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41.
Sabine Kirner Philip E. Hammer D. Steven Hill Annett Altmann Ilona Fischer Laura J. Weislo Mike Lanahan Karl-Heinz van Pée James M. Ligon 《Journal of bacteriology》1998,180(7):1939-1943
Pyrrolnitrin is a secondary metabolite derived from tryptophan and has strong antifungal activity. Recently we described four genes, prnABCD, from Pseudomonas fluorescens that encode the biosynthesis of pyrrolnitrin. In the work presented here, we describe the function of each prn gene product. The four genes encode proteins identical in size and serology to proteins present in wild-type Pseudomonas fluorescens, but absent from a mutant from which the entire prn gene region had been deleted. The prnA gene product catalyzes the chlorination of l-tryptophan to form 7-chloro-l-tryptophan. The prnB gene product catalyzes a ring rearrangement and decarboxylation to convert 7-chloro-l-tryptophan to monodechloroaminopyrrolnitrin. The prnC gene product chlorinates monodechloroaminopyrrolnitrin at the 3 position to form aminopyrrolnitrin. The prnD gene product catalyzes the oxidation of the amino group of aminopyrrolnitrin to a nitro group to form pyrrolnitrin. The organization of the prn genes in the operon is identical to the order of the reactions in the biosynthetic pathway.The antibiotic pyrrolnitrin [3-chloro-4-(2′-nitro-3′-chlorophenyl)pyrrole] (PRN) is produced by many pseudomonads and has broad-spectrum antifungal activity (1, 5, 12–14, 17). PRN has been implicated as an important mechanism of biological control of fungal plant pathogens by several Pseudomonas strains (12–14), including P. fluorescens BL915, from which the prn genes were isolated (10).Tryptophan was identified as the precursor for PRN, based on the feeding of cultures with isotopically labeled and substituted tryptophan (2, 7, 8, 17, 25). Biosynthetic pathways were proposed as early as 1967 (7) and have been refined on the basis of tracer studies and the isolation of intermediates (Fig. (Fig.1)1) (2, 8, 17, 19, 23, 25). Recently, Hammer et al. (9) described the cloning and characterization of a 5.8-kb DNA region which encodes the PRN biosynthetic pathway. This DNA region confers the ability to produce PRN when expressed heterologously in Escherichia coli and contains four genes, prnABCD, each of which is required for PRN production. In the research described here, we used mutants in which each of the four genes was disrupted and strains which overexpress the individual genes to elucidate the function of each gene product in PRN biosynthesis. Open in a separate windowFIG. 1Biosynthetic pathways for PRN as proposed by van Pée et al. (23) (A) and by Chang et al. (2) (B). The reactions catalyzed by the PRN biosynthetic enzymes encoded by the prnABCD genes are indicated above the appropriate reaction arrows.
Open in a separate window
Open in a separate windowa+, PRN detected; −, PRN not detected. Hohaus et al. (11) presented additional evidence of the chlorinating activity of the prnA gene product, specifically, the chlorination of l-tryptophan to form 7-CLT by cell extracts from P. fluorescens strains which expressed the prnA gene, but which did not contain any of the other prn genes. To clarify which isomer was produced, Hohaus et al. (11) extracted 7-CLT from the bacteria and oxidized it to the corresponding indole-3-pyruvic acid with amino acid oxidases. Since the isolated 7-CLT was degraded by l-amino acid oxidase, but not by d-amino acid oxidase (11), it must be in the l configuration. The deduced amino acid sequence for prnA contains a consensus NAD binding site (9), and, indeed, NADH is a required cofactor for the prnA gene product.Cultures of BL915ΔORF2 produced 7-CLT, but 7-chloro-d-tryptophan (11) and other PRN biosynthetic intermediates were not detected (Fig. (Fig.3).3). BL915ΔORF2 produced PRN when supplied with exogenous MDA or APRN, but not when supplied with 7-CT (Table (Table2).2). When prnB was expressed in strain BL915ΔORF1–4, exogenously supplied 7-CT was converted to MDA (Fig. (Fig.4).4). These results indicate that the prnB gene product catalyzes the rearrangement of the indole ring to a phenylpyrrole and the decarboxylation of 7-CLT to convert 7-CLT to MDA. While it is somewhat surprising that a single enzyme carries out both the ring rearrangement and decarboxylation, Chang et al. (2) postulated a mechanism for such a reaction on a single enzyme some 16 years ago. The prnB gene product also catalyzed the production of APP (Fig. (Fig.4),4), presumably by using tryptophan as a substrate. Open in a separate windowFIG. 4In vivo conversion of PRN biosynthetic intermediates by the products of single prn genes. Individual genes were expressed on plasmids in the host strain BL915ΔORF1–4, and biosynthetic intermediates were added to the culture medium as indicated. Culture extracts were separated by TLC on silica plates with toluene as the mobile phase. Metabolites were visualized with van Urk’s reagent. Arrows indicate the positions of APP (dark green), MDA (olive green), APRN (reddish brown), and PRN (purple).MDA accumulated in cultures of BL915ΔORF3, but APP, APRN, and PRN were not detected (Fig. (Fig.3).3). BL915ΔORF3 was able to produce PRN when supplied with APRN in the culture medium, but not when supplied with 7-CT or MDA (Table (Table2).2). Strain BL915ΔORF1–4 expressing prnC converted exogenously supplied MDA to APRN (Fig. (Fig.4).4). These data indicate that the prnC gene product catalyzes the chlorination of MDA to form APRN. Cell extracts of the P. fluorescens strain which overexpresses the prnC gene (but does not contain the other prn genes) can also catalyze the chlorination of MDA to form APRN (11).The prnC gene is homologous to the chl gene from Streptomyces aureofaciens, which encodes a chlorinating enzyme for tetracycline biosynthesis (3, 9). Like prnA, the prnC deduced amino acid sequence contains a consensus NAD binding region (9), and NADH is required for the chlorination of MDA (11). While both prnA and prnC encode halogenating enzymes, they show no homology to previously cloned haloperoxidases (9) or to each other. Furthermore, in contrast to haloperoxidases (16), the two NADH-dependent halogenating enzymes in the PRN biosynthesis pathway are substrate specific (i.e., the tryptophan halogenase does not catalyze the chlorination of MDA and vice versa) (11).APRN accumulated in cultures of BL915ΔORF4 (Fig. (Fig.3),3), and this mutant was not able to produce PRN when supplied with any of the known PRN biosynthetic intermediates. Strain BL915ΔORF1–4 expressing prnD converted exogenously supplied APRN to PRN (Fig. (Fig.4).4). These results indicate that the prnD gene product catalyzes the oxidation of the amino group of APRN to a nitro group forming PRN. In vitro experiments by Kirner and van Pée (15) had suggested that this reaction is catalyzed by a chloroperoxidase; however, gene disruption experiments demonstrated that chloroperoxidases are not involved in PRN biosynthesis in vivo (16). Instead, this oxidation is more likely to be catalyzed by a class IA oxygenase (20), as suggested by the homology of prnD with these enzymes (9).We have shown that each prn gene encodes a protein found in the wild-type BL915 strain and have demonstrated in vivo that these four gene products carry out four biochemical steps which convert l-tryptophan to PRN. None of the conversions were observed in strain BL915ΔORF1–4, from which the entire 5.8-kb prn gene region has been deleted (Fig. (Fig.4).4). The arrangement of the genes in the operon is identical to the sequence of reactions in the biosynthetic pathway proposed by van Pée et al. (23) (Fig. (Fig.11).Chang et al. (2) proposed an alternate biosynthetic scheme (Fig. (Fig.1B)1B) and reported the conversion of exogenously supplied APP to PRN in vivo. Similarly, Zhou et al. (25) reported the conversion of APP to APRN in a cell-free system. These workers concluded that APP is an intermediate in PRN biosynthesis and that ring rearrangement precedes chlorination (Fig. (Fig.1B).1B). In the present study, APP accumulated only in strains which overexpressed the prnB gene. Furthermore, APP was not detected in cultures of BL915ΔORF1, which contains functional prnBCD genes expressed from the native promoter, as would be expected if the ring rearrangement (catalyzed by the prnB gene product) occurs before the first chlorination step (catalyzed by the prnA gene product). Like Hamill et al. (8) and van Pée et al. (23), we demonstrated that exogenously supplied 7-CT is converted to PRN. These results, together with the finding that the gene product of prnA catalyzes the NADH-dependent chlorination of l-tryptophan to 7-CLT (11), support the biosynthetic pathway proposed by van Pée et al. (23) (Fig. (Fig.1A)1A) and suggest that APP is a side product or dead-end metabolite. Purification and kinetic characterization of the prnA and prnB gene products, including investigations of substrate specificity and regioselectivity, will further clarify the roles of 7-CLT and APP in the PRN biosynthetic pathway.If APP is indeed a dead-end metabolite, it would be advantageous to tightly regulate the amount of prnB gene product present in cells, thus minimizing the diversion of substrate into APP. The prnB gene begins with GTG (9), which is a two- to threefold-less-efficient initiation codon than ATG (18); however, the prnB open reading frame is apparently translationally coupled to the prnA open reading frame (9). Coupling increases translational efficiency and is thought to be a mechanism to ensure coordinate expression of the coupled genes (18). In PRN biosynthesis, translational coupling of prnA and prnB may be a mechanism to regulate the level of prnB gene product present in cells and minimize the diversion of tryptophan to APP. 相似文献
Bacterial strains and plasmids.
The bacterial strains and plasmids used in this study are described in Table Table1.1. Pseudomonas strains were cultured in Luria-Bertani medium at 28°C. Antibiotics, when used, were added at the following concentrations: tetracycline, 30 μg/ml; and kanamycin, 50 μg/ml. The expression vector pPEH14 consists of the Ptac promoter and rrnB ribosomal terminator from pKK223-3 (Pharmacia, Uppsala, Sweden) cloned into the BglII site of the broad-host-range plasmid pRK290 (4). Ptac is a strong constitutive promoter in Pseudomonas (unpublished data). The PRN biosynthetic genes are the coding regions described by Hammer et al. (9). Each coding region was cloned from the translation initiation codon to the stop codon by PCR with restriction sites added to the ends to facilitate cloning. For prnB, the native GTG initiation codon was changed to ATG. The clones were sequenced after PCR.TABLE 1
Bacterial strains and plasmids used in this study| P. fluorescens strain or plasmid | Characteristics | Source or reference |
|---|---|---|
| Strains | ||
| BL915 | Wild type | 10 |
| BL915ΔORF1 | Deletion in prnA of BL915, Prn−, Kmr | 9 |
| BL915ΔORF2 | Deletion in prnB of BL915, Prn−, Kmr | 9 |
| BL915ΔORF3 | Deletion in prnC of BL915, Prn−, Kmr | 9 |
| BL915ΔORF4 | Deletion in prnD of BL915, Prn−, Kmr | 9 |
| BL915ΔORF1–4 | Deletion in prnABCD of BL915, Prn−, Kmr | 9 |
| Plasmids | ||
| pPEH14(prnA) | pRK290 carrying Ptac functionally fused to the 1.6-kb prnA coding region | This study |
| pPEH14(prnB) | pRK290 carrying Ptac functionally fused to the 1.1-kb prnB coding region | This study |
| pPEH14(prnC) | pRK290 carrying Ptac functionally fused to the 1.7-kb prnC coding region | This study |
| pPEH14(prnD) | pRK290 carrying Ptac functionally fused to the 1.1-kb prnD coding region | This study |
Chemical standards.
7-Cl-d,l-tryptophan (7-CT) was synthesized as described by van Pée et al. (24). Monodechloroaminopyrrolnitrin (MDA) was extracted from cultures of P. aureofaciens and verified as described by van Pée et al. (23). Aminopyrrolnitrin (APRN) was prepared from PRN by reduction with sodium dithionite (22). PRN was synthesized according to the method of Gosteli (6).Western analysis.
To produce antigen, each prn gene was subcloned into a pET3 vector and transformed into E. coli BL21(De3) (Novagen, Inc., Madison, Wis.). Inclusion bodies were purified from induced cultures with protocols from Novagen. Inclusion body protein (100 μg) was run on a preparative Laemmli polyacrylamide electrophoresis gel, blotted to nitrocellulose filters, and stained with Ponceau S. The major band was excised, solubilized in dimethyl sulfoxide, and used by Duncroft, Inc. (Lovettsville, Va.), to immunize goats and produce antiserum against each PRN protein.Cultures of P. fluorescens BL915 were grown for 48 h in Luria-Bertani medium with the appropriate antibiotics. The cells were pelleted and resuspended in a small volume of Tris-EDTA. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western analysis were performed as described by Sambrook et al. (21). The primary antiserum (goat anti-PRN protein) was diluted 1/1,000, and the secondary antibody (rabbit anti-goat immunoglobulin G conjugated to peroxidase; Pierce, Rockford, Ill.) was diluted 1/3,000. Bands were visualized with an enhanced chemiluminescence kit (Amersham, Arlington Heights, Ill.). This Western analysis demonstrated that each antibody recognized a single protein band from wild-type BL915, and these bands were not present in BL915ΔORF1–4 (Fig. (Fig.2).2). The molecular weights of the recognized proteins were consistent with the sizes predicted from the gene sequences. Each prn gene was expressed on a plasmid in BL915ΔORF1–4. In each case, the protein product of the cloned gene reacted only with the expected antibody and was identical in size to the band detected by that antibody in wild-type BL915 (Fig. (Fig.2).2). Open in a separate windowFIG. 2Western blot analysis of the protein products of prn genes cloned from P. fluorescens BL915. Individual genes were expressed on plasmids in the host strain BL915ΔORF1–4. BL915 wild-type and BL915ΔORF1–4 controls are included on each blot. Blots A, B, C, and D were probed with antibodies raised against the products of prnA, prnB, prnC, and prnD, respectively. Arrows indicate the positions of the 60- and 42-kDa molecular mass markers.Intermediate analysis and feeding experiments.
To determine which biosynthetic intermediates were produced by the prn gene deletion mutants, 2-day-old cultures were extracted with an equal volume of ethyl acetate. The organic phase was dried under vacuum, and the residue was dissolved in a small volume of methanol. Thin-layer chromatography (TLC) was performed on silica-coated plates with toluene or hexane-ethyl acetate (2:1) as the mobile phase. PRN, APRN, MDA, and aminophenylpyrrole (APP) were visualized with van Urk’s reagent as described previously (22).To further clarify which biosynthetic step was blocked in each deletion mutant, intermediate feeding experiments were conducted. Cultures (10 ml) were incubated at 28°C for 48 h. Biosynthetic intermediates were dissolved in a small volume of methanol and added to 4 ml of culture at the following final concentrations: 7-CT, 2.5 μg/ml; MDA, 25 μg/ml; APRN, 12.5 μg/ml. The cultures were incubated for an additional 4 h at 28°C and then extracted with ethyl acetate and analyzed by TLC and liquid chromatography-mass spectrometry as described above.MDA, APRN, and PRN were not detected in cultures of BL915ΔORF1 (Fig. (Fig.3),3), indicating that this mutant is blocked at an early step in PRN biosynthesis. BL915ΔORF1 was able to produce PRN when 7-CT, MDA, or APRN was supplied exogenously (Table (Table2).2). When prnA was expressed in the absence of other prn genes (i.e., in BL915ΔORF1–4), 7-chloro-l-tryptophan (7-CLT) accumulated. The identity of 7-CLT was verified by comparison of results of high-performance liquid chromatography and mass spectra with chemically synthesized 7-CT. These results indicate that the prnA gene product catalyzes the chlorination of l-tryptophan. Open in a separate windowFIG. 3Accumulation of PRN biosynthetic intermediates in P. fluorescens BL915 and prn gene deletion mutants derived from it. Extracts from 2-day-old cultures were separated by TLC on silica plates with hexane-ethyl acetate (2:1 [vol/vol]) as the mobile phase. Metabolites were visualized with van Urk’s reagent. Arrows indicate the positions of MDA (olive green), APRN (reddish brown), and PRN (purple).TABLE 2
Production of PRN by deletion mutants when supplied with biosynthetic intermediates in the growth medium| Strain | Result with intermediate added to culturesa
| ||
|---|---|---|---|
| 7-CT | MDA | APRN | |
| BL915ΔORF1 | + | + | + |
| BL915ΔORF2 | − | + | + |
| BL915ΔORF3 | − | − | + |
| BL915ΔORF4 | − | − | − |
42.
Teresa Mozo Sabine Fischer Sebastian Meier-Ewert Hans Lehrach Thomas Altmann 《The Plant journal : for cell and molecular biology》1998,16(3):377-384
In order to generate a physical map of the Arabidopsis thaliana genome based on bacterial artificial chromosome clones (BACs), an iterative high throughput hybridisation strategy was applied and its efficiency was evaluated. Thus, probes generated from both ends of 500 BAC clones selected from the Arabidopsis –IGF–BAC library were hybridised to the entire library gridded on high density filters. The 1000 hybridisation reactions identified 4496 clones (41.8% of the complete library, or 50.3% if organellar, centromeric, and ribosomal DNA carrying clones are excluded) which were assembled into a minimum of 220 contigs. These results demonstrate the viability of the applied ‘double-end clone-limited/sampling without replacement’ hybridisation strategy for the generation of a high resolution physical map, and provide a highly useful resource for map-based gene cloning approaches and further genome analysis. 相似文献
43.
Friedrich Altmann 《Glycoconjugate journal》1998,15(1):79-82
N-glycan moiety of ascorbic acid oxidase from zucchini (Cucurbita pepo) has been described to be a core-pentasaccharide with a xylose [D'Andrea et al. (1988) Glycoconjugate J 5:151-7]. Ascorbic acid oxidase is sometimes used to characterize antibodies directed against carbohydrate determinants on plant glycoproteins. To prevent misinterpretations of immunological data, the structure of the N-glycan of ascorbic acid oxidase has been reinvestigated. The oligosaccharides were released by almond N-glycosidase and analysed as their pyridylamino derivatives by 2D-HPLC and exoglycosidase digestions. The main structure resembled the typical complex plant N-glycan consisting of a core-pentasaccharide decorated with xylose and 3-linked fucose. The other abundant species lacked the fucose residue. Small amounts of these glycans carried a GlcNAc residue on the 6-arm. Therefore, ascorbic acid oxidase will not only react with antibodies directed against the xylosylated region but also with those binding to N-glycans with 3-linked fucose. 相似文献
44.
The binding to concanavalin A (Con A) by pyridylaminated oligosaccharides derived from bromelain (Man alpha 1,6(Xyl beta 1, 2) Man beta 1, 4GlcNAc beta 1, 4(Fuc alpha 1, 3)GlcNAc), horseradish peroxidase (Man alpha 1,6(Man alpha 1, 3) (Xyl beta 1, 2)Man beta 1, 4GlcNAc beta 1,4(Fuc alpha 1, 3) GlcNAc), bee venom phospholipase A2 (Man alpha 1,6Man beta 1,4GlcNAc beta 1,4GlcNAc and Man alpha 1,6(Man alpha 1, 3)Man beta 1,4GlcNAc beta 1, 4 (Fuc alpha 1, 3)GlcNAc) and zucchini ascorbate oxidase (Man alpha 1,6(Man alpha 1, 3) (Xyl beta 1, 2)Man beta 1, 4 GlcNAc beta 1, 4GlcNAc) was compared to the binding by Man3GlcNAc2, Man5GlcNAc2 and the asialo-triantennary complex oligosaccharide from bovine fetuin. While the fetuin oligosaccharide did not bind, bromelain, zucchini, Man2GlcNAc2 and horseradish peroxidase were retarded (in that order). The alpha 1, 3-fucosylated phospholipase, Man3GlcNAc2 and Man5GlcNAc2 structures were eluted with 15 M alpha -methylmannoside. It is concluded that core alpha 1,3-fucosylation has little or no effect on ConA binding while xylosylation decreases affinity for ConA. In a parallel study comparing the endoglycosidase D (Endo D) sensitivities of Man3GlcNAc2, IgG-derived GlcNAc beta 1, 2Man alpha 1,6(GlcNAc beta 1,2Man alpha 1,3)Man beta 1,4GlcNAc beta 1,4(Fuc alpha 1,6)GlcNAc, the phospholipase Man alpha 1,6(Man alpha 1, 3)Man beta 1, 4GlcNAc beta 1,4(Fuc alpha 1,3)GlcNAc, and horseradish and zucchini pyridylaminated N-linked oligosaccharides, it was found that only the Man3GlcNAc2 structure was cleaved. The IgG structure was sensitive only when beta -hexosaminidase was also present. Thus, in contrast to core alpha 1,6-fucosylated structures, such as those present in mammals, the presence of core alpha 1,3-fucose, as found in structures from plants and insects, and/or beta 1,2-xylose, as found in plants, causes resistance to Endo D. 相似文献
45.
Andreas Roitinger Harald Leiter Erika Staudacher Friedrich Altmann 《Glycoconjugate journal》1998,15(1):89-91
Mammalian cells often contain an enzyme which transfers fucose onto the reducing terminal GlcNAc (GlcNAc-1) of N-glycans with an α1,6-linkage. In plants, on the other hand, the fucose is transferred to GlcNAc-1 with an α1,3-linkage. Insect cells can exhibit both enzymatic activities. Hitherto, the activity of these fucosyltransferases has been determined by the incorporation of radioactively labelled fucose into an acceptor glycopeptide. This assay, however, cannot discriminate these two activities. Here we report on the use of dansylated glycoasparagine for the specific determination of 1,3- and 1,6-fucosyltransferases. The two possible products and the substrate are separated on a reversed phase column and detected by fluorescence. 相似文献
46.
J?rg Hagmann Claude Becker Jonas Müller Oliver Stegle Rhonda C. Meyer George Wang Korbinian Schneeberger Joffrey Fitz Thomas Altmann Joy Bergelson Karsten Borgwardt Detlef Weigel 《PLoS genetics》2015,11(1)
There has been much excitement about the possibility that exposure to specific environments can induce an ecological memory in the form of whole-sale, genome-wide epigenetic changes that are maintained over many generations. In the model plant Arabidopsis thaliana, numerous heritable DNA methylation differences have been identified in greenhouse-grown isogenic lines, but it remains unknown how natural, highly variable environments affect the rate and spectrum of such changes. Here we present detailed methylome analyses in a geographically dispersed A. thaliana population that constitutes a collection of near-isogenic lines, diverged for at least a century from a common ancestor. Methylome variation largely reflected genetic distance, and was in many aspects similar to that of lines raised in uniform conditions. Thus, even when plants are grown in varying and diverse natural sites, genome-wide epigenetic variation accumulates mostly in a clock-like manner, and epigenetic divergence thus parallels the pattern of genome-wide DNA sequence divergence. 相似文献
47.
Rhonda Christiane Meyer Barbara Kusterer Jan Lisec Matthias Steinfath Martina Becher Hanno Scharr Albrecht E. Melchinger Joachim Selbig Ulrich Schurr Lothar Willmitzer Thomas Altmann 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,120(2):227-237
The main objective of this study was to identify genomic regions involved in biomass heterosis using QTL, generation means, and mode-of-inheritance classification analyses. In a modified North Carolina Design III we backcrossed 429 recombinant inbred line and 140 introgression line populations to the two parental accessions, C24 and Col-0, whose F 1 hybrid exhibited 44% heterosis for biomass. Mid-parent heterosis in the RILs ranged from ?31 to 99% for dry weight and from ?58 to 143% for leaf area. We detected ten genomic positions involved in biomass heterosis at an early developmental stage, individually explaining between 2.4 and 15.7% of the phenotypic variation. While overdominant gene action was prevalent in heterotic QTL, our results suggest that a combination of dominance, overdominance and epistasis is involved in biomass heterosis in this Arabidopsis cross. 相似文献
48.
Sandra Andorf Joachim Selbig Thomas Altmann Kathrin Poos Hanna Witucka-Wall Dirk Repsilber 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,120(2):249-259
Heterosis is a well-known phenomenon but the underlying molecular mechanisms are not yet established. To contribute to the
understanding of heterosis at the molecular level, we analyzed genome-wide gene expression profile data of Arabidopsis thaliana in a systems biological approach. We used partial correlations to estimate the global interaction structure of regulatory
networks. Our hypothesis states that heterosis comes with an increased number of partial correlations which we interpret as
increased numbers of regulatory interactions leading to enlarged adaptability of the hybrids. This hypothesis is true for
mid-parent heterosis for our dataset of gene expression in two homozygous parental lines and their reciprocal crosses. For
the case of best-parent heterosis just one hybrid is significant regarding our hypothesis based on a resampling analysis.
Summarizing, both metabolome and gene expression level of our illustrative dataset support our proposal of a systems biological
approach towards a molecular basis of heterosis. 相似文献
49.
Male mate-guarding episodes ('consortships'), are taxonomically widespread, yet costly to individual males. Consequently, males should bias consortships toward females with whom the probability of conception is high. We combined data on consortships with visual scoring of sexual swellings and assays of fecal estrogen concentrations (fE) in a wild population of baboons (Papio cynocephalus) to test the hypotheses that sexual swellings are reliable indicators of (1) within-cycle timing of ovulation, (2) differences in conception probability among females that differ in maturational stage, and (3) conceptive versus non-conceptive cycles of parous females. We also evaluated whether adult males might rely on swellings or other estrogen-dependent signals (e.g., fE) for mate-guarding decisions. We found that sexual swellings reflected conception probability within and among cycles. Adult males limited their consortships to the turgescent phase of cycles, and consorted more with adult females than with newly cycling adolescents. The highest ranking (alpha) males discriminated more than did males of other ranks; they (1) limited their consortships to the 5-day peri-ovulatory period, (2) consorted more with adult than with adolescent females, and (3) consorted more with adult females on conceptive cycles than on non-conceptive cycles, all to a greater extent than did males of other ranks. Male mate choice based on sexual swellings and other estrogenic cues of fertility may result in sexual selection on these female traits and enhance dominance-based reproductive skew in males. Alpha males are the least constrained in their mating behavior and can best take advantage of these cues to mate selectively. 相似文献
50.