You do it
The advantages of sexuality are diverse and often praised - only those who rely on quantity instead of quality practice renunciation. Apparently fewer species are willing than expected.
The average citizen knows little about some things in nature, but somehow enough. An example: mold. They are small individually, but in the area on the wall or brown bread they are disgusting and harmful to he alth. Where they proliferate, we all do something to drive them away. Isn't that enough as necessary information?
Mathieu Paoletti and a number of other researchers disagree. In her opinion, mold is rather a source of exciting sex-and-crime stories that are always worth talking about. And so Paoletti, a researcher at the University of Nottingham, is doing what we're all generally more reluctant to do: he breeds white horses. Of course, the long-term practical goal remains to perfect the fight against fungi - after all, infections caused by Aspergillus and its toxin-producing family can not only weaken he althy people, but also kill those who are already unhe althy.
But back to the stories, "Crime" genre: The most famous victims of Aspergillus niger (nicknamed "The Curse of the Pharaoh") were probably around 30 grave openers at the final resting place of Tut-Anch-Amun. They died of the long-term effects of aflatoxin poisoning from mushrooms that they had stirred up and inhaled in the burial chamber. The toxic mold substances damage the organs affected, which is why, depending on their medical history, those affected died of liver failure, kidney failure and various types of cancer.
And genre "sex"? There, admittedly, mold weakens. Until now, the Aspergillus fungus was considered a sex refuser per se, which only reproduces and multiplies purely asexually, but at least also effectively and quickly. So far - because now Paoletti and colleagues have a different opinion here too. Their subject, Aspergillus fumigatus, had recently made it onto the list of species whose genome was to be fully deciphered, as a frequent inhabitant of organic waste, compost heaps, damp wallpaper, and overwatered flowerpots. The entire DNA sequence of the mold species has therefore recently become available for interested eyes to examine - and Paoletti and nine scientists from three countries threw themselves into the work.
According to the conclusion of the genome analysis, Aspergillus fumigatus apparently does something in secret with its own kind that humans have never observed in mold. On the one hand, it soon became clear that the fungus possessed all the genes that enabled it to halve its chromosome set via meiosis. Amazing, because the fungus only has a slim haploid, i.e. simple, set of genes that is no longer possible to halve any further.
Comparisons of the DNA sequences of 290 Aspergillus individuals from all over the world now also reveal that a certain section always occurs in exactly two variants worldwide - a section that is known as the "mating type locus" in sexually active fungal species characterizes something like the sex of a sexual partner. In Aspergillus, too, this section of DNA seems to contain some of the protein building instructions that are essential for sexual processes between two fungal partners. These include genes for the production and recognition of sex attractants.
The scientists conclude that the fact that the molds are in principle capable of meiosis and always occur in two sexes – or, in biological terms, “mating types” – can never be a coincidence. Their scenario: Two fungi with their single set of chromosomes can fuse and – like the fungal species that have already been revealed to be sexually active – form organisms with double chromosomes. Only this form then has to halve its gene equipment in order to be able to fuse again in the next round. In short, there is an alternation between a single and a double set of genes, which serves the purpose of mixing the DNA sets of two organisms of a species. There is sex, in good German.
With all the advantages that this brings, such as the increased flexibility of a species with constantly new combinations in the gene pool under changing environmental conditions. For the laboratory voyeur fascinated by mushrooms, it was already clear that strictly sexless, self-pollinating mushrooms should be the exception rather than the rule. The question of the importance of casual sex in pathogenic varieties of fungi remains exciting - reason enough to extend the search for sex indicators to other supposedly abstinent fungal species.
