Effect of conspecific alarm calls in the parental behaviour of nesting southern house wrens

Alarm calls are usually used to signal the presence of a threat to members of the same species and have been studied broadly in social foraging species. We analysed the effects of conspecific alarm calls on the parental behaviour of a territorial species, the southern house wrens (Troglodytes aedon musculus), during nestling stage. We compared the parental response of adults feeding 9–11-day-old nestlings when faced with conspecific alarm calls and with a control non-sympatric species’ song broadcast from a neighbouring territory. We measured the time required by parents to return to the nest (latency) when exposed to the stimuli and estimated parent’s nest visitation rate and mean visit duration. Parents took longer to resume parental activities when we broadcast a conspecific alarm call, but they did not modify their nest visitation rate or the mean visit duration. Heterospecific songs did not seem to affect parental behaviour. Our results suggest that nesting southern house wrens can use alarm calls uttered from neighbouring territories to assess the presence of a threat and adjust their parental behaviour accordingly.     

Facultative dispersal by juvenile males in the cooperative stripe-backed wren

We present genetic and demographic data documenting juveniledispersal in the cooperatively breeding stripe-backed wren (Campylorhynchusnuchalis) of Venezuela. Parentage and DNA fragment-sharing analysesrevealed 12 cases in which juveniles were unrelated to othergroup members. Of these 12 foreign juveniles, (1) all were males,(2) eight of 12 had been found with breeding pairs lacking helpersrather than with groups containing helpers, and (3) four outof seven of those observed as adults courted or sired offspringwith the dominant females in their new groups despite the strongincest avoidance of this species. Furthermore, juvenile maleshad a significant tendency to disappear from natal groups intheir first year, and singleton juveniles observed with pairsafter the breeding season were mostly males. These data supportthe hypothesis that foreign juveniles were dispersers from intactgroups and not products of conspecific brood parasitism or adoptionfollowing group dissolution. We suggest that unassisted pairsmight accept juvenile males into their groups as helpers toincrease their future reproductive success and that dispersersthemselves might leave large natal groups in which their helpingis superfluous to join small groups of nonrelatives in whichthey might soon reproduce.     

Structure-based function inference using protein family-specific fingerprints

We describe a method to assign a protein structure to a functional family using family-specific fingerprints. Fingerprints represent amino acid packing patterns that occur in most members of a family but are rare in the background, a nonredundant subset of PDB; their information is additional to sequence alignments, sequence patterns, structural superposition, and active-site templates. Fingerprints were derived for 120 families in SCOP using Frequent Subgraph Mining. For a new structure, all occurrences of these family-specific fingerprints may be found by a fast algorithm for subgraph isomorphism; the structure can then be assigned to a family with a confidence value derived from the number of fingerprints found and their distribution in background proteins. In validation experiments, we infer the function of new members added to SCOP families and we discriminate between structurally similar, but functionally divergent TIM barrel families. We then apply our method to predict function for several structural genomics proteins, including orphan structures. Some predictions have been corroborated by other computational methods and some validated by subsequent functional characterization.     

Detection of Chlamydiaceae DNA in veterinary specimens using a family-specific PCR

AIMS: The aim of this work was to develop a rapid molecular test for the detection of the Chlamydiaceae family, irrespective of the species or animal host. METHODS AND RESULTS: The method described herein is a polymerase chain reaction targeting the 16S rRNA gene of the Chlamydiaceae family, and the results demonstrate that the test reacts with five reference Chlamydiaceae but none of the 19 other bacterial species or five uninfected animal tissues tested. The results also indicate the enhanced sensitivity of this test when compared with conventional culture or serology techniques. This is demonstrated through parallel testing of six real clinical veterinary cases and confirmatory DNA sequence analysis. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: This test can be used by veterinary diagnostic laboratories for rapid detection of Chlamydiaceae in veterinary specimens, with no restriction of chlamydial species or animal host. The test does not differentiate chlamydial species, and if required, speciation must be carried out retrospectively using alternate methods. However, for the purpose of prescribing therapy for chlamydiosis, this test would be an invaluable laboratory tool.     

Intrafamilial transmission and family-specific spectra of cutaneous betapapillomaviruses

Cutaneous human betapapillomaviruses (beta-HPVs) are widespread in the general population and have been associated with skin cancer. To evaluate the impact of continuous person-to-person contact within families on an individual's beta-HPV type spectrum, we collected serial skin swab samples from parents and children from 10 families. All participants were found to be beta-HPV DNA positive, with 1 to 13 types at study entry (median, 4.0 types). Initial and cumulative (2 to 16 types) HPV type multiplicities varied widely between different families but only a little between family members. The high intrafamilial correlation of HPV multiplicity is already obvious for babies aged 10 days to 10 months. Family members typically displayed similar spectra of HPV types. More than 75% of the HPV types in babies were also detected in their parents. This indicates that HPV transmission mainly results from close contact between family members. Type-specific persistence for at least 9 months was more prevalent in parents (92%) than in children (66%). Of the types detected throughout the study, 24% turned out to persist in the parents and only 11% in the children. Interestingly, about one-half of the HPV types found to persist in one of the parents occurred less frequently or even only sporadically in the spouse. Similarly, only one-third of the persisting parental types also persisted in their children. This indicates that even regular exposure to cutaneous HPV does not necessarily lead to the establishment of a persistent infection, which may point to type-specific susceptibilities of different individuals.     

Distribution of family-specific sequence homologies in six families of isoaccepting tRNAs

The nucleotide occupancy of 288 sequences of tRNA has been analyzed for every position on the standard tRnA sequence, except for the anticodon and the variable regions of the D and V loops. Modified nucleotides were assimilated to the canonical nucleotide from which they derive. A X2 test applied at the P = 0.01 level of significance showed family-specific patterns in each of the 6 isoacceptor families (tRNAMet, tRNAPhe, tRNALeu, tRNASer, tRNAVal and tRNAGly) where enough sequences are known to apply the test. The number of positions showing such a pattern ranged from 6 in the tRNASer and tRNAVal families to 15 in the tRNAMet, which is mostly formed of initiator tRNAs. Seven positions (12, 22, 31, 39, 44, 59 and 73) showed homologies in at least four families. The localization of most homologous nucleotides on the tRNA molecule makes it plausible that they interact with the recognition of the aminoacyl tRNA synthetase or, in a few cases, with the anticodon-codon recognition. A few positions (44, 59, 63) show homologies which are difficult to explain by a common functional constraint according to current ideas on the structure and function of tRNAs.     

Fitness-related consequences of egg mass in nestling house wrens

The fitness-related consequences of egg mass, independent of confounding influences associated with parental quality, remain poorly understood for wild birds in general and for passerines in particular. We performed cross-fostering experiments to test the hypothesis that egg mass, independent of parental quality, is the primary determinant of fitness-related traits in nestling house wrens (Troglodytes aedon), an insectivorous passerine. Nestling mass was significantly correlated with the mass of the eggs from which nestlings hatched early but not late in the nestling period in early-season broods. In contrast, in late-season broods, nestling mass was correlated with egg mass until nestlings achieved asymptotic mass. Neither nestling growth nor survival to nest leaving was related to egg mass in either early- or late-season broods; however, nestlings in late-season broods grew more slowly than did nestlings in early-season broods. We propose that nestling mass and egg mass remained correlated throughout the nestling period in late-season broods because decreased arthropod food resources late in the breeding season constrain parents'' ability to provision nestlings. We conclude that female house wrens in this population trade-off clutch size for greater egg mass to maximise reproductive success in late-season broods.     

Behavioral mechanisms preventing filial ovicide in house wrens

Because unmated house wrens (Troglodytes aedon) regularly destroyclutches of conspecifics, we examined mechanisms that preventbreeding individuals from destroying eggs in their own nests.Results of our experimental field study indicate that the egg-destroyingbehavior of males is partially suppressed after mating and thatthe suppression may prevent filial ovicide in some individuals.At least 35% of males continue to destroy conspecific eggs duringthe incubation period of their mates. Because filial ovicideby males is prevented independently of female presence at thenest, we conclude, after eliminating alternative hypotheses,that filial ovicide by males is prevented through their recognitionof nest locations. Egg-destroying behavior of females is alsosuppressed during the incubation. The suppression is strongerthan in males because fewer females than males destroy foreigneggs over a comparable time period. Females respond to experimentallychanged nest location and nest structure, but not egg coloration.We conclude that filial ovicide by females is prevented throughthe suppression of their eggdestroying behavior and throughtheir recognition of nest location and structure.     

Social mating system and reproductive success in house wrens

Current models explaining the establishment and maintenanceof social monogamy and polygyny within avian populations typicallyassume that the reproductive success of polygynous males exceedsthat of monogamous males. This assumption is almost always supportedwhen the number of fledglings or recruits to future breedingpopulations is used to measure adult reproductive success. However,recent studies using DNA markers indicate that simple countsof fledglings or recruits may be a poor estimator of the numberof nestlings sired by the social father. In this paper, we comparethe number of genetic offspring produced by socially monogamousand polygynous house wren (TrogiodyUs atdon) males in nestsat which they were the social father. Polygynous males did,in fact, sire more nestlings in their own nests than did monogamousmales. Moreover, although we have not identified the sires ofextrapair nestlings, we document that even when all extrapairnestlings in this population are hypotheticaOy assigned to monogamousmales, die total reproductive success of polygynous males exceedsthat of monogamous males. These results and those of severalother recent studies are consistent with the assumption thatpolygynous males produce more offspring than monogamous males.     

Male wrens with large testes breed early

To display to females, male wrens, Troglodytes troglodytes, use cock nests built on their territories. Nest building starts about a month before the first females begin egg laying. The timing of nest building is highly variable between males with up to 8 weeks separating the earliest from the latest males to initiate this display activity. Males that weigh more before the breeding season initiate nest building earlier than lighter males. We measured testis size in male wrens in the prebreeding period during which seasonal testicular recrudescence is occurring. The initiation of nest building was predicted by male age and by testis size. This suggests that variation in the start of courtship activity may reflect variation between males in the rate of testicular recrudescence. Variation in male prebreeding body mass was influenced by variation in testis size, which suggests that the relation reported earlier between body mass and timing of nest construction could be explained, in part, by variation in testis size. Alternatively, if body mass reflects body condition then both the extent of testes recrudescence and the timing of courtship activity could be condition-dependent traits. Copyright 2000 The Association for the Study of Animal Behaviour.     

Applicability of multigene family-specific antibodies toward studies of the subtilases in Arabidopsis thaliana

Polyclonal antibodies were made to two synthetic peptides with sequences patterned after conserved regions in a multigene family of 56 subtilisin-related proteolytic enzymes in Arabidopsis thaliana. GST-fusion proteins encompassing full-length or partial cDNAs bearing putative epitope regions were cloned and expressed in Escherichia coli. Immunoblots showed that the antibodies bound 12 of 13 fusion proteins tested. About 27 more subtilase genes code for regions with sequences very similar to the epitope regions of the subtilases that were visualized on the immunoblots. Subtilases in rosette and cauline leaves, stems, flowers, and siliques could be distinguished by the antibodies; some binding the two antibodies to similar extents, while others bind preferentially or almost exclusively to one or the other antibody. When antibodies were used to monitor ion-exchange fractionation of seedling extracts, one specific subtilase was identified by LC-MS-MS. The specificity of the antibodies extended to subtilases in soybean. These studies show that multigene family-specific antibodies can be applied to the study of gene families, where sequence similarities make it difficult to produce antibodies specific for each individual protein in the group.     

DbW: automatic update of a functional family-specific multiple alignment

MOTIVATION: Recent advances in gene sequencing have provided complete sequence information for a number of genomes and as a result the amount of data in the sequence databases is growing at an exponential rate. We introduce here a new program, DbW, to automate the update of a functional family-specific multiple alignment that tries to include relevant sequences. The program is based on the use of different sources of information: sequences and annotations in databases. RESULTS: The advantages of DbW are demonstrated using the 20 families of aminoacyl-tRNA synthetases, where DbW detects a maximum of homologous sequences in the Swiss-Prot and SPTREMBL databases. The global specificity of DbW in this test is 98.4% (1.6% of the sequences included in the alignment did not belong to the family according to their function), and the global sensitivity of DbW is estimated to be 95.2%. Thus, DbW provides a reliable basis for the many applications that rely on accurate multiple alignments, e.g. functional residue identification, 2D/3D structure prediction or homology modeling. AVAILABILITY: The DbW software is available for download at ftp://ftp-igbmc.u-strasbg.fr/pub/DbW/DbW.tar and online at http://titus.u-strasbg.fr/DbW CONTACT: prigent@igbmc.u-strasbg.fr.     

Evidence for heterozygote instability in microsatellite loci in house wrens

Microsatellite loci have high mutation rates and high levels of allelic variation, but the factors influencing their mutation rate are not well understood. The proposal that heterozygosity may increase mutation rates has profound implications for understanding the evolution of microsatellite loci, but currently has limited empirical support. We examined 20 microsatellite mutations identified in an analysis of 12 260 meiotic events across three loci in two populations of a songbird, the house wren (Troglodytes aedon). We found that for an allele of a given length, mutation was significantly more likely when there was a relatively large difference in size between the allele and its homologue (i.e. a large ‘allele span’). Our results support the proposal of heterozygote instability at microsatellite loci.     

Trill consistency is an age-related assessment signal in banded wrens

Older males tend to have a competitive advantage over younger males in sexual selection. Therefore, it is expected that signals used in sexual selection change with age. Although song repertoire size in songbirds is often mentioned as an age-related trait, many species, including the banded wren (Thryothorus pleurostictus), do not increase their repertoires after the first year. Here, we show that banded wrens reproduce the trill notes in their songs with less variability between them (i.e. more consistently) when they grow older. In a playback experiment, we also show that banded wrens discriminate between younger and older birds based on structural aspects of their song. In a second experiment, banded wrens also respond differentially to natural songs versus songs with artificially enhanced consistency. We argue that consistency in trill note reproduction may be achieved through practice. Sexual selection in the form of male–male competition may therefore operate on a phenotypic trait, the expression of which is enhanced by practice.