Interest in Porphyra mariculture in Alaska and a proscription against importing non-indigenous species or stock prompted us to investigate conditions that stimulate release of conchospores in local species of interest. Many of these species had been investigated previously using strains from Washington State. We observed at least one significant difference in release conditions in Alaskan strains of Porphyra abbottiae, P. fallax, and P. torta compared to Washington strains. We have also produced blades from conchocelis of P. cuneiformis, P. pseudolanceolata, and P. pseudolinearis Ueda species complex, for which release conditions have not yet been documented in northeast Pacific strains. Our results show that species of Porphyra in this region have multiple and varying conditions for spore release and blade production, and that important differences in these conditions can arise between populations within a region. Archeospores are reported for the conchocelis of both P. abbottiae and P. torta for the first time.

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The segmentally arranged Verson's glands are epidermal derivatives comprised of three cells: the duct, saccule, and secretory cells. The development of these glands was followed through the 5th instar and larval-pupal transition of Manduca sexta. The glands are relatively small during the feeding stage, begin to grow at wandering, and undergo about a 50-fold increase in size during the prepupal period. The increase in size is due mainly to the hypertrophy of the secretory cell which synthesizes a heterogeneous set of proteinaceous secretory products. Three prominent 11 to 12 kiloDalton (kD) polypeptides are made by the pharate fifth larval gland, whereas the pupal gland produces polypeptides ranging from 14 to 75 kD with a major complex at 30 to 34 kD. The secretory product is poured out onto the surface of the new cuticle at the time of ecdysis and contains all of the major proteins detected in extracts of the whole gland. The accumulation of secretory products by the gland occurs during the prepupal peak of ecdysteroid and is blocked if this rise is prevented by abdominal isolation. Infusion of 30 micrograms 20-hydroxyecdysone (20-HE) into such isolated abdomens caused synthesis of the pupal products. Treatment with the juvenile hormone mimic, methoprene, during the fifth instar showed that the commitment of the glands to produce the pupal proteins is independent of and occurs before the overlying epidermis becomes committed to make pupal cuticle.

Does density affect recruitment and growth in the annual, blade phase of Pyropia sp., does self-thinning occur, and does substrate affect recruitment? These questions were investigated in laboratory-cultured Pyropia torta, a naturally occurring species in Alaska with mariculture potential. Three density levels were produced from conchospores. Measurements were made, initially at settlement and germination and, subsequently, at approximately 3-week intervals, in 12 randomly selected cultures from each density level. Settled spores, germlings, or growing blades were counted microscopically and standardized to unit area. Blade surface area was measured microscopically using image analysis software. Three density levels were still distinct at germination, but the high and medium levels were not significantly different. The germination rate of conchospores was highest at the medium density level, suggesting facilitation at moderate densities but inhibition at higher densities. Significant self-thinning occurred at each density level but differed among levels, while overall blade growth was about 10-fold greater at low density than at the other two levels. In a separate experiment, counts of attached spores per unit area on artificial substrate materials were greatest on materials with interstitial spaces large enough to trap spores until they become firmly attached.