Light Stimuli and Circadian Clock Affect Neural Development in .

Endogenous clocks enable organisms to adapt cellular processes, physiology, and behavior to daily variation in environmental conditions. Metabolic processes in cyanobacteria to humans are under the influence of the circadian clock, and dysregulation of the circadian clock causes metabolic disorders. In mouse and , the circadian clock influences translation of factors involved in ribosome biogenesis and synchronizes protein synthesis.

Mbt/PAK4 together with SRC modulates N-Cadherin adherens junctions in the developing eye.

Tissue morphogenesis is accompanied by changes of adherens junctions (AJ). During eye development, AJ reorganization includes the formation of isolated N-Cadherin AJ between photoreceptors R3/R4. Little is known about how these N-Cadherin AJ are established and maintained.

Animal Models for Coffin-Lowry Syndrome: RSK2 and Nervous System Dysfunction.

Loss of function mutations in the gene cause Coffin-Lowry syndrome (CLS), which is associated with multiple symptoms including severe mental disabilities. Despite the characterization of ribosomal S6 kinase 2 (RSK2) as a protein kinase acting as a downstream effector of the well characterized ERK MAP-kinase signaling pathway, it turns out to be a challenging task to link RSK2 to specific neuronal processes dysregulated in case of mutation. Animal models such as mouse and combine advanced genetic manipulation tools with imaging techniques, high-resolution connectome analysis and a variety of behavioral assays, thereby allowing for an in-depth analysis for gene functions in the nervous system.

RSK Influences the Pace of the Circadian Clock by Negative Regulation of Protein Kinase Shaggy Activity.

Endogenous molecular circadian clocks drive daily rhythmic changes at the cellular, physiological, and behavioral level for adaptation to and anticipation of environmental signals. The core molecular system consists of autoregulatory feedback loops, where clock proteins inhibit their own transcription. A complex and not fully understood interplay of regulatory proteins influences activity, localization and stability of clock proteins to set the pace of the clock.

Mcm3 replicative helicase mutation impairs neuroblast proliferation and memory in Drosophila.

In the developing Drosophila brain, a small number of neural progenitor cells (neuroblasts) generate in a co-ordinated manner a high variety of neuronal cells by integration of temporal, spatial and cell-intrinsic information. In this study, we performed the molecular and phenotypic characterization of a structural brain mutant called small mushroom bodies (smu), which was isolated in a screen for mutants with altered brain structure. Focusing on the mushroom body neuroblast lineages we show that failure of neuroblasts to generate the normal number of mushroom body neurons (Kenyon cells) is the major cause of the smu phenotype.

Loss of the Coffin-Lowry syndrome-associated gene RSK2 alters ERK activity, synaptic function and axonal transport in Drosophila motoneurons.

Plastic changes in synaptic properties are considered as fundamental for adaptive behaviors. Extracellular-signal-regulated kinase (ERK)-mediated signaling has been implicated in regulation of synaptic plasticity. Ribosomal S6 kinase 2 (RSK2) acts as a regulator and downstream effector of ERK.

The MAP kinase p38 is part of Drosophila melanogaster's circadian clock.

All organisms have to adapt to acute as well as to regularly occurring changes in the environment. To deal with these major challenges organisms evolved two fundamental mechanisms: the p38 mitogen-activated protein kinase (MAPK) pathway, a major stress pathway for signaling stressful events, and circadian clocks to prepare for the daily environmental changes. Both systems respond sensitively to light.

iTRAQ analysis of a cell culture model for malignant transformation, including comparison with 2D-PAGE and SILAC.

To study human cancer development, cell culture models for malignant transformation can be used. In 1999 Hahn and Coworkers introduced such a model system and established herewith a basis for research on human tumorigenesis. Primary human fibroblasts are sequentially transduced with defined genetic elements (hTERT, SV40 ER, and H-RasV12), resulting in four defined cell lines, whereby the last has a fully transformed phenotype.

Structural brain mutants: mushroom body defect (mud): a case study.

Single-gene mutants of Drosophila have not only increased our understanding of the biochemical processes underlying learning and memory processes, but also established structure-function relationships. The first relevant mutants were identified by Martin Heisenberg nearly 30 years ago in a screen for altered adult brain structure and were used to link the mushroom bodies in the central brain with olfactory learning and memory processes. Because the observed structural defects in the adult are the consequence of deregulated developmental processes, the characterization of these mutants can also provide insight into the genetic programs underlying the establishment, maintenance, and remodeling of functional neuronal circuits.

The Drosophila p21-activated kinase Mbt modulates DE-cadherin-mediated cell adhesion by phosphorylation of Armadillo.

Phosphorylation by tyrosine and serine/threonine kinases regulate the interactions between components of the cadherin-catenin cell-adhesion complex and thus can influence the dynamic modulation of cell adhesion under normal and disease conditions. Previous mutational analysis and localization experiments suggested an involvement of single members of the family of PAKs (p21-activated kinases) in the regulation of cadherin-mediated cell adhesion, but the molecular mechanism remained elusive. In the present study, we address this question using the Drosophila PAK protein Mbt, which is most similar to vertebrate PAK4.

A 5'-fluorosulfonylbenzoyladenosine-based method to identify physiological substrates of a Drosophila p21-activated kinase.

Nearly all processes in cells are regulated by the coordinated interplay between reversible protein phosphorylation and dephosphorylation. Therefore, it is a great challenge to identify all phosphorylation substrates of a single protein kinase to understand its integration into intracellular signaling networks. In this work, we developed an assay that holds promise as being useful for the identification of phosphorylation substrates of a given protein kinase of interest.

Differentiation potential of FDCPmix cells following injection into blastocysts.

Factor-dependent cell Paterson mixed potential (FDCPmix) cells are murine, multipotent, interleukin-3 (IL-3)-dependent progenitor cells, established from long-term bone marrow cultures. They show multilineage myeloid/erythroid and osteoclast differentiation capacity in vitro. FDCPmix cells are neither immortalised, leukaemic nor transformed and have no detectable karyotypic abnormalities.

Erythroid-like cells from neural stem cells injected into blastocysts.

Objective: In contrast to embryonic stem (ES) cells, which are able to give rise to all cell types of the body, somatic stem cells have been thought to be more limited in their differentiation potential in that they are committed to generate only cells of their tissue of origin. Unexpectedly, some recent data suggest that somatic stem cells isolated from one tissue can also generate cells of heterologous tissues and organs, implying that somatic stem cells have a greater potential for differentiation.

Methods: To explore further the developmental potential of murine neural stem cells (NSCs) we injected cultured NSCs as neurospheres into preimplantation blastocysts and determined the seeding by donor cells in tissues of developing chimeric fetal and adult animals.

The MRJP/YELLOW protein family of Apis mellifera: identification of new members in the EST library.

Major royal jelly proteins (named MRJP1-5) of honeybee (Apis mellifera), yellow proteins of Drosophila, together with putative proteins found in several bacteria, form a protein family termed the MRJP/yellow family. Members of the family exert diverse physiological functions and amongst eukaryotes appear to be restricted to the order Insecta. MRJPs constitute about 90% of total protein of royal jelly, which is secreted by nurse bees to feed the queen and growing larvae.

Chimaerism and erythroid marker expression after microinjection of human acute myeloid leukaemia cells into murine blastocysts.

It has been suggested that the embryonic microenvironment can control the survival and the transformed phenotype of tumour cells. Here, we addressed the hypothesis that the murine embryonic microenvironment can induce the differentiation of human tumour cells. To examine such interactions, we injected human leukaemic cells into preimplantation murine blastocysts at embryonic day 3.

Developmental potentials of hematopoietic and neural stem cells following injection into pre-implantation blastocysts.

Pluripotent embryonic stem (ES) cells are able to differentiate in vivo into all cell types of the fetal and adult organism and in vitro they can differentiate into a variety of cell types. In contrast, multipotent somatic stem cells (SSCs) isolated from fetal and adult tissues differentiate into mature effector cells of their tissue. However, recent studies imply that SSCs can also generate cell types of heterologous tissues indicating unexpected broad differentiation potentials.

Production and characterization of monoclonal antibodies against human BAD protein.

More then 20 hybridoma cell lines secreting antibodies to recombinant human BAD protein were established. From five hybridomas monoclonal antibodies were purified and characterised. Four monoclonal antibodies belong to the IgG1 subclass.

Prognostic relevance of the intrinsic growth deceleration of the first passage xenografts of human renal cell carcinomas.

Background: Although successful xenotransplantation of human tumors in nude mice highly predicts prognosis, little is known regarding the biologic background of this correlation. In this study, the relationship between the macroscopic growth pattern of first-generation xenografts of human renal cell carcinomas in nude mice and prognosis was studied.

Methods: Macroscopic growth patterns of the first-generation xenografts of locally confined renal cell carcinomas were analyzed according to the best-fit Gompertz recursion formulas.

Use of the recursion formula of the Gompertz survival function to evaluate life-table data.

The recursion formula of the Gompertz function is an established method for the analysis of growth processes. In the present study the recursion formula of the Gompertz survival function 1n S(t + s) = a + b x ln S(t) is introduced for the analysis of survival data, where S(t) is the survival fraction at age 1, s is the constant age increment between two consecutive measurements of the survival fraction and a and b are parameters. With the help of this method--and provided stroboscopial measurements of rates of survival are available--the Gompertz survival function, instead of the corresponding mortality function, can be determined directly using linear regression analysis.

Improved determination of variant erythrocytes at the glycophorin A (GPA) locus and variant frequency in patients treated with radioiodine for thyroid cancer.

Red blood cells from individuals with the blood group MN express each form of the allelic GPA protein (GPAM and GPAN) on their cell surface. Variant cells have lost one form of the protein. Their frequency is about 10(-5) in blood from unexposed persons.

EGT2 gene transcription is induced predominantly by Swi5 in early G1.

In a screen for cell cycle-regulated genes in the yeast Saccharomyces cerevisiae, we have identified a gene, EGT2, which is involved in cell separation in the G1 stage of the cell cycle. Transcription of EGT2 is tightly regulated in a cell cycle-dependent manner. Transcriptional levels peak at the boundary of mitosis and early G1 The transcription factors responsible for EGT2 expression in early G1 are Swi5 and, to a lesser extent, Ace2.