The repressor and co-activator HsfB1 regulates the major heat stress transcription factors in tomato.

Plants code for a multitude of heat stress transcription factors (Hsfs). Three of them act as central regulators of heat stress (HS) response in tomato (Solanum lycopersicum). HsfA1a regulates the initial response, and HsfA2 controls acquired thermotolerance.

HsfA2 Controls the Activity of Developmentally and Stress-Regulated Heat Stress Protection Mechanisms in Tomato Male Reproductive Tissues.

Male reproductive tissues are more sensitive to heat stress (HS) compared to vegetative tissues, but the basis of this phenomenon is poorly understood. Heat stress transcription factors (Hsfs) regulate the transcriptional changes required for protection from HS In tomato (Solanum lycopersicum), HsfA2 acts as coactivator of HsfA1a and is one of the major Hsfs accumulating in response to elevated temperatures. The contribution of HsfA2 in heat stress response (HSR) and thermotolerance was investigated in different tissues of transgenic tomato plants with suppressed HsfA2 levels (A2AS).

In the complex family of heat stress transcription factors, HsfA1 has a unique role as master regulator of thermotolerance in tomato.

We generated transgenic tomato plants with altered expression of heat stress transcription factor HsfA1. Plants with 10-fold overexpression of HsfA1 (OE plants) were characterized by a single HsfA1 transgene cassette, whereas plants harboring a tandem inverted repeat of the cassette showed cosuppression (CS plants) by posttranscriptional silencing of the HsfA1 gene connected with formation of small interfering RNAs. Under normal growth conditions, major developmental parameters were similar for wild-type (WT), OE, and CS plants.

The protein encoded by the Drosophila position-effect variegation suppressor gene Su(var)3-9 combines domains of antagonistic regulators of homeotic gene complexes.

Modifier mutations of position-effect variegation (PEV) represent a useful tool for a genetic and molecular dissection of genes connected with chromatin regulation in Drosophila. The Su(var)3-9 gene belongs to the group of haplo suppressor loci which manifest a triplo enhancer effect. Mutations show a strong suppressor effect even in the presence of PEV enhancer mutations, indicating a central role of this gene in the regulation of PEV.

P transposon-induced dominant enhancer mutations of position-effect variegation in Drosophila melanogaster.

P transposon induced modifier mutations of position-effect variegation (PEV) were isolated with the help of hybrid dysgenic crosses (pi 2 strain) and after transposition of the mutator elements pUChsneory+ and P[lArB]. Enhancer mutations were found with a ten times higher frequency than suppressors. The 19 pUChsneory(+)- and 15 P[lArB]-induced enhancer mutations can be used for cloning of genomic sequences at the insertion sites of the mutator elements via plasmid rescue.

Non-selective action of 4-hydroxyanisole on melanoma cells in vivo.

In order to clarify the role of tyrosinase (E.C. 1.

[Synthesis of 5-bromosalicyl-4'-chloroanilide-O-beta-D-xylopyranoside and other transport forms enzymatically activated by microbes].

The synthesis of 5-bromosalicyl-4'-chloroanilide-O-beta-D-xylopyranoside and other glycosides of 5-bromosalicyl-4'-chloroanilide, salicylanilide, 3,5-dichlorophenol and tetrachlorohydrochinone is described. Glycosidations follow the procedures described by Latham et al. Sabalitschka and Helferich et al.

[Synthesis and properties of digitoxigenin-3 beta-O-alpha-L-arabinofuranoside].

The synthesis of a cardenolide glycoside with a furanoide sugar component, digitoxigenin-3 beta-O-alpha-L-arabinofuranoside (4), is described for the first time. 4 was prepared by the reaction of digitoxigenin with 2,3,5-tri-O-benzoyl-alpha-L-arabinofuranosylchloride and Fétizon-reagent in benzene/dioxan followed by debenzoylation with ammonia in dry methanol. Compound 4 is cleaved by alpha-L-arabinofuranosidase (Aspergillus niger K1) into digitoxigenin and L-arabinose.

[Situation and perspectives of tumor chemotherapy from experimental viewpoint (author's transl)].

In a reveiw article the origin, the present position, and the possibilities of further development of tumour chemotherapy are described. The central problems in preparing new substances and combinations with more selective activity, and different forms of carriers with promising perspectives are discussed.

Selective tumor DNA synthesis inhibition: in vivo prodrug activation by an exogenous enzyme.

Using the combination of alpha-L-arabinofuranosidase from Aspergillus niger with beta-peltatin A-alpha-L-arabinofuranoside, the selective effect of a new cancer of chemotherapy method based on a pH-dependent activation of cancerostatic prodrugs by exogenous enzymes was studied. In comparative experiments the selectivity of prodrug activation was measured by 3H-thymidine incorporation in tumor and normal tissues of CBA mice inoculated im with the transplantable mammary carcinoma, MA-21224. The results show that this special type of carrier principle may lead to a higher degree of selectivity than the usual direct application of cancerostatic drugs.