Literature review Overview of Published Work Insects encounter diverse foreign materials (i.e. xenobiotics) at different stages of their lifecycle. Xenobiotics which are usually lipophilic could be of plant origin (allelochemicals) or from insecticides and can cause toxic effects. In order to cope with the challenge posed by these toxic chemicals in its body, insects have developed different detoxification mechanisms which are categorized into two phases based on the kinds of reactions that occur i.e. Phase I and Phase II. Phase 1 reactions include oxidation, hydrolysis and reduction and they generally convert xenobiotic substrate into more polar products which can be excreted or subjected to phase II reactions. The phase II reactions are conjugation reactions involving endogenous compounds like amino acids, glutathione and others, thereby increasing the water solubility of the xenobiotic, making it easily excreted (1). It is worthy of mention that in some cases reactive intermediates can be formed that are much more toxic than the parent compound; bioactivation. A classic example is seen in organophosphate insecticides (Smith 1962) and the carcinogenic metabolites of aryl hydrocarbons (Feyereisen 2005). Considering the afore-mentioned statements, it is best to call the whole process as a metabolic process which could result in detoxification or activation, the former been the focus of this review. This review focus on essential systems of detoxification in insects (Terriere, 1984); Cytochrome P450s (Phase I-oxidase), Glutathione S-transferases (Phase II-conjugants) and Carboxyesterases (Phase I-hydrolases). Cytochrome P450s This represents a large superfamily of enzymes encoded by CYP genes. They are hemoproteins with varying ... ... middle of paper ... ...ges. Ahmad (1983) also proposed that induction of P450 is not related to host to preference but it is likely in response to plant allelochemicals. Qualitative and quantitative difference exists among plant allelochemicals in plant species. Moldenke et al. (1983) focused on the induction effect of three monoterpenes found in peppermint on the sixth instar of Peridoia saucia; pulegone, menthone and menthol. These phytochemicals were fed to the Peridoia saucia at 0.01% - 0.1% of diet. There was no significant difference in the level of induction caused by the three allelochemics; probably due to their closeness in chemical nature. Furthermore, the mixture of the three compounds did not yield greater P450 induction. This is also suggestive that qualitative difference among plant allelochemics might also have effect on induction of P450 and other detoxification enzymes.
..., Department of Zoology, Miami University, Oxford, OH, Available from Journal of Insect Physiology. (46 (2000) 655–661)Retrieved from http://www.units.muohio.edu/cryolab/publications/documents/IrwinLee00.pdf
Stevenson PA, Hofmann HA, Schoch K, Schildberger K. 2000. The fight and flight responses of crickets depleted of biogenic amines. Journal of Neurobiology 43:107-120.
...of sublethal concentrations of fenitrothion on beet armyworm (Lepidoptera: Noctuidae) development and reproduction. Pesticide Biochemistry and
Steel, C. G. & Vafopoulou, X. 2006. Circadian orchestration of developmental hormones in the insect, Rhodnius prolixus. Comparative Biochemistry and Physiology – Part A: Molecular & Integrative Physiology, Vol. 144, pp. 351-364
A study was undertaken by Cutler and Scott-Dupree (2007) in order to understand the long term effects of field exposure to cothianidin (a class of neonicotinoid) through flowering canola, on 32 honey bee colonies, Apis melilfera L. In the study, there were four treated and four untreated fields. Four colonies per field were located either in the middle of the 1-ha clothianidin treated fields or untreated canola fields for a period of 3 weeks (Cutler and Scott-Dupree, 2007). Liquid chromatography and mass spectrometry detection were used to measure the amount of clothianidin residues in honey, beeswax, nectar and pollen (Cutler and Scott-Dupree, 2007). The results of the study were such that: although residues of clothianidin were found in pollen, nectar and honey for the colonies in the treated fields, with the highest concentration being 8-22 fold, the amount of honey produced and the weight gains were similar with those in the control fields. The treated overwintered colonies also did not show any significant differences than the control canola field (Cutler and Scott-Dupree, 2007). Thus, the study concluded that there will not be any long-term affect due to exposure to canola seeds that have been treated with
Anthocyanins, flavanols, flavanones,secoiridoids, phenolic acids, stilbenes, coumarins, and isoflavones form a large class of polyphenols, which are phenolic compounds. This study, however, focuses on one category of these phenolic compounds: phenolic acids. These particular compounds have been classified into two groups, namely hydroxycinnamic acids and hydroxybenzoic acids. The most common hydroxybenzoic acids are protocatechuic acid and gallic acid, while hydroxycinnamic acids include ferulic acid, coumaric acid, caffeic acid, chlorogenic acid, and sinapic acid, (Nigdikar, Williams, Griffin, & Howard). Unlike hydroxycinnamic acids, hydroxybenzoic acids usually occur at very low levels in some black radish, red fruits, and onions, accounting for about 10 ppm on a fresh weight basis. Protocatechuic ac...
Imagine being in a family that is expecting their first child. Articles in the newspaper are showing how the chances of miscarriages are increasing. As soon as anxiety starts to take over, a flip of a page in the newspaper changes everything. An article about a new drug called Diethylstilbestrol seems to be on the next page. Diethylstilbestrol, also known as DES, is a medicine that helps prevent women from having pregnancy complications including miscarriages. “This is amazing!” one may say, but do they really know the consequences of taking this new medication? Diethylstilbestrol was a huge turning point for most pregnant women in the early twentieth century; however, it had many underlying negative consequences that would later affect the mother and child with the word no one ever wants to hear; cancer.
Two studies have shown that the resting metabolic rate of 11 species of cockroaches were VO2=0.261 Moles (Coelho and Moore, 1989) and 3 species of crickets were VO2=0.277 (Prestwich and Walker, 1981) are very similar.
Saxena, M. C., Siddiqui, K.J., Agarwal, Vinita and D. Kuuty. 1983. A comparison of organochlorine insecticide contents in specimens of maternal blood, placenta, and umbilical-cord blood from stillborn and live-born cases. Journal of Toxicology and Environmental Health: II: 7 1 - 79.
How this works is billions of neurons (nerves cells) are placed in the human system and they send electrical impulses to the nervous systems. These impulses control ones movement, feelings, pain, and sensory information and so on. Digging into the neuron, is its components: dendrites, soma, and axon. The dendrites receive signals from other neurons while the axon is the sender. The soma is the body of the neuron. In addition, between the spaces of the neurons are synapses. These contain effector cells, which carry out signals (neurotransmitters) to the next cell or neuron to create a desired action. Now, if the neonicotinoids block a specific chemical pathway which inhibits the communication between the neurons and the central nervous system, then one of these said parts must be affected by the insecticide. The neonicotinoids could destroy the dendrites and/ or the axons because that would prevent the electrical impulses being passed and received. When the central nervous system cannot rely or send any messages to the rest of the body, then it becomes paralyzed. This is how neonicotinoids cause the death of insects and possibly the
Allelopathy is the beneficial or harmful effect that one plant has on another. It occurs by the discharge of chemicals from plants by leaching, root exudation, volatilization, and residue decomposition. Allelopathy can affect the growth, occurrence, plant succession, dominance, diversity, and productivity of a plant. While allelopathy first referred to the negative effects of one plant on another, it has been broadened to include beneficial effects. Common effects of plant allelopathy are reduced seed germination and seedling growth. Although there is no common target site for allelochemicals, common sites of action are cell division, nutrient uptake, pollen germination, and photosynthesis. Allelopathy involves the interaction of phenolic compounds, flavonoids, terpenoids, alkaloids, steroids, carbohydrates, and amino acids. Sometimes mixtures of...
Biochemistry, often called biological chemistry, is the process of understanding chemical processes occurring within and relating to living organisms. By monitoring data flow through biochemical signaling and the current of chemical energy through metabolism, biochemical procedures give rise to the intricacy of life. Over the last 40 years, biochemistry has become so effective at explaining living processes that now almost all parts of the life sciences from botany to medicine are involved in biochemical research. Today, the main emphasis of pure biochemistry is in understanding how biological molecules give rise to the developments that occur within living cells, which in turn relates largely to the study and understanding of complete organisms.
Frequency of application is defined as how often an insecticide is used that influence resistance development. Resistance can happen in many ways such as met...
This is why I decided to focus my research on the effects that foreign substances have on plants. The substances I will focus on are two of the most common and well known substances that people but in their bodies.
The leaves of local wild and cultivated plants are of vegetables which are rich in starch and part of African diet (Smith, 2007). Some of these African leafy vegetables can also be classified as functional foods because they contain high nutrient which are beneficial to human health (Van wyk, 2003). Green plants absorb the minerals they need for diverse anabolic processes from the soil, the complex organic compounds found in plant leaves are antioxidant molecules which serves as protection against oxidative solar radiation (Zimmermann, 2005). Leafy vegetables are therefore important sources of minerals, trace elements and photochemical with health protective and immune–strengthening properties. Molecular evidences shows that the trace elements in leafy vegetables and antioxidant molecules present lowers the risk of cancer and cardiovascular disease through a mechanism that molecule free radical attack on nucleic acids, proteins and polyunsaturated fatty acids (Borek,2003). This is an indication that leafy vegetables have a higher antioxidant properties compared to e...