Re: First Botany 135 Exam, October 11, 2005-Mycotoxins

[Guest guest]

kc, THIS MAY BE A GOOD ARTICLE TO ADD WITH THIS, IT DOESN'T TALK

ABOUT MOLD/MYCO'S BUT TALKS ABOUT CHEMICAL INDOORS, MAINLY IN LOW

AMOUNTS AND CHEMICALS THAT COME IN FROM OUTSIDE. WHATS INTERESTING IS

THAT IT TALKS ABOUT THESE CHEMICALS INDOORS AND HOW THEY ATTACH TO

OTHER PARTICLES IN THE AIR AND HOW WE NOT ONLY INHALE THEM ALL BUT

THEY ALSO LAND ON OUR FOOD AND WE CONSUME THEM. I THINK THE CHANCES

ARE PRETTY GOOD THAT A MOLDY ENVIRONMENT INDOORS ACTUALLY CAUSES US

TO CONSUME MANY THINGS IN OUR INDOOR ENVIRONMENT. BESIDES THE MYCO'S,

SPORES IN OUR AIR SPORES MAY BE ALLOWING THESE CHEMICALS TO ATTACH TO

THEM.MOLD MAY BE EATING ON THINGS WITH THESE CHEMICALS AND OFF GASING

THEM, ECT. I JUST THINK IT'S IMPORTANT THAT PEOPLE UNDERSTAND THAT

SICK BUILDING SYNDROME IS NOT JUST ABOUT MOLD BUT THAT MOLD MAY BE

CAUSEING ALL THESE THINGS IN OUR ENVIRONMENT TO AFFECT US MORE. THE

AMOUTS OF IT ALL INHALED, CONSUMED, ECT. I FELL THIS IS WHAT LEADS TO

MCS, THE COMBINATION OF ALL OF IT AND THE AMOUNTS. I DIDN'T READ THE

WHOLE THING ONLY THE FIRST PART. BUT I CAN SEE HOW DAMP SPORES

RELEASED INSIDE WOULD BE LIKE A MAGNET FOR ALL PARTICLES TO ATTACH

TO. JUST MY THOUGHTS, SEE WHAT YOU THINK.

RANKING CANCER RISKS OF ORGANIC HAZARDOUS AIR POLLUTANTS IN THE

UNITED STATES.

http://www.ehponline.org/members/2007/9884/9884.pdf

--- In , " tigerpaw2c " <tigerpaw2c@...>

wrote:

>

> This primarily deals with ingestion, but it contains alot of

> interesting information concerning mycotoxins.

>

> KC

>

> First Botany 135 Exam, October 11, 2005

>

>

> http://www.botany.hawaii.edu/faculty/wong/BOT135/lect11.htm

>

> Mycotoxins

> Introduction

>

> Fungal diseases are common place in plants and animals. In such

> diseases, the fungi are actively growing on and invading the body

of

> their hosts. There is another means by which fungi can cause harm

> without invading our bodies. When fungi grow on a living organism

or

> on stored food material that we consume, they may produce harmful

> metabolites that diffuses into their food. It is believed that

fungi

> evolved these metabolites as a means of protecting their food

supply

> by preventing other organisms from eating it. These metabolites are

> referred to as mycotoxins, which literally means " fungus poisons " .

> Fungi that produce mycotoxins do not have to be present to do harm.

> If a fungus was growing in, say a grain storage silo, the

> environment may have become unsuitable for the fungus and it dies.

> Even though the fungus is no longer alive, while it was growing, if

> it produced a mycotoxin, it will have poisoned the grains. So for

> those of you who are always looking to save a little money by

buying

> cheese that has been contaminated with a fungus and cutting out the

> part where the fungus is growing, perhaps this is not such a good

> idea. It is possible that the fungus growing on your cheese has

> produced a mycotoxin that has diffused throughout the cheese, even

> though the fungus itself has not. The effects of poisoning by

> mycotoxin is referred to as mycotoxicoses. The knowledge that

> mycotoxicoses is the result of fungal actions was a relatively,

> recent discovery. This is understandable since illnesses in this

> case is due to consumption of mycotoxins that has been released by

> the fungus and is not directly caused by the fungus. So

> demonstrating this would not have been an easy task.

>

> We now know that many species of fungi produce mycotoxins, but why?

> It is thought fungi have evolved production of various mycotoxins

in

> order to prevent other fungi or animals from consuming " their "

food.

> By secreting their mycotoxin into their food the fungus will

inhibit

> growth of other fungi and discourage rotten or other small animals

> from eating their food.

>

> We will have several lectures on mycotoxins. Today, we will cover

> some of the more common mycotoxins that are produced by by molds

> growing in food and describe their symptoms. The following two

> lectures will be concerned with a number of different toxins that

> are all derived from Claviceps purpurea, the fungus responsible for

> the disease on rye, commonly referred to as Ergot, and later in the

> semester we will talk about mushroom toxins.

>

> Early Attempts to Demonstrate the Existence of Mycotoxin

>

> The existence of mycotoxins was not documented until 1960. However,

> just as in the case of diseases, the concept that moldy food could

> lead to illness in people or domestic animals was long suspected

> before their existence was demonstrated by science. It is a greater

> problem, presently, than it was in the distant past. Long ago,

> before there was adequate means of long term storage for perishable

> goods, food was normally consumed a short time after it was

> acquired, but as the world has become more industrialized and

> technological advanced, storage of food has become more of an

issue.

> Food is now commonly stored for long periods of time, giving fungi

a

> greater opportunity to contaminate our food.

>

> Before 1900, in Italy, researchers there believed consumption of

> moldy corn by children led to the development of illness

> (Christensen, 1975). Some experiments, done at that time, included

> the isolation, and growth of the suspected fungus in pure culture,

> and isolation of toxic compounds from the fungus that the

> researchers believed to be the cause of the illness. However, since

> the compound was not identified and was not actually isolated from

> the moldy corn, it could not be concluded that this compound was

the

> cause of the illness or that the compound in question was even

> present on the moldy corn. Nevertheless, it appeared that there was

> a correlation between the illness and consumption of moldy corn,

but

> this did not eliminate the possibility that it was the fungus,

> itself, that caused the disease, which most people believed to be

> the case. It was also possible that there were other reasons for

the

> illnesses that were observed.

>

> Burnside, et al (1957) studied an extensive outbreak of moldy corn

> disease in the southeastern United States in the early 1950's where

> hundreds of wild pigs foraging in cultivated corn fields became

ill,

> and many died. Teams of veterinarians and mycologists collaborated

> to determine the cause of the deaths of these pigs. They isolated a

> number of different fungi from the moldy corn and inoculated each

> fungus on moist corn that had been sterilized and then fed them to

> pigs. The consumption of corn inoculated with Aspergillus flavus

> caused outward signs and inward lesions found in other cases of the

> so-called moldy corn disease. However, since there was no toxin(s)

> isolated, there was little attention paid to the article since it

> still seemed like old news, i.e. domestic animals poisoned by

eating

> moldy corn.

>

> It would not be until 1960, when approximately 100,000 turkeys and

a

> lesser number of other domestic birds died in England, causing

> losses of approximately several hundred thousand dollars, before

the

> first mycotoxin was isolated and identified. As you might guess,

> this did not happen immediately. Initially, the disease was thought

> to be caused by a virus and the syndrome was named " turkey-X

> disease " . The " X " here indicated that the cause of the disease was

> unknown. However, with a great deal of detective work, on the parts

> of the researchers, soon the cause of the disease was traced to

feed

> that was produced by Oil Cake Mills, Ltd. (research always seems to

> get done more quickly and receive more priority when loss of large

> sums of money is involved). The oil cake feed was composed mostly

of

> peanuts. However, it seemed unlikely that the peanut meal itself

was

> toxic, since peanut meal had long been used as a feed ingredient

and

> was known to be an excellent source of protein. Thus, it was

> reasoned that something must have been added to the peanut meal to

> make it toxic, and one possibility that was investigated was that

> peanuts had been made toxic by fungi growing in them. From their

> isolations, the investigators identified Aspergillus flavus, the

> same fungus that was isolated by Burnside and his research teams.

> The isolated fungus was again inoculated into the feed and fed to

> the turkeys. Shortly after feeding, the turkeys died with external

> signs and internal lesions identical to those observed in the birds

> that had previously died in the field.

>

> Unlike Burnside, however, chemists were also employed in this

> investigation, and they were able to isolate and identify the toxin

> from the oil cake feed. The mycotoxin isolated was named aflatoxin,

> the " a " from Aspergillus and " fla " from flavus. Feeding test of

food

> containing aflatoxin, with various laboratory animals, demonstrated

> that to varying degrees, all animals tested were sensitive to

> aflatoxin. Even consumption of extremely small amounts of aflatoxin

> damaged various internal organs and could induce development of

> cancer to the liver.

>

> This was of great concern among the nutritionists and those

> concerned with problems of pubic health, e.g. The Food and Drug

> Administration. There was great concerned domestically since

peanuts

> and peanut products were/are of economic importance. It was also of

> international significance, since peanuts at that time was being

> lauded as an excellent source of protein, for developing countries,

> by UNICEF (United Nations International Children's Emergency Fund)

> and other such organizations. Deficiency in protein often results

> in " kwashiorkor " .

>

> Kwashiorkor (kwä´shê-ôr´kôr´), protein deficiency disorder of

> children, prevalent in overpopulated parts of the world where the

> diet consists mainly of starchy vegetables, particularly Africa,

> Central and South America, and S Asia. Such a diet is deficient in

> certain amino acids, which make up proteins vital for growth.

> Depending on the extent, onset, and duration of the deficiency,

> manifestations include skin changes, edema, severely bloated

> abdomen, diarrhea, and generally retarded development. The Concise

> Columbia Encyclopedia is licensed from Columbia University Press.

> Copyright © 1995 by Columbia University Press. All rights reserved.

>

> Other characteristics include anemia, depigmentation of the skin,

> and loss of hair or change in hair color. Usually, occurring in

> children, shortly after weaning. Peanut products were developed in

> various forms, especially in tropical and subtropical countries,

for

> general distribution. Were these people now exchanging kwashiorkor

> for potential risk of liver damage and cancer from consuming

> aflatoxins? Thus, there was a great deal at stake, which provided

an

> impetus to act on this matter, immediately. In the United States,

as

> soon as awareness of aflatoxins surfaced in the 1960s, programs

were

> established by peanut growers, aided by concentrated research, to

> reduce the possibility of aflatoxin occurring in edible peanuts and

> peanut products. That they have been successful is indicated

through

> random sampling, by the FDA, of only an occasional batch of peanut

> products that contains aflatoxin. What has been discovered have

> almost never been found in sufficient amount to be of any real

> concern. However, in other countries, in which there are no such

> regulatory bodies, the people undoubtedly consume an appreciable

> amount of aflatoxins.

>

> The Fungus

>

> Aspergillus flavus is actually not a single species, but a " species

> complex " , made up of eleven species that are known to occur in many

> kinds of plant materials, including stored grains. One of the

> species in the complex, A. oryzae has long been used in the Orient

> to prepare various kinds of food products, such as sake, tofu and

> soy sauce, which in turn is used in the United States. Were

> aflatoxins present in these products as well? This was a question

> that needed to be answered. Research began to take place at a rapid

> pace and continues to do so. The number of papers published that

> have to do with aflatoxins number in the hundreds annually.

>

> What was determined in early research of aflatoxins is that the

> conditions which allows for growth of A. flavus and aflatoxins is

> very narrow. Aspergillus flavus seldom invades stored grains alone,

> i.e. as a pure culture. Various other species of fungi will

normally

> grow on a substrate prior to invasion by A. flavus, e.g. A. glaucus

> and Candida pseudotropicalis. In a preinvaded substrate, regardless

> of how dense the A. flavus invasion may be, aflatoxin will not

form.

> This was demonstrated at the University of Minnesota where A.

flavus

> as well as other fungi were grown on grain at moisture content and

> temperature range that were optimal for aflatoxin production.

> Although, there was a very dense mycelial growth of A. flavus, the

> grain that was fed to the various kinds of experimental animals,

> ducklings, white rats and baby chicks, for as long as eight months,

> there was not a single case of death from consumption of the feed.

> In fact, weight gain was the same as that of those animals not fed

> the with grain containing the fungal growth. Thus, the amount of

> mycelial growth that occurs in animal feed, with several species of

> fungi involved, even if one is known to be an aflatoxin producer,

> was apparently safe to consume. Thus, in order for aflatoxin

> formation to occur in say a storage bin full of peanuts, A. flavus

> must be growing alone and the peanuts cannot have been previously

or

> simultaneously invaded by other fungi, an occurrence that is rare.

> In the case of the Turkey-X disease, the peanuts that were

> responsible for the aflatoxin poisoning were from South America,

> where the process used to harvest and dry the peanuts was

> responsible for providing an environment that allowed for growth of

> A. flavus and aflatoxin. Aspergillus flavus does not normally

> contaminate grains and other crops while they are still in the

> field. It is only after the grains are harvested and stored does A.

> flavus, as well as other so-called " storage fungi " that have a low

> moisture requirement, can the grain be invaded. Although conditions

> favorable for growth of the A. flavus and production of aflatoxin

is

> narrow, the fungus is common and widespread in nature. It can be

> found growing on various decaying vegetation where it may heat up

> the substrate to as high as 113-122°F as it consumes the material.

>

> The amount of aflatoxin formed differs as to the substrate on which

> it is growing. Although the mycelial mass may be the same in each

> substrate, the aflatoxin produced would be far greater in peanuts

> than in say soybeans, where relatively very little would be

> produced. Other seeds of cereal crops, wheat, corn, barley, oats

and

> sorghum are also generally of low-aflatoxin-risk. Weather and

> climate were also contributing factors. Finally, the amount of

toxin

> produced will vary with the isolate of A. flavus. That is different

> sources of A. flavus will produce different amounts of aflatoxins.

> Some isolates of A. flavus may not even form aflatoxin.

>

> Strange as this may sound, in some cultures, fungi are encouraged

to

> grow on certain foods in order to give them the desired taste. For

> example, the Bantu tribes in Africa prefer the sour flavor of

partly

> spoiled corn to that of fresh corn and fungus is purposely allowed

> to grow on the corn for this reason (Christensen, 1975). However,

> this may only be a coincident, but they also have a very high

> incident of primary liver cancer.

>

> How much aflatoxin is too much?

>

> Christensen (1972), over a period of several years, examined 100

> different samples of black pepper from all over the world. In

> dilution cultures of these samples, the number of fungus colonies

in

> whole or ground black pepper averaged 52,000 per gram/black pepper

> and the upper range was over half a million per gram. These

colonies

> were mostly of A. flavus, A. ochraceus and A. versicolor. All three

> species are known to be aflatoxin producers. Some samples of ground

> pepper were caked lightly with fungus mycelium when first opened in

> the laboratory and with time, a number of these became solidly

caked

> with mycelium.

>

> How heavily contaminated is 52,000 to 500,000 colonies of fungi,

per

> gram? Lets make a comparison for what is acceptable levels of

fungal

> colonies isolated in other food products at the time Christensen

> published his results. Wheat, for example, that is intended for

> milling into flour seldom contains no more than a few thousand

> colonies of fungi per gram of grain. If barley has as many as

10,000

> colonies of the same kind of fungi per gram as in black pepper, it

> would be rejected for malting in beer making. If breakfast cereals

> or bread were as contaminated as black peppers, they would have so

> musty an odor and taste that they would be too revolting to eat.

> Apparently, the natural spicy odor and flavor of black, as well as

> white pepper are potent enough to conceal the taste and odor of

> these fungi. This is also true with many other spices.

>

> One sample of black pepper was even found to contain a rodent

> dropping and a piece of stone about the same size as the pepper.

> Most samples contained peppers partly eaten by insects and partly

or

> mostly decayed by fungi and bacteria. However, you should keep in

> mind that at the time Christensen carried out his little study,

> quality control was not as much of an issue as it is today. With

the

> quality standards that are being enforced, presently, food products

> with the type of contaminations described above would not be

allowed

> on the market.

>

> What about the processed food prepared with A. flavus? At least, in

> the commercial strains that have been utilized to prepare food in

> the United States, the strains that have been tested have not been

> found to produce aflatoxins. However, where these products are

> prepared in a household or village industry, and the fungus is just

> carried from one batch to the next, wild strains capable of

> producing aflatoxin may contaminate them. In an investigation, in

> the Philippines, not a single sample was found that was free of

> aflatoxin. In such communities probably everyone was suffering to

> some extent from chronic aflatoxin poisoning.

>

> Mycotoxins in Other Species of Aspergillus, Penicillium and

Fusarium

>

> Aspergillus ochraceus and ochratoxin

>

> Aspergillus ochraceus is also a species complex, and consist of

nine

> species. These species are common in soil, decaying vegetation, and

> in stored seeds and grains undergoing microbial deterioration.

> However, this fungus is seldom isolated from more than a small

> percentage of seeds or grains that are undergoing microbiological

> deterioration in storage because it is evidently not a good

> competitor, as is also the case with A. flavus. This is a general

> rule, but at the University of Minnesota, A. ochraceus sometimes

has

> been isolated from 40% or more of surface-disinfected kernels of

> corns from bins in which deterioration was in progress. It has also

> been the major organism in some lots of whole black pepper. Also,

> samples of macaroni and spaghetti were found to be heavily invaded

> by this species.

>

> Production of ochratoxin, by A. ochraceus, was first described in

> South Africa by Theron, et al. (1966), where it was isolated along

> with a number of other fungi. In experiments done with this

isolate,

> the LD50 (the single dose that will kill 50 percent of the

> individual animals tested) of ochratoxin for rats is 22mg/kg (= 22

> milligrams of the toxin per kilogram of body weight of the rat),

but

> a lesser amount will result in severe liver damage. A single dose

of

> 12.5 mg/kg (=12.5 milligrams of the toxin per kilogram of body

> weight of the rat) was administered to pregnant rats on the tenth

> day of gestation, and of the 88 fetuses involved, 72, or 81.8% died

> or were resorbed. Ducklings seem to be equally sensitive to

> ochratoxin as they are to aflatoxin.

>

> Another fungus, Penicillium viridicatum, can also produce

> ochratoxin, and is relatively common in stored corn and is a more

> common producer of ochratoxin than A. ochraceus.

>

> Aspergillus versicolor and sterigmatocystin

>

> This species is another storage fungus. However, it is never found

> as the only fungus or as the predominating fungus in deteriorating

> cereals. Normally, by the time a grain sample has become very

moldy,

> A. versicolor, along with other Aspergillus species and usually

> other filamentous fungi and yeasts as well. Some of the black

pepper

> mentioned earlier, as being decayed by fungi, was very heavily

> invaded by A. versicolor, but not by this fungus exclusively.

>

> One rather interesting case concerning this species took place, on

> germinating barley, in a malthouse, in Scotland. The growth of A.

> versicolor was so luxuriant on the germinating barley and produced

> so many spores, that the workers who turned the malts with shovels

> could not see one another because of the spore-filled air. The

> owners and managers of the malthouse hired a mycologist to

determine

> how the fungus was getting in. They had assumed that the

> contamination must have been due to the incoming barley. What the

> mycologist concluded, however, was that there was a lack of

sanitary

> conditions, in the malthouse, and that everything in and around

that

> malthouse must have been thoroughly and heavily contaminated by A.

> versicolor spores (and probably a lot of other fungi as well). So,

> when conditions were favorable, i.e. when the barley was brought

in,

> the growth of fungi grew to spectacular quantities. Can you imagine

> working in such an environment and having to inhale those spores?

>

> This species, under the right conditions, produces

sterigmatocystin,

> a toxic compound given the name because the fungus once was called

> Sterigmatocystis. The toxin is known to cause lung and liver tumors

> in laboratory animals and has been implicated as the cause of

> disease in calves that have consumed feed heavily invaded by A.

> versicolor. Experiments carried out in which the fungus were grown,

> on feed that was fed to calves, produced symptoms of the disease in

> the calves. However, tests were not done to detect the toxin in the

> calves. The toxin has also been detected in moldy coffee beans in

> Africa, but no evidence indicates that even if these beans were

used

> to brew coffee that the toxin would be in the drink.

>

> Aspergillus fumigatus and fumagillin

>

> This particular species is known to be an animal pathogen.

Infection

> occurs through inhalation of spores and affects the lungs.

Infection

> may also occur in eggs and the fetuses of cows. However, it also

> produces a metabolic product that may be considered a toxin or an

> antibiotic. This species differs from the others that we have

> discussed in that it is said to be thermophilic, that is, it is

> found in substrate where there are extremely high temperatures, up

> to 122ºF (=50ºC). This species is usually found on material that is

> in the advanced stages of decomposition in which the substrate

> temperature has been significantly raised by microbial

decomposition.

>

> Under the proper conditions, A. fumigatus produces fumagillin. This

> compound is used as an amoebicide, that is, as a means to rid the

> body of amoebae that are human pathogens and has been used

> effectively in honey bees as well. However, the correct dosage of

> this compound is critical. A little bit more than you need to get

> rid of the amoebae and you will be getting rid of the patient as

> well.

>

> The Genus Fusarium

>

> Species of Fusarium are widespread in nature as saprobes in

decaying

> vegetation and as parasites on all parts of plants. Many cause

> diseases of economically important plants. For this reason, there

> has been a great deal of research carried out in this genus by both

> plant pathologist and mycologist. However, there are a number of

> species that produce mycotoxins, mostly trichothecenes and

> zearalenone. We will discuss a few common examples.

>

> Fusarium tricinctum

>

> The effects of the first trichothecene toxin, T-2, documented was

in

> the 1940s where it was associated with an outbreak of alimentary

> toxic aleukia (ATA). At its peak, in 1944, the population in the

> Orenbury District and other districts of the then USSR suffered

> enormous casualties, more than 10 percent of the population was

> affected and many fatalities occurred. The term alimentary toxic

> refers to the toxin being consumed in foods and aleukia refers to

> the reduced number of leucocytes or white blood cells in the

> affected person. Other symptoms included bleeding from nose and

> throat, multiple, subcutaneous hemorrhages.

>

> The infected food in this case was millet, which made up a great

> part of the diet of the people in the region, and at times, during

> WWII, it was not uncommon to allow the millet to be left standing

in

> the fields over winter because bad weather in the fall prevented

its

> harvest at the proper time. During the late winter and early spring

> the millet would become infected with a variety of fungi, including

> F. tricinctum, and when the people gathered and ate this fungus,

> many came down with what was diagnosed as ATA. Thousands were

> affected, and many died. Locally, Joffe, a plant pathologist

> determined the outbreak of ATA was caused by consumption of a

toxin,

> present in the millet, which had been contaminated by F.

tricinctum.

> This was a remarkable conclusion since this was 20 years before

> aflatoxin was discovered. However, Joffe did not isolate or

identify

> the toxin involved and as a result his work remained unknown until

> about 1965 when he presented a summary of his research at a

> symposium on mycotoxins. The mycotoxin involved was later given the

> common name T-2, and classified as one of several trichothecenes.

> Fed orally to rats, it has an LD50 of 3.8mg/kg, which is lower than

> that of aflatoxin, but still toxic enough.

>

> Fusarium graminearum

>

> Corn is a stable in many countries and is used as a major

ingredient

> in preparation of food for pigs and other domestic animals. Like

> many other grains, the kernels can be infected with fungi before

and

> after harvest, and can affect the nutritional value of corn as food

> or feed.

>

> If the weather is rainy and the ears of corn are maturing in late

> summer and early fall, F. graminearum may infect only a few to a

> third of the kernels. Whatever amount of the ear is infected, all

> the kernels in that portion becomes heavily infected and decayed by

> the fungus. This fungus-infected corn is unattractive to pigs, as

> well as other animals, and they refuse to it. For this reason, this

> phenomenon has been called a refusal factor. Regardless of what the

> composition of the rest of the feed, if it contains more than 5

> percent of kernels with this refusal factor, the pigs will not eat

> it and weight loss will occur. They will starve rather than consume

> it. The infected corn contains an emetic compound produced by the

> fungus, and if this corn is consumed by pigs, they suffer prolonged

> vomiting, after which they sensibly refuse to eat more of the corn

> (who said pigs were stupid?). The toxin involved is deoxynivalenol

> (DON), also known as vomitoxin. The isolation and identification of

> this toxin has occurred only within the last 25 years.

>

> This is a serious problem if you look at it through the eyes of the

> farmer. If you are a farmer and you have 800-1000 pigs and several

> tons of feed mixed with corn, contaminated with vomitoxin, was

> delivered to the farmer's feed bin on a Friday, and it is later

> determined that the pigs will not eat it, then the farmer has a

> serious problem. What are the pigs going to eat between Friday and

> Monday?

>

> Various methods have been tried to make the vomitoxin contaminated

> corn more acceptable to pigs. Among some of the means that have

been

> tried are adding molasses to the feed to conceal whatever flavor or

> odor makes it unacceptable to the pigs, heating the feed, in hopes

> of destroying or inactivating whatever it is that is making the pig

> refuse to eat it, and composting it so that the heat will break

down

> the toxin. However, none of these treatments have made the corn

> acceptable to pigs and are impractical, anyway.

>

> The detection of infected corn or feed is also a problem. Since we

> are talking about mycotoxin here, the inability to isolate the

> causal agent, F. graminearum, is not evidence that the mycotoxin is

> absent. Long after a fungus has died off, mycotoxin secreted into

> the substrate, will still be present. The refusal of pigs to eat

> feed or corn is an indication that the refusal factor is present,

> but not necessarily conclusive. There are a number of reasons as to

> why pigs will refuse to eat. Pigs may be traumatized by being moved

> to a new pen, strange surroundings or even being offered different

> food. The only way that the toxin can be detected is to isolate,

> purify and identify it by spectrographic or other analysis.

>

> Use of Trichothecenes as a Biological Weapon

>

> Yellow Rain

>

> During the mid 1970s, when Vietnam was invading Laos, there were

> stories of " yellow rain " in areas where entire villages were

killed.

> One eye witness account of such an event was told by a Hmong

> refugee, in Thailand. While tending his poppies, outside of his

> village, he and his family witnessed the bombing of their village

by

> the Vietnamese, in MIGS, with a yellow powder that came down like

> yellow rain. Returning to the village, he found all of the animals

> and most of the people were dead. The bodies were bleeding from the

> nose and ears and their skin were blistered and yellowed. The few

> people left alive, when he arrived, were " jerking like fish when

you

> take them out of the water " . These people also eventually died. The

> witness took his family away from the village, but as they left

they

> felt shortness of breath and sick to their stomach. This story is

> similar to other stories that were heard concerning yellow rain.

>

> It was believed by the United States at that time that the Soviet

> Union was somehow involved in what occurred in the Hmong village,

> and medical teams were sent to investigate. However, because of the

> remoteness of these villages, news of such attacks normally took 4

> to 6 weeks to reach someone who could notify the medical teams. By

> the time investigators reached a village, there was no evidence as

> to what happened. It would not be until 1980 that a Defense

> Department chemist recognized the symptoms described by victims of

> the bombing as similar to trichothecene mycotoxicosis. Samples from

> victims and from vegetation in the areas were tested and some were

> found to contain trichothecenes. With this information, President

> Reagan accused the Soviet Union of violating the Geneva

> Convention and Biological Weapons Convention, which of course they

> denied. However, these accusations would continue for three more

> years.

>

> While the accusations and denials were aired, the media and

> scientific community gave a more critical examination of the yellow

> rain story. The analysis that demonstrated Trichothecenes were

being

> used was initially based on a single leaf, collected where one of

> the chemical attacks occurred. Subsequent specimens were collected

> later that also showed Trichothecenes were present, but the ratio

of

> trichothecenes differed where it was found and was entirely absent

> in some samples. In addition, little fanfare was given to the over

> one hundred samples analyzed by the United States Army, which did

> not find any indication of trichothecenes. The eye witness accounts

> also came into question. Although it was implied that many villages

> were attacked with yellow rain, all of the witnesses were from a

> single refugee camp in Thailand, and even these accounts were

> thought to be unreliable. For example in relating a story of the

> bombing, one villager had initially said that 213 villagers were

> killed, but in a later retelling, there were only thirteen people

> killed and then forty. Further erosion of the government's yellow

> rain story came about when a Yale University entomologist, whose

> expertise was in Southeast Asian bees, examined yellow rain samples

> and observed that they contained pollen from the native plants in

> the area. Based on the appearance of these samples, it was

concluded

> that they were feces of bees. In one species of bees, present in

the

> area, there is a tendency for the bees to swarm when they

defecated,

> as a cleansing ritual, which could give the appearance of yellow

> rain falling. News of such chemical attacks soon stopped and many

> civilian scientists were convinced that the entire yellow rain

> incident was a hoax that was carried out by the military to

increase

> funding for defensive chemical and biological weapons.

>

> While a plausible alternative was given as to the cause of the

> yellow rain, the eye witness accounts while questionable,

> contradicted this theory. To date, the question as to what caused

> the yellow rain has still not been satisfactorily resolved and may

> never be.

>

> Trichothecenes and the Lack of Population Increase in Europe

>

> Something very interesting concerning mycotoxins in fungi has

> recently come to light. Historical demographers, that is people

that

> study populations, their distribution, density and other such vital

> statistics, have shown that long life and good health are a recent

> phenomenon. Before 1750, in England for example, the life

expectancy

> of a member of the British peerage, that is one who has borne of

> noble birth, was only 36.7 years, a hundred years later it had

risen

> to 58.4 years. Conditions were worse, and improvement slower among

> the common folks. However, between 1750 and 1850, the population of

> Europe almost doubled.

>

> Before 1750 good health was a privilege of wealth, and not even

then

> did all the rich enjoy it. A commoner was often underweight,

> stunted, sickly and occasionally deranged. They could not even

> imagine the feeling of well being that we have today. There was a

> constant battle with death, with results generally coming out in a

> draw. There were great fluctuations in populations because of

> mortality crises. After a mortality crisis, more people in a

> community would marry and they would marry younger and would

> eventually give rise to more children; so that if things

> were " normal " , a community would tend to produce more babies than

> corpses. But then pretty soon another crisis would come, e.g.,

> disease, famine, natural disasters, etc., and the gain in

population

> would be wiped out.

>

> The way in which populations were generally explained was in

> Malthusian terms. That is populations were self regulating;

> increases and decreases in birth rates were due to the availability

> of resources, i.e. food, so if there was a lot of available food

> there would be less death and more people would live to reproduce

to

> increase the population while if there was not enough available

> food, there would be more deaths and fewer people would be around

to

> reproduce and the population would decrease. This is very sensible,

> but in recent years it has been demonstrated, statistically, that

> this is usually not the case.

>

> What has been suggested, more recently, was that it was an increase

> in fertility that was responsible for an increase in population,

and

> a decline in mortality, between 1750-1850. There have been several

> reasons that have been proposed for the increase in fertility. One

> reason that I became interested was the idea that changes in the

> food supply was responsible for the increase in fertility. In a

> recent book, by Matossian, Poisons of the Past, she puts forth

> the theory that it was the change in diet of Europe that was

> responsible for the tremendous increase in population.

>

> During the 18th century, French adult peasants ate two to three

> pounds of dark bread a day, when they could afford it. The rich and

> affluent, which was less than 5 percent of the population,

preferred

> white bread. In the Mediterranean Basin, the diet of the poor

> consisted of barley, buckwheat, wheat and after the 16th century

> also included corn. North of the Alps and Pyrenees the poor made

> their bread from rye or a mixture of rye and other grains, such as

> barley, oats and buckwheat.

>

> As you should now know cereal stables such as these come from

plants

> that are seldom free of molds, and it is Matossian's theory that it

> was the consumption of such contaminated grains that had damaged

the

> immune system of the population of Europe that had relied on grain

> as their staple and was probably largely responsible for a short

> life span. T-2 and related trichothecenes are known to compromise

an

> individual's immune system. It would be a change of diet that would

> begin to give individuals a longer life span. In addition, the

> change in diet, which included potatoes also affected the birth

> rate For example, recall that there was an increase in the Irish

> population between 1750 and 1850. The reduced fertility in European

> was believed to be due to the consumption of Rye that had been

> contaminated with Ergot of Rye, a disease of Rye. This will be

> another one of our topics on mycotoxins. The change to a diet which

> consisted almost solely of potatoes rather than grains was

> responsible for the increase in population. Matossian presented a

> number of case studies to demonstrate that this had occurred, but

> unfortunately, we don't have time to cover all of these cases.

>

>

> --------------------------------------------------------------------

-

> -----------

>

> Most of this lecture was based on the following books. If you are

> interested in reading a more detailed account of the above stories,

> you may find them in Hamilton Library.

>

> Christensen, C.M. 1975. Molds, Mushrooms, and Mycotoxins.

University

> of Minnesota Press, Minneapolis. 264 pp.

>

> Hudler, G. 1998. Magical and Mischievous Molds. Princeton

University

> Press. 248 pp.

>

> Hunter, B.T., 1989. Mycotoxins: A Significant Public Health

Problem.

> Consumer's Research 72 (6): 8-9.

>

> Kendrick, B. 1992. Mycotoxins in Food and Feed in the Fifth

Kingdom,

> 2nd ed. pp. 316-331. Mycologue Publications. Waterloo Ontario.

>

> Matossian, M.K. 1989. Poisons of the Past: Molds, Epidemics and

> History. Yale University Press, New Haven.

>

>

> --------------------------------------------------------------------

-

> -----------

>

> Mycological Terms

>

> Aflatoxins: First mycotoxins discovered, in 1960, produced by

> Aspergillus flavus.

>

> Aleukia Toxic Aleukia (ATA): Condition associated with consumption

> of trichothecenes mycotoxin, T-2, produced by Fusarium tricinctum.

> Some symptoms of condition include low white blood cell count,

> multiple subcutaneous hemorrhages and bleeding from nose and

throat.

>

> Aspergillus flavus: Species complex in which first mycotoxins,

> aflatoxins, were discovered.

>

> Aspergillus fumigatus: Species of fungi producing

> mycotoxin/antibiotic fumagillin.

>

> Fumagillin: Compound produced by Aspergillus fumigatus, an example

> of the fine line between something that is medicinal and a

> poisonous. Although classified as a mycotoxin, it is also

> effectively used as an antibiotic for amoebic parasites, in human

as

> well as honeybees. However, dosage is very important here, if too

> much is used, it can be fatal.

>

> Fusarium graminearum: Species associated with production of

> mycotoxin, vomitoxin, which causes pigs and other animals not to

> consume food when present. Pigs would initially eat food,

containing

> toxin, but after a prolonged period of vomiting, refused to consume

> more food with toxin. Refusal to eat leads to weigh loss in

animals.

>

> Fusarium tricinctum: Species producing trichothecenes associated

> with alimentary toxic aleukia (ATA). First documented in 1940s, of

> USSR.

>

> Kwashiorkor: Protein deficiency disorder of children in various

> overpopulated countries in the world.

>

> Matossian: Historian and author of Poisons of the Past.

> Believed that the population depression that occurred in Europe

> before 1750 was due to consumption of moldy grains that contained

> mycotoxins. It was believed that such mycotoxins reduced fertility

> and life span of individuals, and that it was not until a change in

> diet from grains to potato did the situation improved. Between 1750

> and 1850, population of Europe doubled as a result of change in

> diet.

>

> Mycotoxicoses: The effects of poisoning from mycotoxins.

>

> Mycotoxins: Literally poisons from fungi, Myco = fungus, toxins =

> poison.

>

> T-2: Trichothecene mycotoxin produced by Fusarium tricinctum that

is

> associated with ATA.

>

> Vomitoxin: Name given to trichothecenes that causes pigs and other

> animals to refuse food containing this mycotoxin. Pig would

> initially eat food with toxin, but after a prolonged period of

> vomiting, the pig would refuse to eat it even when hungry. It

caused

> weigh loss because of refusal to eat.

>

> Yellow Rain: Name given to yellow, powdery material said to have

> been dropped from MIGs, during attack of Hmong villages, in Laos,

by

> Vietnamese, in mid 1970s. Powdery material was said to be a

> trichothecenes that quickly killed villagers.

>

>

> --------------------------------------------------------------------

-

> -----------

>

> Questions to Think About

>

> What was the inherent difficulty of demonstrating that a metabolic

> product produced by fungi was the cause of illnesses?

>

> When an organism produces a chemical, it is usually for a reason.

> What reason can you give for fungi producing mycotoxins.

>

> Although Aspergillus flavus is known to produce aflatoxins, it is

> also utilized in the making of a number of food products, miso,

sake

> and soy sauce, to name a few. Why is it that the makers of these

> food products are not concerned about aflatoxin?

>

> Although the existence of mycotoxins was suspected before its

actual

> discovery, and there were several cases in which the fungal

> contaminated food material was known to be the source of poison,

for

> example Joffe's work in 1940. Yet, it was not until 1960, when

> research was being carried out on the Turkey-X disease that the

> existence of mycotoxin was accepted. What was different about this

> research that finally made everyone accept that it was a poison

> produced by the fungus that was causing illnesses to occur rather

> than just the consumption of the fungus infected food?

>

> Aspergillus fumigatus produces fumagillin, which can either be

> classified an antibiotic or mycotoxin. Can you explain how a single

> compound can be classified as both?

>

> What is your opinion on the " yellow rain " being used as a

biological

> weapon in Laos, during the mid 1970s?

>

> Briefly summarize the reason given by Potossian on the lack of

> population growth, in Europe, until the late 18th. Century.

>