Do dynamic global vegetation models capture the seasonality of carbon fluxes in the Amazon basin? A data‐model intercomparison

To predict forest response to long‐term climate change with high confidence requires that dynamic global vegetation models (DGVMs) be successfully tested against ecosystem response to short‐term variations in environmental drivers, including regular seasonal patterns. Here, we used an integrated dataset from four forests in the Brasil flux network, spanning a range of dry‐season intensities and lengths, to determine how well four state‐of‐the‐art models (IBIS, ED2, JULES, and CLM3.5) simulated the seasonality of carbon exchanges in Amazonian tropical forests. We found that most DGVMs poorly represented the annual cycle of gross primary productivity (GPP), of photosynthetic capacity (Pc), and of other fluxes and pools. Models simulated consistent dry‐season declines in GPP in the equatorial Amazon (Manaus K34, Santarem K67, and Caxiuanã CAX); a contrast to observed GPP increases. Model simulated dry‐season GPP reductions were driven by an external environmental factor, ‘soil water stress’ and consequently by a constant or decreasing photosynthetic infrastructure (Pc), while observed dry‐season GPP resulted from a combination of internal biological (leaf‐flush and abscission and increased Pc) and environmental (incoming radiation) causes. Moreover, we found models generally overestimated observed seasonal net ecosystem exchange (NEE) and respiration (R_e) at equatorial locations. In contrast, a southern Amazon forest (Jarú RJA) exhibited dry‐season declines in GPP and R_e consistent with most DGVMs simulations. While water limitation was represented in models and the primary driver of seasonal photosynthesis in southern Amazonia, changes in internal biophysical processes, light‐harvesting adaptations (e.g., variations in leaf area index (LAI) and increasing leaf‐level assimilation rate related to leaf demography), and allocation lags between leaf and wood, dominated equatorial Amazon carbon flux dynamics and were deficient or absent from current model formulations. Correctly simulating flux seasonality at tropical forests requires a greater understanding and the incorporation of internal biophysical mechanisms in future model developments.     

Strong genetic differentiation and low genetic diversity of the freshwater pearl mussel (<Emphasis Type="Italic">Margaritifera margaritifera</Emphasis> L.) in the southwestern European distribution range

Genetic diversity of European freshwater pearl mussel, Margaritifera margaritifera (L.), appears exceptional with highest genetic variability found in the northernmost European populations of Scandinavia and lower genetic variability in central and southern Europe. The objective of this study was to investigate genetic diversity and differentiation of 14 southernmost populations on the Iberian Peninsula which greatly differ in terms of life span and habitat conditions from the rest of central and northern European populations. The analyses of ten microsatellite loci revealed a pronounced level of genetic divergence and very low genetic diversity. These results match the expectations of geographically peripheral populations with respect to their genetic composition. The life history strategy, the narrow ecological niche of the species, and anthropogenic habitat modifications have most likely shaped the genetic pattern of Iberian pearl mussel populations. The peripheral position with less optimal habitat conditions may increase the extinction risk of these populations and thus effective conservation strategies for the Iberian M. margaritifera are needed. The successful conservation of the species at its southwestern margin requires inclusion of genetically different conservation units which may reveal local adaptation.     

Going deep into protein secondary structure with synchrotron radiation circular dichroism spectroscopy

Circular dichroism (CD) spectroscopy is a fast, powerful, well-established, and widely used analytical technique in the biophysical and structural biology community to study protein secondary structure and to track changes in protein conformation in different environments. The use of the intense light of a synchrotron beam as the light source for collecting CD measurements has emerged as an enhanced method, known as synchrotron radiation circular dichroism (SRCD) spectroscopy, that has several advantages over the conventional CD method, including a significant spectral range extension for data collection, deeper access to the lower limit (cut-off) of conventional CD spectroscopy, an improved signal-to-noise ratio to increase accuracy in the measurements, and the possibility to collect measurements in highly absorbing solutions. In this review, we discuss different applications of the SRCD technique by researchers from Latin America. In this context, we specifically look at the use of this method for examining the secondary structure and conformational behavior of proteins belonging to the four main classes of the hierarchical protein domain classification CATH (Class, Architecture, Topology, Homology) database, focusing on the advantages and improvements associated with SRCD spectroscopy in terms of characterizing proteins composed of different structural elements.     

The role of cytoplasmic catalase in dehydration tolerance of Saccharomyces cerevisiae

In this study, we investigated the role played by cytoplasmic catalase (Ctt1) in resistance against water loss using the yeast Saccharomyces cerevisiae as eukaryotic cell model. Comparing a mutant possessing a specific lesion in CTT1 with its parental strain, it was observed that both control and ctt1 strains exhibited increased levels of lipid peroxidation after dehydration, suggesting that catalase does not protect membranes during drying. Although the ctt1 strain has only 1 catalase isoform (peroxisomal catalase), the mutant showed the same levels of total catalase activity as the control strain. Furthermore, in cells deficient in Ctt1, the reduced glutathione:oxidized glutathione ratio (GSH:GSSG) of dry cells was higher than that of the control strain, indicating a compensatory mechanism of defense in response to dehydration. Even so, desiccation tolerance of the ctt1 strain was significantly lower than in the control strain. Using a fluorescent probe sensitive to oxidation, we observed that cells of the ctt1 strain showed levels of intracellular oxidation 70% higher than those of control strain, suggesting that Ctt1 plays a role in the maintenance of the intracellular redox balance during dehydration and, therefore, in tolerance against a water stress.     

Inactivation of Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa and Staphylococcus aureus on stainless steel and glass surfaces by neutral electrolysed water

AIM: To ascertain the efficacy of neutral electrolysed water (NEW) in reducing Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes on glass and stainless steel surfaces. Its effectiveness for that purpose is compared with that of a sodium hypochlorite (NaClO) solution with similar pH, oxidation-reduction potential (ORP) and active chlorine content. METHODS AND RESULTS: First, the bactericidal activity of NEW was evaluated over pure cultures (8.5 log CFU ml-1) of the abovementioned strains: all of them were reduced by more than 7 log CFU ml-1 within 5 min of exposure either to NEW (63 mg l-1 active chlorine) or to NaClO solution (62 mg l-1 active chlorine). Then, stainless steel and glass surfaces were inoculated with the same strains and rinsed for 1 min in either NEW, NaClO solution or deionized water (control). In the first two cases, the populations of all the strains decreased by more than 6 log CFU 50 cm-2. No significant difference (P相似文献   

Cutting edge: invariant V alpha 14 NKT cells are required for allergen-induced airway inflammation and hyperreactivity in an experimental asthma model

Airway hyperreactivity (AHR), eosinophilic inflammation with a Th2-type cytokine profile, and specific Th2-mediated IgE production characterize allergic asthma. In this paper, we show that OVA-immunized Jalpha18(-/-) mice, which are exclusively deficient in the invariant Valpha14(+) (iValpha14), CD1d-restricted NKT cells, exhibit impaired AHR and airway eosinophilia, decreased IL-4 and IL-5 production in bronchoalveolar lavage fluid, and reduced OVA-specific IgE compared with wild-type (WT) littermates. Adoptive transfer of WT iValpha14 NKT cells fully reconstitutes the capacity of Jalpha18(-/-) mice to develop allergic asthma. Also, specific tetramer staining shows that OVA-immunized WT mice have activated (CD69(+)) iValpha14 NKT cells. Importantly, anti-CD1d mAb treatment blocked the ability of iValpha14 T cells to amplify eosinophil recruitment to airways, and both Th2 cytokine and IgE production following OVA challenge. In conclusion, these findings clearly demonstrate that iValpha14 NKT cells are required to participate in allergen-induced Th2 airway inflammation through a CD1d-dependent mechanism.     

Glochidium metamorphosis in the endangered freshwater mussel Margaritifera auricularia (Spengler, 1793): a histological and scanning electron microscopy study

The metamorphosis of the glochidium of the critically endangered Margaritifera auricularia in the gills of a host is studied here for the first time. Siberian sturgeon, Acipenser baeri, were infected with glochidia and regularly inspected using scanning and optical microscopy. The mature glochidia immediately attach to the epithelium of the sturgeon gill filaments, piercing the secondary lamellae and the connective tissues, blood cells, and vessels within the lamellae. Once the epithelium is pierced, overlapping host lamellae cover the glochidium and form a cyst. Metamorphosis takes place inside the cyst. Sixteen days after infection the glochidium becomes spherical in shape and the larval muscle is reabsorbed. The two adductor muscles of the juvenile are observed 34 days after infection at 16-20 degrees C. Metamorphosis is complete in approximately 51 days at 18-22 degrees C and in 65 days at 16-17 degrees C. Released juveniles have a spherical shell with a thin rim of new shell material and a finely ciliated foot. Juvenile mean measurements are: length = 190 microm, width = 193 microm, and height = 210 microm.     

Experimental evidence and ecological perspectives for the adaptation of Schistosoma mansoni Sambon, 1907 (Digenea: Schistosomatidae) to a wild host,the water-rat,Nectomys squamipes Brants, 1827 (Rodentia: Sigmodontinae)

Due to the semi aquatic habits and the overlap of the geographical distribution of the water-rat, Nectomys spp., with schistosomiasis endemic areas, these wild rodents are very likely to acquire Schistosoma mansoni infection in their daily activities. The role of the water-rat in the S. mansoni cycle would be substantiated if one could prove that these rodents acquire the parasite during their own activity time, a completely independent time schedule of human activities. To pursue this goal, we performed two field experiments in the municipality of Sumidouro, State of Rio de Janeiro, Brazil, a schistosomiasis endemic area where N. squamipes is found naturally infected. One experiment was devised as a series of observations of activity time of the water-rat. The other experiment was a test of the occurrence of late transmission of S. mansoni to the water-rat. The daily activity pattern showed that the water-rat is active chiefly just after sunset. At both diurnal and late exposition essays the water-rat sentinels got infected by S. mansoni. These findings clarify ecological and behavioral components necessary to the adaptation of S. mansoni to the water-rat as a non human definitive host and the existence of a transmission cycle involving this animals as a reservoir.     

Comparison of two Ovsynch protocols (GnRH versus LH) for fixed timed insemination in buffalo (Bubalus bubalis)

We evaluated the efficiency of replacing GnRH with LH in the ovulation synchronization protocol in buffaloes. Buffaloes received GnRH on Day 0, (Buserelin; Conceptal, 20 microg), PGF2alpha (Luprostiol; Prosolvin, 15 mg) on Day 7 and GnRH (Buserelin; Conceptal, 10 microg; Group 1) or porcine LH (LH; Lutropin-V, 12.5 mg; Group 2) on Day 9. In Experiment 1, we studied the follicular dynamics of 30 buffaloes (Group 1, n = 15 and Group 2, n = 15). We performed ultrasonography every 12 h from Days 0 to 2, then on Day 7 and then every 6 h from the time of GnRH or LH treatment (Day 9) until the time of ovulation. All females not ovulating by 48 h after the second GnRH or LH injection were considered as nonresponders. In Experiment 2, we evaluated 305 buffaloes (Group 1, n = 154; Group 2, n = 151), using the same two treatments studied in Experiment 1. We also recorded and evaluated aspects like parity, lactational status, the presence of mucus, and uterine tone at the time of artificial insemination (Al). In Experiment 1, ovulation rate after the first GnRH was 86.6% (26/30). Ovulation rates were 93.3% (14/15; Group 1) after the second dose of GnRH and 93.3% (14/15) after LH (Group 2). Ovulation occurred 36.4+/-10.4 h after the first GnRH. The interval for treatment to ovulation was 26.5+/-9.6 h for buffaloes treated with GnRH (Group 1) and 24.4+/-7.9 h for buffaloes treated with LH (Group 2); the time of ovulation did not differ statistically between the two groups (GnRH versus LH; P > 0.05). In Experiment 2, conception rates of the animals AI in the field were 56.5% (Group 1) and 64.2% (Group 2), respectively (P = 0.08). The response to the treatment with LH was not different to the treatment with GnRH; however, multiparous buffaloes had higher conception rates than the primiparous buffaloes in both groups (P > 0.05). Buffaloes with mucus at the time of AI in Group 2 had higher conception rates than the buffaloes that had mucus in Group 1 (P < 0.05). Uterine tone and lactational status did not influence conception rates (P > 0.05). In summary, the results showed that both treatments resulted in synchronization of ovulation and acceptable conception rates. Therefore, the exogenous injection of LH can substitute the GnRH injections in the Ovsynch program in buffaloes.     

Heat shock protein micro-encapsulation as a double tool for the improvement of new generation vaccines

The modern vaccinology encompasses the recombinant DNA technology, protein and carbohydrate chemistry to obtain safe molecularly defined vaccines. Nevertheless most of the vaccines are poorly immunogenic because a large number of antigens are membrane proteins and consequently they are not present in their active conformation in the vaccine. Others are not as potent because they contain only B epitopes and therefore, cannot stimulate cellular memory. We have been studying the characteristics of the recombinant heat shock protein 18kDa-hsp from Mycobacterium leprae as an alternative carrier protein with a T epitope source to enhance the activity of these second generation vaccines. Here we proved that the 18kDa-hsp acted as carrier, without masking the activity of the carried antigen, with similar immune stimulatory effect when compared with ODN1668. Supramolecular aggregates of 18kDa-hsp and Mice serum albumin (MSA) were obtained using glutaraldehyde as cross linker. The Neisseria meningitides serogroup C polysaccharide (PSC, a B epitope) and the carrier protein 18kDa-hsp were co-encapsulated within Soybean phosphatidylcholine liposomes (SPC: Cho : alpha-Toc, 22 : 5 : 0.18 molar ratio, respectively). These liposomes were prepared in MPB buffer (20 mM phosphate, 295 mM mannitol pH 7.2) in the presence or absence of the ODN1668, TCCATGACGTTCCTGATGCT. When mice were injected with 18kDa-hsp-MSA no antibody against the MSA was observed. This means that the 18kDa-hsp acted as carrier, without masking the carried protein immune activity. Stable liposomes of 150 nm were obtained using mannitol as a cryoprotector. Genetically selected mice when injected with liposomes containing PSC and 18kDa-hsp displayed an antibody titer of 12. In contrast, in those mice injected with free PSC there was no response. The 18kDa-hsp adjuvant effect on the PSC liposomal formulation was comparable to that observed when ODN1668 was co-encapsulated with PSC. Confirming our expectations we observed that the formulation containing 18kDa-hsp conferred a memory response to the carried antigen--the Neisseria meningitidis serogroup C polysaccharide.