Analysis of some morphological and biochemical characteristics of the egg of the predaceous bugMacrolophus caliginosus (Het.: Miridae) during embryogenesis

The predaceous bug,Macrolophus caliginosus Wagner (Heteroptera: Miridae) is a biological control agent used in greenhouses in the French Mediterranean region. The egg of this mirid is embedded in plant tissues and all embryonic development occurs in this environment. In order to define an artificial substrate for egg-laying, exchanges of chemical substances between the egg and the host plant were investigated by morphological and biochemical analyses. Egg wet weight doubled throughout embryonic development, while egg dry weight did not vary. The amino acid content of the egg remained stable during embryogenesis. Only aspartic acid, serine and alanine decreased during the first five days of development. It can be concluded that exchanges mainly involved uptake of water by the egg.     

Adherens junction domains are split by asymmetric division of embryonic neural stem cells

Investigating the mechanisms controlling the asymmetric division of neocortical progenitors that generate neurones in the mammalian brain is crucial for understanding the abnormalities of cortical development. Partitioning of fate determinants is a key instructive step and components of the apical junctional complex (adherens junctions), including the polarity proteins PAR3 and aPKC as well as adhesion molecules such as N‐cadherin, have been proposed to be candidate determinants. In this study, however, we found no correlation between the partitioning of N‐cadherin and fate determination. Rather, we show that adherens junctions comprise three membrane domains, and that during asymmetrical division these are split such that both daughters retain the adhesive proteins that control cell position, but only one daughter inherits the polarity proteins along with the apical membrane. This provides a molecular explanation as to how both daughters remain anchored to the ventricular surface after mitosis, while adopting different fates.     

Necator americanus: the Na-ASP-2 protein secreted by the infective larvae induces neutrophil recruitment in vivo and in vitro

The L3-secreted Ancylostoma Secreted Protein-2 from the human hookworm Necator americanus (Na-ASP-2) has been selected as a candidate vaccine antigen in anticipation of clinical trials. Its crystal structure revealed that Na-ASP-2 has structural and charge similarities to CC-chemokines, suggesting that it might act as a chemokine mimic when released by the infective larvae during tissue migration. Using the air pouch model of acute inflammation, we found that Na-ASP-2 induced a significant leukocyte influx to the skin pouch, mostly comprised of neutrophils (60%) and monocytes (30%) that was transient and resolved in 24h. Other hookworm larval proteins did not cause any inflammatory leukocytes to migrate into air pouches. In vitro chemotaxis assays confirmed our results and demonstrated that leukocyte migration was a direct effect of Na-ASP-2 exposure and not caused by other molecules released by host cells in the inflammatory microenvironment or by the expression vector.     

Mannan chain length controls lipoglycans signaling via and binding to TLR2

TLR2 is a pattern-recognition receptor that is activated by a large variety of conserved microbial components, including lipoproteins, lipoteichoic acids, and peptidoglycan. Lipoglycans are TLR2 agonists found in some genera of the phylogenetic order Actinomycetales, including Mycobacterium. They are built from a mannosyl-phosphatidyl-myo-inositol anchor attached to a (alpha1-->6)-linked d-mannopyranosyl chain whose units can be substituted by d-mannopyranosyl and/or d-arabinofuranosyl units. At this time, little is known about the molecular bases underlying their ability to induce signaling via this receptor. We have recently shown that the anchor must be at least triacylated, including a diacylglyceryl moiety, whereas the contribution of the glycosidic moiety is not yet clearly defined. We show herein that lipoglycan activity is directly determined by mannan chain length. Indeed, activity increases with the number of units constituting the (alpha1-->6)-mannopyranosyl backbone but is also critically dependent on the substitution type of the 2-hydroxyl of these units. We thus provide evidence for the definition of a new pattern that includes the nonlipidic moiety of the molecules, most probably as a result of the (alpha1-->6)-mannopyranosyl backbone being a highly conserved structural feature among lipoglycans. Moreover, we demonstrate that lipoglycans can bind cell surface-expressed TLR2 and that their ability to induce signaling might be, at least in part, dictated by their avidity for the receptor. Finally, our data suggest that lipoglycans and lipoproteins have a common binding site. The present results are thus discussed in the light of the recently published crystal structure of a TLR1-TLR2-lipopeptide complex.     

Synthesis and evaluation of a novel series of pseudo-cinnamic derivatives as antituberculosis agents

In an effort to develop potent new antituberculous drugs effective against Mycobacterium tuberculosis, we have prepared series of cinnamic derivatives (thioesters and amides) with 4-hydroxy and 4-alkoxy groups and investigated the in vitro activities of these compounds. Among them some displayed a good in vitro antibacterial activity, such as (E)-N-(2-acetamidoethyl)-3-{4-[(E)-3,7-dimethylocta-2,6-dienyloxy]phenyl}acrylamide 4b that showed a minimum inhibitory concentration of 0.1 μg/mL (0.26 μM) against M. tuberculosis H37Rv.     

Asymmetric effects of cooler and warmer winters on beech phenology last beyond spring

In temperate trees, the timings of plant growth onset and cessation affect biogeochemical cycles, water, and energy balance. Currently, phenological studies largely focus on specific phenophases and on their responses to warming. How differently spring phenology responds to the warming and cooling, and affects the subsequent phases, has not been yet investigated in trees. Here, we exposed saplings of Fagus sylvatica L. to warmer and cooler climate during the winter 2013–2014 by conducting a reciprocal transplant experiment between two elevations (1,340 vs. 371 m a.s.l., ca. 6°C difference) in the Swiss Jura mountains. To test the legacy effects of earlier or later budburst on the budset timing, saplings were moved back to their original elevation shortly after the occurrence of budburst in spring 2014. One degree decrease in air temperature in winter/spring resulted in a delay of 10.9 days in budburst dates, whereas one degree of warming advanced the date by 8.8 days. Interestingly, we also found an asymmetric effect of the warmer winter vs. cooler winter on the budset timing in late summer. Budset of saplings that experienced a cooler winter was delayed by 31 days compared to the control, whereas it was delayed by only 10 days in saplings that experienced a warmer winter. Budburst timing in 2015 was not significantly impacted by the artificial advance or delay of the budburst timing in 2014, indicating that the legacy effects of the different phenophases might be reset during each winter. Adapting phenological models to the whole annual phenological cycle, and considering the different response to cooling and warming, would improve predictions of tree phenology under future climate warming conditions.     

Estrus synchronization in beef cows: comparison between GnRH+PGF2alpha+GnRH and PRID+PGF2alpha+eCG

The aim of this study was to compare two protocols for estrus synchronization in suckled beef cows over a 2 years period. The population studied consisted of 172 Charolais and 168 Limousin cows from 12 and 14 beef herds, respectively. In each herd, cows were allotted to groups according to parity, body condition score and calving difficulty. Cows in Group 1 (n=174) received PRID on Day-8 with estradiol benzoate (10mg, vaginal capsule), dinoprost on Day-4 (25mg i.m.), eCG on Day 2 (500 IU i.m.). The PRID was removed on Day-2 and cows were inseminated on Day 0, 56 h after PRID was removed. Cows in Group 2 (n=166) received GnRH on Day-10 (100 microg i.m.), dinoprost on Day-3 (25mg i.m.) and GnRH on Day-1 (100 microg i.m.), and were inseminated on Day 0, 16-24h after the last GnRH treatment. Plasma progesterone concentrations were measured to determine cyclicity prior to treatment (Days-20 and -10), to confirm the occurrence of ovulation (Days 0 and 10) and to determine the apparent early pregnancy rate (Days 0, 10 and 24). Pregnancy diagnosis was performed by ultrasonography between Days 35 and 45. The effects of various factors on ovulation, apparent early pregnancy and pregnancy rates were studied using logistic mixed models. There was no significant difference between Groups 1 and 2, respectively, for the cyclicity rate before treatment (80.5% versus 80.1%), for apparent pregnancy rate on Day 24 (62.1% versus 54.8%, P=0.09) and for pregnancy rate on Days 35-45 (53.8% versus 46.3%, P=0.16). Ovulation rate was higher (P<0.01) in Group 1 (90.8%) than in Group 2 (77.1%) and was affected by cyclicity prior to treatment in Group 2 but not in Group 1 (Group 1: 88.2% in anestrous cows versus 91.4% in cyclic cows; Group 2: 45.5% in anestrous cows versus 85.0% in cyclic cows, P interaction=0.05). Apparent pregnancy rates on Day 24 were influenced by the year of study (52.4% versus 68.8%, OR=2.12, P<0.01) and by the cyclicity before treatment (anestrous cows 46.3% versus cyclic cows 61.5%, OR=1.86, P<0.05). Pregnancy rates at 35-45 days were influenced by the year of study (44.2% versus 59.8%, OR=1.92, P<0.01). In conclusion, although pregnancy rates were similar for the two treatments, the combination of GnRH+PGF2alpha+GnRH in suckled beef cows induced a lower rate of ovulation than treatment with PRID+PGF2alpha, particularly in anestrous cows.     

Coordinate regulation of malonyl-CoA decarboxylase,sn-glycerol-3-phosphate acyltransferase,and acetyl-CoA carboxylase by AMP-activated protein kinase in rat tissues in response to exercise

Changes in the concentration of malonyl-CoA in many tissues have been related to alterations in the activity of acetyl-CoA carboxylase (ACC), the rate-limiting enzyme in its formation. In contrast, little is known about the physiological role of malonyl-CoA decarboxylase (MCD), an enzyme responsible for malonyl-CoA catabolism. In this study, we examined the effects of voluntary exercise on MCD activity in rat liver, skeletal muscle, and adipose tissue. In addition, the activity of sn-glycerol-3-phosphate acyltransferase (GPAT), which like MCD and ACC can be regulated by AMP-activated protein kinase (AMPK), was assayed. Thirty min after the completion of a treadmill run, MCD activity was increased approximately 2-fold, malonyl-CoA levels were reduced, and ACC and GPAT activities were diminished by 50% in muscle and liver. These events appeared to be mediated via activation of AMPK since: 1) AMPK activity was concurrently increased by exercise in both tissues; 2) similar findings were observed after the injection of 5-amino 4 imidazole carboxamide, an AMPK activator; 3) changes in the activity of GPAT and ACC paralleled that of MCD; and 4) the increase in MCD activity in muscle was reversed in vitro by incubating immunoprecipitated enzyme from the exercised muscle with protein phosphatase 2A, and it was reproduced by incubating immunopurified MCD from resting muscle with purified AMPK. An unexpected finding was that exercise caused similar changes in the activities of ACC, MCD, GPAT, and AMPK and the concentration of malonyl-CoA in adipose tissue. In conclusion: MCD, GPAT, and ACC are coordinately regulated by AMPK in liver and adipose tissue in response to exercise, and except for GPAT, also in muscle. The results suggest that AMPK activation plays a major role in regulating lipid metabolism in many cells following exercise. They also suggest that in each of them, it acts to increase fatty acid oxidation and decrease its esterification.