Some Observations on Infection of Arachis hypogaea L. by Rhizobium

The infection process in Arachis hypogaea by rhizobia differsfrom that normally found in Trifolium spp. in that no infectionthreads are formed. The root hairs, which are long (up to 4mm), septate, and often with large basal cells, occur only atthe sites of emerging lateral roots. Infection occurs only wherethe root hairs have large basal cells. Rhizobia cause curlingand deformation of the root hairs (as in Trifolium spp.) butenter the root at the junction of the root hair and the epidermaland cortical cells. The bacteria are distributed intercellularlyvia the middle lamellae and enter the cortical cells throughthe structurally altered cell wall, often close to the hostcell nucleus. The root hairs and large basal cells become infectedin the same way. Within the cortical cells of the emerging lateralroot the rhizobia multiply rapidly and the invaded cells dividerepeatedly to form the nodule tissue. Bacteriod formation occursonly when the host cell ceases to divide.     

Identification and characterization of eight microsatellite loci in Aster amellus L. (Asteraceae)

Eight polymorphic microsatellites were developed in the perennial herbaceous Aster amellus L. (Asteraceae) and characterized on three populations from France and Switzerland. The number of alleles ranged between four and 30 depending on the locus, and the mean number of effective alleles was 5.8. The average gene diversity equalled 0.744 (range: 0.419–0.957) and the overall differentiation was found significant (θ = 0.092, P < 0.01). Three loci displayed significant heterozygote deficiencies, which might indicate the presence of null alleles. Amplifications were detected on eight loci in Aster alpinus L.     

A COMPARISON STUDY BETWEEN OXYRASE ANAEROBIC AGAR PLATES AND CONVENTIONAL ANAEROBIC CHAMBER FOR THE ISOLATION AND IDENTIFICATION OF ANAEROBIC BACTERIA FROM CLINICAL INFECTIONS

Misplaced confidence in the broad-spectrum antibiotics, increased resistance among previously predictable anaerobic antibiograms, and the push to maximize productivity of available space and downsizing trends has created a need for a simplified cost-effective, and superior method for the isolation and identification of anaerobic bacteria. In this study, the Oxyrase anaerobic plate system which requires no extraneous apparatus to create an anaerobic environment was compared to an anaerobic chamber in the isolation of anaerobic bacteria from 212 consecutive wound specimens. Brucella blood agar and KVL agar plates were used in this comparison study. RapID ANA II, AP120A, special potency disks, and GLC were used for identification. Of the 212 specimens cultured, 87 yielded anaerobic bacteria comprising 182 strains. Thirty-nine strains failed to grow in the anaerobic chamber but grew on the OxyPlates^(TM). These strains were predominantly Peptostreptococcus species (28%), Eubacterium species (20%), and Propionibacterium species (20%). Fourteen strains failed to grow on the OxyPlates, but grew in the anaerobic chamber. No trend was noted and all organisms in this category grew on the OxyPlates from other specimens. In conclusion, the Oxyrases anaerobic plate system appears to be an excellent alternative to the conventional anaerobic chamber in the isolation and identification of clinically significant anaerobes found in human samples, obviating the need for separate anaerobic-aerobic workstations, expensive anaerobic apparatus, and additional incubator space.     

Fine Structure of Trypanosoma cyclops in Noncellular Cultures*

The fine structure of the epimastigotes of Trypanosoma cyclops maintained in blood agar medium at 25 C is described. This organism was isolated from the Malaysian primates Macaca nemestrina and Macaca ira. A distinctive feature of T. cyclops is that it is pigmented when grown in the presence of hemoglobin. The pigment bodies apparently lack a substructure and are electron dense even in unstained sections. Most of the pigment is located posterior to the kinetoplast region but some is found adjacent and anterior to the kinetoplast. Cells from control cultures grown in medium lacking hemoglobin did not possess this type of pigment body. Similarly, pigment was not found in cells of an Indonesian trypanosome grown in medium containing hemoglobin. The cytoplasm of T. cyclops is bounded by a unit membrane which is specialized where it makes contact with the flagellum. A cytostome extends from the region of the flagellar pocket. The kinetoplast and nucleus are immediately posterior to the base of the flagellum. Transverse sections in the region of the flagellar pocket and flagellar base often reveal a group of 3 microtubules which are distinct from the pellicular microtubules.     

The Use of Analysis of Variance to Examine the Variations between Samples of Marine Bacterial Populations

Studies were made of the variations in the numbers of viable bacteria in Cardigan Bay seawater as estimated using the spread-plate technique and various marine agar media, the results being examined using analysis of variance. Use of duplicated 500 ml sample bottles enabled the detection of statistically significant variations between samples both in terms of numbers of viable bacteria present and their different responses to different counting media, but an important micro-distribution was also indicated. Further studies showed large differences between 25 ml samples taken 10 cm apart: these could not be explained in terms of cell aggregation as presently understood.