Somatic Embryogenesis in Cultured Carrot Cells

Somatic embryogenesis in cultured plant cells is an ideal system for investigating the whole process of differentiation and development from single cells to whole plants, and especially the molecular mechanism of expression of totipotency. This review reports recent progress the studies on somatic embryogenesis.     

Structure of the “Peroxy-Y Base” from Liver tRNA<Superscript>Phe</Superscript>

WE wish to report that reconstituted sperm whale myoglobin prepared by the method of Breslow¹ (except that pH 2 was found sufficient to remove all the haem) (I) crystallizes² in a different habit from those prepared by the method of Rossi-Fanelli et al.³ (II) using haemin of Sigma lot 77B-0220 and our own ⁵⁷Fe photoporphyrin preparation and the native myoglobin (III). Although all three form type A³ monoclinic prisms, the best developed plane is [001] for II and III, it is [100] for I. There seems to be great interest in reconstituted haemoproteins^4,5, so it is important that crystallization habit may be a sensitive test for subtle changes in protein structures.     

Alicyclic acid metabolism in plants 3. Fate of 14C-shikimate and 14C-quinate in mung bean plants

Young mung bean plants (Phaseolus mungo) were exposed to ¹⁴C-shikimateor ¹⁴C-quinate in the light. After 8 or 23.5 hr of incubationat 25°C, radioactivities in free and bound amino acids,organic acids, soluble and insoluble carbohydrates, ether-solublefraction and lignin were determined. Shikimic and quinic acidswere separated by the combined use of paper-chromatography andcolumn chromatography. Specific activity of formed quinate orshikimate was only slightly lower than that of fed shikimateor quinate. Specific activities of phenylalanine, tyrosine andbound tryptophan were high as compared with those of non-aromaticamino acids. Discussion is focused upon the interconversionbetween shikimate and quinate, and their roles in the biosynthesisof aromatic amino acids. (Received November 15, 1968; )     

Potential fragmentation and loss of thermal habitats for charrs in the Japanese archipelago due to climatic warming

1. The upper thermal limits of the present distributions of two charr species, Dolly Varden, Salvelinus malma , and white-spotted charr, S. leucomaenis , in streams of the Japanese archipelago were examined using groundwater temperature as an index of thermal condition. The lower limits of the altitudinal distributions of Dolly Varden and white-spotted charr were delineated, respectively, by 8 and 16 °C groundwater isotherms.
2. The potential impact of future climatic warming on the geographical distribution, habitat extent and population fragmentation of each species was predicted at both the full archipelago and individual catchment levels.
3. For Dolly Varden, analysis at the full archipelago level indicated a loss of 27.6, 67.2, 79.6 and 89.6% of the current geographical range, respectively, for a 1, 2, 3 and 4 °C increase in mean annual air temperature. The present distribution area of white-spotted charr would likewise reduce by 4.1, 20.5, 33.8 and 45.6%, respectively.
4. Based on the analyses of three individual catchments, one for Dolly Varden and two for white-spotted charr, the lower habitat boundaries for the two charr species could be expected to rise increasingly to higher elevations in each catchment as warming proceeded. As a consequence, there would be large reductions in mean habitat area, with increasing habitat fragmentation followed by localized extinctions of the two species.     

Primers Designed for Amplification of Echinococcus multilocularis DNA Amplify the DNA of Encephalitozoon-Like Spores in the Polymerase Chain Reaction

ABSTRACT. Microsporidian spores were developed from cells which were grown in vitro from a human liver lesion which was due to larval Echinococcus multilocularis . The microsporidian spores developed in the same fashion as an Encephalitozoon cuniculi . The Encephalitozoon -like spores were completely separated on Percoll gradients. The separated spores contained DNA capable of amplification by two different primer sets designed for the polymerase chain reaction (PCR) of E. multilocularis DNA. However, the cell DNA from which microsporidium developed was thoroughly insensitive to the PCR using the E. multilocularis primer sets. The results strongly suggested that Encephalitozoon should be taken into consideration, when DNA isolated from larval E. multilocularis is analyzed.     

Antimelanoma Activity of Chloroquine,an Antimalarial Agent With High Affinity for Melanin

The antimalarial agent chloroquine is known for high affinity for melanin. This 4-aminoquinoline derivative was examined for anti-melanoma activity and uptake into melanoma cells. Chloroquine inhibited growth of cultured melanoma cells; the effect was much greater to a moderately pigmented cell line HMV-II than to a nonpigmented HMV-I. Treatment with chloroquine at a dose of 62 mg/kg i.p. for 12 days prolonged by 71% the life span of mice bearing B16 melanoma, while 24-day treatment at 31 mg/kg resulted in a 81% increase in life span. HMV-II cells showed a two-fold increase in up-take of chloroquine as compared with HMV-I cells. Chloroquine, 24 hr after administration to mice implanted s.c. with B16 melanoma, was selectively accumulated in the pigmented tissues, melanoma and eyes. Other nonpigmented tissues such as the liver, lung, and kidney showed rapid uptake (within 1 hr) and release. These results suggest that chloroquine is toxic to pigmented melanoma cells, the process being partly mediated by binding to melanin     

Potential fragmentation and loss of thermal habitats for charrs in the Japanese archipelago due to climatic warming

1. The upper thermal limits of the present distributions of two charr species, Dolly Varden, Salvelinus malma , and white-spotted charr, S. leucomaenis , in streams of the Japanese archipelago were examined using groundwater temperature as an index of thermal condition. The lower limits of the altitudinal distributions of Dolly Varden and white-spotted charr were delineated, respectively, by 8 and 16 °C groundwater isotherms.
2. The potential impact of future climatic warming on the geographical distribution, habitat extent and population fragmentation of each species was predicted at both the full archipelago and individual catchment levels.
3. For Dolly Varden, analysis at the full archipelago level indicated a loss of 27.6, 67.2, 79.6 and 89.6% of the current geographical range, respectively, for a 1, 2, 3 and 4 °C increase in mean annual air temperature. The present distribution area of white-spotted charr would likewise reduce by 4.1, 20.5, 33.8 and 45.6%, respectively.
4. Based on the analyses of three individual catchments, one for Dolly Varden and two for white-spotted charr, the lower habitat boundaries for the two charr species could be expected to rise increasingly to higher elevations in each catchment as warming proceeded. As a consequence, there would be large reductions in mean habitat area, with increasing habitat fragmentation followed by localized extinctions of the two species.     

The Fate of L-Tyrosine-UL−14C in Shoot-Forming Tobacco Callus

Tobacco callus fed L-tyrosine-UL^?14C was sampled at 3-day intervals for 15 days, homogenized and studied with respect to distribution of incorporated radioactivity. The supernatant obtained by centrifuging of the homogenates at 270 g contained the bulk of the radioactivity although significant activity was also detected in the pellet. Sucrose density gradient centrifugation of the supernatant showed over 90% of the recovered label to be associated with a fraction designated as “less dense than mitochondria”, with the remainder being found in the fraction identified as “mitochondria”. During tissue culture, virtually all of the radioactivity in the fraction “less dense than mitochondria” was recovered in the supernatant obtained by centrifugation at 100,000 g. From 4 to 18% of the labeling in the 100,000 g supernatant fraction was attributable to tyrosine-containing protein, and the rest to free tyrosine and unidentified anionic constituents. The highest proportions of radio-activity in the 270 g pellet were associated with substances extractable with NaCl, pronase, 4.6 N NaOH, and acetolyzing reagent. Low but substantial labeling characterized the extracts obtained with Triton X-100 and 1 N NaOH. The final unextractable residue contained 20% of the 270 g pellet radioactivity.     

Indispensability of Iron-bound Chick Transferrin for Chick Myogenesis in Vitro

Myotrophic activity of highly purified chick transferrins (Tfs) to chick primary myogenic cells has been studied in a culture medium containing horse serum. Iron-binding to Tfs is indispensable for the activity. The removal of iron from Tfs gives rise to a complete loss of the activity and it is restored by iron-rebinding depending on the amount of bound iron. This result, combined with other physicochemical and immunological data, strongly, confirms that the myotrophic activity is exerted by the Tfs themselves, not by a contaminating material(s). It has been found that culture medium containing horse Tf which seems inadequate for the study of the biological effects of Tfs is, however, suitable for studies on chick Tfs, since horse Tf is inactive in promoting chick myogenesis. Terminal sialic acid residues are unrelated to myotrophic activity since Tfs with different numbers of residues (0, 1, and 2 moles/Tf molecule) are comprable in their activities. The mechanism of Tf action on cells and contradictions among previous papers as to the requirement of Tf for cell growth have been discussed from the viewpoint of an iron-donor with class-specificity.     

Transferrin Receptor on Chick Fibroblast Cell Surface and the Binding Affinity in Relevance to the Growth Promoting Activity of Transferrin

We examined the transferrin (Tf) receptor of chick skin fibroblasts using chick ¹²⁵I-Tf. When the cells were incubated with ¹²⁵I-Tf on ice, most of the cell-associated ¹²⁵I-Tf was found on the cell surface; on the other hand, a large part of it was located inside the cells when incubated at 37°C. By equilibrium binding assay, the number of Tf receptors per cell was determined as 6.7 × 10³. Dissociation constant was estimated to be 2.6 × 10⁻⁸ M.
The binding of ¹²⁵I-Tf was competitively inhibited by the addition of chick unlabeled Tf. Weaker inhibition was observed when bovine Tf was used as a competitor. Horse Tf had no effect on the binding of chick Tf. This agrees well qualitatively with chick cell growth-promoting activites of these Tfs.
Removal of Fe from Tf affected the affinity for its receptors. About 5- to 10-fold higher concentrations of chick apo–Tf was needed to achieve the same degree of inhibition of ¹²⁵I-Tf binding as that made by chick Fe-Tf.