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lesyeuxverts) wrote2007-03-13 11:48 pm
lesyeuxverts) wrote2007-03-13 11:48 pm
Entry tags:
Courtship and Conjugation
Title: Courtship and Conjugation
Author: lesyeuxverts00
Word Count: ~900
Rating: PG-13
Pairing: Agrobacterium/Agrobacterium
Warnings: Explicit description of the exchange of genetic material; also, a relationship between two genetically identical organisms.
Disclaimer: Not mine ... no, I'm really not responsible for this crack. The plotbunny came from![[insanejournal.com profile]](https://www.dreamwidth.org/img/external/ij-userinfo.gif)
svartalfur, the encouragement from theentwife, the research on A. tumefaciens from Steve Winan's lab, and most everything else from Jane Austen.
AN: Notes and glossary at the end - let me know if I've missed any terms that you think I should define.
It is a truth universally acknowledged that a young bacterium rich with genetic diversity must be in want of a mate. The rhizosphere was abuzz with speculation when Agri moved into the neighborhood, filling an ecological niche that had been lately left vacant. All of the bacteria vied for the chance to visit with him and considered him as the future mate of their daughters.
News travels quickly in the soil, and the Rhizo family was soon awash with chemical signals and anticipation. The eldest of the Rhizos could not be prevailed upon to meet with Agri, and so it was not until the dance at the root nodule that they had a chance to meet him.
"I hear he's very handsome," said Fredii as they swam over, "with a lustrous coat of exopolysaccharides and very strong flagella."
"He's bringing his twelve sisters and six gentlemen from the next rhizosphere over," Brady said. "Also, he told Sir Aeruginosa that he loves to dance."
"He has five thousand metabolites," their mother said. "Can you imagine that, girls?"
When they arrived at the dance, however, the girls found the rich young Agri dancing with his friend Bacti, and their hopes of making a match with him were crushed. The two gentlemen bacteria cut across the dance space with ease, swaying with Brownian motion, their flagella entwined in an intimate caress.
Pseu and Monas, the daughters of Sir Aeruginosa, soon hurried over to the Rhizos to share the latest gossip. "Do you see that man over there, dancing with Agri?" Pseu asked, quivering with alginate.
"They're old friends, they've known each other for several cell division cycles. Bacti is even richer than Agri is, and they share a conjugative plasmid," she told them.
"Isn't it romantic?" Monas sighed.
Bdello, an earnest young bacterium who was also new to the neighborhood, interrupted their conversation with an alarmone. "You can't trust Bacti," he said. "He's done terrible things in the past, robbing me of essential nutrients and that's not all. He's even infected a plant – oh, the horror of those days, the stress we all went through in the rhizosphere, the terrible chemicals that were released. It isn't a story for gentle chemoreceptors, ladies."
With a collective flounce of flagella and an unfavorable chemical gradient, the Rhizo family turned and left the dance, shunning the affectionate Agri and his suitor Bacti.
-----
"Oh, my love," Agri said. "My plasma membrane ruffles with joy at your approach, at the caress of your anionic lipopolysaccharides. Promise me that you'll be with me always, that I'll know this joy forever."
"I swear on my ribosomes, Agri, I'll never leave you. Neither drought nor antibiotic stress nor starvation will ever part us."
Agri spun with delight. "Oh yes, my love, oh yes," he said, feeling a signaling molecule penetrate him. It slid through the lipid bilayer with nary a tremor, the acyl chain stroking his membrane, the polar lactone head group giving him a delicious shiver as it bound a receptor protein.
He was incoherent with pleasure, the activated response regulator turning on the transcription of various genes. His polymerases hummed, his ribosomes whirred, and the polycistronic messenger RNA spun out like beads on a string. He was ready for his lover. "Mate with me, Bacti," he said.
They were both producing signals, the feedback loop intensifying as they swam close together. "I need you," Bacti said, and he brushed his rigid, thick pilus against Agri.
The pilus brought them together and they shuddered at the intense contact, needing more. With a groan, Agri opened himself, letting Bacti's plasmid flow into his cytoplasm. He accepted the nucleic acid, a shudder of ecstasy rushing through his cytoplasm at the additional charge. The osmotic pressure increased and he nearly burst, tightening his cell wall at the last moment.
Bacti hummed with his completion, letting the last of the plasmid slip into his lover. The two bacteria lay locked in an embrace for a moment longer, gathering their polymerases for another cycle of replication, and then Bacti retracted his pilus with a last affectionate brush along Agri's lipopolysaccharides. "Love you," he said.
"I love you too," Agri said.
-----
The Rhizo family was overcome with gratitude for Agri and Bacti when they saved their foolish youngest daughter Fredii from the wicked Bdello. She had succumbed to his charms and was in danger of losing everything when the heroic bacteria rescued her, driving Bdello away with a storm of antimicrobial compounds.
Etli, the second Rhizo daughter, had returned from a voyage to the plant nodule with great haste when she heard about her sister's plight. "Is there anything we can do to repay you?" she asked.
"If you would be so kind, Miss Rhizo," Bacti said, "do please let the rhizosphere know that neither I nor Agri are available. I wasn't flattered by Fredii's flirtations, and the chemical signals here are just too strong. I won't stand for the disapproval of the rhizosphere. I'm devoted to my Agri, and won't ever be parted with him."
"Of course," she said. "I'll let all the neighborhood know. After all, many of my dear cousins are in similar relationships and we all understand, truly we do."
Agri and Bacti thanked her before swimming away, their flagella twined together as they hurried off. Agri nearly burst with happiness, to be alone with his Bacti at last. They'd have privacy to mate again, and perhaps if they were lucky they'd reproduce and have a chance to form their own happy microcolony.
fin
-----
Glossary/microbiology in-jokes:
The exchange of conjugative plasmids (bacterial mating) was originally described in E. coli for the F plasmid. The plasmid is transferred from donor ("male") cell to the recipient ("female") cell in a process called conjugation that involves a sex pilus. Any cell that contains the F plasmid will be able to produce the pilus, and will not be recognized as a recipient cell by other donors.
In a variation on this theme, the soil bacterium Agrobacterium tumefaciens has a conjugative plasmid that is transferred only to other bacteria that already have a copy of the plasmid ... prompting microbiologists to joke about it being the "gay bacteria."
Although this particular conjugative plasmid has been characterized in Agrobacterium tumefaciens, there are homologous plasmids in many of the rhizobial species – it hasn't been directly shown that they are transferred in the same way, but it may be the case ... hence, Etli's comment about understanding Agri and Bacti's relationship.
The names and phylogenetic relationships:
Agri and Bacti: Agrobacterium tumefaciens, a Rhizobium species. A. tumefaciens is a plant pathogen (causes crown gall disease).
The Rhizos - Rhizobium etli, Bradyrhizobium japonicum, and Rhizobium fredii are all species of Rhizobium that can enter into a symbiotic relationship with specific plants, forming root nodules and fixing atmospheric nitrogen.
Sir Aeruginosa and his daughters Pseu and Monas - Pseudomonas aeruginosa, the ubiquitous soil bacteria and opportunistic pathogen
Bdello - Bdellovibrio, a pathogen which preys on other bacteria
Alphabetically:
alarmone – molecule produced by bacteria under stress conditions that causes metabolic changes
alginate – an exopolysaccharide produced by P. aeruginosa
chemoreceptor – a protein or protein complex that detects chemical signals in the environment
exopolysaccharides – sugar polymers produced by many bacteria, they serve a variety of purposes.
flagella – bacterial organ for swimming motility
lipopolysaccharide – composed of lipid and polysaccharide, as the name suggests, usually negatively charged. The lipopolysaccharide is on the outer membrane and exposed to the surface, where it can interact with the environment.
microcolony – a microscopic colony of bacteria
plasma membrane – usually a phosopholipid bilayer that separates the cell from the environment. Gram-negative bacteria (all of the bacteria described in this story) have two membranes, an inner membrane that is a typical phospholipid bilayer and an outer membrane that contains the lipopolysaccharide
pilus – a protein complex protruding from the cell, shorter and more rigid than a flagella, involved in conjugation
polycistronic messenger RNA – a messenger RNA that encodes several proteins, common in prokaryotes. Viewed with electron microscopy, the polycistronic messenger RNA can appear as "beads on a string" - RNA with a series of attached ribosomes
polymerase – makes a copy of the nucleic acid from a template, here either RNA or DNA from a DNA template.
rhizosphere – the soil surrounding plant roots, usually differing from the rest of the soil with specific microbiological and chemical attributes.
ribosomes – synthesize proteins from messenger RNA
response regulator – when bound to the signaling molecule, activates the expression of specific genes. It also activates the expression of the protein that produces the signaling molecule in a positive feedback loop.
signaling molecule – the signaling molecule that Agri and Bacti exchange is a quorum sensing molecule, an acyl homoserine lactone that bacteria use to communicate with one another and regulate gene expression. The acyl chain and lactone head group are parts of the signaling molecule.
Author: lesyeuxverts00
Word Count: ~900
Rating: PG-13
Pairing: Agrobacterium/Agrobacterium
Warnings: Explicit description of the exchange of genetic material; also, a relationship between two genetically identical organisms.
Disclaimer: Not mine ... no, I'm really not responsible for this crack. The plotbunny came from
svartalfur, the encouragement from theentwife, the research on A. tumefaciens from Steve Winan's lab, and most everything else from Jane Austen.AN: Notes and glossary at the end - let me know if I've missed any terms that you think I should define.
It is a truth universally acknowledged that a young bacterium rich with genetic diversity must be in want of a mate. The rhizosphere was abuzz with speculation when Agri moved into the neighborhood, filling an ecological niche that had been lately left vacant. All of the bacteria vied for the chance to visit with him and considered him as the future mate of their daughters.
News travels quickly in the soil, and the Rhizo family was soon awash with chemical signals and anticipation. The eldest of the Rhizos could not be prevailed upon to meet with Agri, and so it was not until the dance at the root nodule that they had a chance to meet him.
"I hear he's very handsome," said Fredii as they swam over, "with a lustrous coat of exopolysaccharides and very strong flagella."
"He's bringing his twelve sisters and six gentlemen from the next rhizosphere over," Brady said. "Also, he told Sir Aeruginosa that he loves to dance."
"He has five thousand metabolites," their mother said. "Can you imagine that, girls?"
When they arrived at the dance, however, the girls found the rich young Agri dancing with his friend Bacti, and their hopes of making a match with him were crushed. The two gentlemen bacteria cut across the dance space with ease, swaying with Brownian motion, their flagella entwined in an intimate caress.
Pseu and Monas, the daughters of Sir Aeruginosa, soon hurried over to the Rhizos to share the latest gossip. "Do you see that man over there, dancing with Agri?" Pseu asked, quivering with alginate.
"They're old friends, they've known each other for several cell division cycles. Bacti is even richer than Agri is, and they share a conjugative plasmid," she told them.
"Isn't it romantic?" Monas sighed.
Bdello, an earnest young bacterium who was also new to the neighborhood, interrupted their conversation with an alarmone. "You can't trust Bacti," he said. "He's done terrible things in the past, robbing me of essential nutrients and that's not all. He's even infected a plant – oh, the horror of those days, the stress we all went through in the rhizosphere, the terrible chemicals that were released. It isn't a story for gentle chemoreceptors, ladies."
With a collective flounce of flagella and an unfavorable chemical gradient, the Rhizo family turned and left the dance, shunning the affectionate Agri and his suitor Bacti.
-----
"Oh, my love," Agri said. "My plasma membrane ruffles with joy at your approach, at the caress of your anionic lipopolysaccharides. Promise me that you'll be with me always, that I'll know this joy forever."
"I swear on my ribosomes, Agri, I'll never leave you. Neither drought nor antibiotic stress nor starvation will ever part us."
Agri spun with delight. "Oh yes, my love, oh yes," he said, feeling a signaling molecule penetrate him. It slid through the lipid bilayer with nary a tremor, the acyl chain stroking his membrane, the polar lactone head group giving him a delicious shiver as it bound a receptor protein.
He was incoherent with pleasure, the activated response regulator turning on the transcription of various genes. His polymerases hummed, his ribosomes whirred, and the polycistronic messenger RNA spun out like beads on a string. He was ready for his lover. "Mate with me, Bacti," he said.
They were both producing signals, the feedback loop intensifying as they swam close together. "I need you," Bacti said, and he brushed his rigid, thick pilus against Agri.
The pilus brought them together and they shuddered at the intense contact, needing more. With a groan, Agri opened himself, letting Bacti's plasmid flow into his cytoplasm. He accepted the nucleic acid, a shudder of ecstasy rushing through his cytoplasm at the additional charge. The osmotic pressure increased and he nearly burst, tightening his cell wall at the last moment.
Bacti hummed with his completion, letting the last of the plasmid slip into his lover. The two bacteria lay locked in an embrace for a moment longer, gathering their polymerases for another cycle of replication, and then Bacti retracted his pilus with a last affectionate brush along Agri's lipopolysaccharides. "Love you," he said.
"I love you too," Agri said.
-----
The Rhizo family was overcome with gratitude for Agri and Bacti when they saved their foolish youngest daughter Fredii from the wicked Bdello. She had succumbed to his charms and was in danger of losing everything when the heroic bacteria rescued her, driving Bdello away with a storm of antimicrobial compounds.
Etli, the second Rhizo daughter, had returned from a voyage to the plant nodule with great haste when she heard about her sister's plight. "Is there anything we can do to repay you?" she asked.
"If you would be so kind, Miss Rhizo," Bacti said, "do please let the rhizosphere know that neither I nor Agri are available. I wasn't flattered by Fredii's flirtations, and the chemical signals here are just too strong. I won't stand for the disapproval of the rhizosphere. I'm devoted to my Agri, and won't ever be parted with him."
"Of course," she said. "I'll let all the neighborhood know. After all, many of my dear cousins are in similar relationships and we all understand, truly we do."
Agri and Bacti thanked her before swimming away, their flagella twined together as they hurried off. Agri nearly burst with happiness, to be alone with his Bacti at last. They'd have privacy to mate again, and perhaps if they were lucky they'd reproduce and have a chance to form their own happy microcolony.
fin
-----
Glossary/microbiology in-jokes:
The exchange of conjugative plasmids (bacterial mating) was originally described in E. coli for the F plasmid. The plasmid is transferred from donor ("male") cell to the recipient ("female") cell in a process called conjugation that involves a sex pilus. Any cell that contains the F plasmid will be able to produce the pilus, and will not be recognized as a recipient cell by other donors.
In a variation on this theme, the soil bacterium Agrobacterium tumefaciens has a conjugative plasmid that is transferred only to other bacteria that already have a copy of the plasmid ... prompting microbiologists to joke about it being the "gay bacteria."
Although this particular conjugative plasmid has been characterized in Agrobacterium tumefaciens, there are homologous plasmids in many of the rhizobial species – it hasn't been directly shown that they are transferred in the same way, but it may be the case ... hence, Etli's comment about understanding Agri and Bacti's relationship.
The names and phylogenetic relationships:
Agri and Bacti: Agrobacterium tumefaciens, a Rhizobium species. A. tumefaciens is a plant pathogen (causes crown gall disease).
The Rhizos - Rhizobium etli, Bradyrhizobium japonicum, and Rhizobium fredii are all species of Rhizobium that can enter into a symbiotic relationship with specific plants, forming root nodules and fixing atmospheric nitrogen.
Sir Aeruginosa and his daughters Pseu and Monas - Pseudomonas aeruginosa, the ubiquitous soil bacteria and opportunistic pathogen
Bdello - Bdellovibrio, a pathogen which preys on other bacteria
Alphabetically:
alarmone – molecule produced by bacteria under stress conditions that causes metabolic changes
alginate – an exopolysaccharide produced by P. aeruginosa
chemoreceptor – a protein or protein complex that detects chemical signals in the environment
exopolysaccharides – sugar polymers produced by many bacteria, they serve a variety of purposes.
flagella – bacterial organ for swimming motility
lipopolysaccharide – composed of lipid and polysaccharide, as the name suggests, usually negatively charged. The lipopolysaccharide is on the outer membrane and exposed to the surface, where it can interact with the environment.
microcolony – a microscopic colony of bacteria
plasma membrane – usually a phosopholipid bilayer that separates the cell from the environment. Gram-negative bacteria (all of the bacteria described in this story) have two membranes, an inner membrane that is a typical phospholipid bilayer and an outer membrane that contains the lipopolysaccharide
pilus – a protein complex protruding from the cell, shorter and more rigid than a flagella, involved in conjugation
polycistronic messenger RNA – a messenger RNA that encodes several proteins, common in prokaryotes. Viewed with electron microscopy, the polycistronic messenger RNA can appear as "beads on a string" - RNA with a series of attached ribosomes
polymerase – makes a copy of the nucleic acid from a template, here either RNA or DNA from a DNA template.
rhizosphere – the soil surrounding plant roots, usually differing from the rest of the soil with specific microbiological and chemical attributes.
ribosomes – synthesize proteins from messenger RNA
response regulator – when bound to the signaling molecule, activates the expression of specific genes. It also activates the expression of the protein that produces the signaling molecule in a positive feedback loop.
signaling molecule – the signaling molecule that Agri and Bacti exchange is a quorum sensing molecule, an acyl homoserine lactone that bacteria use to communicate with one another and regulate gene expression. The acyl chain and lactone head group are parts of the signaling molecule.