Incorporation of [14C]cinnamate into hydrolase-resistant components of the primary cell wall of spinach

[¹⁴C]Cinnamate was taken up very rapidly by cultured spinach cells and completely incorporated into low-MW conjugates within 20 min. The ¹⁴C-labelled products were similar whether the [¹⁴C]cinnamate was supplied continuously over a period of hours via a peristaltic pump or instantaneously. Radioactivity was slowly recruited from the low-MW pool into aromatic components of the cell-wall fraction. Saponification of the radioactive wall fraction yielded, in addition to radioactive ferulate and p-coumarate, large amounts of ethyl acetate-soluble radioactive material with the properties of oxidatively coupled phenols. The coupled material was associated with the most highly ‘Driselase’-resistant fractions of the cell wall. In contrast, ‘Driselase’ released most of the wall's ferulate and p-coumarate on disaccharide fragments. It is suggested that the oxidatively coupled phenols are formed from simpler phenols by peroxidase and that they cross-link the polysaccharides to which they are attached, making these polysaccharides relatively ‘Driselase’-resistant.     

Lack of invaginations of the plasma membrane during budding and cell division of Saccharomyces cerevisiae and Schizosaccharomyces pombe

Abstract The plasma membrane of Saccharomyces cerevisiae and Schizosaccharomyces pombe in stationary phase had abundant invaginations. A round uninvaginated area emerged before budding when S. cerevisiae cells were given fresh medium. Middle-sized buds had some invaginations, whereas the neck between the bud and mother had very few. S. pombe which has neither the neck nor the predetermined position to divide had no uninvaginated ring area even in long cells during elongation in fresh medium. However, an uninvaginated ring area emerged as the earliest noticeable stage of cytokinesis. The uninvaginated state of the plasma membrane appeared to be correlated with budding and cell division.     

Interactions between immature porcine Leydig and Sertoli cells in vitro

Summary Interactions between Leydig and Sertoli cells, as well as a stimulatory effect of FSH on Leydig cell activity, have been reported in many studies. In order to investigate these interactions, the ultrastructure of immature pig Leydig cells under different culture conditions has been studied. When cultured alone in a chemically defined medium, there is a marked regression of the Leydig cell smooth endoplasmic reticulum and a swelling of the mitochondria. Addition of FSH or hCG does not prevent these phenomena. Co-culturing of Leydig cells with Sertoli cells from the same animal maintains the smooth endoplasmic reticulum at the level seen in vivo and in freshly isolated Leydig cells. The addition of FSH to the co-culture stimulates its development and increases Leydig cell activity, as assessed by an increase in hCG binding sites and an increased steroidogenic response to hCG. These results suggest that Sertoli cells exert a trophic effect on Leydig cells, and that the stimulatory effect of FSH on Leydig cell function is mediated via the Sertoli cells. These results reinforce the concept of a local regulatory control of Leydig cell steroidogenesis.Post-Doctoral fellow supported by CIRIT, Generalitat de Catalunya, Spain     

Isolation and complete nucleotide sequence of the gene for bovine parathyroid hormone

The structure of the bovine parathyroid hormone (PTH) gene has been analyzed by Southern blot hybridization of genomic DNA and by nucleotide sequence analysis of a cloned PTH gene. In the Southern analysis, several restriction enzymes produced single fragments that hybridized to PTH cDNA suggesting that there is a single bovine PTH gene. The restriction map of the cloned gene is the same as that determined by Southern blot analysis of bovine DNA. The sequence of 3154 bp of the cloned gene has been determined including 510 bp and 139 bp in the 5' and 3' flanking regions, respectively. The gene contains two introns which separate three exons that code primarily for: (i) the 5' untranslated region, (ii) the pre-sequence of preProPTH, and (iii) PTH and the 3' untranslated region. The gene contains 68% A + T and unusually long stretches of 100- to 150-bp sequences containing alternating A and T nucleotides in the 5' flanking region and intron A. The 5' flanking region contains two TATA sequences, both of which appear to be functional as determined by S1 nuclease mapping. Compared to the rat and human genes, the locations of the introns are identical but the sizes differ. Comparable human and bovine sequences in the flanking regions and introns are about 80% homologous.     

Synchronization of drosophila cells in culture

Summary We synchronized Drosophila cell lines (Schneider's line 2 and K_c) by allowing the cells to enter the stationary phase of growth and then diluting them into fresh culture medium. The cells of both cell lines entered S phase, after an 8- to 14-hr delay, in a state of partial synchrony; 60 to 80% of the cell population accumulated in S phase. Measurements of the cell cycle phases of Schneider's line 2 cells (S=14 to 16 hr; G₂=6 to 8 hr; M=0.4 hr) were similar to those of K_c cells. This work was performed under the auspices of the U.S. Energy Research and Development Administration. A.R. was supported by an NIH post-doctoral fellowship, No. CA01060.     

Suppression of lymphocyte proliferation by a nonspecific factor produced by the burkitt lymphoma-derived lymphoblast cell line

Summary The DAUDI lymphoblast cell line derived from a patient with Burkitt lymphoma was obtained from two different sources. One of these (DAUDI-I) produced a factor that inhibited lymphocyte proliferation in both human and mouse regardless of the stimulator, i.e. allogeneic lymphocytes or mitogens. Glutaraldehyde treatment eliminated production of the factor and demonstrated that DAUDI-I was capable of stimulating normal lymphocytes in MLR. A second DAUDI cell line (DAUDI-S) did not produce the inhibitory factor and was capable of MLR stimulation. Supported by the Children's Leukemia Foundation of Michigan, NIH Grants AI 11013 and AI 11335, and the Kidney Foundation of Michigan.     

STUDIES ON THE AUTECOLOGY OF THE MARINE DIATOM THALASSIOSIRA NORDENSKIOELDII. II. THE INFLUENCE OF CELL SIZE ON GROWTH RATE,AND CARBON,NITROGEN, CHLOROPHYLL a AND SILICA CONTENT1

The effect of cell size on growth rates and some cellular contents of Thalassiosira nordenskioeldii Cleve has been measured at 0 and 10 C. At 0 C the growth rate did not vary with cell size. The 2 smallest clones at this temperature had reduced growth rates because of the induction of sexuality in that size range. The clones grown at 10 C showed a significant negative relationship between growth rate and valve diameter with the cell surface area/volume ratio positively related to growth rate. At both temperatures the smaller cells had proportionately more carbon and nitrogen/unit cell volume. The amount of chlorophyll a and silica/unit cell surface area increased with increasing cell surface area at both 0 and 10 C. Both the C/N and C/chl a ratios showed no significant change with cell size at either temperature but there was a significant increase in the C/chl a ratio at 0 C. The C/Si ratio decreased with increasing cell size at both 0 and 10 C.     

Immunological relationships and a genetic interpretation of major and minor acidic proteins in human parotid saliva

Isoelectric focusing was performed on parotid salivas selected for their electrophoretic phenotypes of proline-rich acidic salivary proteins. Fractions encompassing narrow pH regions were pooled and examined by polyacrylamide gel electrophoresis. Isoelectric focusing yielded partial purification of major and minor acidic proline-rich proteins which were subsequently compared by immunoelectrophoresis and double immunodiffusion against goat anti-human parotid saliva. Cross-reactivity without spurring between all fractions containing major Pr proteins in both immunoelectrophoresis and double immunodiffusion suggests that these proteins are immunologically very similar or identical.This study was supported in part by an award from the American Cancer Society Institutional Grant IN-88F to Fels Research Institute.