EVOLUTIONARY SHIFTS IN THE SPECTRAL PROPERTIES OF SPIDER SILKS

We measured the reflectance properties of unpigmented silks spun by a systematic array of primitive (Deinopoidea) and derived (Araneoidea) aerial, web-spinning spiders, as well as silks spun by Araneomorphae and Mygalomorphae spiders that do not spin aerial webs. Our data show that all of the primitive aerial web spinners produce catching silks with a spectral peak in the ultraviolet (UV), and cladistic analysis suggests that high UV reflection is the primitive character state for silk spectral properties. In contrast, all of the derived aerial web spinners produce silks that are spectrally flat or characterized by reduced reflectance in the UV. Correlated with the evolution of these catching silks is a 37-fold increase in species number and apparent habitat expansion. This suggests that the unique silk proteins spun by the araneoids have been important to their ecological and evolutionary diversity.     

2P1, a novel male mouse cDNA specifically expressed during meiosis

We screened a mouse germinal cell expression library with a probe derived from Sob1, a human testis-specific cDNA, and identified 2P1, a new mouse cDNA. A database search revealed that 2P1 was 91% identical to ORF1 of E3-3, a rat gene probably involved in the regulation of alternative splicing. Sequencing showed that 2P1 has a destabilization motif in its 3'-untranslated region. Northern blotting showed strong gene expression in the testis and weak expression in the epididymis, with no signal detected in other tissues. RT-PCR analysis confirmed testis and epididymis expression. In situ hybridization revealed that 2P1 mRNA was absent in spermatogonia but expressed in spermatocytes. This last result was confirmed by RT-PCR of FACS isolated primary spermatocytes (pachytene stage). Using RT-PCR, purified spermatids were also shown to express 2P1.     

Genetic structure of the xerophilous bromeliad Pitcairnia geyskesii on inselbergs in French Guiana – a test of the forest refuge hypothesis

Inselbergs are isolated granitic rock outcrops that provide distinctive ecological conditions. In northern South America they rise above the surrounding rainforest. Among inselberg specialists, Pitcairnia geyskesii (Bromeliaceae) is restricted to these habitats in French Guiana. We studied populations from 12 inselbergs using 7 microsatellite loci to give a "reverse image" of the reduction-expansion of the rainforest in the context of the refuge hypothesis. Our analyses showed that populations are fragmented with dispersal occurring only over very short distances. Genetic diversity was higher in northern French Guiana, whereas specific alleles were observed in the south. The results point to the occurrence of a dry corridor in the north, as hypothesized by Tardy (1998) based on charcoal analyses, whereas de Granville's (1982) hypothesis of a unique past refuge is not confirmed. Moreover, our data suggests the importance of Oyapock River as a pathway for range expansion, arguing against the potential role of the Inini-Camopi Mountains as a physical barrier. Finally, in spite of a strongly argued scenario in favour of a north-to-south migration history, a clear genetic isolation of P. geyskesii populations living on inselbergs of the Mitaraka archipelago suggests a distinct ancestry of the most southern populations.     

Development of a sensitive ELISA to quantify apolipoprotein CIII in nonhuman primate serum

Apolipoprotein CIII (apoCIII), a major constituent of triglyceride-rich lipoprotein, has been proposed as a key contributor to hypertriglyceridemia on the basis of its inhibitory effects on lipoprotein lipase. Many immunochemical methods have been developed for human apoCIII quantification, including ELISA. However, a sensitive and quantitative assay for nonhuman primates is not commercially available. We developed a sensitive, quantitative, and highly specific sandwich ELISA to measure apoCIII in both nonhuman primate and human serum. Our assay generates a linear calibration curve from 0.01 μg/ml to 10 μg/ml using an apoCIII standard that was purified from cynomolgus monkey serum. It is highly reproducible (intra- and interplate CV < 5% and < 8%, respectively), sensitive enough to distinguish 10% difference of apoCIII present in serum, and has no interference from purified human apolipoprotein AI, AII, B, CI, CII, or E. The same assay can also be used to measure human apoCIII with a linear calibration curve from 0.005 μg/ml to 1 μg/ml using purified human apoCIII as the standard. This fast and highly sensitive ELISA could be a useful tool to investigate the role of apoCIII in lipoprotein transport and cardiovascular disease.     

Identifying habitat conservation priorities and gaps for migratory shorebirds and waterfowl in California

Conservation of migratory shorebirds and waterfowl presents unique challenges due to extensive historic loss of wetland habitats, and current reliance on managed landscapes for wintering and migratory passage. We developed a spatially-explicit approach to estimate potential shorebird and waterfowl densities in California by integrating mapped habitat layers and statewide bird survey data with expert-based habitat rankings. Using these density estimates as inputs, we used the Marxan site-selection program to identify priority shorebird and waterfowl areas at the ecoregional level. We identified 3.7 million ha of habitat for shorebirds and waterfowl, of which 1.4 million ha would be required to conserve 50% of wintering populations. To achieve a conservation goal of 75%, more than twice as much habitat (3.1 million ha) would be necessary. Agricultural habitats comprised a substantial portion of priority areas, especially at the 75% level, suggesting that under current management conditions, large areas of agricultural land, much of it formerly wetland, are needed to provide the habitat availability and landscape connectivity required by shorebird and waterfowl populations. These habitats were found to be largely lacking recognized conservation status in California (96% un-conserved), with only slightly higher levels of conservation for priority shorebird and waterfowl areas. Freshwater habitats, including wetlands and ponds, were also found to have low levels of conservation (67% un-conserved), although priority shorebird and waterfowl areas had somewhat higher levels of conservation than the state as a whole. Conserving migratory waterfowl and shorebirds will require a diversity of conservation strategies executed at a variety of scales. Our modeled results are complementary with other approaches and can help prioritize areas for protection, restoration and other actions. Traditional habitat protection strategies such as conservation easements and fee acquisitions may be of limited utility for protecting and managing significant areas of agricultural lands. Instead, conservation strategies focused on incentive-based programs to support wildlife friendly management practices in agricultural settings may have greater utility and conservation effectiveness.     

Mechanisms of TNF induction by heat-killed Staphylococcus aureus differ upon the origin of mononuclear phagocytes

Mononuclear phagocytes are among the first immune cells activated after pathogens invasion. Although they all derive from the same progenitor in the bone marrow, their characteristics differ on the compartment from which they are derived. In this work, we investigated the contribution of phagocytosis for tumor necrosis factor (TNF) production by murine mononuclear phagocytes (monocytes, peritoneal and alveolar macrophages) in response to heat-killed Staphylococcus aureus (HKSA). Mononuclear phagocytes behaved differently, depending on their compartment of residence. Indeed, when bacterial uptake or phagosome maturation was blocked, activation through membrane receptors was sufficient for a maximal production of TNF and interleukin-10 by peritoneal macrophages. In contrast, monocytes, and to a lesser extent alveolar macrophages, required phagocytosis for optimal cytokine production. While investigating the different actors of signalization, we found that p38 kinase and phosphatidylinositol 3-kinase were playing an important role in HKSA phagocytosis and TNF production. Furthermore, blocking the α(5)β(1)-integrin significantly decreased TNF production in response to HKSA in all three cell types. Finally, using mononuclear phagocytes from NOD2 knockout mice, we observed that TNF production in response to HKSA was dependent on NOD2 for monocytes and peritoneal macrophages. In conclusion, we demonstrate that the mechanisms of activation leading to TNF production in response to HKSA are specific for each mononuclear phagocyte population and involve different recognition processes and signaling pathways. The influence of the compartments on cell properties and behavior should be taken into account, to better understand cell physiology and host-pathogen interaction, and to define efficient strategies to fight infection.