Bacteriophage T4 DNA metabolism is largely insulated from that of its host, although some host functions assist in the repair of T4 DNA damage. Environmental factors sometimes affect survival and mutagenesis after ultraviolet (UV) irradiation of T4, and can affect mutagenesis in many organisms. We therefore tested the effect of certain environmental factors and host genetic defects upon spontan...

Bacteriophage T4 is able to adjust its development to the growth parameters of the host cell. Here, we present evidence for the production of two different subpopulations of phage particles, which differ in their ability to infect starved Escherichia coli cells. The ability of phage T4 to produce a fraction of virions unable to infect starved cells is linked to the functions of genes rI and rII...

Three independent parameters (eclipse and latent periods, and rate of ripening during the rise period) are essential and sufficient to describe bacteriophage development in its bacterial host. A general model to describe the classical "one-step growth" experiment [Rabinovitch et al. (1999a) J. Bacteriol.181, 1687-1683] allowed their calculations from experimental results obtained with T4 in Esc...

BACKGROUND & OBJECTIVES Acanthamoeba keratitis (AK) is a painful and vision-threatening ocular infection. The differentiation of Acanthamoeba at the species and subspecies level is complicated. Nearly all the AK isolates have been shown to belong to T4 genotype when analysed by ribosomal RNA gene sequences and there is no universally acceptable method for differentiation of different subtypes o...

Thyroxine (T4) enters the brain either directly across the blood-brain barrier (BBB) or indirectly via the choroid plexus (CP), which forms the blood-cerebrospinal fluid barrier (B-CSF-B). In this study, using isolated perfused CP of the sheep by single-circulation paired tracer and steady-state techniques, T4 transport mechanisms from blood into lateral ventricle CP has been characterized as t...

The transport of 125I-labeled thyroxine (T4) from the cerebrospinal fluid (CSF) into brain and choroid plexus (CP) was measured in anesthetized rabbit [0.5 mg/kg medetomidine (Domitor) and 10 mg/kg pentobarbitonal sodium (Sagatal) iv] using the ventriculocisternal (V-C) perfusion technique. 125I-labeled T4 contained in artificial CSF was continually perfused into the lateral ventricles for up t...

Mutants of Escherichia coli defective only in the biosynthesis of 5-methyluridine (ribothymidine) in their transfer ribonucleic acid (tRNA) were employed to investigate whether phage T4 induces its own tRNA(mV)methylase and whether T4-specific tRNA contains 5-methyluridine. The amounts of other methylated derivatives in the T4-specific tRNA were also determined. The results establish that T4-sp...

The comparative effects of equimolar doses of thyroxine (T4) and tri-iodothyronine (T3) were studied on fattening, gonadal status and moulting in thyroidectomized female spotted munia. The effects of suppression of peripheral conversion of T4 to T3 were also studied on these parameters. T4 administration led within 10 days to a significant regression of gonads and mobilization of fat, the respo...

Market-size (61-68 day-old) AA broiler chickens were exposed to simulated high-cyclic summer temperatures of North, Central and South China for 5 continuous days. Blood samples were collected at 0AM, 4AM, 8AM, 0PM, 4PM and 8PM each day, and concentrations of triiodothyronine (T3) and thyroxine (T4) were determined by double-antibody radioimmunoassay (RIA). T3, T4 concentration and T3/T4 ratio h...

The influence of puberty on sweating patterns of girls exercising in the heat is not known. Nine- to 17-year-old girls, representing 4 stages of breast development: T1 (n = 21); T2 (n = 22); T3 (n = 25); and T4 (n = 22), cycled for 20 min at 60% in 35 °C. The population density of heat activated sweat glands was higher in T1 vs T3 and T4 and in T2 vs T4. Sweat drop area was lower in T1 vs T3 an...