Complete Genome Sequence of Escherichia Phage Lw1, a New Member of the RB43 Group of Pseudo T-Even Bacteriophages.

RB43-related bacteriophages have a specific genome type that clearly distinguishes them from other T4-like viruses. Here, we present the complete genome sequence of a new virulent phage, Lw1, isolated as an Escherichia coli BL21(DE3) contaminant. Lw1 shares an RB43-like genome organization, but it does not contain putative AP2-domain endonuclease genes.

Requirement for N-cadherin-catenin complex in heart development.

Cell adhesion, mediated by N-cadherin, is critical for embryogenesis since N-cadherin-null embryos die during mid-gestation with multiple developmental defects. To investigate the role of N-cadherin in heart muscle development, N-cadherin was specifically deleted from myocardial cells in mice. The structural integrity of the myocardial cell wall was compromised in the N-cadherin mutant embryos, leading to a malformed heart and a delay in embryonic development.

N-cadherin is dispensable for pancreas development but required for beta-cell granule turnover.

The cadherin family of cell adhesion molecules mediates adhesive interactions that are required for the formation and maintenance of tissues. Previously, we demonstrated that N-cadherin, which is required for numerous morphogenetic processes, is expressed in the pancreatic epithelium at E9.5, but later becomes restricted to endocrine aggregates in mice.

The promoter of the oocyte-specific gene, Gdf9, is active in population of cultured mouse embryonic stem cells with an oocyte-like phenotype.

The study of germ cell-specific gene regulation in vitro is challenging. Here we report that the promoter of the oocyte-specific gene, Gdf9, is active in a population of cultured murine embryonic stem cells (ES) which have a phenotype resembling oocytes. The promoter region of the murine Gdf9 coupled to enhanced green fluorescent protein (eGFP) was stably transfected into XX mouse ES cells.

Expression profile of male germ cell-associated genes in mouse embryonic stem cell cultures treated with all-trans retinoic acid and testosterone.

Cells that morphologically and functionally resemble male germ cells can be spontaneously derived from ES cells. However, this process is inefficient and unpredictable suggesting that the expression pattern of male germ cell associated genes during spontaneous ES cell differentiation does not mimic the in vivo profiles of the genes. Thus, in the present study, the temporal profile of genes expressed at different stages of male germ cell development was examined in differentiating ES cells.

Deficiency of SPAG16L causes male infertility associated with impaired sperm motility.

The axonemes of cilia and flagella contain a "9+2" structure of microtubules and associated proteins. Proteins associated with the central doublet pair have been identified in Chlamydomonas that result in motility defects when mutated. The murine orthologue of the Chlamydomonas PF20 gene, sperm-associated antigen 16 (Spag16), encodes two proteins of M(r) approximately 71 x 10(3) (SPAG16L) and M(r) approximately 35 x 10(3) (SPAG16S).

Cardiac-specific loss of N-cadherin leads to alteration in connexins with conduction slowing and arrhythmogenesis.

The remodeling of ventricular gap junctions, as defined by changes in size, distribution, or function, is a prominent feature of diseased myocardium. However, the regulation of assembly and maintenance of gap junctions remains poorly understood. To investigate N-cadherin function in the adult myocardium, we used a floxed N-cadherin gene in conjunction with a cardiac-specific tamoxifen-inducible Cre transgene.

Induced deletion of the N-cadherin gene in the heart leads to dissolution of the intercalated disc structure.

The structural integrity of the heart is maintained by the end-to-end connection between the myocytes called the intercalated disc. The intercalated disc contains different junctional complexes that enable the myocardium to function as a syncytium. One of the junctional complexes, the zonula adherens or adherens junction, consists of the cell adhesion molecule, N-cadherin, which mediates strong homophilic cell-cell adhesion via linkage to the actin cytoskeleton.

N-cadherin is not essential for limb mesenchymal chondrogenesis.

The cell adhesion molecule N-cadherin is implicated in many morphogenetic processes, including mesenchyme condensation during limb development. To further understand N-cadherin function, we characterized a new N-cadherin allele containing the lacZ reporter gene under the regulation of the mouse N-cadherin promoter. The reporter gene recapitulates the expression pattern of the N-cadherin gene, including expression in heart, neural tube, and somites.

Haploinsufficiency for the murine orthologue of Chlamydomonas PF20 disrupts spermatogenesis.

PF20 was first identified in Chlamydomonas rheinhardtii as an essential component of the axoneme central apparatus. We discovered that the mouse Pf20 gene encodes two major transcripts (2.5 and 1.

Targeted mutation of the MLN64 START domain causes only modest alterations in cellular sterol metabolism.

The StAR-related lipid transfer (START) domain, first identified in the steroidogenic acute regulatory protein (StAR), is involved in the intracellular trafficking of lipids. Sixteen mammalian START domain-containing proteins have been identified to date. StAR, a protein targeted to mitochondria, stimulates the movement of cholesterol from the outer to the inner mitochondrial membranes, where it is metabolized into pregnenolone in steroidogenic cells.

Inappropriate P-cadherin expression in the mouse mammary epithelium is compatible with normal mammary gland function.

Cadherins comprise a family of cell-cell adhesion proteins critical to the architecture and function of tissues. Expression of family members E-, N-, and P-cadherin is regulated in a spatial and temporal fashion in the developing and adult organism. Using in vivo and in vitro experimental systems, perturbation of cadherin expression by genetic deletion, overexpression, mutant dominant-negative constructs, and, to a lesser degree, expression of an inappropriate cadherin have all been shown to alter embryogenesis, tissue architecture, and cell behavior.

Male infertility, impaired sperm motility, and hydrocephalus in mice deficient in sperm-associated antigen 6.

Gene targeting was used to create mice lacking sperm-associated antigen 6 (Spag6), the murine orthologue of Chlamydomonas PF16, an axonemal protein containing eight armadillo repeats predicted to be important for flagellar motility and stability of the axoneme central apparatus. Within 8 weeks of birth, approximately 50% of Spag6-deficient animals died with hydrocephalus. Spag6-deficient males surviving to maturity were infertile.

Differential adhesion leads to segregation and exclusion of N-cadherin-deficient cells in chimeric embryos.

Cadherin-mediated cell-cell interactions are thought to be critical in controlling cell sorting during embryogenesis. Here, we report that chimeric embryos generated with N-cadherin-deficient (N-cadherin(-/-)) embryonic stem cells develop further than embryos completely lacking N-cadherin only when the myocardium consists of N-cadherin-positive cells. Initially, the N-cadherin-negative and -positive cells mix together to form chimeric tissues; however, by embryonic day 9.

Rescuing the N-cadherin knockout by cardiac-specific expression of N- or E-cadherin.

Cell-cell adhesion mediated by some members of the cadherin family is essential for embryonic survival. The N-cadherin-null embryo dies during mid-gestation, with multiple developmental defects. We show that N-cadherin-null embryos expressing cadherins using muscle-specific promoters, alpha- or beta-myosin heavy chain, are partially rescued.

Retinoid signaling is required to complete the vertebrate cardiac left/right asymmetry pathway.

Vitamin A-deficient (VAD) quail embryos have severe abnormalities, including a high incidence of reversed cardiac situs. Using this model we examined in vivo the physiological function of vitamin A in the left/right (L/R) cardiac asymmetry pathway. Molecular analysis reveals the expression of early asymmetry genes activin receptor IIa, sonic hedgehog, Caronte, Lefty-1, and Fgf8 to be unaffected by the lack of retinoids, while expression of the downstream genes nodal-related, snail-related (cSnR), and Pitx2 is altered.

Retinoid signaling required for normal heart development regulates GATA-4 in a pathway distinct from cardiomyocyte differentiation.

Vitamin A is essential for normal embryonic cardiogenesis. The vitamin A-deficient phenotype in the avian embryo includes an abnormal heart tube closed at the sinus venosus and the absence of large vessels that normally connect the embryonic heart to the developing circulatory system. In vitamin A-deficient embryos the expression of cardiomyocyte differentiation genes, including atrial-specific myosin heavy chain, ventricular-specific myosin, and sarcomeric myosins as well as the putative cardiomyocyte specification gene Nkx-2.

Initial retinoid requirement for early avian development coincides with retinoid receptor coexpression in the precardiac fields and induction of normal cardiovascular development.

Vitamin A requirement for early embryonic development is clearly evident in the gross cardiovascular and central nervous system abnormalities and an early death of the vitamin A-deficient quail embryo. This retinoid knockout model system was used to examine the biological activity of various natural retinoids in early cardiovascular development. We demonstrate that all-trans-, 9-cis-, 4-oxo-, and didehydroretinoic acids, and didehydroretinol and all-trans-retinol induce and maintain normal cardiovascular development as well as induce expression of the retinoic acid receptor beta2 in the vitamin A-deficient quail embryo.

Vitamin A-deficient quail embryos have half a hindbrain and other neural defects.

Background: Retinoic acid (RA) is a morphogenetically active signalling molecule thought to be involved in the development of severely embryonic systems (based on its effect when applied in excess and the fact that it can be detected endogenously in embryos). Here, we adopt a novel approach and use the vitamin A-deficient (A-) quail embryo to ask what defects these embryos show when they develop in the absence of RA, with particular reference to the nervous system.

Results: We have examined the anatomy, the expression domains of a variety of genes and the immunoreactivity to several antibodies in these A- embryos.

[A diagnostic analysis of a genetic mutation associated with a deficiency of leukocyte adhesion in cattle].

Bovine leukocyte adhesion (BLAD) is a recessive autosomal disease in Holstein-Friesian cattle caused by point mutation in CD18 gene encoding neutrophil-surface glycoprotein. To determine BLAD carriers, the convenient primers were chosen to amplify the mutant region of gene with the following restriction analysis. A screening program for BLAD has been initiated.

Vitamin A deficiency and the expression of retinoic acid receptors during early cardiogenesis in quail embryo.

The vitamin A deficiency-associated lethal syndrome observed in avian embryos may be linked to dysfunction of vitamin A-dependent genes. We tested this hypothesis in a quail embryo model by examining the expression of retinoic acid receptors (RARs) and cytosolic retinoic acid binding protein (CRABP) in normal and vitamin A-deficient embryos during early development. RARα and RARγ mRNA were expressed at the same level in normal and vitamin A-deficient embryos during all stages studied.

Hensen's node from vitamin A-deficient quail embryo induces chick limb bud duplication and retains its normal asymmetric expression of Sonic hedgehog (Shh).

Both Hensen's node, the organizer center in chick embryo, and exogenous retinoic acid are known to induce limb duplication when grafted or applied to the host chick limb bud. Retinoic acid is known to be present in the node and has been proposed as the putative morphogen for chick limb development. Here, we report that Hensen's node from vitamin A-deficient quail embryo induces limb duplication in the host chick embryo similar to that induced by the node from vitamin A-sufficient control embryos.

Comparative study of Msx-1 expression in early normal and vitamin A-deficient avian embryos.

Homeobox-containing genes may play an important role in establishing embryonic patterns during development of vertebrates. Retinoic acid is able to induce expression of Hox genes in cells in culture and to alter expression patterns in the developing vertebrate embryos. Using wholemount in situ hybridization, we have examined and compared the expression patterns of a homeobox-containing gene, Msx-1, in early normal and vitamin A-deficient quail embryos.

[The mutagenic activity of the DNA of recombinant plasmids in a competent Bacillus subtilis culture].

The method for testing foreign plasmid DNA mutagenicity on the competent culture of B. subtilis has been developed. High mutagenic effect of DNA of recombinant plasmids carrying a single human Alu-repeat or the same repeat in combination with human apoAi gene or human insulin gene was demonstrated.

[The induction of mutations in 6-mercaptopurine resistance in Chinese hamster cells under the action of the recombinant plasmid pAins containing the human insulin gene].

The mutagenic activity of the pUC19 bacterial plasmid DNA and the pAins recombinant plasmid DNA carrying human insulin gene has been investigated. Both pUC19 and pAins plasmid DNAs have been shown to induce the gene mutations in hprt locus of Chinese hamster cell line. The high level of the gene mutations (similar to the indices of the gene mutations induced by the chemical mutagens) has been in the focus of attention.