Sperm metabolism is altered during storage by female insects: evidence from two-photon autofluorescence lifetime measurements in bedbugs.
We explore the possibility of characterizing sperm cells without the need to stain them using spectral and fluorescence lifetime analyses after multi-photon excitation in an insect model. The autofluorescence emission spectrum of sperm of the common bedbug, Cimex lectularius, was consistent with the presence of flavins and NAD(P)H. The mean fluorescence lifetimes showed smaller variation in sperm extracted from the male (tau m, τm = 1.54-1.84 ns) than in that extracted from the female sperm storage organ (tau m, τm = 1.26-2.00 ns). The fluorescence lifetime histograms revealed four peaks. These peaks (0.18, 0.92, 2.50 and 3.80 ns) suggest the presence of NAD(P)H and flavins and show that sperm metabolism can be characterized using fluorescence lifetime imaging. The difference in fluorescence lifetime variation between the sexes is consistent with the notion that female animals alter the metabolism of sperm cells during storage. It is not consistent, however, with the idea that sperm metabolism represents a sexually selected character that provides females with information about the male genotype.
Department of Animal Evolutionary Ecology, University of Tuebingen, Auf der Morgenstelle 28, 27076 Tuebingen, Germany Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK Applied Zoology, Department of Biology, Technische Universität Dresden, 01062 Dresden, Germany klaus.reinhardt@tu-dresden.de.
Klaus
K
Reinhardt
Department of Biophotonics and Laser Technology, Saarland University, Campus A5.1, 66123 Saarbrücken, Germany Jenlab GmbH, Schillerstrasse 1, 07745 Jena, and Science Park 2, Campus D1.2, 66123 Saarbrücken, Germany.
Hans Georg
HG
Breunig
Department of Biophotonics and Laser Technology, Saarland University, Campus A5.1, 66123 Saarbrücken, Germany Jenlab GmbH, Schillerstrasse 1, 07745 Jena, and Science Park 2, Campus D1.2, 66123 Saarbrücken, Germany.
Aisada
A
Uchugonova
Department of Biophotonics and Laser Technology, Saarland University, Campus A5.1, 66123 Saarbrücken, Germany Jenlab GmbH, Schillerstrasse 1, 07745 Jena, and Science Park 2, Campus D1.2, 66123 Saarbrücken, Germany.
Karsten
K
König
D000818:Animals; D001511:Bedbugs / Q000378:metabolism*; D002470:Cell Survival / Q000502:physiology; D005260:Female; D008297:Male; D009249:NADP / Q000378:metabolism*; D013094:Spermatozoa / Q000378:metabolism*
D009249:NADP
biophotonics; cell ageing; sexual selection; sperm competition; sperm metabolism