Stimulation of intrachromosomal homologous recombination in human cells by electroporation with site-specific endonucleases.

In somatic mammalian cells, homologous recombination is a rare event. To study the effects of chromosomal breaks on frequency of homologous recombination, site-specific endonucleases were introduced into human cells by electroporation. Cell lines with a partial duplication within the HPRT (hypoxanthine phosphoribosyltransferase) gene were created through gene targeting. Homologous intrachromosomal recombination between the repeated regions of the gene can reconstruct a functioning, wild-type gene. Treatment of these cells with the restriction endonuclease Xba I, which has a recognition site within the repeated region of HPRT homology, increased the frequency or homologous recombination bv more than 10-fold. Recombination frequency was similarly increased by treatment with the rare-cutting yeast endonuclease PI-Sce I when a cleavage site was placed within the repeated region of HPRT. In contrast, four restriction enzymes that cut at positions either outside of the repeated regions or between them produced no change in recombination frequency. The results suggest that homologous recombination between intrachromosomal repeats can be specifically initiated by a double-strand break occurring within regions of homology, consistent with the predictions of a model.

A close relative of the adrenoleukodystrophy (ALD) gene codes for a peroxisomal protein with a specific expression pattern.

Adrenoleukodystrophy (ALD), a severe demyelinating disease, is caused by mutations in a gene coding for a peroxisomal membrane protein (ALDP), which belongs to the superfamily of ATP binding cassette (ABC) transporters and has the structure of a half transporter. ALDP showed 38% sequence identity with another peroxisomal membrane protein, PMP70, up to now its closest homologue. We describe here the cloning and characterization of a mouse ALD-related gene (ALDR), which codes for a protein with 66% identity with ALDP and shares the same half transporter structure. The ALDR protein was overexpressed in COS cells and was found to be associated with the peroxisomes. The ALD and ALDR genes show overlapping but clearly distinct expression patterns in mouse and may thus play similar but nonequivalent roles. The ALDR gene, which appears highly conserved in man, is a candidate for being a modifier gene that could account for some of the extreme phenotypic variability of ALD. The ALDR gene is also a candidate for being implicated in one of the complementation groups of Zellweger syndrome, a genetically heterogeneous disorder of peroxisome biogenesis, rare cases of which were found to be associated with mutations in the PMP70 (PXMP1) gene.

Detection of membrane-bound HLA-G translated products with a specific monoclonal antibody.

A monomorphic anti-HLA-G monoclonal antibody (mAb) was obtained by immunization of HLA-B27/human beta 2-microglobulin double-transgenic mice with transfected murine L cells expressing both HLA-G and human beta 2-microglobulin. This mAb, designated BFL.1, specifically recognizes, by flow cytometry analysis, the immunizing HLA-G-expressing cells, whereas it does not bind to parental untransfected or to HLA-B7- and HLA-A3-transfected L cells, suggesting that it distinguishes between classical HLA-A and -B and nonclassical HLA-G class I molecules. This was further assessed by the absence of BFL.1 reactivity with a number of human cell lines known to express classical HLA class I proteins. In addition, we showed that the BFL.1 mAb also labels HLA-G-naturally-expressing JEG-3 and HLA-G-transfected JAR human choriocarcinoma cell lines as well as a subpopulation of first-trimester placental cytotrophoblast cells. Further biochemical studies were performed by immunoprecipitation of biotinylated membrane lysates: BFL.1, like the monomorphic W6/32 mAb, immunoprecipitated a 39-kDa protein in HLA-G-expressing cell lines, a size corresponding to the predicted full-length HLA-G1 isoform. However, in contrast to W6/32, which immunoprecipitates both classical and nonclassical HLA class I heavy chains, BFL.1 mAb does not recognize the class Ia products. Such a mAb should be a useful tool for analysis of HLA-G protein expression in various normal and pathological human tissues and for determination of the function(s) of translated HLA-G products.

Microcanonical finite-size scaling in second-order phase transitions with diverging specific heat

A microcanonical finite-size ansatz in terms of quantities measurable in a finite lattice allows extending phenomenological renormalization the so-called quotients method to the microcanonical ensemble. The ansatz is tested numerically in two models where the canonical specific heat diverges at criticality, thus implying Fisher renormalization of the critical exponents: the three-dimensional ferromagnetic Ising model and the two-dimensional four-state Potts model (where large logarithmic corrections are known to occur in the canonical ensemble). A recently proposed microcanonical cluster method allows simulating systems as large as L = 1024 Potts or L= 128 (Ising). The quotients method provides accurate determinations of the anomalous dimension, η, and of the (Fisher-renormalized) thermal ν exponent. While in the Ising model the numerical agreement with our theoretical expectations is very good, in the Potts case, we need to carefully incorporate logarithmic corrections to the microcanonical ansatz in order to rationalize our data.

Institutional bases for control of nonpoint source pollution under the Clean Water Act, with emphasis on agricultural nonpoint sources /

Mode of access: Internet.

Ocean and river gardens : a history of the marine and fresh-water aquaria, with the best methods for their establishment and preservation ...

Pt. II has title: River gardens; being an account of the best methods of cultivating fresh water plants in aquaria.

Some French poets of to-day : a commentary with specimens /

Caption title: Some modern French poets.

Measuring directional velocity in water waves with an acoustic flowmeter /

"April 1970."

Checking the correctness of water analyses with freezing point depressions,

Bibliography: leaf 54.

The turbulent boundary layer with variable Prandtl number.

Mode of access: Internet.

Water heating; a reference book on the application of gas for water heating, with special reference to large volume water uses.

Mode of access: Internet.

Annotated bibliography on the effects of irrigation practices on stream water quality with emphasis on salinity and pesticides /

Mode of access: Internet.

Automata by al-Jazari, The face of a water clock with Zodiac signs, folio from the Kitab fi ma'arifat al-hiyal al-handisaya (the book of knowledge of ingenious mechanical devices) Automata by al-Jazari

1 ft. 13/32 in.x 8 5/8 in.; ink, opaque watercolor and gold on paper

A Total exposure and risk assessment for drinking water contaminated with volatile organic compounds : final report /

"Printed: December 1987."

Restoring Illinois water quality with TMDLs.

The establishment of a Total Maximum Daily Load sets the pollutant reduction goal necessary to improve impaired waters. It determines the load, or quantity of any given pollutant that can be allowed in a particular water body. A TDML must consider all potential sources of pollutants whether point or nonpoint. It also takes into account a margin of safety, which reflects scientific uncertainty, as well as the effects of seasonal variation.