Protected areas have a mixed impact on waterbirds, but management helps.

International policy is focused on increasing the proportion of the Earth's surface that is protected for nature1,2. Although studies show that protected areas prevent habitat loss3-6, there is a lack of evidence for their effect on species' populations: existing studies are at local scale or use simple designs that lack appropriate controls7-13. Here we explore how 1,506 protected areas have affected the trajectories of 27,055 waterbird populations across the globe using a robust before-after control-intervention study design, which compares protected and unprotected populations in the years before and after protection. We show that the simpler study designs typically used to assess protected area effectiveness (before-after or control-intervention) incorrectly estimate effects for 37-50% of populations-for instance misclassifying positively impacted populations as negatively impacted, and vice versa. Using our robust study design, we find that protected areas have a mixed impact on waterbirds, with a strong signal that areas managed for waterbirds or their habitat are more likely to benefit populations, and a weak signal that larger areas are more beneficial than smaller ones. Calls to conserve 30% of the Earth's surface by 2030 are gathering pace14, but we show that protection alone does not guarantee good biodiversity outcomes. As countries gather to agree the new Global Biodiversity Framework, targets must focus on creating and supporting well-managed protected and conserved areas that measurably benefit populations.

Integrative Proteomics and Phosphoproteomics Profiling Reveals Dynamic Signaling Networks and Bioenergetics Pathways Underlying T Cell Activation.

The molecular circuits by which antigens activate quiescent T cells remain poorly understood. We combined temporal profiling of the whole proteome and phosphoproteome via multiplexed isobaric labeling proteomics technology, computational pipelines for integrating multi-omics datasets, and functional perturbation to systemically reconstruct regulatory networks underlying T cell activation. T cell receptors activated the T cell proteome and phosphoproteome with discrete kinetics, marked by early dynamics of phosphorylation and delayed ribosome biogenesis and mitochondrial activation. Systems biology analyses identified multiple functional modules, active kinases, transcription factors and connectivity between them, and mitochondrial pathways including mitoribosomes and complex IV. Genetic perturbation revealed physiological roles for mitochondrial enzyme COX10-mediated oxidative phosphorylation in T cell quiescence exit. Our multi-layer proteomics profiling, integrative network analysis, and functional studies define landscapes of the T cell proteome and phosphoproteome and reveal signaling and bioenergetics pathways that mediate lymphocyte exit from quiescence.

Successful conservation of global waterbird populations depends on effective governance.

Understanding global patterns of biodiversity change is crucial for conservation research, policies and practices. However, for most ecosystems, the lack of systematically collected data at a global level limits our understanding of biodiversity changes and their local-scale drivers. Here we address this challenge by focusing on wetlands, which are among the most biodiverse and productive of any environments and which provide essential ecosystem services, but are also amongst the most seriously threatened ecosystems. Using birds as an indicator taxon of wetland biodiversity, we model time-series abundance data for 461 waterbird species at 25,769 survey sites across the globe. We show that the strongest predictor of changes in waterbird abundance, and of conservation efforts having beneficial effects, is the effective governance of a country. In areas in which governance is on average less effective, such as western and central Asia, sub-Saharan Africa and South America, waterbird declines are particularly pronounced; a higher protected area coverage of wetland environments facilitates waterbird increases, but only in countries with more effective governance. Our findings highlight that sociopolitical instability can lead to biodiversity loss and undermine the benefit of existing conservation efforts, such as the expansion of protected area coverage. Furthermore, data deficiencies in areas with less effective governance could lead to underestimations of the extent of the current biodiversity crisis.

Going back to "basics": Harlow's learning set task with wolves and dogs.

To survive and reproduce, animals need to behave adaptively by adjusting their behavior to their environment, with learning facilitating some of these processes. Dogs have become a go-to model species in comparative cognition studies, making our understanding of their learning skills paramount at multiple levels, not only with regards to basic research on their cognitive skills and the effects of domestication, but also with applied purposes such as training. In order to tackle these issues, we tested similarly raised wolves and dogs in a serial learning task inspired by Harlow's "learning set." In Phase 1, different pairs of objects were presented to the animals, one of which was baited while the other was not. Both species' performance gradually improved with each new set of objects, showing that they "learnt to learn," but no differences were found between the species in their learning speed. In Phase 2, once subjects had learned the association between one of the objects and the food reward, the contingencies were reversed and the previously unrewarded object of the same pair was now rewarded. Dogs' performance in this task seemed to be better than wolves', albeit only when considering just the first session of each reversal, suggesting that the dogs might be more flexible than wolves. Further research (possibly with the aid of refined methods such as computer-based tasks) would help ascertain whether these differences between wolves and dogs are persistent across different learning tasks.

Karyotypic characterization of Centromochlus schultzi Rössel 1962 (Auchenipteridae, Centromochlinae) from the Xingu River basin: New inferences on chromosomal evolution in Centromochlus.

Centromochlinae is a widely diverse subfamily with more than 50 species and several taxonomic conflicts due to morphological similarity between Tatia and Centromochlus species. However, cytogenetic studies on this group have been limited to only four species so far. Therefore, here we present the karyotype of Centromochlus schultzi from the Xingu River in Brazil using classic cytogenetic techniques, physical mapping of the 5S and 18S rDNAs, and telomeric sequences (TTAGGG)n. The species had 58 chromosomes, simple NORs and 18S rDNA sites. Heterochromatic regions were detected on the terminal position of most chromosomes, including pericentromeric and centromeric blocks that correspond to interstitial telomeric sites. The 5S rDNA had multiple sites, including a synteny with the 18S rDNA in the pair 24st, which is an ancestral feature for Doradidae, sister group of Auchenipteridae, but appears to be a homoplastic trait in this species. So far, C. schultzi is only the second species within Centromochlus to be karyotyped, but it has already presented characteristics with great potential to assist in future discussions on taxonomic issues in the subfamily Centromochlinae, including the first synteny between rDNAs in Auchenipteridae and also the presence of heterochromatic ITSs that could represent remnants of ancient chromosomal fusions.

Electronic and magnetic properties of TATA-DNA sequence driven by chemical functionalization.

The TATA box is a promoter sequence able to interact directly with the components of the basal transcription initiation machinery. We investigate the changes in the electronic and magnetic properties of a TATA-DNA sequence when functionalized with different chemical groups; using the first-principles density functional theory specifically, the TATA-DNA sequences were functionalized with methyl groups (CH3 , methylation), amino groups (NH2 , amination), imine groups (NH, imination), chloroamine groups (NCl2 , chloramination), H-adatom (hydrogenation), and Cl-adatom (chlorination). The functional groups were anchored at nitrogen atoms from adenine and oxygen atoms from thymine at sites pointed as reactive regions. We demonstrated that chemical functionalization induces significant changes in charge transfer, hydrogen bond distance, and hydrogen bond energy. The hydrogenation and imination increased the hydrogen bond energy. Results also revealed that the chemical functionalization of DNA molecules exhibit a ferromagnetic ground state, reaching magnetization up to 4.665 µB and complex magnetic ordering. We further demonstrated that the functionalization could induce tautomerism (proton migration in the base pair systems). The present study provides a theoretical basis for understanding the functionalization further into DNA molecules and visualizing possible future applications.

Phase transitions and topological defects in discotic liquid crystal droplets with planar anchoring: a Monte Carlo simulation study.

In this work we present the results of Monte Carlo (MC) simulations at the isothermal-isobaric ensemble for a discotic liquid crystal (DLC) droplet whose surface promotes edge-on (planar) anchoring. For a given pressure, we simulate an annealing process that enables observation of phase transitions within the spherical droplet. In particular, we report a first order isotropic-nematic transition as well as a nematic-columnar transition at the center of the droplet. We found the appearance of topological defects consisting of two disclination lines with ends at the surface of the sphere. We also observed that both transitions, isotropic-nematic and nematic-columnar, occur at lower temperatures as compared to the unconfined system.

Identifying fish eggs and larvae: from classic methodologies to DNA metabarcoding.

Studies involving fish eggs and larvae date back to the end of the nineteenth century. Since then, studies with ichthyoplankton have proved to be an essential tool, generating information for the knowledge of the ichthyofauna and the environmental inventory. Most of these studies reveal the difficulty of obtaining a precise taxonomic identification of the collected materials, making research with ichthyoplankton extremely challenging. With the advent of molecular biology, the use of markers such as COI enabled greater taxonomic precision, helping to understand events involving ichthyofauna. Now we can observe the evolution of the molecular identification tool for ichthyoplankton via DNA barcoding, which has been increasingly used over the last few decades. From 2000 to 2010, we found six publications; from 2011 to 2021, 75 papers were published, and in 2022 four studies. Our survey also showed the accuracy of molecular identification when compared to the taxonomic identification of these. In this review, we show the state of the art of studies that used barcode and DNA metabarcoding to identify fish eggs and larvae in different environments and discuss their importance as the best practice for working with these organisms.

Homeostatic control of metabolic and functional fitness of Treg cells by LKB1 signalling.

Regulatory T cells (Treg cells) have a pivotal role in the establishment and maintenance of immunological self-tolerance and homeostasis. Transcriptional programming of regulatory mechanisms facilitates the functional activation of Treg cells in the prevention of diverse types of inflammatory responses. It remains unclear how Treg cells orchestrate their homeostasis and interplay with environmental signals. Here we show that liver kinase B1 (LKB1) programs the metabolic and functional fitness of Treg cells in the control of immune tolerance and homeostasis. Mice with a Treg-specific deletion of LKB1 developed a fatal inflammatory disease characterized by excessive TH2-type-dominant responses. LKB1 deficiency disrupted Treg cell survival and mitochondrial fitness and metabolism, but also induced aberrant expression of immune regulatory molecules including the negative co-receptor PD-1 and the TNF receptor superfamily proteins GITR and OX40. Unexpectedly, LKB1 function in Treg cells was independent of conventional AMPK signalling or the mTORC1-HIF-1α axis, but contributed to the activation of ß-catenin signalling for the control of PD-1 and TNF receptor proteins. Blockade of PD-1 activity reinvigorated the ability of LKB1-deficient Treg cells to suppress TH2 responses and the interplay with dendritic cells primed by thymic stromal lymphopoietin. Thus, Treg cells use LKB1 signalling to coordinate their metabolic and immunological homeostasis and to prevent apoptotic and functional exhaustion, thereby orchestrating the balance between immunity and tolerance.

Health literacy on quality of life for children with cancer: modules on pediatric palliative care.

Objective: To describe the development of educational materials for parents and other caregivers of children with cancer, which utilized a culturally sensitive approach to reduce acceptance barriers to palliative care (PC). Methods: The Pan American Health Organization (PAHO), St. Jude Children's Research Hospital, and partners in Latin America and the Caribbean collaborated in a three-phase project, beginning with a needs assessment survey of caregivers of children with cancer in Peru. Based on this finding, an interdisciplinary team of pediatric PC experts developed educational content that was designed and validated by an international committee of PC and communication experts. Results: The collaboration resulted in the development of an eight-module series that introduces caregivers to key concepts of pediatric PC, including management of pain, quality of life, and end of life care. The series was designed to reduce caregiver stigma associated with PC through culturally sensitive education that addresses the low levels of health literacy among caregivers in Latin America and the Caribbean. In the 15 months since the launch, these modules have been distributed throughout Latin America and were downloaded 2 825 times. Conclusions: Educational materials and anticipatory guidance of PC were considered to be a priority for parents and other caregivers of children with cancer throughout Latin America. The materials developed through this project have been widely utilized and are available through the PAHO website and the Together by St. Jude™ online resource.

Collaboration for success: the Global Initiative for Childhood Cancer in Latin America.

The Global Initiative for Childhood Cancer (GICC) aims to increase the cure rate for children with cancer globally by improving healthcare access and quality. The Pan American Health Organization (PAHO), St. Jude Children's Research Hospital (St. Jude), and collaborators have joined efforts to improve outcomes of children with cancer in Latin America and the Caribbean (LAC) using the CureAll framework. In this article, we describe the process of developing regional resources aimed at accelerating the GICC implementation in LAC. In March 2021, PAHO formed regional working groups to develop core projects aligned with CureAll pillars and enablers. Seven working groups emerged from regional dialogues: early detection, nursing, psychosocial, nutrition, supportive care, treatment abandonment, and palliative care. PAHO arranged regular online meetings under the mentorship and support of St. Jude regional/transversal programs and international mentors. Between April and December 2021, 202 multidisciplinary experts attended 43 online meetings to promote the dialogue between stakeholders to improve childhood cancer outcomes. Fourteen technical outputs were produced: four regional snapshots, four technical documents, two virtual courses, one set of epidemiological country profiles, one educational content series for parents/caregivers, and two communication campaigns. The ongoing dialogue and commitment of PAHO, St. Jude, LAC working committees, and international collaborators are essential foundations to successfully accelerate GICC implementation. This is achievable through the development of materials of regional and global relevance. Further research and evaluation are needed to determine the impact of these strategies and resources on childhood cancer outcomes in LAC and other regions.

La Iniciativa Mundial contra el Cáncer Infantil tiene como objetivo aumentar a nivel mundial la tasa de curación del cáncer infantil mediante la mejora del acceso a la atención de salud y de su calidad. La Organización Panamericana de la Salud (OPS), el St. Jude Children's Research Hospital y los colaboradores han aunado esfuerzos para mejorar los resultados en la población infantil con cáncer en América Latina y el Caribe valiéndose del marco CureAll. En este artículo describimos el proceso de elaboración de recursos regionales destinados a acelerar la aplicación de la Iniciativa Mundial en América Latina y el Caribe.En marzo del 2021, la OPS formó grupos de trabajo regionales para elaborar proyectos básicos que estuvieran en consonancia con los pilares y los elementos facilitadores del CureAll. De los diálogos regionales surgieron siete grupos de trabajo: detección temprana, enfermería, aspectos psicosociales, nutrición, tratamientos de apoyo, abandono del tratamiento y cuidados paliativos. La OPS organizó con regularidad reuniones virtuales en las que se contó con la tutoría y el apoyo de programas regionales o transversales del St. Jude Children's Research Hospital y de mentores internacionales.Entre abril y diciembre del 2021 hubo 43 reuniones virtuales a las que asistieron 202 expertos multidisciplinarios, con el objetivo de promover el diálogo entre las partes interesadas para mejorar los resultados en materia de cáncer infantil. Se elaboraron catorce productos técnicos: cuatro panoramas regionales, cuatro documentos técnicos, dos cursos virtuales, un conjunto de perfiles epidemiológicos de países, una serie con contenidos educativos para padres y cuidadores y dos campañas de comunicación.El diálogo y el compromiso constantes de la OPS, el St. Jude Children's Research Hospital, los comités de trabajo de América Latina y el Caribe y los colaboradores internacionales son las bases fundamentales para conseguir que se acelere la aplicación de la Iniciativa Mundial. Esto se puede lograr mediante la elaboración de materiales que resulten pertinentes a nivel regional y mundial. Son necesarias más investigaciones y evaluaciones para determinar el impacto que tienen estas estrategias y recursos en los resultados que se obtienen en el cáncer infantil en América Latina y el Caribe y en otras subregiones.

A Iniciativa Global para o Câncer Infantil tem como objetivo aumentar a taxa de cura de crianças com câncer no mundo todo, melhorando o acesso a cuidados e a qualidade da assistência médica. A Organização Pan-Americana da Saúde (OPAS), o St. Jude Children's Research Hospital (St. Jude) e colaboradores uniram esforços para melhorar o desfecho de crianças com câncer na América Latina e no Caribe (ALC) no âmbito do marco CureAll. Neste artigo, descrevemos o processo de desenvolvimento de recursos regionais com o objetivo de acelerar a implementação da Iniciativa na ALC.Em março de 2021, a OPAS formou grupos de trabalho regionais para desenvolver projetos centrais alinhados com os pilares e facilitadores do CureAll. A partir das reuniões de diálogo regionais, foram criados sete grupos de trabalho: detecção precoce, enfermagem, atenção psicossocial, nutrição, cuidados de suporte, abandono do tratamento e cuidados paliativos. A OPAS organizou reuniões virtuais regulares sob a orientação e o apoio dos programas regionais e transversais do St. Jude e de mentores internacionais.Entre abril e dezembro de 2021, 202 especialistas multidisciplinares participaram de 43 reuniões virtuais para promover o diálogo entre as partes interessadas a fim de melhorar os desfechos do câncer infantil. Foram produzidos 14 materiais técnicos: quatro panoramas regionais, quatro documentos técnicos, dois cursos virtuais, um conjunto de perfis epidemiológicos nacionais, uma série de conteúdo educacional para pais e cuidadores e duas campanhas de comunicação.O diálogo e o compromisso contínuos da OPAS, do St. Jude, dos comitês de trabalho da ALC e dos colaboradores internacionais são bases essenciais para acelerar com sucesso a implementação da Iniciativa Global para o Câncer Infantil. Isso é possível por meio do desenvolvimento de materiais de relevância regional e mundial. São necessárias mais pesquisas e avaliações para determinar o impacto dessas estratégias e recursos nos resultados do câncer infantil na ALC e em outras regiões.

A New Variant B Chromosome in Auchenipteridae: The Role of (GATA)n and (TTAGGG)n Sequences in Understanding the Evolution of Supernumeraries in Trachelyopterus.

Basic and molecular cytogenetic techniques were carried out in 3 Neotropical region populations of catfishes, two of Trachelyopterus galeatus (one from the marshlands of Paraguay River basin and another from Lago Catalão, Amazon River basin) and one of Trachelyopterus porosus, a sympatric population to T. galeatus from the Amazon River basin. This study aimed to describe and understand the structure and evolution of Trachelyopterus B chromosomes, mainly through physical mapping of repetitive elements. A diploid number of 58 chromosomes was found for all individuals, as well as the presence of B chromosomes. For T. porosus this is the first report of a supernumerary. The sympatric species of T. galeatus and T. porosus from Amazon River had 1-3 B chromosomes and T. galeatus from Paraguay River had 1-2 B chromosomes, all of them showed intra- and interindividual numerical variation. Two females of T. porosus exhibited a new variant B chromosome (B2), previously not seen in Auchenipteridae, which might have originated from B1 chromosomes. All B chromosomes were entirely heterochromatic. In contrast to all complement A and B2 chromosomes, in which the telomeric sequences were found in the telomeric regions, B1 chromosomes of all populations were totally marked by (TTAGGG)n probes. (GATA)n sequence sites were found through all complement A chromosomes, but B1 and B2 chromosomes exhibited only a clustered block in one of the chromosome arms. The most frequent B chromosomes (B1) in all populations/species, including those previously studied in Auchenipteridae catfishes, share the following characteristics: totally heterochromatic, small, metacentric, with accumulation of repetitive (TTAGGG)n sequences, and a low number of (GATA)n copies, which might suggest a common ancient origin in Trachelyopterus species/populations.

DNA-MBF1 study using molecular dynamics simulations : On the road to understanding the heat stress response in DNA-protein interactions in plants.

Regulatory factor MBF1 is highly conserved between species and has been described as a cofactor and transcription factor. In plants, several reports associate MBF1 with heat stress response. Nevertheless, the specific physical processes involved in the MBF1-DNA interaction are still far from clearly understood. We thus performed extensive molecular dynamics simulations of DNA with a homology-based modethel of the MBF1 protein. Based on recent experimental data, we proposed two B-DNA sequences, analyzing their interaction with our model of the Arabidopsis MBF1c protein (AtMBF1c) at three different temperatures: 293, 300, and 320 K, maintaining a constant pressure of 1 bar. The simulations suggest that MBF1 binds directly to the DNA, supporting the idea of its role as a transcription factor. We identified two different conformations of the MBF1 protein when bound, and characterized the specific groups of amino acids involved in the formation of the DNA-MBF1 complex. These regions of amino acids are bound mostly to the minor groove of DNA by the attraction of positively charged residues and the negatively charged backbone, but subject to the compatibility of shapes, much in the sense of a lock-and-key mechanism. We found that only with a sequence rich in CTAGA motifs at 300 K does MBF1 bind to DNA in the DNA-binding domain Cro/C1-type HTH predicted. In the rest of the systems tested, we observed non-specific DNA-MBF1 interactions. This study complements findings previously reported by others on the role of CTAGA as a DNA-binding element for MBF1c at a heat stress temperature.

Anaerobic digestion of fourth range fruit and vegetable products: comparison of three different scenarios for its valorisation by life cycle assessment and life cycle costing.

Changes in consumer demand due to preferences for a healthier lifestyle have led to a new market offering fruit and salad products ready to eat. This affects the agro-industrial sector and the characteristic of waste streams generated having the organic fraction higher quality and representing a new opportunity of valorisation. This study experimentally evaluated the digestion of wastes derived from the fourth range product sector. It was also proposed the use of this digestate as a fermentation medium for producing plant growth-promoting cultures. Three digestion scenarios were studied: Scenario 1 considered biogas valorisation using a combined heat and power (CHP) unit. Scenario 2 featured biogas upgrading to be used as vehicle fuel. Finally, scenario 3 evaluated the transport of waste materials to the digestion plant by a network of pipes and pumps directly from the production chain. All three scenarios included the land application of a biostimulator based on the production of a plant growth-promoting culture derived from digestate. Life cycle analysis and life cycle costing were used to determine potential environmental impacts and costs over a lifetime of 25 years. The study showed that scenario 1 was the most favourable option for valorising this type of waste, although the economic assessment resulted in negative values for all three alternatives.

Chromosome Mapping of H1 and H4 Histones in Parodontidae (Actinopterygii: Characiformes): Dispersed and/or Co-Opted Transposable Elements?

The karyotypes of the family Parodontidae consist of 2n = 54 chromosomes. The main chromosomal evolutionary changes of its species are attributed to chromosome rearrangements in repetitive DNA regions in their genomes. Physical mapping of the H1 and H4 histones was performed in 7 Parodontidae species to analyze the chromosome rearrangements involved in karyotype diversification in the group. In parallel, the observation of a partial sequence of an endogenous retrovirus (ERV) retrotransposon in the H1 histone sequence was evaluated to verify molecular co-option of the transposable elements (TEs) and to assess paralogous sequence dispersion in the karyotypes. Six of the studied species had an interstitial histone gene cluster in the short arm of the autosomal pair 13. Besides this interstitial cluster, in Apareiodon davisi, a probable further site was detected in the terminal region of the long arm in the same chromosome pair. The H1/H4 clusters in Parodon cf. pongoensis were located in the smallest chromosomes (pair 20). In addition, scattered H1 signals were observed on the chromosomes in all species. The H1 sequence showed an ERV in the open reading frame (ORF), and the scattered H1 signals on the chromosomes were attributed to the ERV's location. The H4 sequence had no similarity to the TEs and displayed no dispersed signals. Furthermore, the degeneration of the inner ERV in the H1 sequence (which overlapped a stretch of the H1 ORF) was discussed regarding the likelihood of molecular co-option of this retroelement in histone gene function in Parodontidae.

Influence of anchoring in the phase behaviour of discotic liquid crystals.

Molecular dynamics simulations were performed for a Gay-Berne discotic fluid confined in a slab geometry for two different anchorings: homeotropic (face-on) and planar (edge-on), and for two different confinement lengths. Our results show that the behaviour of the more confined system in the temperature region of the isotropic-nematic transition is critically influenced by the presence of the walls: the growth of the solid-liquid crystal interface spans over the entire width of the cell, and the character of the transition is changed from first order to continuous. For all the confined systems studied, we observe a higher nematic-columnar transition temperature and a smaller nematic phase region in the phase diagram, as compared with the behaviour of the infinite system.

Delftia rhizosphaerae sp. nov. isolated from the rhizosphere of Cistus ladanifer.

A bacterial strain, designated RA6T, was isolated from the rhizosphere of Cistus ladanifer. Phylogenetic analyses based on 16S rRNA gene sequence placed the isolate into the genus Delftia within a cluster encompassing the type strains of Delftia lacustris, Delftia tsuruhatensis, Delftia acidovorans and Delftia litopenaei, which presented greater than 97 % sequence similarity with respect to strain RA6T. DNA-DNA hybridization studies showed average relatedness ranging from of 11 to 18 % between these species of the genus Delftia and strain RA6T. Catalase and oxidase were positive. Casein was hydrolysed but gelatin and starch were not. Ubiquinone 8 was the major respiratory quinone detected in strain RA6T together with low amounts of ubiquinones 7 and 9. The major fatty acids were those from summed feature 3 (C16 : 1ω7c/C16 : 1 ω6c) and C16 : 0. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain RA6T should be considered as a representative of a novel species of genus Delftia, for which the name Delftia rhizosphaerae sp. nov. is proposed. The type strain is RA6T (=LMG 29737T= CECT 9171T).

Comparative Cytogenetics of Hoplerythrinus unitaeniatus (Agassiz, 1829) (Characiformes, Erythrinidae) Species Complex from Different Brazilian Hydrographic Basins.

Chromosomal characteristics of Hoplerythrinus unitaeniatus populations from 5 Brazilian river basins, namely Arinos (Amazonas basin), Araguaia, Paraguai, Alto Paraná, and São Francisco were analyzed by conventional Giemsa staining, C-banding, silver nitrate impregnation, and fluorescence in situ hybridization (FISH) with 18S and 5S rDNA and telomeric sequence (TTAGGG)n probes. The diploid chromosome number was 2n = 48 in representatives of the populations from Paraguai and Alto Paraná River basins and 2n = 52 for those from the Arinos and Araguaia River basins. The São Francisco population had individuals with 2n = 50 and 52 occurring in sympatry. C-banding showed heterochromatic blocks mainly located at interstitial and pericentromeric positions in most of the chromosomes. Silver nitrate impregnation demonstrated simple NORs for representatives from Arinos and Araguaia River populations and multiple NORs for specimens from Paraguai, Alto Paraná, and São Francisco River populations. FISH with 18S and 5S rDNA probes revealed many chromosomes carrying these cistrons, with up to 21 chromosomes bearing 18S rDNA sites (Alto Rio Paraná basin) and up to 12 chromosomes with 5S rDNA sites (Paraguai basin), besides the occurrence of colocalization in all populations. FISH with telomeric sequence (TTAGGG)n detected sites in the terminal portion of the chromosomes in all populations. These data reinforce the idea that H. unitaeniatus is a species complex. Evolutionary and biogeographical aspects of the group in the Neotropical region are discussed.

Non-additive simple potentials for pre-programmed self-assembly.

A major goal in nanoscience and nanotechnology is the self-assembly of any desired complex structure with a system of particles interacting through simple potentials. To achieve this objective, intense experimental and theoretical efforts are currently concentrated in the development of the so-called "patchy" particles. Here we follow a completely different approach and introduce a very accessible model to produce a large variety of pre-programmed two-dimensional (2D) complex structures. Our model consists of a binary mixture of particles that interact through isotropic interactions that enable them to self-assemble into targeted lattices by the appropriate choice of a small number of geometrical parameters and interaction strengths. We study the system using Monte Carlo computer simulations and, despite its simplicity, we are able to self-assemble potentially useful structures such as chains, stripes, and Kagomé, twisted Kagomé, honeycomb, square, Archimedean and quasicrystalline tilings. Our model is designed in such a way that it may be implemented using discotic particles or, alternatively, using exclusively spherical particles interacting isotropically. Thus, it represents a promising strategy for bottom-up nano-fabrication.

Origin of the X1X1X2X2/X1X2Y sex chromosome system of Harttia punctata (Siluriformes, Loricariidae) inferred from chromosome painting and FISH with ribosomal DNA markers.

Harttia is a genus in the subfamily Loricariinae that accommodates fishes popularly known as armored catfishes. They show extensive karyotypic diversity regarding interspecific numerical/structural variation of the karyotypes, with the presence of the XX/XY1Y2 multiple sex chromosome system, as found in H. carvalhoi. In this context, this study aimed to characterize Harttia punctata chromosomally, for the first time, and to infer the rearrangements that originated the X1X1X2X2/X1X2Y multiple sex chromosome system present in this species. The data obtained in this study, with classical (Giemsa, C-banding and AgNORs) and molecular methodologies (fluorescence in situ hybridization) and chromosome microdissection, indicated that a translocation between distinct acrocentric chromosomes bearing rRNA genes, accompanied by deletions in both chromosomes, might have originated the neo-Y chromosome in this species. The data also suggest that the multiple sex chromosome systems present in H. carvalhoi and H. punctata had an independent origin, evidencing the recurrence of chromosome alterations in species from this genus.