Isolation of yeast candidates for efficient sophorolipids production: their production potentials associate to their lineage

Eleven biosurfactant-producing strains were newly isolated from environmental samples using a drop-collapse assay and thin-layer chromatography (TLC). According to the TLC analysis, the separation patterns of the glycolipid spots of nine dominant strains corresponded to that of the sophorolipids produced by a Starmerella bombicola type strain. The retention factor values of the spot patterns of two strains were less than those of the others. Two representative major products were purified, and their molecular structures were determined. The major products were identified as diacetylated lactonic and acidic sophorolipids. The fatty acid moieties of both compounds were estimated to be 17-hydroxymethyl hexadecenoic acid. The amounts of glycolipids ranged from 5.0 to 22.9 g/L after 4 d of cultivation. According to a phylogenetic analysis, the strains were identified as Starmerella bombicola and Candida floricola.     

In vitro formation of the Merkel cell‐neurite complex in embryonic mouse whiskers using organotypic co‐cultures

A Merkel cell‐neurite complex is a touch receptor composed of specialized epithelial cells named Merkel cells and peripheral sensory nerves in the skin. Merkel cells are found in touch‐sensitive skin components including whisker follicles. The nerve fibers that innervate Merkel cells of a whisker follicle extend from the maxillary branch of the trigeminal ganglion. Whiskers as a sensory organ attribute to the complicated architecture of the Merkel cell‐neurite complex, and therefore it is intriguing how the structure is formed. However, observing the dynamic process of the formation of a Merkel cell‐neurite complex in whiskers during embryonic development is still difficult. In this study, we tried to develop an organotypic co‐culture method of a whisker pad and a trigeminal ganglion explant to form the Merkel cell‐neurite complex in vitro. We initially developed two distinct culture methods of a single whisker row and a trigeminal ganglion explant, and then combined them. By dissecting and cultivating a single row from a whisker pad, the morphogenesis of whisker follicles could be observed under a microscope. After the co‐cultivation of the whisker row with a trigeminal ganglion explant, a Merkel cell‐neurite complex composed of Merkel cells, which were positive for both cytokeratin 8 and SOX2, Neurofilament‐H‐positive trigeminal nerve fibers and Schwann cells expressing Nestin, SOX2 and SOX10 was observed via immunohistochemical analyses. These results suggest that the process for the formation of a Merkel cell‐neurite complex can be observed under a microscope using our organotypic co‐culture method.     

Impaired expression of high affinity interleukin 2 receptor on activated lymphocytes from patients with systemic lupus erythematosus

Peripheral lymphocytes stimulated with phytohemagglutinin (PHA-blasts) were examined for their responsiveness to exogenous interleukin 2 (IL-2). The proliferative response of PHA-blasts to IL-2 was significantly lower in patients with systemic lupus erythematosus (SLE) than in normal subjects. To clarify the reason for this defect, the expression of IL-2 receptor (IL-2R) on PHA-blasts was investigated using anti-Tac antibody and purified IL-2. Cytofluorometric analysis showed no statistical differences in the Tac positivity of PHA-blasts among normal subjects and patients with active and inactive SLE. Scatchard analysis using 125I-labeled anti-Tac monoclonal antibody revealed that the number of Tac epitopes on PHA-blasts was also not different among them. Next, the affinity of IL-2R expressed on PHA-blasts was determined by Scatchard analysis using radiolabeled IL-2 as a ligand. The number of high affinity IL-2R on the PHA-blasts was significantly decreased in patients with active and inactive SLE, as compared with normal subjects. The responsiveness of PHA-blasts to exogenous IL-2 was well correlated to the number of high affinity IL-2R, but not to the number of Tac epitopes or total IL-2R. Inasmuch as high affinity components of IL-2R are functionally active, the defective expression of high affinity IL-2R may be responsible for the T cell dysfunctions in SLE.     

Trophic status of Tilitso,a high altitude Himalayan lake

The trophic status and water quality of Lake Tilitso (4920 m above sea level) in a high altitude region in central Nepal were surveyed in September, 1984. The lake is rather large with a maximum depth of 95 m and a surface area of 10.2 km². The lake water was turbid due to glacier silt and the euphotic layer was only 5 m deep. The nutrient concentration was very low with total phosphorus concentration 1–6 μg l⁻¹, and DTN concentration 0.10–0.22 mg l⁻¹. The phytoplankton biomass and chlorophyll-a concentration were also low. Primary production was estimated to be about 12 mg C m⁻² d⁻¹. The concentrations of particulate matter and most cations and bacterial number were higher in the epilimnion than in the hypolimnion. The trophic status of this lake was estimated as ultraoligotrophic.     

Molecular cloning and nucleotide sequence of cDNA encoding hydroxyindole O-methyltransferase of bovine pineal glands

Messenger RNA for hydroxyindole O-methyltransferase (EC 2.1.1.4) was partially purified from poly(A)+ RNA isolated from bovine pineal glands by sucrose density gradient centrifugation. The enriched mRNA was used to prepare a cDNA library by use of expression vector lambda gt11. The library was screened with monoclonal antibodies to the enzyme, and three cDNA clones were isolated. These cloned cDNAs cross-hybridized with one another, and their fusion proteins reacted to the monoclonal antibodies with different binding properties. Hydroxyindole O-methyltransferase enzymatic activity was demonstrated in the bacteria lysate infected with lambda HIOMT-A16, the clone that contained the longest insert. An almost full-length cDNA clone was isolated from lambda gt10 cDNA library by use of the lambda HIOMT-A16 cDNA as a probe. The primary structure of hydroxyindole O-methyltransferase was determined by analyzing the nucleotide sequence of the cDNAs. It consisted of 1939 nucleotides including a 1050-nucleotide region coding for 350 amino acids. RNA transfer blot analysis indicated that mRNA encoding hydroxyindole O-methyltransferase was present only in the pineal gland and not in the brain, retina, and liver of cow.     

Composition of muscle fibers in the slow loris,using the m. biceps brachii as an example

Histological examination of the skeletal muscle of the slow loris, which displays slow movement and locomotion among the prosimians, revealed a muscle fiber composition which differed from the general condition in mammals. Three types of muscle fiber cells were therefore analyzed quantitatively in order to elucidate their specificity. The skeletal muscle of the limbs of the slow loris was predominantly composed of red muscle fibers (type I) showing persistent tonic contraction.