Seasonal changes in the biomass of floating leaved plant,Trapa spp., and its relation with a leaf beetle,Galerucella nipponensis,in Lake Inba,Japan

Limnology - Trapa spp. dominate many shallow eutrophic lakes in Japan, which must affect the nutrient dynamics in lakes. Trapa spp. are utilized by several animals, in particular the leaf beetle,...     

Calcium concentration in brains from multiple sclerosis patients

Calcium (Ca) concentrations were studied in the central nervous system (CNS) of four patients with definite multiple sclerosis (MS, average age 49 yr) and five controls (average age 68 yr). The Ca concentration was determined by neutron activation analysis in autopsy samples taken from the 26 subanatomical regions of CNS tissues. Although the mean Ca concentration in the 26 CNS regions combined was higher in the four MS patients than in the controls, the content of white matter was lower. Whether or not this significantly lower Ca concentration found in the white matter of MS patients plays an important role in the demyelinating process remains unclear, although that lower concentration seems not be age dependent, but MS specific.     

Coevolution and Hierarchical Interactions of Tomato mosaic virus and the Resistance Gene Tm-1

During antagonistic coevolution between viruses and their hosts, viruses have a major advantage by evolving more rapidly. Nevertheless, viruses and their hosts coexist and have coevolved, although the processes remain largely unknown. We previously identified Tm-1 that confers resistance to Tomato mosaic virus (ToMV), and revealed that it encodes a protein that binds ToMV replication proteins and inhibits RNA replication. Tm-1 was introgressed from a wild tomato species Solanum habrochaites into the cultivated tomato species Solanum lycopersicum. In this study, we analyzed Tm-1 alleles in S. habrochaites. Although most part of this gene was under purifying selection, a cluster of nonsynonymous substitutions in a small region important for inhibitory activity was identified, suggesting that the region is under positive selection. We then examined the resistance of S. habrochaites plants to ToMV. Approximately 60% of 149 individuals from 24 accessions were resistant to ToMV, while the others accumulated detectable levels of coat protein after inoculation. Unexpectedly, many S. habrochaites plants were observed in which even multiplication of the Tm-1-resistance-breaking ToMV mutant LT1 was inhibited. An amino acid change in the positively selected region of the Tm-1 protein was responsible for the inhibition of LT1 multiplication. This amino acid change allowed Tm-1 to bind LT1 replication proteins without losing the ability to bind replication proteins of wild-type ToMV. The antiviral spectra and biochemical properties suggest that Tm-1 has evolved by changing the strengths of its inhibitory activity rather than diversifying the recognition spectra. In the LT1-resistant S. habrochaites plants inoculated with LT1, mutant viruses emerged whose multiplication was not inhibited by the Tm-1 allele that confers resistance to LT1. However, the resistance-breaking mutants were less competitive than the parental strains in the absence of Tm-1. Based on these results, we discuss possible coevolutionary processes of ToMV and Tm-1.     

Changes in Targeting Efficiencies of Proteins to Plant Microbodies Caused by Amino Acid Substitutions in the Carboxy-terminal Tripeptide

It has been demonstrated that the carboxyl terminus of microbodyenzymes functions as a targeting signal to microbodies in higherplants. We have examined an ability of 24 carboxy-terminal aminoacid sequences to facilitate the transport of a cytosolic passengerprotein, ß-glucuroni-dase, into microbodies in greencotyledonary cells of trans-genic Arabidopsis. Immunoelectronmicroscopic analysis revealed that carboxy-terminal tripeptidesequences of the form [C/A/S/P]-[K/R]-[I/L/M] function as amicrobody-targeting signal, although tripeptides with prolineat the first amino acid position and isoleucine at the carboxylterminus show weak targeting efficiencies. All known micro-bodyenzymes that are synthesized in a form similar in size to themature molecule, except catalase, contain one of these tripeptidesequences at their carboxyl terminus. (Received April 14, 1997; Accepted April 8, 1997)     

Physico-chemical control of the growth of a diatom, Asterionella formosa Hass., in a shallow eutrophic lake

Physico-chemical environmental control of the growth rate ofan algal population, the pennate diatom Asterionella formasaHass., was investigated for a year in natural water. This speciesoccurred in vegetative form in the water column all the time,although its population density varied by five orders of magnitudefrom a maximum of 1.4?10⁶ cells l^–1 in February to a minimumof 0.8?10¹ cells l^–1 in August. A mathematical model ofa combination of multiplicative and Liebig types suggested thatvegetative cells were severely limited in their growth rate,reaching almost 80% depression of the maximum rate between Decemberand February by low temperatures and nearly 50% depression inwarm seasons by light intensity. Nutrient limitations were onlyobserved in May, August and September, although they were notas great as by temperature and light intensity in the studylake. Population changing rates of A.formosa determined in thelake were low and agreed well with the estimated growth ratesduring winter, but those in summer were low and disagreed withthe estimated high growth rates. This suggests that populationchange of the species was highly dependent upon the specificgrowth rate in winter, but other factors became predominantin summer.     

Evolutionarily Conserved Interaction between the Phosphoproteins and X Proteins of Bornaviruses from Different Vertebrate Species

Bornavirus, a non-segmented, negative-strand RNA viruses, is currently classified into several genetically distinct genotypes, such as Borna disease virus (BDV) and avian bornaviruses (ABVs). Recent studies revealed that bornavirus genotypes show unique sequence variability in the putative 5′ untranslated region (5′ UTR) of X/P mRNA, a bicistronic mRNA for the X protein and phosphoprotein (P). In this study, to understand the evolutionary relationship among the bornavirus genotypes, we investigated the functional interaction between the X and P proteins of four bornavirus genotypes, BDV, ABV genotype 4 and 5 and reptile bornavirus (RBV), the putative 5′ UTRs of which exhibit variation in the length. Immunofluorescence and immunoprecipitation analyses using mammalian and avian cell lines revealed that the X proteins of bornaviruses conserve the ability to facilitate the export of P from the nucleus to the cytoplasm via interaction with P. Furthermore, we showed that inter-genotypic interactions may occur between X and P among the genotypes, except for X of RBV. In addition, a BDV minireplicon assay demonstrated that the X and P proteins of ABVs, but not RBV, can affect the polymerase activity of BDV. This study demonstrates that bornaviruses may have conserved the fundamental function of a regulatory protein during their evolution, whereas RBV has evolved distinctly from the other bornavirus genotypes.     

Behavioral characteristics of old female Japanese monkeys in a free-ranging group

Fourteen female Japanese monkeys of the Arashiyama-B group ranging in age from 11 to 29 years were observed to elucidate the behavioral characteristics of aging monkeys. A positive significant correlation was found between the occurrences of rest and age, and a negative significant correlation between the occurrences of auto-grooming and age. Younger female monkeys tended to be in contact with or in proximity to group members, while older female monkeys tended to spend much more time alone. As for the grooming interactions, younger female monkeys more often groomed others than did older female monkeys. Also, the former engaged in grooming more frequently than in being groomed, while the latter spent more time in being groomed than in grooming. The old female monkeys showed no marked decline in rank, but some of them were surpassed by their adult daughters.     

Investigation of phospholipase-lipid interactions by optical detection of triplet state magnetic resonance spectroscopy

We have investigated the binding of porcine pancreatic phospholipase A2 (PA2) to n-hexadecylphosphocholine (C16PN) micelles using optical detection of triplet state magnetic resonance (ODMR) spectroscopy. The zero field splittings (zfs) of the single Trp3 residue undergo significant changes upon binding of PA2 to C16PN micelles. Zfs titrations of PA2 vs C16PN indicate that the binding stoichiometry is C16PN:PA2 approximately 25. A reduction of the (E) parameter from 1.227 to 1.135 GHz is postulated to result from Stark effects caused by the binding of a polar group (possibly phosphocholine) near Trp3 in the PA2-C16PN micelle complex.