Competition between inoculum strains ofRhizobium japonicum in the process of soybean nodulation during three planting periods

Competition between inoculum strains ofRhizobium japonicum D 216 and 311 B applied to soybean seeds in mixed inocula depended, especially in the year of inoculation, directly on the ratio of the cell numbers of the two inoculum strains in mixtures. Uninoculated plants grown in original soil contaminated in August 1969 by inoculated seed and stored subsequently in original pots without watering for 8 months displayed, after the spring (May) and summer (August) sowing in 1970, a statistically significant nodulation shift in favour of the D 216 strain. The highest nodulatiou was achieved with all inoculation treatments during spring sowing in 1970.     

Angiogenesis and capillary maturation phenotypes associated with the Edpm3 locus on rat chromosome 3

The quantitative trait locus (QTL) Edpm3 is one of a group of additively acting QTL \responsible for the difference in estrogen-induced pituitary tumor growth between the tumor-susceptible F344 and tumor-resistant BN rat strains. The F344.BN-Edpm3^BN rat strain was produced by moving the segment of rat Chr 3 between D3Mgh7 and D3Mgh13, which contains the Edpm3 QTL, from the BN strain into the F344 genetic background. In a previous study, we used this congenic line to find that the BN allele of the Edpm3 QTL reduces tissue mass and S-phase fraction in the estrogen-induced rat pituitary tumor. We now report on the use of this congenic line to investigate the linkage of Edpm3 to tumor angiogenesis. Contrary to expectation, the F344.BN-Edpm3^BN strain has significantly greater angiogenic activity than does F344 in both treated and untreated rats. Microvessel count (MVC), perivascular space, and number of nonattached pericytes/pericapillary fibroblasts are all elevated in the pituitary by chronic estrogen treatment and their values are significantly greater in F344.BN-Edpm3^BN than F344. Thus, although there is greater angiogenic activity in the pituitary of estrogen-treated F344.BN-Edpm3^BN rats, there is a deficiency in capillary maturation compared with F344.     

Strong and weak immune responses across the same major histocompatibility barrier in rats

Inbred rat strains, Fischer 344 (F-344) and Lewis (LEW), share the serologicalAg-Bl allele and react very weakly in mixed lymphocyte culture (MLC). Despite this apparent identity atAg-B, these strains differ markedly in their immune responses to anAg-B disparate third strain Marshall 520 (M-520) (Ag-B6). F-344 recipients allowed M-520 heart grafts an extended survival, whereas LEW recipients rejected them rapidly. F-344 and M-520 showed a weak response in MLC in contrast to a strong response for LEW and M-520. F-344 produced antisera in response to injection of M-520 cells that had a relatively high antibody titer but low cytotoxic activity. F-344 responded to another strain, Buffalo (BUF) (alsoAg-B6), in a similar fashion. F-344 apparently can produce a strong allogeneic response, as it was able to rapidly reject heart grafts from (LEW x Brown-Norway) F₁ donors (LBN) (Ag-B 1/3). The low response of F-344 to M-520 probably was not due to shared antigens between the two strains because M-520 heart grafts underwent rapid rejection in LEW hosts highly tolerant to F-344. To explain the contrasting response of F-344 and LEW to theAg-B6 disparity, we propose that it is controlled by an immune-response gene(s); that F-344 has a low-responding allele and LEW has a high-responding allele. The data do not reveal a location for this proposed gene. The high-responding allele appears to be dominant, as M-520 hearts were rejected rapidly by (F-344 x LEW) F₁ recipients.     

Comparison of Fat Storage between Fischer 344 and Obesity‐Resistant Lou/C Rats Fed Different Diets**

Objective: We aimed to characterize further the Lou/C (LOU) and Fischer 344 (F344) rat strains for nutritional traits to validate their use as contrasting strains for molecular genetic studies. Research Methods and Procedures: Five batches of LOU and F344 rats were used to measure caloric intake, weight gain, and body composition when fed a chow diet, a self‐selection diet (together with the study of preferences for macronutrients), hypercaloric diets, and a chow diet in a cold environment. Results: Despite a higher caloric intake when fed a chow diet, LOU rats showed a lower weight gain, final body weight, and percentage of fat tissue, together with a higher percentage of carcass weight, than F344 rats. When fed a self‐selection diet, LOU males ingested less protein and more fat than F344 males, and the reverse was observed for females. In this condition, feed efficiency was reduced in LOU but increased in F344 rats compared with the chow diet. Diet‐induced obesity was observed in F344 rats but not in LOU rats fed hypercaloric diets. In a cold environment, both LOU and F344 rats displayed an increased percentage of brown adipose tissue compared with control groups, together with a higher caloric intake. Discussion: The study shows robust nutritional differences between the LOU rat, a lean strain with a low feed efficiency and resistant to diet‐induced obesity, and the contrasting F344 rat strain. It also shows the interest in these strains for studying the genetic components of resistance to obesity.     

Effect of the VAM fungus Glomus sp. on the growth and yield of soybean inoculated with Bradyrhizobium japonicum

The effect of two Bradyrhizobium japonicum strains (D344 and Urbana), on the frequency and intensity of infection by a VAM fungal Glomus sp. and the effect of VAM on biomass production by nodulating plants were tested in soybean growing in a soil containing low levels of accessible P and N. During the initial stage of vegetative growth, mycorrhiza frequency in roots inoculated with the two rhizobial strains did not differ. However, during flowering it was 178% higher in roots with the strain D344 than in the presence of the strain Ubrana. At final harvest (green pods) the VAM frequency did not differ in the presence of either strain. VAM positively affected biomass production, foliar concentrations of P, Zn and Cu, and number and dry matter yield of pods, but did not increase concentrations of total N and K. In nonmycorrhizal plants total nitrogenase activity (not nodule mass) and growth were higher with the rhizobial strain Urbana. The greatest nitrogenase activity, growth and yield occurred in the presence of the VAM fungus, and did not differ for plants with different strains of rhizobia.     

Ethane oxidation by methane-oxidizing bacteria

The relationship between the rates of methane and ethane oxidation by washed suspensions of methane-oxidizing bacteria has been investigated. Considerable differences between bacterial strains were observed. Two closely related Methylomonas strains which differed in their oxidizing capacity were further investigated. The low ethane oxidation rate of one strain could be strongly stimulated by the addition of oxidizable co-substrates, and the presence of ethane stimulated formate oxidation. The other strain had a much higher ethane oxidation rate and stimulation by co-substrates was negligible.Differences between the levels of dissimilative enzymes in cell-free extracts could not be detected. Attempts to produce extracts with methane mono-oxygenase activity failed. When cells were made permeable with chitosan the results suggested that strains with a low ethane oxidizing capacity obtain the required reductant for the mono-oxygenase from endogenous respiration. In strains with a high ethane oxidation rate, the reductant appears to be derived from oxidation of ethanol or acetaldehyde.     

Selection of a Photosynthetic Bacterium Suitable for Hydrogen Production in Outdoor Cultures among Strains Isolated in the Seoul,Taegu, Sendai and Bangkok Areas

Very efficient hydrogen producing photosynthetic bacteria, strains SL1, SL3, SL16 and TG28 newly isolated in Korea, and strain KM113 newly isolated in the Sendai area, were found to be Rhodopseudomonas spp. To examine the stability of cell suspensions of the cultures for hydrogen production, which is closely associated with light absorption, we conducted larger scale cultures under periodic illumination (12-hr intervals) without stirring at 30°C using strains SL1 and Rhodopseudomonas sphaeroides B5, the latter was isolated in the Bangkok area. Both strains gave homogeneous cell suspensions throughout the incubation period and larger amounts of hydrogen were produced in a shorter period of time by both cultures than obtained with Rhodopseudomonas sp. TN3, an isolate from the Sendai area which was reported previously. With the cells of the new isolates and strains TN3 and B5 grown on glutamate-malate medium at 30°C, we measured hydrogen production at 20, 30 and 40°C in the same medium. Among them, strains SL1, SL16 and KM113 showed the highest hydrogen production activity at 30°C. The maximum hydrogen production rates with these strains were over 130 µ1/hr/mg dry cells, but at 40°C, the highest activity (138 µl/hr/mg dry cells) was obtained with strain B5. Since strain B5 also showed good activities at 20 and 30°C, we suggest that this strain might be suitable for hydrogen production in outdoor cultures.     

Characterization of a new Agrobacterium tumefaciens strain from alfalfa (Medicago sativa L.)

Agrobacterium tumefaciens strain 1D1609 is reported here as the first field isolate from alfalfa (Medicago sativa L.). Unlike well-characterized A. tumefaciens strains such as C58 and Ach5, strain 1D1609 is highly virulent on alfalfa and has a distinctive host range. Interestingly, strain 1D1609 is naturally resistant to kanamycin and spectinomycin. The Ti plasmid in strain 1D1609 is an octopine-type; thus, tumors formed by strain 1D1609 synthesize octopine, which is utilized by the bacterium as a sole carbon source. Reciprocal exchange of Ti plasmids between strains 1D1609 and C58 showed that both chromosomal and Ti plasmid genes in strain 1D1609 contribute specifically to tumor formation on alfalfa. In addition, the nondormant CUF101 alfalfa cultivar from which strain 1D1609 was isolated was significantly more susceptible to all Agrobacterium strains tested than was the dormant Agate cultivar. Received: 17 October 1997 / Accepted: 8 December 1997     

The LEXF: A new set of rat recombinant inbred strains between LE/Stm and F344

A new set of rat RI strains consisting of 11 independent strains and 13 of their substrains was established by inbreeding F₂ rats between F344/DuCrj and LE/Stm. The strain distribution pattern was examined for 66 microsatellite loci, 8 biochemical genetic markers, 2 histocompatibility loci, and 2 coat color genes. A rat salivary protein gene Spe1 was newly mapped on Chr 1. Received: 13 August 1996 / Accepted: 23 December 1996     

Effects of dietary protein:carbohydrate balance on life-history traits in six laboratory strains of Drosophila melanogaster

Drosophila melanogaster Meigen (Diptera: Drosophilidae) is a key model insect for studying life span and aging. Many laboratory strains of D. melanogaster are currently used by laboratories worldwide, but they are known to vary considerably in their physiology, behavior, and life histories. Although the importance of dietary protein:carbohydrate (P:C) balance as a predominant determinant of life span and other life-history traits has been highlighted in recent research, it remains unexplored whether the impacts of P:C balance on these fitness-related traits vary in a strain-specific manner in D. melanogaster. In this study, we compared the life-history consequences (life span, egg production rate, pre-adult survival, development time, and body mass at eclosion) of six laboratory strains of D. melanogaster (w1118, yw, Oregon-R, white Canton-S, Canton-S-SNU, and Canton-S-Inha) allocated to one of four synthetic diets differing in P:C ratio (1:16, 1:4, 1:1, or 4:1). The effects of dietary P:C balance on various adult and larval life-history traits were qualitatively similar across all strains studied in this study. Regardless of fly strain, adults exhibited a shortened life span and improved egg production on a diet with the highest P:C ratio of 4:1. In all strains, larvae raised on a diet comprising the lowest P:C ratio of 1:16 suffered high mortality, delayed development time, and reduced body mass. Despite the general similarity in the direction of the effect of P:C balance across strains, fly strains differed in the magnitude of their life-history responses to dietary P:C balance, as indicated by a significant interaction between fly strain and dietary P:C ratio for all measured traits except body mass at eclosion. Possible mechanisms explaining such strain-specific responses are discussed.     

Torulaspora indica a novel yeast species isolated from coal mine soils

Four yeast strains (APSS 805, APSS 806, APSS 815 and AP-18) belonging to a novel Torulaspora species were isolated from coal mine soils of Singareni in Andhra Pradesh state, India. Another strain (PBA-22) was isolated from agricultural field soil from Gujarat state, India. The vegetative cells of all these strains were round, haploid and produced asci by conjugation between independent cells or mother cell and bud, with rough ascospores, suggesting their possible relation to ascomycetous yeast genus Torulaspora. Phylogenetic analysis of the D1/D2 domain of the large subunit (LSU) rRNA gene and Internal Transcribed Spacer (ITS) regions revealed that, among the five strains, three viz. APSS 805, APSS 806 and APSS 815 have identical sequences. The other two strains (AP-18 and PBA-22) differed from the other three strains in less than 1% nucleotide substitutions in the combined D1/D2 domain and ITS sequences, indicating that all of them (five strains) may belong to the same species. These five strains were closely related to Torulaspora globosa, but showed more than 3–7% sequence divergence from T. globosa and all other species in the genus Torulaspora in the combined sequence analysis of D1/D2 domain and ITS region of rRNA gene. In addition, these strains also showed distinct microsatellite finger-printing pattern from related species and differed in several physiological responses suggesting that these strains belong to a novel species of Torulaspora. We propose to name these strains as Torulaspora indica sp. nov., and designate APSS 805^T = MTCC 9772 ^T = CBS 12408 ^T as the type strain of this novel species. The Mycobank number of the novel species is MB 563738.     

A species specific satellite DNA family of Drosophila subsilvestris appearing predominantly in B chromosomes

This paper describes a species specific satellite DNA family (pSsP216) of Drosophila subsilvestris, a palearctic species of the D. obscura group. The pSsP216 family consists of tandemly arranged 216 bp repetitive units that are predominantly localized on B chromosomes. These chromosomes appear in variable numbers in the karyotype of this species. Some pSsP216 repeats can also be detected in the centromeric heterochromatin of the acrocentric A chromosomes. Two strains, one with and the other without B chromosomes, were investigated for sequence variability and for the location of this satellite DNA on the chromosomes. Among 16 clones of the 216 bp basic repeat unit an overall similarity of about 93% and no strain specific differences were found, indicating that the B chromosomes may have derived from the A chromosomes (probably the dots) by spontaneous amplification of the pSsP216 satellite DNA family.     

Evaluation of indigenous bacterial strains for biocontrol of the frogeye leaf spot of soya bean caused by Cercospora sojina

Aims: Assessment of biological control of Cercospora sojina, causal agent of frogeye leaf spot (FLS) of soya bean, using three indigenous bacterial strains, BNM297 (Pseudomonas fluorescens), BNM340 and BNM122 (Bacillus amyloliquefaciens). Methods and Results: From cultures of each bacterial strain, cell suspensions and cell‐free supernatants were obtained and assayed to determine their antifungal activity against C. sojina. Both mycelial growth and spore germination in vitro were more strongly inhibited by bacterial cell suspensions than by cell‐free supernatants. The Bacillus strains BNM122 and BNM340 inhibited the fungal growth to a similar degree (I～52–53%), while cells from P. fluorescens BNM297 caused a lesser reduction (I～32–34%) in the fungus colony diameter. The foliar application of the two Bacillus strains on soya bean seedlings, under greenhouse conditions, significantly reduced the disease severity with respect to control soya bean seedlings and those sprayed with BNM297. This last bacterial strain was not effective in controlling FLS in vivo. Conclusions: Our data demonstrate that the application of antagonistic bacteria may be a promising and environmentally friendly alternative to control the FLS of soya bean. Significance and Impact of the Study: To our knowledge, this is the first report of biological control of C. sojina by using native Bacillus strains.     

Formation of resting forms of arthrobacter globiformis in autolyzing cell suspensions

Under conditions of the spontaneous or induced autolysis of thick cell suspensions,Arthrobacter globiformis strains produced cells exhibiting features typical of resting microbial forms. The number of viable resting cells was greater under conditions of induced rather than spontaneous autolysis. The thermoresistance of the resting cells of A.globiformis strains isolated from 2-to 3 million-year-old permafrost was higher than that of the collectionA. globiformis strain.     

Chromosomal mapping of host resistance loci to Trichinella spiralis nematode infection in rats

The differences in host response among strains of rats to intestinal nematode parasite Trichinella spiralis infection could provide a powerful benefit for further elucidation of molecular interactions between the host and the parasite. Using several strains of rats, we previously observed that DA strain is a strong responder and F344 strain is a weak responder with respect to expulsion of the adult worm. To identify the host resistance loci, quantitative trait loci (QTLs) analysis in F2 population from crosses between DA and F344 strains was performed. One significant QTL (designated as Tspe) was mapped to the middle region of chromosome 9. In addition, the effect of DA allele at Tspe locus could act recessively and lead to the rejection of more adult worms from the gut. The results from the present study provide more insights on host–parasite interactions, which may be useful in facilitating the development of novel approaches for treatment and control of intestinal parasites in human and domestic livestock.     

Cold-adapted yeasts from Antarctica and the Italian Alps—description of three novel species: Mrakia robertii sp. nov., Mrakia blollopis sp. nov. and Mrakiella niccombsii sp. nov.

Worldwide glaciers are annually retreating due to global overheating and this phenomenon determines the potential lost of microbial diversity represented by psychrophilic microbial population sharing these peculiar habitats. In this context, yeast strains, all unable to grow above 20°C, consisting of 42 strains from Antarctic soil and 14 strains isolated from Alpine Glacier, were isolated and grouped together based on similar morphological and physiological characteristics. Sequences of the D1/D2 and ITS regions of the ribosomal DNA confirmed the previous analyses and demonstrated that the strains belong to unknown species. Three new species are proposed: Mrakia robertii sp. nov. (type strain CBS 8912), Mrakia blollopis sp. nov. (type strain CBS 8921) and a related anamorphic species Mrakiella niccombsii sp. nov. (type strain CBS 8917). Phylogenetic analysis of the ITS region revealed that the new proposed species were closely related to each other within the Mrakia clade in the order Cystofilobasidiales, class Tremellomycetes. The Mrakia clade now contains 8 sub-clades. Teliospores were observed in all strains except CBS 8918 and for the Mrakiella niccombsii strains.     

Linear alkanesulfonates as carbon and energy sources for gram-positive and gram-negative bacteria

Several bacteria from soil and rainwater samples were enriched and isolated with propanesulfonate or butanesulfonate as sole carbon and energy source. Most of the strains isolated utilized nonsubstituted alkanesulfonates with a chain length of C3–C6 and the substituted sulfonates taurine and isethionate as carbon and energy source. A gram-positive isolate, P40, and a gram-negative isolate, P53, were characterized in more detail. Phylogenetic analysis grouped strain P40 within group IV of the genus Rhodococcus and showed a close relationship with Rhodococcus opacus. After phylogenetic and physiological analyses, strain P53 was identified as Comamonas acidovorans. Both bacteria also utilized a wide range of sulfonates as sulfur source. Strain P40, but not strain P53, released sulfite into the medium during dissimilation of sulfonated compounds. Cell-free extracts of strain P53 exhibited high sulfite oxidase activity [2.34 U (mg protein)^–1] when assayed with ferricyanide, but not with cytochrome c. Experiments with whole-cell suspensions of both strains showed that the ability to dissimilate 1-propanesulfonate was specifically induced during growth on this substrate and was not present in cells grown on propanol, isethionate or taurine. Whole-cell suspensions of both strains accumulated acetone when oxidizing the non-growth substrate 2-propanesulfonate. Strain P40 cells also accumulated sulfite under these conditions. Stoichiometric measurements with 2-propanesulfonate as substrate in oxygen electrode experiments indicate that the nonsubstituted alkanesulfonates were degraded by a monooxygenase. When strain P53 grew with nonsubstituted alkanesulfonates as carbon and energy source, cells expressed high amounts of yellow pigments, supporting the proposition that an oxygenase containing iron sulfur centres or flavins was involved in their degradation. Received: 21 December 1998 / Accepted: 18 March 1999     

The production of two Th2 cytokines, interleukin-4 and interleukin-10, is controlled independently by locus Cypr1 and by loci Cypr2 and Cypr3, respectively

 The strains BALB/cHeA (BALB/c) and STS/A (STS) differ in production of IL-4 and IL-10, two Th2 cytokines, after stimulation of spleen cells with Concanavalin A, STS being a low and BALB/c a high producer. We analyzed the genetic basis of this strain difference using the recombinant congenic (RC) strains of the BALB/c-c-STS/Dem (CcS/Dem) series. This series comprises 20 homozygous strains. Each CcS/Dem strain contains a different, random set of approximately 12.5% genes of the "donor" strain STS and approximately 87.5% of the "background" strain BALB/c. We selected for further analysis the RC strain production intermediate between BALB/c and STS. In (CcS-20×BALB/c)F₂ hybrids we found that different loci control expression of IL-4 and IL-10. Cypr1 (cytokine production 1) on chromosome 16 near D16Mit15 controls IL-4 production, whereas the production of IL-10 is influenced by loci Cypr2 near D1Mit14 and D1Mit227 on chromosome 1 and Cypr3 marked by D5Mit20 on chromosome 5. In addition, the relationship between the level of these two cytokines depends on the genotype of the F₂ hybrids at a locus cora1 (correlation 1) on chromosome 5. This differential genetic regulation may be relevant for the understanding of biological effects of T-helper cells in mice of different genotypes. Received: 2 March 1998 / Revised: 8 June 1998     

Antigenic relationship betweenHaemophilus influenzae andHaemophilus isolated from porcine pleuropneumonia

Comparative double immunodiffusion techniques were used to study capsular and O antigenic relationships betweenHaemophilus influenzae types a-fandH. pleuropneumoniae types 1–5 and a strain (202) closely related toH. pleuropneumoniae. Culture fluids or culture supernatants were used as antigens and rabbit antisera were produced against cell suspensions of the strains tested. A reaction of identity was obtained between the capsular precipitate ofH. influenzae c and a precipitate formed by strain 202, when developed with anti-H. influenzae c serum or the serum produced against strain 202. Mutual cross-absorption of capsular antibodies was also demonstrable. No other capsular or O antigenic cross-reactivity was demonstrable between the strains tested.     

Ultrastructural and chemotaxonomic analysis of a xylanolytic strain of Cryptococcus adeliensis isolated from sheep droppings in Spain

Cryptococcus adeliensis was initially described as a psycrophilic species containing a single strain CBS 8351^T isolated from decayed algae in Terre Adelie (Antartida). Later, a second strain of this species was isolated from an immunosuppressed patient affected by leukaemia in Germany and recently several strains from this species have been found in human patients and pigeon droppings of the same country. In this study, we isolated from sheep droppings in Spain a xylanolytic strain named LEVX01 that was phenotypically related to the strain CBS 8351^T and showed a 100% similarity in the D1/D2 domain and 5.8S-ITS region sequences with respect to the remaining described strains of C. adeliensis. These findings suggest that this species has a wide geographical distribution and that the animal faeces are a common habitat for C. adeliensis. The chemotaxonomic analyses showed the absence of detectable amounts of xylose in the cell walls of the strains LEVX01 and CBS8351^T in contrast to other Cryptococcus species. Interestingly, the ultrastructural study showed the presence of fimbriae in these two strains that could be involved in the attachment to the host cells and, as occurs in Candida albicans, they could also be a pathogenicity factor for the man.