Functional and conserved domains of the Drosophila transcription factor encoded by the segmentation gene knirps

The Drosophila gap gene knirps (kni) is required for abdominal segmentation. It encodes a steroid/thyroid orphan receptor-type transcription factor which is distributed in a broad band of nuclei in the posterior region of the blastoderm. To identify essential domains of the kni protein (KNI), we cloned and sequenced the DNA encompassing the coding region of nine kni mutant alleles of different strength and kni-homologous genes of related insect species. We also examined in vitro-modified versions of KNI in various assay systems both in vitro and in tissue culture. The results show that KNI contains several functional domains which are arranged in a modular fashion. The N-terminal 185-amino-acid region which includes the DNA-binding domain and a functional nuclear location signal fails to provide kni activity to the embryo. However, a truncated KNI protein that contains additional 47 amino acids exerts rather strong kni activity which is functionally defined by a weak kni mutant phenotype of the embryo. The additional 47-amino-acid stretch includes a transcriptional repressor domain which acts in the context of a heterologous DNA-binding domain of the yeast transcriptional activator GAL4. The different domains of KNI as defined by functional studies are conserved during insect evolution.

Dimerization and the control of transcription by Krüppel

Krüppel (KR), a Drosophila zinc finger-type transcription factor, can both activate and repress gene expression through interaction with a single DNA-binding site. The opposite regulatory effects of KR are concentration-dependent, and they require distinct portions of KR such as the N-terminal region for activation and the C-terminal region for repression. Here we show that KR is able to form homodimers through sequences located within the C terminus. When these sequences were fused to separated functional parts of the yeast transcription factor GAL4, they reconstituted a functional transcriptional activator on dimerization in vivo. Our results suggest that the KR monomer is a transcriptional activator. At higher concentration KR forms a homodimer and becomes a repressor that functions through the same target sequences as the activator.

Transcriptional cascades in Drosophila

Genetics and molecular analyses have combined to yield insights into a functional cascade of transcription factors necessary to establish the molecular blueprint of the Drosophila body pattern in response to positional information in the egg. Recent progress in this field raises exciting questions regarding the molecular mechanisms involved, and their conservation in biological pattern-forming processes.

[European drug policy]

The European harmonization of pharmaceutical legislation was completed in 1992, but the harmonization of marketing authorizations still requires the creation of an "European medicines evaluation agency", From january 1995, two complementary marketing authorization procedures will have to be established for human and veterinary medicines in the European Community: a decentralised procedure for most products, and a centralised procedure, only valid for innovative products. At the same time, a better coordination of the assessment of adverse drug reactions (pharmacovigilance) should be achieved.

Concept for an optical bus-type interconnection network

A concept for parallel optoelectronic bus-type interconnections (many participants-many participants) is given. The choices between multimode and single-mode fan-ins in free-space optical systems are discussed. When one single space-invariant multiple beam-splitting system is used for fan-out and fan-in simultaneously, the energy requirements for communications scale with 2N (for N participants on each busline), which is compared with N(2) for space-variant systems. A simple demonstration experiment with a Dammann grating used as a multiple beam splitter is shown, and in a design example the theoretical performance is discussed.

Transcriptional control by Drosophila gap genes

The segmented body pattern along the longitudinal axis of the Drosophila embryo is established by a cascade of specific transcription factor activities. This cascade is initiated by maternal gene products that are localized at the polar regions of the egg. The initial long-range positional information of the maternal factors, which are transcription factors (or are factors which activate or localize transcription factors), is transferred through the activity of the zygotic segmentation genes. The gap genes act at the top of this regulatory hierarchy. Expression of the gap genes occurs in discrete domains along the longitudinal axis of the preblastoderm and defines specific, overlapping sets of segment primordia. Their protein products, which are DNA-binding transcription factors mostly of the zinc finger type, form broad and overlapping concentration gradients which are controlled by maternal factors and by mutual interactions between the gap genes themselves. Once established, these overlapping gap protein gradients provide spatial cues which generate the repeated pattern of the subordinate pair-rule gene expression, thereby blue-printing the pattern of segmental units in the blastoderm embryo. Our results show different strategies by which maternal gene products, in combination with various gap gene proteins, provide position-dependent sets of transcriptional activator/repressor systems which regulate the spatial pattern of specific gap gene expression. Region-specific combinations of different transcription factors that derive from localized gap gene expression eventually generate the periodic pattern of pair-rule gene expression by the direct interaction with individual cis-acting "stripe elements" of particular pair-rule gene promoters. Thus, the developmental fate of blastoderm cells is programmed according to their position within the anterior-posterior axis of the embryo: maternal transcription factors regulate the region-specific expression of first zygotic transcription factors which, by their specific and unique combinations, control subordinate zygotic transcription factors, thereby subdividing the embryo into increasingly smaller units later seen in the larva.

Concentration-dependent transcriptional activation or repression by Krüppel from a single binding site

One of the gap class of segmentation genes, Krüppel (Kr), is required for normal thorax and abdominal development of the Drosophila embryo. Its gene product, a zinc-finger type protein, forms a bell-shape concentration gradient in a central position of the blastoderm. Genetic and molecular studies suggested that the Kr protein (KR) may act both as a positive and as a negative regulator of transcription on several other genes of the zygotic segmentation hierarchy. We have examined the regulatory potential of Kr by a series of cotransfection experiments in the Drosophila Schneider cell line system. Different doses of Kr expression plasmid were tested for their ability to drive reporter gene expression mediated by a single 11-base pair KR in vitro binding site common to several putative Kr target genes. Our results show that low amounts of Kr expression plasmid lead to transcriptional activation, whereas high amounts result in repression. Distinct portions of KR other than the DNA-binding domain are required for gene activation and repression, suggesting that KR itself can act as a concentration-dependent positive and negative regulator of transcription.

Drug safety in the European community

By 1992 the European Community's pharmaceutical legislation will cover all industrially produced medicines, including vaccines, blood products and radiopharmaceuticals. The quality, safety and efficacy requirements have been harmonised, as have certain aspects of procedures for marketing authorisation or for manufacture. The complete texts of the 'Rules Governing Medicinal Products in the European Community' were published recently. Pharmaceutical companies have 2 types of European Community registration procedures available, which are intended to facilitate the adoption of a common position by the member states. The experience gained with the procedures of the Committee for Proprietary Medicinal Products (CPMP) has highlighted opportunities for closer cooperation, either before national decisions (concertation procedure) or after such decisions (multi-state procedure). The installation, in 1993, of a single European market without borders implies that medicinal products should be able to circulate throughout the European Community with the same conditions attached to their marketing. Monitoring the adverse effects of medicinal products (pharmacovigilance) is also a major issue. The existing arrangements for exchanging postmarketing information will be reinforced, in future, by strengthening the legal provisions already in force.

Staircase telescope arrays for local beam compression in one dimension

A deflecting staircase can be used like a telescope array to produce local beam compression in l-D. Such a component may be useful for array illumination in digital optical information processing. This paper introduces the concept of staircase telescope arrays and discusses realizations with mirrors, prisms, and gratings. The addition of a macro deflecting element and the extension of the staircase concept to 2-D beam compression are further topics.

Fabrication of diffractive-reflective optical interconnects for infrared operation based on total internal reflection

Diffractive-reflective optical interconnects (DROIs) for optical chip-to-chip interconnection were introduced in a 1988 paper. In this paper we demonstrate the use of total internal reflection for guiding the light. inside the glass plate. The required holographic grating couplers were produced by expoiting the wavelength change from blue light recording to red light reconstruction. Several types of fan-out DROI have been made in dichromated gelatin.

Diffractive-reflective optical interconnects

We have demonstrated the feasibility of diffractive-reflective optical interconnects. These interconnects consist of a sandwich of a holographic plane and a reflective plane. Various possibilities like beam relaying, connection switching, and broadcasting are discussed.

Holographic telescope arrays

A typical job in optical computing is to illuminate an array of small nonlinear optical components, separated by wide gaps to avoid crosstalk. We do this by letting a wide uniform beam fall onto a densely packed array of minifying telescopes. Each telescope produces a narrow bundle of parallel rays which illuminates one of the nonlinear optical components. The holographic telescopes can do more than change the width of the bundles of parallel rays. Their image forming capability allows the transmission of many pixels per channel in parallel. The pair of lenslets of a single holographic telescope (Kepler or Galilean) is produced in rigid coupling. The monolithic production avoids adjusting the two lenslets later on.

Rules governing pharmaceuticals in the European Community

In the interest of public health, the European community has progressively established common scientific criteria for the evaluation of human and veterinary medicines and harmonized the national authorization procedures. One major consequence of this has been that neither the tests and trials carried out to obtain authorization nor batch controls need be repeated within the European community. Henceforth the pharmaceutical industry may benefit from two types of procedures intended to facilitate the registration of their medicinal products in the member states. One, reserved for biotechnology/high technology medicinal products, involves community coordination prior to any national decision together with special protection against copies for ten years, irrespective of the position under patent law. The other enables firms to request the recognition by the other member states of an authorization previously granted by one member state. The experience gained from these two procedures will lead to the choice of the most appropriate European registration procedure for the next decade. In the interests of the European consumer, cooperation between the 12 member states and the Commission of the European Communities has progressively increased within the Committee for Proprietary Medicinal Products (adverse effects of medicines/pharmacovigilance) and the Committee for Veterinary Medicinal Products (residues). In association with these committees, several working groups of experts attempt to approximate and codify practices in the evaluation of the quality, safety, and efficacy of medicinal products (guidelines).(ABSTRACT TRUNCATED AT 250 WORDS)

Secondary amenorrhea associated with balanced X-autosome translocation

This is the first reported instance of a patient with gonadal dysgenesis that involves translocation of part of the long arm of an X chromosome to the short arm of a number 7 autosome. The importance of considering gonadal dysgenesis early in the evaluation of patients with secondary amenorrhea considered for ovulation induction is stressed. The relation between chromosomal rearrangement, phenotypic expression, and clinical presentation is discussed.

Metabolite synthesis by rat liver cells and rat liver mitochondria

The use of rat liver cells prepared by mechanical dispersion techniques has recently been severely criticized on the basis that resulting plasma membrane damage leads to total loss of cytoplasmic constituents, thus leaving only membrane sacs containing mitochondria. In the present study, metabolite synthesis by mechanically prepared cells (M cells), collagenase prepared cells (E cells), and isolated mitochondria is compared.It was found that M cells have high rates of endogenous fatty acid oxidation and incorporate [1-14C]acetate approximately equally into 3-hydroxybutyrate, glutamate, citrate, malate, and 2-oxoglutarate. In contrast, mitochondria synthesize primarily citrate and aspartate but no 3-hydroxybutyrate from [1-14C]acetate. Loss of some cytoplasmic enzymes from M cells during isolation was confirmed. M cells are incapable of gluconeogenesis from lactate, synthesize much less glutamate than E cells, and become more highly oxidized during incubation ([NAD+]/[NADH] ratio of 135 versus 30 for E cells). Metabolite synthesis from [1-14C]acetate by mitochondria can be regulated by adding very low concentrations of organic acids and electron donors to the incubation.From these results it was concluded that M cells carry out metabolic reactions not present in isolated mitochondria. Metabolic reactions in mitochondria will approximate those of M cells if electron donors and mixtures of anions are added to the incubation.