Finland. The results indicate that variation in the number of needle sets, viz. defoliation of pines, is a normal phenomenon. The role of net carbon assimilation as a regulator of the number of needle sets is discussed.     

Proteomic Analysis of Rat Hypothalamus Revealed the Role of Ubiquitin–Proteasome System in the Genesis of DR or DIO

Obesity has become a global epidemic, contributing to the increasing burdens of cardiovascular disease and type 2 diabetes. However, the precise molecular mechanisms of obesity remain poorly elucidated. The hypothalamus plays a major part in regulating energy homeostasis by integrating all kinds of nutritional signals. This study investigated the hypothalamus protein profile in diet-induced obese (DIO) and diet-resistant (DR) rats using two dimensional gel electrophoresis (2-DE) combined with MALDI-TOF/TOF–MS analysis. Twenty-two proteins were identified in the hypothalamus of DIO or DR rats. These include metabolic enzymes, antioxidant proteins, proteasome related proteins, and signaling proteins, some of which are related to AMP-activated protein kinase (AMPK) signaling or mitochondrial respiration. Among these proteins, in comparison with the normal-diet group, Ubiquitin was significantly decreased in DR rats but not changed in DIO rats, while Ubiquitin carboxyl-terminal esterase L1 (UCHL-1) was decreased in DIO rats but not changed in DR rats. The expression level of Ubiquitin and UCHL-1 were further validated using Western blot analysis. Our study reveals that Ubiquitin and UCHL-1 are obesity-related factors in the hypothalamus that may play an important role in the genesis of DR or DIO by interfering with the integrated signaling network that control energy balance and feeding.     

On the Role of CD8?T Cells in the Control of Persistent Infections

The control of pathogen density during infections is typically assumed to be the result of a combination of resource limitation (loss of target cells that the pathogen can infect), innate immunity, and specific immunity. The contributions of these factors have been considered in acute infections, which are characterized by having a short duration. What controls the pathogen during persistent infections is less clear, and is complicated by two factors. First, specific immune responses become exhausted if they are subject to chronic stimulation. Exhaustion has been best characterized for CD8 T cell responses, and occurs through a combination of cell death and loss of functionality of surviving cells. Second, new nonexhausted T cells can immigrate from the thymus during the infection, and may play a role in the control of the infection. In this article, we formulate a partial-differential-equation model to describe the interaction between these processes, and use this model to explore how thymic influx and exhaustion might affect the ability of CD8 T cell responses to control persistent infections. We find that although thymic influx can play a critical role in the maintenance of a limited CD8 T cell response during persistent infections, this response is not sufficiently large to play a significant role in controlling the infection. In doing so, our results highlight the importance of resource limitation and innate immunity in the control of persistent infections.     

Modeling the Role of TGF-β in Regulation of the Th17 Phenotype in the LPS-Driven Immune System

Airway exposure levels of lipopolysaccharide (LPS) are known to determine type I versus type II helper T cell induced experimental asthma. While low doses of LPS derive Th2 inflammatory responses, high (and/or intermediate) LPS levels induce Th1- or Th17-dominant responses. The present paper develops a mathematical model of the phenotypic switches among three Th phenotypes (Th1, Th2, and Th17) in response to various LPS levels. In the present work, we simplify the complex network of the interactions between cells and regulatory molecules. The model describes the nonlinear cross-talks between the IL-4/Th2 activities and a key regulatory molecule, transforming growth factor β (TGF-β), in response to high, intermediate, and low levels of LPS. The model characterizes development of three phenotypes (Th1, Th2, and Th17) and predicts the onset of a new phenotype, Th17, under the tight control of TGF-β. Analysis of the model illustrates the mono-, bi-, and oneway-switches in the key regulatory parameter sets in the absence or presence of time delays. The model also predicts coexistence of those phenotypes and Th1- or Th2-dominant immune responses in a spatial domain under various biochemical and bio-mechanical conditions in the microenvironment.     

BRAIN-DAMAGED CHILDREN—The Problem of Relations in the Family Group

Children with minimal brain damage show a characteristic pattern of behavior.Often there are no physical signs of abnormality, but the diagnosis can be made from the history, electroencephalographic tracings, psychologic tests and repeated observations.The behavior is a composite of the effects of the brain damage and the response of the child to his environment. The behavior of the brain-damaged child is frequently so frustrating to parents that attitudes of rejection, withdrawal or excessive punitive measures occur.In the present study, when drugs were given and the child''s behavior improved, the parents were better able to understand the needs of the child and create a better home environment in which there was less frustration and emotional pressure.     

UV-B induction of flavonoid biosynthesis in Scots pine (Pinus sylvestris L . ) seedlings

 Cultivation of Scots pine (Pinus sylvestris L.) seedlings under simulated global radiation including the UV-B band (280 – 320 nm; 220 mW m^–2 UV-B_BE) led to increased formation of the diacylated flavonol glucosides 3″,6″-di-p-coumaroyl-astragalin and 3″,6″-di-p-coumaroyl-isoquercitrin in primary and cotyledonary needles, respectively. 3″,6″-Di-p-coumaroyl-astragalin was also the main constitutive diacylated flavonol glucoside in both needle types. This compound predominantly accumulated in primary needles upon UV-B irradiation, and reached concentrations of 2.4 μmol g^–1 fresh weight (fw). Its concentration was only weakly affected in cotyledonary needles. 3″,6″-Di-p-coumaroyl-isoquercitrin was mainly induced in cotyledonary needles with maximum concentrations of 0.8 to 0.9 μmol g^–1 fw, but was virtually unaffected in primary needles under the same irradiation conditions. Pulse labelling with L-(U-¹⁴C)phenylalanine revealed that these metabolites were formed de novo. Phenylalanine ammonia-lyase (EC 4.3.1.5) and chalcone synthase (EC 2.3.1.74) were only slightly induced by the UV-B treatment. The results described here represent the first report on UV-B-induced flavonoid biosynthesis in a conifer species. Received: 5 December 1995 / Accepted: 20 March 1996     

The rôle of the tapetum in the formation of sporopollenin-containing structures during microsporogenesis in Pinus banksiana

Summary In the microsporangium of Pinus the outer layer of the peritapetal membrane and the pro-orbicular cores are not only formed in a similar manner, but are composed of apparently identical materials. Precursors for this lipoidal material are produced by the tapetal protoplasts, as are the precursors of sporopollenin. Production the precursors is sequential and appears to involve different cytoplasmic structures.The sporopollenin synthesised by the tapetum condenses upon the pro-orbicular cores, the peritapetal membrane, the exine initials and, on fragmentation of the tapetum, parts of the disintegrating cytoplasm. The evident unpolarised nature of the tapetal protoplasts, and the sequential nature of the synthesis of the lipoid and the sporopollenin by them, may point to orbicule formation in gymnosperms being a necessary by-product of the development of the peritapetal membrane.     

Contacts in Death: The Role of the ER–Mitochondria Axis in Acetic Acid-Induced Apoptosis in Yeast

Endoplasmic reticulum–mitochondria contact sites have been a subject of increasing scientific interest since the discovery that these structures are disrupted in several pathologies. Due to the emerging data that correlate endoplasmic reticulum–mitochondria contact sites function with known events of the apoptotic program, we aimed to dissect this interplay using our well-established model of acetic acid-induced apoptosis in Saccharomyces cerevisiae. Until recently, the only known tethering complex between ER and mitochondria in this organism was the ER–mitochondria encounter structure (ERMES). Following our results from a screening designed to identify genes whose deletion rendered cells with an altered sensitivity to acetic acid, we hypothesized that the ERMES complex could be involved in cell death mediated by this stressor. Herein we demonstrate that single ablation of the ERMES components Mdm10p, Mdm12p and Mdm34p increases the resistance of S. cerevisiae to acetic acid-induced apoptosis, which is associated with a prominent delay in the appearance of several apoptotic markers. Moreover, abrogation of Mdm10p or Mdm34p abolished cytochrome c release from mitochondria. Since these two proteins are embedded in the mitochondrial outer membrane, we propose that the ERMES complex plays a part in cytochrome c release, a key event of the apoptotic cascade. In all, these findings will aid in targeted therapies for diseases where apoptosis is disrupted, as well as assist in the development of acetic acid-resistant strains for industrial processes.     

The Role of Gap Junctions in Endothelial–Stromal Cell Interactions

Human Physiology - Gap junctions are one of the most highly specialized intercellular communications providing not only electrical coupling but also metabolic cooperation between cells due to the...