gene duplication

Eto and the Cordyceps fungus

The Aogiri tree(Chinese parasol tree) is actually  considered a horrendously destructive pest in a lot of countries.

‘’ Drought tolerant and cold hardy, this messy deciduous intruder quickly spreads, becoming so dense in just a few seasons that what from only a few feet away looks like a healthy forest is in fact a single species monosystem’’

This tree is an aggressive invader and that would be a similiraty with the Cordyceps fungus a group of parasitic fungi.

When a Cordyceps fungus attacks a host,the hyphae grows rapidly at the expense of host tissue, The conidia are generated through the cellular process of mitosis.The two new haploid cells are genetically identical to the haploid parent, and can develop into new organisms if conditions are favorable, and serve in biological dispersal. this is a form of asexual reproduction.

Eto shares parts of her kagune with other ghouls, they are hosts for her.  

The Cordyceps species are able to affect the behaviour of their insect host, it can change its victim’s behaviour. The cordyceps impels the ant to climb up a stem where it dies. The Cordyceps are also the source of cyclosporin—an immunosuppression drug helpful in human organ transplants, as it inhibits rejection, and is also effective in accelerate nerve regeneration.

Just like when Eto controls the behaviour of Kanae and also gives her hosts their regenerative abilities 

If Eto is in fact a Tree that canot bear fruit. As an hybrid she cannot reproduce. Trees that can not produce seeds are grafted, this is a technique where tissues from one plant are inserted into those of another so that the two sets of vascular tissues may join together.

One plant is selected for its roots and this is called the stock or rootstock. The other plant is selected for its steams, leafs, flowers and fruits, and is called the scion or cionThe scion contains the desired genes to be duplicated in future production by the stock/scion plant. the scion and the stock have to be compatible for this to be possible

Also Cordyceps is a genus of the Ascomycete phylum of Fungi , they have both asexual and sexual reproduction.

The sexual part of the life cycle commences when two hyphal structures mate. In the case of homothallic species, mating is enabled between hyphae of the same fungal clone.

Fusion of the paired nuclei leads to mixing of the genetic material and recombination and is followed by meiosis. This is the origin of a new individual.

The next step in evolution.

Kaneki may be the door Eto was looking for, thanks to him now the Tree is able to bear Fruit.


Where Genes Come From

Some four billion years ago, when cellular life emerged, a typical primordial microbe likely had only a small set of genes. Today, however, genes abound. We, for example, have 20,000 genes that encode proteins. Dogs have their own set, and so do starfish and fireflies and willow trees and every other species on Earth.

Somehow, in all that time, evolution produced a lot of new genes. As [Carl Zimmer] explains in his story, one way to make a new gene is to copy an old one. The two duplicates can then evolve in different directions. Duplicate each of them, and now one gene has become four. There’s plenty of evidence that gene duplication drives the origin of a lot of new genes.

But there are other ways. In his story, Carl focus’s on one example. In animals and plants and related species (known collectively as eukaryotes), protein-coding genes are nestled in vast stretches of DNA that don’t code for proteins. It takes only a modest mutation to non-coding DNA to get a cell to read some non-coding DNA and treat it like a gene. The protein the cell makes may be a complete mess, or it may be harmless. As he writes in his story, there’s a growing body of evidence that this process generates new protein-coding genes at a steady clip. In fact, so many new genes have arisen that scientists are trying to figure out why species don’t have many more genes than they do. (The answer seems to be that sometimes the new genes get accidentally deleted as DNA gets copied.)

You can read Carl Zimmer’s entire article here on the New York Times.

Our closest wormy cousins: About 70% of our genes trace their ancestry back to the acorn worm

A team from the Okinawa Institute of Science and Technology Graduate University (OIST) and its collaborators has sequenced the genomes of two species of small water creatures called acorn worms and showed that we share more genes with them than we do with many other animals, establishing them as our distant cousins.

The study found that 8,600 families of genes are shared across deuterostomes, a large animal grouping that includes a variety of organisms, ranging from acorn worms to star fishes, from frogs to dogs, to humans. This means that approximately 70% of our genes trace their ancestry back to the original deuterostome. By comparing the genomes of acorn worms to other animals, OIST scientists inferred the presence of these genes in the common ancestor of all deuterostomes, an extinct animal that lived half a billion years ago. This research shows that the pharyngeal gene cluster is unique to the deuterostomes and it could be linked to the development of the pharynx, the region that links the mouth and nose to the esophagus in humans. These findings were published in Nature, summarizing an international collaboration between OIST researchers and teams from the US, UK, Japan, Taiwan and Canada.

Around 550 million years ago, a great variety of animals burst onto the world in an event known as the Cambrian explosion. This evolutionary radiation revealed several new animal body plans, and changed life on Earth forever, as complex animals with specialized guts and behavioural features emerged. Thanks to the genome sequencing of multiple contemporary animals of the deuterostome group, we can go back in time to unveil aspects of the long-lost ancestor of this diverse group of animals.

Acorn worms are marine creatures that live on the ocean floor and feed by filtering a steady flow of sea water through slits in the region of their gut between mouth and esophagus. These slits are distantly related to the gills of fish, and represent a critical innovation in evolution not shared with animals like flies or earthworms. Since acorn worms occupy such a critical evolutionary position relative to humans the researchers sequenced two distantly related acorn worm species, Ptychodera flava, collected in Hawaii, and Saccoglossus kowalevskii, from the Atlantic Ocean. “Their genomes are necessary to fill the gap in our understanding of the genes shared by the common ancestor of all deuterostomes,” explains Dr Oleg Simakov, lead author of this study.

Indeed, beyond sequencing these two organisms, the team was also interested in identifying ancient gene families that were already present in the deuterostome ancestor. The team compared the genomes of the two acorn worms with the genomes of 32 diverse animals and found that about 8,600 families of genes are homologous, that is, evolutionarily-related, across all deuterostomes and so are confidently inferred to have been present also in the genome of their deuterostome ancestor. Human arms, birds’ wings, cats’ paws and the whales’ flippers are classical examples of homology, because they all derive from the limbs of a common ancestor. As with anatomical structures, genes homology is defined in terms of shared ancestry. Because of later gene duplications and other processes, these 8,600 homologous genes correspond to at least 14,000 genes, or approximately 70%, of the current human genome.

The study also identified clusters of genes that are close together in acorn worm genomes and in the genomes of humans and other vertebrates. The ancient proximity of these gene clusters, preserved over half a billion years, suggests that the genes may function as a unit. One gene cluster connected with the development of the pharynx in vertebrates and acorn worms is particularly interesting. It is shared by all deuterostomes, but not present in non-deuterostome animals such as insects, octopuses, earthworms and flatworms. The pharynx of acorn worms and other animals functions to filter food and to guide it to the digestive system. In humans, this cluster is active in the formation of the thyroid glands and the pharynx. Scientists suggest there is a connection between the function of the modern thyroid and the filter feeding mechanism of acorn worms. This pharyngeal gene cluster contains six genes ordered in a common pattern in all deuterostomes and includes the genes for four proteins that are critical transcriptional regulators that control activation of numerous other genes. Genes ordered in the same way and located next to each other in the chromosomal DNA are linked and transferred together from one generation to the next. Interestingly, not only the DNA that codes for these transcription factor genes is shared among the deuterostomes, but also some of the DNA pieces that are used as binding sites for the transcription factors are conserved among these animals.

“Our analysis of the acorn worm genomes provides a glimpse into our Cambrian ancestors’ complexity and supplies support for the ancient link between the pharyngeal development and the filter feeding life style that ultimately contributed to our evolution,” explains Dr Simakov.

Recently, the OIST team also sequenced the genomes of the octopus and the coral Porites australiensis.

Image: This is a juvenile of Saccoglossus kowalevskii with one of the transcription factors expressed in the pharyngeal region (highlighted in blue).

Credit: Andrew Gillis