Respiratory Energy Metabolism Research Articles

Identification of Chemical Scaffolds That Inhibit the Mycobacterium tuberculosis Respiratory Complex Succinate Dehydrogenase.

Drug-resistant Mycobacterium tuberculosis is a significant cause of infectious disease morbidity and mortality for which new antimicrobials are urgently needed. Inhibitors of mycobacterial respiratory energy metabolism have emerged as promising next-generation antimicrobials, but a number of targets remain unexplored. Succinate dehydrogenase (SDH), a focal point in mycobacterial central carbon metabolism and respiratory energy production, is required for growth and survival in M. tuberculosis under a number of conditions, highlighting the potential of inhibitors targeting mycobacterial SDH enzymes. To advance SDH as a novel drug target in M. tuberculosis, we utilized a combination of biochemical screening and in-silico deep learning technologies to identify multiple chemical scaffolds capable of inhibiting mycobacterial SDH activity. Antimicrobial susceptibility assays show that lead inhibitors are bacteriostatic agents with activity against wild-type and drug-resistant strains of M. tuberculosis. Mode of action studies on lead compounds demonstrate that the specific inhibition of SDH activity dysregulates mycobacterial metabolism and respiration and results in the secretion of intracellular succinate. Interaction assays demonstrate that the chemical inhibition of SDH activity potentiates the activity of other bioenergetic inhibitors and prevents the emergence of resistance to a variety of drugs. Overall, this study shows that SDH inhibitors are promising next-generation antimicrobials against M. tuberculosis.

The antibacterial and inhibition effect of chitosan grafted gentisate acid derivatives against Pseudomonas fluorescens: Attacking multiple targets on structure, metabolism system, antioxidant system, and biofilm

This work aimed to investigate the antibacterial ability and potential mechanism of chitosan grafted gentisate acid derivatives (CS-g-GA) against Pseudomonas fluorescens. The results showed that CS-g-GA had a significant suppressive impact on the growth of Pseudomonas fluorescens, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 0.64 mg/mL and 1.28 mg/mL, respectively. Results of scanning electron microscopy (SEM) and alkaline phosphatase (AKPase) confirmed that CS-g-GA destroyed the cell structure thereby causing the leakage of intracellular components. In addition, 1 × MIC of CS-g-GA could significantly inhibit the formation of biofilms, and 74.78 % mature biofilm and 86.21 % extracellular polysaccharide of Pseudomonas fluorescens were eradicated by CS-g-GA at 2 × MIC. The results on the respiratory energy metabolism system and antioxidant system demonstrated that CS-g-GA caused respiratory disturbance and energy limitation by influencing the key enzyme activities. It could also bind to DNA and affect genetic metabolism. From this, it could be seen that CS-g-GA had the potential to control foodborne contamination of Pseudomonas fluorescens by attacking multiple targets.

Impact of hypoxia on glucose metabolism and hypoxia signaling pathways in juvenile horseshoe crabs Tachypleus tridentatus

Marine hypoxia poses a significant challenge in the contemporary marine environment. The horseshoe crab, an ancient benthic marine organism, is confronted with the potential threat of species extinction due to hypoxia, making it an ideal candidate for studying hypoxia tolerance mechanisms. In this experiment, juvenile Tachypleus tridentatus were subjected to a 21-day trial at DO:2 mg/L (hypoxia) and DO:6 mg/L conditions. The experimental timeline included a 14-day exposure phase followed by a 7-day recovery period. Sampling occurred on days 0, 7, 14, and 21, where the period from day 14 to day 21 corresponds to seven days of recuperation. Several enzymatic activities of important proteins throughout this investigation were evaluated, such as succinate dehydrogenase (SDH), phosphofructokinase (PFK), hexokinase (HK), lactate dehydrogenase (LDH), and pyruvate kinase (PK). Concurrently, the relative expression of hexokinase-1 (HK), hypoxia-inducible factor 1-alpha inhibitor (FIH), and hypoxia-inducible factor 1-alpha (HIF-1α), pyruvate dehydrogenase phosphatase (PDH), succinate dehydrogenase assembly factor 4 (SDH), and Glucose-6-phosphatase (G6Pase) were also investigated. These analyses aimed to elucidate alterations in the hypoxia signaling pathway and respiratory energy metabolism. It is revealed that juvenile T. tridentatus initiated the HIF pathway under hypoxic conditions, resulting in an upregulation of HIF-1α and FIH-1 gene expression, which in turn, influenced a shift in metabolic patterns. Particularly, the activity of glycolysis-related enzymes was promoted significantly, including PK, HK, PKF, LDH, and the related HK gene. In contrast, enzymes linked to aerobic respiration, PDH, and SDH, as well as the related PDH and SDH genes, displayed down-regulation, signifying a transition from aerobic to anaerobic metabolism. Additionally, the activity of gluconeogenesis-related enzymes such as PK and G6Pase gene expression were significantly elevated, indicating the activation of gluconeogenesis and glycogenolysis pathways. Consequently, juvenile T. tridentatus demonstrated an adaptive response to hypoxic conditions, marked by changes in respiratory energy metabolism modes and the activation of hypoxia signaling pathways.

Seasonal differences in thermal stress susceptibility of diploid and triploid brook trout, Salvelinus fontinalis (Teleostei, Pisces).

Many physiological processes of teleost fish show periodicity due to intrinsic rhythms. It may be hypothesized that also susceptibility to thermal stress differs seasonally. To shed more light on this problem the following experiment was conducted. Diploid and triploid Salvelinus fontinalis were kept at an acclimation temperature of 9°C and at a natural photoperiod typical for the Northern Hemisphere during their entire live. During eight different periods of the year, different subgroups were exposed to a 32 day lasting thermal stress of 20°C. Rate of fish maintaining equilibrium, daily growth rate, condition factor, viscerosomatic index and hepato-somatic index were measured. Complementary mRNA expression of genes characterizing growth (GHR1, GHR2), proteolysis (Protreg, Protα5), stress (Hsp47, Hsp90) and respiratory energy metabolism (ATPJ52) was determined. Seasonal differences in thermal stress susceptibility of 2n and 3n S.fontinalis were detected. It was highest from September to December and moderate from January to March. During the remaining period of the year, susceptibility to thermal stress was minimal. Increased thermal stress susceptibility was related to decreased rates of fish maintaining equilibrium, decreased growth rates, reduction of viscera and liver mass and changes in mRNA expression of genes characterizing proteolysis, growth, respiratory energy metabolism and stress. The differences in seasonal stress susceptibility were minor between 2n and 3n S.fontinalis. The data are valuable for ecology and fish culture to identify periods when animals are most susceptible to thermal stress.

Antifungal activity of 1-octen-3-ol against Monilinia fructicola and its ability in enhancing disease resistance of peach fruit

Peach fruit is susceptible to decay caused by Monilinia fructicola infection. Synthetic fungicides are effective for inhibiting this pathogen and rot rate, but more and more attentions to the safety and pollution that chemicals compel us to find other methods to control M. fructicola disease. Natural volatile organic compound was considered as a potential way to reduce pathogen infection. 1-Octen-3-ol, a natural product from plant or fungi, can inhibit several pathogens growth. In this study, it is found that 1-octen-3-ol fumigation not only inhibited development of M. fructicola in vitro but also effectively reduced brown rot caused by the pathogen in vivo. The results showed 37.20, 55.80 and 74.40 μg mL −1 1-octen-3-ol fumigation could inhibit the extension of M. fructicola hyphae and significantly reduce the ergosterol content of mycelium. The results of microscopy, it can be seen that 1-octen-3-ol destroyed the hyphae morphology and cell structure. The spore apoptosis rate and reactive oxygen species (ROS) increased, and the mitochondrial membrane potential (MMP) decreased. Moreover, 55.80 μg mL −1 1-octen-3-ol fumigation could significantly reduce disease incidence and lesion diameter of fruit. Chitinase and β-1,3-glucanase activities were enhanced, and expression of ICS1 , NPR1 , TGA1 , PR1 were up-regulated, as well as down-regulation of AOS , COI1 and MYC2 . These results indicate that 1-octen-3-ol treatment is a promising approach to control brown rot, which is related to the activation of salicylic acid (SA) signal to enhance fruit disease resistance besides direct destruction of pathogen. • Volatile 1-octen-3-ol could inhibit Monilinia fructicola in vitro. • 1-octen-3-ol destroyed the integrity of fungal biofilm and respiratory energy metabolism. • 1-octen-3-ol treatment effectively inhibited brown rot development in peach fruit. • 1-octen-3-ol may induce disease resistance via activation of SA signal pathway of peach fruit.

Progress in studies on production of chemicals from xylose by Saccharomyces cerevisiae

Effective utilization of xylose is a basis for economic production of biofuels or chemicals from lignocellulose biomass. Over the past 30 years, through metabolic engineering, evolutionary engineering and other strategies, the metabolic capacity of xylose of the traditional ethanol-producing microorganism Saccharomyces cerevisiae has been significantly improved. In recent years, the reported results showed that the transcriptome and metabolome profiles between xylose and glucose metabolism existed significant difference in recombinant yeast strains. Compared with glucose, the overall process of xylose metabolism exhibits Crabtree-negative characteristics, including the limited glycolytic pathway activity, which reduces the metabolic flux of pyruvate to ethanol, and the enhanced cytosolic acetyl-CoA synthesis and respiratory energy metabolism. These traits are helpful to achieve efficient synthesis of downstream products using pyruvate or acetyl-CoA as precursors. This review provides a detailed overview on the modification and optimization of xylose metabolic pathways in S. cerevisiae, the characteristics of xylose metabolism, and the construction of cell factories for production of chemicals using xylose as a carbon source. Meanwhile, the existed difficulties and challenges, and future studies on biosynthesis of bulk chemicals using xylose as an important carbon source are proposed.

Structures of substrate- and product-bound forms of a multi-domain copper nitrite reductase shed light on the role of domain tethering in protein complexes.

Copper-containing nitrite reductases (CuNiRs) are found in all three kingdoms of life and play a major role in the denitrification branch of the global nitro-gen cycle where nitrate is used in place of di-oxy-gen as an electron acceptor in respiratory energy metabolism. Several C- and N-terminal redox domain tethered CuNiRs have been identified and structurally characterized during the last decade. Our understanding of the role of tethered domains in these new classes of three-domain CuNiRs, where an extra cytochrome or cupredoxin domain is tethered to the catalytic two-domain CuNiRs, has remained limited. This is further compounded by a complete lack of substrate-bound structures for these tethered CuNiRs. There is still no substrate-bound structure for any of the as-isolated wild-type tethered enzymes. Here, structures of nitrite and product-bound states from a nitrite-soaked crystal of the N-terminal cupredoxin-tethered enzyme from the Hyphomicrobium denitrificans strain 1NES1 (Hd 1NES1NiR) are provided. These, together with the as-isolated structure of the same species, provide clear evidence for the role of the N-terminal peptide bearing the conserved His27 in water-mediated anchoring of the substrate at the catalytic T2Cu site. Our data indicate a more complex role of tethering than the intuitive advantage for a partner-protein electron-transfer complex by narrowing the conformational search in such a combined system.

Metabolite Regulatory Interactions Control Plant Respiratory Metabolism via Target of Rapamycin (TOR) Kinase Activation.

Respiration rate measurements provide an important readout of energy expenditure and mitochondrial activity in plant cells during the night. As plants inhabit a changing environment, regulatory mechanisms must ensure that respiratory metabolism rapidly and effectively adjusts to the metabolic and environmental conditions of the cell. Using a high-throughput approach, we have directly identified specific metabolites that exert transcriptional, translational, and posttranslational control over the nighttime O2 consumption rate (RN) in mature leaves of Arabidopsis (Arabidopsis thaliana). Multi-hour RN measurements following leaf disc exposure to a wide array of primary carbon metabolites (carbohydrates, amino acids, and organic acids) identified phosphoenolpyruvate (PEP), Pro, and Ala as the most potent stimulators of plant leaf RN Using metabolite combinations, we discovered metabolite-metabolite regulatory interactions controlling RN Many amino acids, as well as Glc analogs, were found to potently inhibit the RN stimulation by Pro and Ala but not PEP. The inhibitory effects of amino acids on Pro- and Ala-stimulated RN were mitigated by inhibition of the Target of Rapamycin (TOR) kinase signaling pathway. Supporting the involvement of TOR, these inhibitory amino acids were also shown to be activators of TOR kinase. This work provides direct evidence that the TOR signaling pathway in plants responds to amino acid levels by eliciting regulatory effects on respiratory energy metabolism at night, uniting a hallmark mechanism of TOR regulation across eukaryotes.

Evaluation of stability and validation of reference genes for real time PCR expression studies in leaves and roots of Prunus spp. rootstocks under flooding

Molecular oxygen (O2) is involved in several biochemical reactions of plants. The low availability of oxygen to cells can lead to an energy crisis, since O2 is the main substrate of respiratory energy metabolism in aerobic organisms, acting as the final acceptor of electrons in the mitochondrial transport chain. When oxygen becomes insufficient for respiration, the plants begin a hypoxia condition. This situation can occur naturally due to excessive rainfall and the existence of poorly drained soils, causing soil flooding. This condition occurs in the South region of Rio Grande do Sul State, in Brazil, which is the largest Brazilian producer of stone fruits, mainly peaches, therefore, its production is adversely affected by flooding. Since the production of stone fruits plants (Prunus spp.) in the region occurs using rootstocks, the aim of this study was to identify potential reference genes for normalization of RT-qPCR data in leaves and roots of four rootstock of Prunus spp. (Capdeboscq, NR0170401, Marianna 2624 and Myrabolan 29-C) in the soil flooding condition. Eight candidate genes were evaluated: PLA2 (phospholipase A2), CYP2 (cyclophilin 2), Ef1α (elongantion factor 1-alpha), RPL13 (ribosomal protein L13), TUA (tubulin alpha), TUB (tubulin beta), RPII (RNA polymerase II), and 18S rRNA (18S ribosomal RNA). Some algorithms for the stability analysis were used, such as the ΔCt comparative method, BestKeeper, NormFinder, geNorm, and the RefFinder tool. As result, the CYP2 and RPII genes presented greater stability in the peach roostocks, whereas RPII and RPL13 were more stable in the plum rootstocks. The Ef1α gene showed no expression stability in the rootstocks ‘NR0170401’ (both tissues) and ‘Myrabolan 29-C’ (roots). The 18S rRNA gene was shown to be unstable for ‘Capdeboscq’ and ‘Marianna 2624’ leaves, while the TUB and PLA2 genes were not stable for roots of these cultivars, respectively. Analysis of the expression of LDH1 (Lactate Dehydrogenase) and ADH1 (alcohol Dehydrogenase) proved the importance of validation of the reference genes to obtain accurate results in RT-qPCR. Taken together, this study selected the reference genes suitable for the reliable normalization of gene expression data in Prunus spp. under flooding.

ArcA overexpression induces fermentation and results in enhanced growth rates of E. coli

Overflow metabolism in the presence of oxygen occurs at fast growth rates in a wide range of organisms including bacteria, yeast and cancer cells and plays an important role in biotechnology during production of proteins or metabolic compounds. As recently suggested, overflow metabolism can be understood in terms of proteome allocation, since fermentation has lower proteome cost for energy production than respiration. Here, we demonstrate that ArcA overexpression in aerobic conditions, results in downregulation of respiratory pathways and enhanced growth rates on glycolytic substrates of E. coli, coinciding with acetate excretion and increased carbon uptake rates. These results suggest that fermentation enables faster growth and demonstrate that fermentation on many glycolytic carbon sources is not limited by carbon uptake. Hence, these findings are difficult to reconcile with many alternative hypotheses that have been proposed for the origin of overflow metabolism and the growth rate dependence of fermentation and respiration, which are based on limited capacity of respiration or limitations in uptake rates and catabolic pathways. Instead, as suggested by increased lag phases of ArcA overexpression strains, respiratory energy metabolism may be related to a general preparatory response, observed for decreasing growth rates, but with limited advantages for maximizing steady-state growth rate.

Pseudomonas aeruginosa strain PA01 impairs enzymes of the phosphotransfer network in the gills of Rhamdia quelen

Integration of mitochondria with cytosolic ATP-consuming/ATP-sensing and substrate supply processes is critical for gills bioenergetics, since this tissue plays an important role in the respiratory energy metabolism. The effects of bacterial infection on gills remain poorly understood, limited only to histopathological analyses. Thus, the aim of this study was to investigate whether experimental infection by Pseudomonas aeruginosa strain PA01 alters the enzymes of the phosphoryltransfer network (adenylate kinase (AK), pyruvate kinase (PK) and cytosolic and mitochondrial creatine kinase (CK)) in gills of silver catfish (Rhamdia quelen). The animals were divided into two groups with six fish each: uninfected (negative control) and infected (positive control). On day 7 post-infection (PI), animals were euthanized and the gills collected. AK, PK, and cytosolic and mitochondrial CK activities in gills decreased in infected compared to uninfected animals. Also, severe gill damage and destruction in the primary and secondary lamellae was observed in the infected animals. Therefore, we have demonstrated, for the first time, that experimental infection by P. aeruginosa inhibits key enzymes linked to the production and utilization of metabolic energy in silver catfish, and consequently, impairs cellular energy homeostasis, which may contribute to disease pathogenesis.

Cyanobacterial Phytochrome2 Regulates the Heterotrophic Metabolism and Has a Function in the Heat and High-Light Stress Response

Cyanobacteria combine the photosynthetic and respiratory electron transport in one membrane system, the thylakoid membrane. This feature requires an elaborate regulation mechanism to maintain a certain redox status of the electron transport chain, hence allowing proper photosynthetic and respiratory energy metabolism. In this context, metabolic adaptations, as seen in the light-to-dark and dark-to-light transitions, are particularly challenging. However, the molecular basis of the underlying regulatory mechanisms is not well-understood. Here, we describe a function of cyanobacterial phytochrome2 (Cph2), a phytochrome of the cyanobacterial model system Synechocystis sp. PCC 6803, in regulation of the primary energy metabolism. When cells are shifted from photoautotrophic planktonic growth to light-activated heterotrophic growth and biofilm initiation, knockout of Cph2 results in impaired growth, a decrease in the activity of Glc-6-P dehydrogenase, a decrease of the transcript abundance/activity of cytochrome-c-oxidase, and slower phycocyanin degradation. Measurements of the plastoquinone reduction confirm an impaired heterotrophic metabolism in the cph2 knockout. When cells that were adapted to heterotrophic metabolism are shifted back to light conditions, the knockout of Cph2 results in an altered photosystem II chlorophyll fluorescence induction curve, which is indicative of an impaired redox balance of the electron transport chain. Moreover, Cph2 plays a role in the heat and high-light stress response, particularly under photomixotrophic conditions. Our results show a function of Cph2 in the adaptation of the primary energy metabolism to changing trophic conditions. The physiological role of Cph2 in biofilm formation is discussed.

The production of ammonia by multiheme cytochromes C.

The global biogeochemical nitrogen cycle is essential for life on Earth. Many of the underlying biotic reactions are catalyzed by a multitude of prokaryotic and eukaryotic life forms whereas others are exclusively carried out by microorganisms. The last century has seen the rise of a dramatic imbalance in the global nitrogen cycle due to human behavior that was mainly caused by the invention of the Haber-Bosch process. Its main product, ammonia, is a chemically reactive and biotically favorable form of bound nitrogen. The anthropogenic supply of reduced nitrogen to the biosphere in the form of ammonia, for example during environmental fertilization, livestock farming, and industrial processes, is mandatory in feeding an increasing world population. In this chapter, environmental ammonia pollution is linked to the activity of microbial metalloenzymes involved in respiratory energy metabolism and bioenergetics. Ammonia-producing multiheme cytochromes c are discussed as paradigm enzymes.

Isotope-reinforced polyunsaturated fatty acids protect yeast cells from oxidative stress

The facile abstraction of bis-allylic hydrogens from polyunsaturated fatty acids (PUFAs) is the hallmark chemistry responsible for initiation and propagation of autoxidation reactions. The products of these autoxidation reactions can form cross-links to other membrane components and damage proteins and nucleic acids. We report that PUFAs deuterated at bis-allylic sites are much more resistant to autoxidation reactions, because of the isotope effect. This is shown using coenzyme Q-deficient Saccharomyces cerevisiae coq mutants with defects in the biosynthesis of coenzyme Q (Q). Q functions in respiratory energy metabolism and also functions as a lipid-soluble antioxidant. Yeast coq mutants incubated in the presence of the PUFA α-linolenic or linoleic acid exhibit 99% loss of colony formation after 4 h, demonstrating a profound loss of viability. In contrast, coq mutants treated with monounsaturated oleic acid or with one of the deuterated PUFAs, 11,11-D 2-linoleic or 11,11,14,14-D 4-α-linolenic acid, retain viability similar to wild-type yeast. Deuterated PUFAs also confer protection to wild-type yeast subjected to heat stress. These results indicate that isotope-reinforced PUFAs are stabilized compared to standard PUFAs, and they protect coq mutants and wild-type yeast cells against the toxic effects of lipid autoxidation products. These findings suggest new approaches to controlling ROS-inflicted cellular damage and oxidative stress.

Isotope‐Reinforced Polyunsaturated Fatty Acids Protect Yeast Cells from Oxidative Stress

Polyunsaturated fatty acids (PUFAs) are exquisitely sensitive to autoxidation damage. The enhanced vulnerability of PUFAs to such autoxidation stems from the labile nature of the bis‐allylic hydrogen atoms. PUFAs synthesized to contain Deuterium atoms uniquely at the bis‐allylic sites (termed isotope‐reinforced PUFAs) would be expected to be more resistant to autoxidation reactions due to the isotope effect. This hypothesis was tested by making use of yeast coq mutants with defects in biosynthesis of coenzyme Q (CoQ, or ubiquinone). CoQ plays a well‐known role in respiratory energy metabolism and also functions as a lipid soluble chain terminating antioxidant. Although yeast cannot synthesize PUFAs, they are able to incorporate exogenously supplied PUFAs. Yeast coq mutants incubated in the presence of linolenic acid (C18:3) exhibit profound loss of viability as ascertained by greater than 99% loss of colony formation at 4 hours. In contrast, the coq mutants treated with the isotope‐reinforced linolenic acid (bis‐allylic D4‐C18:3) retain 80–90% viability, a value similar to wild‐type or CoQ‐replete yeast. These results indicate that isotope reinforced PUFAs are stabilized as compared to standard PUFAs, and the coq mutant yeast cells containing the D4‐linolenic acid are protected against the toxic effects of lipid autoxidation products. This research was supported by NIH GM45952.

Ammonia-mediated LTP inhibition: Effects of NMDA receptor antagonists and l-carnitine

Because hyperammonemia is thought to contribute to the pathogenesis of hepatic encephalopathy, we examined the effects of ammonia on ATP levels, neuronal morphology, and synaptic function in rat hippocampal slices. Although ammonia did not alter ATP levels supported by 10 mM glucose, ammonia significantly depressed ATP levels in the presence of 3.3 mM glucose or 10 mM pyruvate, suggesting effects on respiratory energy metabolism. Ammonia also impaired synaptic function and neuronal integrity sustained by pyruvate. In 10 mM glucose, ammonia inhibited the induction and maintenance of long-term potentiation (LTP) in a concentration-dependent fashion. These inhibitory effects of ammonia were overcome by L-carnitine. DL-APV, an antagonist of NMDA receptors, also diminished the effects of ammonia on ATP levels and LTP induction, indicating that ammonia impairs neuronal function via altered metabolism and untimely NMDA receptor activation. These results suggest that L-carnitine and NMDA receptor antagonists have the potential to preserve neuronal function during hyperammonemia.

Fundamental Causes of the Global Patterns of Species Range and Richness1

Global patterns of species range and richness are a consequence of many interacting factors, including environmental conditions, competition, geographical area, and historical/evolutionary development. Two widely studied global patterns of distribution are the latitudinal and elevation gradients of species range and richness. The fundamental mechanisms by which environment and physiology of the plants themselves interact to generate global-scale correlations between increased species range or decreased species richness and latitude/elevation have not previously been established. This paper develops the hypothesis that the primary climatic variables determining global-scale gradients in ectotherm species range and richness are temperature (T) and temperature variability (ΔT), and that the primary physiological variable defining adaptation of ectotherms to temperature is respiratory energy metabolism. This hypothesis is based on a postulate that adaptation of ectotherms to latitudinal/altitudinal gradients of T and ΔT leads to corresponding gradients in properties of energy metabolism. The gradients of metabolic properties give rise to gradients of species range and richness that are observed on a global scale. We demonstrate that natural selection results in ectotherms with metabolic properties matched to their environment and that energy use efficiency and the temperature range allowing growth are inversely related. Thus, opposing selective pressures to increase metabolic energy-use-efficiency or to increase the probability of surviving climate extremes control adaptation of ectotherms to climate. The principles developed in this paper yield fundamental laws of ecology that allow calculation of the contributions of global temperature patterns to the formation of gradients of species range and diversity. Relative values of richness and range are calculated solely from data on abiotic variables. Predictions agree with known patterns of ectotherm distribution.

KNOWLEDGE-BASED CONTROL SYSTEMS FOR SINGLE STEM ROSE PRODUCTION — PART I: SYSTEMS ANALYSIS AND DESIGN

Systems analysis was performed to develop knowledge-based control systems (KBS) for single stem rose production. System components and control strategies for the KBS were identified from the analysis. The control strategy for daytime temperatures was derived by balancing the conflicting goals of rose production and costs of environmental modification. Nighttime temperature control strategy was determined through qualitative reasoning of the relationship between the plant’s photosynthetic efficiency and respiratory energy metabolism. A fuzzy inference paradigm was applied to facilitate system design. Two fuzzy inference systems (FIS) were designed to determine the daytime and nighttime greenhouse set point temperatures. A set of experiments was conducted to obtain the information on dimensional measurements of single stem rose (Rosa hybrida L., cv. Lady Diana) and the corresponding stem dry weight. An adaptive neuro-fuzzy inference system (ANFIS) was devised that predicted the dry weight for single stem roses from simple nondestructive measurements. An on-line computational algorithm for greenhouse heating and ventilation costs was developed according to the daily energy consumption of each component of heating and ventilation equipment. Two sets of rule bases were derived for daytime and nighttime temperature settings.