Advances in linking wintering migrant birds to their breeding-ground origins using combined analyses of genetic and stable isotope markers

An enduring problem in avian ecology and conservation is linking breeding and wintering grounds of migratory species. As migratory species and populations vary in the degree to which individuals from distinct breeding locales mix on stop-over sites and wintering grounds, establishing migratory connectivity informs our understanding of population demography and species management. We present a new Bayesian approach for inferring breeding grounds of wintering birds of unknown origins in North America. We incorporate prior information from analysis of genetic markers into geographic origin assignment based upon stable-hydrogen isotope analysis of feathers (δ(2)H(f)), using the Loggerhead Shrike (Lanius ludovicianus). Likely geographic origins derived from analyses of DNA microsatellites were used as priors for Bayesian analyses in which birds were assigned to a breeding-ground origin using their δ(2)H(f) values. As with most applications of Bayesian methods, our approach greatly improved the results (i.e. decreased the size of the potential area of origin). Area of origin decreased by 3 to 5-fold on average, but ranged up to a 10-fold improvement. We recommend this approach in future studies of migratory connectivity and suggest that our methodology could be applied more broadly to the study of dispersal, sources of productivity of migratory populations, and a range of evolutionary phenomena.     

Who's My Daddy? Considerations for the influence of sexual selection on multiple paternity in elasmobranch mating systems

Polyandry resulting in multiply‐sired litters has been documented in the majority of elasmobranch species examined to date. Although commonly observed, reasons for this mating system remain relatively obscure, especially in batoids. The round stingray (Urobatis halleri) is an abundant, well‐studied elasmobranch distributed throughout the northeastern Pacific that we used to explore hypotheses regarding multiple paternity in elasmobranchs. Twenty mid‐ to late‐term pregnant females were sampled off the coast of southern California and their litters analyzed for the occurrence of multiple paternity using five nuclear microsatellite loci. In addition, embryo sizes and their position within the female reproductive system (i.e., right or left uterus) were recorded and used to make inferences for patterns of ovulation. Multiple paternity was observed in 90% of litters and male reproductive success within litters was relatively even among sires. High variability in testes mass was observed suggesting that sperm competition is high in this species, although male reproductive success per litter appeared to be relatively even. Using embryo size as a proxy for fertilization, females were found to exhibit a variety of ovulation patterns that could function to limit a male's access to eggs and possibly promote high rates of multiple paternity. Our study highlights that elasmobranch mating systems may be more varied and complex than presumed and further investigation is warranted.     

Rhythms of locomotion expressed by Limulus polyphemus, the American horseshoe crab: II. Relationship to circadian rhythms of visual sensitivity

In the laboratory, horseshoe crabs express a circadian rhythm of visual sensitivity as well as daily and circatidal rhythms of locomotion. The major goal of this investigation was to determine whether the circadian clock underlying changes in visual sensitivity also modulates locomotion. To address this question, we developed a method for simultaneously recording changes in visual sensitivity and locomotion. Although every animal (24) expressed consistent circadian rhythms of visual sensitivity, rhythms of locomotion were more variable: 44% expressed a tidal rhythm, 28% were most active at night, and the rest lacked statistically significant rhythms. When exposed to artificial tides, 8 of 16 animals expressed circatidal rhythms of locomotion that continued after tidal cycles were stopped. However, rhythms of visual sensitivity remained stable and showed no tendency to be influenced by the imposed tides or locomotor activity. These results indicate that horseshoe crabs possess at least two biological clocks: one circadian clock primarily used for modulating visual sensitivity, and one or more clocks that control patterns of locomotion. This arrangement allows horseshoe crabs to see quite well while mating during both daytime and nighttime high tides.     

Modulation of 5' splice site selection using tailed oligonucleotides carrying splicing signals

Background  

We previously described the use of tailed oligonucleotides as a means of reprogramming alternative pre-mRNA splicing in vitro and in vivo. The tailed oligonucleotides that were used interfere with splicing because they contain a portion complementary to sequences immediately upstream of the target 5' splice site combined with a non-hybridizing 5' tail carrying binding sites for the hnRNP A1/A2 proteins.     

Regulation of galectin-9 expression and release in Jurkat T cell line cells

Ecalectin/galectin-9 was recently described as a novel eosinophil chemoattractant highly expressed in immune tissues. We investigated the regulation of galectin-9 expression and release in Jurkat (a T cell line) cells. We demonstrated that medium and long-sized galectin-9 isoforms were constitutively expressed, and phorbol 12-myriastate 13-acetate (PMA) upregulated the level of galectin-9 mRNA in Jurkat cells. Western blotting and flow cytometry analyses revealed that PMA stimulation resulted in the upregulation of both intracellular and surface galectin-9 protein. The stimulated Jurkat cells simultaneously released evident eosinophil chemoattractant activity (ECA). Main ECA was adsorbed by both lactose and anti-galectin-9 antibody affinity column, suggesting that the ECA was ascribed to galectin-9. When Jurkat cells were stimulated with PMA in the presence of a BB94, a matrix metalloproteinase (MMP) inhibitor, but not tissue inhibitor of metalloproteinase-1 (TIMP-1), the release of galectin-9 was suppressed in a dose-dependent manner. We further found that calphostin c, a protein kinase c (PKC) inhibitor, weakly but significantly suppressed the release of galectin-9. The present data suggested that galectin-9 production in Jurkat cells is provoked by the stimulation with PMA and that some MMP and PKC is, at least, partly involved in the release of galectin-9 from Jurkat cells.     

Monitoring of native chemical ligation on solid substrate by surface plasmon resonance

During the last years native chemical ligation (NCL) gained in popularity as a method allowing the chemical synthesis of large peptides and entire proteins. NCL is particularly well-suited for chemoselective and nondenaturing attachment of biomolecules on solid substrates. In the present work, we show the feasibility of monitoring of peptide synthesis, NCL and its catalysis on silicon oxide modified gold surfaces by surface plasmon resonance (SPR). NCL of a model peptide-bradykinin thioester-was carried out and monitored with a custom-built SPR apparatus. Solid-phase produced bradykinin thioester was ligated to the surface in the presence of variable concentrations of 4-mercaptophenylacetic acid as transthioesterification catalyst. At catalyst concentration of 48 mM and above, the NCL reaction was maximal and identical to the reaction of the purified peptide-mercaptophenylacetic acid thioester. SPR curves indicate typical first-order kinetics with t(1/2) of 81 s for this aryl thioester, but of 104 min for the primary alkyl thioester.     

Effects of epidermal growth factor (EGF) on adult mouse small intestine in vivo and in organ culture

1. Exogenous administration of epidermal growth factor (EGF) has not modified the protein and DNA content, nor several brush border enzymes activities of duodenum, jejunum and ileum of intact and fasted adult mice. 2. Exogenous administration of EGF has not stimulated the DNA synthesis in the three regions of the small intestine of intact adult mice. 3. EGF has a stimulatory effect on DNA synthesis of fasted mice intestine 12 hr after injection. 4. In organ culture, EGF has not altered at any concentration (10, 50, 100, 200, 800 ng/ml), the same parameters in duodenal and jejunal explants taken from animals fasted 24 hr before being killed. 5. These last results suggest that the increase of DNA synthesis observed in vivo was not a direct effect of EGF administration. 6. Finally, the EGF content of serum af adult male mice was measured in fed and fasted mice and in the organ culture media.