Chloroplast DNA polymorphism in fertile and male-sterile cytoplasms of sorghum (Sorghum bicolor (L.) Moench)

Summary Restriction endonuclease patterns of chloroplast DNA (cpDNA) were consistently distinguishable between fertile and male-sterile cytoplasms of sorghum [Sorghum bicolor (L.) Moench], whereas no differences in restriction patterns of cpDNA among male-sterile (A₁) lines, including six isocytoplasmic strains, were revealed in this study. It is suggested that chloroplast DNA may contribute to the male sterility of A₁ lines used currently in hybrid sorghum production.This research was supported by a research grant from Kansas Grain Sorghum Commission, Kansas Board of Agriculture. Contribution 90-293-J from the Kansas Agricultural Experiment Station     

Restriction fragment patterns of chloroplast and mitochondrial DNA of Dasypyvum villosum (L.) candargy and wheats

To elucidate the phylogenetic relationships and cytoplasmic types, restriction endonuclease fragment patterns of chloroplast (cp) and mitochondrial (mt) DNAs isolated from two different accessions of Dasypyrum villosum (L.) candargy were compared with those of tetraploid wheat (Triticum durum Desf., PI265007), hexaploid wheat (Triticum aestivum L., cv Chinese Spring), Aegilops longissimum (S. and M., in Muschli) Bowden and Hordeum vulgare L. T. aestivum and T. durum had identical restriction patterns for their cp and mtDNAs in digestions with four different enzymes. Likewise, no differences were found between the restriction fragment patterns of two accessions of D. villosum. But, there were distinct differences in chloroplast and mitochondrial DNA restriction fragment patterns between D. villosum and tetraploid and hexaploid wheats. A. longissimum (G609) showed a similar pattern to those wheats for PstI digestion of cpDNA. Organellar DNA from Hordeum vulgare (cv Himalaya) showed a distinctly different restriction pattern from those of wheat and D. villosum. These results suggest that D. villosum is unlikely to be the donor of cytoplasm to wheats, and its cytoplasmic organelles were also different from those of A. longissimum.Contribution No. 92-522-J from the Kansas Agricultural Experiment Station; Kansas State University, Manhattan, Kansas, USA     

C-banding variation in the Moroccan oat species Avena agadiriana (2n=4x=28)

The C-banding technique was used to describe the chromosomes of a relatively recently-discovered Moroccan oat species, Avena agadiriana (2n=4x=28). A substantial amount of polymorphism for arm ratios and C-banding patterns was observed among five accessions of this species. However a common set of ten putatively homologous chromosomes was identifiable among the five accessions. The chromosomes of A. Agadiriana do not closely match those of any of the previously described diploid or tetraploid oat species in terms of their arm ratios and C-banding patterns. However, their overall C-banded appearance generally resembles the A/B/D groups of chromosomes of Avena species, rather than the more hetrochromatic C genomes. Implications of these findings in terms of chromosome evolution in the genus Avena are discussed.Contribution no. 95-490-J of the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, KS, USA     

C-banding and in-situ hybridization analyses of Agropyron intermedium,a partial wheat x Ag. intermedium amphiploid,and six derived chromosome addition lines

Summary C-banded karyotypes of Agropyron intermedium (2n=6x=42, E₁E₂X), a partial amphiploid Triticum aestivum —Ag. intermedium (2n=8x=56, TAF46), and six derived chromosome addition lines, were analyzed. In Ag. intermedium, diagnostic C-bands were present on 14 pairs of chromosomes, designated from A to N, while the remaining seven pairs, designated O to U, either lacked, or had only faint, C-bands and were not always identified unambiguously. All seven Ag. intermedium chromosome pairs of the partial amphiploid TAF46, and the added Ag. intermedium chromosomes present in the six derived addition lines, were identified by their characteristic C-banding patterns. Chromosome morphology and banding patterns were similar to those of the corresponding chromosomes present in the parent Ag. intermedium accession, suggesting that these chromosomes were not structurally rearranged. In-situ hybridization, using a 18s.265s rDNA probe, showed that the Ag. intermedium chromosomes 1Ai-1 and 5Ai-l present in the addition lines L3 and L5 were carrying actively transcribed nucleolus organizer regions. The results are discussed with respect to the genomic relationships of these chromosomes.Contribution no. 91-561-J from the Wheat Genetics Resource Center and Kansas Agricultural Experiment Station, Kansas State University, Manhatten, USA     

Phylogenetic analysis of Sorghum and related taxa using internal transcribed spacers of nuclear ribosomal DNA

The phylogenetic relationships of the genus Sorghum and related genera were studied by sequencing the nuclear ribosomal DNA (rDNA) internal transcribed spacer region (ITS). DNA was extracted from 15 Sorghum accessions, including one accession from each of the sections Chaetosorghum and Heterosorghum, four accessions from Parasorghum, two accessions from Stiposorghum, and seven representatives from three species of the section Sorghum (one accession from each of S. propinquum and S. halepense, and five races of S. bicolor). The maize (Zea mays) line, H95, and an accession from Cleistachne sorghoides were also included in the study. Variable nucleotides were used to construct a strict consensus phylogenetic tree. The analyses indicate that S. propinquum, S. halepense and S. bicolor subsp. arundinaceum race aethiopicum may be the closest wild relatives of cultivated sorghum; Sorghum nitidum may be the closest 2n=10 relative to S. bicolor, the sections Chaetosorghum and Heterosorghum appear closely related to each other and more closely related to the section Sorghum than Parasorghum; and the section Parasorghum is not monophyletic. The results also indicate that the genus Sorghum is a very ancient and diverse group.This research was partially supported by a Third Country Scholarship from Pioneer Hi-Bred International Incorporated Contribution 94-182-J from Kansas Agricultural Experiment Station     

Standard karyotype of Triticum searsii and its relationship with other S-genome species and common wheat

C-banding polymorphism was analyzed in 14 accessions of Triticum searsii from Israel, and a generalized idiogram of the species was established. One accession was homozygous for whole arm translocations T1S^sS·4S^sS and T1S^sL·4S^sL. C-banding analysis was also used to identify 7 T. aestivum cv Chinese Spring-T. searsii disomic chromosome addition lines, 14 ditelosomic chromosome addition lines, 21 disomic whole chromosome, and 31 ditelosomic chromosome substitution lines. The identity of these lines was further confirmed by meiotic pairing analysis. Sporophytic and gametophytic compensation tests were used to determine the homoeologous relationships of the T. searsii chromosomes. The results show that the T. searsii chromosomes do not compensate well for their wheat homoeologues. The C-banding patterns of T. searsii chromosomes are distinct from those of other S-genome species and from the B-genome chromosomes of wheat, indicating that T. searsii is not a direct B-genome donor species of T. turgidum and T. aestivum.Contribution No. 95-72-J from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, Kansas, USA     

A unique cytoplasmic male sterility (CMS) determinant is present in three Phaseolus species characterized by different mitochondrial genomes

Previous results have shown that cytoplasmic male sterility (CMS) in lines from Phaseolus coccineus and Phaseolus vulgaris contain the same CMS-specific sequence, raising the question of whether this sequence rearrangement arose before divergence of the two species or afterward with subsequent transfer by introgression. Hybridization patterns of total DNA from eight P. vulgaris lines with cytoplasm from P. coccineus and three P. vulgaris lines were examined in order to analyze the mitochondrial DNA (mtDNA) diversity within each species and to determine differences between CMS lines derived from the two species. Three restriction enzymes and 17 heterologous mtDNA sequences were used. The analysis of the different hybridization patterns revealed a considerable diversity in mtDNA organization particularly within P. coccineus. We obtained distinctive hybridization patterns for the five CMS lines tested. The resulting classification showed that mitochondrial genomes from P. coccineus CMS lines group with those of fertile P. coccineus but not with CMS lines from P. vulgaris. The groupings concur with the taxonomic classification of these lines. The results support the hypothesis of a single ancient origin of the CMS determinant and exclude the transfer of cytoplasm by introgression from P. vulgaris to P. coccineus and P. coccineus ssp polyanthus.     

Correction of chlorophyll-defective male-sterile winter oilseed rape (Brassica napus) through organelle exchange: molecular analysis of the cytoplasm of parental lines and corrected progeny

Summary Cytoplasmic differences between male-fertile and male-sterile Brassica napus as well as Raphanus sativus were investigated. Plastids of the male-fertile B. napus were found to differ from those of male-sterile B. napus and R. sativus with respect to DNA restriction enzyme patterns. Differences between male-fertile and male-sterile B. napus mitochondria were detected not only in the restriction fragment patterns of their DNA, but also at the level of expression by in organello translation of mitochondrial polypeptides.The chlorophyll deficiency obtained upon transferral of the male-sterility-conferring radish cytoplasm to a winter variety of B. napus had been corrected earlier through protoplast fusion. The cytoplasmic composition of the corrected lines was analysed using DNA restriction analysis and in organello translation. The stability of the recombined cytoplasm in the corrected lines was confirmed by analysis of the subsequent seed-derived generation.     

Mitochondrial DNA variation in maize plants regenerated during tissue culture selection

Summary Plants resistant to Helminthosporium maydis race T were obtained following selection for H. maydis pathotoxin resistance in tissue cultures of susceptible, Texas male-sterile (T) cytoplasm maize. The selected lines transmitted H. maydis resistance to their sexual progeny as an extranuclear trait. Of 167 resistant, regenerated plants, 97 were male fertile and 70 were classified male sterile for reasons that included abnormal plant, tassel, anther or pollen development. No progeny were obtained from these male-sterile, resistant plants. Male fertility and resistance to the Phyllosticta maydis pathotoxin that specifically affects T cytoplasm maize were co-transmitted with H. maydis resistance to progeny of male-fertile, resistant plants. These three traits previously were associated only with the normal (N) male-fertile cytoplasm condition in maize. Three generations of progeny testing provided no indication that the cytoplasmic association of male sterility and toxin susceptibility had been broken by this selection and regeneration procedure. Restriction endonuclease analysis of mitochondrial DNA (mtDNA) revealed that three selected, resistant lines had distinct mtDNA organization that distinguished them from each other, from T and from N cytoplasm maize. Restriction patterns of the selected resistant lines were similar to those from T cytoplasm mtDNA; these patterns had not been observed in any previous analyses of various sources of T cytoplasm. The mtDNA analyses indicated that the male-fertile, toxin-resistant lines did not originate from selection of N mitochondrial genomes coexisting previously with T genomes in the T cytoplasm line used for selection.Scientific Journal Series Article no. 11,185 of the Minnesota Agricultural Experiment Station and no. 2295 of the Florida Agricultural Experiment Station. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee of warrantly of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable     

Standard karyotype of Triticum umbellulatum and the characterization of derived chromosome addition and translocation lines in common wheat

A standard karyotype and a generalized idiogram of Triticum umbellulatum (syn. Aegilops umbellulata, 2n = 2x = 14) was established based on C-banding analysis of ten accessions of different geographic origin and individual T. umbellulatum chromosomes in T. aestivum — T. umbellulatum chromosome addition lines. Monosomic (MA) and disomic (DA) T. aestivum — T. umbellulatum chromosome addition lines (DA1U = B, DA2U = D, MA4U = F, DA5U = C, DA6U = A, DA7U = E = G) and telosomic addition lines (DA1US, DA1UL, DA2US, DA2UL, DA4UL, MA5US, (+ iso 5US), DA5UL, DA7US, DA7UL) were analyzed. Line H was established as a disomic addition line for the translocated wheat — T. umbellulatum chromosome T2DS·4US. Radiation-induced wheat — T. umbellulatum translocation lines resistant to leaf rust (Lr9) were identified as T40 = T6BL·6BS-6UL, T41 = T4BL·4BS-6UL, T44 = T2DS·2DL-6UL, T47 = Transfer = T6BS·6BL-6UL and T52 = T7BL·7BS-6UL. Breakpoints and sizes of the transferred T. umbellulatum segments in these translocations were determined by in situ hybridization analysis using total genomic T. umbellulatum DNA as a probeContribution no. 94-349-J from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, KS 66506-5502, USA     

Regulation of internodal lenght by peroxidase enzymes in grain sorghum

Summary A relationship between height genes (dw locus) and perioxidase was demonstrated by extracting and determining peroxidase specific activity in internode tissue from different height isogenic lines of sorghum Sorghum bicolor (L.) Moench]. Tall plants (2 dwarf) had less peroxidase per gram tissue than their short counterparts (3 dwarf); their F₁ offspring internodes were closer but had more peroxidase than the tall parent. Peroxidase in the F₂ offspring was inversely related to their height and followed a simply-inherited pattern similar to that for height.Among different tissues analyzed, peroxidase concentration in roots was higher than in leaves and internodes, whole internode higher than in pith, and seed embryo higher than in endosperm. Peroxidase activity of nonviable seeds was negligible.Isoelectric focusing provided a more detailed peroxidase zymogram than did gel electrophoresis. Differences in peroxidase bands among tall and short parental plants, F₁ and F₂ segregating groups all appear to be reflected by intensity differences rather than by position or number of bands.Activities of nitrate reductase and acid phosphatase did not correlate with height. That finding provides a control and suggests that peroxidase activity is not associated with height by chance but may have a functional relationship.Contribution no. 1628-j, Dept. of Agronomy and no. 188-j, Dept. of Biochemistry, and no. 962-j, Dept. of Grain Science and Industry, Kansas State University, Kansas Agricultural Experiment Station, Manhattan, Kansas 66506.     

Characterization of <Emphasis Type="Italic">Streptococcus mutans</Emphasis> diversity by determining restriction fragment-length polymorphisms of the <Emphasis Type="Italic">gtfB</Emphasis> gene of isolates from 5-year-old children and their mothers

The diversity between Streptococcus mutans clinical isolates from 5-year-old children and their mothers in two South African ethnic groups was investigated. The gtfB gene encoding for glucosyltransferase (EC 2.4.1.5), an enzyme responsible for the synthesis of extracellular polysaccharides was characterized by PCR-RFLP with HaeIII restriction enzyme digestion. Forty-seven children were examined for dental caries and 128 S. mutans clinical isolates cultured from samples of their saliva and plaque and from the saliva of their mothers. Thirty-three children had active caries (70%) and the remainder (n = 14) were caries-free. Caries prevalence was significantly different (p = 0.02) between black African and coloured children, but no differences were found between gtfB amplitypes by caries or ethnic grouping. Thirty-four (27%) of the S. mutans clinical isolates investigated did not ferment melibiose. Melibiose-negative phenotypes (n = 10) isolated from four families showed gtfB RFLP patterns identical to each other. Mothers and children harboured between one and three amplitypes. GtfB amplitypes were identical in 17 families (17/47), of which nine only were identical to S. mutans reference strains. The percentage match between S. mutans amplitype from mothers and their children was low (13%) in the caries-free group compared to children with caries (44%). RFLP analysis of the gtfB gene showed the diversity of S. mutans genotypes within two South African populations that were acquired from mothers and other sources.     

Mineral allocation to reproduction in Sorhum bicolor and Sorghum halepense in relation to parental nutrient supply

Summary This experiment investigated the effect of parental nutrient shortage on the allocation of five nutrients to seeds and rhizomes in Sorghum halepense, a perennial, noxious weed, and to seeds in Sorghum bicolor, an annual, cultivated species. Plants from both species were grown from seeds and supplied with fertilizer at three concentrations. The allocation of biomass and nutrients (N, P, K, Ca and Mg) to reproductive and vegetative parts was determined. Relative biomass allocation to reproduction (either sexual or vegetative) remained constant in S. halepense in spite of large differences in total plant weight. In S. bicolor, however, biomass allocation to sexual reproductive structures decreased significantly with decreasing nutrient supply. Individual seed weight was not modified by parental nutrient supply in S. halepense, but it increased with decreasing nutrient availability in S. bicolor. Important differences in mineral allocation to seeds were found between the two species. While S. bicolor seeds were largely buffered from the differences in parental nutrient status, concentration of nutrients in S. halepense seeds decreased significantly with decreasing supply for all the nutrients analyzed except Ca. However, mineral nutrient concentration in S. halepense rhizomes remained remarkably constant despite differences in the external supply, evincing the priority given to vegetative reproduction at the expense of sexual reproduction. Overall, the pattern of nutrient allocation in S. bicolor seeds under different nutrient supply resembled the pattern observed in S. halepense rhizomes, but it had little resemblance to the pattern of nutrient allocation in S. halepense seeds. The results are discussed in terms of differences and similarities in the reproductive strategy of these two species.     

Genotyping of Trichophyton rubrum by analysis of ribosomal-DNA intergenic spacer regions

An attempt was made to explore the genotyping of Trichophyton rubrum (T. rubrum) and the relationship between genotype and geographical origin using ribosomal restriction endonuclease polymorphic analysis. The total DNA was extracted by cetyltrimethyl ammonium bromide (CTAB). The probe was amplified from part of the 18S, ITSI, 5.8S, and ITSII region of T. rubrum standard strain with the universal fungal primers NS5 [5′-AACTT AAAGG AATTG ACGGA AG-3′] and ITS4 [5′-TCCTC CGCTT ATTGA TATGC-3′]. The genomic DNA of 49 clinical T. rubrum isolates digested by EcoR1 were hybridized with this probe, and the hybridization patterns were used as the basis of genotyping. Of the data from 49 strains of T. rubrum studied (21 from Nanjing, 26 from Dalian, and two from Beijing), 20 individual patterns (DNA Type A–T) were identified, among which Type A–C accounted for 48.98% of all the strains. The DNA patterns of Nanjing strains were represented by three bands, those of Dalian strains were represented by four bands. The DNA typing of T. rubrum by Southern blotting was highly sensitive and highly distinguishable. The DNA patterns of Nanjing strains were obviously different from those of Dalian strains.     

RFLP analysis of the ribosomal internal transcribed spacers and the 5.8S rRNA gene region of the genus Saccharomyces: a fast method for species identification and the differentiation of flor yeasts

The PCR amplification and subsequent restriction analysis of the region spanning the internal transcribed spacers (ITS1 and ITS2) and the 5.8S rRNA gene was applied to the identification of yeasts belonging to the genus Saccharomyces. This methodology has previously been used for the identification of some species of this genus, but in the present work, this application was extended to the identification of new accepted Saccharomyces species (S. kunashirensis, S. martiniae, S. rosinii, S. spencerorum, and S. transvaalensis), as well as to the differentiation of an interesting group of Saccharomyces cerevisiae strains, known as flor yeasts, which are responsible for ageing sherry wine. Among the species of the Saccharomyces sensu lato complex, the high diversity observed, either in the length of the amplified region (ranged between 700 and 875 bp) or in their restriction patterns allows the unequivocal identification of these species. With respect to the four sibling species of the Saccharomyces sensu stricto complex, only two of them, S. bayanus and S. pastorianus, cannot be differentiated according to their restriction patterns, which is in accordance with the hybrid origin (S. bayanus × S. cerevisiae) of S. pastorianus. The flor S. cerevisiae strains exhibited restriction patterns different from those typical of the species S. cerevisiae. These differences can easily be used to differentiate this interesting group of strains. We demonstrate that the specific patterns exhibited by flor yeasts are due to the presence of a 24-bp deletion located in the ITS1 region and that this could have originated as a consequence of a slipped-strand mispairing during replication or be due to an unequal crossing-over. A subsequent restriction analysis of this region from more than 150 flor strains indicated that this deletion is fixed in flor yeast populations.     

接种AMF对煤矿废弃物上高丹草的生长和叶绿素荧光的影响

为改善采矿废弃物上植被生长状况,提高植物成活率,该研究采用盆栽试验法,以高丹草为材料,选用摩西球囊霉(Glomus mosseae,G.m)和地表球囊霉(G.versiforme,G.v)两种AM真菌,分别研究单接种和混合接种对粉煤灰(S1)、煤矸石(S2)和粉煤灰与煤矸石混合物(S3)三种煤矿废弃物基质上高丹草(Sorghum bicolor×S.sudanense)生长及叶绿素荧光的影响,并以正常沙土(S4)作为对照。结果表明:(1)4种基质上,3种接种处理均获得较高侵染率,在基质S1、S3和S4上均为接种摩西球囊霉对高丹草根系侵染率最高,分别为49.04%、57.40%、43.34%,在基质S2上,混合接种处理对高丹草根系侵染效果最好,达49.33%。(2)3种煤矿废弃物基质上高丹草根长、干重、叶绿素含量、F_v/F_o、q P和Yield显著降低。接种AM真菌显著提高了高丹草的生长和光合效率。与其他处理相比,在基质S1、S3和S4上,接种摩西球囊霉显著增加了根长、干重、叶绿素含量、F_v/F_o、q P和Yield,在基质S2上,接种地表球囊霉显著增加了根长、干重,接种地表球囊霉和摩西球囊霉+地表球囊霉(G.mv)处理间叶绿素荧光参数均无显著差异。这表明在煤矿废弃物基质的复合逆境中高丹草生长和光合作用显著受到抑制,AM真菌可通过提高高丹草叶绿素含量,改善叶片叶绿素荧光和光合作用,促进植物生长,来缓解该复合逆境对高丹草造成的伤害,增强其对煤矿废弃物不良环境的抗逆性,提高煤矿区植被恢复效果。接种摩西球囊霉对粉煤灰以及粉煤灰和煤矸石混合基质上高丹草的促进作用最佳,而接种地表球囊霉更适于煤矸石基质上高丹草的生长。     

Evaluation of Public Sweet Sorghum A-Lines for Use in Hybrid Production

A fundamental need for commercialization of sweet sorghum [Sorghum bicolor (L.) Moench] as a bioenergy crop is an adequate seed supply, which will require development of hybrid varieties using dwarf seed-parent lines. A set of six public sweet sorghum A-lines (Dwarf Kansas Sourless, KS9, N36, N38, N39, and N4692) were crossed with a set of six public sweet sorghum cultivars (Brawley, Kansas Collier, Dale, Sugar Drip, Waconia, and Wray). Grain, fiber, and sugar yields were determined, and conversion formulas were applied to estimate ethanol yields. Hybrids were grown in fields at Ithaca, NE, USA, in 1983–1984 fertilized with 112 kg ha^?1 N. In terms of yield components and overall ethanol yields, one A-line, N38, was inferior. Average total ethanol yields from hybrids made on the other A-lines were not significantly different, suggesting that any of those five A-lines could be useful seed-parents. With the exception of grain yield, cultivars used as pollen parents were among the highest-performing entries for all traits. For all traits directly contributing to total ethanol yield (grain yield, juice yield, % soluble solids, sugar yield, fiber yield), hybrids were also among the highest-performing entries. Results of this study demonstrate that hybrid sweet sorghum with performance criteria equivalent to existing sweet sorghum cultivars can be produced on the sweet sorghum seed-parent lines A-Dwarf Kansas Sourless, A-KS9, A-N36, A-N39, and A-N4692. Identification of specific seed-parent × pollen parent lines with characteristics best suited for particular growing regions and end-user needs will be critical for commercial hybrid development.     

Phenotypic and genotypic diversity among strains of <Emphasis Type="Italic">Aureobasidium pullulans</Emphasis> in comparison with related species

Intra-specific diversity of 200 Aureobasidium pullulans strains isolated from different sources and their relatives Kabatiella lini CBS 125.21 T and Hormonema prunorum CBS 933.72 T were studied by assessment of macromorphological, and physiological tests, sodium dodecyl sulfate-polyacrylamide gel electrophoresis technique (SDS–PAGE) of whole-cell proteins as well as enterobacterial repetitive intergenic consensus (ERIC)-, repetitive extragenic palindromic (REP)- and BOX-PCR techniques (collectively known as rep-PCR). Rep-PCR is an efficient procedure for discrimination of A. pullulans in terms of simplicity and rapidity. RFLP-PCR technique was applied for the identification of A. pullulans isolates and distinction from related species. This technique was insufficient for investigation of intra-specific diversity. The tested strains of A. pullulans could be divided into two groups based on their macromorphological, protein patterns obtained after SDS-PAGE as well as rep-PCR patterns. The first group of strains shared similar characteristics and was very different from the second one, designated as “complex group”, consisting of strains with very little similarities within the group. Phenetic analysis of ERIC banding patterns failed to group the isolates on the basis of their substrate or geographical origin. Using 18S rDNA gene sequence analysis of selected isolates, three strains: HoHe3 km, A. pullulans DSM 62074 and H. prunorum CBS 933.72 T were distinguished from all other analysed members of genera Aureobasidium and Kabatiella. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Aggregation of 27 oral bacteria by human whole saliva

Twenty-seven oral strains of the genera Actinomyces (5), Bacteroides (3), and Streptococcus (19) were tested for aggregation by human whole saliva, as well as the effect of culture medium, Ca-ions, and bacteria concentration thereupon. Of the media tested, GF-broth gave rise to less interference by autoaggregation or higher aggregation titers than BHI and TSB, and was used throughout this study. In most cases, Ca-ions (1 mM) only enhanced the rate of induced aggregation, whereas raising the bacteria concentration increased the rate of both induce- and autoaggregation. The final titers, ranging from 1–64, were hardly affected by these parameters, except those of S. rattus HG 59 and S. mutans HG 199, which were respectively increased and decreased by Ca-ions. Saliva-induced aggregation was observed for 21 strains of A. viscosus, A. naeslundii, A. israelii, B. gingivalis, B. intermedius, S. cricetus, S. mutans, S. rattus, S. sanguis, and S. sobrinus, mostly within 15 min to 3 h. Seventeen of these strains also showed autoaggregation, usually well after the onset of induced aggregation. Any potential induced aggregation of B. gingivalis HG 91 was always masked by autoaggregation, as well as that of the S. mutans strains under a particular set of conditions. The aggregation rate and titer varied considerably in a mutually unrelated and strain-dependent way. These microtiterplate data were matched by the 5 spectrophotometric patterns observed for saliva-bacterial interaction, which moreover, gave the better differentiation between induced and autoaggregation. In conclusion, most strains tested can show rapid saliva-induced aggregation in a strain-dependent way, yet strongly affected by the experimental conditions and interference from autoaggregation.     

Genetic studies on reference strains of mutans streptococci

Twenty four reference strains (serotype a-h) belonging to the mutans group of streptococci were compared for DNA fragment patterns of rDNA after treatment with Hind III. It was shown that Streptococcus cricetus (serotype a), S. rattus (serotype b), and S. downei (serotype h) reveals comparatively homogeneous patterns while S. mutans (serotype c, e and f) exhibits differences between the different serotypes as well as within single serotypes. S. sobrinus had an intermediary diversity. These data support the previous findings that S. mutans is heterogeneous at the serological, biochemical and genetical level.