Increasing land-use intensity decreases floral colour diversity of plant communities in temperate grasslands

To preserve biodiversity and ecosystem functions in a globally changing world it is crucial to understand the effect of land use on ecosystem processes such as pollination. Floral colouration is known to be central in plant-pollinator interactions. To date, it is still unknown whether land use affects the colouration of flowering plant communities. To assess the effect of land use on the diversity and composition of flower colours in temperate grasslands, we collected data on the number of flowering plant species, blossom cover and flower reflectance spectra from 69 plant communities in two German regions, Schwäbische Alb (SA) and Hainich-Dün (HD). We analysed reflectance data of flower colours as they are perceived by honeybees and studied floral colour diversity based upon spectral loci of each flowering plant species in the Maxwell triangle. Before the first mowing, flower colour diversity decreased with increasing land-use intensity in SA, accompanied by a shift of mean flower colours of communities towards an increasing proportion of white blossom cover in both regions. By changing colour characteristics of grasslands, we suggest that increasing land-use intensity can affect the flower visitor fauna in terms of visitor behaviour and diversity. These changes may in turn influence plant reproduction in grassland plant communities. Our results indicate that land use is likely to affect communication processes between plants and flower visitors by altering flower colour traits.     

Middle Pleistocene ecology and Neanderthal subsistence: Insights from stable isotope analyses in Payre (Ardèche,southeastern France)

The Middle Palaeolithic site of Payre in southeastern France yields abundant archaeological material associated with fossil hominid remains. With its long sequence of Middle Pleistocene deposits, Payre is a key site to study the Middle Palaeolithic chronology of this region. This study is the first to investigate carbon and oxygen isotope contents of Neanderthal tooth enamel bioapatite, together with a wide range of herbivorous and carnivorous species. The aim is to contribute to the understanding of hunting behaviour, resource partitioning, diet and habitat use of animals and Neanderthals through a palaeoecological reconstruction.     

Multi-environment analysis and improved mapping of a yield-related QTL on chromosome 3B of wheat

Improved mapping, multi-environment quantitative trait loci (QTL) analysis and dissection of allelic effects were used to define a QTL associated with grain yield, thousand grain weight and early vigour on chromosome 3BL of bread wheat (Triticum aestivum L.) under abiotic stresses. The QTL had pleiotropic effects and showed QTL x environment interactions across 21 diverse environments in Australia and Mexico. The occurrence and the severity of water deficit combined with high temperatures during the growing season affected the responsiveness of this QTL, resulting in a reversal in the direction of allelic effects. The influence of this QTL can be substantial, with the allele from one parent (RAC875) increasing grain yield by up to 12.5 % (particularly in environments where both heat and drought stress occurred) and the allele from the other parent (Kukri) increasing grain yield by up to 9 % in favourable environments. With the application of additional markers and the genotyping of additional recombinant inbred lines, the genetic map in the QTL region was refined to provide a basis for future positional cloning.     

Silent,generic and plant kairomone sensitive odorant receptors from the Southern house mosquito

The Southern house mosquito Culex quinquefasciatus has the largest repertoire of odorant receptors (ORs) of all mosquitoes and dipteran species whose genomes have been sequenced to date. Previously, we have identified and de-orphanized two ORs expressed in female antennae, CquiOR2 and CquiOR10, which are sensitive to oviposition attractants. In view of a new nomenclature for the Culex genome (VectorBase) we renamed these ORs as CquiOR21 (formerly CquiOR10) and CquiOR121 (CquiOR2). In addition, we selected ORs from six different phylogenetic groups for deorphanization. We cloned four of them by using cDNA from female antennae as a template. Attempts to clone CquiOR87 and CquiOR110 were unsuccessful either because they are pseudogenes or are not expressed in adult female antennae, the main olfactory tissue. By contrast, CquiOR1, CquiOR44, CquiOR73, and CquiOR161 were highly expressed in female antennae. To de-orphanize these ORs, we employed the Xenopus oocyte recording system. CquiORx–CquiOrco-expressed oocytes were challenged with a panel of 90 compounds, including known oviposition attractants, human and vertebrate host odorants, plant kairomones, and naturally occurring repellents. While CquiOR161 did not respond to any test compound in two different laboratories, CquiOR1 showed the features of a generic OR, with strong responses to 1-octen-3-ol and other ligands. CquiOR44 and CquiOR73 showed preference to plant-derived terpenoids and phenolic compounds, respectively. While fenchone was the best ligand for the former, 3,5-dimethylphenol elicited the strongest responses in the latter. The newly de-orphanized ORs may be involved in reception of plant kairomones and/or natural repellents.     

Presenilin-1/γ-Secretase Controls Glutamate Release,Tyrosine Phosphorylation,and Surface Expression of N-Methyl-d-aspartate Receptor (NMDAR) Subunit GluN2B

Abnormally high concentrations of extracellular glutamate in the brain may cause neuronal damage via excitotoxicity. Thus, tight regulation of glutamate release is critical to neuronal function and survival. Excitotoxicity is caused mainly by overactivation of the extrasynaptic NMDA receptor (NMDAR) and results in specific cellular changes, including calcium-induced activation of calpain proteases. Here, we report that presenilin-1 (PS1) null mouse cortical neuronal cultures have increased amounts of calpain-dependent spectrin breakdown products (SBDPs) compared with WT cultures. NMDAR antagonists blocked accumulation of SBDPs, suggesting abnormal activation of this receptor in PS1 null cultures. Importantly, an increase in SBDPs was detected in cultures of at least 7 days in vitro but not in younger cultures. Conditioned medium from PS1 null neuronal cultures at 8 days in vitro contained higher levels of glutamate than medium from WT cultures and stimulated production of SBDPs when added to WT cultures. Use of glutamate reuptake inhibitors indicated that accumulation of this neurotransmitter in the media of PS1 null cultures was due to increased rates of release. PS1 null neurons showed decreased cell surface expression and phosphorylation of the GluN2B subunit of NMDAR, indicating decreased amounts of extrasynaptic NMDAR in the absence of PS1. Inhibition of γ-secretase activity in WT neurons caused changes similar to those observed in PS1 null neurons. Together, these data indicate that the PS1/γ-secretase system regulates release of glutamate, tyrosine phosphorylation, and surface expression of GluN2B-containing NMDARs.     

Darker female pigeons transmit more specific antibodies to their eggs than do paler ones

Melanin‐based coloration is widespread among vertebrates, yet the adaptive significance of such pigments remains elusive, particularly with regard to the link between melanin and immune‐mediated maternal effects. The aim of this study was to investigate whether melanin‐based coloration could signal the ability of mothers to mount a humoral response and to transfer maternal antibodies (Ab) to their young. We injected differently coloured (pale and dark) female feral pigeons (Columba livia) with Chlamydiae (a natural antigen) and Keyhole Limpet Haemocyanin (KLH, an artificial antigen), and found no significant difference in humoral response between differently coloured females. However, darker females transferred more Ab against Chlamydiae into their eggs than paler ones, despite similar circulating levels of Ab. In addition to this, melanin‐based coloration showed a high heritability value. This suggests that a genetically based coloured trait might be linked to the ability of females to transfer specific Ab against Chlamydiae (but not against KLH) to their offspring, independent of their ability to produce Ab. This suggests that transmission of maternal Ab is antigen dependent, and that melanin‐based coloration might signal female ability to transmit specific Ab against natural pathogens. © 2013 The Linnean Society of London     

New insights into the ear region anatomy and cranial blood supply of advanced stem Strepsirhini: Evidence from three primate petrosals from the Eocene of Chambi,Tunisia

We report the discovery of three isolated primate petrosal fragments from the fossiliferous locality of Chambi (Tunisia), a primate-bearing locality dating from the late early to the early middle Eocene. These fossils display a suite of anatomical characteristics otherwise found only in strepsirhines, and as such might be attributed either to Djebelemur or/and cf. Algeripithecus, the two diminutive stem strepsirhine primates recorded from this locality. Although damaged, the petrosals provide substantial information regarding the ear anatomy of these advanced stem strepsirhines (or pre-tooth-combed primates), notably the patterns of the pathway of the arterial blood supply. Using μCT-scanning techniques and digital segmentation of the structures, we show that the transpromontorial and stapedial branches of the internal carotid artery (ICA) were present (presence of bony tubes), but seemingly too small to supply enough blood to the cranium alone. This suggests that the ICA was not the main cranial blood supply in stem strepsirhines, but that the pharyngeal or vertebral artery primitively ensured a great part of this role instead, an arterial pattern that is reminiscent of modern cheirogaleid, lepilemurid lemuriforms and lorisiforms. This could explain parallel loss of the ICA functionality among these families. Specific measurements made on the cochlea indicate that the small strepsirhine primate(s) from Chambi was (were) highly sensitive to high frequencies and poorly sensitive to low frequencies. Finally, variance from orthogonality of the plane of the semicircular canals (SCs) calculated on one petrosal (CBI-1-569) suggests that Djebelemur or cf. Algeripithecus likely moved (at least its head) in a way similar to that of modern mouse lemurs.     

Purification and antibacterial activity of recombinant warnericin RK expressed in Escherichia coli

Warnericin RK is a small cationic peptide produced by Staphylococcus warneri RK. This peptide has an antimicrobial spectrum of activity almost restricted to the Legionella genus. It is a membrane-active peptide with a proposed detergent-like mechanism of action at high concentration. Moreover, the fatty acids content of Legionella was shown to modulate the peptide activity. In order to decipher the mode of action in details using solid-state NMR spectroscopy, large amount of an isotopic labeled peptide is required. Since it is less expensive to obtain such a peptide biologically, we report here methods to express warnericin RK in Escherichia coli with or without a fusion partner and to purify resulting recombinant peptides. The cDNA fragment encoding warnericin RK was synthesized and ligated into three expression vectors. Two fusion peptides, carrying polyhistidine tag in N- or C-terminal and a native peptide, without tag, were expressed in E. coli cells. Fusion peptides were purified, with a yield of 3 mg/l, by affinity chromatography and reverse-phase HPLC. The recombinant native peptide was purified using a two-step purification method consisting of a hydrophobic chromatography followed by a reverse-phase HPLC step with a yield of 1.4 mg/l. However, the anti-Legionella activity was lower for both tagged peptide probably because of structural modifications. So, the native recombinant peptide was preferentially chosen for ¹⁵N-labeling experiments. Our results suggest that the developed production and purification procedures will be useful in obtaining a large quantity of recombinant isotope-labeled warnericin RK for further studies.