Insect hormones

Insect hormones

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Juvenile hormone

The juvenile hormone (neotenin) of the insects is formed by the so-called corporaallata, a pair of glands on the sides of the nerve throat of the insects, and controls the molting processes (metamorphosis of the insects) in interaction with the molting hormone ecdysone. The juvenile hormone is an antagonist of ecdysone, as it allows larval moulting, but inhibits the transition to the pupa. In the late larval stage, more ecdysone and less juvenile hormone are produced, which leads to pupae formation. In the finished insect, the juvenile hormone stimulates egg maturation (gonadotropic hormone effect).

A number of similar structural compounds with juvenile hormone effects are now known, which are summarized under the term juvenoids.Examples of this are Farnesol or juvabion, which smells of lily of the valley, also called paper factor, as it occurs in American paper made from the juvabion-rich balsam fir. In vitro this paper triggers excessive insect skinning (e.g. when breeding fire bugs). Some of these compounds are also distinguished by a specific inhibitory effect on the biosynthesis of juvenile hormones; these substances are called anti-juvenile hormones or precocenes. They are produced by plants for self-protection. Preconene are the role models for new pesticides and insecticides (example: the Juvenoid Pro-Drone).

Hormones and the Endocrine System - Textbook of Endocrinology

Authors: Small, Bernhard, Rossmanith, Winfried G.

  • The only book in German from a biological perspective
  • Biochemical and molecular biological mechanisms of hormone biosynthesis
  • Endocrinological basics based on current research
  • All images now in color

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  • ISBN 978-3-642-37092-2
  • Digitally watermarked, DRM-free
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Basics and new developments

The technical advances and new possibilities of molecular biology - genome analysis, expression analysis, confocal laser microscopy, proteomics - make the physiology of vertebrates, as well as that of non-vertebrates, appear in a new light.

This development is taken into account when presenting the endocrinology of humans and animals: The emphasis is on hormone biochemistry, hormone physiology, hormone receptors, endocrine organs and control loops and the regulation of endocrine rhythms.

The consideration of the endocrine system ranges from its origins in invertebrates, its evolution, the interactions with the nervous or immune system to metabolic disorders in human genetic defects.

In the 3rd edition, all images are now in color. The text has been completely updated, further hormone profiles have been added and the section on steroidogenic enzymes has been completely revised.

Everything understandable and compact in one book!

Bernhard Kleine is a trained chemist. He later turned to endocrinology and worked as a scientist in Winfried Rossmanith's laboratory at the Universities of Ulm and Karlsruhe. He is currently working in clinical research.

Winfried Rossmanith is a doctor. He was laboratory manager at the University of Ulm. He is currently chief physician in the gynecology and obstetrics department at the Diakonissenkrankenhaus Karlsruhe-Rüppurr.

"The book‘ Hormone und Hormonsystem ’by Bernhard Kleine and Winfried Rossmanith offers an excellent and well-founded overview at a scientific level ..." (in: ECHO Gesund & amp Leben, 2008, Vol. 5, September, p. 12)

Chemistry of pesticides and pesticides

Editor: Wegler, Richard (ed.)

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  • ISBN 978-3-7091-4184-7
  • Digitally watermarked, DRM-free
  • Available formats: PDF
  • eBooks can be used on all end devices
  • Instant eBook download after purchase
  • ISBN 978-3-7091-2028-6
  • Free shipping for individual customers worldwide
  • Institutional customers please contact their account manager
  • Usually ships in 3-5 business days if in stock

Chemical pest control is a relatively young science. It has developed rapidly and its importance is still growing. Initially, their aim was solely to control insect pests in crop production. Today, keeping down or preventing plant diseases caused by fungi is just as much a part of chemical pest management as is the destruction of unwanted plants. Insecticides, especially acaricides, are increasingly used in hygiene, in stored product protection and in veterinary medicine, here for. B. to control ticks. It is worth remembering the use of DDT to combat malaria mosquitoes, for which the Nobel Prize was awarded. Plant protection is expanding in many directions. Some more recent uses of chemical compounds no longer fall under the original definition of the term "crop protection". Plant growth inhibitors, for example, are often closely related to herbicides, and this shifts the boundary to the hormones of plant growth. Some naturally occurring growth substances are dealt with in more detail in this work. The focus of recent developments are substances that influence flowering, prevent fruit dropping, increase frost resistance or are intended to be used in other ways for the benefit of cultivated plants. The situation is similar in the field of insecticides. Here, in addition to the classic insecticides, attractants, juvenile hormones and other substances, such as B. chemosterilants, which, however, have only found little use to date. Only the most advanced sexual attractants in insects in terms of their chemical constitution are dealt with in Volume 1 of this book.

They fly, hum and crawl: mosquitoes, bees and ants are everywhere in nature. Why are mosquitoes so fast? How do bees make honey? And how does a caterpillar actually become a butterfly? Here you can read, hear and watch exciting things about insects. Have fun!

Honey tastes sweet and is delicious. Bees fly from flower to flower. But how do bees turn nectar into sweet honey?

Do you know how butterflies are born? A butterfly is first and foremost a caterpillar. What happens then?

Have you ever seen a beehive? A lot of bees live in the hive. What are they doing there?

Have you ever tried to catch a fly? You can't catch flies by hand. Why?

People eat meat. All around the world. In many countries, however, people also eat insects. It's good. Why?

Do you know that? You are lying in bed. "Bssssssssss" Suddenly you hear the hum of a mosquito! Why is the mosquito buzzing?

Mosquitoes can bite. That's why people don't like mosquitos. Why do mosquito bites itch?

Have you looked at all of the insect related content? Here you can test your knowledge.

Sex hormones

Sex hormones (sex hormones): Sex hormones are in the broader sense all hormones that the development and function of the Gonads as well as the Genital organs determine and control, in the narrower sense the Gonadal hormones. They are also responsible for the development of the secondary sexual characteristics and thus z. B. in humans necessary for growth and the sexual development to girls and women or to boys and men. In addition, they control all processes within the framework of the Reproduction, d. H. the formation of Germ cells, pregnancy, birth and Breastfeeding. In principle, sex hormones occur in all vertebrates and also in some invertebrates (higher crustaceans, some insects).

The most important sex hormones in humans are predominant in the male sex Androgens (testosterone and Dihydrotestosterone), which predominate in the female sex Estrogens (Estrone, Estradiol and Estriol) and the Luteal hormoneswho prepare and maintain pregnancy (progesterone and the placenta hormone HCG). Androgens and estrogens are already in both sexes in the embryonic period and then again from the puberty Formed in the testes and ovaries, and to a lesser extent in the adrenal cortex. All of the sex hormones mentioned (except HCG) are chemically related to one another Steroid hormones. Their biosynthesis begins with the cleavage of the side chains of the Cholesterol and with the formation of pregnenolone, which is dehydrated to progesterone, the parent substance of steroid hormones. The individual steroid hormones differ from one another through different side chains and double bonds. The sex hormones in the broader sense also include those Gonadotropins, because they stimulate the gonads to form and mature the germ cells and to produce hormones.

Juvenile hormones

Juvenile hormones, Abbr. JH, a group of glandular insect hormones. J. are created in pairs Corpora allata and promote the differentiation of the larva, but inhibit that of the adults. J. are considered to be analogues of the growth hormones (somatotropin) of vertebrates.

The natural J. are sesquiterpenes. Already that from larvae of the mealkid Tenebrio molitor isolated Farnesol has juvenile hormone activity. Derivatives of farnesol & # 228uremethylester with juvenile hormone activity could be obtained from the butterflies Hyalophora cecropia (as main component C17-JH or JH-I, next to it C18-JH or JH-II) and Manduca sexta (C.16-JH). Numerous compounds isolated from plants or obtained synthetically have juvenile hormone activity, e.g. B. the sesquiterpene Juvabion. Studies on structure-activity relationships aim to develop insecticides with high selectivity. However, insects only react to exogenous J during a relatively short development phase. Larvae and adults are not impaired in development and activity.

You might also be interested in: Spektrum der Wissenschaft 7/2021

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Video: Tied up hormones: A simple experiment to observe insect puberty (May 2022).