Life table analysis of the green rice leafhopper,Nephotettix virescens (distant) (Hemiptera: Cicadellidae), and efficient vector of rice tungro disease in asynchronous rice fields in Indonesia

Population dynamics of Nephotettix virescens was studied in 17 paddy fields transplanted at intervals of about 1 month in 1988–1990. The adult density was highest either in the immigrant or the 1st generation and sharply decreased to the 2nd generation. The survival rate of the 1st generation was lowest in the transition season when areal population density increased. Key factor analysis revealed that the nymphal and adult mortality of the 1st generation (kn) was the principal source of population fluctuations. No significant correaltion was found between kn and natural enemy density, natural enemy density/healthy egg density, or the precipitation during the nymphal period. On these bases adult emigration was suspected to be the key factor. Areal population build-up of N. virescens in the transition season was considered to occur as a result of increasing immigration to young stages of rice.     

Improved regeneration response of creeping bentgrass and japonica rice by maltose and lactose

The effect of alternative carbohydrate sources to sucrose for plant regeneration from long-term cell cultures of creeping bentgrass (Agrostis palustris Huds.cv.Penncross) and japonica rice (Oryza sativa L.cv.Nipponbare) was studied. Both maltose and lactose supported a higher degree of regeneration compared to sucrose; in 8-and 19-month-old cultures of creeping bentgrass, the frequencies of regenerating calli remained at 76–93% and the numbers of plants regenerated were 8 to 36-fold higher. In 35-month-old cultures of japonica rice, 2–4% of the calli were capable of regeneration on maltose and lactose media. These results indicate that loss of plant regeneration in long-term cultures is caused, at least in part, by specific cultural conditions and not by genetic changes.     

Photosynthetic Adaptation to Salt Stress in Three-Color Leaves of a C4 Plant Amaranthus tricolor

We examined the photosynthetic adaptation mechanisms for saltstress in Amaranthus tricolor, which has leaves with green,yellow and red regions, in relation to the accumulation of glycinebetaineas osmoprotectants. The content of Chl, especially of Chl bin the red and yellow regions was 3{small tilde}4% of that inthe green region. The levels of Chl proteins such as LHCII,PSI and PSII were significantly lower than those in the greenregion. However, the contents of other photosynthetic proteinsin these regions seem to be relatively high. We observed thenet photosynthetic CO₂ fixation activity in the red and yellowregions which was about 40% of that in the green region. Uponsalt stress (0.3 M NaCl) for 5 d the levels of Chl, PSI, PSII,ribulose 1,5-bis phosphate carboxygenase and oxygenase, andthe CO₂ fixation rate in the green region decreased by about20{small tilde}35% whereas those in the non-green regions remainedalmost at the same levels. A. tricolor was found to accumulatesglycinebetaine, betainealdehyde dehydrogenase and choline monooxygenaseat similar levels in all three color regions and their contentsincreased upon salt stress. These results suggest that the lowcapacity of light harvesting in non-green regions would be favorof salt stress since the photosynthetic components in theseregions were retained at relatively high levels under high salinity. (Received February 9, 1999; Accepted April 16, 1999)     

Purification and sequence identification of anserinase

Anserinase (Xaa-methyl-His dipeptidase, EC 3.4.13.5) is a dipeptidase that mainly catalyzes the hydrolysis of Nalpha-acetylhistidine in the brain, retina and vitreous body of all poikilothermic vertebrates. The gene encoding anserinase has not been previously identified. We report the molecular identification of anserinase, purified from brain of Nile tilapia Oreochromis niloticus. The determination of the N-terminal sequence of the purified anserinase allowed the design of primers permitting the corresponding cDNA to be cloned by PCR. The anserinase cDNA has an ORF of 1485 nucleotides and encodes a signal peptide of 18 amino acids and a mature protein of 476 amino acids with a predicted molecular mass of 53.3 kDa. Sequence analysis showed that anserinase is a member of the M20A metallopeptidase subfamily in MEROPS peptidase database, to which 'serum' carnosinase (EC 3.4.13.20) and cytosolic nonspecific dipeptidase (EC 3.4.13.18, CNDP) belong. A cDNA encoding CNDP-like protein was also isolated from tilapia brain. Whereas anserinase mRNA was detected only in brain, retina, kidney and skeletal muscle, CNDP-like protein mRNA was detected in all tissues examined.     

Synthesis of angiogenesis-targeted peptide and hydrophobized polyethylene glycol conjugate

For the purpose of cancer antineovascular therapy, a novel angiogenesis-targeted peptide, Ala-Pro-Arg-Pro-Gly, (APRPG) was attached to hydrophobized polyethylene glycol (distearoylphosphatidylethanolamine [DSPE]-PEG). DSPE-PEG and the 5-mer peptide were condensed with DCC-HOBt method. Liposome modified with this DSPE-PEG-APRPG conjugate highly accumulated in tumor of tumor-bearing mice.     

Structurally simplified macrolactone analogues of halichondrin B

A structurally simplified macrolactone analogue of halichondrin B was identified that retains the potent cell growth inhibitory activity of the natural product in vitro.     

Macrocyclic ketone analogues of halichondrin B

Structurally simplified macrocyclic ketone analogues of halichondrin B were prepared by total synthesis and found to retain the potent cell growth inhibitory activity in vitro, stability in mouse serum, and in vivo efficacy of the natural product.