Parasite Eve Sephirotto Part 12

Was this what they called arrhythmia? She shivered at the thought. Symbiosis with Mitochondria. Her body had somehow reacted to that strange lecture tide.

Her logical self told her something was wrong, yet she was strangely captivated by the prospect of hearing the lecture. She might be at the greenhouse while the talks on Chinese medicine and genetic healing were underway, but the final presentation she didn't dare to miss.

At last, the time came.

It was at this point that her friend needed to leave. She had a part-time job as a private tutor and had a five o'clock appointment to make. But Kiyomi would not miss this lecture.

A screen was being lowered behind the podium and next to it was a sign with the lecture topic written in large letters. Although they spelled out the same words that had affected her so deeply earlier, Kiyomi had no reaction to seeing them now. This did not, of course, change the fact that they had affected her. She wanted so much to understand her reaction and had a feeling that the answer somehow resided in this lecture.

Professor Ishihara, after explaining common parasites such as round worms, began to explain exactly what symbiosis was, using intestinal microbes as an example.

"Just like parasites, microbes thrive in our intestines, living off the nourishment we provide to them as hosts. But they also help us utilize vitamin and provide many other valuable functions unknown to many of us. This relationship by which two distinct life forms not only coexist, but also profit from their mutual bond, is called 'symbiosis.' These exemplary microbes are therefore not just parasites, so to speak, but are indeed necessary components of our biology. Judging from this, one might wonder if our symbiosis is restricted only to such microbes. Of course, that is not the case. Which brings us now to the subject of today's lecture: namely mitochondria. I am sure you've all at least encountered the word in junior high, but we have come to learn that mitochondria, too, are parasites. They are not insects, so it may seem a bit strange to call them 'parasites.' However, they are the same in that they exist in all human beings by means of a symbiotic relationship. And from research conducted on mitochondria, we have discovered many interesting things about them.

In my lecture, I will be utilizing what scientists have concluded through research to explain this symbiosis."

At this point, Professor Ishihara took a breath and gave a signal to the slide a.s.sistant.

The slide projector fan began to spin and the auditorium lights were turned off. Kiyomi looked behind her to see who had pressed the switch, but could see nothing, her eyes still adjusting to the darkness.

At that moment, a familiar face entered the corner of her vision.

It belonged to a young man sitting three rows behind her. She focused on him, straining to get a better look, but could not quite identify him in such a dark room. He seemed to notice her as well. Kiyomi felt a little embarra.s.sed and turned quickly back around.

A large diagram of a cell shone on the screen.

"This is a simple drawing of a human cell," Professor Ishihara explained. Using a laser pointer, he continued. "This area in the very center is the nucleus. It is where chromosomes are contained and is filled with all kinds of genetic information. And this oval-shaped area here represents a mitochondrion. It has both an outer and an inner membrane. The inner membrane is folded like so. Now, this diagram is basically the same one you would remember from your textbooks, and, as such, is probably familiar to most of you as shown here, but this does not mean they have this shape in reality. Their structure is actually quite different than what you might think. Next slide, please."

As soon as the image changed, faint murmurs of surprise rose from the audience.

"This is mitochondria's true form."

The screen's black background now framed a large picture of a cell. Inside them were what appeared to be countless green-colored threads. All of them lined diagonally upward, they seemed ready to wave forth. There was a gaping black hole in the center where the nucleus would have been. Kiyomi figured that mitochondria had been somehow stained, then photographed through a microscope to obtain this image. Each cell was crowded with hundreds, even thousands of them, beautiful like folds of velvet. Kiyomi's preconceptions about them were totally wiped away by the splendor before her eyes.

THUMP.

Her heart again.

THUMP.

This was it. Kiyomi realized it now. This was what her heart had reacted to. Her heart thrilled to mitochondria.

But why?

Kiyomi's eyes were riveted to the screen, her breath short. She stared intently at the large image before her, forgetting everything else around her. A few more pictures of stained mitochondria were shown. Some green, some blue, they swelled beyond the screen, twisting, dissolving, breaking away, changing into variant forms. She was fascinated by their structure.

Their wriggling, winding forms resembled intestinal bacteria, and she understood why the professor was comparing them to parasites.

He said there was DNA in mitochondria, that this DNA differed from DNA in the nucleus, and pointed out that mitochondria were proven to be the descendants of what were once parasitic bacteria. Ishihara also explained in detail that long ago, back when we were still delicate single-celled organisms, mitochondria invaded us, and have since thrived in symbiosis.

"At this point I'd like to talk a little about the history of cell development. Life is first thought to have appeared on this planet around 3.8 billion years ago. The first life forms were simple, pliant membranes containing DNA that dwelled near underwater volcanoes on the ocean floor, receiving nourishment in the form of hydrogen sulfide. At this time there was still almost no oxygen in the earth's atmosphere. However, 2.S billion years ago, these first life forms evolved into so-called cyan.o.bacteria, a rudimentary form of chloroplasts. They created sugars from photosynthesis and were the first organisms to, in essence, 'breathe'

oxygen. Cyan.o.bacteria multiplied at an extraordinary rate and spread throughout all the world's oceans. Because of this, oxygen levels rose both in the water and the air. But the old type of bacteria which lived off of sulfuric gases began to suffer. Unlike us, they were actually threatened by the growing presence of oxygen in the sea. The world had become the domain of cyan.o.bacteria, leaving their less evolved counterparts no other choice but to limit their quiet existence to their beloved sulfur-rich areas. It was at this point that aerobic bacteria came into the picture. As I said before, the ocean was teeming with oxygen created by cyan.o.bacteria. What aerobic bacteria did was find a way to make use of this oxygen; they became the early ancestors of mitochondria as we know them today. By utilizing the oxygen around them, aerobic bacteria were able to produce energy far beyond the capacity of normal bacteria. The purpose of that energy? Mobility. These bacteria were the first to actually swim around in the sea. And then, 1.5 million years later, a most amazing event occurred when aerobic bacteria entered the bodies of our distant ancestral life forms, who were barely surviving near volcanoes. It is possible they originally wanted to consume us, but chose instead to make their home inside of us. From that moment on, our relationship with mitochondria began."

A photograph of a single mitochondrion appeared, this one taken through an electron microscope. Situated in the middle of the screen, it was constricted in its center, about to divide. There was a small black ma.s.s inside of it which appeared to be pulling into two halves as well. Ishihara pointed this out as DNA. Mitochondrial division and multiplication happened inside the cell. The DNA was distributed among the new mitochondria. In all this, mitochondria seemed no different from, precisely, bacteria. Kiyomi thought to herself, Mitochondria are alive and they're multiplying inside of my body right now.

"Now what would you say if I told you it is because of mitochondria that we are all here today? As I said before, our earliest ancestors lived in a symbiotic relationship with mitochondria and were able to produce vast amounts of energy. They became aerobic, which in turn gave them the advantage of volition. From this they were able to take sustenance by their own means, instead of having literally to wait for it to float by. Using their own energy, they could go looking for it themselves. Now here, our ancestors acquired a new level of intelligence, namely the capacity to capture prey by any and all means necessary. They figured out how to most efficiently obtain their food. Nerve connections responsible for conceptualization and instinct began to develop, and, before long, they acquired a rather advanced way of thinking.

"We must not forget that, around the same time, mitochondria were not the only living matter to be incorporated into cellular life forms, but that some cells also combined with cyan.o.bacteria. And what happened to them, you might ask? They became self-sustaining organisms that required only sunlight for survival, without needing to go through all the trouble of searching for food. All they had to do was to maximize their surface area to catch as much sunlight as possible. I am sure you have figured out by now that these became plants. Though this explanation may be a bit diluted, now you know the basic difference between plants and animals. We can say with relative surety that our ability to move and think as we do is solely the result of our symbiosis with mitochondria."

The professor then began explaining the evolution of all living things as he pointed to a map outlining just that. At the base of the diagram was a thick trunk labeled "Our Ancestral Life Forms" which joined up with another trunk labeled "Mitochondria." From there, they separated into three paths: "Plants,""Animals," and "Fungi." Halfway up, the "Plants" branch merged into one line with "Chloroplasts," itself extending from the "Cyan.o.bacteria" trunk.

Kiyomi thought the "Mitochondria" trunk looked the most robust in the diagram.

The image on the screen returned to the previous photograph of mitochondria, and Ishihara continued.

"However, as they are now, mitochondria do not have the ability to multiply at will. To this very day, we have no idea exactly how mitochondria divide. What we have concluded, through extensive research, is that they are somehow controlled by genes in the nucleus.

When mitochondria first parasitized our cellular ancestors, they must have had an inherent genetic code which told them to propagate. But soon, mitochondria inserted this code into the nuclear genes of their hosts. And so now mitochondria have only a fraction of their original genetic code left. The processes by which mitochondria divide, as well as the creation of the proteins that comprise them, all begin with the nucleus. Mitochondria therefore put their all into producing energy. From their point of view, they have it pretty easy, considering that the nucleus does all the hard work. The sugars and fats needed to make energy are provided by the host cell. Things aren't bad for the host cell either because, supplied the materials, mitochondria create high- quality energy that the host could never generate on its own. In short, mitochondria have sustained an excellent symbiotic relationship with their hosts' cells since long ago, much in the same way that we do with intestinal microbes."

At this point, Ishihara paused to take a sip of water.

Kiyomi's heart was beating so fast, it was about to jump out of her chest. She had been too enraptured to notice that she was panting like a dog, her mouth hanging wide open. She became aware of herself when the professor stopped. She was surprised at her behavior and swallowed back her saliva with a gulp. Her heart pounded away like there was no tomorrow.

Having no other way out, her breath escaped audibly from her nose in a steady rhythm.

Kiyomi was ashamed. She covered her face with her hands, trying to quiet herself as much as she could. She shut her eyes and took a deep breath.

She was confused. Why did she have such an interest in all of this? Why was she so enchanted by it? These were questions for which she had no answers. Kiyomi's forehead was dotted with sweat, as were her chest and inner thighs. Her dress clung to her skin. She wiped her forehead with the back of her hand, where the sticky sensation remained.

Kiyomi opened her eyes, removed a handkerchief from her pocket, and dabbed her neck and forehead. When she looked back to the screen, Ishihara was discussing mitochondrial DNA, explaining how it brought about abnormalities a.s.sociated with the aging process. This had to do with something called active oxygen. The genetic mutations in mitochondria, he explained, were responsible for many diseases. He then moved on to the inheritance of mitochondrial genes by our descendants.

"Mitochondrial genes are interesting in that they are pa.s.sed along by the mother. At the time of conception, mitochondria in the sperm enter into the egg as well, but in most cases this paternal DNA does not multiply in a fertilized egg. Because only maternal DNA reproduces, the mitochondria of any given child are nearly identical to that of its mother. As a result, the genes are ultimately pa.s.sed down matrilineally. Even so, diseases caused by mitochondrial genes are not all inherited from the mother's side. This is a mystery not even current research has been able to clarify. We have only recently come to know that the genes are not pa.s.sed on entirely maternally. This is a rather complicated issue, so let us move on."

The rate of pictures decreased, changing to brightly colored graphs and various other diagrams. These images looked to have been rendered by computer, and did not excite Kiyomi as much as the microscope photography. The professor continued talking about mitochondrial genes for five minutes. In the meantime, Kiyomi's heartbeat slowed down from its violent pounding to a more subdued pace before eventually returning to normal.

She breathed a sigh of relief and sat upright, trying her best to concentrate on Ishihara's lecture as he moved on to the next subtopic.

"...We have all experienced stress, whether with the people we encounter in school, at home, or in the workplace. Ours has been called the most stressful age in the history of civilization, but I believe stress is simply inevitable, once we have the very act of sharing our lives with those around us. This is very much similar to the relationship between mitochondria and their host cells. When two different ent.i.ties live in a sealed environment, stress is created. In fact, as stress is exerted upon the cells, so-called 'stress proteins' are activated within them. These proteins allow the symbiosis between mitochondria and the nucleus run smoothly."

Ishihara proceeded to explain, with the use of simple visuals, that there were various types of stress proteins within cells, that one of their jobs was to move enzymes into mitochondria, and that when stress proteins died off, this resulted in mitochondrial mutations.

Kiyomi's heart was now perfectly at ease. She looked at her hands, only to find they were knotted tightly, the only indication of the agitation she'd experienced. She opened and closed them a few times to loosen them up and smiled to herself.

Just then, the screen changed yet again, and a large bar graph appeared. Ishihara explained these were the results of their lab experiment. They had examined the degree to which enzymes were still transferred into mitochondria when stress proteins were systematically affected. The horizontal axis named the various stress proteins, from which extended bars of varying heights.

"From this we can see that when some of the stress proteins decay, mitochondria become unable to produce enzymes sufficiently. This lack of mitochondrial function appears to be linked to many diseases."

Kiyomi was staring at the screen, following the bright red dot of Ishihara's laser pointer. After he had finished and told the a.s.sistant to move on to the next side, Kiyomi happened to notice something small written in Roman alphabets in the bottom right hand corner.

Her chest popped: WHUPP!

It came so abruptly that she let out a small cry and pitched herself forward. The slide projector clicked again and another bar graph appeared on the screen. Kiyomi ran her eyes frantically from corner to corner and found the same letters written there. Again, her heart erupted. Professor Ishihara went on, but Kiyomi could no longer hear what he was saying.

Again, the click of the projector. Again, the screen changed to another bar graph. Surely enough, the same letters on the bottom right hand corner. Three times, this intense jolt swept through her. Her body lurched audibly off her seat. She felt everyone's eyes on her, but could make out none of them in her daze. Her heart was going to explode. Kiyomi clutched her chest in a desperate attempt to calm herself. She opened her mouth and tried to speak, but only a painful wheeze escaped. Her breaths grew shorter by the moment. Her face was on fire, her heart was thundering. Somewhere in the jumble of her mind, she tried frantically to rationalize what was happening to her. The fine-printed lettering on the screen. Kiyomi had not even read it all. In a brief moment of lucidity, she strained to remember what it said.

Everything was turning foggy. Someone ran up to her. She remembered now. The words floated into her mind's eye as clearly as the pulse throbbing inside her brain: Nagashima, T. et al, J. Biol. Chem., 266, 3266, 1991.

There was something familiar there, something in that name. T. Thump. To- shi-a-ki.

Yes, that was it. Thump. TOSHIAKI NAGASHIMA. Thump. She had heard that name before. She knew him from somewhere. Of course, she thought, he's the one I met when I first came to college... Thump, THUMP, THUMP.

"Are you okay?"

A voice from afar. Someone was trying to lift her. Kiyomi saw the person's face just before dizziness overwhelmed her. Ah, it's him...

At the same time, she heard a different voice from deep inside her heart. .

A ma.s.sive convulsion racked her entire body. She buried her face in the stranger's arm, entrusting her shivering body to him. Kiyomi lost consciousness before she could ask: Who...

12.

Mariko had been up and about for a week now. Her body was weary from sleeping so much and her legs were a bit wobbly. Still, it was better than having to endure being bedridden any longer.

From her bed, she had seen only white walls and the machinery that surrounded her, but now she could walk over to the windows and gaze out into the courtyard. Leaves and branches were vibrant with lush green. She looked upon them intently, almost breaking a sweat imagining the heat that awaited her outside.

She had only recently been given more freedom in where she could go. Whereas before she had to remain in her room, she could now wander through the ward. And starting tomorrow, she would be able to go to the hospital store, and even take showers. Doctor Yoshizumi and the nurses were all exceedingly glad that her recovery was going so smoothly, but she was indifferent to what she thought to be a false play of emotions.

Everyone was trying so desperately to understand what she was going through. Being constantly surrounded by so much anxiety made her even more depressed.

Her father came to visit her at night.

He was in his usual suit and tie. Isn't he hot in those clothes? she wondered. They probably had good air-conditioning at work. With a feeble smile, he raised a hand to her in greeting.

"How are you feeling?"

Always that line. Always asking something he could tell just by a single look. Mariko sighed.

"Can I get you anything? I can get you a book or something if you want."

She knew he was forcing his smile. She was getting annoyed.

"Can I have some money then?"

"What did you say?"

Her father was somewhat taken aback by her sudden request, as it was the most substantial thing she had said to him in weeks.

"Money. They said I can go to the hospital store tomorrow. I'll just buy something myself."

Her father grew quiet and, for a long while, neither said anything.

At last, a humming sound broke the silence, a car in the distance or noise from the ventilation. When it ended, Anzai sighed.

"Mariko," he said. "Why are you being so stubborn? Tell me. Please?"

Silence.

"You were so happy the first time, weren't you? I thought you were glad to be out of the hospital and back in school. Why are you so unhappy this time? Do you just hate transplants?

Did you like dialysis better? What is it? Say something."

Silence.

"Mariko..."

She wondered how much longer she could keep her mouth shut. Anzai was at a loss for words and gave up. They heard the hum again.

Mariko simply did not understand anymore. Why had her father wanted to give her a kidney so badly?

"...Dad?"

Her father looked up.

"Dad, did you really want to give me your kidney?"

"What are you saying?"

He was clearly upset, but she could not take it back now.

She glared at him. It was her father this time who averted his eyes.

"You really didn't mind doing that? Weren't you just annoyed that I was sick? If mom were still alive, wouldn't you have wanted her to give up her kidney instead? On top of that, it was my fault it f-"

"Stop it!"

The sound of a slap shot through the air.

Slowly, but surely, her cheek began to swell with pain. For a good while, Mariko could not process what had happened.

When she looked at her father, he was shaking, looking at the floor. Hidden as it was in shadow, she could not see his face very well, but he seemed to be choking down some harsh words.

After some time, he left, and Mariko stared for a long time up at the dark ceiling.