A Semi-Synthetic Diet for Eri-Silkworm Raising

Hatchlings of the eri-silkworm (Philosamia cynthia ricini), one of the leaf-feeding insects, may be reared to the adult stage on an artificial diet, named as a semi-synthetic diet, which does not contain any extracts from leaves of food plants such as Ricinus communis, Aylanthus glandulosa etc., not to mention the powder of dry leaves of these plants. The composition of the present semi-synthetic diet was ‘kinako’ (a powder of parched soy bean), sucrose, dry brewer yeast, β-sitosterol, l-ascorbic acid, agar-agar, sodium dehydroacetate as an aseptic and water. Though the present semi-synthetic diet leaves room for improvement, at any rate the diet enabled 48 out of 100 hatchlings to spin their cocoons. Therefore the present (or improved) semi-synthetic diet has opened a way to make possible to rear eri-silkworms all the season with the omission of the cultivation of food plants, such as Ricinus communis, etc. In developing this diet ascorbic acid was shown to be essential for eri-silkworms, and it was also found that sucrose stimulated feeding by this insect in addition to its metabolic importance.     

Phospholipase D from Streptoverticillium cinnamoneum: protein engineering and application for phospholipid production

This review is focusing on an industrially important enzyme, phospholipase D (PLD), exhibiting both transphosphatidylation and hydrolytic activities for various phospholipids. The transphosphatidylation activity of PLD is particularly useful for converting phosphatidylcholine (PC) into other phospholipids. During the last decade, the genes coding for PLD have been identified from various species including mammals, plants, yeast, and bacteria. However, detailed basic and applied enzymological studies on PLD have been hampered by the low productivity in these organisms. Efficient production of a recombinant PLD has also been unsuccessful so far. We recently isolated and characterized the PLD gene from Streptoverticillium cinnamoneum, producing a secretory PLD. Furthermore, we constructed an overexpression system for the secretory enzyme in an active and soluble form using Streptomyces lividans as a host for transformation of the PLD gene. The Stv. cinnamoneum PLD was proven to be useful for the continuous and efficient production of phosphatidylethanolamine (PE) from phosphatidylcholine. Thus, the secretory PLD is a promising catalyst for synthesizing new phospholipids possessing various polar head groups that show versatile physiological functions and may be utilized in food and pharmaceutical industries.     

Calcium dependent action potentials in skeletal muscle fibres of a beetle larva, Xylotrupes dichotomus

The ionic requirement for generating action potentials in ventral longitudinal muscle fibers dissected from beetle larvae was examined by conventional electrophysiological techniques. Muscle fibers that generated only graded responses in physiological saline were able to generate an all-or-none action potential when the potassium permeability of the membrane was inhibited by tetraethylammonium⁺ added to the saline. The peak of the action potential thus elicited was intimately related to the external Ca⁺⁺ concentration. The action potential was blocked by Co⁺⁺ which is known as a competitive inhibitor of Ca-spikes. Neither tetrodotoxin (3 μM) nor a Na-free condition effectively blocked the generation of the action potential. Mg⁺⁺ induced a shift in the peak of the action potential; this was, however, due to the stabilizing action of Mg⁺⁺ but not due to the penetration of Mg⁺⁺ through the muscle membrane. No action potential was elicited in the muscle fiber when immersed in a Ca-free, EGTA saline even when a high concentration of either Mg⁺⁺, Na⁺, or tetraethylammonium⁺ was present. The action potential of the larval muscle fiber was thus concluded to be a Ca-spike, through the channel of which Na⁺ or Mg⁺⁺ did not penetrate.     

Mechanisms of somatic embryogenesis in cell cultures: Physiology,biochemistry, and molecular biology

Summary One of the most characteristic cell functions in plants is totipotency. Somatic embryogenesis can be regarded as a model system for the investigation of mechanisms of totipotency, because a high frequency and synchronous embryogenic system from single somatic cells has been established in carrot suspension cultures. Four phases are recognized in this process, and several molecular markers, viz. polypeptides, mRNAs, antigens against monoclonal antibodies, can be detected during the expression of totipotency, but they disappear during its loss. Four organ-specific genes have been isolated from hypocotyls and roots by differential screening. They were expressed preferentially after the globular-heart stages of embryogenesis, and were strongly suppressed by auxin. A CEM 1 gene was isolated by differential screening of embryogenic cell clusters. This gene was expressed strongly and transiently during the proglobular and globular stages. The sequence of CEM 1 was found to encode a polypeptide showing high homology to the elongation factor isolated from eucaryotic cells. Thus good progress is being made in understanding the basic mechanisms of somatic embryogenesis. Presented in the Session-in-Depth Developmental Biology of Embryogenesis at the 1991 World Congress on Cell and Tissue Culture, Anaheim, California, June 16–20, 1991.     

Birth of normal calves resulting from bovine oocytes matured, fertilized, and cultured with cumulus cells in vitro up to the blastocyst stage

Bovine oocytes matured in vitro were fertilized in high proportions (92% of matured oocytes) by sperm capacitated with Ca ionophore A23187. Eight percent of inseminated oocytes that were denuded 96 h after insemination developed to the morula stage when cultured for 6-120 h after insemination with cumulus cells from the original oocytes. Inseminated oocytes denuded 96 h after insemination developed to the blastocyst stage when cultured with or without cumulus cells or in the conditioned medium from 96 h to 168-216 h after insemination (9.0%, 8.1%, and 6.8% of inseminated oocytes respectively). Six frozen-thawed blastocysts were transferred nonsurgically to 3 recipients (2 embryos/recipient). Two of the 3 recipients became pregnant, with one delivering live twins at term. Seven fresh blastocysts were transferred nonsurgically to 6 recipients (1-2 embryos/recipient). Three of the 6 recipients became pregnant, with 2 delivering live calves.     

Meristem-specific gene expression directed by the promoter of the S-phase-specific gene,cyc07, in transgenic Arabidopsis

A genomic clone for the cyc07 gene, which is expressed specifically at the S phase during the cell cycle in synchronous cultures of periwinkle (Catharanthus roseus) cells, was isolated. Determination of the nucleotide sequence of the clone revealed that the cyc07 gene consists of seven exons separated by six introns. Genomic Southern analysis indicated that the cyc07 gene is present as a single copy per haploid genome in periwinkle. Expression of related genes was detected in a wide range of other plants. Transgenic Arabidopsis plants were generated that expressed the gene for -glucuronidase (GUS) under the control of the promoter of the cyc07 gene. The tissue-specific pattern of expression directed by the promoter was investigated by analysis of GUS activity. Histochemical tests demonstrated that 589 bp of the 5-upstream sequence of the cyc07 gene could direct specifical expression of the GUS reporter gene in meristematic tissues in transgenic plants. The spatial pattern of expression directed by the promoter was closely correlated with meristematic activity and cell proliferation, suggesting an association between the function of the cyc07 gene and cell proliferation.     

A novel approach for myocardial regeneration with educated cord blood cells cocultured with cells from brown adipose tissue

Umbilical cord blood (CB) is a promising source for regeneration therapy in humans. Recently, it was shown that CB was a source of mesenchymal stem cells as well as hematopoietic stem cells, and further that the mesenchymal stem cells could differentiate into a number of cells types of mesenchymal lineage, such as cardiomyocytes (CMs), osteocytes, chondrocytes, and fat cells. Previously, we reported that brown adipose tissue derived cells (BATDCs) differentiated into CMs and these CMs could adapt functionally to repair regions of myocardial infarction. In this study, we examined whether CB mononuclear cells (CBMNCs) could effectively differentiate into CMs by coculturing them with BATDCs and determined which population among CBMNCs differentiated into CMs. The results show that BATDCs effectively induced CBMNCs that were non-hematopoietic stem cells (HSCs) (educated CB cells: e-CBCs) into CMs in vitro. E-CBCs reconstituted infarcted myocardium more effectively than non-educated CBMNCs or CD34-positive HSCs. Moreover, we found that e-CBCs after 3 days coculturing with BATDCs induced the most effective regeneration for impaired CMs. This suggests that e-CBCs have a high potential to differentiate into CMs and that adequate timing of transplantation supports a high efficiency for CM regeneration. This strategy might be a promising therapy for human cardiac disease.     

A novel bifunctional molybdo-enzyme catalyzing both decarboxylation of indolepyruvate and oxidation of indoleacetaldehyde from a thermoacidophilic archaeon, Sulfolobus sp. strain 7

An enzyme, which catalyzes both decarboxylation of indolepyruvate and subsequent oxidation of indoleacetaldehyde into indoleacetate, was purified from a thermoacidophilic archaeon, Sulfolobus sp. strain 7. The enzyme showed a M_r of 280 kDa on gel filtration and was composed of three subunits (a, 89; b, 30; and c, 19 kDa), possibly in a stoichiometry of 2:2:2. Mo and Fe were detected. Thiamine pyrophosphate was absent. Biotin was suggested to bind to the b-subunit. The first step, the decarboxylation reaction, was specific for 2-oxoacids with an aromatic group, while in the second reaction, various aldehydes including glyceraldehyde, which is a glycolytic intermediate in the organism, were oxidized.     

The influence of blood glucose on neutrophil function in individuals without diabetes

We assessed the association of neutrophil function with glycated hemoglobin (HbA1c) levels in a Japanese general population. Participants were 809 males and females who were over 20 years old living in the Iwaki region in Aomori Prefecture located in northern Japan. Lifestyle parameters (smoking, alcohol consumption, and exercise habits), HbA1c and neutrophil function such as reactive oxygen species (ROS) production capability and phagocytic activity (PA) were measured. ROS production capability was measured before and after phagocytic stimulus to obtain basal ROS production and stimulated ROS production. Level of HbA1c had a positive correlation with basal ROS production (p=0.053), a negative correlation with stimulated ROS production (p=0.072) and PA (p=0.059) only in post‐menopausal groups, and not in pre‐menopausal groups. However, there were no correlations between levels of HbA1c and neutrophil functions in male. In conclusion, in the present study, despite the presence of diabetes, chronic hyperglycemia was found to cause an increase in daily basal ROS production of neutrophils, and increased susceptibility to infection caused by reduced neutrophilic reaction in females in their menopause. Therefore, from the oxidative point of view, strict glycemic control is necessary to prevent post‐menopausal females from developing diabetic complications in spite of the presence of diabetes.     

Binding of nonamer peptides to three HLA-B51 molecules which differ by a single amino acid substitution in the A-pocket

The interaction between 9-mer peptides and HLA-B51 molecules was investigated by quantitative peptide binding assay using RMA-S cell expressing human β2-microglobulin and HLA-B51 molecules. Of 147 chemically synthesized 9-mer peptides possessing two anchor residues corresponding to the motif of HLA-B^*5101 binding self-peptides, 27 paptides bound to HLA-B^*5101 molecules. Pro and Ala at position 2 as well as Ile at position 9 were confirmed to be main anchor residues, while Gly at position 2 as well as Val, Leu, and Met at position 9 were weak anchor residues for HLA-B^*5101. The A-pocket is suspected to have a critical role in peptide binding to MHC class I molecules because this pocket corresponds to the N-terminus of peptides and has a strong hydrogen bond formed by conserved Tyr residues. Further analysis of peptide binding to HLA-B^*5102 and B^*5103 molecules showed that a single amino acid substitution of Tyor for His at residue 171(B^*5102) and that of Gly for Trp at residue 167 (B^*5103) has a minimum effect in HLA-B51-peptide binding. Since previous studies showed that some HLA-B51 alloreactive CTL clones failed to kill the cells expressing HLA-B^*5102 or HLA-B^*5103, these results imply that the structural change of the A-pocket among HLA-B51 subtypes causes a critical conformational change of the epitope for TCR recognition rather than influences the interaction between peptides and MHC class I molecules.