Natraj Krishnan

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Verified

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• PhD
• Professor (Associate) and Graduate Coordinator at Mississippi State University

The neurotransmitter dopamine (DA) is known to be involved in a multitude of physiological processes. We investigated sexually dimorphic effects of disruptions in DA homeostasis and its relationship to senescence using three different Drosophila melanogaster mutants namely Catsup (Catsup(26) ) with elevated DA levels, and pale (ple(2) ) and Punch (...

Transfer RNAs (tRNAs) are key molecules participating in protein synthesis. To augment their functionality they undergo extensive post-transcriptional modifications and, as such, are subject to regulation at multiple levels including transcription, transcript processing, localization and ribonucleoside base modification. Post-transcriptional enzyme...

Lipids are essential in insects and play pleiotropic roles in energy storage, serving as a fuel for energy-driven processes such as reproduction, growth, development, locomotion, flight, starvation response, and diapause induction, maintenance, and termination. Lipids also play fundamental roles in signal transduction, hormone synthesis, forming co...

The minute wasp Habrobracon hebetor venom (HH venom) is a potent cocktail of toxins that paralyzes the victim’s muscles and suppresses humoral and cellular immunity. This study examined the effect of HH venom on specific biochemical, physiological, and ultrastructural characteristics of the thoracic and nervous (CNS) tissues of Drosophila melanogas...

Over the past two decades, Drosophila melanogaster has proven to be successful in modeling the polyglutamine (polyQ) (caused by CAG repeats) family of neurodegenerative disorders, including the faithful recapitulation of pathological features such as polyQ length-dependent formation of protein aggregates and progressive neuronal degeneration. In th...

Cotton is the most critical fiber crop and one of the top three oilseed crops in the world. One pronounced feature of cotton is that it is rich in secondary metabolites, mainly including terpenoids, flavonoids, and phenolic acids. These secondary metabolites have various ecological roles, such as defense and signal transmission. With the concept of...

In classical neuroscience, Dale´s principle postulates that neuronal identity is conferred by the specific neurotransmitter that it releases. However, the brain might be more tractable to specific situations regardless of specific specialisation which may contradict this principle. Hence, this constrained approach of how we perceive and study the n...

Tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), is the target for multiple insecticide applications in cotton in the mid-southern U.S. Resistance to several insecticide classes has been documented, so monitoring of resistance levels to insecticides currently used is needed before field control failures occur. Sever...

Neonicotinoids have been implicated as a contributing factor to the observed decreases in honey bee populations. It has been suggested that honey bees can be exposed to seed-treated neonicotinoids through pollen and nectar from treated plants. To investigate the uptake and persistence of neonicotinoids in plant tissue and soil, we conducted seed tr...

Matrix metalloproteinases (MMPs) are zinc- and calcium- dependent endopeptidases that play pivotal roles in many biological processes. The expression of several MMPs in the central nervous system (CNS) have been shown to change in response to injury and various neurological/neurodegenerative disorders. While extracellular MMPs degrade the extracell...

Tarnished plant bug, Lygus lineolaris Palisot de Beauvois (Hemiptera: Miridae), has become a primary pest of cotton in the Midsouthern United States. Insect growth regulators such as novaluron are an important part of L. lineolaris management. While novaluron is lethal to nymphs, it does not kill adults, so it has been used when nymphs are the prim...

BACKGROUND The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), has emerged as a major pest of cotton, Gossypium hirsutum L, in the mid‐southern USA. In the early 1990s L. lineolaris populations developed resistance to several classes of conventional insecticides, increasing the need for insecticides with alternative modes of action suc...

This study was focused on gaining insights into the mechanism by which the herbicide- Spectracide®, induces oxidative stress and alters behavior in Drosophila melanogaster. Exposure to Spectracide® (50%) significantly (p < 0.05) reduced the negative geotaxis response, jumping behavior and dampened locomotor activity rhythm in adult flies compared t...

In order to develop an understanding of the role of adjuvants in a popular glyphosate-based herbicide – Roundup® Concentrate Plus (RCP), on non-target organisms, the effects of pure glyphosate [N-(phosphonomethyl)-glycine], RCP and a non-ionic surfactant – polyethoxylated tallowamine (POEA) were studied in the fruit fly Drosophila melanogaster. Acu...

The impact of disruption of adipokinetic hormone (AKH) signaling was studied during aging in Drosophila in a sexually dimorphic manner. A mutant (Akh1) producing a non-functional AKH peptide was compared with isogenized wild-type controls (w1118), and Akh-rescue line where AKH was ectopically expressed in the mutant background (EE-Akh). Longevity,...

Native Lauraceae (e.g. sassafras, redbay) in the southeastern USA are being severely impacted by laurel wilt disease, which is caused by the pathogen Raffaelea lauricola T. C. Harr., Fraedrich and Aghayeva, and its symbiotic vector, the redbay ambrosia beetle (Xyleborus glabratus Eichhoff). Cold temperatures are currently the only viable limitation...

The homeostatic environment in an organism is under constant challenge by internal and external stressors. Responding to stress is an energy demanding process and takes a toll on energy balance. Hence, energy homeostasis is a fundamental requirement in an organism's adaptive response to stress. The ability of an organism to tolerate and respond to...

Lygus lineolaris (Palisot de Beauvois, 1818) (tarnished plant bug) is a serious pest of cotton (Gossypium hirsutum L.) in the Delta region as compared to cotton in the Hills region of the state of Mississippi in USA. The reason for this is unclear but it was hypothesized that the plant cell wall degrading polygalacturonase enzyme system in the sali...

Experiments were conducted in Mississippi from 2013 to 2015 to determine the systemic and residual efficacy of chlorantraniliprole and flubendiamide against corn earworm, Helicoverpa zea (Boddie), in soybean. Both insecticides were applied at V4 and R3. Ten leaves that were present at the time of application and 10 newly emerged leaves that were no...

Corn earworm, Helicoverpa zea (Boddie), is a significant pest of agroecosystems in the midsouthern and southeastern regions of the United States. These insects have developed resistance to, or inconsistent control has occurred with, most insecticide classes. With their unique mode of action, insecticides in the diamide class have become a key compo...

The red mason bee Osmia rufa is a solitary bee belonging to the family Megachilidae, and is prone to nest in aggregations. Each female builds a nest separately in pre-existing cavities such as holes in wood and walls or empty plant stems. This is done by successively setting the cells in a linear series. In this study, we elucidate the nesting beha...

The tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois) is a polyphagous, phytophagous insect that has emerged as a major pest of cotton, alfalfa, fruits, and vegetable crops in the eastern United States and Canada. Using its piercing-sucking mouthparts, TPB employs a "lacerate and flush" feeding strategy in which saliva injected into...

Agarose gel (A) and Agilent Bioanalyzer (B) images of extracted RNA used in the study. (TIF)

Lygus lineolaris Blast alignments to Acyrthosiphon pisum, Drosophila melanogaster, Tribolium castaneum, and Lygus hesperus. (XLSX)

Lygus lineolaris salivary gland transcriptome InterProScan Pfam annotations. (XLSX)

Lygus lineolaris salivary gland transcriptome Gene Ontology (GO) Molecular Function term enrichment for secreted proteins. (XLSX)

Lygus lineolaris salivary gland transcriptome Gene ontology (GO) terms annotations. (XLSX)

Lygus lineolaris salivary gland transcriptome KEGG pathway and enzyme annotations. (XLSX)

Lygus lineolaris salivary gland transcriptome predicted proteins of interest Blast alignment results. (XLSX)

Esterases are ubiquitous in living organisms and perform multiple functions in animals, plants, insects and microorganisms. Insect esterases broadly perform physiological and defense functions. The present work aims towards identifying heat stable esterase in the hemolymph of near isogenic lines (NILs) and their parents, and further to classify est...

Background: Lygus lineolaris (Palisot de Beauvois) is a serious pest of cotton (Gossypium hirsutum L.) in Mississippi, particularly in the Delta region. This may be due to decreased insecticide susceptibility in that region. Research has revealed populations of L. lineolaris in the Delta region with high levels of insecticide resistance; however,...

Insects, like other organisms, must deal with a wide variety of potentially challenging environmental factors during the course of their life. An important example of such a challenge is the phenomenon of oxidative stress. This review summarizes the current knowledge on the role of adipokinetic hormones (AKH) as principal stress responsive hormones...

Phytophagous insects derive nutritional resources by consuming and digesting plant compounds. In order to access the nutritional components the plant cell wall has to be degraded. Pectin is a major component of the plant cell wall. Enzymes that degrade pectin include polygalacturonases (PG). Some insects harbor PGs in their salivary glands (SGs). I...

In animals olfaction is mediated by the interaction of volatile ligands with a set of specialized membrane proteins known as odorant receptors (Ors). An intriguing question in the biology of the sensory system concerns the equivalency of its primary sensory neurons in driving behavioral outputs, particularly navigational ability towards food and te...

Dopamine (DA) is the sole neuroactive catecholamine in Drosophila melanogaster which regulates locomotor behavior along with various physiological and developmental functions. We monitored the impact of mutations in three key genes in DA regulation on circadian locomotor behavior and resistance to oxidative stress (OS) in D. melanogaster. Catechola...

Adipokinetic hormones (AKH) are secreted in insects by a group of cells in the corpora cardiaca region of the brain. This neuropeptide primarily functions in the mobilization of energy sources for locomotion and flight. Diel changes in secretion of this hormone have been reported earlier. However, the precise links between the circadian clock syste...

The presence and potential role of adiponectin- and resistin-like peptides in mobilizing free lipids of hemolymph during over-wintering was studied in females of the European solitary red mason bee Osmia bicornis L. (Hymenoptera: Megachilidae). The levels of both peptides (as demonstrated both by RIA/ELISA and Western blots) were highest in fat bod...

The effects of enhanced UV-B radiation on the oogenesis and morpho-anatomical characteristics of the European solitary red mason bee Osmia bicornis L (Hymenoptera: Megachilidae) were tested under laboratory conditions. Cocooned females in the pupal stage were exposed directly to different doses (0, 9.24, 12.32 and 24.64 kJ/m2/d) of artificial UV-B....

The effect of adipokinetic hormone (Pyrap-AKH) in stimulating the function of insect salivary glands (SGs) in extra-oral digestive processes was studied in the firebug, Pyrrhocoris apterus (Heteroptera). The analyses were performed on samples of SGs and extracts of linden seeds, a natural source of the bug's food. The SGs from 3-day old P. apterus...

The redbay ambrosia beetle, Xyleborus glabratus Eichoff, (Coleoptera: Curculionidae: Scolytinae) is a severe pest of North American trees and shrubs in the family Lauraceae. Supercooling point (SCP) is an important physiological baseline for cold tolerance studies and could provide useful insights into the invasive potential of X. glabratus in nort...

Polygalacturonase (PG) is an enzyme in the salivary glands of Lygus spp. that is used to break down plant pectins for easier plant tissue feeding and possibly in oviposition site preparation. Previous research has suggested that PG gene expression may change based on the current host of the insect. However, little is known about all the factors tha...

In recent years flubendiamide and chlorantraniliprole have been registered for caterpillar control throughout the southern U.S. Both of these insecticides have excellent acute toxicity and residual control against target pests. A series of bioassays were conducted to better understand the impact of selection pressure with these insecticides

The invasive redbay ambrosia beetle (Xyleborus glabratus Eichoff) (Coleoptera: Curculionidae: Scolytinae) was introduced from Asia into the southeastern United States in 2002. The beetle carries Raffaelea lauricola T.C. Harr., Aghayeva, & Fraedrich, a newly described fungal symbiont responsible for a wilt disease that affects most lauraceous specie...

Background and AimsThe hormone auxin and reactive oxygen species (ROS) regulate root elongation, but the interactions between the two pathways are not well understood. The aim of this study was to investigate how auxin interacts with ROS in regulating root elongation in tomato, Solanum lycopersicum.Methods Wild-type and auxin-resistant mutant, diag...

The catabolic activity of midgut and the turnover of metabolic reserves in fat body and hemolymph was studied during 7 months of overwintering period (September–March) in the European solitary red mason bee Osmia bicornis L. (Hymenoptera: Megachilidae). Assays of lipids, protein, and carbohydrates in midgut, fat body, and hemolymph as well as carbo...

The role of adipokinetic hormone (AKH) in counteracting oxidative stress elicited in the insect body is studied in response to exogenously applied hydrogen peroxide, an important metabolite of oxidative processes. In vivo experiments reveal that the injection of hydrogen peroxide (8 μmol) into the haemocoel of the firebug, Pyrrhocoris apterus L. (H...

The role of adipokinetic hormone (AKH) in counteracting oxidative stress elicited in the insect body is studied in response to exogenously applied hydrogen peroxide, an important metabolite of oxidative processes. In vivo experiments reveal that the injection of hydrogen peroxide (8 μmol) into the haemocoel of the firebug, Pyrrhocoris apterus L. (H...

Circadian rhythms are found in almost all organisms from cyanobacteria to humans, where most behavioral and physiological processes occur over a period of approximately 24 h in tandem with the day/night cycles. In general, these rhythmic processes are under regulation of circadian clocks. The role of circadian clocks in regulating metabolism and co...

The influence of simulated climate change on body weight and depletion of fat body reserves was studied during diapause in the European solitary bee Osmia rufa L. (Hymenoptera: Megachilidae). Insects (females) were reared and collected from outdoor nests from September to March. One cohort of females was weighed and dissected immediately for analys...

The invasive redbay ambrosia beetle (Xyleborus glabratus Eichoff) (Coleoptera: Curculionidae: Scolytinae) is endemic to parts of Asia and was introduced into the southeastern United States in 2002. The beetle carries Raffaelea lauricola T.C. Harr., Aghayeva, & Fraedrich, a newly described fungal symbiont responsible for a wilt disease that affects...

Circadian clocks generate rhythms in molecular, cellular, physiological, and behavioral processes. Recent studies suggest that disruption of the clock mechanism accelerates organismal senescence and age-related pathologies in mammals. Impaired circadian rhythms are observed in many neurological diseases; however, it is not clear whether loss of rhy...

Circadian clocks maintain temporal homeostasis by generating daily output rhythms in molecular, cellular, and physiological functions. Output rhythms, such as sleep/wake cycles and hormonal fluctuations, tend to deteriorate during aging in humans, rodents, and fruit flies. However, it is not clear whether this decay is caused by defects in the core...

Introduction Promotor Analysis Results Discussion Summary and Conclusion Acknowledgments References

The antioxidative potential of the Manduca sexta adipokinetic hormone (Manse-AKH) in the last instar larvae of Spodoptera littoralis (Noctuidae, Lepidoptera) was demonstrated after exposure to oxidative stress (OS) elicited by feeding on artificial diet containing tannic acid (TA). Determination of protein carbonyls (PCs) and reduced glutathione (G...

Females of Osmia rufa, as most species in this genus, enter an obligatory diapause, overwintering as an imago inside a cocoon until the ensuing spring when after emergence - mating, egg development and oviposition occur. Diapause in this species is initiated in November, undergoes 2 months of a pre-wintering period that is terminated at the end of...

Changes in tissue-specific NADP-dependent malate dehydrogenase (MDH) activity and protein and cholesterol contents and retardation of growth and development in the mulberry silkworm, Bombyx mori L., induced by infection with a baculovirus, the B. mori nucleopolyhedrovirus (BmNPV), were investigated. The study revealed that the relative growth rate...

Daily rhythms generated by the circadian clock regulate many life functions, including responses to xenobiotic compounds. In Drosophila melanogaster, the circadian clock consists of positive elements encoded by cycle (cyc) and Clock (Clk) and negative elements encoded by period (per) and timeless (tim) genes. The φ-isoform of the PAR-domain protein...

There is increasing evidence that aging is affected by biological (circadian) clocks - the internal mechanisms that coordinate daily changes in gene expression, physiological functions and behavior with external day/night cycles. Recent data suggest that disruption of the mammalian circadian clock results in accelerated aging and increased age-rela...

Resembling the main function of insect adipokinetic hormones (AKHs), the vertebrate hormone glucagon mobilizes energy reserves and participates in the control of glucose level in the blood. Considering the similarities, the effect of porcine glucagon was evaluated in an insect model species, the firebug Pyrrhocoris apterus. Using the mouse anti-glu...

In view of the antioxidant role of glutathione (GSH) and ascorbic acid (AA), we have examined capacity of the GSH-AA redox cycle in relation to oxidative stress effects in the midgut of the Colorado potato beetle Leptinotarsa decemlineata. Adult gut harbors a higher capacity to cope with oxidative stress than the larval gut. Protein carbonylation w...

Circadian rhythms are fundamental biological phenomena generated by molecular genetic mechanisms known as circadian clocks. There is increasing evidence that circadian synchronization of physiological and cellular processes contribute to the wellness of organisms, curbing pathologies such as cancer and premature aging. Therefore, there is a need to...

The in vivo effects of oxidative stress on adipokinetic hormone (AKH) titer in short-winged (brachypterous) males of the firebug Pyrrhocoris apterus were tested using paraquat (PQ), a bipyridilium herbicide. PQ undergoes a cyclic redox reaction with oxygen during microsomal and electron transfer reactions forming free radicals in the insect body. O...

Representative species, two from each of the cockroach families Blattidae, Blattellidae, and Blaberidae, have similar morphology of the digestive tract but differ in the physiology of digestion. The pH of crop and along the midgut varies in different species from 5.9 to 9.0 and the redox parameter from 10.1 to 12.9. Activities of proteinases and am...

Injections of 38 pmol paraquat (1,1'-dimethyl-4,4'-bypyridilium) into adult Pyrrhocoris apterus (average body weight 29.6 mg in males and 36.9 mg in females) caused a significant elevation of lipid peroxidation and protein carbonylation and a decline of membrane fluidity in the microsomal brain fraction. Another manifestation of oxidative stress wa...

The level of adipokinetic hormones (AKHs) (Peram-CAH-I and II) in the corpora cardiaca and the hemolymph of Leptinotarsa decemlineata enormously increases in the adults fed on genetically modified potatoes containing either GNA lectin or Cry 3Aa toxin concomitant with increased oxidative stress in gut tissues. A similar enhancement of the AKH titer...

The titers of reactive oxygen species (ROS) represented by superoxide anion and general peroxides, and the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), are regulated in the midgut of the Colorado potato beetle (CPB) relative to the gut compartment, developmental stage, and food intake. ROS concentration is low in...

Allelochemicals play important roles in the plant defense against herbivorous insects. They act as feeding deterrents, interfere with digestion and nutrient absorption, and cause production of potentially dangerous oxidative radicals. This study demonstrates that the distributions of oxidative radicals and of the antioxidant enzymes that eliminate...

Nitric oxide production by the hemocytes of the last instar larvae and sessile pharate prepupa of Galleria mellonella (Lepidoptera: Pyralidae) was demonstrated in vitro in response to preparations of bacterial lipopolysaccharide (LPS) from Escherichia coli using the Griess reaction. Augmented, dose dependent nitric oxide production was observed in...

The Egyptian armyworm Spodoptera littoralis is a polyphagous insect attacking a number of plant species including those belonging to the Solanaceae and Cruciferaceae families. Its digestive physiology must therefore adapt to the food plant to ensure maximum extraction of nutrients with minimum trade-off in terms of growth retardation by pro-oxidant...

The haemocytes and haemolymph of the silkworm Bombyx mon L. were analysed for their superoxide dismutase (SOD) activity following Bacillus subtilis inoculation using a photochemical assay system consisting of methionine, riboflavin, and p-nitro blue tetrazolium. The SOD assay had a maximum activity at pH 7.8 with light exposure optima of 15 min. Th...

The relationship between nodulation response to bacterial infection and exogenous application of 3,4-DL-dihydroxyphenyl alanine has been examined in the silkworm Bombyx mori. Intrahaemocoelic injections of the bacteria Bacillus thuringiensis var. sotto, to fifth instar larvae, followed immediately by injections of 3,4-dopa resulted in significant (...

For elucidation of vertebrate estrogen-induced responsiveness of fat body cells of insects, various doses (0.5, 1.0, 5.0, 10 and 50 μg) of 17-β estradiol (E2) were injected thrice, at 5 day intervals, to 130-day-old diapausing pupae of Antheraea mylitta and the changes in cytosolic NADP+-dependent (cMDH, EC 1.1.1.40) and mitochondrial NAD+-dependen...

The presence and role of the biogenic amine, octopamine has been demonstrated in Antheraea mylitta during pupal diapause. For elucidation of estrogen-induced responsiveness of insects, three consecutive injections of estradiol-17-β (E2) at doses of 1, 5, 10 and 50 μg/pupa on days 130, 135, and 140 of pupal age were injected to both male and female...

The agar gel double diffusion test was evaluated for detection of nuclear polyhedrosis virus infecting the silkworm, Bombyx mori L. (BmNPV). The test was successful using alkali-dissolved BmNPV as antigen. The antiserum raised against dissolved BmNPV gave positive results with a wider range of antigenic concentrations compared to antiserum raised a...

Silkworm larvae infected transovarially with Nosema bombycis were fed with an aqueous suspension of Bavistin (50% carbendazim w/w) at 2 and 3% concentrations. The treatments increased the survival of worms and reduced the pebrine infection in the lot significantly, although complete elimination of infection was not observed. Significant beneficial...