Selective synthesis of depsipeptides by the immobilized multienzyme enniatin synthetase

Summary The multifunctional enzyme enniatin synthetase was immobilized by adsorption to propyl agarose. The immobilized multienzyme retained 45% of the activity of the free enzyme; an operational half-life of about 15 h was estimated. Selective synthesis of several different enniatin homologues was achieved with propyl agarose-bound enniatin synthetase. In addition to enniatin A, B, and C formation, a selective synthesis of non-naturally occurring depsipeptides, containing norvaline, norleucine, or -aminobutyric acid as sole amino acid moieties, was observed.     

Age-dependent content of polymerized lipids in Sphagnum fuscum

The polymerized lipids of Sphagnum fuscum cell wall fragments were found to be composed of long chain hydroxy acids, long chain dicarboxylic acids, fatty alcohols and fatty acids. Their content, on a dry weight basis, was low in the topmost 3 cm of the shoot and increased with shoot age (and depth). A pronounced increase (16-fold) occurred in the contents of hydroxy acids which comprised 76% of the totals at the depth of 40–43 cm. The increase at the depth of 40-43 cm is considered to be at least partly associated with the frequently found destruction of the most suscptible part, the thin-walled stem center. The results suggest that aliphatic lipid polymers are present and acumulated in cell walls resistant to breakdown.     

Ribosomal DNA of the fly Sciara coprophila has a very small and homogeneous repeat unit

Summary In this report we show by hybridization of restriction fragments and by Miller spreads that the unit repeat of the fly Sciara coprophila is only 8.4 kb which is the smallest known for a multicellular eukaryote. The 8.4 kb EcoR1 fragment containing a complete unit of Sciara rDNA was cloned in pBR322, and mapped by the method of Parker (1977) and also by double digestion. The coding regions for 28S, 18S, and 5.8S RNA were localized by the method of Berk and Sharp (1977). From these data we conclude that the nontranscribed spacer, external transcribed spacer, and internal transcribed spacer are all shorter than in other organisms, thereby giving rise to the shorter overall rDNA repeat unit of Sciara.At least 90% of the Sciara rDNA repeats are homogeneous, with a length of 8.4 kb, but a 700 bp ladder of minor bands can also be found in digestions of total genome DNA. This profile of major and minor bands is identical between the X and X chromosomes, as seen by a comparison of several genotypes.There are only 45 rRNA genes per X chromosome of Sciara (Gerbi and Crouse, 1976). These can easily be counted by low magnification Miller speads which show that virtually all gene copies are actively being transcribed in the stage of spermatogenesis examined. This is the first demonstration for any reiterated gene family where all copies are shown to be simultaneously active.Present address same as last author     

Phytochrome-mediated control of grana and stroma thylakoid formation in plastids of mustard cotyledons

The etioplast»chloroplast transition in the cotyledons of mustard seedlings (Sinapis alba L.) has been studied by electron microscopy. It was found that the active form of phytochrome, established by a red light pulse pretreatment, increases the initial rate and eliminates the lag of grana and stroma thylakoid formation after the onset of white light 60 h after sowing. The effect of a pretreatment with 15 s red light pulses is fully reversible by 756 nm light pulses. This reversibility is lost within 5 min. Evidence is presented which suggests that the time course of grana and stroma thylakoid formation is not correlated with the time course of the dispersal of the prolamellar body. The different functions of phytochrome and chlorophyll in controlling thylakoid formation are discussed.     

Properties of auxin binding sites in different subcellular fractions from maize coleoptiles

In-vitro binding of labeled auxins to sedimentable particles was tested in subcellular fractions from homogenates of maize (Zea mays L.) coleoptiles. The material was fractionated by differential centrifugation or on sucrose density gradients. It was confirmed that the major saturable binding activity (site I) for 1-naphthyl[1-¹⁴C]acetic acid is associated with vesicles derived from the endoplasmatic reticulum. A second type of specific auxin binding (site II) could be distinguished by several criteria, e.g. by the low affinity towards phenylacetic acid. The particles carrying site II could be clearly separated from markers of the endoplasmatic reticulum, the plasmalemma, the mitochondria and the nuclei, while their density as well as sedimentation velocity correlated with particle-bound acid phosphatase, indicating a localization at the tonoplast. In contrast to site I, binding at site II was hardly affected by a supernatant factor and by sulfhydryl groups. However, the specificity pattern of site II towards auxins and auxin analogs was very similar to that of site I tested in the presence of supernatant factor. The existence of a third auxin receptor localized in plasma membrane-rich gradient fractions was indicated by a preferential in-vitro binding of 2,4-dichlorophenoxyacetic acid.Abbreviations 1-NAA 1-naphthyl acetic acid - 2-NAA 2-naphthyl acetic acid - IAA 3-indolyl acetic acid - PAA phenyl acetic acid - 2,4-D 2,4-D-dichlorophenoxy acetic acid - D-2,4-DP dichlorophenoxy isopropionic acid - NPA 1-N-naphthyl phthalamic acid - ER endoplasmatic reticulum - SF supernatant factor     

Evolutionary changes in non-histone chromosomal proteins within the Drosophila melanogaster group revealed by monoclonal antibodies

Monoclonal antibodies directed against nonhistone chromosomal proteins of D. melanogaster were tested for crossreactivity with the homologous antigens of various Drosophila species. — By indirect immunofluorescence it could be shown that three antibodies react only with polytene chromosomes of species of the D. melanogaster subgroup, and only much less with chromosomes of other species of Drosophila. — With chromosomes of various other species of the Sophophora or Drosophila radiations only a reaction at background level could be observed. — The results suggest that the three antibodies react with different antigenic determinants of a single protein whose conformation changed rather fast during evolution of the Drosophilidae.     

Biphasic 24-Hour Variations in Cyclic GMP Accumulation in the Rat Pineal Gland Are Due to Corresponding Changes in the Activity of Cytosolic and Particulate Guanylate Cyclase

Various parameters of the rat pineal gland display a 24-h rhythm. However, nothing is known about possible 24-h variations in cyclic GMP (cGMP) metabolism. In the present study, 24-h variations in pineal gland cGMP accumulation were investigated by determining the increase in cGMP level with and without inhibitors of phosphodiesterase at different time points over a light/dark cycle (12/12 h). Furthermore, the activity of guanylate cyclase (GC) was determined under substrate-saturated conditions regarding the cytosolic and particulate forms of the enzyme. It has been found that cGMP accumulation and GC activity display biphasic 24-h variations with two peaks--one approximately 7 h after lights "on" and the other approximately 7 h after lights "off." The activity of cytosolic GC remains unchanged in the presence of the nitric oxide (NO) synthesis inhibitor N-monomethyl-L-arginine, indicating that 24-h variations in the activity do not reflect changes in the synthesis of the GC stimulator NO.     

Settlement of the diazotrophic,phytoeffective bacterial strain Pantoea agglomerans on and within winter wheat: An investigation using ELISA and transmission electron microscopy

The aim of this study was to investigate the ability of Pantoea agglomerans, a plant growth-promoting bacterium, to colonize various regions and tissues of the wheat plant (Triticum aestivum L.) by using different inoculation methods and inoculum concentrations. In addition, the enzyme-linked immunosorbent assay (ELISA) and transmission electron microscopy (TEM) were used to determine: (a) the ability of the bacterial cells to grow and survive both on the surface and within internal tissue of the plant and (b) the response of the plant to bacterial infection. After inoculation, cells of the diazotrophic bacterial strain P. agglomerans were found to be located in roots, stems and leaves. Colony development of bacterial cells was only detected within intercellular spaces of the root and on the root surface. However, single bacterial cells were observed in leaves and stems on the surface of the epidermis, in the vicinity to stomatal cells, within intercellular spaces of the mesophyll and within xylem vessels. Inoculated bacterial cells were found to be able to enter host tissues, to multiply in the plant and to maintain a delicate relationship between endophyte and host. The density of bacterial settlement in the plant in all experiments was about 10⁶ to 10⁷ cells per mL root or shoot sap. Establishment was confirmed by a low coefficient of variation of ELISA means at these concentrations.     

Foaming in winemaking

Summary A new technique for the measurement of foaming in winemaking is described. Linear relationships are established between the foaminess of bovine serum albumin solutions and its concentration, between the foaminess of fermented artificial medium and its concentration and between the foaminess and the rate of sparging of gas. The effect of temperature on the foaminess of a bovine serum albumin solution is also established.     

Genetic analysis of Tourette syndrome suggesting major gene effect.

Data on Gilles de la Tourette syndrome are analyzed by multiple threshold models in inheritance that incorporate sex effect. The polygenic-multifactorial model is rejected. Single major locus inheritance can account for the data, although many of the occurrences of Tourette are due to nongenetic phenocopies. In both models, males and females share a common genetic environmental liability, but the less prevalent sex, that is, females, has a higher genetic loading for the disorder. The predicted population prevalences in the single major locus model are 2.3% for males and 0.8% for females. The implications for genetic and biological research in Tourette syndrome are discussed.