Plant regeneration from isolated microspore cultures of Chinese cabbage (Brassica campestris spp. pekinensis)

Isolated microspores of Chinese cabbage (Brassica campestris ssp. pekinensis) were incubated in modified NN medium containing 10% sucrose in darkness at 33°C for one day followed by culture at 25°C. After 14 days of culture, microspores developed into embryos ranging from globular to cotyledonary stage. Plants were regenerated after transfer of embryos to medium containing 3% sucrose and no plant growth regulators.Abbreviations NN Nitsch and Nitsch - MS Murashige and Skoog - NAA naphthaleneacetic acid - BA 6-benzylaminopurine     

3(20)alpha-hydroxysteroid dehydrogenase activity of monkey liver indanol dehydrogenase

Homogeneous indanol dehydrogenase from monkey liver catalyzed the reversible conversion of 3 alpha- or 20 alpha-hydroxy groups of several bile acids and 5 beta-pregnanes to the corresponding 3- or 20-ketosteroids. The kcat values for the steroids determined at pH 7.4 were low, but the kcat/Km values for the 3-ketosteroids were comparable to or exceeded those for 1-indanol and xenobiotic carbonyl substrates. The enzyme transferred the 4-pro-R-hydrogen atom of NADPH to the 3 beta- or 20 beta-face of the ketosteroid substrate. Competitive inhibition of the hydroxysteroid dehydrogenase activity of the enzyme by medroxyprogesterone acetate, hexestrol, and 1,10-phenanthroline suggests that both 1-indanol and hydroxysteroid are oxidized at the same active site on the enzyme. The specific inhibitor of the enzyme, 1,10-phenanthroline, suppressed the 3 alpha-hydroxysteroid dehydrogenase activity in the crude extract of monkey liver by 50%. The results strongly suggest that indanol dehydrogenase acts as a 3(20)alpha-hydroxysteroid dehydrogenase in the metabolism of certain steroid hormones and bile acids.     

Molecular cloning of rat cytolysin

Rat cytolysin is one of the cytolytic factors present in the cytoplasmic granules of rat NK-like cytolytic cells and purified cytolysin exhibits an apparent Mr or 70 kDa. Cytolysis produced by cytolysin occurs in the presence of Ca2+ and is accompanied by the formation of membrane lesions of 160 A diameter. We have isolated a cDNA encoding rat cytolysin from the cDNA library of a rat large granular lymphocyte (LGL) cell line, by hybridization of the rat library with a cDNA probe for mouse perforin. The amino acid sequence deduced from the nucleotide sequence of the isolated cDNA insert indicates that the mature cytolysin protein consist of 534 amino acids with a leader peptide of 20 amino acids. The protein contains two functionally important domains: the first domain is believed to contain the transmembrane channel and the second domain consists of an epidermal growth factor-type "class B" cysteine-rich region. A comparison with mouse perforin indicates that the two genes are very similar (89.9% nucleotide and 84.9% amino acid identity). Northern blot hybridization analysis indicates that cytolysin mRNA is expressed in rat lymphocytes (lymphokine-activated killer cells and LGL cells) and LGL cell lines.     

Mechanism of the stimulatory effect of cyclodextrins on lankacidin-producing Streptomyces

Summary Gel-filtration analysis of a mixture of cyclodextrin (CyD) and lankacidin C showed that -CyD had strong, -CyD weak and -CyD no affinity for lankacidin C. Lankacidin C production activity, which was assayed by measuring the incorporation of l-[methyl-¹⁴C-]methionine into the lankacidin molecule, was the greatest with cells grown in the presence of -CyD, less with -CyD and the least with -CyD. Lankamycin and T-2636M, which are by-products in lankacidin C fermentation, were not included by -CyD and their production was not stimulated by -CyD. It was apparent that the stimulatory effect of CyD was closely related to the formation of an inclusion complex between CyD and the antibiotic. Lankacidin C biosynthesis was repressed by preincubating cells with lankacidin C, while the repressive effect of lankacidin C was abrogated by the inclusion by -CyD. Thus, abrogation of feed-back repression seems to be a main mechanism of the effect of CyD. However, -CyD, which had no affinity for lankacidin C, stimulated the production to the least extent and exhibited a complementary effect on the stimulation by -CyD or -CyD. -CyD also caused a change in cell morphology and cell-surface hydrophobicity. It was assumed that the modification of the cell surface is a secondary mechanism of the effect of CyD.The second report of the stimulatory effect of cyclodextrins on lankacidin fermentationOffprint requests to: H. Sawada     

The spatial distribution pattern of the brown planthopperNilaparvata lugens Stål (Homoptera: Delphacidae) in west Java,Indonesia

Spatial distribution pattern of the brown planthopper (BPH) was analyzed at 9 experimental fields in the northern part of West Java during two consecutive rice cropping seasons, i.e., wet and dry seasons. The population of each developmental stage and wing form of BPH at each location showed consistent departure from the random (Poisson) distribution, the variances of the densities in most cases exceeding their means. Namely, the distribution pattern of BPH per hill of rice plant was found to have a general tendency to be aggregated or contagious and to fit fairly well to the negative binomial model. The tendency for aggregation was further confirmed by both the β-values of -m regression being larger than unity and the C_A-values being larger than zero for each developmental stage. Although significant variations in the distribution pattern as measured by β- or C_A-value were observed between different developmental stages, between wing forms and among locations, the degree of aggregation for a given developmental stage at each experimental field remained fairly stable throughout the crop period, despite wide temporal changes in population density. Possible factors to explain these characteristics of the spatial distribution pattern of the BPH in West Java were discussed with reference to the process generating it.     

Molecular Cloning and Characterization of the cDNA for Discoidin II of Dictyostelium discoideum

By using monoclonal antibodies directed against discoidin II,we have isolated cDNA clones from axenically grown Ax-2 cells.On cDNA clone (D2) condtained a 1.2-k.b insert encoding theentire discoidin II protein, which is conposed of 257 aminoacid residuces and has a calculated molecular mass of 28,574.The amino acid sequences, determined by Edman degradation ofsix tryptic peptides of discoidin II, were identical to thosededuced from the cDNA sequences. The protein bears no resemblanceto any proteins in the data banks, except that its sequenceis 49% identical with the amino acid sequence of discoidin I.Discoidin II shares with discoidin I both a carbohydratebindingsite and an Arg-Gly-Asp (RGD) sequence, which has been foundin fibronectin in mammalian cells. With the onset of aggregation(8 h of development), a 1.3-kb discoidin II mRNA begins to accumulate.A similar pattern of regulation occurs at the protein level. ¹Present address: MRC Laboratory for Molecular Cell Biology,University College London, Gower Street, London, WC1E 6BT UnitedKingdom     

Effects of estradiol and testosterone on the synthesis,expression and degradation of androgen receptor in human uterine endometrial fibroblasts

The mechanism of known receptor-mediated androgen effects on the endometrial stroma was studied in endometrial fibroblasts derived from human uterus. 17-Estradiol (E) induced the expressions of androgen receptor (AR) mRNA, and predominantly increased the level of testosterone-binding sites (TBS) in uterine endometrial fibroblasts. The effect on the level of dihydrotestosterone-binding sites (DHTBS) was similar but smaller. This result suggests that the AR mRNA expressed might encode TBS, but probably not DHTBS. The TBS level increased by estrogen was down-regulated by testosterone (T) + E, but the AR mRNA expression increased by E was not down-regulated by E + T in the fibroblasts. Although the synthesis rate of AR was slightly increased (p<0.05) by E alone or E + T, the degradation rate of AR was significantly accelerated (p<0.05) by E + T in the fibroblasts. This result suggests that T might stimulate the metabolic rate of TBS, but does not inhibit the synthesis rate of AR mRNA to TBS in endometrial fibroblasts.     

Leptocephalus eel larvae will feed in aquaria

Synopsis Premetamorphosing larvae of Muraenesox cinereus (Muraenesocidae) and Conger myriaster (Congridae), caught and kept alive in aquaria, repeatedly bit pieces out of a lump of squid paste. By coloring the paste with Brilliant Red, ingestion and defecation were clearly seen through the transparent gut. The paste is not their natural food, but nevertheless a possible food item for rearing eels from eggs; most previous efforts have failed inasmuch as the larvae have starved.