Henry I. Hirshfield

Peripheral effects of cadmium on the blood and head kidney in the brown bullhead (Ictalurus nebulosus)

The study was undertaken to determine the amount and rate of uptake of cadmium via atomic absorption measurements, and to determine whether acute cadmium exposure (61 ppm) provides alterations in the blood and head kidney. The results indicate that the peripheral blood and head kidney of indigenous fish species feeding in the area of the dump provide the best immediate monitor for water quality. The head kidney and peripheral blood coupled with chemical analysis for cadmium indicate that the head kidney may be one of the initial target organs of cadmium toxicity. After an initial 2-h exposure of 61 ppm cadmium, an immediate and 24-h intervals were used to examine the effect, uptake, storage and clearance of cadmium from the peripheral blood and head kidney. (JMT)

Reconstitutive events in Blepharisma undulans as affected by colchicine

Abstract 1. 1. The effects of selected dosages of colchicine (10 −2 to 10 −13 M ) were studied in a red-pigmented, heterotrichous ciliate Blepharisma undulans on the following: (1) division, (2) regeneration of cut Blepharisma , (3) conjugation, (4) survival of whole Blepharisma , regenerating and non-regenerating fragments. 2. 2. Concentrations below 10 −4 M were ineffective on all processes studied. Higher concentrations (10 −2 M and above) were cytolytic to Blepharisma . 3. 3. Reconstruction of the red pigment in bleached forms was unaffected by colchicine. The response of bleached forms to colchicine was the same as unbleached organisms. Cannibal-giants were less affected by colchicine on the processes studied than normal forms. 4. 4. The effect on division indicated that in ciliate protozoa where there is an amitotically dividing nucleus, the macronucleus, the division of the cytoplasm is apparently unaffected by disruption of the mitotically dividing micronuclei. 10 −4 M produced micronuclear mitotic inhibition without affecting cytoplasmic division, 10 −3 M affected both processes. 5. 5. Conjugating whole Blepharisma or conjugant fragments were more affected by lower concentrations (10 −4 M ) than non-conjugating forms. In some instances conjugating organisms exposed during conjugation did not recover from colchicine exposure. The inability to recover may possibly be due to a disruption of the new nucleus. 6. 6. The process of regeneration in Blepharisma was more affected by lower concentrations (10 −4 M ) than was division. The effect on regeneration may possibly be due to a disruption of the ciliary fibrillar systems. 7. 7. An explanation is offered for the change from the normal-sized individual to the cannibal-giant. This change may be due to the production of a polyploid individual.

Nuclear Control of Cytoplasmic Activities

The study of enucleated amoebae or anucleate fragments is somewhat frustrating to the investigator who attempts to understand the after-effects of the treatment. The visible activities of the anucleate cell and the changes in cytoplasmic constituents do not indicate the profound damage done by removal of the nucleus. A consensus of early publications is nicely summarized by Minchin: “Non-nucleated fragments may continue to live for a certain time; in the case of Amoeba such fragments may emit pseudopodia, the contractile vacuole continues to pulsate, and acts of ingestion and digestion that have begun may continue; but the power to initiate the capture and digestion of food ceases, consequently all growth is a t an end, and sooner or later all non-nucleated bodies die off” (F. bI. Summers). On the whole, there is general agreement with the above statement, except perhaps with that portion dealing with food capture and digestion. I have observed paramecia, damaged by neutral red, captured and “digested” in food vacuoles of anucleate fragments. The “digestion” however, could have been in reality autolysis. Factors considered to be of importance in the activities and longevity of the fragment are the size of the fragment (thus an enucleated amoeba might be expected to have the longest life span and the maximal degree of activity as compared to an anucleate half of an amoeba), and the area of the amoeba removed. If the fragment is from the posterior half (“old gel area”) the locomotor activities are reduced as compared with a fragment obtained from the anterior or pseudopod-forming region. There is great need for the development of a chemically defined medium for the axenic culture of the large free-living amoeba. At present metabolic studies of aging anucleate populations become involved in questions of techniques of culture. Current comparative studies between nucleate and anucleate populations tend to be of the short-range type: terminated within 24 hours, or imposed conditions of starvation (for example, several washes and then maintenance in sterile salt solutions). The latter approach adds the effects of starvation to the effects of anucleation. It is based on the premise that a starving nucleate fragment is an adequate control for the anucleate fragment, which is not necessarily the case, as shown in some of the shortrange studies. However, a t present there is no other alternative, unless the techniques for the induction of pinocytosis (as reported by Marshall and by Holter in this monograph) can provide an approach to the problem of obtaining a well-defined medium for amoebae. Possibly the most comprehensive reports on the activities of enucleate amoebae and anucleate fragments are those of Clark, 1942 and 1943. In his analyses of the behavior of the anucleate, Clark emphasized the importance of the nu-

MACRONUCLEAR VARIABILITY OF BLEPHARISMA ASSOCIATED WITH GROWTH

Publisher Summary This chapter discusses the macronuclear variability of Blepharisma associated with growth. Ten different strains of the genus Blepharisma were selected for comparative studies of their nuclear and cytoplasmic growth from the twenty different strains in culture in the laboratory. A cyst-producing strain from Hingham, Massachusetts, was included among the ten strains. The different species, when grown at 18°C and fed upon bacteria, are morphologically distinguishable as species. The two strains of B. undulans, while they are distinctively different physiologically, are not sufficiently morphologically different to separate them at present into different species. Studies of the effects of different types of nutrition, combined with exposures to 5°C and 36°C, showed that at the high and low temperatures, although there were at first differences in reaction, ultimately all of the species were so drastically altered that they became morphologically indistinguishable. Organisms that were exposed to the 5°C again exhibited their characteristic morphology when returned to 18°C. Adaptation to 36°C of some of the organisms of one species fed on Tetrahymena occurred. That species was B. seshachari. The adapted individuals maintained their species characteristics.

The Effects of Chloramphenicol and Actinomycin D on the Nucleus of the Dinoflagellate Gonyaulax monilata

SUMMARY: The effects of two drugs (chloramphenicol, actinomycin D) which inhibit protein synthesis on the nucleus of the dinoflagellate Gonyaulax monilata were examined. Chloramphenicol had no effect on the morphology of the nucleus but caused a diminution of cytoplasmic protein and a suppression of growth; did not completely suppress mitosis. Treatment with actinomycin D resulted in the loss of chromosomal arrangement within the nucleus, the fraying of the edges of the nucleus and the loss of the nuclear ‘band’, and suppressed division. The results are thought to support the hypotheses that the matrix functions in maintaining nuclear morphology and that the ‘band’ is necessary for mitosis.

Giant Carbohydrate-rich Cells of the Dinoflagellate Gonyaulax monilata

SUMMARY: A small number of organisms in cultures of the dinoflagellate Gonyaulax monilata attained twice the diameter of normal organisms and showed an excessive accumulation of carbohydrate reserves. The nuclei of these giants degenerated as did the cytoplasm. It is suggested that this was not a response to cultural conditions but represented an altered metabolism of individual organisms.