Occurrence of the lutein-epoxide cycle in mistletoes of the Loranthaceae and Viscaceae

The lutein-epoxide cycle (Lx cycle) is an auxiliary xanthophyll cycle known to operate only in some higher-plant species. It occurs in parallel with the common violaxanthin cycle (V cycle) and involves the same epoxidation and de-epoxidation reactions as in the V cycle. In this study, the occurrence of the Lx cycle was investigated in the two major families of mistletoe, the Loranthaceae and the Viscaceae. In an attempt to find the limiting factor(s) for the occurrence of the Lx cycle, pigment profiles of mistletoes with and without the Lx cycle were compared. The availability of lutein as a substrate for the zeaxanthin epoxidase appeared not to be critical. This was supported by the absence of the Lx cycle in the transgenic Arabidopsis plant lutOE, in which synthesis of lutein was increased at the expense of V by overexpression of -cyclase, a key enzyme for lutein synthesis. Furthermore, analysis of pigment distribution within the mistletoe thylakoids excluded the possibility of different localizations for the Lx- and V-cycle pigments. From these findings, together with previous reports on the substrate specificity of the two enzymes in the V cycle, we propose that mutation to zeaxanthin epoxidase could have resulted in altered regulation and/or substrate specificity of the enzyme that gave rise to the parallel operation of two xanthophyll cycles in some plants. The distribution pattern of Lx in the mistletoe phylogeny inferred from 18S rRNA gene sequences also suggested that the occurrence of the Lx cycle is determined genetically. Possible molecular evolutionary processes that may have led to the operation of the Lx cycle in some mistletoes are discussed.Abbreviations A antheraxanthin - - and -Car - and -carotene - Chl chlorophyll - -DM dodecyl--d-maltoside - DPS de-epoxidation state of the violaxanthin cycle (= [A+Z]/[V+A+Z]) - Lut lutein - Lx lutein epoxide - Caro total carotenoid concentration - V violaxanthin - VAZ pool size of the violaxanthin cycle (= V+A+Z) - VDE violaxanthin de-epoxidase - Z zeaxanthin - ZE zeaxanthin epoxidase     

A mutant receptor tyrosine phosphatase,CD148, causes defects in vascular development

Vascularization defects in genetic recombinant mice have defined critical roles for a number of specific receptor tyrosine kinases. Here we evaluated whether an endothelium-expressed receptor tyrosine phosphatase, CD148 (DEP-1/PTPeta), participates in developmental vascularization. A mutant allele, CD148(DeltaCyGFP), was constructed to eliminate CD148 phosphatase activity by in-frame replacement of cytoplasmic sequences with enhanced green fluorescent protein sequences. Homozygous mutant mice died at midgestation, before embryonic day 11.5 (E11.5), with vascularization failure marked by growth retardation and disorganized vascular structures. Structural abnormalities were observed as early as E8.25 in the yolk sac, prior to the appearance of intraembryonic defects. Homozygous mutant mice displayed enlarged vessels comprised of endothelial cells expressing markers of early differentiation, including VEGFR2 (Flk1), Tal1/SCL, CD31, ephrin-B2, and Tie2, with notable lack of endoglin expression. Increased endothelial cell numbers and mitotic activity indices were demonstrated. At E9.5, homozygous mutant embryos showed homogeneously enlarged primitive vessels defective in vascular remodeling and branching, with impaired pericyte investment adjacent to endothelial structures, in similarity to endoglin-deficient embryos. Developing cardiac tissues showed expanded endocardial projections accompanied by defective endocardial cushion formation. These findings implicate a member of the receptor tyrosine phosphatase family, CD148, in developmental vascular organization and provide evidence that it regulates endothelial proliferation and endothelium-pericyte interactions.     

Aging specifically impairs amnesiac-dependent memory in Drosophila

Age-related memory impairment (AMI) is observed in many species. However, it is uncertain whether AMI results from a specific or a nonspecific decay in memory processing. In Drosophila, memory acquired after a single olfactory conditioning paradigm has three distinct phases: short-term memory (STM), middle-term memory (MTM), and longer-lasting anesthesia-resistant memory (ARM). Here, we demonstrate that age-related defects in olfactory memory are identical to those of the MTM mutant amnesiac (amn). Furthermore, amn flies do not exhibit an age-dependent decrease in memory, in contrast to other memory mutants. The absence of AMI in amn flies is restored by expression of an amn transgene predominantly in DPM cells. Thus, we propose that AMI in flies results from a specific decrease in amn-dependent MTM.     

Feeding stimulants eliciting the probing behavior for Peregrinator blannulipes Montrouzier et Signore (Hemiptera: Ruduviidae) from Tribolium confusum (Jacquelin du Val)

Four fatty acid methyl esters identified in the solvent extract of Tribolium confusum (Jacquelin du Val) larvae as kairomones were individually and collectively tested for probing behavior of Peregrinator biannulipes Montrouzier et Signoret. All identified fatty acid methyl eaters, methyl palmitate, methyl linolate, methyl oleate and methyl stearate, exhibited characterisitic kairomonal probing behavior of P. biannulipe toward the lure. These fatty acid methyl ester were active at 0.2 microg/lure but a synergistic effect was not observed among them. Commercially available C8-C14 even-numbered fatty acid methyl esters that were not detected in the extract of T. confusum larvae also elicited a probing behavior but their activities were weaker than those of four fatty acid methyl ester (C16:0, C18:0, C18:1 and C18:2) identified in the extract. On the other hand, C17 and C19 odd-numbered fatty acid methyl esters did not show any activity at all.     

Steroid sulfatase and estrogen sulfotransferase in normal human tissue and breast carcinoma

Steroid sulfatase (STS) hydrolyzes inactive estrone sulfate (E1-S) to estrone (E1), while estrogen sulfotransferase (EST; SULT 1E1 or STE gene) sulfonates estrogens to estrogen sulfates. They are considered to play important roles in the regulation of local estrogenic actions in various human tissues, however, their biological significance remains largely unknown. Therefore, we examined the expression of STS and EST in non-pathologic human tissues and breast carcinomas. STS expression was very weak except for the placenta, while EST expression was markedly detected in various tissues examined. In breast carcinoma tissues, STS and EST immunoreactivity was detected in carcinoma cells in 74 and 44% of cases, respectively, and was significantly associated with their mRNA levels and enzymatic activities. STS immunoreactivity was significantly correlated with the tumor size, and an increased risk of recurrence. EST immunoreactivity was inversely correlated with the tumor size or lymph node status. Moreover, EST immunoreactivity was significantly associated with a decreased risk of recurrence or improved prognosis. Our results suggest that EST is involved in protecting various peripheral tissues from excessive estrogenic effects. In the breast carcinoma, STS and EST are suggested to play important roles in the regulation of in situ estrogen production in the breast carcinomas.     

Functional analysis of the 37 kDa inner envelope membrane polypeptide in chloroplast biogenesis using a Ds-tagged Arabidopsis pale-green mutant

To study the functions of the nuclear genes involved in chloroplast development, we systematically analyzed albino and pale-green Arabidopsis thaliana mutants by using a two-component transposon system based on the Ac/Ds element of maize as a mutagen. One of the pale-green mutants, albino or pale green mutant 1 (designated as apg1), did not survive beyond the seedling stage, when germinated on soil. The chloroplasts of the apg1 plants contained decreased numbers of lamellae with reduced levels of chlorophyll. A gene encoding a 37 kDa polypeptide precursor of the chloroplast inner envelope membrane was disrupted by insertion of the Ds transposon in apg1. The 37 kDa protein had partial sequence similarity to the S-adenosylmethionine-dependent methyltransferase. The apg1 plants lacked plastoquinone (PQ), suggesting that the APG1 protein is involved in the methylation step of PQ biosynthesis, which is localized at the envelope membrane. Our results demonstrate the importance of the 37 kDa protein of the chloroplast inner envelope membrane for chloroplast development in Arabidopsis.     

Effect of difructose anhydride III on calcium absorption in humans

The effects of difructose anhydride III (DFAIII) on stimulating calcium absorption was investigated in humans. We studied changes in the time-course of characteristics urinary calcium excretion in 12 healthy men given 0.3, 1.0 or 3.0 g of DFAIII and 300 mg of calcium as calcium carbonate. In addition, urinary excretion and urine concentrations of creatinine and deoxypyridinoline were determined. Urine calcium excretion every 2 hours after the intake were higher over than that of the control subjects. The total amount of urinary calcium excretion for 10 hours was significantly greates in the subjects given 1.0 g or 3.0 g of DFAIII than that of the control subjects. However, there were no differences in the urine concentrations of creatinine and deoxypyridinoline between the subjects given DFAIII and the control subjects. These findings suggests that low dose of DFAIII had a stimulating effect on calcium absorption in humans.     

Revision of the structure of the major aggregation pheromone of the broad-horned flour beetle (Gnatocerus cornutus) to (1S,4R,5R)-alpha-acoradiene by its synthesis

(1S,4R,5R)-(+)-alpha-acoradiene [1,8-dimethyl-4-(1-methylethenyl)spiro[4.5]dec-7-ene] (1) is shown by its synthesis to be the major component of the male-produced aggregation pheromone of the broad-horned flour beetle (Gnatocerus cornutus).     

Expressions of adrenomedullin mRNA and protein in rats with hypobaric hypoxia-induced pulmonary hypertension

Experimental pulmonary hypertension induced in a hypobaric hypoxic environment (HHE) is characterized by structural remodeling of the heart and pulmonary arteries. Adrenomedullin (AM) has diuretic, natriuretic, and hypotensive effects. To study the possible effects of HHE on the AM synthesis system, 150 male Wistar rats were housed in a chamber at the equivalent of a 5,500-m altitude level for 21 days. After 14 days of exposure to HHE, pulmonary arterial pressure (PAP) was significantly increased (compared with control rats). The plasma AM protein level was significantly increased on day 21 of exposure to HHE. In the right ventricle (RV), right atrium, and left atrium of the heart, the expressions of AM mRNA and protein were increased in the middle to late phase (5-21 days) of HHE, whereas in the brain and lung they were increased much earlier (0.5-5 days). In situ hybridization and immunohistochemistry showed AM mRNA and protein staining to be more intense in the RV in animals in the middle to late phase of HHE exposure than in the controls. During HHE, these changes in AM synthesis, which occurred strongly in the RV, occurred alongside the increase in PAP. Conceivably, AM may play a role in modulating pulmonary hypertension in HHE.