Gold trifluoromethyl complexes as efficient regioselective catalysts in alkyne hydration.

Gold (III) complexes containing trifluromethyl ligands are efficient catalyst in the hydration of alkynes, operating at low catalyst loadings, without additives, using environmentally friendly solvents and at mild conditions (60 ºC). Hydration of terminal and internal alkynes provide the corresponding ketones in quantitative yields without special precautions as dry solvents or inert atmospheres. Remarkably, hydration of asymmetric internal alkynes proceeds with moderate to notable regioselectivities, providing mixtures of the two possible isomers with ratios up to 90:10.

Reproductive morphophysiology of an iteroparous batch spawner fish: from early follicle development to ovulation.

Batch spawner fishes develop successive clutches of oocytes which allows them to participate in many reproductive cycles during their adult life (iteroparous) and spawn in multiple events within each breeding cycle. Here, ovarian follicular development was morpho-functionally analyzed in females of the iteroparous batch spawner fish Gymnocorymbus ternetzi. To obtain better insights into the reproductive morpho-physiology in batch spawners, the objective of this research was to analyze the dynamics of the follicular development, with its hormonal regulation between two active reproduction events. We found that over 16 days, follicles progressed asynchronously to chromatin nucleolus, Primary and Secondary growth stages of oogenesis with progressive secretion of 17ß-estradiol (E2). During the end of secondary growth, the increase in 17α,20ß-dihydroxy-4-pregnen-3-one (17,20ß-p) was measured relative to the maturation process of the ovarian follicles (e.g., nuclear migration and its rupture during the resumption of meiosis). Interestingly, an additional increase in E2 was observed after fish reproduction, probably related to the recruitment of new batch follicles for secondary growth. We also measured the high values of multiple condition factor post-reproduction measurements, reflecting more energy invested during the pre-reproductive process. We also quantified high concentrations of 17,20ß-p, probably related to the recruitment of a new batch of oogonia to meiosis, presumably secreted by post-ovulatory follicles, after fish reproduction. We finally found that fish without exposure to reproductive stimulus developed a regression phase at day 24, characterized by massive follicle atresia, that allow them to recycle energy and constitutive materials of the follicles invested during oogenesis for another reproductive cycle.

Genomic-based microsatellite development for Ternstroemia (Pentaphylacaceae) and transferability to other Ericales.

BACKGROUND: The genus Ternstroemia is associated with the vulnerable tropical montane cloud forest in Mexico and with other relevant vegetation types worldwide. It contains threatened and pharmacologically important species and has taxonomic issues regarding its species limits. This study describes 38 microsatellite markers generated using a genomic-based approach. METHODS AND RESULTS: We tested 23 of these markers in a natural population of Ternstroemia lineata. These markers are highly polymorphic (all loci polymorphic with 3-14 alleles per locus and expected heterozygosity between 0.202 and 0.908), most of them (19 out of 23) are in Hardy-Weinberg Equilibrium and free of null alleles (18 out of 23). Also we found no evidence of linkage among them. Finally, we tested the transferability to six other American species of Ternstroemia, two other Pentaphylacaceae species, and four species from different families within the order Ericales. CONCLUSIONS: These molecular resources are promising tools to investigate genetic diversity loss and as barcodes for ethnopharmacological applications and species delimitation in the family Pentaphylacaceae and some Ericales, among other applications.

Roles of the α1B-Adrenergic Receptor Phosphorylation Domains in Signaling and Internalization.

The function of the α1B-adrenergic receptor phosphorylation sites previously detected by mass spectrometry was evaluated by employing mutants, substituting them with non-phosphorylatable amino acids. Substitution of the intracellular loop 3 (IL3) sites did not alter baseline or stimulated receptor phosphorylation, whereas substitution of phosphorylation sites in the carboxyl terminus (Ctail) or both domains (IL3/Ctail) markedly decreased receptor phosphorylation. Cells expressing the IL3 or Ctail receptor mutants exhibited a noradrenaline-induced calcium-maximal response similar to those expressing the wild-type receptor, and a shift to the left in the concentration-response curve to noradrenaline was also noticed. Cells expressing the IL3/Ctail mutant exhibited higher apparent potency and increased maximal response to noradrenaline than those expressing the wild-type receptor. Phorbol ester-induced desensitization of the calcium response to noradrenaline was reduced in cells expressing the IL3 mutant and abolished in cells in which the Ctail or the IL3/Ctail were modified. In contrast, desensitization in response to preincubation with noradrenaline was unaffected in cells expressing the distinct receptor mutants. Noradrenaline-induced ERK phosphorylation was surprisingly increased in cells expressing IL3-modified receptors but not in those expressing receptors with the Ctail or IL3/Ctail substitutions. Our data indicate that phosphorylation sites in the IL3 and Ctail domains mediate and regulate α1B-adrenergic receptor function. Phorbol ester-induced desensitization seems to be closely associated with receptor phosphorylation, whereas noradrenaline-induced desensitization likely involves other elements.

Re-estimation of juvenile Isurus oxyrinchus growth in the Mexican Pacific through a multimodel inference approach and verification of growth band periodicity.

An update of the age and growth for juveniles of the short fin mako shark (I. oxyrinchus) from the Mexican Pacific is presented, based on the analysis of growth band counts from dorsal vertebrae of 198 individuals [110 females, 74-231 cm of total length (TL) and 88 males, 72-231 cm TL) caught during 2008-2018. New available information on vertebral growth band periodicity (biannual deposition in juveniles) and the convenience of using vertebrae form the dorsal region over the cervical region to count growth bands, as well as a multimodel approach, were used. The von Bertalanffy (VB) growth model, Gompertz, logistic and two parameters of VB (2-VB) were fitted to the length-at-age. Only ages ≤6 years were used for the fitting of the models and their performance was compared with the small-sample bias-corrected form of the Akaike information criterion (AICc), their differences ( ∆ i ) and weights ( w i ). Following a multimodel inference approach, the model averaged asymptotic length ( L ¯ inf ), length-at-age 0 ( L ¯ 0 ) and their unconditional standard error ( SE ¯ ), were estimated for each sex scenario using the three-parameter version of each model. The precision of growth band counts was acceptable for the different methods used and by two different readers. The centrum edge analysis (CEA) and marginal increment analysis (MIA) did not support the hypothesis of biannual band pair formation for juveniles, likewise for adults the periodicity could not be verified due to the small sample of large animals. Age was estimated assuming the formation of two pairs of growth bands per year during the first 5 years and one pair of bands per year afterwards considering direct validation information. The estimated ages in years ranged from 0-14 for females and 0-6 for males. The Kimura likelihood ratio test showed no differences in the growth curves of juveniles by sex (P > 0.05). According to the AICc, the 2-VB model better fitted the length-at-age data for combined sexes (Linf = 386.4 cm, k = 0.12 years-1 , L0 = 70 cm). The model averaged L ¯ inf and L ¯ 0 were 378.3 cm ( SE ¯ = 64.5 ) and 69.5 cm ( SE ¯ = 6.3 ), respectively. The growth parameters determined for juveniles of I. oxyrinchus are similar to those estimated in other regions, showing relatively fast growth rate as previously reported, medium longevity in comparison to other shark species and natural mortality close to that reported in the last stock assessment for the North Pacific Ocean. These life-history parameters should be considered to evaluate the population in the region and to develop better fishery management and conservation measures.

Historiographical approaches to biogeography: a critical review.

We performed a critical review of the historiographical studies on biogeography. We began with the pioneering works of Augustin and Alphonse de Candolle. Then, we analyzed the historical accounts of biogeography developed by (1) Martin Fichman and his history on the extensionism-permanentism debate; (2) Gareth Nelson and his critique of the Neo-Darwinian historiography of biogeography; (3) Ernst Mayr, with his dispersalist viewpoint; (4) Alan Richardson, who wrote a microhistory on the biogeographic model constructed by Darwin; (5) Michael Paul Kinch and the ideas discussed in the 19th century about the geographical distribution of living beings; (6) Janet Browne, who highlighted the importance of the pre-Darwinian naturalists; (7) Peter Bowler, who focused mainly on the influence of paleontology on biogeography; (8) James Larson, who looked into the practices of the naturalists of Northern Europe in the late 18th century; and (9) Malte Ebach, who like Larson, was more interested in analysing the practices rather than the ideas of naturalists who studied the geographical distribution of organisms. Finally, these works are compared with each other. There has not been a dominant paradigm in the construction of historical narratives of biogeography; however, they provide a useful context for understanding problems of biogeography that continue to be debated to this day.

Click synthesis of novel dendronized curcumin and analogs. Strengthening of physicochemical properties toward biological applications.

Curcumin and its analogs, chalcones, and C5-monocarbonyl are molecules of great therapeutic potential, but their poor stability and hydrophobicity have hampered their extensive use in clinical trials. Therefore, significant efforts have been made in materials science to improve their physicochemical properties. In this study, we propose dendronization as a synthetic strategy to strengthen some physicochemical properties such as solubility and stability of curcumin and analogs, taking advantage of the click chemistry (CuAAC) to attach second-generation polyester dendrons to the unsaturated cores. The dendronization, with the subsequent formation of aromatic triazole groups as linkers, not only modified the solubility and stability of the molecular systems but also favored the diketo tautomeric form of curcumin, as demonstrated spectroscopically. This result is significant since the diketo tautomer, which preserves the antioxidant properties of curcumin, is the most biologically active form. The hydrophobic/hydrophilic balance, achieved after dendronization, allowed the solubilization of the chromophoric molecules in buffered solutions at relevant pH values (7.4 and 6.4). Furthermore, the stability of all molecules was also upgraded since UV-vis absorption spectra did not exhibit modified profiles after 7 days at physiologic pH. From photochemical stability experiments irradiating at 415 nm, the dendritic derivatives containing triazole linkers were more susceptible to being degraded. All derivatives exhibited emission properties according to the length of each conjugate fragment. Fluorescence experiments evidenced the role of dendrons in preventing emission quenching by aggregation and exhibited differentiated emission behavior depending on the linker type (triazole or ester) between the chromophoric core and the polyester dendrons.

G protein-coupled receptors as therapeutic target.

Receptors are proteins coded by DNA, some of which have already been crystalized, thus allowing the details of their structure at the atomic level and some aspects of their function to be known. This review focuses on the most diverse and abundant family of receptors, G protein-coupled receptors. This family of receptors recognizes and mediates the action of several endogenous ligands (hormones, neurotransmitters, growth factors and local hormones) and also intervenes in the pathogenesis of various diseases, which is why they are targeted by approximately 30 to 40% of medications that are used in daily clinical practice and of various illegal drugs as well. X-ray crystallography is one of the essential tools that has allowed to observe the structure of these receptors in the amino acids that participate in this interaction, which allows to know the binding site of the endogenous ligand and of synthetic molecules that act on them to modulate their action. Molecular modeling or "docking" is also a computational bioinformatics tool that supports research on receptor-ligand binding, which allows the design and development of increasingly specific drugs. These developments have brought along significant changes in fundamental pharmacodynamic concepts.

Los receptores son proteínas codificadas por el ADN, algunos de los cuales ya han sido cristalizados, lo que permite conocer los detalles de su estructura a nivel atómico y algunos aspectos de su función. Esta revisión se enfoca en los más diversos y abundantes, los receptores acoplados a la proteína G. Esta familia de receptores reconoce y media la acción de varios ligandos endógenos (hormonas, neurotransmisores, factores de crecimiento y hormonas locales) y también interviene en la patogenia de diversas enfermedades, por lo que son el blanco terapéutico de aproximadamente 30 a 40 % de los medicamentos que se emplean en la práctica clínica cotidiana y de diversas drogas ilegales. La cristalografía de rayos X es una de las herramientas clave que ha permitido observar la estructura de estos receptores en los aminoácidos que participan en esta interacción, lo que posibilita conocer el sitio de unión del ligando endógeno y de moléculas sintéticas que actúan sobre ellos para modular su acción. El modelado molecular es también una herramienta bioinformática computacional que apoya la investigación sobre la unión receptor-ligando, que hace posible el diseño y desarrollo de fármacos cada vez más específicos. A estos desarrollos se suman importantes cambios en los conceptos farmacodinámicos fundamentales.

Different phosphorylation patterns regulate α1D-adrenoceptor signaling and desensitization.

Human α1D-adrenoceptors (α1D-ARs) are a group of the seven transmembrane-spanning proteins that mediate many of the physiological and pathophysiological actions of adrenaline and noradrenaline. Although it is known that α1D-ARs are phosphoproteins, their specific phosphorylation sites and the kinases involved in their phosphorylation remain largely unknown. Using a combination of in silico analysis, mass spectrometry and site directed mutagenesis, we identified distinct α1D-AR phosphorylation patterns during noradrenaline- or phorbol ester-mediated desensitizations. We found that the G protein coupled receptor kinase, GRK2, and conventional protein kinases C isoforms α/ß, phosphorylate α1D-AR during these processes. Furthermore, we showed that the phosphorylated residues are located in the receptor's third intracellular loop (S300, S323, T328, S331, S332, S334) and carboxyl region (S441, T442, T477, S486, S492, T507, S515, S516, S518, S543) and are conserved among orthologues but are not conserved among the other human α1-adrenoceptor subtypes. Additionally, we found that phosphorylation in either the third intracellular loop or carboxyl tail was sufficient to regulate calcium signaling desensitization. By contrast, mutations in either of these two domains significantly altered mitogen activated protein kinase (ERK) pathway and receptor internalization, suggesting that they have differential regulatory mechanisms. Our data provide new insights into the functional repercussions of these posttranslational modifications in signaling outcomes and desensitization.

Improving Catalyst Activity in Hydrocarbon Functionalization by Remote Pyrene-Graphene Stacking.

A copper complex bearing an N-heterocyclic carbene ligand with a pyrene "tail" attached to the backbone has been prepared and supported on reduced graphene oxide (rGO). The free and supported copper materials have been employed as homogeneous and heterogeneous catalysts in the functionalization of hydrocarbons such as n-hexane, cyclohexane, and benzene through incorporation of the CHCO2 Et unit from ethyl diazoacetate. The graphene-anchored complex displays higher reaction rates and induces higher yields than its soluble counterpart, features that can be rationalized in terms of a decrease in electron density at the metal center due to a remote net electronic flux from the supported copper complex to the graphene surface.

Possible female philopatry of the smooth hammerhead shark Sphyrna zygaena revealed by genetic structure patterns.

We assessed the spatial pattern of genetic structure of smooth hammerhead shark Sphyrna zygaena in 10 localities from the Northern Mexican Pacific. A total of 35 haplotypes were identified in 129 sequences of the mtDNA control region. The results showed slight but significant genetic structure among localities (ΦST = 0.044, P < 0.001). In addition, the localities with highest number of juveniles were genetically different (ΦST = 0.058, P < 0.024), which may be representative of nursery areas. The genetic differentiation pattern can be associated to female philopatry and preference for particular birthing sites. Finally, historical demography shows that S. zygaena populations present a recent demographic expansion that occurred during glacial events in the late Pleistocene to early Holocene.

Protein Kinase C Activation Promotes α1B-Adrenoceptor Internalization and Late Endosome Trafficking through Rab9 Interaction. Role in Heterologous Desensitization.

Upon agonist stimulation, α1B-adrenergic receptors couple to Gq proteins, calcium signaling and protein kinase C activation; subsequently, the receptors are phosphorylated, desensitized, and internalized. Internalization seems to involve scaffolding proteins, such as ß-arrestin and clathrin. However, the fine mechanisms that participate remain unsolved. The roles of protein kinase C and the small GTPase, Rab9, in α1B-AR vesicular traffic were investigated by studying α1B-adrenergic receptor-Rab protein interactions, using Förster resonance energy transfer (FRET), confocal microscopy, and intracellular calcium quantitation. In human embryonic kidney 293 cells overexpressing Discosoma spp. red fluorescent protein (DsRed)-tagged α1B-ARs and enhanced green fluorescent protein--tagged Rab proteins, pharmacological protein kinase C activation mimicked α1B-AR traffic elicited by nonrelated agents, such as sphingosine 1-phosphate (i.e., transient α1B-AR-Rab5 FRET signal followed by a sustained α1B-AR-Rab9 interaction), suggesting brief receptor localization in early endosomes and transfer to late endosomes. This latter interaction was abrogated by blocking protein kinase C activity, resulting in receptor retention at the plasma membrane. Similar effects were observed when a dominant-negative Rab9 mutant (Rab9-GDP) was employed. When α1B-adrenergic receptors that had been mutated at protein kinase C phosphorylation sites (S396A, S402A) were used, phorbol ester-induced desensitization of the calcium response was markedly decreased; however, interaction with Rab9 was only partially decreased and internalization was observed in response to phorbol esters and sphingosine 1-phosphate. Finally, Rab9-GDP expression did not affect adrenergic-mediated calcium response but abolished receptor traffic and altered desensitization. Data suggest that protein kinase C modulates α1B-adrenergic receptor transfer to late endosomes and that Rab9 regulates this process and participates in G protein-mediated signaling turn-off.

Catalytic Dehydrogenative Coupling of Hydrosilanes with Alcohols for the Production of Hydrogen On-demand: Application of a Silane/Alcohol Pair as a Liquid Organic Hydrogen Carrier.

The compound [Ru(p-cym)(Cl)2 (NHC)] is an effective catalyst for the room-temperature coupling of silanes and alcohols with the concomitant formation of molecular hydrogen. High catalyst activity is observed for a variety of substrates affording quantitative yields in minutes at room temperature and with a catalyst loading as low as 0.1 mol %. The coupling reaction is thermodynamically and, in the presence of a Ru complex, kinetically favourable and allows rapid molecular hydrogen generation on-demand at room temperature, under air, and without any additive. The pair silane/alcohol is a potential liquid organic hydrogen carrier (LOHC) for energy storage over long periods in a safe and secure way. Silanes and alcohols are non-toxic compounds and do not require special handling precautions such as high pressure or an inert atmosphere. These properties enhance the practical applications of the pair silane/alcohol as a good LOHC in the automotive industry. The variety and availability of silanes and alcohols permits a pair combination that fulfils the requirements for developing an efficient LOHC.

Catalytic Hydrogen Production by Ruthenium Complexes from the Conversion of Primary Amines to Nitriles: Potential Application as a Liquid Organic Hydrogen Carrier.

The potential application of the primary amine/nitrile pair as a liquid organic hydrogen carrier (LOHC) has been evaluated. Ruthenium complexes of formula [(p-cym)Ru(NHC)Cl2 ] (NHC=N-heterocyclic carbene) catalyze the acceptorless dehydrogenation of primary amines to nitriles with the formation of molecular hydrogen. Notably, the reaction proceeds without any external additive, under air, and under mild reaction conditions. The catalytic properties of a ruthenium complex supported on the surface of graphene have been explored for reutilization purposes. The ruthenium-supported catalyst is active for at least 10 runs without any apparent loss of activity. The results obtained in terms of catalytic activity, stability, and recyclability are encouraging for the potential application of the amine/nitrile pair as a LOHC. The main challenge in the dehydrogenation of benzylamines is the selectivity control, such as avoiding the formation of imine byproducts due to transamination reactions. Herein, selectivity has been achieved by using long-chain primary amines such as dodecylamine. Mechanistic studies have been performed to rationalize the key factors involved in the activity and selectivity of the catalysts in the dehydrogenation of amines. The experimental results suggest that the catalyst resting state contains a coordinated amine.

[Morphological changes in gametes of tiger barb Puntius tetrazona (Cypriniformes: Cyprinidae) and the implementation of in vitro fertilization]. / Cambios morfológicos en gametos del barbo tigre Puntius tetrazona (Cypriniformes: Cyprinidae) e implementación de la fertilización in vitro.

The production of ornamental fishes represents an economic activity of a growing number of Mexican families. Nevertheless, the reproduction of fish in captivity is one of the complications faced by farmers. This study was set up to: (i) evaluate the morphological and functional changes induced by hydration in the gametes of fish tiger barb (Puntius tetrazona; 240 samples) at tree times after hydration (10, 20 and 30s) with classic spermograms (volume, sperm concentration, viability, motility, and normal morphology); and (ii) evaluate the implementation of in vitro fertilization based on the ovulation rate, the percentage of fertilization and hatching; and the larval numbers obtained after 72 hours. The average volume of milt was 3.0 ± 0.7 µL, and the minimum, maximum and average concentration of sperm was 44.4 x 10(6) spz/mL, 52.3 x 10(6) spz/mL, and 48.1 ± 5.9 x 10(6) spz/mL, respectively. The viability and motility of the sperm was 84.6 ± 3.2% and 81.5 ± 2.2%, respectively. The diameter of the sperm with/without water contact was 2.10 ± 6 µm and 3.8 ± 1.0 µm (p < 0.05); the largest diameter was recorded 30 seconds after the contact with water. For oocytes, the smaller and larger diameters were recorded at 10 and 30s, respectively (both with/without water contact); the oocytes diameters after 10 and 30 seconds of contact with water were 1.11 and 1.55 mm, respectively. A higher ovulation rate was recorded using the in vitro fertilization: 250 ± 50 oocytes versus 28 ± 09 oocytes (during natural fertilization; p < 0.05). Nevertheless, fertilization and hatching rates were higher for the natural fertilization (80 and 60%, respectively). Considering the number of larvae obtained after 72 hours, our results showed a higher value for the in vitro fertilization (75 ± 18 compared to 13.4 ± 12 of the natural fertilization; p < 0.05). We propose this fish as a model for other ornamental fishes of commercial interest. Our results demonstrate that the in vitro fertilization is a very high viable option to optimize and maximize resources; besides, the reproduction management optimization under controlled conditions may enhance wild fish stocks preservation.

[Performance of recirculating aquaculture systems in the intensive farming of Pacú Piaractus mesopotamicus (Characiformes: Characidae)]. / Desempeño de los sistemas acuícolas de recirculación en el cultivo intensivo del Pacú Piaractus mesopotamicus (Characiformes: Characidae).

An alternative to intensify fish production, reducing the environmental impact and production costs are recirculating aquaculture systems (RAS). The performance of a RAS was evaluated, as fish growth and water quality conditions, in a culture of Piaractus mesopotamicus reared for ornamental purposes. Two commercial food brands with different protein contents (18%-T1 and 28%-T2), were given to juvenile fishes during an eight weeks period. Growth was measured bi-weekly: standard length (Lp), peak height (A), weight and multiple condition factor (KM). The evaluation of water parameters included: dissolved oxygen, NH3-NH4, pH, NO2, NO3, KH carbonate hardness and PO4. NH3-N rate production was analyzed following Timmons-Ebeling model. Results demonstrated significant differences in weight only, and T2 showed a 7.5% higher value than T1; nevertheless, treatment T1 had a higher KM. In general, water quality values were suitable for growth: OD=T1: 4.23 +/- 1.23; T2: 4.13 +/- 0.86; NH3=T1: 0.02 +/- 0.02; T2: 0.06 +/- 0.10; however, pH was an exception (T1: 6.95 +/- 0.98; T2: 7.11 +/- 1.03), displaying lethal rates (<5) by the fifth week. Systems NH3 removal had a 99.4% to 100% efficiency. Final fish biomass was 22.03kg for T1 and 27.49kg for T2. We concluded that the systems were able to maintain suggested density up to the experimental fifth week. Water quality parameters remained in suitable levels, with the pH exception. Cultured fishes reached their commercial size (10cm) in eight weeks.

Effect of cell size and thresholds in NDM/NVDM methods on recognizing areas of endemism.

Identifying areas of endemism has represented a great challenge, from the search for their definition, the design of methodologies, and the management of essential information to identify areas where the distributions of at least two taxa overlap. Endemicity Analysis is a widely used method that offers good results; however, an evaluation of the results is necessary. We evaluated the previous establishment of the minimum endemicity index of the species as a criterion to identify areas of endemism, applicated to a set of taxa with endemic and preferential distribution to the Sierra Madre Oriental. The taxa included in our analyses were 178 species of plants, vertebrates, and invertebrates. First, we varied the parameter set minimum score species in the software and the size of the cell. Next, we established criteria to evaluate the results obtained: areas supported by unique sets of species, good fit to the area, and sympatric distribution of taxa (extensive or homopatrid). After choosing the minimum ei with the best performance, we modified the study method for the endemicity analysis (Endemicity Analysis with Progressive Species Elimination). Our results indicate that the variation of the ei influenced the number of areas obtained by the program, decreasing considerably after evaluating the first criterion. The best fit to the cells occurred when we set 0.8 as the minimum ei in both cell sizes. The visually-preview of the sympatrid relationships allowed to recognize areas that do not present congruent distributions, although they meet the two previous criteria evaluated. The areas of endemism identified at different scales and those identified with the implementation of our modification were complementary.

Gold nanoparticle-catalysed functionalization of carbon-hydrogen bonds by carbene transfer reactions.

Gold nanoparticles stabilized by NHC ligands and supported onto reduced graphene oxide (rGO) catalyse the functionalization of cyclohexane and benzene C-H bonds upon insertion of carbene CHCO2Et (from N2CHCO2Et) groups. This is the first example in which such Csp3-H or Csp2-H bonds are functionalized with this strategy with nanoparticulated gold. This Au-NP@rGO material shows an exceptional activity, providing TON values 5-10 times higher than those already reported for molecular gold catalysts. Recyclability is also effective, reaching an accumulated TON value of 1400 after six consecutive uses.

Historical biogeography of the genus Rhadinaea (Squamata: Dipsadinae).

Multiple geological and climatic events have created geographical or ecological barriers associated with speciation events, playing a role in biological diversification in North and Central America. Here, we evaluate the influence of the Neogene and Quaternary geological events, as well as the climatic changes in the diversification of the colubrid snake genus Rhadinaea using molecular dating and ancestral area reconstruction. A multilocus sequence dataset was generated for 37 individuals of Rhadinaea from most of the biogeographical provinces where the genus is distributed, representing 19 of the 21 currently recognized species, and two undescribed species. Our analyses show that the majority of the Rhadinaea species nest in two main clades, herein identified as "Eastern" and "Southern". These clades probably diverged from each other in the early Miocene, and their divergence was followed by 11 divergences during the middle to late Miocene, three divergences during the Pliocene, and six divergences in the Pleistocene. The ancestral distribution of Rhadinaea was reconstructed across the Sierra Madre del Sur. Our phylogenetic analyses do not support the monophyly of Rhadinaea. The Miocene and Pliocene geomorphology, perhaps in conjunction with climate change, appears to have triggered the diversification of the genus, while the climatic changes during the Miocene probably induced the diversification of Rhadinaea in the Sierra Madre del Sur. Our analysis suggests that the uplifting of the Trans-Mexican Volcanic Belt and Chiapan-Guatemalan highlands in this same period resulted in northward and southward colonization events. This was followed by more recent, independent colonization events in the Pliocene and Pleistocene involving the Balsas Basin, Chihuahuan Desert, Pacific Coast, Sierra Madre Occidental, Sierra Madre Oriental, Sierra Madre del Sur, Trans-Mexican Volcanic Belt, and Veracruz provinces, probably driven by the climatic fluctuations of the time.

Reduced Graphene Oxides as Carbocatalysts in Acceptorless Dehydrogenation of N-Heterocycles.

The catalytic properties of graphene-derived materials are evaluated in acceptorless dehydrogenation of N-heterocycles. Among them, reduced graphene oxides (rGOs) are active (quantitative yields in 23 h) under mild conditions (130 °C) and act as efficient heterogeneous carbocatalysts. rGO exhibits reusability and stability at least during eight consecutive runs. Mechanistic investigations supported by experimental evidence (i.e., organic molecules as model compounds, purposely addition of metal impurities and selective functional group masking experiments) suggest a preferential contribution of ketone carbonyl groups as active sites for this transformation.