Immune challenge mediates vocal communication in a passerine bird: an experiment

Secondary sexual characters may have evolved in part to signalresistance to parasites. Avian song has been hypothesized tobe involved in this process, but the role of parasites in modulatingacoustic communication systems in birds remains largely unknown,owing to lack of experiments. We studied the relationship betweenparasitism, testosterone, song performance, and mating successin male collared flycatchers (Ficedula albicollis) by experimentallychallenging their immune system with a novel antigen. We predictedthat a challenge of the immune system would reduce song performance,and that this reduction would be conditional on the size ofa visual sexual signal, the forehead patch that was previouslyfound to reflect resistance. An antagonistic linkage betweentestosterone and immune function would predict that a challengeof the immune system should suppress testosterone level. Animmunological treatment by sheep red blood cells (SRBCs) triggereda decrease in body mass, testosterone level, and song rate,but other song traits were not significantly affected by theantigen challenge. Initial testosterone level was associatedwith forehead patch size and all song traits except song rate.SRBC injection caused stronger reduction in song rate amongmales with smaller forehead patches, and the change in songrate was also predictable by song features such as strophe complexityand length. We show that song rate and other song characteristicsmay be important cues in male-male competition and female choice.These results suggest that parasite-mediated sexual selectionhas contributed in shaping a complex acoustic communicationsystem in the collared flycatcher, and that testosterone mayplay an important role in this process. Parasitism may drivea multiple signaling mechanism involving acoustic and visualtraits with different signal function.     

A comprehensive linkage map of the pig based on a wild pig - Large White intercross

A comprehensive linkage map, including 236 linked markers with a total sex-average map length of about 2300 cM, covering nearly all parts of the pig genome has been established. Linkage groups were assigned to all 18 autosomes, the X chromosome and the X/Y pseudoautosomal region. Several new gene assignments were made including the assignment of linkage group U1 (EAK-HPX) to chromosome 9. The linkage map includes 77 type I loci informative for comparative mapping and 72 in situ mapped markers physically anchoring the linkage groups on chromosomes. A highly significant heterogeneity in recombination rates between sexes was observed with a general tendency towards an excess of female recombination. The average ratio of female to male recombination was estimated at 1–4:1 but this parameter varied between chromosomes as well as between regions within chromosomes. An intriguing finding was that blood group loci were overrepresented at the distal ends of linkage groups.     

Ca2(+)-induced conformational changes and location of Ca2+ transport sites in sarcoplasmic reticulum Ca2(+)-ATPase as detected by the use of proteolytic enzyme (V8)

Treatment of Ca2(+)-ATPase from sarcoplasmic reticulum with V8 protease from Staphylococcus aureus produced appreciable amounts of a Ca2(+)-ATPase fragment (p85) in the presence of Ca2+ (E1 conformation of the enzyme), along with many other peptide fragments that were also formed in the presence of [ethylenebis(oxyethylenenitrilo)]tetraacetic acid (E2 conformation). p85 was formed as a carboxyl-terminal cleavage product of Ca2(+)-ATPase by a split of the peptide bond between Glu-231 and Ile-232. Other conformation-dependent V8 splits were localized to the "hinge" region, involved in ATP binding, between the middle and COOH-terminal one-third of the Ca2(+)-ATPase polypeptide chain. Representative split products in this region (p48,p31) were identified as NH2-terminal and COOH-terminal cleavage products of p85. In the membrane p85 probably remains associated with its complementary NH2-terminal fragment(s) and retains the capacity to bind Ca2+ as evidenced by resistance to V8 degradation in Ca2+ and ability to become phosphorylated by ATP. However, the hydrolysis rate of the phosphorylated enzyme is reduced, indicating that peptide cleavage at Glu-231 interferes with Ca2+ transport steps after phosphorylation. Binding of Ca2+ to V8 and tryptic fragments of Ca2(+)-ATPase was studied on the basis of Ca2(+)-induced changes in electrophoretic mobility and 45Ca2+ autoradiography after transfer of peptides to Immobilon membranes. These data indicate binding by the NH2-terminal 1-198 amino acid residues (corresponding to the tryptic A2 fragment) and the COOH-terminal 715-1001 amino acid residues (corresponding to p31). By contrast the central portion of Ca2(+)-ATPase, including the NH2-terminal portion of p85, is devoid of Ca2+ binding. These results question an earlier proposition that Ca2(+)-binding is located to the "stalk" region of Ca2(+)-ATPase (Brandl, C. J., Green, N. M., Korczak, B., and MacLennan, D. H.) (1986) Cell 44, 597-607) but are in agreement with recent data obtained by oligonucleotide-directed mutagenesis of Ca2(+)-ATPase (Clarke, D. M., Loo, T. W., Inesi, G., and MacLennan, D. H. (1989) Nature 339, 476-478). These different studies suggest that Ca2+ translocation sites may have an intramembranous location and are formed predominantly by the carboxyl-terminal part of the Ca2(+)-ATPase polypeptide chain.     

A large degree of functional diversity exists among helper T cells specific for the same antigenic site of influenza hemagglutinin.

The site-1 determinant of the hemagglutinin molecule of influenza virus (A/PR/8/34) is one of several immunodominant sites in the BALB/c Th cell response to Ha. A synthetic peptide comprising this T cell site (HA110-120), a panel of analogs containing single substitutions in this determinant, and homologs truncated at the amino- or carboxyl-terminal were used to examine the fine specificities of 15 T cells specific for site-1 in the context of I-Ed. The results indicate that every residue within the minimal determinant plays a role in the T cell recognition process, as single substitutions at any of these positions affected the ability of the peptide to stimulate at least some site 1-specific T cells. For the majority of the residues examined, substitutions had dissimilar effects on distinct T cells, indicating that the substituted residues were affecting recognition in a receptor-specific manner. Each of the 15 T cells examined had a distinct fine specificity pattern, suggesting that the BALB/c T cell repertoire for this site is likely to exceed 100 distinct clonotypes.     

Pituitary adenylate cyclase activating polypeptide is expressed in autonomic neurons

Pituitary adenylate cyclase activating polypeptide (PACAP) is a novel vasoactive intestinal peptide (VIP)-like peptide, which is present in neuronal elements of several peripheral organs, and thus a putative neurotransmitter/modulator. In the present study, the expression of PACAP in two parasympathetic ganglia (otic, sphenopalatine) and one mixed parasympathetic/sensory ganglion (jugular-nodose) in rat was characterized by use of in situ hybridization and immunocytochemistry and compared to that of VIP and calcitonin gene-related peptide (CGRP). PACAP and VIP were expressed in virtually all nerve cell bodies in the otic and sphenopalatine ganglia; PACAP and VIP were also expressed in subpopulations of nerve cell bodies in the jugular-nodose ganglion. CGRP was expressed in numerous nerve cell bodies in the jugular-nodose ganglion and in a few, scattered, nerve cell bodies in the sphenopalatine ganglion. In the otic and sphenopalatine ganglia, PACAP- and VIP-like immunoreactivities were frequently co-localized; in the jugular-nodose ganglion, PACAP-like immunoreactivity was frequently co-localized with CGRP-like immunoreactivity in presumably sensory neurons and to a lesser extent with VIP in parasympathetic neurons. Thus, PACAP is synthesized and stored in autonomic parasympathetic neurons as well as in vagal sensory neurons, which provides an anatomical basis for the diverse effects of PACAP previously described.     

Impact of Nutrient Composition on a Degradative Biofilm Community

A microbial community was cultivated in flow cells with 2,4,6-trichlorobenzoic acid (2,4,6-TCB) as sole carbon and energy source and was examined with scanning confocal laser microscopy and fluorescent molecular probes. The biofilm community which developed under these conditions exhibited a characteristic architecture, including a basal cell layer and conspicuous mounds of bacterial cells and polymer (approximately 20 to 30 (mu)m high and 25 to 40 (mu)m in diameter) occurring at 20- to 200-(mu)m intervals. When biofilms grown on 2,4,6-TCB were shifted to a labile, nonchlorinated carbon source (Trypticase soy broth), the biofilms underwent an architectural change which included the loss of mound structures and the formation of a more homogeneous biofilm. Neutrally charged fluorescent dextrans, which upon hydration become cationic, were observed to bind to mounds, as well as to the basal cell layer, in 14-day biofilms. In contrast, polyanionic dextrans bound only to the basal cell layer, indicating that this material incorporated sites with both positive and negative charge. The results from this study indicate that nutrient composition has a significant impact on both the architecture and the physicochemistry of degradative biofilm communities.     

A comparative analysis of the evolution of variation in appearance of eggs of European passerines in relation to brood parasitism

Host of brood parasites increase the ability of rejecting cuckooeggs by production of (1) a clutch with little variation amongeggs and (2) a clutch that differs the most from the modal phenotypeof the population. These hypotheses have been tested by Øienet at. (1995), although they did not control for common phylogeneticancestry. We analyze the evolution of egg color and markingpatterns in European passerines, which are potential hosts ofdie European cuckoo (Cuculus canorus), using Felsenstein's (1985)independent comparative method to control for the effect ofcommon phylogenetic descent We found a significant positiverelationship between interclutch variation in appearance ofhost eggs and parasitism rate, but this relationship disappearedwhen hole-nesting species were excluded from the analysis; andwe found a highly significant multiple regression between rejectionrate and intra- and interclutch variation in egg appearance,even when hole nesters were excluded from the analysis. Thepartial correlation coefficients were negative for intraclutchvariation and positive with interclutch variation in agreementwidi the hypotheses. Therefore, the use of the independent comparativemethod strengthens the hypothesis that the evolution of eggpatterns in hosts is associated with different stages of coevolutionwith the brood parasite.     

Key biocultural values to guide restoration action and planning in New Zealand

A pluralist and cross‐cultural approach that accommodates differing values while encouraging the collaboration and social cohesion necessary for the complex task of ecological restoration is needed. We used qualitative and quantitative analyses to investigate value assigned to biocultural restoration of coastal forests in northern New Zealand by 26 interviewees from three groups (environmental managers, Māori community members, and community project leaders). Māori community members primarily emphasized the importance of Cultural Stewardship and Use in the restoration process, while placing less emphasis on Ecological Integrity. Otherwise, all participants shared common trends, culminating in three interrelated value sets: (1) Personal Engagement, (2) Connection, and (3) the generation and transfer of Knowledge & Wisdom. These values demonstrate that restoration's benefits to people and community are as significant as its reparations of ecological components. Despite differences, all stakeholders were united in a broadly common goal to restore socio‐ecological systems. Their knowledge and shared passion for conservation signal enormous promise for accelerated and effective restoration of coastal forests, if it is conducted using a pluralistic approach. Because some values expressed were intangible and complex, with cross‐cultural dimensions, current valuation tools used by ecological economists to guide management investment fail to adequately account for, in particular, Māori values of ecological restoration.     

Functional properties of a naturally occurring Trp1200----Ser1200 mutation of the insulin receptor

Based on the sequence of cDNA encoding the intracellular domain of the insulin receptor beta-subunit, we recently defined a heterozygous point mutation causing a Ser for Trp substitution at position 1200 in the tyrosine kinase domain of a patient (BI-2) with the type A syndrome of insulin resistance. We have now sequenced the remainder of BI-2's insulin receptor cDNA-coding region and find no additional alterations in the encoded proreceptor protein. The nucleotide sequence of cDNA encoding the portion of the beta-subunit which includes Trp1200 was normal in BI-2's unaffected mother. Hybridization of a mutant allele-specific oligonucleotide to polymerase chain reaction-amplified cDNA confirmed the presence of the mutant allele in the proband and excluded it in her unaffected sister and mother, 18 normal control subjects, and six other subjects with insulin resistance. To determine whether this mutation had functional consequences for receptor signalling, we reconstructed it into a full-length insulin receptor cDNA expression vector. Chinese hamster ovary cells were transfected with mutant cDNA, and the expressed insulin receptors were compared to receptors expressed by cells transfected with wild-type receptor cDNA. Both mutant and wild-type receptors were properly processed into receptor alpha- and beta-subunits, were expressed on the cell surface, and displayed similar insulin-binding affinity. In contrast, insulin-stimulated autophosphorylation of the mutant receptors was severely impaired, whether assessed in intact cells or with a partially purified receptor preparation.(ABSTRACT TRUNCATED AT 250 WORDS)     

An in vitro system for the study of tracheal epithelial cells

Enzymatically dissociated hamster tracheal epithelial (HTE) cells were cultured on collagen coated Millicell filters. Within 3-5 days after being placed in culture large numbers of ciliated and mucus cells began to appear. By 1 week the HTE cells closely resembled those seen in vivo, i.e. columnar morphology and organelle polarity. After 4 weeks in vitro the HTE cultures were still able to maintain the polarity and overall columnar morphology found in in vivo tissue. There was, in addition, no apparent degradation of the collagen substrate. Auto-radiographic data indicated that there was an initial period of high DNA synthesis during the first 3 days in vitro. This was followed by a second phase in which, by day 6, the amount of DNA synthesis was greatly reduced. Analysis of the numbers of ciliated cells relative to non-ciliated cells demonstrated that between days 5 and 8 there was an increase in the percentage of ciliated cells, suggesting that cellular differentiation (i.e. ciliogenesis) follows cellular proliferation. The results of this study show that when HTE cells are grown on collagen-coated Millicell filters there is a significant improvement in cell growth and morphology yielding cells that are very similar to those present under in vivo conditions. Moreover, since there is no degradation of the collagen substrate, HTE cultures may be suitable for long-term studies of respiratory tract epithelia.