Heat resistance of the eggs of a mulberry silkworm strain adapted to a subtropical climate]

The heat stability of the eggs of a polyvoltine strain of Bombyx mori occurring in the conditions of hot climate was studied. No marked differences between this strain and the moderate climate strains were found in the level of heat stability and the character of its age changes. The mechanisms of heat stability upon the diapause-less egg development are discussed.     

Biological method of determining the capacity of mulberry silkworm eggs which remain unpigmented for development]

To determine the stage of the silkworm eggs which did not acquire grey colour due to the serose membrane pigmentation and, as a result, preserved yellow colour, it is suggested to activate such eggs to parthenogenetic development of ameiotic or meiotic type. The eggs lost at the early developmental stages after activation will remain yellow, whereas those arrested at metaphase I begin to develop and acquire the dark colour on the 3rd day. Examples are given for the effective utilization of the method.     

Effect of low-dose gamma-irradiation of silkworm eggs on the development of the mulberry silkworm (Bombyx mori L.)

Chronic gamma-irradiation of an egg at a dose-rate 100, 1000 and 4000 times as high as that of the natural radiation background significantly accelerates the development of Bombyx mori L. The caterpillar development may also be stimulated by a single exposure of the egg to 2 Gy radiation. The acceleration of the caterpillar growth promotes the increase in the cocoon weight and the raw-silk mass.     

Nature of heterosis and combining ability in the silkworm

Summary The isogenic, highly heterotic parthenoclone 29, originating from a hybrid silkworm female, was transformed via unisexual reproduction (meiotic and ameiotic parthenogenesis) into four genotypical variants differing in well-known various levels of hetero zygosity and combinations of useful and harmful genes. A comparison of these changes with the heterosis level made it possible to discover that both heterosity for adaptively neutral genes (overdominance hypothesis) and the number of allelic pairs, each of them being heterozygous for a favourable, completely dominant gene (dominance hypothesis) play no decisive role in the intensity of heterosis. The level of heterosis is largely determined by the relationship between the effects of useful and harmful genes, the first falling into the category of semidominant, cumulatively acting genes which control viability. Their favourable, joint well-coordinated effects, unlike those of genes which control quantitative characters, increase in relation to the number of genes in a geometric rather than an arithmetic progression. The interaction between semilethal genes is subjected to the same regularity. The high combining ability of parthenoclone 29 variants is determined by the number and homozygosity of the useful genes.     

Fragmentation of chromatin by endogenous nucleases, accumulation of the subnucleosomal fragments with high electrophoretic mobility]

Digestion of chromatin by endogenous nucleases to nucleosomes (140-160 base pairs of DNA) is accompanied by the accumulation of subnucleosomal DNP particles with high electrophoretic mobility (20-40 base pairs of DNA). All histones associate with the 140-160 base pairs fragment. The production of subnucleosomal DNP particles does not correlate with the degradation of histone H1 and the appearance of nucleosomes lacking histone H1. Degradation of the protein in this fragment is accompanied by the appearance of free DNA. The data obtained are in agreement with the hypothesis on the origin of subnucleosomes from the nucleosomal locus preferentially associated with the non-histone proteins and on the autonomy of these loci and of the loci associated with histone H1 in the nucleosome.     

Method of electrophoretic mobility of macrophages and its use in clinical immunology]

A test of measurement of the electrophoretic mobility of macrophages (EMM) is used for detection of the product secreted by the sensitized lymphocytes after the contact with the antigen. Thus, by reduction of the macrophage mobility it is possible to assess the sensitization level of the lymphocyte population under study. This offers a possibility of using this test for the diagnosis of some infectious diseases, for provisional diagnosis of malignant growth, and also of destructive affections of the nervous system. The EMM test finds wide application in the determination of compatibility of donor's and the recipient's tissues before the transplantation, and also to assess the efficacy of immunodepressive therapy.     

Beta-fructofuranosidase genes of the silkworm, Bombyx mori: insights into enzymatic adaptation of B. mori to toxic alkaloids in mulberry latex

Mulberry latex contains extremely high concentrations of alkaloidal sugar mimic glycosidase inhibitors, such as 1,4-dideoxy-1,4-imino-D-arabinitol (D-AB1) and 1-deoxynojirimycin (DNJ). Although these compounds do not harm the silkworm, Bombyx mori, a mulberry specialist, they are highly toxic to insects that do not normally feed on mulberry leaves. D-AB1 and DNJ are strong inhibitors of alpha-glucosidases (EC 3.2.1.20); however, they do not affect the activity of beta-fructofuranosidases (EC 3.2.1.26). Although alpha-glucosidase genes are found in a wide range of organisms, beta-fructofuranosidase genes have not been identified in any animals so far. In this study, we report the identification and characterization of beta-fructofuranosidase genes (BmSuc1 and BmSuc2) from B. mori. The BmSuc1 gene was highly expressed in the midgut and silk gland, whereas the expression of BmSuc2 gene was not detected. BmSuc1 encodes a functional beta-fructofuranosidase, whose enzymatic activity was not inhibited by DNJ or D-AB1. We also showed that BmSUC1 protein localized within the midgut goblet cell cavities. Collectively, our data clearly demonstrated that BmSuc1 serves as a sugar-digesting enzyme in the silkworm physiology. This anomalous presence of the beta-fructofuranosidase gene in the B. mori genome may partly explain why the silkworm can circumvent the mulberry's defense system.     

Changes in the electrophoretic mobility of erythrocytes by the action of low-intensity pulse magnetic field

It has been shown that the exposure of "intact" rats and human blood to low-intensity pulse magnetic field leads to similar changes in the electrophoretic mobility of erythrocytes, which may be connected with the modification of the spectrum of their membrane proteins.     

Pathways of carbohydrate metabolism in the eggs of the silkworm,Bombyx mori

Pathways of carbohydrate metabolism in the diapausing eggs of the silkworm, Bombyx mori, were estimated by use of glucose-1-¹⁴C and glucose-6-¹⁴C. The relative rates of glycolytic pathway and that of pentose-phosphate cycle are calculated to be 62% and 38%, respectively. The contribution to energy by lactate fermentation is calculated to be 5.7% of the total during the first 3 days, 2.2% from day 3 to day 5, and 1.1% from day 5 to day 7. The relatively high proportion of anaerobic energy formation is responsible for the accumulation of sorbitol and glycerol in Bombyx eggs.     

Phosphorylation-mediated changes in the electrophoretic mobility of CD5 molecules.

This work shows that tumor promoter agents (TPA) induce the post-translational modification of the human lymphocyte surface CD5 antigen (Tp67) in several cellular types. Treatment of [32P]orthophosphate- and [35S]cysteine-labeled normal and lymphoblastoid T and B cells with active tumor promoters induced the rapid, transitory and dose-dependent appearance of hyperphosphorylated CD5 forms with higher apparent molecular masses. These changes in the electrophoretic mobility of CD5 molecules were independent of RNA and protein synthesis, as well as of differences in neuraminic acid content. The inhibition of the TPA-mediated changes by protein kinase C inhibitors (staurosporine and 1-(5-isoquinolylsulfonyl)-2-methylpiperazine) indicated its protein-kinase-C-mediated nature. Phosphatase digestion of CD5 immunoprecipitates reverted the TPA-mediated mobility changes showing its dependence on phosphorylation. Neuraminidase digestion of intact cells revealed that the target of the TPA effects are surface-expressed CD5 molecules. In conclusion, we suggest that the heterogeneity in the electrophoretic mobility induced by TPA could reflect some structural and/or functional differences within CD5 molecules.     

Carnosine prevents the glycation-induced changes in electrophoretic mobility of aspartate aminotransferase

Carbohydrate-derived aldehydes cause irreversible loss of protein function via glycation. We previously observed that glyceraldehyde 3-phosphate (Glyc3P) abolishes the enzyme activity of cardiac aspartate aminotransferase (cAAT). We also examined the protective effects of carnosine against Glyc3P-induced loss of enzyme activity. The present study looked at carnosine's prevention of Glyc3P-induced change in protein structure. Purified cAAT (2 mg protein/mL) was incubated with various concentrations of carnosine (1-20 mM) in the presence of Glyc3P (500 microM) for 4 days at 37 degrees C. Following incubation, samples were analyzed by SDS-polyacrylamide gel electrophoresis. Carnosine showed prevention of protein modification at carnosine-to-Glyc3P ratios of 10:1 or greater. There was a progressive loss of the unmodified cAAT protein band as Glyc3P concentration was increased. Additionally, the gel position of the Glyc3P-modified cAAT protein varied over time. The apparent molecular weight (MWapp) of the Glyc3P-modified cAAT protein that formed after 1 day at 37 degrees C (500 microM) was greater than its MWapp after 2 days, suggesting that a chemical rearrangement of the initial adduct occurs. These observations support the hypothesis that carnosine is an antiglycation agent and that its mechanism of action involves prevention of protein modification.     

Red fluorescent protein in the digestive juice of the silkworm larvae fed on host-plant mulberry leaves

A red fluorescent protein is present in the digestive juice of silkworm larvae when they are raised on fresh mulberry leaves. It is an antiviral substance and is absent from insects reared on artificial diet. The biosynthesis of this red fluorescent protein has been investigatedin vitro, and shown to require chlorophyll-a and chlorophyllase for its formation. The resulting chlorophyllide-a then reacts with an insect protein to give the final product.

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La Protéine Fluorescente Rouge dans le Suc Digestif des Larves de Ver à Soie Alimentées Avec des Feuilles de M?rier

Résumé Les larves de ver à soie élevées artificiellement étaient plus sensibles à l'attaque de virus par voie orale que les larves élevées sur le m?rier. La raison était apparemment l'absence d'une substance anti-virale (la protéine fluorescente rouge) dans le suc digestif. La protéine fluorescente rouge (RFP) a été produite en ajoutant l'homogénat de chloroplastes de feuilles vertes à la ration préparée. On a étudiéin vitro la biosynthèse de la RFP. Elle pouvait être synthétisée en éprouvette. Il faut noter que l'addition de la fraction soluble dans l'acétone ou de la fraction insoluble dans l'acétone des chloroplastes à l'homogénat de mésentéron des larves ne produisàit pas de RFP, tandis que l'addition de ces deux fractions produisait de la RFP. De la fraction soluble dans l'acétone, on a isolé de la chlorophylle-a à l'état pur qui est l'un des principes actifs dans le système biosynthétique de la RFP, et, de la fraction insoluble, de la chlorophyllase, autre principe actif. Un autre principe actif isolé du mésentéron larvaire s'est avéré être une protéine. Le mécanisme de la biosynthèse est en deux étapes: d'abord une réaction enzymatique entre la chlorophylle-a et la chlorophyllase à pH 10,4 puis une réaction de la chlorophyllide-a, produite pendant la première étape, et de la protéine du mésentéron larvaire environ à pH 7. Comme on le sait, la chlorophylle elle-même est photolabile, et la chlorophyllase thermolabile. Des feuilles vertes et fra?ches sont donc nécessaires à la production de la substance anti-virale RFP dans le suc digestif des larves de ver à soie.

     

Real-time detection of changes in the electrophoretic mobility of a single cell induced by hyperosmotic stress

Living cells survive environmentally stressful conditions by initiating a stress response. We monitored changes in the electrophoretic mobility (EPM) of single, optically trapped yeast cells under hyperosmotic stress conditions using optical tweezers combined with a position detector. We studied the dynamics of the EPM stress response for cells at different phases of the cell cycle.     

The toxicity of certain herbicides to hens' eggs assessed by the egg-injection technique

Twenty-five herbicides have been tested for their toxicity to hen embryos at various concentrations, using an egg-injection technique. Paraquat was the most toxic, giving a complete kill at a concentration in the egg of 0.3 ppm; two other compounds related to it were almost completely lethal at 10 ppm. Of the other compounds, seventeen had little or no effect at 50 ppm and of these eight had none at 100 ppm. Except for feather blanching, caused by some of the substituted phenoxy-acids, no teratogenic effects were found.