Possible involvement of leaf gibberellins in the clock-controlled expression of XSP30, a gene encoding a xylem sap lectin, in cucumber roots

Root-produced organic compounds in xylem sap, such as hormones and amino acids, are known to be important in plant development. Recently, biochemical approaches have revealed the identities of several xylem sap proteins, but the biological functions and the regulation of the production of these proteins are not fully understood. XYLEM SAP PROTEIN 30 kD (XSP30), which is specifically expressed in the roots of cucumber (Cucumis sativus), encodes a lectin and is hypothesized as affecting the development of above-ground organs. In this report, we demonstrate that XSP30 gene expression and the level of XSP30 protein fluctuate in a diurnal rhythm in cucumber roots. The rhythmic gene expression continues for at least two or three cycles, even under continuous light or dark conditions, demonstrating that the expression of this gene is controlled by a circadian clock. Removal of mature leaves or treatment of shoots with uniconazole-P, an inhibitor of gibberellic acid (GA) biosynthesis, dampens the amplitude of the rhythmic expression; the application of GA negates these effects. These results suggest that light signals perceived by above-ground organs, as well as GA that is produced, possibly, in mature leaves, are important for the rhythmic expression of XSP30 in roots. This is the first demonstration of the regulation of the expression of a clock-controlled gene by GA.     

Relative biological effectiveness and tolerance dose of fission neutrons in canine skin for a potential combination of neutron capture therapy and fast-neutron therapy

To investigate the potential efficacy of fission neutrons from a fast-neutron reactor for the treatment of radioresistant tumors, the relative biological effectiveness (RBE) and tolerance dose of fission neutrons in canine skin were determined. The forelimbs of 34 healthy mongrel dogs received a single dose of fission neutrons (5.6, 6.8, 8.2, 9.6 or 11 Gy) or 137Cs gamma rays (10, 15, 20, 25 or 30 Gy). Based on observations of radiodermatitis for each radiation, the single-fraction RBE of fission neutrons in the sixth month was calculated as approximately 3. The tolerance doses of fission neutrons and gamma rays, defined as the highest doses giving no moist desquamation on the irradiated skin in the recovery phase, were estimated as 7.6 Gy and 20 Gy, respectively. The tolerance dose of 7.6 Gy of fission neutrons included 5.0 Gy of fast neutrons possessing high anti-tumor effects and 1.4 x 10(12) n/cm2 of thermal neutrons, which could be applicable to neutron capture therapy (NCT). The combination of fast-neutron therapy and NCT using a fast-neutron reactor might be useful for the treatment of radioresistant tumors.     

Detection of 3-methoxy-4-hydroxyphenylglycol in rabbit skeletal muscle microdialysate

A high-performance liquid chromatography with electrochemical detection (HPLC-ED) method is described for determination of 3-methoxy-4-hydroxyphenylglycol (MHPG) in microdialysate from the skeletal muscle interstitial space. Using a microdialysis technique, we sampled 30 microl dialysate from the skeletal muscle interstitial space and injected dialysate directly into HPLC-ED system. The control MHPG concentration of dialysate was 213+/-18 pg/ml. The MHPG concentrations were reduced by entacapone (catechol-O-methyltransferase inhibitor, COMT), augmented by local infusion of dihydroxyphenylglycol. This system offers a new possibility for simple, rapid monitoring of MHPG as an index of COMT activity in skeletal muscle.     

Insight into tachykinin-related peptides,their receptors,and invertebrate tachykinins: a review

Tachykinins (TKs) constitute the largest vertebrate neuropeptide family with multifunctions in central and peripheral tissues. In several invertebrate species, two types of structurally related peptides, 'tachykinin-related peptides (TKRPs)' and 'invertebrate tachykinins (inv-TKs)' have been identified. TKRPs, isolated from the nerve and/or gut tissues, contain the common C-terminal sequence -Phe-X-Gly-Y-Arg-NH(2) (X and Y are variable) analogous to the vertebrate TK consensus -Phe-X-Gly-Leu-Met-NH(2), and exhibit vertebrate TK-like contractile activity on invertebrate gut tissues. Inv-TKs have been shown to be present exclusively in the salivary gland of several species, to share vertebrate TK consensus motif, and to possess TK-like potencies on vertebrate, not invertebrate tissues. However, the functional and evolutionary relevance of TKRPs and inv-TKs to vertebrate TKs remains to be understood. Recent studies have revealed that TKRP precursors dramatically differ from vertebrate preprotachykinins in structural organization and that TKRP receptors share structural and functional properties with vertebrate TK receptors. Moreover, the C-terminal arginine in TKRPs has been shown to play an essential role in discriminating their receptors from vertebrate TK receptors. Such recent marked progress is expected to enhance further investigation of biological roles of TKRPs. This review provides an overview of the basic findings obtained previously and a buildup of new knowledge regarding TKRPs and inv-TKs. We also compare TKRPs and inv-TKs to vertebrate TKs with regard to evolutionary relationships in structure and function among these structurally related peptides.     

Importance of Ca2+ influx by Na+/Ca2+ exchange under normal and sodium-loaded conditions in mammalian ventricles

Na⁺/Ca²⁺ exchange (NCX) is a major Ca²⁺ extrusion system in cardiac myocytes, but can also mediate Ca²⁺ influx and trigger sarcoplasmic reticulum Ca²⁺ release. Under conditions such as digitalis toxicity or ischemia/reperfusion, increased [Na⁺]_i may lead to a rise in [Ca²⁺]_i through NCX, causing Ca²⁺ overload and triggered arrhythmias. Here we used an agent which selectively blocks Ca²⁺ influx by NCX, KB-R7943 (KBR), and assessed twitch contractions and Ca²⁺ transients in rat and guinea pig ventricular myocytes loaded with indo-1. KBR (5 M) did not alter control steady-state twitch contractions or Ca²⁺ transients at 0.5 Hz in rat, but significantly decreased them in guinea pig myocytes. When cells were Na⁺-loaded by perfusion of strophanthidin (50 M), the addition of KBR reduced diastolic [Ca²⁺]_i and abolished spontaneous Ca²⁺ oscillations. In guinea pig papillary muscles exposed to substrate-free hypoxic medium for 60 min, KBR (10 M applied 10 min before and during reoxygenation) reduced both the incidence and duration of reoxygenation-induced arrhythmias. KBR also enhanced the recovery of developed tension after reoxygenation. It is concluded that (1) the importance of Ca²⁺ influx via NCX for normal excitation-contraction coupling is species-dependent, and (2) Ca²⁺ influx via NCX may be critical in causing myocardial Ca²⁺ overload and triggered activities induced by cardiac glycoside or reoxygenation.     

Production of D-arabitol by Metschnikowia reukaufii AJ14787

A potent producer of D-arabitol was isolated by screening of natural sources and identified as Metschnikowia reukaufii AJ14787. Resting cells of this strain can efficiently produce D-arabitol from D-glucose with a weight yield of more than 60%, and can also produce D-arabitol from several other types of sugars such as polyols, ketoses, and aldoses. To improve productivity, various culture conditions such as temperature and the concentrations of D-glucose and nitrogen sources were examined. Under optimal conditions, 206 g/l of D-arabitol was produced from D-glucose with a weight yield of 52% in 100 hours.     

Molecular cloning and expression analysis of the mouse<Emphasis Type="Italic"> Spot-2</Emphasis> gene in pituitary development

Mouse Spot-1 is a DNA-binding protein with a domain (His-Thr) encoded by p(CA)n repeats. Spot-1 interacts with the nuclear localization signal (NLS) I of p53 through its His-Thr domain. In this study we describe the cloning and expression patterns of a novel gene encoding a protein containing a His-Thr domain, Spot-2. Spot-2 is exclusively expressed in the pituitary from stage E13.5 to E15.5. Mouse Lhx3 plays a critical role during early organogenesis in the pituitary. The Spot-2 gene appears to be a downstream gene of Lhx3. It is suggested that Spot-2 plays important roles in pituitary development.     

Detection of 1270 nm emission from singlet oxygen and photocytotoxic property of sugar-pendant 60 fullerenes

Sugar-pendant [60] fullerene derivatives have been prepared from carbohydrate-linked azides 1a-e. Both monosugar (4a-e) and bissugar derivatives (5a-e) produce singlet oxygen ((1)O(2)) under laser irradiation (355 nm) proved by the direct observation of (1)O(2) emission at 1270 nm. Monosugar derivatives exhibit photocytotoxicity varying by the attached sugar molecule.