Genetic reporter for live tracing fluid flow forces during cell fate segregation in mouse blastocyst development

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Analysis of the invasion mechanisms of the cercaria of Diplostomum apathaceum. I. Attachment and penetration (author's transl)

The invasion of the fish host by the cercaria of Diplostomum spathaceum consists essentially of two steps, (a) Fastening to the host — attachment. (b) Entering the host — penetration. These two mechanisms require different stimuli. Attachment, following spontaneous swimming, was triggered by contact with all the aquatic animals tested, but not by plants or inorganic materials. This was probably due to their chemical rather than physical nature. However, a swimming movement which was initiated by mechanical stimuli, led to attachment on contact with any substrate, but not swimming initiated by shadowing. Penetration is stimulated by fish, frogs and their organs, but not by the first intermediate host or other animals unsuitable as hosts. Penetration stimuli are increasing viscosity and the chemical conditions of the substrate. The variety of available substrates is limited at three levels: (a) Presence of the cercaria at the same depth of water as the fish host, (b) Attachment occurs almost entirely on acquatic animals, (c) Only fish and amphibia are penetrated.     

Synthesis of the Rhodopseudomonas viridis holo-cytochrome c2 in Paracoccus denitrificans

Abstract The gene encoding the Rhodopseudomonas viridis cytochrome c ₂ (cycA) has been introduced on a broad host range vector into Paracoccus denitrificans , leading to high-level expression of the holo-cytochrome with the heme moiety covalently attached to the apoprotein. The cytochrome was demonstrated to reside in the periplasmic space of the host cell. In contrast to R. viridis , aerobic rather than anaerobic growth conditions led to higher production levels of the holo-cytochrome in P. denitrificans . This heterologous expression system provides a suitable genetic background for the functional expression and mutagenesis of polypeptides involved in bacterial photosynthesis, offering the possibility of detailed structural and functional investigation.     

Review: Preimplantation genetic diagnosis (PGD) as a reproductive option in patients with neurodegenerative disorders

Preimplantation genetic diagnosis (PGD) was introduced in the late 1980s and represents an option for couples at risk of transmitting an inherited, debilitating or neurological disorder to their children. From a cleavage or blastocyst stage embryo, cell(s) are collected and then genetically analyzed for disease; enabling an unaffected embryo to be transferred into the uterus cavity. Nowadays, PGD has been carried out for several hundreds of heritable conditions including myotonic dystrophy, and for susceptibility genes involved in cancers of the nervous system. Currently, advanced molecular technologies with better resolution, such as array comparative genomic hybridisation, quantitative polymerase chain reaction, and next generation sequencing, are on the verge of becoming the gold standard in embryo preimplantation screening. Given this, it may be time for neurological societies to consider the published evidence to develop new guidelines for the integration of PGD into modern preventative neurology. Therefore, the main aim of this review is to illustrate the option of PGD to enable conception of an unaffected baby, and to assist clinicians and neurologists in the counseling of the patient at risk of transmitting an inherited disease, to explore the genetic journey throughout in vitro fertilization IVF with PGD.     

Epiblast inducers capture mouse trophectoderm stem cells in vitro and pattern blastoids for implantation in utero

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Inhibition of attachment and growth of tumor cells on collagen by a monoclonal antibody

Summary A murine monoclonal antibody, VM-1, which binds to basal cells of normal human epidermis, reduces the ability of human squamous cell carcinoma cells (SCL-1) derived from the skin to attach and spread on collagen by about 50% and causes cell rounding. Similar effects have been previously shown using normal human keratinocytes. The attachment of cell lines derived from human lung squamous cell carcinomas (SW1271 and SW900), melanoma A375, glioblastoma 126, and fibrosarcoma HT1080 is also inhibited by this antibody. VM-1 antibody does not bind to normal human fibroblasts, benign nevus cells, or the human B-cell-derived line 8866. VM-1 antibody inhibits the growth of SCL-1 cells in vitro as measured by cell numbers and [³H]thymidine ([³H]TdR) incorporation. It is not cytolytic in the presence of complement as measured by⁵¹Cr release. Repeated treatment of SCL-1 cells with VM-1 antibody significantly reduces the proportion of SCL-1 cells that attach to collagen. In addition, after treatment of SCL-1 cells with VM-1 antibody, several proteins can no longer be demonstrated by gel electrophoresis of the cell-free supernatant. The VM-1 antibody effect on attachment and spreading is partially reversed by pretreatment of the collagen surface with laminin and fibronectin, but not with the carbohydrates chondroitin-6-sulfate or hyaluronic acid or with the protein lysozyme. By fluorescence staining, the antigen recognized by VM-1 antibody is membrane-bound and Triton X-100 extractable. The VM-1 antigen is excluded from Bio-Sil TSK-400 and sediments at about 10.5 S. It has a covalent molecular weight on the order of 10⁶. Proteinase K digestion produces VM-1 antibody reactive fragments, assumed to be polysaccharides, with a polydisperse molecular weight distribution in the range 5000 to 30 000. The VM-1 antigen is partially lost from solution on boiling and is no longer detectable in the aqueous or organic phase after chloroform-methanol extraction. The properties of the VM-1 antigen are consistent with those of a proteoglycan involved in attachment and spreading of kerationcytes and certain tumor cells on collagen. This research was supported by a grant from the Elsa U. Pardee Foundation, a Training Grant from the National Institutes of Health, Bethesda, MD, and the Psoriasis Research Institute. Part of this work has appeared as an abstract in Fed. Proc. 43:1929, Abst. #2994, 1984.     

The functions and biosynthesis of the c-type cytochromes of bacterial respiratory chains with particular reference to autotrophs and the handling of C1 compounds

Abstract The behaviour, functions and biosynthesis of c -type cytochromes of the bacterial periplasm are reviewed. Particular emphasis is placed on cytochromes involved in (i) the metabolism of C₁ compounds and (ii) the electron transport reactions of Paracoccus denitrificans .