Venomous substances

Insect venoms. Substances excreted by many species of insects for protection or predatory purposes that are more or less toxic for other oiganisms. They are produced in various skin or body glands and used when required for attack or defence (see also defensive secretions). The compounds are used in many different ways some species have penetrating (e.g., mosquitoes, bugs) or biting (ants) mouth parts or modified... 

Secretions from Glands and Other Specialized Tissues. In general, parasitic Hymenoptera are known to inject secretions from glands and specialized tissues into their hosts. Those secretions, except for the symbiotic viruses and virus material or calyx fluid, are collectively presented in the next two sections as venomous substances. 

Nonparalyzing Venoaous Substances. Often the injection of the virus material and nonparalyzing venomous substances occur simultaneously so that the effects are not easily separated. Reference is made in this section to reports where venomous substances were shown to perform a function independent of symbiotic... 

A diversity of functions and a variety of developmental abnormalities have been associated with nonparalyzing venomous substances. Of the four sources of regulatory factors reviewed in Table I, venomous substances are common to species in all the families represented, by ecto- and endoparasitoids alike, and the only source of regulatory substances in ectoparasitoids known to affect the development of the host. 

The development of Orthosia stabilis was arrested after stinging by the gregarious ectoparasitoid Eulophus larvarum. During the period of arrested development, the host was recorded as mobile and continued to feed for a period of time but failed to produce a new cuticle or initiate apolysis (119). This effect was attributed to a venomous substance, presumably transferred from the parasitoid to the host at the time of stinging, and was shown to be independent of oviposition or the developing parasitoid. 

Nudibranch dermatitis, antigenic venom substances in aquatic environment... 

Other Lethal Agents. There are a number of substances, many found in nature, which are known to be more toxic than nerve agents (6). None has been weaponized. Examples of these toxic natural products include shellfish poison, isolated from toxic clams puffer fish poison, isolated from the viscera of the puffer fish the active principle of curare "heart poisons" of the digitaUs type the active principle of the sea cucumber active principles of snake venom and the protein ricin, obtained from castor beans (See Castor oil). 

Write the Lewis structure of each of the following organic compounds (a) ethanol, Cl IjCLLOH, which is also called ethyl alcohol or grain alcohol (b) methylamine, CH3NH2, a putridsmelling substance formed when flesh decays (c) formic acid, HCOOH, a component of the venom injected by ants. 

Hymenoptera venoms are composed of biogenic amines and other low molecular weight substances, of basic peptides and of proteins. Injection of venom by Hymenoptera stings has toxic effects, due to biogenic amines, peptides and proteins biogenic amines such as histamine cause pain, are vasodilatory and increase... 

Once injured or activated by a toxic substance (e.g., bacterial toxins, placenta chemicals, snake venom, etc.), endothelial cells and monocytes respond by generating tissue factor on the cell surface. This, in turn, leads to the generation of tissue factor-factor Villa complexes, followed by unregulated and excessive generation of thrombin, fibrin, systemic microthrombi and consumption of coagulation factors,... 

Ticks have a bad reputation for good reasons. Not only are they carriers of a number of diseases, the saliva of some can cause paralysis. North American natives were aware of tick paralysis, but the condition was officially noted as a disease of both animals and humans in 1912. The bites of at least 60 species of ticks can cause paralysis, which often does not appear until several days after the bite. The first indication is redness and swelling around the site of the bite. This is followed by neuromuscular weakness and difficulty in walking. If the tick is not removed, speech and breathing are affected, with eventual respiratory paralysis and death. Fortunately, removal of the tick results in a quick recovery of function. The exact mechanism of paralysis is not known but it appears to come from a substance that affects the neuromuscular junction. While not related to the venom of the tick saliva, the tick can also transmit diseases such as Lyme disease, Rocky Mountain spotted fever, Q fever, typhus, and others. Table 13.1 lists some venomous arachnids. 

Wasp stings tend to contain less protein and a more formic acid-type substance that produces an intense burning. Table 13.2 lists some poisonous and venomous insects. 

In vitro studies elsewhere have shown the presence of a substance in the bark which antagonizes the cardiotoxin present in cobra venom (20). This fraction did not contain alkaloids, however. 

Aetinidine (9a) has been identified as an anal gland product of three species of dolichoderine ants in the genera Conomyrma and Iridomyrmex (Table I). The venoms of ants of the Myrmecia species are rich in histamine (136) (Table VIII), which can act as a defensive substance, together with hemolytic, smooth-muscle-stimulating, and histamine-releasing components. 

Histamine may be released from mast cells by mechanisms that do not require prior sensitization of the immune system. Drugs, high-molecular-weight proteins, venoms, and other substances that damage or disrupt cell membranes can induce the release of histamine. Any thermal or mechanical stress of sufficient intensity also will result in histamine release. Cytotoxic compounds, may release histamine as the result of disruption of cell membranes. 

Drugs, particularly organic bases, may release histamine from mast cells by physically displacing the amine from its storage sites. Morphine, codeine, d-tubocu-rarine, guanethidine, and radiocontrast media can release histamine from mast cells. Basic polypeptides, such as bradykinin, neurotensin, substance P, somatostatin, polymyxin B, and the anaphylatoxins resulting from complement activation, also stimulate histamine release. Venoms often contain basic polypeptides as well as the histamine-releasing enzyme phospholipase A. 

---