The olfactory region of the brain was now almost half as big as the optic center used to be. This, like the finger change, was implicit in Brennan's assertions; a Protector had to be able to distinguish one protein molecule from another when they differed by only one amino acid in one place. The processing involved was tremendous.
The brain had more than tripled in size. The new material at the back of the head was mostly three big lobes of cortex, each one a bigger processing net than one of the human brain's cortex hemispheres; and the hemispheres she'd started out with had grown as well. One of these five lobes sufficed for routine activity, allowing the rest to sleep when not needed. Processing networks required something akin to a dream state from time to time, or they began giving aberrant results; a Protector must have at least one cortical lobe in dream state just about all the time. A human Protector could have two in dream state, and still be smarter than a Pak Protector going full out.
There had been nerves dealing with facial muscles and genital response, and those nerves were dead and resorbed in metamorphosis. The brain centers formerly connected to them were now sensing with, and sending commands to, new nerves in the improved fingertips. Small wonder if Protectors enjoyed making things.
The lining of the small intestine was thick, and dense with blood vessels. Intestinal tissue was being constantly converted to embryonic cells, and those were entering the bloodstream, attaching themselves to cells that were functioning improperly. Once there, a new cell wrapped completely around the target cell, took up the cell's proper function, and ate it, digesting its proteins and nucleic acids into individual amino acids and nucleotides. Most of these were released into the blood plasma. The new cells also ate any foreign material, and dead or mutated cells. Bone marrow now produced only red cells—which were some twenty percent more numerous than before, and now had wrinkly surfaces to maximize the O2/CO2 exchange rate.
The virus that was present in the small intestine showed no sign of having ever been capable of infecting a plant. It didn't do that much to the small intestine, for that matter; but the genes it added produced some really astonishing prions—multifunctional enzymes which, among other things, reshaped other proteins, of similar but not identical sequence, into the same shape as the prion. Back in biochemistry classes she'd been taught that twenty-first-century Earth had waged desperate battles in the lab to wipe out just a few types of prions that had gotten into the food supply. Seeing them at work, this was plausible.
Tree-of-life virus must have infected the plants alone, and turned their proteins into prions. Jack Brennan had developed this virus by reverse-engineering the prions and creating the thing from first principles, and must have been planning to do so from the moment he killed Phssthpok. (That part of his story she believed. The Pak Protector would have sterilized Earth if he'd even suspected humans would turn down tree-of-life.) The prions only worked right on cells that had undergone a certain number of divisions—one of them converted telomerase to a new formulation, and too much of the new stuff—a regulating enzyme—would melt you to a blob, while too little would allow your cellular metabolism to speed up until it cooked your brain. The latter had actually happened to one of the Belters who'd inspected Phssthpok's cargo.
There were more mitochondria per cell, too. There seemed little purpose in this until Peace made the connection with a genetic disease she'd read about, now absent from the species, that caused mitochondria to accumulate calcium phosphate. In a Protector, it was a storehouse of material for regenerating bone; in breeders, it sapped strength in all tissues on a cellular level by limiting the size of the ATP reserve. It must have been universal at one time—Pak breeders didn't need stamina, clear heads, or motivation: they had Protectors. Peace recalled that salicylic acid, and its salts and esters, caused mitochondria to store inorganic phosphates, and she determined to stockpile the stuff.
She had used up most of a day getting acquainted with her new condition. Time to get to work. It would be tedious; the annihilation of technological artifacts was so thorough it must have taken some earlier expedition's protectors weeks, and Truesdale and the Home Protectors had stripped out all ore deposits for their arsenals before the asteroid bombardment, sensibly enough. (The mining trees were a splendid bit of misdirection: the Brennan virus had an affinity for the bark, which was crumbly.)
She went through the hidden parts of the computer's memory and found references to inventions the UN ARM had suppressed. Some sounded useful. There were no technical details, but a general outline of principles was usually given, and that was enough.
The third day she gave in to her impatience and built an automaton that could perform simple routine tasks, like cleaning rooms or repairing scanners. For the latter task she had to include a device that distorted the force binding the instrument shells, making them pliable enough to reach through; it had been obvious that the puppeteers must have some means of softening GP hulls, as they would never have sold invulnerable warship hulls to aliens. This done, she had the idea of building automata to fabricate parts usable in a variety of items, and judged it worth the time. (Technology doesn't save labor: it invests it.) Pure elements could be had via the expedient of a conveyor belt, a disintegrator, and a tapered wind tunnel. She dedicated five days to these tasks, then one more for a device that assembled parts to order, and was able to begin work on parts for the exotic stuff. She arranged a foil shell in stasis for workshop housing—some of the mechanisms would absorb stray neutrinos otherwise—and began building various specialized components for weapons of short, middle, and long ranges. Middle range being the horizon.
When the kzinti showed up, she was pleasantly surprised (and just a bit embarrassed for them) to find that she could easily break into their ship's command codes, which raised the possibility of interrogating prisoners. She shut off the fuel feed to their fusion source, then found mechanical cutouts that prevented total shutdown of key systems, so she broke out something she'd built as a battery charger. It was faster than laying cables everywhere: it drew power out of all nearby sources, or a source it was aimed at, all without the need for broadcasting. It was just the thing to make a ship fall down.
Most of the survivors were an armored infantry group, and the ones who saw her didn't fight the way she'd expected kzinti to fight; they seemed desperate, rather than fanatical. It dawned on her that a Pak Protector must have landed on Kzin two and a half million years back, and made a really lasting impression. They would have been intelligent by then, but not civilized. Oral tradition would have distorted with every generation, but drawings would be kept up. Some of these troops blew themselves up when it was clear she'd be able to capture them; it was like they expected her to drag them, screaming, back to Hell.