Differences in lipoprotein composition between heads and tails of human sperm: an infrared spectroscopy study

Pitfalls and promises in FTIR spectromicroscopy analyses to monitor iron-mediated DNA damage in sperm

Many drugs, chemicals, and environmental factors can impair sperm functionality by inducing DNA damage, one of the important causes of reduced fertility potential. The use of vibrational spectromicroscopy represents a promising approach for monitoring DNA integrity in sperm, although some limitations exist, depending from the experimental conditions. Here, we report that when using FTIR spectromicroscopy to reveal oxidative stress mediated by Fenton's reaction on hydrated sperm samples, DNA damage interpretation is partially compromised by unexpected cell surface precipitates. The precipitates give a broad band in the 1150-1000cm(-1) infrared region, which partially covers one of the signatures of DNA (phosphate stretching bands), and are detected as iron and oxygen containing material when using XRF spectroscopy. On the other hand, the analyses further support the potential of FTIR spectromicroscopy to reveal cellular oxidative damage events such as lipid peroxidation, protein misfolding and aggregations, as well as DNA strain breaks.

Investigation of spermatozoa and seminal plasma by fourier transform infrared spectroscopy

Fourier transform infrared (FT-IR) spectra of human spermatozoa and seminal plasma were recorded and analyzed. The procedure that was established for sample preparation enabled acquisition of reproducible spectra. The parameter I(1087)/I(966) for controlling spectra reproducibility was defined. The assignment of bands was carried out using an empirical approach and the origin of the "sperm specific doublet", the bands at 968 cm(-1) and 981 cm(-1), was determined. The principal component regression (PCR) algorithm was used to define the specific spectral regions correlating to characteristics of spermatozoa, such as concentration, straight-line velocity (VSL), and beat cross frequency (BCF). Then, simple spectral parameters, such as band intensities and band ratios, were tested to determine which one best correlates to characteristics of spermatozoa. The region of the amide I band, between 1700 cm(-1) and 1590 cm(-1), was defined as a specific spectral region that correlates to the concentration of spermatozoa. The parameter that gave the linear dependence to the concentration of spermatozoa was the intensity of the amide I band. For VSL, the bands between 1119 cm(-1) and 943 cm(-1) were defined as the specific spectral region. The relative amount of nucleic acids with respect to proteins showed linear dependence on the straight-line velocity of spermatozoa. BCF showed the best correlation to the bands between 3678 cm(-1) and 2749 cm(-1), which largely represent lipids and proteins. These results suggest that FT-IR spectroscopy can serve as an adjunct to conventional histopathology studies.

Lethal and non-lethal responses of spermatozoa from a wide variety of vertebrates and invertebrates to lysenin, a protein from the coelomic fluid of the earthworm Eisenia foetida

Lysenin, a novel protein that we isolated from the coelomic fluid of the earthworm Eisenia foetida, binds specifically to sphingomyelin (SM) among various phospholipids found in cell membranes, and causes cytolysis. The plasma membrane of mammalian spermatozoa is known to contain SM at relatively high levels and we therefore examined the effects of lysenin on the spermatozoa of various animals. Lysenin had lethal effects on spermatozoa of 5 of 33 species of invertebrates tested and on spermatozoa of 30 of 39 species of vertebrates. We postulated that plasma membranes of the spermatozoa of most invertebrates might not contain SM whereas those of most vertebrate species might contain SM. These possibilities were supported by our failure to detect SM chemically in the testes of three species of invertebrates, in none of which spermatozoa responded to lysenin. In contrast, we detected SM in the testes of all 25 vertebrate species examined, irrespective of a negative or positive response of spermatozoa to lysenin. None of the six species of Protista examined was affected by lysenin. Our survey suggests that, in general, the spermatozoa of animals can be grouped into two categories, invertebrate and vertebrate, depending on the absence or presence of SM in their plasma membrane. The incorporation of SM into spermatozoa seems first to have occurred in protochordates during the course of evolution. Discussions about the exceptional responses to lysenin observed in the spermatozoa of five species of invertebrates and of nine species of vertebrates are made from phylogenetic and reproductive viewpoints. J. Exp. Zool. 286:538-549, 2000.