Phasing of cell division by temperature cycles in Euglena cultured autotrophically under continuous illumination

Summary Autotrophic cultures of Euglena in continuous light (LL) were exposed to temperature cycles spanning different temperature intervals in the physiological range. Each cycle consisted of a regular alternation between equal phases of two temperatures differing by 7°. Different temperature combinations varied in the degree to which they were capable of phasing cell division. The most effective combinations tested, 18/25° and 28/35°, produced almost as good a synchrony as has been observed from the use of light/dark cycles (at constant temperature) in this system. Both batch and chemostat cultures with a wide range of generation times were phased, and cycles with period lengths ranging from 8 to 24 hr appeared to be equally effective.Dry weight of cells per milliliter of sample was found to increase uniformly in phased cultures, indicating that most biosynthetic processes continue in such cultures even while all division is inhibited. Phasing cannot, therefore, be explained as a simple growth inhibition by the less favorable temperature of the cycle.The average generation times of cultures phased by 12,12 hr cycles were shorter than the expected times calculated from the results of the corresponding pairs of constant temperature experiments, indicating that temperature cycles have an overall accelerating effect on the growth of Euglena in continuous light. This and other evidence suggests that temperature cycles may be acting as Zeitgeber for Euglena in LL even though many trials revealed no persistence of a cell division rhythm in conditions of constant temperature and LL following temperature-cycle entrainment.This work is derived from a dissertation submitted to the Department of Biological Sciences of the State University of New York at Stony Brook by O. Terry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. It was supported in part by a National Science Foundation Cooperative Graduate Fellowship to O. Terry, and in part by National Science Foundation research grants GB-4140 and GB-6892 and by State University of New York Research Foundation Grant-in-Aid 31-7150A to L. Edmunds.     

The formation of ring canals by cell furrows in Drosophila

Summary Fifteen ring canals or intercellular bridges connect the oocyte and 15 nurse cells in Drosophila. Recently, Koch and King (1969) proposed that these ring canals formed independently of a cell furrow and that cytokinesis during the 4 cell divisions producing the 16 cells occurred through fusion of vesicles aligned along the division plane. Serial sections of germaria, fixed with glutaraldehyde, have been studied with the electron microscope, and no evidence has been found for fusion of vesicles in the cleavage of cells. The probability that the chromate-OsO₄ fixation used by Koch and King resulted in an artifact is discussed.The author gratefully acknowledges the assistance of Mrs. Joan Chlebowski; and the support of National Science Foundation grants GB-9780, GB-5780 and GB-24956; National Institutes of Health grant RR-05539; and an appropriation from the Commonwealth of Pennsylvania.     

Stability of the steady-state size distribution in a model of cell growth and division

The approach to steady-state size distribution is studied for a growing population of cells. The model incorporates cell growth at a linear rate and division into two equal daughters after a random time composed of an exponentially distributed phase and a constant deterministic phase.This work was supported by the National Science Foundation under Grant No. MCS 8300559This work was supported by the National Science Foundation under Grant No. MCS 8301104     

1,25-Dihydroxy vitamin D2 induces leukemia cell differentiation

This work supported in part by the NIH (USPHS), Council for Tobacco Research, American Institute for Cancer Research, and the Cornell Consolidated and Cornell Biotechnology Program which is sponsored by the New York State Science and Technology Foundation, a consortium of industries, the US Army Research Office and the National Science Foundation.     

Hypoxylon cohaerens: Cytology of the ascus

The haploid chromosome number ofHypoxylon cohaerens apparently is 5, based on counts made at meiotic prophase and meiotic and mitotic metaphases. Newly formed ascospores are at first uninucleate, becoming binucleate following mitosis in the ascospore. Subsequently, one of the two nuclei disappears. Maturing ascospores are uninucleate.Scientific Paper No. 3732 Washington State University. College of Agriculture, Project 1767. This study was supported in part by National Science Foundation Grant GB-19924.     

Cycling in simple genetic systems

We describe the — unexpected — occurrence of stable limit cycles in the two locus, two allele model. No frequency dependence is involved. The cycles are due to the interaction between recombination and natural selection.This work received support from the National Science Foundation and the Research Foundation of the City University of New York     

Evidence for the presence of proteinase inhibitor I in vacuolar protein bodies of plant cells

Summary Protein bodies induced in tomato leaf cells by wounding were shown to contain proteinase Inhibitor I by using ferritin-labelled antibodies, fluorescein-labelled antibodies, and cytochrome C-labelled antibody fragments. Both pre-embedding and postembedding techniques were used. Nonspecific binding was least when p-formaldehyde was used as the initial fixative followed by treatment with cytochrome c-labelled antibody fragments.Abbreviations Fab antibody fragments - BSA bovine serum albumin - GMA glycol methacrylate - THB Tris-HCl buffer Taken in part from a doctoral (Ph.D.) dissertation submitted to Washington State University by Vivian V. Yang. This work was supported largely by NSF Grant GB-29614X (LKS) and in part by the United States Department of Agricultural Cooperative States Research Service Grant 316-15-30 (CAR), the National Science Foundation Grant GB-37972 (CAR), and the College of Agriculture Research Center, Washington State University, Pullman, WA 99163, Scientific Paper No. 4525, Project 1791.Program in Genetics and Department of Botany. To whom reprint requests should be sent.Department of Agricultural Chemistry and Program in Biochemistry and Biophysics.     

Regulation of the Photosynthesis Rhythm in Euglena gracilis: I. Carbonic Anhydrase and Glyceraldehyde-3-Phosphate Dehydrogenase Do Not Regulate the Photosynthesis Rhythm

A circadian rhythm of O₂ evolution has been found in Euglena gracilis, Klebs strain Z. The rhythm persists for at least 5 days in constant dim light and temperature, but damps out in constant bright light. The phase of this rhythm can be shifted by a pulse of bright light and the period length is not changed over a 10 C span of growth temperature.

The O₂ evolution rhythm is found in both logarithmic and stationary phase cultures, but CO₂ uptake is clearly rhythmic only in stationary phase cultures.

The activity of glyceraldehyde-3-phosphate dehydrogenase was not rhythmic as previously reported (Walther and Edmunds [1973] Plant Physiol. 51: 250-258). Carbonic anhydrase activity was rhythmic when the cultures were maintained under a light-dark cycle with the highest enzyme activity coinciding with the fastest rate of O₂ evolution. However, the rhythm in carbonic anhydrase activity disappeared under constant conditions. Changes in the activities of these two enzymes are therefore not responsible for the rhythmic changes in photosynthetic capacity.

     

In vitro culture of tissue from the tunicateStyela clava

Summary Pharyngeal explants and circulatory hemocytes from the tunicateStyela clava were cultured in a medium containing tunicate plasma, artificial seawater, RPMI 1640, and antibiotics. Pharnngeal tissue remained viable and proliferated for up to 72 d in vitro. Proliferative activity maintained the pool of hemocytes within explants and facilitated the migration of pharyngeal hemocytes from explants into culture supernatants. The diversity of morphologically distinct cell types within the hemocyte pool of pharyngeal cultures indicated that cell division was followed by regulated differentiation. In contrast to pharyngeal cultures, suspensions of circulatory hemocytes did not survive for prolonged periods in vitro. Proliferative activity could not be detected in circulatory hemocyte cultures. These results are discussed in terms of the differentiation state of hemocytes and the efficacy of culture conditions. This study was supported by the National Science Foundation, Washington, DC (grant DCB 85 19848) and by BRSG funds from UCLA Schools of Medicine and Dentistry. Flow cytometric facilities were sponsored in part by a Johnson Cancer Center Core Grant (CA 16042). David A. Raftos is a Fulbright Postdoctoral Fellow and recipient of a Frederik B. Bang Scholarship in Marine Invertebrate Immunology administered by the American Association of Immunologist. Dan L. Stillman was supported by an REU supplement from the National Science Foundation.     

Cell Cycle-related and Endogenously Controlled Circadian Photosynthetic Rhythms in Euglena

The data presented for three strains of Euglena gracilis corroborate previous reports of a diel rhythm in photosynthetic capacity in division-synchronized cultures of this alga and extend these studies to free running, dividing and nondividing (stationary) cultures maintained in either 24-hour or 40-minute cycles of light and darkness. During synchronous growth entrained by LD: 12,12 or free running under LD: 1/3,1/3, photosynthetic CO(2) fixation was rhythmic with a period (24.0 or about 30 hours) corresponding to the period of the cell division rhythm in the population. Furthermore, the rhythm in CO(2) fixation (per cell) found in nondividing cultures maintained in LD: 12,12 persisted in LD: 1/3,1/3 for weeks with a free running, circadian period of approximately 30 hours. An endogenous, circadian rhythm in cellular chlorophyll was found to exist, independently of cell division, under both light regimens and in each individual experiment; this observation could reflect changes in the functional role of the pigment. In cultures maintained in LD: 1/3,1/3, the phase relationship between the rhythm of photosynthetic capacity and that of chlorophyll content varied, suggesting the possibility of desynchronization among circadian rhythms in a multioscillator, unicellular organism.     

Enrichments of aquatic bacteria in continuous culture

Summary A chemostat was employed for the enrichment and eventual isolation of a variety of heterotrophic bacteria from seawater. Experimental attempts to separate single species from mixed cultures of known composition showed that successful or unsuccessful competition for the limiting substrate is based upon the particular growth parameters of the individual species under the given culture conditions. The technique appears to be suitable to enrich reproducibly for bacterial species of little substrate specificity. Applications in ecological studies are discussed.Dedicated to Prof. C. B. Van Niel on the occasion of his 70th birthday.Contribution No. 1919 of the Woods Hole Oceanographic Institution. Supported by the National Science Foundation Research Grant No. GB-5199.     

Hypoxylon rubiginosum: Cytology of the ascus and surface morphology of the ascospore

Summary The haploid chromosome number ofHypoxylon rubiginosum is 5. The ascospore is uninucleate when formed, becoming binucleate following a mitosis. One of the nuclei subsequently disintegrates. Maturing ascospores are uninucleate.The morphology of the ascospore, as revealed by the scanning electron microscope, is described. The outer wall layer — the perisporium — shows heretofore undescribed surface fibrils. The possible significance of the fibrils is discussed.Paper No. 3205. Washington State University College of Agriculture Project 1767. This study was supported in part by National Science Foundation Grants GB-5219 and GB-8004.     

A phylogenetic comparison of mutation spectra

Summary Spectra of induced mutations resulting in obligate organoauxotrophy are compared at different phylogenetic levels from bacteria to higher plants. It appears that the spectra of mutants concerned with basic cell metabolism are more or less the same in bacteria and fungi. In higher, green plants (an alga and an angiosperm) the spectra are qualitatively different. Mutation frequency in certain pathways is common, while in others no mutants have been found. This lack of recovery of many classes of mutants indicates a reduction, by several orders of magnitude, in either mutability or detectability of the mutants in the majority of the biosynthetic systems.Contribution from the Missouri Agricultural Experiment Station. Journal Series No. 5167. Approved by the Director.This work was supported by National Science Foundation Grants GB-3999, GB-4301 and U.S. Atomic Energy Commission Contract AT (11-1)-1609.     

Neuronal control of heartbeat in the medicinal leech

Summary The leech heartbeat consists of a constriction-dilation rhythm of two lateral heart tubes extending over the length of the body. The beats of the segmental sections of these two tubes are coordinated in such a manner that the heart tube of one body side produces a frontward peristaltic wave while the heart tube on the other body side produces nearly concerted constrictions. This rhythm is metastable, in that left and right heart tubes alternate between peristaltic and concerted constriction modes, with a given mode lasting for tens or hundreds of beat cycles.The constriction-dilation cycles of the segmental heart tube sections are controlled by a set of rhythmically active motor neurons, the heart excitors, or HE cells. A bilateral pair of HE cells is located in all but the two frontmost and the two rearmost segmental ganglia of the ventral nerve cord. Each HE cell innervates via excitatory synapses the circular muscle fibers in the wall of the ipsilateral heart tube section. The activity cycle of the HE cells consists of an active phase, during which they are depolarized and produce a burst of impulses, and an inactive phase during which they are repolarized by a burst of inhibitory synaptic potentials. The intersegmentally coordinated activity cycles of the HE cell set are maintained in an isolated ventral nerve cord. Hence the generation of the heart excitor rhythm does not require sensory feedback.We are indepted to Amy Kelly and King-Wai Yau for advice on the use of the intracellular staining technique and to John Kretz for calling to our attention the existence of an afferent impulse burst rhythm emanating from denervated heart tube preparations. We thank Georgia Harper for excellent technical assistance. This research was supported by Grant GB 31933X from the National Science Foundation and NIH research grants GM17866 and Training Grant GM 01389 from the Institute of General Medical Sciences.     

Ultrastructural changes in nurse and follicle cells during late stages of oogenesis in Drosophila melanogaster

Summary During stages 11 and 12, follicle cells surrounding the nurse cells produce lysosomes which presumably aid in the breakdown of the nurse cells. Accompanying a DNA reduction in nurse cell nuclei are several characteristic morphological changes including the appearance of intranuclear rod-like structures and nuclear granules about 300 Å in diameter. Similarities between structures seen in Drosophila nurse cell nuclei and those seen in other organisms are discussed.This research was supported by U. S. Public Health Service Grants 5TIGM903-3 and 1-F1-GM-33, 385-01 and National Science Foundation grant GB-7457.     

Hypoxylon deustum: The chromosome number

Summary The haploid chromosome number ofHypoxylon deustum is 4. Ascospores are uninucleate when formed, becoming binucleate shortly thereafter. One of the two nuclei disappears in maturing ascospores. Mature ascospores are apparently uninucleate. The significance of these and other findings to the taxonomy of the fungus is discussed.Scientific Paper No. 3008. College of Agriculture, Washington State University. Project 3767.This study was supported in part by National Science Foundation Grant GB-5219.     

Relative growth and nutrient accumulation rates for tobacco

Summary Tobacco plants (Nicotiana tabacum L.) were grown from transplanting until floral expression in the phytotron units of Southeastern Plant Environment Laboratories to evaluate the relationship between relative growth rate (RGR) and relative accumulation rates (RAR) of N, P, K, Ca, and Mg. RAR is calculated to be analogous to RGR. Plants were grown in both controlled-environment rooms with artificial light and air-conditioned greenhouses with natural light at three temperature conditions and three application rates of N-P-K. RGR and RAR were calculated only for the period of grand growth which occurred within the interval from 7 to 32 days after transplanting. In general, neither RGR nor RAR were affected by temperature or nutrient level. However, both temperature and nutrient level affected dry matter accumulation of the plants apparently by an influence on the rapidity with which plants adjusted to their new environment during the initial 7-day interval after transplanting. RAR for P and K were coequal with RGR of the whole plant; thus, the concentrations of P and K within the plant tended to remain constant during growth. RAR for N, Ca, and Mg were less than RGR for the whole plant; thus, internal concentrations of these nutrients declined during growth. RAR of N, Ca, and Mg for the whole plant were equivalent to RGR of the roots. As a rationale for the association of RGR of roots and RAR of N, it is proposed that the soluble carbohydrate pool in the roots concurrently influences both N absorption, as NO₃ ^-, and growth of new roots of immature plants. Research reported in this paper was supported in part by National Science Foundation (RANN) Grants GI-39229 and GI-39230. Operation of the Phytotron Units of Southeastern Plant Environmental Laboratories at Duke and North Carolina State Universities was supported by National Science Foundation Grants GB-28950-1A and GI-28951. Approved as Paper Number 4773 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, NC. Research reported in this paper was supported in part by National Science Foundation (RANN) Grants GI-39229 and GI-39230. Operation of the Phytotron Units of Southeastern Plant Environmental Laboratories at Duke and North Carolina State Universities was supported by National Science Foundation Grants GB-28950-1A and GI-28951. Approved as Paper Number 4773 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, NC.     

A test for hormonal responsiveness in a mammary epithelial cell line,NMuMg

Summary The NMuMG cell line derived from normal mouse mammary epithelial cells was tested for responsiveness to hormones. The hormones studied included insulin, glucocorticoids (cortisol and dexamethasone), and prolactin. In addition to membrane bound insulin receptors and prolactin receptors, the cells had 2 × 10⁴ cytoplasmic glucocorticoid receptors per cell. Morphological changes were observed in response to hormones. Clusters of cells appeared with greatly increased diameter, and the number of cells per plate was reduced. The rate of DNA synthesis, corrected by cell number, indicates that cell division, and hence cell turnover, was increased by the combination of all three hormones. Insulin greatly enhanced protein synthesis, but glucocorticoid and prolactin did not further increase the rate. The combination of the three hormones produced a change in the synthesis of histones, consistent with the increase in cell turnover. There were substantial responses of enzyme activities to hormonal treatment of the cells. Insulin by itself induced a doubling of the activity of glyceraldehyde phosphate dehydrogenase and perhaps a modest increase in NADH-cytochromec reductase. Lactose synthetase activity showed a three- to fourfold induction of both A and B subunits of the enzyme when the cells were treated with insulin, glucocorticoid, and prolactin, and the effect of the latter two hormones was shown to be additional to that of insulin. This work was supported by Contract N01-CB-43866 from the National Cancer Institute, by Grants GB-38658 from the National Science Foundation and GMS-20338 from the National Institutes of Health, and by the Agricultural Experimental Station at the University of California.     

Somatic cell cryopreservation and protoplast regeneration of important disease-resistant wild rice Oryza meyeriana Baill

Oryza meyeriana Baill is one of the three wild rice species found in Chiia.O. mcyeriana possesses valuable characteristics but is reluctant in cell culturein vitro. In a series of experiments, callus with no regeneration ability was induced from young panicle ofO. meyeriana. The callus was subcultured and propagated. Embryogenic cell clones were obtained after cryopreswation. Suspension cultures were established and protoplasts were isolated and regenerated into plants. Results of artificial inoculation ofXanthomonas campestris pv.Oryzae showed that the strong resistance did not change in the regenerated plants. The development of protoplast-to-plant system is an important progress towards utilization ofO. meyeriana via cellular engineering. The experiments demonstrated that cryopreservation of plant calli was a new way to obtain embryogenic cell line. Project partially supported by the National Natural Science Foundation of China (Grant No. 392704361, Foundation for Outstanding Young Teachers of China, State Key Program of China and Natural Science Foundation of Hubei Province, China.     

Ethological study of early language

Sign language studies of cross-fostered chimpanzees measure the effect of special rearing conditions on the development of very young chimpanzees. Cross-fostered chimpanzees, like human children, develop gradually in a process that takes many years. Here we discuss details of the procedure, the overlap between human and chimpanzee infants in the contents of the first 50-item vocabularies, and the ways in which the signs of the chimpanzees exhibit the fuzziness of natural language categories. We also compare the cross-fostering approach with more traditional modular approaches to the study of language-like behavior in nonhuman animals. Project Washoe was originally supported by grants MH-12154 from the National Institute of Mental Health and GB-7432 from the National Science Foundation. We gratefully acknowledge this support and the support that later sign language studies of chimpanzees have received since then from NIH, NSF, the National Geographic Society, the Grant Foundation, the Spencer Foundation, the University of Nevada, and the UNR Foundation.