Metabolic adaptations to environmental changes in Caenorhabditis elegans

Metabolic adaptations to environmental changes were studied in Caenorhabditis elegans. To assess adjustments in enzyme function, maximum activities of key enzymes of main metabolic pathways were determined. After a 12 h incubation at varying temperatures (10, 20°C) and oxygen supplies (normoxia or anoxia), the activities of the following enzymes were determined at two measuring temperatures in tissue extracts: lactate dehydrogenase (LDH; anaerobic glycolysis), 3-hydroxyacyl-CoA-dehydrogenase (HCDH; fatty acid oxidation), isocitrate dehydrogenases (NAD-IDH, NADP-IDH; tricarboxylic acid cycle) and isocitrate lyase (ICL; glyoxylate cycle). Incubation at 20°C induced a strong increase in maximum LDH activity. Anoxic incubation caused maximum HCDH and NADP-IDH activities and, at 10°C incubation, LDH activity to increase. Maximum NAD-IDH and ICL activities were not influenced by any type of incubation. In order to study the time course of metabolic adaptations to varying oxygen supplies, relative quantities of free and protein-bound NADH were determined in living C. elegans using time-resolved fluorescence spectroscopy. During several hours of anoxia, free and protein-bound NADH showed different time courses. One main result was that just at the moment when the protein-bound NADH had reached a constant level, and the free NADH started to increase rapidly, the worms fell into a rigor state. The data on enzyme activity and NADH fluorescence can be interpreted on the basis of a two-stage model of anaerobiosis.     

The environmental contribution to gene expression profiles

Microarray analysis provides a bridge between the molecular genetic analysis of model organisms in laboratory settings and studies of physiology, development, and adaptation in the wild. By sampling species across a range of environments, it is possible to gain a broad picture of the genomic response to environmental perturbation. Incorporating estimates of genetic relationships into study designs will facilitate genomic analysis of environmental plasticity by aiding the identification of major regulatory loci in natural populations.     

Morphological and biochemical adaptations to feeding in some herbivorous gastropods

Feeding range and modes as well as morphological and biochemical adaptations to feeding are analyzed in herbivorous mollusks. The content of hemoglobin in radular tissues and weight properties of the radula are evaluated for different modes of feeding.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 1, 2005, pp. 69–77.Original Russian Text Copyright © 2005 by Alyakrinskaya.     

Skeletal muscle biochemical adaptations to exercise training in miniature swine

McAllister, Richard M., Brian L. Reiter, John F. Amann, andM. Harold Laughlin. Skeletal muscle biochemical adaptations toexercise training in miniature swine. J. Appl.Physiol. 82(6): 1862-1868, 1997.The primarypurpose of this study was to test the hypothesis that enduranceexercise training induces increased oxidative capacity in porcineskeletal muscle. To test this hypothesis, female miniature swine wereeither trained by treadmill running 5 days/wk over 16-20 wk (Trn;n = 35) or pen confined (Sed;n = 33). Myocardialhypertrophy, lower heart rates during submaximal stages of a maximaltreadmill running test, and increased running time to exhaustion duringthat test were indicative of training efficacy. A variety of skeletalmuscles were sampled and subsequently assayed for the enzymes citratesynthase (CS), 3-hydroxyacyl-CoA dehydrogenase, and lactatedehydrogenase and for antioxidant enzymes. Fiber type composition of arepresentative muscle was also determined histochemically. The largestincrease in CS activity (62%) was found in the gluteus maximus muscle(Sed, 14.7 ± 1.1 µmol · min¹ · g¹;Trn, 23.9 ± 1.0; P < 0.0005).Muscles exhibiting increased CS activity, however, were locatedprimarily in the forelimb; ankle and knee extensor and respiratorymuscles were unchanged with training. Only two muscles exhibited higher3-hydroxyacyl-CoA dehydrogenase activity in Trn compared with Sed.Lactate dehydrogenase activity was unchanged with training, as wereactivities of antioxidant enzymes. Histochemical analysis of thetriceps brachii muscle (long head) revealed lower type IIB fibernumbers in Trn (Sed, 42 ± 6%; Trn, 10 ± 4;P < 0.01) and greater type IID/Xfiber numbers (Sed, 11 ± 2; Trn, 22 ± 3;P < 0.025). These findingsindicate that porcine skeletal muscle adapts to endurance exercisetraining in a manner similar to muscle of humans and other animalmodels, with increased oxidative capacity. Specificmuscles exhibiting these adaptations, however, differ between theminiature swine and other species.

     

The application of lucifferase as a reporter of environmental regulation of gene expression in mycobacteria

This paper describes the construction of pSG10, the first mycobacterial promoter probe shuttle vector to use the structural gene of a bacterial luciferase as a reporter gene. To examine the utility of using bacterial luciferase to measure gene expression in mycobacteria, the authors have used this vector to monitor the induction of the acetamidase gene promoter of Mycobacterium smegmatis. Luciferase proved to be a rapid, sensitive and easily assayable reporter of changes in gene activity in response to environment in mycobacteria.     

Changes of gene expression in Solanum tuberosum L. as a result of transgenes

Potato plants of various cultivars, transformed using Agrobacterium tumefaciens with pGV941 plasmid, differed from control plants in glyphosate herbicide tolerance, tryptophane content, intensity of callusogenesis, microtuber formation in vitro and multimolecular forms of peroxidase (EC 1.11.1.7) and superoxide dismutase (EC 1.15.1.11). The results demonstrate the influence of alien DNA on structural gene expression in transgenic plants.     

Life in a changing world: TCH gene regulation of expression and responses to environmental signals

The Arabidopsis TCH genes were discovered as a consequence of their marked upregulation of expression in response to seemingly innocuous stimuli, such as touch. Further analyses have indicated that these genes are upregulated by a variety of diverse stimuli. Understanding the mechanism(s) and factors that control TCH gene regulation will shed light on the signalling pathways that enable plants to respond to changing environmental conditions. The TCH proteins include calmodulin, calmodulin-related proteins and a xyloglucan endotransglycosylase. Expression analyses and localization of protein accumulation indicate that the potential sites of TCH protein function include expanding cells and tissues under mechanical strain. We hypothesize that the TCH proteins may collaborate in cell wall biogenesis.     

How to cluster gene expression dynamics in response to environmental signals

Organisms usually cope with change in the environment by altering the dynamic trajectory of gene expression to adjust the complement of active proteins. The identification of particular sets of genes whose expression is adaptive in response to environmental changes helps to understand the mechanistic base of gene-environment interactions essential for organismic development. We describe a computational framework for clustering the dynamics of gene expression in distinct environments through Gaussian mixture fitting to the expression data measured at a set of discrete time points. We outline a number of quantitative testable hypotheses about the patterns of dynamic gene expression in changing environments and gene-environment interactions causing developmental differentiation. The future directions of gene clustering in terms of incorporations of the latest biological discoveries and statistical innovations are discussed. We provide a set of computational tools that are applicable to modeling and analysis of dynamic gene expression data measured in multiple environments.     

Changes in gene expression and biochemical composition of Haematococcus pluvialis grown under different light colors

Journal of Applied Phycology - The present study evaluated the effect of blue, red, and white light on the expression of four carotenogenic genes (psy, lyc, bkt, and crtr-r); one gene related to...     

Cardiac biochemical and functional adaptations to exercise in sympathectomized neonatal rats

This study was undertaken to examine the influence of guanethidine monosulfate-induced sympathectomy on exercise-induced adaptations of cardiac contractile protein and on acute hemodynamic responses to exercise involving female neonatal rats. Four groups of rats were studied: 1) normal sedentary (NS), 2) normal trained (NT), 3) sympathectomized sedentary (SS), and 4) sympathectomized trained (ST). The 9-wk running program, which began at 20 days of age, induced increases in whole-body maximal O2 consumption and skeletal-muscle citrate synthase activity in both NT and ST groups compared with NS (P less than 0.05). Submaximal exercise tests demonstrated circulatory adaptations for NT, SS, and ST groups compared with NC; however, the ST group demonstrated the greatest degree of altered cardiac function (decreased heart rate, left ventricular pressure, and contractility index) during exercise. Also, significant reductions in both myosin- and Ca2+-regulated myofibril adenosinetriphosphatase (ATPase) activity and increases in the relative content of the low ATPase myosin isozyme, V3, occurred in the hearts of the two trained groups (P less than 0.05). These findings suggest that chronic exercise involving normal and sympathectomized neonatal rats improves cardiac function without compromising maximal exercise capacity. Also, the exercise-related adaptation involving myosin isozyme shifts are exaggerated when involvement of the sympathetic nervous system is reduced during training.     

Phenological spread in plants: A result of adaptations to environmental stochasticity?

Summary Plant species co-inhabiting a given geographical region often have distinetly different times of flowering. It is shown that such phenological spread, duc to short-term stochastic variation in weather variables, relaxes competition for empty sites to be colonized by diaspores. For sufficiently large spreads stable coexistence becomes possible. The applicability of the proposed hypothesis to the observed instances of phenological spread is discussed and shown to extend beyond that of other current theories.We thank L.-E. Liljelund, C. Solbreck and C. Wiklund for helpful comments. This work was carried out within the Swedish Coniferous Forest Project, supported by the Swedish Natural Science Research Council, the Swedish Environmental Protection Board, the Swedish Council of Forestry and Agricultural Research, and the Wallenberg foundation.     

Cell wall adaptations to multiple environmental stresses in maize roots

A municipal solid-waste bottom slag was used to grow maize plants under various abiotic stresses (high pH, high salt and high heavy metal content) and to analyse the structural and chemical adaptations of the cell walls of various root tissues. When compared with roots of control plants, more intensive wall thickenings were detected in the inner tangential wall of the endodermis. In addition, phi thickenings in the rhizodermis in the oldest part of the seminal root were induced when plants were grown in the slag. The role of the phi thickenings may not be a barrier for solutes as an apoplastic dye could freely diffuse through them. The chemical composition of cell walls from endodermis and hypodermis was analysed. Slag-grown plants had higher amounts of lignin in endodermal cell walls when compared to control plants and a higher proportion of H-type lignin in the cell walls of the hypodermis. Finally, the amount of aliphatic suberin in both endo- and hypodermal cell walls was not affected by growing the plants on slag. The role of these changes in relation to the increase in mechanical strengthening of the root is discussed.     

Muscle morphological and biochemical adaptations to training in obese Zucker rats

The purposes of the present study were to characterize the histochemical and enzymatic profiles of various hindlimb skeletal muscles, as well as to determine maximal O2 consumption (VO2max) and respiratory exchange ratios (R) during steady-state exercise in the obese Zucker rat. The changes that occurred in these parameters in response to a 6-wk training program were then assessed. Obese rats were randomly assigned to a sedentary or training group. Lean littermates served as a second control. Training consisted of treadmill running at 18 m/min up an 8% grade, 1.5 h/day, 5 day/wk for 6 wk. During week 6, VO2max and R during a steady-state run (74% max) were determined. After 2 days of inactivity, hindlimb muscles were excised, stained for fiber type and capillaries, and assayed for hexokinase, citrate synthase, cytochrome oxidase, and beta-hydroxyacetyl-CoA dehydrogenase. The obese sedentary rats demonstrated greater oxidative enzyme activities per gram of muscle tissue than their lean littermates, greater R values during submaximal exercise of the same relative intensity, and greater absolute VO2max values. Training resulted in a 20-56% increase in oxidative enzymes, a 10% increase in VO2max, and an increase in capillary density in the soleus and plantaris. There was no alteration in R values during exercise at 74% VO2max or in fiber type composition in response to exercise training. Results suggest that the muscle of the obese Zucker rat manifests a greater oxidative capacity than the muscle of its lean littermates. The apparent inability of the obese rat to increase its use of fat during submaximal exercise of the same relative intensity in response to training remains to be elucidated.     

The lactate dehydrogenase of the icefish heart: biochemical adaptations to hypoxia tolerance

Cardiac lactate dehydrogenase from the hemoglobin- and myoglobin-free antarctic icefish has been purified by affinity chromatography. Structural and kinetic properties of the enzyme were found close or identical to those of its skeletal muscle counterpart and other M-type lactate dehydrogenases. A model involving a dual oxidative-anaerobic metabolism of the icefish heart is proposed.