The riverscape of Western Amazonia – a quantitative approach to the fluvial biogeography of the region

Aim To provide a quantitative spatial analysis of the riverscape (open‐water bodies and their surrounding areas) of the Western Amazonian lowlands using a consistent surface of remotely sensed imagery. Taking into account the essential significance of fluvial environments for the Amazonian biota, we propose that an enhanced understanding of the Amazonian riverscape will provide new insight for biogeographical studies in the region and contribute to the understanding of these megadiverse tropical lowlands. Location An area of 2.2 million km² covering the Western Amazonian lowlands of the Andean foreland region, i.e. the upper reaches of the Amazon river system. Areas in Colombia, Venezuela, Ecuador, Peru, Brazil and Bolivia between longitudes 83 °W and 65 °W and latitudes 5 °N and 12 °S are included. Methods A mosaic of 120 Landsat TM satellite images was created with 100‐m resolution, and water areas of over 1 ha in size or c. 60 m in width were extracted using a simple ratio threshold applicable to a large set of data. With this method, 99.1% of the water areas present in 30‐m imagery were mapped with images with 100‐m resolution. Water pixels of distinct river segments were assigned to river classes on the basis of their channel properties, and islands and lakes were distinguished separately and classified. Measures of water patterns such as structure, composition, richness and remoteness were provided for various spatial units. Riverine corridors were computed from the open‐water mask by outer limits of active channels and floodplain lakes. Analytical results are shown as both thematic maps and statistics. Results A total of 1.1% of Western Amazonia is covered by open‐water bodies over 1 ha in size or 60 m in width. River‐bound waters comprise 98% of the total water surface. Whilst isolated lakes are scarce, river‐bound oxbow and backchannel lakes are plentiful, comprising 17.5% of all waters. They are particularly frequent along meandering channels, which dominate both in area and length. The riverine corridors including active channels and floodplain lakes cover 17% of the land area. The average distance from any point of land to the nearest water is 12 km. Geographically speaking, the distribution of waters is uneven across the region, and the detailed characteristics of the riverscape are geographically highly variable. Three major, fluvially distinct regions can be identified: central Western Amazonia, the south, and the north‐east. The proportional surface areas of the riverine corridors, numbers of lakes, sizes of islands and their distributions depend largely on the types and sizes of the rivers. Main conclusions Our results support the notion of Western Amazonia as a dynamic, highly fluvial environment, highlighting and quantifying considerable internal variation within the region in terms of fluvial patterns and the processes that they reflect and control. Biogeographically, the variety of types of fluvial environments and their characteristics are important constituents of what influences the distribution of species and dynamics of terrestrial habitats. Spatially consistent riverscape data can serve as a consistent and scalable source of relevant information for other biogeographical approaches in the region.     

Early-onset renal cell carcinoma as a novel extraparaganglial component of SDHB-associated heritable paraganglioma

Hereditary paraganglioma syndrome has recently been shown to be caused by germline heterozygous mutations in three (SDHB, SDHC, and SDHD) of the four genes that encode mitochondrial succinate dehydrogenase. Extraparaganglial component neoplasias have never been previously documented. In a population-based registry of symptomatic presentations of phaeochromocytoma/paraganglioma comprising 352 registrants, among whom 16 unrelated registrants were SDHB mutation positive, one family with germline SDHB mutation c.847-50delTCTC had two members with renal cell carcinoma (RCC), of solid histology, at ages 24 and 26 years. Both also had paraganglioma. A registry of early-onset RCCs revealed a family comprising a son with clear-cell RCC and his mother with a cardiac tumor, both with the germline SDHB R27X mutation. The cardiac tumor proved to be a paraganglioma. All RCCs showed loss of the remaining wild-type allele. Our observations suggest that germline SDHB mutations can predispose to early-onset kidney cancers in addition to paragangliomas and carry implications for medical surveillance.     

A cascade of 24 histatins (histatin 3 fragments) in human saliva. Suggestions for a pre-secretory sequential cleavage pathway

The systematic search by tandem mass spectrometry of human saliva from four different subjects, of 136 possible fragments originated from histatin 3, allowed the detection of 24 different peptides. They include, with the exception of histatin 4, all the known histatin 3 fragments, namely histatins 5-12 and the peptides corresponding to 15-24, 26-32, 29-32 residues, and 13 new fragments corresponding to 1-11, 1-12, 1-13, 5-13, 6-11, 6-13, 7-11, 7-12, 7-13, 14-24, 14-25, 15-25, and 28-32 residues of histatin 3. On the contrary, none of 119 possible fragments of histatin 1, including histatin 2, was detected. The results suggest that the genesis of histatin 3-related peptides, being under the principal action of trypsin-like activities, is probably not a random process but rather follows a sequential fragmentation pathway. Lack of detection of C-terminal fragments, with the exception of 26-32, 28-32, and 29-32 fragments, suggested that arginine 25 should be the first cleavage site, generating histatin 6 and 26-32 fragments. The genesis of 28-32 and 29-32 fragments and histatin 5 should implicate a subsequent exo-protease action. Similarly, lack of detection of fragments having Lys-5 and Arg-6 at the N terminus and Arg-25 at the C terminus strongly suggested that sequences KRKF (11-14 residues) and AKR (4-6 residues) should be the second and the third cleavage sites, respectively. Lys-17 and Arg-22 are not cleaved at all.     

Enhancing the thermal stability of avidin. Introduction of disulfide bridges between subunit interfaces

In this study we showed that tetrameric chicken avidin can be stabilized by introducing intermonomeric disulfide bridges between its subunits. These covalent bonds had no major effects on the biotin binding properties of the respective mutants. Moreover, one of the mutants (Avd-ccci) maintained its tetrameric integrity even in denaturing conditions. The new avidin forms Avd-ci and Avd-ccci, which have native --> denatured transition midpoints (T(m)) of 98.6 and 94.7 degrees C, respectively, in the absence of biotin, will find use in applications where extreme stability or minimal leakage of subunits is required. Furthermore, we showed that the intramonomeric disulfide bridges found in the wild-type avidin affect its stability. The mutant Avd-nc, in which this bridge was removed, had a lower T(m) in the absence of biotin than the wild-type avidin but showed comparable stability in the presence of biotin.     

Association of Maedi Visna virus with Brucella ovis infection in rams

Maedi Visna Virus (MVV) is the etiological agent of a systemic disease of sheep, which causes lesions in lungs, the central nervous system, joints, and mammary glands. It has been speculated that the association with Brucella ovis may lead to the venereal shedding of the virus. In this work, samples of epididymis from ten rams positive for MVV and infected experimentally with Brucella ovis, were subjected to liquid-phase PCR, immunohistochemistry (IHC) and in situ PCR tests, aimed at identifying the pathogens in a tissue context. IHC was carried out using a monoclonal antibody raised against p28 MVV protein and a polyclonal antibody to B. ovis. Liquid phase- and in situ PCR were designed to amplify a portion of MVV proviral DNA Pol sequence. In the animals showing B. ovis-related histopathological changes, IHC clearly demonstrated a positivity for B. ovis and MVV in interstitial and epithelial ductal cells. In situ PCR assessed the presence of MVV proviral DNA in macrophages and elements inside the epithelium. The unaffected and reagent control samples constantly gave negative results. Taken together, these data demonstrate that MVV may affect ovine epididymis, apparently taking advantage of the concurrent infection by B. ovis. The tropism of MVV for the epididymal epithelial cells, may be responsible for its excretion with the semen.     

Activation of human and mouse Kupffer cells by lipopolysaccharide is mediated by CD14

Upregulation of CD14 in Kupffer cells has been implicated in the pathogenesis of several forms of liver injury, including alcoholic liver disease. However, it remains unclear whether CD14 mediates lipopolysaccharide (LPS) signaling in this specialized liver macrophage population. In this series of experiments, we determined the role of CD14 in LPS activation of Kupffer cells by using several complementary approaches. First, we isolated Kupffer cells from human livers and studied the effects of anti-CD14 antibodies on LPS activation of these cells. Kupffer cells were incubated with increasing concentrations of LPS in the presence and absence of recombinant human LPS binding protein (LBP). With increasing concentrations of LPS, human Kupffer cell tumor necrosis factor-alpha (TNF-alpha) production (a marker for Kupffer cell activation) increased in a dose-dependent manner in the presence and absence of LBP. In the presence of anti-human CD14 antibodies, the production of TNF-alpha was significantly diminished. Second, we compared LPS activation of Kupffer cells isolated from wild-type and CD14 knockout mice. Kupffer cells from CD14 knockout mice produced significantly less TNF-alpha in response to the same amount of LPS. Together, these data strongly support a critical role for CD14 in Kupffer cell responses to LPS.     

In vitro adhesion specificity of indigenous Lactobacilli within the avian intestinal tract

In vitro adherence of Lactobacillus strains to cell and tissue types along the chicken alimentary tract and to ileal mucus were determined. Fresh isolates from chickens adhered to the epithelium of crop and, in a strain-dependent manner, to follicle-associated epithelium and the apical surfaces of mature enterocytes of intestinal villi. No adherence to the apical surfaces of undifferentiated enterocytes, the mucus-producing goblet cells, or the ileal mucus was detected.     

Palmar pattern frequencies as indicators of relationships among Sardinian linguistic groups of males

Palmar pattern frequencies were used to calculate distance coefficients between Sardinian linguistic groups of males for the purpose of verifying, by means of correlation matrix analyses, whether or not the dermatoglyphic traits considered lead to a reliable identification of the biological relationships on the basis of the linguistic backgrounds of these groups. With Sanghvi's as the distance measure and by using palmar pattern frequencies in the Hy area, Th/I, II, III, and IV interdigital areas and all traits together for palms combined or separated were calculated dermatoglyphic distance measures. Mantel tests of matrix correspondence showed that, by using palmar pattern frequencies in the Th/I interdigital area (palms combined), in the II, III, and IV interdigital areas, or all traits together for palms combined and separated, statistical significance between dermatoglyphic and linguistic distances can be obtained, even when the effect of geography is removed; there is no statistically significant correspondence between geographic and dermatoglyphic distance matrices, even when the effect of language is removed. The results obtained in this study by means of the Mantel test procedure demonstrate that the dermatoglyphic traits analyzed, with the exception of palmar pattern frequencies in the Hy area and in the Th/I interdigital area for plams separated when these areas are used singly, can be considered as a good set of variables to use in finding biological relationships between Sardinian linguistic groups of males examined on the basis of their linguistic backgrounds.