burial (version 1.0): a method for testing genetic similarity within small groups of individuals using fragmentary data sets

Biologists are frequently facing the problem of dealing with data sets with a small amount of data and a high proportion of missing information. We were particularly interested in analysing fragmentary data sets generated by the application of molecular methods in palaeoanthropology in order to determine whether individuals are genetically related. In this note, we announce the release of the software burial (version 1.0) to test the null hypothesis that the observed grouping of individuals at a particular burial site reflects random placement of genotypes. The proposed test, however, can also be applied to data sets whose objects can be grouped according to nongenetic criteria such as the style of clothing, the kind of burial gifts or cultural artefacts. The C + + source code and binary executables for Windows and Linux are available for download at: http://www.uni‐tuebingen.de/uni/bcm/BURIAL/index.html .     

Adherens junctions in the Drosophila embryo: The role of E-cadherin in their establishment and morphogenetic function

The integrity of epithelia depends largely on specialised adhesive structures, the adherens junctions. Several of the components required for building these structures are highly conserved between vertebrates and insects (e.g. E-cadherin and α- and β-catenin), while others have so far been found only in invertebrates (e.g. crumbs). Two recent papers^(1,2) show that the Drosophila E-cadherin is encoded by the gene shotgun. Phenotypic analyses of shotgun as well as armadillo (β-catenin) and crumbs mutants provide new insights into the mechanisms by which adherens junctions are built and, further, show that the requirement for E-cadherin largely depends on the morphogenetic activity of an epithelium.     

Automated imunoanalysis systems for monitoring mammalian cell cultivation processes

Two different automated immunoanalysis systems are presented. Both are based on the principles of flow-injection analysis and were developed to provide reliable, rapid monitoring of relevant proteins in animal cell cultivation processes. One system uses a turbidimetric analysis, and the other employs a heterogeneous chemistry with immobilized immunocomponents. For both systems, the analysis time is in the range of a few minutes, and a complete analysis cycle, including triplicate analyses and various washing steps, is in the range of 20–30 minutes. Samples from cultivation processes can be analyzed directly without dilution. Quantitation of proteins such as rt-PA or monoclonal antibodies can be performed over an analyte concentration range of 1–1000 mg/L. Both systems were compared to conventional ELISA assays on microtiter plates. The turbidimetric analysis system also included a biosensor for simultaneous glucose determination.     

DNA methyltransferases: Activity minigel analysis and determination with DNA covalently bound to a solid matrix

We describe two methods that facilitate detection and characterization of DNA methyltransferases: activity gel analysis and the use of DNA-cellulose or DNA-Sepharose in DNA methylation reactions. The first permits identification of catalytic subunits, determination of the influence of proteolysis, and evolutionary or developmental studies. The second allows accurate and fast determination of DNA methyltransferase activities in crude extracts and during purification.     

Culture of hybridoma and friend leukemia virus transformed cells in microgravity. Spacelab IML-1 mission

Summary— The behavior of two mammalian cell lines was investigated in Biorack during the 1st Spacelab international microgravity laboratory flight (IML-1) in the ESA facility Biorack. The parameters determined were cell proliferation, biosynthesis of specific cell products, consumption of glucose, glutamine and production of ammonia and lactate respectively. Murine Friend leukemia virus-transformed cells (Friend cells) were induced to differentiate and express hemoglobin (Hg) genes upon induction with dimethylsulfoxide (DMSO). No change was observed in all metabolic parameters including the production of Hg and the number of Hg-positive cells. Electron microscopy analysis showed no difference in morphology, mean cell volume and mitotic index between the different cell samples, Murine hybridoma cells revealed an increase (+ 30–40%) of cell proliferation rate in microgravity, whereas the metabolic parameters, production of monoclonal antibodies included, were lower in the 0 g than in the 1 g controls. The results clearly show that not all mammalian cells undergo dramatic changes in microgravity and that the effects reported on human T lymphocytes represent a unique case.     

A Mixed Model for Binary Data: The Modified X2-test

In this paper, a statistical model for clinical trials is presented for the special situation that a varying and unstructered number of binary responses is obtained from each subject. The assumptions of the model are the following: 1.) For each subject there is a (constant) individual Bernoulli parameter determining the distribution of the binary responses of this subject. 2.) The Bernoulli parameters associated with the subjects are realizations of independent random variables with distributions P_g in treatment group g(g = 1, 2, …, G). 3.) Given the value of the Bernoulli parameter, the observations are stochastically independent within each subject. Under these assumptions, a test statistic is derived to test the hypothesis H₀:E(P₁) = E(P₂) = … = E(P_G). It is proven and demonstrated by simulations, that the test statistic asymptotically (i.e. for a large number of subjects) follows the X²-distribution.