Limited feeding of nitrate during culture of Nannochloris sp. UTEX LB1999 for intracellular lipid and triglyceride accumulation was investigated with the aim of obtaining cells superior for liquefaction into a fuel oil. The intracellular lipid contents and the percentage of triglycerides in the lipids of cells grown in a nitrogen-limited medium (0.9 mM KNO3) were 1.3 times as high as those grown in a modified NORO medium containing 2.0-9.9 mM KNO3. However, the cell concentration was too low for the practical production of fuel oil by high-pressure liquefaction of the cell mass. A single feeding of 0.9 mM nitrate after nitrate depletion during cultivation in a nitrate-limited medium increased the cell concentration to twice that obtained without such feeding, and the lipid content was maintained at a high level. The timing of nitrate feeding, i.e., whether it was given during the log phase (before nitrate depletion), the constant growth phase (just after the depletion), or the stationary phase (after the depletion), had negligible effect on the intracellular lipid content and percentage of triglycerides in the lipids. When 0.9 mM nitrate was intermittently fed ten times during the log phase in addition to the initial nitrate feed (0.9 mM), the cell concentration reached almost the same (2.16 g/l) and the intracellular lipid content and the percentage of triglycerides in the lipids increased from 31.0 to 50.9% and 26.0 to 47.6%, respectively, compared with those of cells cultured in a modified NORO medium containing 9.9 mM KNO3 without additional nitrate feeding.

No abstract

We investigated the effect of fibronectin on epithelial migration onto the stroma in cultured rabbit cornea. Rabbit plasma fibronectin was purified by affinity chromatography using gelatin-Sepharose 4B, and its purity was confirmed by SDS polyacrylamide slab gel electrophoresis. Antibody against rabbit plasma fibronectin raised in guinea pigs formed a single precipitin line against rabbit plasma and purified rabbit plasma fibronectin by Ouchterlony double diffusion test. When rabbit cornea was cut into small blocks and cultured in TCM-199 medium alone, corneal epithelial cells began to migrate on the cut edge of the corneal stroma. The addition of purified rabbit plasma fibronectin to the culture medium significantly enhanced epithelial migration. The degree of enhancement depended on the amount of fibronectin added. When guinea pig IgG anti-rabbit plasma fibronectin was added, epithelial migration was significantly inhibited when compared with that in control cultured corneal blocks. The results demonstrate that fibronectin promotes epithelial migration in the cornea and thus plays an important role in corneal wound healing.

Novel antimicrobial peptides (AMP), designated Fa-AMP1 and Fa-AMP2, were purified from the seeds of buckwheat (Fagopyrum esculentum Moench.) by gel filtration on Sephadex G75, ion-exchange HPLC on SP COSMOGEL, and reverse-phase HPLC. They were basic peptides having isoelectric points of over 10. Fa-AMP1 and Fa-AMP2 had molecular masses of 3,879 Da and 3,906 Da on MALDI-TOF MS analysis, and their extinction coefficients in 1% aqueous solutions at 280 nm were 42.8 and 38.9, respectively. Half of all amino acid residues of Fa-AMP1 and Fa-AMP2 were cysteine and glycine, and they had continuous sequences of cysteine and glycine. The concentrations of peptides required for 50% inhibition (IC50) of the growth of plant pathogenic fungi, and Gram-positive and -negative bacteria were 11 to 36 microg/ml. The structural and antimicrobial characteristics of Fa-AMPs indicated that they are a novel type of antimicrobial peptides belonging to a plant defensin family.

Using peroxidase‐antiperoxidase (PAP) method, carcinoembryonic antigen (CEA) was demonstrated in conventionally processed colorectal cancer tissues. A new immunohistochemical grading for colorectal cancers based on the mode of the localization was made in an attempt to clarify the factors responsible for elevation of plasma CEA levels in colorectal cancer patients. Most of the patients with well differentiated adenocarcinoma, in which CEA was densely distributed along the apical surface but only rarely present along the basolateral surfaces of the carcinoma cells, had very low levels of plasma CEA, whereas all patients showing CEA distribution in the stroma as well as over the entire surfaces of the cancer cells and their cytoplasm showed high plasma CEA levels. In addition, there was a good correlation between the grading and presence of the blood vessel and lymphatic invasions. Thus, the appearance of CEA in the surrounding stroma, due to abnormal distribution of CEA on the basolateral plasma membrane of cancer cells, may play a significant role in the elevation of plasma CEA levels in colorectal cancer patients.