THE CYTONUCLEOPROTEINS OF AMEBAE : I. Some Chemical Properties and Intracellular Distribution

Autoradiographs of whole Amoeba proteus host cells fixed after the implantation of single nuclei from A. proteus donors labeled with any one of 8 different radioactive amino acids showed that the label had become highly concentrated in the host cell nucleus as well as in the donor nucleus and that the cytoplasmic activity was relatively low. When these amebae were sectioned, the radioactivity was found to be homogeneously distributed throughout the nuclei. The effect of unlabeled amino acid "chaser," the solubility of the labeled material, and the long-term behavior of the labeled material gave evidence that the radioactivity was in protein. At equilibrium, the host cell nucleus contained approximately 30 per cent of the radioactivity distributed between the two nuclei. This unequal nuclear distribution is attributed to the presence of two classes of nuclear proteins: a non-migratory one that does not leave the nucleus during interphase, and a migratory one, called cytonucleoprotein, that shuttles between nucleus and cytoplasm in a non-random manner. It is estimated that between 12 per cent and 44 per cent of the cytonucleoproteins are present in the cytoplasm of a binucleate cell at any one moment. Nuclei of Chaos chaos host cells also concentrated label acquired from implanted radioactive A. proteus nuclei.     

ELECTRON MICROSCOPIC STUDIES OF MITOSIS IN AMEBAE : II. The Giant Ameba Pelomyxa carolinensis

Dividing nuclei from the giant ameba Pelomyxa carolinensis were fixed in osmium tetroxide solutions buffered with veronal acetate to pH 8.0. If divalent cations (0.002 M calcium, magnesium, or strontium as chlorides) were added to the fixation solution, fibrils that are 14 mµ in diameter and have a dense cortex are observed in the spindle. If the divalent ions were omitted, oriented particles of smaller size are present and fibrils are not obvious. The stages of mitosis were observed and spindle components compared. Fibrils fixed in the presence of calcium ions are not so well defined in early metaphase as later, but otherwise have the same diameter in the late metaphase, anaphase, and early telophase. Fibrils are surrounded by clouds of fine material except in early telophase, when they are formed into tight bundles lying in the cytoplasm unattached to nuclei. Metaphase and anaphase fibrils fixed without calcium ions are less well defined and are not observably different from each other. The observations are consistent with the concept that spindle fibrils are composed of polymerized, oriented protein molecules that are in equilibrium with and bathed in non-oriented molecules of the same protein. Partially formed spindle fibrils and ribosome-like particles were observed in the mixoplasm when the nuclear envelope had only small discontinuities. Remnants of the envelope are visible throughout division and are probably incorporated into the new envelope in the telophase. Ribosome-like particles are numerous in the metaphase and anaphase spindle but are not seen in the telophase nucleus, once the envelope is reestablished, or in the interphase nucleus.     

THE DEVELOPMENT OF GOLGI COMPLEXES AND THEIR DEPENDENCE UPON THE NUCLEUS IN AMEBAE

The production of Golgi complexes was investigated in Amoeba proteus by introducing a nucleus into cells that had been enucleated for 5 days. Golgi complexes were not detected in 5 day enucleates, nor were they observed in amebae fixed 15 min after renucleation. Samples taken at longer intervals after the introduction of a nucleus exhibited an increase in the size and abundance of Golgi complexes. Small curved smooth cisternae, some of which were aligned in parallel to form small Golgi complexes, were observed 30 min after the operation. Aggregations of small Golgi complexes increased in number in amebae fixed 1 to 6 hr after renucleation. Golgi complexes of normal size were present 6 hr after the operation and became more abundant in samples fixed 12 hr, and 1, 2, and 3 days after renucleation. The possible participation of the granular endoplasmic reticulum in the development of Golgi complexes was suggested by two observations. First, the Golgi complexes in renucleates contained a dense material similar to the content of the endoplasmic reticulum in enucleates and early renucleates. Second, examples of continuity between the endoplasmic reticulum and Golgi cisternae were present in renucleates. The possibility that Golgi complexes can be produced in the absence of preexisting Golgi complexes is discussed.     

Some Aspects on Acyclonucleoside Synthesis

Abstract

An acyclonucleoside synthesis was investigated on the regioselective introduction of an acyclochain. We found that iodotrimethylsilane catalyzed the reaction of acyclochain introduction as well as its migration from S² to N¹ of 2-thiothymine and from N⁷ to N⁹ position of guanine. By taking the findings into account, several acyclo-nucleosides were synthesized in a simple one-pot procedure.     

Some Aspects of Social Behavior in the Canidae

Despite the diversity of morphology and ecology in members ofthe Canidae, social behavior remains similar throughout theFamily. Some specializations have occurred in groupliving species,serving to maintain group cohesion and to reduce intraspecificaggression, and these changes in behaviors and postures havebeen ones of degree rather than kind. The type of specializationdiffers in each species and is probably related to its ecology.Thus, the bateared fox has developed contact behaviors suchas social grooming while the wolf has evolved more specializedagonistic postures that are used in the maintenance of a socialhierarchy.     

ELECTRON MICROSCOPIC STUDIES OF MITOSIS IN AMEBAE : I. Amoeba proteus

Individual organisms of Amoeba proteus have been fixed in buffered osmium tetroxide in either 0.9 per cent NaCl or 0.01 per cent CaCl₂, sectioned, and studied in the electron microscope in interphase and in several stages of mitosis. The helices typical of interphase nuclei do not coexist with condensed chromatin and thus either represent a DNA configuration unique to interphase or are not DNA at all. The membranes of the complex nuclear envelope are present in all stages observed but are discontinuous in metaphase. The inner, thick, honeycomb layer of the nuclear envelope disappears during prophase, reappearing after telophase when nuclear reconstruction is in progress. Nucleoli decrease in size and number during prophase and re-form during telophase in association with the chromatin network. In the early reconstruction nucleus, the nucleolar material forms into thin, sheet-like configurations which are closely associated with small amounts of chromatin and are closely applied to the inner, partially formed layer of the nuclear envelope. It is proposed that nucleolar material is implicated in the formation of the inner layer of the envelope and that there is a configuration of nucleolar material peculiar to this time. The plasmalemma is partially denuded of its fringe-like material during division.     

Some Aspects of the Chemical Synthesis of Oligoribonucleotides

Abstract

The present position regarding the protection of the 2′- and 5′-hydroxy functions in the chemical synthesis of oligoribonucleotides is discussed.     

Some Aspects of the Nesting Behavior and Reproductive Biology of Sea Turtles

Basic reproductive data from 21 green turtle (Chelonia mydas),8 leatherback (Dermochelys coriacea), 7 hawksbill (Eretmochelysimbricata), 7 olive ridley (Lepidochelys olivacea),6 loggerhead(Caretta caretta), 1 Kemp's ridley (Lepidochelys kempi), and1 flatback (Chelonia depressa) populations are provided. Someintraspecific and interspecific relationships between size ofnester and clutch, egg size and hatchling size are analyzed.Measurements of reproductive rates (=numbers of hatchlings perfemale per year) in 11 populations varied from 35 to 200 inan olive ridley and loggerhead colony, respectively. Nestingbehavior of each species is described in terms of type of nestingemergence and time spent on the nesting beach (=chelonery).The relatively large number of yolkless eggs laid by many leatherbacksand by some hawksbills invites further study. Some aspects ofsea turtle nesting behavior and reproduction are compared tothose of other chelonians.     

A Comparative Study of Some Brands of Tolbutamide Available in Canada: Part II. Pharmaceutical Aspects

Pharmaceutical analyses were carried out on 26 lots of tolbutamide from 21 manufacturers. All lots were found to be satisfactory with respect to identity and strength. Disintegration time of 24 lots ranged from one to 35 minutes, with 72 and 83 minutes for the other two. The time to 90% dissolution in intestinal solution (pH 7.5) ranged from five to 69 minutes in all except two lots for which the times were 99 and over 120 minutes. While the clinical significance of these findings cannot be ascertained in the absence of data from controlled studies, the evidence does not suggest that most of the non-proprietary products available in Canada would not be satisfactory for the purpose intended.     

Nitrogen Metabolism of Lemna minor. II. Enzymes of Nitrate Assimilation and Some Aspects of Their Regulation

In L. minor grown in sterile culture, the primary enzymes of nitrate assimilation, nitrate reductase (NR), nitrite reductase (NiR) and glutamate dehydrogenase (GDH) change in response to nitrogen source. NR and NiR levels are low when grown on amino acids (hydrolyzed casein) or ammonia; both enzymes are rapidly induced on addition of nitrate, while addition of nitrite induces NiR only. Ammonia represses the nitrate induced synthesis of both NR and NiR.NADH dependent GDH activity is low when grown on amino acids and high when grown on nitrate or ammonia, but the activities of NADPH dependent GDH and Alanine dehydro-genase (AIDH) are much less affected by nitrogen source. NADH-GDH and AIDH are induced by ammonia, and it is suggested that these enzymes are involved in primary nitrogen assimilation.     

Some Evolutionary Aspects of the Food-Procuring Group Behavior in Phylogenesis of Primates

The peculiarities were studied of the intragroup competitive and cooperative behavior of primates differing by the level of phylogenetic development, beginning from low-organized species of the higher primates to high-organized anthropoid monkeys (Callithrix jacchus, Cebus apella, Macaca mulatta, Papio hamaofrijas, Pan troglodytes). It has been shown that in all monkeys, under conditions of competitive feeding situation, there were changes of the complex behavioral forms observed at individual learning. Under conditions of the activity in pairs, the females of platyrrhine (New World) and lower narrow-nose (Old World) monkeys lost the possibility to realize the skill and food needs, so the programmed tasks were solved predominantly by the males. In chimpanzees, the change of indices of instrumental activity involved to the equal degree the male and female, and solution of the alternation task was higher in individual experiments. The age differences were revealed in the competitive behavior of chimpanzees in group. The realization of formed skills depended on the complex of factors including the requirements dominating in the given situation and the age and typological peculiarities, as well as the social rank of each monkey in the community. In rhesus macaques the capability for cooperative interaction was revealed under conditions of complex operant activity.     

THE PHAGOCYTOSIS OF SOLID PARTICLES : II. CARBON.

1. By measurements of the diameter and velocity of leucocytes and of the particles in two carbon suspensions, the relative rates of ingestion of the two suspensions by the leucocytes are predicted and the predictions verified experimentally. 2. The results indicate that 4.7µ particles of carbon are ingested as readily as 3.2µ particles. The more rapid apparent rate of ingestion of the 4.7µ particles is due to their greater availability rather than the greater capability of the leucocytes. 3. There is almost no phagocytosis of carbon in absence of serum or in heated serum. 4. The clumping of unwashed leucocytes is accllerated by serum and by the ingestion of carbon. 5. The available evidence indicates that the phagocytosis of bacteria does not follow the law for a monomolecular reaction, possibly because of the toxic effect upon the leucocytes of bacterial extracts.     

THE EFFECT OF RENNIN UPON CASEIN : II. FURTHER CONSIDERATION OF THE PROPERTIES OF PARACASEIN.

The properties of the paracasein and casein preparations studied are compared in Table VI. See PDF for Structure I. Casein retains its characteristic solubility in NaOH: (1) after being exposed to a high degree of alkalinity during its preparation, (2) when recovered from partially hydrolyzed solutions in NaOH, and (3) after being kept for a prolonged time at the isoelectric point at 5°C. II. It follows from I, that: (1) paracasein is not identical to casein modified by an excess of alkali, and that (2) this protein was not produced from casein by a partial hydrolysis of the latter in presence of NaOH.     

THE ULTRASTRUCTURE OF THE CAT MYOCARDIUM : II. Atrial Muscle

The ultrastructure of the cells specialized for contraction in the atrium and ventricle of young adult cats are compared. The cells specialized for conduction are not included. In addition to possessing distinctive atrial granules, the cells of the atrium are smaller in diameter (5–6 µ) than ventricular cells (10–12 µ) and have strikingly fewer T tubules. These latter differences are discussed in terms of their possible significance for the rate of conduction of the action potential. It is suggested that the very small number of T tubules in atrial cells may compensate for the small cell diameter, and thus permit rapid conduction of the action potential across the surface of the atrium. Coated dense vesicles found in association with the sarcoplasmic reticulum at the level of the Z line in ventricular muscle are more evident in atrial cells. In the virtual absence of T tubules in atrial cells, the sub-sarcolemmal cisternae of the sarcoplasmic reticulum are almost exclusively at the cell periphery. The ends of the cells and their processes in ventricular muscle are rectilinear with the interdigitated portions of the intercalated discs oriented transversely, whereas those of the atrium are often oblique to the myofilament axis. This difference may be related to the lower mechanical tension on atrial cells.