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.     

Microsatellite cross-species amplification in the genus Littorina and detection of null alleles in Littorina saxatilis

Microsatellite DNA is widely used as population genetic marker,but the cost of using microsatellites is high, as they usuallyneed to be developed and optimized for each species separately.Cross-species amplification of microsatellites is thereforecommonly applied to bring down the cost, but it can also involvegenotyping errors. We studied cross-species amplification ofmicrosatellites in four species of the Atlantic group of Littorina(Neritrema): L. saxatilis (Olivi, 1792), L. obtusata (Linnaeus,1758), L. fabalis (Turton, 1825) and L. arcana Hannaford Ellis,1978 to investigate whether markers originally developed fora more distantly related Pacific species [L. subrotundata (Carpenter,1864)] suffered from more amplification problems than markersdeveloped for one of the species in the Atlantic group (L. saxatilis).We also compared variation in amplification success among thespecies and among different regions in the NE Atlantic. Approximatelyhalf of the 12 primers developed for L. subrotundata and theseven primers developed for L. saxatilis were successfully amplifiedin other species of the subgenus. The success was dependenton phylogenetic distance among species within the subgenus.On the other hand, the variation in performance of the locibetween geographically remote populations of the same specieswas as high as variation among the species. In earlier studiesstatistical analyses indicated that several loci showed a heterozygotedeficiency due to null alleles. The presence of null alleleswas confirmed by a segregation analysis of the microsatelliteloci in eight half-sib families of L. saxatilis. (Received 2 April 2007; accepted 19 November 2007)     

Analysing botanical collecting effort in Amazonia and correcting for it in species range estimation

Aim The aim of this study is to analyse the distribution pattern of the botanical collecting effort in Amazonia so that it can be accounted for when interpreting phytogeographical patterns such as inferred species ranges. We also develop a mechanistic and transparent method for taking into account the bias in collecting effort when estimating likelihoods of species occurrences. Location Amazonia, Neotropics. Methods We utilized electronic data sets of georeferenced herbarium collections (1,063,530 in total). We plotted collecting localities (68,246 in total) on maps overlaid with 1° and 0.5° square grids, and analysed collecting effort using a geographical information system (GIS). We also drew a map of Thiessen polygons, using collecting localities as polygon centres, to visualize collecting density in a scale‐independent way. We then created a ‘collecting activity landscape’ in which well‐collected areas appear as peaks and poorly studied areas as valleys. We demonstrate how this surface can be utilized when estimating species distributions. Results The data available to us confirm that botanical collecting activity is still severely biased in Amazonia. The uncollected area represents 43% of the total area of Amazonia, while another 28% is poorly collected and only 2% can be considered relatively well collected. The Thiessen polygon network represents an improvement in the presentation of collecting intensity compared with square grids. Main conclusions The maps of botanical collecting effort in the Neotropics should be used for visually correcting phytogeographical interpretations. With the help of GIS applications the observed spatial bias in collecting effort can be utilized in estimating the likelihood of occurrence of species in a repeatable manner. These estimates, in turn, can be used for various purposes in basic and applied science as well as in decision‐making. The biased collecting effort should, in the long run, be corrected by further field work in unexplored areas, which can be identified with the maps presented here.     

A directional strategy for monitoring Cre-mediated recombination at the cellular level in the mouse

Functional redundancies, compensatory mechanisms, and lethal phenotypes often prevent the full analysis of gene functions through generation of germline null mutations in the mouse. The use of site-specific recombinases, such as Cre, which catalyzes recombination between loxP sites, has allowed the engineering of mice harboring targeted somatic mutations, which are both temporally controlled and cell-type restricted. Many Cre-expressing mouse lines exist, but only a few transgenic lines are available that harbor a reporter gene whose expression is dependent on a Cre-mediated event. Moreover, their use to monitor gene ablation at the level of individual cells is often limited, as in some tissues the reporter gene may be silenced, be affected by position-effect variegation, or reside in a chromatin configuration inaccessible for recombination. Thus, one cannot validly extrapolate from the expression of a reporter transgene to an identical ablation pattern for the conditional allele of a given gene. By combining the ability of Cre recombinase to invert or excise a DNA fragment, depending on the orientation of the flanking loxP sites, and the availability of both wild-type (WT) and mutant loxP sites, we designed a Cre-dependent genetic switch (FLEx switch) through which the expression of a given gene is turned off, while the expression of another one is concomitantly turned on. We demonstrate the efficiency and reliability of this switch to readily detect, in the mouse, at the single cell level, Cre-mediated gene ablation. We discuss how this strategy can be used to generate genetic modifications in a conditional manner.     

Monoclonal antibodies, immunofluorometric assay, and detection of human semenogelin in male reproductive tract: no association with in vitro fertilizing capacity of sperm

Semenogelin plays an important role in sperm clotting and is degraded into smaller fragments by prostate-specific antigen (PSA) during clot liquefaction. Semenogelin and its fragments inhibit sperm motility in vitro. We studied the expression of semenogelin I mRNA and its localization in various tissues of the male genital tract. We also studied semenogelin concentrations with respect to sperm parameters and the outcome of in vitro fertilization. Semenogelin protein was detected by immunohistochemical staining and semenogelin I mRNA was detected by Northern blot analysis in the seminal vesicles and ampullary part of the vas deferens, whereas specimens from the prostate, epididymis, testis, and the female genital tract were negative. Using monoclonal antibodies against semenogelin, an immunofluorometric assay was developed to measure semenogelin levels in seminal plasma and to evaluate possible correlations with sperm parameters and fertilization in vitro. No correlation was found between the semenogelin concentration and the volume of the ejaculate, sperm concentration, sperm motility, or in vitro fertilization rate. Semenogelin levels were positively correlated with the total protein concentration in seminal plasma, and there was an inverse correlation between the concentration of semenogelin and that of PSA. The levels of semenogelin appear to bear no relationship to the in vitro fertilization capacity of the spermatozoa.     

Bax and heart mitochondria: uncoupling and inhibition of respiration without permeability transition

The effects of Bax (full-length, FL, and C-terminal truncated, DeltaC) on respiration rate, membrane potential, MgATPase activity and kinetics of regulation of respiration were studied in isolated rat heart mitochondria and permeabilized cardiomyocytes. The results showed that while both Bax-FL and Bax-DeltaC permeabilized the outer mitochondrial membrane, released cytochrome c and reduced the respiration rate, the latter could be fully restored by exogenous cytochrome c only in the case of Bax-DeltaC, but not in presence of Bax-FL. In addition, Bax-FL but not Bax-DeltaC increased the MgATPase activity, and their effects on the mitochondrial membrane potential were quantitatively different. None of these effects was sensitive to cyclosporin A (CsA).It is concluded that Bax-FL affects both the outer and the inner mitochondrial membranes by: (1) opening large pores in the outer membrane; (2) inhibiting some segments of the respiratory chain in the inner membrane; and (3) uncoupling the inner mitochondrial membrane by increasing proton leak without opening the permeability transition pore (PTP).     

Determinants of Psychosocial Difficulties Experienced by Persons with Brain Disorders: Towards a ‘Horizontal Epidemiology’ Approach

BackgroundPersons with brain disorders experience significant psychosocial difficulties (PSD) in daily life, e.g. problems with managing daily routine or emotional lability, and the level of the PSD depends on social, physical and political environments, and psychologic-personal determinants. Our objective is to determine a brief set of environmental and psychologic-personal factors that are shared determinants of PSD among persons with different brain disorders.MethodsCross-sectional study, convenience sample of persons with either dementia, stroke, multiple sclerosis, epilepsy, migraine, depression, schizophrenia, substance dependence or Parkinson’s disease. Random forest regression and classical linear regression were used in the analyses.Results722 subjects were interviewed in four European countries. The brief set of determinants encompasses presence of comorbidities, health status appraisal, stressful life events, personality changes, adaptation, self-esteem, self-worth, built environment, weather, and health problems in the family.ConclusionsThe identified brief set of common determinants of PSD can be used to support the implementation of cross-cutting interventions, social actions and policy tools to lower PSD experienced by persons with brain disorders. This set complements a recently proposed reliable and valid direct metric of PSD for brain disorders called PARADISE24.     

Understanding the Impact of Brain Disorders: Towards a ‘Horizontal Epidemiology’ of Psychosocial Difficulties and Their Determinants

Objective

To test the hypothesis of ‘horizontal epidemiology’, i.e. that psychosocial difficulties (PSDs), such as sleep disturbances, emotional instability and difficulties in personal interactions, and their environmental determinants are experienced in common across neurological and psychiatric disorders, together called brain disorders.

Study Design

A multi-method study involving systematic literature reviews, content analysis of patient-reported outcomes and outcome instruments, clinical input and a qualitative study was carried out to generate a pool of PSD and environmental determinants relevant for nine different brain disorders, namely epilepsy, migraine, multiple sclerosis, Parkinson’s disease, stroke, dementia, depression, schizophrenia and substance dependency. Information from these sources was harmonized and compiled, and after feedback from external experts, a data collection protocol including PSD and determinants common across these nine disorders was developed. This protocol was implemented as an interview in a cross-sectional study including a convenience sample of persons with one of the nine brain disorders. PSDs endorsed by at least 25% of patients with a brain disorder were considered associated with the disorder. PSD were considered common across disorders if associated to 5 out of the 9 brain disorders and if among the 5 both neurological and psychiatric conditions were represented.

Setting

The data collection protocol with 64 PSDs and 20 determinants was used to collect data from a convenience sample of 722 persons in four specialized health care facilities in Europe.

Results

57 of the PSDs and 16 of the determinants included in the protocol were found to be experienced across brain disorders.

Conclusion

This is the first evidence that supports the hypothesis of horizontal epidemiology in brain disorders. This result challenges the brain disorder-specific or vertical approach in which clinical and epidemiological research about psychosocial difficulties experienced in daily life is commonly carried in neurology and psychiatry and the way in which the corresponding health care delivery is practiced in many countries of the world.     

The influence of environmental variables on larval growth of stoneflies (Plecoptera) in natural and deforested streams

A total 14 streams located in the Tatra Mts (Slovakia) were investigated. The studied river basins have different deforestation range (0–45.5%) influenced by windstorm. Daily and annual water temperature suggested that in streams overflowing through the area deforested by windstorm the temperature was higher than in selected non-disturbed streams. Higher average nutrient concentrations in samples from these streams are connected with nutrient mobilization from disturbed forest soils after the windstorm. Most of the damaged streams have higher trophic status, including POM and biofilms. The growth of the most abundant larvae increases with deforestation. Growth of species Leuctra rauscheri, Protonemura Montana, and Perlodes intricatus correlates with the sum of daily temperatures over a given time interval. Growth of species Brachyptera seticornis, Leuctra autumnalis and Isoperla sudetica are affected by stream trophy.