Makoto Kazama

Sea urchin spermatozoa generate at least two reactive oxygen species; the type of reactive oxygen species changes under different conditions.

Reactive oxygen species (ROS) cause oxidative stress and act as signal transduction molecules in many cells. Spermatozoa from several mammals generate ROS, which are involved in male infertility and signaling during capacitation. In the present study, we investigated ROS generation by sea urchin spermatozoa at the initiation of motility, during dilution with seawater, and following egg jelly treatment. In seawater containing an ROS indicator, 5‐(and 6‐)chloromethyl‐2′,7′‐dichlorodihydrofluorescein diacetate (CM‐H2DCFDA), fluorescence increased after the addition of spermatozoa. The ROS generation rate was dependent upon the dilution ratio and respiratory rate of the spermatozoa. Spermatozoa in sodium‐free seawater did not increase fluorescence, but fluorescence did increase with the addition of NaCl. Sodium chloride also led to the initiation of sperm motility and respiration. Using the indicator MitoSOX Red, ROS generation was detected from spermatozoa exposed to egg jelly dissolved in seawater, but not in normal seawater. Moreover, the respiratory inhibitor antimycin A prevented CM‐H2DCFDA‐detectable ROS and increased MitoSox‐detectable ROS at a higher concentration. These findings revealed that the ROS generated were of different species, possibly hydrogen peroxide (H2O2) and superoxide anion (

Species-dependent microarchitectural traits of iridescent scales in the triad taxa of Ornithoptera birdwing butterflies: Birdwing microarchitectural traits

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Fertilization induced changes in sea urchin sperm: Mitochondrial deformation and phosphatidylserine exposure

), and their detected levels were altered by egg jelly. We concluded that sea urchin spermatozoa generate at least two species of ROS depending on the physiological conditions to which they are exposed. It is possible that the major ROS from sea urchin spermatozoa changes during the course of fertilization. Mol. Reprod. Dev. 79: 283–295, 2012.

Spontaneous generation of reactive oxygen species and effect on motility and fertilizability of sea urchin spermatozoa

Ornithoptera birdwing butterflies have blue, green, or orange iridescent scales in different species or subspecies. To understand the species‐ or subspecies‐dependent scale color differences, we performed comparative morphometric analyses of iridescent scales from three closely related taxa: O. priamus priamus (green), O. priamus urvillianus (blue), and O. croesus (orange). The three types of Ornithoptera wings exhibited reversible color changes to longer wavelengths with different kinetics upon immersion in methanol, suggesting that their color differences are at least partly based on differences in the size of air cavities made by nanostructures. Cover scales of all three color types were visually semi‐transparent glass scales that exhibited color when placed on a dark background. The dorsoventral differences in coloration were observed in single scales, suggesting the optical importance of scale surfaces. Scanning electron microscopy of cover scales in cross section revealed that all color types exhibited finely sculpted tapered ridges and thick, irregular basal multilayers containing tandemly clustered granular objects and air cavities. Scale thickness, ridge height, and multilayer thickness were significantly different among the three color types, and granular object size was significantly different between orange scales and blue and green scales. We conclude that each of the three taxa of Ornithoptera butterflies possesses unique quantitative size values on tapered ridges and irregular multilayers with granular objects and air cavities to express unique structural color. These species‐ or subspecies‐dependent structural colors might have evolved via quantitative shifts in these microarchitectural traits rather than via changes in the basic developmental or architectural plan for color expression.