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Biomedical subjects

D Leach

Publications and source records attributed to D Leach.

At least 37 records · Page 2Linked to original sources
PubMed1983

The interaction of cos with Chi is separable from DNA packaging in recA-recBC-mediated recombination of bacteriophage lambda.

Chi (5'-GCTGGTGG) is a recombinator in RecA-RecBC-mediated recombination in Escherichia coli. In bacteriophage lambda vegetative recombination, Chi is fully active only when it is correctly oriented with respect to cos, the site that defines the ends of the packaged chromosome. Here we demonstrate that packaging from cos is not necessary for this cos-Chi interaction. Our evidence suggests that correctly oriented cos is an activator of Chi. cos, as an activator, is (1) dominant over cos-, (2) active opposite an extensive heterology, (3) able to interact with Chi only when on the same (cis) chromosome, and (4) able to interact with Chi at distances as far as greater than or equal to 20 kb. Thus, cos and Chi form a two-component recombinator system for general recombination. cos may serve as an asymmetric entry site for a recombination enzyme that recognizes Chi in an asymmetric way.

Bacteriophage lambda↗
PubMed1983

Annular gap junctions of the equine hoof wall.

Incidental to studies of keratinization of the equine hoof wall, annular gap junctions were found in the stratum spinosum of the intertubular horn of the stratum medium. Adjacent cells of the stratum spinosum showed extensive gap junctions, and often local invaginations of one cell into another were bound by gap junctions. It is proposed that these invaginations become detached from the cell surface to form the annular gap junctions. Formation of annular gap junctions may be a means of disposing of plasma membrane in response to changes in cell volume or shape occurring in keratinization. Interiorization of gap junctions may also facilitate cell movement, and perhaps may act to reorganize desmosome-tonofibril arrangements by budding off appropriate interdesmosomal areas, thus drawing the desmosomes closer to one another.

Animals↗
PubMed1979

The isolation and characterisation of a plaque-forming derivative of bacteriophage Mu carrying a fragment of Tn3 conferring ampicillin resistance.

We have isolated a plaque-forming derivative of phage Mu which carries a determinant for ApR. The biological properties of this MuAp phage are similar to those of normal Mu. Its genome contains a 1.1 kb substitution where Mu DNA from the right end of the G region has been replaced by a similar length of DNA from the transposon Tn3. This fragment of Tn3 DNA carries the ApR gene, but is no longer capable of independent transposition.

Ampicillin↗
PubMed1979

Comparative kinematic analysis of bipedal and quadrupedal locomotion: a cyclographic technique.

This paper shows the convention for, and applicability of, a new computer-aided cyclographic technique for kinematic analysis of locomotion in quadrupeds. Comparison is made of the walking, trotting and galloping patterns of a reference quadruped, Canis familiaris. The method is effective where an investigator required an accurate evaluation of limb movement in the cranio-caudal plane.

Adult↗
PubMedDate not supplied

Classroom and playground interaction of students with and without disabilities.

The classroom and playground behaviors of students with disabilities, in an integrated classroom, are frequently cited as reasons for rejection of these students by their regular-class peers. We compared the classroom and playground behavior of 95 students with mild disabilities with that of 95 students without disabilities, age and sex matched, and enrolled in the same classes. The children, age 8-13 years, attended state government elementary schools. Behaviors were observed using a time-sampling method with nine categories of behavior in each setting. The behavior of both groups of students was in many ways similar, regardless of the presence of disabilities.

Adolescent↗