Polymorphisms for melanic form of insects may provide various selective advantages.However,melanic alleles may have significant/subtle pleiotrophic“costs.”Several potential pleiotrophic effects of the W(=Y)‐linked ...Polymorphisms for melanic form of insects may provide various selective advantages.However,melanic alleles may have significant/subtle pleiotrophic“costs.”Several potential pleiotrophic effects of the W(=Y)‐linked melanism gene in Papilio glaucus L.(Lepidoptera)showed no costs for melanic versus yellow in adult size,oviposition preferences,fecundity,egg viability,larval survival/growth rates,cold stress tolerance,or postdiapause emergence times.Sexual selection(males choosing yellow rather than mimetic dark females)had been suggested to provide a balanced polymorphism in P.glaucus,but spermatophore counts in wild females and direct field tethering studies of size‐matched pairs of virgin females(dark and yellow),show that male preferences are random or frequency‐dependent from Florida to Michigan,providing no yellow counter‐advantages.Recent frequency declines of dark(melanic/mimetic)females in P.glaucus populations are shown in several major populations from Florida(27.3°N latitude)to Ohio(38.5°N).Summer temperatures have increased significantly at all these locations during this time(1999–2018),but whether dark morphs may be more vulnerable(in any stage)to such climate warming remains to be determined.Additional potential reasons for the frequency declines in mimetic females are discussed:(i)genetic introgression of Z‐linked melanism suppressor genes from P.canadensis(R&J)and the hybrid species,P.appalachiensis(Pavulaan&Wright),(ii)differential developmental incompatibilities,or Haldane effects,known to occur in hybrids,(iii)selection against intermediately melanic(“dusty”)females(with the W‐linked melanic gene,b+)which higher temperatures can cause.展开更多
Melanization/pigmentation is an important physiological phenomenon in insects,which is involved incuticular tanning,parasite encapsulation,and egg shell hardening.During the past few years,we have beenusing mosquito e...Melanization/pigmentation is an important physiological phenomenon in insects,which is involved incuticular tanning,parasite encapsulation,and egg shell hardening.During the past few years,we have beenusing mosquito eggs as a model to study the detailed biochemistry of melanization reactions in mosquitoes.Chorion of newly oviposited eggs is white and soft,but the chorion becomes black and hard within 3～4 hfollowing oviposition. Once the chorion turns black,the eggs become resistant to desiccation and solubiliza-tion.Floodwater mosquitoes,such as Aedes aegypti,oviposit on substrates at the edge of water and theeggs hatch only after being flooded with water following adequate rainfall.Consequently,the ability towithstand the desiccation and other environmental adversities is critical for egg survival.Our research deal-ing with chorion melanization in mosquitoes is aimed at understanding the biochemical processes and mech-展开更多
The anodic polarization curves of chromate zinc plates were studied under the condition of with and without illumination. It is found that the chromate film of zinc plate is characterized by an n type semi conductive ...The anodic polarization curves of chromate zinc plates were studied under the condition of with and without illumination. It is found that the chromate film of zinc plate is characterized by an n type semi conductive property. The illumination on the surface and the addition of Pb in the surface raises the anodic photocurrent and plays a part of the n type property in the film. Contrarily, Ag in the film plays a part of the p type dopant. The effects of quantitative Pb 2+ and Ag + in bath on the melanization(black patina) of zinc plate after chromate treatment also has been studied by comparing the lightness differences Δ L by means of a whiteness meter. It is found that the lightness decreasing process (the melanization rate) is consistent with the Wagner equation Δ L =kt 1/2 +C, and that Pb in the film increases k , on the other hand, Ag in the film decreases k of the melanizing rate.[展开更多
Melanization is harmful to the lightness of galvanized steel surface and also reduces the bonding force between a paint coat and the steel sheet. Experimental results showed that the hypothesis of Zn-Pb codeposition d...Melanization is harmful to the lightness of galvanized steel surface and also reduces the bonding force between a paint coat and the steel sheet. Experimental results showed that the hypothesis of Zn-Pb codeposition does not hold true, while the fact that PbSO4 micelles in sulfate bath settle on the coating surface support the second hypothesis. The authors come to the conclusions that (1) Any measure to eliminate PbSO4 micelles before or after passivation of the coating will prevent melanization; (2) PbSO4 micelles adsorbed on the surface of passivated film promote the growth of oxygen-deficient Zn oxide and result in the generation of melanization.展开更多
基金This research was supported in part by the College of Natural Science and the Michigan Agricultural Experiment Station(Project#1644)the National Science Foundation(DEB 9201122,DEB 9981608,DEB-0716683,and DEB 0918879)。
文摘Polymorphisms for melanic form of insects may provide various selective advantages.However,melanic alleles may have significant/subtle pleiotrophic“costs.”Several potential pleiotrophic effects of the W(=Y)‐linked melanism gene in Papilio glaucus L.(Lepidoptera)showed no costs for melanic versus yellow in adult size,oviposition preferences,fecundity,egg viability,larval survival/growth rates,cold stress tolerance,or postdiapause emergence times.Sexual selection(males choosing yellow rather than mimetic dark females)had been suggested to provide a balanced polymorphism in P.glaucus,but spermatophore counts in wild females and direct field tethering studies of size‐matched pairs of virgin females(dark and yellow),show that male preferences are random or frequency‐dependent from Florida to Michigan,providing no yellow counter‐advantages.Recent frequency declines of dark(melanic/mimetic)females in P.glaucus populations are shown in several major populations from Florida(27.3°N latitude)to Ohio(38.5°N).Summer temperatures have increased significantly at all these locations during this time(1999–2018),but whether dark morphs may be more vulnerable(in any stage)to such climate warming remains to be determined.Additional potential reasons for the frequency declines in mimetic females are discussed:(i)genetic introgression of Z‐linked melanism suppressor genes from P.canadensis(R&J)and the hybrid species,P.appalachiensis(Pavulaan&Wright),(ii)differential developmental incompatibilities,or Haldane effects,known to occur in hybrids,(iii)selection against intermediately melanic(“dusty”)females(with the W‐linked melanic gene,b+)which higher temperatures can cause.
文摘Melanization/pigmentation is an important physiological phenomenon in insects,which is involved incuticular tanning,parasite encapsulation,and egg shell hardening.During the past few years,we have beenusing mosquito eggs as a model to study the detailed biochemistry of melanization reactions in mosquitoes.Chorion of newly oviposited eggs is white and soft,but the chorion becomes black and hard within 3～4 hfollowing oviposition. Once the chorion turns black,the eggs become resistant to desiccation and solubiliza-tion.Floodwater mosquitoes,such as Aedes aegypti,oviposit on substrates at the edge of water and theeggs hatch only after being flooded with water following adequate rainfall.Consequently,the ability towithstand the desiccation and other environmental adversities is critical for egg survival.Our research deal-ing with chorion melanization in mosquitoes is aimed at understanding the biochemical processes and mech-
文摘The anodic polarization curves of chromate zinc plates were studied under the condition of with and without illumination. It is found that the chromate film of zinc plate is characterized by an n type semi conductive property. The illumination on the surface and the addition of Pb in the surface raises the anodic photocurrent and plays a part of the n type property in the film. Contrarily, Ag in the film plays a part of the p type dopant. The effects of quantitative Pb 2+ and Ag + in bath on the melanization(black patina) of zinc plate after chromate treatment also has been studied by comparing the lightness differences Δ L by means of a whiteness meter. It is found that the lightness decreasing process (the melanization rate) is consistent with the Wagner equation Δ L =kt 1/2 +C, and that Pb in the film increases k , on the other hand, Ag in the film decreases k of the melanizing rate.[
基金Tlle work was financially supported by ShanghaiBaoshan Steel Company.
文摘Melanization is harmful to the lightness of galvanized steel surface and also reduces the bonding force between a paint coat and the steel sheet. Experimental results showed that the hypothesis of Zn-Pb codeposition does not hold true, while the fact that PbSO4 micelles in sulfate bath settle on the coating surface support the second hypothesis. The authors come to the conclusions that (1) Any measure to eliminate PbSO4 micelles before or after passivation of the coating will prevent melanization; (2) PbSO4 micelles adsorbed on the surface of passivated film promote the growth of oxygen-deficient Zn oxide and result in the generation of melanization.
