The “dehesa”, a key ecosystem in maintaining the diversity of Mediterranean saproxylic insects (Coleoptera and Diptera: Syrphidae)

The “dehesa” is a traditional Iberian agrosilvopastoral ecosystem characterized by the presence of old scattered trees that are considered as “keystone-structures”, which favor the presence of a wide range of biodiversity. We show the high diversity of saproxylic beetles and syrphids (Diptera) in this ecosystem, including red-listed species. We analyzed whether saproxylic species distribution in the “dehesa” was affected by tree density per hectare, dominant tree species or vegetation coverage. Species diversity did not correlate with tree density; however, it was affected by tree species and shrub coverage but in a different way for each taxon. The highest beetle diversity was linked to Quercus pyrenaica, the most managed tree species, with eight indicator species. In contrast, Q. rotundifolia hosted more species of saproxylic syrphids. Regarding vegetation coverage, shrub coverage was the only variable that affected insect richness, again in a different way for both taxa. In contrast, beetle species composition was only affected by dominant tree species whereas syrphid species composition was not affected by tree species or shrub coverage. We concluded that the high diversity of saproxylic insects in the “dehesa” is related to its long history of agrosilvopastoral management, which has generated landscape heterogeneity and preserved old mature trees. However, the richness and composition of different taxa of insects respond in different ways to tree species and vegetation coverage. Consequently, conservation strategies should try to maintain traditional management, and different saproxylic taxa should be used to monitor the effect of management on saproxylic diversity.     

Structural and optical properties of europium‐ and titanium‐doped Y2O3 nanoparticles

Luminescent nanoparticles of Y₂O₃ doped with europium (Eu) and/or titanium (Ti) were synthesized using modified sol–gel routes. The crystalline cubic phase was confirmed using X‐ray powder diffraction (XRD). Particle morphology and size were evaluated using scanning and transmission electron microscopy. High‐resolution transmission electron microscopy showed that the synthesis method affected the average particle size and the Fourier transform of the images showed the lattice plane distances, indicating that the samples presented high crystallinity degree in accordance with the XRD pattern. The Ti valence was investigated using X‐ray absorption near edge spectroscopy and the tetravalent form was the dominant oxidizing state in the samples, mainly in Eu and Ti co‐doped Y₂O₃. Optical behaviour was investigated through X‐ray excited optical luminescence and photoluminescence under ultraviolet–visible (UV–vis) and vacuum ultraviolet (VUV) excitation. Results indicated that Eu³⁺ is the emitting centre in samples doped with only Eu and with both Eu and Ti with the ⁵D₀→⁷F₂ transition as the most intense, indicating Eu³⁺ in a noncentrosymmetric site. Finally, in the Eu,Ti‐doped Y₂O₃ system, Ti³⁺ (or Ti^IV) excitation was observed but no Ti emission was present, indicating a very efficient energy transfer process from Ti to Eu³⁺. These results can aid the development of efficient nanomaterials, activated using UV, VUV, or X‐rays.     

Anomala trapezifera species-group: a burst of diversity (Coleoptera: Scarabaeidae: Rutelinae)

The species Anomala aereiventris n. sp., A. aspersa n. sp., A. atrivillosa n. sp., A. clarivillosa n. sp., A. contusa n. sp., A. eusticta n. sp., A. hiata n. sp., A. latifalculata n. sp., A. leopardina n. sp., A. levicollis n. sp., A. longisacculata n. sp., A. m-fuscum n. sp., A. perspicax n. sp., A. piccolina n. sp., A. globulata n. sp., A. stillaticia n. sp., A. subridens n. sp., A. subusta n. sp., A. tenoriensis n. sp., A. tuberculata n. sp. and A. vallisneria n. sp. from Costa Rica are described. These species and A. polygona Bates 1888, A. trapezifera Bates 1888 and A. vulcanicola Ohaus 1897 are placed in a new species-group, named after A. trapezifera, whose diagnosis is provided. Their distribution patterns are discussed.     

Purification of sarcoplasmic reticulum vesicles through their loading with calcium phosphate

A technique of purification of sarcoplasmic reticulum was devised through selective loading of the vesicular material with calcium phosphate. In presence of amount of disposable calcium lower than the maximum accumulation capacity of the total vesicular population, we have defined conditions of loading which allow the selection by centrifugation. The results described in this work show that about 30% of the starting material can be isolated as a vesicular population homogenous on the stand of the amount of accumulated cation. The purification is achieved by the removal of calcium by dissociation of the precipitate. Freeze-fracture electron microscopy studies show that the more active fraction when freed of calcium phosphate precipitate displays smooth convex (EF_s) and particulated concave (PF_p) fracture planes. It has been verified that the purification described in this work allows the removal of all the inactive material. The rate of calcium uptake of the selected preparation is about twice as large as that displayed by the starting material. The structural homogeneity of this material and the increase in the activity are good evidence for the purity of the selected sarcoplasmic reticulum vesicles.     

Inverse folding of RNA pseudoknot structures

Background  

RNA exhibits a variety of structural configurations. Here we consider a structure to be tantamount to the noncrossing Watson-Crick and G-U-base pairings (secondary structure) and additional cross-serial base pairs. These interactions are called pseudoknots and are observed across the whole spectrum of RNA functionalities. In the context of studying natural RNA structures, searching for new ribozymes and designing artificial RNA, it is of interest to find RNA sequences folding into a specific structure and to analyze their induced neutral networks. Since the established inverse folding algorithms, RNAinverse, RNA-SSD as well as INFO-RNA are limited to RNA secondary structures, we present in this paper the inverse folding algorithm Inv which can deal with 3-noncrossing, canonical pseudoknot structures.     

Sodium-, chloride-, and mibefradil-sensitive calcium channels in intestinal pacing in wild-type and W/WV mice

Pacing of intestinal smooth muscle is driven by a network of cells found in the myenteric plexus called the interstitial cells of Cajal (ICC-MP), which produce a rhythmic pacemaker current. Using intact segments of circular (CM) and longitudinal (LM) muscle from wild-type and W/WV mice, we found that sodium-, chloride-, and mibefradil-sensitive ion channel currents are required for normal pacing to occur. Application of 30 micromol/L and 300 micromol/L lidocaine, 1 mmol/L 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), 50 nmol/L and 500 nmol/L mibefradil, or low sodium Krebs significantly reduced pacing frequency in LM and CM. However, simultaneously applying DIDS and lidocaine or low sodium Krebs solution did not completely block pacing nor did it have an additive effect. Lidocaine and low sodium Krebs solution also abolished the gradient of pacing frequencies (higher proximally) found throughout the intestine, resulting in a uniform contraction frequency of 30-40/min. In W/WV mice, which lack ICC-MP, application of DIDS and lidocaine had no effect on the robust pacing in LM segments. In conclusion we found that sodium-, chloride-, and mibefradil-sensitive channel activities were required for normal pacing and to maintain the pacing gradient found throughout the intestines in wild-type but not W/WV mice.     

The hepatocytes of the brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis> f. <Emphasis Type="Italic">fario</Emphasis>): a stereological study of their number and size during the breeding cycle

A firm knowledge of the normal structure is crucial for evaluating pathological processes and morphofunctional correlations. Stereological liver structure characterization had its debut for mammals in the 1960s, but only in the 1980s did it start to be used in fishes. Using stereology, our aim was to verify the hypothesis that in parallel with the well-known annual seasonal changes in the liver–body ratio of brown trout, hepatocytes would vary their number and/or size, and that gender differences likely exist. Three-year-old specimens were used. Five animals per gender were examined in May (endogenous vitellogenesis), September (exogenous vitellogenesis), and February (spawning season end). The liver was fixed by perfusion, and its total volume estimated. Systematically sampled material was embedded in epoxy or in metachrylate resins. Stereology was executed on light and electron microscopy images. Unbiased design-based techniques were applied, using physical disectors and differential point counting. Target parameters were the relative (per unit volume) and total number of hepatocytes, the mean cell and nuclear volumes, and the total volumes of hepatocytes and their nuclei. Data support that in both genders the number of hepatocytes and the volume of its nucleus change along the breeding cycle. The cell number increased from endogenous to exogenous vitellogenesis (accompanying relative liver size gains), later followed by a decline in the cell number, still detectable after the spawning season. The total liver volumes of the cell and nucleus also increased from May to September in females, despite that the mean hepatocyte nuclear volume showed a minimum in September. No statistical changes in the mean cell volume were detected, regardless of the tendency for lower mean values in September. Changes were more marked in females and showed a higher correlation with the gonad weight. It was firstly suggested that numerical (rather than cell size) changes govern the shifts of the relative liver weight seen during the brown trout annual breeding cycle, and eventually of other fishes. We hypothesized that there are seasonal cycles of hepatocyte mitosis (from after spawning to exogenous vitellogenesis) and of apoptosis (at spawning). These cycles would be regulated by sex steroids, being more striking in females.