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Various biomonitoring methods are used worldwide to evaluate water quality and the ecological integrity of freshwater habitats. Most of these methods are based upon macroinvertebrates, mainly insects, whereas water mites (Hydrachnidia) are widely neglected. In the present review, I summarize the diversity and ecology of water mites and evaluate their potential as bioindicators. Studies correlating water mite assemblages with water quality are presented in a detailed historical overview. Possible constraints to use this group as bioindicators are also discussed. The particular importance of Hydrachnidia in the monitoring of springs is discussed, as well as the state of knowledge on the ecology of neotropical water mites. I present the first data on water mites as bioindicators in streams in Costa Rica and Panama. The need for further research is explained and a call for collaboration is expressed. [ABSTRACT FROM PUBLISHER]

Alzheimer's disease is characterized by the accumulation of amyloid deposits in the brain and the progressive loss of cognitive functions. Although the precise role of amyloid-β in disease progression remains somewhat controversial, many efforts to halt or reverse disease progression have focussed on reducing its synthesis or enhancing its removal. It is believed that brain and peripheral soluble amyloid-β are in equilibrium and it has previously been hypothesized that a reduction in peripheral amyloid-β can lower brain amyloid-β, thereby reducing formation of plaques predominantly composed of insoluble amyloid-β; the so-called peripheral sink hypothesis. Here we describe the use of an amyloid-β degrading enzyme, the endogenous metallopeptidase neprilysin, which is fused to albumin to extend plasma half-life and has been engineered to confer increased amyloid-β degradation activity. We used this molecule to investigate the effect of degradation of peripheral amyloid-β on amyloid-β levels in the brain and cerebrospinal fluid after repeated intravenous dosing for up to 4 months in Tg2576 transgenic mice, and 1 month in rats and monkeys. This molecule proved highly effective at degradation of amyloid-β in the periphery but did not alter brain or cerebrospinal fluid amyloid-β levels, suggesting that the peripheral sink hypothesis is not valid and is the first time that this has been demonstrated in non-human primates. [ABSTRACT FROM AUTHOR]

Lowering levels of peripheral amyloid-β has been proposed as a strategy to reduce plaques in patients with Alzheimer’s disease. Henderson et al. test a modified version of the amyloid-degrading enzyme neprilysin in rats, monkeys and Tg2576 mice. Levels of amyloid-β were reduced in the bloodstream, but not in the CNS.Alzheimer’s disease is characterized by the accumulation of amyloid deposits in the brain and the progressive loss of cognitive functions. Although the precise role of amyloid-β in disease progression remains somewhat controversial, many efforts to halt or reverse disease progression have focussed on reducing its synthesis or enhancing its removal. It is believed that brain and peripheral soluble amyloid-β are in equilibrium and it has previously been hypothesized that a reduction in peripheral amyloid-β can lower brain amyloid-β, thereby reducing formation of plaques predominantly composed of insoluble amyloid-β; the so-called peripheral sink hypothesis. Here we describe the use of an amyloid-β degrading enzyme, the endogenous metallopeptidase neprilysin, which is fused to albumin to extend plasma half-life and has been engineered to confer increased amyloid-β degradation activity. We used this molecule to investigate the effect of degradation of peripheral amyloid-β on amyloid-β levels in the brain and cerebrospinal fluid after repeated intravenous dosing for up to 4 months in Tg2576 transgenic mice, and 1 month in rats and monkeys. This molecule proved highly effective at degradation of amyloid-β in the periphery but did not alter brain or cerebrospinal fluid amyloid-β levels, suggesting that the peripheral sink hypothesis is not valid and is the first time that this has been demonstrated in non-human primates. [ABSTRACT FROM AUTHOR]

In this paper we give descriptions of two new species each of the genera Torrenticola Piersig, 1896 and Monatractides K. Viets, 1926 from South Africa: Torrenticola spatulifera n. sp., T. tsitsikamma n. sp., Monatractides drakensbergen n. sp., and M. nigromontanus n. sp. Additional data on distribution are given for T. binga K.O. Viets, 1971, T. disjuncta Lundblad, 1951, T. distans K.O. Viets, 1981, T. harrisoni K. Viets, 1956, T. ima K.O. Viets, 1974, T. proxima Lundblad, 1951, T. rhodesiensis K.O. Viets, 1971, and T. violacea K.O. Viets, 1972, as well as for M. capensis K. Viets, 1956, M. spinipalpis K.O. Viets, 1981, and M. c.f. ventriosa (K. Viets, 1916). Additional measurements, figures and information on the morphology are given for T. binga - description of gnathosoma and genital skeleton; T. disjuncta - first description of the male; T. harrisoni - description of gnathosoma and genital skeleton; T. proxima - first description of the male; T. rhodesiensis - description of the gnathosoma, T. violacea - first description of the female; and M. Spinipalpis - description of gnathosoma. [ABSTRACT FROM AUTHOR]

The Hydrachnidia (water mites) represent the most important group of the Arachnida in fresh water. Over 6,000 species have been described worldwide, representing 57 families, 81 subfamilies and more than 400 genera. The article analyzes extant water mite diversity and biogeography. Data on distribution and species richness of water mites are substantial but still far from complete. Many parts of the world are poorly investigated, Oriental and Afrotropical regions in particular. Moreover, information among different freshwater habitats is unbalanced with springs and interstitial waters disproportionately unrepresented. Therefore, more than 10,000 species could be reasonably expected to occur in inland waters worldwide. Based on available information, the Palaearctic region represents one of the better investigated areas with the highest number of species recorded (1,642 species). More than 1,000 species have been recorded in each of the Neotropical (1,305 species) and Nearctic regions (1,025 species). Known species richness is lower in Afrotropical (787 species) and Australasian (694 species) regions, and lowest in the Oriental region (554 species). The total number of genera is not correlated with species richness and is distinctly higher in the Neotropical (164 genera); genus richness is similar in the Palaearctic, Nearctic and Australasian regions (128–131 genera) and is lower in the Afrotropical and Oriental regions with 110 and 94 genera, respectively. A mean number of about three genera per family occur in the Palaeartic, Nearctic and Oriental while an average of more than four genera characterizes the families of Australasian and Afrotropical regions and more than five genera those of the Neotropical. Australasian fauna is also characterized by the highest percentage of endemic genera (62%), followed by Neotropical (50.6%) and Afrotropical (47.2%) regions. Lower values are recorded for the Palaearctic (26.9%), Oriental (24.4%) and Nearctic (21.4%). The Palaearctic and Nearctic have the highest faunistic similarity, some minor affinities are also evident for the generic diversification of Holarctic and Oriental families. The faunas of Southern Hemisphere bioregions are more distinct and characterized by the presence of ancient Gondwanan clades with a regional diversification particularly evident in the Neotropics and Australasia. This scenario of water mite diversity and distribution reflect the basic vicariance pattern, isolation, phylogenetic diversification, recent climatic vicissitudes and episodes of dispersal between adjacent land masses together with extant ecological factors can be evoked to explain distribution patterns at a global scale. [ABSTRACT FROM AUTHOR]

In this paper the Latin American species of the water mite genus Torrenticola are presented and discussed comprehensively for the first time. All 21 previously known species from Central and South America are portrayed in detail, descriptions are given for 36 new species from Costa Rica: Torrenticola adunca, T. alargada, T. alexandra, T. alticola, T. altifontana, T. amalgamada, T. ambigua, T. australis, T. baderi, T. chicacoxalis, T. chirripoensis, T. collina, T. conopalpis, T. corta, T. cortobrazo, T. costaricense, T. cumbrensis, T. delgada, T. dispersa, T. elhachensis, T. esferica, T. esquinada, T. fastigata, T. flexirostris, T. fontinale, T. guanacastensis, T. harpagophora, T. levicoxalis, T. menudopalpis, T. monticola, T. pervagata, T. rapidensis, T. ratoncitoi, T. rubella, T. tilaranensis and T. torpebrazo . The Latin American species of Torrenticola are subdivided in a clear, robust system of ten species groups – five of these are regarded as phylogenetic entities, five as rather artificial groups. An identification key to these species groups is given, as well as keys, measurement tables, figures and detailed descriptions of all species within these groups. The males of T. gennada Cook, 1980 and T. keesdavidsi Cramer, 1992, as well as the female of T. amala Cook, 1980 are described for the first time. Descriptions and figures of the genital skeleton of nine formerly described species are given for the first time. All information available on the habitat preferences (habitat type, stream velocity, altitudinal distribution, choriotope types, temperature and conductivity) and the geographical distribution of the species is presented. Zoogeographical characteristics, endemicity and habitat preferences of the 42 species of Torrenticola found in Costa Rica are analysed. The main object of this study is to facilitate further systematic and ecological work on this important genus and to make it accessible for general limnological surveys. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 150, 443–678. [ABSTRACT FROM AUTHOR]

This paper presents an ecological analysis of the water mite fauna of 350 streams, rivers, springs and standing waters from all main regions, ecosystems and elevations in Costa Rica. From 509 sample sites about 20,000 water mites representing 74 genera in 21 families were collected. 17 habitat types were distinguished and 11 further environmental parameters were measured. The significance of the particular parameters was analysed using canonical correspondence analysis (CCA). Habitat type, elevation, temperature and velocity were identified as major factors determining water mite assemblages. The analyses showed the existence of characteristic water mite coenoses in different neotropical habitats and the suitability of neotropical water mites for biomonitoring programmes. [ABSTRACT FROM AUTHOR]

MRL Ipr/lpr mice develop a generalized autoimmune disease associated with a massive accumulation In the peripheral lymphoid organs of abnormal, phenotyplcally immature T cells. Both the lymphoadenopathy and the autoimmunity are thymus-dependent and likely to arise from an aberrant pathway of intrathymic differentiation. We here present the marked beneficial effects acquired in MRL lpr/lpr mice after administration of a novel Immunomodulator called linomlde. The highly altered pattern of thymic subpopulatlons In MRL lpr/lpr mice Is normalized after llnomlde-treatment. Concomltantly, the peripheral T cell compartment, which in MRL lpr/lpr is highly deficient In producing and responding to IL-2, gains substantial functional reactivities. We propose that linomide acts by correcting the abnormal T cell development In autoimmune MRL lpr/lpr mice. This new immunomodulator may be a useful tool for providing insight Into both the pathogenesis of autoimmune disorders and intrathymic differentiation. [ABSTRACT FROM PUBLISHER]

Many studies emphasized the role that water mites play within the invertebrate communities of spring ecosystems, regarding species diversity and its significance within the crenal food web, as well as the specific preferences water mites exhibit towards spring typology. In pristine natural springs with permanent flow, water mites are nearly always present and usually display high diversity. This study aimed to determine whether significant differences in water mite assemblages between rheocrene (river-forming springs with dominant riffle habitats) and limnocrene (lake-forming springs with dominant pool habitats) karst springs could be detected in terms of species richness, diversity and abundance, but also in different ratios of specific synecological groups: crenobiont (exclusively found in springs), crenophilous (associated with springs) and stygophilous (associated with groundwater) water mite taxa. Our research was carried out on four limnocrenes and four rheocrenes in the Dinaric karst region of Croatia. Seasonal samples (20 sub-samples per sampling) were taken at each spring with a 200-µm net, taking into consideration all microhabitat types with coverage of at least 5%. Water mite abundance was found not to differ between morphological spring types. Significantly higher values of species richness and diversity indices were found in rheocrenes compared to limnocrenes, like those usually reported for this type of springs. However, unlike the studies previously reported, in this case, the higher shares of crenophilous and crenobiont water mite individuals were found in limnocrenes. The differences between stygophilous water mite taxa ratios among spring morphotypes were not statistically significant, indicating that the degree of the groundwater/surface water interaction (and water mite interaction therein) does not seem to be directly influenced by spring morphotype. Within this research, 40% of identified water mite species (eight out of twenty) were recorded for the first time in Croatia, thus highlighting again a huge gap in water mite knowledge of karst springs. [ABSTRACT FROM AUTHOR]