Zooplankton Variability and Copepod Species Assemblages from a Tropical Coastal Lagoon

Results of monthly zooplankton sampling, carried out from December 1990 to November 1991, are compared from three localities in the Mexican Caribbean. Two stations, Bojórquez, and Cuenca Norte, represent partially enclosed areas of the Nichupté Lagoon System in the northeastern region of the Yucatán Peninsula; a third station was located in adjacent neritic waters. At the neritic station, temperature was lower, salinity was higher, and variations in the two parameters smaller as compared to the two lagoon stations. Zooplankton abundance ranged from 3585.5 org./m3 at the neritic station to 18,742.7 org./m3 at Cuenca Norte. Considering all animals collected, decapod larvae (39%), copepods (28.7%) and ophiopluteus-echinopluteus larvae (22.8%) made the bulk of the catch. A total of 47 copepod species were recorded, of these, 14 were found at Bojórquez, 12 at Cuenca Norte and 42 at the neritic station. Acartia tonsa dominated the copepod population assemblage at Bojórquez (94.4%) and made important contributions at Cuenca Norte (34.5%) and in the neritic station (24.5%). Paracalanus quasimodo was most abundant at Cuenca Norte (40.3%) and contributed 20.9% at the neritic station. It is suggested that both, the high capture of A. tonsa in Bojórquez and the dominance of P. quasimodo at Cuenca Norte, is probably related with two factors: the anthropogenically nutrient-enriched condition of Bojórquez lagoon and the relatively higher breeding frequency of the chaetognath Sagitta hispida in Bojórquez. The highest abundance of zooplankters occurred at the stations within the lagoonal system, and the highest number of copepod species was found at the neritic station, where more stable conditions prevailed

RNA Pol II Length and Disorder Enable Cooperative Scaling of Transcriptional Bursting

RNA polymerase II (RNA Pol II) contains a disordered C-terminal domain (CTD) whose length enigmatically correlates with genome size. The CTD is crucial to eukaryotic transcription, yet the functional and evolutionary relevance of this variation remains unclear. Here, we investigate how CTD length and disorder influence transcription. We find that length modulates the size and frequency of transcriptional bursting. Disorder is highly conserved and facilitates CTD-CTD interactions, an ability we show is separable from protein sequence and necessary for efficient transcription. We build a data-driven quantitative model, simulations of which recapitulate experiments and support that CTD length promotes initial polymerase recruitment to the promoter and slows down its release from it and that CTD-CTD interactions enable recruitment of multiple polymerases. Our results reveal how these parameters provide access to a range of transcriptional activity, offering a new perspective for the mechanistic significance of CTD length and disorder in transcription across eukaryotes

Multiscale conceptual design of a scalable and sustainable process to dissolve and regenerate keratin from chicken feathers

A multiscale strategy was used to conceptually design and economically analyze a scalable and sustainable process for dissolving and regenerating keratin from chicken feathers by using a sodium acetate-urea deep eutectic solvent as the reacting media. In this study, the recovery and recycling of the solvent were also considered. Moreover, molecular modeling of the solvent, keratin and its derivatives, property estimation of the corresponding mixtures, and simulation of the different process alternatives proposed, including the equipment sizing, estimation of energy needs, and economic analysis were presented. A quasi-planar cluster governed by H-bond interactions resulted in the most stable configuration of the deep eutectic solvent. Molecular models having molecular weights higher than 1.400 g/mol were created to represent the keratin species, where the most abundant amino acids in the feathers were included and conveniently ordered in the chain. Property estimations performed with the conductor-like screening model-real solvent succeeded in describing the main features of the interactions between the keratin derivatives and the solvents used. The process analysis performed on several alternatives showed that the process is technically and economically viable at the industrial scale, the costs being strongly dependent on the excess of both the solvent used to dissolve keratin and the water added for its regeneration. Several options to improve the process and reduce the costs are discussedEuropeanUnion’s Horizon 2020 Researchand Innovation program undergrant agreement 72326

Análisis de la demanda de harina de trigo y semola en Colombia.

Trigo-Triticum aestivuMaestría en CienciasMaestrí

3D multi-robot patrolling with a two-level coordination strategy

Teams of UGVs patrolling harsh and complex 3D environments can experience interference and spatial conflicts with one another. Neglecting the occurrence of these events crucially hinders both soundness and reliability of a patrolling process. This work presents a distributed multi-robot patrolling technique, which uses a two-level coordination strategy to minimize and explicitly manage the occurrence of conflicts and interference. The first level guides the agents to single out exclusive target nodes on a topological map. This target selection relies on a shared idleness representation and a coordination mechanism preventing topological conflicts. The second level hosts coordination strategies based on a metric representation of space and is supported by a 3D SLAM system. Here, each robot path planner negotiates spatial conflicts by applying a multi-robot traversability function. Continuous interactions between these two levels ensure coordination and conflicts resolution. Both simulations and real-world experiments are presented to validate the performances of the proposed patrolling strategy in 3D environments. Results show this is a promising solution for managing spatial conflicts and preventing deadlocks

Ewe Daily-Weight Gain Grazing \u3ci\u3eLeucaena leucocephala-Megathyrsus maximus\u3c/i\u3e CV Mombasa Silvopastoral System and Tropical Native Unimproved Range

Silvopastoral systems are a viable option to increase livestock productivity, The silvopastoral arrangement of Leucaena leucocephala associated with Megathyrsus maximus CV Mombasa (LMS) is successfully cultivated in tropical environments.. The objective of the study was to determine ewe daily-weight gain grazing LMS and a tropical unimproved native range. Two LMS were tested: high and low leucaena densities, 4700 and 2383 plants/ha, respectively. Grazing was rotational, lasted 150 d (rainy season) at equivalent stocking rate of 59 ewes/ha/150 d. Experimental design was a completely random design with three replications, the experimental unit was a 192 m2 plot. Variables measured on plots were amount (dry matter basis), in vitro dry matter digestibility (IVDMD), and crude protein (CP) of forage on-offer, from mixed samples herbaceous and tree fodder. Weight and serum concentrations of Ca, P, K, Mg, Na, Zn, Cu, and Fe were measured in ewes, daily weight gain was calculated. On average forage on-offer and IVDMD concentration were 50 and 15% higher (p \u3c 0.05) in LMS than in native range, respectively, with no difference between LMS. CP concentration was 25% higher (p \u3c 0.05) in native range than both LMS, with no difference between them. LMS’s showed no difference (p \u3e 0.05) between them on ewe daily weight gain, on average 59.2 g, and were higher than native range where ewes showed a mean daily weight loss of 14.8 g. Serum concentrations of the 8 minerals measured were similar (p \u3e 0.05) across all ewes regardless the treatments. It was concluded that the Leucaena leucocephala-Megathyrsus maximus CV Mombasa silvopastoral system is an option to improve livestock productivity compared with unimproved native range due to higher forage on-offer

Ewe Daily-Weight Gain Grazing \u3ci\u3eLeucaena leucocephala-Megathyrsus maximus\u3c/i\u3e CV Mombasa Silvopastoral System and Tropical Native Unimproved Range

Silvopastoral systems are a viable option to increase livestock productivity, The silvopastoral arrangement of Leucaena leucocephala associated with Megathyrsus maximus CV Mombasa (LMS) is successfully cultivated in tropical environments.. The objective of the study was to determine ewe daily-weight gain grazing LMS and a tropical unimproved native range. Two LMS were tested: high and low leucaena densities, 4700 and 2383 plants/ha, respectively. Grazing was rotational, lasted 150 d (rainy season) at equivalent stocking rate of 59 ewes/ha/150 d. Experimental design was a completely random design with three replications, the experimental unit was a 192 m2 plot. Variables measured on plots were amount (dry matter basis), in vitro dry matter digestibility (IVDMD), and crude protein (CP) of forage on-offer, from mixed samples herbaceous and tree fodder. Weight and serum concentrations of Ca, P, K, Mg, Na, Zn, Cu, and Fe were measured in ewes, daily weight gain was calculated. On average forage on-offer and IVDMD concentration were 50 and 15% higher (p \u3c 0.05) in LMS than in native range, respectively, with no difference between LMS. CP concentration was 25% higher (p \u3c 0.05) in native range than both LMS, with no difference between them. LMS’s showed no difference (p \u3e 0.05) between them on ewe daily weight gain, on average 59.2 g, and were higher than native range where ewes showed a mean daily weight loss of 14.8 g. Serum concentrations of the 8 minerals measured were similar (p \u3e 0.05) across all ewes regardless the treatments. It was concluded that the Leucaena leucocephala-Megathyrsus maximus CV Mombasa silvopastoral system is an option to improve livestock productivity compared with unimproved native range due to higher forage on-offer

The influence of the complex topography and dynamic history of the montane Neotropics on the evolutionary differentiation of a cloud forest bird (Premnoplex brunnescens, Furnariidae)

Aim: To examine the effect of geographical barriers and habitat dynamics related to climatic oscillations on the phylogeography of a widespread passerine of Neotropical cloud forests, the spotted barbtail (Premnoplex brunnescens). Location: Neotropical humid forests of montane areas in lower Central America and South America. Methods: We sequenced two mitochondrial genes and one nuclear intron from specimens collected across the distribution of P. brunnescens. Phylogenetic relationships were inferred using Bayesian and maximum-likelihood methods. Groups with maximum differentiation were estimated with spatial analysis of molecular variance (SAMOVA). We estimated timing of differentiation and relationships among groups with a species-tree approach and historical demography with extended Bayesian skyline plots. Results: Six highly differentiated clades of P. brunnescens are distributed in lower Central America, Sierra Nevada de Santa Marta, northern Venezuelan mountains, the Northern Andes, central Peru, and southern Peru and Bolivia. Within the Northern Andes clade, six phylogroups were identified associated with different slopes and isolated cordilleras. Most clades occupy opposite sides of low-lying valleys and ridgelines, but little differentiation was observed across several putative barriers. Population divergence occurred in the late Miocene and Pliocene, perhaps in association with Andean uplift. Historical fluctuations in population sizes suggest that populations tracked the spatial dynamics of montane forests associated with glacial cycles. Main conclusions: Extensive genetic differentiation in mitochondrial and nuclear DNA exists among populations of P. brunnescens. Such marked divergence was probably promoted by the rugged topography and dynamic ecological history of the Neotropical mountains. Our study sheds light on mechanisms promoting population differentiation in the montane Neotropics. © 2014 John Wiley & Sons Ltd

Physical–chemical parameters and validation of a colorimetric method for deoxycholic and ursodeoxycholic acids: kit reagent and optical sensor

AbstractThe simple and low cost β-cyclodextrin (β-CD)–phenolphthalein (PHP) inclusion complex was used for both the study of physical–chemical parameters and validation of analytical procedures for deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA) determinations in different formulations. The usefulness of this inclusion complex is proposed either in the form of kit reagent and as an original optical sensor for DCA and UDCA. The results showed that temperature had a negative effect on the equilibrium constant resulting in high negative values of enthalpy and positive values of entropy. The half-life values for DCA and UDCA measurements were 68.71 and 294.71 days, respectively. The method was validated showing limits of detection and quantification of 4.92×10−5molL−1 and 1.64×10−4molL−1 for DCA, 1.14×10−5molL−1 and 3.79×10−5molL−1 for UDCA, respectively. The developed optical sensor also showed response linearity, ease of implementation and potential application in fast screening tasks even out of the laboratory