Marine amoebae from waters of northwest Spain, with comments on a potentially pathogenic euryhaline species

Of 17 species of free-living amoebae identified in various samples of salt water, only 1, Acanthamoeba polyphaga, is known to be a potential pathogen. While no deaths occurred when laboratory animals were inoculated with A. polyphaga to test for pathogenicity, the protozoa were present in the brain, liver and lungs of some but not all of the animals.     

Effects of Drought on CAM and Water Relations in Plants of Peperomia carnevalii

The mechanisms underlying the drought tolerance of Peperomiacarnevalii Steyermark (Piperaceae), a succulent herb growingin the understorey of seasonally dry forests, were examined.Crassulacean acid metabolism (CAM) was studied in the fieldand laboratory, and measurements of water status were made inplants subjected to drought in the greenhouse. Nocturnal acidaccumulation and day and night-time CO₂assimilation rates weregreatest in watered plants and decreased in drought. The proportionof CO₂recycled through CAM in droughted plants, with nocturnalCO₂uptake close to zero, was higher than in watered plants.Maximum quantum yield of chlorophyll fluorescence remained unchangedduring drought, but the PSII quantum yield at the photosyntheticphoton flux density at which the plants were grown was significantlydecreased. Leaf anatomy consists of a chlorophyll-less hydrenchymalocated beneath the upper epidermis, and a two-layered mesophyll.Leaves nearer to the apex are thinner than those nearer to thebase of the shoot. Drought caused a reduction in leaf thicknessdue to shrinkage of the hydrenchyma, but not of the mesophyll.This was associated with the occurrence of a gradient of osmoticpotential between these tissues. Comparison of water loss fromthin leaves of watered and droughted plants, either partly defoliatedat the lower nodes or intact, suggested that water moved fromthe thick to the thin leaves. This process was related to theoccurrence of a gradient of water potential between the thickand the thin leaves. Drought tolerance in P. carnevalii is achievedby the operation of CAM and the occurrence of water movementwithin and between leaves. Copyright 2000 Annals of Botany Company Crassulacean acid metabolism, fluorescence, hydrenchyma, mesophyll, Peperomia carnevalii, water relations     

Maturation and persistence of the anti-SARS-CoV-2 memory B cell response

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Interactions of the high-mobility-group-like Ceratitis capitata C1 proteins with DNA

We have studied the interactions of the high-mobility-group-like proteins (C1a1, C1a2 and C1b) from the fruit fly Ceratitis capitata with DNA. Nitrocellulose filter binding assays, thermal denaturation studies and spectrofluorimetry of the complexes revealed the existence of specific and nonspecific interactions. Thermal denaturation curves showed that the three proteins stabilized the DNA, thus suggesting a preferential binding to double-stranded DNA. The calculation of the thermodynamic parameters of the interactions showed that the nonspecific bindings were characterized by low association constants (Ka) with values ranging from 2.7 X 10(4) M-1 to 2.0 X 10(6) M-1. Also, the cooperativity of these interactions was relatively high (cooperativity factor, w, values ranging over 20-35), and the number of nucleotides involved was low (1-3 base pairs). On the other hand, the existence of specific interactions between C1 proteins and DNA was suggested by two facts: the retention of C. capitata [3H]DNA in nitrocellulose filters was only a low percentage of total input DNA and there was a marked size dependence of the binding (25% retention of a 40-kb DNA and only 3% retention with a DNA of 1 kb). The specific bindings had higher Ka values than the nonspecific ones, and they also were cooperative. Some differences were observed between C1b and the C1a proteins about the way they interact with C. capitata DNA.     

Hydrolysis of fish oil by hyperactivated rhizomucor miehei lipase immobilized by multipoint anion exchange

Rhizomucor miehei lipase (RML) is greatly hyperactivated (around 20‐ to 25‐fold toward small substrates) in the presence of sucrose laurate. Hyperactivation appears to be an intramolecular process because it is very similar for soluble enzymes and covalently immobilized derivatives. The hyperactivated enzyme was immobilized (in the presence of sucrose laurate) on cyanogen bromide‐activated Sepharose (very mild covalent immobilization through the amino terminal residue), on glyoxyl Sepharose (intense multipoint covalent immobilization through the region with the highest amount of Lys residues), and on different anion exchangers (by multipoint anionic exchange through the region with the highest density of negative charges). Covalent immobilization does not promote the fixation of the hyperactivated enzyme, but immobilization on Sepharose Q retains the hyperactivated enzyme even in the absence of a detergent. The hydrolysis of fish oils by these hyperactivated enzyme derivatives was sevenfold faster than by covalently immobilized derivatives and three and a half times faster than by the enzyme hyperactivated on octyl‐Sepharose. The open structure of the hyperactivated lipase is fairly exposed to the medium, and no steric hindrance should interfere with the hydrolysis of large substrates. These new hyperactivated derivatives seem to be more suitable for hydrolysis of oils by RML immobilized inside porous supports. In addition, the hyperactivated derivatives are fairly stable against heat and organic cosolvents. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011     

Behavioural modification of a social spider by a parasitoid wasp

1. Manipulation of host behaviour by parasitoids has long captured the imagination of ecologists. Parasitoid wasps in the Polysphincta group of genera develop as external parasitoids of spiders. 2. In the present study, the previously undescribed interaction between a Zatypota sp. wasp (Ichneumonidae) and a social spider Anelosimus eximius (Theridiidae) is described. The larva of this Zatypota wasp is found to induce its host to disperse from their communal web and build an entirely enclosed web consisting of densely spun silk. 3. The wasp is observed to target primarily immature A. eximius individuals, with 37.5–44% of nests in a given area being parasitised. Of those nests, approximately 1.3–2.0% of individuals are hosts to the parasitoid larvae. Larger spider colonies had a significantly higher probability of harbouring parasitoids. 4. This interaction results in unusual behaviours for A. eximius induced by the parasitoid: (i) leaving the protection of the social nest and (ii) building a unique, altered web that it would not otherwise build. It is suggested that the wasp may be tapping into ancestral dispersal behaviours in its host and that a social species provides this wasp an evolutionary advantage by allowing a stable host source.     

Habitat preference in the critically endangered yellow‐tailed woolly monkey (Lagothrix flavicauda) at La Esperanza,Peru

Habitat loss is one of the main threats to wildlife. Therefore, knowledge of habitat use and preference is essential for the design of conservation strategies and identification of priority sites for the protection of endangered species. The yellow‐tailed woolly monkey (Lagothrix flavicauda Humboldt, 1812), categorized as Critically Endangered on the IUCN Red List, is endemic to montane forests in northern Peru where its habitat is greatly threatened. We assessed how habitat use and preference in L. flavicauda are linked to forest structure and composition. The study took place near La Esperanza, in the Amazonas region, Peru. Our objective was to identify characteristics of habitat most utilized by L. flavicauda to provide information that will be useful for the selection of priority sites for conservation measures. Using presence records collected from May 2013 to February 2014 for one group of L. flavicauda, we classified the study site into three different use zones: low‐use, medium‐use, and high‐use. We assessed forest structure and composition for all use zones using 0.1 ha Gentry vegetation transects. Results show high levels of variation in plant species composition across the three use zones. Plants used as food resources had considerably greater density, dominance, and ecological importance in high‐use zones. High‐use zones presented similar structure to medium‐ and low‐use zones; thus it remains difficult to assess the influence of forest structure on habitat preference. We recommend focusing conservation efforts on areas with a similar floristic composition to the high‐use zones recorded in this study and suggest utilizing key alimentation species for reforestation efforts.     

Nature du priming de la circulation extracorporelle en chirurgie cardiaque adulte et pédiatrique

During the recent years a new debate occurred because of the introduction of a new generation of hydroxyethyl starches (HES) and of balanced cristalloids, for the composition of the priming for cardiopulmonary bypass in cardiac surgery. Colloids used for fluid therapy belong to two groups: gelatin (modified fluid gelatine – MFG – in France) and hydroxyethyl starch (HES). Isotonic saline is mainly used as a solvent of colloids even though responsible for hyperchloremic acidosis when perfused in large volume. Morbidity due to this metabolic disorder is not largely investigated but does not seem very deleterious. However maintenance of the metabolic and acid-base equilibrium encourages the use of balanced solutions as proposed for some HES colloids. Characteristics of HES 130/0.4-0.42 improve safety profile and are preferred, however deleterious effects of HES on hemostasis with increasing bleeding risk and risk of renal impairment, cornerstone in cardiac surgery, lead to a respect of doses, indications and contra-indications of HES. Discussion is mandatory for the use of the new colloids and crystalloids in the composition of the priming, particularly some non oncotic effect of the synthetic colloids must be elucidated to improve the choice between albumin and other colloids.