Aquaporins in complex tissues. I.Developmental patterns in respiratory and glandular tissues of rat

Developmentalexpression of aquaporin water transport proteins is not well understoodin respiratory tract or secretory glands; here we define aquaporinprotein ontogeny in rat. Expression of aquaporin-3 (AQP3), AQP4, andAQP5 proteins occurs within 2 wk after birth, whereas AQP1 firstappears before birth. In most tissues, aquaporin protein expressionincreases progressively, although transient high-level expression isnoted in distal lung (AQP4 at postnatal day+2) and trachea (AQP5 at postnatalday +21 and AQP3 at postnatal day+42). In mature animals, AQP5 is abundant in distallung and salivary glands, AQP3 and AQP4 are present in trachea, andAQP1 is present in all of these tissues except salivary glands.Surprisingly, all four aquaporin proteins are highly abundant innasopharynx. Unlike AQP1, corticosteroids did not induce expression ofAQP3, AQP4, or AQP5 in lung. Our results seemingly implicate aquaporinsin proximal airway humidification, glandular secretion, and perinatalclearance of fluid from distal airways. However, the studies underscorea need for detailed immunohistochemical characterizations anddefinitive functional studies.

     

Regional and local patterns in plant species richness with respect to resource availability

The hump-shaped relationship between plant species richness and productivity is a well-established and important paradigm. While plot-based species richness patterns on local scales have received much attention, little is currently known about species-based patterns on a regional scale. Using Ellenberg's indicator values for 1802 plant species in central Europe, we assess the patterns in regional species richness with respect to light, water, and mineral nutrient availability – three variables that strongly influence productivity. The results of this analysis are compared to those of published studies on smaller scales leading to the following conclusions:

• 1.

  On a regional scale in central Europe there is a hump-shaped relationship between soil nutrient supply and plant species richness within a given biome.

       

Aquaporins in complex tissues: distribution of aquaporins 1-5 in human and rat eye

Multiple physiological fluid movements areinvolved in vision. Here we define the cellular and subcellular sitesof aquaporin (AQP) water transport proteins in human and rat eyes byimmunoblotting, high-resolution immunocytochemistry, and immunoelectronmicroscopy. AQP3 is abundant in bulbar conjunctival epithelium andglands but is only weakly present in corneal epithelium. In contrast, AQP5 is prominent in corneal epithelium and apical membranes of lacrimal acini. AQP1 is heavily expressed in scleral fibroblasts, corneal endothelium and keratocytes, and endothelium covering thetrabecular meshwork and Schlemm's canal. Although AQP1 is plentiful inciliary nonpigmented epithelium, it is not present in ciliary pigmentedepithelium. Posterior and anterior epithelium of the iris and anteriorlens epithelium also contain significant amounts of AQP1, but AQP0(major intrinsic protein of the lens) is expressed in lens fiber cells.Retinal Müller cells and astrocytes exhibit notableconcentrations of AQP4, whereas neurons and retinal pigment epitheliumdo not display aquaporin immunolabeling. These studies demonstrateselective expression of AQP1, AQP3, AQP4, and AQP5 in distinct ocularepithelia, predicting specific roles for each in the complex networkthrough which water movements occur in the eye.

     

Troponin elevation in patients with various tachycardias and normal epicardial coronaries

Troponin elevation is usually synonymous with acute coronary syndrome (ACS). Although sensitive for ACS, the elevation of serum troponin, in the absence of clinical evidence of ischemia, should prompt a search for other etiologies of myocardial necrosis. In fact, elevated values of troponin are correlated with myocardial necrosis even though it does not discriminate the mechanism involved. We report a series of seven patients (age range 18-67 years), who presented with complaints of chest discomfort and were found to have regular supraventricular tachycardia (5 patients) and one patient each with atrial fibrillation and ventricular tachycardia. All these patients had elevated troponin I and underwent coronary angiography that revealed normal epicardial coronary arteries. This is first case series in which all patients underwent coronary angiography and none of the patients was hemodynamically unstable at the time of presentation. Patients with elevated troponin due to conditions other than ACS can receive inappropriate and delayed definitive diagnosis and treatment.     

Vaccination with a Plasmodium chabaudi adami multivalent DNA vaccine cross-protects A/J mice against challenge with P. c. adami DK and virulent Plasmodium chabaudi chabaudi AS parasites

A current goal of malaria vaccine research is the development of vaccines that will cross-protect against multiple strains of malaria. In the present study, the breadth of cross-reactivity induced by a 30K multivalent DNA vaccine has been evaluated in susceptible A/J mice (H-2a) against infection with the Plasmodium chabaudi adami DK strain and a virulent parasite subspecies, Plasmodium chabaudi chabaudi AS. Immunized A/J mice were significantly protected against infection with both P. c. adami DK (31–40% reduction in cumulative parasitemia) and P. c. chabaudi AS parasites, where a 30–39% reduction in cumulative parasitemia as well as enhanced survival was observed. The 30K vaccine-induced specific IFN-γ production by splenocytes in response to native antigens from both P. c. chabaudi AS and P. c. adami DK. Specific antibodies reacting with surface antigens expressed on P. c. adami DS and P. c. chabaudi AS infected red blood cells, and with opsonizing properties, were detected. These results suggest that multivalent vaccines encoding conserved antigens can feasibly induce immune cross-reactivity that span Plasmodium strains and subspecies and can protect hosts of distinct major histocompatibility complex haplotypes.     

Interpreting some outstanding features of the flora and vegetation of Madagascar

Six features are covered. (1) The high endemism, which is not discussed in detail, is all-pervasive, and has resulted from the isolation of Madagascar from Africa some 125 million years ago and their present separation by 430 km. (2) The great richness in plant species (especially relative to Africa), seen particularly in the families of woody species in the wetter vegetation-types, involves both sympatry and allopatry within genera, and is explicable in terms of much less extreme drying out than in Africa during the Pleistocene and effective ‘species-pumping’ rather than mass extinctions during that period. (3) The abundance and species-richness of palms, pandans, tree-ferns, bamboos, and certain families of dicot trees (notably Lauraceae, Monimiaceae, Myrsinaceae and Myristicaceae) in the lowland rain forests also appears to be a result of both past and present wetness of the climate, while it is hypothesized that the low stature of most lowland rain forests, paucity of large-girth trees, and small size and sparsity of broad-leaved herbs, are a result of most rain forest soils being old and relatively nutrient-poor. (4) Within the dry evergreen forest region where rainfall is moderate (900–1600 mm yr⁻¹) a sub-set of trees with fire-resistant bark seems to have evolved at sites prone to frequent ground fires, some perhaps spreading out of adjacent palm savanna on seasonally flooded sites. (5) Both the evolution of thicket rather than grassy woodland in the driest areas (300–600 mm yr⁻¹), and the abundance of evergreen trees and shrubs on ordinary soils – not confined to run-on sites – are explicable in terms of there being a finite chance of rain throughout the year rather than one short wet season, coupled with relatively high values for air humidity throughout the year. The same factors probably explain the abundance and variety of succulents in the thicket; they are found throughout and not just on rocks. (6) Concerning physical defence against herbivores, the rain forests, dry evergreen forests and deciduous forests all show a complete lack of plants with physiognomic features plausibly related to browsing by extinct giant birds (a strong contrast with New Zealand), but in the semi-deciduous thicket there are many tiny-leaved, mostly non-spiny shrubs and small trees, whose dense branching and impenetrability have plausibly evolved as a defence against browsing by elephant birds. The Didiereaceae of the thicket are spiny (unlike members of the same family in Africa), and are giant analogues of the ‘ocotillo’ (Fouquieria splendens) in western North America rather than of Cactaceae; their spines appear to be protecting the leaves more than the stems against arboreal primates, spine length paralleling leaf length.     

The hemopexin and O-glycosylated domains tune gelatinase B/MMP-9 bioavailability via inhibition and binding to cargo receptors

Gelatinase B/matrix metalloproteinase-9 (MMP-9), a key regulator and effector of immunity, contains a C-terminal hemopexin domain preceded by a unique linker sequence of approximately 64 amino acid residues. This linker sequence is demonstrated to be an extensively O-glycosylated (OG) domain with a compact three-dimensional structure. The OG and hemopexin domains have no influence on the cleavage efficiency of MMP-9 substrates. In contrast, the hemopexin domain contains a binding site for the cargo receptor low density lipoprotein receptor-related protein-1 (LRP-1). Furthermore, megalin/LRP-2 is identified as a new functional receptor for the hemopexin domain of MMP-9, able to mediate the endocytosis and catabolism of the enzyme. The OG domain is required to correctly orient the hemopexin domain for inhibition by TIMP-1 and internalization by LRP-1 and megalin. Therefore, the OG and hemopexin domains down-regulate the bioavailability of active MMP-9 and the interactions with the cargo receptors are proposed to be the original function of hemopexin domains in MMPs.