Age-related variation in lipophilic chemical compounds from femoral gland secretions of male lizards Psammodromus algirus

In spite of the importance of chemoreception in social organization of lizards, only a few studies have examined chemical composition of secretions of lizards. The secretion of the femoral glands of male lizards Psammodromus algirus contains 59 lipophilic compounds, mainly carboxylic acids between n-C₉ and n-C₂₀, and steroids (mainly campesterol, ergosterol and cholesterol), and minor components such as five alcohols, six aldehydes, squalene, α-tocopherol, ketones, and a furanone. These compounds were identified on the basis of mass spectra, obtained by GC–MS. Secretions of adult males of different age were different. Older lizards had secretions with relatively lower proportions of octadecadienoic, oleic and eicosatetraenoic acids, and higher proportions of campesterol, ergosterol, ergostenol, 4,4-dimethy-cholest-7-en-3-ol, and ergosta-5,22-dien-3-ol. These differences might allow conspecifics to get information on the age of the sender based on chemicals alone, which may have an important role in social behavior of this lizard.     

Lipophilic compounds in femoral secretions of male collared lizards,Crotaphytus bicinctores (Iguania,Crotaphytidae)

In many lizards, chemical compounds from the femoral gland secretions are used in intraspecific communication, but most studies describing these chemicals are for lizard species included in the Scleroglossa clade, whereas lizards within the Iguanian clade have been much less studied, probably because these lizards were considered to rely more on visual cues. However, many iguanian lizards have abundant femoral secretions and are able of chemosensory conspecific recognition, which might be based on compounds secreted by femoral glands. By using GC–MS analyses, we found 58 lipophilic compounds in femoral gland secretions of male Great Basin collared lizard, Crotaphytus bicinctores (Iguania, Crotaphytidae). Main compounds were steroids (mainly two triunsaturated steroids and cholesterol), carboxylic acids (mainly hexadecanoic acid), waxy esters of long chain fatty acids, alcohols (mainly hexadecanol), aldehydes and other minor compounds. We compared these compounds with those found in other lizard species and discussed the potential signaling function of some compounds and how the xeric habitat of this lizard could have conditioned the composition of secretions.     

Chemical composition of femoral secretions of oviparous and viviparous types of male common lizards Lacerta vivipara

In spite of the importance of chemoreception in intraspecific communication of lizards, only a few studies have examined chemical composition of secretions of lizards. The secretion of the femoral glands of adult male lizards Lacerta vivipara contains a relatively low number (18) of lipophilic compounds in comparison with other related lacertid lizards. These compounds were identified on the basis of mass spectra, obtained by GC-MS. Chemicals included ten steroids (mainly cholesterol) and four carboxylic acids between n-C₁₂ and n-C₁₈, and minor components such as squalene, α-tocopherol, and two waxy esters, which may contribute to avoid oxidation of other lipophilic components in the fairly humid environments occupied by this lizard. Secretions of adult males from oviparous and viviparous populations did not differ in the numbers and quality of chemical compounds, but there were some differences in the relative proportion of some compounds. Males from oviparous populations had lower proportions of hexadecanoic acid and cholestan-3-one, and higher proportions of squalene than viviparous males. These differences might be explained by either small genetic differences between types or due to different microclimatic conditions in the original populations.     

New compounds, sexual differences, and age-related variations in the femoral gland secretions of the lacertid lizard Acanthodactylus boskianus

Integumental gland secretions in lizards have been postulated to play a role as semiochemicals, but few studies have analysed the chemical nature of the gland secretions used in communication. We analysed the femoral gland secretions of Acanthodactylus boskianus using GC–MS, compared secretions of both sexes and different ages of males. For the first time in reptiles monoglycerides of fatty acids and glycerol monoethers of long chain alcohols were identified. In addition, alcohols, steroids, carboxylic acids, alkanes, amides, aldehydes, carboxylic acid esters, and squalene occurred. Sexual differences and age correlation in the amount of all major groups of compounds occurred, as such these results strengthen the theory that these secretions are used as semiochemicals. This work lays the foundations to test in future the role of chemical cues in mate choice and dominance hierarchies in lizards and to test the activity of compounds in behavioural assays to eventually identify the pheromones.     

Inter-island variation in femoral secretions of the Balearic lizard,Podarcis lilfordi (Lacertidae)

Many lizards use femoral gland secretions in intraspecific communication. Although there is a consistent interspecific variation in chemical composition of secretions, considerable variation is also often found between populations, which may affect conspecifc recognition and lead to speciation processes. Balearic lizards (Podarcis lilfordi) are currently distributed only in several isolated islets offshore of the main islands with different environmental conditions (vegetation, diet, density of population, etc). Also, there is a high genetic variability between populations. We examined whether there was a similar variation in the composition of the femoral secretions of male lizards, and which could be the causes of such variation. By using GC–MS analyses, we found 75 lipophilic compounds in femoral gland secretions of male P. lilfordi from three representative island populations. Main compounds were steroids (94.4%), mainly cholesterol, but we also found alkanes, ketones, waxy esters, squalene, carboxylic acids and their ethyl esters, alcohols and other minor compounds. However, there were clear differences between populations with respect to the number and relative proportions of compounds. Using the patterns of presence and abundance of compounds in secretions it is possible to predict the population of origin of a lizard. We discuss how these differences could be explained considering genetic and environmental differences between populations.     

Lipids in femoral gland secretions of male lizards, Psammodromus hispanicus

Many lizards produce chemical secretions that may be used as pheromones in reproductive behavior, but only a few studies have identified chemical compounds in secretions. By using GC–MS, we found only 20 lipophilic compounds in femoral glands secretion of male lizards, Psammodromus hispanicus. Main compounds were six steroids (mainly cholesterol and campesterol) and seven n-C₉ to n-C₁₈ carboxylic acids (especially dodecanoic acid), and minor components were six alcohols between C₁₆ and C₂₉ and squalene. We compared these chemicals with those previously found in secretions of the closely related sister species Psammodromus algirus and other lizard species.     

Age related differences in lipophilic compounds found in femoral gland secretions of male spiny-footed lizards, Acanthodactylus erythrurus

Although chemoreception plays an important role in social organization of many lizards, only a few studies have examined the chemicals found in secretions used for intraspecific communication. We report the composition of the secretion of the femoral glands of males of the spiny-footed lizard (Acanthodactylus erythrurus). On the basis of mass spectra, obtained by GC/MS, we identified 45 lipophilic compounds, including several alcohols ranging from 10 to 29 carbon atoms (mainly hexacosanol and tetracosanol), steroids (mainly cholesterol and dehydrocholesterol), n-C9 to n-C20 carboxylic acids, esters of carboxylic acids, and minor components such as lactones, ketones, squalene and a-tocopherol. Some of these compounds are reported for the first time in lizards. Adult and subadult males differed in the composition of secretions, with C9 to C15 carboxylic acids being more abundant in younger than in older lizards, whereas C16 to C20 carboxylic acids were more abundant in older lizards. Also, older lizards had significant lower proportions of cholesterol and campesterol but higher proportions of dehydrocholesterol.     

Chemical scent constituents in feces of wild Iberian wolves (Canis lupus signatus)

In spite of the importance of feces in scent marking and intraspecific chemical communication of many mammals, only a few studies have examined the chemical constituents of feces that could have a signaling function. We described here the chemicals found in feces recently deposited in the wild by adult and pup Iberian wolves (Canis lupus signatus). By means of analyses using gas chromatography–mass spectrometry (GC–MS), we identified 77 compounds in feces of adult wolves, mainly heterocyclic aromatic organic compounds, such as indole or phenol, but also steroids, such as cholesterol, carboxylic acids and their esters between n-C₃ and n-C₁₈, aldehydes, alcohols and significant quantities of squalene and α-tocopherol, which would increase the chemical stability of feces on humid substrates. Some of the odoriferous compounds are very likely originated in the anal-sac secretions, and later incorporated onto feces during defecation. However, the abundance of the main odoriferous compounds in feces could be explained by the result of the bacterial action on food components. Feces of pups only had 26 compounds, most of these were also found in adults’ feces, but four compounds were only found in pups’ feces, and there were also age-related differences respect to the proportions of shared chemicals. These differences could be partly due to the absence of anal-sac glands in pups, which would not need to scent mark substrates.     

Chemical constituents of the femoral gland secretions of male tegu lizards (Tupinambis merianae) (Family teiidae)

In spite of the importance of chemical signals (pheromones) in the reproductive behaviour of lizards, the chemical compounds secreted by their femoral glands, which may be used as sexual signals, are only known for a few lizard species. Based on mass spectra, obtained by GC-MS, we found 49 lipophilic compounds in femoral gland secretions of male tegu lizards (Tupinambis merianae) (fam. Teiidae), including a very high proportion of carboxylic acids and their esters ranging between n-C8 and n-C20 (mainly octadecanoic and 9,12-octadecadienoic acids), with much less proportions of steroids, tocopherol, aldehydes, and squalene. We discuss the potential function of these compounds in secretions, and compare the compounds found here with those documented for other lizard species.     

Chemical compounds from femoral gland secretions of male Iberian rock lizards, Lacerta monticola cyreni

In spite of the importance of chemoreception and chemical signals in the social organization of lizards, there are only a few studies examining the chemical composition of secretions of lizards used for scent marking. The secretion of the femoral glands of male Iberian rock lizards (Lacerta monticola cyreni) contains 44 lipophilic compounds, including several steroids (mainly cholesterol), and n-C6 to n-C22 carboxylic acids, and minor components such as esters of carboxylic acids, alcohols, squalene, and one lactone. These compounds were identified on the basis of mass spectra, obtained by GC-MS. Most lipids were detected in all individuals, although relative proportions of each chemical show a high interindividual variability. This variability might be related to the characteristics or physical and health condition of males and might be the basis of female choice based on chemical cues observed in this lizard species.     

A new sexual signal in rutting male red deer: Age related chemical scent constituents in the belly black spot

Rutting behaviour of red deer stags (Cervus elaphus) includes an extensive repertoire of visual and acoustic signals directed either to rival males or to females. As in other mammals, olfactory communication is expected to play a central role in these rutting interactions too, but this has rarely been investigated. Only during the rutting season, red deer males show a conspicuous black spot area throughout most of their underbelly produced by the impregnation of substances with a strong scent. Here, we examined the origin of these compounds and their potential role as chemical signals. By using gas chromatography–mass spectrometry (GC–MS), we identified 67 compounds in the hair from the belly black spot of red deer stags, mainly heterocyclic aromatic organic compounds, such as m-cresol, benzoic acid, cyclohexanecarboxylic acid and ethylphenol, but we also found steroids, such as cholesterol and androstane-3,17-dione, carboxylic acids and their esters between n-C₆ and n-C₂₂, alcohols, squalene and other minor compounds. Many of these compounds are found in the belly black spot but not in other hair areas, and may have originated from several sources, such as the urine or the sebaceous glands of the skin, which impregnated the belly. Moreover, we found differences in chemical profiles depending on age, with older males having higher proportions of benzoic acid and androstane-3,17-dione, but lower proportions of m-cresol. Because most of these compounds are strongly odoriferous, and appear related to male characteristics, our data indicate that scent from the hairs forming the black spot of the belly may be regarded as an overlooked new sexual chemical signal in red deer in the context of competition for mates during the rutting season.     

New chemicals from the dufour gland of the formicine ant Lasius niger (Hymenoptera:Formicidae)

A series of esters of C₈-C₁₃ fatty acids formed with C₁₀-C₁₂ straight chain alcohols, representing 3.7% of the glandular contents, was found in the Dufour gland of workers of the formicine ant Lasius niger. Altogether, nearly 50 components, among them hydrocarbons, alcohols, acetates and propionates were identified in the glandular liquid by means of gas chromatography (GC) and mass spectrometry (MS), using a solid injection technique. The wax esters and the propionates—decyl, dodecyl, octadecyl and farnesyl—have not been previously reported from ant secretions.     

Epicuticular waxes of two sorghum varieties

The epicuticular waxes of the two sorghum varieties Alliance A and SD 102 have been analyzed, after separation of the leaf blades from the sheaths. The major constituents were found to be free fatty acids but small amounts of esters, aldehydes, alcohols, n-alkanes and sterols were also detected. The typical chain lengths of aldehydes, free alcohols and free fatty acids were C₂₈ and C₃₀.     

Surface wax of Andreaea and Pogonatum species

The mosses Andreaea rupestris, Pogonatum aloides and P. urnigerum contain surface waxes in amounts of 0.05–0.12% dry wt. The waxes consisted of esters (C₃₈-C₅₄), primary alcohols (C₂₀-C₃₂), free fatty acids (C₁₆-C₃₀), and alkanes (C₂₁-C₃₁). Additionally, aldehydes (C₂₂-C₃₀) were major constituents in the wax of P. urnigerum. The classes and their chain length distributions in the surface waxes of these mosses are comparable to those of epicuticular waxes of higher plants.     

Differences in chemical signals may explain species recognition between an island lizard, Podarcis atrata, and related mainland lizards, P. hispanica

Chemical signals can be the basis of interspecific recognition and speciation in many animals. The Columbretes Islands wall lizard, Podarcis atrata is very close genetically to the mainland Iberian wall lizard Podarcis hispanica. However, a previous study suggested that chemosensory interspecific recognition would avoid reproductive interactions and hybridization between these two species. These results suggested that chemicals used in intraspecific communication might differ in composition and/or proportions between these two species. In this paper, we used gas chromatography–mass spectrometry (GC–MS) to characterize the chemical composition of the lipophilic fraction from femoral gland secretions of male P. atrata and P. hispanica. The analysis showed that chemicals found in femoral secretions varied in composition and proportions between species and between populations. Seven steroids and two unidentified waxy esters, were exclusive of P. atrata lizards from the islands. In contrast, nine steroids and other six compounds were only found in mainland P. hispanica. There were also differences in proportions of shared compounds between species. Moreover, all these differences were higher between P. atrata and P. hispanica than between any population of P. hispanica. Chemical differences might be consequence of genetic differences, but they could also be explained by adaptation to different habitats with different climatic conditions or diet resources. Compounds that are specific of each species, or differences in the pattern of compounds, could explain species recognition. Therefore, these results of chemical composition and previous studies of chemosensory recognition reinforce the fact that the genetic differences between P. hispanica and P. atrata may result in an effective reproductive isolation between these two taxa.     

Formation of volatile alcohols and esters from aldehydes in strawberries

The aldehydes acetaldehyde, propanal, 2-methylpropanal, butanal, 3-methylbutanal, pentanal and hexanal, were reduced to their corresponding alcohols by incubation with strawberry fruit. The alcohols formed were then converted to their acetate, propionate, n-butyrate, isovalerate and n-caproate esters during the incubation with strawberry fruit. Simultaneous reaction of isobutyric acid, n-valeric acid and isocaproic acid with aldehyde and strawberry fruit resulted in the formation of esters of these acids. In all seven alcohols and 54 esters were produced by means of incubation of aldehydes and volatile fatty acids with strawberry fruit.     

Composition of the epicuticular and intracuticular wax layers on Kalanchoe daigremontiana (Hamet et Perr. de la Bathie) leaves

Epicuticular and intracuticular waxes from both adaxial and abaxial surfaces of the leaves of Kalanchoe daigremontiana were analyzed. All wax mixtures were found to contain approximately equal amounts of triterpenoids and very long chain fatty acid (VLCFA) derivatives. The triterpenoid fraction consisted of glutinol (8-19% of the total wax) and friedelin (4-9%), together with smaller amounts of glutanol, glutinol acetate, epifriedelanol, germanicol and β-amyrin. The VLCFA derivatives comprised C₂₇-C₃₅ alkanes (19-37% of the total wax), C₃₂-C₃₄ aldehydes (3-7%), C₃₂ and C₃₄ fatty acids (0.2-3%), C₂₆-C₃₆ primary alcohols (4-8%), and C₄₂-C₅₂ alkyl esters (2-9%). The wax layers were found to differ in triterpenoid amounts, with the intracuticular wax containing higher percentages of most triterpenoids than the epicuticular wax. Friedelin, the only triterpenoid ketone present, showed the opposite distribution with higher proportions in the epicuticular wax. VLCFA derivatives also accumulated to higher percentages in the epicuticular than in the intracuticular wax layer. Epicuticular wax crystals were observed on both the adaxial and abaxial leaf surfaces.     

Vitamin E supplementation increases the attractiveness of males' scent for female European green lizards

Background

In spite that chemoreception is important in sexual selection for many animals, such as reptiles, the mechanisms that confer reliability to chemical signals are relatively unknown. European green lizards (Lacerta viridis) have substantial amounts of α-tocopherol ( = vitamin E) in their femoral secretions. Because vitamin E is metabolically important and can only be attained from the diet, its secretion is assumed to be costly. However, its role in intraspecific communication is unknown.

Methodology/Principal Findings

Here, we experimentally show that male European green lizards that received a dietary supplement of vitamin E increased proportions of vitamin E in their femoral secretions. Furthermore, our experiments revealed that females preferred to use areas scent marked by males with experimentally increased vitamin E levels in their secretions. Finally, female preferences were stronger when vitamin E differences between a pair of males'' secretions were larger.

Conclusions/Significance

Our results demonstrate that female green lizards are able to discriminate between males based on the vitamin E content of the males'' femoral secretions. We suggest that the possible cost of allocating vitamin E to secretions, which might be dependent on male quality, may be a mechanism that confers reliability to scent marks of green lizards and allows their evolution as sexual signals.     

Chemical Composition of Lipids from Peat-Forming Leafy Mosses of Eutrophic Swamps of Western Siberia and Altai

The molecular composition of lipids in three samples of leafy mosses (Aulacomnium palustre, Warnstorfia fluitans, and Calliergon giganteum) has been determined. The revealed acyclic compounds included normal and isoprenoid alkanes, isoprenoid alkenes, normal and isoprenoid ketones, carboxylic acids and their esters, alcohols, and aldehydes. Among cyclic compounds, bi-, tri- and tetracyclic polycycloaromatic hydrocarbons (PAHs), bicyclic and pentacyclic terpenoids, steroids and tocopherols have been observed. The identified organic compounds consisted mainly of carbocyclic acids and n-alkanes with the prevalence of C₂₇ homologues. A. palustre is characterized by a reduced content of isoprenoid compounds, alcohols, and ketones, while the content of unsaturated acids, pentacyclic terpenoids, and aldehydes is rather heightened. A. palustre differs from W. fluitans and C. giganteum in the steroid composition and contains eremophylene, a sesquiterpenoid, which is absent in the mosses of the family Amblystegiaceae. Compared to C. giganteum, W. fluitans has a higher content of lycopadiene, carboxylic acids, n-alkanes, phyt-2-ene, aldehydes, esters, squalene, diploptene, α-tocopherol, and triphenyl phosphates.     

Comparison of the organic compounds composition of Hylobius abietis males and females before and after exposure to Beauveria bassiana infection

In the present study, the lipid composition from male and female Hylobius abietis is analyzed pre- and post-infection with Beauveria bassiana. The compounds are analyzed by gas chromatography-mass spectrometry. In the lipids of males and females fatty acids, fatty acid methyl esters, alcohols, amino acids and other organic compounds are identified. The lipids of males and females after B. bassiana exposure contain 31 and 33 organic compounds, respectively, whereas the lipids of non-infected males and females contain 30 and 37 compounds, respectively. The most abundant compounds in infected and non-infected males are fatty acids: C16:0, C18:0, C18:1 and C18:2. Contents of dominant compounds from the lipids of infected and non-infected males are similar to those extracted from the lipids of infected and non-infected females. It should be noted that the total mass of organic compounds is higher in non-infected insects than infected insects.