Physiological changes accompanying the recovery of cell division in "giant" cells of Chlorella vulgaris (EMERSON strain)

A homogeneous population of "giant" cells of the EMERSON strainof Chlorella vulgaris, produced following culture under carefullycontrolled conditions in a glucose medium in the dark, recoversits capacity to undergo cell division when returned to autotrophicconditions. A similar recovery also occurs after a prolongedperiod of culture in the dark. The division of the giant cellsis accompanied, in each case, by marked pigment synthesis anda consequent recovery of photosynthetic capacity. Under autotrophicconditions the recovery of cell division and restoration ofthe full pigment concentration are complete within a 24 hr period.The recovery which takes place in a glucose medium in the darkoccurs only after a period of 10–14 days growth. (Received May 9, 1970; )     

Physical and physiological costs of ectoparasitic mites on host flight endurance

1. Dispersal is essential for locating mates, new resources, and to escape unfavourable conditions. Parasitism can impact a host's ability to perform energetically demanding activities such as long‐distance flight, with important consequences for gene flow and meta‐population dynamics. 2. Ectoparasites, in particular, can adversely affect host flight performance by diminishing flight aerodynamics and/or by inflicting physiological damage while feeding on host tissue. 3. Experimental flight assays were conducted using two fruit fly‐mite systems: Drosophila nigrospiracula (Patterson and Wheeler) – Macrocheles subbadius (Berlese) and D. hydei (Sturtevan) – M. muscaedomesticae (Scopoli). Flies that are burdened by mites are expected to exhibit lower flight endurance compared to uninfected flies. 4. The results show that the presence of mites (attached) significantly decreased flight endurance by 57% and 78% compared to uninfected D. nigrospiracula and D. hydei, respectively. The physiological damage caused by M. subbadius was revealed through a 53% decline in flight time among previously infected flies (mites removed just prior to flight assay). Surprisingly, the presumably phoretic M. muscaedomesticae also caused a 62% reduction in flight endurance among previously infected D. hydei. 5. These results suggest a strong deleterious effect of ectoparasitic mites on host flight performance, mediated by a reduction in flight aerodynamics and damage to host physiology. Adverse effects on host flight and/or dispersal may have broad implications for gene flow, population genetic structure, and local adaptation in both host and parasite meta‐populations.     

The contrasting effects of chloramphenicol and cycloheximide on the recovery of cell division and chlorophyll synthesis in "giant" cells of Chlorella vulgaris (Emerson strain)

The simultaneous recovery of cell division and chlorophyll synthesisin "giant", "bleached" cells of the Emerson strain of Chlorellavulgaris which occurs upon exposure to light has been investigatedusing the two inhibitors of protein synthesis, chloramphenicoland cycloheximide. With both antibiotics, it has been foundpossible, under suitable conditions, to separate cell divisionand chlorophyll synthesis. The best separation is obtained withthose chloramphenicol treatments which severely inhibit chlorophyllsynthesis and the development of a photosynthetic capacity butwithout affecting cell division. The separation achieved withcycloheximide is less clear-cut. The significance of these resultsis discussed with particular reference to the relationship betweenchloroplast development and other events occurring in the cytoplasm. (Received October 12, 1970; )     

"Brother" and "Uncle": An Analysis of Rules, Structural Contradictions, and Meaning in Vietnamese Kinship

This paper analyzes the meanings of Vietnamese kinship terms on the basis of the rules that regulate their referential and nonreferential uses. These rules are not completely consistent with one another. They constitute contradictory models of and for sociocultural reality at a certain level. The structural contradictions among these models render "fuzzy" even the definitions of the prototypical uses of Vietnamese kin terms. The coexistence of alternative models makes the use of a linguistic form both a goal-directed action and the representation of an order.