. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. VII VIII \ $.'••. .'.:•" Region Mitosis Expansion Setal area Mitosis Expansion Setal area Protopod 4,662 SC NA NA Endues 1,080 1 1 .653 Endopod 88 SC NA 293 9,007 535 Exopod 185 None NA 222 402 Epipod 480 SC NA 250 6,774 NA Total = (11,315) [72,906) Expansion indicates an increase in apical surface area supported by biosynthesis of new plasma membrane. Setal area was determined as the area of a cone, using setal height and base diameter mi
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. VII VIII \ $.'••. .'.:•" Region Mitosis Expansion Setal area Mitosis Expansion Setal area Protopod 4,662 SC NA NA Endues 1,080 1 1 .653 Endopod 88 SC NA 293 9,007 535 Exopod 185 None NA 222 402 Epipod 480 SC NA 250 6,774 NA Total = (11,315) [72,906) Expansion indicates an increase in apical surface area supported by biosynthesis of new plasma membrane. Setal area was determined as the area of a cone, using setal height and base diameter minus the original apical surface area. SC indicates an increase due to cell shape change without synthesis of additional plasma membrane. Values in parentheses at bottom indicate the grand total for the period of growth. NA indicates that the region lacks setae. (Coutteau and Mourente, 1997; Sakamoto et 1982). Similar results have been obtained with other crustaceans (Kanazawa and Koshio, 1994). Considering the rapid rate of cellular growth observed in this study, the level of essential fatty acids in the diet becomes critical for optimum cell differentiation. Several studies have demonstrated variation in the num- ber of larval instars in Artemia, and some of the observa- tions shown here are slightly different from those seen in previous studies (Schrehardt. 1987). Variation in instar number has also been shown in other groups of crustacean larvae (Williamson, 1982). Although these differences could be ascribed to different strains of cysts, it is equally possible that the feeding regime affects the number of instars. Knowlton (1974) and McConaugha (1985) have suggested that nutrient allocation for general maintenance, molting, growth, and differentiation occurs during each instar and that there may be a hierarchy in the allocation such that cell differentiation does not occur when the levels of essential nutrients (fatty acids) are low. The cells may allocate nutr
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
