Buccal mass structure of the Cretaceous ammonite Gaudryceras

A rhynchaptychus attributed to the lower jaw of Gaudryceras sp. from the Upper Santonian rocks of Hokkaido, Japan, has an interesting impression well-preserved on the inner surface of the outer lamella. The impression is regarded as the imprints of chitin-secreting cells (beccublast cells), because of similarity in the characteristic arrangement of polygonal pits to those of modern coleoids. Each unit cell impression of G. sp. is, however, about five to ten times larger than in modern coleoids known to us. In modern coleoids and Nautilus a layer of tall beccublast cells is intercalated between the buecal muscles and the outer side of the upper jaw and/or the inner side of the lower jaw. The other sides of the jaws are, in contrast, free from jaw muscles, and are covered directly with a thin connecting tissue. Based on these observations a possible buecal mass structure of G. sp. is restored. The beccublast cell impressions of Gaudryceras and modern coleoids markedly differ from that of modern Nautilus in the absence of numerous micropores. This fact suggests weaker mechanical properties of the jaw muscles in Gaudryceras than in Nautilus , as the branching ends of beccublast cells of the latter are inserted in the micropores to keep a firm attachment of the jaw muscles on the jaw plates.     

AUXIN-INDUCED GROWTH OP TUBER TISSUE OP JERUSALEM ARTICHOKE: III. EFFECT OF ACTINOMYCIN D ON AUXIN-INDUCED EXPANSION GROWTH AND RNA SYNTHESIS

1. The following results were obtained using tissue slices excisedfrom cold-stored Jerusalem artichoke tubers.
2. Actinomycin Dat the concentration of 20 µg/ml given duringthe agingperiod did not affect the subsequent expansion growthcausedby auxin or auxin plus kinetin.
3. Actinomycin D given in thegrowth period, on the other hand,strongly inhibited the expansiongrowth of tissue slices agedin the absence of the antibiotic.
4. In the growth period, auxin or auxin plus kinetin promotedtheincorporation of uracil-2-¹⁴C into RNA fraction.
5. ActinomycinD inhibited the incorporation of ³²P orthophosphateinto ribosomalRNA during the aging period.
6. In the growth period, the incorporationof ³²P into RNA wasenhanced by auxin and was inhibited by actinomycinD, more remarkablyin ribosomal RNA than in lighter RNA.

¹A part of this paper was presented at the Conference on PlantGrowth Regulators held by the New York Academy of Sciences onMay 16, 1966.     

Ubiquitous distribution of fluorescent protein in muscles of four species and two subspecies of eel (genus <Emphasis Type="Italic">Anguilla</Emphasis>)

In this study, the localization of fluorescent protein (FP) was characterized in the muscles of four species and two subspecies of eels Anguilla anguilla, A. australis, A. bicolor bicolor (b.), A. bicolor pacifica (p.) and A. mossambica in addition to the previously reported A. japonica. The open reading frame of each eel FP was 417 bp encoding 139 amino acid residues. The deduced amino acid sequences among the four species and two subspecies exhibited 91.4–100% identity, and belonged to the fatty-acid-binding protein (FABP) family. The gene structure of eel FPs in A. japonica, A. anguilla, A. australis, A. bicolor b., A. bicolor p. and A. mossambica have four exons and three introns, and were common to that of FABP family. The apo eel FPs expressed by Escherichia coli with recombinant eel FP genes were analysed for the fluorescent properties in the presence of bilirubin. The excitation and emission spectra of holo eel FPs had the maximum wavelengths of 490–496 and 527–530 nm, respectively. The holo eel FPs indicated that the fluorescent intensities were stronger in A. japonica and A. bicolor than in A. mossambica, A. australis and A. anguilla. The comparison of amino acid sequences revealed two common substitutions in A. mossambica, A. australis and A. anguilla with weak fluorescent intensity.     

Cell elongation and metabolic turnover of the cell wall as affected by auxin and cell wall degrading enzymes

A cell wall fraction (pectic substances) of oat coleoptile segmentsfed with ¹⁴C-glucose contained more radioactivity under theeffect of auxin than did the control. When labeled segmentswere grown for 6 hr in auxin or glucanase solution the labelin the hemicellulose fraction decreased as growth increased.ß-1,3-Glucanase prepared from the culture of a fungus,Sclerotinia libertiana, induces elongation of segments of thepea stem and the oat coleoptile. Traces of cellulase and pectinmethylesterase contaminating the enzyme preparation are notresponsible for the stimulatory effect. Cellulase seemed tobe rather inhibitory and pectin methylesterase showed only aslight effect on coleoptile elongation. A possible relationshipbetween the metabolic turnover of hemicellulosic polysaccharideand cell wall extension is suggested. (Received February 5, 1968; )     

Melanoma Antigen and Transforming Gene

We summarize our recent studies on the analysis of melanoma antigen and the melanoma gene recently cloned. The melanoma antigen analyzed by syngeneic monoclonal antibodies is composed of a complex of GM3 ganglioside and protein molecules. The epitope recognized by antimelanoma cytotoxic T lymphocytes seemed to be the combinatorial determinants of GM3 and proteins, whereas the epitope for the suppressor T cells was found to be solely GM3 (NeuAc). The genomic DNA controlling the melanoma antigen was recently isolated and was found to possess transforming activity. The structure of this transforming gene is discussed based on the sequence data of the corresponding cDNA clone.     

Auxin-induced synthesis of TB-RNA in pea stems

The effect of 2,4-dichlorophenoxyacetic acid on RNA synthesisin etiolated pea internode segments was studied. Auxin stimulatedsynthesis of TB-RNA only in short period incubation, suggestingits primary importance in auxin action. The nucleotide compositionof newly synthesized TB-RNA seems to be modified under auxininfluence. (Received February 8, 1969; )     

ENZYMATIC DISSOCIATION OF NASCENT MACROCYSTS AND PARTITION OF THE LIBERATED CYTOPHAGIC GIANT CELLS IN DICTYOSTELIUM MUCOROIDES*

Nascent macrocysts of the cellular slime mold Dictyostelium mucoroides were dissociated enzymatically and the liberated cytophagic giant cells were partitioned by dextrin density gradient centrifugation. Enzymatic and cytochemical studies revealed that the primary wall is composed mainly of cellulose (β-1,4-glucan) associated with polysaccharides including hemicellulose, pectic substances and á-1,4-glucan. The buoyant density of the liberated cytophagic giant cells and peripheral cells was determined by density gradient centrifugation, and partitioning of the cells was possible due to the difference in this property. The process of macrocyst reconstitution was investigated using dissociated cells. The isolated cytophagic giant cell has a specific affinity for other cytophagic giant cells and predominantly ingests them by phagocytosis, while it retains the ability to ingest peripheral cells. The present study provides a clue for investigating the differentiation and development of sexual cells, since only the cytophagic giant cell gives rise to a zygote in macrocyst formation.     

EFFECT OF AUXIN AND ANTIAUXIN ON THE GROWTH AND RNA SYNTHESIS OF ETIOLATED PEA INTERNODE

Using etiolated Alaska pea internode segments the followingresults were obtained. An auxin, 2,4-dichlorophenoxyacetic acid, 1 mg/liter, inducedthe elongation growth of the segment and stimulated the biosynthesisof RNA, particularly of messengar RNA, in 3 hr incubation. Thesimilar stimulation of RNA synthesis and of elongation due toindole-3-acetic acid was found in 1 hr incubation. The stimulativeeffect of 2,4-dichlorophenoxyacetic acid on the elongation andon the synthesis of messenger RNA was inhibited by the additionof an antiauxin, transcinnamic acid. Significance of the auxin-inducedsynthesis of messenger RNA in producing protein responsiblefor the stress relaxation of cell wall is discussed. (Received June 13, 1967; )     

FURTHER STUDIES ON THE RNA FUNCTIONAL IN AUXIN ACTION

Avena coleoptile and a respiration-deficient mutant of yeastwhose cells are elongated by the action of auxin in the absenceof GA added were subjected to the phenol method of RNA fractionation."RNA" from the phenol layer promoted the auxin-induced expansionof Jerusalem artichoke tuber slices just as GA did, whereas"RNA" from the water layer was ineffective. The GA-like activityof the former "RNA" was reduced by treatment with RNase or alkali. No active "RNA" was extractable from a respiration-sufficientyeast strain which does not respond to auxin without GA supplemented. (Received August 19, 1964; )