Electric field detection of phase-locked near-infrared pulses using photoconductive antenna.

We have demonstrated that a photoconductive antenna gated with 5-fs ultrashort laser pulses can detect electric field transients of near-infrared pulses at least up to 180 THz. Measured sensitivity spectrum of the antenna shows a good agreement with a simple calculation, demonstrating the promising capability of the antenna to near infrared spectroscopy. Using this setup, near-infrared time-domain spectroscopy and characterization of phase controlled near-infrared pulses are demonstrated. Observed absorption spectrum of a polystyrene film and complex refractive index dispersion of a fused silica plate both agree well with those obtained by the conventional methods.

Differences in the DNA-stainability of spermatozoa from fertile and suspected infertile men.

The aim of this work was to determine whether it is possible to distinguish between fertile (control group, already fathers) and infertile men (suspected infertility), by comparing the fluorescence intensity of the sperm-DNA after incubation with appropriate dyes. First we examined two different DNA-specific dyes (DAPI and YOYO-1) using bull spermatozoa. Based on good results in immunohistochemical applications, YOYO-1 was chosen for further work. The fluorescence-intensity of 200 single, morphologically normal spermatozoa in each semen sample were measured in a cytophotometer, means + SD determined and histograms delineated. Of 20 samples from the control group, 17 had markedly higher fluorescence-intensity than did 7/15 of the suspected infertile men. It is concluded that the DNA of the latter seven samples was less accessible to the dye than was the DNA of the control group. There are cases of infertility known in which there is loss of one or more of the DNA-binding proteins, which in spermatozoa are mainly (85%) protamines. The relationship between the stainability of the sperm-DNA and the packaging with DNA-binding proteins is discussed. Two of the histograms showed abnormalities in the distribution of the fluorescence-intensities, one sample was extremely fragile and most of the sperm lysed during the staining-procedure. Five samples showed normal histograms in comparison with the control group.

Parvalbumin-immunoreactive proteins in the nervous system of planarians.

1. Using immunological methods, we have identified parvalbumin-like material in the triclade flatworms, Polycelis nigra, Polycelis auriculata, Crenobia alpina, Dugesia tahitiensis, and Dugesia polychroa. 2. Western immunoblot analysis of these five species revealed heat stable parvalbumin-immunoreactive proteins between 32 kD and 44 kD. 3. Proteins at 19 and 32 kD revealed intense labeling with 45Ca2+. 4. Double immunodiffusion of planarian supernatants showed complete fusion of precipitates, indicating immunological relatedness of the parvalbumin-like material among the species investigated. 5. Immunocytochemical studies exhibit parvalbumin-immunoreactive material exclusively in neurons supporting the notion of an early evolutionary appearance of these proteins in the nervous system.