Demographic influences of translocated individuals on a resident population of house sparrows

Translocation of individuals from source populations to augment small populations facing risk of extinction is an important conservation tool. Here we examine sex‐specific differences between resident and translocated house sparrows Passer domesticus in reproductive success and survival, and the contribution of translocated individuals to the growth of a local population. We found evidence for assortative mating based on origin revealed by fewer parentages between translocated males and resident females than expected, and the total number of fledglings produced by such pairs was lower. The reproductive success of translocated males was positively related to the size of the throat badge (a sexual ornament), such that only translocated males with a large badge size were as successful as resident males. However, offspring with parents of different origin had higher survival than offspring with parents of the same origin, which suggests hybrid vigour. The contribution of resident and translocated individuals to the stochastic component of the long‐run growth rate of the population was similar; neither the mean individual contributions in fitness nor the demographic variance differed between the two groups. Thus, this experiment shows that translocated individuals may have a similar demographic influence on the growth of local populations as resident individuals. Still, the intermixing of translocated and resident individuals was low, and fitness differed according to origin in relation to individual differences in a sexually selected trait. In addition, hybrid vigour with respect to offspring recruitment seemed to partially decrease the negative fitness consequences of the assortative mating based on origin.     

Structural basis for the cooperation of Hsp70 and Hsp110 chaperones in protein folding

Protein folding by Hsp70 is tightly controlled by cochaperones, including J-domain proteins that trigger ATP hydrolysis and nucleotide exchange factors (NEFs) that remove ADP from Hsp70. Here we present the crystal structure of the yeast NEF Sse1p (Hsp110) in complex with the nucleotide-binding domain (NBD) of Hsp70. Hsp110 proteins are homologous to Hsp70s and consist of an NBD, a beta sandwich domain, and a three helix bundle domain (3HBD). In the complex, the NBD of Sse1p is ATP bound, and together with the 3HBD it embraces the NBD of Hsp70, inducing opening and the release of bound ADP from Hsp70. Mutations that abolish NEF activity are lethal, thus defining nucleotide exchange on Hsp70 as an essential function of Sse1p. Our data suggest that Sse1p does not employ the nucleotide-dependent allostery and peptide-binding mode of canonical Hsp70s, and that direct interactions of substrate with Sse1p may support Hsp70-assisted protein folding in a cooperative process.     

Endothelium-specific ablation of PDGFB leads to pericyte loss and glomerular, cardiac and placental abnormalities

Platelet-derived growth factor-B (PDGFB) is necessary for normal cardiovascular development, but the relative importance of different cellular sources of PDGFB has not been established. Using Cre-lox techniques, we show here that genetic ablation of Pdgfb in endothelial cells leads to impaired recruitment of pericytes to blood vessels. The endothelium-restricted Pdgfb knockout mutants also developed organ defects including cardiac, placental and renal abnormalities. These defects were similar to those observed in Pdgfb null mice. However, in marked contrast to the embryonic lethality of Pdgfb null mutants, the endothelium-specific mutants survived into adulthood with persistent pathological changes, including brain microhemorrhages, focal astrogliosis, and kidney glomerulus abnormalities. This spectrum of pathological changes is reminiscent of diabetic microangiopathy, suggesting that the endothelium-restricted Pdgfb knockouts may serve as models for some of the pathogenic events of vascular complications to diabetes.     

Isolation and characterization of complement component C3 from Atlantic cod (Gadus morhua L.) and Atlantic halibut (Hippoglossus hippoglossus L.)

Complement component C3 was isolated from the plasma of cod (Gadus morhua L.) and halibut (Hippoglossus hippoglossus L.). Fast protein liquid chromatography (FPLC) techniques, involving ion exchange and gel filtration columns, were used. The purified proteins were analysed by SDS-PAGE which showed a two-chain structure, alpha- and beta-chains, as seen in higher vertebrates. Both proteins had intra-chain thioesters located within their alpha-chains and N-terminal amino acid sequencing confirmed their identity with reference to known C3 amino acid sequences from other species. Specific antibodies were prepared against cod and halibut C3 and tested in Western blotting on sera and purified C3. The proteolytic fragmentation of C3 was tested with trypsin, pepsin, papain and the extracellular product (ECP) from the bacterium Aeromonas salmonicida ssp. achromogenes (Asa). Both trypsin and papain were successful in cleaving C3 whereas pepsin and ECP had no effect. Carbohydrate moieties were detected in the alpha- and beta-chains of cod and halibut C3 and N-linked oligosaccharides were removed from the C3 with PNGase treatment, revealing a difference in C3 glycosylation between the two species.     

The ontogeny of complement component C3 in Atlantic cod (Gadus morhua L.)--an immunohistochemical study

The complement system in fish is well developed and plays an important role in the immune response. Very little is known about the ontogeny of C3 in fish and no study has previously been done on the development of C3 in teleosts. In this study we have detected the presence of C3 in cod larvae from the age of 1 day post hatching (p.h.) till 57 days p.h., using immunohistochemistry. The specific primary antibodies used, were produced against the beta-chain of cod C3. Immunostaining on cod larvae sections revealed that C3 is detectable in the yolksac membrane from day 1 p.h., and in liver, brain, kidney and muscle from day 2 p.h. C3 was also detected in other organs such as eye, notochord, stomach, intestines, pancreas, heart and gills at different stages of cod larval development. These findings suggest that complement is not only important in immune defence against invading pathogens but may also play a role in the formation and generation of different organs.     

The ontogenic development of innate immune parameters of cod (Gadus morhua L.)

The aim of this study was to monitor the ontogenic development of innate immune parameters of cod (Gadus morhua L.) and to determine the presence of maternal IgM. The general protein composition and enzyme activity was also studied. At intervals, samples were collected of fertilized cod eggs and larvae from 3 days after fertilization until 57 days after hatching. Cell lysates were prepared and analysed by Western blotting using antibodies prepared against cod IgM, the complement component C3 and C-reactive protein (CRP) as well as against cod serum proteins and haemoglobin. Antibodies against salmon cathepsins and against several mammalian proteins of immunological significance were also used. Maternal IgM was not detected but C3 and the closely associated apolipoprotein A-I were present from the time of embryo organogenesis. C-reactive protein was not detected and none of the antibodies against mammalian immune parameters cross-reacted with the cod material. Protein and proteomic analysis showed that the major proteins of the egg samples were vitellogenin derived maternal proteins. Other non-vitellogenin maternal proteins, not yet identified, were also detected in the fertilized eggs. Cathepsin was present in all samples, but other enzyme activity was restricted to larval samples from 4 days after hatching when feeding had commenced. Haemoglobin was not detected until 10 days after hatching.     

A divergent Sm fold in EDC3 proteins mediates DCP1 binding and P-body targeting

Members of the (L)Sm (Sm and Sm-like) protein family are found across all kingdoms of life and play crucial roles in RNA metabolism. The P-body component EDC3 (enhancer of decapping 3) is a divergent member of this family that functions in mRNA decapping. EDC3 is composed of a N-terminal LSm domain, a central FDF domain, and a C-terminal YjeF-N domain. We show that this modular architecture enables EDC3 to interact with multiple components of the decapping machinery, including DCP1, DCP2, and Me31B. The LSm domain mediates DCP1 binding and P-body localization. We determined the three-dimensional structures of the LSm domains of Drosophila melanogaster and human EDC3 and show that the domain adopts a divergent Sm fold that lacks the characteristic N-terminal α-helix and has a disrupted β4-strand. This domain remains monomeric in solution and lacks several features that canonical (L)Sm domains require for binding RNA. The structures also revealed a conserved patch of surface residues that are required for the interaction with DCP1 but not for P-body localization. The conservation of surface and of critical structural residues indicates that LSm domains in EDC3 proteins adopt a similar fold that has separable novel functions that are absent in canonical (L)Sm proteins.     

The PEROXIN11 protein family controls peroxisome proliferation in Arabidopsis

PEROXIN11 (PEX11) is a peroxisomal membrane protein in fungi and mammals and was proposed to play a major role in peroxisome proliferation. To begin understanding how peroxisomes proliferate in plants and how changes in peroxisome abundance affect plant development, we characterized the extended Arabidopsis thaliana PEX11 protein family, consisting of the three phylogenetically distinct subfamilies PEX11a, PEX11b, and PEX11c to PEX11e. All five Arabidopsis PEX11 proteins target to peroxisomes, as demonstrated for endogenous and cyan fluorescent protein fusion proteins by fluorescence microscopy and immunobiochemical analysis using highly purified leaf peroxisomes. PEX11a and PEX11c to PEX11e behave as integral proteins of the peroxisome membrane. Overexpression of At PEX11 genes in Arabidopsis induced peroxisome proliferation, whereas reduction in gene expression decreased peroxisome abundance. PEX11c and PEX11e, but not PEX11a, PEX11b, and PEX11d, complemented to significant degrees the growth phenotype of the Saccharomyces cerevisiae pex11 null mutant on oleic acid. Heterologous expression of PEX11e in the yeast mutant increased the number and reduced the size of the peroxisomes. We conclude that all five Arabidopsis PEX11 proteins promote peroxisome proliferation and that individual family members play specific roles in distinct peroxisomal subtypes and environmental conditions and possibly in different steps of peroxisome proliferation.