Membrane fluidity change in erythrocytes induced by complement system.

The structural change in erythrocyte membranes induced by antibody and complement was studied using phospholipid spin-labels. Sheep erythrocytes were labeled with phosphatidylcholine spin-label and various intermediate cells (erythrocyte-antibody complex (EA), EA bound with complement components from C1 to C7 (EAC1-7), EAC1-8, and EAC1-9) were prepared. Electron spin resonance spectra of EA, EAC1-7, and EAC1-8 were very similar to that of the erythrocytes, while that of EAC1-9 was markedly different. The overall splitting value for the lysed EAC1-9 (53 G) was much smaller than that for the erythrocytes (57 G), indicating a marked fluidization around the phosphatidylcholine label. The unlysed EAC1-9 membranes contained a limited fraction of the fluidized area. When EA was reacted with complement in the presence of 36% bovine serum albumin, the membranes were fluidized similarly to the lysed EAC1-9, although the hemolysis was largely blocked. The membranes of unlysed EAC1-9 prepared in isotonic (ethylenedinitrilo)tetraacetic acid were also fluidized, but to somewhat smaller extent. The role of C9 in the modification of erythrocyte membranes was also demonstrated using Mg2+ ghosts, which were prepared by hypotonic hemolysis in the presence of Mg2+. The membranes of Mg2+ ghost of EAC1-7 were markedly fluidized when bound with C8 and C9, but not affected by binding of C8 only. The component C8 was found to give a latent effect on the membranes that caused irreversible fluidization upon osmotic shock. The terminal component thus creates a fluidized area in the erythrocyte membranes through which small ions and molecules may diffuse more easily and the resulting osmotic unbalance may finally cause hemolysis.     

Melanocortins Contribute to Sequential Differentiation and Enucleation of Human Erythroblasts via Melanocortin Receptors 1, 2 and 5

In this study, we showed that adrenocorticotropic hormone (ACTH) promoted erythroblast differentiation and increased the enucleation ratio of erythroblasts. Because ACTH was contained in hematopoietic medium as contamination, the ratio decreased by the addition of anti-ACTH antibody (Ab). Addition of neutralizing Abs (nAbs) for melanocortin receptors (MCRs) caused erythroblast accumulation at specific stages, i.e., the addition of anti-MC2R nAb led to erythroblast accumulation at the basophilic stage (baso-E), the addition of anti-MC1R nAb caused accumulation at the polychromatic stage (poly-E), and the addition of anti-MC5R nAb caused accumulation at the orthochromatic stage (ortho-E). During erythroblast differentiation, ERK, STAT5, and AKT were consecutively phosphorylated by erythropoietin (EPO). ERK, STAT5, and AKT phosphorylation was inhibited by blocking MC2R, MC1R, and MC5R, respectively. Finally, the phosphorylation of myosin light chain 2, which is essential for the formation of contractile actomyosin rings, was inhibited by anti-MC5R nAb. Taken together, our study suggests that MC2R and MC1R signals are consecutively required for the regulation of EPO signal transduction in erythroblast differentiation, and that MC5R signal transduction is required to induce enucleation. Thus, melanocortin induces proliferation and differentiation at baso-E, and polarization and formation of an actomyosin contractile ring at ortho-E are required for enucleation.     

Coffee polyphenol caffeic acid but not chlorogenic acid increases 5'AMP-activated protein kinase and insulin-independent glucose transport in rat skeletal muscle

Chlorogenic acid is an ester of caffeic and quinic acids, and is one of the most widely consumed polyphenols because it is abundant in foods, especially coffee. We explored whether chlorogenic acid and its metabolite, caffeic acid, act directly on skeletal muscle to stimulate 5'-adenosine monophosphate-activated protein kinase (AMPK). Incubation of rat epitrochlearis muscles with Krebs buffer containing caffeic acid (≥0.1 mM, ≥30 min) but not chlorogenic acid increased the phosphorylation of AMPKα Thr(172), an essential step for kinase activation, and acetyl CoA carboxylase Ser(79), a downstream target of AMPK, in a dose- and time-dependent manner. Analysis of isoform-specific AMPK activity revealed that AMPKα2 activity increased significantly, whereas AMPKα1 activity did not change. This enzyme activation was associated with a reduction in phosphocreatine content and an increased rate of 3-O-methyl-d-glucose transport activity in the absence of insulin. These results suggest that caffeic acid but not chlorogenic acid acutely stimulates skeletal muscle AMPK activity and insulin-independent glucose transport with a reduction of the intracellular energy status.     

Dynamic sweating response of man to infrared irradiation in various spectral regions

In an attempt to detect differences in the thermal effect of infrared irradiation of different wavelengths, transient sweating response to infrared irradiation in various spectral regions was examined. In Series 1, the ventral or dorsal surface of the nude subject was irradiated repetitively for a period of 4 min (2 min on, 2 min off) by each of three kinds of infrared heaters with main emissivity in near-infrared (NIR; 0.7–2.8 m), intermediate-infrared (MIR; 1.5–5.8 m), and far-infrared (FIR; 2.8–25 m) regions. The sweating response on a non-irradiated area tended to be the greatest with MIR, while the magnitude of the sweating response on the irradiated area showed no consistent differences among various wavelengths. The results infer that MIR stimulated cutaneous thomoreceptors most effectively, while its direct effect on local sweat gland activity was minimal. In Series 2, the effects of 9–12 min irradiations in more restricted ranges of wavelength were compared by the combination of the three kinds of heaters with filters (translucent to wavelength ranges of 1.3–2.7, 2.7–3.5, 3.6–8.0 m, respectively). The sweating response on a remote area was predominantly greater with the range of 2.7–3.5 m than with the other wavelength ranges, while the local effect on sweating was minimal with this range. The results of Series 2 reinforce those of Series 1, indicating that the degree of stimulation of cutaneous thermoreceptors and of direct thermal effect on sweat gland activity differ with spectral regions incident on the skin, thus affecting local and remote effects on the sweating response.     

Excessive ingestion of long-chain polyunsaturated fatty acids during developmental stage causes strain- and sex-dependent eye abnormalities in mice

The eyes are riched in long-chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic acid [ARA; 20:4 (n−6)] and docosahexaenoic acid [DHA; 22:6 (n−3)]. Despite their abundance in the eyes, ARA and DHA cannot be sufficiently synthesized de novo in mammals. During gestation, eye development is exceptionally rapid, and substantial amounts of LC-PUFAs are needed to ensure proper eye development. Here, we studied the influences of dietary LC-PUFAs in dams (C57BL/6 and C3H/He) on the eye morphogenesis and organogenesis of their pups. Intriguingly, fetuses and newborn mice from C57BL/6 dams fed an LC-PUFA (particularly ARA)-enriched diet displayed a much higher incidence of eye abnormalities such as microphthalmia (small eye) and corneal opacity than those from dams fed an LC-PUFA-poor diet. The effects of LC-PUFAs on eye anomalies were evident only in the female pups of C57BL/6 inbred mice, not in those of C3H/He mice or male C57BL/6 mice. These results demonstrate a gene-by-environment (GxE) interaction in eye development in mice. Furthermore, our molecular analysis suggested the potential roles of Pitx3 and Pax6 in the above interaction involving ARA.     

An NB-LRR gene, <Emphasis Type="Italic">TYNBS1</Emphasis>, is responsible for resistance mediated by the <Emphasis Type="Italic">Ty</Emphasis>-<Emphasis Type="Italic">2 Begomovirus</Emphasis> resistance locus of tomato

Key message

An NB-LRR gene, TYNBS1, was isolated from Begomovirus-resistance locus Ty-2. Transgenic plant analysis revealed that TYNBS1 is a functional resistance gene. TYNBS1 is considered to be synonymous with Ty-2.

Abstract

Tomato yellow leaf curl disease caused by Tomato yellow leaf curl virus (TYLCV) is a serious threat to tomato (Solanum lycopersicum L.) production worldwide. A Begomovirus resistance gene, Ty-2, was introduced into cultivated tomato from Solanum habrochaites by interspecific crossing. To identify the Ty-2 gene, we performed genetic analysis. Identification of recombinant line 3701 confirmed the occurrence of a chromosome inversion in the Ty-2 region of the resistant haplotype. Genetic analysis revealed that the Ty-2 gene is linked to an introgression encompassing two markers, SL11_25_54277 and repeat A (approximately 200 kb). Genomic sequences of the upper and lower border of the inversion section of susceptible and resistant haplotypes were determined. Two nucleotide-binding domain and leucine-rich repeat-containing (NB-LRR) genes, TYNBS1 and TYNBS2, were identified around the upper and lower ends of the inversion section, respectively. TYNBS1 strictly co-segregated with TYLCV resistance, whereas TYNBS2 did not. Genetic introduction of genomic fragments containing the TYNBS1 gene into susceptible tomato plants conferred TYLCV resistance. These results demonstrate that TYNBS1 is a functional resistance gene for TYLCV, and is synonymous with the Ty-2 gene.

     

The biotron breeding system: a rapid and reliable procedure for genetic studies and breeding in rice

Oryza sativa is widely used as a model organism for many aspects of research in monocots and cereals. However, it has certain disadvantages as a model species compared with Arabidopsis thaliana, the eudicot species most widely used in plant sciences: first, it has a long cultivation time; and second, it requires considerably more space for growth. Here, we introduce a biotron breeding system, which allows rapid and reliable rice cultivation using a well-equipped artificial environmental chamber. This system involves use of regulation of CO? levels, removal of tillers and embryo rescue to overcome the disadvantages of rice cultivation. The rice cultivars Nipponbare, Koshihikari, Taichung 65 and Kasalath all showed vigorous growth and sufficient seed production in the biotron breeding system with accelerated flowering time. Nipponbare, which was the earliest among these cultivars, flowered at about 50 d after sowing. The life cycle of these plants could be further shortened using an embryo rescue technique on immature seeds at 7 d after pollination, thereby avoiding the lengthy process of seed maturation. Overall, it was possible to shorten the life cycle of Nipponbare to about 2 months under the controlled conditions. Furthermore, controlled crosses, which can be difficult with conventional cultivation methods, were easy to perform as we could control the exact timing of anther dehiscence. Thus, our biotron breeding system offers a valuable new approach to genetic and breeding studies in rice.     

Osmoelastic coupling in biological structures: a comprehensive thermodynamic analysis of the osmotic response of phospholipid vesicles and a reevaluation of the "dehydration force" theory

A comprehensive thermodynamic analysis of the osmotic response of phospholipid vesicles is presented, using the Gibbs free energy of a vesicle suspension including the elastic contribution of the bilayer membrane. The results indicate that, in addition to the hydrostatic pressure difference across the membrane and the interbilayer pressure due to electrostatic repulsion, the elastic pressure arising from the coupling between the osmotic stress and the elasticity of the membrane (osmoelastic coupling) should participate in the osmotic response of phospholipid vesicles. The data of Cowley et al. [Cowley, A. C., Fuller, N. L., Rand, R. P., & Parsegian, V. A. (1978) Biochemistry 17, 3163-3168] and of Parsegian et al. [Parsegian, V. A., Fuller, N., & Rand, R. P. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 2750-2754] on the osmotic shrinkage of multilayer vesicles are discussed in terms of the elastic pressure and the interbilayer pressure, and the proposed "dehydration force" theory is reevaluated from the viewpoint of the present analysis.