Influence of the blood concentration of prolactin on the length of the sensitive period for establishing maternal behavior in sheep at parturition

The fading of postpartum maternal interest for the neonate (sensitive period) in ewes separated from their young at lambing is delayed when parturition is induced with 20 mg of estradiol benzoate (EB). An experiment was carried out to investigate the role of prolactin in this phenomenon. The sensitive period was studied in three groups of parturient ewes. In all groups lambs were removed at birth and reintroduced to their mothers 24 hr later. Maternal acceptance was tested at this time. In group 1 (dexamethasone D), ewes were induced to lamb with dexamethasone (15 mg im). In group 2 (EB), ewes were treated with 20 mg of estradiol benzoate (im). In group 3 (EB + CB 154) ewes received 20 mg of EB as in group 2 and 1 mg of CB 154 (sc) every 12 hr to prevent the enhanced secretion of prolactin which normally occurs after EB injection. The concentration of prolactin was highest in group 2 (EB), lowest in group 3 (EB + CB), and intermediate in group 1 (D) (p ? 0.001 between groups). By contrast, the proportion of ewes showing maternal behavior was similar in groups 2 and 3 ($\text{15}\text{23}$ and $\text{17}\text{22}$), both of which differed from group 1 ($\text{3}\text{22}\text{; p ? 0.005}$). It is concluded that the lengthening of the sensitive period for establishing maternal behavior in sheep following EB induced parturition is not related with high levels of prolactin in the peripheral circulation.     

Nitric oxide does not promote iron release from ferritin

It has been previously reported that iron release from ferritin could be promoted by nitric oxide (NO) generated from sodium nitroprusside. It was thus proposed that some of the toxic effects of NO could be related to its ability to increase intracellular free iron concentrations and generate an oxidative stress. On the contrary, the iron exchange experiments reported here show that NO from S-nitrosothiols is unable to promote iron release from ferritin. The discrepancy may be explained by the disregarded ability of ferrozine, the ferrous trap used in the previous report, to mobilize iron both from ferritin and from sodium nitroprusside spontaneously.     

Role of evolutionary and ecological factors in the reproductive success and the spatial genetic structure of the temperate gorgonian Paramuricea clavata

Dispersal and mating features strongly influence the evolutionary dynamics and the spatial genetic structure (SGS) of marine populations. For the first time in a marine invertebrate, we examined individual reproductive success, by conducting larval paternity assignments after a natural spawning event, combined with a small‐scale SGS analysis within a population of the gorgonian Paramuricea clavata. Thirty four percent of the larvae were sired by male colonies surrounding the brooding female colonies, revealing that the bulk of the mating was accomplished by males from outside the studied area. Male success increased with male height and decreased with increasing male to female distance. The parentage analyses, with a strong level of self‐recruitment (25%), unveiled the occurrence of a complex family structure at a small spatial scale, consistent with the limited larval dispersal of this species. However, no evidence of small scale SGS was revealed despite this family structure. Furthermore, temporal genetic structure was not observed, which appears to be related to the rather large effective population size. The low level of inbreeding found suggests a pattern of random mating in this species, which disagrees with expectations that limited larval dispersal should lead to biparental inbreeding. Surface brooding and investment in sexual reproduction in P. clavata contribute to multiple paternity (on average 6.4 fathers were assigned per brood), which enhance genetic diversity of the brood. Several factors may have contributed to the lack of biparental inbreeding in our study such as (i) the lack of sperm limitation at a small scale, (ii) multiple paternity, and (iii) the large effective population size. Thus, our results indicate that limited larval dispersal and complex family structure do not necessarily lead to biparental inbreeding and SGS. In the framework of conservation purposes, our results suggested that colony size, proximity among colonies and the population size should be taken into consideration for restoration projects.     

Dectin-1 Is Essential for Reverse Transcytosis of Glycosylated SIgA-Antigen Complexes by Intestinal M Cells

Intestinal microfold (M) cells possess a high transcytosis capacity and are able to transport a broad range of materials including particulate antigens, soluble macromolecules, and pathogens from the intestinal lumen to inductive sites of the mucosal immune system. M cells are also the primary pathway for delivery of secretory IgA (SIgA) to the gut-associated lymphoid tissue. However, although the consequences of SIgA uptake by M cells are now well known and described, the mechanisms whereby SIgA is selectively bound and taken up remain poorly understood. Here we first demonstrate that both the Cα1 region and glycosylation, more particularly sialic acid residues, are involved in M cell–mediated reverse transcytosis. Second, we found that SIgA is taken up by M cells via the Dectin-1 receptor, with the possible involvement of Siglec-5 acting as a co-receptor. Third, we establish that transcytosed SIgA is taken up by mucosal CX3CR1⁺ dendritic cells (DCs) via the DC-SIGN receptor. Fourth, we show that mucosal and systemic antibody responses against the HIV p24-SIgA complexes administered orally is strictly dependent on the expression of Dectin-1. Having deciphered the mechanisms leading to specific targeting of SIgA-based Ag complexes paves the way to the use of such a vehicle for mucosal vaccination against various infectious diseases.     

Two Intracellular Signaling Pathways for the Dopamine D3 Receptor: Opposite and Synergistic Interactions with Cyclic AMP

Abstract: As cerebral neurons express the dopamine D₁ receptor positively coupled with adenylyl cyclase, together with the D₃ receptor, we have investigated in a heterologous cell expression system the relationships of cyclic AMP with D₃ receptor signaling pathways. In NG108-15 cells transfected with the human D₃ receptor cDNA, dopamine, quinpirole, and other dopamine receptor agonists inhibited cyclic AMP accumulation induced by forskolin. Quinpirole also increased mitogenesis, assessed by measuring [³H]thymidine incorporation. This effect was blocked partially by genistein, a tyrosine kinase inhibitor. Forskolin enhanced by 50–75% the quinpirole-induced [³H]thymidine incorporation. This effect was maximal with 100 n M forskolin, occurred after 6–16 h, was reproduced by cyclic AMP-permeable analogues, and was blocked by a protein kinase A inhibitor. Forskolin increased D₃ receptor expression up to 135%, but only after 16 h and at concentrations of >1 µ M . Thus, in this cell line, the D₃ receptor uses two distinct signaling pathways: it efficiently inhibits adenylyl cyclase and induces mitogenesis, an effect possibly involving tyrosine phosphorylation. Activation of the cyclic AMP cascade potentiates the D₃ receptor-mediated mitogenic response, through phosphorylation by a cyclic AMP-dependent kinase of a yet unidentified component. Hence, transduction of the D₃ receptor can involve both opposite and synergistic interactions with cyclic AMP.     

Nonsense-mediated mRNA decay impacts MSI-driven carcinogenesis and anti-tumor immunity in colorectal cancers

Nonsense-mediated mRNA Decay (NMD) degrades mutant mRNAs containing premature termination codon (PTC-mRNAs). Here we evaluate the consequence of NMD activity in colorectal cancers (CRCs) showing microsatellite instability (MSI) whose progression is associated with the accumulation of PTC-mRNAs encoding immunogenic proteins due to frameshift mutations in coding repeat sequences. Inhibition of UPF1, one of the major NMD factors, was achieved by siRNA in the HCT116 MSI CRC cell line and the resulting changes in gene expression were studied using expression microarrays. The impact of NMD activity was also investigated in primary MSI CRCs by quantifying the expression of several mRNAs relative to their mutational status and to endogenous UPF1 and UPF2 expression. Host immunity developed against MSI cancer cells was appreciated by quantifying the number of CD3epsilon-positive tumor-infiltrating lymphocytes (TILs). UPF1 silencing led to the up-regulation of 1251 genes in HCT116, among which a proportion of them (i.e. 38%) significantly higher than expected by chance contained a coding microsatellite (P<2x10(-16)). In MSI primary CRCs, UPF1 was significantly over-expressed compared to normal adjacent mucosa (P<0.002). Our data provided evidence for differential decay of PTC-mRNAs compared to wild-type that was positively correlated to UPF1 endogenous expression level (P = 0.02). A negative effect of UPF1 and UPF2 expression on the host's anti-tumor response was observed (P<0.01). Overall, our results show that NMD deeply influences MSI-driven tumorigenesis at the molecular level and indicate a functional negative impact of this system on anti-tumor immunity whose intensity has been recurrently shown to be an independent factor of favorable outcome in CRCs.     

Biosynthesis of glycoconjugates in mitochondrial outer membranes

The results reported in this paper show two distinct ways for the incorporation ofN-acetylglucosamine into mitochondrial outer membranes. The first one is the glycosylation of dolichol acceptors, which is indicated by the inhibition of the synthesis of these products by the inhibitors of the dolichol intermediates (tunicamycin and GDP). The second one is the incorporation ofN-acetylglucosamine into protein acceptors directly from UDP-N-acetylglucosamine. This second way of glycosylation is only localized in mitochondria outer membranes.The existence of a direct route forN-glycoprotein biosynthesis has been based on the following evidence. First, the synthesis of theN-acetylglucosaminylated protein acceptors was not inhibited by tunicamycin or GDP. Second, the addition of exogenous dolichol-phosphate did not change the rate of biosynthesis of glycosylated protein material. Third, the sequential incorporation ofN-acetylglucosamine and mannose from their nucleotide derivatives in the presence of GDP and tunicamycin led to the synthesis of glycosylated protein material which entirely bound to Concanavalin A-Sepharose. The oligosaccharide moiety of the glycosylated protein material resulting from the direct transfer of sugars from their nucleotide derivatives to the protein acceptor is of theN-glycan type. On sodium dodecylsulphate polyacrylamide gel electrophoresis, this glycosylated material migrated as a marker protein with a molecular weight between 45 000 and 63 000. HPLC chromatofocusing analysis revealed that the fraction studied was anionic. The oligosaccharide moiety of the glycoprotein material can only be elongated by the incorporation ofN-acetylglucosamine and galactose from their nucleotide derivatives.     

Stage-specificity of spontaneous mutation at a tandem repeat DNA locus in the mouse germline

Mouse expanded simple tandem repeat (ESTR) loci are the most unstable loci in the mouse genome. Despite the fact that over the last decade these loci have been extensively used for studying germline mutation induction in mice, to date little is known about the mechanisms underlying spontaneous and induced ESTR mutation. Here we used flow cytometry and single-molecule PCR to compare the frequency of ESTR mutation in four flow-sorted fractions of the mouse male germ cells – spermatogonia, spermatocytes I, round and elongated spermatids. The frequency and the spectrum of ESTR mutation did not significantly differ between different stages of mouse spermatogenesis. Considering these data and the results of other publications, we propose that spontaneous ESTR mutation is mostly attributed to replication slippage in spermatogonia and these loci may be regarded as a class of expanded microsatellites.     

Influence of the margin vegetation on the conservation of aphid biological control in apple orchards

The influence of three margin strip treatments (wildflower strips, grass strips and spontaneous vegetation) adjacent to apple orchards on the biological control of Dysaphis plantaginea Passerini (Hemiptera: Aphididae) was compared during two consecutive years. The wildflower strips provided the highest amount of floral resources. Within the margin strips, hoverflies responded positively to higher resource provisioning whereas ladybird abundance did not differ between strip treatments. Within the orchards, the presence of parasitoids, hoverflies, and ladybirds in aphid colonies and the predation of sentinel aphids were not significantly affected by the adjacent strip treatments. The number of natural enemies observed in aphid colonies was mainly driven by aphid number. Aphid numbers were higher close to the margin strips suggesting that aphid colonization from orchard edges may counteract the positive effect of wildflower strips on natural enemy abundance and on a reduction of aphid infestation. The results confirm the positive influence of floral resource provisioning by wildflower strips on the conservation of aphid natural enemies, but also suggest that effects of wildflower strips on aphid regulation inside orchards are not very strong compared with spontaneous vegetation naturally occurring in the margins.     

The utility of wing morphometrics for assigning type specimens to cryptic bumblebee species

Since the beginning of taxonomy, species have been described based on morphology, but the advent of using semio-chemicals and genetics has led to the discovery of cryptic species (i.e. morphologically similar species). When a new cryptic species is described, earlier type specimens have to be re-evaluated, although this process can be challenging as only nondestructive methods ought to be used in order to preserve the integrity of the type specimens. Methods should allow comparison with recently collected specimens clustered based on chemical, ethological and/or genetic traits with old specimens (i.e. type specimens) where only morphological traits are available. Here we develop a method based on geometric morphometric analyses of wing shape for a taxonomically challenging group of bumblebees, the subgenus Alpinobombus Skorikov. We consider nine monophyletic taxa (including several cryptic species) to assess the accuracy of this method to discriminate the taxa based on their wing shape and then to attribute type specimens using a leave-one-out cross-validation procedure. We show that, for these bees, wing shape is taxon-specific, except for two sister taxa for which the species status is still debated. Moreover, for most of the taxa, type specimens were correctly attributed with high posterior probabilities of attribution, except for a few type specimens corresponding to the same two sister taxa where taxa delimitation based on wing shape was previously the subject of discussion. Our study highlights the potential of geometric morphometric analyses to help in the re-attribution of type specimens when the existence of cryptic species is revealed.