Beauveria bassiana, known for its entomopathogenic characteristics, is the most widely used biocontrol agent against many insect pests and may also be active against soil-borne pathogens. It inhabits the surfaces or inner tissues of various plant species without causing any visible signs or symptoms. Here we show that B. bassiana strain GHA, the active ingredient of a commercial microbial insecticide, colonises tomato plants. GHA grew on intact leaf surfaces of tomato in high humidity, but never entered stomata. Viable hyphae and conidia were detected, and the population on inoculated leaves significantly increased until 14 days after inoculation. On tomato leaves, GHA conidiated normally via conidiophores and phialides, and also via microcycle conidiation (conidiophores and phialides form directly from germ tubes and produce conidia). Hyphae were also detected inside the rachis, even more frequently after plant surfaces were scarified. These results suggested that B. bassiana strain GHA can grow epiphytically and endophytically on tomato plants.

Cladosporium fulvum, the causal fungus of leaf mould of tomato, is present in most countries that grow tomatoes, and is an economic problem, particularly in Japan. The diverse, complex race structure of C. fulvum in Japan enables the fungus to overcome all resistant commercial cultivars. It was noted that C. fulvum lesions on tomato leaves in the greenhouse were overgrown with white mycelia and that leaf mould did not spread further. Two isolates from the white mycelia, designated 414‐2 and 414‐3, were identified from morphological and phylogenetic analyses as the mycoparasite Dicyma pulvinata. Scanning electron microscopy of inoculated leaves showed the mycoparasite had coiled around C. fulvum hyphae around stomata. Microscopic analysis revealed that C. fulvum, engineered to express green fluorescent protein, died when entwined by the isolates only when cocultured in the absence of a carbon source. These results indicate that these isolates are mycoparasitic fungi that absorbed nutrients from C. fulvum. Two isolates and four strains were evaluated according to their abilities to control disease caused by C. fulvum, form conidia and produce an antifungal agent. Isolate 414‐3 parasitized hyphae of C. fulvum on plants in the greenhouse and inhibited leaf mould caused by all physiological races that cause problems for tomato production in Japan. This indigenous isolate of D. pulvinata may thus serve to control the foliar pathogen C. fulvum.

A set of non-histone proteins has been identified in the nuclei from liver, brain, spleen and testis tissues of the rat. Following moderate digestion of thoroughly washed nuclei with DNase 1 or micrococcal nuclease, EDTA was added to 5 m M to the reaction mixture and the preparation centrifuged. We found that the supernatant contained a limited amount of non-histone proteins (fraction SI). Sodium dodecyl sulfate (SDS) gel electrophoresis revealed S1 to be composed of a remarkably simple set of proteins resolved into four groups (A -D) each possessing closely spaced doublets or a triplet. Their molecular weights were A, 76100-80000; B, 48200-49500; C, 44500-45200 and D, 39500-41 500. The yield suggested that these proteins were structural constituents; however, they did not coincide with the known structural proteins of the cell nucleus. Two-dimensional gel electrophoresis further resolved each of the SDS bands into as many as nine spots, according to various charges. Some were labelled with [32P]orthophosphate in vivo, or with [y-32P]ATP and purified nuclear protein kinase NII in vitro. The released proteins B -D had fairly constant relative molar ratios at various times of digestion, thereby indicating possible localizations a t similar sites in the nucleus. The kinetic data together with the aggregation property at neutral pH values and the solubility in 5 mM EDTA suggest that proteins B -D constitute a group of proteins that have several common characteristics.The abundance of protein species in the cell nucleus varies with the protein; some are structural or regulatory in function while others are catalytic in various biochemical processes. Isolation and characterization of these nuclear proteins should greatly aid in understanding the structure and function of the nucleus as well as the molecular properties of the protein in question. Isolation of a group of proteins which share molecular properties may be advantageous, as a common biological function may be involved. The precedent of this can be illustrated with histones and high mobility group (HMG) proteins. Histones, the building molecules of the nucleosomes [I], can be readily extracted in a set from the chromatin with dilute mineral acids [2]; H M G proteins, which confer a structural characteristic of the active Chromatin [3], are extracted as a group from chromatin with 0.35 M NaCl and remain soluble in 2There have been numerous studies on various nuclear architectures such as chromatin, nuclear matrix and nuclear envelopes. One approach is to use DNA-hydrolyzing enzymes ; for example, DNase I has been used to distinguish the transcriptionally active from the bulk chromatin in differential digestion kinetics [5], or to isolate the nuclear pore complexlamina fraction [6] and nuclear matrix [7].In our studies on nuclear proteins we were interested in protein components liberated from the nuclei by digestion with DNA-hydrolyzing enzymes. We report here that a novel and remarkably simple set of non-histone proteins was isolated from the nuclei by nucle...

S1 proteins are present in the nuclear structures sensitive to DNases and RNase. To examine localization of these proteins, an antibody was raised in a rabbit. Indirect immunofluorescence staining revealed that S1 proteins located in the extranucleolar nuclear regions of quiescent myocardial and cerebellar cells as well as actively duplicating mouse 3T3 fibroblasts. They located in euchromatin regions of thymus lymphocytes, with a characteristic aster-like immunofluorescence pattern, and on the border of condensed chromatin areas by deposition of immunogold particles in ultrathin sections of thymus. Thus, S1 proteins may be in a nuclear function assigned to the border of heterochromatin areas, and other than synthesis of DNA or of ribosomal RNA. Possible involvement of S1 proteins in the extranucleolar RNA synthesis is discussed.

A unique and simple set of proteins (S1 proteins) has been detected in the cell nuclei of various tissues of the rat (Inoue et al. (1983) Eur. J. Biochem. 135, 61-68). They were liberated from the nuclei by digestion with DNA-hydrolyzing enzymes under the conditions where transcriptionally active chromatin is preferentially digested and released into the reaction supernatant. S1 proteins account for 20% of the total supernatant proteins (Higashi et al. (1984) Biochem. Int. 9, 697-704). The present study demonstrates that S1 proteins occur at the sites sensitive to RNase A as well as DNase I, and are rapidly liberated from the nuclei by digestion with either enzyme.