Cattle Is Possible Host Animal of The Land Leech (Advanced Studies on Sustainable Animal Production: Interrelationships among Human, Animal and Environment, 8th International Symposium of Integrated Field Science)

Poster Sessio

Functional expression and characterization of an archaeal aquaporin. AqpM from methanothermobacter marburgensis.

Researchers have described aquaporin water channels from diverse eubacterial and eukaryotic species but not from the third division of life, Archaea. Methanothermobacter marburgensis is a methanogenic archaeon that thrives under anaerobic conditions at 65 °C. After transfer to hypertonic media,M. marburgensis sustained cytoplasmic shrinkage that could be prevented with HgCl2. We amplified aqpM by PCR from M. marburgensis DNA. Like known aquaporins, the open reading frame of aqpM encodes two tandem repeats each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro-Ala (NPA). Unlike other known homologs, the putative Hg2+-sensitive cysteine was found proximal to the first NPA motif in AqpM, rather than the second. Moreover, amino acids distinguishing water-selective homologs from glycerol-transporting homologs were not conserved in AqpM. A fusion protein, 10-His-AqpM, was expressed and purified from Escherichia coli. AqpM reconstituted into proteoliposomes was shown by stopped-flow light scattering assays to have elevated osmotic water permeability (P f = 57 μm·s−1 versus12 μm·s−1 of control liposomes) that was reversibly inhibited with HgCl2. Transient, initial glycerol permeability was also detected. AqpM remained functional after incubations at temperatures above 80 °C and formed SDS-stable tetramers. Our studies of archaeal AqpM demonstrate the ubiquity of aquaporins in nature and provide new insight into protein structure and transport selectivity. To withstand environmental and physiological stresses, organisms must be able to rapidly absorb and release water. Facilitated transport of water across cell membranes must be highly selective to prevent uncontrolled movement of other solutes, protons, and ions. Discovery of the aquaporins provided a molecular explanation to these processes (2). More than 200 aquaporins have now been identified, and their presence has been established in most forms of life (3). No aquaporin from Archaea has yet been characterized, although functional roles for a water channel protein have been predicted in these organisms (4). Two major protein family subsets are presently recognized, water-selective channels (aquaporins) and glycerol-transporting homologs with varying water permeabilities (aquaglyceroporins). The permeation selectivity of new members of the protein family may be predicted by a small number of conserved residues (5, 6). Several prokaryotic aquaporins and aquaglyceroporins are known. The bacterial water channel, AqpZ, was first identified in Escherichia coli (7, 8). Movement of water across the bacterial plasma membrane may be part of the osmoregulatory response by which microorganisms adjust cell turgor (9), although the regulation and physiological role of AqpZ are being reassessed (10). AqpZ is a highly stable tetramer with negligible permeability to glycerol. In contrast, the glycerol permeability of the glycerol facilitator (GlpF) fromE. coli has long been recognized (11). GlpF has relatively limited water permeability (12), and the tetrameric form has reduced stability in some detergents (13). Atomic resolution structures have been solved for GlpF (14) as well as human and bovine AQP11 (15-17). These have elucidated differential specificities and functional mechanisms of the two sequence-related proteins. Archaea and certain other microorganisms are able to withstand exceptional challenges in maintaining water balance as they thrive in extreme environments including saturated salt solutions, extreme pH, and temperatures up to 130 °C (18). We recently recognized the DNA sequence of AqpM, a candidate aquaporin or aquaglyceroporin in the genome of a methanogenic thermophilic archaeon,Methanothermobacter marburgensis 2 (,19). Here we investigate water permeability in living cells and report the purification, functional reconstitution, and characterization of AqpM

Water structure changes induced by ceramics can be detected by increased permeability through aquaporin

Aquporins are intrinsic membrane proteins that function as water channel to transport water and/or mineral nutrients across biological membranes. In this study, we aimed to clarify whether water structure can be changed by the presence of ceramics and whether such a change can be determined by aquaporin. First, we confirmed that ceramics could transform tap water into active tap water by increasing water permeability through aquaporin. We also found that this change in water permeability by treatment with ceramics occurred in distilled water. The distilled water was determined to exhibit the same aquaporin permeability as the original tap water. Our data indicate that the aquaporin permeability of water can be changed by severe physical shocks, such as slapping and sonication, which is consistent with the implication that the aquaporin permeability is closely related to the structure of the water. In this study, using aquaporins, we first reported that the treatment of water with ceramics can affect the structure of water, and the water can retain the structure for a given period under certain conditio

Plant aquaporins: Their roles beyond water transport

Compared to other organisms, plants have evolved a greater number of aquaporins with diverse substrates and functions to adapt to ever-changing environmental and internal stimuli for growth and development. Although aquaporins were initially identified as channels that allow water molecules to cross biological membranes, progress has been made in identifying various novel permeable substrates. Many studies have characterized the versatile physiological and biophysical functions of plant aquaporins. Here, we review the recent reports that highlight aquaporin-facilitated regulation of major physiological processes and stress tolerance throughout plant life cycles as well as the potential prospects and possibilities of applying aquaporins to improve agricultural productivity, food quality, environmental protection, and ecological conservation

Heterogeneity of immune complex-derived anti-DNA antibodies associated with lupus nephritis

Heterogeneity of immune complex-derived anti-DNA antibodies associated with lupus nephritis. The mechanisms responsible for the tissue injuries associated with lupus nephritis have not yet been well explained. We have investigated the characteristics of anti-DNA antibodies in circulating immune complexes (CIC) and in the deposits of renal glomeruli in patients with active lupus nephritis. The CIC-derived antibodies expressed anti-DNA idiotypes (Id) designated as 0-81 Id and NE-1 Id, and bound mainly to single-stranded DNA but never to glomerular basement membrane (GBM) antigens. On the other hand, the immunoglobulins (Ig) eluted from renal glomeruli of lupus patients reacted not only with DNA but also with GBM, proteoglycan, and heparan sulfate. The binding of glomeruli-deposited Ig was markedly low when GBM antigens were used after treatment with heparitinase, suggesting that some anti-DNA antibodies may bind directly to GBM antigens associated with heparan sulfate, and form in situ IC in renal glomeruli. It was also revealed that the renal eluates obtained after passing through GBM antigen-coupled Sepharose lost the binding ability with GBM but still retained DNA-binding and 0-81 Id activity, showing the participation of circulating IC-derived anti-DNA antibodies in the glomerular deposits. Theoretically there may be two mechanisms in the pathogenesis of lupus nephritis through the deposition of circulating IC and through in situ formation of anti-DNA IC in renal glomeruli. The diversity ofhistological features in lupus kidneys may be attributed to the heterogeneity of the mechanisms