Great Diversity Of Environments Research Articles

Shepherding the past: High-resolution data on Neolithic Southern Iberian livestock management at Cueva de El Toro (Antequera, Málaga).

The feeding strategies of the first domesticated herds had to manage the risks arising from the novelty of livestock practices in territories often distant from the animals' primary habitats. The Iberian Peninsula is characterised by a great diversity of environments, which undoubtedly influenced these dynamics. At the beginning of the Neolithic period these led the possibility to combine diverse livestock farming practices based on different animal feeding habits. This variability is also consistent with the rythms of adoption of domesticated animals, being later on the northern area. In order to address this issue, this work focuses on the dietary regimes of early sheep herds from southern Iberia, an area for which information is currently scarce. This study utilises high-resolution radiocarbon dating and stable isotope data on teeth to investigate sheep husbandry management strategies in Cueva de El Toro (Antequera, Málaga). The radiocarbon dates on the analysed remains evidenced they were deposited at the site over a short period, supporting the recurrent use of the cave. The sequential analysis of oxygen and carbon isotopes in tooth enamel reveals distinct livestock management strategies, reproduction patterns, feeding habits, and mobility during this short period. This variability demonstrates that livestock management practices in the western Mediterranean are more diverse than previously considered. Furthermore, these findings support the hypothesis that early Neolithic communities in the southern Iberian Peninsula were able to adopt different feeding strategies within the same herd, depending on their ecological and productive needs.

Patterns of Ant Diversity in the Natural Grasslands of Southern Brazil.

In the south of Brazil, grasslands are naturally widespread over two different biomes, the Pampa in the southernmost region and within the Atlantic Forest in the northern portions. The natural grasslands of the state of Paraná comprise a very particular physiognomy composed of two distinct formations: the Campos Gerais and the grasslands of the southwest. The first is located in the edge of the second plateau of Paraná state, comprising a great diversity of environments. The grasslands of the southwest are more homogeneous, with a continuous herbaceous stratum dominating the landscape. In this context, the aim of this study was to evaluate the patterns of species richness and composition of ants, an ecologically prominent group, along the natural grasslands of Paraná. We also intended to compare the faunal similarity between the two different grassland formations. For that, four different Conservation Unities were sampled along a latitudinal gradient. A remarkable total of 245 ant species was recorded, and the results indicate that species richness decreases as latitude increases along the grasslands of Paraná. There were clear differences in species composition between these two grasslands formations, given the significative number of endemic species in each of these two grassland formations. Ten species were recorded for the first time in the state of Paraná, of which three also for the first time in the Southern Region of Brazil. Overall, our study contributes to a better understanding about the diversity and composition of ant communities in subtropical grasslands.

Evolution in the Genus Rhinella: A Total Evidence Phylogenetic Analysis of Neotropical True Toads (Anura: Bufonidae)

True toads of the genus Rhinella are among the most common and diverse group of Neotropical anurans. These toads are widely distributed throughout South America, inhabiting a great diversity of environments and ecoregions. Currently, however, the genus is defined solely on the basis of molecular characters, and it lacks a proper diagnosis. Although some phenetic species groups have traditionally been recognized within Rhinella, the monophyly of some of them have been rejected in previous phylogenetic analyses, and many species remain unassigned to these poorly defined groups. Additionally, the identity and taxonomy of several species are problematic and hinder the specific recognition and description of undescribed taxa. In this work, we first perform phylogenetic analyses of separate mitochondrial and nuclear datasets to test the possible occurrence of hybridization and/or genetic introgression in the genus. The comparative analysis of both datasets revealed unidirectional mitochondrial introgressions of an unknown parental species into R. horribilis (“ghost introgression”) and of R. dorbignyi into R. bernardoi; therefore, the mitochondrial and nuclear datasets of these species were considered separately in subsequent analyses. We performed total-evidence phylogenetic analyses that included revised molecular (four mitochondrial and five nuclear genes) and phenotypic (90 characters) datasets for 83 nominal species of Rhinella, plus several undescribed and problematic species and multiple outgroups. Results demonstrate that Rhinella was nonmonophyletic due to the position of R. ceratophrys, which was recovered as the sister taxon of Rhaebo nasicus with strong support. Among our outgroups, the strongly supported Anaxyrus + Incilius is the sister clade of all other species of Rhinella. Once R. ceratophrys is excluded, the genus Rhinella is monophyletic, well supported, and composed of two major clades. One of these is moderately supported and includes species of the former R. spinulosa Group (including R. gallardoi); the monophyletic R. granulosa, R. crucifer, and R. marina Groups; and a clade composed of the mitochondrial sequences of R. horribilis. The other major clade is strongly supported and composed of all the species from the non-monophyletic R. veraguensis and R. margaritifera Groups, the former R. acrolopha Group, and R. sternosignata. Consistent with these results, we define eight species groups of Rhinella that are mostly diagnosed by phenotypic synapomorphies in addition to a combination of morphological character states. Rhinella sternosignata is the only species that remains unassigned to any group. We also synonymize nine species, treat three former subspecies as full species, and suggest that 15 lineages represent putative undescribed species. Lastly, we discuss the apparently frequent occurrence of hybridization, deep mitochondrial divergence, and “ghost introgression”; the incomplete phenotypic evidence (including putative character systems that could be used for future phylogenetic analyses); and the validity of the known fossil record of Rhinella as a source of calibration points for divergence dating analyses.

A new simple approach to assess sediment yield at a large scale with high landscape diversity: an example of Morocco

Sedimentation of dams and soil erosion remain a worldwide issue, this is especially true in countries characterized by great environmental diversity where their assessment remains a serious difficult issue. Morocco ranks among countries with the greatest achievements in the dams field in Africa, characterized by a great climate, vegetation cover and morphological diversity. The objective of this study was to identify the spatial distribution of Sediment Yield (SY) and Area-Specific Sediment Yield (SSY) on the country scale and to present a new simple approach by exploiting the statistical tool to assess their controlling factors. We collected and analyzed environmental data of 42 catchments of the biggest and most important dams of the country of Morocco. The adopted statistical methodology reveals that Moroccan catchments can be subdivided into 5 categories (depending on climate, morphology and vegetation cover conditions) in which SY is most related to the catchment area and drainage network length, while SSY is mostly related to the soil organic carbon stock, rainfall and clay fraction. Our approach provides important new insights regarding modelling catchment scale sediments dynamic to asses SY and SSY in different regions around the world, especially in large scale and where there is a great environmental diversity.

The species diversity, distribution, and conservation status of the terrestrial mammals of Iran

Located at the crossroad of the Palearctic, Saharo-Arabian, and Oriental zoogeographic realms, and with its great environmental diversity, Iran harbors a high complexity and richness of fauna and flora. Knowledge about the Iranian mammal fauna has greatly increased over recent years thanks to the growing availability of molecular tools, which brought marked changes in taxonomy, but also because of intensive field surveys resulting in growing distributional data. These data are, however, scattered throughout numerous publications and unpublished sources, most of which are difficult to access. Here, we present a comprehensive review of the current mammal species taxonomies with an update on systematics and their spatial distribution based on all possible sources spanning the period between 1758 and today. We updated the geographical distribution of all Iranian land mammals, providing their regional extent of occurrence and area of occupancy, as well as mapped species richness. Based on this information, we then assessed the conservation status of Iran's mammals using the International Union for Conservation of Nature Red List criteria, providing a regional status assessment. The current species list of terrestrial mammals of Iran comprises 192 species from 34 families, of which eight species are endemics. Since the publication of Karami et al. (2008), 13 new species or new records have been added to the mammals of Iran and 32 changes in classification or nomenclature have been made. The Alborz and Zagros mountains accumulate the highest species richness. Nearly 13% of the species in Iran are threatened, and a further 14% are near to qualifying for threatened status. With the current review, we provide an up-to-date summary of the current knowledge about the terrestrial mammals of Iran that can serve as a guideline for mammalogists, a reference for monitoring regional biodiversity status and trends, and a framework for planning management actions to sustain biodiversity conservation.

Mass Spectrometry of Non-allomerized Chlorophylls a and b Derivatives from Plants

Background: Non-allomerized chlorophylls a and b are part of a great diversity of environments: senescent and ripened vegetal tissues, processed foods, sediments, fecal pellets, etc. Consequently, the articles characterizing their mass spectrometry behavior belong to a variety of disciplines. Objective: To compile in a single review all the information published related to mass spectrometry of 26 chlorophyll derivatives, including chlorophyllides, pheophorbides, pheophytins, and hydroxy-, lactone-, and pyro-chlorophyll derivatives. Method: A detailed and extensive bibliographic search through the Web of ScienceTM followed by a comprehensive and critic discussion. Results: This review gathers all the information concerning mass spectroscopic characteristics published for each non-allomerized chlorophyll of a and b series. This means that for each one of the 26 chlorophyll derivatives, it has been compiled the complete information published of mass (or exact mass), mass spectrometry technique and equipment (ionization method and mass analyzer), product ions, structural assignments and proposed mechanisms (if available), detailing the references. Conclusion: The evaluation of referenced data in literature has allowed to obtain common characteristics in the mass spectrometry behavior between the different chlorophyll derivatives. In addition, specific product ions have been reported, revealing specific structural modifications in the chlorophyll molecule, facilitating the structural characterization. This review embraces the application of predictive software tools, which improve accuracy of predictions and make straightforward the structural assignments. Keywords: Chlorophyllide, hydroxy-chlorophyll, lactone-chlorophyll, mass spectrometry, pheophorbide, pheophytin, pyrochlorophyll.

The First Male of the Spider GenusTemnidaSimon, 1896 (Araneae: Anyphaenidae: Anyphaeninae)

Summary Anyphaenidae has 56 genera and 546 species and includes small to medium-sized spiders, inhabiting a great diversity of environments. The subfamily Anyphaeninae comprises 32 genera and 374 species and its greatest diversity occurs in the New World. Among the Anyphaeninae, the Aysha group can be distinguished by the presence of an embolic process, which is the putative synapomorphy the group. In this paper we described the male of Temnida rosario the first time.

Plant diversity in different bioclimatic zones in Tunisia

The Republic of Tunisia, located in northern Africa, faces various environmental challenges caused by anthropogenic practices such as overgrazing, deforestation, and desertification. The conversion of natural ecosystems is the major cause of plant biodiversity loss. Tunisia can be divided into three main climatic zones as follows: a northern Mediterranean climate zone, a central steppe climate zone, and a southern desert climate zone. Because of this great environmental diversity, there are distinctive vegetation and various genetic resources in Tunisia. This research was conducted to investigate plant biodiversity within the various bioclimatic zones and to characterize useful plant resources in Tunisia. We investigated native, medicinal and aromatic, desert, and soil erosion control plant species.

A predictive model based on a pluviothermic index for leathery pocket and fruitlet core rot of pineapple cv. ‘Queen’

Leathery pocket (LP) and fruitlet core rot (FCR) of pineapple (Ananas comosus L.) caused by Penicillium funiculosum Thom. and/or Fusarium moniliforme Sheld cause significant damage in all production areas, resulting in a major economic impact that affects both the fresh fruit market and the processing sector. The detection of Penicillium and Fusarium in the two main areas of pineapple production in Reunion Island, and representing a large range of climatic conditions, indicated that these fungi responsible for FCR and LP diseases were present throughout the pineapple cycle, whatever the climatic conditions. The proportion of fruits naturally infected by these pathogens was not related to climatic conditions during the infection period, suggesting that the inoculum level was not limiting. As these diseases cannot be reliably controlled, due in particular to the role of climatic conditions, an important research goal is to predict periods of higher disease risk using a model based on weather data. Taking advantage of the great diversity of environments on the tropical island of Reunion (Indian Ocean), we were able to establish a link between a pluviothermic index (PTi: ratio between total rainfall and the average temperature over the fruit development stages), and LP or FCR incidence. Disease incidence was modelled as a function of the pluviothermic index via a Weibull model. The most accurate model was obtained during the open heart to harvest stage. Lastly, the model output can be used by pineapple production stakeholders in farm management strategies and to adapt fruit grading before marketing.

A rapid live-cell ELISA for characterizing antibodies against cell surface antigens of Chlamydomonas reinhardtii and its use in isolating algae from natural environments with related cell wall components.

BackgroundCell walls are essential for most bacteria, archaea, fungi, algae and land plants to provide shape, structural integrity and protection from numerous biotic and abiotic environmental factors. In the case of eukaryotic algae, relatively little is known of the composition, structure or mechanisms of assembly of cell walls in individual species or between species and how these differences enable algae to inhabit a great diversity of environments. In this paper we describe the use of camelid antibody fragments (VHHs) and a streamlined ELISA assay as powerful new tools for obtaining mono-specific reagents for detecting individual algal cell wall components and for isolating algae that share a particular cell surface component.ResultsTo develop new microalgal bioprospecting tools to aid in the search of environmental samples for algae that share similar cell wall and cell surface components, we have produced single-chain camelid antibodies raised against cell surface components of the single-cell alga, Chlamydomonas reinhardtii. We have cloned the variable-region domains (VHHs) from the camelid heavy-chain-only antibodies and overproduced tagged versions of these monoclonal-like antibodies in E. coli. Using these VHHs, we have developed an accurate, facile, low cost ELISA that uses live cells as a source of antigens in their native conformation and that requires less than 90 minutes to perform. This ELISA technique was demonstrated to be as accurate as standard ELISAs that employ proteins from cell lysates and that generally require >24 hours to complete. Among the cloned VHHs, VHH B11, exhibited the highest affinity (EC50 < 1 nM) for the C. reinhardtii cell surface. The live-cell ELISA procedure was employed to detect algae sharing cell surface components with C. reinhardtii in water samples from natural environments. In addition, mCherry-tagged VHH B11 was used along with fluorescence activated cell sorting (FACS) to select individual axenic isolates of presumed wild relatives of C. reinhardtii and other Chlorphyceae from the same environmental samples.ConclusionsCamelid antibody VHH domains provide a highly specific tool for detection of individual cell wall components of algae and for allowing the selection of algae that share a particular cell surface molecule from diverse ecosystems.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0244-0) contains supplementary material, which is available to authorized users.

Environmental factors that affect sheep production in Brazil

Sheep were originally brought to Brazil approximately 500 years ago from Europe and Northern Africa; they adapted quickly to their new environments and developed unique traits. The objective of this study was to correlate environmental variables with sheep production in Brazil to promote the development of this activity. Brazil has several distinct environments as shown in this paper. These variables included vegetation cover (NDVI), precipitation, temperature, altitude, relative humidity (RH), solar radiation and the temperature humidity index (THI). Correlation analyses were performed with environmental variables and production levels at national and regional level. A factor analysis was performed to characterize the covariance between variables. We formed groups (clusters) due to productivity levels and performed canonical discriminant analyses to determine which variables were associated with different levels of production. The municipalities with the highest levels of sheep production were selected to define the intervals of each environmental variable. A map was drafted in ArcGis 9.3 to illustrate the landscape features where the highest levels of production are located. The results showed that, nationally, production is influenced by a great diversity of environments, thus masking possible correlations. When the correlation analysis was carried out by region, significant correlations were observed. Cluster analysis identified two dominant, clearly separated producing regions (northeast and south). The canonical analysis indicated that the most important variables delineating the clusters were precipitation, THI, temperature and RH. The map showing the landscape features where the highest production levels are located indicated that the breeds in the northeast are reared on an area of approximately 900,000 km2, while those from the south are reared on an area of approximately 1,100 million km2. This study showed that it is important to consider the environmental characteristics of different regions of Brazil when proposing public policies related to sheep production.

Informal Irrigation in the Colombian Andes: Local Practices, National Agendas, and Options for Innovation

Knowledge about the extent of irrigated land in Colombia is scarce because most irrigation is done informally and therefore not registered. Informal irrigation in Colombia has not been investigated, its national presence has not been identified, and its characteristics are still unknown. The present article aims to help fill this gap. Because of topographical and agricultural patterns, Andean informal irrigation is impossible to identify or characterize using standard methods. To provide information on the scale of informal irrigation systems in Colombia, their type, the users they serve, and the type of water sources they use, a large-scale partial inventory was made combining statistical analysis, questionnaires, interviews, and field trips. The findings indicate that informal irrigation is widespread in the country's mountainous zones, in a great diversity of environments, characterized by an equally great diversity of local uses and water-use strategies. This diversity has resulted from the coexistence of very different community and state institutions, posing challenges for planning and organizing water-resource management more efficiently and sustainably for producers, the government, and other stakeholders.

Modificações nas propriedades dos solos de uma área de manejo florestal na Chapada do Araripe

A Chapada do Araripe possui grande diversidade ambiental, onde é predominante o Latossolo Vermelho-Amarelo. Nela encontra-se a Floresta Nacional do Araripe (FLONA) e várias unidades de manejo florestal (UMF). O objetivo deste estudo foi utilizar a análise multivariada para obter-se um indicador básico que represente um conjunto de atributos físicos, químicos e biológicos utilizados como indicadores de modificações nas propriedades dos solos de uma UMF. Foram analisados, em triplicata, na profundidade de 0-20 cm, solos de 15 pontos da UMF e quatro da FLONA, onde foram determinados nove atributos utilizados na identificação das peculiaridades de grupos de estado de recuperação dos solos e suas principais diferenças. A análise demonstrou que dois componentes principais respondem por aproximadamente 76 % da variância dos dados: o primeiro é o indicador da qualidade biológica, química e física dos solos; e o segundo, do estado de compactação. A análise de agrupamento multivariada, aplicada ao primeiro componente principal, evidenciou a formação de três grupos: um da FLONA e dois contendo amostras da UMF, em diferentes estados de recuperação. A utilização do teste de Tukey em nível de 5 % no agrupamento dos teores de matéria orgânica dos solos apresentou os mesmos grupos da análise de agrupamento multivariada, indicando que esse atributo pode ser utilizado como indicador básico na área de estudo.

Essential genes from Arctic bacteria used to construct stable, temperature-sensitive bacterial vaccines

All bacteria share a set of evolutionarily conserved essential genes that encode products that are required for viability. The great diversity of environments that bacteria inhabit, including environments at extreme temperatures, place adaptive pressure on essential genes. We sought to use this evolutionary diversity of essential genes to engineer bacterial pathogens to be stably temperature-sensitive, and thus useful as live vaccines. We isolated essential genes from bacteria found in the Arctic and substituted them for their counterparts into pathogens of mammals. We found that substitution of nine different essential genes from psychrophilic (cold-loving) bacteria into mammalian pathogenic bacteria resulted in strains that died below their normal-temperature growth limits. Substitution of three different psychrophilic gene orthologs of ligA, which encode NAD-dependent DNA ligase, resulted in bacterial strains that died at 33, 35, and 37 degrees C. One ligA gene was shown to render Francisella tularensis, Salmonella enterica, and Mycobacterium smegmatis temperature-sensitive, demonstrating that this gene functions in both Gram-negative and Gram-positive lineage bacteria. Three temperature-sensitive F. tularensis strains were shown to induce protective immunity after vaccination at a cool body site. About half of the genes that could be tested were unable to mutate to temperature-resistant forms at detectable levels. These results show that psychrophilic essential genes can be used to create a unique class of bacterial temperature-sensitive vaccines for important human pathogens, such as S. enterica and Mycobacterium tuberculosis.

Análise da adaptabilidade e da estabilidade de genótipos de trigo como ferramenta auxiliar na recomendação de novas cultivares

A análise da adaptabilidade e da estabilidade de genótipos de trigo auxilia o melhorista na recomendação de novas cultivares, indicando linhagens de adaptação ampla ou específica aos ambientes. Esse procedimento é particularmente importante para a cultura do trigo, principalmente levando em consideração a grande diversidade de ambientes a que o cereal é submetido no Brasil. Assim, este trabalho teve como objetivo identificar genótipos de trigo com ampla adaptação e estáveis para recomendação. Os dados para as análises foram obtidos a partir do ensaio de Valor de Cultivo e Uso (VCU) estabelecido nas diferentes regiões de adaptação do Brasil, em 2003 e 2004. O delineamento experimental usado foi o de blocos ao acaso, com 4 repetições. A variável analisada foi o rendimento de grãos. Para fins de comparação, foram usadas três cultivares como testemunhas: "CEP 24", "BRS 194" e "Ônix". Para a determinação da adaptabilidade e da estabilidade dos genótipos, foram usados os métodos descritos por Eberhart &amp; Russel e por Lin &amp; Binns. Quatro genótipos apresentaram ampla adaptabilidade e estabilidade (beta=1 e S²d=0) pelo método de Eberhart &amp; Russel destes, dois não diferiram estatisticamente da melhor testemunha. Os coeficientes de determinação foram significativos e explicaram o comportamento de todos os genótipos avaliados (R²&gt;80% e significativo). O modelo de Lin &amp; Binns gerou resultados coerentes com o de Eberhart &amp; Russel, para a maioria das linhagens avaliadas. Os genótipos PF 990313 e PF 980524 destacaram-se pela ampla adaptação e produtividade média, podendo ser recomendados para todas as regiões tritícolas do Brasil.

Florística e fitossociologia do componente arbóreo de uma floresta ribeirinha, arroio Passo das Tropas, Santa Maria, RS, Brasil

Florestas ribeirinhas são caracterizadas por alta heterogeneidade ambiental, onde diferentes fatores físicos e bióticos regulam o mosaico vegetacional. Embora sejam áreas prioritárias à conservação, devido a sua fragilidade e importância, poucos estudos vêm sendo desenvolvidos nestes ambientes, em especial no Rio Grande do Sul. O objetivo do presente estudo é caracterizar a composição florística e a estrutura fitossociológica de um trecho de floresta ribeirinha em Santa Maria, RS. Para o levantamento, foram demarcadas 100 parcelas de 10x10m cada, dispostas paralelamente ao curso do rio, onde todos os indivíduos arbóreos PAP &gt; 15cm foram amostrados. Foram amostrados 2.195 indivíduos vivos e mais 137 mortos ainda em pé. Os indivíduos vivos pertencem a 57 espécies de 47 gêneros distribuídos em 26 famílias. As espécies com maiores valores de importância foram Gymnanthes concolor Spreng, Sebastiania commersoniana (Baill.) Smith &amp; Downs, Eugenia uniflora L., Plinia rivularis (Camb.) Rotman e Sebastiania brasiliensis Spreng. O índice de diversidade (H') foi de 2,73 nats/indivíduos e a equabilidade (J') 0,69 nats/indivíduos, valores considerados intermediários em comparação a outros levantamentos. A maioria das espécies amostradas (57%) provém do oeste do Estado, características das bacias do Paraná-Uruguai, enquanto que 41% são de ampla distribuição e apenas uma espécie provém do corredor atlântico.

Composição da assembléia de peixes da Baía da Ribeira, Angra dos Reis, Rio de Janeiro, Brasil

The ichthyofauna composition of the Baia da Ribeira was analyzed between December 1998 and November2001. The instruments used were an otter-trawl net, beach seines, cast net and visual census. It was registered two classes, composed by 16 orders, 59 families and 148 species. The high wealth of the region is due to the great diversity of environments and its location at the north limit of Argentine an Zoogeographic Province. The instruments diversification, the samples regions and the long sampling period were the responsables to the great numbers of collected species in comparison to some others studies at the same area.

Eficiência de glyphosate no controle de Commelina benghalensis e Commelina diffusa

A planta daninha trapoeraba (Commelina spp.) possui grande capacidade de sobreviver em ambientes diversificados, o que dificulta o seu controle. Em cafezais da Zona da Mata de Minas Gerais, onde o herbicida glyphosate é aplicado repetidamente, as espécies Commelina benghalensis e C. diffusa têm apresentado tolerância a este herbicida. Para confirmar esse fato e verificar o efeito de doses crescentes de glyphosate (720, 1.440, 2.160, 2.880 e 3.600 g i.a. ha-1) no controle dessas duas espécies de plantas daninhas, instalou-se um experimento no delineamento experimental de blocos casualizados, com seis repetições. As doses do herbicida foram aplicadas no período de florescimento de plantas de trapoeraba cultivadas em caixas de polietileno com dimensões de 10 cm de altura, 27,5 cm de largura e 39,5 cm de comprimento, em ambiente desprotegido. A eficácia dos tratamentos foi avaliada por meio da porcentagem de controle em relação à testemunha e da biomassa seca da parte aérea que sobreviveu aos tratamentos. C. benghalensis foi eficientemente controlada pelo glyphosate, mas C. diffusa apresentou tolerância. Para C. benghalensis o controle foi acima de 94% a partir da menor dose, 25 dias após tratamento (DAT) e de 100% em todas as doses aos 63 DAT. Para C. diffusa, em geral, quanto maior a dose de glyphosate, menor a biomassa seca da parte aérea. Entretanto, mesmo nas três maiores doses, nas quais se observou, aos 46 DAT, até 98,3% de controle, constatou-se regeneração de plantas aos 88 DAT. Nas condições do experimento, o glyphosate proporcionou excelente controle de C. benghalensis a partir de 720 g i.a. ha-1, 25 DAT. Contudo, excelente controle de C. diffusa por mais de 60 dias só foi obtido a partir de 2.880 g i.a. ha-1 de glyphosate.

Immobilization and Mineralization of Metallic Ions by Bacteria

Abstract Although all forms of life are of critical importance biogeochemicalfy, bacteria are especially significant. This uniqueness arises not only from the great diversity of environments populated by bacteria, but also because they perform many biogeochemical transformations that are carried out poorly or not at all by higher organisms. In addition, bacteria exhibit a profound ability to bind substantial quantities of metallic ions. This retention of metals is facilitated by electrostatic interactions with anionic carboxyl or phosphoryl groups in the structural polymers of the cells. The macromolecular constituents in cell walls and external sheaths of bacteria are particularly reactive, so metals tend to concentrate at the cell surface. These cellular structures also tenaciously bind metallic ions during diagenesis and serve as distinct nucleation sites for the formation of authigenic minerals. Evidence of micro-fossils in ancient sedimentary rocks suggests further that bacteria contributed to analog...