Gene expression pattern of glucose transporters in the skeletal muscles of newly hatched chicks

The gene expression pattern of the glucose transporters (GLUT1, GLUT3, GLUT8, and GLUT12) among pectoralis major and minor, biceps femoris, and sartorius muscles from newly hatched chicks was examined. GLUT1 mRNA level was higher in pectoralis major muscle than in the other muscles. Phosphorylated AKT level was also high in the same muscle, suggesting a relationship between AKT and GLUT1 expression.     

Gamma-radiolysis of D-glucose in aerated, aqueous solution.

Gamma-Radiolysis of D-glucose in aerated, aqueous solution gives mainly D-glucono-1,5-lactone, D-arabino-hexosulose, and D-ribo-hexos-3-ulose, together with D-xylo-hexos-4-ulose, D-xylo-hexos-5-ulose, and other pentose, tetrose, and triose derivatives as minor products, which were estimated by mass spectrometry of their alditol-d acetates. These hexose derivatives appear to be produced by the decomposition of D-glucose peroxy-radicals which are formed by the reaction of the primary radicals of D-glucose with oxygen. Bond scission of the peroxy-radicals yields triose, tetrose, and pentose. A radiolysis mechanism for the degradation of D-glucose in aerated, aqueous solution is proposed, based on the reaction of several kinds of D-glucose radical with oxygen.     

Reverse-flow island flap: clinical report and venous drainage

Twenty-two reverse-flow island flaps were transferred. These included peroneal, forearm, anterior tibial, and temporal flaps. Sixteen of 22 flaps survived completely. We encountered partial necrosis in 4 flaps and total necrosis in only 2 flaps. We credit this success to the reliability and availability of the peroneal, forearm, and temporal flaps; but we do not encourage use of the anterior tibial flap. The flaps that survived well did not show any signs of venous congestion. The advantage of the reverse-flow island flap is that it can be transferred from a proximal to a distal location. Using cadavers and fresh amputated limbs, studies on venous drainage of the reverse-flow island flap were performed. The venae comitantes had numerous venous valves and communicating branches, but more than sufficient reflux of the venous blood occurred through the valves at pressures of 90 to 105 cmH2O. We believe that the venous drainage of the reverse-flow island flap occurs as a result of reflux actions at the valve, communicating branches between the venae comitantes, and bypass vessels around the valves.     

Evidence for the presence of androgen receptors in human Leydig cells

Localization of androgen receptors (ARs) in the human testis Leydig cells was examined with an AR assay and Northern blot analysis. Leydig cells, highly purified on a Percoll gradient, were used for the experiments. AR concentration in the total cell extract containing both the cytosol and nuclear fractions in Leydig cells was measured using [3H]methyltrienolone. ARs in Leydig cells showed a high affinity for [3H]methyltrienolone and the Kd and Bmax of the receptors were 1.24 nM and 11.7 fmol/mg protein, respectively. Northern blot analysis, using a 32P-labeled full-length human AR complementary DNA (cDNA) detected a 9.5-kb hybridizing band in the total RNA extracted from Leydig cells. These data can be interpreted as evidence of the existence of ARs in human Leydig cells.     

Extraadrenal expression of steroid 21-hydroxylase and 11β-hydroxylase by a benign testicular leydig cell tumor

We present an unusual case with bilateral testicular Leydig cell tumors displaying extraadrenal expression of steroid 21-hydroxylase and 11β-hydroxylase. Histological examination of a 38-yr-old man infertile due to azoospermia showed him to have bilateral testicular Leydig cell tumors. The in vitro steroidogenic potential of the tumors and their adjacent testicular tissue was evaluated using organ culture. Tumor tissue was found to secrete deoxycorticosterone (DOC), corticosterone (B) and cortisol, which are not produced in normal adult testis, into the medium, while testicular tissue adjacent to the tumors secreted a small amount of DOC and B. Northern blot analysis with cytochrome P-450_C21 complementary DNA (cDNA) and P-450_11β cDNA as probes revealed that the tumor contained a considerable amount of mRNA for P-450_C21 and P-450_11β, while the mRNAs were not detected in the testicular tissues adjacent to the tumors. It is suggested that the high local levels of estrogen and/or progesterone within the Leydig cell tumors and their adjacent testicular tissues induced extraadrenal expression of steroid 21-hydroxylase and 11β-hydroxylase by the tumors and their adjacent testicular tissues.     

Chemoenzymatic synthesis of hydroxytyrosol monoesters and their suppression effect on nitric oxide production stimulated by lipopolysaccharides

Fatty acid monoesters of hydroxytyrosol [2-(3,4-dihydroxyphenyl)ethanol] were synthesized in two steps from tyrosol (4-hydroxyphenylethanol) by successive Candida antarctica lipase B-catalyzed chemoselective acylation on the primary aliphatic hydroxy group over phenolic hydroxy group in tyrosol, and 2-iodoxybenzoic acid (IBX)-mediated hydroxylation adjacent to the remaining free phenolic hydroxy group. Examination of their suppression effects on nitric oxide production stimulated by lipopolysaccharides in RAW264.7 cells showed that hydroxytyrosol butyrate exhibited the highest inhibition (IC₅₀ 7.0 μM) among the tested compounds.     

Functional Characterization of a Silicon Transporter Gene Implicated in Silicon Distribution in Barley

Silicon (Si) is a beneficial element for plant growth. In barley (Hordeum vulgare), Si uptake by the roots is mainly mediated by a Si channel, Low Silicon1 (HvLsi1), and an efflux transporter, HvLsi2. However, transporters involved in the distribution of Si in the shoots have not been identified. Here, we report the functional characterization of a homolog of HvLsi1, HvLsi6. HvLsi6 showed permeability for Si and localized to the plasma membrane. At the vegetative growth stage, HvLsi6 was expressed in both the roots and shoots. The expression level was unaffected by Si supply. In the roots, HvLsi6 was localized in epidermis and cortex cells of the tips, while in the leaf blades and sheaths, HvLsi6 was only localized at parenchyma cells of vascular bundles. At the reproductive growth stage, high expression of HvLsi6 was also found in the nodes. HvLsi6 in node I was polarly located at the transfer cells surrounding the enlarged vascular bundles toward the numerous xylem vessels. These results suggest that HvLsi6 is involved in Si uptake in the root tips, xylem unloading of Si in leaf blade and sheath, and intervascular transfer of Si in the nodes. Furthermore, HvLsi2 was found to be localized at the parenchyma cell layer adjacent to the transfer cells with opposite polarity of HvLsi6, suggesting that the coupling of HvLsi6 and HvLsi2 is involved in the intervascular transfer of Si at the nodes. Si translocated via the enlarged vascular bundles is unloaded to the transfer cells by HvLsi6, followed by HvLsi2 to reload Si to the diffuse vascular bundles, which are connected to the upper part of the plant, especially the panicles, the ultimate Si sink.Silicon (Si) is a beneficial element for plant growth. It enhances the resistance of plants to various biotic and abiotic stresses (Epstein, 1999; Ma and Takahashi, 2002; Ma and Yamaji, 2006). For example, Si reduces the epidemics of both leaf and panicle blast in rice (Oryza sativa; Datnoff and Rodrigues, 2005) and decreases the incidence of powdery mildew in cucumber (Cucumis sativus), barley (Hordeum vulgare), and wheat (Triticum aestivum; Fauteux et al., 2005). Si also suppresses insect pests such as stem borer (Chilo suppressalis), brown planthopper (Nilaparvata lugens), and rice green leafhopper (Nephotettix cincticeps; Savant et al., 1997). Resistance to the damage by wild rabbit in wheat is also enhanced by an increased amount of Si in leaf tissue (Cotterill et al., 2007). Si is also able to alleviate lodging, drought, and low- and high-temperature stresses (Ma, 2004). The beneficial effects of Si under phosphate deficiency, phosphate excess, and manganese and salt toxicity stresses have been observed in many plants (Ma and Takahashi, 2002). Usually, the more Si that accumulates in the shoots, the greater its effect in enhancing the plant’s response. This is because most effects of Si are expressed through the formation of silica gel, which is deposited on leaves, stems, and other organs of plants (Ma and Yamaji, 2006). Therefore, for the plant to benefit from Si, a high accumulation is required. However, Si accumulation greatly varies with plant species, and this difference has been attributed to the ability of plants to take up Si.Transporters responsible for Si uptake by roots have been identified in several plant species, including barley, maize (Zea mays), pumpkin (Cucurbita moschata), rice, wheat (Ma et al., 2011), and most recently in horsetail (Equisetum arvense; EaNIP3s [for Nod26-like major intrinsic protein3]; Grégoire et al., 2012). Two different types of transporter, Si-permeable channel and efflux transporter, are involved in the Si-uptake process. Low Silicon1 (Lsi1) belongs to a NIP subfamily of aquaporin-like proteins and functions as a Si-permeable channel. Lsi1 in rice is localized in the distal side of root exodermis and endodermis (Ma et al., 2006), but Lsi1 in barley, maize, and pumpkin is localized in the epidermis and cortex (Chiba et al., 2009; Mitani et al., 2009b, 2011). On the other hand, Lsi2 functions as an efflux Si transporter and belongs to a putative anion transporter family without any similarity to Lsi1. Lsi2 in rice is also localized at the root exodermis and endodermis as Lsi1, but it is polarly localized at the proximal side (Ma et al., 2007). By contrast, Lsi2 in barley and maize is localized only to the endodermis of roots. Furthermore, these transporters do not show polar localization in barley and maize (Mitani et al., 2009a). Therefore, Si uptake mediated by Lsi1 and Lsi2 shows different pathways between rice and other plant species (Ma et al., 2011).Following uptake by the roots through Lsi1 and Lsi2, Si is translocated to the aboveground part and distributed in different tissues. Lsi6, a homolog of Lsi1, is involved in xylem unloading of Si in rice (Yamaji et al., 2008). Lsi6 is localized on the adaxial side of the xylem parenchyma cells in the leaf sheaths and leaf blades. Knockout of Lsi6 resulted in altered distribution of Si in the leaf cells. Furthermore, at the reproductive growth stage of rice, Lsi6 is also highly expressed at the nodes (Yamaji and Ma, 2009). At node I below the panicle, Lsi6 is mainly localized at the xylem transfer cells with polarity facing toward the xylem vessel (Yamaji and Ma, 2009). Knockout of Lsi6 decreased Si accumulation in the panicle but increased Si accumulation in the flag leaf. These findings indicate that Lsi6 is also required for the intervascular transfer of Si in rice, transferring Si from the enlarged vascular bundles coming from the roots to the diffuse vascular bundles connected to the panicle.Barley is a Si-accumulating species, although the accumulation extent is lower than that of rice. Transporters responsible for Si uptake in barley roots have been identified (Chiba et al., 2009; Mitani et al., 2009a); however, transporters for Si distribution in aboveground plant tissues are unknown. In this study, we functionally characterized a rice Lsi6 homolog gene in barley, HvLsi6, in terms of transport activity and expression pattern, as well as cellular and subcellular localizations. We found that HvLsi6 is probably involved in Si uptake in the root tip, xylem unloading in the leaf, and intervascular transfer of Si at the nodes in barley. We further found that HvLsi2 was also expressed in the nodes and involved in the intervascular transfer by coupling with HvLsi6.     

Cloning, functional characterization and heterologous expression of TaLsi1, a wheat silicon transporter gene

Silicon (Si) is known to be beneficial to plants, namely in alleviating biotic and abiotic stresses. The magnitude of such positive effects is associated with a plant's natural ability to absorb Si. Many grasses can accumulate as much as 10% on a dry weight basis while most dicots, including Arabidopsis, will accumulate less than 0.1%. In this report, we describe the cloning and functional characterization of TaLsi1, a wheat Si transporter gene. In addition, we developed a heterologous system for the study of Si uptake in plants by introducing TaLsi1 and OsLsi1, its ortholog in rice, into Arabidopsis, a species with a very low innate Si uptake capacity. When expressed constitutively under the control of the CaMV 35S promoter, both TaLsi1 and OsLsi1 were expressed in cells of roots and shoots. Such constitutive expression of TaLsi1 or OsLsi1 resulted in a fourfold to fivefold increase in Si accumulation in transformed plants compared to WT. However, this Si absorption caused deleterious symptoms. When the wheat transporter was expressed under the control of a root-specific promoter (a boron transporter gene (AtNIP5;1) promoter), a similar increase in Si absorption was noted but the plants did not exhibit symptoms and grew normally. These results demonstrate that TaLsi1 is indeed a functional Si transporter as its expression in Arabidopsis leads to increased Si uptake, but that this expression must be confined to root cells for healthy plant development. The availability of this heterologous expression system will facilitate further studies into the mechanisms and benefits of Si uptake.