biology zoology blog benno meyer rochow gall genetics

Cancer Researchers & Molecular Geneticists: this could be something for you

The incredible galls

Round and red like cherries they were, the oak-apples, a kind of plant gall, which I loved to collect as a child. But they had a biting-bitter flavour, which taught me that despite their enticing looks as far as their value as a food item was concerned, they were pretty useless. A very important lesson, indeed, for not everything that’s pretty on the outside has a valuable inside. Later I also learned that not all plant galls have to be smooth, round or red. There are some that are warty, chimney-shaped, pimple-like, white and even purple in colour and they may not even be confined to the blade of a leaf. As a young, first year student (I started my university life as someone who considered math as a major, but then decided on chemistry only to change a year later to fisheries and ultimately end up in Neurobiology) I described a gall that was formed by the actions of an aphid known as the spiral gall aphid (Pemphigus spirothecae). This “plant louse” causes the stem of a poplar tree’s leaf to undergo a helical twist combined with a bulbous swelling into which the aphid settles and starts its family. The species has recently been shown to be a “social insect”, exhibiting division of labour between individuals and altruistic behaviour traits similar to those of ants and honey bees.

For centuries some galls had practical roles (as a source of ink) or found uses in homeopathy and medical compounds, but none to the best of my knowledge served as a regular component of the human diet. The principal agents in plant gall formation are the larvae of certain beetles species, plant sap-sucking aphids, flies and solitary wasps. A few small moths, some mites and nematode worms are also on record to cause gall growths. Each gall former usually has an “agreement” with one particular species of plant. Through an as yet still poorly understood mechanism the growing embryo or larva in the plant tissue manipulates the metabolism and growth machinery of the plant, so that certain cells undergo rapid proliferation (as in cancers), creating a thick coat of multi-cellular, nutritive tissue around the insect: a tissue that is out of place and out of character for the plant; hence another similarity to a cancerous growth. The plant gall, as it continues to grow and acquire colour, becomes conspicuous to other insects and some, which originally have had nothing to do with the formation of the gall, may “decide to become tenants” so that a mature gall can become the home to a dozen or so different species of insects.

It surprises me immensely that cancer researchers and molecular geneticists or even nutrition specialists have not homed in on this wondrous interplay between an animal and a plant. If we knew how the plant makes the gall, couldn’t we program a plant to produce an edible product, a kind of seedless “fruit” that did not originate from a flower? Before our eyes, the gall-inducer manipulates the plant to “do” things it would not normally do, and the plant appears defenceless. But by complying, the plant actually confines the “pest” to one localized spot rather than allowing it to crawl unrestrictedly all over it and although the plant is “persuaded” to provide some nourishment to the gall residents, it can, in the end, rid itself of the uninvited and unwanted guests: by shedding its leaves.

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biology zoology insects pearl mussels

Pearl Mussels in Peril

Is there any help for pearl mussels?

We hear and read so much about plants and animal species being threatened by extinction, but not all species make headlines, like for instance the freshwater pearl mussel with the beautiful name Margaritifera margaritifera. Not only oysters and other marine molluscs produce pearls: the freshwater pearl mussel of the holarctic region on both sides of the Atlantic has for centuries yielded valuable wild pearls, too. But the times when these bog mussels were literally plastering the beds of fast flowing streams of areas poor in nutrients and calcium are nearly over – and that despite the fact that this animal can probably reach an age of 200 or even more years. —>—>

Oddballs of the Plant World

Strange, stranger, strangest

Higher plants (and I will probably restrict myself to those that have seeds and are therefore referred to as Spermatophytes) are supposed to have roots, a stem, leaves, flowers and seeds, right? Fungi (mushrooms, toadstools and the like) used to be considered odd plants, but for quite a while now have been given their own “kingdom”, namely that of “Fungi”. Since they are not “autotroph” like plants and with the help of sunlight can turn water and CO2 into sugars and starch, but like animals require food in the form of organic matter, they have more in common with the latter than with the former. Also the fact that fungal cell walls are made of chitin (a carbohydrate typical of, for example, insects and kin, but not plants) and some fungi possess the enzyme collagenase, contain melanin, or are able to produce light, demonstrates that they share more features with animals than plants. —>