Yellow Strain Research Articles

Carotenoids protectPhaffia rhodozyma against singlet oxygen damage

The only known habitat of the astaxanthin-containingPhaffia rhodozyma is in slime fluxes of deciduous trees at high altitudes. In this habitat, the function of carotenoids inP. rhodozyma is probably to provide protection against photogenerated antifungal substances in the tree flux such as singlet oxygen (1O2). To investigate the role of carotenoids inP. rhodozyma, genetic selections were employed to determine if carotenogenic yeast strains ofP. rhodozyma have enhanced ability to quench1O2. Singlet oxygen was generated in liquid culture by the interaction of visible light (λ-550 nm) with the photosensitizer rose bengal or by the activation of α-terthienyl with ultraviolet light (λ=366 nm). In each case the treatments selected for growth of pigmented strains ofP. rhodozyma. Albino (carotenoid-less) or yellow (β-carotene producing) strains grew less well in media containing1O2. Addition of the1O2 quencher sodium azide to the medium with α-terthienyl allowed growth of non-pigmented strains. Since the ecological niche ofP. rhodozyma is highly specific, we investigated whether extracts of birch trees (Betula), the original source ofP. rhodozyma, contained a compound that would select for pigmented populations of the yeast. WhenP. rhodozyma strains were exposed to ethyl acetate extracts ofBetula papyrifera excited with 366 nm ultraviolet light, only pigmented cells were able to grow. These results suggest that carotenogenesis developed inP. rhodozyma in response to the presence of photoactivatable antifungal compounds produced by the host tree.

トウモロコシおよびテオシントから分離されたキュウリモザイクウイルスについて

Cucumber mosaic virus (CMV) occurred widely in maize (Zea mays) and also rarely in teosinte (Euchlaena mexicana) in Kanto area, Japan. Isolates from maize plants were classified into two types (I and II) on their biological and serological properties. Isolate II, but not isolate I, infected to barley and wheat plants by sap inoculation. It suggested that the isolate I is closely to leguminous strain, but isolate II (tentatively named maize strain) may be a previously undescribed strain, on their host range and symptomatology. Isolates from teosinte plants appeared to be related to yellow (Y) strain on tabacco symptoms. We propose to designate teosinte necrotic mosaic for the disease.

Complete nucleotide sequence of yellow fever virus vaccine strains 17DD and 17D-213

The complete nucleotide sequence of the genome from two yellow fever (YF) virus vaccine strains, 17DD and 17D-213, has been determined. Comparison of these sequences with those of other YF viruses including the parental virulent Asibi strain allowed the identification of 48 nucleotide sequence differences which are common to all 17D substrains. This is a significant reduction from the 67 nucleotide changes originally reported as being 17D-specific and potentially related to viral attenuation. The 48 changes are scattered throughout the genome, 26 of which are silent and 22 led to amino acid substitutions. These 22 changes are bona fide candidates to test by mutating the infectious YF cDNA to investigate their role in viral attenuation.

Induction of betacyanin formation in cell cultures ofChenopodium albumunder UV-light irradiation

A cell culture of Chenopodium album was cultivated under different light conditions (UV, blue, white, red light, and darkness). Red-violet coloured betacyanincontaining cell groups were formed on the surface of the cell culture only under UV-light or UV-containing light qualities (blue and white), respectively. A direct correlation exists between UV-portions of different light qualities and the number of red-violet cell groups formed, whereas light conditions without UV-light do not induce betacyanin formation. Betacyanins formed under UV-light were degraded after transfer to red light and darkness. The phytohormone kinetin enhanced the betacyanin formation in white light, but was unable to induce betacyanins in darkness. The phytohormone 2,4-D totally inhibited the formation of betacyanins under all light conditions studied. All other investigated parameters of primary and secondary metabolism of the cells (protein content, respiration activity, concentration of carotenoids and flavonoids) only unspecifically increased in reaction to continuous UV-light irradiation. A selected yellow coloured cell strain autotroph to auxin was unable to form betacyanin under continuous UV-light irradiation and under increased kinetin concentration

Geographic Variation in Larval Survival and Growth of Five Scirpophaga incertulas (Lepidoptera: Pyralidae) Strains on Different Rice Hosts

Survival and growth was measured for five geographically distinct strains of Scirpophaga incertulas (Walker) (the yellow stem borer) reared on three wild species of rice ( Oryza nivara, O. barthii , and O. officinalis ), three traditional cultivars of O. sativa rice (‘C018’, ‘W1253’, and ‘Rexoro’), and three modern, high yielding rice ( O. sativa ) cultivars (‘IR56’, ‘IR40’, and ‘IR62’). All yellow stem borer strains showed differential survival and weight gain across the nine rice hosts. There were significant differences in mean survival of the five stem borer strains on all of the rice hosts except two wild rices, O. nivara and O. officinalis , where all five strains had similar survival. Statistically significant host-by-strain interaction in both survival and weight indicates that differences among populations of the S. incertulas were host-dependent and were most likely the result of genetic differentiation. There was some indication of similarity between geographically related stem borer strains, but this was not consistent. The importance of these findings to the development of strategies for deploying rice varieties with resistance to S. incertulas is discussed.

Linkage Analysis of a Resistance Gene to Barley Yellow Mosaic Virus Strain II in Two-rowed Barley.

わが国の二条大麦品種について大麦縞萎縮ウイルスII型系統に対する反応を調査した結果，抵抗性とエステラーゼ同位酵素遺伝子型との間に密接な関係が認められた(飯田ら 1993).そこで，大麦縞萎縮ウイルスI型系統に対する抵抗性遺伝子とエステラーゼ同位酵素遺伝子群との連鎖関係を明らかにするために，つぎのような実験を行った.すなわち，関東中生ゴールド(罹病性)×ミホゴールデン(抵抗性)及び栃木ゴールデンメロン(罹病性)XPrior(抵抗性)のF2個体のエステラーゼ同位酵素遺伝子型を調べるとともに，それらF3系統の大麦縞萎縮ウイルス皿型系統に対する反応を調査した.その結果，抵抗性は単一の遺伝子によって支配され，抵抗性遺伝子は第3染色体長腕末端部に座乗するエステラーゼ同位酵素遺伝子群Est1-Est2-Est4)と組換価10.15%と6.97%で連鎖していた.これらの組換価から，この抵抗性遺伝子は同じ第3染色体に座乗するミサトゴールデンのもつ抵抗性遺伝子とは明らかに遺伝子座を異にするものと考えられる.

キュウリモザイクウイルス（ＣＭＶ）による殻実用アマランサス（Ａｍａｒａｎｔｈｕｓ ｈｙｐｏｃｈｏｎｄｒｉａｃｕｓ Ｌ．）のモザイク病

A virus was isolated from grain amaranth (Amaranthus hypochondriacus L.) showing mosaic symptoms. The virus infected 20 plant species of 8 families, and was readily transmitted by aphid. The thermal inactivation point of the virus in crude sap was 55-60°C (10min), dilution end point 10-3-10-4, and longevity in vitro 2-4 days at 25°C. The virus was isometric about 28-30nm in diameter, and was serologically indistinguishable from a yellow strain of cucumber mosaic virus (CMV-Y). Electrophoretic patterns of dsRNA of the virus were similar to those of CMVs. Based on these results, the virus was identified as CMV.

Viability of diploid males in the parasitic wasp,Diadromus pulchellus (Hym.: Ichneumonidae)

In the HymenopteraDiadromus pulchellus diploid males have been observed in samples collected in the wild and bred in the laboratory. Using a yellow body color mutant strain, a protocol of crosses, involving inbred individuals, allows the routine production of such diploid males. These males result from the development of fertilized ova and emerge normally. Their preimaginal viability is similar to those of other individuals, and their imaginal viability does not differ from that of haploid males. Diploid males present normal external morphology and neither mosaicism nor intersexuality was observed. However, they are bigger than haploid males and have head size and wing length similar to those of females. The significance of diploid male viability in hymenopteran populations is discussed.

Comparison of the nucleotide and deduced amino acid sequences of the structural protein genes of the yellow fever 17DD vaccine strain from Senegal with those of other yellow fever vaccine viruses

The nucleic acid and deduced amino acid sequences of the structural proteins of the 17DD vaccine strain of yellow fever (YF) virus originating from Senegal are compared with those published for other vaccine strains of YF virus. Even though the 17D-204 and 17DD substrains of 17D diverged at passage 195 of 17D, they show a very high degree of nucleotide (99.5%) and amino acid (99.5%) homology over this region. The sequences are discussed with respect to monoclonal antibodies that can distinguish between 17DD and 17D-204 substrains of YF vaccines.

Relationship between Reaction to Infection with Barley Yellow Mosaic Virus Strains and Genotypes for Esterase Isozymes in Two-rowed Barley(Hordeum distichum L.) Cultivars.

The authors evaluated the reaction of the major Japanese two-rowed barley cultivars to infection with strains I, II and III of barley yellow mosaic virus (BaYMV) (Table 1). Out of 50 cultivars tested, 44, 18 and 47 cultivars were susceptible to strain I, II and III respectively (Table 2). Although almost all of the two-rowed barley cultivars were susceptible to strains I and III, many cultivars were resistant to strain II. 44 cultivars susceptible to strain I could be classified into two groups, susceptible or resistant to strain II. The old cultivars, for instance Kirin Choku 1, Tochigi Golden Melon and Golden Melon Sai 1, were susceptible to strain II, while the introduced or recently improved cultivars, for instance Prior, Svanhals, Haruna Nijo and Amagi Nijo were mainly resistant to it. It could be considered that the resistance gene(s) to strain 11 was mainly incorporated into Japanese two-rowed barley cultivars from Prior, Plumage Archer and Sapporo 7, especially Prior played an important role in the transmission of this resistance gene(s) (Fig. 1).

Effect of growth phase on the fatty acid composition of Thermus spp.

Two yellow and two red pigmented strains of Thermus were monitored for changes in fatty acid content and composition with reference to growth phase at the optimum temperature. Fatty acid content per mg of dry weight increased as the cultures aged. In addition the quantities of iso C 15:0, iso C 17:0 and iso C 16:0 increased in yellow pigmented strains, but in red pigmented strains, an increase was seen in iso C 15:0, but C 16:0 and iso C 16:0 levels decreased. Thus the fatty acid composition of these organisms varies with growth phase, and shows also strain specific variability.

Heterogeneity in envelope protein sequence and N-Linked glycosylation among yellow fever virus vaccine strains

We have compared the deduced envelope (E) protein sequences of two biologically well-characterized yellow fever (YF) virus vaccine strains. The 17DD strain has been produced in Brazil for more than 50 years and used to successfully vaccinate millions of people worldwide. The 17D-213 is a candidate vaccine strain produced in tissue culture which has previously passed the monkey neurovirulence assay for testing human YF vaccines. Nucleotide sequence analysis of polymerase chain reaction-amplified cDNA revealed a number of mutations which were strain- and substrain-specific. A major difference of 17DD and 17D-213 as compared to 17D-204 and Asibi was the existence of a potential N-linked glycosylation site located at amino acid residues 153 and 151 of 17DD and 17D-213, respectively. These acceptor sites are apparently utilized for the addition of high-mannose carbohydrate chains as shown by endoglycosidase analyses of immunoprecipitated E proteins. Glycosylated E protein is also used to assemble YF vaccine virions. This work and eventual complete nucleotide sequence analysis of both vaccine strains should help to define possible changes involved in YF virus attenuation and allow their biological importance to be determined using a recently developed system for generating YF virus from cDNA. In addition, these data provide an estimate on the extent of genetic variability among YF 17D seeds and vaccines.

Determinants of tomato golden mosaic virus symptom development located on DNA B

Infectious clones have been constructed from two strains of the bipartite geminivirus tomato golden mosaic virus. The common strain and the yellow vein strain show marked phenotypic differences in Nicotiana benthamiana which are reproduced following infection with the cloned viral genomes. Pseudorecombinants between the two strains, produced by exchange of genome components (DNAs A and B), established that the difference in symptoms in several species of the Solanaceae is determined by DNA B. Recombinants produced in vitro between the DNA B components showed that determinants of symptom development map to the common region and gene BL1. DNA B is known to carry functions necessary for spread of viral DNA through the host plant. Our results emphasize the link between symptom type and virus spread.

Molecular analysis of yellow fever virus 17DD vaccine strain

The Oswaldo Cruz Foundation produces most of the yellow fever (YF) vaccine prepared worldwide. As part of a broader approach to determine the genetic variability in YF 17D seeds and vaccines and its relevance to viral attenuation the 17DD virus was purified directly from chick embryo homogenates which is the source of virus used for vaccination of millions of people in Brazil and other countries for half a century. Neutralization and hemagglutination tests showed that the purified virus is similar to the original stock. Furthermore, radioimmune precipitation of 35S-methionine-labeled viral proteins using mouse hyperimmune ascitic fluid revealed identical patterns for the purified 17DD virus and the YF 17D-204 strain except for the 17DD E protein which migrated slower on SDS-PAGE. This difference is likely to be due to N-linked glycosylation. Finally, comparison by northern blot hybridization of virion RNAs of purified 17DD with two other strains of YF 17D virus revealed only genome-sized molecules for all three viruses. These observations suggest that the vaccine phenotype is primarily associated with the accumulation of mutations.

Interference of a Non-Seedling Yellows by a Seedling Yellows Strain of Citrus Tristeza Virus in Sweet Orange

Interference of a Non-Seedling Yellows by a Seedling Yellows Strain of Citrus Tristeza Virus in Sweet Orange

The role of extracellular products in copper colonisation

Abstract Three strains of Pseudomonas bacteria were isolated from copper water pipes showing pitting corrosion. The effects of temperature and copper concentration on growth and exopolymer production were investigated. Various differences were noted between the organisms when grown as pure cultures and as a mixed culture; from the pure culture work some of the contributions made by each organism to the mixed culture can be deduced. It would appear that the production of extracellular products varies with temperature and that polymer production and growth are enhanced in a mixed culture. All three strains grown as pure cultures showed a decrease in growth at lower temperatures as the copper concentration was increased. This effect was altered when the organisms were grown as a mixed culture. It was noted that copper tolerance was conferred on one of the organisms (a yellow strain of Ps. paucimobilis ) by the presence of the other two. These results can be used to explain some of the observations made on the colonisation of copper by bacteria associated with pipe corrosion.

Partial nucleotide sequence of South American yellow fever virus strain 1899/81: structural proteins and NS1

We have partially cloned and sequenced the genome of a Peruvian yellow fever virus isolate (1899/81) and compared the nucleotide and deduced amino acid sequences of this strain with the previously published sequence of the West African yellow fever virus strain Asibi. In the 3594 base region sequenced, which contains the structural genes (C, M, E), all but the 72 3'-terminal nucleotides of the NS1 gene and 108 nucleotides of the 5' non-coding region, 515 nucleotide substitutions were detected. Nucleotide divergence was lowest in the 5' non-coding region, 2.8%, compared with an average rate of 14.7% in the coding regions. Over 91% of the 512 nucleotide changes in the coding region were silent; 44 amino acid substitutions resulted. The capsid protein was the least conserved, whereas the M protein was the most highly conserved (6.7% and 1.3% divergence, respectively). The envelope protein had 18 amino acid changes (3.7% divergence), one of which created an additional site for potential glycosylation of the 1899/81 virus. NS1 protein divergence (3.9%) was similar to that seen in the E protein. Of the 44 amino acid substitutions found, 34 (77%) were conservative. The highest number of nonconservative differences occurred in the envelope glycoprotein. These changes may significantly affect the antigenic and biological functions of the viruses.

Polar Lipid and Fatty Acid Composition of Strains of the Genus Thermus

Summary Eighteen isolates and five reference strains of the genus Thermus were examined for polar lipid patterns and fatty acid composition. All high-temperature yellow or nonpigmented strains had a major glycolipid and a major phospholipid, and minor, slightly variable components. The red-pigmented strains, related to Thermus ruber, had two prominent glycolipids in addition to the major phospholipid. With the exception of Thermus filiformis, all strains had iso-C15 and iso-C17 fatty acids as major components, followed by lower relative proportions of the anteiso-brmched fatty acids. In contrast, anteiso-branched fatty acids were predominant in T. filiformis. Principal component analysis of the fatty acid results did not reflect the classification of the members of the genus Thermus.

Selection in Red Clover for Resistance to Northern Anthracnose

Northern anthracnose (NA), caused by Kabatiella caulivora (Kirchn.) Karak., is a destructive disease of red clover (Trifolium pratense L.) in the northern USA. The range of adaptation of southern red clover cultivars could be broadened by addition of NA resistance. A program was initiated to enhance NA resistance in 10 parental populations related to the cultivar Kenstar, and to evaluate response to phenotypic recurrent selection in these low NA‐variation susceptible populations. These populations are resistant to powdery mildew (Erisyphe polygoni DC) and bean yellow mosaic virus strain 204‐1. The 10 populations were subjected in a greenhouse to six cycles of phenotypic recurrent selection for NA resistance. Remnant seed from each cycle of selection was used to establish an evaluation study. Northern anthracnose resistance was significantly improved. Mean disease severity index (DSI) was reduced by 36% through six cycles and was linear across cycles. However, populations were variable in their response to selection. Selection improved DSI by less than 24% through six cycles in four of the populations, while average improvement of the other six was 46%. Realized heritabilities averaged 20% per cycle and were greatest among the six populations with greatest improvement in DSI Inbreeding was minimal during the selection process, averaging 2.8% after six cycles. The resistance obtained from these low‐variation susceptible populations indicates that phenotypic recurrent selection is an effective means of uncovering latent variation for resistance to NA.

Resistance to Beet Western Yellows Virus Among Forage Brassicas

Fourteen forage Brassica cultivars representing four species were evaluated for resistance to beet western yellows virus (BWYV), potato leafroll virus (PLRV), and the tomato yellow top strain of PLRV (PLRV-TY) under field exposure. Incidence of field infection with BWYV ranged in several susceptibility classes from less than 2 to 100%. The four most susceptible cultivars were all turnips. The four most resistant cultivars included one each of the four Brassica species. All four species were represented among the intermediately susceptible cultivars. Once infection was achieved, there was little or no difference among the cultivars in resistance to systemic virus accumulation. Symptoms of BWYV were mild. Neither strain of PLRV was detected by ELISA or aphid transmission. There was no correlation between numbers of aphids on plants in the fall and susceptibility to infection. All Brassica cultivars survived winters, but neither live aphids (Myzus persicae) nor aphid eggs were found on plants at the end of winter.